lamfat

A no_std FAT12/16/32 filesystem library — read and write — for embedded and UEFI-bootloader contexts that need to read a kernel (or write a config) on a FAT volume without a userspace filesystem stack.

Faithful republish of rafalh/rust-fatfs. See PROVENANCE.md for the exact upstream commit and the full list of changes from upstream.

What it does

Given any seekable byte source (IoBase + Read + Write + Seek) holding a FAT volume:

Mounts the volume and exposes the root directory.
Reads and writes files; creates and removes files and directories.
Handles FAT12, FAT16, and FAT32, short (8.3) and long file names (lfn).

It is the same battle-tested fatfs engine, repackaged under a distinct crate name so it can be a published dependency of the LamBoot bootloader family and packaged for Debian/Fedora. The on-disk format logic is unchanged from upstream.

Usage sketch

use lamfat::{FileSystem, FsOptions};

// `disk` is anything implementing lamfat's IoBase + Read + Write + Seek over the
// FAT volume's bytes — a block device, a partition, or (with the std feature) a
// file wrapped in a buffering stream.
fn list_root<D: lamfat::ReadWriteSeek>(disk: D) -> Result<(), lamfat::Error<D::Error>> {
    let fs = FileSystem::new(disk, FsOptions::new())?;
    for entry in fs.root_dir().iter() {
        let entry = entry?;
        let _name = entry.file_name();
    }
    Ok(())
}

Complete examples (ls, cat, write, mkfatfs, partition) are in the examples/ directory.

Features

std — enable std::io integration (off by default; the crate is no_std).
alloc — long-filename and format paths that need allocation.
lfn — long file name (VFAT) support.
unicode — full Unicode case handling for file names.
log_level_error / _warn / _info — compile-time log verbosity ceilings.

chrono (timestamps) is available as an opt-in dependency but is off by default, so the default dependency tree is just bitflags + log.

no_std

Set default-features = false for no_std operation. alloc is required for long file names and formatting; the core read path works without it.

License