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# THIS FILE IS AUTOMATICALLY GENERATED BY CARGO
#
# When uploading crates to the registry Cargo will automatically
# "normalize" Cargo.toml files for maximal compatibility
# with all versions of Cargo and also rewrite `path` dependencies
# to registry (e.g., crates.io) dependencies
#
# If you believe there's an error in this file please file an
# issue against the rust-lang/cargo repository. If you're
# editing this file be aware that the upstream Cargo.toml
# will likely look very different (and much more reasonable)
[package]
name = "core_io"
version = "0.1.20210325"
authors = ["The Rust Project Developers", "Jethro Beekman"]
build = "build.rs"
include = ["build.rs", "Cargo.toml", "LICENSE-*", "mapping.rs", "src/**/*.rs"]
description = "This is a copy of libstd::io with all the parts that don't work in core removed.\nMost importantly, it provides the Read and Write traits.\n\nThis crate is (mostly) automatically generated from the rust git source. The\nversion of the source that corresponds to your compiler version will be\nselected automatically by the build script.\n"
documentation = "https://doc.rust-lang.org/nightly/std/io/index.html"
keywords = ["core", "no_std", "io", "read", "write"]
license = "MIT/Apache-2.0"
repository = "https://github.com/jethrogb/rust-core_io"
[build-dependencies.rustc_version]
version = "0.1.7"
[features]
alloc = []
collections = ["alloc"]

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[package]
name = "core_io"
version = "0.1.20210325"
authors = ["The Rust Project Developers", "Jethro Beekman"]
license = "MIT/Apache-2.0"
description = """
This is a copy of libstd::io with all the parts that don't work in core removed.
Most importantly, it provides the Read and Write traits.
This crate is (mostly) automatically generated from the rust git source. The
version of the source that corresponds to your compiler version will be
selected automatically by the build script.
"""
repository = "https://github.com/jethrogb/rust-core_io"
documentation = "https://doc.rust-lang.org/nightly/std/io/index.html"
keywords = ["core", "no_std", "io", "read", "write"]
include = [
"build.rs",
"Cargo.toml",
"LICENSE-*",
"mapping.rs",
"src/**/*.rs",
]
build = "build.rs"
[build-dependencies]
rustc_version = "0.1.7"
[features]
alloc = []
collections = ["alloc"]

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Copyright (c) 2014 The Rust Project Developers
Permission is hereby granted, free of charge, to any
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SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
DEALINGS IN THE SOFTWARE.

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extern crate rustc_version;
use std::env;
use std::fs::File;
use std::io::Write;
use std::path::PathBuf;
struct Mapping(&'static str,&'static str);
fn parse_mappings(mut mappings: &'static str) -> Vec<Mapping> {
// FIXME: The format used here used to be parsed directly by rustc, which
// is why it's kind of weird. It should be changed to a saner format.
const P1: &'static str = r#"-Mapping(""#;
const P2: &'static str = r#"",""#;
const P3: &'static str = "\")\n";
trait TakePrefix: Sized {
fn take_prefix(&mut self, mid: usize) -> Self;
}
impl<'a> TakePrefix for &'a str {
fn take_prefix(&mut self, mid: usize) -> Self {
let prefix = &self[..mid];
*self = &self[mid..];
prefix
}
}
let mut result = Vec::with_capacity( mappings.len() / (P1.len()+40+P2.len()+40+P3.len()) );
while mappings.len() != 0 {
match (
mappings.take_prefix(P1.len()),
mappings.take_prefix(40),
mappings.take_prefix(P2.len()),
mappings.take_prefix(40),
mappings.take_prefix(P3.len()),
) {
(P1, hash1, P2, hash2, P3) => result.push(Mapping(hash1, hash2)),
_ => panic!("Invalid input in mappings"),
}
}
result
}
type Cfg = Option<&'static str>;
type Date = &'static str;
/// A `ConditionalCfg` is basically a list of optional feature names
/// (`Cfg`s) separated by `Date`s. The dates specify ranges of compiler
/// versions for which to enable particular features.
type ConditionalCfg = (Cfg, &'static [(Date, Cfg)]);
const CONDITIONAL_CFGS: &'static [ConditionalCfg] = &[
(None, &[("2019-02-24", Some("pattern_guards"))]),
(None, &[("2018-08-14", Some("non_exhaustive"))]),
(Some("unicode"), &[("2018-08-13", None)]),
(None, &[("2018-01-01", Some("core_memchr"))]),
(None, &[("2017-06-15", Some("no_collections"))]),
(Some("rustc_unicode"), &[("2016-12-15", Some("std_unicode")), ("2017-03-03", None)]),
];
fn main() {
let ver=rustc_version::version_meta();
let io_commit=match env::var("CORE_IO_COMMIT") {
Ok(c) => c,
Err(env::VarError::NotUnicode(_)) => panic!("Invalid commit specified in CORE_IO_COMMIT"),
Err(env::VarError::NotPresent) => {
let mappings=parse_mappings(include_str!("mapping.rs"));
let compiler=ver.commit_hash.expect("Couldn't determine compiler version");
mappings.iter().find(|&&Mapping(elem,_)|elem==compiler).expect("Unknown compiler version, upgrade core_io?").1.to_owned()
}
};
for &(mut curcfg, rest) in CONDITIONAL_CFGS {
for &(date, nextcfg) in rest {
// if no commit_date is provided, assume compiler is current
if ver.commit_date.as_ref().map_or(false,|d| &**d<date) {
break;
}
curcfg = nextcfg;
}
if let Some(cfg) = curcfg {
println!("cargo:rustc-cfg={}", cfg);
}
}
let mut dest_path=PathBuf::from(env::var_os("OUT_DIR").unwrap());
dest_path.push("io.rs");
let mut f=File::create(&dest_path).unwrap();
let mut target_path=PathBuf::from(env::var_os("CARGO_MANIFEST_DIR").unwrap());
target_path.push("src");
target_path.push(io_commit);
target_path.push("mod.rs");
f.write_all(br#"#[path=""#).unwrap();
f.write_all(target_path.into_os_string().into_string().unwrap().replace("\\", "\\\\").as_bytes()).unwrap();
f.write_all(br#""] mod io;"#).unwrap();
}

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use crate::io::prelude::*;
use core::cmp;
use crate::io::{self, Initializer, SeekFrom, Error, ErrorKind, IoSlice, IoSliceMut};
#[cfg(feature="collections")] use core::convert::TryInto;
/// A `Cursor` wraps an in-memory buffer and provides it with a
/// [`Seek`] implementation.
///
/// `Cursor`s are used with in-memory buffers, anything implementing
/// `AsRef<[u8]>`, to allow them to implement [`Read`] and/or [`Write`],
/// allowing these buffers to be used anywhere you might use a reader or writer
/// that does actual I/O.
///
/// The standard library implements some I/O traits on various types which
/// are commonly used as a buffer, like `Cursor<`[`Vec`]`<u8>>` and
/// `Cursor<`[`&[u8]`][bytes]`>`.
///
/// # Examples
///
/// We may want to write bytes to a [`File`] in our production
/// code, but use an in-memory buffer in our tests. We can do this with
/// `Cursor`:
///
/// [`Seek`]: trait.Seek.html
/// [`Read`]: ../../std/io/trait.Read.html
/// [`Write`]: ../../std/io/trait.Write.html
/// [`Vec`]: ../../std/vec/struct.Vec.html
/// [bytes]: ../../std/primitive.slice.html
/// [`File`]: ../fs/struct.File.html
///
/// ```no_run
/// use std::io::prelude::*;
/// use std::io::{self, SeekFrom};
/// use std::fs::File;
///
/// // a library function we've written
/// fn write_ten_bytes_at_end<W: Write + Seek>(writer: &mut W) -> io::Result<()> {
/// writer.seek(SeekFrom::End(-10))?;
///
/// for i in 0..10 {
/// writer.write(&[i])?;
/// }
///
/// // all went well
/// Ok(())
/// }
///
/// # fn foo() -> io::Result<()> {
/// // Here's some code that uses this library function.
/// //
/// // We might want to use a BufReader here for efficiency, but let's
/// // keep this example focused.
/// let mut file = File::create("foo.txt")?;
///
/// write_ten_bytes_at_end(&mut file)?;
/// # Ok(())
/// # }
///
/// // now let's write a test
/// #[test]
/// fn test_writes_bytes() {
/// // setting up a real File is much slower than an in-memory buffer,
/// // let's use a cursor instead
/// use std::io::Cursor;
/// let mut buff = Cursor::new(vec![0; 15]);
///
/// write_ten_bytes_at_end(&mut buff).unwrap();
///
/// assert_eq!(&buff.get_ref()[5..15], &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
/// }
/// ```
#[derive(Clone, Debug, Default)]
pub struct Cursor<T> {
inner: T,
pos: u64,
}
impl<T> Cursor<T> {
/// Creates a new cursor wrapping the provided underlying in-memory buffer.
///
/// Cursor initial position is `0` even if underlying buffer (e.g., `Vec`)
/// is not empty. So writing to cursor starts with overwriting `Vec`
/// content, not with appending to it.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
/// ```
pub fn new(inner: T) -> Cursor<T> {
Cursor { pos: 0, inner: inner }
}
/// Consumes this cursor, returning the underlying value.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
///
/// let vec = buff.into_inner();
/// ```
pub fn into_inner(self) -> T { self.inner }
/// Gets a reference to the underlying value in this cursor.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
///
/// let reference = buff.get_ref();
/// ```
pub fn get_ref(&self) -> &T { &self.inner }
/// Gets a mutable reference to the underlying value in this cursor.
///
/// Care should be taken to avoid modifying the internal I/O state of the
/// underlying value as it may corrupt this cursor's position.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let mut buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
///
/// let reference = buff.get_mut();
/// ```
pub fn get_mut(&mut self) -> &mut T { &mut self.inner }
/// Returns the current position of this cursor.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
/// use std::io::prelude::*;
/// use std::io::SeekFrom;
///
/// let mut buff = Cursor::new(vec![1, 2, 3, 4, 5]);
///
/// assert_eq!(buff.position(), 0);
///
/// buff.seek(SeekFrom::Current(2)).unwrap();
/// assert_eq!(buff.position(), 2);
///
/// buff.seek(SeekFrom::Current(-1)).unwrap();
/// assert_eq!(buff.position(), 1);
/// ```
pub fn position(&self) -> u64 { self.pos }
/// Sets the position of this cursor.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let mut buff = Cursor::new(vec![1, 2, 3, 4, 5]);
///
/// assert_eq!(buff.position(), 0);
///
/// buff.set_position(2);
/// assert_eq!(buff.position(), 2);
///
/// buff.set_position(4);
/// assert_eq!(buff.position(), 4);
/// ```
pub fn set_position(&mut self, pos: u64) { self.pos = pos; }
}
impl<T> io::Seek for Cursor<T> where T: AsRef<[u8]> {
fn seek(&mut self, style: SeekFrom) -> io::Result<u64> {
let (base_pos, offset) = match style {
SeekFrom::Start(n) => { self.pos = n; return Ok(n); }
SeekFrom::End(n) => (self.inner.as_ref().len() as u64, n),
SeekFrom::Current(n) => (self.pos, n),
};
let new_pos = if offset >= 0 {
base_pos.checked_add(offset as u64)
} else {
base_pos.checked_sub((offset.wrapping_neg()) as u64)
};
match new_pos {
Some(n) => {self.pos = n; Ok(self.pos)}
None => Err(Error::new(ErrorKind::InvalidInput,
"invalid seek to a negative or overflowing position"))
}
}
fn stream_len(&mut self) -> io::Result<u64> {
Ok(self.inner.as_ref().len() as u64)
}
fn stream_position(&mut self) -> io::Result<u64> {
Ok(self.pos)
}
}
impl<T> Read for Cursor<T> where T: AsRef<[u8]> {
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
let n = Read::read(&mut self.get_buf()?, buf)?;
self.pos += n as u64;
Ok(n)
}
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
let mut nread = 0;
for buf in bufs {
let n = self.read(buf)?;
nread += n;
if n < buf.len() {
break;
}
}
Ok(nread)
}
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
let n = buf.len();
Read::read_exact(&mut self.get_buf()?, buf)?;
self.pos += n as u64;
Ok(())
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
}
impl<T> Cursor<T> where T: AsRef<[u8]> {
fn get_buf(&mut self) -> io::Result<&[u8]> {
let amt = cmp::min(self.pos, self.inner.as_ref().len() as u64);
Ok(&self.inner.as_ref()[(amt as usize)..])
}
}
#[cfg(feature="collections")]
impl<T> BufRead for Cursor<T> where T: AsRef<[u8]> {
fn fill_buf(&mut self) -> io::Result<&[u8]> { self.get_buf() }
fn consume(&mut self, amt: usize) { self.pos += amt as u64; }
}
// Non-resizing write implementation
#[inline]
fn slice_write(pos_mut: &mut u64, slice: &mut [u8], buf: &[u8]) -> io::Result<usize> {
let pos = cmp::min(*pos_mut, slice.len() as u64);
let amt = (&mut slice[(pos as usize)..]).write(buf)?;
*pos_mut += amt as u64;
Ok(amt)
}
#[inline]
fn slice_write_vectored(
pos_mut: &mut u64,
slice: &mut [u8],
bufs: &[IoSlice<'_>],
) -> io::Result<usize>
{
let mut nwritten = 0;
for buf in bufs {
let n = slice_write(pos_mut, slice, buf)?;
nwritten += n;
if n < buf.len() {
break;
}
}
Ok(nwritten)
}
// Resizing write implementation
#[cfg(feature="collections")]
fn vec_write(pos_mut: &mut u64, vec: &mut Vec<u8>, buf: &[u8]) -> io::Result<usize> {
let pos: usize = (*pos_mut).try_into().map_err(|_| {
Error::new(ErrorKind::InvalidInput,
"cursor position exceeds maximum possible vector length")
})?;
// Make sure the internal buffer is as least as big as where we
// currently are
let len = vec.len();
if len < pos {
// use `resize` so that the zero filling is as efficient as possible
vec.resize(pos, 0);
}
// Figure out what bytes will be used to overwrite what's currently
// there (left), and what will be appended on the end (right)
{
let space = vec.len() - pos;
let (left, right) = buf.split_at(cmp::min(space, buf.len()));
vec[pos..pos + left.len()].copy_from_slice(left);
vec.extend_from_slice(right);
}
// Bump us forward
*pos_mut = (pos + buf.len()) as u64;
Ok(buf.len())
}
#[cfg(feature="collections")]
fn vec_write_vectored(
pos_mut: &mut u64,
vec: &mut Vec<u8>,
bufs: &[IoSlice<'_>],
) -> io::Result<usize>
{
let mut nwritten = 0;
for buf in bufs {
nwritten += vec_write(pos_mut, vec, buf)?;
}
Ok(nwritten)
}
impl Write for Cursor<&mut [u8]> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
slice_write(&mut self.pos, self.inner, buf)
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
slice_write_vectored(&mut self.pos, self.inner, bufs)
}
#[inline]
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
#[cfg(feature="collections")]
impl Write for Cursor<&mut Vec<u8>> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
vec_write(&mut self.pos, self.inner, buf)
}
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
vec_write_vectored(&mut self.pos, self.inner, bufs)
}
#[inline]
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
#[cfg(feature = "collections")]
impl Write for Cursor<Vec<u8>> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
vec_write(&mut self.pos, &mut self.inner, buf)
}
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
vec_write_vectored(&mut self.pos, &mut self.inner, bufs)
}
#[inline]
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
#[cfg(feature = "alloc")]
impl Write for Cursor<::alloc::boxed::Box<[u8]>> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
slice_write(&mut self.pos, &mut self.inner, buf)
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
slice_write_vectored(&mut self.pos, &mut self.inner, bufs)
}
#[inline]
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
#[cfg(test)]
mod tests {
use crate::io::prelude::*;
use crate::io::{Cursor, SeekFrom, IoSlice, IoSliceMut};
#[test]
fn test_vec_writer() {
let mut writer = Vec::new();
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.write_vectored(
&[IoSlice::new(&[]), IoSlice::new(&[8, 9]), IoSlice::new(&[10])],
).unwrap(), 3);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
assert_eq!(writer, b);
}
#[test]
fn test_mem_writer() {
let mut writer = Cursor::new(Vec::new());
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.write_vectored(
&[IoSlice::new(&[]), IoSlice::new(&[8, 9]), IoSlice::new(&[10])],
).unwrap(), 3);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
assert_eq!(&writer.get_ref()[..], b);
}
#[test]
fn test_mem_mut_writer() {
let mut vec = Vec::new();
let mut writer = Cursor::new(&mut vec);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.write_vectored(
&[IoSlice::new(&[]), IoSlice::new(&[8, 9]), IoSlice::new(&[10])],
).unwrap(), 3);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
assert_eq!(&writer.get_ref()[..], b);
}
#[test]
fn test_box_slice_writer() {
let mut writer = Cursor::new(vec![0u8; 9].into_boxed_slice());
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[]).unwrap(), 0);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[8, 9]).unwrap(), 1);
assert_eq!(writer.write(&[10]).unwrap(), 0);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8];
assert_eq!(&**writer.get_ref(), b);
}
#[test]
fn test_box_slice_writer_vectored() {
let mut writer = Cursor::new(vec![0u8; 9].into_boxed_slice());
assert_eq!(writer.position(), 0);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[0])]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(
writer.write_vectored(&[
IoSlice::new(&[1, 2, 3]),
IoSlice::new(&[4, 5, 6, 7]),
]).unwrap(),
7,
);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write_vectored(&[]).unwrap(), 0);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[8, 9])]).unwrap(), 1);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[10])]).unwrap(), 0);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8];
assert_eq!(&**writer.get_ref(), b);
}
#[test]
fn test_buf_writer() {
let mut buf = [0 as u8; 9];
{
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[]).unwrap(), 0);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[8, 9]).unwrap(), 1);
assert_eq!(writer.write(&[10]).unwrap(), 0);
}
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8];
assert_eq!(buf, b);
}
#[test]
fn test_buf_writer_vectored() {
let mut buf = [0 as u8; 9];
{
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[0])]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(
writer.write_vectored(
&[IoSlice::new(&[1, 2, 3]), IoSlice::new(&[4, 5, 6, 7])],
).unwrap(),
7,
);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write_vectored(&[]).unwrap(), 0);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[8, 9])]).unwrap(), 1);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[10])]).unwrap(), 0);
}
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8];
assert_eq!(buf, b);
}
#[test]
fn test_buf_writer_seek() {
let mut buf = [0 as u8; 8];
{
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[1]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.seek(SeekFrom::Start(2)).unwrap(), 2);
assert_eq!(writer.position(), 2);
assert_eq!(writer.write(&[2]).unwrap(), 1);
assert_eq!(writer.position(), 3);
assert_eq!(writer.seek(SeekFrom::Current(-2)).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[3]).unwrap(), 1);
assert_eq!(writer.position(), 2);
assert_eq!(writer.seek(SeekFrom::End(-1)).unwrap(), 7);
assert_eq!(writer.position(), 7);
assert_eq!(writer.write(&[4]).unwrap(), 1);
assert_eq!(writer.position(), 8);
}
let b: &[_] = &[1, 3, 2, 0, 0, 0, 0, 4];
assert_eq!(buf, b);
}
#[test]
fn test_buf_writer_error() {
let mut buf = [0 as u8; 2];
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[0, 0]).unwrap(), 1);
assert_eq!(writer.write(&[0, 0]).unwrap(), 0);
}
#[test]
fn test_mem_reader() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7]);
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.position(), 5);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(buf, b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_mem_reader_vectored() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7]);
let mut buf = [];
assert_eq!(reader.read_vectored(&mut [IoSliceMut::new(&mut buf)]).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(
reader.read_vectored(&mut [
IoSliceMut::new(&mut []),
IoSliceMut::new(&mut buf),
]).unwrap(),
1,
);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf1 = [0; 4];
let mut buf2 = [0; 4];
assert_eq!(
reader.read_vectored(&mut [
IoSliceMut::new(&mut buf1),
IoSliceMut::new(&mut buf2),
]).unwrap(),
7,
);
let b1: &[_] = &[1, 2, 3, 4];
let b2: &[_] = &[5, 6, 7];
assert_eq!(buf1, b1);
assert_eq!(&buf2[..3], b2);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_boxed_slice_reader() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7].into_boxed_slice());
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.position(), 5);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(buf, b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_boxed_slice_reader_vectored() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7].into_boxed_slice());
let mut buf = [];
assert_eq!(reader.read_vectored(&mut [IoSliceMut::new(&mut buf)]).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(
reader.read_vectored(&mut [
IoSliceMut::new(&mut []),
IoSliceMut::new(&mut buf),
]).unwrap(),
1,
);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf1 = [0; 4];
let mut buf2 = [0; 4];
assert_eq!(
reader.read_vectored(
&mut [IoSliceMut::new(&mut buf1), IoSliceMut::new(&mut buf2)],
).unwrap(),
7,
);
let b1: &[_] = &[1, 2, 3, 4];
let b2: &[_] = &[5, 6, 7];
assert_eq!(buf1, b1);
assert_eq!(&buf2[..3], b2);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn read_to_end() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7]);
let mut v = Vec::new();
reader.read_to_end(&mut v).unwrap();
assert_eq!(v, [0, 1, 2, 3, 4, 5, 6, 7]);
}
#[test]
fn test_slice_reader() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let reader = &mut &in_buf[..];
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.len(), 7);
let b: &[_] = &[0];
assert_eq!(&buf[..], b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.len(), 3);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(&buf[..], b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_slice_reader_vectored() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let reader = &mut &in_buf[..];
let mut buf = [];
assert_eq!(reader.read_vectored(&mut [IoSliceMut::new(&mut buf)]).unwrap(), 0);
let mut buf = [0];
assert_eq!(
reader.read_vectored(&mut [
IoSliceMut::new(&mut []),
IoSliceMut::new(&mut buf),
]).unwrap(),
1,
);
assert_eq!(reader.len(), 7);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf1 = [0; 4];
let mut buf2 = [0; 4];
assert_eq!(
reader.read_vectored(
&mut [IoSliceMut::new(&mut buf1), IoSliceMut::new(&mut buf2)],
).unwrap(),
7,
);
let b1: &[_] = &[1, 2, 3, 4];
let b2: &[_] = &[5, 6, 7];
assert_eq!(buf1, b1);
assert_eq!(&buf2[..3], b2);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_read_exact() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let reader = &mut &in_buf[..];
let mut buf = [];
assert!(reader.read_exact(&mut buf).is_ok());
let mut buf = [8];
assert!(reader.read_exact(&mut buf).is_ok());
assert_eq!(buf[0], 0);
assert_eq!(reader.len(), 7);
let mut buf = [0, 0, 0, 0, 0, 0, 0];
assert!(reader.read_exact(&mut buf).is_ok());
assert_eq!(buf, [1, 2, 3, 4, 5, 6, 7]);
assert_eq!(reader.len(), 0);
let mut buf = [0];
assert!(reader.read_exact(&mut buf).is_err());
}
#[test]
fn test_buf_reader() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let mut reader = Cursor::new(&in_buf[..]);
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.position(), 5);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(buf, b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn seek_past_end() {
let buf = [0xff];
let mut r = Cursor::new(&buf[..]);
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.read(&mut [0]).unwrap(), 0);
let mut r = Cursor::new(vec![10]);
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.read(&mut [0]).unwrap(), 0);
let mut buf = [0];
let mut r = Cursor::new(&mut buf[..]);
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.write(&[3]).unwrap(), 0);
let mut r = Cursor::new(vec![10].into_boxed_slice());
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.write(&[3]).unwrap(), 0);
}
#[test]
fn seek_past_i64() {
let buf = [0xff];
let mut r = Cursor::new(&buf[..]);
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
let mut r = Cursor::new(vec![10]);
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
let mut buf = [0];
let mut r = Cursor::new(&mut buf[..]);
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
let mut r = Cursor::new(vec![10].into_boxed_slice());
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
}
#[test]
fn seek_before_0() {
let buf = [0xff];
let mut r = Cursor::new(&buf[..]);
assert!(r.seek(SeekFrom::End(-2)).is_err());
let mut r = Cursor::new(vec![10]);
assert!(r.seek(SeekFrom::End(-2)).is_err());
let mut buf = [0];
let mut r = Cursor::new(&mut buf[..]);
assert!(r.seek(SeekFrom::End(-2)).is_err());
let mut r = Cursor::new(vec![10].into_boxed_slice());
assert!(r.seek(SeekFrom::End(-2)).is_err());
}
#[test]
fn test_seekable_mem_writer() {
let mut writer = Cursor::new(Vec::<u8>::new());
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.position(), 8);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::Start(0)).unwrap(), 0);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[3, 4]).unwrap(), 2);
let b: &[_] = &[3, 4, 2, 3, 4, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::Current(1)).unwrap(), 3);
assert_eq!(writer.write(&[0, 1]).unwrap(), 2);
let b: &[_] = &[3, 4, 2, 0, 1, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::End(-1)).unwrap(), 7);
assert_eq!(writer.write(&[1, 2]).unwrap(), 2);
let b: &[_] = &[3, 4, 2, 0, 1, 5, 6, 1, 2];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::End(1)).unwrap(), 10);
assert_eq!(writer.write(&[1]).unwrap(), 1);
let b: &[_] = &[3, 4, 2, 0, 1, 5, 6, 1, 2, 0, 1];
assert_eq!(&writer.get_ref()[..], b);
}
#[test]
fn vec_seek_past_end() {
let mut r = Cursor::new(Vec::new());
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.write(&[3]).unwrap(), 1);
}
#[test]
fn vec_seek_before_0() {
let mut r = Cursor::new(Vec::new());
assert!(r.seek(SeekFrom::End(-2)).is_err());
}
#[test]
#[cfg(target_pointer_width = "32")]
fn vec_seek_and_write_past_usize_max() {
let mut c = Cursor::new(Vec::new());
c.set_position(<usize>::max_value() as u64 + 1);
assert!(c.write_all(&[1, 2, 3]).is_err());
}
}

View File

@ -0,0 +1,564 @@
#[cfg(feature="alloc")] use alloc::boxed::Box;
#[cfg(not(feature="alloc"))] use ::FakeBox as Box;
use core::convert::Into;
use core::fmt;
use core::marker::{Send, Sync};
use core::option::Option::{self, Some, None};
use core::result;
#[cfg(feature="collections")] use collections::string::String;
#[cfg(not(feature="collections"))] use ::ErrorString as String;
use core::convert::From;
/// A specialized [`Result`](../result/enum.Result.html) type for I/O
/// operations.
///
/// This type is broadly used across [`std::io`] for any operation which may
/// produce an error.
///
/// This typedef is generally used to avoid writing out [`io::Error`] directly and
/// is otherwise a direct mapping to [`Result`].
///
/// While usual Rust style is to import types directly, aliases of [`Result`]
/// often are not, to make it easier to distinguish between them. [`Result`] is
/// generally assumed to be [`std::result::Result`][`Result`], and so users of this alias
/// will generally use `io::Result` instead of shadowing the prelude's import
/// of [`std::result::Result`][`Result`].
///
/// [`std::io`]: ../io/index.html
/// [`io::Error`]: ../io/struct.Error.html
/// [`Result`]: ../result/enum.Result.html
///
/// # Examples
///
/// A convenience function that bubbles an `io::Result` to its caller:
///
/// ```
/// use std::io;
///
/// fn get_string() -> io::Result<String> {
/// let mut buffer = String::new();
///
/// io::stdin().read_line(&mut buffer)?;
///
/// Ok(buffer)
/// }
/// ```
pub type Result<T> = result::Result<T, Error>;
/// The error type for I/O operations of the [`Read`], [`Write`], [`Seek`], and
/// associated traits.
///
/// Errors mostly originate from the underlying OS, but custom instances of
/// `Error` can be created with crafted error messages and a particular value of
/// [`ErrorKind`].
///
/// [`Read`]: ../io/trait.Read.html
/// [`Write`]: ../io/trait.Write.html
/// [`Seek`]: ../io/trait.Seek.html
/// [`ErrorKind`]: enum.ErrorKind.html
pub struct Error {
repr: Repr,
}
impl fmt::Debug for Error {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt::Debug::fmt(&self.repr, f)
}
}
enum Repr {
Os(i32),
Simple(ErrorKind),
#[cfg(feature="alloc")]
Custom(Box<Custom>),
#[cfg(not(feature="alloc"))]
Custom(Custom),
}
#[derive(Debug)]
struct Custom {
kind: ErrorKind,
error: String,
}
/// A list specifying general categories of I/O error.
///
/// This list is intended to grow over time and it is not recommended to
/// exhaustively match against it.
///
/// It is used with the [`io::Error`] type.
///
/// [`io::Error`]: struct.Error.html
#[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
#[allow(deprecated)]
#[non_exhaustive]
pub enum ErrorKind {
/// An entity was not found, often a file.
NotFound,
/// The operation lacked the necessary privileges to complete.
PermissionDenied,
/// The connection was refused by the remote server.
ConnectionRefused,
/// The connection was reset by the remote server.
ConnectionReset,
/// The connection was aborted (terminated) by the remote server.
ConnectionAborted,
/// The network operation failed because it was not connected yet.
NotConnected,
/// A socket address could not be bound because the address is already in
/// use elsewhere.
AddrInUse,
/// A nonexistent interface was requested or the requested address was not
/// local.
AddrNotAvailable,
/// The operation failed because a pipe was closed.
BrokenPipe,
/// An entity already exists, often a file.
AlreadyExists,
/// The operation needs to block to complete, but the blocking operation was
/// requested to not occur.
WouldBlock,
/// A parameter was incorrect.
InvalidInput,
/// Data not valid for the operation were encountered.
///
/// Unlike [`InvalidInput`], this typically means that the operation
/// parameters were valid, however the error was caused by malformed
/// input data.
///
/// For example, a function that reads a file into a string will error with
/// `InvalidData` if the file's contents are not valid UTF-8.
///
/// [`InvalidInput`]: #variant.InvalidInput
InvalidData,
/// The I/O operation's timeout expired, causing it to be canceled.
TimedOut,
/// An error returned when an operation could not be completed because a
/// call to [`write`] returned [`Ok(0)`].
///
/// This typically means that an operation could only succeed if it wrote a
/// particular number of bytes but only a smaller number of bytes could be
/// written.
///
/// [`write`]: ../../std/io/trait.Write.html#tymethod.write
/// [`Ok(0)`]: ../../std/io/type.Result.html
WriteZero,
/// This operation was interrupted.
///
/// Interrupted operations can typically be retried.
Interrupted,
/// Any I/O error not part of this list.
Other,
/// An error returned when an operation could not be completed because an
/// "end of file" was reached prematurely.
///
/// This typically means that an operation could only succeed if it read a
/// particular number of bytes but only a smaller number of bytes could be
/// read.
UnexpectedEof,
}
impl ErrorKind {
pub(crate) fn as_str(&self) -> &'static str {
match *self {
ErrorKind::NotFound => "entity not found",
ErrorKind::PermissionDenied => "permission denied",
ErrorKind::ConnectionRefused => "connection refused",
ErrorKind::ConnectionReset => "connection reset",
ErrorKind::ConnectionAborted => "connection aborted",
ErrorKind::NotConnected => "not connected",
ErrorKind::AddrInUse => "address in use",
ErrorKind::AddrNotAvailable => "address not available",
ErrorKind::BrokenPipe => "broken pipe",
ErrorKind::AlreadyExists => "entity already exists",
ErrorKind::WouldBlock => "operation would block",
ErrorKind::InvalidInput => "invalid input parameter",
ErrorKind::InvalidData => "invalid data",
ErrorKind::TimedOut => "timed out",
ErrorKind::WriteZero => "write zero",
ErrorKind::Interrupted => "operation interrupted",
ErrorKind::Other => "other os error",
ErrorKind::UnexpectedEof => "unexpected end of file",
}
}
}
/// Intended for use for errors not exposed to the user, where allocating onto
/// the heap (for normal construction via Error::new) is too costly.
impl From<ErrorKind> for Error {
/// Converts an [`ErrorKind`] into an [`Error`].
///
/// This conversion allocates a new error with a simple representation of error kind.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// let not_found = ErrorKind::NotFound;
/// let error = Error::from(not_found);
/// assert_eq!("entity not found", format!("{}", error));
/// ```
///
/// [`ErrorKind`]: ../../std/io/enum.ErrorKind.html
/// [`Error`]: ../../std/io/struct.Error.html
#[inline]
fn from(kind: ErrorKind) -> Error {
Error {
repr: Repr::Simple(kind)
}
}
}
impl Error {
/// Creates a new I/O error from a known kind of error as well as an
/// arbitrary error payload.
///
/// This function is used to generically create I/O errors which do not
/// originate from the OS itself. The `error` argument is an arbitrary
/// payload which will be contained in this `Error`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// // errors can be created from strings
/// let custom_error = Error::new(ErrorKind::Other, "oh no!");
///
/// // errors can also be created from other errors
/// let custom_error2 = Error::new(ErrorKind::Interrupted, custom_error);
/// ```
pub fn new<E>(kind: ErrorKind, error: E) -> Error
where E: Into<String>
{
Self::_new(kind, error.into())
}
fn _new(kind: ErrorKind, error: String) -> Error {
Error {
repr: Repr::Custom(Box::new(Custom {
kind,
error,
}))
}
}
/// Creates a new instance of an `Error` from a particular OS error code.
///
/// # Examples
///
/// On Linux:
///
/// ```
/// # if cfg!(target_os = "linux") {
/// use std::io;
///
/// let error = io::Error::from_raw_os_error(22);
/// assert_eq!(error.kind(), io::ErrorKind::InvalidInput);
/// # }
/// ```
///
/// On Windows:
///
/// ```
/// # if cfg!(windows) {
/// use std::io;
///
/// let error = io::Error::from_raw_os_error(10022);
/// assert_eq!(error.kind(), io::ErrorKind::InvalidInput);
/// # }
/// ```
pub fn from_raw_os_error(code: i32) -> Error {
Error { repr: Repr::Os(code) }
}
/// Returns the OS error that this error represents (if any).
///
/// If this `Error` was constructed via `last_os_error` or
/// `from_raw_os_error`, then this function will return `Some`, otherwise
/// it will return `None`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_os_error(err: &Error) {
/// if let Some(raw_os_err) = err.raw_os_error() {
/// println!("raw OS error: {:?}", raw_os_err);
/// } else {
/// println!("Not an OS error");
/// }
/// }
///
/// fn main() {
/// // Will print "raw OS error: ...".
/// print_os_error(&Error::last_os_error());
/// // Will print "Not an OS error".
/// print_os_error(&Error::new(ErrorKind::Other, "oh no!"));
/// }
/// ```
pub fn raw_os_error(&self) -> Option<i32> {
match self.repr {
Repr::Os(i) => Some(i),
Repr::Custom(..) => None,
Repr::Simple(..) => None,
}
}
/// Returns a reference to the inner error wrapped by this error (if any).
///
/// If this `Error` was constructed via `new` then this function will
/// return `Some`, otherwise it will return `None`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_error(err: &Error) {
/// if let Some(inner_err) = err.get_ref() {
/// println!("Inner error: {:?}", inner_err);
/// } else {
/// println!("No inner error");
/// }
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(&Error::last_os_error());
/// // Will print "Inner error: ...".
/// print_error(&Error::new(ErrorKind::Other, "oh no!"));
/// }
/// ```
pub fn get_ref(&self) -> Option<&String> {
match self.repr {
Repr::Os(..) => None,
Repr::Simple(..) => None,
Repr::Custom(ref c) => Some(&c.error),
}
}
/// Returns a mutable reference to the inner error wrapped by this error
/// (if any).
///
/// If this `Error` was constructed via `new` then this function will
/// return `Some`, otherwise it will return `None`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
/// use std::{error, fmt};
/// use std::fmt::Display;
///
/// #[derive(Debug)]
/// struct MyError {
/// v: String,
/// }
///
/// impl MyError {
/// fn new() -> MyError {
/// MyError {
/// v: "oh no!".to_string()
/// }
/// }
///
/// fn change_message(&mut self, new_message: &str) {
/// self.v = new_message.to_string();
/// }
/// }
///
/// impl error::Error for MyError {
/// fn description(&self) -> &str { &self.v }
/// }
///
/// impl Display for MyError {
/// fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
/// write!(f, "MyError: {}", &self.v)
/// }
/// }
///
/// fn change_error(mut err: Error) -> Error {
/// if let Some(inner_err) = err.get_mut() {
/// inner_err.downcast_mut::<MyError>().unwrap().change_message("I've been changed!");
/// }
/// err
/// }
///
/// fn print_error(err: &Error) {
/// if let Some(inner_err) = err.get_ref() {
/// println!("Inner error: {}", inner_err);
/// } else {
/// println!("No inner error");
/// }
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(&change_error(Error::last_os_error()));
/// // Will print "Inner error: ...".
/// print_error(&change_error(Error::new(ErrorKind::Other, MyError::new())));
/// }
/// ```
pub fn get_mut(&mut self) -> Option<&mut String> {
match self.repr {
Repr::Os(..) => None,
Repr::Simple(..) => None,
Repr::Custom(ref mut c) => Some(&mut c.error),
}
}
/// Consumes the `Error`, returning its inner error (if any).
///
/// If this `Error` was constructed via `new` then this function will
/// return `Some`, otherwise it will return `None`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_error(err: Error) {
/// if let Some(inner_err) = err.into_inner() {
/// println!("Inner error: {}", inner_err);
/// } else {
/// println!("No inner error");
/// }
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(Error::last_os_error());
/// // Will print "Inner error: ...".
/// print_error(Error::new(ErrorKind::Other, "oh no!"));
/// }
/// ```
pub fn into_inner(self) -> Option<String> {
match self.repr {
Repr::Os(..) => None,
Repr::Simple(..) => None,
Repr::Custom(c) => Some(c.error)
}
}
/// Returns the corresponding `ErrorKind` for this error.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_error(err: Error) {
/// println!("{:?}", err.kind());
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(Error::last_os_error());
/// // Will print "Inner error: ...".
/// print_error(Error::new(ErrorKind::AddrInUse, "oh no!"));
/// }
/// ```
pub fn kind(&self) -> ErrorKind {
match self.repr {
Repr::Os(_code) => ErrorKind::Other,
Repr::Custom(ref c) => c.kind,
Repr::Simple(kind) => kind,
}
}
}
impl fmt::Debug for Repr {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
match *self {
Repr::Os(code) =>
fmt.debug_struct("Os")
.field("code", &code).finish(),
Repr::Custom(ref c) => fmt::Debug::fmt(&c, fmt),
Repr::Simple(kind) => fmt.debug_tuple("Kind").field(&kind).finish(),
}
}
}
impl fmt::Display for Error {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
match self.repr {
Repr::Os(code) => {
write!(fmt, "os error {}", code)
}
Repr::Custom(ref c) => c.error.fmt(fmt),
Repr::Simple(kind) => write!(fmt, "{}", kind.as_str()),
}
}
}
fn _assert_error_is_sync_send() {
fn _is_sync_send<T: Sync+Send>() {}
_is_sync_send::<Error>();
}
#[cfg(test)]
mod test {
use super::{Error, ErrorKind, Repr, Custom};
use crate::error;
use crate::fmt;
use crate::sys::os::error_string;
use crate::sys::decode_error_kind;
#[test]
fn test_debug_error() {
let code = 6;
let msg = error_string(code);
let kind = decode_error_kind(code);
let err = Error {
repr: Repr::Custom(box Custom {
kind: ErrorKind::InvalidInput,
error: box Error {
repr: super::Repr::Os(code)
},
})
};
let expected = format!(
"Custom {{ \
kind: InvalidInput, \
error: Os {{ \
code: {:?}, \
kind: {:?}, \
message: {:?} \
}} \
}}",
code, kind, msg
);
assert_eq!(format!("{:?}", err), expected);
}
#[test]
fn test_downcasting() {
#[derive(Debug)]
struct TestError;
impl fmt::Display for TestError {
fn fmt(&self, _: &mut fmt::Formatter<'_>) -> fmt::Result {
Ok(())
}
}
impl error::Error for TestError {
fn description(&self) -> &str {
"asdf"
}
}
// we have to call all of these UFCS style right now since method
// resolution won't implicitly drop the Send+Sync bounds
let mut err = Error::new(ErrorKind::Other, TestError);
assert!(err.get_ref().unwrap().is::<TestError>());
assert_eq!("asdf", err.get_ref().unwrap().description());
assert!(err.get_mut().unwrap().is::<TestError>());
let extracted = err.into_inner().unwrap();
extracted.downcast::<TestError>().unwrap();
}
}

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@ -0,0 +1,400 @@
#[cfg(feature="alloc")] use alloc::boxed::Box;
use core::cmp;
use crate::io::{self, SeekFrom, Read, Initializer, Write, Seek, Error, ErrorKind, IoSliceMut, IoSlice};
#[cfg(feature="collections")] use crate::io::BufRead;
use core::fmt;
use core::mem;
#[cfg(feature="collections")] use collections::string::String;
#[cfg(feature="collections")] use collections::vec::Vec;
// =============================================================================
// Forwarding implementations
impl<R: Read + ?Sized> Read for &mut R {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
(**self).read(buf)
}
#[inline]
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
(**self).read_vectored(bufs)
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
(**self).initializer()
}
#[cfg(feature="collections")]
#[inline]
fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_to_end(buf)
}
#[cfg(feature="collections")]
#[inline]
fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_to_string(buf)
}
#[inline]
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
(**self).read_exact(buf)
}
}
impl<W: Write + ?Sized> Write for &mut W {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> { (**self).write(buf) }
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
(**self).write_vectored(bufs)
}
#[inline]
fn flush(&mut self) -> io::Result<()> { (**self).flush() }
#[inline]
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
(**self).write_all(buf)
}
#[inline]
fn write_fmt(&mut self, fmt: fmt::Arguments<'_>) -> io::Result<()> {
(**self).write_fmt(fmt)
}
}
impl<S: Seek + ?Sized> Seek for &mut S {
#[inline]
fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> { (**self).seek(pos) }
}
#[cfg(feature="collections")]
impl<B: BufRead + ?Sized> BufRead for &mut B {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> { (**self).fill_buf() }
#[inline]
fn consume(&mut self, amt: usize) { (**self).consume(amt) }
#[inline]
fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_until(byte, buf)
}
#[inline]
fn read_line(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_line(buf)
}
}
#[cfg(feature="alloc")]
impl<R: Read + ?Sized> Read for Box<R> {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
(**self).read(buf)
}
#[inline]
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
(**self).read_vectored(bufs)
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
(**self).initializer()
}
#[cfg(feature="collections")]
#[inline]
fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_to_end(buf)
}
#[cfg(feature="collections")]
#[inline]
fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_to_string(buf)
}
#[inline]
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
(**self).read_exact(buf)
}
}
#[cfg(feature="alloc")]
impl<W: Write + ?Sized> Write for Box<W> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> { (**self).write(buf) }
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
(**self).write_vectored(bufs)
}
#[inline]
fn flush(&mut self) -> io::Result<()> { (**self).flush() }
#[inline]
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
(**self).write_all(buf)
}
#[inline]
fn write_fmt(&mut self, fmt: fmt::Arguments<'_>) -> io::Result<()> {
(**self).write_fmt(fmt)
}
}
#[cfg(feature="alloc")]
impl<S: Seek + ?Sized> Seek for Box<S> {
#[inline]
fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> { (**self).seek(pos) }
}
#[cfg(feature="collections")]
impl<B: BufRead + ?Sized> BufRead for Box<B> {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> { (**self).fill_buf() }
#[inline]
fn consume(&mut self, amt: usize) { (**self).consume(amt) }
#[inline]
fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_until(byte, buf)
}
#[inline]
fn read_line(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_line(buf)
}
}
// Used by panicking::default_hook
#[cfg(test)]
/// This impl is only used by printing logic, so any error returned is always
/// of kind `Other`, and should be ignored.
impl Write for Box<dyn (::realstd::io::Write) + Send> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
(**self).write(buf).map_err(|_| ErrorKind::Other.into())
}
fn flush(&mut self) -> io::Result<()> {
(**self).flush().map_err(|_| ErrorKind::Other.into())
}
}
// =============================================================================
// In-memory buffer implementations
/// Read is implemented for `&[u8]` by copying from the slice.
///
/// Note that reading updates the slice to point to the yet unread part.
/// The slice will be empty when EOF is reached.
impl Read for &[u8] {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
let amt = cmp::min(buf.len(), self.len());
let (a, b) = self.split_at(amt);
// First check if the amount of bytes we want to read is small:
// `copy_from_slice` will generally expand to a call to `memcpy`, and
// for a single byte the overhead is significant.
if amt == 1 {
buf[0] = a[0];
} else {
buf[..amt].copy_from_slice(a);
}
*self = b;
Ok(amt)
}
#[inline]
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
let mut nread = 0;
for buf in bufs {
nread += self.read(buf)?;
if self.is_empty() {
break;
}
}
Ok(nread)
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
#[inline]
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
if buf.len() > self.len() {
return Err(Error::new(ErrorKind::UnexpectedEof,
"failed to fill whole buffer"));
}
let (a, b) = self.split_at(buf.len());
// First check if the amount of bytes we want to read is small:
// `copy_from_slice` will generally expand to a call to `memcpy`, and
// for a single byte the overhead is significant.
if buf.len() == 1 {
buf[0] = a[0];
} else {
buf.copy_from_slice(a);
}
*self = b;
Ok(())
}
#[cfg(feature="collections")]
#[inline]
fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
buf.extend_from_slice(*self);
let len = self.len();
*self = &self[len..];
Ok(len)
}
}
#[cfg(feature="collections")]
impl BufRead for &[u8] {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> { Ok(*self) }
#[inline]
fn consume(&mut self, amt: usize) { *self = &self[amt..]; }
}
/// Write is implemented for `&mut [u8]` by copying into the slice, overwriting
/// its data.
///
/// Note that writing updates the slice to point to the yet unwritten part.
/// The slice will be empty when it has been completely overwritten.
impl Write for &mut [u8] {
#[inline]
fn write(&mut self, data: &[u8]) -> io::Result<usize> {
let amt = cmp::min(data.len(), self.len());
let (a, b) = mem::replace(self, &mut []).split_at_mut(amt);
a.copy_from_slice(&data[..amt]);
*self = b;
Ok(amt)
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
let mut nwritten = 0;
for buf in bufs {
nwritten += self.write(buf)?;
if self.is_empty() {
break;
}
}
Ok(nwritten)
}
#[inline]
fn write_all(&mut self, data: &[u8]) -> io::Result<()> {
if self.write(data)? == data.len() {
Ok(())
} else {
Err(Error::new(ErrorKind::WriteZero, "failed to write whole buffer"))
}
}
#[inline]
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
/// Write is implemented for `Vec<u8>` by appending to the vector.
/// The vector will grow as needed.
#[cfg(feature="collections")]
impl Write for Vec<u8> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
self.extend_from_slice(buf);
Ok(buf.len())
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
let len = bufs.iter().map(|b| b.len()).sum();
self.reserve(len);
for buf in bufs {
self.extend_from_slice(buf);
}
Ok(len)
}
#[inline]
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
self.extend_from_slice(buf);
Ok(())
}
#[inline]
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
#[cfg(test)]
mod tests {
use crate::io::prelude::*;
#[bench]
fn bench_read_slice(b: &mut test::Bencher) {
let buf = [5; 1024];
let mut dst = [0; 128];
b.iter(|| {
let mut rd = &buf[..];
for _ in 0..8 {
let _ = rd.read(&mut dst);
test::black_box(&dst);
}
})
}
#[bench]
fn bench_write_slice(b: &mut test::Bencher) {
let mut buf = [0; 1024];
let src = [5; 128];
b.iter(|| {
let mut wr = &mut buf[..];
for _ in 0..8 {
let _ = wr.write_all(&src);
test::black_box(&wr);
}
})
}
#[bench]
fn bench_read_vec(b: &mut test::Bencher) {
let buf = vec![5; 1024];
let mut dst = [0; 128];
b.iter(|| {
let mut rd = &buf[..];
for _ in 0..8 {
let _ = rd.read(&mut dst);
test::black_box(&dst);
}
})
}
#[bench]
fn bench_write_vec(b: &mut test::Bencher) {
let mut buf = Vec::with_capacity(1024);
let src = [5; 128];
b.iter(|| {
let mut wr = &mut buf[..];
for _ in 0..8 {
let _ = wr.write_all(&src);
test::black_box(&wr);
}
})
}
}

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//! The I/O Prelude
//!
//! The purpose of this module is to alleviate imports of many common I/O traits
//! by adding a glob import to the top of I/O heavy modules:
//!
//! ```
//! # #![allow(unused_imports)]
//! use std::io::prelude::*;
//! ```
pub use super::{Read, Write, Seek};
#[cfg(feature="collections")] pub use super::BufRead;
#[cfg(feature="collections")] pub use alloc::boxed::Box;
#[cfg(feature="collections")] pub use collections::vec::Vec;

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#![allow(missing_copy_implementations)]
use core::fmt;
use crate::io::{self, Read, Initializer, Write, ErrorKind, IoSlice, IoSliceMut};
#[cfg(feature="collections")] use crate::io::BufRead;
use core::mem;
/// Copies the entire contents of a reader into a writer.
///
/// This function will continuously read data from `reader` and then
/// write it into `writer` in a streaming fashion until `reader`
/// returns EOF.
///
/// On success, the total number of bytes that were copied from
/// `reader` to `writer` is returned.
///
/// If youre wanting to copy the contents of one file to another and youre
/// working with filesystem paths, see the [`fs::copy`] function.
///
/// [`fs::copy`]: ../fs/fn.copy.html
///
/// # Errors
///
/// This function will return an error immediately if any call to `read` or
/// `write` returns an error. All instances of `ErrorKind::Interrupted` are
/// handled by this function and the underlying operation is retried.
///
/// # Examples
///
/// ```
/// use std::io;
///
/// fn main() -> io::Result<()> {
/// let mut reader: &[u8] = b"hello";
/// let mut writer: Vec<u8> = vec![];
///
/// io::copy(&mut reader, &mut writer)?;
///
/// assert_eq!(&b"hello"[..], &writer[..]);
/// Ok(())
/// }
/// ```
pub fn copy<R: ?Sized, W: ?Sized>(reader: &mut R, writer: &mut W) -> io::Result<u64>
where R: Read, W: Write
{
let mut buf = unsafe {
let mut buf: [u8; super::DEFAULT_BUF_SIZE] = mem::uninitialized();
reader.initializer().initialize(&mut buf);
buf
};
let mut written = 0;
loop {
let len = match reader.read(&mut buf) {
Ok(0) => return Ok(written),
Ok(len) => len,
Err(ref e) if e.kind() == ErrorKind::Interrupted => continue,
Err(e) => return Err(e),
};
writer.write_all(&buf[..len])?;
written += len as u64;
}
}
/// A reader which is always at EOF.
///
/// This struct is generally created by calling [`empty`]. Please see
/// the documentation of [`empty()`][`empty`] for more details.
///
/// [`empty`]: fn.empty.html
pub struct Empty { _priv: () }
/// Constructs a new handle to an empty reader.
///
/// All reads from the returned reader will return [`Ok`]`(0)`.
///
/// [`Ok`]: ../result/enum.Result.html#variant.Ok
///
/// # Examples
///
/// A slightly sad example of not reading anything into a buffer:
///
/// ```
/// use std::io::{self, Read};
///
/// let mut buffer = String::new();
/// io::empty().read_to_string(&mut buffer).unwrap();
/// assert!(buffer.is_empty());
/// ```
pub fn empty() -> Empty { Empty { _priv: () } }
impl Read for Empty {
#[inline]
fn read(&mut self, _buf: &mut [u8]) -> io::Result<usize> { Ok(0) }
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
}
#[cfg(feature="collections")]
impl BufRead for Empty {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> { Ok(&[]) }
#[inline]
fn consume(&mut self, _n: usize) {}
}
impl fmt::Debug for Empty {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.pad("Empty { .. }")
}
}
/// A reader which yields one byte over and over and over and over and over and...
///
/// This struct is generally created by calling [`repeat`][repeat]. Please
/// see the documentation of `repeat()` for more details.
///
/// [repeat]: fn.repeat.html
pub struct Repeat { byte: u8 }
/// Creates an instance of a reader that infinitely repeats one byte.
///
/// All reads from this reader will succeed by filling the specified buffer with
/// the given byte.
///
/// # Examples
///
/// ```
/// use std::io::{self, Read};
///
/// let mut buffer = [0; 3];
/// io::repeat(0b101).read_exact(&mut buffer).unwrap();
/// assert_eq!(buffer, [0b101, 0b101, 0b101]);
/// ```
pub fn repeat(byte: u8) -> Repeat { Repeat { byte } }
impl Read for Repeat {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
for slot in &mut *buf {
*slot = self.byte;
}
Ok(buf.len())
}
#[inline]
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
let mut nwritten = 0;
for buf in bufs {
nwritten += self.read(buf)?;
}
Ok(nwritten)
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
}
impl fmt::Debug for Repeat {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.pad("Repeat { .. }")
}
}
/// A writer which will move data into the void.
///
/// This struct is generally created by calling [`sink`][sink]. Please
/// see the documentation of `sink()` for more details.
///
/// [sink]: fn.sink.html
pub struct Sink { _priv: () }
/// Creates an instance of a writer which will successfully consume all data.
///
/// All calls to `write` on the returned instance will return `Ok(buf.len())`
/// and the contents of the buffer will not be inspected.
///
/// # Examples
///
/// ```rust
/// use std::io::{self, Write};
///
/// let buffer = vec![1, 2, 3, 5, 8];
/// let num_bytes = io::sink().write(&buffer).unwrap();
/// assert_eq!(num_bytes, 5);
/// ```
pub fn sink() -> Sink { Sink { _priv: () } }
impl Write for Sink {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> { Ok(buf.len()) }
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
let total_len = bufs.iter().map(|b| b.len()).sum();
Ok(total_len)
}
#[inline]
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
impl fmt::Debug for Sink {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.pad("Sink { .. }")
}
}
#[cfg(test)]
mod tests {
use crate::io::prelude::*;
use crate::io::{copy, sink, empty, repeat};
#[test]
fn copy_copies() {
let mut r = repeat(0).take(4);
let mut w = sink();
assert_eq!(copy(&mut r, &mut w).unwrap(), 4);
let mut r = repeat(0).take(1 << 17);
assert_eq!(copy(&mut r as &mut dyn Read, &mut w as &mut dyn Write).unwrap(), 1 << 17);
}
#[test]
fn sink_sinks() {
let mut s = sink();
assert_eq!(s.write(&[]).unwrap(), 0);
assert_eq!(s.write(&[0]).unwrap(), 1);
assert_eq!(s.write(&[0; 1024]).unwrap(), 1024);
assert_eq!(s.by_ref().write(&[0; 1024]).unwrap(), 1024);
}
#[test]
fn empty_reads() {
let mut e = empty();
assert_eq!(e.read(&mut []).unwrap(), 0);
assert_eq!(e.read(&mut [0]).unwrap(), 0);
assert_eq!(e.read(&mut [0; 1024]).unwrap(), 0);
assert_eq!(e.by_ref().read(&mut [0; 1024]).unwrap(), 0);
}
#[test]
fn repeat_repeats() {
let mut r = repeat(4);
let mut b = [0; 1024];
assert_eq!(r.read(&mut b).unwrap(), 1024);
assert!(b.iter().all(|b| *b == 4));
}
#[test]
fn take_some_bytes() {
assert_eq!(repeat(4).take(100).bytes().count(), 100);
assert_eq!(repeat(4).take(100).bytes().next().unwrap().unwrap(), 4);
assert_eq!(repeat(1).take(10).chain(repeat(2).take(10)).bytes().count(), 20);
}
}

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// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use core::prelude::v1::*;
use io::prelude::*;
#[cfg(feature = "collections")] use core::convert::TryInto;
use core::cmp;
use io::{self, Initializer, SeekFrom, Error, ErrorKind};
/// A `Cursor` wraps another type and provides it with a
/// [`Seek`] implementation.
///
/// `Cursor`s are typically used with in-memory buffers to allow them to
/// implement [`Read`] and/or [`Write`], allowing these buffers to be used
/// anywhere you might use a reader or writer that does actual I/O.
///
/// The standard library implements some I/O traits on various types which
/// are commonly used as a buffer, like `Cursor<`[`Vec`]`<u8>>` and
/// `Cursor<`[`&[u8]`][bytes]`>`.
///
/// # Examples
///
/// We may want to write bytes to a [`File`] in our production
/// code, but use an in-memory buffer in our tests. We can do this with
/// `Cursor`:
///
/// [`Seek`]: trait.Seek.html
/// [`Read`]: ../../std/io/trait.Read.html
/// [`Write`]: ../../std/io/trait.Write.html
/// [`Vec`]: ../../std/vec/struct.Vec.html
/// [bytes]: ../../std/primitive.slice.html
/// [`File`]: ../fs/struct.File.html
///
/// ```no_run
/// use std::io::prelude::*;
/// use std::io::{self, SeekFrom};
/// use std::fs::File;
///
/// // a library function we've written
/// fn write_ten_bytes_at_end<W: Write + Seek>(writer: &mut W) -> io::Result<()> {
/// writer.seek(SeekFrom::End(-10))?;
///
/// for i in 0..10 {
/// writer.write(&[i])?;
/// }
///
/// // all went well
/// Ok(())
/// }
///
/// # fn foo() -> io::Result<()> {
/// // Here's some code that uses this library function.
/// //
/// // We might want to use a BufReader here for efficiency, but let's
/// // keep this example focused.
/// let mut file = File::create("foo.txt")?;
///
/// write_ten_bytes_at_end(&mut file)?;
/// # Ok(())
/// # }
///
/// // now let's write a test
/// #[test]
/// fn test_writes_bytes() {
/// // setting up a real File is much slower than an in-memory buffer,
/// // let's use a cursor instead
/// use std::io::Cursor;
/// let mut buff = Cursor::new(vec![0; 15]);
///
/// write_ten_bytes_at_end(&mut buff).unwrap();
///
/// assert_eq!(&buff.get_ref()[5..15], &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
/// }
/// ```
#[derive(Clone, Debug)]
pub struct Cursor<T> {
inner: T,
pos: u64,
}
impl<T> Cursor<T> {
/// Creates a new cursor wrapping the provided underlying I/O object.
///
/// Cursor initial position is `0` even if underlying object (e.
/// g. `Vec`) is not empty. So writing to cursor starts with
/// overwriting `Vec` content, not with appending to it.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
/// ```
pub fn new(inner: T) -> Cursor<T> {
Cursor { pos: 0, inner: inner }
}
/// Consumes this cursor, returning the underlying value.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
///
/// let vec = buff.into_inner();
/// ```
pub fn into_inner(self) -> T { self.inner }
/// Gets a reference to the underlying value in this cursor.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
///
/// let reference = buff.get_ref();
/// ```
pub fn get_ref(&self) -> &T { &self.inner }
/// Gets a mutable reference to the underlying value in this cursor.
///
/// Care should be taken to avoid modifying the internal I/O state of the
/// underlying value as it may corrupt this cursor's position.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let mut buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
///
/// let reference = buff.get_mut();
/// ```
pub fn get_mut(&mut self) -> &mut T { &mut self.inner }
/// Returns the current position of this cursor.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
/// use std::io::prelude::*;
/// use std::io::SeekFrom;
///
/// let mut buff = Cursor::new(vec![1, 2, 3, 4, 5]);
///
/// assert_eq!(buff.position(), 0);
///
/// buff.seek(SeekFrom::Current(2)).unwrap();
/// assert_eq!(buff.position(), 2);
///
/// buff.seek(SeekFrom::Current(-1)).unwrap();
/// assert_eq!(buff.position(), 1);
/// ```
pub fn position(&self) -> u64 { self.pos }
/// Sets the position of this cursor.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let mut buff = Cursor::new(vec![1, 2, 3, 4, 5]);
///
/// assert_eq!(buff.position(), 0);
///
/// buff.set_position(2);
/// assert_eq!(buff.position(), 2);
///
/// buff.set_position(4);
/// assert_eq!(buff.position(), 4);
/// ```
pub fn set_position(&mut self, pos: u64) { self.pos = pos; }
}
impl<T> io::Seek for Cursor<T> where T: AsRef<[u8]> {
fn seek(&mut self, style: SeekFrom) -> io::Result<u64> {
let (base_pos, offset) = match style {
SeekFrom::Start(n) => { self.pos = n; return Ok(n); }
SeekFrom::End(n) => (self.inner.as_ref().len() as u64, n),
SeekFrom::Current(n) => (self.pos, n),
};
let new_pos = if offset >= 0 {
base_pos.checked_add(offset as u64)
} else {
base_pos.checked_sub((offset.wrapping_neg()) as u64)
};
match new_pos {
Some(n) => {self.pos = n; Ok(self.pos)}
None => Err(Error::new(ErrorKind::InvalidInput,
"invalid seek to a negative or overflowing position"))
}
}
}
impl<T> Read for Cursor<T> where T: AsRef<[u8]> {
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
let n = Read::read(&mut self.get_buf()?, buf)?;
self.pos += n as u64;
Ok(n)
}
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
let n = buf.len();
Read::read_exact(&mut self.get_buf()?, buf)?;
self.pos += n as u64;
Ok(())
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
}
impl<T> Cursor<T> where T: AsRef<[u8]> {
fn get_buf(&mut self) -> io::Result<&[u8]> {
let amt = cmp::min(self.pos, self.inner.as_ref().len() as u64);
Ok(&self.inner.as_ref()[(amt as usize)..])
}
}
#[cfg(feature="collections")]
impl<T> BufRead for Cursor<T> where T: AsRef<[u8]> {
fn fill_buf(&mut self) -> io::Result<&[u8]> { self.get_buf() }
fn consume(&mut self, amt: usize) { self.pos += amt as u64; }
}
impl<'a> Write for Cursor<&'a mut [u8]> {
#[inline]
fn write(&mut self, data: &[u8]) -> io::Result<usize> {
let pos = cmp::min(self.pos, self.inner.len() as u64);
let amt = (&mut self.inner[(pos as usize)..]).write(data)?;
self.pos += amt as u64;
Ok(amt)
}
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
#[cfg(feature = "collections")]
impl Write for Cursor<Vec<u8>> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
let pos: usize = self.position().try_into().map_err(|_| {
Error::new(ErrorKind::InvalidInput,
"cursor position exceeds maximum possible vector length")
})?;
// Make sure the internal buffer is as least as big as where we
// currently are
let len = self.inner.len();
if len < pos {
// use `resize` so that the zero filling is as efficient as possible
self.inner.resize(pos, 0);
}
// Figure out what bytes will be used to overwrite what's currently
// there (left), and what will be appended on the end (right)
{
let space = self.inner.len() - pos;
let (left, right) = buf.split_at(cmp::min(space, buf.len()));
self.inner[pos..pos + left.len()].copy_from_slice(left);
self.inner.extend_from_slice(right);
}
// Bump us forward
self.set_position((pos + buf.len()) as u64);
Ok(buf.len())
}
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
#[cfg(feature = "alloc")]
impl Write for Cursor<::alloc::boxed::Box<[u8]>> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
let pos = cmp::min(self.pos, self.inner.len() as u64);
let amt = (&mut self.inner[(pos as usize)..]).write(buf)?;
self.pos += amt as u64;
Ok(amt)
}
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
#[cfg(test)]
mod tests {
use io::prelude::*;
use io::{Cursor, SeekFrom};
#[test]
fn test_vec_writer() {
let mut writer = Vec::new();
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7];
assert_eq!(writer, b);
}
#[test]
fn test_mem_writer() {
let mut writer = Cursor::new(Vec::new());
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
}
#[test]
fn test_box_slice_writer() {
let mut writer = Cursor::new(vec![0u8; 9].into_boxed_slice());
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[]).unwrap(), 0);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[8, 9]).unwrap(), 1);
assert_eq!(writer.write(&[10]).unwrap(), 0);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8];
assert_eq!(&**writer.get_ref(), b);
}
#[test]
fn test_buf_writer() {
let mut buf = [0 as u8; 9];
{
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[]).unwrap(), 0);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[8, 9]).unwrap(), 1);
assert_eq!(writer.write(&[10]).unwrap(), 0);
}
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8];
assert_eq!(buf, b);
}
#[test]
fn test_buf_writer_seek() {
let mut buf = [0 as u8; 8];
{
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[1]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.seek(SeekFrom::Start(2)).unwrap(), 2);
assert_eq!(writer.position(), 2);
assert_eq!(writer.write(&[2]).unwrap(), 1);
assert_eq!(writer.position(), 3);
assert_eq!(writer.seek(SeekFrom::Current(-2)).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[3]).unwrap(), 1);
assert_eq!(writer.position(), 2);
assert_eq!(writer.seek(SeekFrom::End(-1)).unwrap(), 7);
assert_eq!(writer.position(), 7);
assert_eq!(writer.write(&[4]).unwrap(), 1);
assert_eq!(writer.position(), 8);
}
let b: &[_] = &[1, 3, 2, 0, 0, 0, 0, 4];
assert_eq!(buf, b);
}
#[test]
fn test_buf_writer_error() {
let mut buf = [0 as u8; 2];
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[0, 0]).unwrap(), 1);
assert_eq!(writer.write(&[0, 0]).unwrap(), 0);
}
#[test]
fn test_mem_reader() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7]);
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.position(), 5);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(buf, b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_boxed_slice_reader() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7].into_boxed_slice());
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.position(), 5);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(buf, b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn read_to_end() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7]);
let mut v = Vec::new();
reader.read_to_end(&mut v).unwrap();
assert_eq!(v, [0, 1, 2, 3, 4, 5, 6, 7]);
}
#[test]
fn test_slice_reader() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let reader = &mut &in_buf[..];
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.len(), 7);
let b: &[_] = &[0];
assert_eq!(&buf[..], b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.len(), 3);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(&buf[..], b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_read_exact() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let reader = &mut &in_buf[..];
let mut buf = [];
assert!(reader.read_exact(&mut buf).is_ok());
let mut buf = [8];
assert!(reader.read_exact(&mut buf).is_ok());
assert_eq!(buf[0], 0);
assert_eq!(reader.len(), 7);
let mut buf = [0, 0, 0, 0, 0, 0, 0];
assert!(reader.read_exact(&mut buf).is_ok());
assert_eq!(buf, [1, 2, 3, 4, 5, 6, 7]);
assert_eq!(reader.len(), 0);
let mut buf = [0];
assert!(reader.read_exact(&mut buf).is_err());
}
#[test]
fn test_buf_reader() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let mut reader = Cursor::new(&in_buf[..]);
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.position(), 5);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(buf, b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_read_char() {
let b = &b"Vi\xE1\xBB\x87t"[..];
let mut c = Cursor::new(b).chars();
assert_eq!(c.next().unwrap().unwrap(), 'V');
assert_eq!(c.next().unwrap().unwrap(), 'i');
assert_eq!(c.next().unwrap().unwrap(), 'ệ');
assert_eq!(c.next().unwrap().unwrap(), 't');
assert!(c.next().is_none());
}
#[test]
fn test_read_bad_char() {
let b = &b"\x80"[..];
let mut c = Cursor::new(b).chars();
assert!(c.next().unwrap().is_err());
}
#[test]
fn seek_past_end() {
let buf = [0xff];
let mut r = Cursor::new(&buf[..]);
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.read(&mut [0]).unwrap(), 0);
let mut r = Cursor::new(vec![10]);
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.read(&mut [0]).unwrap(), 0);
let mut buf = [0];
let mut r = Cursor::new(&mut buf[..]);
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.write(&[3]).unwrap(), 0);
let mut r = Cursor::new(vec![10].into_boxed_slice());
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.write(&[3]).unwrap(), 0);
}
#[test]
fn seek_past_i64() {
let buf = [0xff];
let mut r = Cursor::new(&buf[..]);
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
let mut r = Cursor::new(vec![10]);
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
let mut buf = [0];
let mut r = Cursor::new(&mut buf[..]);
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
let mut r = Cursor::new(vec![10].into_boxed_slice());
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
}
#[test]
fn seek_before_0() {
let buf = [0xff];
let mut r = Cursor::new(&buf[..]);
assert!(r.seek(SeekFrom::End(-2)).is_err());
let mut r = Cursor::new(vec![10]);
assert!(r.seek(SeekFrom::End(-2)).is_err());
let mut buf = [0];
let mut r = Cursor::new(&mut buf[..]);
assert!(r.seek(SeekFrom::End(-2)).is_err());
let mut r = Cursor::new(vec![10].into_boxed_slice());
assert!(r.seek(SeekFrom::End(-2)).is_err());
}
#[test]
fn test_seekable_mem_writer() {
let mut writer = Cursor::new(Vec::<u8>::new());
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.position(), 8);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::Start(0)).unwrap(), 0);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[3, 4]).unwrap(), 2);
let b: &[_] = &[3, 4, 2, 3, 4, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::Current(1)).unwrap(), 3);
assert_eq!(writer.write(&[0, 1]).unwrap(), 2);
let b: &[_] = &[3, 4, 2, 0, 1, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::End(-1)).unwrap(), 7);
assert_eq!(writer.write(&[1, 2]).unwrap(), 2);
let b: &[_] = &[3, 4, 2, 0, 1, 5, 6, 1, 2];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::End(1)).unwrap(), 10);
assert_eq!(writer.write(&[1]).unwrap(), 1);
let b: &[_] = &[3, 4, 2, 0, 1, 5, 6, 1, 2, 0, 1];
assert_eq!(&writer.get_ref()[..], b);
}
#[test]
fn vec_seek_past_end() {
let mut r = Cursor::new(Vec::new());
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.write(&[3]).unwrap(), 1);
}
#[test]
fn vec_seek_before_0() {
let mut r = Cursor::new(Vec::new());
assert!(r.seek(SeekFrom::End(-2)).is_err());
}
#[test]
#[cfg(target_pointer_width = "32")]
fn vec_seek_and_write_past_usize_max() {
let mut c = Cursor::new(Vec::new());
c.set_position(<usize>::max_value() as u64 + 1);
assert!(c.write_all(&[1, 2, 3]).is_err());
}
}

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@ -0,0 +1,538 @@
// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
#[cfg(feature="alloc")] use alloc::boxed::Box;
#[cfg(not(feature="alloc"))] use ::FakeBox as Box;
use core::convert::Into;
use core::fmt;
use core::marker::{Send, Sync};
use core::option::Option::{self, Some, None};
use core::result;
#[cfg(feature="collections")] use collections::string::String;
#[cfg(not(feature="collections"))] use ::ErrorString as String;
use core::convert::From;
/// A specialized [`Result`](../result/enum.Result.html) type for I/O
/// operations.
///
/// This type is broadly used across [`std::io`] for any operation which may
/// produce an error.
///
/// This typedef is generally used to avoid writing out [`io::Error`] directly and
/// is otherwise a direct mapping to [`Result`].
///
/// While usual Rust style is to import types directly, aliases of [`Result`]
/// often are not, to make it easier to distinguish between them. [`Result`] is
/// generally assumed to be [`std::result::Result`][`Result`], and so users of this alias
/// will generally use `io::Result` instead of shadowing the prelude's import
/// of [`std::result::Result`][`Result`].
///
/// [`std::io`]: ../io/index.html
/// [`io::Error`]: ../io/struct.Error.html
/// [`Result`]: ../result/enum.Result.html
///
/// # Examples
///
/// A convenience function that bubbles an `io::Result` to its caller:
///
/// ```
/// use std::io;
///
/// fn get_string() -> io::Result<String> {
/// let mut buffer = String::new();
///
/// io::stdin().read_line(&mut buffer)?;
///
/// Ok(buffer)
/// }
/// ```
pub type Result<T> = result::Result<T, Error>;
/// The error type for I/O operations of the [`Read`], [`Write`], [`Seek`], and
/// associated traits.
///
/// Errors mostly originate from the underlying OS, but custom instances of
/// `Error` can be created with crafted error messages and a particular value of
/// [`ErrorKind`].
///
/// [`Read`]: ../io/trait.Read.html
/// [`Write`]: ../io/trait.Write.html
/// [`Seek`]: ../io/trait.Seek.html
/// [`ErrorKind`]: enum.ErrorKind.html
#[derive(Debug)]
pub struct Error {
repr: Repr,
}
enum Repr {
Os(i32),
Simple(ErrorKind),
#[cfg(feature="alloc")]
Custom(Box<Custom>),
#[cfg(not(feature="alloc"))]
Custom(Custom),
}
#[derive(Debug)]
struct Custom {
kind: ErrorKind,
error: String,
}
/// A list specifying general categories of I/O error.
///
/// This list is intended to grow over time and it is not recommended to
/// exhaustively match against it.
///
/// It is used with the [`io::Error`] type.
///
/// [`io::Error`]: struct.Error.html
#[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
#[allow(deprecated)]
pub enum ErrorKind {
/// An entity was not found, often a file.
NotFound,
/// The operation lacked the necessary privileges to complete.
PermissionDenied,
/// The connection was refused by the remote server.
ConnectionRefused,
/// The connection was reset by the remote server.
ConnectionReset,
/// The connection was aborted (terminated) by the remote server.
ConnectionAborted,
/// The network operation failed because it was not connected yet.
NotConnected,
/// A socket address could not be bound because the address is already in
/// use elsewhere.
AddrInUse,
/// A nonexistent interface was requested or the requested address was not
/// local.
AddrNotAvailable,
/// The operation failed because a pipe was closed.
BrokenPipe,
/// An entity already exists, often a file.
AlreadyExists,
/// The operation needs to block to complete, but the blocking operation was
/// requested to not occur.
WouldBlock,
/// A parameter was incorrect.
InvalidInput,
/// Data not valid for the operation were encountered.
///
/// Unlike [`InvalidInput`], this typically means that the operation
/// parameters were valid, however the error was caused by malformed
/// input data.
///
/// For example, a function that reads a file into a string will error with
/// `InvalidData` if the file's contents are not valid UTF-8.
///
/// [`InvalidInput`]: #variant.InvalidInput
InvalidData,
/// The I/O operation's timeout expired, causing it to be canceled.
TimedOut,
/// An error returned when an operation could not be completed because a
/// call to [`write`] returned [`Ok(0)`].
///
/// This typically means that an operation could only succeed if it wrote a
/// particular number of bytes but only a smaller number of bytes could be
/// written.
///
/// [`write`]: ../../std/io/trait.Write.html#tymethod.write
/// [`Ok(0)`]: ../../std/io/type.Result.html
WriteZero,
/// This operation was interrupted.
///
/// Interrupted operations can typically be retried.
Interrupted,
/// Any I/O error not part of this list.
Other,
/// An error returned when an operation could not be completed because an
/// "end of file" was reached prematurely.
///
/// This typically means that an operation could only succeed if it read a
/// particular number of bytes but only a smaller number of bytes could be
/// read.
UnexpectedEof,
/// A marker variant that tells the compiler that users of this enum cannot
/// match it exhaustively.
#[doc(hidden)]
__Nonexhaustive,
}
impl ErrorKind {
fn as_str(&self) -> &'static str {
match *self {
ErrorKind::NotFound => "entity not found",
ErrorKind::PermissionDenied => "permission denied",
ErrorKind::ConnectionRefused => "connection refused",
ErrorKind::ConnectionReset => "connection reset",
ErrorKind::ConnectionAborted => "connection aborted",
ErrorKind::NotConnected => "not connected",
ErrorKind::AddrInUse => "address in use",
ErrorKind::AddrNotAvailable => "address not available",
ErrorKind::BrokenPipe => "broken pipe",
ErrorKind::AlreadyExists => "entity already exists",
ErrorKind::WouldBlock => "operation would block",
ErrorKind::InvalidInput => "invalid input parameter",
ErrorKind::InvalidData => "invalid data",
ErrorKind::TimedOut => "timed out",
ErrorKind::WriteZero => "write zero",
ErrorKind::Interrupted => "operation interrupted",
ErrorKind::Other => "other os error",
ErrorKind::UnexpectedEof => "unexpected end of file",
ErrorKind::__Nonexhaustive => unreachable!()
}
}
}
/// Intended for use for errors not exposed to the user, where allocating onto
/// the heap (for normal construction via Error::new) is too costly.
impl From<ErrorKind> for Error {
#[inline]
fn from(kind: ErrorKind) -> Error {
Error {
repr: Repr::Simple(kind)
}
}
}
impl Error {
/// Creates a new I/O error from a known kind of error as well as an
/// arbitrary error payload.
///
/// This function is used to generically create I/O errors which do not
/// originate from the OS itself. The `error` argument is an arbitrary
/// payload which will be contained in this `Error`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// // errors can be created from strings
/// let custom_error = Error::new(ErrorKind::Other, "oh no!");
///
/// // errors can also be created from other errors
/// let custom_error2 = Error::new(ErrorKind::Interrupted, custom_error);
/// ```
pub fn new<E>(kind: ErrorKind, error: E) -> Error
where E: Into<String>
{
Self::_new(kind, error.into())
}
fn _new(kind: ErrorKind, error: String) -> Error {
Error {
repr: Repr::Custom(Box::new(Custom {
kind,
error,
}))
}
}
/// Creates a new instance of an `Error` from a particular OS error code.
///
/// # Examples
///
/// On Linux:
///
/// ```
/// # if cfg!(target_os = "linux") {
/// use std::io;
///
/// let error = io::Error::from_raw_os_error(98);
/// assert_eq!(error.kind(), io::ErrorKind::AddrInUse);
/// # }
/// ```
///
/// On Windows:
///
/// ```
/// # if cfg!(windows) {
/// use std::io;
///
/// let error = io::Error::from_raw_os_error(10048);
/// assert_eq!(error.kind(), io::ErrorKind::AddrInUse);
/// # }
/// ```
pub fn from_raw_os_error(code: i32) -> Error {
Error { repr: Repr::Os(code) }
}
/// Returns the OS error that this error represents (if any).
///
/// If this `Error` was constructed via `last_os_error` or
/// `from_raw_os_error`, then this function will return `Some`, otherwise
/// it will return `None`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_os_error(err: &Error) {
/// if let Some(raw_os_err) = err.raw_os_error() {
/// println!("raw OS error: {:?}", raw_os_err);
/// } else {
/// println!("Not an OS error");
/// }
/// }
///
/// fn main() {
/// // Will print "raw OS error: ...".
/// print_os_error(&Error::last_os_error());
/// // Will print "Not an OS error".
/// print_os_error(&Error::new(ErrorKind::Other, "oh no!"));
/// }
/// ```
pub fn raw_os_error(&self) -> Option<i32> {
match self.repr {
Repr::Os(i) => Some(i),
Repr::Custom(..) => None,
Repr::Simple(..) => None,
}
}
/// Returns a reference to the inner error wrapped by this error (if any).
///
/// If this `Error` was constructed via `new` then this function will
/// return `Some`, otherwise it will return `None`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_error(err: &Error) {
/// if let Some(inner_err) = err.get_ref() {
/// println!("Inner error: {:?}", inner_err);
/// } else {
/// println!("No inner error");
/// }
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(&Error::last_os_error());
/// // Will print "Inner error: ...".
/// print_error(&Error::new(ErrorKind::Other, "oh no!"));
/// }
/// ```
pub fn get_ref(&self) -> Option<&String> {
match self.repr {
Repr::Os(..) => None,
Repr::Simple(..) => None,
Repr::Custom(ref c) => Some(&c.error),
}
}
/// Returns a mutable reference to the inner error wrapped by this error
/// (if any).
///
/// If this `Error` was constructed via `new` then this function will
/// return `Some`, otherwise it will return `None`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
/// use std::{error, fmt};
/// use std::fmt::Display;
///
/// #[derive(Debug)]
/// struct MyError {
/// v: String,
/// }
///
/// impl MyError {
/// fn new() -> MyError {
/// MyError {
/// v: "oh no!".to_string()
/// }
/// }
///
/// fn change_message(&mut self, new_message: &str) {
/// self.v = new_message.to_string();
/// }
/// }
///
/// impl error::Error for MyError {
/// fn description(&self) -> &str { &self.v }
/// }
///
/// impl Display for MyError {
/// fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
/// write!(f, "MyError: {}", &self.v)
/// }
/// }
///
/// fn change_error(mut err: Error) -> Error {
/// if let Some(inner_err) = err.get_mut() {
/// inner_err.downcast_mut::<MyError>().unwrap().change_message("I've been changed!");
/// }
/// err
/// }
///
/// fn print_error(err: &Error) {
/// if let Some(inner_err) = err.get_ref() {
/// println!("Inner error: {}", inner_err);
/// } else {
/// println!("No inner error");
/// }
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(&change_error(Error::last_os_error()));
/// // Will print "Inner error: ...".
/// print_error(&change_error(Error::new(ErrorKind::Other, MyError::new())));
/// }
/// ```
pub fn get_mut(&mut self) -> Option<&mut String> {
match self.repr {
Repr::Os(..) => None,
Repr::Simple(..) => None,
Repr::Custom(ref mut c) => Some(&mut c.error),
}
}
/// Consumes the `Error`, returning its inner error (if any).
///
/// If this `Error` was constructed via `new` then this function will
/// return `Some`, otherwise it will return `None`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_error(err: Error) {
/// if let Some(inner_err) = err.into_inner() {
/// println!("Inner error: {}", inner_err);
/// } else {
/// println!("No inner error");
/// }
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(Error::last_os_error());
/// // Will print "Inner error: ...".
/// print_error(Error::new(ErrorKind::Other, "oh no!"));
/// }
/// ```
pub fn into_inner(self) -> Option<String> {
match self.repr {
Repr::Os(..) => None,
Repr::Simple(..) => None,
Repr::Custom(c) => Some(c.error)
}
}
/// Returns the corresponding `ErrorKind` for this error.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_error(err: Error) {
/// println!("{:?}", err.kind());
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(Error::last_os_error());
/// // Will print "Inner error: ...".
/// print_error(Error::new(ErrorKind::AddrInUse, "oh no!"));
/// }
/// ```
pub fn kind(&self) -> ErrorKind {
match self.repr {
Repr::Os(_code) => ErrorKind::Other,
Repr::Custom(ref c) => c.kind,
Repr::Simple(kind) => kind,
}
}
}
impl fmt::Debug for Repr {
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
match *self {
Repr::Os(ref code) =>
fmt.debug_struct("Os").field("code", code).finish(),
Repr::Custom(ref c) => fmt.debug_tuple("Custom").field(c).finish(),
Repr::Simple(kind) => fmt.debug_tuple("Kind").field(&kind).finish(),
}
}
}
impl fmt::Display for Error {
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
match self.repr {
Repr::Os(code) => {
write!(fmt, "os error {}", code)
}
Repr::Custom(ref c) => c.error.fmt(fmt),
Repr::Simple(kind) => write!(fmt, "{}", kind.as_str()),
}
}
}
fn _assert_error_is_sync_send() {
fn _is_sync_send<T: Sync+Send>() {}
_is_sync_send::<Error>();
}
#[cfg(test)]
mod test {
use super::{Error, ErrorKind};
use error;
use fmt;
use sys::os::error_string;
#[test]
fn test_debug_error() {
let code = 6;
let msg = error_string(code);
let err = Error { repr: super::Repr::Os(code) };
let expected = format!("Error {{ repr: Os {{ code: {:?}, message: {:?} }} }}", code, msg);
assert_eq!(format!("{:?}", err), expected);
}
#[test]
fn test_downcasting() {
#[derive(Debug)]
struct TestError;
impl fmt::Display for TestError {
fn fmt(&self, _: &mut fmt::Formatter) -> fmt::Result {
Ok(())
}
}
impl error::Error for TestError {
fn description(&self) -> &str {
"asdf"
}
}
// we have to call all of these UFCS style right now since method
// resolution won't implicitly drop the Send+Sync bounds
let mut err = Error::new(ErrorKind::Other, TestError);
assert!(err.get_ref().unwrap().is::<TestError>());
assert_eq!("asdf", err.get_ref().unwrap().description());
assert!(err.get_mut().unwrap().is::<TestError>());
let extracted = err.into_inner().unwrap();
extracted.downcast::<TestError>().unwrap();
}
}

