forked from M-Labs/rust-fatfs
1f8f8365d6
This functionality is very useful for embedded usage where chrono feature cannot be enabled.
361 lines
13 KiB
Rust
361 lines
13 KiB
Rust
use core;
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use core::cmp;
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use io;
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use io::prelude::*;
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use io::{ErrorKind, SeekFrom};
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use dir_entry::{Date, DateTime, DirEntryEditor};
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use fs::{FileSystem, ReadWriteSeek};
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const MAX_FILE_SIZE: u32 = core::u32::MAX;
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/// A FAT filesystem file object used for reading and writing data.
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///
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/// This struct is created by the `open_file` or `create_file` methods on `Dir`.
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pub struct File<'a, T: ReadWriteSeek + 'a> {
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// Note first_cluster is None if file is empty
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first_cluster: Option<u32>,
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// Note: if offset points between clusters current_cluster is the previous cluster
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current_cluster: Option<u32>,
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// current position in this file
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offset: u32,
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// file dir entry editor - None for root dir
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entry: Option<DirEntryEditor>,
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// file-system reference
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fs: &'a FileSystem<T>,
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}
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impl<'a, T: ReadWriteSeek> File<'a, T> {
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pub(crate) fn new(first_cluster: Option<u32>, entry: Option<DirEntryEditor>, fs: &'a FileSystem<T>) -> Self {
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File {
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first_cluster,
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entry,
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fs,
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current_cluster: None, // cluster before first one
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offset: 0,
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}
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}
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fn update_dir_entry_after_write(&mut self) {
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let offset = self.offset;
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if let Some(ref mut e) = self.entry {
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let now = self.fs.options.time_provider.get_current_date_time();
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e.set_modified(now);
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if e.inner().size().map_or(false, |s| offset > s) {
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e.set_size(offset);
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}
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}
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}
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/// Truncate file in current position.
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pub fn truncate(&mut self) -> io::Result<()> {
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if let Some(ref mut e) = self.entry {
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e.set_size(self.offset);
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if self.offset == 0 {
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e.set_first_cluster(None, self.fs.fat_type());
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}
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}
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if self.offset > 0 {
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debug_assert!(self.current_cluster.is_some());
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// if offset is not 0 current cluster cannot be empty
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self.fs.truncate_cluster_chain(self.current_cluster.unwrap()) // SAFE
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} else {
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debug_assert!(self.current_cluster.is_none());
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if let Some(n) = self.first_cluster {
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self.fs.free_cluster_chain(n)?;
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self.first_cluster = None;
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}
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Ok(())
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}
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}
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pub(crate) fn abs_pos(&self) -> Option<u64> {
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// Returns current position relative to filesystem start
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// Note: when between clusters it returns position after previous cluster
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match self.current_cluster {
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Some(n) => {
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let cluster_size = self.fs.cluster_size();
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let offset_in_cluster = self.offset % cluster_size;
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let offset_in_fs = self.fs.offset_from_cluster(n) + (offset_in_cluster as u64);
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Some(offset_in_fs)
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},
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None => None,
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}
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}
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fn flush_dir_entry(&mut self) -> io::Result<()> {
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if let Some(ref mut e) = self.entry {
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e.flush(self.fs)?;
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}
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Ok(())
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}
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/// Sets date and time of creation for this file.
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///
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/// Note: if `chrono` feature is enabled (default) library automatically updates all timestamps
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pub fn set_created(&mut self, date_time: DateTime) {
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if let Some(ref mut e) = self.entry {
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e.set_created(date_time);
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}
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}
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/// Sets date of last access for this file.
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///
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/// Note: if `chrono` feature is enabled (default) library automatically updates all timestamps
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pub fn set_accessed(&mut self, date: Date) {
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if let Some(ref mut e) = self.entry {
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e.set_accessed(date);
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}
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}
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/// Sets date and time of last modification for this file.
