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// Protocol Buffers - Google's data interchange format
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// Copyright 2008 Google Inc. All rights reserved.
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// http://code.google.com/p/protobuf/
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following disclaimer
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// in the documentation and/or other materials provided with the
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// * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived from
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// this software without specific prior written permission.
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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// Author: brianolson@google.com (Brian Olson)
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// This file contains the definition for classes GzipInputStream and
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// GzipInputStream decompresses data from an underlying
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// ZeroCopyInputStream and provides the decompressed data as a
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// ZeroCopyInputStream.
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// GzipOutputStream is an ZeroCopyOutputStream that compresses data to
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// an underlying ZeroCopyOutputStream.
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#ifndef GOOGLE_PROTOBUF_IO_GZIP_STREAM_H__
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#define GOOGLE_PROTOBUF_IO_GZIP_STREAM_H__
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#include <google/protobuf/stubs/common.h>
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#include <google/protobuf/io/zero_copy_stream.h>
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// A ZeroCopyInputStream that reads compressed data through zlib
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class LIBPROTOBUF_EXPORT GzipInputStream : public ZeroCopyInputStream {
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// Format key for constructor
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// zlib will autodetect gzip header or deflate stream
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// GZIP streams have some extra header data for file attributes.
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// Simpler zlib stream format.
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// buffer_size and format may be -1 for default of 64kB and GZIP format
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explicit GzipInputStream(
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ZeroCopyInputStream* sub_stream,
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int buffer_size = -1);
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virtual ~GzipInputStream();
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// Return last error message or NULL if no error.
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inline const char* ZlibErrorMessage() const {
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inline int ZlibErrorCode() const {
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// implements ZeroCopyInputStream ----------------------------------
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bool Next(const void** data, int* size);
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void BackUp(int count);
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int64 ByteCount() const;
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ZeroCopyInputStream* sub_stream_;
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void* output_position_;
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size_t output_buffer_length_;
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int Inflate(int flush);
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void DoNextOutput(const void** data, int* size);
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GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(GzipInputStream);
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class LIBPROTOBUF_EXPORT GzipOutputStream : public ZeroCopyOutputStream {
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// Format key for constructor
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// GZIP streams have some extra header data for file attributes.
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// Simpler zlib stream format.
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struct LIBPROTOBUF_EXPORT Options {
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// What size buffer to use internally. Defaults to 64kB.
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// A number between 0 and 9, where 0 is no compression and 9 is best
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// compression. Defaults to Z_DEFAULT_COMPRESSION (see zlib.h).
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int compression_level;
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// Defaults to Z_DEFAULT_STRATEGY. Can also be set to Z_FILTERED,
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// Z_HUFFMAN_ONLY, or Z_RLE. See the documentation for deflateInit2 in
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// zlib.h for definitions of these constants.
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int compression_strategy;
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Options(); // Initializes with default values.
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// Create a GzipOutputStream with default options.
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explicit GzipOutputStream(ZeroCopyOutputStream* sub_stream);
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// Create a GzipOutputStream with the given options.
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ZeroCopyOutputStream* sub_stream,
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const Options& options);
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virtual ~GzipOutputStream();
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// Return last error message or NULL if no error.
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inline const char* ZlibErrorMessage() const {
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return zcontext_.msg;
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inline int ZlibErrorCode() const {
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// Flushes data written so far to zipped data in the underlying stream.
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// It is the caller's responsibility to flush the underlying stream if
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// Compression may be less efficient stopping and starting around flushes.
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// Returns true if no error.
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// Please ensure that block size is > 6. Here is an excerpt from the zlib
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// doc that explains why:
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// In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that avail_out
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// is greater than six to avoid repeated flush markers due to
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// avail_out == 0 on return.
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// Writes out all data and closes the gzip stream.
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// It is the caller's responsibility to close the underlying stream if
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// Returns true if no error.
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// implements ZeroCopyOutputStream ---------------------------------
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bool Next(void** data, int* size);
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void BackUp(int count);
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int64 ByteCount() const;
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ZeroCopyOutputStream* sub_stream_;
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// Result from calling Next() on sub_stream_
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size_t input_buffer_length_;
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// Shared constructor code.
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void Init(ZeroCopyOutputStream* sub_stream, const Options& options);
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// Do some compression.
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// Takes zlib flush mode.
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// Returns zlib error code.
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int Deflate(int flush);
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GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(GzipOutputStream);
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} // namespace protobuf
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} // namespace google
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#endif // GOOGLE_PROTOBUF_IO_GZIP_STREAM_H__