#zlib #zlib-ng

sys libz-sys

Low-level bindings to the system libz library (also known as zlib)

38 releases (stable)

Uses old Rust 2015

1.1.2 Sep 4, 2020
1.0.25 Oct 24, 2018
1.0.18 Oct 14, 2017
1.0.16 Jun 20, 2017
0.1.0 Nov 27, 2014

#5 in #zlib

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Used in 922 crates (34 directly)


53K SLoC

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A common library for linking libz to rust programs (also known as zlib).


High-level API

This crate provides bindings to the raw low-level C API. For a higher-level safe API to work with DEFLATE, zlib, or gzip streams, see flate2. flate2 also supports alternative implementations, including slower but pure Rust implementations.


This crate supports building either the high-performance zlib-ng (in zlib-compat mode), or the widely available stock zlib.

By default, libz-sys uses stock zlib, primarily because doing so allows the use of a shared system zlib library if available.

Any application or library designed for zlib should work with zlib-ng in zlib-compat mode, as long as it doesn't make assumptions about the exact size or output of the deflated data (e.g. "compressing this data produces exactly this many bytes"), and as long as you don't also dynamically pull in a copy of stock zlib (which will produce conflicting symbols). Nonetheless, for maximum compatibility, every library crate in a build must opt into allowing zlib-ng; if any library crate in your dependency graph wants stock zlib, libz-sys will use stock zlib.

Library crates depending on libz-sys should use:

libz-sys = { version = "1.1.0", default-features = false, features = ["libc"] }

(Omit the libc feature if you don't require the corresponding functions.)

This allows higher-level crates depending on your library to opt into zlib-ng if desired.

Building zlib-ng requires cmake.


This project is licensed under either of

at your option.


Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in libz-sys by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.