1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
//! A DEFLATE-based stream compression/decompression library
//!
//! This library provides support for compression and decompression of
//! DEFLATE-based streams:
//!
//! * the DEFLATE format itself
//! * the zlib format
//! * gzip
//!
//! These three formats are all closely related and largely only differ in their
//! headers/footers. This crate has three types in each submodule for dealing
//! with these three formats.
//!
//! # Implementation
//!
//! In addition to supporting three formats, this crate supports several different
//! backends, controlled through this crate's features:
//!
//! * `default`, or `rust_backend` - this implementation uses the `miniz_oxide`
//!   crate which is a port of `miniz.c` (below) to Rust. This feature does not
//!   require a C compiler and only requires Rust code.
//!
//! * `zlib` - this feature will enable linking against the `libz` library, typically found on most
//!   Linux systems by default. If the library isn't found to already be on the system it will be
//!   compiled from source (this is a C library).
//!
//! There's various tradeoffs associated with each implementation, but in general you probably
//! won't have to tweak the defaults. The default choice is selected to avoid the need for a C
//! compiler at build time. `zlib-ng-compat` is useful if you're using zlib for compatibility but
//! want performance via zlib-ng's zlib-compat mode. `zlib` is useful if something else in your
//! dependencies links the original zlib so you cannot use zlib-ng-compat. The compression ratios
//! and performance of each of these feature should be roughly comparable, but you'll likely want
//! to run your own tests if you're curious about the performance.
//!
//! # Organization
//!
//! This crate consists mainly of three modules, [`read`], [`write`], and
//! [`bufread`]. Each module contains a number of types used to encode and
//! decode various streams of data.
//!
//! All types in the [`write`] module work on instances of [`Write`][write],
//! whereas all types in the [`read`] module work on instances of
//! [`Read`][read] and [`bufread`] works with [`BufRead`][bufread]. If you
//! are decoding directly from a `&[u8]`, use the [`bufread`] types.
//!
//! ```
//! use flate2::write::GzEncoder;
//! use flate2::Compression;
//! use std::io;
//! use std::io::prelude::*;
//!
//! # fn main() { let _ = run(); }
//! # fn run() -> io::Result<()> {
//! let mut encoder = GzEncoder::new(Vec::new(), Compression::default());
//! encoder.write_all(b"Example")?;
//! # Ok(())
//! # }
//! ```
//!
//!
//! Other various types are provided at the top-level of the crate for
//! management and dealing with encoders/decoders. Also note that types which
//! operate over a specific trait often implement the mirroring trait as well.
//! For example a `flate2::read::DeflateDecoder<T>` *also* implements the
//! `Write` trait if `T: Write`. That is, the "dual trait" is forwarded directly
//! to the underlying object if available.
//!
//! [`read`]: read/index.html
//! [`bufread`]: bufread/index.html
//! [`write`]: write/index.html
//! [read]: https://doc.rust-lang.org/std/io/trait.Read.html
//! [write]: https://doc.rust-lang.org/std/io/trait.Write.html
//! [bufread]: https://doc.rust-lang.org/std/io/trait.BufRead.html
#![doc(html_root_url = "https://docs.rs/flate2/0.2")]
#![deny(missing_docs)]
#![deny(missing_debug_implementations)]
#![allow(trivial_numeric_casts)]
#![cfg_attr(test, deny(warnings))]
#![cfg_attr(docsrs, feature(doc_auto_cfg))]

pub use crate::crc::{Crc, CrcReader, CrcWriter};
pub use crate::gz::GzBuilder;
pub use crate::gz::GzHeader;
pub use crate::mem::{Compress, CompressError, Decompress, DecompressError, Status};
pub use crate::mem::{FlushCompress, FlushDecompress};

mod bufreader;
mod crc;
mod deflate;
mod ffi;
mod gz;
mod mem;
mod zio;
mod zlib;