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// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
#[cfg(feature="alloc")] use alloc::boxed::Box;
use core::cmp;
use io::{self, SeekFrom, Read, Initializer, Write, Seek, Error, ErrorKind};
#[cfg(feature="collections")] use io::BufRead;
use core::fmt;
use core::mem;
#[cfg(feature="collections")] use collections::string::String;
#[cfg(feature="collections")] use collections::vec::Vec;
// =============================================================================
// Forwarding implementations
impl<'a, R: Read + ?Sized> Read for &'a mut R {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
(**self).read(buf)
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
(**self).initializer()
}
#[cfg(feature="collections")]
#[inline]
fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_to_end(buf)
}
#[cfg(feature="collections")]
#[inline]
fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_to_string(buf)
}
#[inline]
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
(**self).read_exact(buf)
}
}
impl<'a, W: Write + ?Sized> Write for &'a mut W {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> { (**self).write(buf) }
#[inline]
fn flush(&mut self) -> io::Result<()> { (**self).flush() }
#[inline]
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
(**self).write_all(buf)
}
#[inline]
fn write_fmt(&mut self, fmt: fmt::Arguments) -> io::Result<()> {
(**self).write_fmt(fmt)
}
}
impl<'a, S: Seek + ?Sized> Seek for &'a mut S {
#[inline]
fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> { (**self).seek(pos) }
}
#[cfg(feature="collections")]
impl<'a, B: BufRead + ?Sized> BufRead for &'a mut B {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> { (**self).fill_buf() }
#[inline]
fn consume(&mut self, amt: usize) { (**self).consume(amt) }
#[inline]
fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_until(byte, buf)
}
#[inline]
fn read_line(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_line(buf)
}
}
#[cfg(feature="alloc")]
impl<R: Read + ?Sized> Read for Box<R> {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
(**self).read(buf)
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
(**self).initializer()
}
#[cfg(feature="collections")]
#[inline]
fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_to_end(buf)
}
#[cfg(feature="collections")]
#[inline]
fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_to_string(buf)
}
#[inline]
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
(**self).read_exact(buf)
}
}
#[cfg(feature="alloc")]
impl<W: Write + ?Sized> Write for Box<W> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> { (**self).write(buf) }
#[inline]
fn flush(&mut self) -> io::Result<()> { (**self).flush() }
#[inline]
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
(**self).write_all(buf)
}
#[inline]
fn write_fmt(&mut self, fmt: fmt::Arguments) -> io::Result<()> {
(**self).write_fmt(fmt)
}
}
#[cfg(feature="alloc")]
impl<S: Seek + ?Sized> Seek for Box<S> {
#[inline]
fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> { (**self).seek(pos) }
}
#[cfg(feature="collections")]
impl<B: BufRead + ?Sized> BufRead for Box<B> {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> { (**self).fill_buf() }
#[inline]
fn consume(&mut self, amt: usize) { (**self).consume(amt) }
#[inline]
fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_until(byte, buf)
}
#[inline]
fn read_line(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_line(buf)
}
}
// =============================================================================
// In-memory buffer implementations
/// Read is implemented for `&[u8]` by copying from the slice.
///
/// Note that reading updates the slice to point to the yet unread part.
/// The slice will be empty when EOF is reached.
impl<'a> Read for &'a [u8] {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
let amt = cmp::min(buf.len(), self.len());
let (a, b) = self.split_at(amt);
// First check if the amount of bytes we want to read is small:
// `copy_from_slice` will generally expand to a call to `memcpy`, and
// for a single byte the overhead is significant.
if amt == 1 {
buf[0] = a[0];
} else {
buf[..amt].copy_from_slice(a);
}
*self = b;
Ok(amt)
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
#[inline]
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
if buf.len() > self.len() {
return Err(Error::new(ErrorKind::UnexpectedEof,
"failed to fill whole buffer"));
}
let (a, b) = self.split_at(buf.len());
// First check if the amount of bytes we want to read is small:
// `copy_from_slice` will generally expand to a call to `memcpy`, and
// for a single byte the overhead is significant.
if buf.len() == 1 {
buf[0] = a[0];
} else {
buf.copy_from_slice(a);
}
*self = b;
Ok(())
}
#[cfg(feature="collections")]
#[inline]
fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
buf.extend_from_slice(*self);
let len = self.len();
*self = &self[len..];
Ok(len)
}
}
#[cfg(feature="collections")]
impl<'a> BufRead for &'a [u8] {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> { Ok(*self) }
#[inline]
fn consume(&mut self, amt: usize) { *self = &self[amt..]; }
}
/// Write is implemented for `&mut [u8]` by copying into the slice, overwriting
/// its data.
///
/// Note that writing updates the slice to point to the yet unwritten part.
/// The slice will be empty when it has been completely overwritten.
impl<'a> Write for &'a mut [u8] {
#[inline]
fn write(&mut self, data: &[u8]) -> io::Result<usize> {
let amt = cmp::min(data.len(), self.len());
let (a, b) = mem::replace(self, &mut []).split_at_mut(amt);
a.copy_from_slice(&data[..amt]);
*self = b;
Ok(amt)
}
#[inline]
fn write_all(&mut self, data: &[u8]) -> io::Result<()> {
if self.write(data)? == data.len() {
Ok(())
} else {
Err(Error::new(ErrorKind::WriteZero, "failed to write whole buffer"))
}
}
#[inline]
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
/// Write is implemented for `Vec<u8>` by appending to the vector.
/// The vector will grow as needed.
#[cfg(feature="collections")]
impl Write for Vec<u8> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
self.extend_from_slice(buf);
Ok(buf.len())
}
#[inline]
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
self.extend_from_slice(buf);
Ok(())
}
#[inline]
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
#[cfg(test)]
mod tests {
use io::prelude::*;
use test;
#[bench]
fn bench_read_slice(b: &mut test::Bencher) {
let buf = [5; 1024];
let mut dst = [0; 128];
b.iter(|| {
let mut rd = &buf[..];
for _ in 0..8 {
let _ = rd.read(&mut dst);
test::black_box(&dst);
}
})
}
#[bench]
fn bench_write_slice(b: &mut test::Bencher) {
let mut buf = [0; 1024];
let src = [5; 128];
b.iter(|| {
let mut wr = &mut buf[..];
for _ in 0..8 {
let _ = wr.write_all(&src);
test::black_box(&wr);
}
})
}
#[bench]
fn bench_read_vec(b: &mut test::Bencher) {
let buf = vec![5; 1024];
let mut dst = [0; 128];
b.iter(|| {
let mut rd = &buf[..];
for _ in 0..8 {
let _ = rd.read(&mut dst);
test::black_box(&dst);
}
})
}
#[bench]
fn bench_write_vec(b: &mut test::Bencher) {
let mut buf = Vec::with_capacity(1024);
let src = [5; 128];
b.iter(|| {
let mut wr = &mut buf[..];
for _ in 0..8 {
let _ = wr.write_all(&src);
test::black_box(&wr);
}
})
}
}

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// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//
// Original implementation taken from rust-memchr
// Copyright 2015 Andrew Gallant, bluss and Nicolas Koch
pub use self::fallback::{memchr,memrchr};
#[allow(dead_code)]
pub mod fallback {
use core::cmp;
use core::mem;
const LO_U64: u64 = 0x0101010101010101;
const HI_U64: u64 = 0x8080808080808080;
// use truncation
const LO_USIZE: usize = LO_U64 as usize;
const HI_USIZE: usize = HI_U64 as usize;
/// Return `true` if `x` contains any zero byte.
///
/// From *Matters Computational*, J. Arndt
///
/// "The idea is to subtract one from each of the bytes and then look for
/// bytes where the borrow propagated all the way to the most significant
/// bit."
#[inline]
fn contains_zero_byte(x: usize) -> bool {
x.wrapping_sub(LO_USIZE) & !x & HI_USIZE != 0
}
#[cfg(target_pointer_width = "32")]
#[inline]
fn repeat_byte(b: u8) -> usize {
let mut rep = (b as usize) << 8 | b as usize;
rep = rep << 16 | rep;
rep
}
#[cfg(target_pointer_width = "64")]
#[inline]
fn repeat_byte(b: u8) -> usize {
let mut rep = (b as usize) << 8 | b as usize;
rep = rep << 16 | rep;
rep = rep << 32 | rep;
rep
}
/// Return the first index matching the byte `a` in `text`.
pub fn memchr(x: u8, text: &[u8]) -> Option<usize> {
// Scan for a single byte value by reading two `usize` words at a time.
//
// Split `text` in three parts
// - unaligned initial part, before the first word aligned address in text
// - body, scan by 2 words at a time
// - the last remaining part, < 2 word size
let len = text.len();
let ptr = text.as_ptr();
let usize_bytes = mem::size_of::<usize>();
// search up to an aligned boundary
let mut offset = ptr.align_offset(usize_bytes);
if offset > 0 {
offset = cmp::min(offset, len);
if let Some(index) = text[..offset].iter().position(|elt| *elt == x) {
return Some(index);
}
}
// search the body of the text
let repeated_x = repeat_byte(x);
if len >= 2 * usize_bytes {
while offset <= len - 2 * usize_bytes {
unsafe {
let u = *(ptr.offset(offset as isize) as *const usize);
let v = *(ptr.offset((offset + usize_bytes) as isize) as *const usize);
// break if there is a matching byte
let zu = contains_zero_byte(u ^ repeated_x);
let zv = contains_zero_byte(v ^ repeated_x);
if zu || zv {
break;
}
}
offset += usize_bytes * 2;
}
}
// find the byte after the point the body loop stopped
text[offset..].iter().position(|elt| *elt == x).map(|i| offset + i)
}
/// Return the last index matching the byte `a` in `text`.
pub fn memrchr(x: u8, text: &[u8]) -> Option<usize> {
// Scan for a single byte value by reading two `usize` words at a time.
//
// Split `text` in three parts
// - unaligned tail, after the last word aligned address in text
// - body, scan by 2 words at a time
// - the first remaining bytes, < 2 word size
let len = text.len();
let ptr = text.as_ptr();
let usize_bytes = mem::size_of::<usize>();
// search to an aligned boundary
let end_align = (ptr as usize + len) & (usize_bytes - 1);
let mut offset;
if end_align > 0 {
offset = if end_align >= len { 0 } else { len - end_align };
if let Some(index) = text[offset..].iter().rposition(|elt| *elt == x) {
return Some(offset + index);
}
} else {
offset = len;
}
// search the body of the text
let repeated_x = repeat_byte(x);
while offset >= 2 * usize_bytes {
unsafe {
let u = *(ptr.offset(offset as isize - 2 * usize_bytes as isize) as *const usize);
let v = *(ptr.offset(offset as isize - usize_bytes as isize) as *const usize);
// break if there is a matching byte
let zu = contains_zero_byte(u ^ repeated_x);
let zv = contains_zero_byte(v ^ repeated_x);
if zu || zv {
break;
}
}
offset -= 2 * usize_bytes;
}
// find the byte before the point the body loop stopped
text[..offset].iter().rposition(|elt| *elt == x)
}
// test fallback implementations on all platforms
#[test]
fn matches_one() {
assert_eq!(Some(0), memchr(b'a', b"a"));
}
#[test]
fn matches_begin() {
assert_eq!(Some(0), memchr(b'a', b"aaaa"));
}
#[test]
fn matches_end() {
assert_eq!(Some(4), memchr(b'z', b"aaaaz"));
}
#[test]
fn matches_nul() {
assert_eq!(Some(4), memchr(b'\x00', b"aaaa\x00"));
}
#[test]
fn matches_past_nul() {
assert_eq!(Some(5), memchr(b'z', b"aaaa\x00z"));
}
#[test]
fn no_match_empty() {
assert_eq!(None, memchr(b'a', b""));
}
#[test]
fn no_match() {
assert_eq!(None, memchr(b'a', b"xyz"));
}
#[test]
fn matches_one_reversed() {
assert_eq!(Some(0), memrchr(b'a', b"a"));
}
#[test]
fn matches_begin_reversed() {
assert_eq!(Some(3), memrchr(b'a', b"aaaa"));
}
#[test]
fn matches_end_reversed() {
assert_eq!(Some(0), memrchr(b'z', b"zaaaa"));
}
#[test]
fn matches_nul_reversed() {
assert_eq!(Some(4), memrchr(b'\x00', b"aaaa\x00"));
}
#[test]
fn matches_past_nul_reversed() {
assert_eq!(Some(0), memrchr(b'z', b"z\x00aaaa"));
}
#[test]
fn no_match_empty_reversed() {
assert_eq!(None, memrchr(b'a', b""));
}
#[test]
fn no_match_reversed() {
assert_eq!(None, memrchr(b'a', b"xyz"));
}
#[test]
fn each_alignment_reversed() {
let mut data = [1u8; 64];
let needle = 2;
let pos = 40;
data[pos] = needle;
for start in 0..16 {
assert_eq!(Some(pos - start), memrchr(needle, &data[start..]));
}
}
}

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// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//! The I/O Prelude
//!
//! The purpose of this module is to alleviate imports of many common I/O traits
//! by adding a glob import to the top of I/O heavy modules:
//!
//! ```
//! # #![allow(unused_imports)]
//! use std::io::prelude::*;
//! ```
pub use super::{Read, Write, Seek};
#[cfg(feature="collections")] pub use super::BufRead;
#[cfg(feature="collections")] pub use alloc::boxed::Box;
#[cfg(feature="collections")] pub use collections::vec::Vec;

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// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
#![allow(missing_copy_implementations)]
use core::fmt;
use io::{self, Read, Initializer, Write, ErrorKind};
use core::mem;
#[cfg(feature="collections")] use io::BufRead;
/// Copies the entire contents of a reader into a writer.
///
/// This function will continuously read data from `reader` and then
/// write it into `writer` in a streaming fashion until `reader`
/// returns EOF.
///
/// On success, the total number of bytes that were copied from
/// `reader` to `writer` is returned.
///
/// # Errors
///
/// This function will return an error immediately if any call to `read` or
/// `write` returns an error. All instances of `ErrorKind::Interrupted` are
/// handled by this function and the underlying operation is retried.
///
/// # Examples
///
/// ```
/// use std::io;
///
/// # fn foo() -> io::Result<()> {
/// let mut reader: &[u8] = b"hello";
/// let mut writer: Vec<u8> = vec![];
///
/// io::copy(&mut reader, &mut writer)?;
///
/// assert_eq!(&b"hello"[..], &writer[..]);
/// # Ok(())
/// # }
/// # foo().unwrap();
/// ```
pub fn copy<R: ?Sized, W: ?Sized>(reader: &mut R, writer: &mut W) -> io::Result<u64>
where R: Read, W: Write
{
let mut buf = unsafe {
let mut buf: [u8; super::DEFAULT_BUF_SIZE] = mem::uninitialized();
reader.initializer().initialize(&mut buf);
buf
};
let mut written = 0;
loop {
let len = match reader.read(&mut buf) {
Ok(0) => return Ok(written),
Ok(len) => len,
Err(ref e) if e.kind() == ErrorKind::Interrupted => continue,
Err(e) => return Err(e),
};
writer.write_all(&buf[..len])?;
written += len as u64;
}
}
/// A reader which is always at EOF.
///
/// This struct is generally created by calling [`empty`]. Please see
/// the documentation of [`empty()`][`empty`] for more details.
///
/// [`empty`]: fn.empty.html
pub struct Empty { _priv: () }
/// Constructs a new handle to an empty reader.
///
/// All reads from the returned reader will return [`Ok`]`(0)`.
///
/// [`Ok`]: ../result/enum.Result.html#variant.Ok
///
/// # Examples
///
/// A slightly sad example of not reading anything into a buffer:
///
/// ```
/// use std::io::{self, Read};
///
/// let mut buffer = String::new();
/// io::empty().read_to_string(&mut buffer).unwrap();
/// assert!(buffer.is_empty());
/// ```
pub fn empty() -> Empty { Empty { _priv: () } }
impl Read for Empty {
#[inline]
fn read(&mut self, _buf: &mut [u8]) -> io::Result<usize> { Ok(0) }
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
}
#[cfg(feature="collections")]
impl BufRead for Empty {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> { Ok(&[]) }
#[inline]
fn consume(&mut self, _n: usize) {}
}
impl fmt::Debug for Empty {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.pad("Empty { .. }")
}
}
/// A reader which yields one byte over and over and over and over and over and...
///
/// This struct is generally created by calling [`repeat`][repeat]. Please
/// see the documentation of `repeat()` for more details.
///
/// [repeat]: fn.repeat.html
pub struct Repeat { byte: u8 }
/// Creates an instance of a reader that infinitely repeats one byte.
///
/// All reads from this reader will succeed by filling the specified buffer with
/// the given byte.
///
/// # Examples
///
/// ```
/// use std::io::{self, Read};
///
/// let mut buffer = [0; 3];
/// io::repeat(0b101).read_exact(&mut buffer).unwrap();
/// assert_eq!(buffer, [0b101, 0b101, 0b101]);
/// ```
pub fn repeat(byte: u8) -> Repeat { Repeat { byte: byte } }
impl Read for Repeat {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
for slot in &mut *buf {
*slot = self.byte;
}
Ok(buf.len())
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
}
impl fmt::Debug for Repeat {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.pad("Repeat { .. }")
}
}
/// A writer which will move data into the void.
///
/// This struct is generally created by calling [`sink`][sink]. Please
/// see the documentation of `sink()` for more details.
///
/// [sink]: fn.sink.html
pub struct Sink { _priv: () }
/// Creates an instance of a writer which will successfully consume all data.
///
/// All calls to `write` on the returned instance will return `Ok(buf.len())`
/// and the contents of the buffer will not be inspected.
///
/// # Examples
///
/// ```rust
/// use std::io::{self, Write};
///
/// let buffer = vec![1, 2, 3, 5, 8];
/// let num_bytes = io::sink().write(&buffer).unwrap();
/// assert_eq!(num_bytes, 5);
/// ```
pub fn sink() -> Sink { Sink { _priv: () } }
impl Write for Sink {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> { Ok(buf.len()) }
#[inline]
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
impl fmt::Debug for Sink {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.pad("Sink { .. }")
}
}
#[cfg(test)]
mod tests {
use io::prelude::*;
use io::{copy, sink, empty, repeat};
#[test]
fn copy_copies() {
let mut r = repeat(0).take(4);
let mut w = sink();
assert_eq!(copy(&mut r, &mut w).unwrap(), 4);
let mut r = repeat(0).take(1 << 17);
assert_eq!(copy(&mut r as &mut Read, &mut w as &mut Write).unwrap(), 1 << 17);
}
#[test]
fn sink_sinks() {
let mut s = sink();
assert_eq!(s.write(&[]).unwrap(), 0);
assert_eq!(s.write(&[0]).unwrap(), 1);
assert_eq!(s.write(&[0; 1024]).unwrap(), 1024);
assert_eq!(s.by_ref().write(&[0; 1024]).unwrap(), 1024);
}
#[test]
fn empty_reads() {
let mut e = empty();
assert_eq!(e.read(&mut []).unwrap(), 0);
assert_eq!(e.read(&mut [0]).unwrap(), 0);
assert_eq!(e.read(&mut [0; 1024]).unwrap(), 0);
assert_eq!(e.by_ref().read(&mut [0; 1024]).unwrap(), 0);
}
#[test]
fn repeat_repeats() {
let mut r = repeat(4);
let mut b = [0; 1024];
assert_eq!(r.read(&mut b).unwrap(), 1024);
assert!(b.iter().all(|b| *b == 4));
}
#[test]
fn take_some_bytes() {
assert_eq!(repeat(4).take(100).bytes().count(), 100);
assert_eq!(repeat(4).take(100).bytes().next().unwrap().unwrap(), 4);
assert_eq!(repeat(1).take(10).chain(repeat(2).take(10)).bytes().count(), 20);
}
}

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// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use core::prelude::v1::*;
use io::prelude::*;
#[cfg(feature = "collections")] use core::convert::TryInto;
use core::cmp;
use io::{self, SeekFrom, Error, ErrorKind};
/// A `Cursor` wraps another type and provides it with a
/// [`Seek`] implementation.
///
/// `Cursor`s are typically used with in-memory buffers to allow them to
/// implement [`Read`] and/or [`Write`], allowing these buffers to be used
/// anywhere you might use a reader or writer that does actual I/O.
///
/// The standard library implements some I/O traits on various types which
/// are commonly used as a buffer, like `Cursor<`[`Vec`]`<u8>>` and
/// `Cursor<`[`&[u8]`][bytes]`>`.
///
/// # Examples
///
/// We may want to write bytes to a [`File`] in our production
/// code, but use an in-memory buffer in our tests. We can do this with
/// `Cursor`:
///
/// [`Seek`]: trait.Seek.html
/// [`Read`]: ../../std/io/trait.Read.html
/// [`Write`]: ../../std/io/trait.Write.html
/// [`Vec`]: ../../std/vec/struct.Vec.html
/// [bytes]: ../../std/primitive.slice.html
/// [`File`]: ../fs/struct.File.html
///
/// ```no_run
/// use std::io::prelude::*;
/// use std::io::{self, SeekFrom};
/// use std::fs::File;
///
/// // a library function we've written
/// fn write_ten_bytes_at_end<W: Write + Seek>(writer: &mut W) -> io::Result<()> {
/// writer.seek(SeekFrom::End(-10))?;
///
/// for i in 0..10 {
/// writer.write(&[i])?;
/// }
///
/// // all went well
/// Ok(())
/// }
///
/// # fn foo() -> io::Result<()> {
/// // Here's some code that uses this library function.
/// //
/// // We might want to use a BufReader here for efficiency, but let's
/// // keep this example focused.
/// let mut file = File::create("foo.txt")?;
///
/// write_ten_bytes_at_end(&mut file)?;
/// # Ok(())
/// # }
///
/// // now let's write a test
/// #[test]
/// fn test_writes_bytes() {
/// // setting up a real File is much more slow than an in-memory buffer,
/// // let's use a cursor instead
/// use std::io::Cursor;
/// let mut buff = Cursor::new(vec![0; 15]);
///
/// write_ten_bytes_at_end(&mut buff).unwrap();
///
/// assert_eq!(&buff.get_ref()[5..15], &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
/// }
/// ```
#[derive(Clone, Debug)]
pub struct Cursor<T> {
inner: T,
pos: u64,
}
impl<T> Cursor<T> {
/// Creates a new cursor wrapping the provided underlying I/O object.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
/// ```
pub fn new(inner: T) -> Cursor<T> {
Cursor { pos: 0, inner: inner }
}
/// Consumes this cursor, returning the underlying value.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
///
/// let vec = buff.into_inner();
/// ```
pub fn into_inner(self) -> T { self.inner }
/// Gets a reference to the underlying value in this cursor.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
///
/// let reference = buff.get_ref();
/// ```
pub fn get_ref(&self) -> &T { &self.inner }
/// Gets a mutable reference to the underlying value in this cursor.
///
/// Care should be taken to avoid modifying the internal I/O state of the
/// underlying value as it may corrupt this cursor's position.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let mut buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
///
/// let reference = buff.get_mut();
/// ```
pub fn get_mut(&mut self) -> &mut T { &mut self.inner }
/// Returns the current position of this cursor.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
/// use std::io::prelude::*;
/// use std::io::SeekFrom;
///
/// let mut buff = Cursor::new(vec![1, 2, 3, 4, 5]);
///
/// assert_eq!(buff.position(), 0);
///
/// buff.seek(SeekFrom::Current(2)).unwrap();
/// assert_eq!(buff.position(), 2);
///
/// buff.seek(SeekFrom::Current(-1)).unwrap();
/// assert_eq!(buff.position(), 1);
/// ```
pub fn position(&self) -> u64 { self.pos }
/// Sets the position of this cursor.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let mut buff = Cursor::new(vec![1, 2, 3, 4, 5]);
///
/// assert_eq!(buff.position(), 0);
///
/// buff.set_position(2);
/// assert_eq!(buff.position(), 2);
///
/// buff.set_position(4);
/// assert_eq!(buff.position(), 4);
/// ```
pub fn set_position(&mut self, pos: u64) { self.pos = pos; }
}
impl<T> io::Seek for Cursor<T> where T: AsRef<[u8]> {
fn seek(&mut self, style: SeekFrom) -> io::Result<u64> {
let (base_pos, offset) = match style {
SeekFrom::Start(n) => { self.pos = n; return Ok(n); }
SeekFrom::End(n) => (self.inner.as_ref().len() as u64, n),
SeekFrom::Current(n) => (self.pos, n),
};
let new_pos = if offset >= 0 {
base_pos.checked_add(offset as u64)
} else {
base_pos.checked_sub((offset.wrapping_neg()) as u64)
};
match new_pos {
Some(n) => {self.pos = n; Ok(self.pos)}
None => Err(Error::new(ErrorKind::InvalidInput,
"invalid seek to a negative or overflowing position"))
}
}
}
impl<T> Read for Cursor<T> where T: AsRef<[u8]> {
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
let n = Read::read(&mut self.get_buf()?, buf)?;
self.pos += n as u64;
Ok(n)
}
}
impl<T> Cursor<T> where T: AsRef<[u8]> {
fn get_buf(&mut self) -> io::Result<&[u8]> {
let amt = cmp::min(self.pos, self.inner.as_ref().len() as u64);
Ok(&self.inner.as_ref()[(amt as usize)..])
}
}
#[cfg(feature = "collections")]
impl<T> BufRead for Cursor<T> where T: AsRef<[u8]> {
fn fill_buf(&mut self) -> io::Result<&[u8]> { self.get_buf() }
fn consume(&mut self, amt: usize) { self.pos += amt as u64; }
}
impl<'a> Write for Cursor<&'a mut [u8]> {
#[inline]
fn write(&mut self, data: &[u8]) -> io::Result<usize> {
let pos = cmp::min(self.pos, self.inner.len() as u64);
let amt = (&mut self.inner[(pos as usize)..]).write(data)?;
self.pos += amt as u64;
Ok(amt)
}
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
#[cfg(feature = "collections")]
impl Write for Cursor<Vec<u8>> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
let pos: usize = self.position().try_into().map_err(|_| {
Error::new(ErrorKind::InvalidInput,
"cursor position exceeds maximum possible vector length")
})?;
// Make sure the internal buffer is as least as big as where we
// currently are
let len = self.inner.len();
if len < pos {
// use `resize` so that the zero filling is as efficient as possible
self.inner.resize(pos, 0);
}
// Figure out what bytes will be used to overwrite what's currently
// there (left), and what will be appended on the end (right)
{
let space = self.inner.len() - pos;
let (left, right) = buf.split_at(cmp::min(space, buf.len()));
self.inner[pos..pos + left.len()].copy_from_slice(left);
self.inner.extend_from_slice(right);
}
// Bump us forward
self.set_position((pos + buf.len()) as u64);
Ok(buf.len())
}
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
#[cfg(feature = "alloc")]
impl Write for Cursor<::alloc::boxed::Box<[u8]>> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
let pos = cmp::min(self.pos, self.inner.len() as u64);
let amt = (&mut self.inner[(pos as usize)..]).write(buf)?;
self.pos += amt as u64;
Ok(amt)
}
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
#[cfg(test)]
mod tests {
use io::prelude::*;
use io::{Cursor, SeekFrom};
#[test]
fn test_vec_writer() {
let mut writer = Vec::new();
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7];
assert_eq!(writer, b);
}
#[test]
fn test_mem_writer() {
let mut writer = Cursor::new(Vec::new());
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
}
#[test]
fn test_box_slice_writer() {
let mut writer = Cursor::new(vec![0u8; 9].into_boxed_slice());
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[]).unwrap(), 0);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[8, 9]).unwrap(), 1);
assert_eq!(writer.write(&[10]).unwrap(), 0);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8];
assert_eq!(&**writer.get_ref(), b);
}
#[test]
fn test_buf_writer() {
let mut buf = [0 as u8; 9];
{
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[]).unwrap(), 0);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[8, 9]).unwrap(), 1);
assert_eq!(writer.write(&[10]).unwrap(), 0);
}
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8];
assert_eq!(buf, b);
}
#[test]
fn test_buf_writer_seek() {
let mut buf = [0 as u8; 8];
{
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[1]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.seek(SeekFrom::Start(2)).unwrap(), 2);
assert_eq!(writer.position(), 2);
assert_eq!(writer.write(&[2]).unwrap(), 1);
assert_eq!(writer.position(), 3);
assert_eq!(writer.seek(SeekFrom::Current(-2)).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[3]).unwrap(), 1);
assert_eq!(writer.position(), 2);
assert_eq!(writer.seek(SeekFrom::End(-1)).unwrap(), 7);
assert_eq!(writer.position(), 7);
assert_eq!(writer.write(&[4]).unwrap(), 1);
assert_eq!(writer.position(), 8);
}
let b: &[_] = &[1, 3, 2, 0, 0, 0, 0, 4];
assert_eq!(buf, b);
}
#[test]
fn test_buf_writer_error() {
let mut buf = [0 as u8; 2];
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[0, 0]).unwrap(), 1);
assert_eq!(writer.write(&[0, 0]).unwrap(), 0);
}
#[test]
fn test_mem_reader() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7]);
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.position(), 5);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(buf, b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_boxed_slice_reader() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7].into_boxed_slice());
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.position(), 5);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(buf, b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn read_to_end() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7]);
let mut v = Vec::new();
reader.read_to_end(&mut v).unwrap();
assert_eq!(v, [0, 1, 2, 3, 4, 5, 6, 7]);
}
#[test]
fn test_slice_reader() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let mut reader = &mut &in_buf[..];
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.len(), 7);
let b: &[_] = &[0];
assert_eq!(&buf[..], b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.len(), 3);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(&buf[..], b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_buf_reader() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let mut reader = Cursor::new(&in_buf[..]);
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.position(), 5);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(buf, b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_read_char() {
let b = &b"Vi\xE1\xBB\x87t"[..];
let mut c = Cursor::new(b).chars();
assert_eq!(c.next().unwrap().unwrap(), 'V');
assert_eq!(c.next().unwrap().unwrap(), 'i');
assert_eq!(c.next().unwrap().unwrap(), 'ệ');
assert_eq!(c.next().unwrap().unwrap(), 't');
assert!(c.next().is_none());
}
#[test]
fn test_read_bad_char() {
let b = &b"\x80"[..];
let mut c = Cursor::new(b).chars();
assert!(c.next().unwrap().is_err());
}
#[test]
fn seek_past_end() {
let buf = [0xff];
let mut r = Cursor::new(&buf[..]);
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.read(&mut [0]).unwrap(), 0);
let mut r = Cursor::new(vec![10]);
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.read(&mut [0]).unwrap(), 0);
let mut buf = [0];
let mut r = Cursor::new(&mut buf[..]);
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.write(&[3]).unwrap(), 0);
let mut r = Cursor::new(vec![10].into_boxed_slice());
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.write(&[3]).unwrap(), 0);
}
#[test]
fn seek_past_i64() {
let buf = [0xff];
let mut r = Cursor::new(&buf[..]);
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
let mut r = Cursor::new(vec![10]);
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
let mut buf = [0];
let mut r = Cursor::new(&mut buf[..]);
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
let mut r = Cursor::new(vec![10].into_boxed_slice());
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
}
#[test]
fn seek_before_0() {
let buf = [0xff];
let mut r = Cursor::new(&buf[..]);
assert!(r.seek(SeekFrom::End(-2)).is_err());
let mut r = Cursor::new(vec![10]);
assert!(r.seek(SeekFrom::End(-2)).is_err());
let mut buf = [0];
let mut r = Cursor::new(&mut buf[..]);
assert!(r.seek(SeekFrom::End(-2)).is_err());
let mut r = Cursor::new(vec![10].into_boxed_slice());
assert!(r.seek(SeekFrom::End(-2)).is_err());
}
#[test]
fn test_seekable_mem_writer() {
let mut writer = Cursor::new(Vec::<u8>::new());
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.position(), 8);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::Start(0)).unwrap(), 0);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[3, 4]).unwrap(), 2);
let b: &[_] = &[3, 4, 2, 3, 4, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::Current(1)).unwrap(), 3);
assert_eq!(writer.write(&[0, 1]).unwrap(), 2);
let b: &[_] = &[3, 4, 2, 0, 1, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::End(-1)).unwrap(), 7);
assert_eq!(writer.write(&[1, 2]).unwrap(), 2);
let b: &[_] = &[3, 4, 2, 0, 1, 5, 6, 1, 2];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::End(1)).unwrap(), 10);
assert_eq!(writer.write(&[1]).unwrap(), 1);
let b: &[_] = &[3, 4, 2, 0, 1, 5, 6, 1, 2, 0, 1];
assert_eq!(&writer.get_ref()[..], b);
}
#[test]
fn vec_seek_past_end() {
let mut r = Cursor::new(Vec::new());
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.write(&[3]).unwrap(), 1);
}
#[test]
fn vec_seek_before_0() {
let mut r = Cursor::new(Vec::new());
assert!(r.seek(SeekFrom::End(-2)).is_err());
}
#[test]
#[cfg(target_pointer_width = "32")]
fn vec_seek_and_write_past_usize_max() {
let mut c = Cursor::new(Vec::new());
c.set_position(<usize>::max_value() as u64 + 1);
assert!(c.write_all(&[1, 2, 3]).is_err());
}
}

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@ -0,0 +1,530 @@
// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
#[cfg(feature="alloc")] use alloc::boxed::Box;
#[cfg(not(feature="alloc"))] use ::FakeBox as Box;
use core::convert::Into;
use core::fmt;
use core::marker::{Send, Sync};
use core::option::Option::{self, Some, None};
use core::result;
#[cfg(feature="collections")] use collections::string::String;
#[cfg(not(feature="collections"))] use ::ErrorString as String;
use core::convert::From;
/// A specialized [`Result`](../result/enum.Result.html) type for I/O
/// operations.
///
/// This type is broadly used across `std::io` for any operation which may
/// produce an error.
///
/// This typedef is generally used to avoid writing out `io::Error` directly and
/// is otherwise a direct mapping to `Result`.
///
/// While usual Rust style is to import types directly, aliases of `Result`
/// often are not, to make it easier to distinguish between them. `Result` is
/// generally assumed to be `std::result::Result`, and so users of this alias
/// will generally use `io::Result` instead of shadowing the prelude's import
/// of `std::result::Result`.
///
/// # Examples
///
/// A convenience function that bubbles an `io::Result` to its caller:
///
/// ```
/// use std::io;
///
/// fn get_string() -> io::Result<String> {
/// let mut buffer = String::new();
///
/// io::stdin().read_line(&mut buffer)?;
///
/// Ok(buffer)
/// }
/// ```
pub type Result<T> = result::Result<T, Error>;
/// The error type for I/O operations of the `Read`, `Write`, `Seek`, and
/// associated traits.
///
/// Errors mostly originate from the underlying OS, but custom instances of
/// `Error` can be created with crafted error messages and a particular value of
/// [`ErrorKind`].
///
/// [`ErrorKind`]: enum.ErrorKind.html
#[derive(Debug)]
pub struct Error {
repr: Repr,
}
enum Repr {
Os(i32),
Simple(ErrorKind),
#[cfg(feature="alloc")]
Custom(Box<Custom>),
#[cfg(not(feature="alloc"))]
Custom(Custom),
}
#[derive(Debug)]
struct Custom {
kind: ErrorKind,
error: String,
}
/// A list specifying general categories of I/O error.
///
/// This list is intended to grow over time and it is not recommended to
/// exhaustively match against it.
///
/// It is used with the [`io::Error`] type.
///
/// [`io::Error`]: struct.Error.html
#[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
#[allow(deprecated)]
pub enum ErrorKind {
/// An entity was not found, often a file.
NotFound,
/// The operation lacked the necessary privileges to complete.
PermissionDenied,
/// The connection was refused by the remote server.
ConnectionRefused,
/// The connection was reset by the remote server.
ConnectionReset,
/// The connection was aborted (terminated) by the remote server.
ConnectionAborted,
/// The network operation failed because it was not connected yet.
NotConnected,
/// A socket address could not be bound because the address is already in
/// use elsewhere.
AddrInUse,
/// A nonexistent interface was requested or the requested address was not
/// local.
AddrNotAvailable,
/// The operation failed because a pipe was closed.
BrokenPipe,
/// An entity already exists, often a file.
AlreadyExists,
/// The operation needs to block to complete, but the blocking operation was
/// requested to not occur.
WouldBlock,
/// A parameter was incorrect.
InvalidInput,
/// Data not valid for the operation were encountered.
///
/// Unlike [`InvalidInput`], this typically means that the operation
/// parameters were valid, however the error was caused by malformed
/// input data.
///
/// For example, a function that reads a file into a string will error with
/// `InvalidData` if the file's contents are not valid UTF-8.
///
/// [`InvalidInput`]: #variant.InvalidInput
InvalidData,
/// The I/O operation's timeout expired, causing it to be canceled.
TimedOut,
/// An error returned when an operation could not be completed because a
/// call to [`write()`] returned [`Ok(0)`].
///
/// This typically means that an operation could only succeed if it wrote a
/// particular number of bytes but only a smaller number of bytes could be
/// written.
///
/// [`write()`]: ../../std/io/trait.Write.html#tymethod.write
/// [`Ok(0)`]: ../../std/io/type.Result.html
WriteZero,
/// This operation was interrupted.
///
/// Interrupted operations can typically be retried.
Interrupted,
/// Any I/O error not part of this list.
Other,
/// An error returned when an operation could not be completed because an
/// "end of file" was reached prematurely.
///
/// This typically means that an operation could only succeed if it read a
/// particular number of bytes but only a smaller number of bytes could be
/// read.
UnexpectedEof,
/// A marker variant that tells the compiler that users of this enum cannot
/// match it exhaustively.
#[doc(hidden)]
__Nonexhaustive,
}
impl ErrorKind {
fn as_str(&self) -> &'static str {
match *self {
ErrorKind::NotFound => "entity not found",
ErrorKind::PermissionDenied => "permission denied",
ErrorKind::ConnectionRefused => "connection refused",
ErrorKind::ConnectionReset => "connection reset",
ErrorKind::ConnectionAborted => "connection aborted",
ErrorKind::NotConnected => "not connected",
ErrorKind::AddrInUse => "address in use",
ErrorKind::AddrNotAvailable => "address not available",
ErrorKind::BrokenPipe => "broken pipe",
ErrorKind::AlreadyExists => "entity already exists",
ErrorKind::WouldBlock => "operation would block",
ErrorKind::InvalidInput => "invalid input parameter",
ErrorKind::InvalidData => "invalid data",
ErrorKind::TimedOut => "timed out",
ErrorKind::WriteZero => "write zero",
ErrorKind::Interrupted => "operation interrupted",
ErrorKind::Other => "other os error",
ErrorKind::UnexpectedEof => "unexpected end of file",
ErrorKind::__Nonexhaustive => unreachable!()
}
}
}
/// Intended for use for errors not exposed to the user, where allocating onto
/// the heap (for normal construction via Error::new) is too costly.
impl From<ErrorKind> for Error {
fn from(kind: ErrorKind) -> Error {
Error {
repr: Repr::Simple(kind)
}
}
}
impl Error {
/// Creates a new I/O error from a known kind of error as well as an
/// arbitrary error payload.
///
/// This function is used to generically create I/O errors which do not
/// originate from the OS itself. The `error` argument is an arbitrary
/// payload which will be contained in this `Error`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// // errors can be created from strings
/// let custom_error = Error::new(ErrorKind::Other, "oh no!");
///
/// // errors can also be created from other errors
/// let custom_error2 = Error::new(ErrorKind::Interrupted, custom_error);
/// ```
pub fn new<E>(kind: ErrorKind, error: E) -> Error
where E: Into<String>
{
Self::_new(kind, error.into())
}
fn _new(kind: ErrorKind, error: String) -> Error {
Error {
repr: Repr::Custom(Box::new(Custom {
kind: kind,
error: error,
}))
}
}
/// Creates a new instance of an `Error` from a particular OS error code.
///
/// # Examples
///
/// On Linux:
///
/// ```
/// # if cfg!(target_os = "linux") {
/// use std::io;
///
/// let error = io::Error::from_raw_os_error(98);
/// assert_eq!(error.kind(), io::ErrorKind::AddrInUse);
/// # }
/// ```
///
/// On Windows:
///
/// ```
/// # if cfg!(windows) {
/// use std::io;
///
/// let error = io::Error::from_raw_os_error(10048);
/// assert_eq!(error.kind(), io::ErrorKind::AddrInUse);
/// # }
/// ```
pub fn from_raw_os_error(code: i32) -> Error {
Error { repr: Repr::Os(code) }
}
/// Returns the OS error that this error represents (if any).
///
/// If this `Error` was constructed via `last_os_error` or
/// `from_raw_os_error`, then this function will return `Some`, otherwise
/// it will return `None`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_os_error(err: &Error) {
/// if let Some(raw_os_err) = err.raw_os_error() {
/// println!("raw OS error: {:?}", raw_os_err);
/// } else {
/// println!("Not an OS error");
/// }
/// }
///
/// fn main() {
/// // Will print "raw OS error: ...".
/// print_os_error(&Error::last_os_error());
/// // Will print "Not an OS error".
/// print_os_error(&Error::new(ErrorKind::Other, "oh no!"));
/// }
/// ```
pub fn raw_os_error(&self) -> Option<i32> {
match self.repr {
Repr::Os(i) => Some(i),
Repr::Custom(..) => None,
Repr::Simple(..) => None,
}
}
/// Returns a reference to the inner error wrapped by this error (if any).
///
/// If this `Error` was constructed via `new` then this function will
/// return `Some`, otherwise it will return `None`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_error(err: &Error) {
/// if let Some(inner_err) = err.get_ref() {
/// println!("Inner error: {:?}", inner_err);
/// } else {
/// println!("No inner error");
/// }
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(&Error::last_os_error());
/// // Will print "Inner error: ...".
/// print_error(&Error::new(ErrorKind::Other, "oh no!"));
/// }
/// ```
pub fn get_ref(&self) -> Option<&String> {
match self.repr {
Repr::Os(..) => None,
Repr::Simple(..) => None,
Repr::Custom(ref c) => Some(&c.error),
}
}
/// Returns a mutable reference to the inner error wrapped by this error
/// (if any).
///
/// If this `Error` was constructed via `new` then this function will
/// return `Some`, otherwise it will return `None`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
/// use std::{error, fmt};
/// use std::fmt::Display;
///
/// #[derive(Debug)]
/// struct MyError {
/// v: String,
/// }
///
/// impl MyError {
/// fn new() -> MyError {
/// MyError {
/// v: "oh no!".to_string()
/// }
/// }
///
/// fn change_message(&mut self, new_message: &str) {
/// self.v = new_message.to_string();
/// }
/// }
///
/// impl error::Error for MyError {
/// fn description(&self) -> &str { &self.v }
/// }
///
/// impl Display for MyError {
/// fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
/// write!(f, "MyError: {}", &self.v)
/// }
/// }
///
/// fn change_error(mut err: Error) -> Error {
/// if let Some(inner_err) = err.get_mut() {
/// inner_err.downcast_mut::<MyError>().unwrap().change_message("I've been changed!");
/// }
/// err
/// }
///
/// fn print_error(err: &Error) {
/// if let Some(inner_err) = err.get_ref() {
/// println!("Inner error: {}", inner_err);
/// } else {
/// println!("No inner error");
/// }
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(&change_error(Error::last_os_error()));
/// // Will print "Inner error: ...".
/// print_error(&change_error(Error::new(ErrorKind::Other, MyError::new())));
/// }
/// ```
pub fn get_mut(&mut self) -> Option<&mut String> {
match self.repr {
Repr::Os(..) => None,
Repr::Simple(..) => None,
Repr::Custom(ref mut c) => Some(&mut c.error),
}
}
/// Consumes the `Error`, returning its inner error (if any).
///
/// If this `Error` was constructed via `new` then this function will
/// return `Some`, otherwise it will return `None`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_error(err: Error) {
/// if let Some(inner_err) = err.into_inner() {
/// println!("Inner error: {}", inner_err);
/// } else {
/// println!("No inner error");
/// }
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(Error::last_os_error());
/// // Will print "Inner error: ...".
/// print_error(Error::new(ErrorKind::Other, "oh no!"));
/// }
/// ```
pub fn into_inner(self) -> Option<String> {
match self.repr {
Repr::Os(..) => None,
Repr::Simple(..) => None,
Repr::Custom(c) => Some(c.error)
}
}
/// Returns the corresponding `ErrorKind` for this error.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_error(err: Error) {
/// println!("{:?}", err.kind());
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(Error::last_os_error());
/// // Will print "Inner error: ...".
/// print_error(Error::new(ErrorKind::AddrInUse, "oh no!"));
/// }
/// ```
pub fn kind(&self) -> ErrorKind {
match self.repr {
Repr::Os(_code) => ErrorKind::Other,
Repr::Custom(ref c) => c.kind,
Repr::Simple(kind) => kind,
}
}
}
impl fmt::Debug for Repr {
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
match *self {
Repr::Os(ref code) =>
fmt.debug_struct("Os").field("code", code).finish(),
Repr::Custom(ref c) => fmt.debug_tuple("Custom").field(c).finish(),
Repr::Simple(kind) => fmt.debug_tuple("Kind").field(&kind).finish(),
}
}
}
impl fmt::Display for Error {
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
match self.repr {
Repr::Os(code) => {
write!(fmt, "os error {}", code)
}
Repr::Custom(ref c) => c.error.fmt(fmt),
Repr::Simple(kind) => write!(fmt, "{}", kind.as_str()),
}
}
}
fn _assert_error_is_sync_send() {
fn _is_sync_send<T: Sync+Send>() {}
_is_sync_send::<Error>();
}
#[cfg(test)]
mod test {
use super::{Error, ErrorKind};
use error;
use fmt;
use sys::os::error_string;
#[test]
fn test_debug_error() {
let code = 6;
let msg = error_string(code);
let err = Error { repr: super::Repr::Os(code) };
let expected = format!("Error {{ repr: Os {{ code: {:?}, message: {:?} }} }}", code, msg);
assert_eq!(format!("{:?}", err), expected);
}
#[test]
fn test_downcasting() {
#[derive(Debug)]
struct TestError;
impl fmt::Display for TestError {
fn fmt(&self, _: &mut fmt::Formatter) -> fmt::Result {
Ok(())
}
}
impl error::Error for TestError {
fn description(&self) -> &str {
"asdf"
}
}
// we have to call all of these UFCS style right now since method
// resolution won't implicitly drop the Send+Sync bounds
let mut err = Error::new(ErrorKind::Other, TestError);
assert!(err.get_ref().unwrap().is::<TestError>());
assert_eq!("asdf", err.get_ref().unwrap().description());
assert!(err.get_mut().unwrap().is::<TestError>());
let extracted = err.into_inner().unwrap();
extracted.downcast::<TestError>().unwrap();
}
}

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@ -0,0 +1,317 @@
// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
#[cfg(feature="alloc")] use alloc::boxed::Box;
use core::cmp;
use io::{self, SeekFrom, Read, Write, Seek, Error, ErrorKind};
#[cfg(feature="collections")] use io::BufRead;
use core::fmt;
use core::mem;
#[cfg(feature="collections")] use collections::string::String;
#[cfg(feature="collections")] use collections::vec::Vec;
// =============================================================================
// Forwarding implementations
impl<'a, R: Read + ?Sized> Read for &'a mut R {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
(**self).read(buf)
}
#[cfg(feature="collections")]
#[inline]
fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_to_end(buf)
}
#[cfg(feature="collections")]
#[inline]
fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_to_string(buf)
}
#[inline]
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
(**self).read_exact(buf)
}
}
impl<'a, W: Write + ?Sized> Write for &'a mut W {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> { (**self).write(buf) }
#[inline]
fn flush(&mut self) -> io::Result<()> { (**self).flush() }
#[inline]
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
(**self).write_all(buf)
}
#[inline]
fn write_fmt(&mut self, fmt: fmt::Arguments) -> io::Result<()> {
(**self).write_fmt(fmt)
}
}
impl<'a, S: Seek + ?Sized> Seek for &'a mut S {
#[inline]
fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> { (**self).seek(pos) }
}
#[cfg(feature="collections")]
impl<'a, B: BufRead + ?Sized> BufRead for &'a mut B {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> { (**self).fill_buf() }
#[inline]
fn consume(&mut self, amt: usize) { (**self).consume(amt) }
#[inline]
fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_until(byte, buf)
}
#[inline]
fn read_line(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_line(buf)
}
}
#[cfg(feature="alloc")]
impl<R: Read + ?Sized> Read for Box<R> {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
(**self).read(buf)
}
#[cfg(feature="collections")]
#[inline]
fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_to_end(buf)
}
#[cfg(feature="collections")]
#[inline]
fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_to_string(buf)
}
#[inline]
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
(**self).read_exact(buf)
}
}
#[cfg(feature="alloc")]
impl<W: Write + ?Sized> Write for Box<W> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> { (**self).write(buf) }
#[inline]
fn flush(&mut self) -> io::Result<()> { (**self).flush() }
#[inline]
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
(**self).write_all(buf)
}
#[inline]
fn write_fmt(&mut self, fmt: fmt::Arguments) -> io::Result<()> {
(**self).write_fmt(fmt)
}
}
#[cfg(feature="alloc")]
impl<S: Seek + ?Sized> Seek for Box<S> {
#[inline]
fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> { (**self).seek(pos) }
}
#[cfg(feature="collections")]
impl<B: BufRead + ?Sized> BufRead for Box<B> {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> { (**self).fill_buf() }
#[inline]
fn consume(&mut self, amt: usize) { (**self).consume(amt) }
#[inline]
fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_until(byte, buf)
}
#[inline]
fn read_line(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_line(buf)
}
}
// =============================================================================
// In-memory buffer implementations
/// Read is implemented for `&[u8]` by copying from the slice.
///
/// Note that reading updates the slice to point to the yet unread part.
/// The slice will be empty when EOF is reached.
impl<'a> Read for &'a [u8] {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
let amt = cmp::min(buf.len(), self.len());
let (a, b) = self.split_at(amt);
// First check if the amount of bytes we want to read is small:
// `copy_from_slice` will generally expand to a call to `memcpy`, and
// for a single byte the overhead is significant.
if amt == 1 {
buf[0] = a[0];
} else {
buf[..amt].copy_from_slice(a);
}
*self = b;
Ok(amt)
}
#[inline]
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
if buf.len() > self.len() {
return Err(Error::new(ErrorKind::UnexpectedEof,
"failed to fill whole buffer"));
}
let (a, b) = self.split_at(buf.len());
// First check if the amount of bytes we want to read is small:
// `copy_from_slice` will generally expand to a call to `memcpy`, and
// for a single byte the overhead is significant.
if buf.len() == 1 {
buf[0] = a[0];
} else {
buf.copy_from_slice(a);
}
*self = b;
Ok(())
}
}
#[cfg(feature="collections")]
impl<'a> BufRead for &'a [u8] {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> { Ok(*self) }
#[inline]
fn consume(&mut self, amt: usize) { *self = &self[amt..]; }
}
/// Write is implemented for `&mut [u8]` by copying into the slice, overwriting
/// its data.
///
/// Note that writing updates the slice to point to the yet unwritten part.
/// The slice will be empty when it has been completely overwritten.
impl<'a> Write for &'a mut [u8] {
#[inline]
fn write(&mut self, data: &[u8]) -> io::Result<usize> {
let amt = cmp::min(data.len(), self.len());
let (a, b) = mem::replace(self, &mut []).split_at_mut(amt);
a.copy_from_slice(&data[..amt]);
*self = b;
Ok(amt)
}
#[inline]
fn write_all(&mut self, data: &[u8]) -> io::Result<()> {
if self.write(data)? == data.len() {
Ok(())
} else {
Err(Error::new(ErrorKind::WriteZero, "failed to write whole buffer"))
}
}
#[inline]
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
/// Write is implemented for `Vec<u8>` by appending to the vector.
/// The vector will grow as needed.
#[cfg(feature="collections")]
impl Write for Vec<u8> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
self.extend_from_slice(buf);
Ok(buf.len())
}
#[inline]
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
self.extend_from_slice(buf);
Ok(())
}
#[inline]
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
#[cfg(test)]
mod tests {
use io::prelude::*;
use test;
#[bench]
fn bench_read_slice(b: &mut test::Bencher) {
let buf = [5; 1024];
let mut dst = [0; 128];
b.iter(|| {
let mut rd = &buf[..];
for _ in 0..8 {
let _ = rd.read(&mut dst);
test::black_box(&dst);
}
})
}
#[bench]
fn bench_write_slice(b: &mut test::Bencher) {
let mut buf = [0; 1024];
let src = [5; 128];
b.iter(|| {
let mut wr = &mut buf[..];
for _ in 0..8 {
let _ = wr.write_all(&src);
test::black_box(&wr);
}
})
}
#[bench]
fn bench_read_vec(b: &mut test::Bencher) {
let buf = vec![5; 1024];
let mut dst = [0; 128];
b.iter(|| {
let mut rd = &buf[..];
for _ in 0..8 {
let _ = rd.read(&mut dst);
test::black_box(&dst);
}
})
}
#[bench]
fn bench_write_vec(b: &mut test::Bencher) {
let mut buf = Vec::with_capacity(1024);
let src = [5; 128];
b.iter(|| {
let mut wr = &mut buf[..];
for _ in 0..8 {
let _ = wr.write_all(&src);
test::black_box(&wr);
}
})
}
}

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// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//
// Original implementation taken from rust-memchr
// Copyright 2015 Andrew Gallant, bluss and Nicolas Koch
pub use self::fallback::{memchr,memrchr};
#[allow(dead_code)]
pub mod fallback {
use core::cmp;
use core::mem;
const LO_U64: u64 = 0x0101010101010101;
const HI_U64: u64 = 0x8080808080808080;
// use truncation
const LO_USIZE: usize = LO_U64 as usize;
const HI_USIZE: usize = HI_U64 as usize;
/// Return `true` if `x` contains any zero byte.
///
/// From *Matters Computational*, J. Arndt
///
/// "The idea is to subtract one from each of the bytes and then look for
/// bytes where the borrow propagated all the way to the most significant
/// bit."
#[inline]
fn contains_zero_byte(x: usize) -> bool {
x.wrapping_sub(LO_USIZE) & !x & HI_USIZE != 0
}
#[cfg(target_pointer_width = "32")]
#[inline]
fn repeat_byte(b: u8) -> usize {
let mut rep = (b as usize) << 8 | b as usize;
rep = rep << 16 | rep;
rep
}
#[cfg(target_pointer_width = "64")]
#[inline]
fn repeat_byte(b: u8) -> usize {
let mut rep = (b as usize) << 8 | b as usize;
rep = rep << 16 | rep;
rep = rep << 32 | rep;
rep
}
/// Return the first index matching the byte `a` in `text`.
pub fn memchr(x: u8, text: &[u8]) -> Option<usize> {
// Scan for a single byte value by reading two `usize` words at a time.
//
// Split `text` in three parts
// - unaligned initial part, before the first word aligned address in text
// - body, scan by 2 words at a time
// - the last remaining part, < 2 word size
let len = text.len();
let ptr = text.as_ptr();
let usize_bytes = mem::size_of::<usize>();
// search up to an aligned boundary
let align = (ptr as usize) & (usize_bytes- 1);
let mut offset;
if align > 0 {
offset = cmp::min(usize_bytes - align, len);
if let Some(index) = text[..offset].iter().position(|elt| *elt == x) {
return Some(index);
}
} else {
offset = 0;
}
// search the body of the text
let repeated_x = repeat_byte(x);
if len >= 2 * usize_bytes {
while offset <= len - 2 * usize_bytes {
unsafe {
let u = *(ptr.offset(offset as isize) as *const usize);
let v = *(ptr.offset((offset + usize_bytes) as isize) as *const usize);
// break if there is a matching byte
let zu = contains_zero_byte(u ^ repeated_x);
let zv = contains_zero_byte(v ^ repeated_x);
if zu || zv {
break;
}
}
offset += usize_bytes * 2;
}
}
// find the byte after the point the body loop stopped
text[offset..].iter().position(|elt| *elt == x).map(|i| offset + i)
}
/// Return the last index matching the byte `a` in `text`.
pub fn memrchr(x: u8, text: &[u8]) -> Option<usize> {
// Scan for a single byte value by reading two `usize` words at a time.
//
// Split `text` in three parts
// - unaligned tail, after the last word aligned address in text
// - body, scan by 2 words at a time
// - the first remaining bytes, < 2 word size
let len = text.len();
let ptr = text.as_ptr();
let usize_bytes = mem::size_of::<usize>();
// search to an aligned boundary
let end_align = (ptr as usize + len) & (usize_bytes - 1);
let mut offset;
if end_align > 0 {
offset = if end_align >= len { 0 } else { len - end_align };
if let Some(index) = text[offset..].iter().rposition(|elt| *elt == x) {
return Some(offset + index);
}
} else {
offset = len;
}
// search the body of the text
let repeated_x = repeat_byte(x);
while offset >= 2 * usize_bytes {
unsafe {
let u = *(ptr.offset(offset as isize - 2 * usize_bytes as isize) as *const usize);
let v = *(ptr.offset(offset as isize - usize_bytes as isize) as *const usize);
// break if there is a matching byte
let zu = contains_zero_byte(u ^ repeated_x);
let zv = contains_zero_byte(v ^ repeated_x);
if zu || zv {
break;
}
}
offset -= 2 * usize_bytes;
}
// find the byte before the point the body loop stopped
text[..offset].iter().rposition(|elt| *elt == x)
}
// test fallback implementations on all platforms
#[test]
fn matches_one() {
assert_eq!(Some(0), memchr(b'a', b"a"));
}
#[test]
fn matches_begin() {
assert_eq!(Some(0), memchr(b'a', b"aaaa"));
}
#[test]
fn matches_end() {
assert_eq!(Some(4), memchr(b'z', b"aaaaz"));
}
#[test]
fn matches_nul() {
assert_eq!(Some(4), memchr(b'\x00', b"aaaa\x00"));
}
#[test]
fn matches_past_nul() {
assert_eq!(Some(5), memchr(b'z', b"aaaa\x00z"));
}
#[test]
fn no_match_empty() {
assert_eq!(None, memchr(b'a', b""));
}
#[test]
fn no_match() {
assert_eq!(None, memchr(b'a', b"xyz"));
}
#[test]
fn matches_one_reversed() {
assert_eq!(Some(0), memrchr(b'a', b"a"));
}
#[test]
fn matches_begin_reversed() {
assert_eq!(Some(3), memrchr(b'a', b"aaaa"));
}
#[test]
fn matches_end_reversed() {
assert_eq!(Some(0), memrchr(b'z', b"zaaaa"));
}
#[test]
fn matches_nul_reversed() {
assert_eq!(Some(4), memrchr(b'\x00', b"aaaa\x00"));
}
#[test]
fn matches_past_nul_reversed() {
assert_eq!(Some(0), memrchr(b'z', b"z\x00aaaa"));
}
#[test]
fn no_match_empty_reversed() {
assert_eq!(None, memrchr(b'a', b""));
}
#[test]
fn no_match_reversed() {
assert_eq!(None, memrchr(b'a', b"xyz"));
}
#[test]
fn each_alignment_reversed() {
let mut data = [1u8; 64];
let needle = 2;
let pos = 40;
data[pos] = needle;
for start in 0..16 {
assert_eq!(Some(pos - start), memrchr(needle, &data[start..]));
}
}
}

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// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//! The I/O Prelude
//!
//! The purpose of this module is to alleviate imports of many common I/O traits
//! by adding a glob import to the top of I/O heavy modules:
//!
//! ```
//! # #![allow(unused_imports)]
//! use std::io::prelude::*;
//! ```
pub use super::{Read, Write, Seek};
#[cfg(feature="collections")] pub use super::BufRead;
#[cfg(feature="collections")] pub use alloc::boxed::Box;
#[cfg(feature="collections")] pub use collections::vec::Vec;

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// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
#![allow(missing_copy_implementations)]
use core::fmt;
use io::{self, Read, Write, ErrorKind};
#[cfg(feature="collections")] use io::BufRead;
/// Copies the entire contents of a reader into a writer.
///
/// This function will continuously read data from `reader` and then
/// write it into `writer` in a streaming fashion until `reader`
/// returns EOF.
///
/// On success, the total number of bytes that were copied from
/// `reader` to `writer` is returned.
///
/// # Errors
///
/// This function will return an error immediately if any call to `read` or
/// `write` returns an error. All instances of `ErrorKind::Interrupted` are
/// handled by this function and the underlying operation is retried.
///
/// # Examples
///
/// ```
/// use std::io;
///
/// # fn foo() -> io::Result<()> {
/// let mut reader: &[u8] = b"hello";
/// let mut writer: Vec<u8> = vec![];
///
/// io::copy(&mut reader, &mut writer)?;
///
/// assert_eq!(reader, &writer[..]);
/// # Ok(())
/// # }
/// ```
pub fn copy<R: ?Sized, W: ?Sized>(reader: &mut R, writer: &mut W) -> io::Result<u64>
where R: Read, W: Write
{
let mut buf = [0; super::DEFAULT_BUF_SIZE];
let mut written = 0;
loop {
let len = match reader.read(&mut buf) {
Ok(0) => return Ok(written),
Ok(len) => len,
Err(ref e) if e.kind() == ErrorKind::Interrupted => continue,
Err(e) => return Err(e),
};
writer.write_all(&buf[..len])?;
written += len as u64;
}
}
/// A reader which is always at EOF.
///
/// This struct is generally created by calling [`empty()`][empty]. Please see
/// the documentation of `empty()` for more details.
///
/// [empty]: fn.empty.html
pub struct Empty { _priv: () }
/// Constructs a new handle to an empty reader.
///
/// All reads from the returned reader will return `Ok(0)`.
///
/// # Examples
///
/// A slightly sad example of not reading anything into a buffer:
///
/// ```
/// use std::io::{self, Read};
///
/// let mut buffer = String::new();
/// io::empty().read_to_string(&mut buffer).unwrap();
/// assert!(buffer.is_empty());
/// ```
pub fn empty() -> Empty { Empty { _priv: () } }
impl Read for Empty {
fn read(&mut self, _buf: &mut [u8]) -> io::Result<usize> { Ok(0) }
}
#[cfg(feature="collections")]
impl BufRead for Empty {
fn fill_buf(&mut self) -> io::Result<&[u8]> { Ok(&[]) }
fn consume(&mut self, _n: usize) {}
}
impl fmt::Debug for Empty {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.pad("Empty { .. }")
}
}
/// A reader which yields one byte over and over and over and over and over and...
///
/// This struct is generally created by calling [`repeat()`][repeat]. Please
/// see the documentation of `repeat()` for more details.
///
/// [repeat]: fn.repeat.html
pub struct Repeat { byte: u8 }
/// Creates an instance of a reader that infinitely repeats one byte.
///
/// All reads from this reader will succeed by filling the specified buffer with
/// the given byte.
///
/// # Examples
///
/// ```
/// use std::io::{self, Read};
///
/// let mut buffer = [0; 3];
/// io::repeat(0b101).read_exact(&mut buffer).unwrap();
/// assert_eq!(buffer, [0b101, 0b101, 0b101]);
/// ```
pub fn repeat(byte: u8) -> Repeat { Repeat { byte: byte } }
impl Read for Repeat {
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
for slot in &mut *buf {
*slot = self.byte;
}
Ok(buf.len())
}
}
impl fmt::Debug for Repeat {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.pad("Repeat { .. }")
}
}
/// A writer which will move data into the void.
///
/// This struct is generally created by calling [`sink()`][sink]. Please
/// see the documentation of `sink()` for more details.
///
/// [sink]: fn.sink.html
pub struct Sink { _priv: () }
/// Creates an instance of a writer which will successfully consume all data.
///
/// All calls to `write` on the returned instance will return `Ok(buf.len())`
/// and the contents of the buffer will not be inspected.
///
/// # Examples
///
/// ```rust
/// use std::io::{self, Write};
///
/// let buffer = vec![1, 2, 3, 5, 8];
/// let num_bytes = io::sink().write(&buffer).unwrap();
/// assert_eq!(num_bytes, 5);
/// ```
pub fn sink() -> Sink { Sink { _priv: () } }
impl Write for Sink {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> { Ok(buf.len()) }
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
impl fmt::Debug for Sink {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.pad("Sink { .. }")
}
}
#[cfg(test)]
mod tests {
use io::prelude::*;
use io::{copy, sink, empty, repeat};
#[test]
fn copy_copies() {
let mut r = repeat(0).take(4);
let mut w = sink();
assert_eq!(copy(&mut r, &mut w).unwrap(), 4);
let mut r = repeat(0).take(1 << 17);
assert_eq!(copy(&mut r as &mut Read, &mut w as &mut Write).unwrap(), 1 << 17);
}
#[test]
fn sink_sinks() {
let mut s = sink();
assert_eq!(s.write(&[]).unwrap(), 0);
assert_eq!(s.write(&[0]).unwrap(), 1);
assert_eq!(s.write(&[0; 1024]).unwrap(), 1024);
assert_eq!(s.by_ref().write(&[0; 1024]).unwrap(), 1024);
}
#[test]
fn empty_reads() {
let mut e = empty();
assert_eq!(e.read(&mut []).unwrap(), 0);
assert_eq!(e.read(&mut [0]).unwrap(), 0);
assert_eq!(e.read(&mut [0; 1024]).unwrap(), 0);
assert_eq!(e.by_ref().read(&mut [0; 1024]).unwrap(), 0);
}
#[test]
fn repeat_repeats() {
let mut r = repeat(4);
let mut b = [0; 1024];
assert_eq!(r.read(&mut b).unwrap(), 1024);
assert!(b.iter().all(|b| *b == 4));
}
#[test]
fn take_some_bytes() {
assert_eq!(repeat(4).take(100).bytes().count(), 100);
assert_eq!(repeat(4).take(100).bytes().next().unwrap().unwrap(), 4);
assert_eq!(repeat(1).take(10).chain(repeat(2).take(10)).bytes().count(), 20);
}
}

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use crate::io::prelude::*;
use core::cmp;
use crate::io::{self, Error, ErrorKind, Initializer, IoSlice, IoSliceMut, SeekFrom};
#[cfg(feature="collections")] use core::convert::TryInto;
/// A `Cursor` wraps an in-memory buffer and provides it with a
/// [`Seek`] implementation.
///
/// `Cursor`s are used with in-memory buffers, anything implementing
/// `AsRef<[u8]>`, to allow them to implement [`Read`] and/or [`Write`],
/// allowing these buffers to be used anywhere you might use a reader or writer
/// that does actual I/O.
///
/// The standard library implements some I/O traits on various types which
/// are commonly used as a buffer, like `Cursor<`[`Vec`]`<u8>>` and
/// `Cursor<`[`&[u8]`][bytes]`>`.
///
/// # Examples
///
/// We may want to write bytes to a [`File`] in our production
/// code, but use an in-memory buffer in our tests. We can do this with
/// `Cursor`:
///
/// [`Seek`]: trait.Seek.html
/// [`Read`]: ../../std/io/trait.Read.html
/// [`Write`]: ../../std/io/trait.Write.html
/// [`Vec`]: ../../std/vec/struct.Vec.html
/// [bytes]: ../../std/primitive.slice.html
/// [`File`]: ../fs/struct.File.html
///
/// ```no_run
/// use std::io::prelude::*;
/// use std::io::{self, SeekFrom};
/// use std::fs::File;
///
/// // a library function we've written
/// fn write_ten_bytes_at_end<W: Write + Seek>(writer: &mut W) -> io::Result<()> {
/// writer.seek(SeekFrom::End(-10))?;
///
/// for i in 0..10 {
/// writer.write(&[i])?;
/// }
///
/// // all went well
/// Ok(())
/// }
///
/// # fn foo() -> io::Result<()> {
/// // Here's some code that uses this library function.
/// //
/// // We might want to use a BufReader here for efficiency, but let's
/// // keep this example focused.
/// let mut file = File::create("foo.txt")?;
///
/// write_ten_bytes_at_end(&mut file)?;
/// # Ok(())
/// # }
///
/// // now let's write a test
/// #[test]
/// fn test_writes_bytes() {
/// // setting up a real File is much slower than an in-memory buffer,
/// // let's use a cursor instead
/// use std::io::Cursor;
/// let mut buff = Cursor::new(vec![0; 15]);
///
/// write_ten_bytes_at_end(&mut buff).unwrap();
///
/// assert_eq!(&buff.get_ref()[5..15], &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
/// }
/// ```
#[derive(Clone, Debug, Default, Eq, PartialEq)]
pub struct Cursor<T> {
inner: T,
pos: u64,
}
impl<T> Cursor<T> {
/// Creates a new cursor wrapping the provided underlying in-memory buffer.
///
/// Cursor initial position is `0` even if underlying buffer (e.g., `Vec`)
/// is not empty. So writing to cursor starts with overwriting `Vec`
/// content, not with appending to it.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
/// ```
pub fn new(inner: T) -> Cursor<T> {
Cursor { pos: 0, inner }
}
/// Consumes this cursor, returning the underlying value.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
///
/// let vec = buff.into_inner();
/// ```
pub fn into_inner(self) -> T {
self.inner
}
/// Gets a reference to the underlying value in this cursor.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
///
/// let reference = buff.get_ref();
/// ```
pub fn get_ref(&self) -> &T {
&self.inner
}
/// Gets a mutable reference to the underlying value in this cursor.
///
/// Care should be taken to avoid modifying the internal I/O state of the
/// underlying value as it may corrupt this cursor's position.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let mut buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
///
/// let reference = buff.get_mut();
/// ```
pub fn get_mut(&mut self) -> &mut T {
&mut self.inner
}
/// Returns the current position of this cursor.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
/// use std::io::prelude::*;
/// use std::io::SeekFrom;
///
/// let mut buff = Cursor::new(vec![1, 2, 3, 4, 5]);
///
/// assert_eq!(buff.position(), 0);
///
/// buff.seek(SeekFrom::Current(2)).unwrap();
/// assert_eq!(buff.position(), 2);
///
/// buff.seek(SeekFrom::Current(-1)).unwrap();
/// assert_eq!(buff.position(), 1);
/// ```
pub fn position(&self) -> u64 {
self.pos
}
/// Sets the position of this cursor.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let mut buff = Cursor::new(vec![1, 2, 3, 4, 5]);
///
/// assert_eq!(buff.position(), 0);
///
/// buff.set_position(2);
/// assert_eq!(buff.position(), 2);
///
/// buff.set_position(4);
/// assert_eq!(buff.position(), 4);
/// ```
pub fn set_position(&mut self, pos: u64) {
self.pos = pos;
}
}
impl<T> io::Seek for Cursor<T>
where
T: AsRef<[u8]>,
{
fn seek(&mut self, style: SeekFrom) -> io::Result<u64> {
let (base_pos, offset) = match style {
SeekFrom::Start(n) => {
self.pos = n;
return Ok(n);
}
SeekFrom::End(n) => (self.inner.as_ref().len() as u64, n),
SeekFrom::Current(n) => (self.pos, n),
};
let new_pos = if offset >= 0 {
base_pos.checked_add(offset as u64)
} else {
base_pos.checked_sub((offset.wrapping_neg()) as u64)
};
match new_pos {
Some(n) => {
self.pos = n;
Ok(self.pos)
}
None => Err(Error::new(
ErrorKind::InvalidInput,
"invalid seek to a negative or overflowing position",
)),
}
}
fn stream_len(&mut self) -> io::Result<u64> {
Ok(self.inner.as_ref().len() as u64)
}
fn stream_position(&mut self) -> io::Result<u64> {
Ok(self.pos)
}
}
impl<T> Read for Cursor<T>
where
T: AsRef<[u8]>,
{
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
let n = Read::read(&mut self.get_buf()?, buf)?;
self.pos += n as u64;
Ok(n)
}
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
let mut nread = 0;
for buf in bufs {
let n = self.read(buf)?;
nread += n;
if n < buf.len() {
break;
}
}
Ok(nread)
}
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
let n = buf.len();
Read::read_exact(&mut self.get_buf()?, buf)?;
self.pos += n as u64;
Ok(())
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
}
impl<T> Cursor<T>
where
T: AsRef<[u8]>,
{
fn get_buf(&mut self) -> io::Result<&[u8]> {
let amt = cmp::min(self.pos, self.inner.as_ref().len() as u64);
Ok(&self.inner.as_ref()[(amt as usize)..])
}
}
#[cfg(feature="collections")]
impl<T> BufRead for Cursor<T>
where
T: AsRef<[u8]>,
{
fn fill_buf(&mut self) -> io::Result<&[u8]> {
self.get_buf()
}
fn consume(&mut self, amt: usize) {
self.pos += amt as u64;
}
}
// Non-resizing write implementation
#[inline]
fn slice_write(pos_mut: &mut u64, slice: &mut [u8], buf: &[u8]) -> io::Result<usize> {
let pos = cmp::min(*pos_mut, slice.len() as u64);
let amt = (&mut slice[(pos as usize)..]).write(buf)?;
*pos_mut += amt as u64;
Ok(amt)
}
#[inline]
fn slice_write_vectored(
pos_mut: &mut u64,
slice: &mut [u8],
bufs: &[IoSlice<'_>],
) -> io::Result<usize> {
let mut nwritten = 0;
for buf in bufs {
let n = slice_write(pos_mut, slice, buf)?;
nwritten += n;
if n < buf.len() {
break;
}
}
Ok(nwritten)
}
// Resizing write implementation
#[cfg(feature="collections")]
fn vec_write(pos_mut: &mut u64, vec: &mut Vec<u8>, buf: &[u8]) -> io::Result<usize> {
let pos: usize = (*pos_mut).try_into().map_err(|_| {
Error::new(
ErrorKind::InvalidInput,
"cursor position exceeds maximum possible vector length",
)
})?;
// Make sure the internal buffer is as least as big as where we
// currently are
let len = vec.len();
if len < pos {
// use `resize` so that the zero filling is as efficient as possible
vec.resize(pos, 0);
}
// Figure out what bytes will be used to overwrite what's currently
// there (left), and what will be appended on the end (right)
{
let space = vec.len() - pos;
let (left, right) = buf.split_at(cmp::min(space, buf.len()));
vec[pos..pos + left.len()].copy_from_slice(left);
vec.extend_from_slice(right);
}
// Bump us forward
*pos_mut = (pos + buf.len()) as u64;
Ok(buf.len())
}
#[cfg(feature="collections")]
fn vec_write_vectored(
pos_mut: &mut u64,
vec: &mut Vec<u8>,
bufs: &[IoSlice<'_>],
) -> io::Result<usize> {
let mut nwritten = 0;
for buf in bufs {
nwritten += vec_write(pos_mut, vec, buf)?;
}
Ok(nwritten)
}
impl Write for Cursor<&mut [u8]> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
slice_write(&mut self.pos, self.inner, buf)
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
slice_write_vectored(&mut self.pos, self.inner, bufs)
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
#[cfg(feature="collections")]
impl Write for Cursor<&mut Vec<u8>> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
vec_write(&mut self.pos, self.inner, buf)
}
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
vec_write_vectored(&mut self.pos, self.inner, bufs)
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
#[cfg(feature = "collections")]
impl Write for Cursor<Vec<u8>> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
vec_write(&mut self.pos, &mut self.inner, buf)
}
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
vec_write_vectored(&mut self.pos, &mut self.inner, bufs)
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
#[cfg(feature = "alloc")]
impl Write for Cursor<::alloc::boxed::Box<[u8]>> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
slice_write(&mut self.pos, &mut self.inner, buf)
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
slice_write_vectored(&mut self.pos, &mut self.inner, bufs)
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
#[cfg(test)]
mod tests {
use crate::io::prelude::*;
use crate::io::{Cursor, IoSlice, IoSliceMut, SeekFrom};
#[test]
fn test_vec_writer() {
let mut writer = Vec::new();
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(
writer
.write_vectored(&[IoSlice::new(&[]), IoSlice::new(&[8, 9]), IoSlice::new(&[10])],)
.unwrap(),
3
);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
assert_eq!(writer, b);
}
#[test]
fn test_mem_writer() {
let mut writer = Cursor::new(Vec::new());
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(
writer
.write_vectored(&[IoSlice::new(&[]), IoSlice::new(&[8, 9]), IoSlice::new(&[10])],)
.unwrap(),
3
);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
assert_eq!(&writer.get_ref()[..], b);
}
#[test]
fn test_mem_mut_writer() {
let mut vec = Vec::new();
let mut writer = Cursor::new(&mut vec);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(
writer
.write_vectored(&[IoSlice::new(&[]), IoSlice::new(&[8, 9]), IoSlice::new(&[10])],)
.unwrap(),
3
);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
assert_eq!(&writer.get_ref()[..], b);
}
#[test]
fn test_box_slice_writer() {
let mut writer = Cursor::new(vec![0u8; 9].into_boxed_slice());
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[]).unwrap(), 0);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[8, 9]).unwrap(), 1);
assert_eq!(writer.write(&[10]).unwrap(), 0);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8];
assert_eq!(&**writer.get_ref(), b);
}
#[test]
fn test_box_slice_writer_vectored() {
let mut writer = Cursor::new(vec![0u8; 9].into_boxed_slice());
assert_eq!(writer.position(), 0);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[0])]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(
writer
.write_vectored(&[IoSlice::new(&[1, 2, 3]), IoSlice::new(&[4, 5, 6, 7]),])
.unwrap(),
7,
);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write_vectored(&[]).unwrap(), 0);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[8, 9])]).unwrap(), 1);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[10])]).unwrap(), 0);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8];
assert_eq!(&**writer.get_ref(), b);
}
#[test]
fn test_buf_writer() {
let mut buf = [0 as u8; 9];
{
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[]).unwrap(), 0);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[8, 9]).unwrap(), 1);
assert_eq!(writer.write(&[10]).unwrap(), 0);
}
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8];
assert_eq!(buf, b);
}
#[test]
fn test_buf_writer_vectored() {
let mut buf = [0 as u8; 9];
{
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[0])]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(
writer
.write_vectored(&[IoSlice::new(&[1, 2, 3]), IoSlice::new(&[4, 5, 6, 7])],)
.unwrap(),
7,
);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write_vectored(&[]).unwrap(), 0);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[8, 9])]).unwrap(), 1);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[10])]).unwrap(), 0);
}
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8];
assert_eq!(buf, b);
}
#[test]
fn test_buf_writer_seek() {
let mut buf = [0 as u8; 8];
{
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[1]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.seek(SeekFrom::Start(2)).unwrap(), 2);
assert_eq!(writer.position(), 2);
assert_eq!(writer.write(&[2]).unwrap(), 1);
assert_eq!(writer.position(), 3);
assert_eq!(writer.seek(SeekFrom::Current(-2)).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[3]).unwrap(), 1);
assert_eq!(writer.position(), 2);
assert_eq!(writer.seek(SeekFrom::End(-1)).unwrap(), 7);
assert_eq!(writer.position(), 7);
assert_eq!(writer.write(&[4]).unwrap(), 1);
assert_eq!(writer.position(), 8);
}
let b: &[_] = &[1, 3, 2, 0, 0, 0, 0, 4];
assert_eq!(buf, b);
}
#[test]
fn test_buf_writer_error() {
let mut buf = [0 as u8; 2];
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[0, 0]).unwrap(), 1);
assert_eq!(writer.write(&[0, 0]).unwrap(), 0);
}
#[test]
fn test_mem_reader() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7]);
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.position(), 5);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(buf, b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_mem_reader_vectored() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7]);
let mut buf = [];
assert_eq!(reader.read_vectored(&mut [IoSliceMut::new(&mut buf)]).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(
reader
.read_vectored(&mut [IoSliceMut::new(&mut []), IoSliceMut::new(&mut buf),])
.unwrap(),
1,
);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf1 = [0; 4];
let mut buf2 = [0; 4];
assert_eq!(
reader
.read_vectored(&mut [IoSliceMut::new(&mut buf1), IoSliceMut::new(&mut buf2),])
.unwrap(),
7,
);
let b1: &[_] = &[1, 2, 3, 4];
let b2: &[_] = &[5, 6, 7];
assert_eq!(buf1, b1);
assert_eq!(&buf2[..3], b2);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_boxed_slice_reader() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7].into_boxed_slice());
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.position(), 5);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(buf, b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_boxed_slice_reader_vectored() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7].into_boxed_slice());
let mut buf = [];
assert_eq!(reader.read_vectored(&mut [IoSliceMut::new(&mut buf)]).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(
reader
.read_vectored(&mut [IoSliceMut::new(&mut []), IoSliceMut::new(&mut buf),])
.unwrap(),
1,
);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf1 = [0; 4];
let mut buf2 = [0; 4];
assert_eq!(
reader
.read_vectored(&mut [IoSliceMut::new(&mut buf1), IoSliceMut::new(&mut buf2)],)
.unwrap(),
7,
);
let b1: &[_] = &[1, 2, 3, 4];
let b2: &[_] = &[5, 6, 7];
assert_eq!(buf1, b1);
assert_eq!(&buf2[..3], b2);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn read_to_end() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7]);
let mut v = Vec::new();
reader.read_to_end(&mut v).unwrap();
assert_eq!(v, [0, 1, 2, 3, 4, 5, 6, 7]);
}
#[test]
fn test_slice_reader() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let reader = &mut &in_buf[..];
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.len(), 7);
let b: &[_] = &[0];
assert_eq!(&buf[..], b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.len(), 3);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(&buf[..], b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_slice_reader_vectored() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let reader = &mut &in_buf[..];
let mut buf = [];
assert_eq!(reader.read_vectored(&mut [IoSliceMut::new(&mut buf)]).unwrap(), 0);
let mut buf = [0];
assert_eq!(
reader
.read_vectored(&mut [IoSliceMut::new(&mut []), IoSliceMut::new(&mut buf),])
.unwrap(),
1,
);
assert_eq!(reader.len(), 7);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf1 = [0; 4];
let mut buf2 = [0; 4];
assert_eq!(
reader
.read_vectored(&mut [IoSliceMut::new(&mut buf1), IoSliceMut::new(&mut buf2)],)
.unwrap(),
7,
);
let b1: &[_] = &[1, 2, 3, 4];
let b2: &[_] = &[5, 6, 7];
assert_eq!(buf1, b1);
assert_eq!(&buf2[..3], b2);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_read_exact() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let reader = &mut &in_buf[..];
let mut buf = [];
assert!(reader.read_exact(&mut buf).is_ok());
let mut buf = [8];
assert!(reader.read_exact(&mut buf).is_ok());
assert_eq!(buf[0], 0);
assert_eq!(reader.len(), 7);
let mut buf = [0, 0, 0, 0, 0, 0, 0];
assert!(reader.read_exact(&mut buf).is_ok());
assert_eq!(buf, [1, 2, 3, 4, 5, 6, 7]);
assert_eq!(reader.len(), 0);
let mut buf = [0];
assert!(reader.read_exact(&mut buf).is_err());
}
#[test]
fn test_buf_reader() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let mut reader = Cursor::new(&in_buf[..]);
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.position(), 5);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(buf, b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn seek_past_end() {
let buf = [0xff];
let mut r = Cursor::new(&buf[..]);
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.read(&mut [0]).unwrap(), 0);
let mut r = Cursor::new(vec![10]);
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.read(&mut [0]).unwrap(), 0);
let mut buf = [0];
let mut r = Cursor::new(&mut buf[..]);
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.write(&[3]).unwrap(), 0);
let mut r = Cursor::new(vec![10].into_boxed_slice());
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.write(&[3]).unwrap(), 0);
}
#[test]
fn seek_past_i64() {
let buf = [0xff];
let mut r = Cursor::new(&buf[..]);
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
let mut r = Cursor::new(vec![10]);
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
let mut buf = [0];
let mut r = Cursor::new(&mut buf[..]);
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
let mut r = Cursor::new(vec![10].into_boxed_slice());
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
}
#[test]
fn seek_before_0() {
let buf = [0xff];
let mut r = Cursor::new(&buf[..]);
assert!(r.seek(SeekFrom::End(-2)).is_err());
let mut r = Cursor::new(vec![10]);
assert!(r.seek(SeekFrom::End(-2)).is_err());
let mut buf = [0];
let mut r = Cursor::new(&mut buf[..]);
assert!(r.seek(SeekFrom::End(-2)).is_err());
let mut r = Cursor::new(vec![10].into_boxed_slice());
assert!(r.seek(SeekFrom::End(-2)).is_err());
}
#[test]
fn test_seekable_mem_writer() {
let mut writer = Cursor::new(Vec::<u8>::new());
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.position(), 8);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::Start(0)).unwrap(), 0);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[3, 4]).unwrap(), 2);
let b: &[_] = &[3, 4, 2, 3, 4, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::Current(1)).unwrap(), 3);
assert_eq!(writer.write(&[0, 1]).unwrap(), 2);
let b: &[_] = &[3, 4, 2, 0, 1, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::End(-1)).unwrap(), 7);
assert_eq!(writer.write(&[1, 2]).unwrap(), 2);
let b: &[_] = &[3, 4, 2, 0, 1, 5, 6, 1, 2];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::End(1)).unwrap(), 10);
assert_eq!(writer.write(&[1]).unwrap(), 1);
let b: &[_] = &[3, 4, 2, 0, 1, 5, 6, 1, 2, 0, 1];
assert_eq!(&writer.get_ref()[..], b);
}
#[test]
fn vec_seek_past_end() {
let mut r = Cursor::new(Vec::new());
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.write(&[3]).unwrap(), 1);
}
#[test]
fn vec_seek_before_0() {
let mut r = Cursor::new(Vec::new());
assert!(r.seek(SeekFrom::End(-2)).is_err());
}
#[test]
#[cfg(target_pointer_width = "32")]
fn vec_seek_and_write_past_usize_max() {
let mut c = Cursor::new(Vec::new());
c.set_position(<usize>::max_value() as u64 + 1);
assert!(c.write_all(&[1, 2, 3]).is_err());
}
#[test]
fn test_partial_eq() {
assert_eq!(Cursor::new(Vec::<u8>::new()), Cursor::new(Vec::<u8>::new()));
}
#[test]
fn test_eq() {
struct AssertEq<T: Eq>(pub T);
let _: AssertEq<Cursor<Vec<u8>>> = AssertEq(Cursor::new(Vec::new()));
}
}

