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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The motivation for this fork came after 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 and companies have contributed both small and big improvements, or valuable testing.
Please read LICENSE.md, it is very simple and very liberal.
There are two ways to build zlib-ng:
To build zlib-ng using the cross-platform makefile generator cmake.
cmake . cmake --build . --config Release ctest --verbose -C Release
Alternatively, you can use the cmake configuration GUI tool ccmake:
ccmake .
To build zlib-ng using the bash configure script:
./configure make make test
| CMake | configure | Description | Default |
|---|---|---|---|
| ZLIB_COMPAT | --zlib-compat | Compile with zlib compatible API | OFF |
| ZLIB_ENABLE_TESTS | Build test binaries | ON | |
| WITH_GZFILEOP | --without-gzfileops | Compile with support for gzFile related functions | ON |
| WITH_OPTIM | --without-optimizations | Build with optimisations | ON |
| WITH_NEW_STRATEGIES | --without-new-strategies | Use new strategies | ON |
| WITH_NATIVE_INSTRUCTIONS | --native | Compiles with full instruction set supported on this host (gcc/clang -march=native) | OFF |
| WITH_SANITIZER | --with-sanitizer | Build with sanitizer (memory, address, undefined) | 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 |
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 incompatibility 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
To install zlib-ng system-wide using cmake:
cmake --build . --target install
To install zlib-ng system-wide using the configure script:
make install
Zlib-ng is a aiming 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.
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).
| CMake | configure | Description | Default |
|---|---|---|---|
| ZLIB_DUAL_LINK | Dual link tests with system zlib | OFF | |
| UNALIGNED_OK | Allow unaligned reads | ON (x86, arm) | |
| --force-sse2 | Skip runtime check for SSE2 instructions (Always on for x86_64) | OFF (x86) | |
| WITH_AVX2 | Build with AVX2 intrinsics | ON | |
| WITH_SSE2 | Build with SSE2 intrinsics | ON | |
| WITH_SSE4 | Build with SSE4 intrinsics | ON | |
| WITH_PCLMULQDQ | Build with PCLMULQDQ intrinsics | ON | |
| WITH_ACLE | --without-acle | Build with ACLE intrinsics | ON |
| WITH_NEON | --without-neon | Build with NEON intrinsics | ON |
| WITH_POWER8 | Build with POWER8 optimisations | ON | |
| WITH_DFLTCC_DEFLATE | --with-dfltcc-deflate | Build with DFLTCC intrinsics for compression on IBM Z | OFF |
| WITH_DFLTCC_INFLATE | --with-dfltcc-inflate | Build with DFLTCC intrinsics for decompression on IBM Z | OFF |
| WITH_UNALIGNED | Allow optimizations that use unaligned reads if safe on current arch | ON | |
| WITH_INFLATE_STRICT | Build with strict inflate distance checking | OFF | |
| WITH_INFLATE_ALLOW_INVALID_DIST | Build with zero fill for inflate invalid distances | OFF | |
| INSTALL_UTILS | Copy minigzip and minideflate during install | OFF |