Bug: 188410695

Clone this repo:
  1. 6d80347 Make flate2 available to product and vendor am: 87bbf59bd0 by Matthew Maurer · 3 months ago main master android-u-beta-1-gpl
  2. 87bbf59 Make flate2 available to product and vendor by Matthew Maurer · 3 months ago
  3. d514a41 Update TEST_MAPPING am: 2ddde70beb by Jeff Vander Stoep · 4 months ago
  4. 2ddde70 Update TEST_MAPPING by Jeff Vander Stoep · 4 months ago
  5. 27095ab Update TEST_MAPPING am: 174944d149 by David Brazdil · 5 months ago


Crates.io Documentation

A streaming compression/decompression library DEFLATE-based streams in Rust.

This crate by default uses the miniz_oxide crate, a port of miniz.c to pure Rust. This crate also supports other backends, such as the widely available zlib library or the high-performance zlib-ng library.

Supported formats:

  • deflate
  • zlib
  • gzip
# Cargo.toml
flate2 = "1.0"


use std::io::prelude::*;
use flate2::Compression;
use flate2::write::ZlibEncoder;

fn main() {
    let mut e = ZlibEncoder::new(Vec::new(), Compression::default());
    let compressed_bytes = e.finish();


use std::io::prelude::*;
use flate2::read::GzDecoder;

fn main() {
    let mut d = GzDecoder::new("...".as_bytes());
    let mut s = String::new();
    d.read_to_string(&mut s).unwrap();
    println!("{}", s);


The default miniz_oxide backend has the advantage of being pure Rust. If you want maximum performance, you can use the zlib-ng C library:

flate2 = { version = "1.0.17", features = ["zlib-ng"], default-features = false }

Note that the "zlib-ng" feature works even if some other part of your crate graph depends on zlib.

However, if you're already using another C or Rust library that depends on zlib, and you want to avoid including both zlib and zlib-ng, you can use that for Rust code as well:

flate2 = { version = "1.0.17", features = ["zlib"], default-features = false }

Or, if you have C or Rust code that depends on zlib and you want to use zlib-ng via libz-sys in zlib-compat mode, use:

flate2 = { version = "1.0.17", features = ["zlib-ng-compat"], default-features = false }

Note that when using the "zlib-ng-compat" feature, if any crate in your dependency graph explicitly requests stock zlib, or uses libz-sys directly without default-features = false, you'll get stock zlib rather than zlib-ng. See the libz-sys README for details. To avoid that, use the "zlib-ng" feature instead.

For compatibility with previous versions of flate2, the Cloudflare optimized version of zlib is available, via the cloudflare_zlib feature. It‘s not as fast as zlib-ng, but it’s faster than stock zlib. It requires an x86-64 CPU with SSE 4.2 or ARM64 with NEON & CRC. It does not support 32-bit CPUs at all and is incompatible with mingw. For more information check the crate documentation. Note that cloudflare_zlib will cause breakage if any other crate in your crate graph uses another version of zlib/libz.


This project is licensed under either of

at your option.


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