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Avoid multiple error types in IO traits #13

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Jan 10, 2024
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Avoid multiple error types in IO traits #13

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10 changes: 4 additions & 6 deletions src/fs/ext2/block.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,7 @@ use crate::dev::Device;
use crate::error::Error;
use crate::fs::error::FsError;
use crate::fs::ext2::block_group::BlockGroupDescriptor;
use crate::io::{Read, Seek, SeekFrom, Write};
use crate::io::{Base, Read, Seek, SeekFrom, Write};

/// An ext2 block.
#[derive(Clone)]
Expand Down Expand Up @@ -196,9 +196,11 @@ impl<Dev: Device<u8, Ext2Error>> From<Block<Dev>> for u32 {
}
}

impl<Dev: Device<u8, Ext2Error>> Read for Block<Dev> {
impl<Dev: Device<u8, Ext2Error>> Base for Block<Dev> {
type Error = Ext2Error;
}

impl<Dev: Device<u8, Ext2Error>> Read for Block<Dev> {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> Result<usize, Error<Ext2Error>> {
let fs = self.filesystem.borrow();
Expand All @@ -217,8 +219,6 @@ impl<Dev: Device<u8, Ext2Error>> Read for Block<Dev> {
}

impl<Dev: Device<u8, Ext2Error>> Write for Block<Dev> {
type Error = Ext2Error;

#[inline]
fn write(&mut self, buf: &[u8]) -> Result<usize, Error<Ext2Error>> {
let fs = self.filesystem.borrow();
Expand All @@ -244,8 +244,6 @@ impl<Dev: Device<u8, Ext2Error>> Write for Block<Dev> {
}

impl<Dev: Device<u8, Ext2Error>> Seek for Block<Dev> {
type Error = Ext2Error;

#[inline]
fn seek(&mut self, pos: SeekFrom) -> Result<u64, Error<Ext2Error>> {
let fs = self.filesystem.borrow();
Expand Down
18 changes: 7 additions & 11 deletions src/fs/ext2/file.rs
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Expand Up @@ -22,7 +22,7 @@ use crate::file::{self, DirectoryEntry, Stat};
use crate::fs::error::FsError;
use crate::fs::ext2::block::Block;
use crate::fs::PATH_MAX;
use crate::io::{Read, Seek, SeekFrom, Write};
use crate::io::{Base, Read, Seek, SeekFrom, Write};
use crate::types::{Blkcnt, Blksize, Dev, Gid, Ino, Mode, Nlink, Off, Time, Timespec, Uid};

/// Limit in bytes for the length of a pointed path of a symbolic link to be store in an inode and not in a separate data block.
Expand Down Expand Up @@ -147,9 +147,11 @@ pub struct Regular<D: Device<u8, Ext2Error>> {
file: File<D>,
}

impl<D: Device<u8, Ext2Error>> Read for File<D> {
impl<D: Device<u8, Ext2Error>> Base for File<D> {
type Error = Ext2Error;
}

impl<D: Device<u8, Ext2Error>> Read for File<D> {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> Result<usize, Error<Self::Error>> {
let filesystem = self.filesystem.borrow();
Expand Down Expand Up @@ -186,8 +188,6 @@ struct BlockWithState {
}

impl<D: Device<u8, Ext2Error>> Write for File<D> {
type Error = Ext2Error;

#[inline]
#[allow(clippy::too_many_lines)]
#[allow(clippy::cognitive_complexity)] // TODO: make this understandable for a human
Expand Down Expand Up @@ -673,8 +673,6 @@ impl<D: Device<u8, Ext2Error>> Write for File<D> {
}

impl<D: Device<u8, Ext2Error>> Seek for File<D> {
type Error = Ext2Error;

#[inline]
fn seek(&mut self, pos: SeekFrom) -> Result<u64, Error<Ext2Error>> {
// SAFETY: it is safe to assume that the file length is smaller than 2^63 bytes long
Expand Down Expand Up @@ -756,18 +754,18 @@ impl<D: Device<u8, Ext2Error>> file::File for Regular<D> {
}
}

impl<D: Device<u8, Ext2Error>> Read for Regular<D> {
impl<D: Device<u8, Ext2Error>> Base for Regular<D> {
type Error = Ext2Error;
}

impl<D: Device<u8, Ext2Error>> Read for Regular<D> {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> Result<usize, Error<Ext2Error>> {
self.file.read(buf)
}
}

impl<D: Device<u8, Ext2Error>> Write for Regular<D> {
type Error = Ext2Error;