View File

@ -0,0 +1,552 @@
use core::convert::From;
use core::fmt;
use core::result;
use core::convert::Into;
use core::marker::{Send, Sync};
use core::option::Option::{self, Some, None};
#[cfg(feature="alloc")] use alloc::boxed::Box;
#[cfg(not(feature="alloc"))] use ::FakeBox as Box;
#[cfg(feature="collections")] use collections::string::String;
#[cfg(not(feature="collections"))] use ::ErrorString as String;
/// A specialized [`Result`](../result/enum.Result.html) type for I/O
/// operations.
///
/// This type is broadly used across [`std::io`] for any operation which may
/// produce an error.
///
/// This typedef is generally used to avoid writing out [`io::Error`] directly and
/// is otherwise a direct mapping to [`Result`].
///
/// While usual Rust style is to import types directly, aliases of [`Result`]
/// often are not, to make it easier to distinguish between them. [`Result`] is
/// generally assumed to be [`std::result::Result`][`Result`], and so users of this alias
/// will generally use `io::Result` instead of shadowing the prelude's import
/// of [`std::result::Result`][`Result`].
///
/// [`std::io`]: ../io/index.html
/// [`io::Error`]: ../io/struct.Error.html
/// [`Result`]: ../result/enum.Result.html
///
/// # Examples
///
/// A convenience function that bubbles an `io::Result` to its caller:
///
/// ```
/// use std::io;
///
/// fn get_string() -> io::Result<String> {
/// let mut buffer = String::new();
///
/// io::stdin().read_line(&mut buffer)?;
///
/// Ok(buffer)
/// }
/// ```
pub type Result<T> = result::Result<T, Error>;
/// The error type for I/O operations of the [`Read`], [`Write`], [`Seek`], and
/// associated traits.
///
/// Errors mostly originate from the underlying OS, but custom instances of
/// `Error` can be created with crafted error messages and a particular value of
/// [`ErrorKind`].
///
/// [`Read`]: ../io/trait.Read.html
/// [`Write`]: ../io/trait.Write.html
/// [`Seek`]: ../io/trait.Seek.html
/// [`ErrorKind`]: enum.ErrorKind.html
pub struct Error {
repr: Repr,
}
impl fmt::Debug for Error {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt::Debug::fmt(&self.repr, f)
}
}
enum Repr {
Os(i32),
Simple(ErrorKind),
#[cfg(feature="alloc")]
Custom(Box<Custom>),
#[cfg(not(feature="alloc"))]
Custom(Custom),
}
#[derive(Debug)]
struct Custom {
kind: ErrorKind,
error: String,
}
/// A list specifying general categories of I/O error.
///
/// This list is intended to grow over time and it is not recommended to
/// exhaustively match against it.
///
/// It is used with the [`io::Error`] type.
///
/// [`io::Error`]: struct.Error.html
#[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
#[allow(deprecated)]
#[non_exhaustive]
pub enum ErrorKind {
/// An entity was not found, often a file.
NotFound,
/// The operation lacked the necessary privileges to complete.
PermissionDenied,
/// The connection was refused by the remote server.
ConnectionRefused,
/// The connection was reset by the remote server.
ConnectionReset,
/// The connection was aborted (terminated) by the remote server.
ConnectionAborted,
/// The network operation failed because it was not connected yet.
NotConnected,
/// A socket address could not be bound because the address is already in
/// use elsewhere.
AddrInUse,
/// A nonexistent interface was requested or the requested address was not
/// local.
AddrNotAvailable,
/// The operation failed because a pipe was closed.
BrokenPipe,
/// An entity already exists, often a file.
AlreadyExists,
/// The operation needs to block to complete, but the blocking operation was
/// requested to not occur.
WouldBlock,
/// A parameter was incorrect.
InvalidInput,
/// Data not valid for the operation were encountered.
///
/// Unlike [`InvalidInput`], this typically means that the operation
/// parameters were valid, however the error was caused by malformed
/// input data.
///
/// For example, a function that reads a file into a string will error with
/// `InvalidData` if the file's contents are not valid UTF-8.
///
/// [`InvalidInput`]: #variant.InvalidInput
InvalidData,
/// The I/O operation's timeout expired, causing it to be canceled.
TimedOut,
/// An error returned when an operation could not be completed because a
/// call to [`write`] returned [`Ok(0)`].
///
/// This typically means that an operation could only succeed if it wrote a
/// particular number of bytes but only a smaller number of bytes could be
/// written.
///
/// [`write`]: ../../std/io/trait.Write.html#tymethod.write
/// [`Ok(0)`]: ../../std/io/type.Result.html
WriteZero,
/// This operation was interrupted.
///
/// Interrupted operations can typically be retried.
Interrupted,
/// Any I/O error not part of this list.
Other,
/// An error returned when an operation could not be completed because an
/// "end of file" was reached prematurely.
///
/// This typically means that an operation could only succeed if it read a
/// particular number of bytes but only a smaller number of bytes could be
/// read.
UnexpectedEof,
}
impl ErrorKind {
pub(crate) fn as_str(&self) -> &'static str {
match *self {
ErrorKind::NotFound => "entity not found",
ErrorKind::PermissionDenied => "permission denied",
ErrorKind::ConnectionRefused => "connection refused",
ErrorKind::ConnectionReset => "connection reset",
ErrorKind::ConnectionAborted => "connection aborted",
ErrorKind::NotConnected => "not connected",
ErrorKind::AddrInUse => "address in use",
ErrorKind::AddrNotAvailable => "address not available",
ErrorKind::BrokenPipe => "broken pipe",
ErrorKind::AlreadyExists => "entity already exists",
ErrorKind::WouldBlock => "operation would block",
ErrorKind::InvalidInput => "invalid input parameter",
ErrorKind::InvalidData => "invalid data",
ErrorKind::TimedOut => "timed out",
ErrorKind::WriteZero => "write zero",
ErrorKind::Interrupted => "operation interrupted",
ErrorKind::Other => "other os error",
ErrorKind::UnexpectedEof => "unexpected end of file",
}
}
}
/// Intended for use for errors not exposed to the user, where allocating onto
/// the heap (for normal construction via Error::new) is too costly.
impl From<ErrorKind> for Error {
/// Converts an [`ErrorKind`] into an [`Error`].
///
/// This conversion allocates a new error with a simple representation of error kind.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// let not_found = ErrorKind::NotFound;
/// let error = Error::from(not_found);
/// assert_eq!("entity not found", format!("{}", error));
/// ```
///
/// [`ErrorKind`]: ../../std/io/enum.ErrorKind.html
/// [`Error`]: ../../std/io/struct.Error.html
#[inline]
fn from(kind: ErrorKind) -> Error {
Error { repr: Repr::Simple(kind) }
}
}
impl Error {
/// Creates a new I/O error from a known kind of error as well as an
/// arbitrary error payload.
///
/// This function is used to generically create I/O errors which do not
/// originate from the OS itself. The `error` argument is an arbitrary
/// payload which will be contained in this `Error`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// // errors can be created from strings
/// let custom_error = Error::new(ErrorKind::Other, "oh no!");
///
/// // errors can also be created from other errors
/// let custom_error2 = Error::new(ErrorKind::Interrupted, custom_error);
/// ```
pub fn new<E>(kind: ErrorKind, error: E) -> Error
where
E: Into<String>,
{
Self::_new(kind, error.into())
}
fn _new(kind: ErrorKind, error: String) -> Error {
Error { repr: Repr::Custom(Box::new(Custom { kind, error })) }
}
/// Creates a new instance of an `Error` from a particular OS error code.
///
/// # Examples
///
/// On Linux:
///
/// ```
/// # if cfg!(target_os = "linux") {
/// use std::io;
///
/// let error = io::Error::from_raw_os_error(22);
/// assert_eq!(error.kind(), io::ErrorKind::InvalidInput);
/// # }
/// ```
///
/// On Windows:
///
/// ```
/// # if cfg!(windows) {
/// use std::io;
///
/// let error = io::Error::from_raw_os_error(10022);
/// assert_eq!(error.kind(), io::ErrorKind::InvalidInput);
/// # }
/// ```
pub fn from_raw_os_error(code: i32) -> Error {
Error { repr: Repr::Os(code) }
}
/// Returns the OS error that this error represents (if any).
///
/// If this `Error` was constructed via `last_os_error` or
/// `from_raw_os_error`, then this function will return `Some`, otherwise
/// it will return `None`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_os_error(err: &Error) {
/// if let Some(raw_os_err) = err.raw_os_error() {
/// println!("raw OS error: {:?}", raw_os_err);
/// } else {
/// println!("Not an OS error");
/// }
/// }
///
/// fn main() {
/// // Will print "raw OS error: ...".
/// print_os_error(&Error::last_os_error());
/// // Will print "Not an OS error".
/// print_os_error(&Error::new(ErrorKind::Other, "oh no!"));
/// }
/// ```
pub fn raw_os_error(&self) -> Option<i32> {
match self.repr {
Repr::Os(i) => Some(i),
Repr::Custom(..) => None,
Repr::Simple(..) => None,
}
}
/// Returns a reference to the inner error wrapped by this error (if any).
///
/// If this `Error` was constructed via `new` then this function will
/// return `Some`, otherwise it will return `None`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_error(err: &Error) {
/// if let Some(inner_err) = err.get_ref() {
/// println!("Inner error: {:?}", inner_err);
/// } else {
/// println!("No inner error");
/// }
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(&Error::last_os_error());
/// // Will print "Inner error: ...".
/// print_error(&Error::new(ErrorKind::Other, "oh no!"));
/// }
/// ```
pub fn get_ref(&self) -> Option<&String> {
match self.repr {
Repr::Os(..) => None,
Repr::Simple(..) => None,
Repr::Custom(ref c) => Some(&c.error),
}
}
/// Returns a mutable reference to the inner error wrapped by this error
/// (if any).
///
/// If this `Error` was constructed via `new` then this function will
/// return `Some`, otherwise it will return `None`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
/// use std::{error, fmt};
/// use std::fmt::Display;
///
/// #[derive(Debug)]
/// struct MyError {
/// v: String,
/// }
///
/// impl MyError {
/// fn new() -> MyError {
/// MyError {
/// v: "oh no!".to_string()
/// }
/// }
///
/// fn change_message(&mut self, new_message: &str) {
/// self.v = new_message.to_string();
/// }
/// }
///
/// impl error::Error for MyError {}
///
/// impl Display for MyError {
/// fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
/// write!(f, "MyError: {}", &self.v)
/// }
/// }
///
/// fn change_error(mut err: Error) -> Error {
/// if let Some(inner_err) = err.get_mut() {
/// inner_err.downcast_mut::<MyError>().unwrap().change_message("I've been changed!");
/// }
/// err
/// }
///
/// fn print_error(err: &Error) {
/// if let Some(inner_err) = err.get_ref() {
/// println!("Inner error: {}", inner_err);
/// } else {
/// println!("No inner error");
/// }
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(&change_error(Error::last_os_error()));
/// // Will print "Inner error: ...".
/// print_error(&change_error(Error::new(ErrorKind::Other, MyError::new())));
/// }
/// ```
pub fn get_mut(&mut self) -> Option<&mut String> {
match self.repr {
Repr::Os(..) => None,
Repr::Simple(..) => None,
Repr::Custom(ref mut c) => Some(&mut c.error),
}
}
/// Consumes the `Error`, returning its inner error (if any).
///
/// If this `Error` was constructed via `new` then this function will
/// return `Some`, otherwise it will return `None`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_error(err: Error) {
/// if let Some(inner_err) = err.into_inner() {
/// println!("Inner error: {}", inner_err);
/// } else {
/// println!("No inner error");
/// }
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(Error::last_os_error());
/// // Will print "Inner error: ...".
/// print_error(Error::new(ErrorKind::Other, "oh no!"));
/// }
/// ```
pub fn into_inner(self) -> Option<String> {
match self.repr {
Repr::Os(..) => None,
Repr::Simple(..) => None,
Repr::Custom(c) => Some(c.error),
}
}
/// Returns the corresponding `ErrorKind` for this error.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_error(err: Error) {
/// println!("{:?}", err.kind());
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(Error::last_os_error());
/// // Will print "Inner error: ...".
/// print_error(Error::new(ErrorKind::AddrInUse, "oh no!"));
/// }
/// ```
pub fn kind(&self) -> ErrorKind {
match self.repr {
Repr::Os(_code) => ErrorKind::Other,
Repr::Custom(ref c) => c.kind,
Repr::Simple(kind) => kind,
}
}
}
impl fmt::Debug for Repr {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
match *self {
Repr::Os(code) => fmt
.debug_struct("Os")
.field("code", &code)
.finish(),
Repr::Custom(ref c) => fmt::Debug::fmt(&c, fmt),
Repr::Simple(kind) => fmt.debug_tuple("Kind").field(&kind).finish(),
}
}
}
impl fmt::Display for Error {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
match self.repr {
Repr::Os(code) => {
write!(fmt, "os error {}", code)
}
Repr::Custom(ref c) => c.error.fmt(fmt),
Repr::Simple(kind) => write!(fmt, "{}", kind.as_str()),
}
}
}
fn _assert_error_is_sync_send() {
fn _is_sync_send<T: Sync + Send>() {}
_is_sync_send::<Error>();
}
#[cfg(test)]
mod test {
use super::{Custom, Error, ErrorKind, Repr};
use crate::error;
use crate::fmt;
use crate::sys::decode_error_kind;
use crate::sys::os::error_string;
#[test]
fn test_debug_error() {
let code = 6;
let msg = error_string(code);
let kind = decode_error_kind(code);
let err = Error {
repr: Repr::Custom(box Custom {
kind: ErrorKind::InvalidInput,
error: box Error { repr: super::Repr::Os(code) },
}),
};
let expected = format!(
"Custom {{ \
kind: InvalidInput, \
error: Os {{ \
code: {:?}, \
kind: {:?}, \
message: {:?} \
}} \
}}",
code, kind, msg
);
assert_eq!(format!("{:?}", err), expected);
}
#[test]
fn test_downcasting() {
#[derive(Debug)]
struct TestError;
impl fmt::Display for TestError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.write_str("asdf")
}
}
impl error::Error for TestError {}
// we have to call all of these UFCS style right now since method
// resolution won't implicitly drop the Send+Sync bounds
let mut err = Error::new(ErrorKind::Other, TestError);
assert!(err.get_ref().unwrap().is::<TestError>());
assert_eq!("asdf", err.get_ref().unwrap().to_string());
assert!(err.get_mut().unwrap().is::<TestError>());
let extracted = err.into_inner().unwrap();
extracted.downcast::<TestError>().unwrap();
}
}

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@ -0,0 +1,430 @@
use core::cmp;
use core::fmt;
use crate::io::{
self, Error, ErrorKind, Initializer, IoSlice, IoSliceMut, Read, Seek, SeekFrom, Write,
};
#[cfg(feature="collections")] use crate::io::BufRead;
use core::mem;
#[cfg(feature="alloc")] use alloc::boxed::Box;
#[cfg(feature="collections")] use collections::string::String;
#[cfg(feature="collections")] use collections::vec::Vec;
// =============================================================================
// Forwarding implementations
impl<R: Read + ?Sized> Read for &mut R {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
(**self).read(buf)
}
#[inline]
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
(**self).read_vectored(bufs)
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
(**self).initializer()
}
#[cfg(feature="collections")]
#[inline]
fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_to_end(buf)
}
#[cfg(feature="collections")]
#[inline]
fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_to_string(buf)
}
#[inline]
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
(**self).read_exact(buf)
}
}
impl<W: Write + ?Sized> Write for &mut W {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
(**self).write(buf)
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
(**self).write_vectored(bufs)
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
(**self).flush()
}
#[inline]
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
(**self).write_all(buf)
}
#[inline]
fn write_fmt(&mut self, fmt: fmt::Arguments<'_>) -> io::Result<()> {
(**self).write_fmt(fmt)
}
}
impl<S: Seek + ?Sized> Seek for &mut S {
#[inline]
fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
(**self).seek(pos)
}
}
#[cfg(feature="collections")]
impl<B: BufRead + ?Sized> BufRead for &mut B {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> {
(**self).fill_buf()
}
#[inline]
fn consume(&mut self, amt: usize) {
(**self).consume(amt)
}
#[inline]
fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_until(byte, buf)
}
#[inline]
fn read_line(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_line(buf)
}
}
#[cfg(feature="alloc")]
impl<R: Read + ?Sized> Read for Box<R> {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
(**self).read(buf)
}
#[inline]
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
(**self).read_vectored(bufs)
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
(**self).initializer()
}
#[cfg(feature="collections")]
#[inline]
fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_to_end(buf)
}
#[cfg(feature="collections")]
#[inline]
fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_to_string(buf)
}
#[inline]
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
(**self).read_exact(buf)
}
}
#[cfg(feature="alloc")]
impl<W: Write + ?Sized> Write for Box<W> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
(**self).write(buf)
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
(**self).write_vectored(bufs)
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
(**self).flush()
}
#[inline]
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
(**self).write_all(buf)
}
#[inline]
fn write_fmt(&mut self, fmt: fmt::Arguments<'_>) -> io::Result<()> {
(**self).write_fmt(fmt)
}
}
#[cfg(feature="alloc")]
impl<S: Seek + ?Sized> Seek for Box<S> {
#[inline]
fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
(**self).seek(pos)
}
}
#[cfg(feature="collections")]
impl<B: BufRead + ?Sized> BufRead for Box<B> {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> {
(**self).fill_buf()
}
#[inline]
fn consume(&mut self, amt: usize) {
(**self).consume(amt)
}
#[inline]
fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_until(byte, buf)
}
#[inline]
fn read_line(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_line(buf)
}
}
// Used by panicking::default_hook
#[cfg(test)]
/// This impl is only used by printing logic, so any error returned is always
/// of kind `Other`, and should be ignored.
impl Write for Box<dyn (::realstd::io::Write) + Send> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
(**self).write(buf).map_err(|_| ErrorKind::Other.into())
}
fn flush(&mut self) -> io::Result<()> {
(**self).flush().map_err(|_| ErrorKind::Other.into())
}
}
// =============================================================================
// In-memory buffer implementations
/// Read is implemented for `&[u8]` by copying from the slice.
///
/// Note that reading updates the slice to point to the yet unread part.
/// The slice will be empty when EOF is reached.
impl Read for &[u8] {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
let amt = cmp::min(buf.len(), self.len());
let (a, b) = self.split_at(amt);
// First check if the amount of bytes we want to read is small:
// `copy_from_slice` will generally expand to a call to `memcpy`, and
// for a single byte the overhead is significant.
if amt == 1 {
buf[0] = a[0];
} else {
buf[..amt].copy_from_slice(a);
}
*self = b;
Ok(amt)
}
#[inline]
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
let mut nread = 0;
for buf in bufs {
nread += self.read(buf)?;
if self.is_empty() {
break;
}
}
Ok(nread)
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
#[inline]
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
if buf.len() > self.len() {
return Err(Error::new(ErrorKind::UnexpectedEof, "failed to fill whole buffer"));
}
let (a, b) = self.split_at(buf.len());
// First check if the amount of bytes we want to read is small:
// `copy_from_slice` will generally expand to a call to `memcpy`, and
// for a single byte the overhead is significant.
if buf.len() == 1 {
buf[0] = a[0];
} else {
buf.copy_from_slice(a);
}
*self = b;
Ok(())
}
#[cfg(feature="collections")]
#[inline]
fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
buf.extend_from_slice(*self);
let len = self.len();
*self = &self[len..];
Ok(len)
}
}
#[cfg(feature="collections")]
impl BufRead for &[u8] {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> {
Ok(*self)
}
#[inline]
fn consume(&mut self, amt: usize) {
*self = &self[amt..];
}
}
/// Write is implemented for `&mut [u8]` by copying into the slice, overwriting
/// its data.
///
/// Note that writing updates the slice to point to the yet unwritten part.
/// The slice will be empty when it has been completely overwritten.
impl Write for &mut [u8] {
#[inline]
fn write(&mut self, data: &[u8]) -> io::Result<usize> {
let amt = cmp::min(data.len(), self.len());
let (a, b) = mem::replace(self, &mut []).split_at_mut(amt);
a.copy_from_slice(&data[..amt]);
*self = b;
Ok(amt)
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
let mut nwritten = 0;
for buf in bufs {
nwritten += self.write(buf)?;
if self.is_empty() {
break;
}
}
Ok(nwritten)
}
#[inline]
fn write_all(&mut self, data: &[u8]) -> io::Result<()> {
if self.write(data)? == data.len() {
Ok(())
} else {
Err(Error::new(ErrorKind::WriteZero, "failed to write whole buffer"))
}
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
/// Write is implemented for `Vec<u8>` by appending to the vector.
/// The vector will grow as needed.
#[cfg(feature="collections")]
impl Write for Vec<u8> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
self.extend_from_slice(buf);
Ok(buf.len())
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
let len = bufs.iter().map(|b| b.len()).sum();
self.reserve(len);
for buf in bufs {
self.extend_from_slice(buf);
}
Ok(len)
}
#[inline]
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
self.extend_from_slice(buf);
Ok(())
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
#[cfg(test)]
mod tests {
use crate::io::prelude::*;
#[bench]
fn bench_read_slice(b: &mut test::Bencher) {
let buf = [5; 1024];
let mut dst = [0; 128];
b.iter(|| {
let mut rd = &buf[..];
for _ in 0..8 {
let _ = rd.read(&mut dst);
test::black_box(&dst);
}
})
}
#[bench]
fn bench_write_slice(b: &mut test::Bencher) {
let mut buf = [0; 1024];
let src = [5; 128];
b.iter(|| {
let mut wr = &mut buf[..];
for _ in 0..8 {
let _ = wr.write_all(&src);
test::black_box(&wr);
}
})
}
#[bench]
fn bench_read_vec(b: &mut test::Bencher) {
let buf = vec![5; 1024];
let mut dst = [0; 128];
b.iter(|| {
let mut rd = &buf[..];
for _ in 0..8 {
let _ = rd.read(&mut dst);
test::black_box(&dst);
}
})
}
#[bench]
fn bench_write_vec(b: &mut test::Bencher) {
let mut buf = Vec::with_capacity(1024);
let src = [5; 128];
b.iter(|| {
let mut wr = &mut buf[..];
for _ in 0..8 {
let _ = wr.write_all(&src);
test::black_box(&wr);
}
})
}
}

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//! The I/O Prelude
//!
//! The purpose of this module is to alleviate imports of many common I/O traits
//! by adding a glob import to the top of I/O heavy modules:
//!
//! ```
//! # #![allow(unused_imports)]
//! use std::io::prelude::*;
//! ```
pub use super::{Read, Seek, Write};
#[cfg(feature="collections")] pub use super::BufRead;
#[cfg(feature="collections")] pub use alloc::boxed::Box;
#[cfg(feature="collections")] pub use collections::vec::Vec;

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#![allow(missing_copy_implementations)]
use core::fmt;
use crate::io::{self, ErrorKind, Initializer, IoSlice, IoSliceMut, Read, Write};
#[cfg(feature="collections")] use crate::io::BufRead;
use core::mem::MaybeUninit;
/// Copies the entire contents of a reader into a writer.
///
/// This function will continuously read data from `reader` and then
/// write it into `writer` in a streaming fashion until `reader`
/// returns EOF.
///
/// On success, the total number of bytes that were copied from
/// `reader` to `writer` is returned.
///
/// If youre wanting to copy the contents of one file to another and youre
/// working with filesystem paths, see the [`fs::copy`] function.
///
/// [`fs::copy`]: ../fs/fn.copy.html
///
/// # Errors
///
/// This function will return an error immediately if any call to `read` or
/// `write` returns an error. All instances of `ErrorKind::Interrupted` are
/// handled by this function and the underlying operation is retried.
///
/// # Examples
///
/// ```
/// use std::io;
///
/// fn main() -> io::Result<()> {
/// let mut reader: &[u8] = b"hello";
/// let mut writer: Vec<u8> = vec![];
///
/// io::copy(&mut reader, &mut writer)?;
///
/// assert_eq!(&b"hello"[..], &writer[..]);
/// Ok(())
/// }
/// ```
pub fn copy<R: ?Sized, W: ?Sized>(reader: &mut R, writer: &mut W) -> io::Result<u64>
where
R: Read,
W: Write,
{
let mut buf = MaybeUninit::<[u8; super::DEFAULT_BUF_SIZE]>::uninit();
// FIXME(#53491): This is calling `get_mut` and `get_ref` on an uninitialized
// `MaybeUninit`. Revisit this once we decided whether that is valid or not.
// This is still technically undefined behavior due to creating a reference
// to uninitialized data, but within libstd we can rely on more guarantees
// than if this code were in an external lib.
unsafe {
reader.initializer().initialize(buf.get_mut());
}
let mut written = 0;
loop {
let len = match reader.read(unsafe { buf.get_mut() }) {
Ok(0) => return Ok(written),
Ok(len) => len,
Err(ref e) if e.kind() == ErrorKind::Interrupted => continue,
Err(e) => return Err(e),
};
writer.write_all(unsafe { &buf.get_ref()[..len] })?;
written += len as u64;
}
}
/// A reader which is always at EOF.
///
/// This struct is generally created by calling [`empty`]. Please see
/// the documentation of [`empty()`][`empty`] for more details.
///
/// [`empty`]: fn.empty.html
pub struct Empty {
_priv: (),
}
/// Constructs a new handle to an empty reader.
///
/// All reads from the returned reader will return [`Ok`]`(0)`.
///
/// [`Ok`]: ../result/enum.Result.html#variant.Ok
///
/// # Examples
///
/// A slightly sad example of not reading anything into a buffer:
///
/// ```
/// use std::io::{self, Read};
///
/// let mut buffer = String::new();
/// io::empty().read_to_string(&mut buffer).unwrap();
/// assert!(buffer.is_empty());
/// ```
pub fn empty() -> Empty {
Empty { _priv: () }
}
impl Read for Empty {
#[inline]
fn read(&mut self, _buf: &mut [u8]) -> io::Result<usize> {
Ok(0)
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
}
#[cfg(feature="collections")]
impl BufRead for Empty {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> {
Ok(&[])
}
#[inline]
fn consume(&mut self, _n: usize) {}
}
impl fmt::Debug for Empty {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.pad("Empty { .. }")
}
}
/// A reader which yields one byte over and over and over and over and over and...
///
/// This struct is generally created by calling [`repeat`][repeat]. Please
/// see the documentation of `repeat()` for more details.
///
/// [repeat]: fn.repeat.html
pub struct Repeat {
byte: u8,
}
/// Creates an instance of a reader that infinitely repeats one byte.
///
/// All reads from this reader will succeed by filling the specified buffer with
/// the given byte.
///
/// # Examples
///
/// ```
/// use std::io::{self, Read};
///
/// let mut buffer = [0; 3];
/// io::repeat(0b101).read_exact(&mut buffer).unwrap();
/// assert_eq!(buffer, [0b101, 0b101, 0b101]);
/// ```
pub fn repeat(byte: u8) -> Repeat {
Repeat { byte }
}
impl Read for Repeat {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
for slot in &mut *buf {
*slot = self.byte;
}
Ok(buf.len())
}
#[inline]
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
let mut nwritten = 0;
for buf in bufs {
nwritten += self.read(buf)?;
}
Ok(nwritten)
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
}
impl fmt::Debug for Repeat {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.pad("Repeat { .. }")
}
}
/// A writer which will move data into the void.
///
/// This struct is generally created by calling [`sink`][sink]. Please
/// see the documentation of `sink()` for more details.
///
/// [sink]: fn.sink.html
pub struct Sink {
_priv: (),
}
/// Creates an instance of a writer which will successfully consume all data.
///
/// All calls to `write` on the returned instance will return `Ok(buf.len())`
/// and the contents of the buffer will not be inspected.
///
/// # Examples
///
/// ```rust
/// use std::io::{self, Write};
///
/// let buffer = vec![1, 2, 3, 5, 8];
/// let num_bytes = io::sink().write(&buffer).unwrap();
/// assert_eq!(num_bytes, 5);
/// ```
pub fn sink() -> Sink {
Sink { _priv: () }
}
impl Write for Sink {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
Ok(buf.len())
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
let total_len = bufs.iter().map(|b| b.len()).sum();
Ok(total_len)
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
impl fmt::Debug for Sink {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.pad("Sink { .. }")
}
}
#[cfg(test)]
mod tests {
use crate::io::prelude::*;
use crate::io::{copy, empty, repeat, sink};
#[test]
fn copy_copies() {
let mut r = repeat(0).take(4);
let mut w = sink();
assert_eq!(copy(&mut r, &mut w).unwrap(), 4);
let mut r = repeat(0).take(1 << 17);
assert_eq!(copy(&mut r as &mut dyn Read, &mut w as &mut dyn Write).unwrap(), 1 << 17);
}
#[test]
fn sink_sinks() {
let mut s = sink();
assert_eq!(s.write(&[]).unwrap(), 0);
assert_eq!(s.write(&[0]).unwrap(), 1);
assert_eq!(s.write(&[0; 1024]).unwrap(), 1024);
assert_eq!(s.by_ref().write(&[0; 1024]).unwrap(), 1024);
}
#[test]
fn empty_reads() {
let mut e = empty();
assert_eq!(e.read(&mut []).unwrap(), 0);
assert_eq!(e.read(&mut [0]).unwrap(), 0);
assert_eq!(e.read(&mut [0; 1024]).unwrap(), 0);
assert_eq!(e.by_ref().read(&mut [0; 1024]).unwrap(), 0);
}
#[test]
fn repeat_repeats() {
let mut r = repeat(4);
let mut b = [0; 1024];
assert_eq!(r.read(&mut b).unwrap(), 1024);
assert!(b.iter().all(|b| *b == 4));
}
#[test]
fn take_some_bytes() {
assert_eq!(repeat(4).take(100).bytes().count(), 100);
assert_eq!(repeat(4).take(100).bytes().next().unwrap().unwrap(), 4);
assert_eq!(repeat(1).take(10).chain(repeat(2).take(10)).bytes().count(), 20);
}
}

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use crate::io::prelude::*;
use core::cmp;
use crate::io::{self, Initializer, SeekFrom, Error, ErrorKind, IoSlice, IoSliceMut};
#[cfg(feature="collections")] use core::convert::TryInto;
/// A `Cursor` wraps an in-memory buffer and provides it with a
/// [`Seek`] implementation.
///
/// `Cursor`s are used with in-memory buffers, anything implementing
/// `AsRef<[u8]>`, to allow them to implement [`Read`] and/or [`Write`],
/// allowing these buffers to be used anywhere you might use a reader or writer
/// that does actual I/O.
///
/// The standard library implements some I/O traits on various types which
/// are commonly used as a buffer, like `Cursor<`[`Vec`]`<u8>>` and
/// `Cursor<`[`&[u8]`][bytes]`>`.
///
/// # Examples
///
/// We may want to write bytes to a [`File`] in our production
/// code, but use an in-memory buffer in our tests. We can do this with
/// `Cursor`:
///
/// [`Seek`]: trait.Seek.html
/// [`Read`]: ../../std/io/trait.Read.html
/// [`Write`]: ../../std/io/trait.Write.html
/// [`Vec`]: ../../std/vec/struct.Vec.html
/// [bytes]: ../../std/primitive.slice.html
/// [`File`]: ../fs/struct.File.html
///
/// ```no_run
/// use std::io::prelude::*;
/// use std::io::{self, SeekFrom};
/// use std::fs::File;
///
/// // a library function we've written
/// fn write_ten_bytes_at_end<W: Write + Seek>(writer: &mut W) -> io::Result<()> {
/// writer.seek(SeekFrom::End(-10))?;
///
/// for i in 0..10 {
/// writer.write(&[i])?;
/// }
///
/// // all went well
/// Ok(())
/// }
///
/// # fn foo() -> io::Result<()> {
/// // Here's some code that uses this library function.
/// //
/// // We might want to use a BufReader here for efficiency, but let's
/// // keep this example focused.
/// let mut file = File::create("foo.txt")?;
///
/// write_ten_bytes_at_end(&mut file)?;
/// # Ok(())
/// # }
///
/// // now let's write a test
/// #[test]
/// fn test_writes_bytes() {
/// // setting up a real File is much slower than an in-memory buffer,
/// // let's use a cursor instead
/// use std::io::Cursor;
/// let mut buff = Cursor::new(vec![0; 15]);
///
/// write_ten_bytes_at_end(&mut buff).unwrap();
///
/// assert_eq!(&buff.get_ref()[5..15], &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
/// }
/// ```
#[derive(Clone, Debug, Default)]
pub struct Cursor<T> {
inner: T,
pos: u64,
}
impl<T> Cursor<T> {
/// Creates a new cursor wrapping the provided underlying in-memory buffer.
///
/// Cursor initial position is `0` even if underlying buffer (e.g., `Vec`)
/// is not empty. So writing to cursor starts with overwriting `Vec`
/// content, not with appending to it.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
/// ```
pub fn new(inner: T) -> Cursor<T> {
Cursor { pos: 0, inner: inner }
}
/// Consumes this cursor, returning the underlying value.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
///
/// let vec = buff.into_inner();
/// ```
pub fn into_inner(self) -> T { self.inner }
/// Gets a reference to the underlying value in this cursor.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
///
/// let reference = buff.get_ref();
/// ```
pub fn get_ref(&self) -> &T { &self.inner }
/// Gets a mutable reference to the underlying value in this cursor.
///
/// Care should be taken to avoid modifying the internal I/O state of the
/// underlying value as it may corrupt this cursor's position.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let mut buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
///
/// let reference = buff.get_mut();
/// ```
pub fn get_mut(&mut self) -> &mut T { &mut self.inner }
/// Returns the current position of this cursor.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
/// use std::io::prelude::*;
/// use std::io::SeekFrom;
///
/// let mut buff = Cursor::new(vec![1, 2, 3, 4, 5]);
///
/// assert_eq!(buff.position(), 0);
///
/// buff.seek(SeekFrom::Current(2)).unwrap();
/// assert_eq!(buff.position(), 2);
///
/// buff.seek(SeekFrom::Current(-1)).unwrap();
/// assert_eq!(buff.position(), 1);
/// ```
pub fn position(&self) -> u64 { self.pos }
/// Sets the position of this cursor.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let mut buff = Cursor::new(vec![1, 2, 3, 4, 5]);
///
/// assert_eq!(buff.position(), 0);
///
/// buff.set_position(2);
/// assert_eq!(buff.position(), 2);
///
/// buff.set_position(4);
/// assert_eq!(buff.position(), 4);
/// ```
pub fn set_position(&mut self, pos: u64) { self.pos = pos; }
}
impl<T> io::Seek for Cursor<T> where T: AsRef<[u8]> {
fn seek(&mut self, style: SeekFrom) -> io::Result<u64> {
let (base_pos, offset) = match style {
SeekFrom::Start(n) => { self.pos = n; return Ok(n); }
SeekFrom::End(n) => (self.inner.as_ref().len() as u64, n),
SeekFrom::Current(n) => (self.pos, n),
};
let new_pos = if offset >= 0 {
base_pos.checked_add(offset as u64)
} else {
base_pos.checked_sub((offset.wrapping_neg()) as u64)
};
match new_pos {
Some(n) => {self.pos = n; Ok(self.pos)}
None => Err(Error::new(ErrorKind::InvalidInput,
"invalid seek to a negative or overflowing position"))
}
}
fn stream_len(&mut self) -> io::Result<u64> {
Ok(self.inner.as_ref().len() as u64)
}
fn stream_position(&mut self) -> io::Result<u64> {
Ok(self.pos)
}
}
impl<T> Read for Cursor<T> where T: AsRef<[u8]> {
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
let n = Read::read(&mut self.get_buf()?, buf)?;
self.pos += n as u64;
Ok(n)
}
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
let mut nread = 0;
for buf in bufs {
let n = self.read(buf)?;
nread += n;
if n < buf.len() {
break;
}
}
Ok(nread)
}
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
let n = buf.len();
Read::read_exact(&mut self.get_buf()?, buf)?;
self.pos += n as u64;
Ok(())
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
}
impl<T> Cursor<T> where T: AsRef<[u8]> {
fn get_buf(&mut self) -> io::Result<&[u8]> {
let amt = cmp::min(self.pos, self.inner.as_ref().len() as u64);
Ok(&self.inner.as_ref()[(amt as usize)..])
}
}
#[cfg(feature="collections")]
impl<T> BufRead for Cursor<T> where T: AsRef<[u8]> {
fn fill_buf(&mut self) -> io::Result<&[u8]> { self.get_buf() }
fn consume(&mut self, amt: usize) { self.pos += amt as u64; }
}
// Non-resizing write implementation
#[inline]
fn slice_write(pos_mut: &mut u64, slice: &mut [u8], buf: &[u8]) -> io::Result<usize> {
let pos = cmp::min(*pos_mut, slice.len() as u64);
let amt = (&mut slice[(pos as usize)..]).write(buf)?;
*pos_mut += amt as u64;
Ok(amt)
}
#[inline]
fn slice_write_vectored(
pos_mut: &mut u64,
slice: &mut [u8],
bufs: &[IoSlice<'_>],
) -> io::Result<usize>
{
let mut nwritten = 0;
for buf in bufs {
let n = slice_write(pos_mut, slice, buf)?;
nwritten += n;
if n < buf.len() {
break;
}
}
Ok(nwritten)
}
// Resizing write implementation
#[cfg(feature="collections")]
fn vec_write(pos_mut: &mut u64, vec: &mut Vec<u8>, buf: &[u8]) -> io::Result<usize> {
let pos: usize = (*pos_mut).try_into().map_err(|_| {
Error::new(ErrorKind::InvalidInput,
"cursor position exceeds maximum possible vector length")
})?;
// Make sure the internal buffer is as least as big as where we
// currently are
let len = vec.len();
if len < pos {
// use `resize` so that the zero filling is as efficient as possible
vec.resize(pos, 0);
}
// Figure out what bytes will be used to overwrite what's currently
// there (left), and what will be appended on the end (right)
{
let space = vec.len() - pos;
let (left, right) = buf.split_at(cmp::min(space, buf.len()));
vec[pos..pos + left.len()].copy_from_slice(left);
vec.extend_from_slice(right);
}
// Bump us forward
*pos_mut = (pos + buf.len()) as u64;
Ok(buf.len())
}
#[cfg(feature="collections")]
fn vec_write_vectored(
pos_mut: &mut u64,
vec: &mut Vec<u8>,
bufs: &[IoSlice<'_>],
) -> io::Result<usize>
{
let mut nwritten = 0;
for buf in bufs {
nwritten += vec_write(pos_mut, vec, buf)?;
}
Ok(nwritten)
}
impl Write for Cursor<&mut [u8]> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
slice_write(&mut self.pos, self.inner, buf)
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
slice_write_vectored(&mut self.pos, self.inner, bufs)
}
#[inline]
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
#[cfg(feature="collections")]
impl Write for Cursor<&mut Vec<u8>> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
vec_write(&mut self.pos, self.inner, buf)
}
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
vec_write_vectored(&mut self.pos, self.inner, bufs)
}
#[inline]
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
#[cfg(feature = "collections")]
impl Write for Cursor<Vec<u8>> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
vec_write(&mut self.pos, &mut self.inner, buf)
}
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
vec_write_vectored(&mut self.pos, &mut self.inner, bufs)
}
#[inline]
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
#[cfg(feature = "alloc")]
impl Write for Cursor<::alloc::boxed::Box<[u8]>> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
slice_write(&mut self.pos, &mut self.inner, buf)
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
slice_write_vectored(&mut self.pos, &mut self.inner, bufs)
}
#[inline]
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
#[cfg(test)]
mod tests {
use crate::io::prelude::*;
use crate::io::{Cursor, SeekFrom, IoSlice, IoSliceMut};
#[test]
fn test_vec_writer() {
let mut writer = Vec::new();
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.write_vectored(
&[IoSlice::new(&[]), IoSlice::new(&[8, 9]), IoSlice::new(&[10])],
).unwrap(), 3);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
assert_eq!(writer, b);
}
#[test]
fn test_mem_writer() {
let mut writer = Cursor::new(Vec::new());
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.write_vectored(
&[IoSlice::new(&[]), IoSlice::new(&[8, 9]), IoSlice::new(&[10])],
).unwrap(), 3);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
assert_eq!(&writer.get_ref()[..], b);
}
#[test]
fn test_mem_mut_writer() {
let mut vec = Vec::new();
let mut writer = Cursor::new(&mut vec);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.write_vectored(
&[IoSlice::new(&[]), IoSlice::new(&[8, 9]), IoSlice::new(&[10])],
).unwrap(), 3);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
assert_eq!(&writer.get_ref()[..], b);
}
#[test]
fn test_box_slice_writer() {
let mut writer = Cursor::new(vec![0u8; 9].into_boxed_slice());
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[]).unwrap(), 0);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[8, 9]).unwrap(), 1);
assert_eq!(writer.write(&[10]).unwrap(), 0);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8];
assert_eq!(&**writer.get_ref(), b);
}
#[test]
fn test_box_slice_writer_vectored() {
let mut writer = Cursor::new(vec![0u8; 9].into_boxed_slice());
assert_eq!(writer.position(), 0);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[0])]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(
writer.write_vectored(&[
IoSlice::new(&[1, 2, 3]),
IoSlice::new(&[4, 5, 6, 7]),
]).unwrap(),
7,
);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write_vectored(&[]).unwrap(), 0);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[8, 9])]).unwrap(), 1);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[10])]).unwrap(), 0);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8];
assert_eq!(&**writer.get_ref(), b);
}
#[test]
fn test_buf_writer() {
let mut buf = [0 as u8; 9];
{
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[]).unwrap(), 0);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[8, 9]).unwrap(), 1);
assert_eq!(writer.write(&[10]).unwrap(), 0);
}
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8];
assert_eq!(buf, b);
}
#[test]
fn test_buf_writer_vectored() {
let mut buf = [0 as u8; 9];
{
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[0])]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(
writer.write_vectored(
&[IoSlice::new(&[1, 2, 3]), IoSlice::new(&[4, 5, 6, 7])],
).unwrap(),
7,
);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write_vectored(&[]).unwrap(), 0);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[8, 9])]).unwrap(), 1);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[10])]).unwrap(), 0);
}
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8];
assert_eq!(buf, b);
}
#[test]
fn test_buf_writer_seek() {
let mut buf = [0 as u8; 8];
{
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[1]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.seek(SeekFrom::Start(2)).unwrap(), 2);
assert_eq!(writer.position(), 2);
assert_eq!(writer.write(&[2]).unwrap(), 1);
assert_eq!(writer.position(), 3);
assert_eq!(writer.seek(SeekFrom::Current(-2)).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[3]).unwrap(), 1);
assert_eq!(writer.position(), 2);
assert_eq!(writer.seek(SeekFrom::End(-1)).unwrap(), 7);
assert_eq!(writer.position(), 7);
assert_eq!(writer.write(&[4]).unwrap(), 1);
assert_eq!(writer.position(), 8);
}
let b: &[_] = &[1, 3, 2, 0, 0, 0, 0, 4];
assert_eq!(buf, b);
}
#[test]
fn test_buf_writer_error() {
let mut buf = [0 as u8; 2];
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[0, 0]).unwrap(), 1);
assert_eq!(writer.write(&[0, 0]).unwrap(), 0);
}
#[test]
fn test_mem_reader() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7]);
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.position(), 5);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(buf, b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_mem_reader_vectored() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7]);
let mut buf = [];
assert_eq!(reader.read_vectored(&mut [IoSliceMut::new(&mut buf)]).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(
reader.read_vectored(&mut [
IoSliceMut::new(&mut []),
IoSliceMut::new(&mut buf),
]).unwrap(),
1,
);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf1 = [0; 4];
let mut buf2 = [0; 4];
assert_eq!(
reader.read_vectored(&mut [
IoSliceMut::new(&mut buf1),
IoSliceMut::new(&mut buf2),
]).unwrap(),
7,
);
let b1: &[_] = &[1, 2, 3, 4];
let b2: &[_] = &[5, 6, 7];
assert_eq!(buf1, b1);
assert_eq!(&buf2[..3], b2);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_boxed_slice_reader() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7].into_boxed_slice());
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.position(), 5);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(buf, b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_boxed_slice_reader_vectored() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7].into_boxed_slice());
let mut buf = [];
assert_eq!(reader.read_vectored(&mut [IoSliceMut::new(&mut buf)]).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(
reader.read_vectored(&mut [
IoSliceMut::new(&mut []),
IoSliceMut::new(&mut buf),
]).unwrap(),
1,
);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf1 = [0; 4];
let mut buf2 = [0; 4];
assert_eq!(
reader.read_vectored(
&mut [IoSliceMut::new(&mut buf1), IoSliceMut::new(&mut buf2)],
).unwrap(),
7,
);
let b1: &[_] = &[1, 2, 3, 4];
let b2: &[_] = &[5, 6, 7];
assert_eq!(buf1, b1);
assert_eq!(&buf2[..3], b2);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn read_to_end() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7]);
let mut v = Vec::new();
reader.read_to_end(&mut v).unwrap();
assert_eq!(v, [0, 1, 2, 3, 4, 5, 6, 7]);
}
#[test]
fn test_slice_reader() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let reader = &mut &in_buf[..];
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.len(), 7);
let b: &[_] = &[0];
assert_eq!(&buf[..], b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.len(), 3);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(&buf[..], b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_slice_reader_vectored() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let reader = &mut &in_buf[..];
let mut buf = [];
assert_eq!(reader.read_vectored(&mut [IoSliceMut::new(&mut buf)]).unwrap(), 0);
let mut buf = [0];
assert_eq!(
reader.read_vectored(&mut [
IoSliceMut::new(&mut []),
IoSliceMut::new(&mut buf),
]).unwrap(),
1,
);
assert_eq!(reader.len(), 7);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf1 = [0; 4];
let mut buf2 = [0; 4];
assert_eq!(
reader.read_vectored(
&mut [IoSliceMut::new(&mut buf1), IoSliceMut::new(&mut buf2)],
).unwrap(),
7,
);
let b1: &[_] = &[1, 2, 3, 4];
let b2: &[_] = &[5, 6, 7];
assert_eq!(buf1, b1);
assert_eq!(&buf2[..3], b2);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_read_exact() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let reader = &mut &in_buf[..];
let mut buf = [];
assert!(reader.read_exact(&mut buf).is_ok());
let mut buf = [8];
assert!(reader.read_exact(&mut buf).is_ok());
assert_eq!(buf[0], 0);
assert_eq!(reader.len(), 7);
let mut buf = [0, 0, 0, 0, 0, 0, 0];
assert!(reader.read_exact(&mut buf).is_ok());
assert_eq!(buf, [1, 2, 3, 4, 5, 6, 7]);
assert_eq!(reader.len(), 0);
let mut buf = [0];
assert!(reader.read_exact(&mut buf).is_err());
}
#[test]
fn test_buf_reader() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let mut reader = Cursor::new(&in_buf[..]);
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.position(), 5);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(buf, b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn seek_past_end() {
let buf = [0xff];
let mut r = Cursor::new(&buf[..]);
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.read(&mut [0]).unwrap(), 0);
let mut r = Cursor::new(vec![10]);
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.read(&mut [0]).unwrap(), 0);
let mut buf = [0];
let mut r = Cursor::new(&mut buf[..]);
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.write(&[3]).unwrap(), 0);
let mut r = Cursor::new(vec![10].into_boxed_slice());
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.write(&[3]).unwrap(), 0);
}
#[test]
fn seek_past_i64() {
let buf = [0xff];
let mut r = Cursor::new(&buf[..]);
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
let mut r = Cursor::new(vec![10]);
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
let mut buf = [0];
let mut r = Cursor::new(&mut buf[..]);
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
let mut r = Cursor::new(vec![10].into_boxed_slice());
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
}
#[test]
fn seek_before_0() {
let buf = [0xff];
let mut r = Cursor::new(&buf[..]);
assert!(r.seek(SeekFrom::End(-2)).is_err());
let mut r = Cursor::new(vec![10]);
assert!(r.seek(SeekFrom::End(-2)).is_err());
let mut buf = [0];
let mut r = Cursor::new(&mut buf[..]);
assert!(r.seek(SeekFrom::End(-2)).is_err());
let mut r = Cursor::new(vec![10].into_boxed_slice());
assert!(r.seek(SeekFrom::End(-2)).is_err());
}
#[test]
fn test_seekable_mem_writer() {
let mut writer = Cursor::new(Vec::<u8>::new());
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.position(), 8);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::Start(0)).unwrap(), 0);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[3, 4]).unwrap(), 2);
let b: &[_] = &[3, 4, 2, 3, 4, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::Current(1)).unwrap(), 3);
assert_eq!(writer.write(&[0, 1]).unwrap(), 2);
let b: &[_] = &[3, 4, 2, 0, 1, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::End(-1)).unwrap(), 7);
assert_eq!(writer.write(&[1, 2]).unwrap(), 2);
let b: &[_] = &[3, 4, 2, 0, 1, 5, 6, 1, 2];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::End(1)).unwrap(), 10);
assert_eq!(writer.write(&[1]).unwrap(), 1);
let b: &[_] = &[3, 4, 2, 0, 1, 5, 6, 1, 2, 0, 1];
assert_eq!(&writer.get_ref()[..], b);
}
#[test]
fn vec_seek_past_end() {
let mut r = Cursor::new(Vec::new());
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.write(&[3]).unwrap(), 1);
}
#[test]
fn vec_seek_before_0() {
let mut r = Cursor::new(Vec::new());
assert!(r.seek(SeekFrom::End(-2)).is_err());
}
#[test]
#[cfg(target_pointer_width = "32")]
fn vec_seek_and_write_past_usize_max() {
let mut c = Cursor::new(Vec::new());
c.set_position(<usize>::max_value() as u64 + 1);
assert!(c.write_all(&[1, 2, 3]).is_err());
}
}

View File

@ -0,0 +1,564 @@
#[cfg(feature="alloc")] use alloc::boxed::Box;
#[cfg(not(feature="alloc"))] use ::FakeBox as Box;
use core::convert::Into;
use core::fmt;
use core::marker::{Send, Sync};
use core::option::Option::{self, Some, None};
use core::result;
#[cfg(feature="collections")] use collections::string::String;
#[cfg(not(feature="collections"))] use ::ErrorString as String;
use core::convert::From;
/// A specialized [`Result`](../result/enum.Result.html) type for I/O
/// operations.
///
/// This type is broadly used across [`std::io`] for any operation which may
/// produce an error.
///
/// This typedef is generally used to avoid writing out [`io::Error`] directly and
/// is otherwise a direct mapping to [`Result`].
///
/// While usual Rust style is to import types directly, aliases of [`Result`]
/// often are not, to make it easier to distinguish between them. [`Result`] is
/// generally assumed to be [`std::result::Result`][`Result`], and so users of this alias
/// will generally use `io::Result` instead of shadowing the prelude's import
/// of [`std::result::Result`][`Result`].
///
/// [`std::io`]: ../io/index.html
/// [`io::Error`]: ../io/struct.Error.html
/// [`Result`]: ../result/enum.Result.html
///
/// # Examples
///
/// A convenience function that bubbles an `io::Result` to its caller:
///
/// ```
/// use std::io;
///
/// fn get_string() -> io::Result<String> {
/// let mut buffer = String::new();
///
/// io::stdin().read_line(&mut buffer)?;
///
/// Ok(buffer)
/// }
/// ```
pub type Result<T> = result::Result<T, Error>;
/// The error type for I/O operations of the [`Read`], [`Write`], [`Seek`], and
/// associated traits.
///
/// Errors mostly originate from the underlying OS, but custom instances of
/// `Error` can be created with crafted error messages and a particular value of
/// [`ErrorKind`].
///
/// [`Read`]: ../io/trait.Read.html
/// [`Write`]: ../io/trait.Write.html
/// [`Seek`]: ../io/trait.Seek.html
/// [`ErrorKind`]: enum.ErrorKind.html
pub struct Error {
repr: Repr,
}
impl fmt::Debug for Error {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt::Debug::fmt(&self.repr, f)
}
}
enum Repr {
Os(i32),
Simple(ErrorKind),
#[cfg(feature="alloc")]
Custom(Box<Custom>),
#[cfg(not(feature="alloc"))]
Custom(Custom),
}
#[derive(Debug)]
struct Custom {
kind: ErrorKind,
error: String,
}
/// A list specifying general categories of I/O error.
///
/// This list is intended to grow over time and it is not recommended to
/// exhaustively match against it.
///
/// It is used with the [`io::Error`] type.
///
/// [`io::Error`]: struct.Error.html
#[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
#[allow(deprecated)]
#[non_exhaustive]
pub enum ErrorKind {
/// An entity was not found, often a file.
NotFound,
/// The operation lacked the necessary privileges to complete.
PermissionDenied,
/// The connection was refused by the remote server.
ConnectionRefused,
/// The connection was reset by the remote server.
ConnectionReset,
/// The connection was aborted (terminated) by the remote server.
ConnectionAborted,
/// The network operation failed because it was not connected yet.
NotConnected,
/// A socket address could not be bound because the address is already in
/// use elsewhere.
AddrInUse,
/// A nonexistent interface was requested or the requested address was not
/// local.
AddrNotAvailable,
/// The operation failed because a pipe was closed.
BrokenPipe,
/// An entity already exists, often a file.
AlreadyExists,
/// The operation needs to block to complete, but the blocking operation was
/// requested to not occur.
WouldBlock,
/// A parameter was incorrect.
InvalidInput,
/// Data not valid for the operation were encountered.
///
/// Unlike [`InvalidInput`], this typically means that the operation
/// parameters were valid, however the error was caused by malformed
/// input data.
///
/// For example, a function that reads a file into a string will error with
/// `InvalidData` if the file's contents are not valid UTF-8.
///
/// [`InvalidInput`]: #variant.InvalidInput
InvalidData,
/// The I/O operation's timeout expired, causing it to be canceled.
TimedOut,
/// An error returned when an operation could not be completed because a
/// call to [`write`] returned [`Ok(0)`].
///
/// This typically means that an operation could only succeed if it wrote a
/// particular number of bytes but only a smaller number of bytes could be
/// written.
///
/// [`write`]: ../../std/io/trait.Write.html#tymethod.write
/// [`Ok(0)`]: ../../std/io/type.Result.html
WriteZero,
/// This operation was interrupted.
///
/// Interrupted operations can typically be retried.
Interrupted,
/// Any I/O error not part of this list.
Other,
/// An error returned when an operation could not be completed because an
/// "end of file" was reached prematurely.
///
/// This typically means that an operation could only succeed if it read a
/// particular number of bytes but only a smaller number of bytes could be
/// read.
UnexpectedEof,
}
impl ErrorKind {
pub(crate) fn as_str(&self) -> &'static str {
match *self {
ErrorKind::NotFound => "entity not found",
ErrorKind::PermissionDenied => "permission denied",
ErrorKind::ConnectionRefused => "connection refused",
ErrorKind::ConnectionReset => "connection reset",
ErrorKind::ConnectionAborted => "connection aborted",
ErrorKind::NotConnected => "not connected",
ErrorKind::AddrInUse => "address in use",
ErrorKind::AddrNotAvailable => "address not available",
ErrorKind::BrokenPipe => "broken pipe",
ErrorKind::AlreadyExists => "entity already exists",
ErrorKind::WouldBlock => "operation would block",
ErrorKind::InvalidInput => "invalid input parameter",
ErrorKind::InvalidData => "invalid data",
ErrorKind::TimedOut => "timed out",
ErrorKind::WriteZero => "write zero",
ErrorKind::Interrupted => "operation interrupted",
ErrorKind::Other => "other os error",
ErrorKind::UnexpectedEof => "unexpected end of file",
}
}
}
/// Intended for use for errors not exposed to the user, where allocating onto
/// the heap (for normal construction via Error::new) is too costly.
impl From<ErrorKind> for Error {
/// Converts an [`ErrorKind`] into an [`Error`].
///
/// This conversion allocates a new error with a simple representation of error kind.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// let not_found = ErrorKind::NotFound;
/// let error = Error::from(not_found);
/// assert_eq!("entity not found", format!("{}", error));
/// ```
///
/// [`ErrorKind`]: ../../std/io/enum.ErrorKind.html
/// [`Error`]: ../../std/io/struct.Error.html
#[inline]
fn from(kind: ErrorKind) -> Error {
Error {
repr: Repr::Simple(kind)
}
}
}
impl Error {
/// Creates a new I/O error from a known kind of error as well as an
/// arbitrary error payload.
///
/// This function is used to generically create I/O errors which do not
/// originate from the OS itself. The `error` argument is an arbitrary
/// payload which will be contained in this `Error`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// // errors can be created from strings
/// let custom_error = Error::new(ErrorKind::Other, "oh no!");
///
/// // errors can also be created from other errors
/// let custom_error2 = Error::new(ErrorKind::Interrupted, custom_error);
/// ```
pub fn new<E>(kind: ErrorKind, error: E) -> Error
where E: Into<String>
{
Self::_new(kind, error.into())
}
fn _new(kind: ErrorKind, error: String) -> Error {
Error {
repr: Repr::Custom(Box::new(Custom {
kind,
error,
}))
}
}
/// Creates a new instance of an `Error` from a particular OS error code.
///
/// # Examples
///
/// On Linux:
///
/// ```
/// # if cfg!(target_os = "linux") {
/// use std::io;
///
/// let error = io::Error::from_raw_os_error(22);
/// assert_eq!(error.kind(), io::ErrorKind::InvalidInput);
/// # }
/// ```
///
/// On Windows:
///
/// ```
/// # if cfg!(windows) {
/// use std::io;
///
/// let error = io::Error::from_raw_os_error(10022);
/// assert_eq!(error.kind(), io::ErrorKind::InvalidInput);
/// # }
/// ```
pub fn from_raw_os_error(code: i32) -> Error {
Error { repr: Repr::Os(code) }
}
/// Returns the OS error that this error represents (if any).
///
/// If this `Error` was constructed via `last_os_error` or
/// `from_raw_os_error`, then this function will return `Some`, otherwise
/// it will return `None`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_os_error(err: &Error) {
/// if let Some(raw_os_err) = err.raw_os_error() {
/// println!("raw OS error: {:?}", raw_os_err);
/// } else {
/// println!("Not an OS error");
/// }
/// }
///
/// fn main() {
/// // Will print "raw OS error: ...".
/// print_os_error(&Error::last_os_error());
/// // Will print "Not an OS error".
/// print_os_error(&Error::new(ErrorKind::Other, "oh no!"));
/// }
/// ```
pub fn raw_os_error(&self) -> Option<i32> {
match self.repr {
Repr::Os(i) => Some(i),
Repr::Custom(..) => None,
Repr::Simple(..) => None,
}
}
/// Returns a reference to the inner error wrapped by this error (if any).
///
/// If this `Error` was constructed via `new` then this function will
/// return `Some`, otherwise it will return `None`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_error(err: &Error) {
/// if let Some(inner_err) = err.get_ref() {
/// println!("Inner error: {:?}", inner_err);
/// } else {
/// println!("No inner error");
/// }
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(&Error::last_os_error());
/// // Will print "Inner error: ...".
/// print_error(&Error::new(ErrorKind::Other, "oh no!"));
/// }
/// ```
pub fn get_ref(&self) -> Option<&String> {
match self.repr {
Repr::Os(..) => None,
Repr::Simple(..) => None,
Repr::Custom(ref c) => Some(&c.error),
}
}
/// Returns a mutable reference to the inner error wrapped by this error
/// (if any).
///
/// If this `Error` was constructed via `new` then this function will
/// return `Some`, otherwise it will return `None`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
/// use std::{error, fmt};
/// use std::fmt::Display;
///
/// #[derive(Debug)]
/// struct MyError {
/// v: String,
/// }
///
/// impl MyError {
/// fn new() -> MyError {
/// MyError {
/// v: "oh no!".to_string()
/// }
/// }
///
/// fn change_message(&mut self, new_message: &str) {
/// self.v = new_message.to_string();
/// }
/// }
///
/// impl error::Error for MyError {
/// fn description(&self) -> &str { &self.v }
/// }
///
/// impl Display for MyError {
/// fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
/// write!(f, "MyError: {}", &self.v)
/// }
/// }
///
/// fn change_error(mut err: Error) -> Error {
/// if let Some(inner_err) = err.get_mut() {
/// inner_err.downcast_mut::<MyError>().unwrap().change_message("I've been changed!");
/// }
/// err
/// }
///
/// fn print_error(err: &Error) {
/// if let Some(inner_err) = err.get_ref() {
/// println!("Inner error: {}", inner_err);
/// } else {
/// println!("No inner error");
/// }
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(&change_error(Error::last_os_error()));
/// // Will print "Inner error: ...".
/// print_error(&change_error(Error::new(ErrorKind::Other, MyError::new())));
/// }
/// ```
pub fn get_mut(&mut self) -> Option<&mut String> {
match self.repr {
Repr::Os(..) => None,
Repr::Simple(..) => None,
Repr::Custom(ref mut c) => Some(&mut c.error),
}
}
/// Consumes the `Error`, returning its inner error (if any).
///
/// If this `Error` was constructed via `new` then this function will
/// return `Some`, otherwise it will return `None`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_error(err: Error) {
/// if let Some(inner_err) = err.into_inner() {
/// println!("Inner error: {}", inner_err);
/// } else {
/// println!("No inner error");
/// }
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(Error::last_os_error());
/// // Will print "Inner error: ...".
/// print_error(Error::new(ErrorKind::Other, "oh no!"));
/// }
/// ```
pub fn into_inner(self) -> Option<String> {
match self.repr {
Repr::Os(..) => None,
Repr::Simple(..) => None,
Repr::Custom(c) => Some(c.error)
}
}
/// Returns the corresponding `ErrorKind` for this error.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_error(err: Error) {
/// println!("{:?}", err.kind());
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(Error::last_os_error());
/// // Will print "Inner error: ...".
/// print_error(Error::new(ErrorKind::AddrInUse, "oh no!"));
/// }
/// ```
pub fn kind(&self) -> ErrorKind {
match self.repr {
Repr::Os(_code) => ErrorKind::Other,
Repr::Custom(ref c) => c.kind,
Repr::Simple(kind) => kind,
}
}
}
impl fmt::Debug for Repr {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
match *self {
Repr::Os(code) =>
fmt.debug_struct("Os")
.field("code", &code).finish(),
Repr::Custom(ref c) => fmt::Debug::fmt(&c, fmt),
Repr::Simple(kind) => fmt.debug_tuple("Kind").field(&kind).finish(),
}
}
}
impl fmt::Display for Error {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
match self.repr {
Repr::Os(code) => {
write!(fmt, "os error {}", code)
}
Repr::Custom(ref c) => c.error.fmt(fmt),
Repr::Simple(kind) => write!(fmt, "{}", kind.as_str()),
}
}
}
fn _assert_error_is_sync_send() {
fn _is_sync_send<T: Sync+Send>() {}
_is_sync_send::<Error>();
}
#[cfg(test)]
mod test {
use super::{Error, ErrorKind, Repr, Custom};
use crate::error;
use crate::fmt;
use crate::sys::os::error_string;
use crate::sys::decode_error_kind;
#[test]
fn test_debug_error() {
let code = 6;
let msg = error_string(code);
let kind = decode_error_kind(code);
let err = Error {
repr: Repr::Custom(box Custom {
kind: ErrorKind::InvalidInput,
error: box Error {
repr: super::Repr::Os(code)
},
})
};
let expected = format!(
"Custom {{ \
kind: InvalidInput, \
error: Os {{ \
code: {:?}, \
kind: {:?}, \
message: {:?} \
}} \
}}",
code, kind, msg
);
assert_eq!(format!("{:?}", err), expected);
}
#[test]
fn test_downcasting() {
#[derive(Debug)]
struct TestError;
impl fmt::Display for TestError {
fn fmt(&self, _: &mut fmt::Formatter<'_>) -> fmt::Result {
Ok(())
}
}
impl error::Error for TestError {
fn description(&self) -> &str {
"asdf"
}
}
// we have to call all of these UFCS style right now since method
// resolution won't implicitly drop the Send+Sync bounds
let mut err = Error::new(ErrorKind::Other, TestError);
assert!(err.get_ref().unwrap().is::<TestError>());
assert_eq!("asdf", err.get_ref().unwrap().description());
assert!(err.get_mut().unwrap().is::<TestError>());
let extracted = err.into_inner().unwrap();
extracted.downcast::<TestError>().unwrap();
}
}

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@ -0,0 +1,400 @@
#[cfg(feature="alloc")] use alloc::boxed::Box;
use core::cmp;
use crate::io::{self, SeekFrom, Read, Initializer, Write, Seek, Error, ErrorKind, IoSliceMut, IoSlice};
#[cfg(feature="collections")] use crate::io::BufRead;
use core::fmt;
use core::mem;
#[cfg(feature="collections")] use collections::string::String;
#[cfg(feature="collections")] use collections::vec::Vec;
// =============================================================================
// Forwarding implementations
impl<R: Read + ?Sized> Read for &mut R {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
(**self).read(buf)
}
#[inline]
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
(**self).read_vectored(bufs)
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
(**self).initializer()
}
#[cfg(feature="collections")]
#[inline]
fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_to_end(buf)
}
#[cfg(feature="collections")]
#[inline]
fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_to_string(buf)
}
#[inline]
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
(**self).read_exact(buf)
}
}
impl<W: Write + ?Sized> Write for &mut W {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> { (**self).write(buf) }
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
(**self).write_vectored(bufs)
}
#[inline]
fn flush(&mut self) -> io::Result<()> { (**self).flush() }
#[inline]
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
(**self).write_all(buf)
}
#[inline]
fn write_fmt(&mut self, fmt: fmt::Arguments<'_>) -> io::Result<()> {
(**self).write_fmt(fmt)
}
}
impl<S: Seek + ?Sized> Seek for &mut S {
#[inline]
fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> { (**self).seek(pos) }
}
#[cfg(feature="collections")]
impl<B: BufRead + ?Sized> BufRead for &mut B {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> { (**self).fill_buf() }
#[inline]
fn consume(&mut self, amt: usize) { (**self).consume(amt) }
#[inline]
fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_until(byte, buf)
}
#[inline]
fn read_line(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_line(buf)
}
}
#[cfg(feature="alloc")]
impl<R: Read + ?Sized> Read for Box<R> {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
(**self).read(buf)
}
#[inline]
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
(**self).read_vectored(bufs)
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
(**self).initializer()
}
#[cfg(feature="collections")]
#[inline]
fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_to_end(buf)
}
#[cfg(feature="collections")]
#[inline]
fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_to_string(buf)
}
#[inline]
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
(**self).read_exact(buf)
}
}
#[cfg(feature="alloc")]
impl<W: Write + ?Sized> Write for Box<W> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> { (**self).write(buf) }
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
(**self).write_vectored(bufs)
}
#[inline]
fn flush(&mut self) -> io::Result<()> { (**self).flush() }
#[inline]
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
(**self).write_all(buf)
}
#[inline]
fn write_fmt(&mut self, fmt: fmt::Arguments<'_>) -> io::Result<()> {
(**self).write_fmt(fmt)
}
}
#[cfg(feature="alloc")]
impl<S: Seek + ?Sized> Seek for Box<S> {
#[inline]
fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> { (**self).seek(pos) }
}
#[cfg(feature="collections")]
impl<B: BufRead + ?Sized> BufRead for Box<B> {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> { (**self).fill_buf() }
#[inline]
fn consume(&mut self, amt: usize) { (**self).consume(amt) }
#[inline]
fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_until(byte, buf)
}
#[inline]
fn read_line(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_line(buf)
}
}
// Used by panicking::default_hook
#[cfg(test)]
/// This impl is only used by printing logic, so any error returned is always
/// of kind `Other`, and should be ignored.
impl Write for Box<dyn (::realstd::io::Write) + Send> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
(**self).write(buf).map_err(|_| ErrorKind::Other.into())
}
fn flush(&mut self) -> io::Result<()> {
(**self).flush().map_err(|_| ErrorKind::Other.into())
}
}
// =============================================================================
// In-memory buffer implementations
/// Read is implemented for `&[u8]` by copying from the slice.
///
/// Note that reading updates the slice to point to the yet unread part.
/// The slice will be empty when EOF is reached.
impl Read for &[u8] {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
let amt = cmp::min(buf.len(), self.len());
let (a, b) = self.split_at(amt);
// First check if the amount of bytes we want to read is small:
// `copy_from_slice` will generally expand to a call to `memcpy`, and
// for a single byte the overhead is significant.
if amt == 1 {
buf[0] = a[0];
} else {
buf[..amt].copy_from_slice(a);
}
*self = b;
Ok(amt)
}
#[inline]
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
let mut nread = 0;
for buf in bufs {
nread += self.read(buf)?;
if self.is_empty() {
break;
}
}
Ok(nread)
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
#[inline]
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
if buf.len() > self.len() {
return Err(Error::new(ErrorKind::UnexpectedEof,
"failed to fill whole buffer"));
}
let (a, b) = self.split_at(buf.len());
// First check if the amount of bytes we want to read is small:
// `copy_from_slice` will generally expand to a call to `memcpy`, and
// for a single byte the overhead is significant.
if buf.len() == 1 {
buf[0] = a[0];
} else {
buf.copy_from_slice(a);
}
*self = b;
Ok(())
}
#[cfg(feature="collections")]
#[inline]
fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
buf.extend_from_slice(*self);
let len = self.len();
*self = &self[len..];
Ok(len)
}
}
#[cfg(feature="collections")]
impl BufRead for &[u8] {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> { Ok(*self) }
#[inline]
fn consume(&mut self, amt: usize) { *self = &self[amt..]; }
}
/// Write is implemented for `&mut [u8]` by copying into the slice, overwriting
/// its data.
///
/// Note that writing updates the slice to point to the yet unwritten part.
/// The slice will be empty when it has been completely overwritten.
impl Write for &mut [u8] {
#[inline]
fn write(&mut self, data: &[u8]) -> io::Result<usize> {
let amt = cmp::min(data.len(), self.len());
let (a, b) = mem::replace(self, &mut []).split_at_mut(amt);
a.copy_from_slice(&data[..amt]);
*self = b;
Ok(amt)
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
let mut nwritten = 0;
for buf in bufs {
nwritten += self.write(buf)?;
if self.is_empty() {
break;
}
}
Ok(nwritten)
}
#[inline]
fn write_all(&mut self, data: &[u8]) -> io::Result<()> {
if self.write(data)? == data.len() {
Ok(())
} else {
Err(Error::new(ErrorKind::WriteZero, "failed to write whole buffer"))
}
}
#[inline]
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
/// Write is implemented for `Vec<u8>` by appending to the vector.
/// The vector will grow as needed.
#[cfg(feature="collections")]
impl Write for Vec<u8> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
self.extend_from_slice(buf);
Ok(buf.len())
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
let len = bufs.iter().map(|b| b.len()).sum();
self.reserve(len);
for buf in bufs {
self.extend_from_slice(buf);
}
Ok(len)
}
#[inline]
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
self.extend_from_slice(buf);
Ok(())
}
#[inline]
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
#[cfg(test)]
mod tests {
use crate::io::prelude::*;
#[bench]
fn bench_read_slice(b: &mut test::Bencher) {
let buf = [5; 1024];
let mut dst = [0; 128];
b.iter(|| {
let mut rd = &buf[..];
for _ in 0..8 {
let _ = rd.read(&mut dst);
test::black_box(&dst);
}
})
}
#[bench]
fn bench_write_slice(b: &mut test::Bencher) {
let mut buf = [0; 1024];
let src = [5; 128];
b.iter(|| {
let mut wr = &mut buf[..];
for _ in 0..8 {
let _ = wr.write_all(&src);
test::black_box(&wr);
}
})
}
#[bench]
fn bench_read_vec(b: &mut test::Bencher) {
let buf = vec![5; 1024];
let mut dst = [0; 128];
b.iter(|| {
let mut rd = &buf[..];
for _ in 0..8 {
let _ = rd.read(&mut dst);
test::black_box(&dst);
}
})
}
#[bench]
fn bench_write_vec(b: &mut test::Bencher) {
let mut buf = Vec::with_capacity(1024);
let src = [5; 128];
b.iter(|| {
let mut wr = &mut buf[..];
for _ in 0..8 {
let _ = wr.write_all(&src);
test::black_box(&wr);
}
})
}
}

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//! The I/O Prelude
//!
//! The purpose of this module is to alleviate imports of many common I/O traits
//! by adding a glob import to the top of I/O heavy modules:
//!
//! ```
//! # #![allow(unused_imports)]
//! use std::io::prelude::*;
//! ```
pub use super::{Read, Write, Seek};
#[cfg(feature="collections")] pub use super::BufRead;
#[cfg(feature="collections")] pub use alloc::boxed::Box;
#[cfg(feature="collections")] pub use collections::vec::Vec;

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#![allow(missing_copy_implementations)]
use core::fmt;
use crate::io::{self, Read, Initializer, Write, ErrorKind, IoSlice, IoSliceMut};
#[cfg(feature="collections")] use crate::io::BufRead;
use core::mem;
/// Copies the entire contents of a reader into a writer.
///
/// This function will continuously read data from `reader` and then
/// write it into `writer` in a streaming fashion until `reader`
/// returns EOF.
///
/// On success, the total number of bytes that were copied from
/// `reader` to `writer` is returned.
///
/// If youre wanting to copy the contents of one file to another and youre
/// working with filesystem paths, see the [`fs::copy`] function.
///
/// [`fs::copy`]: ../fs/fn.copy.html
///
/// # Errors
///
/// This function will return an error immediately if any call to `read` or
/// `write` returns an error. All instances of `ErrorKind::Interrupted` are
/// handled by this function and the underlying operation is retried.
///
/// # Examples
///
/// ```
/// use std::io;
///
/// fn main() -> io::Result<()> {
/// let mut reader: &[u8] = b"hello";
/// let mut writer: Vec<u8> = vec![];
///
/// io::copy(&mut reader, &mut writer)?;
///
/// assert_eq!(&b"hello"[..], &writer[..]);
/// Ok(())
/// }
/// ```
pub fn copy<R: ?Sized, W: ?Sized>(reader: &mut R, writer: &mut W) -> io::Result<u64>
where R: Read, W: Write
{
let mut buf = unsafe {
// This is still technically undefined behavior due to creating a reference
// to uninitialized data, but within libstd we can rely on more guarantees
// than if this code were in an external lib
// FIXME: This should probably be changed to an array of `MaybeUninit<u8>`
// once the `mem::MaybeUninit` slice APIs stabilize
let mut buf: mem::MaybeUninit<[u8; super::DEFAULT_BUF_SIZE]> = mem::MaybeUninit::uninit();
reader.initializer().initialize(&mut *buf.as_mut_ptr());
buf.assume_init()
};
let mut written = 0;
loop {
let len = match reader.read(&mut buf) {
Ok(0) => return Ok(written),
Ok(len) => len,
Err(ref e) if e.kind() == ErrorKind::Interrupted => continue,
Err(e) => return Err(e),
};
writer.write_all(&buf[..len])?;
written += len as u64;
}
}
/// A reader which is always at EOF.
///
/// This struct is generally created by calling [`empty`]. Please see
/// the documentation of [`empty()`][`empty`] for more details.
///
/// [`empty`]: fn.empty.html
pub struct Empty { _priv: () }
/// Constructs a new handle to an empty reader.
///
/// All reads from the returned reader will return [`Ok`]`(0)`.
///
/// [`Ok`]: ../result/enum.Result.html#variant.Ok
///
/// # Examples
///
/// A slightly sad example of not reading anything into a buffer:
///
/// ```
/// use std::io::{self, Read};
///
/// let mut buffer = String::new();
/// io::empty().read_to_string(&mut buffer).unwrap();
/// assert!(buffer.is_empty());
/// ```
pub fn empty() -> Empty { Empty { _priv: () } }
impl Read for Empty {
#[inline]
fn read(&mut self, _buf: &mut [u8]) -> io::Result<usize> { Ok(0) }
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
}
#[cfg(feature="collections")]
impl BufRead for Empty {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> { Ok(&[]) }
#[inline]
fn consume(&mut self, _n: usize) {}
}
impl fmt::Debug for Empty {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.pad("Empty { .. }")
}
}
/// A reader which yields one byte over and over and over and over and over and...
///
/// This struct is generally created by calling [`repeat`][repeat]. Please
/// see the documentation of `repeat()` for more details.
///
/// [repeat]: fn.repeat.html
pub struct Repeat { byte: u8 }
/// Creates an instance of a reader that infinitely repeats one byte.
///
/// All reads from this reader will succeed by filling the specified buffer with
/// the given byte.
///
/// # Examples
///
/// ```
/// use std::io::{self, Read};
///
/// let mut buffer = [0; 3];
/// io::repeat(0b101).read_exact(&mut buffer).unwrap();
/// assert_eq!(buffer, [0b101, 0b101, 0b101]);
/// ```
pub fn repeat(byte: u8) -> Repeat { Repeat { byte } }
impl Read for Repeat {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
for slot in &mut *buf {
*slot = self.byte;
}
Ok(buf.len())
}
#[inline]
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
let mut nwritten = 0;
for buf in bufs {
nwritten += self.read(buf)?;
}
Ok(nwritten)
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
}
impl fmt::Debug for Repeat {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.pad("Repeat { .. }")
}
}
/// A writer which will move data into the void.
///
/// This struct is generally created by calling [`sink`][sink]. Please
/// see the documentation of `sink()` for more details.
///
/// [sink]: fn.sink.html
pub struct Sink { _priv: () }
/// Creates an instance of a writer which will successfully consume all data.
///
/// All calls to `write` on the returned instance will return `Ok(buf.len())`
/// and the contents of the buffer will not be inspected.
///
/// # Examples
///
/// ```rust
/// use std::io::{self, Write};
///
/// let buffer = vec![1, 2, 3, 5, 8];
/// let num_bytes = io::sink().write(&buffer).unwrap();
/// assert_eq!(num_bytes, 5);
/// ```
pub fn sink() -> Sink { Sink { _priv: () } }
impl Write for Sink {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> { Ok(buf.len()) }
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
let total_len = bufs.iter().map(|b| b.len()).sum();
Ok(total_len)
}
#[inline]
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
impl fmt::Debug for Sink {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.pad("Sink { .. }")
}
}
#[cfg(test)]
mod tests {
use crate::io::prelude::*;
use crate::io::{copy, sink, empty, repeat};
#[test]
fn copy_copies() {
let mut r = repeat(0).take(4);
let mut w = sink();
assert_eq!(copy(&mut r, &mut w).unwrap(), 4);
let mut r = repeat(0).take(1 << 17);
assert_eq!(copy(&mut r as &mut dyn Read, &mut w as &mut dyn Write).unwrap(), 1 << 17);
}
#[test]
fn sink_sinks() {
let mut s = sink();
assert_eq!(s.write(&[]).unwrap(), 0);
assert_eq!(s.write(&[0]).unwrap(), 1);
assert_eq!(s.write(&[0; 1024]).unwrap(), 1024);
assert_eq!(s.by_ref().write(&[0; 1024]).unwrap(), 1024);
}
#[test]
fn empty_reads() {
let mut e = empty();
assert_eq!(e.read(&mut []).unwrap(), 0);
assert_eq!(e.read(&mut [0]).unwrap(), 0);
assert_eq!(e.read(&mut [0; 1024]).unwrap(), 0);
assert_eq!(e.by_ref().read(&mut [0; 1024]).unwrap(), 0);
}
#[test]
fn repeat_repeats() {
let mut r = repeat(4);
let mut b = [0; 1024];
assert_eq!(r.read(&mut b).unwrap(), 1024);
assert!(b.iter().all(|b| *b == 4));
}
#[test]
fn take_some_bytes() {
assert_eq!(repeat(4).take(100).bytes().count(), 100);
assert_eq!(repeat(4).take(100).bytes().next().unwrap().unwrap(), 4);
assert_eq!(repeat(1).take(10).chain(repeat(2).take(10)).bytes().count(), 20);
}
}

