// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc. All rights reserved.
// https://developers.google.com/protocol-buffers/
//
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// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
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//
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// Author: brianolson@google.com (Brian Olson)
//
// This file contains the definition for classes GzipInputStream and
// GzipOutputStream.
//
// GzipInputStream decompresses data from an underlying
// ZeroCopyInputStream and provides the decompressed data as a
// ZeroCopyInputStream.
//
// GzipOutputStream is an ZeroCopyOutputStream that compresses data to
// an underlying ZeroCopyOutputStream.
#ifndef GOOGLE_PROTOBUF_IO_GZIP_STREAM_H__
#define GOOGLE_PROTOBUF_IO_GZIP_STREAM_H__
#include <google/protobuf/stubs/common.h>
#include <google/protobuf/io/zero_copy_stream.h>
#include <zlib.h>
namespace google {
namespace protobuf {
namespace io {
// A ZeroCopyInputStream that reads compressed data through zlib
class LIBPROTOBUF_EXPORT GzipInputStream : public ZeroCopyInputStream {
public:
// Format key for constructor
enum Format {
// zlib will autodetect gzip header or deflate stream
AUTO = 0,
// GZIP streams have some extra header data for file attributes.
GZIP = 1,
// Simpler zlib stream format.
ZLIB = 2,
};
// buffer_size and format may be -1 for default of 64kB and GZIP format
explicit GzipInputStream(
ZeroCopyInputStream* sub_stream,
Format format = AUTO,
int buffer_size = -1);
virtual ~GzipInputStream();
// Return last error message or NULL if no error.
inline const char* ZlibErrorMessage() const {
return zcontext_.msg;
}
inline int ZlibErrorCode() const {
return zerror_;
}
// implements ZeroCopyInputStream ----------------------------------
bool Next(const void** data, int* size);
void BackUp(int count);
bool Skip(int count);
int64 ByteCount() const;
private:
Format format_;
ZeroCopyInputStream* sub_stream_;
z_stream zcontext_;
int zerror_;
void* output_buffer_;
void* output_position_;
size_t output_buffer_length_;
int64 byte_count_;
int Inflate(int flush);
void DoNextOutput(const void** data, int* size);
GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(GzipInputStream);
};
class LIBPROTOBUF_EXPORT GzipOutputStream : public ZeroCopyOutputStream {
public:
// Format key for constructor
enum Format {
// GZIP streams have some extra header data for file attributes.
GZIP = 1,
// Simpler zlib stream format.
ZLIB = 2,
};
struct Options {
// Defaults to GZIP.
Format format;
// What size buffer to use internally. Defaults to 64kB.
int buffer_size;
// A number between 0 and 9, where 0 is no compression and 9 is best
// compression. Defaults to Z_DEFAULT_COMPRESSION (see zlib.h).
int compression_level;
// Defaults to Z_DEFAULT_STRATEGY. Can also be set to Z_FILTERED,
// Z_HUFFMAN_ONLY, or Z_RLE. See the documentation for deflateInit2 in
// zlib.h for definitions of these constants.
int compression_strategy;
Options(); // Initializes with default values.
};
// Create a GzipOutputStream with default options.
explicit GzipOutputStream(ZeroCopyOutputStream* sub_stream);
// Create a GzipOutputStream with the given options.
GzipOutputStream(
ZeroCopyOutputStream* sub_stream,
const Options& options);
virtual ~GzipOutputStream();
// Return last error message or NULL if no error.
inline const char* ZlibErrorMessage() const {
return zcontext_.msg;
}
inline int ZlibErrorCode() const {
return zerror_;
}
// Flushes data written so far to zipped data in the underlying stream.
// It is the caller's responsibility to flush the underlying stream if
// necessary.
// Compression may be less efficient stopping and starting around flushes.
// Returns true if no error.
//
// Please ensure that block size is > 6. Here is an excerpt from the zlib
// doc that explains why:
//
// In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that avail_out
// is greater than six to avoid repeated flush markers due to
// avail_out == 0 on return.
bool Flush();
// Writes out all data and closes the gzip stream.
// It is the caller's responsibility to close the underlying stream if
// necessary.
// Returns true if no error.
bool Close();
// implements ZeroCopyOutputStream ---------------------------------
bool Next(void** data, int* size);
void BackUp(int count);
int64 ByteCount() const;
private:
ZeroCopyOutputStream* sub_stream_;
// Result from calling Next() on sub_stream_
void* sub_data_;
int sub_data_size_;
z_stream zcontext_;
int zerror_;
void* input_buffer_;
size_t input_buffer_length_;
// Shared constructor code.
void Init(ZeroCopyOutputStream* sub_stream, const Options& options);
// Do some compression.
// Takes zlib flush mode.
// Returns zlib error code.
int Deflate(int flush);
GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(GzipOutputStream);
};
} // namespace io
} // namespace protobuf
} // namespace google
#endif // GOOGLE_PROTOBUF_IO_GZIP_STREAM_H__
