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/*
* Copyright 2009, Google Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* 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.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
//
// GzCompressor compresses a byte stream using gzip compression
// calling the client's ProcessBytes() method with the compressed stream
//
#include "import/cross/gz_compressor.h"
#include <assert.h>
#include "import/cross/memory_buffer.h"
#include "import/cross/memory_stream.h"
#include "zutil.h"
const size_t kChunkSize = 16384;
namespace o3d {
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
GzCompressor::GzCompressor(StreamProcessor *callback_client)
: stream_is_closed_(false),
callback_client_(callback_client) {
strm_.zalloc = Z_NULL;
strm_.zfree = Z_NULL;
strm_.opaque = Z_NULL;
// Store this, so we can later check if it's OK to start processing
int result = deflateInit2(
&strm_,
Z_DEFAULT_COMPRESSION,
Z_DEFLATED,
MAX_WBITS + 16, // 16 means write out gzip header/trailer
DEF_MEM_LEVEL,
Z_DEFAULT_STRATEGY);
initialized_ = result == Z_OK;
}
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
void GzCompressor::Close(bool success) {
if (!stream_is_closed_) {
// Flush the compression stream
MemoryReadStream stream(NULL, 0);
CompressBytes(&stream, 0, true);
// Deallocate resources
deflateEnd(&strm_);
stream_is_closed_ = true;
}
callback_client_->Close(success);
}
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
GzCompressor::~GzCompressor() {
}
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
StreamProcessor::Status GzCompressor::ProcessBytes(MemoryReadStream *stream,
size_t bytes_to_process) {
// Basic sanity check
if (stream->GetDirectMemoryPointer() == NULL || bytes_to_process == 0) {
return FAILURE;
}
return CompressBytes(stream, bytes_to_process, false);
}
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
StreamProcessor::Status GzCompressor::CompressBytes(MemoryReadStream *stream,
size_t bytes_to_process,
bool flush) {
// Don't even bother trying if we didn't get initialized properly
if (!initialized_) return FAILURE;
uint8 out[kChunkSize];
// Don't try to read more than our stream has
size_t remaining = stream->GetRemainingByteCount();
if (bytes_to_process > remaining) {
return FAILURE;
}
// Use direct memory access on the MemoryStream object
const uint8 *input_data = stream->GetDirectMemoryPointer();
stream->Skip(bytes_to_process);
// Fill out the zlib z_stream struct
strm_.avail_in = bytes_to_process;
strm_.next_in = const_cast<uint8*>(input_data);
// We need to flush the stream when we reach the end
int flush_code = flush ? Z_FINISH : Z_NO_FLUSH;
// Run deflate() on input until output buffer not full
int result;
do {
strm_.avail_out = kChunkSize;
strm_.next_out = out;
result = deflate(&strm_, flush_code);
if (result == Z_STREAM_ERROR)
return FAILURE;
size_t have = kChunkSize - strm_.avail_out;
// Callback with the compressed byte stream
MemoryReadStream decompressed_stream(out, have);
if (have > 0 && callback_client_) {
if (callback_client_->ProcessBytes(&decompressed_stream,
have) == FAILURE) {
return FAILURE;
}
}
} while (strm_.avail_out == 0);
return result == Z_OK ? IN_PROGRESS : FAILURE;
}
} // namespace o3d
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