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@ -0,0 +1,412 @@
use core::cmp;
use core::fmt;
use crate::io::{self, BufRead, Initializer, IoSliceMut, Read, Seek, SeekFrom, DEFAULT_BUF_SIZE};
use crate::io::prelude::*;
/// The `BufReader<R>` struct adds buffering to any reader.
///
/// It can be excessively inefficient to work directly with a [`Read`] instance.
/// For example, every call to [`read`][`TcpStream::read`] on [`TcpStream`]
/// results in a system call. A `BufReader<R>` performs large, infrequent reads on
/// the underlying [`Read`] and maintains an in-memory buffer of the results.
///
/// `BufReader<R>` can improve the speed of programs that make *small* and
/// *repeated* read calls to the same file or network socket. It does not
/// help when reading very large amounts at once, or reading just one or a few
/// times. It also provides no advantage when reading from a source that is
/// already in memory, like a [`Vec`]`<u8>`.
///
/// When the `BufReader<R>` is dropped, the contents of its buffer will be
/// discarded. Creating multiple instances of a `BufReader<R>` on the same
/// stream can cause data loss. Reading from the underlying reader after
/// unwrapping the `BufReader<R>` with [`BufReader::into_inner`] can also cause
/// data loss.
///
// HACK(#78696): can't use `crate` for associated items
/// [`TcpStream::read`]: super::super::super::net::TcpStream::read
/// [`TcpStream`]: crate::net::TcpStream
///
/// # Examples
///
/// ```no_run
/// use std::io::prelude::*;
/// use std::io::BufReader;
/// use std::fs::File;
///
/// fn main() -> std::io::Result<()> {
/// let f = File::open("log.txt")?;
/// let mut reader = BufReader::new(f);
///
/// let mut line = String::new();
/// let len = reader.read_line(&mut line)?;
/// println!("First line is {} bytes long", len);
/// Ok(())
/// }
/// ```
pub struct BufReader<R> {
inner: R,
buf: Box<[u8]>,
pos: usize,
cap: usize,
}
impl<R: Read> BufReader<R> {
/// Creates a new `BufReader<R>` with a default buffer capacity. The default is currently 8 KB,
/// but may change in the future.
///
/// # Examples
///
/// ```no_run
/// use std::io::BufReader;
/// use std::fs::File;
///
/// fn main() -> std::io::Result<()> {
/// let f = File::open("log.txt")?;
/// let reader = BufReader::new(f);
/// Ok(())
/// }
/// ```
pub fn new(inner: R) -> BufReader<R> {
BufReader::with_capacity(DEFAULT_BUF_SIZE, inner)
}
/// Creates a new `BufReader<R>` with the specified buffer capacity.
///
/// # Examples
///
/// Creating a buffer with ten bytes of capacity:
///
/// ```no_run
/// use std::io::BufReader;
/// use std::fs::File;
///
/// fn main() -> std::io::Result<()> {
/// let f = File::open("log.txt")?;
/// let reader = BufReader::with_capacity(10, f);
/// Ok(())
/// }
/// ```
pub fn with_capacity(capacity: usize, inner: R) -> BufReader<R> {
unsafe {
let mut buffer = Vec::with_capacity(capacity);
buffer.set_len(capacity);
inner.initializer().initialize(&mut buffer);
BufReader { inner, buf: buffer.into_boxed_slice(), pos: 0, cap: 0 }
}
}
}
impl<R> BufReader<R> {
/// Gets a reference to the underlying reader.
///
/// It is inadvisable to directly read from the underlying reader.
///
/// # Examples
///
/// ```no_run
/// use std::io::BufReader;
/// use std::fs::File;
///
/// fn main() -> std::io::Result<()> {
/// let f1 = File::open("log.txt")?;
/// let reader = BufReader::new(f1);
///
/// let f2 = reader.get_ref();
/// Ok(())
/// }
/// ```
pub fn get_ref(&self) -> &R {
&self.inner
}
/// Gets a mutable reference to the underlying reader.
///
/// It is inadvisable to directly read from the underlying reader.
///
/// # Examples
///
/// ```no_run
/// use std::io::BufReader;
/// use std::fs::File;
///
/// fn main() -> std::io::Result<()> {
/// let f1 = File::open("log.txt")?;
/// let mut reader = BufReader::new(f1);
///
/// let f2 = reader.get_mut();
/// Ok(())
/// }
/// ```
pub fn get_mut(&mut self) -> &mut R {
&mut self.inner
}
/// Returns a reference to the internally buffered data.
///
/// Unlike [`fill_buf`], this will not attempt to fill the buffer if it is empty.
///
/// [`fill_buf`]: BufRead::fill_buf
///
/// # Examples
///
/// ```no_run
/// use std::io::{BufReader, BufRead};
/// use std::fs::File;
///
/// fn main() -> std::io::Result<()> {
/// let f = File::open("log.txt")?;
/// let mut reader = BufReader::new(f);
/// assert!(reader.buffer().is_empty());
///
/// if reader.fill_buf()?.len() > 0 {
/// assert!(!reader.buffer().is_empty());
/// }
/// Ok(())
/// }
/// ```
pub fn buffer(&self) -> &[u8] {
&self.buf[self.pos..self.cap]
}
/// Returns the number of bytes the internal buffer can hold at once.
///
/// # Examples
///
/// ```no_run
/// use std::io::{BufReader, BufRead};
/// use std::fs::File;
///
/// fn main() -> std::io::Result<()> {
/// let f = File::open("log.txt")?;
/// let mut reader = BufReader::new(f);
///
/// let capacity = reader.capacity();
/// let buffer = reader.fill_buf()?;
/// assert!(buffer.len() <= capacity);
/// Ok(())
/// }
/// ```
pub fn capacity(&self) -> usize {
self.buf.len()
}
/// Unwraps this `BufReader<R>`, returning the underlying reader.
///
/// Note that any leftover data in the internal buffer is lost. Therefore,
/// a following read from the underlying reader may lead to data loss.
///
/// # Examples
///
/// ```no_run
/// use std::io::BufReader;
/// use std::fs::File;
///
/// fn main() -> std::io::Result<()> {
/// let f1 = File::open("log.txt")?;
/// let reader = BufReader::new(f1);
///
/// let f2 = reader.into_inner();
/// Ok(())
/// }
/// ```
pub fn into_inner(self) -> R {
self.inner
}
/// Invalidates all data in the internal buffer.
#[inline]
fn discard_buffer(&mut self) {
self.pos = 0;
self.cap = 0;
}
}
impl<R: Seek> BufReader<R> {
/// Seeks relative to the current position. If the new position lies within the buffer,
/// the buffer will not be flushed, allowing for more efficient seeks.
/// This method does not return the location of the underlying reader, so the caller
/// must track this information themselves if it is required.
pub fn seek_relative(&mut self, offset: i64) -> io::Result<()> {
let pos = self.pos as u64;
if offset < 0 {
if let Some(new_pos) = pos.checked_sub((-offset) as u64) {
self.pos = new_pos as usize;
return Ok(());
}
} else {
if let Some(new_pos) = pos.checked_add(offset as u64) {
if new_pos <= self.cap as u64 {
self.pos = new_pos as usize;
return Ok(());
}
}
}
self.seek(SeekFrom::Current(offset)).map(drop)
}
}
impl<R: Read> Read for BufReader<R> {
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
// If we don't have any buffered data and we're doing a massive read
// (larger than our internal buffer), bypass our internal buffer
// entirely.
if self.pos == self.cap && buf.len() >= self.buf.len() {
self.discard_buffer();
return self.inner.read(buf);
}
let nread = {
let mut rem = self.fill_buf()?;
rem.read(buf)?
};
self.consume(nread);
Ok(nread)
}
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
let total_len = bufs.iter().map(|b| b.len()).sum::<usize>();
if self.pos == self.cap && total_len >= self.buf.len() {
self.discard_buffer();
return self.inner.read_vectored(bufs);
}
let nread = {
let mut rem = self.fill_buf()?;
rem.read_vectored(bufs)?
};
self.consume(nread);
Ok(nread)
}
fn is_read_vectored(&self) -> bool {
self.inner.is_read_vectored()
}
// we can't skip unconditionally because of the large buffer case in read.
unsafe fn initializer(&self) -> Initializer {
self.inner.initializer()
}
}
impl<R: Read> BufRead for BufReader<R> {
fn fill_buf(&mut self) -> io::Result<&[u8]> {
// If we've reached the end of our internal buffer then we need to fetch
// some more data from the underlying reader.
// Branch using `>=` instead of the more correct `==`
// to tell the compiler that the pos..cap slice is always valid.
if self.pos >= self.cap {
debug_assert!(self.pos == self.cap);
self.cap = self.inner.read(&mut self.buf)?;
self.pos = 0;
}
Ok(&self.buf[self.pos..self.cap])
}
fn consume(&mut self, amt: usize) {
self.pos = cmp::min(self.pos + amt, self.cap);
}
}
impl<R> fmt::Debug for BufReader<R>
where
R: fmt::Debug,
{
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt.debug_struct("BufReader")
.field("reader", &self.inner)
.field("buffer", &format_args!("{}/{}", self.cap - self.pos, self.buf.len()))
.finish()
}
}
impl<R: Seek> Seek for BufReader<R> {
/// Seek to an offset, in bytes, in the underlying reader.
///
/// The position used for seeking with [`SeekFrom::Current`]`(_)` is the
/// position the underlying reader would be at if the `BufReader<R>` had no
/// internal buffer.
///
/// Seeking always discards the internal buffer, even if the seek position
/// would otherwise fall within it. This guarantees that calling
/// [`BufReader::into_inner()`] immediately after a seek yields the underlying reader
/// at the same position.
///
/// To seek without discarding the internal buffer, use [`BufReader::seek_relative`].
///
/// See [`std::io::Seek`] for more details.
///
/// Note: In the edge case where you're seeking with [`SeekFrom::Current`]`(n)`
/// where `n` minus the internal buffer length overflows an `i64`, two
/// seeks will be performed instead of one. If the second seek returns
/// [`Err`], the underlying reader will be left at the same position it would
/// have if you called `seek` with [`SeekFrom::Current`]`(0)`.
///
/// [`std::io::Seek`]: Seek
fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
let result: u64;
if let SeekFrom::Current(n) = pos {
let remainder = (self.cap - self.pos) as i64;
// it should be safe to assume that remainder fits within an i64 as the alternative
// means we managed to allocate 8 exbibytes and that's absurd.
// But it's not out of the realm of possibility for some weird underlying reader to
// support seeking by i64::MIN so we need to handle underflow when subtracting
// remainder.
if let Some(offset) = n.checked_sub(remainder) {
result = self.inner.seek(SeekFrom::Current(offset))?;
} else {
// seek backwards by our remainder, and then by the offset
self.inner.seek(SeekFrom::Current(-remainder))?;
self.discard_buffer();
result = self.inner.seek(SeekFrom::Current(n))?;
}
} else {
// Seeking with Start/End doesn't care about our buffer length.
result = self.inner.seek(pos)?;
}
self.discard_buffer();
Ok(result)
}
/// Returns the current seek position from the start of the stream.
///
/// The value returned is equivalent to `self.seek(SeekFrom::Current(0))`
/// but does not flush the internal buffer. Due to this optimization the
/// function does not guarantee that calling `.into_inner()` immediately
/// afterwards will yield the underlying reader at the same position. Use
/// [`BufReader::seek`] instead if you require that guarantee.
///
/// # Panics
///
/// This function will panic if the position of the inner reader is smaller
/// than the amount of buffered data. That can happen if the inner reader
/// has an incorrect implementation of [`Seek::stream_position`], or if the
/// position has gone out of sync due to calling [`Seek::seek`] directly on
/// the underlying reader.
///
/// # Example
///
/// ```no_run
/// #![feature(seek_convenience)]
/// use std::{
/// io::{self, BufRead, BufReader, Seek},
/// fs::File,
/// };
///
/// fn main() -> io::Result<()> {
/// let mut f = BufReader::new(File::open("foo.txt")?);
///
/// let before = f.stream_position()?;
/// f.read_line(&mut String::new())?;
/// let after = f.stream_position()?;
///
/// println!("The first line was {} bytes long", after - before);
/// Ok(())
/// }
/// ```
fn stream_position(&mut self) -> io::Result<u64> {
let remainder = (self.cap - self.pos) as u64;
self.inner.stream_position().map(|pos| {
pos.checked_sub(remainder).expect(
"overflow when subtracting remaining buffer size from inner stream position",
)
})
}
}

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use core::fmt;
use crate::io::{
self, Error, ErrorKind, IntoInnerError, IoSlice, Seek, SeekFrom, Write, DEFAULT_BUF_SIZE,
};
use crate::io::prelude::*;
/// Wraps a writer and buffers its output.
///
/// It can be excessively inefficient to work directly with something that
/// implements [`Write`]. For example, every call to
/// [`write`][`TcpStream::write`] on [`TcpStream`] results in a system call. A
/// `BufWriter<W>` keeps an in-memory buffer of data and writes it to an underlying
/// writer in large, infrequent batches.
///
/// `BufWriter<W>` can improve the speed of programs that make *small* and
/// *repeated* write calls to the same file or network socket. It does not
/// help when writing very large amounts at once, or writing just one or a few
/// times. It also provides no advantage when writing to a destination that is
/// in memory, like a [`Vec`]`<u8>`.
///
/// It is critical to call [`flush`] before `BufWriter<W>` is dropped. Though
/// dropping will attempt to flush the contents of the buffer, any errors
/// that happen in the process of dropping will be ignored. Calling [`flush`]
/// ensures that the buffer is empty and thus dropping will not even attempt
/// file operations.
///
/// # Examples
///
/// Let's write the numbers one through ten to a [`TcpStream`]:
///
/// ```no_run
/// use std::io::prelude::*;
/// use std::net::TcpStream;
///
/// let mut stream = TcpStream::connect("127.0.0.1:34254").unwrap();
///
/// for i in 0..10 {
/// stream.write(&[i+1]).unwrap();
/// }
/// ```
///
/// Because we're not buffering, we write each one in turn, incurring the
/// overhead of a system call per byte written. We can fix this with a
/// `BufWriter<W>`:
///
/// ```no_run
/// use std::io::prelude::*;
/// use std::io::BufWriter;
/// use std::net::TcpStream;
///
/// let mut stream = BufWriter::new(TcpStream::connect("127.0.0.1:34254").unwrap());
///
/// for i in 0..10 {
/// stream.write(&[i+1]).unwrap();
/// }
/// stream.flush().unwrap();
/// ```
///
/// By wrapping the stream with a `BufWriter<W>`, these ten writes are all grouped
/// together by the buffer and will all be written out in one system call when
/// the `stream` is flushed.
///
// HACK(#78696): can't use `crate` for associated items
/// [`TcpStream::write`]: super::super::super::net::TcpStream::write
/// [`TcpStream`]: crate::net::TcpStream
/// [`flush`]: BufWriter::flush
pub struct BufWriter<W: Write> {
inner: Option<W>,
buf: Vec<u8>,
// #30888: If the inner writer panics in a call to write, we don't want to
// write the buffered data a second time in BufWriter's destructor. This
// flag tells the Drop impl if it should skip the flush.
panicked: bool,
}
impl<W: Write> BufWriter<W> {
/// Creates a new `BufWriter<W>` with a default buffer capacity. The default is currently 8 KB,
/// but may change in the future.
///
/// # Examples
///
/// ```no_run
/// use std::io::BufWriter;
/// use std::net::TcpStream;
///
/// let mut buffer = BufWriter::new(TcpStream::connect("127.0.0.1:34254").unwrap());
/// ```
pub fn new(inner: W) -> BufWriter<W> {
BufWriter::with_capacity(DEFAULT_BUF_SIZE, inner)
}
/// Creates a new `BufWriter<W>` with the specified buffer capacity.
///
/// # Examples
///
/// Creating a buffer with a buffer of a hundred bytes.
///
/// ```no_run
/// use std::io::BufWriter;
/// use std::net::TcpStream;
///
/// let stream = TcpStream::connect("127.0.0.1:34254").unwrap();
/// let mut buffer = BufWriter::with_capacity(100, stream);
/// ```
pub fn with_capacity(capacity: usize, inner: W) -> BufWriter<W> {
BufWriter { inner: Some(inner), buf: Vec::with_capacity(capacity), panicked: false }
}
/// Send data in our local buffer into the inner writer, looping as
/// necessary until either it's all been sent or an error occurs.
///
/// Because all the data in the buffer has been reported to our owner as
/// "successfully written" (by returning nonzero success values from
/// `write`), any 0-length writes from `inner` must be reported as i/o
/// errors from this method.
pub(super) fn flush_buf(&mut self) -> io::Result<()> {
/// Helper struct to ensure the buffer is updated after all the writes
/// are complete. It tracks the number of written bytes and drains them
/// all from the front of the buffer when dropped.
struct BufGuard<'a> {
buffer: &'a mut Vec<u8>,
written: usize,
}
impl<'a> BufGuard<'a> {
fn new(buffer: &'a mut Vec<u8>) -> Self {
Self { buffer, written: 0 }
}
/// The unwritten part of the buffer
fn remaining(&self) -> &[u8] {
&self.buffer[self.written..]
}
/// Flag some bytes as removed from the front of the buffer
fn consume(&mut self, amt: usize) {
self.written += amt;
}
/// true if all of the bytes have been written
fn done(&self) -> bool {
self.written >= self.buffer.len()
}
}
impl Drop for BufGuard<'_> {
fn drop(&mut self) {
if self.written > 0 {
self.buffer.drain(..self.written);
}
}
}
let mut guard = BufGuard::new(&mut self.buf);
let inner = self.inner.as_mut().unwrap();
while !guard.done() {
self.panicked = true;
let r = inner.write(guard.remaining());
self.panicked = false;
match r {
Ok(0) => {
return Err(Error::new(
ErrorKind::WriteZero,
"failed to write the buffered data",
));
}
Ok(n) => guard.consume(n),
Err(ref e) if e.kind() == io::ErrorKind::Interrupted => {}
Err(e) => return Err(e),
}
}
Ok(())
}
/// Buffer some data without flushing it, regardless of the size of the
/// data. Writes as much as possible without exceeding capacity. Returns
/// the number of bytes written.
pub(super) fn write_to_buf(&mut self, buf: &[u8]) -> usize {
let available = self.buf.capacity() - self.buf.len();
let amt_to_buffer = available.min(buf.len());
self.buf.extend_from_slice(&buf[..amt_to_buffer]);
amt_to_buffer
}
/// Gets a reference to the underlying writer.
///
/// # Examples
///
/// ```no_run
/// use std::io::BufWriter;
/// use std::net::TcpStream;
///
/// let mut buffer = BufWriter::new(TcpStream::connect("127.0.0.1:34254").unwrap());
///
/// // we can use reference just like buffer
/// let reference = buffer.get_ref();
/// ```
pub fn get_ref(&self) -> &W {
self.inner.as_ref().unwrap()
}
/// Gets a mutable reference to the underlying writer.
///
/// It is inadvisable to directly write to the underlying writer.
///
/// # Examples
///
/// ```no_run
/// use std::io::BufWriter;
/// use std::net::TcpStream;
///
/// let mut buffer = BufWriter::new(TcpStream::connect("127.0.0.1:34254").unwrap());
///
/// // we can use reference just like buffer
/// let reference = buffer.get_mut();
/// ```
pub fn get_mut(&mut self) -> &mut W {
self.inner.as_mut().unwrap()
}
/// Returns a reference to the internally buffered data.
///
/// # Examples
///
/// ```no_run
/// use std::io::BufWriter;
/// use std::net::TcpStream;
///
/// let buf_writer = BufWriter::new(TcpStream::connect("127.0.0.1:34254").unwrap());
///
/// // See how many bytes are currently buffered
/// let bytes_buffered = buf_writer.buffer().len();
/// ```
pub fn buffer(&self) -> &[u8] {
&self.buf
}
/// Returns the number of bytes the internal buffer can hold without flushing.
///
/// # Examples
///
/// ```no_run
/// use std::io::BufWriter;
/// use std::net::TcpStream;
///
/// let buf_writer = BufWriter::new(TcpStream::connect("127.0.0.1:34254").unwrap());
///
/// // Check the capacity of the inner buffer
/// let capacity = buf_writer.capacity();
/// // Calculate how many bytes can be written without flushing
/// let without_flush = capacity - buf_writer.buffer().len();
/// ```
pub fn capacity(&self) -> usize {
self.buf.capacity()
}
/// Unwraps this `BufWriter<W>`, returning the underlying writer.
///
/// The buffer is written out before returning the writer.
///
/// # Errors
///
/// An [`Err`] will be returned if an error occurs while flushing the buffer.
///
/// # Examples
///
/// ```no_run
/// use std::io::BufWriter;
/// use std::net::TcpStream;
///
/// let mut buffer = BufWriter::new(TcpStream::connect("127.0.0.1:34254").unwrap());
///
/// // unwrap the TcpStream and flush the buffer
/// let stream = buffer.into_inner().unwrap();
/// ```
pub fn into_inner(mut self) -> Result<W, IntoInnerError<BufWriter<W>>> {
match self.flush_buf() {
Err(e) => Err(IntoInnerError::new(self, e)),
Ok(()) => Ok(self.inner.take().unwrap()),
}
}
}
impl<W: Write> Write for BufWriter<W> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
if self.buf.len() + buf.len() > self.buf.capacity() {
self.flush_buf()?;
}
// FIXME: Why no len > capacity? Why not buffer len == capacity? #72919
if buf.len() >= self.buf.capacity() {
self.panicked = true;
let r = self.get_mut().write(buf);
self.panicked = false;
r
} else {
self.buf.extend_from_slice(buf);
Ok(buf.len())
}
}
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
// Normally, `write_all` just calls `write` in a loop. We can do better
// by calling `self.get_mut().write_all()` directly, which avoids
// round trips through the buffer in the event of a series of partial
// writes in some circumstances.
if self.buf.len() + buf.len() > self.buf.capacity() {
self.flush_buf()?;
}
// FIXME: Why no len > capacity? Why not buffer len == capacity? #72919
if buf.len() >= self.buf.capacity() {
self.panicked = true;
let r = self.get_mut().write_all(buf);
self.panicked = false;
r
} else {
self.buf.extend_from_slice(buf);
Ok(())
}
}
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
if self.get_ref().is_write_vectored() {
let total_len = bufs.iter().map(|b| b.len()).sum::<usize>();
if self.buf.len() + total_len > self.buf.capacity() {
self.flush_buf()?;
}
if total_len >= self.buf.capacity() {
self.panicked = true;
let r = self.get_mut().write_vectored(bufs);
self.panicked = false;
r
} else {
bufs.iter().for_each(|b| self.buf.extend_from_slice(b));
Ok(total_len)
}
} else {
let mut iter = bufs.iter();
let mut total_written = if let Some(buf) = iter.by_ref().find(|&buf| !buf.is_empty()) {
// This is the first non-empty slice to write, so if it does
// not fit in the buffer, we still get to flush and proceed.
if self.buf.len() + buf.len() > self.buf.capacity() {
self.flush_buf()?;
}
if buf.len() >= self.buf.capacity() {
// The slice is at least as large as the buffering capacity,
// so it's better to write it directly, bypassing the buffer.
self.panicked = true;
let r = self.get_mut().write(buf);
self.panicked = false;
return r;
} else {
self.buf.extend_from_slice(buf);
buf.len()
}
} else {
return Ok(0);
};
debug_assert!(total_written != 0);
for buf in iter {
if self.buf.len() + buf.len() > self.buf.capacity() {
break;
} else {
self.buf.extend_from_slice(buf);
total_written += buf.len();
}
}
Ok(total_written)
}
}
fn is_write_vectored(&self) -> bool {
true
}
fn flush(&mut self) -> io::Result<()> {
self.flush_buf().and_then(|()| self.get_mut().flush())
}
}
impl<W: Write> fmt::Debug for BufWriter<W>
where
W: fmt::Debug,
{
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt.debug_struct("BufWriter")
.field("writer", &self.inner.as_ref().unwrap())
.field("buffer", &format_args!("{}/{}", self.buf.len(), self.buf.capacity()))
.finish()
}
}
impl<W: Write + Seek> Seek for BufWriter<W> {
/// Seek to the offset, in bytes, in the underlying writer.
///
/// Seeking always writes out the internal buffer before seeking.
fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
self.flush_buf()?;
self.get_mut().seek(pos)
}
}
impl<W: Write> Drop for BufWriter<W> {
fn drop(&mut self) {
if self.inner.is_some() && !self.panicked {
// dtors should not panic, so we ignore a failed flush
let _r = self.flush_buf();
}
}
}

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@ -0,0 +1,224 @@
use core::fmt;
use crate::io::{self, buffered::LineWriterShim, BufWriter, IntoInnerError, IoSlice, Write};
/// Wraps a writer and buffers output to it, flushing whenever a newline
/// (`0x0a`, `'\n'`) is detected.
///
/// The [`BufWriter`] struct wraps a writer and buffers its output.
/// But it only does this batched write when it goes out of scope, or when the
/// internal buffer is full. Sometimes, you'd prefer to write each line as it's
/// completed, rather than the entire buffer at once. Enter `LineWriter`. It
/// does exactly that.
///
/// Like [`BufWriter`], a `LineWriter`s buffer will also be flushed when the
/// `LineWriter` goes out of scope or when its internal buffer is full.
///
/// If there's still a partial line in the buffer when the `LineWriter` is
/// dropped, it will flush those contents.
///
/// # Examples
///
/// We can use `LineWriter` to write one line at a time, significantly
/// reducing the number of actual writes to the file.
///
/// ```no_run
/// use std::fs::{self, File};
/// use std::io::prelude::*;
/// use std::io::LineWriter;
///
/// fn main() -> std::io::Result<()> {
/// let road_not_taken = b"I shall be telling this with a sigh
/// Somewhere ages and ages hence:
/// Two roads diverged in a wood, and I -
/// I took the one less traveled by,
/// And that has made all the difference.";
///
/// let file = File::create("poem.txt")?;
/// let mut file = LineWriter::new(file);
///
/// file.write_all(b"I shall be telling this with a sigh")?;
///
/// // No bytes are written until a newline is encountered (or
/// // the internal buffer is filled).
/// assert_eq!(fs::read_to_string("poem.txt")?, "");
/// file.write_all(b"\n")?;
/// assert_eq!(
/// fs::read_to_string("poem.txt")?,
/// "I shall be telling this with a sigh\n",
/// );
///
/// // Write the rest of the poem.
/// file.write_all(b"Somewhere ages and ages hence:
/// Two roads diverged in a wood, and I -
/// I took the one less traveled by,
/// And that has made all the difference.")?;
///
/// // The last line of the poem doesn't end in a newline, so
/// // we have to flush or drop the `LineWriter` to finish
/// // writing.
/// file.flush()?;
///
/// // Confirm the whole poem was written.
/// assert_eq!(fs::read("poem.txt")?, &road_not_taken[..]);
/// Ok(())
/// }
/// ```
pub struct LineWriter<W: Write> {
inner: BufWriter<W>,
}
impl<W: Write> LineWriter<W> {
/// Creates a new `LineWriter`.
///
/// # Examples
///
/// ```no_run
/// use std::fs::File;
/// use std::io::LineWriter;
///
/// fn main() -> std::io::Result<()> {
/// let file = File::create("poem.txt")?;
/// let file = LineWriter::new(file);
/// Ok(())
/// }
/// ```
pub fn new(inner: W) -> LineWriter<W> {
// Lines typically aren't that long, don't use a giant buffer
LineWriter::with_capacity(1024, inner)
}
/// Creates a new `LineWriter` with a specified capacity for the internal
/// buffer.
///
/// # Examples
///
/// ```no_run
/// use std::fs::File;
/// use std::io::LineWriter;
///
/// fn main() -> std::io::Result<()> {
/// let file = File::create("poem.txt")?;
/// let file = LineWriter::with_capacity(100, file);
/// Ok(())
/// }
/// ```
pub fn with_capacity(capacity: usize, inner: W) -> LineWriter<W> {
LineWriter { inner: BufWriter::with_capacity(capacity, inner) }
}
/// Gets a reference to the underlying writer.
///
/// # Examples
///
/// ```no_run
/// use std::fs::File;
/// use std::io::LineWriter;
///
/// fn main() -> std::io::Result<()> {
/// let file = File::create("poem.txt")?;
/// let file = LineWriter::new(file);
///
/// let reference = file.get_ref();
/// Ok(())
/// }
/// ```
pub fn get_ref(&self) -> &W {
self.inner.get_ref()
}
/// Gets a mutable reference to the underlying writer.
///
/// Caution must be taken when calling methods on the mutable reference
/// returned as extra writes could corrupt the output stream.
///
/// # Examples
///
/// ```no_run
/// use std::fs::File;
/// use std::io::LineWriter;
///
/// fn main() -> std::io::Result<()> {
/// let file = File::create("poem.txt")?;
/// let mut file = LineWriter::new(file);
///
/// // we can use reference just like file
/// let reference = file.get_mut();
/// Ok(())
/// }
/// ```
pub fn get_mut(&mut self) -> &mut W {
self.inner.get_mut()
}
/// Unwraps this `LineWriter`, returning the underlying writer.
///
/// The internal buffer is written out before returning the writer.
///
/// # Errors
///
/// An [`Err`] will be returned if an error occurs while flushing the buffer.
///
/// # Examples
///
/// ```no_run
/// use std::fs::File;
/// use std::io::LineWriter;
///
/// fn main() -> std::io::Result<()> {
/// let file = File::create("poem.txt")?;
///
/// let writer: LineWriter<File> = LineWriter::new(file);
///
/// let file: File = writer.into_inner()?;
/// Ok(())
/// }
/// ```
pub fn into_inner(self) -> Result<W, IntoInnerError<LineWriter<W>>> {
self.inner.into_inner().map_err(|err| err.new_wrapped(|inner| LineWriter { inner }))
}
}
impl<W: Write> Write for LineWriter<W> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
LineWriterShim::new(&mut self.inner).write(buf)
}
fn flush(&mut self) -> io::Result<()> {
self.inner.flush()
}
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
LineWriterShim::new(&mut self.inner).write_vectored(bufs)
}
fn is_write_vectored(&self) -> bool {
self.inner.is_write_vectored()
}
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
LineWriterShim::new(&mut self.inner).write_all(buf)
}
fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> io::Result<()> {
LineWriterShim::new(&mut self.inner).write_all_vectored(bufs)
}
fn write_fmt(&mut self, fmt: fmt::Arguments<'_>) -> io::Result<()> {
LineWriterShim::new(&mut self.inner).write_fmt(fmt)
}
}
impl<W: Write> fmt::Debug for LineWriter<W>
where
W: fmt::Debug,
{
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt.debug_struct("LineWriter")
.field("writer", &self.get_ref())
.field(
"buffer",
&format_args!("{}/{}", self.inner.buffer().len(), self.inner.capacity()),
)
.finish()
}
}

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use crate::io::{self, BufWriter, IoSlice, Write};
use crate::io::memchr;
/// Private helper struct for implementing the line-buffered writing logic.
/// This shim temporarily wraps a BufWriter, and uses its internals to
/// implement a line-buffered writer (specifically by using the internal
/// methods like write_to_buf and flush_buf). In this way, a more
/// efficient abstraction can be created than one that only had access to
/// `write` and `flush`, without needlessly duplicating a lot of the
/// implementation details of BufWriter. This also allows existing
/// `BufWriters` to be temporarily given line-buffering logic; this is what
/// enables Stdout to be alternately in line-buffered or block-buffered mode.
#[derive(Debug)]
pub struct LineWriterShim<'a, W: Write> {
buffer: &'a mut BufWriter<W>,
}
impl<'a, W: Write> LineWriterShim<'a, W> {
pub fn new(buffer: &'a mut BufWriter<W>) -> Self {
Self { buffer }
}
/// Get a reference to the inner writer (that is, the writer
/// wrapped by the BufWriter).
fn inner(&self) -> &W {
self.buffer.get_ref()
}
/// Get a mutable reference to the inner writer (that is, the writer
/// wrapped by the BufWriter). Be careful with this writer, as writes to
/// it will bypass the buffer.
fn inner_mut(&mut self) -> &mut W {
self.buffer.get_mut()
}
/// Get the content currently buffered in self.buffer
fn buffered(&self) -> &[u8] {
self.buffer.buffer()
}
/// Flush the buffer iff the last byte is a newline (indicating that an
/// earlier write only succeeded partially, and we want to retry flushing
/// the buffered line before continuing with a subsequent write)
fn flush_if_completed_line(&mut self) -> io::Result<()> {
match self.buffered().last().copied() {
Some(b'\n') => self.buffer.flush_buf(),
_ => Ok(()),
}
}
}
impl<'a, W: Write> Write for LineWriterShim<'a, W> {
/// Write some data into this BufReader with line buffering. This means
/// that, if any newlines are present in the data, the data up to the last
/// newline is sent directly to the underlying writer, and data after it
/// is buffered. Returns the number of bytes written.
///
/// This function operates on a "best effort basis"; in keeping with the
/// convention of `Write::write`, it makes at most one attempt to write
/// new data to the underlying writer. If that write only reports a partial
/// success, the remaining data will be buffered.
///
/// Because this function attempts to send completed lines to the underlying
/// writer, it will also flush the existing buffer if it ends with a
/// newline, even if the incoming data does not contain any newlines.
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
let newline_idx = match memchr::memrchr(b'\n', buf) {
// If there are no new newlines (that is, if this write is less than
// one line), just do a regular buffered write (which may flush if
// we exceed the inner buffer's size)
None => {
self.flush_if_completed_line()?;
return self.buffer.write(buf);
}
// Otherwise, arrange for the lines to be written directly to the
// inner writer.
Some(newline_idx) => newline_idx + 1,
};
// Flush existing content to prepare for our write. We have to do this
// before attempting to write `buf` in order to maintain consistency;
// if we add `buf` to the buffer then try to flush it all at once,
// we're obligated to return Ok(), which would mean suppressing any
// errors that occur during flush.
self.buffer.flush_buf()?;
// This is what we're going to try to write directly to the inner
// writer. The rest will be buffered, if nothing goes wrong.
let lines = &buf[..newline_idx];
// Write `lines` directly to the inner writer. In keeping with the
// `write` convention, make at most one attempt to add new (unbuffered)
// data. Because this write doesn't touch the BufWriter state directly,
// and the buffer is known to be empty, we don't need to worry about
// self.buffer.panicked here.
let flushed = self.inner_mut().write(lines)?;
// If buffer returns Ok(0), propagate that to the caller without
// doing additional buffering; otherwise we're just guaranteeing
// an "ErrorKind::WriteZero" later.
if flushed == 0 {
return Ok(0);
}
// Now that the write has succeeded, buffer the rest (or as much of
// the rest as possible). If there were any unwritten newlines, we
// only buffer out to the last unwritten newline that fits in the
// buffer; this helps prevent flushing partial lines on subsequent
// calls to LineWriterShim::write.
// Handle the cases in order of most-common to least-common, under
// the presumption that most writes succeed in totality, and that most
// writes are smaller than the buffer.
// - Is this a partial line (ie, no newlines left in the unwritten tail)
// - If not, does the data out to the last unwritten newline fit in
// the buffer?
// - If not, scan for the last newline that *does* fit in the buffer
let tail = if flushed >= newline_idx {
&buf[flushed..]
} else if newline_idx - flushed <= self.buffer.capacity() {
&buf[flushed..newline_idx]
} else {
let scan_area = &buf[flushed..];
let scan_area = &scan_area[..self.buffer.capacity()];
match memchr::memrchr(b'\n', scan_area) {
Some(newline_idx) => &scan_area[..newline_idx + 1],
None => scan_area,
}
};
let buffered = self.buffer.write_to_buf(tail);
Ok(flushed + buffered)
}
fn flush(&mut self) -> io::Result<()> {
self.buffer.flush()
}
/// Write some vectored data into this BufReader with line buffering. This
/// means that, if any newlines are present in the data, the data up to
/// and including the buffer containing the last newline is sent directly
/// to the inner writer, and the data after it is buffered. Returns the
/// number of bytes written.
///
/// This function operates on a "best effort basis"; in keeping with the
/// convention of `Write::write`, it makes at most one attempt to write
/// new data to the underlying writer.
///
/// Because this function attempts to send completed lines to the underlying
/// writer, it will also flush the existing buffer if it contains any
/// newlines.
///
/// Because sorting through an array of `IoSlice` can be a bit convoluted,
/// This method differs from write in the following ways:
///
/// - It attempts to write the full content of all the buffers up to and
/// including the one containing the last newline. This means that it
/// may attempt to write a partial line, that buffer has data past the
/// newline.
/// - If the write only reports partial success, it does not attempt to
/// find the precise location of the written bytes and buffer the rest.
///
/// If the underlying vector doesn't support vectored writing, we instead
/// simply write the first non-empty buffer with `write`. This way, we
/// get the benefits of more granular partial-line handling without losing
/// anything in efficiency
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
// If there's no specialized behavior for write_vectored, just use
// write. This has the benefit of more granular partial-line handling.
if !self.is_write_vectored() {
return match bufs.iter().find(|buf| !buf.is_empty()) {
Some(buf) => self.write(buf),
None => Ok(0),
};
}
// Find the buffer containing the last newline
let last_newline_buf_idx = bufs
.iter()
.enumerate()
.rev()
.find_map(|(i, buf)| memchr::memchr(b'\n', buf).map(|_| i));
// If there are no new newlines (that is, if this write is less than
// one line), just do a regular buffered write
let last_newline_buf_idx = match last_newline_buf_idx {
// No newlines; just do a normal buffered write
None => {
self.flush_if_completed_line()?;
return self.buffer.write_vectored(bufs);
}
Some(i) => i,
};
// Flush existing content to prepare for our write
self.buffer.flush_buf()?;
// This is what we're going to try to write directly to the inner
// writer. The rest will be buffered, if nothing goes wrong.
let (lines, tail) = bufs.split_at(last_newline_buf_idx + 1);
// Write `lines` directly to the inner writer. In keeping with the
// `write` convention, make at most one attempt to add new (unbuffered)
// data. Because this write doesn't touch the BufWriter state directly,
// and the buffer is known to be empty, we don't need to worry about
// self.panicked here.
let flushed = self.inner_mut().write_vectored(lines)?;
// If inner returns Ok(0), propagate that to the caller without
// doing additional buffering; otherwise we're just guaranteeing
// an "ErrorKind::WriteZero" later.
if flushed == 0 {
return Ok(0);
}
// Don't try to reconstruct the exact amount written; just bail
// in the event of a partial write
let lines_len = lines.iter().map(|buf| buf.len()).sum();
if flushed < lines_len {
return Ok(flushed);
}
// Now that the write has succeeded, buffer the rest (or as much of the
// rest as possible)
let buffered: usize = tail
.iter()
.filter(|buf| !buf.is_empty())
.map(|buf| self.buffer.write_to_buf(buf))
.take_while(|&n| n > 0)
.sum();
Ok(flushed + buffered)
}
fn is_write_vectored(&self) -> bool {
self.inner().is_write_vectored()
}
/// Write some data into this BufReader with line buffering. This means
/// that, if any newlines are present in the data, the data up to the last
/// newline is sent directly to the underlying writer, and data after it
/// is buffered.
///
/// Because this function attempts to send completed lines to the underlying
/// writer, it will also flush the existing buffer if it contains any
/// newlines, even if the incoming data does not contain any newlines.
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
match memchr::memrchr(b'\n', buf) {
// If there are no new newlines (that is, if this write is less than
// one line), just do a regular buffered write (which may flush if
// we exceed the inner buffer's size)
None => {
self.flush_if_completed_line()?;
self.buffer.write_all(buf)
}
Some(newline_idx) => {
let (lines, tail) = buf.split_at(newline_idx + 1);
if self.buffered().is_empty() {
self.inner_mut().write_all(lines)?;
} else {
// If there is any buffered data, we add the incoming lines
// to that buffer before flushing, which saves us at least
// one write call. We can't really do this with `write`,
// since we can't do this *and* not suppress errors *and*
// report a consistent state to the caller in a return
// value, but here in write_all it's fine.
self.buffer.write_all(lines)?;
self.buffer.flush_buf()?;
}
self.buffer.write_all(tail)
}
}
}
}

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//! Buffering wrappers for I/O traits
mod bufreader;
mod bufwriter;
mod linewriter;
mod linewritershim;
#[cfg(test)]
mod tests;
use core::fmt;
use crate::io::Error;
pub use self::bufreader::BufReader;
pub use self::bufwriter::BufWriter;
pub use self::linewriter::LineWriter;
use self::linewritershim::LineWriterShim;
/// An error returned by [`BufWriter::into_inner`] which combines an error that
/// happened while writing out the buffer, and the buffered writer object
/// which may be used to recover from the condition.
///
/// # Examples
///
/// ```no_run
/// use std::io::BufWriter;
/// use std::net::TcpStream;
///
/// let mut stream = BufWriter::new(TcpStream::connect("127.0.0.1:34254").unwrap());
///
/// // do stuff with the stream
///
/// // we want to get our `TcpStream` back, so let's try:
///
/// let stream = match stream.into_inner() {
/// Ok(s) => s,
/// Err(e) => {
/// // Here, e is an IntoInnerError
/// panic!("An error occurred");
/// }
/// };
/// ```
#[derive(Debug)]
pub struct IntoInnerError<W>(W, Error);
impl<W> IntoInnerError<W> {
/// Construct a new IntoInnerError
fn new(writer: W, error: Error) -> Self {
Self(writer, error)
}
/// Helper to construct a new IntoInnerError; intended to help with
/// adapters that wrap other adapters
fn new_wrapped<W2>(self, f: impl FnOnce(W) -> W2) -> IntoInnerError<W2> {
let Self(writer, error) = self;
IntoInnerError::new(f(writer), error)
}
/// Returns the error which caused the call to [`BufWriter::into_inner()`]
/// to fail.
///
/// This error was returned when attempting to write the internal buffer.
///
/// # Examples
///
/// ```no_run
/// use std::io::BufWriter;
/// use std::net::TcpStream;
///
/// let mut stream = BufWriter::new(TcpStream::connect("127.0.0.1:34254").unwrap());
///
/// // do stuff with the stream
///
/// // we want to get our `TcpStream` back, so let's try:
///
/// let stream = match stream.into_inner() {
/// Ok(s) => s,
/// Err(e) => {
/// // Here, e is an IntoInnerError, let's log the inner error.
/// //
/// // We'll just 'log' to stdout for this example.
/// println!("{}", e.error());
///
/// panic!("An unexpected error occurred.");
/// }
/// };
/// ```
pub fn error(&self) -> &Error {
&self.1
}
/// Returns the buffered writer instance which generated the error.
///
/// The returned object can be used for error recovery, such as
/// re-inspecting the buffer.
///
/// # Examples
///
/// ```no_run
/// use std::io::BufWriter;
/// use std::net::TcpStream;
///
/// let mut stream = BufWriter::new(TcpStream::connect("127.0.0.1:34254").unwrap());
///
/// // do stuff with the stream
///
/// // we want to get our `TcpStream` back, so let's try:
///
/// let stream = match stream.into_inner() {
/// Ok(s) => s,
/// Err(e) => {
/// // Here, e is an IntoInnerError, let's re-examine the buffer:
/// let buffer = e.into_inner();
///
/// // do stuff to try to recover
///
/// // afterwards, let's just return the stream
/// buffer.into_inner().unwrap()
/// }
/// };
/// ```
pub fn into_inner(self) -> W {
self.0
}
/// Consumes the [`IntoInnerError`] and returns the error which caused the call to
/// [`BufWriter::into_inner()`] to fail. Unlike `error`, this can be used to
/// obtain ownership of the underlying error.
///
/// # Example
/// ```
/// #![feature(io_into_inner_error_parts)]
/// use std::io::{BufWriter, ErrorKind, Write};
///
/// let mut not_enough_space = [0u8; 10];
/// let mut stream = BufWriter::new(not_enough_space.as_mut());
/// write!(stream, "this cannot be actually written").unwrap();
/// let into_inner_err = stream.into_inner().expect_err("now we discover it's too small");
/// let err = into_inner_err.into_error();
/// assert_eq!(err.kind(), ErrorKind::WriteZero);
/// ```
pub fn into_error(self) -> Error {
self.1
}
/// Consumes the [`IntoInnerError`] and returns the error which caused the call to
/// [`BufWriter::into_inner()`] to fail, and the underlying writer.
///
/// This can be used to simply obtain ownership of the underlying error; it can also be used for
/// advanced error recovery.
///
/// # Example
/// ```
/// #![feature(io_into_inner_error_parts)]
/// use std::io::{BufWriter, ErrorKind, Write};
///
/// let mut not_enough_space = [0u8; 10];
/// let mut stream = BufWriter::new(not_enough_space.as_mut());
/// write!(stream, "this cannot be actually written").unwrap();
/// let into_inner_err = stream.into_inner().expect_err("now we discover it's too small");
/// let (err, recovered_writer) = into_inner_err.into_parts();
/// assert_eq!(err.kind(), ErrorKind::WriteZero);
/// assert_eq!(recovered_writer.buffer(), b"t be actually written");
/// ```
pub fn into_parts(self) -> (Error, W) {
(self.1, self.0)
}
}
impl<W> From<IntoInnerError<W>> for Error {
fn from(iie: IntoInnerError<W>) -> Error {
iie.1
}
}
impl<W> fmt::Display for IntoInnerError<W> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
self.error().fmt(f)
}
}

View File

@ -0,0 +1,958 @@
use crate::io::prelude::*;
use crate::io::{self, BufReader, BufWriter, ErrorKind, IoSlice, LineWriter, SeekFrom};
use crate::panic;
use crate::sync::atomic::{AtomicUsize, Ordering};
use crate::thread;
/// A dummy reader intended at testing short-reads propagation.
pub struct ShortReader {
lengths: Vec<usize>,
}
// FIXME: rustfmt and tidy disagree about the correct formatting of this
// function. This leads to issues for users with editors configured to
// rustfmt-on-save.
impl Read for ShortReader {
fn read(&mut self, _: &mut [u8]) -> io::Result<usize> {
if self.lengths.is_empty() { Ok(0) } else { Ok(self.lengths.remove(0)) }
}
}
#[test]
fn test_buffered_reader() {
let inner: &[u8] = &[5, 6, 7, 0, 1, 2, 3, 4];
let mut reader = BufReader::with_capacity(2, inner);
let mut buf = [0, 0, 0];
let nread = reader.read(&mut buf);
assert_eq!(nread.unwrap(), 3);
assert_eq!(buf, [5, 6, 7]);
assert_eq!(reader.buffer(), []);
let mut buf = [0, 0];
let nread = reader.read(&mut buf);
assert_eq!(nread.unwrap(), 2);
assert_eq!(buf, [0, 1]);
assert_eq!(reader.buffer(), []);
let mut buf = [0];
let nread = reader.read(&mut buf);
assert_eq!(nread.unwrap(), 1);
assert_eq!(buf, [2]);
assert_eq!(reader.buffer(), [3]);
let mut buf = [0, 0, 0];
let nread = reader.read(&mut buf);
assert_eq!(nread.unwrap(), 1);
assert_eq!(buf, [3, 0, 0]);
assert_eq!(reader.buffer(), []);
let nread = reader.read(&mut buf);
assert_eq!(nread.unwrap(), 1);
assert_eq!(buf, [4, 0, 0]);
assert_eq!(reader.buffer(), []);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_buffered_reader_seek() {
let inner: &[u8] = &[5, 6, 7, 0, 1, 2, 3, 4];
let mut reader = BufReader::with_capacity(2, io::Cursor::new(inner));
assert_eq!(reader.seek(SeekFrom::Start(3)).ok(), Some(3));
assert_eq!(reader.fill_buf().ok(), Some(&[0, 1][..]));
assert_eq!(reader.seek(SeekFrom::Current(0)).ok(), Some(3));
assert_eq!(reader.fill_buf().ok(), Some(&[0, 1][..]));
assert_eq!(reader.seek(SeekFrom::Current(1)).ok(), Some(4));
assert_eq!(reader.fill_buf().ok(), Some(&[1, 2][..]));
reader.consume(1);
assert_eq!(reader.seek(SeekFrom::Current(-2)).ok(), Some(3));
}
#[test]
fn test_buffered_reader_seek_relative() {
let inner: &[u8] = &[5, 6, 7, 0, 1, 2, 3, 4];
let mut reader = BufReader::with_capacity(2, io::Cursor::new(inner));
assert!(reader.seek_relative(3).is_ok());
assert_eq!(reader.fill_buf().ok(), Some(&[0, 1][..]));
assert!(reader.seek_relative(0).is_ok());
assert_eq!(reader.fill_buf().ok(), Some(&[0, 1][..]));
assert!(reader.seek_relative(1).is_ok());
assert_eq!(reader.fill_buf().ok(), Some(&[1][..]));
assert!(reader.seek_relative(-1).is_ok());
assert_eq!(reader.fill_buf().ok(), Some(&[0, 1][..]));
assert!(reader.seek_relative(2).is_ok());
assert_eq!(reader.fill_buf().ok(), Some(&[2, 3][..]));
}
#[test]
fn test_buffered_reader_stream_position() {
let inner: &[u8] = &[5, 6, 7, 0, 1, 2, 3, 4];
let mut reader = BufReader::with_capacity(2, io::Cursor::new(inner));
assert_eq!(reader.stream_position().ok(), Some(0));
assert_eq!(reader.seek(SeekFrom::Start(3)).ok(), Some(3));
assert_eq!(reader.stream_position().ok(), Some(3));
// relative seeking within the buffer and reading position should keep the buffer
assert_eq!(reader.fill_buf().ok(), Some(&[0, 1][..]));
assert!(reader.seek_relative(0).is_ok());
assert_eq!(reader.stream_position().ok(), Some(3));
assert_eq!(reader.buffer(), &[0, 1][..]);
assert!(reader.seek_relative(1).is_ok());
assert_eq!(reader.stream_position().ok(), Some(4));
assert_eq!(reader.buffer(), &[1][..]);
assert!(reader.seek_relative(-1).is_ok());
assert_eq!(reader.stream_position().ok(), Some(3));
assert_eq!(reader.buffer(), &[0, 1][..]);
// relative seeking outside the buffer will discard it
assert!(reader.seek_relative(2).is_ok());
assert_eq!(reader.stream_position().ok(), Some(5));
assert_eq!(reader.buffer(), &[][..]);
}
#[test]
fn test_buffered_reader_stream_position_panic() {
let inner: &[u8] = &[5, 6, 7, 0, 1, 2, 3, 4];
let mut reader = BufReader::with_capacity(4, io::Cursor::new(inner));
// cause internal buffer to be filled but read only partially
let mut buffer = [0, 0];
assert!(reader.read_exact(&mut buffer).is_ok());
// rewinding the internal reader will cause buffer to loose sync
let inner = reader.get_mut();
assert!(inner.seek(SeekFrom::Start(0)).is_ok());
// overflow when subtracting the remaining buffer size from current position
let result = panic::catch_unwind(panic::AssertUnwindSafe(|| reader.stream_position().ok()));
assert!(result.is_err());
}
#[test]
fn test_buffered_reader_invalidated_after_read() {
let inner: &[u8] = &[5, 6, 7, 0, 1, 2, 3, 4];
let mut reader = BufReader::with_capacity(3, io::Cursor::new(inner));
assert_eq!(reader.fill_buf().ok(), Some(&[5, 6, 7][..]));
reader.consume(3);
let mut buffer = [0, 0, 0, 0, 0];
assert_eq!(reader.read(&mut buffer).ok(), Some(5));
assert_eq!(buffer, [0, 1, 2, 3, 4]);
assert!(reader.seek_relative(-2).is_ok());
let mut buffer = [0, 0];
assert_eq!(reader.read(&mut buffer).ok(), Some(2));
assert_eq!(buffer, [3, 4]);
}
#[test]
fn test_buffered_reader_invalidated_after_seek() {
let inner: &[u8] = &[5, 6, 7, 0, 1, 2, 3, 4];
let mut reader = BufReader::with_capacity(3, io::Cursor::new(inner));
assert_eq!(reader.fill_buf().ok(), Some(&[5, 6, 7][..]));
reader.consume(3);
assert!(reader.seek(SeekFrom::Current(5)).is_ok());
assert!(reader.seek_relative(-2).is_ok());
let mut buffer = [0, 0];
assert_eq!(reader.read(&mut buffer).ok(), Some(2));
assert_eq!(buffer, [3, 4]);
}
#[test]
fn test_buffered_reader_seek_underflow() {
// gimmick reader that yields its position modulo 256 for each byte
struct PositionReader {
pos: u64,
}
impl Read for PositionReader {
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
let len = buf.len();
for x in buf {
*x = self.pos as u8;
self.pos = self.pos.wrapping_add(1);
}
Ok(len)
}
}
impl Seek for PositionReader {
fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
match pos {
SeekFrom::Start(n) => {
self.pos = n;
}
SeekFrom::Current(n) => {
self.pos = self.pos.wrapping_add(n as u64);
}
SeekFrom::End(n) => {
self.pos = u64::MAX.wrapping_add(n as u64);
}
}
Ok(self.pos)
}
}
let mut reader = BufReader::with_capacity(5, PositionReader { pos: 0 });
assert_eq!(reader.fill_buf().ok(), Some(&[0, 1, 2, 3, 4][..]));
assert_eq!(reader.seek(SeekFrom::End(-5)).ok(), Some(u64::MAX - 5));
assert_eq!(reader.fill_buf().ok().map(|s| s.len()), Some(5));
// the following seek will require two underlying seeks
let expected = 9223372036854775802;
assert_eq!(reader.seek(SeekFrom::Current(i64::MIN)).ok(), Some(expected));
assert_eq!(reader.fill_buf().ok().map(|s| s.len()), Some(5));
// seeking to 0 should empty the buffer.
assert_eq!(reader.seek(SeekFrom::Current(0)).ok(), Some(expected));
assert_eq!(reader.get_ref().pos, expected);
}
#[test]
fn test_buffered_reader_seek_underflow_discard_buffer_between_seeks() {
// gimmick reader that returns Err after first seek
struct ErrAfterFirstSeekReader {
first_seek: bool,
}
impl Read for ErrAfterFirstSeekReader {
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
for x in &mut *buf {
*x = 0;
}
Ok(buf.len())
}
}
impl Seek for ErrAfterFirstSeekReader {
fn seek(&mut self, _: SeekFrom) -> io::Result<u64> {
if self.first_seek {
self.first_seek = false;
Ok(0)
} else {
Err(io::Error::new(io::ErrorKind::Other, "oh no!"))
}
}
}
let mut reader = BufReader::with_capacity(5, ErrAfterFirstSeekReader { first_seek: true });
assert_eq!(reader.fill_buf().ok(), Some(&[0, 0, 0, 0, 0][..]));
// The following seek will require two underlying seeks. The first will
// succeed but the second will fail. This should still invalidate the
// buffer.
assert!(reader.seek(SeekFrom::Current(i64::MIN)).is_err());
assert_eq!(reader.buffer().len(), 0);
}
#[test]
fn test_buffered_writer() {
let inner = Vec::new();
let mut writer = BufWriter::with_capacity(2, inner);
writer.write(&[0, 1]).unwrap();
assert_eq!(writer.buffer(), []);
assert_eq!(*writer.get_ref(), [0, 1]);
writer.write(&[2]).unwrap();
assert_eq!(writer.buffer(), [2]);
assert_eq!(*writer.get_ref(), [0, 1]);
writer.write(&[3]).unwrap();
assert_eq!(writer.buffer(), [2, 3]);
assert_eq!(*writer.get_ref(), [0, 1]);
writer.flush().unwrap();
assert_eq!(writer.buffer(), []);
assert_eq!(*writer.get_ref(), [0, 1, 2, 3]);
writer.write(&[4]).unwrap();
writer.write(&[5]).unwrap();
assert_eq!(writer.buffer(), [4, 5]);
assert_eq!(*writer.get_ref(), [0, 1, 2, 3]);
writer.write(&[6]).unwrap();
assert_eq!(writer.buffer(), [6]);
assert_eq!(*writer.get_ref(), [0, 1, 2, 3, 4, 5]);
writer.write(&[7, 8]).unwrap();
assert_eq!(writer.buffer(), []);
assert_eq!(*writer.get_ref(), [0, 1, 2, 3, 4, 5, 6, 7, 8]);
writer.write(&[9, 10, 11]).unwrap();
assert_eq!(writer.buffer(), []);
assert_eq!(*writer.get_ref(), [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]);
writer.flush().unwrap();
assert_eq!(writer.buffer(), []);
assert_eq!(*writer.get_ref(), [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]);
}
#[test]
fn test_buffered_writer_inner_flushes() {
let mut w = BufWriter::with_capacity(3, Vec::new());
w.write(&[0, 1]).unwrap();
assert_eq!(*w.get_ref(), []);
let w = w.into_inner().unwrap();
assert_eq!(w, [0, 1]);
}
#[test]
fn test_buffered_writer_seek() {
let mut w = BufWriter::with_capacity(3, io::Cursor::new(Vec::new()));
w.write_all(&[0, 1, 2, 3, 4, 5]).unwrap();
w.write_all(&[6, 7]).unwrap();
assert_eq!(w.seek(SeekFrom::Current(0)).ok(), Some(8));
assert_eq!(&w.get_ref().get_ref()[..], &[0, 1, 2, 3, 4, 5, 6, 7][..]);
assert_eq!(w.seek(SeekFrom::Start(2)).ok(), Some(2));
w.write_all(&[8, 9]).unwrap();
assert_eq!(&w.into_inner().unwrap().into_inner()[..], &[0, 1, 8, 9, 4, 5, 6, 7]);
}
#[test]
fn test_read_until() {
let inner: &[u8] = &[0, 1, 2, 1, 0];
let mut reader = BufReader::with_capacity(2, inner);
let mut v = Vec::new();
reader.read_until(0, &mut v).unwrap();
assert_eq!(v, [0]);
v.truncate(0);
reader.read_until(2, &mut v).unwrap();
assert_eq!(v, [1, 2]);
v.truncate(0);
reader.read_until(1, &mut v).unwrap();
assert_eq!(v, [1]);
v.truncate(0);
reader.read_until(8, &mut v).unwrap();
assert_eq!(v, [0]);
v.truncate(0);
reader.read_until(9, &mut v).unwrap();
assert_eq!(v, []);
}
#[test]
fn test_line_buffer() {
let mut writer = LineWriter::new(Vec::new());
writer.write(&[0]).unwrap();
assert_eq!(*writer.get_ref(), []);
writer.write(&[1]).unwrap();
assert_eq!(*writer.get_ref(), []);
writer.flush().unwrap();
assert_eq!(*writer.get_ref(), [0, 1]);
writer.write(&[0, b'\n', 1, b'\n', 2]).unwrap();
assert_eq!(*writer.get_ref(), [0, 1, 0, b'\n', 1, b'\n']);
writer.flush().unwrap();
assert_eq!(*writer.get_ref(), [0, 1, 0, b'\n', 1, b'\n', 2]);
writer.write(&[3, b'\n']).unwrap();
assert_eq!(*writer.get_ref(), [0, 1, 0, b'\n', 1, b'\n', 2, 3, b'\n']);
}
#[test]
fn test_read_line() {
let in_buf: &[u8] = b"a\nb\nc";
let mut reader = BufReader::with_capacity(2, in_buf);
let mut s = String::new();
reader.read_line(&mut s).unwrap();
assert_eq!(s, "a\n");
s.truncate(0);
reader.read_line(&mut s).unwrap();
assert_eq!(s, "b\n");
s.truncate(0);
reader.read_line(&mut s).unwrap();
assert_eq!(s, "c");
s.truncate(0);
reader.read_line(&mut s).unwrap();
assert_eq!(s, "");
}
#[test]
fn test_lines() {
let in_buf: &[u8] = b"a\nb\nc";
let reader = BufReader::with_capacity(2, in_buf);
let mut it = reader.lines();
assert_eq!(it.next().unwrap().unwrap(), "a".to_string());
assert_eq!(it.next().unwrap().unwrap(), "b".to_string());
assert_eq!(it.next().unwrap().unwrap(), "c".to_string());
assert!(it.next().is_none());
}
#[test]
fn test_short_reads() {
let inner = ShortReader { lengths: vec![0, 1, 2, 0, 1, 0] };
let mut reader = BufReader::new(inner);
let mut buf = [0, 0];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.read(&mut buf).unwrap(), 2);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
#[should_panic]
fn dont_panic_in_drop_on_panicked_flush() {
struct FailFlushWriter;
impl Write for FailFlushWriter {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
Ok(buf.len())
}
fn flush(&mut self) -> io::Result<()> {
Err(io::Error::last_os_error())
}
}
let writer = FailFlushWriter;
let _writer = BufWriter::new(writer);
// If writer panics *again* due to the flush error then the process will
// abort.
panic!();
}
#[test]
#[cfg_attr(target_os = "emscripten", ignore)]
fn panic_in_write_doesnt_flush_in_drop() {
static WRITES: AtomicUsize = AtomicUsize::new(0);
struct PanicWriter;
impl Write for PanicWriter {
fn write(&mut self, _: &[u8]) -> io::Result<usize> {
WRITES.fetch_add(1, Ordering::SeqCst);
panic!();
}
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
thread::spawn(|| {
let mut writer = BufWriter::new(PanicWriter);
let _ = writer.write(b"hello world");
let _ = writer.flush();
})
.join()
.unwrap_err();
assert_eq!(WRITES.load(Ordering::SeqCst), 1);
}
#[bench]
fn bench_buffered_reader(b: &mut test::Bencher) {
b.iter(|| BufReader::new(io::empty()));
}
#[bench]
fn bench_buffered_writer(b: &mut test::Bencher) {
b.iter(|| BufWriter::new(io::sink()));
}
/// A simple `Write` target, designed to be wrapped by `LineWriter` /
/// `BufWriter` / etc, that can have its `write` & `flush` behavior
/// configured
#[derive(Default, Clone)]
struct ProgrammableSink {
// Writes append to this slice
pub buffer: Vec<u8>,
// Flush sets this flag
pub flushed: bool,
// If true, writes will always be an error
pub always_write_error: bool,
// If true, flushes will always be an error
pub always_flush_error: bool,
// If set, only up to this number of bytes will be written in a single
// call to `write`
pub accept_prefix: Option<usize>,
// If set, counts down with each write, and writes return an error
// when it hits 0
pub max_writes: Option<usize>,
// If set, attempting to write when max_writes == Some(0) will be an
// error; otherwise, it will return Ok(0).
pub error_after_max_writes: bool,
}
impl Write for ProgrammableSink {
fn write(&mut self, data: &[u8]) -> io::Result<usize> {
if self.always_write_error {
return Err(io::Error::new(io::ErrorKind::Other, "test - always_write_error"));
}
match self.max_writes {
Some(0) if self.error_after_max_writes => {
return Err(io::Error::new(io::ErrorKind::Other, "test - max_writes"));
}
Some(0) => return Ok(0),
Some(ref mut count) => *count -= 1,
None => {}
}
let len = match self.accept_prefix {
None => data.len(),
Some(prefix) => data.len().min(prefix),
};
let data = &data[..len];
self.buffer.extend_from_slice(data);
Ok(len)
}
fn flush(&mut self) -> io::Result<()> {
if self.always_flush_error {
Err(io::Error::new(io::ErrorKind::Other, "test - always_flush_error"))
} else {
self.flushed = true;
Ok(())
}
}
}
/// Previously the `LineWriter` could successfully write some bytes but
/// then fail to report that it has done so. Additionally, an erroneous
/// flush after a successful write was permanently ignored.
///
/// Test that a line writer correctly reports the number of written bytes,
/// and that it attempts to flush buffered lines from previous writes
/// before processing new data
///
/// Regression test for #37807
#[test]
fn erroneous_flush_retried() {
let writer = ProgrammableSink {
// Only write up to 4 bytes at a time
accept_prefix: Some(4),
// Accept the first two writes, then error the others
max_writes: Some(2),
error_after_max_writes: true,
..Default::default()
};
// This should write the first 4 bytes. The rest will be buffered, out
// to the last newline.
let mut writer = LineWriter::new(writer);
assert_eq!(writer.write(b"a\nb\nc\nd\ne").unwrap(), 8);
// This write should attempt to flush "c\nd\n", then buffer "e". No
// errors should happen here because no further writes should be
// attempted against `writer`.
assert_eq!(writer.write(b"e").unwrap(), 1);
assert_eq!(&writer.get_ref().buffer, b"a\nb\nc\nd\n");
}
#[test]
fn line_vectored() {
let mut a = LineWriter::new(Vec::new());
assert_eq!(
a.write_vectored(&[
IoSlice::new(&[]),
IoSlice::new(b"\n"),
IoSlice::new(&[]),
IoSlice::new(b"a"),
])
.unwrap(),
2,
);
assert_eq!(a.get_ref(), b"\n");
assert_eq!(
a.write_vectored(&[
IoSlice::new(&[]),
IoSlice::new(b"b"),
IoSlice::new(&[]),
IoSlice::new(b"a"),
IoSlice::new(&[]),
IoSlice::new(b"c"),
])
.unwrap(),
3,
);
assert_eq!(a.get_ref(), b"\n");
a.flush().unwrap();
assert_eq!(a.get_ref(), b"\nabac");
assert_eq!(a.write_vectored(&[]).unwrap(), 0);
assert_eq!(
a.write_vectored(&[
IoSlice::new(&[]),
IoSlice::new(&[]),
IoSlice::new(&[]),
IoSlice::new(&[]),
])
.unwrap(),
0,
);
assert_eq!(a.write_vectored(&[IoSlice::new(b"a\nb"),]).unwrap(), 3);
assert_eq!(a.get_ref(), b"\nabaca\nb");
}
#[test]
fn line_vectored_partial_and_errors() {
use crate::collections::VecDeque;
enum Call {
Write { inputs: Vec<&'static [u8]>, output: io::Result<usize> },
Flush { output: io::Result<()> },
}
#[derive(Default)]
struct Writer {
calls: VecDeque<Call>,
}
impl Write for Writer {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
self.write_vectored(&[IoSlice::new(buf)])
}
fn write_vectored(&mut self, buf: &[IoSlice<'_>]) -> io::Result<usize> {
match self.calls.pop_front().expect("unexpected call to write") {
Call::Write { inputs, output } => {
assert_eq!(inputs, buf.iter().map(|b| &**b).collect::<Vec<_>>());
output
}
Call::Flush { .. } => panic!("unexpected call to write; expected a flush"),
}
}
fn is_write_vectored(&self) -> bool {
true
}
fn flush(&mut self) -> io::Result<()> {
match self.calls.pop_front().expect("Unexpected call to flush") {
Call::Flush { output } => output,
Call::Write { .. } => panic!("unexpected call to flush; expected a write"),
}
}
}
impl Drop for Writer {
fn drop(&mut self) {
if !thread::panicking() {
assert_eq!(self.calls.len(), 0);
}
}
}
// partial writes keep going
let mut a = LineWriter::new(Writer::default());
a.write_vectored(&[IoSlice::new(&[]), IoSlice::new(b"abc")]).unwrap();
a.get_mut().calls.push_back(Call::Write { inputs: vec![b"abc"], output: Ok(1) });
a.get_mut().calls.push_back(Call::Write { inputs: vec![b"bc"], output: Ok(2) });
a.get_mut().calls.push_back(Call::Write { inputs: vec![b"x", b"\n"], output: Ok(2) });
a.write_vectored(&[IoSlice::new(b"x"), IoSlice::new(b"\n")]).unwrap();
a.get_mut().calls.push_back(Call::Flush { output: Ok(()) });
a.flush().unwrap();
// erroneous writes stop and don't write more
a.get_mut().calls.push_back(Call::Write { inputs: vec![b"x", b"\na"], output: Err(err()) });
a.get_mut().calls.push_back(Call::Flush { output: Ok(()) });
assert!(a.write_vectored(&[IoSlice::new(b"x"), IoSlice::new(b"\na")]).is_err());
a.flush().unwrap();
fn err() -> io::Error {
io::Error::new(io::ErrorKind::Other, "x")
}
}
/// Test that, in cases where vectored writing is not enabled, the
/// LineWriter uses the normal `write` call, which more-correctly handles
/// partial lines
#[test]
fn line_vectored_ignored() {
let writer = ProgrammableSink::default();
let mut writer = LineWriter::new(writer);
let content = [
IoSlice::new(&[]),
IoSlice::new(b"Line 1\nLine"),
IoSlice::new(b" 2\nLine 3\nL"),
IoSlice::new(&[]),
IoSlice::new(&[]),
IoSlice::new(b"ine 4"),
IoSlice::new(b"\nLine 5\n"),
];
let count = writer.write_vectored(&content).unwrap();
assert_eq!(count, 11);
assert_eq!(&writer.get_ref().buffer, b"Line 1\n");
let count = writer.write_vectored(&content[2..]).unwrap();
assert_eq!(count, 11);
assert_eq!(&writer.get_ref().buffer, b"Line 1\nLine 2\nLine 3\n");
let count = writer.write_vectored(&content[5..]).unwrap();
assert_eq!(count, 5);
assert_eq!(&writer.get_ref().buffer, b"Line 1\nLine 2\nLine 3\n");
let count = writer.write_vectored(&content[6..]).unwrap();
assert_eq!(count, 8);
assert_eq!(
writer.get_ref().buffer.as_slice(),
b"Line 1\nLine 2\nLine 3\nLine 4\nLine 5\n".as_ref()
);
}
/// Test that, given this input:
///
/// Line 1\n
/// Line 2\n
/// Line 3\n
/// Line 4
///
/// And given a result that only writes to midway through Line 2
///
/// That only up to the end of Line 3 is buffered
///
/// This behavior is desirable because it prevents flushing partial lines
#[test]
fn partial_write_buffers_line() {
let writer = ProgrammableSink { accept_prefix: Some(13), ..Default::default() };
let mut writer = LineWriter::new(writer);
assert_eq!(writer.write(b"Line 1\nLine 2\nLine 3\nLine4").unwrap(), 21);
assert_eq!(&writer.get_ref().buffer, b"Line 1\nLine 2");
assert_eq!(writer.write(b"Line 4").unwrap(), 6);
assert_eq!(&writer.get_ref().buffer, b"Line 1\nLine 2\nLine 3\n");
}
/// Test that, given this input:
///
/// Line 1\n
/// Line 2\n
/// Line 3
///
/// And given that the full write of lines 1 and 2 was successful
/// That data up to Line 3 is buffered
#[test]
fn partial_line_buffered_after_line_write() {
let writer = ProgrammableSink::default();
let mut writer = LineWriter::new(writer);
assert_eq!(writer.write(b"Line 1\nLine 2\nLine 3").unwrap(), 20);
assert_eq!(&writer.get_ref().buffer, b"Line 1\nLine 2\n");
assert!(writer.flush().is_ok());
assert_eq!(&writer.get_ref().buffer, b"Line 1\nLine 2\nLine 3");
}
/// Test that, given a partial line that exceeds the length of
/// LineBuffer's buffer (that is, without a trailing newline), that that
/// line is written to the inner writer
#[test]
fn long_line_flushed() {
let writer = ProgrammableSink::default();
let mut writer = LineWriter::with_capacity(5, writer);
assert_eq!(writer.write(b"0123456789").unwrap(), 10);
assert_eq!(&writer.get_ref().buffer, b"0123456789");
}
/// Test that, given a very long partial line *after* successfully
/// flushing a complete line, that that line is buffered unconditionally,
/// and no additional writes take place. This assures the property that
/// `write` should make at-most-one attempt to write new data.
#[test]
fn line_long_tail_not_flushed() {
let writer = ProgrammableSink::default();
let mut writer = LineWriter::with_capacity(5, writer);
// Assert that Line 1\n is flushed, and 01234 is buffered
assert_eq!(writer.write(b"Line 1\n0123456789").unwrap(), 12);
assert_eq!(&writer.get_ref().buffer, b"Line 1\n");
// Because the buffer is full, this subsequent write will flush it
assert_eq!(writer.write(b"5").unwrap(), 1);
assert_eq!(&writer.get_ref().buffer, b"Line 1\n01234");
}
/// Test that, if an attempt to pre-flush buffered data returns Ok(0),
/// this is propagated as an error.
#[test]
fn line_buffer_write0_error() {
let writer = ProgrammableSink {
// Accept one write, then return Ok(0) on subsequent ones
max_writes: Some(1),
..Default::default()
};
let mut writer = LineWriter::new(writer);
// This should write "Line 1\n" and buffer "Partial"
assert_eq!(writer.write(b"Line 1\nPartial").unwrap(), 14);
assert_eq!(&writer.get_ref().buffer, b"Line 1\n");
// This will attempt to flush "partial", which will return Ok(0), which
// needs to be an error, because we've already informed the client
// that we accepted the write.
let err = writer.write(b" Line End\n").unwrap_err();
assert_eq!(err.kind(), ErrorKind::WriteZero);
assert_eq!(&writer.get_ref().buffer, b"Line 1\n");
}
/// Test that, if a write returns Ok(0) after a successful pre-flush, this
/// is propagated as Ok(0)
#[test]
fn line_buffer_write0_normal() {
let writer = ProgrammableSink {
// Accept two writes, then return Ok(0) on subsequent ones
max_writes: Some(2),
..Default::default()
};
let mut writer = LineWriter::new(writer);
// This should write "Line 1\n" and buffer "Partial"
assert_eq!(writer.write(b"Line 1\nPartial").unwrap(), 14);
assert_eq!(&writer.get_ref().buffer, b"Line 1\n");
// This will flush partial, which will succeed, but then return Ok(0)
// when flushing " Line End\n"
assert_eq!(writer.write(b" Line End\n").unwrap(), 0);
assert_eq!(&writer.get_ref().buffer, b"Line 1\nPartial");
}
/// LineWriter has a custom `write_all`; make sure it works correctly
#[test]
fn line_write_all() {
let writer = ProgrammableSink {
// Only write 5 bytes at a time
accept_prefix: Some(5),
..Default::default()
};
let mut writer = LineWriter::new(writer);
writer.write_all(b"Line 1\nLine 2\nLine 3\nLine 4\nPartial").unwrap();
assert_eq!(&writer.get_ref().buffer, b"Line 1\nLine 2\nLine 3\nLine 4\n");
writer.write_all(b" Line 5\n").unwrap();
assert_eq!(
writer.get_ref().buffer.as_slice(),
b"Line 1\nLine 2\nLine 3\nLine 4\nPartial Line 5\n".as_ref(),
);
}
#[test]
fn line_write_all_error() {
let writer = ProgrammableSink {
// Only accept up to 3 writes of up to 5 bytes each
accept_prefix: Some(5),
max_writes: Some(3),
..Default::default()
};
let mut writer = LineWriter::new(writer);
let res = writer.write_all(b"Line 1\nLine 2\nLine 3\nLine 4\nPartial");
assert!(res.is_err());
// An error from write_all leaves everything in an indeterminate state,
// so there's nothing else to test here
}
/// Under certain circumstances, the old implementation of LineWriter
/// would try to buffer "to the last newline" but be forced to buffer
/// less than that, leading to inappropriate partial line writes.
/// Regression test for that issue.
#[test]
fn partial_multiline_buffering() {
let writer = ProgrammableSink {
// Write only up to 5 bytes at a time
accept_prefix: Some(5),
..Default::default()
};
let mut writer = LineWriter::with_capacity(10, writer);
let content = b"AAAAABBBBB\nCCCCDDDDDD\nEEE";
// When content is written, LineWriter will try to write blocks A, B,
// C, and D. Only block A will succeed. Under the old behavior, LineWriter
// would then try to buffer B, C and D, but because its capacity is 10,
// it will only be able to buffer B and C. We don't want to buffer
// partial lines concurrent with whole lines, so the correct behavior
// is to buffer only block B (out to the newline)
assert_eq!(writer.write(content).unwrap(), 11);
assert_eq!(writer.get_ref().buffer, *b"AAAAA");
writer.flush().unwrap();
assert_eq!(writer.get_ref().buffer, *b"AAAAABBBBB\n");
}
/// Same as test_partial_multiline_buffering, but in the event NO full lines
/// fit in the buffer, just buffer as much as possible
#[test]
fn partial_multiline_buffering_without_full_line() {
let writer = ProgrammableSink {
// Write only up to 5 bytes at a time
accept_prefix: Some(5),
..Default::default()
};
let mut writer = LineWriter::with_capacity(5, writer);
let content = b"AAAAABBBBBBBBBB\nCCCCC\nDDDDD";
// When content is written, LineWriter will try to write blocks A, B,
// and C. Only block A will succeed. Under the old behavior, LineWriter
// would then try to buffer B and C, but because its capacity is 5,
// it will only be able to buffer part of B. Because it's not possible
// for it to buffer any complete lines, it should buffer as much of B as
// possible
assert_eq!(writer.write(content).unwrap(), 10);
assert_eq!(writer.get_ref().buffer, *b"AAAAA");
writer.flush().unwrap();
assert_eq!(writer.get_ref().buffer, *b"AAAAABBBBB");
}
#[derive(Debug, Clone, PartialEq, Eq)]
enum RecordedEvent {
Write(String),
Flush,
}
#[derive(Debug, Clone, Default)]
struct WriteRecorder {
pub events: Vec<RecordedEvent>,
}
impl Write for WriteRecorder {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
use crate::str::from_utf8;
self.events.push(RecordedEvent::Write(from_utf8(buf).unwrap().to_string()));
Ok(buf.len())
}
fn flush(&mut self) -> io::Result<()> {
self.events.push(RecordedEvent::Flush);
Ok(())
}
}
/// Test that a normal, formatted writeln only results in a single write
/// call to the underlying writer. A naive implementation of
/// LineWriter::write_all results in two writes: one of the buffered data,
/// and another of the final substring in the formatted set
#[test]
fn single_formatted_write() {
let writer = WriteRecorder::default();
let mut writer = LineWriter::new(writer);
// Under a naive implementation of LineWriter, this will result in two
// writes: "hello, world" and "!\n", because write() has to flush the
// buffer before attempting to write the last "!\n". write_all shouldn't
// have this limitation.
writeln!(&mut writer, "{}, {}!", "hello", "world").unwrap();
assert_eq!(writer.get_ref().events, [RecordedEvent::Write("hello, world!\n".to_string())]);
}

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@ -0,0 +1,81 @@
use crate::io::{self, ErrorKind, Read, Write};
use core::mem::MaybeUninit;
/// Copies the entire contents of a reader into a writer.
///
/// This function will continuously read data from `reader` and then
/// write it into `writer` in a streaming fashion until `reader`
/// returns EOF.
///
/// On success, the total number of bytes that were copied from
/// `reader` to `writer` is returned.
///
/// If youre wanting to copy the contents of one file to another and youre
/// working with filesystem paths, see the [`fs::copy`] function.
///
/// [`fs::copy`]: crate::fs::copy
///
/// # Errors
///
/// This function will return an error immediately if any call to [`read`] or
/// [`write`] returns an error. All instances of [`ErrorKind::Interrupted`] are
/// handled by this function and the underlying operation is retried.
///
/// [`read`]: Read::read
/// [`write`]: Write::write
///
/// # Examples
///
/// ```
/// use std::io;
///
/// fn main() -> io::Result<()> {
/// let mut reader: &[u8] = b"hello";
/// let mut writer: Vec<u8> = vec![];
///
/// io::copy(&mut reader, &mut writer)?;
///
/// assert_eq!(&b"hello"[..], &writer[..]);
/// Ok(())
/// }
/// ```
pub fn copy<R: ?Sized, W: ?Sized>(reader: &mut R, writer: &mut W) -> io::Result<u64>
where
R: Read,
W: Write,
{
generic_copy(reader, writer)
}
/// The general read-write-loop implementation of
/// `io::copy` that is used when specializations are not available or not applicable.
pub(crate) fn generic_copy<R: ?Sized, W: ?Sized>(reader: &mut R, writer: &mut W) -> io::Result<u64>
where
R: Read,
W: Write,
{
let mut buf = MaybeUninit::<[u8; super::DEFAULT_BUF_SIZE]>::uninit();
// FIXME: #42788
//
// - This creates a (mut) reference to a slice of
// _uninitialized_ integers, which is **undefined behavior**
//
// - Only the standard library gets to soundly "ignore" this,
// based on its privileged knowledge of unstable rustc
// internals;
unsafe {
reader.initializer().initialize(buf.assume_init_mut());
}
let mut written = 0;
loop {
let len = match reader.read(unsafe { buf.assume_init_mut() }) {
Ok(0) => return Ok(written),
Ok(len) => len,
Err(ref e) if e.kind() == ErrorKind::Interrupted => continue,
Err(e) => return Err(e),
};
writer.write_all(unsafe { &buf.assume_init_ref()[..len] })?;
written += len as u64;
}
}

