lwext4 in Rust

To provide the rust interface, lwext4 is abstracted in Rust language.

lwext4 is an ext2/ext3/ext4 filesystem library in C for microcontrollers

Supported features

• lwext4_rust for x86_64, riscv64 and aarch64 on Rust OS is supported
• File system mount and unmount operations
• Filetypes: regular, directories, softlinks
• Journal recovery & transactions
• memory as Block Cache

Quick start on Rust OS

Wrap up the file operations

Wrap up the file operation struct Ext4File. It can provide the file system interfaces for the upper layer of Rust OS.

For the specific code, please refer to ext4fs.rs

Ext4File operations include: file_read, file_write, file_seek, file_open, file_close, file_rename, lwext4_dir_entries ...

Implement interface for disk operations

These operate the physical disk through the interface of disk driver.

impl KernelDevOp for Disk {
    type DevType = Disk;
    fn read() {}
    fn write() {}
    fn seek() {}
    fn flush() {}
}

Create a file system object

New a file system object, initialize and mount the ext4 file system.

let ext4fs = 
Ext4BlockWrapper::<Disk>::new(disk).expect("failed to initialize EXT4 filesystem");

Linking libc

• No longer need to implement the libc.a

Compile lwext4_rust separately

cargo build -vv --target x86_64-unknown-none | riscv64gc-unknown-none-elf | aarch64-unknown-none-softfloat

OR If you need to compile the lwext4 in C separately,

please run make musl-generic -C c/lwext4 ARCH=<x86_64|riscv64|aarch64>

Dependencies

• only C library on Rust OS
• Rust development environment
• C musl-based cross compile toolchains
  • x86_64-linux-musl-gcc
  • riscv64-linux-musl-gcc
  • aarch64-linux-musl-gcc

Reference

• lwext4
• arceos-lwip