preflate-rs 0.6.3

Decompresses existing DEFLATE streams to allow for better compression (eg with ZStandard) while allowing the exact original binary DEFLATE stream to be recreated by detecting the parameters used during compression.
Documentation 
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

/*---------------------------------------------------------------------------------------------
 *  Copyright (c) Microsoft Corporation. All rights reserved.
 *  Licensed under the Apache License, Version 2.0. See LICENSE.txt in the project root for license information.
 *  This software incorporates material from third parties. See NOTICE.txt for details.
 *--------------------------------------------------------------------------------------------*/

mod bit_helper;
mod cabac_codec;
mod deflate;
mod estimator;
mod hash_algorithm;
mod hash_chain;
mod hash_chain_holder;
mod idat_parse;
mod preflate_container;
mod preflate_error;
mod preflate_input;
mod process;
mod scan_deflate;
mod statistical_codec;
mod token_predictor;
mod tree_predictor;

pub mod unmanaged_api;

use hash_algorithm::HashAlgorithm;
pub use preflate_container::{
    compress_zstd, decompress_deflate_stream, decompress_zstd, expand_zlib_chunks,
    recompress_deflate_stream, recreated_zlib_chunks,
};
pub use preflate_error::ExitCode;
pub use preflate_error::{PreflateError, Result};

use std::io::Write;

pub struct PreflateCompressionContext {
    content: Vec<u8>,
    result: Option<Vec<u8>>,
    result_pos: usize,
    compression_stats: CompressionStats,
    test_baseline: bool,
}

#[derive(Debug, Copy, Clone, Default)]
pub struct CompressionStats {
    deflate_compressed_size: u64,
    zstd_compressed_size: u64,
    uncompressed_size: u64,
    overhead_bytes: u64,
    hash_algorithm: HashAlgorithm,
    zstd_baseline_size: u64,
}

impl PreflateCompressionContext {
    pub fn new(test_baseline: bool) -> Self {
        PreflateCompressionContext {
            content: Vec::new(),
            compression_stats: CompressionStats::default(),
            result: None,
            result_pos: 0,
            test_baseline,
        }
    }

    fn process_buffer(
        &mut self,
        input: &[u8],
        input_complete: bool,
        writer: &mut impl Write,
        max_output_write: usize,
    ) -> Result<bool> {
        if self.result.is_some() {
            if input.len() > 0 {
                return Err(PreflateError::new(
                    ExitCode::InvalidParameter,
                    "more data provided after input_complete signaled",
                ));
            }
        }

        self.content.extend_from_slice(input);

        if input_complete {
            if self.test_baseline {
                self.compression_stats.zstd_baseline_size +=
                    zstd::bulk::compress(&self.content, 9)?.len() as u64;
            }

            self.result = Some(compress_zstd(
                &self.content,
                9,
                &mut self.compression_stats,
            )?);
        }

        if let Some(result) = &mut self.result {
            let amount_to_write = std::cmp::min(max_output_write, result.len() - self.result_pos);

            writer.write(&result[self.result_pos..self.result_pos + amount_to_write])?;
            self.result_pos += amount_to_write;
            Ok(self.result_pos == result.len())
        } else {
            Ok(false)
        }
    }

    pub fn stats(&self) -> CompressionStats {
        self.compression_stats
    }
}

struct PreflateDecompressionContext {
    capacity: usize,
    content: Vec<u8>,
    result: Option<Vec<u8>>,
    result_pos: usize,
}

impl PreflateDecompressionContext {
    fn new(capacity: usize) -> Self {
        PreflateDecompressionContext {
            content: Vec::new(),
            result: None,
            result_pos: 0,
            capacity,
        }
    }

    fn process_buffer(
        &mut self,
        input: &[u8],
        input_complete: bool,
        writer: &mut impl Write,
        max_output_write: usize,
    ) -> Result<bool> {
        if self.result.is_some() {
            if input.len() > 0 {
                return Err(PreflateError::new(
                    ExitCode::InvalidParameter,
                    "more data provided after input_complete signaled",
                ));
            }
        }

        self.content.extend_from_slice(input);

        if input_complete {
            self.result = Some(decompress_zstd(&self.content, self.capacity)?);
        }

        if let Some(result) = &mut self.result {
            let amount_to_write = std::cmp::min(max_output_write, result.len() - self.result_pos);

            writer.write(&result[self.result_pos..self.result_pos + amount_to_write])?;
            self.result_pos += amount_to_write;
            Ok(self.result_pos == result.len())
        } else {
            Ok(false)
        }
    }
}