Crate libz_rs_sys

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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.

§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())

§Safety of *mut z_stream

Most functions require an argument of type *mut z_stream. Unless otherwise noted, the safety requirements on such arguments are at least that the pointer must be either:

  • A NULL pointer
  • A pointer to a correctly aligned, initialized value of type z_stream.

In other words, it must be safe to cast the *mut z_stream to a Option<&mut z_stream>. It is always safe to provide an argument of type &mut z_stream: rust will automatically downcast the argument to *mut z_stream.

Structs§

  • gz_header
    gzip header information passed to and from zlib routines. See RFC 1952 for more details on the meanings of these fields.
  • z_stream

Enums§

Constants§

Functions§

Type Aliases§