/// Types which operate over [`Read`] streams, both encoders and decoders for
/// various formats.
///
/// [`Read`]: https://doc.rust-lang.org/std/io/trait.Read.html
pub mod read {
    pub use crate::deflate::read::DeflateDecoder;
    pub use crate::deflate::read::DeflateEncoder;
    pub use crate::gz::read::GzDecoder;
    pub use crate::gz::read::GzEncoder;
    pub use crate::gz::read::MultiGzDecoder;
    pub use crate::zlib::read::ZlibDecoder;
    pub use crate::zlib::read::ZlibEncoder;
}

/// Types which operate over [`Write`] streams, both encoders and decoders for
/// various formats.
///
/// [`Write`]: https://doc.rust-lang.org/std/io/trait.Write.html
pub mod write {
    pub use crate::deflate::write::DeflateDecoder;
    pub use crate::deflate::write::DeflateEncoder;
    pub use crate::gz::write::GzDecoder;
    pub use crate::gz::write::GzEncoder;
    pub use crate::gz::write::MultiGzDecoder;
    pub use crate::zlib::write::ZlibDecoder;
    pub use crate::zlib::write::ZlibEncoder;
}

/// Types which operate over [`BufRead`] streams, both encoders and decoders for
/// various formats.
///
/// [`BufRead`]: https://doc.rust-lang.org/std/io/trait.BufRead.html
pub mod bufread {
    pub use crate::deflate::bufread::DeflateDecoder;
    pub use crate::deflate::bufread::DeflateEncoder;
    pub use crate::gz::bufread::GzDecoder;
    pub use crate::gz::bufread::GzEncoder;
    pub use crate::gz::bufread::MultiGzDecoder;
    pub use crate::zlib::bufread::ZlibDecoder;
    pub use crate::zlib::bufread::ZlibEncoder;
}

fn _assert_send_sync() {
    fn _assert_send_sync<T: Send + Sync>() {}

    _assert_send_sync::<read::DeflateEncoder<&[u8]>>();
    _assert_send_sync::<read::DeflateDecoder<&[u8]>>();
    _assert_send_sync::<read::ZlibEncoder<&[u8]>>();
    _assert_send_sync::<read::ZlibDecoder<&[u8]>>();
    _assert_send_sync::<read::GzEncoder<&[u8]>>();
    _assert_send_sync::<read::GzDecoder<&[u8]>>();
    _assert_send_sync::<read::MultiGzDecoder<&[u8]>>();
    _assert_send_sync::<write::DeflateEncoder<Vec<u8>>>();
    _assert_send_sync::<write::DeflateDecoder<Vec<u8>>>();
    _assert_send_sync::<write::ZlibEncoder<Vec<u8>>>();
    _assert_send_sync::<write::ZlibDecoder<Vec<u8>>>();
    _assert_send_sync::<write::GzEncoder<Vec<u8>>>();
    _assert_send_sync::<write::GzDecoder<Vec<u8>>>();
}

/// When compressing data, the compression level can be specified by a value in
/// this enum.
#[derive(Copy, Clone, PartialEq, Eq, Debug)]
pub struct Compression(u32);

impl Compression {
    /// Creates a new description of the compression level with an explicitly
    /// specified integer.
    ///
    /// The integer here is typically on a scale of 0-9 where 0 means "no
    /// compression" and 9 means "take as long as you'd like".
    pub const fn new(level: u32) -> Compression {
        Compression(level)
    }

    /// No compression is to be performed, this may actually inflate data
    /// slightly when encoding.
    pub const fn none() -> Compression {
        Compression(0)
    }

    /// Optimize for the best speed of encoding.
    pub const fn fast() -> Compression {
        Compression(1)
    }

    /// Optimize for the size of data being encoded.
    pub const fn best() -> Compression {
        Compression(9)
    }

    /// Returns an integer representing the compression level, typically on a
    /// scale of 0-9
    pub fn level(&self) -> u32 {
        self.0
    }
}

impl Default for Compression {
    fn default() -> Compression {
        Compression(6)
    }
}

#[cfg(test)]
fn random_bytes() -> impl Iterator<Item = u8> {
    use rand::Rng;
    use std::iter;

    iter::repeat(()).map(|_| rand::thread_rng().gen())
}