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1 : //
2 : // Copyright (c) 2021 Vinnie Falco (vinnie.falco@gmail.com)
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
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