This crate is a C API for zlib-rs. The API is broadly equivalent to zlib-sys and zlib-ng-sys, but does not currently provide the gz* family of functions.

From a rust perspective, this API is not very ergonomic. Use the flate2 crate for a more ergonomic rust interface to zlib.

Features

custom-prefix

Add a custom prefix to all exported symbols.

The value of the LIBZ_RS_SYS_PREFIX is used as a prefix for all exported symbols. For example:

> LIBZ_RS_SYS_PREFIX="MY_CUSTOM_PREFIX" cargo build -p libz-rs-sys --features=custom-prefix
   Compiling libz-rs-sys v0.2.1 (/home/folkertdev/rust/zlib-rs/libz-rs-sys)
    Finished `dev` profile [optimized + debuginfo] target(s) in 0.21s
> objdump -tT target/debug/liblibz_rs_sys.so | grep "uncompress"
0000000000081028 l     O .got	0000000000000000              _ZN7zlib_rs7inflate10uncompress17he7d985e55c58a189E$got
000000000002c570 l     F .text	00000000000001ef              _ZN7zlib_rs7inflate10uncompress17he7d985e55c58a189E
0000000000024330 g     F .text	000000000000008e              MY_CUSTOM_PREFIXuncompress
0000000000024330 g    DF .text	000000000000008e  Base        MY_CUSTOM_PREFIXuncompress

c-allocator, rust-allocator

Pick the default allocator implementation that is used if no zalloc and zfree are configured in the input z_stream.

• c-allocator: use malloc/free for the implementation of zalloc and zfree
• rust-allocator: the rust global allocator for the implementation of zalloc and zfree

The rust-allocator is the default when this crate is used as a rust dependency, and slightly more efficient because alignment is handled by the allocator. When building a dynamic library, it may make sense to use c-allocator instead.

std

Assume that std is available. When this feature is turned off, this crate is compatible with #![no_std].

Example

This example compresses ("deflates") the string "Hello, World!" and then decompresses ("inflates") it again.

let mut strm = libz_rs_sys::z_stream::default();

let version = libz_rs_sys::zlibVersion();
let stream_size = core::mem::size_of_val(&strm) as i32;

let level = 6; // the default compression level
let err = unsafe { libz_rs_sys::deflateInit_(&mut strm, level, version, stream_size) };
assert_eq!(err, libz_rs_sys::Z_OK);

let input = "Hello, World!";
strm.avail_in = input.len() as _;
strm.next_in = input.as_ptr();

let mut output = [0u8; 32];
strm.avail_out = output.len() as _;
strm.next_out = output.as_mut_ptr();

let err = unsafe { libz_rs_sys::deflate(&mut strm, libz_rs_sys::Z_FINISH) };
assert_eq!(err, libz_rs_sys::Z_STREAM_END);

let err = unsafe { libz_rs_sys::deflateEnd(&mut strm) };
assert_eq!(err, libz_rs_sys::Z_OK);

let deflated = &mut output[..strm.total_out as usize];

let mut strm = libz_rs_sys::z_stream::default();
let err = unsafe { libz_rs_sys::inflateInit_(&mut strm, version, stream_size) };
assert_eq!(err, libz_rs_sys::Z_OK);

strm.avail_in = deflated.len() as _;
strm.next_in = deflated.as_ptr();

let mut output = [0u8; 32];
strm.avail_out = output.len() as _;
strm.next_out = output.as_mut_ptr();

let err = unsafe { libz_rs_sys::inflate(&mut strm, libz_rs_sys::Z_FINISH) };
assert_eq!(err, libz_rs_sys::Z_STREAM_END);

let err = unsafe { libz_rs_sys::inflateEnd(&mut strm) };
assert_eq!(err, libz_rs_sys::Z_OK);

let inflated = &output[..strm.total_out as usize];

assert_eq!(inflated, input.as_bytes())