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// Copyright 2022 The ChromiumOS Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
use std::fs::File;
use std::io::Error;
use std::io::ErrorKind;
use std::io::Result;
use crate::VolatileSlice;
/// A trait for flushing the contents of a file to disk.
/// This is equivalent to File's `sync_all` and `sync_data` methods, but wrapped in a trait so that
/// it can be implemented for other types.
pub trait FileSync {
// Flush buffers related to this file to disk.
fn fsync(&mut self) -> Result<()>;
// Flush buffers related to this file's data to disk, avoiding updating extra metadata. Note
// that an implementation may simply implement fsync for fdatasync.
fn fdatasync(&mut self) -> Result<()>;
}
impl FileSync for File {
fn fsync(&mut self) -> Result<()> {
self.sync_all()
}
fn fdatasync(&mut self) -> Result<()> {
self.sync_data()
}
}
/// A trait for setting the size of a file.
/// This is equivalent to File's `set_len` method, but
/// wrapped in a trait so that it can be implemented for
/// other types.
pub trait FileSetLen {
// Set the size of this file.
// This is the moral equivalent of `ftruncate()`.
fn set_len(&self, _len: u64) -> Result<()>;
}
impl FileSetLen for File {
fn set_len(&self, len: u64) -> Result<()> {
File::set_len(self, len)
}
}
/// A trait for allocating disk space in a sparse file.
/// This is equivalent to fallocate() with no special flags.
pub trait FileAllocate {
/// Allocate storage for the region of the file starting at `offset` and extending `len` bytes.
fn allocate(&mut self, offset: u64, len: u64) -> Result<()>;
}
/// A trait for getting the size of a file.
/// This is equivalent to File's metadata().len() method,
/// but wrapped in a trait so that it can be implemented for
/// other types.
pub trait FileGetLen {
/// Get the current length of the file in bytes.
fn get_len(&self) -> Result<u64>;
}
impl FileGetLen for File {
fn get_len(&self) -> Result<u64> {
Ok(self.metadata()?.len())
}
}
/// A trait similar to `Read` and `Write`, but uses volatile memory as buffers.
pub trait FileReadWriteVolatile {
/// Read bytes from this file into the given slice, returning the number of bytes read on
/// success.
fn read_volatile(&mut self, slice: VolatileSlice) -> Result<usize>;
/// Like `read_volatile`, except it reads to a slice of buffers. Data is copied to fill each
/// buffer in order, with the final buffer written to possibly being only partially filled. This
/// method must behave as a single call to `read_volatile` with the buffers concatenated would.
/// The default implementation calls `read_volatile` with either the first nonempty buffer
/// provided, or returns `Ok(0)` if none exists.
fn read_vectored_volatile(&mut self, bufs: &[VolatileSlice]) -> Result<usize> {
bufs.iter()
.find(|b| b.size() > 0)
.map(|&b| self.read_volatile(b))
.unwrap_or(Ok(0))
}
/// Reads bytes from this into the given slice until all bytes in the slice are written, or an
/// error is returned.
fn read_exact_volatile(&mut self, mut slice: VolatileSlice) -> Result<()> {
while slice.size() > 0 {
let bytes_read = self.read_volatile(slice)?;
if bytes_read == 0 {
return Err(Error::from(ErrorKind::UnexpectedEof));
}
// Will panic if read_volatile read more bytes than we gave it, which would be worthy of
// a panic.
slice = slice.offset(bytes_read).unwrap();
}
Ok(())
}
/// Write bytes from the slice to the given file, returning the number of bytes written on
/// success.
fn write_volatile(&mut self, slice: VolatileSlice) -> Result<usize>;
/// Like `write_volatile`, except that it writes from a slice of buffers. Data is copied from
/// each buffer in order, with the final buffer read from possibly being only partially
/// consumed. This method must behave as a call to `write_volatile` with the buffers
/// concatenated would. The default implementation calls `write_volatile` with either the first
/// nonempty buffer provided, or returns `Ok(0)` if none exists.