#[inline]
fn write(&mut self, buf: &[u8]) -> Result<usize, Error<Ext2Error>> {
self.file.write(buf)
Expand All @@ -780,8 +778,6 @@ impl<D: Device<u8, Ext2Error>> Write for Regular<D> {
}

impl<D: Device<u8, Ext2Error>> Seek for Regular<D> {
type Error = Ext2Error;

#[inline]
fn seek(&mut self, pos: SeekFrom) -> Result<u64, Error<Ext2Error>> {
self.file.seek(pos)
Expand Down
56 changes: 9 additions & 47 deletions src/io.rs
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Expand Up @@ -2,13 +2,16 @@

use crate::error::Error;

/// Allows for reading bytes from a source.
///
/// See [`std::io::Read`] for more information: this trait is a `no_std` based variant.
pub trait Read {
/// Base I/O trait that must be implemented for all types implementing [`Read`], [`Write`] or [`Seek`].
pub trait Base {
/// Error type corresponding to the [`FileSystem`](crate::fs::FileSystem) implemented.
type Error: core::error::Error;
}

/// Allows for reading bytes from a source.
///
/// See [`std::io::Read`] for more information: this trait is a `no_std` based variant.
pub trait Read: Base {
/// Pull some bytes from this source into the specified buffer, returning how many bytes were read.
///
/// If the returned number is 0, the reader is considered as ended.
Expand All @@ -23,23 +26,10 @@ pub trait Read {
fn read(&mut self, buf: &mut [u8]) -> Result<usize, Error<Self::Error>>;
}

#[cfg(feature = "std")]
impl<S: std::io::Read> Read for S {
type Error = std::io::Error;

#[inline]
fn read(&mut self, buf: &mut [u8]) -> Result<usize, Error<Self::Error>> {
std::io::Read::read(self, buf).map_err(Error::IO)
}
}

/// Allows for writing bytes to a destination.
///
/// See [`std::io::Write`] for more information: this trait is a `no_std` based variant.
pub trait Write {
/// Error type corresponding to the [`FileSystem`](crate::fs::FileSystem) implemented.
type Error: core::error::Error;

pub trait Write: Base {
/// Write a buffer into this writer, returning how many bytes were written.
///
/// If the returned number is 0, either the writer is ended or cannot add any more bytes at its end.
Expand All @@ -63,21 +53,6 @@ pub trait Write {
fn flush(&mut self) -> Result<(), Error<Self::Error>>;
}

#[cfg(feature = "std")]
impl<S: std::io::Write> Write for S {
type Error = std::io::Error;

#[inline]
fn write(&mut self, buf: &[u8]) -> Result<usize, Error<Self::Error>> {
std::io::Write::write(self, buf).map_err(Error::IO)
}

#[inline]
fn flush(&mut self) -> Result<(), Error<Self::Error>> {
std::io::Write::flush(self).map_err(Error::IO)
}
}

/// Enumeration of possible methods to seek within an I/O object.
///
/// See [`std::io::SeekFrom`] for more information.
Expand Down Expand Up @@ -124,10 +99,7 @@ impl From<SeekFrom> for std::io::SeekFrom {
/// Provides a cursor which can be moved within a stream of bytes.
///
/// See [`std::io::Seek`] for more information: this trait is a `no_std` based variant.
pub trait Seek {
/// Error type corresponding to the [`FileSystem`](crate::fs::FileSystem) implemented.
type Error: core::error::Error;

pub trait Seek: Base {
/// Seek to an offset, in bytes, in a stream.
///
/// See [`seek`](https://docs.rs/no_std_io/latest/no_std_io/io/trait.Seek.html#tymethod.seek) for more information.
Expand All @@ -137,13 +109,3 @@ pub trait Seek {
/// Returns an [`DevError`](crate::dev::error::DevError) if the device on which the directory is located could not be read.
fn seek(&mut self, pos: SeekFrom) -> Result<u64, Error<Self::Error>>;
}

#[cfg(feature = "std")]
impl<S: std::io::Seek> Seek for S {
type Error = std::io::Error;

#[inline]
fn seek(&mut self, pos: SeekFrom) -> Result<u64, Error<Self::Error>> {
std::io::Seek::seek(self, pos.into()).map_err(Error::IO)
}
}