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Merged
Koichi98 merged 2 commits into from
Jun 11, 2025
Merged

feat(filesystem): Add InMemoryDisk struct #495

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44ac4e5
Add InMemoryDisk struct
Koichi98 Jun 11, 2025
39de3b0
fix memfs Seekfrom
Koichi98 Jun 11, 2025
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1 change: 1 addition & 0 deletions awkernel_lib/src/file.rs
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Original file line number Diff line number Diff line change
@@ -1,3 +1,4 @@
pub mod error;
pub mod fatfs;
pub mod io;
pub mod memfs;
106 changes: 106 additions & 0 deletions awkernel_lib/src/file/memfs.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,106 @@
extern crate alloc;

use super::error::IoError;
use super::io::{IoBase, Read, Seek, SeekFrom, Write};
use alloc::{string::String, vec::Vec};
use core::fmt::{self, Debug};

pub struct InMemoryDisk {
data: Vec<u8>,
position: u64,
}

impl InMemoryDisk {
pub fn new(data: Vec<u8>, position: u64) -> Self {
InMemoryDisk { data, position }
}
}

impl IoBase for InMemoryDisk {
type Error = InMemoryDiskError;
}

impl Read for InMemoryDisk {
fn read(&mut self, buf: &mut [u8]) -> Result<usize, Self::Error> {
let len = (self.data.len() as u64 - self.position) as usize;
let bytes_to_read = core::cmp::min(buf.len(), len);
if bytes_to_read == 0 {
return Ok(0);
}
buf[..bytes_to_read].copy_from_slice(
&self.data[self.position as usize..self.position as usize + bytes_to_read],
);
self.position += bytes_to_read as u64;
Ok(bytes_to_read)
}
}

impl Write for InMemoryDisk {
fn write(&mut self, buf: &[u8]) -> Result<usize, Self::Error> {
let len = (self.data.len() as u64 - self.position) as usize;
let bytes_to_write = core::cmp::min(buf.len(), len);
if bytes_to_write == 0 {
return Ok(0);
}
self.data[self.position as usize..self.position as usize + bytes_to_write]
.copy_from_slice(&buf[..bytes_to_write]);
self.position += bytes_to_write as u64;
Ok(bytes_to_write)
}

fn flush(&mut self) -> Result<(), Self::Error> {
Ok(()) // In-memory, nothing to flush
}
}

impl Seek for InMemoryDisk {
fn seek(&mut self, pos: SeekFrom) -> Result<u64, Self::Error> {
let new_position = match pos {
SeekFrom::Start(offset) => offset as i64,
SeekFrom::Current(offset) => self.position as i64 + offset,
SeekFrom::End(offset) => self.data.len() as i64 + offset,
};

if new_position < 0 || new_position > self.data.len() as i64 {
return Err(InMemoryDiskError::OutOfBounds);
}

self.position = new_position as u64;
Ok(self.position)
}
}

#[derive(Debug)]
pub enum InMemoryDiskError {
OutOfBounds,
WriteZero,
UnexpectedEof,
Interrupted,
Other(String),
}

impl fmt::Display for InMemoryDiskError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
InMemoryDiskError::OutOfBounds => write!(f, "Out of bounds access"),
InMemoryDiskError::WriteZero => write!(f, "Failed to write whole buffer"),
InMemoryDiskError::UnexpectedEof => write!(f, "Failed to fill whole buffer"),
InMemoryDiskError::Interrupted => write!(f, "Operation interrupted"),
InMemoryDiskError::Other(msg) => write!(f, "An error occurred: {msg}"),
}
}
}

impl IoError for InMemoryDiskError {
fn is_interrupted(&self) -> bool {
matches!(self, InMemoryDiskError::Interrupted)
}

fn new_unexpected_eof_error() -> Self {
InMemoryDiskError::UnexpectedEof
}

fn new_write_zero_error() -> Self {
InMemoryDiskError::WriteZero
}
}