View File

@ -0,0 +1,453 @@
#[cfg(test)]
mod tests;
use crate::io::prelude::*;
use core::cmp;
use crate::io::{self, Error, ErrorKind, Initializer, IoSlice, IoSliceMut, SeekFrom};
#[cfg(feature="collections")] use core::convert::TryInto;
/// A `Cursor` wraps an in-memory buffer and provides it with a
/// [`Seek`] implementation.
///
/// `Cursor`s are used with in-memory buffers, anything implementing
/// [`AsRef`]`<[u8]>`, to allow them to implement [`Read`] and/or [`Write`],
/// allowing these buffers to be used anywhere you might use a reader or writer
/// that does actual I/O.
///
/// The standard library implements some I/O traits on various types which
/// are commonly used as a buffer, like `Cursor<`[`Vec`]`<u8>>` and
/// `Cursor<`[`&[u8]`][bytes]`>`.
///
/// # Examples
///
/// We may want to write bytes to a [`File`] in our production
/// code, but use an in-memory buffer in our tests. We can do this with
/// `Cursor`:
///
/// [bytes]: crate::slice
/// [`File`]: crate::fs::File
///
/// ```no_run
/// use std::io::prelude::*;
/// use std::io::{self, SeekFrom};
/// use std::fs::File;
///
/// // a library function we've written
/// fn write_ten_bytes_at_end<W: Write + Seek>(writer: &mut W) -> io::Result<()> {
/// writer.seek(SeekFrom::End(-10))?;
///
/// for i in 0..10 {
/// writer.write(&[i])?;
/// }
///
/// // all went well
/// Ok(())
/// }
///
/// # fn foo() -> io::Result<()> {
/// // Here's some code that uses this library function.
/// //
/// // We might want to use a BufReader here for efficiency, but let's
/// // keep this example focused.
/// let mut file = File::create("foo.txt")?;
///
/// write_ten_bytes_at_end(&mut file)?;
/// # Ok(())
/// # }
///
/// // now let's write a test
/// #[test]
/// fn test_writes_bytes() {
/// // setting up a real File is much slower than an in-memory buffer,
/// // let's use a cursor instead
/// use std::io::Cursor;
/// let mut buff = Cursor::new(vec![0; 15]);
///
/// write_ten_bytes_at_end(&mut buff).unwrap();
///
/// assert_eq!(&buff.get_ref()[5..15], &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
/// }
/// ```
#[derive(Clone, Debug, Default, Eq, PartialEq)]
pub struct Cursor<T> {
inner: T,
pos: u64,
}
impl<T> Cursor<T> {
/// Creates a new cursor wrapping the provided underlying in-memory buffer.
///
/// Cursor initial position is `0` even if underlying buffer (e.g., [`Vec`])
/// is not empty. So writing to cursor starts with overwriting [`Vec`]
/// content, not with appending to it.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
/// ```
pub const fn new(inner: T) -> Cursor<T> {
Cursor { pos: 0, inner }
}
/// Consumes this cursor, returning the underlying value.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
///
/// let vec = buff.into_inner();
/// ```
pub fn into_inner(self) -> T {
self.inner
}
/// Gets a reference to the underlying value in this cursor.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
///
/// let reference = buff.get_ref();
/// ```
pub const fn get_ref(&self) -> &T {
&self.inner
}
/// Gets a mutable reference to the underlying value in this cursor.
///
/// Care should be taken to avoid modifying the internal I/O state of the
/// underlying value as it may corrupt this cursor's position.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let mut buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
///
/// let reference = buff.get_mut();
/// ```
pub fn get_mut(&mut self) -> &mut T {
&mut self.inner
}
/// Returns the current position of this cursor.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
/// use std::io::prelude::*;
/// use std::io::SeekFrom;
///
/// let mut buff = Cursor::new(vec![1, 2, 3, 4, 5]);
///
/// assert_eq!(buff.position(), 0);
///
/// buff.seek(SeekFrom::Current(2)).unwrap();
/// assert_eq!(buff.position(), 2);
///
/// buff.seek(SeekFrom::Current(-1)).unwrap();
/// assert_eq!(buff.position(), 1);
/// ```
pub const fn position(&self) -> u64 {
self.pos
}
/// Sets the position of this cursor.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let mut buff = Cursor::new(vec![1, 2, 3, 4, 5]);
///
/// assert_eq!(buff.position(), 0);
///
/// buff.set_position(2);
/// assert_eq!(buff.position(), 2);
///
/// buff.set_position(4);
/// assert_eq!(buff.position(), 4);
/// ```
pub fn set_position(&mut self, pos: u64) {
self.pos = pos;
}
}
impl<T> io::Seek for Cursor<T>
where
T: AsRef<[u8]>,
{
fn seek(&mut self, style: SeekFrom) -> io::Result<u64> {
let (base_pos, offset) = match style {
SeekFrom::Start(n) => {
self.pos = n;
return Ok(n);
}
SeekFrom::End(n) => (self.inner.as_ref().len() as u64, n),
SeekFrom::Current(n) => (self.pos, n),
};
let new_pos = if offset >= 0 {
base_pos.checked_add(offset as u64)
} else {
base_pos.checked_sub((offset.wrapping_neg()) as u64)
};
match new_pos {
Some(n) => {
self.pos = n;
Ok(self.pos)
}
None => Err(Error::new(
ErrorKind::InvalidInput,
"invalid seek to a negative or overflowing position",
)),
}
}
fn stream_len(&mut self) -> io::Result<u64> {
Ok(self.inner.as_ref().len() as u64)
}
fn stream_position(&mut self) -> io::Result<u64> {
Ok(self.pos)
}
}
impl<T> Read for Cursor<T>
where
T: AsRef<[u8]>,
{
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
let n = Read::read(&mut self.get_buf()?, buf)?;
self.pos += n as u64;
Ok(n)
}
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
let mut nread = 0;
for buf in bufs {
let n = self.read(buf)?;
nread += n;
if n < buf.len() {
break;
}
}
Ok(nread)
}
fn is_read_vectored(&self) -> bool {
true
}
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
let n = buf.len();
Read::read_exact(&mut self.get_buf()?, buf)?;
self.pos += n as u64;
Ok(())
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
}
impl<T> Cursor<T>
where
T: AsRef<[u8]>,
{
fn get_buf(&mut self) -> io::Result<&[u8]> {
let amt = cmp::min(self.pos, self.inner.as_ref().len() as u64);
Ok(&self.inner.as_ref()[(amt as usize)..])
}
}
#[cfg(feature="collections")]
impl<T> BufRead for Cursor<T>
where
T: AsRef<[u8]>,
{
fn fill_buf(&mut self) -> io::Result<&[u8]> {
self.get_buf()
}
fn consume(&mut self, amt: usize) {
self.pos += amt as u64;
}
}
// Non-resizing write implementation
#[inline]
fn slice_write(pos_mut: &mut u64, slice: &mut [u8], buf: &[u8]) -> io::Result<usize> {
let pos = cmp::min(*pos_mut, slice.len() as u64);
let amt = (&mut slice[(pos as usize)..]).write(buf)?;
*pos_mut += amt as u64;
Ok(amt)
}
#[inline]
fn slice_write_vectored(
pos_mut: &mut u64,
slice: &mut [u8],
bufs: &[IoSlice<'_>],
) -> io::Result<usize> {
let mut nwritten = 0;
for buf in bufs {
let n = slice_write(pos_mut, slice, buf)?;
nwritten += n;
if n < buf.len() {
break;
}
}
Ok(nwritten)
}
// Resizing write implementation
#[cfg(feature="collections")]
fn vec_write(pos_mut: &mut u64, vec: &mut Vec<u8>, buf: &[u8]) -> io::Result<usize> {
let pos: usize = (*pos_mut).try_into().map_err(|_| {
Error::new(
ErrorKind::InvalidInput,
"cursor position exceeds maximum possible vector length",
)
})?;
// Make sure the internal buffer is as least as big as where we
// currently are
let len = vec.len();
if len < pos {
// use `resize` so that the zero filling is as efficient as possible
vec.resize(pos, 0);
}
// Figure out what bytes will be used to overwrite what's currently
// there (left), and what will be appended on the end (right)
{
let space = vec.len() - pos;
let (left, right) = buf.split_at(cmp::min(space, buf.len()));
vec[pos..pos + left.len()].copy_from_slice(left);
vec.extend_from_slice(right);
}
// Bump us forward
*pos_mut = (pos + buf.len()) as u64;
Ok(buf.len())
}
#[cfg(feature="collections")]
fn vec_write_vectored(
pos_mut: &mut u64,
vec: &mut Vec<u8>,
bufs: &[IoSlice<'_>],
) -> io::Result<usize> {
let mut nwritten = 0;
for buf in bufs {
nwritten += vec_write(pos_mut, vec, buf)?;
}
Ok(nwritten)
}
impl Write for Cursor<&mut [u8]> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
slice_write(&mut self.pos, self.inner, buf)
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
slice_write_vectored(&mut self.pos, self.inner, bufs)
}
#[inline]
fn is_write_vectored(&self) -> bool {
true
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
#[cfg(feature="collections")]
impl Write for Cursor<&mut Vec<u8>> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
vec_write(&mut self.pos, self.inner, buf)
}
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
vec_write_vectored(&mut self.pos, self.inner, bufs)
}
#[inline]
fn is_write_vectored(&self) -> bool {
true
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
#[cfg(feature = "collections")]
impl Write for Cursor<Vec<u8>> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
vec_write(&mut self.pos, &mut self.inner, buf)
}
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
vec_write_vectored(&mut self.pos, &mut self.inner, bufs)
}
#[inline]
fn is_write_vectored(&self) -> bool {
true
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
#[cfg(feature = "alloc")]
impl Write for Cursor<::alloc::boxed::Box<[u8]>> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
slice_write(&mut self.pos, &mut self.inner, buf)
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
slice_write_vectored(&mut self.pos, &mut self.inner, bufs)
}
#[inline]
fn is_write_vectored(&self) -> bool {
true
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}

View File

@ -0,0 +1,523 @@
use crate::io::prelude::*;
use crate::io::{Cursor, IoSlice, IoSliceMut, SeekFrom};
#[test]
fn test_vec_writer() {
let mut writer = Vec::new();
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(
writer
.write_vectored(&[IoSlice::new(&[]), IoSlice::new(&[8, 9]), IoSlice::new(&[10])],)
.unwrap(),
3
);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
assert_eq!(writer, b);
}
#[test]
fn test_mem_writer() {
let mut writer = Cursor::new(Vec::new());
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(
writer
.write_vectored(&[IoSlice::new(&[]), IoSlice::new(&[8, 9]), IoSlice::new(&[10])],)
.unwrap(),
3
);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
assert_eq!(&writer.get_ref()[..], b);
}
#[test]
fn test_mem_mut_writer() {
let mut vec = Vec::new();
let mut writer = Cursor::new(&mut vec);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(
writer
.write_vectored(&[IoSlice::new(&[]), IoSlice::new(&[8, 9]), IoSlice::new(&[10])],)
.unwrap(),
3
);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
assert_eq!(&writer.get_ref()[..], b);
}
#[test]
fn test_box_slice_writer() {
let mut writer = Cursor::new(vec![0u8; 9].into_boxed_slice());
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[]).unwrap(), 0);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[8, 9]).unwrap(), 1);
assert_eq!(writer.write(&[10]).unwrap(), 0);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8];
assert_eq!(&**writer.get_ref(), b);
}
#[test]
fn test_box_slice_writer_vectored() {
let mut writer = Cursor::new(vec![0u8; 9].into_boxed_slice());
assert_eq!(writer.position(), 0);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[0])]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(
writer.write_vectored(&[IoSlice::new(&[1, 2, 3]), IoSlice::new(&[4, 5, 6, 7]),]).unwrap(),
7,
);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write_vectored(&[]).unwrap(), 0);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[8, 9])]).unwrap(), 1);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[10])]).unwrap(), 0);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8];
assert_eq!(&**writer.get_ref(), b);
}
#[test]
fn test_buf_writer() {
let mut buf = [0 as u8; 9];
{
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[]).unwrap(), 0);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[8, 9]).unwrap(), 1);
assert_eq!(writer.write(&[10]).unwrap(), 0);
}
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8];
assert_eq!(buf, b);
}
#[test]
fn test_buf_writer_vectored() {
let mut buf = [0 as u8; 9];
{
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[0])]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(
writer
.write_vectored(&[IoSlice::new(&[1, 2, 3]), IoSlice::new(&[4, 5, 6, 7])],)
.unwrap(),
7,
);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write_vectored(&[]).unwrap(), 0);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[8, 9])]).unwrap(), 1);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[10])]).unwrap(), 0);
}
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8];
assert_eq!(buf, b);
}
#[test]
fn test_buf_writer_seek() {
let mut buf = [0 as u8; 8];
{
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[1]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.seek(SeekFrom::Start(2)).unwrap(), 2);
assert_eq!(writer.position(), 2);
assert_eq!(writer.write(&[2]).unwrap(), 1);
assert_eq!(writer.position(), 3);
assert_eq!(writer.seek(SeekFrom::Current(-2)).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[3]).unwrap(), 1);
assert_eq!(writer.position(), 2);
assert_eq!(writer.seek(SeekFrom::End(-1)).unwrap(), 7);
assert_eq!(writer.position(), 7);
assert_eq!(writer.write(&[4]).unwrap(), 1);
assert_eq!(writer.position(), 8);
}
let b: &[_] = &[1, 3, 2, 0, 0, 0, 0, 4];
assert_eq!(buf, b);
}
#[test]
fn test_buf_writer_error() {
let mut buf = [0 as u8; 2];
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[0, 0]).unwrap(), 1);
assert_eq!(writer.write(&[0, 0]).unwrap(), 0);
}
#[test]
fn test_mem_reader() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7]);
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.position(), 5);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(buf, b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_mem_reader_vectored() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7]);
let mut buf = [];
assert_eq!(reader.read_vectored(&mut [IoSliceMut::new(&mut buf)]).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(
reader.read_vectored(&mut [IoSliceMut::new(&mut []), IoSliceMut::new(&mut buf),]).unwrap(),
1,
);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf1 = [0; 4];
let mut buf2 = [0; 4];
assert_eq!(
reader
.read_vectored(&mut [IoSliceMut::new(&mut buf1), IoSliceMut::new(&mut buf2),])
.unwrap(),
7,
);
let b1: &[_] = &[1, 2, 3, 4];
let b2: &[_] = &[5, 6, 7];
assert_eq!(buf1, b1);
assert_eq!(&buf2[..3], b2);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_boxed_slice_reader() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7].into_boxed_slice());
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.position(), 5);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(buf, b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_boxed_slice_reader_vectored() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7].into_boxed_slice());
let mut buf = [];
assert_eq!(reader.read_vectored(&mut [IoSliceMut::new(&mut buf)]).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(
reader.read_vectored(&mut [IoSliceMut::new(&mut []), IoSliceMut::new(&mut buf),]).unwrap(),
1,
);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf1 = [0; 4];
let mut buf2 = [0; 4];
assert_eq!(
reader
.read_vectored(&mut [IoSliceMut::new(&mut buf1), IoSliceMut::new(&mut buf2)],)
.unwrap(),
7,
);
let b1: &[_] = &[1, 2, 3, 4];
let b2: &[_] = &[5, 6, 7];
assert_eq!(buf1, b1);
assert_eq!(&buf2[..3], b2);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn read_to_end() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7]);
let mut v = Vec::new();
reader.read_to_end(&mut v).unwrap();
assert_eq!(v, [0, 1, 2, 3, 4, 5, 6, 7]);
}
#[test]
fn test_slice_reader() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let reader = &mut &in_buf[..];
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.len(), 7);
let b: &[_] = &[0];
assert_eq!(&buf[..], b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.len(), 3);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(&buf[..], b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_slice_reader_vectored() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let reader = &mut &in_buf[..];
let mut buf = [];
assert_eq!(reader.read_vectored(&mut [IoSliceMut::new(&mut buf)]).unwrap(), 0);
let mut buf = [0];
assert_eq!(
reader.read_vectored(&mut [IoSliceMut::new(&mut []), IoSliceMut::new(&mut buf),]).unwrap(),
1,
);
assert_eq!(reader.len(), 7);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf1 = [0; 4];
let mut buf2 = [0; 4];
assert_eq!(
reader
.read_vectored(&mut [IoSliceMut::new(&mut buf1), IoSliceMut::new(&mut buf2)],)
.unwrap(),
7,
);
let b1: &[_] = &[1, 2, 3, 4];
let b2: &[_] = &[5, 6, 7];
assert_eq!(buf1, b1);
assert_eq!(&buf2[..3], b2);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_read_exact() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let reader = &mut &in_buf[..];
let mut buf = [];
assert!(reader.read_exact(&mut buf).is_ok());
let mut buf = [8];
assert!(reader.read_exact(&mut buf).is_ok());
assert_eq!(buf[0], 0);
assert_eq!(reader.len(), 7);
let mut buf = [0, 0, 0, 0, 0, 0, 0];
assert!(reader.read_exact(&mut buf).is_ok());
assert_eq!(buf, [1, 2, 3, 4, 5, 6, 7]);
assert_eq!(reader.len(), 0);
let mut buf = [0];
assert!(reader.read_exact(&mut buf).is_err());
}
#[test]
fn test_buf_reader() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let mut reader = Cursor::new(&in_buf[..]);
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.position(), 5);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(buf, b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn seek_past_end() {
let buf = [0xff];
let mut r = Cursor::new(&buf[..]);
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.read(&mut [0]).unwrap(), 0);
let mut r = Cursor::new(vec![10]);
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.read(&mut [0]).unwrap(), 0);
let mut buf = [0];
let mut r = Cursor::new(&mut buf[..]);
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.write(&[3]).unwrap(), 0);
let mut r = Cursor::new(vec![10].into_boxed_slice());
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.write(&[3]).unwrap(), 0);
}
#[test]
fn seek_past_i64() {
let buf = [0xff];
let mut r = Cursor::new(&buf[..]);
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
let mut r = Cursor::new(vec![10]);
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
let mut buf = [0];
let mut r = Cursor::new(&mut buf[..]);
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
let mut r = Cursor::new(vec![10].into_boxed_slice());
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
}
#[test]
fn seek_before_0() {
let buf = [0xff];
let mut r = Cursor::new(&buf[..]);
assert!(r.seek(SeekFrom::End(-2)).is_err());
let mut r = Cursor::new(vec![10]);
assert!(r.seek(SeekFrom::End(-2)).is_err());
let mut buf = [0];
let mut r = Cursor::new(&mut buf[..]);
assert!(r.seek(SeekFrom::End(-2)).is_err());
let mut r = Cursor::new(vec![10].into_boxed_slice());
assert!(r.seek(SeekFrom::End(-2)).is_err());
}
#[test]
fn test_seekable_mem_writer() {
let mut writer = Cursor::new(Vec::<u8>::new());
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.position(), 8);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::Start(0)).unwrap(), 0);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[3, 4]).unwrap(), 2);
let b: &[_] = &[3, 4, 2, 3, 4, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::Current(1)).unwrap(), 3);
assert_eq!(writer.write(&[0, 1]).unwrap(), 2);
let b: &[_] = &[3, 4, 2, 0, 1, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::End(-1)).unwrap(), 7);
assert_eq!(writer.write(&[1, 2]).unwrap(), 2);
let b: &[_] = &[3, 4, 2, 0, 1, 5, 6, 1, 2];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::End(1)).unwrap(), 10);
assert_eq!(writer.write(&[1]).unwrap(), 1);
let b: &[_] = &[3, 4, 2, 0, 1, 5, 6, 1, 2, 0, 1];
assert_eq!(&writer.get_ref()[..], b);
}
#[test]
fn vec_seek_past_end() {
let mut r = Cursor::new(Vec::new());
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.write(&[3]).unwrap(), 1);
}
#[test]
fn vec_seek_before_0() {
let mut r = Cursor::new(Vec::new());
assert!(r.seek(SeekFrom::End(-2)).is_err());
}
#[test]
#[cfg(target_pointer_width = "32")]
fn vec_seek_and_write_past_usize_max() {
let mut c = Cursor::new(Vec::new());
c.set_position(usize::MAX as u64 + 1);
assert!(c.write_all(&[1, 2, 3]).is_err());
}
#[test]
fn test_partial_eq() {
assert_eq!(Cursor::new(Vec::<u8>::new()), Cursor::new(Vec::<u8>::new()));
}
#[test]
fn test_eq() {
struct AssertEq<T: Eq>(pub T);
let _: AssertEq<Cursor<Vec<u8>>> = AssertEq(Cursor::new(Vec::new()));
}
#[allow(dead_code)]
fn const_cursor() {
const CURSOR: Cursor<&[u8]> = Cursor::new(&[0]);
const _: &&[u8] = CURSOR.get_ref();
const _: u64 = CURSOR.position();
}

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@ -0,0 +1,508 @@
#[cfg(test)]
mod tests;
use core::convert::From;
use core::fmt;
use core::result;
use core::convert::Into;
use core::marker::{Send, Sync};
use core::option::Option::{self, Some, None};
#[cfg(feature="alloc")] use alloc::boxed::Box;
#[cfg(not(feature="alloc"))] use ::FakeBox as Box;
#[cfg(feature="collections")] use collections::string::String;
#[cfg(not(feature="collections"))] use ::ErrorString as String;
/// A specialized [`Result`] type for I/O operations.
///
/// This type is broadly used across [`std::io`] for any operation which may
/// produce an error.
///
/// This typedef is generally used to avoid writing out [`io::Error`] directly and
/// is otherwise a direct mapping to [`Result`].
///
/// While usual Rust style is to import types directly, aliases of [`Result`]
/// often are not, to make it easier to distinguish between them. [`Result`] is
/// generally assumed to be [`std::result::Result`][`Result`], and so users of this alias
/// will generally use `io::Result` instead of shadowing the [prelude]'s import
/// of [`std::result::Result`][`Result`].
///
/// [`std::io`]: crate::io
/// [`io::Error`]: Error
/// [`Result`]: crate::result::Result
/// [prelude]: crate::prelude
///
/// # Examples
///
/// A convenience function that bubbles an `io::Result` to its caller:
///
/// ```
/// use std::io;
///
/// fn get_string() -> io::Result<String> {
/// let mut buffer = String::new();
///
/// io::stdin().read_line(&mut buffer)?;
///
/// Ok(buffer)
/// }
/// ```
pub type Result<T> = result::Result<T, Error>;
/// The error type for I/O operations of the [`Read`], [`Write`], [`Seek`], and
/// associated traits.
///
/// Errors mostly originate from the underlying OS, but custom instances of
/// `Error` can be created with crafted error messages and a particular value of
/// [`ErrorKind`].
///
/// [`Read`]: crate::io::Read
/// [`Write`]: crate::io::Write
/// [`Seek`]: crate::io::Seek
pub struct Error {
repr: Repr,
}
impl fmt::Debug for Error {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt::Debug::fmt(&self.repr, f)
}
}
enum Repr {
Os(i32),
Simple(ErrorKind),
#[cfg(feature="alloc")]
Custom(Box<Custom>),
#[cfg(not(feature="alloc"))]
Custom(Custom),
}
#[derive(Debug)]
struct Custom {
kind: ErrorKind,
error: String,
}
/// A list specifying general categories of I/O error.
///
/// This list is intended to grow over time and it is not recommended to
/// exhaustively match against it.
///
/// It is used with the [`io::Error`] type.
///
/// [`io::Error`]: Error
#[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
#[allow(deprecated)]
#[non_exhaustive]
pub enum ErrorKind {
/// An entity was not found, often a file.
NotFound,
/// The operation lacked the necessary privileges to complete.
PermissionDenied,
/// The connection was refused by the remote server.
ConnectionRefused,
/// The connection was reset by the remote server.
ConnectionReset,
/// The connection was aborted (terminated) by the remote server.
ConnectionAborted,
/// The network operation failed because it was not connected yet.
NotConnected,
/// A socket address could not be bound because the address is already in
/// use elsewhere.
AddrInUse,
/// A nonexistent interface was requested or the requested address was not
/// local.
AddrNotAvailable,
/// The operation failed because a pipe was closed.
BrokenPipe,
/// An entity already exists, often a file.
AlreadyExists,
/// The operation needs to block to complete, but the blocking operation was
/// requested to not occur.
WouldBlock,
/// A parameter was incorrect.
InvalidInput,
/// Data not valid for the operation were encountered.
///
/// Unlike [`InvalidInput`], this typically means that the operation
/// parameters were valid, however the error was caused by malformed
/// input data.
///
/// For example, a function that reads a file into a string will error with
/// `InvalidData` if the file's contents are not valid UTF-8.
///
/// [`InvalidInput`]: ErrorKind::InvalidInput
InvalidData,
/// The I/O operation's timeout expired, causing it to be canceled.
TimedOut,
/// An error returned when an operation could not be completed because a
/// call to [`write`] returned [`Ok(0)`].
///
/// This typically means that an operation could only succeed if it wrote a
/// particular number of bytes but only a smaller number of bytes could be
/// written.
///
/// [`write`]: crate::io::Write::write
/// [`Ok(0)`]: Ok
WriteZero,
/// This operation was interrupted.
///
/// Interrupted operations can typically be retried.
Interrupted,
/// Any I/O error not part of this list.
///
/// Errors that are `Other` now may move to a different or a new
/// [`ErrorKind`] variant in the future. It is not recommended to match
/// an error against `Other` and to expect any additional characteristics,
/// e.g., a specific [`Error::raw_os_error`] return value.
Other,
/// An error returned when an operation could not be completed because an
/// "end of file" was reached prematurely.
///
/// This typically means that an operation could only succeed if it read a
/// particular number of bytes but only a smaller number of bytes could be
/// read.
UnexpectedEof,
}
impl ErrorKind {
pub(crate) fn as_str(&self) -> &'static str {
match *self {
ErrorKind::NotFound => "entity not found",
ErrorKind::PermissionDenied => "permission denied",
ErrorKind::ConnectionRefused => "connection refused",
ErrorKind::ConnectionReset => "connection reset",
ErrorKind::ConnectionAborted => "connection aborted",
ErrorKind::NotConnected => "not connected",
ErrorKind::AddrInUse => "address in use",
ErrorKind::AddrNotAvailable => "address not available",
ErrorKind::BrokenPipe => "broken pipe",
ErrorKind::AlreadyExists => "entity already exists",
ErrorKind::WouldBlock => "operation would block",
ErrorKind::InvalidInput => "invalid input parameter",
ErrorKind::InvalidData => "invalid data",
ErrorKind::TimedOut => "timed out",
ErrorKind::WriteZero => "write zero",
ErrorKind::Interrupted => "operation interrupted",
ErrorKind::Other => "other os error",
ErrorKind::UnexpectedEof => "unexpected end of file",
}
}
}
/// Intended for use for errors not exposed to the user, where allocating onto
/// the heap (for normal construction via Error::new) is too costly.
impl From<ErrorKind> for Error {
/// Converts an [`ErrorKind`] into an [`Error`].
///
/// This conversion allocates a new error with a simple representation of error kind.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// let not_found = ErrorKind::NotFound;
/// let error = Error::from(not_found);
/// assert_eq!("entity not found", format!("{}", error));
/// ```
#[inline]
fn from(kind: ErrorKind) -> Error {
Error { repr: Repr::Simple(kind) }
}
}
impl Error {
/// Creates a new I/O error from a known kind of error as well as an
/// arbitrary error payload.
///
/// This function is used to generically create I/O errors which do not
/// originate from the OS itself. The `error` argument is an arbitrary
/// payload which will be contained in this [`Error`].
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// // errors can be created from strings
/// let custom_error = Error::new(ErrorKind::Other, "oh no!");
///
/// // errors can also be created from other errors
/// let custom_error2 = Error::new(ErrorKind::Interrupted, custom_error);
/// ```
pub fn new<E>(kind: ErrorKind, error: E) -> Error
where
E: Into<String>,
{
Self::_new(kind, error.into())
}
fn _new(kind: ErrorKind, error: String) -> Error {
Error { repr: Repr::Custom(Box::new(Custom { kind, error })) }
}
/// Creates a new instance of an [`Error`] from a particular OS error code.
///
/// # Examples
///
/// On Linux:
///
/// ```
/// # if cfg!(target_os = "linux") {
/// use std::io;
///
/// let error = io::Error::from_raw_os_error(22);
/// assert_eq!(error.kind(), io::ErrorKind::InvalidInput);
/// # }
/// ```
///
/// On Windows:
///
/// ```
/// # if cfg!(windows) {
/// use std::io;
///
/// let error = io::Error::from_raw_os_error(10022);
/// assert_eq!(error.kind(), io::ErrorKind::InvalidInput);
/// # }
/// ```
pub fn from_raw_os_error(code: i32) -> Error {
Error { repr: Repr::Os(code) }
}
/// Returns the OS error that this error represents (if any).
///
/// If this [`Error`] was constructed via [`last_os_error`] or
/// [`from_raw_os_error`], then this function will return [`Some`], otherwise
/// it will return [`None`].
///
/// [`last_os_error`]: Error::last_os_error
/// [`from_raw_os_error`]: Error::from_raw_os_error
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_os_error(err: &Error) {
/// if let Some(raw_os_err) = err.raw_os_error() {
/// println!("raw OS error: {:?}", raw_os_err);
/// } else {
/// println!("Not an OS error");
/// }
/// }
///
/// fn main() {
/// // Will print "raw OS error: ...".
/// print_os_error(&Error::last_os_error());
/// // Will print "Not an OS error".
/// print_os_error(&Error::new(ErrorKind::Other, "oh no!"));
/// }
/// ```
pub fn raw_os_error(&self) -> Option<i32> {
match self.repr {
Repr::Os(i) => Some(i),
Repr::Custom(..) => None,
Repr::Simple(..) => None,
}
}
/// Returns a reference to the inner error wrapped by this error (if any).
///
/// If this [`Error`] was constructed via [`new`] then this function will
/// return [`Some`], otherwise it will return [`None`].
///
/// [`new`]: Error::new
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_error(err: &Error) {
/// if let Some(inner_err) = err.get_ref() {
/// println!("Inner error: {:?}", inner_err);
/// } else {
/// println!("No inner error");
/// }
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(&Error::last_os_error());
/// // Will print "Inner error: ...".
/// print_error(&Error::new(ErrorKind::Other, "oh no!"));
/// }
/// ```
pub fn get_ref(&self) -> Option<&String> {
match self.repr {
Repr::Os(..) => None,
Repr::Simple(..) => None,
Repr::Custom(ref c) => Some(&c.error),
}
}
/// Returns a mutable reference to the inner error wrapped by this error
/// (if any).
///
/// If this [`Error`] was constructed via [`new`] then this function will
/// return [`Some`], otherwise it will return [`None`].
///
/// [`new`]: Error::new
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
/// use std::{error, fmt};
/// use std::fmt::Display;
///
/// #[derive(Debug)]
/// struct MyError {
/// v: String,
/// }
///
/// impl MyError {
/// fn new() -> MyError {
/// MyError {
/// v: "oh no!".to_string()
/// }
/// }
///
/// fn change_message(&mut self, new_message: &str) {
/// self.v = new_message.to_string();
/// }
/// }
///
/// impl error::Error for MyError {}
///
/// impl Display for MyError {
/// fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
/// write!(f, "MyError: {}", &self.v)
/// }
/// }
///
/// fn change_error(mut err: Error) -> Error {
/// if let Some(inner_err) = err.get_mut() {
/// inner_err.downcast_mut::<MyError>().unwrap().change_message("I've been changed!");
/// }
/// err
/// }
///
/// fn print_error(err: &Error) {
/// if let Some(inner_err) = err.get_ref() {
/// println!("Inner error: {}", inner_err);
/// } else {
/// println!("No inner error");
/// }
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(&change_error(Error::last_os_error()));
/// // Will print "Inner error: ...".
/// print_error(&change_error(Error::new(ErrorKind::Other, MyError::new())));
/// }
/// ```
pub fn get_mut(&mut self) -> Option<&mut String> {
match self.repr {
Repr::Os(..) => None,
Repr::Simple(..) => None,
Repr::Custom(ref mut c) => Some(&mut c.error),
}
}
/// Consumes the `Error`, returning its inner error (if any).
///
/// If this [`Error`] was constructed via [`new`] then this function will
/// return [`Some`], otherwise it will return [`None`].
///
/// [`new`]: Error::new
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_error(err: Error) {
/// if let Some(inner_err) = err.into_inner() {
/// println!("Inner error: {}", inner_err);
/// } else {
/// println!("No inner error");
/// }
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(Error::last_os_error());
/// // Will print "Inner error: ...".
/// print_error(Error::new(ErrorKind::Other, "oh no!"));
/// }
/// ```
pub fn into_inner(self) -> Option<String> {
match self.repr {
Repr::Os(..) => None,
Repr::Simple(..) => None,
Repr::Custom(c) => Some(c.error),
}
}
/// Returns the corresponding [`ErrorKind`] for this error.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_error(err: Error) {
/// println!("{:?}", err.kind());
/// }
///
/// fn main() {
/// // Will print "Other".
/// print_error(Error::last_os_error());
/// // Will print "AddrInUse".
/// print_error(Error::new(ErrorKind::AddrInUse, "oh no!"));
/// }
/// ```
pub fn kind(&self) -> ErrorKind {
match self.repr {
Repr::Os(_code) => ErrorKind::Other,
Repr::Custom(ref c) => c.kind,
Repr::Simple(kind) => kind,
}
}
}
impl fmt::Debug for Repr {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
match *self {
Repr::Os(code) => fmt
.debug_struct("Os")
.field("code", &code)
.finish(),
Repr::Custom(ref c) => fmt::Debug::fmt(&c, fmt),
Repr::Simple(kind) => fmt.debug_tuple("Kind").field(&kind).finish(),
}
}
}
impl fmt::Display for Error {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
match self.repr {
Repr::Os(code) => {
write!(fmt, "os error {}", code)
}
Repr::Custom(ref c) => c.error.fmt(fmt),
Repr::Simple(kind) => write!(fmt, "{}", kind.as_str()),
}
}
}
fn _assert_error_is_sync_send() {
fn _is_sync_send<T: Sync + Send>() {}
_is_sync_send::<Error>();
}

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@ -0,0 +1,53 @@
use super::{Custom, Error, ErrorKind, Repr};
use crate::error;
use crate::fmt;
use crate::sys::decode_error_kind;
use crate::sys::os::error_string;
#[test]
fn test_debug_error() {
let code = 6;
let msg = error_string(code);
let kind = decode_error_kind(code);
let err = Error {
repr: Repr::Custom(box Custom {
kind: ErrorKind::InvalidInput,
error: box Error { repr: super::Repr::Os(code) },
}),
};
let expected = format!(
"Custom {{ \
kind: InvalidInput, \
error: Os {{ \
code: {:?}, \
kind: {:?}, \
message: {:?} \
}} \
}}",
code, kind, msg
);
assert_eq!(format!("{:?}", err), expected);
}
#[test]
fn test_downcasting() {
#[derive(Debug)]
struct TestError;
impl fmt::Display for TestError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.write_str("asdf")
}
}
impl error::Error for TestError {}
// we have to call all of these UFCS style right now since method
// resolution won't implicitly drop the Send+Sync bounds
let mut err = Error::new(ErrorKind::Other, TestError);
assert!(err.get_ref().unwrap().is::<TestError>());
assert_eq!("asdf", err.get_ref().unwrap().to_string());
assert!(err.get_mut().unwrap().is::<TestError>());
let extracted = err.into_inner().unwrap();
extracted.downcast::<TestError>().unwrap();
}

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@ -0,0 +1,397 @@
#[cfg(test)]
mod tests;
use core::cmp;
use core::fmt;
use crate::io::{
self, Error, ErrorKind, Initializer, IoSlice, IoSliceMut, Read, Seek, SeekFrom, Write,
};
#[cfg(feature="collections")] use crate::io::BufRead;
use core::mem;
#[cfg(feature="alloc")] use alloc::boxed::Box;
#[cfg(feature="collections")] use collections::string::String;
#[cfg(feature="collections")] use collections::vec::Vec;
// =============================================================================
// Forwarding implementations
impl<R: Read + ?Sized> Read for &mut R {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
(**self).read(buf)
}
#[inline]
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
(**self).read_vectored(bufs)
}
#[inline]
fn is_read_vectored(&self) -> bool {
(**self).is_read_vectored()
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
(**self).initializer()
}
#[cfg(feature="collections")]
#[inline]
fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_to_end(buf)
}
#[cfg(feature="collections")]
#[inline]
fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_to_string(buf)
}
#[inline]
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
(**self).read_exact(buf)
}
}
impl<W: Write + ?Sized> Write for &mut W {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
(**self).write(buf)
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
(**self).write_vectored(bufs)
}
#[inline]
fn is_write_vectored(&self) -> bool {
(**self).is_write_vectored()
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
(**self).flush()
}
#[inline]
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
(**self).write_all(buf)
}
#[inline]
fn write_fmt(&mut self, fmt: fmt::Arguments<'_>) -> io::Result<()> {
(**self).write_fmt(fmt)
}
}
impl<S: Seek + ?Sized> Seek for &mut S {
#[inline]
fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
(**self).seek(pos)
}
}
#[cfg(feature="collections")]
impl<B: BufRead + ?Sized> BufRead for &mut B {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> {
(**self).fill_buf()
}
#[inline]
fn consume(&mut self, amt: usize) {
(**self).consume(amt)
}
#[inline]
fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_until(byte, buf)
}
#[inline]
fn read_line(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_line(buf)
}
}
#[cfg(feature="alloc")]
impl<R: Read + ?Sized> Read for Box<R> {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
(**self).read(buf)
}
#[inline]
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
(**self).read_vectored(bufs)
}
#[inline]
fn is_read_vectored(&self) -> bool {
(**self).is_read_vectored()
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
(**self).initializer()
}
#[cfg(feature="collections")]
#[inline]
fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_to_end(buf)
}
#[cfg(feature="collections")]
#[inline]
fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_to_string(buf)
}
#[inline]
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
(**self).read_exact(buf)
}
}
#[cfg(feature="alloc")]
impl<W: Write + ?Sized> Write for Box<W> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
(**self).write(buf)
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
(**self).write_vectored(bufs)
}
#[inline]
fn is_write_vectored(&self) -> bool {
(**self).is_write_vectored()
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
(**self).flush()
}
#[inline]
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
(**self).write_all(buf)
}
#[inline]
fn write_fmt(&mut self, fmt: fmt::Arguments<'_>) -> io::Result<()> {
(**self).write_fmt(fmt)
}
}
#[cfg(feature="alloc")]
impl<S: Seek + ?Sized> Seek for Box<S> {
#[inline]
fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
(**self).seek(pos)
}
}
#[cfg(feature="collections")]
impl<B: BufRead + ?Sized> BufRead for Box<B> {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> {
(**self).fill_buf()
}
#[inline]
fn consume(&mut self, amt: usize) {
(**self).consume(amt)
}
#[inline]
fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_until(byte, buf)
}
#[inline]
fn read_line(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_line(buf)
}
}
// =============================================================================
// In-memory buffer implementations
/// Read is implemented for `&[u8]` by copying from the slice.
///
/// Note that reading updates the slice to point to the yet unread part.
/// The slice will be empty when EOF is reached.
impl Read for &[u8] {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
let amt = cmp::min(buf.len(), self.len());
let (a, b) = self.split_at(amt);
// First check if the amount of bytes we want to read is small:
// `copy_from_slice` will generally expand to a call to `memcpy`, and
// for a single byte the overhead is significant.
if amt == 1 {
buf[0] = a[0];
} else {
buf[..amt].copy_from_slice(a);
}
*self = b;
Ok(amt)
}
#[inline]
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
let mut nread = 0;
for buf in bufs {
nread += self.read(buf)?;
if self.is_empty() {
break;
}
}
Ok(nread)
}
#[inline]
fn is_read_vectored(&self) -> bool {
true
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
#[inline]
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
if buf.len() > self.len() {
return Err(Error::new(ErrorKind::UnexpectedEof, "failed to fill whole buffer"));
}
let (a, b) = self.split_at(buf.len());
// First check if the amount of bytes we want to read is small:
// `copy_from_slice` will generally expand to a call to `memcpy`, and
// for a single byte the overhead is significant.
if buf.len() == 1 {
buf[0] = a[0];
} else {
buf.copy_from_slice(a);
}
*self = b;
Ok(())
}
#[cfg(feature="collections")]
#[inline]
fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
buf.extend_from_slice(*self);
let len = self.len();
*self = &self[len..];
Ok(len)
}
}
#[cfg(feature="collections")]
impl BufRead for &[u8] {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> {
Ok(*self)
}
#[inline]
fn consume(&mut self, amt: usize) {
*self = &self[amt..];
}
}
/// Write is implemented for `&mut [u8]` by copying into the slice, overwriting
/// its data.
///
/// Note that writing updates the slice to point to the yet unwritten part.
/// The slice will be empty when it has been completely overwritten.
///
/// If the number of bytes to be written exceeds the size of the slice, write operations will
/// return short writes: ultimately, `Ok(0)`; in this situation, `write_all` returns an error of
/// kind `ErrorKind::WriteZero`.
impl Write for &mut [u8] {
#[inline]
fn write(&mut self, data: &[u8]) -> io::Result<usize> {
let amt = cmp::min(data.len(), self.len());
let (a, b) = mem::replace(self, &mut []).split_at_mut(amt);
a.copy_from_slice(&data[..amt]);
*self = b;
Ok(amt)
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
let mut nwritten = 0;
for buf in bufs {
nwritten += self.write(buf)?;
if self.is_empty() {
break;
}
}
Ok(nwritten)
}
#[inline]
fn is_write_vectored(&self) -> bool {
true
}
#[inline]
fn write_all(&mut self, data: &[u8]) -> io::Result<()> {
if self.write(data)? == data.len() {
Ok(())
} else {
Err(Error::new(ErrorKind::WriteZero, "failed to write whole buffer"))
}
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
/// Write is implemented for `Vec<u8>` by appending to the vector.
/// The vector will grow as needed.
#[cfg(feature="collections")]
impl Write for Vec<u8> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
self.extend_from_slice(buf);
Ok(buf.len())
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
let len = bufs.iter().map(|b| b.len()).sum();
self.reserve(len);
for buf in bufs {
self.extend_from_slice(buf);
}
Ok(len)
}
#[inline]
fn is_write_vectored(&self) -> bool {
true
}
#[inline]
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
self.extend_from_slice(buf);
Ok(())
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}

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use crate::io::prelude::*;
#[bench]
fn bench_read_slice(b: &mut test::Bencher) {
let buf = [5; 1024];
let mut dst = [0; 128];
b.iter(|| {
let mut rd = &buf[..];
for _ in 0..8 {
let _ = rd.read(&mut dst);
test::black_box(&dst);
}
})
}
#[bench]
fn bench_write_slice(b: &mut test::Bencher) {
let mut buf = [0; 1024];
let src = [5; 128];
b.iter(|| {
let mut wr = &mut buf[..];
for _ in 0..8 {
let _ = wr.write_all(&src);
test::black_box(&wr);
}
})
}
#[bench]
fn bench_read_vec(b: &mut test::Bencher) {
let buf = vec![5; 1024];
let mut dst = [0; 128];
b.iter(|| {
let mut rd = &buf[..];
for _ in 0..8 {
let _ = rd.read(&mut dst);
test::black_box(&dst);
}
})
}
#[bench]
fn bench_write_vec(b: &mut test::Bencher) {
let mut buf = Vec::with_capacity(1024);
let src = [5; 128];
b.iter(|| {
let mut wr = &mut buf[..];
for _ in 0..8 {
let _ = wr.write_all(&src);
test::black_box(&wr);
}
})
}

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//! The I/O Prelude
//!
//! The purpose of this module is to alleviate imports of many common I/O traits
//! by adding a glob import to the top of I/O heavy modules:
//!
//! ```
//! # #![allow(unused_imports)]
//! use std::io::prelude::*;
//! ```
pub use super::{Read, Seek, Write};
#[cfg(feature="collections")] pub use super::BufRead;
#[cfg(feature="collections")] pub use alloc::boxed::Box;
#[cfg(feature="collections")] pub use collections::vec::Vec;

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use super::*;
use crate::panic::{RefUnwindSafe, UnwindSafe};
use crate::thread;
#[test]
fn stdout_unwind_safe() {
assert_unwind_safe::<Stdout>();
}
#[test]
fn stdoutlock_unwind_safe() {
assert_unwind_safe::<StdoutLock<'_>>();
assert_unwind_safe::<StdoutLock<'static>>();
}
#[test]
fn stderr_unwind_safe() {
assert_unwind_safe::<Stderr>();
}
#[test]
fn stderrlock_unwind_safe() {
assert_unwind_safe::<StderrLock<'_>>();
assert_unwind_safe::<StderrLock<'static>>();
}
fn assert_unwind_safe<T: UnwindSafe + RefUnwindSafe>() {}
#[test]
#[cfg_attr(target_os = "emscripten", ignore)]
fn panic_doesnt_poison() {
thread::spawn(|| {
let _a = stdin();
let _a = _a.lock();
let _a = stdout();
let _a = _a.lock();
let _a = stderr();
let _a = _a.lock();
panic!();
})
.join()
.unwrap_err();
let _a = stdin();
let _a = _a.lock();
let _a = stdout();
let _a = _a.lock();
let _a = stderr();
let _a = _a.lock();
}

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use super::{repeat, Cursor, SeekFrom};
use crate::cmp::{self, min};
use crate::io::{self, IoSlice, IoSliceMut};
use crate::io::{BufRead, Read, Seek, Write};
use crate::ops::Deref;
#[test]
#[cfg_attr(target_os = "emscripten", ignore)]
fn read_until() {
let mut buf = Cursor::new(&b"12"[..]);
let mut v = Vec::new();
assert_eq!(buf.read_until(b'3', &mut v).unwrap(), 2);
assert_eq!(v, b"12");
let mut buf = Cursor::new(&b"1233"[..]);
let mut v = Vec::new();
assert_eq!(buf.read_until(b'3', &mut v).unwrap(), 3);
assert_eq!(v, b"123");
v.truncate(0);
assert_eq!(buf.read_until(b'3', &mut v).unwrap(), 1);
assert_eq!(v, b"3");
v.truncate(0);
assert_eq!(buf.read_until(b'3', &mut v).unwrap(), 0);
assert_eq!(v, []);
}
#[test]
fn split() {
let buf = Cursor::new(&b"12"[..]);
let mut s = buf.split(b'3');
assert_eq!(s.next().unwrap().unwrap(), vec![b'1', b'2']);
assert!(s.next().is_none());
let buf = Cursor::new(&b"1233"[..]);
let mut s = buf.split(b'3');
assert_eq!(s.next().unwrap().unwrap(), vec![b'1', b'2']);
assert_eq!(s.next().unwrap().unwrap(), vec![]);
assert!(s.next().is_none());
}
#[test]
fn read_line() {
let mut buf = Cursor::new(&b"12"[..]);
let mut v = String::new();
assert_eq!(buf.read_line(&mut v).unwrap(), 2);
assert_eq!(v, "12");
let mut buf = Cursor::new(&b"12\n\n"[..]);
let mut v = String::new();
assert_eq!(buf.read_line(&mut v).unwrap(), 3);
assert_eq!(v, "12\n");
v.truncate(0);
assert_eq!(buf.read_line(&mut v).unwrap(), 1);
assert_eq!(v, "\n");
v.truncate(0);
assert_eq!(buf.read_line(&mut v).unwrap(), 0);
assert_eq!(v, "");
}
#[test]
fn lines() {
let buf = Cursor::new(&b"12\r"[..]);
let mut s = buf.lines();
assert_eq!(s.next().unwrap().unwrap(), "12\r".to_string());
assert!(s.next().is_none());
let buf = Cursor::new(&b"12\r\n\n"[..]);
let mut s = buf.lines();
assert_eq!(s.next().unwrap().unwrap(), "12".to_string());
assert_eq!(s.next().unwrap().unwrap(), "".to_string());
assert!(s.next().is_none());
}
#[test]
fn read_to_end() {
let mut c = Cursor::new(&b""[..]);
let mut v = Vec::new();
assert_eq!(c.read_to_end(&mut v).unwrap(), 0);
assert_eq!(v, []);
let mut c = Cursor::new(&b"1"[..]);
let mut v = Vec::new();
assert_eq!(c.read_to_end(&mut v).unwrap(), 1);
assert_eq!(v, b"1");
let cap = 1024 * 1024;
let data = (0..cap).map(|i| (i / 3) as u8).collect::<Vec<_>>();
let mut v = Vec::new();
let (a, b) = data.split_at(data.len() / 2);
assert_eq!(Cursor::new(a).read_to_end(&mut v).unwrap(), a.len());
assert_eq!(Cursor::new(b).read_to_end(&mut v).unwrap(), b.len());
assert_eq!(v, data);
}
#[test]
fn read_to_string() {
let mut c = Cursor::new(&b""[..]);
let mut v = String::new();
assert_eq!(c.read_to_string(&mut v).unwrap(), 0);
assert_eq!(v, "");
let mut c = Cursor::new(&b"1"[..]);
let mut v = String::new();
assert_eq!(c.read_to_string(&mut v).unwrap(), 1);
assert_eq!(v, "1");
let mut c = Cursor::new(&b"\xff"[..]);
let mut v = String::new();
assert!(c.read_to_string(&mut v).is_err());
}
#[test]
fn read_exact() {
let mut buf = [0; 4];
let mut c = Cursor::new(&b""[..]);
assert_eq!(c.read_exact(&mut buf).unwrap_err().kind(), io::ErrorKind::UnexpectedEof);
let mut c = Cursor::new(&b"123"[..]).chain(Cursor::new(&b"456789"[..]));
c.read_exact(&mut buf).unwrap();
assert_eq!(&buf, b"1234");
c.read_exact(&mut buf).unwrap();
assert_eq!(&buf, b"5678");
assert_eq!(c.read_exact(&mut buf).unwrap_err().kind(), io::ErrorKind::UnexpectedEof);
}
#[test]
fn read_exact_slice() {
let mut buf = [0; 4];
let mut c = &b""[..];
assert_eq!(c.read_exact(&mut buf).unwrap_err().kind(), io::ErrorKind::UnexpectedEof);
let mut c = &b"123"[..];
assert_eq!(c.read_exact(&mut buf).unwrap_err().kind(), io::ErrorKind::UnexpectedEof);
// make sure the optimized (early returning) method is being used
assert_eq!(&buf, &[0; 4]);
let mut c = &b"1234"[..];
c.read_exact(&mut buf).unwrap();
assert_eq!(&buf, b"1234");
let mut c = &b"56789"[..];
c.read_exact(&mut buf).unwrap();
assert_eq!(&buf, b"5678");
assert_eq!(c, b"9");
}
#[test]
fn take_eof() {
struct R;
impl Read for R {
fn read(&mut self, _: &mut [u8]) -> io::Result<usize> {
Err(io::Error::new(io::ErrorKind::Other, ""))
}
}
impl BufRead for R {
fn fill_buf(&mut self) -> io::Result<&[u8]> {
Err(io::Error::new(io::ErrorKind::Other, ""))
}
fn consume(&mut self, _amt: usize) {}
}
let mut buf = [0; 1];
assert_eq!(0, R.take(0).read(&mut buf).unwrap());
assert_eq!(b"", R.take(0).fill_buf().unwrap());
}
fn cmp_bufread<Br1: BufRead, Br2: BufRead>(mut br1: Br1, mut br2: Br2, exp: &[u8]) {
let mut cat = Vec::new();
loop {
let consume = {
let buf1 = br1.fill_buf().unwrap();
let buf2 = br2.fill_buf().unwrap();
let minlen = if buf1.len() < buf2.len() { buf1.len() } else { buf2.len() };
assert_eq!(buf1[..minlen], buf2[..minlen]);
cat.extend_from_slice(&buf1[..minlen]);
minlen
};
if consume == 0 {
break;
}
br1.consume(consume);
br2.consume(consume);
}
assert_eq!(br1.fill_buf().unwrap().len(), 0);
assert_eq!(br2.fill_buf().unwrap().len(), 0);
assert_eq!(&cat[..], &exp[..])
}
#[test]
fn chain_bufread() {
let testdata = b"ABCDEFGHIJKL";
let chain1 =
(&testdata[..3]).chain(&testdata[3..6]).chain(&testdata[6..9]).chain(&testdata[9..]);
let chain2 = (&testdata[..4]).chain(&testdata[4..8]).chain(&testdata[8..]);
cmp_bufread(chain1, chain2, &testdata[..]);
}
#[test]
fn chain_zero_length_read_is_not_eof() {
let a = b"A";
let b = b"B";
let mut s = String::new();
let mut chain = (&a[..]).chain(&b[..]);
chain.read(&mut []).unwrap();
chain.read_to_string(&mut s).unwrap();
assert_eq!("AB", s);
}
#[bench]
#[cfg_attr(target_os = "emscripten", ignore)]
fn bench_read_to_end(b: &mut test::Bencher) {
b.iter(|| {
let mut lr = repeat(1).take(10000000);
let mut vec = Vec::with_capacity(1024);
super::read_to_end(&mut lr, &mut vec)
});
}
#[test]
fn seek_len() -> io::Result<()> {
let mut c = Cursor::new(vec![0; 15]);
assert_eq!(c.stream_len()?, 15);
c.seek(SeekFrom::End(0))?;
let old_pos = c.stream_position()?;
assert_eq!(c.stream_len()?, 15);
assert_eq!(c.stream_position()?, old_pos);
c.seek(SeekFrom::Start(7))?;
c.seek(SeekFrom::Current(2))?;
let old_pos = c.stream_position()?;
assert_eq!(c.stream_len()?, 15);
assert_eq!(c.stream_position()?, old_pos);
Ok(())
}
#[test]
fn seek_position() -> io::Result<()> {
// All `asserts` are duplicated here to make sure the method does not
// change anything about the seek state.
let mut c = Cursor::new(vec![0; 15]);
assert_eq!(c.stream_position()?, 0);
assert_eq!(c.stream_position()?, 0);
c.seek(SeekFrom::End(0))?;
assert_eq!(c.stream_position()?, 15);
assert_eq!(c.stream_position()?, 15);
c.seek(SeekFrom::Start(7))?;
c.seek(SeekFrom::Current(2))?;
assert_eq!(c.stream_position()?, 9);
assert_eq!(c.stream_position()?, 9);
c.seek(SeekFrom::End(-3))?;
c.seek(SeekFrom::Current(1))?;
c.seek(SeekFrom::Current(-5))?;
assert_eq!(c.stream_position()?, 8);
assert_eq!(c.stream_position()?, 8);
Ok(())
}
// A simple example reader which uses the default implementation of
// read_to_end.
struct ExampleSliceReader<'a> {
slice: &'a [u8],
}
impl<'a> Read for ExampleSliceReader<'a> {
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
let len = cmp::min(self.slice.len(), buf.len());
buf[..len].copy_from_slice(&self.slice[..len]);
self.slice = &self.slice[len..];
Ok(len)
}
}
#[test]
fn test_read_to_end_capacity() -> io::Result<()> {
let input = &b"foo"[..];
// read_to_end() generally needs to over-allocate, both for efficiency
// and so that it can distinguish EOF. Assert that this is the case
// with this simple ExampleSliceReader struct, which uses the default
// implementation of read_to_end. Even though vec1 is allocated with
// exactly enough capacity for the read, read_to_end will allocate more
// space here.
let mut vec1 = Vec::with_capacity(input.len());
ExampleSliceReader { slice: input }.read_to_end(&mut vec1)?;
assert_eq!(vec1.len(), input.len());
assert!(vec1.capacity() > input.len(), "allocated more");
// However, std::io::Take includes an implementation of read_to_end
// that will not allocate when the limit has already been reached. In
// this case, vec2 never grows.
let mut vec2 = Vec::with_capacity(input.len());
ExampleSliceReader { slice: input }.take(input.len() as u64).read_to_end(&mut vec2)?;
assert_eq!(vec2.len(), input.len());
assert_eq!(vec2.capacity(), input.len(), "did not allocate more");
Ok(())
}
#[test]
fn io_slice_mut_advance() {
let mut buf1 = [1; 8];
let mut buf2 = [2; 16];
let mut buf3 = [3; 8];
let mut bufs = &mut [
IoSliceMut::new(&mut buf1),
IoSliceMut::new(&mut buf2),
IoSliceMut::new(&mut buf3),
][..];
// Only in a single buffer..
bufs = IoSliceMut::advance(bufs, 1);
assert_eq!(bufs[0].deref(), [1; 7].as_ref());
assert_eq!(bufs[1].deref(), [2; 16].as_ref());
assert_eq!(bufs[2].deref(), [3; 8].as_ref());
// Removing a buffer, leaving others as is.
bufs = IoSliceMut::advance(bufs, 7);
assert_eq!(bufs[0].deref(), [2; 16].as_ref());
assert_eq!(bufs[1].deref(), [3; 8].as_ref());
// Removing a buffer and removing from the next buffer.
bufs = IoSliceMut::advance(bufs, 18);
assert_eq!(bufs[0].deref(), [3; 6].as_ref());
}
#[test]
fn io_slice_mut_advance_empty_slice() {
let empty_bufs = &mut [][..];
// Shouldn't panic.
IoSliceMut::advance(empty_bufs, 1);
}
#[test]
fn io_slice_mut_advance_beyond_total_length() {
let mut buf1 = [1; 8];
let mut bufs = &mut [IoSliceMut::new(&mut buf1)][..];
// Going beyond the total length should be ok.
bufs = IoSliceMut::advance(bufs, 9);
assert!(bufs.is_empty());
}
#[test]
fn io_slice_advance() {
let buf1 = [1; 8];
let buf2 = [2; 16];
let buf3 = [3; 8];
let mut bufs = &mut [IoSlice::new(&buf1), IoSlice::new(&buf2), IoSlice::new(&buf3)][..];
// Only in a single buffer..
bufs = IoSlice::advance(bufs, 1);
assert_eq!(bufs[0].deref(), [1; 7].as_ref());
assert_eq!(bufs[1].deref(), [2; 16].as_ref());
assert_eq!(bufs[2].deref(), [3; 8].as_ref());
// Removing a buffer, leaving others as is.
bufs = IoSlice::advance(bufs, 7);
assert_eq!(bufs[0].deref(), [2; 16].as_ref());
assert_eq!(bufs[1].deref(), [3; 8].as_ref());
// Removing a buffer and removing from the next buffer.
bufs = IoSlice::advance(bufs, 18);
assert_eq!(bufs[0].deref(), [3; 6].as_ref());
}
#[test]
fn io_slice_advance_empty_slice() {
let empty_bufs = &mut [][..];
// Shouldn't panic.
IoSlice::advance(empty_bufs, 1);
}
#[test]
fn io_slice_advance_beyond_total_length() {
let buf1 = [1; 8];
let mut bufs = &mut [IoSlice::new(&buf1)][..];
// Going beyond the total length should be ok.
bufs = IoSlice::advance(bufs, 9);
assert!(bufs.is_empty());
}
/// Create a new writer that reads from at most `n_bufs` and reads
/// `per_call` bytes (in total) per call to write.
fn test_writer(n_bufs: usize, per_call: usize) -> TestWriter {
TestWriter { n_bufs, per_call, written: Vec::new() }
}
struct TestWriter {
n_bufs: usize,
per_call: usize,
written: Vec<u8>,
}
impl Write for TestWriter {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
self.write_vectored(&[IoSlice::new(buf)])
}
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
let mut left = self.per_call;
let mut written = 0;
for buf in bufs.iter().take(self.n_bufs) {
let n = min(left, buf.len());
self.written.extend_from_slice(&buf[0..n]);
left -= n;
written += n;
}
Ok(written)
}
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
#[test]
fn test_writer_read_from_one_buf() {
let mut writer = test_writer(1, 2);
assert_eq!(writer.write(&[]).unwrap(), 0);
assert_eq!(writer.write_vectored(&[]).unwrap(), 0);
// Read at most 2 bytes.
assert_eq!(writer.write(&[1, 1, 1]).unwrap(), 2);
let bufs = &[IoSlice::new(&[2, 2, 2])];
assert_eq!(writer.write_vectored(bufs).unwrap(), 2);
// Only read from first buf.
let bufs = &[IoSlice::new(&[3]), IoSlice::new(&[4, 4])];
assert_eq!(writer.write_vectored(bufs).unwrap(), 1);
assert_eq!(writer.written, &[1, 1, 2, 2, 3]);
}
#[test]
fn test_writer_read_from_multiple_bufs() {
let mut writer = test_writer(3, 3);
// Read at most 3 bytes from two buffers.
let bufs = &[IoSlice::new(&[1]), IoSlice::new(&[2, 2, 2])];
assert_eq!(writer.write_vectored(bufs).unwrap(), 3);
// Read at most 3 bytes from three buffers.
let bufs = &[IoSlice::new(&[3]), IoSlice::new(&[4]), IoSlice::new(&[5, 5])];
assert_eq!(writer.write_vectored(bufs).unwrap(), 3);
assert_eq!(writer.written, &[1, 2, 2, 3, 4, 5]);
}
#[test]
fn test_write_all_vectored() {
#[rustfmt::skip] // Becomes unreadable otherwise.
let tests: Vec<(_, &'static [u8])> = vec![
(vec![], &[]),
(vec![IoSlice::new(&[]), IoSlice::new(&[])], &[]),
(vec![IoSlice::new(&[1])], &[1]),
(vec![IoSlice::new(&[1, 2])], &[1, 2]),
(vec![IoSlice::new(&[1, 2, 3])], &[1, 2, 3]),
(vec![IoSlice::new(&[1, 2, 3, 4])], &[1, 2, 3, 4]),
(vec![IoSlice::new(&[1, 2, 3, 4, 5])], &[1, 2, 3, 4, 5]),
(vec![IoSlice::new(&[1]), IoSlice::new(&[2])], &[1, 2]),
(vec![IoSlice::new(&[1]), IoSlice::new(&[2, 2])], &[1, 2, 2]),
(vec![IoSlice::new(&[1, 1]), IoSlice::new(&[2, 2])], &[1, 1, 2, 2]),
(vec![IoSlice::new(&[1, 1]), IoSlice::new(&[2, 2, 2])], &[1, 1, 2, 2, 2]),
(vec![IoSlice::new(&[1, 1]), IoSlice::new(&[2, 2, 2])], &[1, 1, 2, 2, 2]),
(vec![IoSlice::new(&[1, 1, 1]), IoSlice::new(&[2, 2, 2])], &[1, 1, 1, 2, 2, 2]),
(vec![IoSlice::new(&[1, 1, 1]), IoSlice::new(&[2, 2, 2, 2])], &[1, 1, 1, 2, 2, 2, 2]),
(vec![IoSlice::new(&[1, 1, 1, 1]), IoSlice::new(&[2, 2, 2, 2])], &[1, 1, 1, 1, 2, 2, 2, 2]),
(vec![IoSlice::new(&[1]), IoSlice::new(&[2]), IoSlice::new(&[3])], &[1, 2, 3]),
(vec![IoSlice::new(&[1, 1]), IoSlice::new(&[2, 2]), IoSlice::new(&[3, 3])], &[1, 1, 2, 2, 3, 3]),
(vec![IoSlice::new(&[1]), IoSlice::new(&[2, 2]), IoSlice::new(&[3, 3, 3])], &[1, 2, 2, 3, 3, 3]),
(vec![IoSlice::new(&[1, 1, 1]), IoSlice::new(&[2, 2, 2]), IoSlice::new(&[3, 3, 3])], &[1, 1, 1, 2, 2, 2, 3, 3, 3]),
];
let writer_configs = &[(1, 1), (1, 2), (1, 3), (2, 2), (2, 3), (3, 3)];
for (n_bufs, per_call) in writer_configs.iter().copied() {
for (mut input, wanted) in tests.clone().into_iter() {
let mut writer = test_writer(n_bufs, per_call);
assert!(writer.write_all_vectored(&mut *input).is_ok());
assert_eq!(&*writer.written, &*wanted);
}
}
}

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@ -0,0 +1,204 @@
#![allow(missing_copy_implementations)]
#[cfg(test)]
mod tests;
use core::fmt;
use crate::io::{self, Initializer, IoSlice, IoSliceMut, Read, Write};
#[cfg(feature="collections")] use crate::io::BufRead;
/// A reader which is always at EOF.
///
/// This struct is generally created by calling [`empty()`]. Please see
/// the documentation of [`empty()`] for more details.
pub struct Empty {
_priv: (),
}
/// Constructs a new handle to an empty reader.
///
/// All reads from the returned reader will return [`Ok`]`(0)`.
///
/// # Examples
///
/// A slightly sad example of not reading anything into a buffer:
///
/// ```
/// use std::io::{self, Read};
///
/// let mut buffer = String::new();
/// io::empty().read_to_string(&mut buffer).unwrap();
/// assert!(buffer.is_empty());
/// ```
pub const fn empty() -> Empty {
Empty { _priv: () }
}
impl Read for Empty {
#[inline]
fn read(&mut self, _buf: &mut [u8]) -> io::Result<usize> {
Ok(0)
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
}
#[cfg(feature="collections")]
impl BufRead for Empty {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> {
Ok(&[])
}
#[inline]
fn consume(&mut self, _n: usize) {}
}
impl fmt::Debug for Empty {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.pad("Empty { .. }")
}
}
/// A reader which yields one byte over and over and over and over and over and...
///
/// This struct is generally created by calling [`repeat()`]. Please
/// see the documentation of [`repeat()`] for more details.
pub struct Repeat {
byte: u8,
}
/// Creates an instance of a reader that infinitely repeats one byte.
///
/// All reads from this reader will succeed by filling the specified buffer with
/// the given byte.
///
/// # Examples
///
/// ```
/// use std::io::{self, Read};
///
/// let mut buffer = [0; 3];
/// io::repeat(0b101).read_exact(&mut buffer).unwrap();
/// assert_eq!(buffer, [0b101, 0b101, 0b101]);
/// ```
pub const fn repeat(byte: u8) -> Repeat {
Repeat { byte }
}
impl Read for Repeat {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
for slot in &mut *buf {
*slot = self.byte;
}
Ok(buf.len())
}
#[inline]
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
let mut nwritten = 0;
for buf in bufs {
nwritten += self.read(buf)?;
}
Ok(nwritten)
}
#[inline]
fn is_read_vectored(&self) -> bool {
true
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
}
impl fmt::Debug for Repeat {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.pad("Repeat { .. }")
}
}
/// A writer which will move data into the void.
///
/// This struct is generally created by calling [`sink`]. Please
/// see the documentation of [`sink()`] for more details.
pub struct Sink {
_priv: (),
}
/// Creates an instance of a writer which will successfully consume all data.
///
/// All calls to [`write`] on the returned instance will return `Ok(buf.len())`
/// and the contents of the buffer will not be inspected.
///
/// [`write`]: Write::write
///
/// # Examples
///
/// ```rust
/// use std::io::{self, Write};
///
/// let buffer = vec![1, 2, 3, 5, 8];
/// let num_bytes = io::sink().write(&buffer).unwrap();
/// assert_eq!(num_bytes, 5);
/// ```
pub const fn sink() -> Sink {
Sink { _priv: () }
}
impl Write for Sink {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
Ok(buf.len())
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
let total_len = bufs.iter().map(|b| b.len()).sum();
Ok(total_len)
}
#[inline]
fn is_write_vectored(&self) -> bool {
true
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
impl Write for &Sink {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
Ok(buf.len())
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
let total_len = bufs.iter().map(|b| b.len()).sum();
Ok(total_len)
}
#[inline]
fn is_write_vectored(&self) -> bool {
true
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
impl fmt::Debug for Sink {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.pad("Sink { .. }")
}
}

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use crate::io::prelude::*;
use crate::io::{copy, empty, repeat, sink, Empty, Repeat, Sink};
#[test]
fn copy_copies() {
let mut r = repeat(0).take(4);
let mut w = sink();
assert_eq!(copy(&mut r, &mut w).unwrap(), 4);
let mut r = repeat(0).take(1 << 17);
assert_eq!(copy(&mut r as &mut dyn Read, &mut w as &mut dyn Write).unwrap(), 1 << 17);
}
#[test]
fn sink_sinks() {
let mut s = sink();
assert_eq!(s.write(&[]).unwrap(), 0);
assert_eq!(s.write(&[0]).unwrap(), 1);
assert_eq!(s.write(&[0; 1024]).unwrap(), 1024);
assert_eq!(s.by_ref().write(&[0; 1024]).unwrap(), 1024);
}
#[test]
fn empty_reads() {
let mut e = empty();
assert_eq!(e.read(&mut []).unwrap(), 0);
assert_eq!(e.read(&mut [0]).unwrap(), 0);
assert_eq!(e.read(&mut [0; 1024]).unwrap(), 0);
assert_eq!(e.by_ref().read(&mut [0; 1024]).unwrap(), 0);
}
#[test]
fn repeat_repeats() {
let mut r = repeat(4);
let mut b = [0; 1024];
assert_eq!(r.read(&mut b).unwrap(), 1024);
assert!(b.iter().all(|b| *b == 4));
}
#[test]
fn take_some_bytes() {
assert_eq!(repeat(4).take(100).bytes().count(), 100);
assert_eq!(repeat(4).take(100).bytes().next().unwrap().unwrap(), 4);
assert_eq!(repeat(1).take(10).chain(repeat(2).take(10)).bytes().count(), 20);
}
#[allow(dead_code)]
fn const_utils() {
const _: Empty = empty();
const _: Repeat = repeat(b'c');
const _: Sink = sink();
}

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use crate::io::prelude::*;
use core::cmp;
use crate::io::{self, Error, ErrorKind, Initializer, IoSlice, IoSliceMut, SeekFrom};
#[cfg(feature="collections")] use core::convert::TryInto;
/// A `Cursor` wraps an in-memory buffer and provides it with a
/// [`Seek`] implementation.
///
/// `Cursor`s are used with in-memory buffers, anything implementing
/// `AsRef<[u8]>`, to allow them to implement [`Read`] and/or [`Write`],
/// allowing these buffers to be used anywhere you might use a reader or writer
/// that does actual I/O.
///
/// The standard library implements some I/O traits on various types which
/// are commonly used as a buffer, like `Cursor<`[`Vec`]`<u8>>` and
/// `Cursor<`[`&[u8]`][bytes]`>`.
///
/// # Examples
///
/// We may want to write bytes to a [`File`] in our production
/// code, but use an in-memory buffer in our tests. We can do this with
/// `Cursor`:
///
/// [`Seek`]: trait.Seek.html
/// [`Read`]: ../../std/io/trait.Read.html
/// [`Write`]: ../../std/io/trait.Write.html
/// [`Vec`]: ../../std/vec/struct.Vec.html
/// [bytes]: ../../std/primitive.slice.html
/// [`File`]: ../fs/struct.File.html
///
/// ```no_run
/// use std::io::prelude::*;
/// use std::io::{self, SeekFrom};
/// use std::fs::File;
///
/// // a library function we've written
/// fn write_ten_bytes_at_end<W: Write + Seek>(writer: &mut W) -> io::Result<()> {
/// writer.seek(SeekFrom::End(-10))?;
///
/// for i in 0..10 {
/// writer.write(&[i])?;
/// }
///
/// // all went well
/// Ok(())
/// }
///
/// # fn foo() -> io::Result<()> {
/// // Here's some code that uses this library function.
/// //
/// // We might want to use a BufReader here for efficiency, but let's
/// // keep this example focused.
/// let mut file = File::create("foo.txt")?;
///
/// write_ten_bytes_at_end(&mut file)?;
/// # Ok(())
/// # }
///
/// // now let's write a test
/// #[test]
/// fn test_writes_bytes() {
/// // setting up a real File is much slower than an in-memory buffer,
/// // let's use a cursor instead
/// use std::io::Cursor;
/// let mut buff = Cursor::new(vec![0; 15]);
///
/// write_ten_bytes_at_end(&mut buff).unwrap();
///
/// assert_eq!(&buff.get_ref()[5..15], &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
/// }
/// ```
#[derive(Clone, Debug, Default, Eq, PartialEq)]
pub struct Cursor<T> {
inner: T,
pos: u64,
}
impl<T> Cursor<T> {
/// Creates a new cursor wrapping the provided underlying in-memory buffer.
///
/// Cursor initial position is `0` even if underlying buffer (e.g., `Vec`)
/// is not empty. So writing to cursor starts with overwriting `Vec`
/// content, not with appending to it.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
/// ```
pub fn new(inner: T) -> Cursor<T> {
Cursor { pos: 0, inner }
}
/// Consumes this cursor, returning the underlying value.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
///
/// let vec = buff.into_inner();
/// ```
pub fn into_inner(self) -> T {
self.inner
}
/// Gets a reference to the underlying value in this cursor.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
///
/// let reference = buff.get_ref();
/// ```
pub fn get_ref(&self) -> &T {
&self.inner
}
/// Gets a mutable reference to the underlying value in this cursor.
///
/// Care should be taken to avoid modifying the internal I/O state of the
/// underlying value as it may corrupt this cursor's position.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let mut buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
///
/// let reference = buff.get_mut();
/// ```
pub fn get_mut(&mut self) -> &mut T {
&mut self.inner
}
/// Returns the current position of this cursor.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
/// use std::io::prelude::*;
/// use std::io::SeekFrom;
///
/// let mut buff = Cursor::new(vec![1, 2, 3, 4, 5]);
///
/// assert_eq!(buff.position(), 0);
///
/// buff.seek(SeekFrom::Current(2)).unwrap();
/// assert_eq!(buff.position(), 2);
///
/// buff.seek(SeekFrom::Current(-1)).unwrap();
/// assert_eq!(buff.position(), 1);
/// ```
pub fn position(&self) -> u64 {
self.pos
}
/// Sets the position of this cursor.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let mut buff = Cursor::new(vec![1, 2, 3, 4, 5]);
///
/// assert_eq!(buff.position(), 0);
///
/// buff.set_position(2);
/// assert_eq!(buff.position(), 2);
///
/// buff.set_position(4);
/// assert_eq!(buff.position(), 4);
/// ```
pub fn set_position(&mut self, pos: u64) {
self.pos = pos;
}
}
impl<T> io::Seek for Cursor<T>
where
T: AsRef<[u8]>,
{
fn seek(&mut self, style: SeekFrom) -> io::Result<u64> {
let (base_pos, offset) = match style {
SeekFrom::Start(n) => {
self.pos = n;
return Ok(n);
}
SeekFrom::End(n) => (self.inner.as_ref().len() as u64, n),
SeekFrom::Current(n) => (self.pos, n),
};
let new_pos = if offset >= 0 {
base_pos.checked_add(offset as u64)
} else {
base_pos.checked_sub((offset.wrapping_neg()) as u64)
};
match new_pos {
Some(n) => {
self.pos = n;
Ok(self.pos)
}
None => Err(Error::new(
ErrorKind::InvalidInput,
"invalid seek to a negative or overflowing position",
)),
}
}
fn stream_len(&mut self) -> io::Result<u64> {
Ok(self.inner.as_ref().len() as u64)
}
fn stream_position(&mut self) -> io::Result<u64> {
Ok(self.pos)
}
}
impl<T> Read for Cursor<T>
where
T: AsRef<[u8]>,
{
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
let n = Read::read(&mut self.get_buf()?, buf)?;
self.pos += n as u64;
Ok(n)
}
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
let mut nread = 0;
for buf in bufs {
let n = self.read(buf)?;
nread += n;
if n < buf.len() {
break;
}
}
Ok(nread)
}
fn is_read_vectored(&self) -> bool {
true
}
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
let n = buf.len();
Read::read_exact(&mut self.get_buf()?, buf)?;
self.pos += n as u64;
Ok(())
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
}
impl<T> Cursor<T>
where
T: AsRef<[u8]>,
{
fn get_buf(&mut self) -> io::Result<&[u8]> {
let amt = cmp::min(self.pos, self.inner.as_ref().len() as u64);
Ok(&self.inner.as_ref()[(amt as usize)..])
}
}
#[cfg(feature="collections")]
impl<T> BufRead for Cursor<T>
where
T: AsRef<[u8]>,
{
fn fill_buf(&mut self) -> io::Result<&[u8]> {
self.get_buf()
}
fn consume(&mut self, amt: usize) {
self.pos += amt as u64;
}
}
// Non-resizing write implementation
#[inline]
fn slice_write(pos_mut: &mut u64, slice: &mut [u8], buf: &[u8]) -> io::Result<usize> {
let pos = cmp::min(*pos_mut, slice.len() as u64);
let amt = (&mut slice[(pos as usize)..]).write(buf)?;
*pos_mut += amt as u64;
Ok(amt)
}
#[inline]
fn slice_write_vectored(
pos_mut: &mut u64,
slice: &mut [u8],
bufs: &[IoSlice<'_>],
) -> io::Result<usize> {
let mut nwritten = 0;
for buf in bufs {
let n = slice_write(pos_mut, slice, buf)?;
nwritten += n;
if n < buf.len() {
break;
}
}
Ok(nwritten)
}
// Resizing write implementation
#[cfg(feature="collections")]
fn vec_write(pos_mut: &mut u64, vec: &mut Vec<u8>, buf: &[u8]) -> io::Result<usize> {
let pos: usize = (*pos_mut).try_into().map_err(|_| {
Error::new(
ErrorKind::InvalidInput,
"cursor position exceeds maximum possible vector length",
)
})?;
// Make sure the internal buffer is as least as big as where we
// currently are
let len = vec.len();
if len < pos {
// use `resize` so that the zero filling is as efficient as possible
vec.resize(pos, 0);
}
// Figure out what bytes will be used to overwrite what's currently
// there (left), and what will be appended on the end (right)
{
let space = vec.len() - pos;
let (left, right) = buf.split_at(cmp::min(space, buf.len()));
vec[pos..pos + left.len()].copy_from_slice(left);
vec.extend_from_slice(right);
}
// Bump us forward
*pos_mut = (pos + buf.len()) as u64;
Ok(buf.len())
}
#[cfg(feature="collections")]
fn vec_write_vectored(
pos_mut: &mut u64,
vec: &mut Vec<u8>,
bufs: &[IoSlice<'_>],
) -> io::Result<usize> {
let mut nwritten = 0;
for buf in bufs {
nwritten += vec_write(pos_mut, vec, buf)?;
}
Ok(nwritten)
}
impl Write for Cursor<&mut [u8]> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
slice_write(&mut self.pos, self.inner, buf)
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
slice_write_vectored(&mut self.pos, self.inner, bufs)
}
#[inline]
fn is_write_vectored(&self) -> bool {
true
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
#[cfg(feature="collections")]
impl Write for Cursor<&mut Vec<u8>> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
vec_write(&mut self.pos, self.inner, buf)
}
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
vec_write_vectored(&mut self.pos, self.inner, bufs)
}
#[inline]
fn is_write_vectored(&self) -> bool {
true
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
#[cfg(feature = "collections")]
impl Write for Cursor<Vec<u8>> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
vec_write(&mut self.pos, &mut self.inner, buf)
}
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
vec_write_vectored(&mut self.pos, &mut self.inner, bufs)
}
#[inline]
fn is_write_vectored(&self) -> bool {
true
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
#[cfg(feature = "alloc")]
impl Write for Cursor<::alloc::boxed::Box<[u8]>> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
slice_write(&mut self.pos, &mut self.inner, buf)
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
slice_write_vectored(&mut self.pos, &mut self.inner, bufs)
}
#[inline]
fn is_write_vectored(&self) -> bool {
true
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
#[cfg(test)]
mod tests {
use crate::io::prelude::*;
use crate::io::{Cursor, IoSlice, IoSliceMut, SeekFrom};
#[test]
fn test_vec_writer() {
let mut writer = Vec::new();
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(
writer
.write_vectored(&[IoSlice::new(&[]), IoSlice::new(&[8, 9]), IoSlice::new(&[10])],)
.unwrap(),
3
);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
assert_eq!(writer, b);
}
#[test]
fn test_mem_writer() {
let mut writer = Cursor::new(Vec::new());
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(
writer
.write_vectored(&[IoSlice::new(&[]), IoSlice::new(&[8, 9]), IoSlice::new(&[10])],)
.unwrap(),
3
);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
assert_eq!(&writer.get_ref()[..], b);
}
#[test]
fn test_mem_mut_writer() {
let mut vec = Vec::new();
let mut writer = Cursor::new(&mut vec);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(
writer
.write_vectored(&[IoSlice::new(&[]), IoSlice::new(&[8, 9]), IoSlice::new(&[10])],)
.unwrap(),
3
);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
assert_eq!(&writer.get_ref()[..], b);
}
#[test]
fn test_box_slice_writer() {
let mut writer = Cursor::new(vec![0u8; 9].into_boxed_slice());
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[]).unwrap(), 0);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[8, 9]).unwrap(), 1);
assert_eq!(writer.write(&[10]).unwrap(), 0);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8];
assert_eq!(&**writer.get_ref(), b);
}
#[test]
fn test_box_slice_writer_vectored() {
let mut writer = Cursor::new(vec![0u8; 9].into_boxed_slice());
assert_eq!(writer.position(), 0);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[0])]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(
writer
.write_vectored(&[IoSlice::new(&[1, 2, 3]), IoSlice::new(&[4, 5, 6, 7]),])
.unwrap(),
7,
);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write_vectored(&[]).unwrap(), 0);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[8, 9])]).unwrap(), 1);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[10])]).unwrap(), 0);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8];
assert_eq!(&**writer.get_ref(), b);
}
#[test]
fn test_buf_writer() {
let mut buf = [0 as u8; 9];
{
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[]).unwrap(), 0);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[8, 9]).unwrap(), 1);
assert_eq!(writer.write(&[10]).unwrap(), 0);
}
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8];
assert_eq!(buf, b);
}
#[test]
fn test_buf_writer_vectored() {
let mut buf = [0 as u8; 9];
{
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[0])]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(
writer
.write_vectored(&[IoSlice::new(&[1, 2, 3]), IoSlice::new(&[4, 5, 6, 7])],)
.unwrap(),
7,
);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write_vectored(&[]).unwrap(), 0);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[8, 9])]).unwrap(), 1);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[10])]).unwrap(), 0);
}
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8];
assert_eq!(buf, b);
}
#[test]
fn test_buf_writer_seek() {
let mut buf = [0 as u8; 8];
{
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[1]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.seek(SeekFrom::Start(2)).unwrap(), 2);
assert_eq!(writer.position(), 2);
assert_eq!(writer.write(&[2]).unwrap(), 1);
assert_eq!(writer.position(), 3);
assert_eq!(writer.seek(SeekFrom::Current(-2)).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[3]).unwrap(), 1);
assert_eq!(writer.position(), 2);
assert_eq!(writer.seek(SeekFrom::End(-1)).unwrap(), 7);
assert_eq!(writer.position(), 7);
assert_eq!(writer.write(&[4]).unwrap(), 1);
assert_eq!(writer.position(), 8);
}
let b: &[_] = &[1, 3, 2, 0, 0, 0, 0, 4];
assert_eq!(buf, b);
}
#[test]
fn test_buf_writer_error() {
let mut buf = [0 as u8; 2];
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[0, 0]).unwrap(), 1);
assert_eq!(writer.write(&[0, 0]).unwrap(), 0);
}
#[test]
fn test_mem_reader() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7]);
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.position(), 5);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(buf, b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_mem_reader_vectored() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7]);
let mut buf = [];
assert_eq!(reader.read_vectored(&mut [IoSliceMut::new(&mut buf)]).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(
reader
.read_vectored(&mut [IoSliceMut::new(&mut []), IoSliceMut::new(&mut buf),])
.unwrap(),
1,
);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf1 = [0; 4];
let mut buf2 = [0; 4];
assert_eq!(
reader
.read_vectored(&mut [IoSliceMut::new(&mut buf1), IoSliceMut::new(&mut buf2),])
.unwrap(),
7,
);
let b1: &[_] = &[1, 2, 3, 4];
let b2: &[_] = &[5, 6, 7];
assert_eq!(buf1, b1);
assert_eq!(&buf2[..3], b2);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_boxed_slice_reader() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7].into_boxed_slice());
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.position(), 5);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(buf, b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_boxed_slice_reader_vectored() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7].into_boxed_slice());
let mut buf = [];
assert_eq!(reader.read_vectored(&mut [IoSliceMut::new(&mut buf)]).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(
reader
.read_vectored(&mut [IoSliceMut::new(&mut []), IoSliceMut::new(&mut buf),])
.unwrap(),
1,
);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf1 = [0; 4];
let mut buf2 = [0; 4];
assert_eq!(
reader
.read_vectored(&mut [IoSliceMut::new(&mut buf1), IoSliceMut::new(&mut buf2)],)
.unwrap(),
7,
);
let b1: &[_] = &[1, 2, 3, 4];
let b2: &[_] = &[5, 6, 7];
assert_eq!(buf1, b1);
assert_eq!(&buf2[..3], b2);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn read_to_end() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7]);
let mut v = Vec::new();
reader.read_to_end(&mut v).unwrap();
assert_eq!(v, [0, 1, 2, 3, 4, 5, 6, 7]);
}
#[test]
fn test_slice_reader() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let reader = &mut &in_buf[..];
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.len(), 7);
let b: &[_] = &[0];
assert_eq!(&buf[..], b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.len(), 3);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(&buf[..], b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_slice_reader_vectored() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let reader = &mut &in_buf[..];
let mut buf = [];
assert_eq!(reader.read_vectored(&mut [IoSliceMut::new(&mut buf)]).unwrap(), 0);
let mut buf = [0];
assert_eq!(
reader
.read_vectored(&mut [IoSliceMut::new(&mut []), IoSliceMut::new(&mut buf),])
.unwrap(),
1,
);
assert_eq!(reader.len(), 7);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf1 = [0; 4];
let mut buf2 = [0; 4];
assert_eq!(
reader
.read_vectored(&mut [IoSliceMut::new(&mut buf1), IoSliceMut::new(&mut buf2)],)
.unwrap(),
7,
);
let b1: &[_] = &[1, 2, 3, 4];
let b2: &[_] = &[5, 6, 7];
assert_eq!(buf1, b1);
assert_eq!(&buf2[..3], b2);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_read_exact() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let reader = &mut &in_buf[..];
let mut buf = [];
assert!(reader.read_exact(&mut buf).is_ok());
let mut buf = [8];
assert!(reader.read_exact(&mut buf).is_ok());
assert_eq!(buf[0], 0);
assert_eq!(reader.len(), 7);
let mut buf = [0, 0, 0, 0, 0, 0, 0];
assert!(reader.read_exact(&mut buf).is_ok());
assert_eq!(buf, [1, 2, 3, 4, 5, 6, 7]);
assert_eq!(reader.len(), 0);
let mut buf = [0];
assert!(reader.read_exact(&mut buf).is_err());
}
#[test]
fn test_buf_reader() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let mut reader = Cursor::new(&in_buf[..]);
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.position(), 5);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(buf, b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn seek_past_end() {
let buf = [0xff];
let mut r = Cursor::new(&buf[..]);
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.read(&mut [0]).unwrap(), 0);
let mut r = Cursor::new(vec![10]);
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.read(&mut [0]).unwrap(), 0);
let mut buf = [0];
let mut r = Cursor::new(&mut buf[..]);
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.write(&[3]).unwrap(), 0);
let mut r = Cursor::new(vec![10].into_boxed_slice());
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.write(&[3]).unwrap(), 0);
}
#[test]
fn seek_past_i64() {
let buf = [0xff];
let mut r = Cursor::new(&buf[..]);
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
let mut r = Cursor::new(vec![10]);
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
let mut buf = [0];
let mut r = Cursor::new(&mut buf[..]);
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
let mut r = Cursor::new(vec![10].into_boxed_slice());
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
}
#[test]
fn seek_before_0() {
let buf = [0xff];
let mut r = Cursor::new(&buf[..]);
assert!(r.seek(SeekFrom::End(-2)).is_err());
let mut r = Cursor::new(vec![10]);
assert!(r.seek(SeekFrom::End(-2)).is_err());
let mut buf = [0];
let mut r = Cursor::new(&mut buf[..]);
assert!(r.seek(SeekFrom::End(-2)).is_err());
let mut r = Cursor::new(vec![10].into_boxed_slice());
assert!(r.seek(SeekFrom::End(-2)).is_err());
}
#[test]
fn test_seekable_mem_writer() {
let mut writer = Cursor::new(Vec::<u8>::new());
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.position(), 8);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::Start(0)).unwrap(), 0);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[3, 4]).unwrap(), 2);
let b: &[_] = &[3, 4, 2, 3, 4, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::Current(1)).unwrap(), 3);
assert_eq!(writer.write(&[0, 1]).unwrap(), 2);
let b: &[_] = &[3, 4, 2, 0, 1, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::End(-1)).unwrap(), 7);
assert_eq!(writer.write(&[1, 2]).unwrap(), 2);
let b: &[_] = &[3, 4, 2, 0, 1, 5, 6, 1, 2];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::End(1)).unwrap(), 10);
assert_eq!(writer.write(&[1]).unwrap(), 1);
let b: &[_] = &[3, 4, 2, 0, 1, 5, 6, 1, 2, 0, 1];
assert_eq!(&writer.get_ref()[..], b);
}
#[test]
fn vec_seek_past_end() {
let mut r = Cursor::new(Vec::new());
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.write(&[3]).unwrap(), 1);
}
#[test]
fn vec_seek_before_0() {
let mut r = Cursor::new(Vec::new());
assert!(r.seek(SeekFrom::End(-2)).is_err());
}
#[test]
#[cfg(target_pointer_width = "32")]
fn vec_seek_and_write_past_usize_max() {
let mut c = Cursor::new(Vec::new());
c.set_position(<usize>::max_value() as u64 + 1);
assert!(c.write_all(&[1, 2, 3]).is_err());
}
#[test]
fn test_partial_eq() {
assert_eq!(Cursor::new(Vec::<u8>::new()), Cursor::new(Vec::<u8>::new()));
}
#[test]
fn test_eq() {
struct AssertEq<T: Eq>(pub T);
let _: AssertEq<Cursor<Vec<u8>>> = AssertEq(Cursor::new(Vec::new()));
}
}

