1 // Copyright (C) 2009 Google LLC 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 // This file contains the definition for classes GzipInputStream and 16 // GzipOutputStream. It is forked from protobuf because these classes are only 17 // provided in libprotobuf-full but we would like to link libicing against the 18 // smaller libprotobuf-lite instead. 19 // 20 // GzipInputStream decompresses data from an underlying 21 // ZeroCopyInputStream and provides the decompressed data as a 22 // ZeroCopyInputStream. 23 // 24 // GzipOutputStream is an ZeroCopyOutputStream that compresses data to 25 // an underlying ZeroCopyOutputStream. 26 27 #ifndef GOOGLE3_ICING_PORTABLE_GZIP_STREAM_H_ 28 #define GOOGLE3_ICING_PORTABLE_GZIP_STREAM_H_ 29 30 #include "icing/portable/zlib.h" 31 #include <google/protobuf/io/zero_copy_stream_impl_lite.h> 32 33 namespace icing { 34 namespace lib { 35 namespace protobuf_ports { 36 37 // A ZeroCopyInputStream that reads compressed data through zlib 38 class GzipInputStream : public google::protobuf::io::ZeroCopyInputStream { 39 public: 40 // Format key for constructor 41 enum Format { 42 // zlib will autodetect gzip header or deflate stream 43 AUTO = 0, 44 45 // GZIP streams have some extra header data for file attributes. 46 GZIP = 1, 47 48 // Simpler zlib stream format. 49 ZLIB = 2, 50 }; 51 52 // buffer_size and format may be -1 for default of 64kB and GZIP format 53 explicit GzipInputStream(google::protobuf::io::ZeroCopyInputStream* sub_stream, 54 Format format = AUTO, int buffer_size = -1); 55 virtual ~GzipInputStream(); 56 57 // Return last error message or NULL if no error. ZlibErrorMessage()58 inline const char* ZlibErrorMessage() const { return zcontext_.msg; } ZlibErrorCode()59 inline int ZlibErrorCode() const { return zerror_; } 60 61 // implements ZeroCopyInputStream ---------------------------------- 62 bool Next(const void** data, int* size) override; 63 void BackUp(int count) override; 64 bool Skip(int count) override; 65 int64_t ByteCount() const override; 66 67 private: 68 Format format_; 69 70 google::protobuf::io::ZeroCopyInputStream* sub_stream_; 71 72 z_stream zcontext_; 73 int zerror_; 74 75 void* output_buffer_; 76 void* output_position_; 77 size_t output_buffer_length_; 78 int64_t byte_count_; 79 80 int Inflate(int flush); 81 void DoNextOutput(const void** data, int* size); 82 }; 83 84 class GzipOutputStream : public google::protobuf::io::ZeroCopyOutputStream { 85 public: 86 // Format key for constructor 87 enum Format { 88 // GZIP streams have some extra header data for file attributes. 89 GZIP = 1, 90 91 // Simpler zlib stream format. 92 ZLIB = 2, 93 }; 94 95 struct Options { 96 // Defaults to GZIP. 97 Format format; 98 99 // What size buffer to use internally. Defaults to 64kB. 100 int buffer_size; 101 102 // A number between 0 and 9, where 0 is no compression and 9 is best 103 // compression. Defaults to Z_DEFAULT_COMPRESSION (see zlib.h). 104 int compression_level; 105 106 // Defaults to Z_DEFAULT_STRATEGY. Can also be set to Z_FILTERED, 107 // Z_HUFFMAN_ONLY, or Z_RLE. See the documentation for deflateInit2 in 108 // zlib.h for definitions of these constants. 109 int compression_strategy; 110 111 Options(); // Initializes with default values. 112 }; 113 114 // Create a GzipOutputStream with default options. 115 explicit GzipOutputStream(google::protobuf::io::ZeroCopyOutputStream* sub_stream); 116 117 // Create a GzipOutputStream with the given options. 118 GzipOutputStream(google::protobuf::io::ZeroCopyOutputStream* sub_stream, 119 const Options& options); 120 121 virtual ~GzipOutputStream(); 122 123 // Return last error message or NULL if no error. ZlibErrorMessage()124 inline const char* ZlibErrorMessage() const { return zcontext_.msg; } ZlibErrorCode()125 inline int ZlibErrorCode() const { return zerror_; } 126 127 // Flushes data written so far to zipped data in the underlying stream. 128 // It is the caller's responsibility to flush the underlying stream if 129 // necessary. 130 // Compression may be less efficient stopping and starting around flushes. 131 // Returns true if no error. 132 // 133 // Please ensure that block size is > 6. Here is an excerpt from the zlib 134 // doc that explains why: 135 // 136 // In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that avail_out 137 // is greater than six to avoid repeated flush markers due to 138 // avail_out == 0 on return. 139 bool Flush(); 140 141 // Writes out all data and closes the gzip stream. 142 // It is the caller's responsibility to close the underlying stream if 143 // necessary. 144 // Returns true if no error. 145 bool Close(); 146 147 // implements ZeroCopyOutputStream --------------------------------- 148 bool Next(void** data, int* size) override; 149 void BackUp(int count) override; 150 int64_t ByteCount() const override; 151 152 private: 153 google::protobuf::io::ZeroCopyOutputStream* sub_stream_; 154 // Result from calling Next() on sub_stream_ 155 void* sub_data_; 156 int sub_data_size_; 157 158 z_stream zcontext_; 159 int zerror_; 160 void* input_buffer_; 161 size_t input_buffer_length_; 162 163 // Shared constructor code. 164 void Init(google::protobuf::io::ZeroCopyOutputStream* sub_stream, 165 const Options& options); 166 167 // Do some compression. 168 // Takes zlib flush mode. 169 // Returns zlib error code. 170 int Deflate(int flush); 171 }; 172 173 } // namespace protobuf_ports 174 } // namespace lib 175 } // namespace icing 176 177 #endif // GOOGLE3_ICING_PORTABLE_GZIP_STREAM_H_ 178