fn write_vectored_volatile(&mut self, bufs: &[VolatileSlice]) -> Result<usize> {
bufs.iter()
.find(|b| b.size() > 0)
.map(|&b| self.write_volatile(b))
.unwrap_or(Ok(0))
}
/// Write bytes from the slice to the given file until all the bytes from the slice have been
/// written, or an error is returned.
fn write_all_volatile(&mut self, mut slice: VolatileSlice) -> Result<()> {
while slice.size() > 0 {
let bytes_written = self.write_volatile(slice)?;
if bytes_written == 0 {
return Err(Error::from(ErrorKind::WriteZero));
}
// Will panic if read_volatile read more bytes than we gave it, which would be worthy of
// a panic.
slice = slice.offset(bytes_written).unwrap();
}
Ok(())
}
}
impl<'a, T: FileReadWriteVolatile + ?Sized> FileReadWriteVolatile for &'a mut T {
fn read_volatile(&mut self, slice: VolatileSlice) -> Result<usize> {
(**self).read_volatile(slice)
}
fn read_vectored_volatile(&mut self, bufs: &[VolatileSlice]) -> Result<usize> {
(**self).read_vectored_volatile(bufs)
}
fn read_exact_volatile(&mut self, slice: VolatileSlice) -> Result<()> {
(**self).read_exact_volatile(slice)
}
fn write_volatile(&mut self, slice: VolatileSlice) -> Result<usize> {
(**self).write_volatile(slice)
}
fn write_vectored_volatile(&mut self, bufs: &[VolatileSlice]) -> Result<usize> {
(**self).write_vectored_volatile(bufs)
}
fn write_all_volatile(&mut self, slice: VolatileSlice) -> Result<()> {
(**self).write_all_volatile(slice)
}
}
/// A trait similar to the unix `ReadExt` and `WriteExt` traits, but for volatile memory.
pub trait FileReadWriteAtVolatile {
/// Reads bytes from this file at `offset` into the given slice, returning the number of bytes
/// read on success. On Windows file pointer will update with the read, but on Linux the
/// file pointer will not change.
fn read_at_volatile(&mut self, slice: VolatileSlice, offset: u64) -> Result<usize>;
/// Like `read_at_volatile`, except it reads to a slice of buffers. Data is copied to fill each
/// buffer in order, with the final buffer written to possibly being only partially filled. This
/// method must behave as a single call to `read_at_volatile` with the buffers concatenated
/// would. The default implementation calls `read_at_volatile` with either the first nonempty
/// buffer provided, or returns `Ok(0)` if none exists.
/// On Windows file pointer will update with the read, but on Linux the file pointer will not
/// change.
fn read_vectored_at_volatile(&mut self, bufs: &[VolatileSlice], offset: u64) -> Result<usize> {
if let Some(&slice) = bufs.first() {
self.read_at_volatile(slice, offset)
} else {
Ok(0)
}
}
/// Reads bytes from this file at `offset` into the given slice until all bytes in the slice are
/// read, or an error is returned. On Windows file pointer will update with the read, but on
/// Linux the file pointer will not change.
fn read_exact_at_volatile(&mut self, mut slice: VolatileSlice, mut offset: u64) -> Result<()> {
while slice.size() > 0 {
match self.read_at_volatile(slice, offset) {
Ok(0) => return Err(Error::from(ErrorKind::UnexpectedEof)),
Ok(n) => {
slice = slice.offset(n).unwrap();
offset = offset.checked_add(n as u64).unwrap();
}
Err(ref e) if e.kind() == ErrorKind::Interrupted => {}
Err(e) => return Err(e),
}
}
Ok(())
}
/// Writes bytes to this file at `offset` from the given slice, returning the number of bytes
/// written on success. On Windows file pointer will update with the write, but on Linux the
/// file pointer will not change.
fn write_at_volatile(&mut self, slice: VolatileSlice, offset: u64) -> Result<usize>;
/// Like `write_at_volatile`, except that it writes from a slice of buffers. Data is copied
/// from each buffer in order, with the final buffer read from possibly being only partially
/// consumed. This method must behave as a call to `write_at_volatile` with the buffers
/// concatenated would. The default implementation calls `write_at_volatile` with either the
/// first nonempty buffer provided, or returns `Ok(0)` if none exists.