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///
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/// Note: if `chrono` feature is enabled (default) library automatically updates all timestamps
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pub fn set_modified(&mut self, date_time: DateTime) {
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if let Some(ref mut e) = self.entry {
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e.set_modified(date_time);
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}
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}
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fn bytes_left_in_file(&self) -> Option<usize> {
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match self.entry {
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Some(ref e) => e.inner().size().map(|s| (s - self.offset) as usize),
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None => None,
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}
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}
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fn set_first_cluster(&mut self, cluster: u32) {
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self.first_cluster = Some(cluster);
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if let Some(ref mut e) = self.entry {
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e.set_first_cluster(self.first_cluster, self.fs.fat_type());
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}
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}
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pub(crate) fn first_cluster(&self) -> Option<u32> {
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self.first_cluster
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}
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}
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impl<'a, T: ReadWriteSeek> Drop for File<'a, T> {
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fn drop(&mut self) {
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if let Err(err) = self.flush() {
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error!("flush failed {}", err);
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}
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}
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}
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// Note: derive cannot be used because of invalid bounds. See: https://github.com/rust-lang/rust/issues/26925
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impl<'a, T: ReadWriteSeek> Clone for File<'a, T> {
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fn clone(&self) -> Self {
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File {
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first_cluster: self.first_cluster,
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current_cluster: self.current_cluster,
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offset: self.offset,
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entry: self.entry.clone(),
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fs: self.fs,
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}
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}
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}
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impl<'a, T: ReadWriteSeek> Read for File<'a, T> {
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fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
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let cluster_size = self.fs.cluster_size();
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let current_cluster_opt = if self.offset % cluster_size == 0 {
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// next cluster
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match self.current_cluster {
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None => self.first_cluster,
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Some(n) => {
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let r = self.fs.cluster_iter(n).next();
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match r {
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Some(Err(err)) => return Err(err),
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Some(Ok(n)) => Some(n),
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None => None,
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}
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},
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}
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} else {
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self.current_cluster
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};
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let current_cluster = match current_cluster_opt {
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Some(n) => n,
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None => return Ok(0),
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};
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let offset_in_cluster = self.offset % cluster_size;
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let bytes_left_in_cluster = (cluster_size - offset_in_cluster) as usize;
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let bytes_left_in_file = self.bytes_left_in_file().unwrap_or(bytes_left_in_cluster);
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let read_size = cmp::min(cmp::min(buf.len(), bytes_left_in_cluster), bytes_left_in_file);
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if read_size == 0 {
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return Ok(0);
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}
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trace!("read {} bytes in cluster {}", read_size, current_cluster);
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let offset_in_fs = self.fs.offset_from_cluster(current_cluster) + (offset_in_cluster as u64);
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let read_bytes = {
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let mut disk = self.fs.disk.borrow_mut();
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disk.seek(SeekFrom::Start(offset_in_fs))?;
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disk.read(&mut buf[..read_size])?
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};
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if read_bytes == 0 {
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return Ok(0);
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}
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self.offset += read_bytes as u32;
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self.current_cluster = Some(current_cluster);
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if let Some(ref mut e) = self.entry {
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if self.fs.options.update_accessed_date {
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let now = self.fs.options.time_provider.get_current_date();
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e.set_accessed(now);
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}
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}
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Ok(read_bytes)
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}
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}
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impl<'a, T: ReadWriteSeek> Write for File<'a, T> {
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fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
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let cluster_size = self.fs.cluster_size();
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let offset_in_cluster = self.offset % cluster_size;
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let bytes_left_in_cluster = (cluster_size - offset_in_cluster) as usize;
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let bytes_left_until_max_file_size = (MAX_FILE_SIZE - self.offset) as usize;
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let write_size = cmp::min(buf.len(), bytes_left_in_cluster);
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let write_size = cmp::min(write_size, bytes_left_until_max_file_size);
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// Exit early if we are going to write no data
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if write_size == 0 {
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return Ok(0);
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}
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// Get cluster for write possibly allocating new one
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let current_cluster = if self.offset % cluster_size == 0 {
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// next cluster
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let next_cluster = match self.current_cluster {
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None => self.first_cluster,
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Some(n) => {
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let r = self.fs.cluster_iter(n).next();
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match r {
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Some(Err(err)) => return Err(err),
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Some(Ok(n)) => Some(n),
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None => None,
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}
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},
