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# flate2
[](https://crates.io/crates/flate2)
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](#Backends), such as the widely
available zlib library or the high-performance zlib-ng library.
Supported formats:
* deflate
* zlib
* gzip
```toml
# Cargo.toml
[dependencies]
flate2 = "1.0"
```
## MSRV (Minimum Supported Rust Version) Policy
This crate supports the current stable and the last stable for the latest version.
For example, if the current stable is 1.64, this crate supports 1.64 and 1.63.
Older stables may work, but we don't guarantee these will continue to work.
## Compression
```rust
use std::io::prelude::*;
use flate2::Compression;
use flate2::write::ZlibEncoder;
fn main() {
let mut e = ZlibEncoder::new(Vec::new(), Compression::default());
e.write_all(b"foo");
e.write_all(b"bar");
let compressed_bytes = e.finish();
}
```
## Decompression
```rust,no_run
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);
}
```
## Backends
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:
```toml
[dependencies]
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:
```toml
[dependencies]
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:
```toml
[dependencies]
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
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
`cloudflare_zlib` will cause breakage if any other crate in your crate graph
uses another version of zlib/libz.
# License
This project is licensed under either of
* Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or
* MIT license ([LICENSE-MIT](LICENSE-MIT) or
at your option.
### Contribution
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.