View File

@ -0,0 +1,552 @@
use core::convert::From;
use core::fmt;
use core::result;
use core::convert::Into;
use core::marker::{Send, Sync};
use core::option::Option::{self, Some, None};
#[cfg(feature="alloc")] use alloc::boxed::Box;
#[cfg(not(feature="alloc"))] use ::FakeBox as Box;
#[cfg(feature="collections")] use collections::string::String;
#[cfg(not(feature="collections"))] use ::ErrorString as String;
/// A specialized [`Result`](../result/enum.Result.html) type for I/O
/// operations.
///
/// This type is broadly used across [`std::io`] for any operation which may
/// produce an error.
///
/// This typedef is generally used to avoid writing out [`io::Error`] directly and
/// is otherwise a direct mapping to [`Result`].
///
/// While usual Rust style is to import types directly, aliases of [`Result`]
/// often are not, to make it easier to distinguish between them. [`Result`] is
/// generally assumed to be [`std::result::Result`][`Result`], and so users of this alias
/// will generally use `io::Result` instead of shadowing the prelude's import
/// of [`std::result::Result`][`Result`].
///
/// [`std::io`]: ../io/index.html
/// [`io::Error`]: ../io/struct.Error.html
/// [`Result`]: ../result/enum.Result.html
///
/// # Examples
///
/// A convenience function that bubbles an `io::Result` to its caller:
///
/// ```
/// use std::io;
///
/// fn get_string() -> io::Result<String> {
/// let mut buffer = String::new();
///
/// io::stdin().read_line(&mut buffer)?;
///
/// Ok(buffer)
/// }
/// ```
pub type Result<T> = result::Result<T, Error>;
/// The error type for I/O operations of the [`Read`], [`Write`], [`Seek`], and
/// associated traits.
///
/// Errors mostly originate from the underlying OS, but custom instances of
/// `Error` can be created with crafted error messages and a particular value of
/// [`ErrorKind`].
///
/// [`Read`]: ../io/trait.Read.html
/// [`Write`]: ../io/trait.Write.html
/// [`Seek`]: ../io/trait.Seek.html
/// [`ErrorKind`]: enum.ErrorKind.html
pub struct Error {
repr: Repr,
}
impl fmt::Debug for Error {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt::Debug::fmt(&self.repr, f)
}
}
enum Repr {
Os(i32),
Simple(ErrorKind),
#[cfg(feature="alloc")]
Custom(Box<Custom>),
#[cfg(not(feature="alloc"))]
Custom(Custom),
}
#[derive(Debug)]
struct Custom {
kind: ErrorKind,
error: String,
}
/// A list specifying general categories of I/O error.
///
/// This list is intended to grow over time and it is not recommended to
/// exhaustively match against it.
///
/// It is used with the [`io::Error`] type.
///
/// [`io::Error`]: struct.Error.html
#[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
#[allow(deprecated)]
#[non_exhaustive]
pub enum ErrorKind {
/// An entity was not found, often a file.
NotFound,
/// The operation lacked the necessary privileges to complete.
PermissionDenied,
/// The connection was refused by the remote server.
ConnectionRefused,
/// The connection was reset by the remote server.
ConnectionReset,
/// The connection was aborted (terminated) by the remote server.
ConnectionAborted,
/// The network operation failed because it was not connected yet.
NotConnected,
/// A socket address could not be bound because the address is already in
/// use elsewhere.
AddrInUse,
/// A nonexistent interface was requested or the requested address was not
/// local.
AddrNotAvailable,
/// The operation failed because a pipe was closed.
BrokenPipe,
/// An entity already exists, often a file.
AlreadyExists,
/// The operation needs to block to complete, but the blocking operation was
/// requested to not occur.
WouldBlock,
/// A parameter was incorrect.
InvalidInput,
/// Data not valid for the operation were encountered.
///
/// Unlike [`InvalidInput`], this typically means that the operation
/// parameters were valid, however the error was caused by malformed
/// input data.
///
/// For example, a function that reads a file into a string will error with
/// `InvalidData` if the file's contents are not valid UTF-8.
///
/// [`InvalidInput`]: #variant.InvalidInput
InvalidData,
/// The I/O operation's timeout expired, causing it to be canceled.
TimedOut,
/// An error returned when an operation could not be completed because a
/// call to [`write`] returned [`Ok(0)`].
///
/// This typically means that an operation could only succeed if it wrote a
/// particular number of bytes but only a smaller number of bytes could be
/// written.
///
/// [`write`]: ../../std/io/trait.Write.html#tymethod.write
/// [`Ok(0)`]: ../../std/io/type.Result.html
WriteZero,
/// This operation was interrupted.
///
/// Interrupted operations can typically be retried.
Interrupted,
/// Any I/O error not part of this list.
Other,
/// An error returned when an operation could not be completed because an
/// "end of file" was reached prematurely.
///
/// This typically means that an operation could only succeed if it read a
/// particular number of bytes but only a smaller number of bytes could be
/// read.
UnexpectedEof,
}
impl ErrorKind {
pub(crate) fn as_str(&self) -> &'static str {
match *self {
ErrorKind::NotFound => "entity not found",
ErrorKind::PermissionDenied => "permission denied",
ErrorKind::ConnectionRefused => "connection refused",
ErrorKind::ConnectionReset => "connection reset",
ErrorKind::ConnectionAborted => "connection aborted",
ErrorKind::NotConnected => "not connected",
ErrorKind::AddrInUse => "address in use",
ErrorKind::AddrNotAvailable => "address not available",
ErrorKind::BrokenPipe => "broken pipe",
ErrorKind::AlreadyExists => "entity already exists",
ErrorKind::WouldBlock => "operation would block",
ErrorKind::InvalidInput => "invalid input parameter",
ErrorKind::InvalidData => "invalid data",
ErrorKind::TimedOut => "timed out",
ErrorKind::WriteZero => "write zero",
ErrorKind::Interrupted => "operation interrupted",
ErrorKind::Other => "other os error",
ErrorKind::UnexpectedEof => "unexpected end of file",
}
}
}
/// Intended for use for errors not exposed to the user, where allocating onto
/// the heap (for normal construction via Error::new) is too costly.
impl From<ErrorKind> for Error {
/// Converts an [`ErrorKind`] into an [`Error`].
///
/// This conversion allocates a new error with a simple representation of error kind.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// let not_found = ErrorKind::NotFound;
/// let error = Error::from(not_found);
/// assert_eq!("entity not found", format!("{}", error));
/// ```
///
/// [`ErrorKind`]: ../../std/io/enum.ErrorKind.html
/// [`Error`]: ../../std/io/struct.Error.html
#[inline]
fn from(kind: ErrorKind) -> Error {
Error { repr: Repr::Simple(kind) }
}
}
impl Error {
/// Creates a new I/O error from a known kind of error as well as an
/// arbitrary error payload.
///
/// This function is used to generically create I/O errors which do not
/// originate from the OS itself. The `error` argument is an arbitrary
/// payload which will be contained in this `Error`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// // errors can be created from strings
/// let custom_error = Error::new(ErrorKind::Other, "oh no!");
///
/// // errors can also be created from other errors
/// let custom_error2 = Error::new(ErrorKind::Interrupted, custom_error);
/// ```
pub fn new<E>(kind: ErrorKind, error: E) -> Error
where
E: Into<String>,
{
Self::_new(kind, error.into())
}
fn _new(kind: ErrorKind, error: String) -> Error {
Error { repr: Repr::Custom(Box::new(Custom { kind, error })) }
}
/// Creates a new instance of an `Error` from a particular OS error code.
///
/// # Examples
///
/// On Linux:
///
/// ```
/// # if cfg!(target_os = "linux") {
/// use std::io;
///
/// let error = io::Error::from_raw_os_error(22);
/// assert_eq!(error.kind(), io::ErrorKind::InvalidInput);
/// # }
/// ```
///
/// On Windows:
///
/// ```
/// # if cfg!(windows) {
/// use std::io;
///
/// let error = io::Error::from_raw_os_error(10022);
/// assert_eq!(error.kind(), io::ErrorKind::InvalidInput);
/// # }
/// ```
pub fn from_raw_os_error(code: i32) -> Error {
Error { repr: Repr::Os(code) }
}
/// Returns the OS error that this error represents (if any).
///
/// If this `Error` was constructed via `last_os_error` or
/// `from_raw_os_error`, then this function will return `Some`, otherwise
/// it will return `None`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_os_error(err: &Error) {
/// if let Some(raw_os_err) = err.raw_os_error() {
/// println!("raw OS error: {:?}", raw_os_err);
/// } else {
/// println!("Not an OS error");
/// }
/// }
///
/// fn main() {
/// // Will print "raw OS error: ...".
/// print_os_error(&Error::last_os_error());
/// // Will print "Not an OS error".
/// print_os_error(&Error::new(ErrorKind::Other, "oh no!"));
/// }
/// ```
pub fn raw_os_error(&self) -> Option<i32> {
match self.repr {
Repr::Os(i) => Some(i),
Repr::Custom(..) => None,
Repr::Simple(..) => None,
}
}
/// Returns a reference to the inner error wrapped by this error (if any).
///
/// If this `Error` was constructed via `new` then this function will
/// return `Some`, otherwise it will return `None`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_error(err: &Error) {
/// if let Some(inner_err) = err.get_ref() {
/// println!("Inner error: {:?}", inner_err);
/// } else {
/// println!("No inner error");
/// }
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(&Error::last_os_error());
/// // Will print "Inner error: ...".
/// print_error(&Error::new(ErrorKind::Other, "oh no!"));
/// }
/// ```
pub fn get_ref(&self) -> Option<&String> {
match self.repr {
Repr::Os(..) => None,
Repr::Simple(..) => None,
Repr::Custom(ref c) => Some(&c.error),
}
}
/// Returns a mutable reference to the inner error wrapped by this error
/// (if any).
///
/// If this `Error` was constructed via `new` then this function will
/// return `Some`, otherwise it will return `None`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
/// use std::{error, fmt};
/// use std::fmt::Display;
///
/// #[derive(Debug)]
/// struct MyError {
/// v: String,
/// }
///
/// impl MyError {
/// fn new() -> MyError {
/// MyError {
/// v: "oh no!".to_string()
/// }
/// }
///
/// fn change_message(&mut self, new_message: &str) {
/// self.v = new_message.to_string();
/// }
/// }
///
/// impl error::Error for MyError {}
///
/// impl Display for MyError {
/// fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
/// write!(f, "MyError: {}", &self.v)
/// }
/// }
///
/// fn change_error(mut err: Error) -> Error {
/// if let Some(inner_err) = err.get_mut() {
/// inner_err.downcast_mut::<MyError>().unwrap().change_message("I've been changed!");
/// }
/// err
/// }
///
/// fn print_error(err: &Error) {
/// if let Some(inner_err) = err.get_ref() {
/// println!("Inner error: {}", inner_err);
/// } else {
/// println!("No inner error");
/// }
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(&change_error(Error::last_os_error()));
/// // Will print "Inner error: ...".
/// print_error(&change_error(Error::new(ErrorKind::Other, MyError::new())));
/// }
/// ```
pub fn get_mut(&mut self) -> Option<&mut String> {
match self.repr {
Repr::Os(..) => None,
Repr::Simple(..) => None,
Repr::Custom(ref mut c) => Some(&mut c.error),
}
}
/// Consumes the `Error`, returning its inner error (if any).
///
/// If this `Error` was constructed via `new` then this function will
/// return `Some`, otherwise it will return `None`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_error(err: Error) {
/// if let Some(inner_err) = err.into_inner() {
/// println!("Inner error: {}", inner_err);
/// } else {
/// println!("No inner error");
/// }
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(Error::last_os_error());
/// // Will print "Inner error: ...".
/// print_error(Error::new(ErrorKind::Other, "oh no!"));
/// }
/// ```
pub fn into_inner(self) -> Option<String> {
match self.repr {
Repr::Os(..) => None,
Repr::Simple(..) => None,
Repr::Custom(c) => Some(c.error),
}
}
/// Returns the corresponding `ErrorKind` for this error.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_error(err: Error) {
/// println!("{:?}", err.kind());
/// }
///
/// fn main() {
/// // Will print "Other".
/// print_error(Error::last_os_error());
/// // Will print "AddrInUse".
/// print_error(Error::new(ErrorKind::AddrInUse, "oh no!"));
/// }
/// ```
pub fn kind(&self) -> ErrorKind {
match self.repr {
Repr::Os(_code) => ErrorKind::Other,
Repr::Custom(ref c) => c.kind,
Repr::Simple(kind) => kind,
}
}
}
impl fmt::Debug for Repr {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
match *self {
Repr::Os(code) => fmt
.debug_struct("Os")
.field("code", &code)
.finish(),
Repr::Custom(ref c) => fmt::Debug::fmt(&c, fmt),
Repr::Simple(kind) => fmt.debug_tuple("Kind").field(&kind).finish(),
}
}
}
impl fmt::Display for Error {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
match self.repr {
Repr::Os(code) => {
write!(fmt, "os error {}", code)
}
Repr::Custom(ref c) => c.error.fmt(fmt),
Repr::Simple(kind) => write!(fmt, "{}", kind.as_str()),
}
}
}
fn _assert_error_is_sync_send() {
fn _is_sync_send<T: Sync + Send>() {}
_is_sync_send::<Error>();
}
#[cfg(test)]
mod test {
use super::{Custom, Error, ErrorKind, Repr};
use crate::error;
use crate::fmt;
use crate::sys::decode_error_kind;
use crate::sys::os::error_string;
#[test]
fn test_debug_error() {
let code = 6;
let msg = error_string(code);
let kind = decode_error_kind(code);
let err = Error {
repr: Repr::Custom(box Custom {
kind: ErrorKind::InvalidInput,
error: box Error { repr: super::Repr::Os(code) },
}),
};
let expected = format!(
"Custom {{ \
kind: InvalidInput, \
error: Os {{ \
code: {:?}, \
kind: {:?}, \
message: {:?} \
}} \
}}",
code, kind, msg
);
assert_eq!(format!("{:?}", err), expected);
}
#[test]
fn test_downcasting() {
#[derive(Debug)]
struct TestError;
impl fmt::Display for TestError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.write_str("asdf")
}
}
impl error::Error for TestError {}
// we have to call all of these UFCS style right now since method
// resolution won't implicitly drop the Send+Sync bounds
let mut err = Error::new(ErrorKind::Other, TestError);
assert!(err.get_ref().unwrap().is::<TestError>());
assert_eq!("asdf", err.get_ref().unwrap().to_string());
assert!(err.get_mut().unwrap().is::<TestError>());
let extracted = err.into_inner().unwrap();
extracted.downcast::<TestError>().unwrap();
}
}

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@ -0,0 +1,465 @@
use core::cmp;
use core::fmt;
use crate::io::{
self, Error, ErrorKind, Initializer, IoSlice, IoSliceMut, Read, Seek, SeekFrom, Write,
};
#[cfg(feature="collections")] use crate::io::BufRead;
use core::mem;
#[cfg(feature="alloc")] use alloc::boxed::Box;
#[cfg(feature="collections")] use collections::string::String;
#[cfg(feature="collections")] use collections::vec::Vec;
// =============================================================================
// Forwarding implementations
impl<R: Read + ?Sized> Read for &mut R {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
(**self).read(buf)
}
#[inline]
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
(**self).read_vectored(bufs)
}
#[inline]
fn is_read_vectored(&self) -> bool {
(**self).is_read_vectored()
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
(**self).initializer()
}
#[cfg(feature="collections")]
#[inline]
fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_to_end(buf)
}
#[cfg(feature="collections")]
#[inline]
fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_to_string(buf)
}
#[inline]
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
(**self).read_exact(buf)
}
}
impl<W: Write + ?Sized> Write for &mut W {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
(**self).write(buf)
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
(**self).write_vectored(bufs)
}
#[inline]
fn is_write_vectored(&self) -> bool {
(**self).is_write_vectored()
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
(**self).flush()
}
#[inline]
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
(**self).write_all(buf)
}
#[inline]
fn write_fmt(&mut self, fmt: fmt::Arguments<'_>) -> io::Result<()> {
(**self).write_fmt(fmt)
}
}
impl<S: Seek + ?Sized> Seek for &mut S {
#[inline]
fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
(**self).seek(pos)
}
}
#[cfg(feature="collections")]
impl<B: BufRead + ?Sized> BufRead for &mut B {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> {
(**self).fill_buf()
}
#[inline]
fn consume(&mut self, amt: usize) {
(**self).consume(amt)
}
#[inline]
fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_until(byte, buf)
}
#[inline]
fn read_line(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_line(buf)
}
}
#[cfg(feature="alloc")]
impl<R: Read + ?Sized> Read for Box<R> {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
(**self).read(buf)
}
#[inline]
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
(**self).read_vectored(bufs)
}
#[inline]
fn is_read_vectored(&self) -> bool {
(**self).is_read_vectored()
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
(**self).initializer()
}
#[cfg(feature="collections")]
#[inline]
fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_to_end(buf)
}
#[cfg(feature="collections")]
#[inline]
fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_to_string(buf)
}
#[inline]
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
(**self).read_exact(buf)
}
}
#[cfg(feature="alloc")]
impl<W: Write + ?Sized> Write for Box<W> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
(**self).write(buf)
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
(**self).write_vectored(bufs)
}
#[inline]
fn is_write_vectored(&self) -> bool {
(**self).is_write_vectored()
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
(**self).flush()
}
#[inline]
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
(**self).write_all(buf)
}
#[inline]
fn write_fmt(&mut self, fmt: fmt::Arguments<'_>) -> io::Result<()> {
(**self).write_fmt(fmt)
}
}
#[cfg(feature="alloc")]
impl<S: Seek + ?Sized> Seek for Box<S> {
#[inline]
fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
(**self).seek(pos)
}
}
#[cfg(feature="collections")]
impl<B: BufRead + ?Sized> BufRead for Box<B> {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> {
(**self).fill_buf()
}
#[inline]
fn consume(&mut self, amt: usize) {
(**self).consume(amt)
}
#[inline]
fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_until(byte, buf)
}
#[inline]
fn read_line(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_line(buf)
}
}
// Used by panicking::default_hook
#[cfg(test)]
/// This impl is only used by printing logic, so any error returned is always
/// of kind `Other`, and should be ignored.
impl Write for Box<dyn (::realstd::io::Write) + Send> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
(**self).write(buf).map_err(|_| ErrorKind::Other.into())
}
fn flush(&mut self) -> io::Result<()> {
(**self).flush().map_err(|_| ErrorKind::Other.into())
}
}
// =============================================================================
// In-memory buffer implementations
/// Read is implemented for `&[u8]` by copying from the slice.
///
/// Note that reading updates the slice to point to the yet unread part.
/// The slice will be empty when EOF is reached.
impl Read for &[u8] {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
let amt = cmp::min(buf.len(), self.len());
let (a, b) = self.split_at(amt);
// First check if the amount of bytes we want to read is small:
// `copy_from_slice` will generally expand to a call to `memcpy`, and
// for a single byte the overhead is significant.
if amt == 1 {
buf[0] = a[0];
} else {
buf[..amt].copy_from_slice(a);
}
*self = b;
Ok(amt)
}
#[inline]
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
let mut nread = 0;
for buf in bufs {
nread += self.read(buf)?;
if self.is_empty() {
break;
}
}
Ok(nread)
}
#[inline]
fn is_read_vectored(&self) -> bool {
true
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
#[inline]
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
if buf.len() > self.len() {
return Err(Error::new(ErrorKind::UnexpectedEof, "failed to fill whole buffer"));
}
let (a, b) = self.split_at(buf.len());
// First check if the amount of bytes we want to read is small:
// `copy_from_slice` will generally expand to a call to `memcpy`, and
// for a single byte the overhead is significant.
if buf.len() == 1 {
buf[0] = a[0];
} else {
buf.copy_from_slice(a);
}
*self = b;
Ok(())
}
#[cfg(feature="collections")]
#[inline]
fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
buf.extend_from_slice(*self);
let len = self.len();
*self = &self[len..];
Ok(len)
}
}
#[cfg(feature="collections")]
impl BufRead for &[u8] {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> {
Ok(*self)
}
#[inline]
fn consume(&mut self, amt: usize) {
*self = &self[amt..];
}
}
/// Write is implemented for `&mut [u8]` by copying into the slice, overwriting
/// its data.
///
/// Note that writing updates the slice to point to the yet unwritten part.
/// The slice will be empty when it has been completely overwritten.
impl Write for &mut [u8] {
#[inline]
fn write(&mut self, data: &[u8]) -> io::Result<usize> {
let amt = cmp::min(data.len(), self.len());
let (a, b) = mem::replace(self, &mut []).split_at_mut(amt);
a.copy_from_slice(&data[..amt]);
*self = b;
Ok(amt)
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
let mut nwritten = 0;
for buf in bufs {
nwritten += self.write(buf)?;
if self.is_empty() {
break;
}
}
Ok(nwritten)
}
#[inline]
fn is_write_vectored(&self) -> bool {
true
}
#[inline]
fn write_all(&mut self, data: &[u8]) -> io::Result<()> {
if self.write(data)? == data.len() {
Ok(())
} else {
Err(Error::new(ErrorKind::WriteZero, "failed to write whole buffer"))
}
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
/// Write is implemented for `Vec<u8>` by appending to the vector.
/// The vector will grow as needed.
#[cfg(feature="collections")]
impl Write for Vec<u8> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
self.extend_from_slice(buf);
Ok(buf.len())
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
let len = bufs.iter().map(|b| b.len()).sum();
self.reserve(len);
for buf in bufs {
self.extend_from_slice(buf);
}
Ok(len)
}
#[inline]
fn is_write_vectored(&self) -> bool {
true
}
#[inline]
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
self.extend_from_slice(buf);
Ok(())
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
#[cfg(test)]
mod tests {
use crate::io::prelude::*;
#[bench]
fn bench_read_slice(b: &mut test::Bencher) {
let buf = [5; 1024];
let mut dst = [0; 128];
b.iter(|| {
let mut rd = &buf[..];
for _ in 0..8 {
let _ = rd.read(&mut dst);
test::black_box(&dst);
}
})
}
#[bench]
fn bench_write_slice(b: &mut test::Bencher) {
let mut buf = [0; 1024];
let src = [5; 128];
b.iter(|| {
let mut wr = &mut buf[..];
for _ in 0..8 {
let _ = wr.write_all(&src);
test::black_box(&wr);
}
})
}
#[bench]
fn bench_read_vec(b: &mut test::Bencher) {
let buf = vec![5; 1024];
let mut dst = [0; 128];
b.iter(|| {
let mut rd = &buf[..];
for _ in 0..8 {
let _ = rd.read(&mut dst);
test::black_box(&dst);
}
})
}
#[bench]
fn bench_write_vec(b: &mut test::Bencher) {
let mut buf = Vec::with_capacity(1024);
let src = [5; 128];
b.iter(|| {
let mut wr = &mut buf[..];
for _ in 0..8 {
let _ = wr.write_all(&src);
test::black_box(&wr);
}
})
}
}

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//! The I/O Prelude
//!
//! The purpose of this module is to alleviate imports of many common I/O traits
//! by adding a glob import to the top of I/O heavy modules:
//!
//! ```
//! # #![allow(unused_imports)]
//! use std::io::prelude::*;
//! ```
pub use super::{Read, Seek, Write};
#[cfg(feature="collections")] pub use super::BufRead;
#[cfg(feature="collections")] pub use alloc::boxed::Box;
#[cfg(feature="collections")] pub use collections::vec::Vec;

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#![allow(missing_copy_implementations)]
use core::fmt;
use crate::io::{self, ErrorKind, Initializer, IoSlice, IoSliceMut, Read, Write};
#[cfg(feature="collections")] use crate::io::BufRead;
use core::mem::MaybeUninit;
/// Copies the entire contents of a reader into a writer.
///
/// This function will continuously read data from `reader` and then
/// write it into `writer` in a streaming fashion until `reader`
/// returns EOF.
///
/// On success, the total number of bytes that were copied from
/// `reader` to `writer` is returned.
///
/// If youre wanting to copy the contents of one file to another and youre
/// working with filesystem paths, see the [`fs::copy`] function.
///
/// [`fs::copy`]: ../fs/fn.copy.html
///
/// # Errors
///
/// This function will return an error immediately if any call to `read` or
/// `write` returns an error. All instances of `ErrorKind::Interrupted` are
/// handled by this function and the underlying operation is retried.
///
/// # Examples
///
/// ```
/// use std::io;
///
/// fn main() -> io::Result<()> {
/// let mut reader: &[u8] = b"hello";
/// let mut writer: Vec<u8> = vec![];
///
/// io::copy(&mut reader, &mut writer)?;
///
/// assert_eq!(&b"hello"[..], &writer[..]);
/// Ok(())
/// }
/// ```
pub fn copy<R: ?Sized, W: ?Sized>(reader: &mut R, writer: &mut W) -> io::Result<u64>
where
R: Read,
W: Write,
{
let mut buf = MaybeUninit::<[u8; super::DEFAULT_BUF_SIZE]>::uninit();
// FIXME(#53491): This is calling `get_mut` and `get_ref` on an uninitialized
// `MaybeUninit`. Revisit this once we decided whether that is valid or not.
// This is still technically undefined behavior due to creating a reference
// to uninitialized data, but within libstd we can rely on more guarantees
// than if this code were in an external lib.
unsafe {
reader.initializer().initialize(buf.get_mut());
}
let mut written = 0;
loop {
let len = match reader.read(unsafe { buf.get_mut() }) {
Ok(0) => return Ok(written),
Ok(len) => len,
Err(ref e) if e.kind() == ErrorKind::Interrupted => continue,
Err(e) => return Err(e),
};
writer.write_all(unsafe { &buf.get_ref()[..len] })?;
written += len as u64;
}
}
/// A reader which is always at EOF.
///
/// This struct is generally created by calling [`empty`]. Please see
/// the documentation of [`empty()`][`empty`] for more details.
///
/// [`empty`]: fn.empty.html
pub struct Empty {
_priv: (),
}
/// Constructs a new handle to an empty reader.
///
/// All reads from the returned reader will return [`Ok`]`(0)`.
///
/// [`Ok`]: ../result/enum.Result.html#variant.Ok
///
/// # Examples
///
/// A slightly sad example of not reading anything into a buffer:
///
/// ```
/// use std::io::{self, Read};
///
/// let mut buffer = String::new();
/// io::empty().read_to_string(&mut buffer).unwrap();
/// assert!(buffer.is_empty());
/// ```
pub fn empty() -> Empty {
Empty { _priv: () }
}
impl Read for Empty {
#[inline]
fn read(&mut self, _buf: &mut [u8]) -> io::Result<usize> {
Ok(0)
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
}
#[cfg(feature="collections")]
impl BufRead for Empty {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> {
Ok(&[])
}
#[inline]
fn consume(&mut self, _n: usize) {}
}
impl fmt::Debug for Empty {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.pad("Empty { .. }")
}
}
/// A reader which yields one byte over and over and over and over and over and...
///
/// This struct is generally created by calling [`repeat`][repeat]. Please
/// see the documentation of `repeat()` for more details.
///
/// [repeat]: fn.repeat.html
pub struct Repeat {
byte: u8,
}
/// Creates an instance of a reader that infinitely repeats one byte.
///
/// All reads from this reader will succeed by filling the specified buffer with
/// the given byte.
///
/// # Examples
///
/// ```
/// use std::io::{self, Read};
///
/// let mut buffer = [0; 3];
/// io::repeat(0b101).read_exact(&mut buffer).unwrap();
/// assert_eq!(buffer, [0b101, 0b101, 0b101]);
/// ```
pub fn repeat(byte: u8) -> Repeat {
Repeat { byte }
}
impl Read for Repeat {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
for slot in &mut *buf {
*slot = self.byte;
}
Ok(buf.len())
}
#[inline]
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
let mut nwritten = 0;
for buf in bufs {
nwritten += self.read(buf)?;
}
Ok(nwritten)
}
#[inline]
fn is_read_vectored(&self) -> bool {
true
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
}
impl fmt::Debug for Repeat {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.pad("Repeat { .. }")
}
}
/// A writer which will move data into the void.
///
/// This struct is generally created by calling [`sink`][sink]. Please
/// see the documentation of `sink()` for more details.
///
/// [sink]: fn.sink.html
pub struct Sink {
_priv: (),
}
/// Creates an instance of a writer which will successfully consume all data.
///
/// All calls to `write` on the returned instance will return `Ok(buf.len())`
/// and the contents of the buffer will not be inspected.
///
/// # Examples
///
/// ```rust
/// use std::io::{self, Write};
///
/// let buffer = vec![1, 2, 3, 5, 8];
/// let num_bytes = io::sink().write(&buffer).unwrap();
/// assert_eq!(num_bytes, 5);
/// ```
pub fn sink() -> Sink {
Sink { _priv: () }
}
impl Write for Sink {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
Ok(buf.len())
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
let total_len = bufs.iter().map(|b| b.len()).sum();
Ok(total_len)
}
#[inline]
fn is_write_vectored(&self) -> bool {
true
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
impl fmt::Debug for Sink {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.pad("Sink { .. }")
}
}
#[cfg(test)]
mod tests {
use crate::io::prelude::*;
use crate::io::{copy, empty, repeat, sink};
#[test]
fn copy_copies() {
let mut r = repeat(0).take(4);
let mut w = sink();
assert_eq!(copy(&mut r, &mut w).unwrap(), 4);
let mut r = repeat(0).take(1 << 17);
assert_eq!(copy(&mut r as &mut dyn Read, &mut w as &mut dyn Write).unwrap(), 1 << 17);
}
#[test]
fn sink_sinks() {
let mut s = sink();
assert_eq!(s.write(&[]).unwrap(), 0);
assert_eq!(s.write(&[0]).unwrap(), 1);
assert_eq!(s.write(&[0; 1024]).unwrap(), 1024);
assert_eq!(s.by_ref().write(&[0; 1024]).unwrap(), 1024);
}
#[test]
fn empty_reads() {
let mut e = empty();
assert_eq!(e.read(&mut []).unwrap(), 0);
assert_eq!(e.read(&mut [0]).unwrap(), 0);
assert_eq!(e.read(&mut [0; 1024]).unwrap(), 0);
assert_eq!(e.by_ref().read(&mut [0; 1024]).unwrap(), 0);
}
#[test]
fn repeat_repeats() {
let mut r = repeat(4);
let mut b = [0; 1024];
assert_eq!(r.read(&mut b).unwrap(), 1024);
assert!(b.iter().all(|b| *b == 4));
}
#[test]
fn take_some_bytes() {
assert_eq!(repeat(4).take(100).bytes().count(), 100);
assert_eq!(repeat(4).take(100).bytes().next().unwrap().unwrap(), 4);
assert_eq!(repeat(1).take(10).chain(repeat(2).take(10)).bytes().count(), 20);
}
}

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// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use io::prelude::*;
#[cfg(feature="collections")] use core::convert::TryInto;
use core::cmp;
use io::{self, Initializer, SeekFrom, Error, ErrorKind};
/// A `Cursor` wraps an in-memory buffer and provides it with a
/// [`Seek`] implementation.
///
/// `Cursor`s are used with in-memory buffers, anything implementing
/// `AsRef<[u8]>`, to allow them to implement [`Read`] and/or [`Write`],
/// allowing these buffers to be used anywhere you might use a reader or writer
/// that does actual I/O.
///
/// The standard library implements some I/O traits on various types which
/// are commonly used as a buffer, like `Cursor<`[`Vec`]`<u8>>` and
/// `Cursor<`[`&[u8]`][bytes]`>`.
///
/// # Examples
///
/// We may want to write bytes to a [`File`] in our production
/// code, but use an in-memory buffer in our tests. We can do this with
/// `Cursor`:
///
/// [`Seek`]: trait.Seek.html
/// [`Read`]: ../../std/io/trait.Read.html
/// [`Write`]: ../../std/io/trait.Write.html
/// [`Vec`]: ../../std/vec/struct.Vec.html
/// [bytes]: ../../std/primitive.slice.html
/// [`File`]: ../fs/struct.File.html
///
/// ```no_run
/// use std::io::prelude::*;
/// use std::io::{self, SeekFrom};
/// use std::fs::File;
///
/// // a library function we've written
/// fn write_ten_bytes_at_end<W: Write + Seek>(writer: &mut W) -> io::Result<()> {
/// writer.seek(SeekFrom::End(-10))?;
///
/// for i in 0..10 {
/// writer.write(&[i])?;
/// }
///
/// // all went well
/// Ok(())
/// }
///
/// # fn foo() -> io::Result<()> {
/// // Here's some code that uses this library function.
/// //
/// // We might want to use a BufReader here for efficiency, but let's
/// // keep this example focused.
/// let mut file = File::create("foo.txt")?;
///
/// write_ten_bytes_at_end(&mut file)?;
/// # Ok(())
/// # }
///
/// // now let's write a test
/// #[test]
/// fn test_writes_bytes() {
/// // setting up a real File is much slower than an in-memory buffer,
/// // let's use a cursor instead
/// use std::io::Cursor;
/// let mut buff = Cursor::new(vec![0; 15]);
///
/// write_ten_bytes_at_end(&mut buff).unwrap();
///
/// assert_eq!(&buff.get_ref()[5..15], &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
/// }
/// ```
#[derive(Clone, Debug)]
pub struct Cursor<T> {
inner: T,
pos: u64,
}
impl<T> Cursor<T> {
/// Creates a new cursor wrapping the provided underlying in-memory buffer.
///
/// Cursor initial position is `0` even if underlying buffer (e.g. `Vec`)
/// is not empty. So writing to cursor starts with overwriting `Vec`
/// content, not with appending to it.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
/// ```
pub fn new(inner: T) -> Cursor<T> {
Cursor { pos: 0, inner: inner }
}
/// Consumes this cursor, returning the underlying value.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
///
/// let vec = buff.into_inner();
/// ```
pub fn into_inner(self) -> T { self.inner }
/// Gets a reference to the underlying value in this cursor.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
///
/// let reference = buff.get_ref();
/// ```
pub fn get_ref(&self) -> &T { &self.inner }
/// Gets a mutable reference to the underlying value in this cursor.
///
/// Care should be taken to avoid modifying the internal I/O state of the
/// underlying value as it may corrupt this cursor's position.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let mut buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
///
/// let reference = buff.get_mut();
/// ```
pub fn get_mut(&mut self) -> &mut T { &mut self.inner }
/// Returns the current position of this cursor.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
/// use std::io::prelude::*;
/// use std::io::SeekFrom;
///
/// let mut buff = Cursor::new(vec![1, 2, 3, 4, 5]);
///
/// assert_eq!(buff.position(), 0);
///
/// buff.seek(SeekFrom::Current(2)).unwrap();
/// assert_eq!(buff.position(), 2);
///
/// buff.seek(SeekFrom::Current(-1)).unwrap();
/// assert_eq!(buff.position(), 1);
/// ```
pub fn position(&self) -> u64 { self.pos }
/// Sets the position of this cursor.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let mut buff = Cursor::new(vec![1, 2, 3, 4, 5]);
///
/// assert_eq!(buff.position(), 0);
///
/// buff.set_position(2);
/// assert_eq!(buff.position(), 2);
///
/// buff.set_position(4);
/// assert_eq!(buff.position(), 4);
/// ```
pub fn set_position(&mut self, pos: u64) { self.pos = pos; }
}
impl<T> io::Seek for Cursor<T> where T: AsRef<[u8]> {
fn seek(&mut self, style: SeekFrom) -> io::Result<u64> {
let (base_pos, offset) = match style {
SeekFrom::Start(n) => { self.pos = n; return Ok(n); }
SeekFrom::End(n) => (self.inner.as_ref().len() as u64, n),
SeekFrom::Current(n) => (self.pos, n),
};
let new_pos = if offset >= 0 {
base_pos.checked_add(offset as u64)
} else {
base_pos.checked_sub((offset.wrapping_neg()) as u64)
};
match new_pos {
Some(n) => {self.pos = n; Ok(self.pos)}
None => Err(Error::new(ErrorKind::InvalidInput,
"invalid seek to a negative or overflowing position"))
}
}
}
impl<T> Read for Cursor<T> where T: AsRef<[u8]> {
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
let n = Read::read(&mut self.get_buf()?, buf)?;
self.pos += n as u64;
Ok(n)
}
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
let n = buf.len();
Read::read_exact(&mut self.get_buf()?, buf)?;
self.pos += n as u64;
Ok(())
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
}
impl<T> Cursor<T> where T: AsRef<[u8]> {
fn get_buf(&mut self) -> io::Result<&[u8]> {
let amt = cmp::min(self.pos, self.inner.as_ref().len() as u64);
Ok(&self.inner.as_ref()[(amt as usize)..])
}
}
#[cfg(feature="collections")]
impl<T> BufRead for Cursor<T> where T: AsRef<[u8]> {
fn fill_buf(&mut self) -> io::Result<&[u8]> { self.get_buf() }
fn consume(&mut self, amt: usize) { self.pos += amt as u64; }
}
// Non-resizing write implementation
fn slice_write(pos_mut: &mut u64, slice: &mut [u8], buf: &[u8]) -> io::Result<usize> {
let pos = cmp::min(*pos_mut, slice.len() as u64);
let amt = (&mut slice[(pos as usize)..]).write(buf)?;
*pos_mut += amt as u64;
Ok(amt)
}
// Resizing write implementation
#[cfg(feature="collections")]
fn vec_write(pos_mut: &mut u64, vec: &mut Vec<u8>, buf: &[u8]) -> io::Result<usize> {
let pos: usize = (*pos_mut).try_into().map_err(|_| {
Error::new(ErrorKind::InvalidInput,
"cursor position exceeds maximum possible vector length")
})?;
// Make sure the internal buffer is as least as big as where we
// currently are
let len = vec.len();
if len < pos {
// use `resize` so that the zero filling is as efficient as possible
vec.resize(pos, 0);
}
// Figure out what bytes will be used to overwrite what's currently
// there (left), and what will be appended on the end (right)
{
let space = vec.len() - pos;
let (left, right) = buf.split_at(cmp::min(space, buf.len()));
vec[pos..pos + left.len()].copy_from_slice(left);
vec.extend_from_slice(right);
}
// Bump us forward
*pos_mut = (pos + buf.len()) as u64;
Ok(buf.len())
}
impl<'a> Write for Cursor<&'a mut [u8]> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
slice_write(&mut self.pos, self.inner, buf)
}
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
#[cfg(feature="collections")]
impl<'a> Write for Cursor<&'a mut Vec<u8>> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
vec_write(&mut self.pos, self.inner, buf)
}
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
#[cfg(feature = "collections")]
impl Write for Cursor<Vec<u8>> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
vec_write(&mut self.pos, &mut self.inner, buf)
}
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
#[cfg(feature = "alloc")]
impl Write for Cursor<::alloc::boxed::Box<[u8]>> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
slice_write(&mut self.pos, &mut self.inner, buf)
}
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
#[cfg(test)]
mod tests {
use io::prelude::*;
use io::{Cursor, SeekFrom};
#[test]
fn test_vec_writer() {
let mut writer = Vec::new();
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7];
assert_eq!(writer, b);
}
#[test]
fn test_mem_writer() {
let mut writer = Cursor::new(Vec::new());
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
}
#[test]
fn test_mem_mut_writer() {
let mut vec = Vec::new();
let mut writer = Cursor::new(&mut vec);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
}
#[test]
fn test_box_slice_writer() {
let mut writer = Cursor::new(vec![0u8; 9].into_boxed_slice());
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[]).unwrap(), 0);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[8, 9]).unwrap(), 1);
assert_eq!(writer.write(&[10]).unwrap(), 0);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8];
assert_eq!(&**writer.get_ref(), b);
}
#[test]
fn test_buf_writer() {
let mut buf = [0 as u8; 9];
{
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[]).unwrap(), 0);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[8, 9]).unwrap(), 1);
assert_eq!(writer.write(&[10]).unwrap(), 0);
}
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8];
assert_eq!(buf, b);
}
#[test]
fn test_buf_writer_seek() {
let mut buf = [0 as u8; 8];
{
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[1]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.seek(SeekFrom::Start(2)).unwrap(), 2);
assert_eq!(writer.position(), 2);
assert_eq!(writer.write(&[2]).unwrap(), 1);
assert_eq!(writer.position(), 3);
assert_eq!(writer.seek(SeekFrom::Current(-2)).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[3]).unwrap(), 1);
assert_eq!(writer.position(), 2);
assert_eq!(writer.seek(SeekFrom::End(-1)).unwrap(), 7);
assert_eq!(writer.position(), 7);
assert_eq!(writer.write(&[4]).unwrap(), 1);
assert_eq!(writer.position(), 8);
}
let b: &[_] = &[1, 3, 2, 0, 0, 0, 0, 4];
assert_eq!(buf, b);
}
#[test]
fn test_buf_writer_error() {
let mut buf = [0 as u8; 2];
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[0, 0]).unwrap(), 1);
assert_eq!(writer.write(&[0, 0]).unwrap(), 0);
}
#[test]
fn test_mem_reader() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7]);
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.position(), 5);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(buf, b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_boxed_slice_reader() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7].into_boxed_slice());
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.position(), 5);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(buf, b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn read_to_end() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7]);
let mut v = Vec::new();
reader.read_to_end(&mut v).unwrap();
assert_eq!(v, [0, 1, 2, 3, 4, 5, 6, 7]);
}
#[test]
fn test_slice_reader() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let reader = &mut &in_buf[..];
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.len(), 7);
let b: &[_] = &[0];
assert_eq!(&buf[..], b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.len(), 3);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(&buf[..], b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_read_exact() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let reader = &mut &in_buf[..];
let mut buf = [];
assert!(reader.read_exact(&mut buf).is_ok());
let mut buf = [8];
assert!(reader.read_exact(&mut buf).is_ok());
assert_eq!(buf[0], 0);
assert_eq!(reader.len(), 7);
let mut buf = [0, 0, 0, 0, 0, 0, 0];
assert!(reader.read_exact(&mut buf).is_ok());
assert_eq!(buf, [1, 2, 3, 4, 5, 6, 7]);
assert_eq!(reader.len(), 0);
let mut buf = [0];
assert!(reader.read_exact(&mut buf).is_err());
}
#[test]
fn test_buf_reader() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let mut reader = Cursor::new(&in_buf[..]);
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.position(), 5);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(buf, b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn seek_past_end() {
let buf = [0xff];
let mut r = Cursor::new(&buf[..]);
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.read(&mut [0]).unwrap(), 0);
let mut r = Cursor::new(vec![10]);
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.read(&mut [0]).unwrap(), 0);
let mut buf = [0];
let mut r = Cursor::new(&mut buf[..]);
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.write(&[3]).unwrap(), 0);
let mut r = Cursor::new(vec![10].into_boxed_slice());
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.write(&[3]).unwrap(), 0);
}
#[test]
fn seek_past_i64() {
let buf = [0xff];
let mut r = Cursor::new(&buf[..]);
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
let mut r = Cursor::new(vec![10]);
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
let mut buf = [0];
let mut r = Cursor::new(&mut buf[..]);
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
let mut r = Cursor::new(vec![10].into_boxed_slice());
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
}
#[test]
fn seek_before_0() {
let buf = [0xff];
let mut r = Cursor::new(&buf[..]);
assert!(r.seek(SeekFrom::End(-2)).is_err());
let mut r = Cursor::new(vec![10]);
assert!(r.seek(SeekFrom::End(-2)).is_err());
let mut buf = [0];
let mut r = Cursor::new(&mut buf[..]);
assert!(r.seek(SeekFrom::End(-2)).is_err());
let mut r = Cursor::new(vec![10].into_boxed_slice());
assert!(r.seek(SeekFrom::End(-2)).is_err());
}
#[test]
fn test_seekable_mem_writer() {
let mut writer = Cursor::new(Vec::<u8>::new());
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.position(), 8);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::Start(0)).unwrap(), 0);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[3, 4]).unwrap(), 2);
let b: &[_] = &[3, 4, 2, 3, 4, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::Current(1)).unwrap(), 3);
assert_eq!(writer.write(&[0, 1]).unwrap(), 2);
let b: &[_] = &[3, 4, 2, 0, 1, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::End(-1)).unwrap(), 7);
assert_eq!(writer.write(&[1, 2]).unwrap(), 2);
let b: &[_] = &[3, 4, 2, 0, 1, 5, 6, 1, 2];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::End(1)).unwrap(), 10);
assert_eq!(writer.write(&[1]).unwrap(), 1);
let b: &[_] = &[3, 4, 2, 0, 1, 5, 6, 1, 2, 0, 1];
assert_eq!(&writer.get_ref()[..], b);
}
#[test]
fn vec_seek_past_end() {
let mut r = Cursor::new(Vec::new());
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.write(&[3]).unwrap(), 1);
}
#[test]
fn vec_seek_before_0() {
let mut r = Cursor::new(Vec::new());
assert!(r.seek(SeekFrom::End(-2)).is_err());
}
#[test]
#[cfg(target_pointer_width = "32")]
fn vec_seek_and_write_past_usize_max() {
let mut c = Cursor::new(Vec::new());
c.set_position(<usize>::max_value() as u64 + 1);
assert!(c.write_all(&[1, 2, 3]).is_err());
}
}

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@ -0,0 +1,558 @@
// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
#[cfg(feature="alloc")] use alloc::boxed::Box;
#[cfg(not(feature="alloc"))] use ::FakeBox as Box;
use core::convert::Into;
use core::fmt;
use core::marker::{Send, Sync};
use core::option::Option::{self, Some, None};
use core::result;
#[cfg(feature="collections")] use collections::string::String;
#[cfg(not(feature="collections"))] use ::ErrorString as String;
use core::convert::From;
/// A specialized [`Result`](../result/enum.Result.html) type for I/O
/// operations.
///
/// This type is broadly used across [`std::io`] for any operation which may
/// produce an error.
///
/// This typedef is generally used to avoid writing out [`io::Error`] directly and
/// is otherwise a direct mapping to [`Result`].
///
/// While usual Rust style is to import types directly, aliases of [`Result`]
/// often are not, to make it easier to distinguish between them. [`Result`] is
/// generally assumed to be [`std::result::Result`][`Result`], and so users of this alias
/// will generally use `io::Result` instead of shadowing the prelude's import
/// of [`std::result::Result`][`Result`].
///
/// [`std::io`]: ../io/index.html
/// [`io::Error`]: ../io/struct.Error.html
/// [`Result`]: ../result/enum.Result.html
///
/// # Examples
///
/// A convenience function that bubbles an `io::Result` to its caller:
///
/// ```
/// use std::io;
///
/// fn get_string() -> io::Result<String> {
/// let mut buffer = String::new();
///
/// io::stdin().read_line(&mut buffer)?;
///
/// Ok(buffer)
/// }
/// ```
pub type Result<T> = result::Result<T, Error>;
/// The error type for I/O operations of the [`Read`], [`Write`], [`Seek`], and
/// associated traits.
///
/// Errors mostly originate from the underlying OS, but custom instances of
/// `Error` can be created with crafted error messages and a particular value of
/// [`ErrorKind`].
///
/// [`Read`]: ../io/trait.Read.html
/// [`Write`]: ../io/trait.Write.html
/// [`Seek`]: ../io/trait.Seek.html
/// [`ErrorKind`]: enum.ErrorKind.html
pub struct Error {
repr: Repr,
}
impl fmt::Debug for Error {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
fmt::Debug::fmt(&self.repr, f)
}
}
enum Repr {
Os(i32),
Simple(ErrorKind),
#[cfg(feature="alloc")]
Custom(Box<Custom>),
#[cfg(not(feature="alloc"))]
Custom(Custom),
}
#[derive(Debug)]
struct Custom {
kind: ErrorKind,
error: String,
}
/// A list specifying general categories of I/O error.
///
/// This list is intended to grow over time and it is not recommended to
/// exhaustively match against it.
///
/// It is used with the [`io::Error`] type.
///
/// [`io::Error`]: struct.Error.html
#[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
#[allow(deprecated)]
#[non_exhaustive]
pub enum ErrorKind {
/// An entity was not found, often a file.
NotFound,
/// The operation lacked the necessary privileges to complete.
PermissionDenied,
/// The connection was refused by the remote server.
ConnectionRefused,
/// The connection was reset by the remote server.
ConnectionReset,
/// The connection was aborted (terminated) by the remote server.
ConnectionAborted,
/// The network operation failed because it was not connected yet.
NotConnected,
/// A socket address could not be bound because the address is already in
/// use elsewhere.
AddrInUse,
/// A nonexistent interface was requested or the requested address was not
/// local.
AddrNotAvailable,
/// The operation failed because a pipe was closed.
BrokenPipe,
/// An entity already exists, often a file.
AlreadyExists,
/// The operation needs to block to complete, but the blocking operation was
/// requested to not occur.
WouldBlock,
/// A parameter was incorrect.
InvalidInput,
/// Data not valid for the operation were encountered.
///
/// Unlike [`InvalidInput`], this typically means that the operation
/// parameters were valid, however the error was caused by malformed
/// input data.
///
/// For example, a function that reads a file into a string will error with
/// `InvalidData` if the file's contents are not valid UTF-8.
///
/// [`InvalidInput`]: #variant.InvalidInput
InvalidData,
/// The I/O operation's timeout expired, causing it to be canceled.
TimedOut,
/// An error returned when an operation could not be completed because a
/// call to [`write`] returned [`Ok(0)`].
///
/// This typically means that an operation could only succeed if it wrote a
/// particular number of bytes but only a smaller number of bytes could be
/// written.
///
/// [`write`]: ../../std/io/trait.Write.html#tymethod.write
/// [`Ok(0)`]: ../../std/io/type.Result.html
WriteZero,
/// This operation was interrupted.
///
/// Interrupted operations can typically be retried.
Interrupted,
/// Any I/O error not part of this list.
Other,
/// An error returned when an operation could not be completed because an
/// "end of file" was reached prematurely.
///
/// This typically means that an operation could only succeed if it read a
/// particular number of bytes but only a smaller number of bytes could be
/// read.
UnexpectedEof,
}
impl ErrorKind {
fn as_str(&self) -> &'static str {
match *self {
ErrorKind::NotFound => "entity not found",
ErrorKind::PermissionDenied => "permission denied",
ErrorKind::ConnectionRefused => "connection refused",
ErrorKind::ConnectionReset => "connection reset",
ErrorKind::ConnectionAborted => "connection aborted",
ErrorKind::NotConnected => "not connected",
ErrorKind::AddrInUse => "address in use",
ErrorKind::AddrNotAvailable => "address not available",
ErrorKind::BrokenPipe => "broken pipe",
ErrorKind::AlreadyExists => "entity already exists",
ErrorKind::WouldBlock => "operation would block",
ErrorKind::InvalidInput => "invalid input parameter",
ErrorKind::InvalidData => "invalid data",
ErrorKind::TimedOut => "timed out",
ErrorKind::WriteZero => "write zero",
ErrorKind::Interrupted => "operation interrupted",
ErrorKind::Other => "other os error",
ErrorKind::UnexpectedEof => "unexpected end of file",
}
}
}
/// Intended for use for errors not exposed to the user, where allocating onto
/// the heap (for normal construction via Error::new) is too costly.
impl From<ErrorKind> for Error {
#[inline]
fn from(kind: ErrorKind) -> Error {
Error {
repr: Repr::Simple(kind)
}
}
}
impl Error {
/// Creates a new I/O error from a known kind of error as well as an
/// arbitrary error payload.
///
/// This function is used to generically create I/O errors which do not
/// originate from the OS itself. The `error` argument is an arbitrary
/// payload which will be contained in this `Error`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// // errors can be created from strings
/// let custom_error = Error::new(ErrorKind::Other, "oh no!");
///
/// // errors can also be created from other errors
/// let custom_error2 = Error::new(ErrorKind::Interrupted, custom_error);
/// ```
pub fn new<E>(kind: ErrorKind, error: E) -> Error
where E: Into<String>
{
Self::_new(kind, error.into())
}
fn _new(kind: ErrorKind, error: String) -> Error {
Error {
repr: Repr::Custom(Box::new(Custom {
kind,
error,
}))
}
}
/// Creates a new instance of an `Error` from a particular OS error code.
///
/// # Examples
///
/// On Linux:
///
/// ```
/// # if cfg!(target_os = "linux") {
/// use std::io;
///
/// let error = io::Error::from_raw_os_error(22);
/// assert_eq!(error.kind(), io::ErrorKind::InvalidInput);
/// # }
/// ```
///
/// On Windows:
///
/// ```
/// # if cfg!(windows) {
/// use std::io;
///
/// let error = io::Error::from_raw_os_error(10022);
/// assert_eq!(error.kind(), io::ErrorKind::InvalidInput);
/// # }
/// ```
pub fn from_raw_os_error(code: i32) -> Error {
Error { repr: Repr::Os(code) }
}
/// Returns the OS error that this error represents (if any).
///
/// If this `Error` was constructed via `last_os_error` or
/// `from_raw_os_error`, then this function will return `Some`, otherwise
/// it will return `None`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_os_error(err: &Error) {
/// if let Some(raw_os_err) = err.raw_os_error() {
/// println!("raw OS error: {:?}", raw_os_err);
/// } else {
/// println!("Not an OS error");
/// }
/// }
///
/// fn main() {
/// // Will print "raw OS error: ...".
/// print_os_error(&Error::last_os_error());
/// // Will print "Not an OS error".
/// print_os_error(&Error::new(ErrorKind::Other, "oh no!"));
/// }
/// ```
pub fn raw_os_error(&self) -> Option<i32> {
match self.repr {
Repr::Os(i) => Some(i),
Repr::Custom(..) => None,
Repr::Simple(..) => None,
}
}
/// Returns a reference to the inner error wrapped by this error (if any).
///
/// If this `Error` was constructed via `new` then this function will
/// return `Some`, otherwise it will return `None`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_error(err: &Error) {
/// if let Some(inner_err) = err.get_ref() {
/// println!("Inner error: {:?}", inner_err);
/// } else {
/// println!("No inner error");
/// }
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(&Error::last_os_error());
/// // Will print "Inner error: ...".
/// print_error(&Error::new(ErrorKind::Other, "oh no!"));
/// }
/// ```
pub fn get_ref(&self) -> Option<&String> {
match self.repr {
Repr::Os(..) => None,
Repr::Simple(..) => None,
Repr::Custom(ref c) => Some(&c.error),
}
}
/// Returns a mutable reference to the inner error wrapped by this error
/// (if any).
///
/// If this `Error` was constructed via `new` then this function will
/// return `Some`, otherwise it will return `None`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
/// use std::{error, fmt};
/// use std::fmt::Display;
///
/// #[derive(Debug)]
/// struct MyError {
/// v: String,
/// }
///
/// impl MyError {
/// fn new() -> MyError {
/// MyError {
/// v: "oh no!".to_string()
/// }
/// }
///
/// fn change_message(&mut self, new_message: &str) {
/// self.v = new_message.to_string();
/// }
/// }
///
/// impl error::Error for MyError {
/// fn description(&self) -> &str { &self.v }
/// }
///
/// impl Display for MyError {
/// fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
/// write!(f, "MyError: {}", &self.v)
/// }
/// }
///
/// fn change_error(mut err: Error) -> Error {
/// if let Some(inner_err) = err.get_mut() {
/// inner_err.downcast_mut::<MyError>().unwrap().change_message("I've been changed!");
/// }
/// err
/// }
///
/// fn print_error(err: &Error) {
/// if let Some(inner_err) = err.get_ref() {
/// println!("Inner error: {}", inner_err);
/// } else {
/// println!("No inner error");
/// }
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(&change_error(Error::last_os_error()));
/// // Will print "Inner error: ...".
/// print_error(&change_error(Error::new(ErrorKind::Other, MyError::new())));
/// }
/// ```
pub fn get_mut(&mut self) -> Option<&mut String> {
match self.repr {
Repr::Os(..) => None,
Repr::Simple(..) => None,
Repr::Custom(ref mut c) => Some(&mut c.error),
}
}
/// Consumes the `Error`, returning its inner error (if any).
///
/// If this `Error` was constructed via `new` then this function will
/// return `Some`, otherwise it will return `None`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_error(err: Error) {
/// if let Some(inner_err) = err.into_inner() {
/// println!("Inner error: {}", inner_err);
/// } else {
/// println!("No inner error");
/// }
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(Error::last_os_error());
/// // Will print "Inner error: ...".
/// print_error(Error::new(ErrorKind::Other, "oh no!"));
/// }
/// ```
pub fn into_inner(self) -> Option<String> {
match self.repr {
Repr::Os(..) => None,
Repr::Simple(..) => None,
Repr::Custom(c) => Some(c.error)
}
}
/// Returns the corresponding `ErrorKind` for this error.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_error(err: Error) {
/// println!("{:?}", err.kind());
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(Error::last_os_error());
/// // Will print "Inner error: ...".
/// print_error(Error::new(ErrorKind::AddrInUse, "oh no!"));
/// }
/// ```
pub fn kind(&self) -> ErrorKind {
match self.repr {
Repr::Os(_code) => ErrorKind::Other,
Repr::Custom(ref c) => c.kind,
Repr::Simple(kind) => kind,
}
}
}
impl fmt::Debug for Repr {
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
match *self {
Repr::Os(code) =>
fmt.debug_struct("Os")
.field("code", &code).finish(),
Repr::Custom(ref c) => fmt::Debug::fmt(&c, fmt),
Repr::Simple(kind) => fmt.debug_tuple("Kind").field(&kind).finish(),
}
}
}
impl fmt::Display for Error {
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
match self.repr {
Repr::Os(code) => {
write!(fmt, "os error {}", code)
}
Repr::Custom(ref c) => c.error.fmt(fmt),
Repr::Simple(kind) => write!(fmt, "{}", kind.as_str()),
}
}
}
fn _assert_error_is_sync_send() {
fn _is_sync_send<T: Sync+Send>() {}
_is_sync_send::<Error>();
}
#[cfg(test)]
mod test {
use super::{Error, ErrorKind, Repr, Custom};
use error;
use fmt;
use sys::os::error_string;
use sys::decode_error_kind;
#[test]
fn test_debug_error() {
let code = 6;
let msg = error_string(code);
let kind = decode_error_kind(code);
let err = Error {
repr: Repr::Custom(box Custom {
kind: ErrorKind::InvalidInput,
error: box Error {
repr: super::Repr::Os(code)
},
})
};
let expected = format!(
"Custom {{ \
kind: InvalidInput, \
error: Os {{ \
code: {:?}, \
kind: {:?}, \
message: {:?} \
}} \
}}",
code, kind, msg
);
assert_eq!(format!("{:?}", err), expected);
}
#[test]
fn test_downcasting() {
#[derive(Debug)]
struct TestError;
impl fmt::Display for TestError {
fn fmt(&self, _: &mut fmt::Formatter) -> fmt::Result {
Ok(())
}
}
impl error::Error for TestError {
fn description(&self) -> &str {
"asdf"
}
}
// we have to call all of these UFCS style right now since method
// resolution won't implicitly drop the Send+Sync bounds
let mut err = Error::new(ErrorKind::Other, TestError);
assert!(err.get_ref().unwrap().is::<TestError>());
assert_eq!("asdf", err.get_ref().unwrap().description());
assert!(err.get_mut().unwrap().is::<TestError>());
let extracted = err.into_inner().unwrap();
extracted.downcast::<TestError>().unwrap();
}
}

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@ -0,0 +1,341 @@
// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
#[cfg(feature="alloc")] use alloc::boxed::Box;
use core::cmp;
use io::{self, SeekFrom, Read, Initializer, Write, Seek, Error, ErrorKind};
#[cfg(feature="collections")] use io::BufRead;
use core::fmt;
use core::mem;
#[cfg(feature="collections")] use collections::string::String;
#[cfg(feature="collections")] use collections::vec::Vec;
// =============================================================================
// Forwarding implementations
impl<'a, R: Read + ?Sized> Read for &'a mut R {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
(**self).read(buf)
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
(**self).initializer()
}
#[cfg(feature="collections")]
#[inline]
fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_to_end(buf)
}
#[cfg(feature="collections")]
#[inline]
fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_to_string(buf)
}
#[inline]
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
(**self).read_exact(buf)
}
}
impl<'a, W: Write + ?Sized> Write for &'a mut W {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> { (**self).write(buf) }
#[inline]
fn flush(&mut self) -> io::Result<()> { (**self).flush() }
#[inline]
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
(**self).write_all(buf)
}
#[inline]
fn write_fmt(&mut self, fmt: fmt::Arguments) -> io::Result<()> {
(**self).write_fmt(fmt)
}
}
impl<'a, S: Seek + ?Sized> Seek for &'a mut S {
#[inline]
fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> { (**self).seek(pos) }
}
#[cfg(feature="collections")]
impl<'a, B: BufRead + ?Sized> BufRead for &'a mut B {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> { (**self).fill_buf() }
#[inline]
fn consume(&mut self, amt: usize) { (**self).consume(amt) }
#[inline]
fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_until(byte, buf)
}
#[inline]
fn read_line(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_line(buf)
}
}
#[cfg(feature="alloc")]
impl<R: Read + ?Sized> Read for Box<R> {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
(**self).read(buf)
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
(**self).initializer()
}
#[cfg(feature="collections")]
#[inline]
fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_to_end(buf)
}
#[cfg(feature="collections")]
#[inline]
fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_to_string(buf)
}
#[inline]
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
(**self).read_exact(buf)
}
}
#[cfg(feature="alloc")]
impl<W: Write + ?Sized> Write for Box<W> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> { (**self).write(buf) }
#[inline]
fn flush(&mut self) -> io::Result<()> { (**self).flush() }
#[inline]
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
(**self).write_all(buf)
}
#[inline]
fn write_fmt(&mut self, fmt: fmt::Arguments) -> io::Result<()> {
(**self).write_fmt(fmt)
}
}
#[cfg(feature="alloc")]
impl<S: Seek + ?Sized> Seek for Box<S> {
#[inline]
fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> { (**self).seek(pos) }
}
#[cfg(feature="collections")]
impl<B: BufRead + ?Sized> BufRead for Box<B> {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> { (**self).fill_buf() }
#[inline]
fn consume(&mut self, amt: usize) { (**self).consume(amt) }
#[inline]
fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_until(byte, buf)
}
#[inline]
fn read_line(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_line(buf)
}
}
// =============================================================================
// In-memory buffer implementations
/// Read is implemented for `&[u8]` by copying from the slice.
///
/// Note that reading updates the slice to point to the yet unread part.
/// The slice will be empty when EOF is reached.
impl<'a> Read for &'a [u8] {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
let amt = cmp::min(buf.len(), self.len());
let (a, b) = self.split_at(amt);
// First check if the amount of bytes we want to read is small:
// `copy_from_slice` will generally expand to a call to `memcpy`, and
// for a single byte the overhead is significant.
if amt == 1 {
buf[0] = a[0];
} else {
buf[..amt].copy_from_slice(a);
}
*self = b;
Ok(amt)
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
#[inline]
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
if buf.len() > self.len() {
return Err(Error::new(ErrorKind::UnexpectedEof,
"failed to fill whole buffer"));
}
let (a, b) = self.split_at(buf.len());
// First check if the amount of bytes we want to read is small:
// `copy_from_slice` will generally expand to a call to `memcpy`, and
// for a single byte the overhead is significant.
if buf.len() == 1 {
buf[0] = a[0];
} else {
buf.copy_from_slice(a);
}
*self = b;
Ok(())
}
#[cfg(feature="collections")]
#[inline]
fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
buf.extend_from_slice(*self);
let len = self.len();
*self = &self[len..];
Ok(len)
}
}
#[cfg(feature="collections")]
impl<'a> BufRead for &'a [u8] {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> { Ok(*self) }
#[inline]
fn consume(&mut self, amt: usize) { *self = &self[amt..]; }
}
/// Write is implemented for `&mut [u8]` by copying into the slice, overwriting
/// its data.
///
/// Note that writing updates the slice to point to the yet unwritten part.
/// The slice will be empty when it has been completely overwritten.
impl<'a> Write for &'a mut [u8] {
#[inline]
fn write(&mut self, data: &[u8]) -> io::Result<usize> {
let amt = cmp::min(data.len(), self.len());
let (a, b) = mem::replace(self, &mut []).split_at_mut(amt);
a.copy_from_slice(&data[..amt]);
*self = b;
Ok(amt)
}
#[inline]
fn write_all(&mut self, data: &[u8]) -> io::Result<()> {
if self.write(data)? == data.len() {
Ok(())
} else {
Err(Error::new(ErrorKind::WriteZero, "failed to write whole buffer"))
}
}
#[inline]
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
/// Write is implemented for `Vec<u8>` by appending to the vector.
/// The vector will grow as needed.
#[cfg(feature="collections")]
impl Write for Vec<u8> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
self.extend_from_slice(buf);
Ok(buf.len())
}
#[inline]
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
self.extend_from_slice(buf);
Ok(())
}
#[inline]
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
#[cfg(test)]
mod tests {
use io::prelude::*;
use test;
#[bench]
fn bench_read_slice(b: &mut test::Bencher) {
let buf = [5; 1024];
let mut dst = [0; 128];
b.iter(|| {
let mut rd = &buf[..];
for _ in 0..8 {
let _ = rd.read(&mut dst);
test::black_box(&dst);
}
})
}
#[bench]
fn bench_write_slice(b: &mut test::Bencher) {
let mut buf = [0; 1024];
let src = [5; 128];
b.iter(|| {
let mut wr = &mut buf[..];
for _ in 0..8 {
let _ = wr.write_all(&src);
test::black_box(&wr);
}
})
}
#[bench]
fn bench_read_vec(b: &mut test::Bencher) {
let buf = vec![5; 1024];
let mut dst = [0; 128];
b.iter(|| {
let mut rd = &buf[..];
for _ in 0..8 {
let _ = rd.read(&mut dst);
test::black_box(&dst);
}
})
}
#[bench]
fn bench_write_vec(b: &mut test::Bencher) {
let mut buf = Vec::with_capacity(1024);
let src = [5; 128];
b.iter(|| {
let mut wr = &mut buf[..];
for _ in 0..8 {
let _ = wr.write_all(&src);
test::black_box(&wr);
}
})
}
}

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// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//! The I/O Prelude
//!
//! The purpose of this module is to alleviate imports of many common I/O traits
//! by adding a glob import to the top of I/O heavy modules:
//!
//! ```
//! # #![allow(unused_imports)]
//! use std::io::prelude::*;
//! ```
pub use super::{Read, Write, Seek};
#[cfg(feature="collections")] pub use super::BufRead;
#[cfg(feature="collections")] pub use alloc::boxed::Box;
#[cfg(feature="collections")] pub use collections::vec::Vec;

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// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
#![allow(missing_copy_implementations)]
use core::fmt;
use io::{self, Read, Initializer, Write, ErrorKind};
use core::mem;
#[cfg(feature="collections")] use io::BufRead;
/// Copies the entire contents of a reader into a writer.
///
/// This function will continuously read data from `reader` and then
/// write it into `writer` in a streaming fashion until `reader`
/// returns EOF.
///
/// On success, the total number of bytes that were copied from
/// `reader` to `writer` is returned.
///
/// If youre wanting to copy the contents of one file to another and youre
/// working with filesystem paths, see the [`fs::copy`] function.
///
/// [`fs::copy`]: ../fs/fn.copy.html
///
/// # Errors
///
/// This function will return an error immediately if any call to `read` or
/// `write` returns an error. All instances of `ErrorKind::Interrupted` are
/// handled by this function and the underlying operation is retried.
///
/// # Examples
///
/// ```
/// use std::io;
///
/// fn main() -> io::Result<()> {
/// let mut reader: &[u8] = b"hello";
/// let mut writer: Vec<u8> = vec![];
///
/// io::copy(&mut reader, &mut writer)?;
///
/// assert_eq!(&b"hello"[..], &writer[..]);
/// Ok(())
/// }
/// ```
pub fn copy<R: ?Sized, W: ?Sized>(reader: &mut R, writer: &mut W) -> io::Result<u64>
where R: Read, W: Write
{
let mut buf = unsafe {
let mut buf: [u8; super::DEFAULT_BUF_SIZE] = mem::uninitialized();
reader.initializer().initialize(&mut buf);
buf
};
let mut written = 0;
loop {
let len = match reader.read(&mut buf) {
Ok(0) => return Ok(written),
Ok(len) => len,
Err(ref e) if e.kind() == ErrorKind::Interrupted => continue,
Err(e) => return Err(e),
};
writer.write_all(&buf[..len])?;
written += len as u64;
}
}
/// A reader which is always at EOF.
///
/// This struct is generally created by calling [`empty`]. Please see
/// the documentation of [`empty()`][`empty`] for more details.
///
/// [`empty`]: fn.empty.html
pub struct Empty { _priv: () }
/// Constructs a new handle to an empty reader.
///
/// All reads from the returned reader will return [`Ok`]`(0)`.
///
/// [`Ok`]: ../result/enum.Result.html#variant.Ok
///
/// # Examples
///
/// A slightly sad example of not reading anything into a buffer:
///
/// ```
/// use std::io::{self, Read};
///
/// let mut buffer = String::new();
/// io::empty().read_to_string(&mut buffer).unwrap();
/// assert!(buffer.is_empty());
/// ```
pub fn empty() -> Empty { Empty { _priv: () } }
impl Read for Empty {
#[inline]
fn read(&mut self, _buf: &mut [u8]) -> io::Result<usize> { Ok(0) }
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
}
#[cfg(feature="collections")]
impl BufRead for Empty {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> { Ok(&[]) }
#[inline]
fn consume(&mut self, _n: usize) {}
}
impl fmt::Debug for Empty {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.pad("Empty { .. }")
}
}
/// A reader which yields one byte over and over and over and over and over and...
///
/// This struct is generally created by calling [`repeat`][repeat]. Please
/// see the documentation of `repeat()` for more details.
///
/// [repeat]: fn.repeat.html
pub struct Repeat { byte: u8 }
/// Creates an instance of a reader that infinitely repeats one byte.
///
/// All reads from this reader will succeed by filling the specified buffer with
/// the given byte.
///
/// # Examples
///
/// ```
/// use std::io::{self, Read};
///
/// let mut buffer = [0; 3];
/// io::repeat(0b101).read_exact(&mut buffer).unwrap();
/// assert_eq!(buffer, [0b101, 0b101, 0b101]);
/// ```
pub fn repeat(byte: u8) -> Repeat { Repeat { byte: byte } }
impl Read for Repeat {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
for slot in &mut *buf {
*slot = self.byte;
}
Ok(buf.len())
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
}
impl fmt::Debug for Repeat {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.pad("Repeat { .. }")
}
}
/// A writer which will move data into the void.
///
/// This struct is generally created by calling [`sink`][sink]. Please
/// see the documentation of `sink()` for more details.
///
/// [sink]: fn.sink.html
pub struct Sink { _priv: () }
/// Creates an instance of a writer which will successfully consume all data.
///
/// All calls to `write` on the returned instance will return `Ok(buf.len())`
/// and the contents of the buffer will not be inspected.
///
/// # Examples
///
/// ```rust
/// use std::io::{self, Write};
///
/// let buffer = vec![1, 2, 3, 5, 8];
/// let num_bytes = io::sink().write(&buffer).unwrap();
/// assert_eq!(num_bytes, 5);
/// ```
pub fn sink() -> Sink { Sink { _priv: () } }
impl Write for Sink {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> { Ok(buf.len()) }
#[inline]
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
impl fmt::Debug for Sink {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.pad("Sink { .. }")
}
}
#[cfg(test)]
mod tests {
use io::prelude::*;
use io::{copy, sink, empty, repeat};
#[test]
fn copy_copies() {
let mut r = repeat(0).take(4);
let mut w = sink();
assert_eq!(copy(&mut r, &mut w).unwrap(), 4);
let mut r = repeat(0).take(1 << 17);
assert_eq!(copy(&mut r as &mut dyn Read, &mut w as &mut dyn Write).unwrap(), 1 << 17);
}
#[test]
fn sink_sinks() {
let mut s = sink();
assert_eq!(s.write(&[]).unwrap(), 0);
assert_eq!(s.write(&[0]).unwrap(), 1);
assert_eq!(s.write(&[0; 1024]).unwrap(), 1024);
assert_eq!(s.by_ref().write(&[0; 1024]).unwrap(), 1024);
}
#[test]
fn empty_reads() {
let mut e = empty();
assert_eq!(e.read(&mut []).unwrap(), 0);
assert_eq!(e.read(&mut [0]).unwrap(), 0);
assert_eq!(e.read(&mut [0; 1024]).unwrap(), 0);
assert_eq!(e.by_ref().read(&mut [0; 1024]).unwrap(), 0);
}
#[test]
fn repeat_repeats() {
let mut r = repeat(4);
let mut b = [0; 1024];
assert_eq!(r.read(&mut b).unwrap(), 1024);
assert!(b.iter().all(|b| *b == 4));
}
#[test]
fn take_some_bytes() {
assert_eq!(repeat(4).take(100).bytes().count(), 100);
assert_eq!(repeat(4).take(100).bytes().next().unwrap().unwrap(), 4);
assert_eq!(repeat(1).take(10).chain(repeat(2).take(10)).bytes().count(), 20);
}
}

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// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use core::prelude::v1::*;
use io::prelude::*;
#[cfg(feature = "collections")] use core::convert::TryInto;
use core::cmp;
use io::{self, Initializer, SeekFrom, Error, ErrorKind};
/// A `Cursor` wraps another type and provides it with a
/// [`Seek`] implementation.
///
/// `Cursor`s are typically used with in-memory buffers to allow them to
/// implement [`Read`] and/or [`Write`], allowing these buffers to be used
/// anywhere you might use a reader or writer that does actual I/O.
///
/// The standard library implements some I/O traits on various types which
/// are commonly used as a buffer, like `Cursor<`[`Vec`]`<u8>>` and
/// `Cursor<`[`&[u8]`][bytes]`>`.
///
/// # Examples
///
/// We may want to write bytes to a [`File`] in our production
/// code, but use an in-memory buffer in our tests. We can do this with
/// `Cursor`:
///
/// [`Seek`]: trait.Seek.html
/// [`Read`]: ../../std/io/trait.Read.html
/// [`Write`]: ../../std/io/trait.Write.html
/// [`Vec`]: ../../std/vec/struct.Vec.html
/// [bytes]: ../../std/primitive.slice.html
/// [`File`]: ../fs/struct.File.html
///
/// ```no_run
/// use std::io::prelude::*;
/// use std::io::{self, SeekFrom};
/// use std::fs::File;
///
/// // a library function we've written
/// fn write_ten_bytes_at_end<W: Write + Seek>(writer: &mut W) -> io::Result<()> {
/// writer.seek(SeekFrom::End(-10))?;
///
/// for i in 0..10 {
/// writer.write(&[i])?;
/// }
///
/// // all went well
/// Ok(())
/// }
///
/// # fn foo() -> io::Result<()> {
/// // Here's some code that uses this library function.
/// //
/// // We might want to use a BufReader here for efficiency, but let's
/// // keep this example focused.
/// let mut file = File::create("foo.txt")?;
///
/// write_ten_bytes_at_end(&mut file)?;
/// # Ok(())
/// # }
///
/// // now let's write a test
/// #[test]
/// fn test_writes_bytes() {
/// // setting up a real File is much slower than an in-memory buffer,
/// // let's use a cursor instead
/// use std::io::Cursor;
/// let mut buff = Cursor::new(vec![0; 15]);
///
/// write_ten_bytes_at_end(&mut buff).unwrap();
///
/// assert_eq!(&buff.get_ref()[5..15], &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
/// }
/// ```
#[derive(Clone, Debug)]
pub struct Cursor<T> {
inner: T,
pos: u64,
}
impl<T> Cursor<T> {
/// Creates a new cursor wrapping the provided underlying I/O object.
///
/// Cursor initial position is `0` even if underlying object (e.
/// g. `Vec`) is not empty. So writing to cursor starts with
/// overwriting `Vec` content, not with appending to it.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
/// ```
pub fn new(inner: T) -> Cursor<T> {
Cursor { pos: 0, inner: inner }
}
/// Consumes this cursor, returning the underlying value.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
///
/// let vec = buff.into_inner();
/// ```
pub fn into_inner(self) -> T { self.inner }
/// Gets a reference to the underlying value in this cursor.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
///
/// let reference = buff.get_ref();
/// ```
pub fn get_ref(&self) -> &T { &self.inner }
/// Gets a mutable reference to the underlying value in this cursor.
///
/// Care should be taken to avoid modifying the internal I/O state of the
/// underlying value as it may corrupt this cursor's position.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let mut buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
///
/// let reference = buff.get_mut();
/// ```
pub fn get_mut(&mut self) -> &mut T { &mut self.inner }
/// Returns the current position of this cursor.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
/// use std::io::prelude::*;
/// use std::io::SeekFrom;
///
/// let mut buff = Cursor::new(vec![1, 2, 3, 4, 5]);
///
/// assert_eq!(buff.position(), 0);
///
/// buff.seek(SeekFrom::Current(2)).unwrap();
/// assert_eq!(buff.position(), 2);
///
/// buff.seek(SeekFrom::Current(-1)).unwrap();
/// assert_eq!(buff.position(), 1);
/// ```
pub fn position(&self) -> u64 { self.pos }
/// Sets the position of this cursor.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let mut buff = Cursor::new(vec![1, 2, 3, 4, 5]);
///
/// assert_eq!(buff.position(), 0);
///
/// buff.set_position(2);
/// assert_eq!(buff.position(), 2);
///
/// buff.set_position(4);
/// assert_eq!(buff.position(), 4);
/// ```
pub fn set_position(&mut self, pos: u64) { self.pos = pos; }
}
impl<T> io::Seek for Cursor<T> where T: AsRef<[u8]> {
fn seek(&mut self, style: SeekFrom) -> io::Result<u64> {
let (base_pos, offset) = match style {
SeekFrom::Start(n) => { self.pos = n; return Ok(n); }
SeekFrom::End(n) => (self.inner.as_ref().len() as u64, n),
SeekFrom::Current(n) => (self.pos, n),
};
let new_pos = if offset >= 0 {
base_pos.checked_add(offset as u64)
} else {
base_pos.checked_sub((offset.wrapping_neg()) as u64)
};
match new_pos {
Some(n) => {self.pos = n; Ok(self.pos)}
None => Err(Error::new(ErrorKind::InvalidInput,
"invalid seek to a negative or overflowing position"))
}
}
}
impl<T> Read for Cursor<T> where T: AsRef<[u8]> {
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
let n = Read::read(&mut self.get_buf()?, buf)?;
self.pos += n as u64;
Ok(n)
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
}
impl<T> Cursor<T> where T: AsRef<[u8]> {
fn get_buf(&mut self) -> io::Result<&[u8]> {
let amt = cmp::min(self.pos, self.inner.as_ref().len() as u64);
Ok(&self.inner.as_ref()[(amt as usize)..])
}
}
#[cfg(feature="collections")]
impl<T> BufRead for Cursor<T> where T: AsRef<[u8]> {
fn fill_buf(&mut self) -> io::Result<&[u8]> { self.get_buf() }
fn consume(&mut self, amt: usize) { self.pos += amt as u64; }
}
impl<'a> Write for Cursor<&'a mut [u8]> {
#[inline]
fn write(&mut self, data: &[u8]) -> io::Result<usize> {
let pos = cmp::min(self.pos, self.inner.len() as u64);
let amt = (&mut self.inner[(pos as usize)..]).write(data)?;
self.pos += amt as u64;
Ok(amt)
}
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
#[cfg(feature = "collections")]
impl Write for Cursor<Vec<u8>> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
let pos: usize = self.position().try_into().map_err(|_| {
Error::new(ErrorKind::InvalidInput,
"cursor position exceeds maximum possible vector length")
})?;
// Make sure the internal buffer is as least as big as where we
// currently are
let len = self.inner.len();
if len < pos {
// use `resize` so that the zero filling is as efficient as possible
self.inner.resize(pos, 0);
}
// Figure out what bytes will be used to overwrite what's currently
// there (left), and what will be appended on the end (right)
{
let space = self.inner.len() - pos;
let (left, right) = buf.split_at(cmp::min(space, buf.len()));
self.inner[pos..pos + left.len()].copy_from_slice(left);
self.inner.extend_from_slice(right);
}
// Bump us forward
self.set_position((pos + buf.len()) as u64);
Ok(buf.len())
}
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
#[cfg(feature = "alloc")]
impl Write for Cursor<::alloc::boxed::Box<[u8]>> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
let pos = cmp::min(self.pos, self.inner.len() as u64);
let amt = (&mut self.inner[(pos as usize)..]).write(buf)?;
self.pos += amt as u64;
Ok(amt)
}
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
#[cfg(test)]
mod tests {
use io::prelude::*;
use io::{Cursor, SeekFrom};
#[test]
fn test_vec_writer() {
let mut writer = Vec::new();
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7];
assert_eq!(writer, b);
}
#[test]
fn test_mem_writer() {
let mut writer = Cursor::new(Vec::new());
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
}
#[test]
fn test_box_slice_writer() {
let mut writer = Cursor::new(vec![0u8; 9].into_boxed_slice());
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[]).unwrap(), 0);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[8, 9]).unwrap(), 1);
assert_eq!(writer.write(&[10]).unwrap(), 0);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8];
assert_eq!(&**writer.get_ref(), b);
}
#[test]
fn test_buf_writer() {
let mut buf = [0 as u8; 9];
{
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[]).unwrap(), 0);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[8, 9]).unwrap(), 1);
assert_eq!(writer.write(&[10]).unwrap(), 0);
}
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8];
assert_eq!(buf, b);
}
#[test]
fn test_buf_writer_seek() {
let mut buf = [0 as u8; 8];
{
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[1]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.seek(SeekFrom::Start(2)).unwrap(), 2);
assert_eq!(writer.position(), 2);
assert_eq!(writer.write(&[2]).unwrap(), 1);
assert_eq!(writer.position(), 3);
assert_eq!(writer.seek(SeekFrom::Current(-2)).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[3]).unwrap(), 1);
assert_eq!(writer.position(), 2);
assert_eq!(writer.seek(SeekFrom::End(-1)).unwrap(), 7);
assert_eq!(writer.position(), 7);
assert_eq!(writer.write(&[4]).unwrap(), 1);
assert_eq!(writer.position(), 8);
}
let b: &[_] = &[1, 3, 2, 0, 0, 0, 0, 4];
assert_eq!(buf, b);
}
#[test]
fn test_buf_writer_error() {
let mut buf = [0 as u8; 2];
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[0, 0]).unwrap(), 1);
assert_eq!(writer.write(&[0, 0]).unwrap(), 0);
}
#[test]
fn test_mem_reader() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7]);
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.position(), 5);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(buf, b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_boxed_slice_reader() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7].into_boxed_slice());
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.position(), 5);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(buf, b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn read_to_end() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7]);
let mut v = Vec::new();
reader.read_to_end(&mut v).unwrap();
assert_eq!(v, [0, 1, 2, 3, 4, 5, 6, 7]);
}
#[test]
fn test_slice_reader() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let reader = &mut &in_buf[..];
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.len(), 7);
let b: &[_] = &[0];
assert_eq!(&buf[..], b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.len(), 3);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(&buf[..], b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_buf_reader() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let mut reader = Cursor::new(&in_buf[..]);
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.position(), 5);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(buf, b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_read_char() {
let b = &b"Vi\xE1\xBB\x87t"[..];
let mut c = Cursor::new(b).chars();
assert_eq!(c.next().unwrap().unwrap(), 'V');
assert_eq!(c.next().unwrap().unwrap(), 'i');
assert_eq!(c.next().unwrap().unwrap(), 'ệ');
assert_eq!(c.next().unwrap().unwrap(), 't');
assert!(c.next().is_none());
}
#[test]
fn test_read_bad_char() {
let b = &b"\x80"[..];
let mut c = Cursor::new(b).chars();
assert!(c.next().unwrap().is_err());
}
#[test]
fn seek_past_end() {
let buf = [0xff];
let mut r = Cursor::new(&buf[..]);
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.read(&mut [0]).unwrap(), 0);
let mut r = Cursor::new(vec![10]);
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.read(&mut [0]).unwrap(), 0);
let mut buf = [0];
let mut r = Cursor::new(&mut buf[..]);
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.write(&[3]).unwrap(), 0);
let mut r = Cursor::new(vec![10].into_boxed_slice());
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.write(&[3]).unwrap(), 0);
}
#[test]
fn seek_past_i64() {
let buf = [0xff];
let mut r = Cursor::new(&buf[..]);
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
let mut r = Cursor::new(vec![10]);
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
let mut buf = [0];
let mut r = Cursor::new(&mut buf[..]);
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
let mut r = Cursor::new(vec![10].into_boxed_slice());
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
}
#[test]
fn seek_before_0() {
let buf = [0xff];
let mut r = Cursor::new(&buf[..]);
assert!(r.seek(SeekFrom::End(-2)).is_err());
let mut r = Cursor::new(vec![10]);
assert!(r.seek(SeekFrom::End(-2)).is_err());
let mut buf = [0];
let mut r = Cursor::new(&mut buf[..]);
assert!(r.seek(SeekFrom::End(-2)).is_err());
let mut r = Cursor::new(vec![10].into_boxed_slice());
assert!(r.seek(SeekFrom::End(-2)).is_err());
}
#[test]
fn test_seekable_mem_writer() {
let mut writer = Cursor::new(Vec::<u8>::new());
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.position(), 8);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::Start(0)).unwrap(), 0);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[3, 4]).unwrap(), 2);
let b: &[_] = &[3, 4, 2, 3, 4, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::Current(1)).unwrap(), 3);
assert_eq!(writer.write(&[0, 1]).unwrap(), 2);
let b: &[_] = &[3, 4, 2, 0, 1, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::End(-1)).unwrap(), 7);
assert_eq!(writer.write(&[1, 2]).unwrap(), 2);
let b: &[_] = &[3, 4, 2, 0, 1, 5, 6, 1, 2];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::End(1)).unwrap(), 10);
assert_eq!(writer.write(&[1]).unwrap(), 1);
let b: &[_] = &[3, 4, 2, 0, 1, 5, 6, 1, 2, 0, 1];
assert_eq!(&writer.get_ref()[..], b);
}
#[test]
fn vec_seek_past_end() {
let mut r = Cursor::new(Vec::new());
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.write(&[3]).unwrap(), 1);
}
#[test]
fn vec_seek_before_0() {
let mut r = Cursor::new(Vec::new());
assert!(r.seek(SeekFrom::End(-2)).is_err());
}
#[test]
#[cfg(target_pointer_width = "32")]
fn vec_seek_and_write_past_usize_max() {
let mut c = Cursor::new(Vec::new());
c.set_position(<usize>::max_value() as u64 + 1);
assert!(c.write_all(&[1, 2, 3]).is_err());
}
}