/// On Windows file pointer will update with the write, but on Linux the file pointer will not
/// change.
fn write_vectored_at_volatile(&mut self, bufs: &[VolatileSlice], offset: u64) -> Result<usize> {
if let Some(&slice) = bufs.first() {
self.write_at_volatile(slice, offset)
} else {
Ok(0)
}
}
/// Writes bytes to this file at `offset` from the given slice until all bytes in the slice
/// are written, or an error is returned. On Windows file pointer will update with the write,
/// but on Linux the file pointer will not change.
fn write_all_at_volatile(&mut self, mut slice: VolatileSlice, mut offset: u64) -> Result<()> {
while slice.size() > 0 {
match self.write_at_volatile(slice, offset) {
Ok(0) => return Err(Error::from(ErrorKind::WriteZero)),
Ok(n) => {
slice = slice.offset(n).unwrap();
offset = offset.checked_add(n as u64).unwrap();
}
Err(ref e) if e.kind() == ErrorKind::Interrupted => {}
Err(e) => return Err(e),
}
}
Ok(())
}
}
impl<'a, T: FileReadWriteAtVolatile + ?Sized> FileReadWriteAtVolatile for &'a mut T {
fn read_at_volatile(&mut self, slice: VolatileSlice, offset: u64) -> Result<usize> {
(**self).read_at_volatile(slice, offset)
}
fn read_vectored_at_volatile(&mut self, bufs: &[VolatileSlice], offset: u64) -> Result<usize> {
(**self).read_vectored_at_volatile(bufs, offset)
}
fn read_exact_at_volatile(&mut self, slice: VolatileSlice, offset: u64) -> Result<()> {
(**self).read_exact_at_volatile(slice, offset)
}
fn write_at_volatile(&mut self, slice: VolatileSlice, offset: u64) -> Result<usize> {
(**self).write_at_volatile(slice, offset)
}
fn write_vectored_at_volatile(&mut self, bufs: &[VolatileSlice], offset: u64) -> Result<usize> {
(**self).write_vectored_at_volatile(bufs, offset)
}
fn write_all_at_volatile(&mut self, slice: VolatileSlice, offset: u64) -> Result<()> {
(**self).write_all_at_volatile(slice, offset)
}
}
#[cfg(test)]
mod tests {
use std::io::Read;
use std::io::Seek;
use std::io::SeekFrom;
use std::io::Write;
use tempfile::tempfile;
use super::*;
#[test]
fn read_file() -> Result<()> {
let mut f = tempfile()?;
f.write_all(b"AAAAAAAAAAbbbbbbbbbbAAAAA")
.expect("Failed to write bytes");
f.seek(SeekFrom::Start(0))?;
let mut omem = [0u8; 30];
let om = &mut omem[..];
let buf = VolatileSlice::new(om);
f.read_volatile(buf).expect("read_volatile failed.");
f.seek(SeekFrom::Start(0))?;
let mut mem = [0u8; 30];
let (m1, rest) = mem.split_at_mut(10);
let (m2, m3) = rest.split_at_mut(10);
let buf1 = VolatileSlice::new(m1);
let buf2 = VolatileSlice::new(m2);
let buf3 = VolatileSlice::new(m3);
let bufs = [buf1, buf2, buf3];
f.read_vectored_volatile(&bufs)
.expect("read_vectored_volatile failed.");
assert_eq!(&mem[..], b"AAAAAAAAAAbbbbbbbbbbAAAAA\0\0\0\0\0");
Ok(())
}
#[test]
fn write_file() -> Result<()> {
let mut f = tempfile()?;
