FatFs-Wasm

FatFs is a generic FAT/exFAT filesystem module for small embedded systems, authored by CHaN. FatFs-Wasm is a library which uses a WebAssembly build of FatFs to manipulate FAT image files from node or the browser.

Features:

• Read, write, rename, stat, chmod, and delete files
• Create, iterate, rename, and delete directories
• Supports FAT12, FAT16, and FAT32

Limitations:

• ExFat is not enabled in this build
• LFN is not enabled in this build
• Async drivers not supported

Getting Started

FatFs-Wasm can be used from Node.js or the browser , In the browser, include fatfs-wasm.js, which makes fatfs-wasm available in the window namespace:

<script src="fatfs-wasm.js"></script>
<script>
    const { FatFsDisk } = window['fatfs-wasm']
    // ...
</script>

Using npm

npm install --save fatfs-wasm

Then in Javascript

const { FatFsDisk } = require('fatfs-wasm')

Using

FatFs can be used with typed arrays to create disk images:

const data = new Uint8Array(1 << 23);
const disk = FatFsDisk.create(data);
disk.mkfs();   // Format filesystem
disk.mount();  // Mount workspace

Or open existing ones:

const response = await fetch('disk.img');
const data = new Uint8Array(response.arrayBuffer());
const disk = FatFsDisk.create(data);
disk.mount();  // Mount workspace

Once a workspace is mounted, the library provides APIs for manipulating files:

const file = disk.open('file.txt', FatFsMode.READ);
const buffer = new Uint8Array(1024);
file.read(buffer);
file.close();

// Or, for convenience:
const file = disk.readFile('file.txt');

As well as iterating directories

const dir = disk.open('folder');
for (const file of dir) {
    // ...
}
dir.close();

See the API documentation for details

API Documentation

API Documentation

Modifying FatFs C Code

FatFs has many feature gates defined using the preprocessor. See native/ff15/source/ffconf.h to make adjustments. Please note that any changes to the C code must be reflected in the `src/fatfs.ts`` wrapper, which is not automatically generated. Make changes at your own risk!

To build, open a terminal in MacOS, Linux, or WSL with clang installed and run the build script:

cd native
./build.sh

This will build ff_single.wasm and ff_multi.wasm (multi-partition support) and copy it to the src directory.

Running Tests

npx vitest