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@ -0,0 +1,538 @@
// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
#[cfg(feature="alloc")] use alloc::boxed::Box;
#[cfg(not(feature="alloc"))] use ::FakeBox as Box;
use core::convert::Into;
use core::fmt;
use core::marker::{Send, Sync};
use core::option::Option::{self, Some, None};
use core::result;
#[cfg(feature="collections")] use collections::string::String;
#[cfg(not(feature="collections"))] use ::ErrorString as String;
use core::convert::From;
/// A specialized [`Result`](../result/enum.Result.html) type for I/O
/// operations.
///
/// This type is broadly used across [`std::io`] for any operation which may
/// produce an error.
///
/// This typedef is generally used to avoid writing out [`io::Error`] directly and
/// is otherwise a direct mapping to [`Result`].
///
/// While usual Rust style is to import types directly, aliases of [`Result`]
/// often are not, to make it easier to distinguish between them. [`Result`] is
/// generally assumed to be [`std::result::Result`][`Result`], and so users of this alias
/// will generally use `io::Result` instead of shadowing the prelude's import
/// of [`std::result::Result`][`Result`].
///
/// [`std::io`]: ../io/index.html
/// [`io::Error`]: ../io/struct.Error.html
/// [`Result`]: ../result/enum.Result.html
///
/// # Examples
///
/// A convenience function that bubbles an `io::Result` to its caller:
///
/// ```
/// use std::io;
///
/// fn get_string() -> io::Result<String> {
/// let mut buffer = String::new();
///
/// io::stdin().read_line(&mut buffer)?;
///
/// Ok(buffer)
/// }
/// ```
pub type Result<T> = result::Result<T, Error>;
/// The error type for I/O operations of the [`Read`], [`Write`], [`Seek`], and
/// associated traits.
///
/// Errors mostly originate from the underlying OS, but custom instances of
/// `Error` can be created with crafted error messages and a particular value of
/// [`ErrorKind`].
///
/// [`Read`]: ../io/trait.Read.html
/// [`Write`]: ../io/trait.Write.html
/// [`Seek`]: ../io/trait.Seek.html
/// [`ErrorKind`]: enum.ErrorKind.html
#[derive(Debug)]
pub struct Error {
repr: Repr,
}
enum Repr {
Os(i32),
Simple(ErrorKind),
#[cfg(feature="alloc")]
Custom(Box<Custom>),
#[cfg(not(feature="alloc"))]
Custom(Custom),
}
#[derive(Debug)]
struct Custom {
kind: ErrorKind,
error: String,
}
/// A list specifying general categories of I/O error.
///
/// This list is intended to grow over time and it is not recommended to
/// exhaustively match against it.
///
/// It is used with the [`io::Error`] type.
///
/// [`io::Error`]: struct.Error.html
#[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
#[allow(deprecated)]
pub enum ErrorKind {
/// An entity was not found, often a file.
NotFound,
/// The operation lacked the necessary privileges to complete.
PermissionDenied,
/// The connection was refused by the remote server.
ConnectionRefused,
/// The connection was reset by the remote server.
ConnectionReset,
/// The connection was aborted (terminated) by the remote server.
ConnectionAborted,
/// The network operation failed because it was not connected yet.
NotConnected,
/// A socket address could not be bound because the address is already in
/// use elsewhere.
AddrInUse,
/// A nonexistent interface was requested or the requested address was not
/// local.
AddrNotAvailable,
/// The operation failed because a pipe was closed.
BrokenPipe,
/// An entity already exists, often a file.
AlreadyExists,
/// The operation needs to block to complete, but the blocking operation was
/// requested to not occur.
WouldBlock,
/// A parameter was incorrect.
InvalidInput,
/// Data not valid for the operation were encountered.
///
/// Unlike [`InvalidInput`], this typically means that the operation
/// parameters were valid, however the error was caused by malformed
/// input data.
///
/// For example, a function that reads a file into a string will error with
/// `InvalidData` if the file's contents are not valid UTF-8.
///
/// [`InvalidInput`]: #variant.InvalidInput
InvalidData,
/// The I/O operation's timeout expired, causing it to be canceled.
TimedOut,
/// An error returned when an operation could not be completed because a
/// call to [`write`] returned [`Ok(0)`].
///
/// This typically means that an operation could only succeed if it wrote a
/// particular number of bytes but only a smaller number of bytes could be
/// written.
///
/// [`write`]: ../../std/io/trait.Write.html#tymethod.write
/// [`Ok(0)`]: ../../std/io/type.Result.html
WriteZero,
/// This operation was interrupted.
///
/// Interrupted operations can typically be retried.
Interrupted,
/// Any I/O error not part of this list.
Other,
/// An error returned when an operation could not be completed because an
/// "end of file" was reached prematurely.
///
/// This typically means that an operation could only succeed if it read a
/// particular number of bytes but only a smaller number of bytes could be
/// read.
UnexpectedEof,
/// A marker variant that tells the compiler that users of this enum cannot
/// match it exhaustively.
#[doc(hidden)]
__Nonexhaustive,
}
impl ErrorKind {
fn as_str(&self) -> &'static str {
match *self {
ErrorKind::NotFound => "entity not found",
ErrorKind::PermissionDenied => "permission denied",
ErrorKind::ConnectionRefused => "connection refused",
ErrorKind::ConnectionReset => "connection reset",
ErrorKind::ConnectionAborted => "connection aborted",
ErrorKind::NotConnected => "not connected",
ErrorKind::AddrInUse => "address in use",
ErrorKind::AddrNotAvailable => "address not available",
ErrorKind::BrokenPipe => "broken pipe",
ErrorKind::AlreadyExists => "entity already exists",
ErrorKind::WouldBlock => "operation would block",
ErrorKind::InvalidInput => "invalid input parameter",
ErrorKind::InvalidData => "invalid data",
ErrorKind::TimedOut => "timed out",
ErrorKind::WriteZero => "write zero",
ErrorKind::Interrupted => "operation interrupted",
ErrorKind::Other => "other os error",
ErrorKind::UnexpectedEof => "unexpected end of file",
ErrorKind::__Nonexhaustive => unreachable!()
}
}
}
/// Intended for use for errors not exposed to the user, where allocating onto
/// the heap (for normal construction via Error::new) is too costly.
impl From<ErrorKind> for Error {
#[inline]
fn from(kind: ErrorKind) -> Error {
Error {
repr: Repr::Simple(kind)
}
}
}
impl Error {
/// Creates a new I/O error from a known kind of error as well as an
/// arbitrary error payload.
///
/// This function is used to generically create I/O errors which do not
/// originate from the OS itself. The `error` argument is an arbitrary
/// payload which will be contained in this `Error`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// // errors can be created from strings
/// let custom_error = Error::new(ErrorKind::Other, "oh no!");
///
/// // errors can also be created from other errors
/// let custom_error2 = Error::new(ErrorKind::Interrupted, custom_error);
/// ```
pub fn new<E>(kind: ErrorKind, error: E) -> Error
where E: Into<String>
{
Self::_new(kind, error.into())
}
fn _new(kind: ErrorKind, error: String) -> Error {
Error {
repr: Repr::Custom(Box::new(Custom {
kind,
error,
}))
}
}
/// Creates a new instance of an `Error` from a particular OS error code.
///
/// # Examples
///
/// On Linux:
///
/// ```
/// # if cfg!(target_os = "linux") {
/// use std::io;
///
/// let error = io::Error::from_raw_os_error(98);
/// assert_eq!(error.kind(), io::ErrorKind::AddrInUse);
/// # }
/// ```
///
/// On Windows:
///
/// ```
/// # if cfg!(windows) {
/// use std::io;
///
/// let error = io::Error::from_raw_os_error(10048);
/// assert_eq!(error.kind(), io::ErrorKind::AddrInUse);
/// # }
/// ```
pub fn from_raw_os_error(code: i32) -> Error {
Error { repr: Repr::Os(code) }
}
/// Returns the OS error that this error represents (if any).
///
/// If this `Error` was constructed via `last_os_error` or
/// `from_raw_os_error`, then this function will return `Some`, otherwise
/// it will return `None`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_os_error(err: &Error) {
/// if let Some(raw_os_err) = err.raw_os_error() {
/// println!("raw OS error: {:?}", raw_os_err);
/// } else {
/// println!("Not an OS error");
/// }
/// }
///
/// fn main() {
/// // Will print "raw OS error: ...".
/// print_os_error(&Error::last_os_error());
/// // Will print "Not an OS error".
/// print_os_error(&Error::new(ErrorKind::Other, "oh no!"));
/// }
/// ```
pub fn raw_os_error(&self) -> Option<i32> {
match self.repr {
Repr::Os(i) => Some(i),
Repr::Custom(..) => None,
Repr::Simple(..) => None,
}
}
/// Returns a reference to the inner error wrapped by this error (if any).
///
/// If this `Error` was constructed via `new` then this function will
/// return `Some`, otherwise it will return `None`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_error(err: &Error) {
/// if let Some(inner_err) = err.get_ref() {
/// println!("Inner error: {:?}", inner_err);
/// } else {
/// println!("No inner error");
/// }
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(&Error::last_os_error());
/// // Will print "Inner error: ...".
/// print_error(&Error::new(ErrorKind::Other, "oh no!"));
/// }
/// ```
pub fn get_ref(&self) -> Option<&String> {
match self.repr {
Repr::Os(..) => None,
Repr::Simple(..) => None,
Repr::Custom(ref c) => Some(&c.error),
}
}
/// Returns a mutable reference to the inner error wrapped by this error
/// (if any).
///
/// If this `Error` was constructed via `new` then this function will
/// return `Some`, otherwise it will return `None`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
/// use std::{error, fmt};
/// use std::fmt::Display;
///
/// #[derive(Debug)]
/// struct MyError {
/// v: String,
/// }
///
/// impl MyError {
/// fn new() -> MyError {
/// MyError {
/// v: "oh no!".to_string()
/// }
/// }
///
/// fn change_message(&mut self, new_message: &str) {
/// self.v = new_message.to_string();
/// }
/// }
///
/// impl error::Error for MyError {
/// fn description(&self) -> &str { &self.v }
/// }
///
/// impl Display for MyError {
/// fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
/// write!(f, "MyError: {}", &self.v)
/// }
/// }
///
/// fn change_error(mut err: Error) -> Error {
/// if let Some(inner_err) = err.get_mut() {
/// inner_err.downcast_mut::<MyError>().unwrap().change_message("I've been changed!");
/// }
/// err
/// }
///
/// fn print_error(err: &Error) {
/// if let Some(inner_err) = err.get_ref() {
/// println!("Inner error: {}", inner_err);
/// } else {
/// println!("No inner error");
/// }
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(&change_error(Error::last_os_error()));
/// // Will print "Inner error: ...".
/// print_error(&change_error(Error::new(ErrorKind::Other, MyError::new())));
/// }
/// ```
pub fn get_mut(&mut self) -> Option<&mut String> {
match self.repr {
Repr::Os(..) => None,
Repr::Simple(..) => None,
Repr::Custom(ref mut c) => Some(&mut c.error),
}
}
/// Consumes the `Error`, returning its inner error (if any).
///
/// If this `Error` was constructed via `new` then this function will
/// return `Some`, otherwise it will return `None`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_error(err: Error) {
/// if let Some(inner_err) = err.into_inner() {
/// println!("Inner error: {}", inner_err);
/// } else {
/// println!("No inner error");
/// }
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(Error::last_os_error());
/// // Will print "Inner error: ...".
/// print_error(Error::new(ErrorKind::Other, "oh no!"));
/// }
/// ```
pub fn into_inner(self) -> Option<String> {
match self.repr {
Repr::Os(..) => None,
Repr::Simple(..) => None,
Repr::Custom(c) => Some(c.error)
}
}
/// Returns the corresponding `ErrorKind` for this error.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_error(err: Error) {
/// println!("{:?}", err.kind());
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(Error::last_os_error());
/// // Will print "Inner error: ...".
/// print_error(Error::new(ErrorKind::AddrInUse, "oh no!"));
/// }
/// ```
pub fn kind(&self) -> ErrorKind {
match self.repr {
Repr::Os(_code) => ErrorKind::Other,
Repr::Custom(ref c) => c.kind,
Repr::Simple(kind) => kind,
}
}
}
impl fmt::Debug for Repr {
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
match *self {
Repr::Os(ref code) =>
fmt.debug_struct("Os").field("code", code).finish(),
Repr::Custom(ref c) => fmt.debug_tuple("Custom").field(c).finish(),
Repr::Simple(kind) => fmt.debug_tuple("Kind").field(&kind).finish(),
}
}
}
impl fmt::Display for Error {
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
match self.repr {
Repr::Os(code) => {
write!(fmt, "os error {}", code)
}
Repr::Custom(ref c) => c.error.fmt(fmt),
Repr::Simple(kind) => write!(fmt, "{}", kind.as_str()),
}
}
}
fn _assert_error_is_sync_send() {
fn _is_sync_send<T: Sync+Send>() {}
_is_sync_send::<Error>();
}
#[cfg(test)]
mod test {
use super::{Error, ErrorKind};
use error;
use fmt;
use sys::os::error_string;
#[test]
fn test_debug_error() {
let code = 6;
let msg = error_string(code);
let err = Error { repr: super::Repr::Os(code) };
let expected = format!("Error {{ repr: Os {{ code: {:?}, message: {:?} }} }}", code, msg);
assert_eq!(format!("{:?}", err), expected);
}
#[test]
fn test_downcasting() {
#[derive(Debug)]
struct TestError;
impl fmt::Display for TestError {
fn fmt(&self, _: &mut fmt::Formatter) -> fmt::Result {
Ok(())
}
}
impl error::Error for TestError {
fn description(&self) -> &str {
"asdf"
}
}
// we have to call all of these UFCS style right now since method
// resolution won't implicitly drop the Send+Sync bounds
let mut err = Error::new(ErrorKind::Other, TestError);
assert!(err.get_ref().unwrap().is::<TestError>());
assert_eq!("asdf", err.get_ref().unwrap().description());
assert!(err.get_mut().unwrap().is::<TestError>());
let extracted = err.into_inner().unwrap();
extracted.downcast::<TestError>().unwrap();
}
}

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// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
#[cfg(feature="alloc")] use alloc::boxed::Box;
use core::cmp;
use io::{self, SeekFrom, Read, Initializer, Write, Seek, Error, ErrorKind};
#[cfg(feature="collections")] use io::BufRead;
use core::fmt;
use core::mem;
#[cfg(feature="collections")] use collections::string::String;
#[cfg(feature="collections")] use collections::vec::Vec;
// =============================================================================
// Forwarding implementations
impl<'a, R: Read + ?Sized> Read for &'a mut R {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
(**self).read(buf)
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
(**self).initializer()
}
#[cfg(feature="collections")]
#[inline]
fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_to_end(buf)
}
#[cfg(feature="collections")]
#[inline]
fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_to_string(buf)
}
#[inline]
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
(**self).read_exact(buf)
}
}
impl<'a, W: Write + ?Sized> Write for &'a mut W {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> { (**self).write(buf) }
#[inline]
fn flush(&mut self) -> io::Result<()> { (**self).flush() }
#[inline]
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
(**self).write_all(buf)
}
#[inline]
fn write_fmt(&mut self, fmt: fmt::Arguments) -> io::Result<()> {
(**self).write_fmt(fmt)
}
}
impl<'a, S: Seek + ?Sized> Seek for &'a mut S {
#[inline]
fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> { (**self).seek(pos) }
}
#[cfg(feature="collections")]
impl<'a, B: BufRead + ?Sized> BufRead for &'a mut B {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> { (**self).fill_buf() }
#[inline]
fn consume(&mut self, amt: usize) { (**self).consume(amt) }
#[inline]
fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_until(byte, buf)
}
#[inline]
fn read_line(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_line(buf)
}
}
#[cfg(feature="alloc")]
impl<R: Read + ?Sized> Read for Box<R> {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
(**self).read(buf)
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
(**self).initializer()
}
#[cfg(feature="collections")]
#[inline]
fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_to_end(buf)
}
#[cfg(feature="collections")]
#[inline]
fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_to_string(buf)
}
#[inline]
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
(**self).read_exact(buf)
}
}
#[cfg(feature="alloc")]
impl<W: Write + ?Sized> Write for Box<W> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> { (**self).write(buf) }
#[inline]
fn flush(&mut self) -> io::Result<()> { (**self).flush() }
#[inline]
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
(**self).write_all(buf)
}
#[inline]
fn write_fmt(&mut self, fmt: fmt::Arguments) -> io::Result<()> {
(**self).write_fmt(fmt)
}
}
#[cfg(feature="alloc")]
impl<S: Seek + ?Sized> Seek for Box<S> {
#[inline]
fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> { (**self).seek(pos) }
}
#[cfg(feature="collections")]
impl<B: BufRead + ?Sized> BufRead for Box<B> {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> { (**self).fill_buf() }
#[inline]
fn consume(&mut self, amt: usize) { (**self).consume(amt) }
#[inline]
fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_until(byte, buf)
}
#[inline]
fn read_line(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_line(buf)
}
}
// =============================================================================
// In-memory buffer implementations
/// Read is implemented for `&[u8]` by copying from the slice.
///
/// Note that reading updates the slice to point to the yet unread part.
/// The slice will be empty when EOF is reached.
impl<'a> Read for &'a [u8] {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
let amt = cmp::min(buf.len(), self.len());
let (a, b) = self.split_at(amt);
// First check if the amount of bytes we want to read is small:
// `copy_from_slice` will generally expand to a call to `memcpy`, and
// for a single byte the overhead is significant.
if amt == 1 {
buf[0] = a[0];
} else {
buf[..amt].copy_from_slice(a);
}
*self = b;
Ok(amt)
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
#[inline]
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
if buf.len() > self.len() {
return Err(Error::new(ErrorKind::UnexpectedEof,
"failed to fill whole buffer"));
}
let (a, b) = self.split_at(buf.len());
// First check if the amount of bytes we want to read is small:
// `copy_from_slice` will generally expand to a call to `memcpy`, and
// for a single byte the overhead is significant.
if buf.len() == 1 {
buf[0] = a[0];
} else {
buf.copy_from_slice(a);
}
*self = b;
Ok(())
}
}
#[cfg(feature="collections")]
impl<'a> BufRead for &'a [u8] {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> { Ok(*self) }
#[inline]
fn consume(&mut self, amt: usize) { *self = &self[amt..]; }
}
/// Write is implemented for `&mut [u8]` by copying into the slice, overwriting
/// its data.
///
/// Note that writing updates the slice to point to the yet unwritten part.
/// The slice will be empty when it has been completely overwritten.
impl<'a> Write for &'a mut [u8] {
#[inline]
fn write(&mut self, data: &[u8]) -> io::Result<usize> {
let amt = cmp::min(data.len(), self.len());
let (a, b) = mem::replace(self, &mut []).split_at_mut(amt);
a.copy_from_slice(&data[..amt]);
*self = b;
Ok(amt)
}
#[inline]
fn write_all(&mut self, data: &[u8]) -> io::Result<()> {
if self.write(data)? == data.len() {
Ok(())
} else {
Err(Error::new(ErrorKind::WriteZero, "failed to write whole buffer"))
}
}
#[inline]
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
/// Write is implemented for `Vec<u8>` by appending to the vector.
/// The vector will grow as needed.
#[cfg(feature="collections")]
impl Write for Vec<u8> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
self.extend_from_slice(buf);
Ok(buf.len())
}
#[inline]
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
self.extend_from_slice(buf);
Ok(())
}
#[inline]
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
#[cfg(test)]
mod tests {
use io::prelude::*;
use test;
#[bench]
fn bench_read_slice(b: &mut test::Bencher) {
let buf = [5; 1024];
let mut dst = [0; 128];
b.iter(|| {
let mut rd = &buf[..];
for _ in 0..8 {
let _ = rd.read(&mut dst);
test::black_box(&dst);
}
})
}
#[bench]
fn bench_write_slice(b: &mut test::Bencher) {
let mut buf = [0; 1024];
let src = [5; 128];
b.iter(|| {
let mut wr = &mut buf[..];
for _ in 0..8 {
let _ = wr.write_all(&src);
test::black_box(&wr);
}
})
}
#[bench]
fn bench_read_vec(b: &mut test::Bencher) {
let buf = vec![5; 1024];
let mut dst = [0; 128];
b.iter(|| {
let mut rd = &buf[..];
for _ in 0..8 {
let _ = rd.read(&mut dst);
test::black_box(&dst);
}
})
}
#[bench]
fn bench_write_vec(b: &mut test::Bencher) {
let mut buf = Vec::with_capacity(1024);
let src = [5; 128];
b.iter(|| {
let mut wr = &mut buf[..];
for _ in 0..8 {
let _ = wr.write_all(&src);
test::black_box(&wr);
}
})
}
}

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// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//
// Original implementation taken from rust-memchr
// Copyright 2015 Andrew Gallant, bluss and Nicolas Koch
pub use self::fallback::{memchr,memrchr};
#[allow(dead_code)]
pub mod fallback {
use core::cmp;
use core::mem;
const LO_U64: u64 = 0x0101010101010101;
const HI_U64: u64 = 0x8080808080808080;
// use truncation
const LO_USIZE: usize = LO_U64 as usize;
const HI_USIZE: usize = HI_U64 as usize;
/// Return `true` if `x` contains any zero byte.
///
/// From *Matters Computational*, J. Arndt
///
/// "The idea is to subtract one from each of the bytes and then look for
/// bytes where the borrow propagated all the way to the most significant
/// bit."
#[inline]
fn contains_zero_byte(x: usize) -> bool {
x.wrapping_sub(LO_USIZE) & !x & HI_USIZE != 0
}
#[cfg(target_pointer_width = "32")]
#[inline]
fn repeat_byte(b: u8) -> usize {
let mut rep = (b as usize) << 8 | b as usize;
rep = rep << 16 | rep;
rep
}
#[cfg(target_pointer_width = "64")]
#[inline]
fn repeat_byte(b: u8) -> usize {
let mut rep = (b as usize) << 8 | b as usize;
rep = rep << 16 | rep;
rep = rep << 32 | rep;
rep
}
/// Return the first index matching the byte `a` in `text`.
pub fn memchr(x: u8, text: &[u8]) -> Option<usize> {
// Scan for a single byte value by reading two `usize` words at a time.
//
// Split `text` in three parts
// - unaligned initial part, before the first word aligned address in text
// - body, scan by 2 words at a time
// - the last remaining part, < 2 word size
let len = text.len();
let ptr = text.as_ptr();
let usize_bytes = mem::size_of::<usize>();
// search up to an aligned boundary
let mut offset = ptr.align_offset(usize_bytes);
if offset > 0 {
offset = cmp::min(offset, len);
if let Some(index) = text[..offset].iter().position(|elt| *elt == x) {
return Some(index);
}
}
// search the body of the text
let repeated_x = repeat_byte(x);
if len >= 2 * usize_bytes {
while offset <= len - 2 * usize_bytes {
unsafe {
let u = *(ptr.offset(offset as isize) as *const usize);
let v = *(ptr.offset((offset + usize_bytes) as isize) as *const usize);
// break if there is a matching byte
let zu = contains_zero_byte(u ^ repeated_x);
let zv = contains_zero_byte(v ^ repeated_x);
if zu || zv {
break;
}
}
offset += usize_bytes * 2;
}
}
// find the byte after the point the body loop stopped
text[offset..].iter().position(|elt| *elt == x).map(|i| offset + i)
}
/// Return the last index matching the byte `a` in `text`.
pub fn memrchr(x: u8, text: &[u8]) -> Option<usize> {
// Scan for a single byte value by reading two `usize` words at a time.
//
// Split `text` in three parts
// - unaligned tail, after the last word aligned address in text
// - body, scan by 2 words at a time
// - the first remaining bytes, < 2 word size
let len = text.len();
let ptr = text.as_ptr();
let usize_bytes = mem::size_of::<usize>();
// search to an aligned boundary
let end_align = (ptr as usize + len) & (usize_bytes - 1);
let mut offset;
if end_align > 0 {
offset = if end_align >= len { 0 } else { len - end_align };
if let Some(index) = text[offset..].iter().rposition(|elt| *elt == x) {
return Some(offset + index);
}
} else {
offset = len;
}
// search the body of the text
let repeated_x = repeat_byte(x);
while offset >= 2 * usize_bytes {
unsafe {
let u = *(ptr.offset(offset as isize - 2 * usize_bytes as isize) as *const usize);
let v = *(ptr.offset(offset as isize - usize_bytes as isize) as *const usize);
// break if there is a matching byte
let zu = contains_zero_byte(u ^ repeated_x);
let zv = contains_zero_byte(v ^ repeated_x);
if zu || zv {
break;
}
}
offset -= 2 * usize_bytes;
}
// find the byte before the point the body loop stopped
text[..offset].iter().rposition(|elt| *elt == x)
}
// test fallback implementations on all platforms
#[test]
fn matches_one() {
assert_eq!(Some(0), memchr(b'a', b"a"));
}
#[test]
fn matches_begin() {
assert_eq!(Some(0), memchr(b'a', b"aaaa"));
}
#[test]
fn matches_end() {
assert_eq!(Some(4), memchr(b'z', b"aaaaz"));
}
#[test]
fn matches_nul() {
assert_eq!(Some(4), memchr(b'\x00', b"aaaa\x00"));
}
#[test]
fn matches_past_nul() {
assert_eq!(Some(5), memchr(b'z', b"aaaa\x00z"));
}
#[test]
fn no_match_empty() {
assert_eq!(None, memchr(b'a', b""));
}
#[test]
fn no_match() {
assert_eq!(None, memchr(b'a', b"xyz"));
}
#[test]
fn matches_one_reversed() {
assert_eq!(Some(0), memrchr(b'a', b"a"));
}
#[test]
fn matches_begin_reversed() {
assert_eq!(Some(3), memrchr(b'a', b"aaaa"));
}
#[test]
fn matches_end_reversed() {
assert_eq!(Some(0), memrchr(b'z', b"zaaaa"));
}
#[test]
fn matches_nul_reversed() {
assert_eq!(Some(4), memrchr(b'\x00', b"aaaa\x00"));
}
#[test]
fn matches_past_nul_reversed() {
assert_eq!(Some(0), memrchr(b'z', b"z\x00aaaa"));
}
#[test]
fn no_match_empty_reversed() {
assert_eq!(None, memrchr(b'a', b""));
}
#[test]
fn no_match_reversed() {
assert_eq!(None, memrchr(b'a', b"xyz"));
}
#[test]
fn each_alignment_reversed() {
let mut data = [1u8; 64];
let needle = 2;
let pos = 40;
data[pos] = needle;
for start in 0..16 {
assert_eq!(Some(pos - start), memrchr(needle, &data[start..]));
}
}
}

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// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//! The I/O Prelude
//!
//! The purpose of this module is to alleviate imports of many common I/O traits
//! by adding a glob import to the top of I/O heavy modules:
//!
//! ```
//! # #![allow(unused_imports)]
//! use std::io::prelude::*;
//! ```
pub use super::{Read, Write, Seek};
#[cfg(feature="collections")] pub use super::BufRead;
#[cfg(feature="collections")] pub use alloc::boxed::Box;
#[cfg(feature="collections")] pub use collections::vec::Vec;

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// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
#![allow(missing_copy_implementations)]
use core::fmt;
use io::{self, Read, Initializer, Write, ErrorKind};
use core::mem;
#[cfg(feature="collections")] use io::BufRead;
/// Copies the entire contents of a reader into a writer.
///
/// This function will continuously read data from `reader` and then
/// write it into `writer` in a streaming fashion until `reader`
/// returns EOF.
///
/// On success, the total number of bytes that were copied from
/// `reader` to `writer` is returned.
///
/// # Errors
///
/// This function will return an error immediately if any call to `read` or
/// `write` returns an error. All instances of `ErrorKind::Interrupted` are
/// handled by this function and the underlying operation is retried.
///
/// # Examples
///
/// ```
/// use std::io;
///
/// # fn foo() -> io::Result<()> {
/// let mut reader: &[u8] = b"hello";
/// let mut writer: Vec<u8> = vec![];
///
/// io::copy(&mut reader, &mut writer)?;
///
/// assert_eq!(&b"hello"[..], &writer[..]);
/// # Ok(())
/// # }
/// # foo().unwrap();
/// ```
pub fn copy<R: ?Sized, W: ?Sized>(reader: &mut R, writer: &mut W) -> io::Result<u64>
where R: Read, W: Write
{
let mut buf = unsafe {
let mut buf: [u8; super::DEFAULT_BUF_SIZE] = mem::uninitialized();
reader.initializer().initialize(&mut buf);
buf
};
let mut written = 0;
loop {
let len = match reader.read(&mut buf) {
Ok(0) => return Ok(written),
Ok(len) => len,
Err(ref e) if e.kind() == ErrorKind::Interrupted => continue,
Err(e) => return Err(e),
};
writer.write_all(&buf[..len])?;
written += len as u64;
}
}
/// A reader which is always at EOF.
///
/// This struct is generally created by calling [`empty`]. Please see
/// the documentation of [`empty()`][`empty`] for more details.
///
/// [`empty`]: fn.empty.html
pub struct Empty { _priv: () }
/// Constructs a new handle to an empty reader.
///
/// All reads from the returned reader will return [`Ok`]`(0)`.
///
/// [`Ok`]: ../result/enum.Result.html#variant.Ok
///
/// # Examples
///
/// A slightly sad example of not reading anything into a buffer:
///
/// ```
/// use std::io::{self, Read};
///
/// let mut buffer = String::new();
/// io::empty().read_to_string(&mut buffer).unwrap();
/// assert!(buffer.is_empty());
/// ```
pub fn empty() -> Empty { Empty { _priv: () } }
impl Read for Empty {
#[inline]
fn read(&mut self, _buf: &mut [u8]) -> io::Result<usize> { Ok(0) }
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
}
#[cfg(feature="collections")]
impl BufRead for Empty {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> { Ok(&[]) }
#[inline]
fn consume(&mut self, _n: usize) {}
}
impl fmt::Debug for Empty {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.pad("Empty { .. }")
}
}
/// A reader which yields one byte over and over and over and over and over and...
///
/// This struct is generally created by calling [`repeat`][repeat]. Please
/// see the documentation of `repeat()` for more details.
///
/// [repeat]: fn.repeat.html
pub struct Repeat { byte: u8 }
/// Creates an instance of a reader that infinitely repeats one byte.
///
/// All reads from this reader will succeed by filling the specified buffer with
/// the given byte.
///
/// # Examples
///
/// ```
/// use std::io::{self, Read};
///
/// let mut buffer = [0; 3];
/// io::repeat(0b101).read_exact(&mut buffer).unwrap();
/// assert_eq!(buffer, [0b101, 0b101, 0b101]);
/// ```
pub fn repeat(byte: u8) -> Repeat { Repeat { byte: byte } }
impl Read for Repeat {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
for slot in &mut *buf {
*slot = self.byte;
}
Ok(buf.len())
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
}
impl fmt::Debug for Repeat {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.pad("Repeat { .. }")
}
}
/// A writer which will move data into the void.
///
/// This struct is generally created by calling [`sink`][sink]. Please
/// see the documentation of `sink()` for more details.
///
/// [sink]: fn.sink.html
pub struct Sink { _priv: () }
/// Creates an instance of a writer which will successfully consume all data.
///
/// All calls to `write` on the returned instance will return `Ok(buf.len())`
/// and the contents of the buffer will not be inspected.
///
/// # Examples
///
/// ```rust
/// use std::io::{self, Write};
///
/// let buffer = vec![1, 2, 3, 5, 8];
/// let num_bytes = io::sink().write(&buffer).unwrap();
/// assert_eq!(num_bytes, 5);
/// ```
pub fn sink() -> Sink { Sink { _priv: () } }
impl Write for Sink {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> { Ok(buf.len()) }
#[inline]
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
impl fmt::Debug for Sink {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.pad("Sink { .. }")
}
}
#[cfg(test)]
mod tests {
use io::prelude::*;
use io::{copy, sink, empty, repeat};
#[test]
fn copy_copies() {
let mut r = repeat(0).take(4);
let mut w = sink();
assert_eq!(copy(&mut r, &mut w).unwrap(), 4);
let mut r = repeat(0).take(1 << 17);
assert_eq!(copy(&mut r as &mut Read, &mut w as &mut Write).unwrap(), 1 << 17);
}
#[test]
fn sink_sinks() {
let mut s = sink();
assert_eq!(s.write(&[]).unwrap(), 0);
assert_eq!(s.write(&[0]).unwrap(), 1);
assert_eq!(s.write(&[0; 1024]).unwrap(), 1024);
assert_eq!(s.by_ref().write(&[0; 1024]).unwrap(), 1024);
}
#[test]
fn empty_reads() {
let mut e = empty();
assert_eq!(e.read(&mut []).unwrap(), 0);
assert_eq!(e.read(&mut [0]).unwrap(), 0);
assert_eq!(e.read(&mut [0; 1024]).unwrap(), 0);
assert_eq!(e.by_ref().read(&mut [0; 1024]).unwrap(), 0);
}
#[test]
fn repeat_repeats() {
let mut r = repeat(4);
let mut b = [0; 1024];
assert_eq!(r.read(&mut b).unwrap(), 1024);
assert!(b.iter().all(|b| *b == 4));
}
#[test]
fn take_some_bytes() {
assert_eq!(repeat(4).take(100).bytes().count(), 100);
assert_eq!(repeat(4).take(100).bytes().next().unwrap().unwrap(), 4);
assert_eq!(repeat(1).take(10).chain(repeat(2).take(10)).bytes().count(), 20);
}
}

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use crate::io::prelude::*;
use core::cmp;
use crate::io::{self, Error, ErrorKind, Initializer, IoSlice, IoSliceMut, SeekFrom};
#[cfg(feature="collections")] use core::convert::TryInto;
/// A `Cursor` wraps an in-memory buffer and provides it with a
/// [`Seek`] implementation.
///
/// `Cursor`s are used with in-memory buffers, anything implementing
/// `AsRef<[u8]>`, to allow them to implement [`Read`] and/or [`Write`],
/// allowing these buffers to be used anywhere you might use a reader or writer
/// that does actual I/O.
///
/// The standard library implements some I/O traits on various types which
/// are commonly used as a buffer, like `Cursor<`[`Vec`]`<u8>>` and
/// `Cursor<`[`&[u8]`][bytes]`>`.
///
/// # Examples
///
/// We may want to write bytes to a [`File`] in our production
/// code, but use an in-memory buffer in our tests. We can do this with
/// `Cursor`:
///
/// [`Seek`]: trait.Seek.html
/// [`Read`]: ../../std/io/trait.Read.html
/// [`Write`]: ../../std/io/trait.Write.html
/// [`Vec`]: ../../std/vec/struct.Vec.html
/// [bytes]: ../../std/primitive.slice.html
/// [`File`]: ../fs/struct.File.html
///
/// ```no_run
/// use std::io::prelude::*;
/// use std::io::{self, SeekFrom};
/// use std::fs::File;
///
/// // a library function we've written
/// fn write_ten_bytes_at_end<W: Write + Seek>(writer: &mut W) -> io::Result<()> {
/// writer.seek(SeekFrom::End(-10))?;
///
/// for i in 0..10 {
/// writer.write(&[i])?;
/// }
///
/// // all went well
/// Ok(())
/// }
///
/// # fn foo() -> io::Result<()> {
/// // Here's some code that uses this library function.
/// //
/// // We might want to use a BufReader here for efficiency, but let's
/// // keep this example focused.
/// let mut file = File::create("foo.txt")?;
///
/// write_ten_bytes_at_end(&mut file)?;
/// # Ok(())
/// # }
///
/// // now let's write a test
/// #[test]
/// fn test_writes_bytes() {
/// // setting up a real File is much slower than an in-memory buffer,
/// // let's use a cursor instead
/// use std::io::Cursor;
/// let mut buff = Cursor::new(vec![0; 15]);
///
/// write_ten_bytes_at_end(&mut buff).unwrap();
///
/// assert_eq!(&buff.get_ref()[5..15], &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
/// }
/// ```
#[derive(Clone, Debug, Default, Eq, PartialEq)]
pub struct Cursor<T> {
inner: T,
pos: u64,
}
impl<T> Cursor<T> {
/// Creates a new cursor wrapping the provided underlying in-memory buffer.
///
/// Cursor initial position is `0` even if underlying buffer (e.g., `Vec`)
/// is not empty. So writing to cursor starts with overwriting `Vec`
/// content, not with appending to it.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
/// ```
pub fn new(inner: T) -> Cursor<T> {
Cursor { pos: 0, inner }
}
/// Consumes this cursor, returning the underlying value.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
///
/// let vec = buff.into_inner();
/// ```
pub fn into_inner(self) -> T {
self.inner
}
/// Gets a reference to the underlying value in this cursor.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
///
/// let reference = buff.get_ref();
/// ```
pub fn get_ref(&self) -> &T {
&self.inner
}
/// Gets a mutable reference to the underlying value in this cursor.
///
/// Care should be taken to avoid modifying the internal I/O state of the
/// underlying value as it may corrupt this cursor's position.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let mut buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
///
/// let reference = buff.get_mut();
/// ```
pub fn get_mut(&mut self) -> &mut T {
&mut self.inner
}
/// Returns the current position of this cursor.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
/// use std::io::prelude::*;
/// use std::io::SeekFrom;
///
/// let mut buff = Cursor::new(vec![1, 2, 3, 4, 5]);
///
/// assert_eq!(buff.position(), 0);
///
/// buff.seek(SeekFrom::Current(2)).unwrap();
/// assert_eq!(buff.position(), 2);
///
/// buff.seek(SeekFrom::Current(-1)).unwrap();
/// assert_eq!(buff.position(), 1);
/// ```
pub fn position(&self) -> u64 {
self.pos
}
/// Sets the position of this cursor.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let mut buff = Cursor::new(vec![1, 2, 3, 4, 5]);
///
/// assert_eq!(buff.position(), 0);
///
/// buff.set_position(2);
/// assert_eq!(buff.position(), 2);
///
/// buff.set_position(4);
/// assert_eq!(buff.position(), 4);
/// ```
pub fn set_position(&mut self, pos: u64) {
self.pos = pos;
}
}
impl<T> io::Seek for Cursor<T>
where
T: AsRef<[u8]>,
{
fn seek(&mut self, style: SeekFrom) -> io::Result<u64> {
let (base_pos, offset) = match style {
SeekFrom::Start(n) => {
self.pos = n;
return Ok(n);
}
SeekFrom::End(n) => (self.inner.as_ref().len() as u64, n),
SeekFrom::Current(n) => (self.pos, n),
};
let new_pos = if offset >= 0 {
base_pos.checked_add(offset as u64)
} else {
base_pos.checked_sub((offset.wrapping_neg()) as u64)
};
match new_pos {
Some(n) => {
self.pos = n;
Ok(self.pos)
}
None => Err(Error::new(
ErrorKind::InvalidInput,
"invalid seek to a negative or overflowing position",
)),
}
}
fn stream_len(&mut self) -> io::Result<u64> {
Ok(self.inner.as_ref().len() as u64)
}
fn stream_position(&mut self) -> io::Result<u64> {
Ok(self.pos)
}
}
impl<T> Read for Cursor<T>
where
T: AsRef<[u8]>,
{
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
let n = Read::read(&mut self.get_buf()?, buf)?;
self.pos += n as u64;
Ok(n)
}
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
let mut nread = 0;
for buf in bufs {
let n = self.read(buf)?;
nread += n;
if n < buf.len() {
break;
}
}
Ok(nread)
}
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
let n = buf.len();
Read::read_exact(&mut self.get_buf()?, buf)?;
self.pos += n as u64;
Ok(())
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
}
impl<T> Cursor<T>
where
T: AsRef<[u8]>,
{
fn get_buf(&mut self) -> io::Result<&[u8]> {
let amt = cmp::min(self.pos, self.inner.as_ref().len() as u64);
Ok(&self.inner.as_ref()[(amt as usize)..])
}
}
#[cfg(feature="collections")]
impl<T> BufRead for Cursor<T>
where
T: AsRef<[u8]>,
{
fn fill_buf(&mut self) -> io::Result<&[u8]> {
self.get_buf()
}
fn consume(&mut self, amt: usize) {
self.pos += amt as u64;
}
}
// Non-resizing write implementation
#[inline]
fn slice_write(pos_mut: &mut u64, slice: &mut [u8], buf: &[u8]) -> io::Result<usize> {
let pos = cmp::min(*pos_mut, slice.len() as u64);
let amt = (&mut slice[(pos as usize)..]).write(buf)?;
*pos_mut += amt as u64;
Ok(amt)
}
#[inline]
fn slice_write_vectored(
pos_mut: &mut u64,
slice: &mut [u8],
bufs: &[IoSlice<'_>],
) -> io::Result<usize> {
let mut nwritten = 0;
for buf in bufs {
let n = slice_write(pos_mut, slice, buf)?;
nwritten += n;
if n < buf.len() {
break;
}
}
Ok(nwritten)
}
// Resizing write implementation
#[cfg(feature="collections")]
fn vec_write(pos_mut: &mut u64, vec: &mut Vec<u8>, buf: &[u8]) -> io::Result<usize> {
let pos: usize = (*pos_mut).try_into().map_err(|_| {
Error::new(
ErrorKind::InvalidInput,
"cursor position exceeds maximum possible vector length",
)
})?;
// Make sure the internal buffer is as least as big as where we
// currently are
let len = vec.len();
if len < pos {
// use `resize` so that the zero filling is as efficient as possible
vec.resize(pos, 0);
}
// Figure out what bytes will be used to overwrite what's currently
// there (left), and what will be appended on the end (right)
{
let space = vec.len() - pos;
let (left, right) = buf.split_at(cmp::min(space, buf.len()));
vec[pos..pos + left.len()].copy_from_slice(left);
vec.extend_from_slice(right);
}
// Bump us forward
*pos_mut = (pos + buf.len()) as u64;
Ok(buf.len())
}
#[cfg(feature="collections")]
fn vec_write_vectored(
pos_mut: &mut u64,
vec: &mut Vec<u8>,
bufs: &[IoSlice<'_>],
) -> io::Result<usize> {
let mut nwritten = 0;
for buf in bufs {
nwritten += vec_write(pos_mut, vec, buf)?;
}
Ok(nwritten)
}
impl Write for Cursor<&mut [u8]> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
slice_write(&mut self.pos, self.inner, buf)
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
slice_write_vectored(&mut self.pos, self.inner, bufs)
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
#[cfg(feature="collections")]
impl Write for Cursor<&mut Vec<u8>> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
vec_write(&mut self.pos, self.inner, buf)
}
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
vec_write_vectored(&mut self.pos, self.inner, bufs)
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
#[cfg(feature = "collections")]
impl Write for Cursor<Vec<u8>> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
vec_write(&mut self.pos, &mut self.inner, buf)
}
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
vec_write_vectored(&mut self.pos, &mut self.inner, bufs)
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
#[cfg(feature = "alloc")]
impl Write for Cursor<::alloc::boxed::Box<[u8]>> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
slice_write(&mut self.pos, &mut self.inner, buf)
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
slice_write_vectored(&mut self.pos, &mut self.inner, bufs)
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
#[cfg(test)]
mod tests {
use crate::io::prelude::*;
use crate::io::{Cursor, IoSlice, IoSliceMut, SeekFrom};
#[test]
fn test_vec_writer() {
let mut writer = Vec::new();
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(
writer
.write_vectored(&[IoSlice::new(&[]), IoSlice::new(&[8, 9]), IoSlice::new(&[10])],)
.unwrap(),
3
);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
assert_eq!(writer, b);
}
#[test]
fn test_mem_writer() {
let mut writer = Cursor::new(Vec::new());
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(
writer
.write_vectored(&[IoSlice::new(&[]), IoSlice::new(&[8, 9]), IoSlice::new(&[10])],)
.unwrap(),
3
);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
assert_eq!(&writer.get_ref()[..], b);
}
#[test]
fn test_mem_mut_writer() {
let mut vec = Vec::new();
let mut writer = Cursor::new(&mut vec);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(
writer
.write_vectored(&[IoSlice::new(&[]), IoSlice::new(&[8, 9]), IoSlice::new(&[10])],)
.unwrap(),
3
);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
assert_eq!(&writer.get_ref()[..], b);
}
#[test]
fn test_box_slice_writer() {
let mut writer = Cursor::new(vec![0u8; 9].into_boxed_slice());
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[]).unwrap(), 0);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[8, 9]).unwrap(), 1);
assert_eq!(writer.write(&[10]).unwrap(), 0);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8];
assert_eq!(&**writer.get_ref(), b);
}
#[test]
fn test_box_slice_writer_vectored() {
let mut writer = Cursor::new(vec![0u8; 9].into_boxed_slice());
assert_eq!(writer.position(), 0);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[0])]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(
writer
.write_vectored(&[IoSlice::new(&[1, 2, 3]), IoSlice::new(&[4, 5, 6, 7]),])
.unwrap(),
7,
);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write_vectored(&[]).unwrap(), 0);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[8, 9])]).unwrap(), 1);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[10])]).unwrap(), 0);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8];
assert_eq!(&**writer.get_ref(), b);
}
#[test]
fn test_buf_writer() {
let mut buf = [0 as u8; 9];
{
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[]).unwrap(), 0);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[8, 9]).unwrap(), 1);
assert_eq!(writer.write(&[10]).unwrap(), 0);
}
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8];
assert_eq!(buf, b);
}
#[test]
fn test_buf_writer_vectored() {
let mut buf = [0 as u8; 9];
{
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[0])]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(
writer
.write_vectored(&[IoSlice::new(&[1, 2, 3]), IoSlice::new(&[4, 5, 6, 7])],)
.unwrap(),
7,
);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write_vectored(&[]).unwrap(), 0);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[8, 9])]).unwrap(), 1);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[10])]).unwrap(), 0);
}
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8];
assert_eq!(buf, b);
}
#[test]
fn test_buf_writer_seek() {
let mut buf = [0 as u8; 8];
{
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[1]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.seek(SeekFrom::Start(2)).unwrap(), 2);
assert_eq!(writer.position(), 2);
assert_eq!(writer.write(&[2]).unwrap(), 1);
assert_eq!(writer.position(), 3);
assert_eq!(writer.seek(SeekFrom::Current(-2)).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[3]).unwrap(), 1);
assert_eq!(writer.position(), 2);
assert_eq!(writer.seek(SeekFrom::End(-1)).unwrap(), 7);
assert_eq!(writer.position(), 7);
assert_eq!(writer.write(&[4]).unwrap(), 1);
assert_eq!(writer.position(), 8);
}
let b: &[_] = &[1, 3, 2, 0, 0, 0, 0, 4];
assert_eq!(buf, b);
}
#[test]
fn test_buf_writer_error() {
let mut buf = [0 as u8; 2];
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[0, 0]).unwrap(), 1);
assert_eq!(writer.write(&[0, 0]).unwrap(), 0);
}
#[test]
fn test_mem_reader() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7]);
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.position(), 5);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(buf, b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_mem_reader_vectored() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7]);
let mut buf = [];
assert_eq!(reader.read_vectored(&mut [IoSliceMut::new(&mut buf)]).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(
reader
.read_vectored(&mut [IoSliceMut::new(&mut []), IoSliceMut::new(&mut buf),])
.unwrap(),
1,
);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf1 = [0; 4];
let mut buf2 = [0; 4];
assert_eq!(
reader
.read_vectored(&mut [IoSliceMut::new(&mut buf1), IoSliceMut::new(&mut buf2),])
.unwrap(),
7,
);
let b1: &[_] = &[1, 2, 3, 4];
let b2: &[_] = &[5, 6, 7];
assert_eq!(buf1, b1);
assert_eq!(&buf2[..3], b2);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_boxed_slice_reader() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7].into_boxed_slice());
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.position(), 5);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(buf, b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_boxed_slice_reader_vectored() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7].into_boxed_slice());
let mut buf = [];
assert_eq!(reader.read_vectored(&mut [IoSliceMut::new(&mut buf)]).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(
reader
.read_vectored(&mut [IoSliceMut::new(&mut []), IoSliceMut::new(&mut buf),])
.unwrap(),
1,
);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf1 = [0; 4];
let mut buf2 = [0; 4];
assert_eq!(
reader
.read_vectored(&mut [IoSliceMut::new(&mut buf1), IoSliceMut::new(&mut buf2)],)
.unwrap(),
7,
);
let b1: &[_] = &[1, 2, 3, 4];
let b2: &[_] = &[5, 6, 7];
assert_eq!(buf1, b1);
assert_eq!(&buf2[..3], b2);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn read_to_end() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7]);
let mut v = Vec::new();
reader.read_to_end(&mut v).unwrap();
assert_eq!(v, [0, 1, 2, 3, 4, 5, 6, 7]);
}
#[test]
fn test_slice_reader() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let reader = &mut &in_buf[..];
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.len(), 7);
let b: &[_] = &[0];
assert_eq!(&buf[..], b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.len(), 3);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(&buf[..], b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_slice_reader_vectored() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let reader = &mut &in_buf[..];
let mut buf = [];
assert_eq!(reader.read_vectored(&mut [IoSliceMut::new(&mut buf)]).unwrap(), 0);
let mut buf = [0];
assert_eq!(
reader
.read_vectored(&mut [IoSliceMut::new(&mut []), IoSliceMut::new(&mut buf),])
.unwrap(),
1,
);
assert_eq!(reader.len(), 7);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf1 = [0; 4];
let mut buf2 = [0; 4];
assert_eq!(
reader
.read_vectored(&mut [IoSliceMut::new(&mut buf1), IoSliceMut::new(&mut buf2)],)
.unwrap(),
7,
);
let b1: &[_] = &[1, 2, 3, 4];
let b2: &[_] = &[5, 6, 7];
assert_eq!(buf1, b1);
assert_eq!(&buf2[..3], b2);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_read_exact() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let reader = &mut &in_buf[..];
let mut buf = [];
assert!(reader.read_exact(&mut buf).is_ok());
let mut buf = [8];
assert!(reader.read_exact(&mut buf).is_ok());
assert_eq!(buf[0], 0);
assert_eq!(reader.len(), 7);
let mut buf = [0, 0, 0, 0, 0, 0, 0];
assert!(reader.read_exact(&mut buf).is_ok());
assert_eq!(buf, [1, 2, 3, 4, 5, 6, 7]);
assert_eq!(reader.len(), 0);
let mut buf = [0];
assert!(reader.read_exact(&mut buf).is_err());
}
#[test]
fn test_buf_reader() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let mut reader = Cursor::new(&in_buf[..]);
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.position(), 5);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(buf, b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn seek_past_end() {
let buf = [0xff];
let mut r = Cursor::new(&buf[..]);
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.read(&mut [0]).unwrap(), 0);
let mut r = Cursor::new(vec![10]);
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.read(&mut [0]).unwrap(), 0);
let mut buf = [0];
let mut r = Cursor::new(&mut buf[..]);
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.write(&[3]).unwrap(), 0);
let mut r = Cursor::new(vec![10].into_boxed_slice());
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.write(&[3]).unwrap(), 0);
}
#[test]
fn seek_past_i64() {
let buf = [0xff];
let mut r = Cursor::new(&buf[..]);
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
let mut r = Cursor::new(vec![10]);
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
let mut buf = [0];
let mut r = Cursor::new(&mut buf[..]);
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
let mut r = Cursor::new(vec![10].into_boxed_slice());
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
}
#[test]
fn seek_before_0() {
let buf = [0xff];
let mut r = Cursor::new(&buf[..]);
assert!(r.seek(SeekFrom::End(-2)).is_err());
let mut r = Cursor::new(vec![10]);
assert!(r.seek(SeekFrom::End(-2)).is_err());
let mut buf = [0];
let mut r = Cursor::new(&mut buf[..]);
assert!(r.seek(SeekFrom::End(-2)).is_err());
let mut r = Cursor::new(vec![10].into_boxed_slice());
assert!(r.seek(SeekFrom::End(-2)).is_err());
}
#[test]
fn test_seekable_mem_writer() {
let mut writer = Cursor::new(Vec::<u8>::new());
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.position(), 8);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::Start(0)).unwrap(), 0);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[3, 4]).unwrap(), 2);
let b: &[_] = &[3, 4, 2, 3, 4, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::Current(1)).unwrap(), 3);
assert_eq!(writer.write(&[0, 1]).unwrap(), 2);
let b: &[_] = &[3, 4, 2, 0, 1, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::End(-1)).unwrap(), 7);
assert_eq!(writer.write(&[1, 2]).unwrap(), 2);
let b: &[_] = &[3, 4, 2, 0, 1, 5, 6, 1, 2];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::End(1)).unwrap(), 10);
assert_eq!(writer.write(&[1]).unwrap(), 1);
let b: &[_] = &[3, 4, 2, 0, 1, 5, 6, 1, 2, 0, 1];
assert_eq!(&writer.get_ref()[..], b);
}
#[test]
fn vec_seek_past_end() {
let mut r = Cursor::new(Vec::new());
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.write(&[3]).unwrap(), 1);
}
#[test]
fn vec_seek_before_0() {
let mut r = Cursor::new(Vec::new());
assert!(r.seek(SeekFrom::End(-2)).is_err());
}
#[test]
#[cfg(target_pointer_width = "32")]
fn vec_seek_and_write_past_usize_max() {
let mut c = Cursor::new(Vec::new());
c.set_position(<usize>::max_value() as u64 + 1);
assert!(c.write_all(&[1, 2, 3]).is_err());
}
#[test]
fn test_partial_eq() {
assert_eq!(Cursor::new(Vec::<u8>::new()), Cursor::new(Vec::<u8>::new()));
}
#[test]
fn test_eq() {
struct AssertEq<T: Eq>(pub T);
let _: AssertEq<Cursor<Vec<u8>>> = AssertEq(Cursor::new(Vec::new()));
}
}

View File

@ -0,0 +1,552 @@
use core::convert::From;
use core::fmt;
use core::result;
use core::convert::Into;
use core::marker::{Send, Sync};
use core::option::Option::{self, Some, None};
#[cfg(feature="alloc")] use alloc::boxed::Box;
#[cfg(not(feature="alloc"))] use ::FakeBox as Box;
#[cfg(feature="collections")] use collections::string::String;
#[cfg(not(feature="collections"))] use ::ErrorString as String;
/// A specialized [`Result`](../result/enum.Result.html) type for I/O
/// operations.
///
/// This type is broadly used across [`std::io`] for any operation which may
/// produce an error.
///
/// This typedef is generally used to avoid writing out [`io::Error`] directly and
/// is otherwise a direct mapping to [`Result`].
///
/// While usual Rust style is to import types directly, aliases of [`Result`]
/// often are not, to make it easier to distinguish between them. [`Result`] is
/// generally assumed to be [`std::result::Result`][`Result`], and so users of this alias
/// will generally use `io::Result` instead of shadowing the prelude's import
/// of [`std::result::Result`][`Result`].
///
/// [`std::io`]: ../io/index.html
/// [`io::Error`]: ../io/struct.Error.html
/// [`Result`]: ../result/enum.Result.html
///
/// # Examples
///
/// A convenience function that bubbles an `io::Result` to its caller:
///
/// ```
/// use std::io;
///
/// fn get_string() -> io::Result<String> {
/// let mut buffer = String::new();
///
/// io::stdin().read_line(&mut buffer)?;
///
/// Ok(buffer)
/// }
/// ```
pub type Result<T> = result::Result<T, Error>;
/// The error type for I/O operations of the [`Read`], [`Write`], [`Seek`], and
/// associated traits.
///
/// Errors mostly originate from the underlying OS, but custom instances of
/// `Error` can be created with crafted error messages and a particular value of
/// [`ErrorKind`].
///
/// [`Read`]: ../io/trait.Read.html
/// [`Write`]: ../io/trait.Write.html
/// [`Seek`]: ../io/trait.Seek.html
/// [`ErrorKind`]: enum.ErrorKind.html
pub struct Error {
repr: Repr,
}
impl fmt::Debug for Error {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt::Debug::fmt(&self.repr, f)
}
}
enum Repr {
Os(i32),
Simple(ErrorKind),
#[cfg(feature="alloc")]
Custom(Box<Custom>),
#[cfg(not(feature="alloc"))]
Custom(Custom),
}
#[derive(Debug)]
struct Custom {
kind: ErrorKind,
error: String,
}
/// A list specifying general categories of I/O error.
///
/// This list is intended to grow over time and it is not recommended to
/// exhaustively match against it.
///
/// It is used with the [`io::Error`] type.
///
/// [`io::Error`]: struct.Error.html
#[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
#[allow(deprecated)]
#[non_exhaustive]
pub enum ErrorKind {
/// An entity was not found, often a file.
NotFound,
/// The operation lacked the necessary privileges to complete.
PermissionDenied,
/// The connection was refused by the remote server.
ConnectionRefused,
/// The connection was reset by the remote server.
ConnectionReset,
/// The connection was aborted (terminated) by the remote server.
ConnectionAborted,
/// The network operation failed because it was not connected yet.
NotConnected,
/// A socket address could not be bound because the address is already in
/// use elsewhere.
AddrInUse,
/// A nonexistent interface was requested or the requested address was not
/// local.
AddrNotAvailable,
/// The operation failed because a pipe was closed.
BrokenPipe,
/// An entity already exists, often a file.
AlreadyExists,
/// The operation needs to block to complete, but the blocking operation was
/// requested to not occur.
WouldBlock,
/// A parameter was incorrect.
InvalidInput,
/// Data not valid for the operation were encountered.
///
/// Unlike [`InvalidInput`], this typically means that the operation
/// parameters were valid, however the error was caused by malformed
/// input data.
///
/// For example, a function that reads a file into a string will error with
/// `InvalidData` if the file's contents are not valid UTF-8.
///
/// [`InvalidInput`]: #variant.InvalidInput
InvalidData,
/// The I/O operation's timeout expired, causing it to be canceled.
TimedOut,
/// An error returned when an operation could not be completed because a
/// call to [`write`] returned [`Ok(0)`].
///
/// This typically means that an operation could only succeed if it wrote a
/// particular number of bytes but only a smaller number of bytes could be
/// written.
///
/// [`write`]: ../../std/io/trait.Write.html#tymethod.write
/// [`Ok(0)`]: ../../std/io/type.Result.html
WriteZero,
/// This operation was interrupted.
///
/// Interrupted operations can typically be retried.
Interrupted,
/// Any I/O error not part of this list.
Other,
/// An error returned when an operation could not be completed because an
/// "end of file" was reached prematurely.
///
/// This typically means that an operation could only succeed if it read a
/// particular number of bytes but only a smaller number of bytes could be
/// read.
UnexpectedEof,
}
impl ErrorKind {
pub(crate) fn as_str(&self) -> &'static str {
match *self {
ErrorKind::NotFound => "entity not found",
ErrorKind::PermissionDenied => "permission denied",
ErrorKind::ConnectionRefused => "connection refused",
ErrorKind::ConnectionReset => "connection reset",
ErrorKind::ConnectionAborted => "connection aborted",
ErrorKind::NotConnected => "not connected",
ErrorKind::AddrInUse => "address in use",
ErrorKind::AddrNotAvailable => "address not available",
ErrorKind::BrokenPipe => "broken pipe",
ErrorKind::AlreadyExists => "entity already exists",
ErrorKind::WouldBlock => "operation would block",
ErrorKind::InvalidInput => "invalid input parameter",
ErrorKind::InvalidData => "invalid data",
ErrorKind::TimedOut => "timed out",
ErrorKind::WriteZero => "write zero",
ErrorKind::Interrupted => "operation interrupted",
ErrorKind::Other => "other os error",
ErrorKind::UnexpectedEof => "unexpected end of file",
}
}
}
/// Intended for use for errors not exposed to the user, where allocating onto
/// the heap (for normal construction via Error::new) is too costly.
impl From<ErrorKind> for Error {
/// Converts an [`ErrorKind`] into an [`Error`].
///
/// This conversion allocates a new error with a simple representation of error kind.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// let not_found = ErrorKind::NotFound;
/// let error = Error::from(not_found);
/// assert_eq!("entity not found", format!("{}", error));
/// ```
///
/// [`ErrorKind`]: ../../std/io/enum.ErrorKind.html
/// [`Error`]: ../../std/io/struct.Error.html
#[inline]
fn from(kind: ErrorKind) -> Error {
Error { repr: Repr::Simple(kind) }
}
}
impl Error {
/// Creates a new I/O error from a known kind of error as well as an
/// arbitrary error payload.
///
/// This function is used to generically create I/O errors which do not
/// originate from the OS itself. The `error` argument is an arbitrary
/// payload which will be contained in this `Error`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// // errors can be created from strings
/// let custom_error = Error::new(ErrorKind::Other, "oh no!");
///
/// // errors can also be created from other errors
/// let custom_error2 = Error::new(ErrorKind::Interrupted, custom_error);
/// ```
pub fn new<E>(kind: ErrorKind, error: E) -> Error
where
E: Into<String>,
{
Self::_new(kind, error.into())
}
fn _new(kind: ErrorKind, error: String) -> Error {
Error { repr: Repr::Custom(Box::new(Custom { kind, error })) }
}
/// Creates a new instance of an `Error` from a particular OS error code.
///
/// # Examples
///
/// On Linux:
///
/// ```
/// # if cfg!(target_os = "linux") {
/// use std::io;
///
/// let error = io::Error::from_raw_os_error(22);
/// assert_eq!(error.kind(), io::ErrorKind::InvalidInput);
/// # }
/// ```
///
/// On Windows:
///
/// ```
/// # if cfg!(windows) {
/// use std::io;
///
/// let error = io::Error::from_raw_os_error(10022);
/// assert_eq!(error.kind(), io::ErrorKind::InvalidInput);
/// # }
/// ```
pub fn from_raw_os_error(code: i32) -> Error {
Error { repr: Repr::Os(code) }
}
/// Returns the OS error that this error represents (if any).
///
/// If this `Error` was constructed via `last_os_error` or
/// `from_raw_os_error`, then this function will return `Some`, otherwise
/// it will return `None`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_os_error(err: &Error) {
/// if let Some(raw_os_err) = err.raw_os_error() {
/// println!("raw OS error: {:?}", raw_os_err);
/// } else {
/// println!("Not an OS error");
/// }
/// }
///
/// fn main() {
/// // Will print "raw OS error: ...".
/// print_os_error(&Error::last_os_error());
/// // Will print "Not an OS error".
/// print_os_error(&Error::new(ErrorKind::Other, "oh no!"));
/// }
/// ```
pub fn raw_os_error(&self) -> Option<i32> {
match self.repr {
Repr::Os(i) => Some(i),
Repr::Custom(..) => None,
Repr::Simple(..) => None,
}
}
/// Returns a reference to the inner error wrapped by this error (if any).
///
/// If this `Error` was constructed via `new` then this function will
/// return `Some`, otherwise it will return `None`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_error(err: &Error) {
/// if let Some(inner_err) = err.get_ref() {
/// println!("Inner error: {:?}", inner_err);
/// } else {
/// println!("No inner error");
/// }
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(&Error::last_os_error());
/// // Will print "Inner error: ...".
/// print_error(&Error::new(ErrorKind::Other, "oh no!"));
/// }
/// ```
pub fn get_ref(&self) -> Option<&String> {
match self.repr {
Repr::Os(..) => None,
Repr::Simple(..) => None,
Repr::Custom(ref c) => Some(&c.error),
}
}
/// Returns a mutable reference to the inner error wrapped by this error
/// (if any).
///
/// If this `Error` was constructed via `new` then this function will
/// return `Some`, otherwise it will return `None`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
/// use std::{error, fmt};
/// use std::fmt::Display;
///
/// #[derive(Debug)]
/// struct MyError {
/// v: String,
/// }
///
/// impl MyError {
/// fn new() -> MyError {
/// MyError {
/// v: "oh no!".to_string()
/// }
/// }
///
/// fn change_message(&mut self, new_message: &str) {
/// self.v = new_message.to_string();
/// }
/// }
///
/// impl error::Error for MyError {}
///
/// impl Display for MyError {
/// fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
/// write!(f, "MyError: {}", &self.v)
/// }
/// }
///
/// fn change_error(mut err: Error) -> Error {
/// if let Some(inner_err) = err.get_mut() {
/// inner_err.downcast_mut::<MyError>().unwrap().change_message("I've been changed!");
/// }
/// err
/// }
///
/// fn print_error(err: &Error) {
/// if let Some(inner_err) = err.get_ref() {
/// println!("Inner error: {}", inner_err);
/// } else {
/// println!("No inner error");
/// }
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(&change_error(Error::last_os_error()));
/// // Will print "Inner error: ...".
/// print_error(&change_error(Error::new(ErrorKind::Other, MyError::new())));
/// }
/// ```
pub fn get_mut(&mut self) -> Option<&mut String> {
match self.repr {
Repr::Os(..) => None,
Repr::Simple(..) => None,
Repr::Custom(ref mut c) => Some(&mut c.error),
}
}
/// Consumes the `Error`, returning its inner error (if any).
///
/// If this `Error` was constructed via `new` then this function will
/// return `Some`, otherwise it will return `None`.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_error(err: Error) {
/// if let Some(inner_err) = err.into_inner() {
/// println!("Inner error: {}", inner_err);
/// } else {
/// println!("No inner error");
/// }
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(Error::last_os_error());
/// // Will print "Inner error: ...".
/// print_error(Error::new(ErrorKind::Other, "oh no!"));
/// }
/// ```
pub fn into_inner(self) -> Option<String> {
match self.repr {
Repr::Os(..) => None,
Repr::Simple(..) => None,
Repr::Custom(c) => Some(c.error),
}
}
/// Returns the corresponding `ErrorKind` for this error.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_error(err: Error) {
/// println!("{:?}", err.kind());
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(Error::last_os_error());
/// // Will print "Inner error: ...".
/// print_error(Error::new(ErrorKind::AddrInUse, "oh no!"));
/// }
/// ```
pub fn kind(&self) -> ErrorKind {
match self.repr {
Repr::Os(_code) => ErrorKind::Other,
Repr::Custom(ref c) => c.kind,
Repr::Simple(kind) => kind,
}
}
}
impl fmt::Debug for Repr {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
match *self {
Repr::Os(code) => fmt
.debug_struct("Os")
.field("code", &code)
.finish(),
Repr::Custom(ref c) => fmt::Debug::fmt(&c, fmt),
Repr::Simple(kind) => fmt.debug_tuple("Kind").field(&kind).finish(),
}
}
}
impl fmt::Display for Error {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
match self.repr {
Repr::Os(code) => {
write!(fmt, "os error {}", code)
}
Repr::Custom(ref c) => c.error.fmt(fmt),
Repr::Simple(kind) => write!(fmt, "{}", kind.as_str()),
}
}
}
fn _assert_error_is_sync_send() {
fn _is_sync_send<T: Sync + Send>() {}
_is_sync_send::<Error>();
}
#[cfg(test)]
mod test {
use super::{Custom, Error, ErrorKind, Repr};
use crate::error;
use crate::fmt;
use crate::sys::decode_error_kind;
use crate::sys::os::error_string;
#[test]
fn test_debug_error() {
let code = 6;
let msg = error_string(code);
let kind = decode_error_kind(code);
let err = Error {
repr: Repr::Custom(box Custom {
kind: ErrorKind::InvalidInput,
error: box Error { repr: super::Repr::Os(code) },
}),
};
let expected = format!(
"Custom {{ \
kind: InvalidInput, \
error: Os {{ \
code: {:?}, \
kind: {:?}, \
message: {:?} \
}} \
}}",
code, kind, msg
);
assert_eq!(format!("{:?}", err), expected);
}
#[test]
fn test_downcasting() {
#[derive(Debug)]
struct TestError;
impl fmt::Display for TestError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.write_str("asdf")
}
}
impl error::Error for TestError {}
// we have to call all of these UFCS style right now since method
// resolution won't implicitly drop the Send+Sync bounds
let mut err = Error::new(ErrorKind::Other, TestError);
assert!(err.get_ref().unwrap().is::<TestError>());
assert_eq!("asdf", err.get_ref().unwrap().to_string());
assert!(err.get_mut().unwrap().is::<TestError>());
let extracted = err.into_inner().unwrap();
extracted.downcast::<TestError>().unwrap();
}
}

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@ -0,0 +1,430 @@
use core::cmp;
use core::fmt;
use crate::io::{
self, Error, ErrorKind, Initializer, IoSlice, IoSliceMut, Read, Seek, SeekFrom, Write,
};
#[cfg(feature="collections")] use crate::io::BufRead;
use core::mem;
#[cfg(feature="alloc")] use alloc::boxed::Box;
#[cfg(feature="collections")] use collections::string::String;
#[cfg(feature="collections")] use collections::vec::Vec;
// =============================================================================
// Forwarding implementations
impl<R: Read + ?Sized> Read for &mut R {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
(**self).read(buf)
}
#[inline]
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
(**self).read_vectored(bufs)
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
(**self).initializer()
}
#[cfg(feature="collections")]
#[inline]
fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_to_end(buf)
}
#[cfg(feature="collections")]
#[inline]
fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_to_string(buf)
}
#[inline]
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
(**self).read_exact(buf)
}
}
impl<W: Write + ?Sized> Write for &mut W {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
(**self).write(buf)
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
(**self).write_vectored(bufs)
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
(**self).flush()
}
#[inline]
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
(**self).write_all(buf)
}
#[inline]
fn write_fmt(&mut self, fmt: fmt::Arguments<'_>) -> io::Result<()> {
(**self).write_fmt(fmt)
}
}
impl<S: Seek + ?Sized> Seek for &mut S {
#[inline]
fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
(**self).seek(pos)
}
}
#[cfg(feature="collections")]
impl<B: BufRead + ?Sized> BufRead for &mut B {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> {
(**self).fill_buf()
}
#[inline]
fn consume(&mut self, amt: usize) {
(**self).consume(amt)
}
#[inline]
fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_until(byte, buf)
}
#[inline]
fn read_line(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_line(buf)
}
}
#[cfg(feature="alloc")]
impl<R: Read + ?Sized> Read for Box<R> {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
(**self).read(buf)
}
#[inline]
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
(**self).read_vectored(bufs)
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
(**self).initializer()
}
#[cfg(feature="collections")]
#[inline]
fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_to_end(buf)
}
#[cfg(feature="collections")]
#[inline]
fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_to_string(buf)
}
#[inline]
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
(**self).read_exact(buf)
}
}
#[cfg(feature="alloc")]
impl<W: Write + ?Sized> Write for Box<W> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
(**self).write(buf)
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
(**self).write_vectored(bufs)
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
(**self).flush()
}
#[inline]
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
(**self).write_all(buf)
}
#[inline]
fn write_fmt(&mut self, fmt: fmt::Arguments<'_>) -> io::Result<()> {
(**self).write_fmt(fmt)
}
}
#[cfg(feature="alloc")]
impl<S: Seek + ?Sized> Seek for Box<S> {
#[inline]
fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
(**self).seek(pos)
}
}
#[cfg(feature="collections")]
impl<B: BufRead + ?Sized> BufRead for Box<B> {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> {
(**self).fill_buf()
}
#[inline]
fn consume(&mut self, amt: usize) {
(**self).consume(amt)
}
#[inline]
fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_until(byte, buf)
}
#[inline]
fn read_line(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_line(buf)
}
}
// Used by panicking::default_hook
#[cfg(test)]
/// This impl is only used by printing logic, so any error returned is always
/// of kind `Other`, and should be ignored.
impl Write for Box<dyn (::realstd::io::Write) + Send> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
(**self).write(buf).map_err(|_| ErrorKind::Other.into())
}
fn flush(&mut self) -> io::Result<()> {
(**self).flush().map_err(|_| ErrorKind::Other.into())
}
}
// =============================================================================
// In-memory buffer implementations
/// Read is implemented for `&[u8]` by copying from the slice.
///
/// Note that reading updates the slice to point to the yet unread part.
/// The slice will be empty when EOF is reached.
impl Read for &[u8] {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
let amt = cmp::min(buf.len(), self.len());
let (a, b) = self.split_at(amt);
// First check if the amount of bytes we want to read is small:
// `copy_from_slice` will generally expand to a call to `memcpy`, and
// for a single byte the overhead is significant.
if amt == 1 {
buf[0] = a[0];
} else {
buf[..amt].copy_from_slice(a);
}
*self = b;
Ok(amt)
}
#[inline]
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
let mut nread = 0;
for buf in bufs {
nread += self.read(buf)?;
if self.is_empty() {
break;
}
}
Ok(nread)
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
#[inline]
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
if buf.len() > self.len() {
return Err(Error::new(ErrorKind::UnexpectedEof, "failed to fill whole buffer"));
}
let (a, b) = self.split_at(buf.len());
// First check if the amount of bytes we want to read is small:
// `copy_from_slice` will generally expand to a call to `memcpy`, and
// for a single byte the overhead is significant.
if buf.len() == 1 {
buf[0] = a[0];
} else {
buf.copy_from_slice(a);
}
*self = b;
Ok(())
}
#[cfg(feature="collections")]
#[inline]
fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
buf.extend_from_slice(*self);
let len = self.len();
*self = &self[len..];
Ok(len)
}
}
#[cfg(feature="collections")]
impl BufRead for &[u8] {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> {
Ok(*self)
}
#[inline]
fn consume(&mut self, amt: usize) {
*self = &self[amt..];
}
}
/// Write is implemented for `&mut [u8]` by copying into the slice, overwriting
/// its data.
///
/// Note that writing updates the slice to point to the yet unwritten part.
/// The slice will be empty when it has been completely overwritten.
impl Write for &mut [u8] {
#[inline]
fn write(&mut self, data: &[u8]) -> io::Result<usize> {
let amt = cmp::min(data.len(), self.len());
let (a, b) = mem::replace(self, &mut []).split_at_mut(amt);
a.copy_from_slice(&data[..amt]);
*self = b;
Ok(amt)
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
let mut nwritten = 0;
for buf in bufs {
nwritten += self.write(buf)?;
if self.is_empty() {
break;
}
}
Ok(nwritten)
}
#[inline]
fn write_all(&mut self, data: &[u8]) -> io::Result<()> {
if self.write(data)? == data.len() {
Ok(())
} else {
Err(Error::new(ErrorKind::WriteZero, "failed to write whole buffer"))
}
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
/// Write is implemented for `Vec<u8>` by appending to the vector.
/// The vector will grow as needed.
#[cfg(feature="collections")]
impl Write for Vec<u8> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
self.extend_from_slice(buf);
Ok(buf.len())
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
let len = bufs.iter().map(|b| b.len()).sum();
self.reserve(len);
for buf in bufs {
self.extend_from_slice(buf);
}
Ok(len)
}
#[inline]
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
self.extend_from_slice(buf);
Ok(())
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
#[cfg(test)]
mod tests {
use crate::io::prelude::*;
#[bench]
fn bench_read_slice(b: &mut test::Bencher) {
let buf = [5; 1024];
let mut dst = [0; 128];
b.iter(|| {
let mut rd = &buf[..];
for _ in 0..8 {
let _ = rd.read(&mut dst);
test::black_box(&dst);
}
})
}
#[bench]
fn bench_write_slice(b: &mut test::Bencher) {
let mut buf = [0; 1024];
let src = [5; 128];
b.iter(|| {
let mut wr = &mut buf[..];
for _ in 0..8 {
let _ = wr.write_all(&src);
test::black_box(&wr);
}
})
}
#[bench]
fn bench_read_vec(b: &mut test::Bencher) {
let buf = vec![5; 1024];
let mut dst = [0; 128];
b.iter(|| {
let mut rd = &buf[..];
for _ in 0..8 {
let _ = rd.read(&mut dst);
test::black_box(&dst);
}
})
}
#[bench]
fn bench_write_vec(b: &mut test::Bencher) {
let mut buf = Vec::with_capacity(1024);
let src = [5; 128];
b.iter(|| {
let mut wr = &mut buf[..];
for _ in 0..8 {
let _ = wr.write_all(&src);
test::black_box(&wr);
}
})
}
}

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//! The I/O Prelude
//!
//! The purpose of this module is to alleviate imports of many common I/O traits
//! by adding a glob import to the top of I/O heavy modules:
//!
//! ```
//! # #![allow(unused_imports)]
//! use std::io::prelude::*;
//! ```
pub use super::{Read, Seek, Write};
#[cfg(feature="collections")] pub use super::BufRead;
#[cfg(feature="collections")] pub use alloc::boxed::Box;
#[cfg(feature="collections")] pub use collections::vec::Vec;

