src/libflate/lib.rs

   1 // Copyright 2012 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 //! Simple [DEFLATE][def]-based compression. This is a wrapper around the
  12 //! [`miniz`][mz] library, which is a one-file pure-C implementation of zlib.
  13 //!
  14 //! [def]: https://en.wikipedia.org/wiki/DEFLATE
  15 //! [mz]: https://code.google.com/p/miniz/
  16
  17 #![crate_name = "flate"]
  18 #![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
  19 #![crate_type = "rlib"]
  20 #![crate_type = "dylib"]
  21 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
  22        html_favicon_url = "https://doc.rust-lang.org/favicon.ico",
  23        html_root_url = "https://doc.rust-lang.org/nightly/",
  24        test(attr(deny(warnings))))]
  25 #![deny(warnings)]
  26
  27 #![feature(libc)]
  28 #![cfg_attr(stage0, feature(staged_api))]
  29 #![feature(unique)]
  30 #![cfg_attr(test, feature(rand))]
  31
  32 extern crate libc;
  33
  34 use libc::{c_int, c_void, size_t};
  35 use std::fmt;
  36 use std::ops::Deref;
  37 use std::ptr::Unique;
  38 use std::slice;
  39
  40 #[derive(Clone, Eq, Hash, Ord, PartialEq, PartialOrd)]
  41 pub struct Error {
  42     _unused: (),
  43 }
  44
  45 impl Error {
  46     fn new() -> Error {
  47         Error { _unused: () }
  48     }
  49 }
  50
  51 impl fmt::Debug for Error {
  52     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
  53         "decompression error".fmt(f)
  54     }
  55 }
  56
  57 pub struct Bytes {
  58     ptr: Unique<u8>,
  59     len: usize,
  60 }
  61
  62 impl Deref for Bytes {
  63     type Target = [u8];
  64     fn deref(&self) -> &[u8] {
  65         unsafe { slice::from_raw_parts(self.ptr.as_ptr(), self.len) }
  66     }
  67 }
  68
  69 impl Drop for Bytes {
  70     fn drop(&mut self) {
  71         unsafe {
  72             libc::free(self.ptr.as_ptr() as *mut _);
  73         }
  74     }
  75 }
  76
  77 extern "C" {
  78     /// Raw miniz compression function.
  79     fn tdefl_compress_mem_to_heap(psrc_buf: *const c_void,
  80                                   src_buf_len: size_t,
  81                                   pout_len: *mut size_t,
  82                                   flags: c_int)
  83                                   -> *mut c_void;
  84
  85     /// Raw miniz decompression function.
  86     fn tinfl_decompress_mem_to_heap(psrc_buf: *const c_void,
  87                                     src_buf_len: size_t,
  88                                     pout_len: *mut size_t,
  89                                     flags: c_int)
  90                                     -> *mut c_void;
  91 }
  92
  93 const LZ_FAST: c_int = 0x01;  // LZ with 1 probe, "fast"
  94 const TDEFL_GREEDY_PARSING_FLAG: c_int = 0x04000; // fast greedy parsing instead of lazy parsing
  95
  96 /// Compress a buffer without writing any sort of header on the output. Fast
  97 /// compression is used because it is almost twice as fast as default
  98 /// compression and the compression ratio is only marginally worse.
  99 pub fn deflate_bytes(bytes: &[u8]) -> Bytes {
 100     let flags = LZ_FAST | TDEFL_GREEDY_PARSING_FLAG;
 101     unsafe {
 102         let mut outsz: size_t = 0;
 103         let res = tdefl_compress_mem_to_heap(bytes.as_ptr() as *const _,
 104                                              bytes.len() as size_t,
 105                                              &mut outsz,
 106                                              flags);
 107         assert!(!res.is_null());
 108         Bytes {
 109             ptr: Unique::new(res as *mut u8),
 110             len: outsz as usize,
 111         }
 112     }
 113 }
 114
 115 /// Decompress a buffer without parsing any sort of header on the input.
 116 pub fn inflate_bytes(bytes: &[u8]) -> Result<Bytes, Error> {
 117     let flags = 0;
 118     unsafe {
 119         let mut outsz: size_t = 0;
 120         let res = tinfl_decompress_mem_to_heap(bytes.as_ptr() as *const _,
 121                                                bytes.len() as size_t,
 122                                                &mut outsz,
 123                                                flags);
 124         if !res.is_null() {
 125             Ok(Bytes {
 126                 ptr: Unique::new(res as *mut u8),
 127                 len: outsz as usize,
 128             })
 129         } else {
 130             Err(Error::new())
 131         }
 132     }
 133 }
 134
 135 #[cfg(test)]
 136 mod tests {
 137     #![allow(deprecated)]
 138     use super::{deflate_bytes, inflate_bytes};
 139     use std::__rand::{Rng, thread_rng};
 140
 141     #[test]
 142     fn test_flate_round_trip() {
 143         let mut r = thread_rng();
 144         let mut words = vec![];
 145         for _ in 0..20 {
 146             let range = r.gen_range(1, 10);
 147             let v = r.gen_iter::<u8>().take(range).collect::<Vec<u8>>();
 148             words.push(v);
 149         }
 150         for _ in 0..20 {
 151             let mut input = vec![];
 152             for _ in 0..2000 {
 153                 input.extend_from_slice(r.choose(&words).unwrap());
 154             }
 155             let cmp = deflate_bytes(&input);
 156             let out = inflate_bytes(&cmp).unwrap();
 157             assert_eq!(&*input, &*out);
 158         }
 159     }
 160
 161     #[test]
 162     fn test_zlib_flate() {
 163         let bytes = vec![1, 2, 3, 4, 5];
 164         let deflated = deflate_bytes(&bytes);
 165         let inflated = inflate_bytes(&deflated).unwrap();
 166         assert_eq!(&*inflated, &*bytes);
 167     }
 168 }