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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "chrome/browser/sessions/compress_data_helper.h"
#include "base/memory/scoped_ptr.h"
#include "base/pickle.h"
#if defined(USE_SYSTEM_LIBBZ2)
#include <bzlib.h>
#else
#include "third_party/bzip2/bzlib.h"
#endif
#include <string>
// static
void CompressDataHelper::CompressAndWriteStringToPickle(const std::string& str,
int max_bytes,
Pickle* pickle,
int* bytes_written) {
// If there is no data to write, only write the size (0).
if (str.empty()) {
pickle->WriteInt(0);
return;
}
bool written = false;
int max_output_size = max_bytes - *bytes_written;
if (max_output_size > 0) {
// We need a non-const char* to pass to the compression algorithm.
int input_size = str.size();
scoped_array<char> input(new char[input_size]);
memcpy(input.get(), str.data(), input_size);
scoped_array<char> output(new char[max_output_size]);
memset(output.get(), 0, max_output_size);
bz_stream stream;
stream.bzalloc = NULL;
stream.bzfree = NULL;
stream.opaque = NULL;
int result = BZ2_bzCompressInit(&stream,
1, // 100K block size ( > size of our data)
0, // quiet
0); // default work factor
if (result == BZ_OK) {
stream.next_in = input.get();
stream.avail_in = input_size;
stream.next_out = output.get();
stream.avail_out = max_output_size;
do {
result = BZ2_bzCompress(&stream, BZ_FINISH);
} while (result == BZ_FINISH_OK);
// If there wasn't enough space for the output, the result won't be
// BZ_STREAM_END.
if (result == BZ_STREAM_END) {
result = BZ2_bzCompressEnd(&stream);
DCHECK(stream.total_out_lo32 <=
static_cast<unsigned>(max_output_size));
if (result == BZ_OK) {
// Write the size of the original input, so that the decompression
// part knows how much memory to allocate.
pickle->WriteInt(input_size);
pickle->WriteData(output.get(), stream.total_out_lo32);
*bytes_written += stream.total_out_lo32;
written = true;
}
} else {
BZ2_bzCompressEnd(&stream);
}
}
}
if (!written) {
// We cannot write any data. Write only the data size (0). The reading part
// will not try to read any data after seeing the size 0.
pickle->WriteInt(0);
}
}
// static
bool CompressDataHelper::ReadAndDecompressStringFromPickle(const Pickle& pickle,
void** iter,
std::string* str) {
// Read the size of the original data.
int original_size = 0;
if (!pickle.ReadLength(iter, &original_size))
return false;
if (original_size == 0) {
// No data to decompress.
return true;
}
// Read the compressed data.
const char* compressed_data = NULL;
int compressed_size = 0;
if (!pickle.ReadData(iter, &compressed_data, &compressed_size))
return false;
scoped_array<char> original_data(new char[original_size]);
memset(original_data.get(), 0, original_size);
// We need a non-const char* to pass to the decompression algorithm.
scoped_array<char> compressed_data_copy(new char[compressed_size]);
memcpy(compressed_data_copy.get(), compressed_data, compressed_size);
bz_stream stream;
stream.bzalloc = NULL;
stream.bzfree = NULL;
stream.opaque = NULL;
int result = BZ2_bzDecompressInit(&stream, 0, 0);
if (result == BZ_OK) {
stream.next_in = compressed_data_copy.get();
stream.avail_in = compressed_size;
stream.next_out = original_data.get();
stream.avail_out = original_size;
do {
// We should know exactly how much space to allocate for the result, thus
// no out-of-space errors should happen.
DCHECK(stream.avail_out > 0);
result = BZ2_bzDecompress(&stream);
} while (result == BZ_OK);
DCHECK(result == BZ_STREAM_END);
if (result == BZ_STREAM_END) {
result = BZ2_bzDecompressEnd(&stream);
if (result == BZ_OK) {
str->assign(original_data.get(), original_size);
}
} else {
BZ2_bzDecompressEnd(&stream);
}
}
return !str->empty();
}
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