zlib-ng

zlib data compression library for the next generation systems

Maintained by Hans Kristian Rosbach aka Dead2 (zlib-ng àt circlestorm dót org)

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Fork Motivation

The motivation for this fork was due to seeing several 3rd party contributions containing new optimizations not getting implemented into the official zlib repository.

Mark Adler has been maintaining zlib for a very long time, and he has done a great job and hopefully he will continue for a long time yet. The idea of zlib-ng is not to replace zlib, but to co-exist as a drop-in replacement with a lower threshold for code change.

zlib has a long history and is incredibly portable, even supporting lots of systems that predate the Internet. This is great, but it does complicate further development and maintainability. The zlib code has numerous workarounds for old compilers that do not understand ANSI-C or to accommodate systems with limitations such as operating in a 16-bit environment.

Many of these workarounds are only maintenance burdens, some of them are pretty huge code-wise. For example, the [v]s[n]printf workaround code has a whopping 8 different implementations just to cater to various old compilers. With this many workarounds cluttered throughout the code, new programmers with an idea/interest for zlib will need to take some time to figure out why all of these seemingly strange things are used, and how to work within those confines.

So I decided to make a fork, merge all the Intel optimizations, merge the Cloudflare optimizations that did not conflict, plus a couple of other smaller patches. Then I started cleaning out workarounds, various dead code, all contrib and example code as there is little point in having those in this fork for various reasons.

A lot of improvements have gone into zlib-ng since its start, and numerous people have contributed both small and big improvements, or valuable testing.

Please read LICENSE.md, it is very simple and very liberal.

Build

There are two ways to build zlib-ng:

Cmake

To build zlib-ng using the cross-platform makefile generator cmake.

cmake .
cmake --build . --config Release
ctest --verbose -C Release

Alternatively, yuou can use the cmake configuration GUI tool ccmake:

ccmake .

Configure

To build zlib-ng using the bash configure script:

./configure
make
make test

Build Options

CMake	configure	Description	Default
ZLIB_COMPAT	--zlib-compat	Compile with zlib compatible API	OFF
ZLIB_ENABLE_TESTS		Build test binaries	ON
WITH_GZFILEOP	--with-gzfileops	Compile with support for gzFile related functions	OFF
WITH_MSAN	--with-msan	Build with memory sanitizer	OFF
WITH_OPTIM	--without-optimizations	Build with optimisations	ON
WITH_NEW_STRATEGIES	--without-new-strategies	Use new strategies	ON
WITH_NATIVE_INSTRUCTIONS		Instruct the compiler to use the full instruction set on this host (gcc/clang -march=native)	OFF
	--force-sse2	Assume SSE2 instructions are always available	DISABLED (x86), ENABLED (x86_64)
WITH_ACLE	--without-acle	Build with ACLE CRC	ON
WITH_NEON	--without-neon	Build with NEON intrinsics	ON
WITH_DFLTCC_DEFLATE	--with-dfltcc-deflate	Use DEFLATE COMPRESSION CALL instruction for compression on IBM Z	OFF
WITH_DFLTCC_INFLATE	--with-dfltcc-inflate	Use DEFLATE COMPRESSION CALL instruction for decompression on IBM Z	OFF
WITH_SANITIZERS	--with-sanitizers	Build with address sanitizer and all supported sanitizers other than memory sanitizer	OFF
WITH_FUZZERS	--with-fuzzers	Build test/fuzz	OFF
WITH_MAINTAINER_WARNINGS		Build with project maintainer warnings	OFF
WITH_CODE_COVERAGE		Enable code coverage reporting	OFF

Install

WARNING: We do not recommend manually installing unless you really know what you are doing, because this can potentially override the system default zlib library, and any incompatability or wrong configuration of zlib-ng can make the whole system unusable, requiring recovery or reinstall. If you still want a manual install, we recommend using the /opt/ path prefix.

For Linux distros, an alternative way to use zlib-ng (if compiled in zlib-compat mode) instead of zlib, is through the use of the LD_PRELOAD environment variable. If the program is dynamically linked with zlib, then zlib-ng will temporarily be used instead by the program, without risking system-wide instability.

LD_PRELOAD=/opt/zlib-ng/libz.so.1.2.11.zlib-ng /usr/bin/program

Cmake

To install zlib-ng system-wide using cmake:

cmake --build . --target install

Configure

To install zlib-ng system-wide using the configure script:

make install

Contributing

Zlib-ng is a young project, and we aim to be open to contributions, and we would be delighted to receive pull requests on github. Just remember that any code you submit must be your own and it must be zlib licensed. Help with testing and reviewing of pull requests etc is also very much appreciated.

If you are interested in contributing, please consider joining our IRC channel #zlib-ng on the Freenode IRC network.

Acknowledgments

Thanks to Servebolt.com for sponsoring my maintainership of zlib-ng.

Thanks go out to all the people and companies who have taken the time to contribute code reviews, testing and/or patches. Zlib-ng would not have been nearly as good without you.

The deflate format used by zlib was defined by Phil Katz. The deflate and zlib specifications were written by L. Peter Deutsch.

zlib was originally created by Jean-loup Gailly (compression) and Mark Adler (decompression).

Contents

Name	Description
arch/	Architecture-specific code
doc/	Documentation for formats and algorithms
test/example.c	Zlib usages examples for build testing
test/minigzip.c	Minimal gzip-like functionality for build testing
test/infcover.c	Inflate code coverage for build testing
win32/	Shared library version resources for Windows
CMakeLists.txt	Cmake build script
configure	Bash configure/build script
adler32.c	Compute the Adler-32 checksum of a data stream
compress.c	Compress a memory buffer
deflate.*	Compress data using the deflate algorithm
deflate_fast.c	Compress data using the deflate algorithm with fast strategy
deflate_medium.c	Compress data using the deflate algorithm with medium stragety
deflate_slow.c	Compress data using the deflate algorithm with slow strategy
functable.*	Struct containing function pointers to optimized functions
gzclose.c	Close gzip files
gzguts.h	Internal definitions for gzip operations
gzlib.c	Functions common to reading and writing gzip files
gzread.c	Read gzip files
gzwrite.c	Write gzip files
infback.*	Inflate using a callback interface
inflate.*	Decompress data
inffast.*	Decompress data with speed optimizations
inffixed.h	Table for decoding fixed codes
inftrees.h	Generate Huffman trees for efficient decoding
memcopy.h	Inline functions to copy small data chunks
trees.*	Output deflated data using Huffman coding
uncompr.c	Decompress a memory buffer
zconf.h.cmakein	zconf.h template for cmake
zendian.h	BYTE_ORDER for endian tests
zlib.3	Man page for zlib
zlib.map	Linux symbol information
zlib.pc.in	Pkg-config template