1# flate2
2
3[![Crates.io](https://img.shields.io/crates/v/flate2.svg?maxAge=2592000)](https://crates.io/crates/flate2)
4[![Documentation](https://docs.rs/flate2/badge.svg)](https://docs.rs/flate2)
5
6A streaming compression/decompression library DEFLATE-based streams in Rust.
7
8This crate by default uses the `miniz_oxide` crate, a port of `miniz.c` to pure
9Rust. This crate also supports other [backends](#Backends), such as the widely
10available zlib library or the high-performance zlib-ng library.
11
12Supported formats:
13
14* deflate
15* zlib
16* gzip
17
18```toml
19# Cargo.toml
20[dependencies]
21flate2 = "1.0"
22```
23
24## Compression
25
26```rust
27use std::io::prelude::*;
28use flate2::Compression;
29use flate2::write::ZlibEncoder;
30
31fn main() {
32    let mut e = ZlibEncoder::new(Vec::new(), Compression::default());
33    e.write_all(b"foo");
34    e.write_all(b"bar");
35    let compressed_bytes = e.finish();
36}
37```
38
39## Decompression
40
41```rust,no_run
42use std::io::prelude::*;
43use flate2::read::GzDecoder;
44
45fn main() {
46    let mut d = GzDecoder::new("...".as_bytes());
47    let mut s = String::new();
48    d.read_to_string(&mut s).unwrap();
49    println!("{}", s);
50}
51```
52
53## Backends
54
55The default `miniz_oxide` backend has the advantage of being pure Rust, but if
56you're already using zlib with another C library, for example, you can use that
57for Rust code as well:
58
59```toml
60[dependencies]
61flate2 = { version = "1.0.17", features = ["zlib"], default-features = false }
62```
63
64This supports either the high-performance zlib-ng backend (in zlib-compat mode)
65or the use of a shared system zlib library. To explicitly opt into the fast
66zlib-ng backend, use:
67
68```toml
69[dependencies]
70flate2 = { version = "1.0.17", features = ["zlib-ng-compat"], default-features = false }
71```
72
73Note that if any crate in your dependency graph explicitly requests stock zlib,
74or uses libz-sys directly without `default-features = false`, you'll get stock
75zlib rather than zlib-ng. See [the libz-sys
76README](https://github.com/rust-lang/libz-sys/blob/main/README.md) for details.
77
78For compatibility with previous versions of `flate2`, the cloudflare optimized
79version of zlib is available, via the `cloudflare_zlib` feature. It's not as
80fast as zlib-ng, but it's faster than stock zlib. It requires a x86-64 CPU with
81SSE 4.2 or ARM64 with NEON & CRC. It does not support 32-bit CPUs at all and is
82incompatible with mingw. For more information check the [crate
83documentation](https://crates.io/crates/cloudflare-zlib-sys). Note that
84`cloudflare_zlib` will cause breakage if any other crate in your crate graph
85uses another version of zlib/libz.
86
87For compatibility with previous versions of `flate2`, the C version of `miniz.c`
88is still available, using the feature `miniz-sys`.
89
90# License
91
92This project is licensed under either of
93
94 * Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or
95   http://www.apache.org/licenses/LICENSE-2.0)
96 * MIT license ([LICENSE-MIT](LICENSE-MIT) or
97   http://opensource.org/licenses/MIT)
98
99at your option.
100
101### Contribution
102
103Unless you explicitly state otherwise, any contribution intentionally submitted
104for inclusion in this project by you, as defined in the Apache-2.0 license,
105shall be dual licensed as above, without any additional terms or conditions.
106