BusyBox + Emscripten + nanozip + diff3

BusyBox compiled to WebAssembly using Emscripten. This repo contains build scripts without being a full fork of BusyBox, making version upgrades easier.

Current versions: BusyBox 1.37.0, Emscripten 4.x

Download

Pre-built binaries are available on the Releases page:

• busybox-linux-x86_64 - Native Linux binary
• busybox.js / busybox.wasm - WebAssembly build

Build

Requires Emscripten SDK for WASM builds.

Deno runner

The WASM build is emitted as an ES module (MODULARIZE + EXPORT_ES6) so it can be used directly in Deno. The helper in deno/busybox_runner.ts loads busybox.js/busybox.wasm and exposes a simple run() API. busybox.js/busybox.wasm are expected to live next to the runner in releases or your build output.

# native version
make build/native/busybox

# wasm version
make build/wasm/busybox_unstripped.js

Custom Applets

This repo includes two custom BusyBox applets:

• nanozip - miniz-based imitation of zip utility:

  busybox nanozip [-r] [[-x EXCLUDED_PATH] ...] OUTPUT_NAME.zip INPUT_PATH [...]
  

• diff3 - OpenBSD-based implementation of diff3:

  busybox diff3 [-exEX3] /tmp/d3a.?????????? /tmp/d3b.?????????? file1 file2 file3
  

Credits

The em-shell.c, em-shell.h, em-shell.js files are based on the excellent work by Todd Fleming:

• tbfleming/em-shell
• tbfleming/em-busybox

These have been updated for modern Emscripten (4.x) compatibility.