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include/boost/http/zlib/deflate.hpp

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include/boost/http/zlib/deflate.hpp
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1 //
2 // Copyright (c) 2021 Vinnie Falco ([email protected])
3 // Copyright (c) 2025 Mohammad Nejati
4 //
5 // Distributed under the Boost Software License, Version 1.0. (See accompanying
6 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
7 //
8 // Official repository: https://github.com/cppalliance/http
9 //
10
11 #ifndef BOOST_HTTP_ZLIB_DEFLATE_HPP
12 #define BOOST_HTTP_ZLIB_DEFLATE_HPP
13
14 #include <boost/http/detail/config.hpp>
15 #include <boost/http/zlib/service.hpp>
16 #include <boost/http/zlib/stream.hpp>
17
18 #include <boost/capy/ex/execution_context.hpp>
19
20 #include <cstddef>
21
22 namespace boost {
23 namespace http {
24 namespace zlib {
25
26 /** Provides the ZLib compression API.
27
28 This service interface exposes the ZLib deflate (compression)
29 functionality through a set of virtual functions. The deflate
30 algorithm compresses data by finding repeated byte sequences
31 and encoding them efficiently using a combination of LZ77 and
32 Huffman coding.
33
34 The windowBits parameter in init2() controls the format:
35 - 8..15: zlib format with specified window size
36 - -8..-15: raw deflate format (no header/trailer)
37 - 16+windowBits: gzip format
38
39 @code
40 // Example: Basic compression
41 boost::http::datastore ctx;
42 auto& deflate_svc = boost::http::zlib::install_deflate_service(ctx);
43
44 boost::http::zlib::stream st = {};
45 std::vector<unsigned char> input_data = get_data();
46 std::vector<unsigned char> output(input_data.size() * 2);
47
48 st.zalloc = nullptr;
49 st.zfree = nullptr;
50 st.opaque = nullptr;
51
52 deflate_svc.init(st, boost::http::zlib::default_compression);
53
54 st.avail_in = input_data.size();
55 st.next_in = input_data.data();
56 st.avail_out = output.size();
57 st.next_out = output.data();
58
59 deflate_svc.deflate(st, boost::http::zlib::finish);
60 output.resize(st.total_out);
61
62 deflate_svc.deflate_end(st);
63 @endcode
64
65 @code
66 // Example: Gzip compression with custom window size
67 boost::http::zlib::stream st = {};
68 st.zalloc = nullptr;
69 st.zfree = nullptr;
70
71 // Use gzip format (16 + 15 for max window)
72 deflate_svc.init2(st,
73 6, // level
74 boost::http::zlib::deflated, // method
75 16 + 15, // gzip format
76 8, // memLevel
77 boost::http::zlib::default_strategy); // strategy
78
79 // Compress data...
80 deflate_svc.deflate_end(st);
81 @endcode
82 */
83 struct BOOST_SYMBOL_VISIBLE
84 deflate_service
85 : capy::execution_context::service
86 {
87 /** Return the ZLib version string. */
88 virtual char const* version() const noexcept = 0;
89
90 /** Initialize deflate compression.
91 @param st The stream to initialize.
92 @param level The compression level.
93 @return Zero on success, or an error code.
94 */
95 virtual int init(stream& st, int level) const = 0;
96
97 /** Initialize deflate compression with extended parameters.
98 @param st The stream to initialize.
99 @param level The compression level.
100 @param method The compression method.
101 @param windowBits The base-2 logarithm of the window size.
102 @param memLevel Memory usage level (1-9).
103 @param strategy The compression strategy.
104 @return Zero on success, or an error code.
105 */
106 virtual int init2(stream& st, int level, int method,
107 int windowBits, int memLevel, int strategy) const = 0;
108
109 /** Set the compression dictionary.
110 @param st The stream.
111 @param dict Pointer to the dictionary data.
112 @param len Length of the dictionary.
113 @return Zero on success, or an error code.
114 */
115 virtual int set_dict(stream& st, unsigned char const* dict, unsigned len) const = 0;
116
117 /** Return the current compression dictionary.
118 @param st The stream.
119 @param dest Destination buffer for the dictionary.
120 @param len Pointer to variable receiving dictionary length.
121 @return Zero on success, or an error code.
122 */
123 virtual int get_dict(stream& st, unsigned char* dest, unsigned* len) const = 0;
124
125 /** Duplicate a deflate stream.
126 @param dest The destination stream.
127 @param src The source stream to duplicate.
128 @return Zero on success, or an error code.
129 */
130 virtual int dup(stream& dest, stream& src) const = 0;
131
132 /** Compress data in the stream.
133 @param st The stream containing data to compress.
134 @param flush The flush mode.
135 @return Status code indicating compression state.
136 */
137 virtual int deflate(stream& st, int flush) const = 0;
138
139 /** Release all resources held by the deflate stream.
140 @param st The stream to finalize.
141 @return Zero on success, or an error code.
142 */
143 virtual int deflate_end(stream& st) const = 0;
144
145 /** Reset the deflate stream state.
146 @param st The stream to reset.
147 @return Zero on success, or an error code.
148 */
149 virtual int reset(stream& st) const = 0;
150
151 /** Dynamically update compression parameters.
152 @param st The stream.
153 @param level The new compression level.
154 @param strategy The new compression strategy.
155 @return Zero on success, or an error code.
156 */
157 virtual int params(stream& st, int level, int strategy) const = 0;
158
159 /** Return an upper bound on compressed size.
160 @param st The stream.
161 @param sourceLen The length of source data.
162 @return Maximum possible compressed size.
163 */
164 virtual std::size_t bound(stream& st, unsigned long sourceLen) const = 0;
165
166 /** Return the number of pending output bytes.
167 @param st The stream.
168 @param pending Pointer to variable receiving pending byte count.
169 @param bits Pointer to variable receiving pending bit count.
170 @return Zero on success, or an error code.
171 */
172 virtual int pending(stream& st, unsigned* pending, int* bits) const = 0;
173
174 /** Insert bits into the compressed stream.
175 @param st The stream.
176 @param bits Number of bits to insert.
177 @param value The bit pattern to insert.
178 @return Zero on success, or an error code.
179 */
180 virtual int prime(stream& st, int bits, int value) const = 0;
181
182 /** Set the gzip header information.
183 @param st The stream.
184 @param header Pointer to gzip header structure.
185 @return Zero on success, or an error code.
186 */
187 virtual int set_header(stream& st, void* header) const = 0;
188
189 protected:
190 1 void shutdown() override {}
191 };
192
193 } // zlib
194 } // http
195 } // boost
196
197 #endif
198