Node-liblzma

What is liblzma/XZ ?

XZ is a container for compressed archives. It is among the best compressors out there according to several benchmarks:

• Gzip vs Bzip2 vs LZMA vs XZ vs LZ4 vs LZO
• Large Text Compression Benchmark
• Linux Compression Comparison (GZIP vs BZIP2 vs LZMA vs ZIP vs Compress)

It has a good balance between compression time/ratio and decompression time/memory.

About this project

This project aims towards providing:

• A quick and easy way to play with XZ compression: Quick and easy as it conforms to zlib API, so that switching from zlib/deflate to xz might be as easy as a string search/replace in your code editor 😄

• Complete integration with XZ sources/binaries: You can either use system packages or download a specific version and compile it! See installation below.

Only LZMA2 is supported for compression output. But the library can open and read any LZMA1 or LZMA2 compressed file.

What's new ?

It has been quite some time since I first published this package. In the meantime, N-API eventually became the de facto standard to provide stable ABI API for NodeJS Native Modules.

It therefore replaces good ol' nan !

It supports all NodeJS versions >= 12 and lots has been done to change CICD pipelines and testing.

It has been tested and works on:

• Linux x64 (Ubuntu)
• OSX (macos-11)
• Raspberry Pi 2/3/4 (both on 32-bit and 64-bit architectures)
• Windows (windows-2019 and windows-2022 are part of GitHub CI)

Notes:

• For Windows There is no "global" installation of the LZMA library on the Windows machine provisionned by GitHub, so it is pointless to build with this config

• For Linux
• For MacOS

Prebuilt images

Several prebuilt versions are bundled within the package.

• Windows x86_64
• Linux x86_64
• MacOS x86_64 / Arm64

If your OS/architecture matches, you will use this version which has been compiled using the following default flags:

Flag	Description	Default value	Possible values
USE_GLOBAL	Should the library use the system provided DLL/.so library ?	yes (no if OS is Windows)	yes or no
RUNTIME_LINK	Should the library be linked statically or use the shared LZMA library ?	shared	static or shared
ENABLE_THREAD_SUPPORT	Does the LZMA library support threads ?	yes	yes or no

If not node-gyp will automagically start compiling stuff according to the environment variables set, or the default values above.

If you want to change compilation flags, please read on here.

Related projects

Thanks to the community, there are several choices out there:

• lzma-purejs A pure JavaScript implementation of the algorithm
• node-xz Node binding of XZ library
• lzma-native A very complete implementation of XZ library bindings
• Others are also available but they fork "xz" process in the background.

API comparison

var lzma = require('node-liblzma');

Zlib	XZlib	Arguments
createGzip	createXz	([lzma_options, [options]])
createGunzip	createUnxz	([lzma_options, [options]])
gzip	xz	(buf, [options], callback)
gunzip	unxz	(buf, [options], callback)
gzipSync	xzSync	(buf, [options])
gunzipSync	unxzSync	(buf, [options])

Constants

options is an Object with the following possible attributes:

Attribute	Type	Available options
check	Uint32	NONE
	CRC32
	CRC64
	SHA256
preset	Uint32	DEFAULT
	EXTREME
flag	Uint32	TELL_NO_CHECK
	TELL_UNSUPPORTED_CHECK
	TELL_ANY_CHECK
	CONCATENATED
mode	Uint32	FAST
	NORMAL
filters	Array	LZMA2 (added by default)
	X86
	POWERPC
	IA64
	ARM
	ARMTHUMB
	SPARC

For further information about each of these flags, you will find reference at XZ SDK.

Installation

Well, as simple as this one-liner:

$ npm i node-liblzma --save

--OR--

$ yarn add node-liblzma

If you want to recompile the source, for example to disable threading support in the module, then you have to opt out with:

$ ENABLE_THREAD_SUPPORT=no npm install node-liblzma --build-from-source

Note: Enabling thread support in the library will NOT work if the LZMA library itself has been built without such support.

To build the module, you have the following options:

1. Using system development libraries
2. Ask the build system to download xz and build it
3. Compile xz yourself, outside node-liblzma, and have it use it after

Using system dev libraries to compile

You need to have the development package installed on your system. If you have Debian based distro:

# apt-get install liblzma-dev

Automatic download and compilation to statically link xz

If you do not plan on having a local install, you can ask for automatic download and build of whatever version of xz you want.

Just do:

$ npm install node-liblzma --build-from-source

When no option is given in the commandline arguments, it will build with default values.

Local install of xz sources (outside node-liblzma)

So you did install xz somewhere outside the module and want the module to use it.

For that, you need to set the include directory and library directory search paths as GCC environment variables.

$ export CPATH=$HOME/path/to/headers
$ export LIBRARY_PATH=$HOME/path/to/lib
$ export LD_LIBRARY_PATH=$HOME/path/to/lib:$LD_LIBRARY_PATH

The latest is needed for tests to be run right after.

Once done, this should suffice:

$ npm install

Tests

You can run tests with:

$ npm test

It will build and launch tests suite with Mocha.

Usage

As the API is very close to NodeJS Zlib, you will probably find a good reference there.

Otherwise examples can be found as part of the test suite, so feel free to use them! They are written in CoffeeScript.

Bugs

If you find one, feel free to contribute and post a new issue! PR are accepted as well :)

Kudos goes to addaleax for helping me out with C++ stuff !

If you compile with threads, you may see a bunch of warnings about -Wmissing-field-initializers. This is normal and does not prevent threading from being active and working. I did not yet figure how to fix this except by masking the warning..

License

This software is released under LGPL3.0+