Bzip2 `bzip2/`

Type: Compression Library
License: bzip2 License (BSD-like)
Fork Origin: GitLab | Sourceware
Status: Detached Fork (independently maintained) Latest Version: 0.0.5-1

Overview

Bzip2/libbz2 is a program and library for lossless, block-sorting data compression. It typically compresses files to within 10% to 15% of the best available techniques (PPM family), while being around twice as fast at compression and six times faster at decompression.

This repository contains a maintained fork that now advances in its own tree while staying compatible with upstream.

Usage in ProjT Launcher

Bzip2 is used for:

Mod archive extraction — Some modpacks use bzip2 compression
Legacy support — Older Minecraft assets may use bzip2
Download optimization — Efficient compression for large files

Documentation

Resource	Description
Compiling Guide	Build instructions (Meson & CMake)
Test Suite	Quick and large test suites
Test Files	Test file collection
Original Manual	Upstream plain-text manual
`bzip2/manual.html`	Full API documentation

Build Systems

Bzip2 supports two build systems:

Build System	Platform Support	Recommended For
Meson	Unix, Windows	Unix-like systems
CMake	Unix, Windows	Cross-platform builds

For detailed build instructions, see bzip2-compiling.md.

Quick Build (CMake)

cd bzip2
mkdir build && cd build
cmake .. -DCMAKE_BUILD_TYPE=Release
cmake --build .
ctest -V

Contributing

The bzip2 development happens in the ProjT Launcher repository:

Branch	Purpose
`develop`	Main development branch
`release-*`	Stable release branches
Feature branches	Experimental work (may be rebased)

Report Issues

Please report bugs via GitHub Issues.

⚠️ Important Notices

Warning

This program and library compresses data by performing several non-trivial transformations. Unless you are 100% familiar with all the algorithms contained herein, you should NOT modify the compression or decompression machinery. Incorrect changes can lead to disastrous loss of data.

Disclaimer

NO RESPONSIBILITY IS TAKEN FOR ANY LOSS OF DATA ARISING FROM THE USE OF THIS PROGRAM/LIBRARY.

The complexity of the algorithms makes it impossible to rule out the possibility of bugs. Do not compress critical data without backups.

Patents

To the best of our knowledge, bzip2/libbz2 does not use any patented algorithms. However, no patent search has been conducted, so no guarantee can be given.

Copyright & Licensing

Copyright (C) 1996-2010 Julian Seward <jseward@acm.org>
Copyright (C) 2019-2020 Federico Mena Quintero <federico@gnome.org>
Copyright (C) 2021-2025 Micah Snyder
Copyright (C) 2025 YongDo-Hyun
Copyright (C) 2025 grxtor

Licensed under the bzip2 license (BSD-like). See bzip2/COPYING for full text.