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};
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match next_cluster {
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Some(n) => n,
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None => {
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// end of chain reached - allocate new cluster
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let new_cluster = self.fs.alloc_cluster(self.current_cluster)?;
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trace!("allocated cluser {}", new_cluster);
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if self.first_cluster.is_none() {
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self.set_first_cluster(new_cluster);
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}
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if self.entry.iter().next().map_or(true, |e| e.inner().size().is_none()) {
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// zero new directory cluster
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trace!("zeroing directory cluser {}", new_cluster);
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let abs_pos = self.fs.offset_from_cluster(new_cluster);
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let mut disk = self.fs.disk.borrow_mut();
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disk.seek(SeekFrom::Start(abs_pos))?;
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for _ in 0..cluster_size / 32 {
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let zero = [0u8; 32];
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disk.write(&zero)?;
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}
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}
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new_cluster
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},
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}
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} else {
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// self.current_cluster should be a valid cluster
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match self.current_cluster {
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Some(n) => n,
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None => panic!("Offset inside cluster but no cluster allocated"),
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}
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};
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trace!("write {} bytes in cluster {}", write_size, current_cluster);
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let offset_in_fs = self.fs.offset_from_cluster(current_cluster) + (offset_in_cluster as u64);
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let written_bytes = {
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let mut disk = self.fs.disk.borrow_mut();
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disk.seek(SeekFrom::Start(offset_in_fs))?;
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disk.write(&buf[..write_size])?
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};
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if written_bytes == 0 {
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return Ok(0);
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}
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// some bytes were writter - update position and optionally size
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self.offset += written_bytes as u32;
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self.current_cluster = Some(current_cluster);
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self.update_dir_entry_after_write();
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Ok(written_bytes)
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}
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fn flush(&mut self) -> io::Result<()> {
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self.flush_dir_entry()?;
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let mut disk = self.fs.disk.borrow_mut();
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disk.flush()
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}
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}
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impl<'a, T: ReadWriteSeek> Seek for File<'a, T> {
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fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
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let mut new_pos = match pos {
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SeekFrom::Current(x) => self.offset as i64 + x,
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SeekFrom::Start(x) => x as i64,
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SeekFrom::End(x) => {
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self.entry
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.iter()
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.next()
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.map_or(None, |e| e.inner().size())
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.expect("cannot seek from end if size is unknown") as i64 + x
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},
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};
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if new_pos < 0 {
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return Err(io::Error::new(ErrorKind::InvalidInput, "Seek to a negative offset"));
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}
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new_pos = match self.entry {
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Some(ref e) => {
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if e.inner().size().map_or(false, |s| new_pos > s as i64) {
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info!("seek beyond end of file");
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e.inner().size().unwrap() as i64 // SAFE: map_or returns false if size is empty
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} else {
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new_pos
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}
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},
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_ => new_pos,
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};
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trace!("file seek {} -> {} - entry {:?}", self.offset, new_pos, self.entry);
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if new_pos == self.offset as i64 {
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return Ok(self.offset as u64);
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}
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let cluster_size = self.fs.cluster_size();
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// get number of clusters to seek (favoring previous cluster in corner case)
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let cluster_count = ((new_pos + cluster_size as i64 - 1) / cluster_size as i64 - 1) as isize;
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let old_cluster_count = ((self.offset as i64 + cluster_size as i64 - 1) / cluster_size as i64 - 1) as isize;
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let new_cluster = if new_pos == 0 {
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None
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} else if cluster_count == old_cluster_count {
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self.current_cluster
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} else {
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match self.first_cluster {
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Some(n) => {
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let mut cluster = n;
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let mut iter = self.fs.cluster_iter(n);
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for i in 0..cluster_count {
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cluster = match iter.next() {
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Some(r) => r?,
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None => {
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// chain ends before new position - seek to end of last cluster
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new_pos = (i + 1) as i64 * cluster_size as i64;
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break;
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},
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};
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}
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Some(cluster)
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},
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None => {
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// empty file - always seek to 0
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new_pos = 0;
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None
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},
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}
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};
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self.offset = new_pos as u32;
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self.current_cluster = new_cluster;
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Ok(self.offset as u64)
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}
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}
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