1 // Protocol Buffers - Google's data interchange format 2 // Copyright 2008 Google Inc. All rights reserved. 3 // https://developers.google.com/protocol-buffers/ 4 // 5 // Redistribution and use in source and binary forms, with or without 6 // modification, are permitted provided that the following conditions are 7 // met: 8 // 9 // * Redistributions of source code must retain the above copyright 10 // notice, this list of conditions and the following disclaimer. 11 // * Redistributions in binary form must reproduce the above 12 // copyright notice, this list of conditions and the following disclaimer 13 // in the documentation and/or other materials provided with the 14 // distribution. 15 // * Neither the name of Google Inc. nor the names of its 16 // contributors may be used to endorse or promote products derived from 17 // this software without specific prior written permission. 18 // 19 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 20 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 21 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 22 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 23 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 24 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 25 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 26 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 27 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 28 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 29 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 30 31 // Author: brianolson@google.com (Brian Olson) 32 // 33 // This file contains the definition for classes GzipInputStream and 34 // GzipOutputStream. 35 // 36 // GzipInputStream decompresses data from an underlying 37 // ZeroCopyInputStream and provides the decompressed data as a 38 // ZeroCopyInputStream. 39 // 40 // GzipOutputStream is an ZeroCopyOutputStream that compresses data to 41 // an underlying ZeroCopyOutputStream. 42 43 #ifndef GOOGLE_PROTOBUF_IO_GZIP_STREAM_H__ 44 #define GOOGLE_PROTOBUF_IO_GZIP_STREAM_H__ 45 46 47 #include <google/protobuf/stubs/common.h> 48 #include <google/protobuf/io/zero_copy_stream.h> 49 #include <google/protobuf/port.h> 50 #include <zlib.h> 51 52 #include <google/protobuf/port_def.inc> 53 54 namespace google { 55 namespace protobuf { 56 namespace io { 57 58 // A ZeroCopyInputStream that reads compressed data through zlib 59 class PROTOBUF_EXPORT GzipInputStream : public ZeroCopyInputStream { 60 public: 61 // Format key for constructor 62 enum Format { 63 // zlib will autodetect gzip header or deflate stream 64 AUTO = 0, 65 66 // GZIP streams have some extra header data for file attributes. 67 GZIP = 1, 68 69 // Simpler zlib stream format. 70 ZLIB = 2, 71 }; 72 73 // buffer_size and format may be -1 for default of 64kB and GZIP format 74 explicit GzipInputStream(ZeroCopyInputStream* sub_stream, 75 Format format = AUTO, int buffer_size = -1); 76 virtual ~GzipInputStream(); 77 78 // Return last error message or NULL if no error. ZlibErrorMessage()79 inline const char* ZlibErrorMessage() const { return zcontext_.msg; } ZlibErrorCode()80 inline int ZlibErrorCode() const { return zerror_; } 81 82 // implements ZeroCopyInputStream ---------------------------------- 83 bool Next(const void** data, int* size) override; 84 void BackUp(int count) override; 85 bool Skip(int count) override; 86 int64_t ByteCount() const override; 87 88 private: 89 Format format_; 90 91 ZeroCopyInputStream* sub_stream_; 92 93 z_stream zcontext_; 94 int zerror_; 95 96 void* output_buffer_; 97 void* output_position_; 98 size_t output_buffer_length_; 99 int64_t byte_count_; 100 101 int Inflate(int flush); 102 void DoNextOutput(const void** data, int* size); 103 104 GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(GzipInputStream); 105 }; 106 107 class PROTOBUF_EXPORT GzipOutputStream : public ZeroCopyOutputStream { 108 public: 109 // Format key for constructor 110 enum Format { 111 // GZIP streams have some extra header data for file attributes. 112 GZIP = 1, 113 114 // Simpler zlib stream format. 115 ZLIB = 2, 116 }; 117 118 struct PROTOBUF_EXPORT Options { 119 // Defaults to GZIP. 120 Format format; 121 122 // What size buffer to use internally. Defaults to 64kB. 123 int buffer_size; 124 125 // A number between 0 and 9, where 0 is no compression and 9 is best 126 // compression. Defaults to Z_DEFAULT_COMPRESSION (see zlib.h). 127 int compression_level; 128 129 // Defaults to Z_DEFAULT_STRATEGY. Can also be set to Z_FILTERED, 130 // Z_HUFFMAN_ONLY, or Z_RLE. See the documentation for deflateInit2 in 131 // zlib.h for definitions of these constants. 132 int compression_strategy; 133 134 Options(); // Initializes with default values. 135 }; 136 137 // Create a GzipOutputStream with default options. 138 explicit GzipOutputStream(ZeroCopyOutputStream* sub_stream); 139 140 // Create a GzipOutputStream with the given options. 141 GzipOutputStream(ZeroCopyOutputStream* sub_stream, const Options& options); 142 143 virtual ~GzipOutputStream(); 144 145 // Return last error message or NULL if no error. ZlibErrorMessage()146 inline const char* ZlibErrorMessage() const { return zcontext_.msg; } ZlibErrorCode()147 inline int ZlibErrorCode() const { return zerror_; } 148 149 // Flushes data written so far to zipped data in the underlying stream. 150 // It is the caller's responsibility to flush the underlying stream if 151 // necessary. 152 // Compression may be less efficient stopping and starting around flushes. 153 // Returns true if no error. 154 // 155 // Please ensure that block size is > 6. Here is an excerpt from the zlib 156 // doc that explains why: 157 // 158 // In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that avail_out 159 // is greater than six to avoid repeated flush markers due to 160 // avail_out == 0 on return. 161 bool Flush(); 162 163 // Writes out all data and closes the gzip stream. 164 // It is the caller's responsibility to close the underlying stream if 165 // necessary. 166 // Returns true if no error. 167 bool Close(); 168 169 // implements ZeroCopyOutputStream --------------------------------- 170 bool Next(void** data, int* size) override; 171 void BackUp(int count) override; 172 int64_t ByteCount() const override; 173 174 private: 175 ZeroCopyOutputStream* sub_stream_; 176 // Result from calling Next() on sub_stream_ 177 void* sub_data_; 178 int sub_data_size_; 179 180 z_stream zcontext_; 181 int zerror_; 182 void* input_buffer_; 183 size_t input_buffer_length_; 184 185 // Shared constructor code. 186 void Init(ZeroCopyOutputStream* sub_stream, const Options& options); 187 188 // Do some compression. 189 // Takes zlib flush mode. 190 // Returns zlib error code. 191 int Deflate(int flush); 192 193 GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(GzipOutputStream); 194 }; 195 196 } // namespace io 197 } // namespace protobuf 198 } // namespace google 199 200 #include <google/protobuf/port_undef.inc> 201 202 #endif // GOOGLE_PROTOBUF_IO_GZIP_STREAM_H__ 203