let mut omem = [0u8; 25];
let om = &mut omem[..];
let buf = VolatileSlice::new(om);
buf.write_bytes(65);
f.write_volatile(buf).expect("write_volatile failed.");
f.seek(SeekFrom::Start(0))?;
let mut filebuf = [0u8; 25];
f.read_exact(&mut filebuf).expect("Failed to read filebuf");
assert_eq!(&filebuf, b"AAAAAAAAAAAAAAAAAAAAAAAAA");
Ok(())
}
#[test]
fn write_vectored_file() -> Result<()> {
let mut f = tempfile()?;
let mut mem = [0u8; 30];
let (m1, rest) = mem.split_at_mut(10);
let (m2, m3) = rest.split_at_mut(10);
let buf1 = VolatileSlice::new(m1);
let buf2 = VolatileSlice::new(m2);
let buf3 = VolatileSlice::new(m3);
buf1.write_bytes(65);
buf2.write_bytes(98);
buf3.write_bytes(65);
let bufs = [buf1, buf2, buf3];
f.write_vectored_volatile(&bufs)
.expect("write_vectored_volatile failed.");
f.seek(SeekFrom::Start(0))?;
let mut filebuf = [0u8; 30];
f.read_exact(&mut filebuf).expect("Failed to read filebuf.");
assert_eq!(&filebuf, b"AAAAAAAAAAbbbbbbbbbbAAAAAAAAAA");
Ok(())
}
#[test]
fn read_at_file() -> Result<()> {
let mut f = tempfile()?;
f.write_all(b"AAAAAAAAAAbbbbbbbbbbAAAAA")
.expect("Failed to write bytes.");
let mut omem = [0u8; 20];
let om = &mut omem[..];
let buf = VolatileSlice::new(om);
f.read_at_volatile(buf, 10)
.expect("read_at_volatile failed.");
assert_eq!(om, b"bbbbbbbbbbAAAAA\0\0\0\0\0");
let mut mem = [0u8; 20];
let (m1, m2) = mem.split_at_mut(10);
let buf1 = VolatileSlice::new(m1);
let buf2 = VolatileSlice::new(m2);
let bufs = [buf1, buf2];
f.read_vectored_at_volatile(&bufs, 10)
.expect("read_vectored_at_volatile failed.");
assert_eq!(&mem[..], b"bbbbbbbbbbAAAAA\0\0\0\0\0");
Ok(())
}
#[test]
fn write_at_file() -> Result<()> {
let mut f = tempfile()?;
f.write_all(b"ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ")
.expect("Failed to write bytes");
let mut omem = [0u8; 15];
let om = &mut omem[..];
let buf = VolatileSlice::new(om);
buf.write_bytes(65);
f.write_at_volatile(buf, 10)
.expect("write_at_volatile failed.");
f.seek(SeekFrom::Start(0))?;
let mut filebuf = [0u8; 30];
f.read_exact(&mut filebuf).expect("Failed to read filebuf.");
assert_eq!(&filebuf, b"ZZZZZZZZZZAAAAAAAAAAAAAAAZZZZZ");
Ok(())
}
#[test]
fn write_vectored_at_file() -> Result<()> {
let mut f = tempfile()?;
f.write_all(b"ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ")
.expect("Failed to write bytes");
let mut mem = [0u8; 30];
let (m1, m2) = mem.split_at_mut(10);
let buf1 = VolatileSlice::new(m1);
let buf2 = VolatileSlice::new(m2);
buf1.write_bytes(65);
buf2.write_bytes(98);
let bufs = [buf1, buf2];
f.write_vectored_at_volatile(&bufs, 10)
.expect("write_vectored_at_volatile failed.");
f.seek(SeekFrom::Start(0))?;
let mut filebuf = [0u8; 30];
f.read_exact(&mut filebuf).expect("Failed to read filebuf.");
assert_eq!(&filebuf, b"ZZZZZZZZZZAAAAAAAAAAbbbbbbbbbb");
Ok(())
}
}