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#![allow(missing_copy_implementations)]
use core::fmt;
use crate::io::{self, ErrorKind, Initializer, IoSlice, IoSliceMut, Read, Write};
#[cfg(feature="collections")] use crate::io::BufRead;
use core::mem::MaybeUninit;
/// Copies the entire contents of a reader into a writer.
///
/// This function will continuously read data from `reader` and then
/// write it into `writer` in a streaming fashion until `reader`
/// returns EOF.
///
/// On success, the total number of bytes that were copied from
/// `reader` to `writer` is returned.
///
/// If youre wanting to copy the contents of one file to another and youre
/// working with filesystem paths, see the [`fs::copy`] function.
///
/// [`fs::copy`]: ../fs/fn.copy.html
///
/// # Errors
///
/// This function will return an error immediately if any call to `read` or
/// `write` returns an error. All instances of `ErrorKind::Interrupted` are
/// handled by this function and the underlying operation is retried.
///
/// # Examples
///
/// ```
/// use std::io;
///
/// fn main() -> io::Result<()> {
/// let mut reader: &[u8] = b"hello";
/// let mut writer: Vec<u8> = vec![];
///
/// io::copy(&mut reader, &mut writer)?;
///
/// assert_eq!(&b"hello"[..], &writer[..]);
/// Ok(())
/// }
/// ```
pub fn copy<R: ?Sized, W: ?Sized>(reader: &mut R, writer: &mut W) -> io::Result<u64>
where
R: Read,
W: Write,
{
let mut buf = MaybeUninit::<[u8; super::DEFAULT_BUF_SIZE]>::uninit();
// FIXME(#53491): This is calling `get_mut` and `get_ref` on an uninitialized
// `MaybeUninit`. Revisit this once we decided whether that is valid or not.
// This is still technically undefined behavior due to creating a reference
// to uninitialized data, but within libstd we can rely on more guarantees
// than if this code were in an external lib.
unsafe {
reader.initializer().initialize(buf.get_mut());
}
let mut written = 0;
loop {
let len = match reader.read(unsafe { buf.get_mut() }) {
Ok(0) => return Ok(written),
Ok(len) => len,
Err(ref e) if e.kind() == ErrorKind::Interrupted => continue,
Err(e) => return Err(e),
};
writer.write_all(unsafe { &buf.get_ref()[..len] })?;
written += len as u64;
}
}
/// A reader which is always at EOF.
///
/// This struct is generally created by calling [`empty`]. Please see
/// the documentation of [`empty()`][`empty`] for more details.
///
/// [`empty`]: fn.empty.html
pub struct Empty {
_priv: (),
}
/// Constructs a new handle to an empty reader.
///
/// All reads from the returned reader will return [`Ok`]`(0)`.
///
/// [`Ok`]: ../result/enum.Result.html#variant.Ok
///
/// # Examples
///
/// A slightly sad example of not reading anything into a buffer:
///
/// ```
/// use std::io::{self, Read};
///
/// let mut buffer = String::new();
/// io::empty().read_to_string(&mut buffer).unwrap();
/// assert!(buffer.is_empty());
/// ```
pub fn empty() -> Empty {
Empty { _priv: () }
}
impl Read for Empty {
#[inline]
fn read(&mut self, _buf: &mut [u8]) -> io::Result<usize> {
Ok(0)
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
}
#[cfg(feature="collections")]
impl BufRead for Empty {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> {
Ok(&[])
}
#[inline]
fn consume(&mut self, _n: usize) {}
}
impl fmt::Debug for Empty {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.pad("Empty { .. }")
}
}
/// A reader which yields one byte over and over and over and over and over and...
///
/// This struct is generally created by calling [`repeat`][repeat]. Please
/// see the documentation of `repeat()` for more details.
///
/// [repeat]: fn.repeat.html
pub struct Repeat {
byte: u8,
}
/// Creates an instance of a reader that infinitely repeats one byte.
///
/// All reads from this reader will succeed by filling the specified buffer with
/// the given byte.
///
/// # Examples
///
/// ```
/// use std::io::{self, Read};
///
/// let mut buffer = [0; 3];
/// io::repeat(0b101).read_exact(&mut buffer).unwrap();
/// assert_eq!(buffer, [0b101, 0b101, 0b101]);
/// ```
pub fn repeat(byte: u8) -> Repeat {
Repeat { byte }
}
impl Read for Repeat {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
for slot in &mut *buf {
*slot = self.byte;
}
Ok(buf.len())
}
#[inline]
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
let mut nwritten = 0;
for buf in bufs {
nwritten += self.read(buf)?;
}
Ok(nwritten)
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
}
impl fmt::Debug for Repeat {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.pad("Repeat { .. }")
}
}
/// A writer which will move data into the void.
///
/// This struct is generally created by calling [`sink`][sink]. Please
/// see the documentation of `sink()` for more details.
///
/// [sink]: fn.sink.html
pub struct Sink {
_priv: (),
}
/// Creates an instance of a writer which will successfully consume all data.
///
/// All calls to `write` on the returned instance will return `Ok(buf.len())`
/// and the contents of the buffer will not be inspected.
///
/// # Examples
///
/// ```rust
/// use std::io::{self, Write};
///
/// let buffer = vec![1, 2, 3, 5, 8];
/// let num_bytes = io::sink().write(&buffer).unwrap();
/// assert_eq!(num_bytes, 5);
/// ```
pub fn sink() -> Sink {
Sink { _priv: () }
}
impl Write for Sink {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
Ok(buf.len())
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
let total_len = bufs.iter().map(|b| b.len()).sum();
Ok(total_len)
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
impl fmt::Debug for Sink {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.pad("Sink { .. }")
}
}
#[cfg(test)]
mod tests {
use crate::io::prelude::*;
use crate::io::{copy, empty, repeat, sink};
#[test]
fn copy_copies() {
let mut r = repeat(0).take(4);
let mut w = sink();
assert_eq!(copy(&mut r, &mut w).unwrap(), 4);
let mut r = repeat(0).take(1 << 17);
assert_eq!(copy(&mut r as &mut dyn Read, &mut w as &mut dyn Write).unwrap(), 1 << 17);
}
#[test]
fn sink_sinks() {
let mut s = sink();
assert_eq!(s.write(&[]).unwrap(), 0);
assert_eq!(s.write(&[0]).unwrap(), 1);
assert_eq!(s.write(&[0; 1024]).unwrap(), 1024);
assert_eq!(s.by_ref().write(&[0; 1024]).unwrap(), 1024);
}
#[test]
fn empty_reads() {
let mut e = empty();
assert_eq!(e.read(&mut []).unwrap(), 0);
assert_eq!(e.read(&mut [0]).unwrap(), 0);
assert_eq!(e.read(&mut [0; 1024]).unwrap(), 0);
assert_eq!(e.by_ref().read(&mut [0; 1024]).unwrap(), 0);
}
#[test]
fn repeat_repeats() {
let mut r = repeat(4);
let mut b = [0; 1024];
assert_eq!(r.read(&mut b).unwrap(), 1024);
assert!(b.iter().all(|b| *b == 4));
}
#[test]
fn take_some_bytes() {
assert_eq!(repeat(4).take(100).bytes().count(), 100);
assert_eq!(repeat(4).take(100).bytes().next().unwrap().unwrap(), 4);
assert_eq!(repeat(1).take(10).chain(repeat(2).take(10)).bytes().count(), 20);
}
}

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use crate::io::prelude::*;
use crate::io::{self, BufReader, BufWriter, ErrorKind, IoSlice, LineWriter, SeekFrom};
use crate::sync::atomic::{AtomicUsize, Ordering};
use crate::thread;
/// A dummy reader intended at testing short-reads propagation.
pub struct ShortReader {
lengths: Vec<usize>,
}
// FIXME: rustfmt and tidy disagree about the correct formatting of this
// function. This leads to issues for users with editors configured to
// rustfmt-on-save.
impl Read for ShortReader {
fn read(&mut self, _: &mut [u8]) -> io::Result<usize> {
if self.lengths.is_empty() { Ok(0) } else { Ok(self.lengths.remove(0)) }
}
}
#[test]
fn test_buffered_reader() {
let inner: &[u8] = &[5, 6, 7, 0, 1, 2, 3, 4];
let mut reader = BufReader::with_capacity(2, inner);
let mut buf = [0, 0, 0];
let nread = reader.read(&mut buf);
assert_eq!(nread.unwrap(), 3);
assert_eq!(buf, [5, 6, 7]);
assert_eq!(reader.buffer(), []);
let mut buf = [0, 0];
let nread = reader.read(&mut buf);
assert_eq!(nread.unwrap(), 2);
assert_eq!(buf, [0, 1]);
assert_eq!(reader.buffer(), []);
let mut buf = [0];
let nread = reader.read(&mut buf);
assert_eq!(nread.unwrap(), 1);
assert_eq!(buf, [2]);
assert_eq!(reader.buffer(), [3]);
let mut buf = [0, 0, 0];
let nread = reader.read(&mut buf);
assert_eq!(nread.unwrap(), 1);
assert_eq!(buf, [3, 0, 0]);
assert_eq!(reader.buffer(), []);
let nread = reader.read(&mut buf);
assert_eq!(nread.unwrap(), 1);
assert_eq!(buf, [4, 0, 0]);
assert_eq!(reader.buffer(), []);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_buffered_reader_seek() {
let inner: &[u8] = &[5, 6, 7, 0, 1, 2, 3, 4];
let mut reader = BufReader::with_capacity(2, io::Cursor::new(inner));
assert_eq!(reader.seek(SeekFrom::Start(3)).ok(), Some(3));
assert_eq!(reader.fill_buf().ok(), Some(&[0, 1][..]));
assert_eq!(reader.seek(SeekFrom::Current(0)).ok(), Some(3));
assert_eq!(reader.fill_buf().ok(), Some(&[0, 1][..]));
assert_eq!(reader.seek(SeekFrom::Current(1)).ok(), Some(4));
assert_eq!(reader.fill_buf().ok(), Some(&[1, 2][..]));
reader.consume(1);
assert_eq!(reader.seek(SeekFrom::Current(-2)).ok(), Some(3));
}
#[test]
fn test_buffered_reader_seek_relative() {
let inner: &[u8] = &[5, 6, 7, 0, 1, 2, 3, 4];
let mut reader = BufReader::with_capacity(2, io::Cursor::new(inner));
assert!(reader.seek_relative(3).is_ok());
assert_eq!(reader.fill_buf().ok(), Some(&[0, 1][..]));
assert!(reader.seek_relative(0).is_ok());
assert_eq!(reader.fill_buf().ok(), Some(&[0, 1][..]));
assert!(reader.seek_relative(1).is_ok());
assert_eq!(reader.fill_buf().ok(), Some(&[1][..]));
assert!(reader.seek_relative(-1).is_ok());
assert_eq!(reader.fill_buf().ok(), Some(&[0, 1][..]));
assert!(reader.seek_relative(2).is_ok());
assert_eq!(reader.fill_buf().ok(), Some(&[2, 3][..]));
}
#[test]
fn test_buffered_reader_invalidated_after_read() {
let inner: &[u8] = &[5, 6, 7, 0, 1, 2, 3, 4];
let mut reader = BufReader::with_capacity(3, io::Cursor::new(inner));
assert_eq!(reader.fill_buf().ok(), Some(&[5, 6, 7][..]));
reader.consume(3);
let mut buffer = [0, 0, 0, 0, 0];
assert_eq!(reader.read(&mut buffer).ok(), Some(5));
assert_eq!(buffer, [0, 1, 2, 3, 4]);
assert!(reader.seek_relative(-2).is_ok());
let mut buffer = [0, 0];
assert_eq!(reader.read(&mut buffer).ok(), Some(2));
assert_eq!(buffer, [3, 4]);
}
#[test]
fn test_buffered_reader_invalidated_after_seek() {
let inner: &[u8] = &[5, 6, 7, 0, 1, 2, 3, 4];
let mut reader = BufReader::with_capacity(3, io::Cursor::new(inner));
assert_eq!(reader.fill_buf().ok(), Some(&[5, 6, 7][..]));
reader.consume(3);
assert!(reader.seek(SeekFrom::Current(5)).is_ok());
assert!(reader.seek_relative(-2).is_ok());
let mut buffer = [0, 0];
assert_eq!(reader.read(&mut buffer).ok(), Some(2));
assert_eq!(buffer, [3, 4]);
}
#[test]
fn test_buffered_reader_seek_underflow() {
// gimmick reader that yields its position modulo 256 for each byte
struct PositionReader {
pos: u64,
}
impl Read for PositionReader {
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
let len = buf.len();
for x in buf {
*x = self.pos as u8;
self.pos = self.pos.wrapping_add(1);
}
Ok(len)
}
}
impl Seek for PositionReader {
fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
match pos {
SeekFrom::Start(n) => {
self.pos = n;
}
SeekFrom::Current(n) => {
self.pos = self.pos.wrapping_add(n as u64);
}
SeekFrom::End(n) => {
self.pos = u64::MAX.wrapping_add(n as u64);
}
}
Ok(self.pos)
}
}
let mut reader = BufReader::with_capacity(5, PositionReader { pos: 0 });
assert_eq!(reader.fill_buf().ok(), Some(&[0, 1, 2, 3, 4][..]));
assert_eq!(reader.seek(SeekFrom::End(-5)).ok(), Some(u64::MAX - 5));
assert_eq!(reader.fill_buf().ok().map(|s| s.len()), Some(5));
// the following seek will require two underlying seeks
let expected = 9223372036854775802;
assert_eq!(reader.seek(SeekFrom::Current(i64::MIN)).ok(), Some(expected));
assert_eq!(reader.fill_buf().ok().map(|s| s.len()), Some(5));
// seeking to 0 should empty the buffer.
assert_eq!(reader.seek(SeekFrom::Current(0)).ok(), Some(expected));
assert_eq!(reader.get_ref().pos, expected);
}
#[test]
fn test_buffered_reader_seek_underflow_discard_buffer_between_seeks() {
// gimmick reader that returns Err after first seek
struct ErrAfterFirstSeekReader {
first_seek: bool,
}
impl Read for ErrAfterFirstSeekReader {
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
for x in &mut *buf {
*x = 0;
}
Ok(buf.len())
}
}
impl Seek for ErrAfterFirstSeekReader {
fn seek(&mut self, _: SeekFrom) -> io::Result<u64> {
if self.first_seek {
self.first_seek = false;
Ok(0)
} else {
Err(io::Error::new(io::ErrorKind::Other, "oh no!"))
}
}
}
let mut reader = BufReader::with_capacity(5, ErrAfterFirstSeekReader { first_seek: true });
assert_eq!(reader.fill_buf().ok(), Some(&[0, 0, 0, 0, 0][..]));
// The following seek will require two underlying seeks. The first will
// succeed but the second will fail. This should still invalidate the
// buffer.
assert!(reader.seek(SeekFrom::Current(i64::MIN)).is_err());
assert_eq!(reader.buffer().len(), 0);
}
#[test]
fn test_buffered_writer() {
let inner = Vec::new();
let mut writer = BufWriter::with_capacity(2, inner);
writer.write(&[0, 1]).unwrap();
assert_eq!(writer.buffer(), []);
assert_eq!(*writer.get_ref(), [0, 1]);
writer.write(&[2]).unwrap();
assert_eq!(writer.buffer(), [2]);
assert_eq!(*writer.get_ref(), [0, 1]);
writer.write(&[3]).unwrap();
assert_eq!(writer.buffer(), [2, 3]);
assert_eq!(*writer.get_ref(), [0, 1]);
writer.flush().unwrap();
assert_eq!(writer.buffer(), []);
assert_eq!(*writer.get_ref(), [0, 1, 2, 3]);
writer.write(&[4]).unwrap();
writer.write(&[5]).unwrap();
assert_eq!(writer.buffer(), [4, 5]);
assert_eq!(*writer.get_ref(), [0, 1, 2, 3]);
writer.write(&[6]).unwrap();
assert_eq!(writer.buffer(), [6]);
assert_eq!(*writer.get_ref(), [0, 1, 2, 3, 4, 5]);
writer.write(&[7, 8]).unwrap();
assert_eq!(writer.buffer(), []);
assert_eq!(*writer.get_ref(), [0, 1, 2, 3, 4, 5, 6, 7, 8]);
writer.write(&[9, 10, 11]).unwrap();
assert_eq!(writer.buffer(), []);
assert_eq!(*writer.get_ref(), [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]);
writer.flush().unwrap();
assert_eq!(writer.buffer(), []);
assert_eq!(*writer.get_ref(), [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]);
}
#[test]
fn test_buffered_writer_inner_flushes() {
let mut w = BufWriter::with_capacity(3, Vec::new());
w.write(&[0, 1]).unwrap();
assert_eq!(*w.get_ref(), []);
let w = w.into_inner().unwrap();
assert_eq!(w, [0, 1]);
}
#[test]
fn test_buffered_writer_seek() {
let mut w = BufWriter::with_capacity(3, io::Cursor::new(Vec::new()));
w.write_all(&[0, 1, 2, 3, 4, 5]).unwrap();
w.write_all(&[6, 7]).unwrap();
assert_eq!(w.seek(SeekFrom::Current(0)).ok(), Some(8));
assert_eq!(&w.get_ref().get_ref()[..], &[0, 1, 2, 3, 4, 5, 6, 7][..]);
assert_eq!(w.seek(SeekFrom::Start(2)).ok(), Some(2));
w.write_all(&[8, 9]).unwrap();
assert_eq!(&w.into_inner().unwrap().into_inner()[..], &[0, 1, 8, 9, 4, 5, 6, 7]);
}
#[test]
fn test_read_until() {
let inner: &[u8] = &[0, 1, 2, 1, 0];
let mut reader = BufReader::with_capacity(2, inner);
let mut v = Vec::new();
reader.read_until(0, &mut v).unwrap();
assert_eq!(v, [0]);
v.truncate(0);
reader.read_until(2, &mut v).unwrap();
assert_eq!(v, [1, 2]);
v.truncate(0);
reader.read_until(1, &mut v).unwrap();
assert_eq!(v, [1]);
v.truncate(0);
reader.read_until(8, &mut v).unwrap();
assert_eq!(v, [0]);
v.truncate(0);
reader.read_until(9, &mut v).unwrap();
assert_eq!(v, []);
}
#[test]
fn test_line_buffer() {
let mut writer = LineWriter::new(Vec::new());
writer.write(&[0]).unwrap();
assert_eq!(*writer.get_ref(), []);
writer.write(&[1]).unwrap();
assert_eq!(*writer.get_ref(), []);
writer.flush().unwrap();
assert_eq!(*writer.get_ref(), [0, 1]);
writer.write(&[0, b'\n', 1, b'\n', 2]).unwrap();
assert_eq!(*writer.get_ref(), [0, 1, 0, b'\n', 1, b'\n']);
writer.flush().unwrap();
assert_eq!(*writer.get_ref(), [0, 1, 0, b'\n', 1, b'\n', 2]);
writer.write(&[3, b'\n']).unwrap();
assert_eq!(*writer.get_ref(), [0, 1, 0, b'\n', 1, b'\n', 2, 3, b'\n']);
}
#[test]
fn test_read_line() {
let in_buf: &[u8] = b"a\nb\nc";
let mut reader = BufReader::with_capacity(2, in_buf);
let mut s = String::new();
reader.read_line(&mut s).unwrap();
assert_eq!(s, "a\n");
s.truncate(0);
reader.read_line(&mut s).unwrap();
assert_eq!(s, "b\n");
s.truncate(0);
reader.read_line(&mut s).unwrap();
assert_eq!(s, "c");
s.truncate(0);
reader.read_line(&mut s).unwrap();
assert_eq!(s, "");
}
#[test]
fn test_lines() {
let in_buf: &[u8] = b"a\nb\nc";
let reader = BufReader::with_capacity(2, in_buf);
let mut it = reader.lines();
assert_eq!(it.next().unwrap().unwrap(), "a".to_string());
assert_eq!(it.next().unwrap().unwrap(), "b".to_string());
assert_eq!(it.next().unwrap().unwrap(), "c".to_string());
assert!(it.next().is_none());
}
#[test]
fn test_short_reads() {
let inner = ShortReader { lengths: vec![0, 1, 2, 0, 1, 0] };
let mut reader = BufReader::new(inner);
let mut buf = [0, 0];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.read(&mut buf).unwrap(), 2);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
#[should_panic]
fn dont_panic_in_drop_on_panicked_flush() {
struct FailFlushWriter;
impl Write for FailFlushWriter {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
Ok(buf.len())
}
fn flush(&mut self) -> io::Result<()> {
Err(io::Error::last_os_error())
}
}
let writer = FailFlushWriter;
let _writer = BufWriter::new(writer);
// If writer panics *again* due to the flush error then the process will
// abort.
panic!();
}
#[test]
#[cfg_attr(target_os = "emscripten", ignore)]
fn panic_in_write_doesnt_flush_in_drop() {
static WRITES: AtomicUsize = AtomicUsize::new(0);
struct PanicWriter;
impl Write for PanicWriter {
fn write(&mut self, _: &[u8]) -> io::Result<usize> {
WRITES.fetch_add(1, Ordering::SeqCst);
panic!();
}
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
thread::spawn(|| {
let mut writer = BufWriter::new(PanicWriter);
let _ = writer.write(b"hello world");
let _ = writer.flush();
})
.join()
.unwrap_err();
assert_eq!(WRITES.load(Ordering::SeqCst), 1);
}
#[bench]
fn bench_buffered_reader(b: &mut test::Bencher) {
b.iter(|| BufReader::new(io::empty()));
}
#[bench]
fn bench_buffered_writer(b: &mut test::Bencher) {
b.iter(|| BufWriter::new(io::sink()));
}
/// A simple `Write` target, designed to be wrapped by `LineWriter` /
/// `BufWriter` / etc, that can have its `write` & `flush` behavior
/// configured
#[derive(Default, Clone)]
struct ProgrammableSink {
// Writes append to this slice
pub buffer: Vec<u8>,
// Flush sets this flag
pub flushed: bool,
// If true, writes will always be an error
pub always_write_error: bool,
// If true, flushes will always be an error
pub always_flush_error: bool,
// If set, only up to this number of bytes will be written in a single
// call to `write`
pub accept_prefix: Option<usize>,
// If set, counts down with each write, and writes return an error
// when it hits 0
pub max_writes: Option<usize>,
// If set, attempting to write when max_writes == Some(0) will be an
// error; otherwise, it will return Ok(0).
pub error_after_max_writes: bool,
}
impl Write for ProgrammableSink {
fn write(&mut self, data: &[u8]) -> io::Result<usize> {
if self.always_write_error {
return Err(io::Error::new(io::ErrorKind::Other, "test - always_write_error"));
}
match self.max_writes {
Some(0) if self.error_after_max_writes => {
return Err(io::Error::new(io::ErrorKind::Other, "test - max_writes"));
}
Some(0) => return Ok(0),
Some(ref mut count) => *count -= 1,
None => {}
}
let len = match self.accept_prefix {
None => data.len(),
Some(prefix) => data.len().min(prefix),
};
let data = &data[..len];
self.buffer.extend_from_slice(data);
Ok(len)
}
fn flush(&mut self) -> io::Result<()> {
if self.always_flush_error {
Err(io::Error::new(io::ErrorKind::Other, "test - always_flush_error"))
} else {
self.flushed = true;
Ok(())
}
}
}
/// Previously the `LineWriter` could successfully write some bytes but
/// then fail to report that it has done so. Additionally, an erroneous
/// flush after a successful write was permanently ignored.
///
/// Test that a line writer correctly reports the number of written bytes,
/// and that it attempts to flush buffered lines from previous writes
/// before processing new data
///
/// Regression test for #37807
#[test]
fn erroneous_flush_retried() {
let writer = ProgrammableSink {
// Only write up to 4 bytes at a time
accept_prefix: Some(4),
// Accept the first two writes, then error the others
max_writes: Some(2),
error_after_max_writes: true,
..Default::default()
};
// This should write the first 4 bytes. The rest will be buffered, out
// to the last newline.
let mut writer = LineWriter::new(writer);
assert_eq!(writer.write(b"a\nb\nc\nd\ne").unwrap(), 8);
// This write should attempt to flush "c\nd\n", then buffer "e". No
// errors should happen here because no further writes should be
// attempted against `writer`.
assert_eq!(writer.write(b"e").unwrap(), 1);
assert_eq!(&writer.get_ref().buffer, b"a\nb\nc\nd\n");
}
#[test]
fn line_vectored() {
let mut a = LineWriter::new(Vec::new());
assert_eq!(
a.write_vectored(&[
IoSlice::new(&[]),
IoSlice::new(b"\n"),
IoSlice::new(&[]),
IoSlice::new(b"a"),
])
.unwrap(),
2,
);
assert_eq!(a.get_ref(), b"\n");
assert_eq!(
a.write_vectored(&[
IoSlice::new(&[]),
IoSlice::new(b"b"),
IoSlice::new(&[]),
IoSlice::new(b"a"),
IoSlice::new(&[]),
IoSlice::new(b"c"),
])
.unwrap(),
3,
);
assert_eq!(a.get_ref(), b"\n");
a.flush().unwrap();
assert_eq!(a.get_ref(), b"\nabac");
assert_eq!(a.write_vectored(&[]).unwrap(), 0);
assert_eq!(
a.write_vectored(&[
IoSlice::new(&[]),
IoSlice::new(&[]),
IoSlice::new(&[]),
IoSlice::new(&[]),
])
.unwrap(),
0,
);
assert_eq!(a.write_vectored(&[IoSlice::new(b"a\nb"),]).unwrap(), 3);
assert_eq!(a.get_ref(), b"\nabaca\nb");
}
#[test]
fn line_vectored_partial_and_errors() {
use crate::collections::VecDeque;
enum Call {
Write { inputs: Vec<&'static [u8]>, output: io::Result<usize> },
Flush { output: io::Result<()> },
}
#[derive(Default)]
struct Writer {
calls: VecDeque<Call>,
}
impl Write for Writer {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
self.write_vectored(&[IoSlice::new(buf)])
}
fn write_vectored(&mut self, buf: &[IoSlice<'_>]) -> io::Result<usize> {
match self.calls.pop_front().expect("unexpected call to write") {
Call::Write { inputs, output } => {
assert_eq!(inputs, buf.iter().map(|b| &**b).collect::<Vec<_>>());
output
}
Call::Flush { .. } => panic!("unexpected call to write; expected a flush"),
}
}
fn is_write_vectored(&self) -> bool {
true
}
fn flush(&mut self) -> io::Result<()> {
match self.calls.pop_front().expect("Unexpected call to flush") {
Call::Flush { output } => output,
Call::Write { .. } => panic!("unexpected call to flush; expected a write"),
}
}
}
impl Drop for Writer {
fn drop(&mut self) {
if !thread::panicking() {
assert_eq!(self.calls.len(), 0);
}
}
}
// partial writes keep going
let mut a = LineWriter::new(Writer::default());
a.write_vectored(&[IoSlice::new(&[]), IoSlice::new(b"abc")]).unwrap();
a.get_mut().calls.push_back(Call::Write { inputs: vec![b"abc"], output: Ok(1) });
a.get_mut().calls.push_back(Call::Write { inputs: vec![b"bc"], output: Ok(2) });
a.get_mut().calls.push_back(Call::Write { inputs: vec![b"x", b"\n"], output: Ok(2) });
a.write_vectored(&[IoSlice::new(b"x"), IoSlice::new(b"\n")]).unwrap();
a.get_mut().calls.push_back(Call::Flush { output: Ok(()) });
a.flush().unwrap();
// erroneous writes stop and don't write more
a.get_mut().calls.push_back(Call::Write { inputs: vec![b"x", b"\na"], output: Err(err()) });
a.get_mut().calls.push_back(Call::Flush { output: Ok(()) });
assert!(a.write_vectored(&[IoSlice::new(b"x"), IoSlice::new(b"\na")]).is_err());
a.flush().unwrap();
fn err() -> io::Error {
io::Error::new(io::ErrorKind::Other, "x")
}
}
/// Test that, in cases where vectored writing is not enabled, the
/// LineWriter uses the normal `write` call, which more-correctly handles
/// partial lines
#[test]
fn line_vectored_ignored() {
let writer = ProgrammableSink::default();
let mut writer = LineWriter::new(writer);
let content = [
IoSlice::new(&[]),
IoSlice::new(b"Line 1\nLine"),
IoSlice::new(b" 2\nLine 3\nL"),
IoSlice::new(&[]),
IoSlice::new(&[]),
IoSlice::new(b"ine 4"),
IoSlice::new(b"\nLine 5\n"),
];
let count = writer.write_vectored(&content).unwrap();
assert_eq!(count, 11);
assert_eq!(&writer.get_ref().buffer, b"Line 1\n");
let count = writer.write_vectored(&content[2..]).unwrap();
assert_eq!(count, 11);
assert_eq!(&writer.get_ref().buffer, b"Line 1\nLine 2\nLine 3\n");
let count = writer.write_vectored(&content[5..]).unwrap();
assert_eq!(count, 5);
assert_eq!(&writer.get_ref().buffer, b"Line 1\nLine 2\nLine 3\n");
let count = writer.write_vectored(&content[6..]).unwrap();
assert_eq!(count, 8);
assert_eq!(
writer.get_ref().buffer.as_slice(),
b"Line 1\nLine 2\nLine 3\nLine 4\nLine 5\n".as_ref()
);
}
/// Test that, given this input:
///
/// Line 1\n
/// Line 2\n
/// Line 3\n
/// Line 4
///
/// And given a result that only writes to midway through Line 2
///
/// That only up to the end of Line 3 is buffered
///
/// This behavior is desirable because it prevents flushing partial lines
#[test]
fn partial_write_buffers_line() {
let writer = ProgrammableSink { accept_prefix: Some(13), ..Default::default() };
let mut writer = LineWriter::new(writer);
assert_eq!(writer.write(b"Line 1\nLine 2\nLine 3\nLine4").unwrap(), 21);
assert_eq!(&writer.get_ref().buffer, b"Line 1\nLine 2");
assert_eq!(writer.write(b"Line 4").unwrap(), 6);
assert_eq!(&writer.get_ref().buffer, b"Line 1\nLine 2\nLine 3\n");
}
/// Test that, given this input:
///
/// Line 1\n
/// Line 2\n
/// Line 3
///
/// And given that the full write of lines 1 and 2 was successful
/// That data up to Line 3 is buffered
#[test]
fn partial_line_buffered_after_line_write() {
let writer = ProgrammableSink::default();
let mut writer = LineWriter::new(writer);
assert_eq!(writer.write(b"Line 1\nLine 2\nLine 3").unwrap(), 20);
assert_eq!(&writer.get_ref().buffer, b"Line 1\nLine 2\n");
assert!(writer.flush().is_ok());
assert_eq!(&writer.get_ref().buffer, b"Line 1\nLine 2\nLine 3");
}
/// Test that, given a partial line that exceeds the length of
/// LineBuffer's buffer (that is, without a trailing newline), that that
/// line is written to the inner writer
#[test]
fn long_line_flushed() {
let writer = ProgrammableSink::default();
let mut writer = LineWriter::with_capacity(5, writer);
assert_eq!(writer.write(b"0123456789").unwrap(), 10);
assert_eq!(&writer.get_ref().buffer, b"0123456789");
}
/// Test that, given a very long partial line *after* successfully
/// flushing a complete line, that that line is buffered unconditionally,
/// and no additional writes take place. This assures the property that
/// `write` should make at-most-one attempt to write new data.
#[test]
fn line_long_tail_not_flushed() {
let writer = ProgrammableSink::default();
let mut writer = LineWriter::with_capacity(5, writer);
// Assert that Line 1\n is flushed, and 01234 is buffered
assert_eq!(writer.write(b"Line 1\n0123456789").unwrap(), 12);
assert_eq!(&writer.get_ref().buffer, b"Line 1\n");
// Because the buffer is full, this subsequent write will flush it
assert_eq!(writer.write(b"5").unwrap(), 1);
assert_eq!(&writer.get_ref().buffer, b"Line 1\n01234");
}
/// Test that, if an attempt to pre-flush buffered data returns Ok(0),
/// this is propagated as an error.
#[test]
fn line_buffer_write0_error() {
let writer = ProgrammableSink {
// Accept one write, then return Ok(0) on subsequent ones
max_writes: Some(1),
..Default::default()
};
let mut writer = LineWriter::new(writer);
// This should write "Line 1\n" and buffer "Partial"
assert_eq!(writer.write(b"Line 1\nPartial").unwrap(), 14);
assert_eq!(&writer.get_ref().buffer, b"Line 1\n");
// This will attempt to flush "partial", which will return Ok(0), which
// needs to be an error, because we've already informed the client
// that we accepted the write.
let err = writer.write(b" Line End\n").unwrap_err();
assert_eq!(err.kind(), ErrorKind::WriteZero);
assert_eq!(&writer.get_ref().buffer, b"Line 1\n");
}
/// Test that, if a write returns Ok(0) after a successful pre-flush, this
/// is propagated as Ok(0)
#[test]
fn line_buffer_write0_normal() {
let writer = ProgrammableSink {
// Accept two writes, then return Ok(0) on subsequent ones
max_writes: Some(2),
..Default::default()
};
let mut writer = LineWriter::new(writer);
// This should write "Line 1\n" and buffer "Partial"
assert_eq!(writer.write(b"Line 1\nPartial").unwrap(), 14);
assert_eq!(&writer.get_ref().buffer, b"Line 1\n");
// This will flush partial, which will succeed, but then return Ok(0)
// when flushing " Line End\n"
assert_eq!(writer.write(b" Line End\n").unwrap(), 0);
assert_eq!(&writer.get_ref().buffer, b"Line 1\nPartial");
}
/// LineWriter has a custom `write_all`; make sure it works correctly
#[test]
fn line_write_all() {
let writer = ProgrammableSink {
// Only write 5 bytes at a time
accept_prefix: Some(5),
..Default::default()
};
let mut writer = LineWriter::new(writer);
writer.write_all(b"Line 1\nLine 2\nLine 3\nLine 4\nPartial").unwrap();
assert_eq!(&writer.get_ref().buffer, b"Line 1\nLine 2\nLine 3\nLine 4\n");
writer.write_all(b" Line 5\n").unwrap();
assert_eq!(
writer.get_ref().buffer.as_slice(),
b"Line 1\nLine 2\nLine 3\nLine 4\nPartial Line 5\n".as_ref(),
);
}
#[test]
fn line_write_all_error() {
let writer = ProgrammableSink {
// Only accept up to 3 writes of up to 5 bytes each
accept_prefix: Some(5),
max_writes: Some(3),
..Default::default()
};
let mut writer = LineWriter::new(writer);
let res = writer.write_all(b"Line 1\nLine 2\nLine 3\nLine 4\nPartial");
assert!(res.is_err());
// An error from write_all leaves everything in an indeterminate state,
// so there's nothing else to test here
}
/// Under certain circumstances, the old implementation of LineWriter
/// would try to buffer "to the last newline" but be forced to buffer
/// less than that, leading to inappropriate partial line writes.
/// Regression test for that issue.
#[test]
fn partial_multiline_buffering() {
let writer = ProgrammableSink {
// Write only up to 5 bytes at a time
accept_prefix: Some(5),
..Default::default()
};
let mut writer = LineWriter::with_capacity(10, writer);
let content = b"AAAAABBBBB\nCCCCDDDDDD\nEEE";
// When content is written, LineWriter will try to write blocks A, B,
// C, and D. Only block A will succeed. Under the old behavior, LineWriter
// would then try to buffer B, C and D, but because its capacity is 10,
// it will only be able to buffer B and C. We don't want to buffer
// partial lines concurrent with whole lines, so the correct behavior
// is to buffer only block B (out to the newline)
assert_eq!(writer.write(content).unwrap(), 11);
assert_eq!(writer.get_ref().buffer, *b"AAAAA");
writer.flush().unwrap();
assert_eq!(writer.get_ref().buffer, *b"AAAAABBBBB\n");
}
/// Same as test_partial_multiline_buffering, but in the event NO full lines
/// fit in the buffer, just buffer as much as possible
#[test]
fn partial_multiline_buffering_without_full_line() {
let writer = ProgrammableSink {
// Write only up to 5 bytes at a time
accept_prefix: Some(5),
..Default::default()
};
let mut writer = LineWriter::with_capacity(5, writer);
let content = b"AAAAABBBBBBBBBB\nCCCCC\nDDDDD";
// When content is written, LineWriter will try to write blocks A, B,
// and C. Only block A will succeed. Under the old behavior, LineWriter
// would then try to buffer B and C, but because its capacity is 5,
// it will only be able to buffer part of B. Because it's not possible
// for it to buffer any complete lines, it should buffer as much of B as
// possible
assert_eq!(writer.write(content).unwrap(), 10);
assert_eq!(writer.get_ref().buffer, *b"AAAAA");
writer.flush().unwrap();
assert_eq!(writer.get_ref().buffer, *b"AAAAABBBBB");
}
#[derive(Debug, Clone, PartialEq, Eq)]
enum RecordedEvent {
Write(String),
Flush,
}
#[derive(Debug, Clone, Default)]
struct WriteRecorder {
pub events: Vec<RecordedEvent>,
}
impl Write for WriteRecorder {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
use crate::str::from_utf8;
self.events.push(RecordedEvent::Write(from_utf8(buf).unwrap().to_string()));
Ok(buf.len())
}
fn flush(&mut self) -> io::Result<()> {
self.events.push(RecordedEvent::Flush);
Ok(())
}
}
/// Test that a normal, formatted writeln only results in a single write
/// call to the underlying writer. A naive implementation of
/// LineWriter::write_all results in two writes: one of the buffered data,
/// and another of the final substring in the formatted set
#[test]
fn single_formatted_write() {
let writer = WriteRecorder::default();
let mut writer = LineWriter::new(writer);
// Under a naive implementation of LineWriter, this will result in two
// writes: "hello, world" and "!\n", because write() has to flush the
// buffer before attempting to write the last "!\n". write_all shouldn't
// have this limitation.
writeln!(&mut writer, "{}, {}!", "hello", "world").unwrap();
assert_eq!(writer.get_ref().events, [RecordedEvent::Write("hello, world!\n".to_string())]);
}

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@ -0,0 +1,453 @@
#[cfg(test)]
mod tests;
use crate::io::prelude::*;
use core::cmp;
use crate::io::{self, Error, ErrorKind, Initializer, IoSlice, IoSliceMut, SeekFrom};
#[cfg(feature="collections")] use core::convert::TryInto;
/// A `Cursor` wraps an in-memory buffer and provides it with a
/// [`Seek`] implementation.
///
/// `Cursor`s are used with in-memory buffers, anything implementing
/// [`AsRef`]`<[u8]>`, to allow them to implement [`Read`] and/or [`Write`],
/// allowing these buffers to be used anywhere you might use a reader or writer
/// that does actual I/O.
///
/// The standard library implements some I/O traits on various types which
/// are commonly used as a buffer, like `Cursor<`[`Vec`]`<u8>>` and
/// `Cursor<`[`&[u8]`][bytes]`>`.
///
/// # Examples
///
/// We may want to write bytes to a [`File`] in our production
/// code, but use an in-memory buffer in our tests. We can do this with
/// `Cursor`:
///
/// [bytes]: crate::slice
/// [`File`]: crate::fs::File
///
/// ```no_run
/// use std::io::prelude::*;
/// use std::io::{self, SeekFrom};
/// use std::fs::File;
///
/// // a library function we've written
/// fn write_ten_bytes_at_end<W: Write + Seek>(writer: &mut W) -> io::Result<()> {
/// writer.seek(SeekFrom::End(-10))?;
///
/// for i in 0..10 {
/// writer.write(&[i])?;
/// }
///
/// // all went well
/// Ok(())
/// }
///
/// # fn foo() -> io::Result<()> {
/// // Here's some code that uses this library function.
/// //
/// // We might want to use a BufReader here for efficiency, but let's
/// // keep this example focused.
/// let mut file = File::create("foo.txt")?;
///
/// write_ten_bytes_at_end(&mut file)?;
/// # Ok(())
/// # }
///
/// // now let's write a test
/// #[test]
/// fn test_writes_bytes() {
/// // setting up a real File is much slower than an in-memory buffer,
/// // let's use a cursor instead
/// use std::io::Cursor;
/// let mut buff = Cursor::new(vec![0; 15]);
///
/// write_ten_bytes_at_end(&mut buff).unwrap();
///
/// assert_eq!(&buff.get_ref()[5..15], &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
/// }
/// ```
#[derive(Clone, Debug, Default, Eq, PartialEq)]
pub struct Cursor<T> {
inner: T,
pos: u64,
}
impl<T> Cursor<T> {
/// Creates a new cursor wrapping the provided underlying in-memory buffer.
///
/// Cursor initial position is `0` even if underlying buffer (e.g., [`Vec`])
/// is not empty. So writing to cursor starts with overwriting [`Vec`]
/// content, not with appending to it.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
/// ```
pub fn new(inner: T) -> Cursor<T> {
Cursor { pos: 0, inner }
}
/// Consumes this cursor, returning the underlying value.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
///
/// let vec = buff.into_inner();
/// ```
pub fn into_inner(self) -> T {
self.inner
}
/// Gets a reference to the underlying value in this cursor.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
///
/// let reference = buff.get_ref();
/// ```
pub fn get_ref(&self) -> &T {
&self.inner
}
/// Gets a mutable reference to the underlying value in this cursor.
///
/// Care should be taken to avoid modifying the internal I/O state of the
/// underlying value as it may corrupt this cursor's position.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let mut buff = Cursor::new(Vec::new());
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
/// # force_inference(&buff);
///
/// let reference = buff.get_mut();
/// ```
pub fn get_mut(&mut self) -> &mut T {
&mut self.inner
}
/// Returns the current position of this cursor.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
/// use std::io::prelude::*;
/// use std::io::SeekFrom;
///
/// let mut buff = Cursor::new(vec![1, 2, 3, 4, 5]);
///
/// assert_eq!(buff.position(), 0);
///
/// buff.seek(SeekFrom::Current(2)).unwrap();
/// assert_eq!(buff.position(), 2);
///
/// buff.seek(SeekFrom::Current(-1)).unwrap();
/// assert_eq!(buff.position(), 1);
/// ```
pub fn position(&self) -> u64 {
self.pos
}
/// Sets the position of this cursor.
///
/// # Examples
///
/// ```
/// use std::io::Cursor;
///
/// let mut buff = Cursor::new(vec![1, 2, 3, 4, 5]);
///
/// assert_eq!(buff.position(), 0);
///
/// buff.set_position(2);
/// assert_eq!(buff.position(), 2);
///
/// buff.set_position(4);
/// assert_eq!(buff.position(), 4);
/// ```
pub fn set_position(&mut self, pos: u64) {
self.pos = pos;
}
}
impl<T> io::Seek for Cursor<T>
where
T: AsRef<[u8]>,
{
fn seek(&mut self, style: SeekFrom) -> io::Result<u64> {
let (base_pos, offset) = match style {
SeekFrom::Start(n) => {
self.pos = n;
return Ok(n);
}
SeekFrom::End(n) => (self.inner.as_ref().len() as u64, n),
SeekFrom::Current(n) => (self.pos, n),
};
let new_pos = if offset >= 0 {
base_pos.checked_add(offset as u64)
} else {
base_pos.checked_sub((offset.wrapping_neg()) as u64)
};
match new_pos {
Some(n) => {
self.pos = n;
Ok(self.pos)
}
None => Err(Error::new(
ErrorKind::InvalidInput,
"invalid seek to a negative or overflowing position",
)),
}
}
fn stream_len(&mut self) -> io::Result<u64> {
Ok(self.inner.as_ref().len() as u64)
}
fn stream_position(&mut self) -> io::Result<u64> {
Ok(self.pos)
}
}
impl<T> Read for Cursor<T>
where
T: AsRef<[u8]>,
{
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
let n = Read::read(&mut self.get_buf()?, buf)?;
self.pos += n as u64;
Ok(n)
}
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
let mut nread = 0;
for buf in bufs {
let n = self.read(buf)?;
nread += n;
if n < buf.len() {
break;
}
}
Ok(nread)
}
fn is_read_vectored(&self) -> bool {
true
}
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
let n = buf.len();
Read::read_exact(&mut self.get_buf()?, buf)?;
self.pos += n as u64;
Ok(())
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
}
impl<T> Cursor<T>
where
T: AsRef<[u8]>,
{
fn get_buf(&mut self) -> io::Result<&[u8]> {
let amt = cmp::min(self.pos, self.inner.as_ref().len() as u64);
Ok(&self.inner.as_ref()[(amt as usize)..])
}
}
#[cfg(feature="collections")]
impl<T> BufRead for Cursor<T>
where
T: AsRef<[u8]>,
{
fn fill_buf(&mut self) -> io::Result<&[u8]> {
self.get_buf()
}
fn consume(&mut self, amt: usize) {
self.pos += amt as u64;
}
}
// Non-resizing write implementation
#[inline]
fn slice_write(pos_mut: &mut u64, slice: &mut [u8], buf: &[u8]) -> io::Result<usize> {
let pos = cmp::min(*pos_mut, slice.len() as u64);
let amt = (&mut slice[(pos as usize)..]).write(buf)?;
*pos_mut += amt as u64;
Ok(amt)
}
#[inline]
fn slice_write_vectored(
pos_mut: &mut u64,
slice: &mut [u8],
bufs: &[IoSlice<'_>],
) -> io::Result<usize> {
let mut nwritten = 0;
for buf in bufs {
let n = slice_write(pos_mut, slice, buf)?;
nwritten += n;
if n < buf.len() {
break;
}
}
Ok(nwritten)
}
// Resizing write implementation
#[cfg(feature="collections")]
fn vec_write(pos_mut: &mut u64, vec: &mut Vec<u8>, buf: &[u8]) -> io::Result<usize> {
let pos: usize = (*pos_mut).try_into().map_err(|_| {
Error::new(
ErrorKind::InvalidInput,
"cursor position exceeds maximum possible vector length",
)
})?;
// Make sure the internal buffer is as least as big as where we
// currently are
let len = vec.len();
if len < pos {
// use `resize` so that the zero filling is as efficient as possible
vec.resize(pos, 0);
}
// Figure out what bytes will be used to overwrite what's currently
// there (left), and what will be appended on the end (right)
{
let space = vec.len() - pos;
let (left, right) = buf.split_at(cmp::min(space, buf.len()));
vec[pos..pos + left.len()].copy_from_slice(left);
vec.extend_from_slice(right);
}
// Bump us forward
*pos_mut = (pos + buf.len()) as u64;
Ok(buf.len())
}
#[cfg(feature="collections")]
fn vec_write_vectored(
pos_mut: &mut u64,
vec: &mut Vec<u8>,
bufs: &[IoSlice<'_>],
) -> io::Result<usize> {
let mut nwritten = 0;
for buf in bufs {
nwritten += vec_write(pos_mut, vec, buf)?;
}
Ok(nwritten)
}
impl Write for Cursor<&mut [u8]> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
slice_write(&mut self.pos, self.inner, buf)
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
slice_write_vectored(&mut self.pos, self.inner, bufs)
}
#[inline]
fn is_write_vectored(&self) -> bool {
true
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
#[cfg(feature="collections")]
impl Write for Cursor<&mut Vec<u8>> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
vec_write(&mut self.pos, self.inner, buf)
}
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
vec_write_vectored(&mut self.pos, self.inner, bufs)
}
#[inline]
fn is_write_vectored(&self) -> bool {
true
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
#[cfg(feature = "collections")]
impl Write for Cursor<Vec<u8>> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
vec_write(&mut self.pos, &mut self.inner, buf)
}
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
vec_write_vectored(&mut self.pos, &mut self.inner, bufs)
}
#[inline]
fn is_write_vectored(&self) -> bool {
true
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
#[cfg(feature = "alloc")]
impl Write for Cursor<::alloc::boxed::Box<[u8]>> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
slice_write(&mut self.pos, &mut self.inner, buf)
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
slice_write_vectored(&mut self.pos, &mut self.inner, bufs)
}
#[inline]
fn is_write_vectored(&self) -> bool {
true
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}

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@ -0,0 +1,516 @@
use crate::io::prelude::*;
use crate::io::{Cursor, IoSlice, IoSliceMut, SeekFrom};
#[test]
fn test_vec_writer() {
let mut writer = Vec::new();
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(
writer
.write_vectored(&[IoSlice::new(&[]), IoSlice::new(&[8, 9]), IoSlice::new(&[10])],)
.unwrap(),
3
);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
assert_eq!(writer, b);
}
#[test]
fn test_mem_writer() {
let mut writer = Cursor::new(Vec::new());
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(
writer
.write_vectored(&[IoSlice::new(&[]), IoSlice::new(&[8, 9]), IoSlice::new(&[10])],)
.unwrap(),
3
);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
assert_eq!(&writer.get_ref()[..], b);
}
#[test]
fn test_mem_mut_writer() {
let mut vec = Vec::new();
let mut writer = Cursor::new(&mut vec);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(
writer
.write_vectored(&[IoSlice::new(&[]), IoSlice::new(&[8, 9]), IoSlice::new(&[10])],)
.unwrap(),
3
);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
assert_eq!(&writer.get_ref()[..], b);
}
#[test]
fn test_box_slice_writer() {
let mut writer = Cursor::new(vec![0u8; 9].into_boxed_slice());
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[]).unwrap(), 0);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[8, 9]).unwrap(), 1);
assert_eq!(writer.write(&[10]).unwrap(), 0);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8];
assert_eq!(&**writer.get_ref(), b);
}
#[test]
fn test_box_slice_writer_vectored() {
let mut writer = Cursor::new(vec![0u8; 9].into_boxed_slice());
assert_eq!(writer.position(), 0);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[0])]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(
writer.write_vectored(&[IoSlice::new(&[1, 2, 3]), IoSlice::new(&[4, 5, 6, 7]),]).unwrap(),
7,
);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write_vectored(&[]).unwrap(), 0);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[8, 9])]).unwrap(), 1);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[10])]).unwrap(), 0);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8];
assert_eq!(&**writer.get_ref(), b);
}
#[test]
fn test_buf_writer() {
let mut buf = [0 as u8; 9];
{
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[]).unwrap(), 0);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write(&[8, 9]).unwrap(), 1);
assert_eq!(writer.write(&[10]).unwrap(), 0);
}
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8];
assert_eq!(buf, b);
}
#[test]
fn test_buf_writer_vectored() {
let mut buf = [0 as u8; 9];
{
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[0])]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(
writer
.write_vectored(&[IoSlice::new(&[1, 2, 3]), IoSlice::new(&[4, 5, 6, 7])],)
.unwrap(),
7,
);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write_vectored(&[]).unwrap(), 0);
assert_eq!(writer.position(), 8);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[8, 9])]).unwrap(), 1);
assert_eq!(writer.write_vectored(&[IoSlice::new(&[10])]).unwrap(), 0);
}
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8];
assert_eq!(buf, b);
}
#[test]
fn test_buf_writer_seek() {
let mut buf = [0 as u8; 8];
{
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[1]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.seek(SeekFrom::Start(2)).unwrap(), 2);
assert_eq!(writer.position(), 2);
assert_eq!(writer.write(&[2]).unwrap(), 1);
assert_eq!(writer.position(), 3);
assert_eq!(writer.seek(SeekFrom::Current(-2)).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[3]).unwrap(), 1);
assert_eq!(writer.position(), 2);
assert_eq!(writer.seek(SeekFrom::End(-1)).unwrap(), 7);
assert_eq!(writer.position(), 7);
assert_eq!(writer.write(&[4]).unwrap(), 1);
assert_eq!(writer.position(), 8);
}
let b: &[_] = &[1, 3, 2, 0, 0, 0, 0, 4];
assert_eq!(buf, b);
}
#[test]
fn test_buf_writer_error() {
let mut buf = [0 as u8; 2];
let mut writer = Cursor::new(&mut buf[..]);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.write(&[0, 0]).unwrap(), 1);
assert_eq!(writer.write(&[0, 0]).unwrap(), 0);
}
#[test]
fn test_mem_reader() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7]);
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.position(), 5);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(buf, b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_mem_reader_vectored() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7]);
let mut buf = [];
assert_eq!(reader.read_vectored(&mut [IoSliceMut::new(&mut buf)]).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(
reader.read_vectored(&mut [IoSliceMut::new(&mut []), IoSliceMut::new(&mut buf),]).unwrap(),
1,
);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf1 = [0; 4];
let mut buf2 = [0; 4];
assert_eq!(
reader
.read_vectored(&mut [IoSliceMut::new(&mut buf1), IoSliceMut::new(&mut buf2),])
.unwrap(),
7,
);
let b1: &[_] = &[1, 2, 3, 4];
let b2: &[_] = &[5, 6, 7];
assert_eq!(buf1, b1);
assert_eq!(&buf2[..3], b2);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_boxed_slice_reader() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7].into_boxed_slice());
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.position(), 5);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(buf, b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_boxed_slice_reader_vectored() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7].into_boxed_slice());
let mut buf = [];
assert_eq!(reader.read_vectored(&mut [IoSliceMut::new(&mut buf)]).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(
reader.read_vectored(&mut [IoSliceMut::new(&mut []), IoSliceMut::new(&mut buf),]).unwrap(),
1,
);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf1 = [0; 4];
let mut buf2 = [0; 4];
assert_eq!(
reader
.read_vectored(&mut [IoSliceMut::new(&mut buf1), IoSliceMut::new(&mut buf2)],)
.unwrap(),
7,
);
let b1: &[_] = &[1, 2, 3, 4];
let b2: &[_] = &[5, 6, 7];
assert_eq!(buf1, b1);
assert_eq!(&buf2[..3], b2);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn read_to_end() {
let mut reader = Cursor::new(vec![0, 1, 2, 3, 4, 5, 6, 7]);
let mut v = Vec::new();
reader.read_to_end(&mut v).unwrap();
assert_eq!(v, [0, 1, 2, 3, 4, 5, 6, 7]);
}
#[test]
fn test_slice_reader() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let reader = &mut &in_buf[..];
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.len(), 7);
let b: &[_] = &[0];
assert_eq!(&buf[..], b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.len(), 3);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(&buf[..], b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_slice_reader_vectored() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let reader = &mut &in_buf[..];
let mut buf = [];
assert_eq!(reader.read_vectored(&mut [IoSliceMut::new(&mut buf)]).unwrap(), 0);
let mut buf = [0];
assert_eq!(
reader.read_vectored(&mut [IoSliceMut::new(&mut []), IoSliceMut::new(&mut buf),]).unwrap(),
1,
);
assert_eq!(reader.len(), 7);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf1 = [0; 4];
let mut buf2 = [0; 4];
assert_eq!(
reader
.read_vectored(&mut [IoSliceMut::new(&mut buf1), IoSliceMut::new(&mut buf2)],)
.unwrap(),
7,
);
let b1: &[_] = &[1, 2, 3, 4];
let b2: &[_] = &[5, 6, 7];
assert_eq!(buf1, b1);
assert_eq!(&buf2[..3], b2);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn test_read_exact() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let reader = &mut &in_buf[..];
let mut buf = [];
assert!(reader.read_exact(&mut buf).is_ok());
let mut buf = [8];
assert!(reader.read_exact(&mut buf).is_ok());
assert_eq!(buf[0], 0);
assert_eq!(reader.len(), 7);
let mut buf = [0, 0, 0, 0, 0, 0, 0];
assert!(reader.read_exact(&mut buf).is_ok());
assert_eq!(buf, [1, 2, 3, 4, 5, 6, 7]);
assert_eq!(reader.len(), 0);
let mut buf = [0];
assert!(reader.read_exact(&mut buf).is_err());
}
#[test]
fn test_buf_reader() {
let in_buf = vec![0, 1, 2, 3, 4, 5, 6, 7];
let mut reader = Cursor::new(&in_buf[..]);
let mut buf = [];
assert_eq!(reader.read(&mut buf).unwrap(), 0);
assert_eq!(reader.position(), 0);
let mut buf = [0];
assert_eq!(reader.read(&mut buf).unwrap(), 1);
assert_eq!(reader.position(), 1);
let b: &[_] = &[0];
assert_eq!(buf, b);
let mut buf = [0; 4];
assert_eq!(reader.read(&mut buf).unwrap(), 4);
assert_eq!(reader.position(), 5);
let b: &[_] = &[1, 2, 3, 4];
assert_eq!(buf, b);
assert_eq!(reader.read(&mut buf).unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(&buf[..3], b);
assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
#[test]
fn seek_past_end() {
let buf = [0xff];
let mut r = Cursor::new(&buf[..]);
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.read(&mut [0]).unwrap(), 0);
let mut r = Cursor::new(vec![10]);
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.read(&mut [0]).unwrap(), 0);
let mut buf = [0];
let mut r = Cursor::new(&mut buf[..]);
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.write(&[3]).unwrap(), 0);
let mut r = Cursor::new(vec![10].into_boxed_slice());
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.write(&[3]).unwrap(), 0);
}
#[test]
fn seek_past_i64() {
let buf = [0xff];
let mut r = Cursor::new(&buf[..]);
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
let mut r = Cursor::new(vec![10]);
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
let mut buf = [0];
let mut r = Cursor::new(&mut buf[..]);
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
let mut r = Cursor::new(vec![10].into_boxed_slice());
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
}
#[test]
fn seek_before_0() {
let buf = [0xff];
let mut r = Cursor::new(&buf[..]);
assert!(r.seek(SeekFrom::End(-2)).is_err());
let mut r = Cursor::new(vec![10]);
assert!(r.seek(SeekFrom::End(-2)).is_err());
let mut buf = [0];
let mut r = Cursor::new(&mut buf[..]);
assert!(r.seek(SeekFrom::End(-2)).is_err());
let mut r = Cursor::new(vec![10].into_boxed_slice());
assert!(r.seek(SeekFrom::End(-2)).is_err());
}
#[test]
fn test_seekable_mem_writer() {
let mut writer = Cursor::new(Vec::<u8>::new());
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[0]).unwrap(), 1);
assert_eq!(writer.position(), 1);
assert_eq!(writer.write(&[1, 2, 3]).unwrap(), 3);
assert_eq!(writer.write(&[4, 5, 6, 7]).unwrap(), 4);
assert_eq!(writer.position(), 8);
let b: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::Start(0)).unwrap(), 0);
assert_eq!(writer.position(), 0);
assert_eq!(writer.write(&[3, 4]).unwrap(), 2);
let b: &[_] = &[3, 4, 2, 3, 4, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::Current(1)).unwrap(), 3);
assert_eq!(writer.write(&[0, 1]).unwrap(), 2);
let b: &[_] = &[3, 4, 2, 0, 1, 5, 6, 7];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::End(-1)).unwrap(), 7);
assert_eq!(writer.write(&[1, 2]).unwrap(), 2);
let b: &[_] = &[3, 4, 2, 0, 1, 5, 6, 1, 2];
assert_eq!(&writer.get_ref()[..], b);
assert_eq!(writer.seek(SeekFrom::End(1)).unwrap(), 10);
assert_eq!(writer.write(&[1]).unwrap(), 1);
let b: &[_] = &[3, 4, 2, 0, 1, 5, 6, 1, 2, 0, 1];
assert_eq!(&writer.get_ref()[..], b);
}
#[test]
fn vec_seek_past_end() {
let mut r = Cursor::new(Vec::new());
assert_eq!(r.seek(SeekFrom::Start(10)).unwrap(), 10);
assert_eq!(r.write(&[3]).unwrap(), 1);
}
#[test]
fn vec_seek_before_0() {
let mut r = Cursor::new(Vec::new());
assert!(r.seek(SeekFrom::End(-2)).is_err());
}
#[test]
#[cfg(target_pointer_width = "32")]
fn vec_seek_and_write_past_usize_max() {
let mut c = Cursor::new(Vec::new());
c.set_position(usize::MAX as u64 + 1);
assert!(c.write_all(&[1, 2, 3]).is_err());
}
#[test]
fn test_partial_eq() {
assert_eq!(Cursor::new(Vec::<u8>::new()), Cursor::new(Vec::<u8>::new()));
}
#[test]
fn test_eq() {
struct AssertEq<T: Eq>(pub T);
let _: AssertEq<Cursor<Vec<u8>>> = AssertEq(Cursor::new(Vec::new()));
}

View File

@ -0,0 +1,508 @@
#[cfg(test)]
mod tests;
use core::convert::From;
use core::fmt;
use core::result;
use core::convert::Into;
use core::marker::{Send, Sync};
use core::option::Option::{self, Some, None};
#[cfg(feature="alloc")] use alloc::boxed::Box;
#[cfg(not(feature="alloc"))] use ::FakeBox as Box;
#[cfg(feature="collections")] use collections::string::String;
#[cfg(not(feature="collections"))] use ::ErrorString as String;
/// A specialized [`Result`] type for I/O operations.
///
/// This type is broadly used across [`std::io`] for any operation which may
/// produce an error.
///
/// This typedef is generally used to avoid writing out [`io::Error`] directly and
/// is otherwise a direct mapping to [`Result`].
///
/// While usual Rust style is to import types directly, aliases of [`Result`]
/// often are not, to make it easier to distinguish between them. [`Result`] is
/// generally assumed to be [`std::result::Result`][`Result`], and so users of this alias
/// will generally use `io::Result` instead of shadowing the [prelude]'s import
/// of [`std::result::Result`][`Result`].
///
/// [`std::io`]: crate::io
/// [`io::Error`]: Error
/// [`Result`]: crate::result::Result
/// [prelude]: crate::prelude
///
/// # Examples
///
/// A convenience function that bubbles an `io::Result` to its caller:
///
/// ```
/// use std::io;
///
/// fn get_string() -> io::Result<String> {
/// let mut buffer = String::new();
///
/// io::stdin().read_line(&mut buffer)?;
///
/// Ok(buffer)
/// }
/// ```
pub type Result<T> = result::Result<T, Error>;
/// The error type for I/O operations of the [`Read`], [`Write`], [`Seek`], and
/// associated traits.
///
/// Errors mostly originate from the underlying OS, but custom instances of
/// `Error` can be created with crafted error messages and a particular value of
/// [`ErrorKind`].
///
/// [`Read`]: crate::io::Read
/// [`Write`]: crate::io::Write
/// [`Seek`]: crate::io::Seek
pub struct Error {
repr: Repr,
}
impl fmt::Debug for Error {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt::Debug::fmt(&self.repr, f)
}
}
enum Repr {
Os(i32),
Simple(ErrorKind),
#[cfg(feature="alloc")]
Custom(Box<Custom>),
#[cfg(not(feature="alloc"))]
Custom(Custom),
}
#[derive(Debug)]
struct Custom {
kind: ErrorKind,
error: String,
}
/// A list specifying general categories of I/O error.
///
/// This list is intended to grow over time and it is not recommended to
/// exhaustively match against it.
///
/// It is used with the [`io::Error`] type.
///
/// [`io::Error`]: Error
#[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
#[allow(deprecated)]
#[non_exhaustive]
pub enum ErrorKind {
/// An entity was not found, often a file.
NotFound,
/// The operation lacked the necessary privileges to complete.
PermissionDenied,
/// The connection was refused by the remote server.
ConnectionRefused,
/// The connection was reset by the remote server.
ConnectionReset,
/// The connection was aborted (terminated) by the remote server.
ConnectionAborted,
/// The network operation failed because it was not connected yet.
NotConnected,
/// A socket address could not be bound because the address is already in
/// use elsewhere.
AddrInUse,
/// A nonexistent interface was requested or the requested address was not
/// local.
AddrNotAvailable,
/// The operation failed because a pipe was closed.
BrokenPipe,
/// An entity already exists, often a file.
AlreadyExists,
/// The operation needs to block to complete, but the blocking operation was
/// requested to not occur.
WouldBlock,
/// A parameter was incorrect.
InvalidInput,
/// Data not valid for the operation were encountered.
///
/// Unlike [`InvalidInput`], this typically means that the operation
/// parameters were valid, however the error was caused by malformed
/// input data.
///
/// For example, a function that reads a file into a string will error with
/// `InvalidData` if the file's contents are not valid UTF-8.
///
/// [`InvalidInput`]: ErrorKind::InvalidInput
InvalidData,
/// The I/O operation's timeout expired, causing it to be canceled.
TimedOut,
/// An error returned when an operation could not be completed because a
/// call to [`write`] returned [`Ok(0)`].
///
/// This typically means that an operation could only succeed if it wrote a
/// particular number of bytes but only a smaller number of bytes could be
/// written.
///
/// [`write`]: crate::io::Write::write
/// [`Ok(0)`]: Ok
WriteZero,
/// This operation was interrupted.
///
/// Interrupted operations can typically be retried.
Interrupted,
/// Any I/O error not part of this list.
///
/// Errors that are `Other` now may move to a different or a new
/// [`ErrorKind`] variant in the future. It is not recommended to match
/// an error against `Other` and to expect any additional characteristics,
/// e.g., a specific [`Error::raw_os_error`] return value.
Other,
/// An error returned when an operation could not be completed because an
/// "end of file" was reached prematurely.
///
/// This typically means that an operation could only succeed if it read a
/// particular number of bytes but only a smaller number of bytes could be
/// read.
UnexpectedEof,
}
impl ErrorKind {
pub(crate) fn as_str(&self) -> &'static str {
match *self {
ErrorKind::NotFound => "entity not found",
ErrorKind::PermissionDenied => "permission denied",
ErrorKind::ConnectionRefused => "connection refused",
ErrorKind::ConnectionReset => "connection reset",
ErrorKind::ConnectionAborted => "connection aborted",
ErrorKind::NotConnected => "not connected",
ErrorKind::AddrInUse => "address in use",
ErrorKind::AddrNotAvailable => "address not available",
ErrorKind::BrokenPipe => "broken pipe",
ErrorKind::AlreadyExists => "entity already exists",
ErrorKind::WouldBlock => "operation would block",
ErrorKind::InvalidInput => "invalid input parameter",
ErrorKind::InvalidData => "invalid data",
ErrorKind::TimedOut => "timed out",
ErrorKind::WriteZero => "write zero",
ErrorKind::Interrupted => "operation interrupted",
ErrorKind::Other => "other os error",
ErrorKind::UnexpectedEof => "unexpected end of file",
}
}
}
/// Intended for use for errors not exposed to the user, where allocating onto
/// the heap (for normal construction via Error::new) is too costly.
impl From<ErrorKind> for Error {
/// Converts an [`ErrorKind`] into an [`Error`].
///
/// This conversion allocates a new error with a simple representation of error kind.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// let not_found = ErrorKind::NotFound;
/// let error = Error::from(not_found);
/// assert_eq!("entity not found", format!("{}", error));
/// ```
#[inline]
fn from(kind: ErrorKind) -> Error {
Error { repr: Repr::Simple(kind) }
}
}
impl Error {
/// Creates a new I/O error from a known kind of error as well as an
/// arbitrary error payload.
///
/// This function is used to generically create I/O errors which do not
/// originate from the OS itself. The `error` argument is an arbitrary
/// payload which will be contained in this [`Error`].
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// // errors can be created from strings
/// let custom_error = Error::new(ErrorKind::Other, "oh no!");
///
/// // errors can also be created from other errors
/// let custom_error2 = Error::new(ErrorKind::Interrupted, custom_error);
/// ```
pub fn new<E>(kind: ErrorKind, error: E) -> Error
where
E: Into<String>,
{
Self::_new(kind, error.into())
}
fn _new(kind: ErrorKind, error: String) -> Error {
Error { repr: Repr::Custom(Box::new(Custom { kind, error })) }
}
/// Creates a new instance of an [`Error`] from a particular OS error code.
///
/// # Examples
///
/// On Linux:
///
/// ```
/// # if cfg!(target_os = "linux") {
/// use std::io;
///
/// let error = io::Error::from_raw_os_error(22);
/// assert_eq!(error.kind(), io::ErrorKind::InvalidInput);
/// # }
/// ```
///
/// On Windows:
///
/// ```
/// # if cfg!(windows) {
/// use std::io;
///
/// let error = io::Error::from_raw_os_error(10022);
/// assert_eq!(error.kind(), io::ErrorKind::InvalidInput);
/// # }
/// ```
pub fn from_raw_os_error(code: i32) -> Error {
Error { repr: Repr::Os(code) }
}
/// Returns the OS error that this error represents (if any).
///
/// If this [`Error`] was constructed via [`last_os_error`] or
/// [`from_raw_os_error`], then this function will return [`Some`], otherwise
/// it will return [`None`].
///
/// [`last_os_error`]: Error::last_os_error
/// [`from_raw_os_error`]: Error::from_raw_os_error
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_os_error(err: &Error) {
/// if let Some(raw_os_err) = err.raw_os_error() {
/// println!("raw OS error: {:?}", raw_os_err);
/// } else {
/// println!("Not an OS error");
/// }
/// }
///
/// fn main() {
/// // Will print "raw OS error: ...".
/// print_os_error(&Error::last_os_error());
/// // Will print "Not an OS error".
/// print_os_error(&Error::new(ErrorKind::Other, "oh no!"));
/// }
/// ```
pub fn raw_os_error(&self) -> Option<i32> {
match self.repr {
Repr::Os(i) => Some(i),
Repr::Custom(..) => None,
Repr::Simple(..) => None,
}
}
/// Returns a reference to the inner error wrapped by this error (if any).
///
/// If this [`Error`] was constructed via [`new`] then this function will
/// return [`Some`], otherwise it will return [`None`].
///
/// [`new`]: Error::new
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_error(err: &Error) {
/// if let Some(inner_err) = err.get_ref() {
/// println!("Inner error: {:?}", inner_err);
/// } else {
/// println!("No inner error");
/// }
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(&Error::last_os_error());
/// // Will print "Inner error: ...".
/// print_error(&Error::new(ErrorKind::Other, "oh no!"));
/// }
/// ```
pub fn get_ref(&self) -> Option<&String> {
match self.repr {
Repr::Os(..) => None,
Repr::Simple(..) => None,
Repr::Custom(ref c) => Some(&c.error),
}
}
/// Returns a mutable reference to the inner error wrapped by this error
/// (if any).
///
/// If this [`Error`] was constructed via [`new`] then this function will
/// return [`Some`], otherwise it will return [`None`].
///
/// [`new`]: Error::new
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
/// use std::{error, fmt};
/// use std::fmt::Display;
///
/// #[derive(Debug)]
/// struct MyError {
/// v: String,
/// }
///
/// impl MyError {
/// fn new() -> MyError {
/// MyError {
/// v: "oh no!".to_string()
/// }
/// }
///
/// fn change_message(&mut self, new_message: &str) {
/// self.v = new_message.to_string();
/// }
/// }
///
/// impl error::Error for MyError {}
///
/// impl Display for MyError {
/// fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
/// write!(f, "MyError: {}", &self.v)
/// }
/// }
///
/// fn change_error(mut err: Error) -> Error {
/// if let Some(inner_err) = err.get_mut() {
/// inner_err.downcast_mut::<MyError>().unwrap().change_message("I've been changed!");
/// }
/// err
/// }
///
/// fn print_error(err: &Error) {
/// if let Some(inner_err) = err.get_ref() {
/// println!("Inner error: {}", inner_err);
/// } else {
/// println!("No inner error");
/// }
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(&change_error(Error::last_os_error()));
/// // Will print "Inner error: ...".
/// print_error(&change_error(Error::new(ErrorKind::Other, MyError::new())));
/// }
/// ```
pub fn get_mut(&mut self) -> Option<&mut String> {
match self.repr {
Repr::Os(..) => None,
Repr::Simple(..) => None,
Repr::Custom(ref mut c) => Some(&mut c.error),
}
}
/// Consumes the `Error`, returning its inner error (if any).
///
/// If this [`Error`] was constructed via [`new`] then this function will
/// return [`Some`], otherwise it will return [`None`].
///
/// [`new`]: Error::new
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_error(err: Error) {
/// if let Some(inner_err) = err.into_inner() {
/// println!("Inner error: {}", inner_err);
/// } else {
/// println!("No inner error");
/// }
/// }
///
/// fn main() {
/// // Will print "No inner error".
/// print_error(Error::last_os_error());
/// // Will print "Inner error: ...".
/// print_error(Error::new(ErrorKind::Other, "oh no!"));
/// }
/// ```
pub fn into_inner(self) -> Option<String> {
match self.repr {
Repr::Os(..) => None,
Repr::Simple(..) => None,
Repr::Custom(c) => Some(c.error),
}
}
/// Returns the corresponding [`ErrorKind`] for this error.
///
/// # Examples
///
/// ```
/// use std::io::{Error, ErrorKind};
///
/// fn print_error(err: Error) {
/// println!("{:?}", err.kind());
/// }
///
/// fn main() {
/// // Will print "Other".
/// print_error(Error::last_os_error());
/// // Will print "AddrInUse".
/// print_error(Error::new(ErrorKind::AddrInUse, "oh no!"));
/// }
/// ```
pub fn kind(&self) -> ErrorKind {
match self.repr {
Repr::Os(_code) => ErrorKind::Other,
Repr::Custom(ref c) => c.kind,
Repr::Simple(kind) => kind,
}
}
}
impl fmt::Debug for Repr {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
match *self {
Repr::Os(code) => fmt
.debug_struct("Os")
.field("code", &code)
.finish(),
Repr::Custom(ref c) => fmt::Debug::fmt(&c, fmt),
Repr::Simple(kind) => fmt.debug_tuple("Kind").field(&kind).finish(),
}
}
}
impl fmt::Display for Error {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
match self.repr {
Repr::Os(code) => {
write!(fmt, "os error {}", code)
}
Repr::Custom(ref c) => c.error.fmt(fmt),
Repr::Simple(kind) => write!(fmt, "{}", kind.as_str()),
}
}
}
fn _assert_error_is_sync_send() {
fn _is_sync_send<T: Sync + Send>() {}
_is_sync_send::<Error>();
}

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@ -0,0 +1,53 @@
use super::{Custom, Error, ErrorKind, Repr};
use crate::error;
use crate::fmt;
use crate::sys::decode_error_kind;
use crate::sys::os::error_string;
#[test]
fn test_debug_error() {
let code = 6;
let msg = error_string(code);
let kind = decode_error_kind(code);
let err = Error {
repr: Repr::Custom(box Custom {
kind: ErrorKind::InvalidInput,
error: box Error { repr: super::Repr::Os(code) },
}),
};
let expected = format!(
"Custom {{ \
kind: InvalidInput, \
error: Os {{ \
code: {:?}, \
kind: {:?}, \
message: {:?} \
}} \
}}",
code, kind, msg
);
assert_eq!(format!("{:?}", err), expected);
}
#[test]
fn test_downcasting() {
#[derive(Debug)]
struct TestError;
impl fmt::Display for TestError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.write_str("asdf")
}
}
impl error::Error for TestError {}
// we have to call all of these UFCS style right now since method
// resolution won't implicitly drop the Send+Sync bounds
let mut err = Error::new(ErrorKind::Other, TestError);
assert!(err.get_ref().unwrap().is::<TestError>());
assert_eq!("asdf", err.get_ref().unwrap().to_string());
assert!(err.get_mut().unwrap().is::<TestError>());
let extracted = err.into_inner().unwrap();
extracted.downcast::<TestError>().unwrap();
}

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@ -0,0 +1,407 @@
#[cfg(test)]
mod tests;
use core::cmp;
use core::fmt;
use crate::io::{
self, Error, ErrorKind, Initializer, IoSlice, IoSliceMut, Read, Seek, SeekFrom, Write,
};
#[cfg(feature="collections")] use crate::io::BufRead;
use core::mem;
#[cfg(feature="alloc")] use alloc::boxed::Box;
#[cfg(feature="collections")] use collections::string::String;
#[cfg(feature="collections")] use collections::vec::Vec;
// =============================================================================
// Forwarding implementations
impl<R: Read + ?Sized> Read for &mut R {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
(**self).read(buf)
}
#[inline]
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
(**self).read_vectored(bufs)
}
#[inline]
fn is_read_vectored(&self) -> bool {
(**self).is_read_vectored()
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
(**self).initializer()
}
#[cfg(feature="collections")]
#[inline]
fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_to_end(buf)
}
#[cfg(feature="collections")]
#[inline]
fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_to_string(buf)
}
#[inline]
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
(**self).read_exact(buf)
}
}
impl<W: Write + ?Sized> Write for &mut W {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
(**self).write(buf)
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
(**self).write_vectored(bufs)
}
#[inline]
fn is_write_vectored(&self) -> bool {
(**self).is_write_vectored()
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
(**self).flush()
}
#[inline]
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
(**self).write_all(buf)
}
#[inline]
fn write_fmt(&mut self, fmt: fmt::Arguments<'_>) -> io::Result<()> {
(**self).write_fmt(fmt)
}
}
impl<S: Seek + ?Sized> Seek for &mut S {
#[inline]
fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
(**self).seek(pos)
}
}
#[cfg(feature="collections")]
impl<B: BufRead + ?Sized> BufRead for &mut B {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> {
(**self).fill_buf()
}
#[inline]
fn consume(&mut self, amt: usize) {
(**self).consume(amt)
}
#[inline]
fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_until(byte, buf)
}
#[inline]
fn read_line(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_line(buf)
}
}
#[cfg(feature="alloc")]
impl<R: Read + ?Sized> Read for Box<R> {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
(**self).read(buf)
}
#[inline]
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
(**self).read_vectored(bufs)
}
#[inline]
fn is_read_vectored(&self) -> bool {
(**self).is_read_vectored()
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
(**self).initializer()
}
#[cfg(feature="collections")]
#[inline]
fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_to_end(buf)
}
#[cfg(feature="collections")]
#[inline]
fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_to_string(buf)
}
#[inline]
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
(**self).read_exact(buf)
}
}
#[cfg(feature="alloc")]
impl<W: Write + ?Sized> Write for Box<W> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
(**self).write(buf)
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
(**self).write_vectored(bufs)
}
#[inline]
fn is_write_vectored(&self) -> bool {
(**self).is_write_vectored()
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
(**self).flush()
}
#[inline]
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
(**self).write_all(buf)
}
#[inline]
fn write_fmt(&mut self, fmt: fmt::Arguments<'_>) -> io::Result<()> {
(**self).write_fmt(fmt)
}
}
#[cfg(feature="alloc")]
impl<S: Seek + ?Sized> Seek for Box<S> {
#[inline]
fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
(**self).seek(pos)
}
}
#[cfg(feature="collections")]
impl<B: BufRead + ?Sized> BufRead for Box<B> {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> {
(**self).fill_buf()
}
#[inline]
fn consume(&mut self, amt: usize) {
(**self).consume(amt)
}
#[inline]
fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> io::Result<usize> {
(**self).read_until(byte, buf)
}
#[inline]
fn read_line(&mut self, buf: &mut String) -> io::Result<usize> {
(**self).read_line(buf)
}
}
// Used by panicking::default_hook
#[cfg(test)]
/// This impl is only used by printing logic, so any error returned is always
/// of kind `Other`, and should be ignored.
impl Write for Box<dyn (::realstd::io::Write) + Send> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
(**self).write(buf).map_err(|_| ErrorKind::Other.into())
}
fn flush(&mut self) -> io::Result<()> {
(**self).flush().map_err(|_| ErrorKind::Other.into())
}
}
// =============================================================================
// In-memory buffer implementations
/// Read is implemented for `&[u8]` by copying from the slice.
///
/// Note that reading updates the slice to point to the yet unread part.
/// The slice will be empty when EOF is reached.
impl Read for &[u8] {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
let amt = cmp::min(buf.len(), self.len());
let (a, b) = self.split_at(amt);
// First check if the amount of bytes we want to read is small:
// `copy_from_slice` will generally expand to a call to `memcpy`, and
// for a single byte the overhead is significant.
if amt == 1 {
buf[0] = a[0];
} else {
buf[..amt].copy_from_slice(a);
}
*self = b;
Ok(amt)
}
#[inline]
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
let mut nread = 0;
for buf in bufs {
nread += self.read(buf)?;
if self.is_empty() {
break;
}
}
Ok(nread)
}
#[inline]
fn is_read_vectored(&self) -> bool {
true
}
#[inline]
unsafe fn initializer(&self) -> Initializer {
Initializer::nop()
}
#[inline]
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
if buf.len() > self.len() {
return Err(Error::new(ErrorKind::UnexpectedEof, "failed to fill whole buffer"));
}
let (a, b) = self.split_at(buf.len());
// First check if the amount of bytes we want to read is small:
// `copy_from_slice` will generally expand to a call to `memcpy`, and
// for a single byte the overhead is significant.
if buf.len() == 1 {
buf[0] = a[0];
} else {
buf.copy_from_slice(a);
}
*self = b;
Ok(())
}
#[cfg(feature="collections")]
#[inline]
fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
buf.extend_from_slice(*self);
let len = self.len();
*self = &self[len..];
Ok(len)
}
}
#[cfg(feature="collections")]
impl BufRead for &[u8] {
#[inline]
fn fill_buf(&mut self) -> io::Result<&[u8]> {
Ok(*self)
}
#[inline]
fn consume(&mut self, amt: usize) {
*self = &self[amt..];
}
}
/// Write is implemented for `&mut [u8]` by copying into the slice, overwriting
/// its data.
///
/// Note that writing updates the slice to point to the yet unwritten part.
/// The slice will be empty when it has been completely overwritten.
impl Write for &mut [u8] {
#[inline]
fn write(&mut self, data: &[u8]) -> io::Result<usize> {
let amt = cmp::min(data.len(), self.len());
let (a, b) = mem::replace(self, &mut []).split_at_mut(amt);
a.copy_from_slice(&data[..amt]);
*self = b;
Ok(amt)
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
let mut nwritten = 0;
for buf in bufs {
nwritten += self.write(buf)?;
if self.is_empty() {
break;
}
}
Ok(nwritten)
}
#[inline]
fn is_write_vectored(&self) -> bool {
true
}
#[inline]
fn write_all(&mut self, data: &[u8]) -> io::Result<()> {
if self.write(data)? == data.len() {
Ok(())
} else {
Err(Error::new(ErrorKind::WriteZero, "failed to write whole buffer"))
}
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
/// Write is implemented for `Vec<u8>` by appending to the vector.
/// The vector will grow as needed.
#[cfg(feature="collections")]
impl Write for Vec<u8> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
self.extend_from_slice(buf);
Ok(buf.len())
}
#[inline]
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
let len = bufs.iter().map(|b| b.len()).sum();
self.reserve(len);
for buf in bufs {
self.extend_from_slice(buf);
}
Ok(len)
}
#[inline]
fn is_write_vectored(&self) -> bool {
true
}
#[inline]
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
self.extend_from_slice(buf);
Ok(())
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}

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@ -0,0 +1,57 @@
use crate::io::prelude::*;
#[bench]
fn bench_read_slice(b: &mut test::Bencher) {
let buf = [5; 1024];
let mut dst = [0; 128];
b.iter(|| {
let mut rd = &buf[..];
for _ in 0..8 {
let _ = rd.read(&mut dst);
test::black_box(&dst);
}
})
}
#[bench]
fn bench_write_slice(b: &mut test::Bencher) {
let mut buf = [0; 1024];
let src = [5; 128];
b.iter(|| {
let mut wr = &mut buf[..];
for _ in 0..8 {
let _ = wr.write_all(&src);
test::black_box(&wr);
}
})
}
#[bench]
fn bench_read_vec(b: &mut test::Bencher) {
let buf = vec![5; 1024];
let mut dst = [0; 128];
b.iter(|| {
let mut rd = &buf[..];
for _ in 0..8 {
let _ = rd.read(&mut dst);
test::black_box(&dst);
}
})
}
#[bench]
fn bench_write_vec(b: &mut test::Bencher) {
let mut buf = Vec::with_capacity(1024);
let src = [5; 128];
b.iter(|| {
let mut wr = &mut buf[..];
for _ in 0..8 {
let _ = wr.write_all(&src);
test::black_box(&wr);
}
})
}

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