xz-decompress

XZ-Decompress - Streaming XZ decompression for the browser & Node

Part of HTTP Toolkit: powerful tools for building, testing & debugging HTTP(S)

This is an NPM package compatible with both Node.js & browsers that can decompress XZ streams.

You can use this if you want your web server to return XZ-encoded content and have your JavaScript code see the uncompressed data (as an alternative to Gzip or Brotli), or if you want to decompress XZ files within Node.js without needing to mess with any native addons.

This is a fork of https://github.com/SteveSanderson/xzwasm, intended for use in Frida-JS and HTTP Toolkit.

Installation

npm install --save xz-decompress

You can then import things from xz-decompress in your existing JavaScript/TypeScript files. Example:

import { XzReadableStream } from 'xz-decompress';

How to use

Given an XZ-compressed stream, such as a fetch response body, you can get a decompressed response by wrapping it with XzReadableStream. Example:

const compressedResponse = await fetch('somefile.xz');

const decompressedResponse = new Response(
   new XzReadableStream(compressedResponse.body)
);

// We now have a regular Response object, so can use standard APIs to parse its body data,
// such as .text(), .json(), or .arrayBuffer():
const text = await decompressedResponse.text();

The API is designed to be as JavaScript-standard as possible, so XzReadableStream is a ReadableStream instance, which in turn means you can feed it into a Response, and in turn get a blob, an ArrayBuffer, JSON data, or anything else that your runtime can do with a Response.

If you're using this to decompress content from a file or other source, rather than an HTTP response body, you'll need to get a ReadableStream (a web stream) for the file's data to replace the compressedResponse.body stream above. For example, in Node.js you could use Readable.toWeb(fs.createReadStream(filename)) to stream from the disk, or new Blob([buffer]).stream() if you already have the data in a Buffer.

What about .tar.xz files?

Since the .xz format only represents one file, it's common for people to bundle up a collection of files as .tar, and then compress this to .tar.xz.

XZ-Decompress doesn't have built-in support for .tar. However, you can use it to convert a .tar.xz stream to a stream representing the .tar file, and then pass this data to another library such as js-untar or tarballjs to get the bundled files.

Building code in this repo

Note: This is only needed if you want to work on xz-decompress itself, not if you just want to use it.

• Clone this repo
• Clone/update submodules
  • git submodule update --init --recursive
• Ensure you have a working Clang toolchain that can build wasm
  • If running on Linux: npm run setup-wasi-sdk
  • Otherwise you can install https://github.com/WebAssembly/wasi-sdk and export wasisdkroot=/path/to/wasi-sdk
• (For testing only) Ensure you have xz and brotli available as commands on $PATH
• Run make

Building the NPM package contents

• Have node installed
• npm install
• Run make package

Running scenario/perf tests

• Have node installed
• npm install -g http-server
• make run-sample