VFAT / FAT32

A simple VFAT implementation written in rust, and mostly tested against Linux's vfat driver.

It aims to be straightforward to understand and easy to use in a custom kernel.

It supports all the basic operations:

• File and directory creation,
• File reading and writing,
• Directory and file deletion,
• Metadata updates,
• Backup FAT writing
• Deleted clusters and directory entry slots are reused.

It needs better support for defragmentation — there is no defragmentation tool to consolidate free space.

no_std

This component was first developed with no_std in mind. std is supported behind a feature flag, and it is used for integration testing.

Using it in your kernel

The exported apis are in the api module. The OS should provide:

• An implementation for the TimeManagerTrait. This is used for timestamping file creation and update.
• An implementation for the device trait. This is used to interact with the disk.
• alloc support — the library relies on the alloc crate (but not std) for heap-allocated types; like Box, Arc and String.

Run example

The example runs in userspace. To run the example, first create a vfat fs using the script tests/setup.sh. This script:

• creates a vfat fs,
• mounts it,
• writes a bunch of files and directories (using your kernel's driver)
• unmounts it.

This file is also used for running integration tests. Your user needs sudo access for mount and unmount commands:

fponzi ALL=(ALL) NOPASSWD: /usr/bin/mount,/usr/bin/umount

Then, you're ready to run the example file using:

cargo run --example simple --features std

Benchmarks

CI runs benchmarks on every push to master and publishes historical results with trend charts to the benchmark dashboard. If a benchmark regresses by more than 50%, an alert comment is created automatically.