zynq-rs/libcoreio/src/io/util.rs

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#![allow(missing_copy_implementations)]
use core::fmt;
use core::mem;
use crate::io::{self, ErrorKind, Initializer, Read, Write};
#[cfg(feature = "collections")] use crate::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 {
#[allow(deprecated)]
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]
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 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);
}
}