/thirdparty/breakpad/third_party/protobuf/protobuf/src/google/protobuf/io/gzip_stream.h

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 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#include <zlib.h>
 47
 48#include <google/protobuf/io/zero_copy_stream.h>
 49
 50namespace google {
 51namespace protobuf {
 52namespace io {
 53
 54// A ZeroCopyInputStream that reads compressed data through zlib
 55class LIBPROTOBUF_EXPORT GzipInputStream : public ZeroCopyInputStream {
 56 public:
 57  // Format key for constructor
 58  enum Format {
 59    // zlib will autodetect gzip header or deflate stream
 60    AUTO = 0,
 61
 62    // GZIP streams have some extra header data for file attributes.
 63    GZIP = 1,
 64
 65    // Simpler zlib stream format.
 66    ZLIB = 2,
 67  };
 68
 69  // buffer_size and format may be -1 for default of 64kB and GZIP format
 70  explicit GzipInputStream(
 71      ZeroCopyInputStream* sub_stream,
 72      Format format = AUTO,
 73      int buffer_size = -1);
 74  virtual ~GzipInputStream();
 75
 76  // Return last error message or NULL if no error.
 77  inline const char* ZlibErrorMessage() const {
 78    return zcontext_.msg;
 79  }
 80  inline int ZlibErrorCode() const {
 81    return zerror_;
 82  }
 83
 84  // implements ZeroCopyInputStream ----------------------------------
 85  bool Next(const void** data, int* size);
 86  void BackUp(int count);
 87  bool Skip(int count);
 88  int64 ByteCount() const;
 89
 90 private:
 91  Format format_;
 92
 93  ZeroCopyInputStream* sub_stream_;
 94
 95  z_stream zcontext_;
 96  int zerror_;
 97
 98  void* output_buffer_;
 99  void* output_position_;
100  size_t output_buffer_length_;
101
102  int Inflate(int flush);
103  void DoNextOutput(const void** data, int* size);
104
105  GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(GzipInputStream);
106};
107
108
109class LIBPROTOBUF_EXPORT GzipOutputStream : public ZeroCopyOutputStream {
110 public:
111  // Format key for constructor
112  enum Format {
113    // GZIP streams have some extra header data for file attributes.
114    GZIP = 1,
115
116    // Simpler zlib stream format.
117    ZLIB = 2,
118  };
119
120  struct Options {
121    // Defaults to GZIP.
122    Format format;
123
124    // What size buffer to use internally.  Defaults to 64kB.
125    int buffer_size;
126
127    // A number between 0 and 9, where 0 is no compression and 9 is best
128    // compression.  Defaults to Z_DEFAULT_COMPRESSION (see zlib.h).
129    int compression_level;
130
131    // Defaults to Z_DEFAULT_STRATEGY.  Can also be set to Z_FILTERED,
132    // Z_HUFFMAN_ONLY, or Z_RLE.  See the documentation for deflateInit2 in
133    // zlib.h for definitions of these constants.
134    int compression_strategy;
135
136    Options();  // Initializes with default values.
137  };
138
139  // Create a GzipOutputStream with default options.
140  explicit GzipOutputStream(ZeroCopyOutputStream* sub_stream);
141
142  // Create a GzipOutputStream with the given options.
143  GzipOutputStream(
144      ZeroCopyOutputStream* sub_stream,
145      const Options& options);
146
147  // DEPRECATED:  Use one of the above constructors instead.
148  GzipOutputStream(
149      ZeroCopyOutputStream* sub_stream,
150      Format format,
151      int buffer_size = -1) GOOGLE_ATTRIBUTE_DEPRECATED;
152
153  virtual ~GzipOutputStream();
154
155  // Return last error message or NULL if no error.
156  inline const char* ZlibErrorMessage() const {
157    return zcontext_.msg;
158  }
159  inline int ZlibErrorCode() const {
160    return zerror_;
161  }
162
163  // Flushes data written so far to zipped data in the underlying stream.
164  // It is the caller's responsibility to flush the underlying stream if
165  // necessary.
166  // Compression may be less efficient stopping and starting around flushes.
167  // Returns true if no error.
168  bool Flush();
169
170  // Writes out all data and closes the gzip stream.
171  // It is the caller's responsibility to close the underlying stream if
172  // necessary.
173  // Returns true if no error.
174  bool Close();
175
176  // implements ZeroCopyOutputStream ---------------------------------
177  bool Next(void** data, int* size);
178  void BackUp(int count);
179  int64 ByteCount() const;
180
181 private:
182  ZeroCopyOutputStream* sub_stream_;
183  // Result from calling Next() on sub_stream_
184  void* sub_data_;
185  int sub_data_size_;
186
187  z_stream zcontext_;
188  int zerror_;
189  void* input_buffer_;
190  size_t input_buffer_length_;
191
192  // Shared constructor code.
193  void Init(ZeroCopyOutputStream* sub_stream, const Options& options);
194
195  // Do some compression.
196  // Takes zlib flush mode.
197  // Returns zlib error code.
198  int Deflate(int flush);
199
200  GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(GzipOutputStream);
201};
202
203}  // namespace io
204}  // namespace protobuf
205
206}  // namespace google
207#endif  // GOOGLE_PROTOBUF_IO_GZIP_STREAM_H__