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// Copyright (c) 2006-2008 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 <algorithm>
#include "base/file_util.h"
#include "base/histogram.h"
#include "base/logging.h"
#include "net/base/sdch_filter.h"
#include "net/base/sdch_manager.h"
#include "sdch/open_vcdiff/depot/opensource/open-vcdiff/src/google/vcdecoder.h"
SdchFilter::SdchFilter()
: decoding_status_(DECODING_UNINITIALIZED),
vcdiff_streaming_decoder_(NULL),
dictionary_(NULL),
dest_buffer_excess_(),
dest_buffer_excess_index_(0),
source_bytes_(0),
output_bytes_(0) {
}
SdchFilter::~SdchFilter() {
if (vcdiff_streaming_decoder_.get()) {
if (!vcdiff_streaming_decoder_->FinishDecoding())
decoding_status_ = DECODING_ERROR;
}
// TODO(jar): Use DHISTOGRAM when we turn sdch on by default.
if (decoding_status_ == DECODING_ERROR) {
HISTOGRAM_COUNTS(L"Sdch.Decoding Error bytes read", source_bytes_);
HISTOGRAM_COUNTS(L"Sdch.Decoding Error bytes output", output_bytes_);
} else {
if (decoding_status_ == DECODING_IN_PROGRESS) {
HISTOGRAM_COUNTS(L"Sdch.Bytes read", source_bytes_);
HISTOGRAM_COUNTS(L"Sdch.Bytes output", output_bytes_);
}
}
if (dictionary_)
dictionary_->Release();
}
bool SdchFilter::InitDecoding() {
if (decoding_status_ != DECODING_UNINITIALIZED)
return false;
// Initialize decoder only after we have a dictionary in hand.
decoding_status_ = WAITING_FOR_DICTIONARY_SELECTION;
return true;
}
Filter::FilterStatus SdchFilter::ReadFilteredData(char* dest_buffer,
int* dest_len) {
int available_space = *dest_len;
*dest_len = 0; // Nothing output yet.
if (!dest_buffer || available_space <= 0)
return FILTER_ERROR;
char* dest_buffer_end = dest_buffer + available_space;
if (WAITING_FOR_DICTIONARY_SELECTION == decoding_status_) {
FilterStatus status = InitializeDictionary();
if (DECODING_IN_PROGRESS != decoding_status_) {
DCHECK(status == FILTER_ERROR || status == FILTER_NEED_MORE_DATA);
return status;
}
}
if (decoding_status_ != DECODING_IN_PROGRESS) {
decoding_status_ = DECODING_ERROR;
return FILTER_ERROR;
}
int amount = OutputBufferExcess(dest_buffer, available_space);
*dest_len += amount;
dest_buffer += amount;
available_space -= amount;
DCHECK(available_space >= 0);
if (available_space <= 0)
return FILTER_OK;
DCHECK(dest_buffer_excess_.empty());
if (!next_stream_data_ || stream_data_len_ <= 0)
return FILTER_NEED_MORE_DATA;
bool ret = vcdiff_streaming_decoder_->DecodeChunk(
next_stream_data_, stream_data_len_, &dest_buffer_excess_);
// Assume all data was used in decoding.
next_stream_data_ = NULL;
source_bytes_ += stream_data_len_;
stream_data_len_ = 0;
output_bytes_ += dest_buffer_excess_.size();
if (!ret) {
vcdiff_streaming_decoder_.reset(NULL); // Don't call it again.
decoding_status_ = DECODING_ERROR;
return FILTER_ERROR;
}
amount = OutputBufferExcess(dest_buffer, available_space);
*dest_len += amount;
dest_buffer += amount;
if (0 == available_space && !dest_buffer_excess_.empty())
return FILTER_OK;
return FILTER_NEED_MORE_DATA;
}
Filter::FilterStatus SdchFilter::InitializeDictionary() {
const size_t kServerIdLength = 9; // Dictionary hash plus null from server.
size_t bytes_needed = kServerIdLength - dictionary_hash_.size();
DCHECK(bytes_needed > 0);
if (!next_stream_data_)
return FILTER_NEED_MORE_DATA;
if (static_cast<size_t>(stream_data_len_) < bytes_needed) {
dictionary_hash_.append(next_stream_data_, stream_data_len_);
next_stream_data_ = NULL;
stream_data_len_ = 0;
return FILTER_NEED_MORE_DATA;
}
dictionary_hash_.append(next_stream_data_, bytes_needed);
DCHECK(kServerIdLength == dictionary_hash_.size());
stream_data_len_ -= bytes_needed;
DCHECK(0 <= stream_data_len_);
if (stream_data_len_ > 0)
next_stream_data_ += bytes_needed;
else
next_stream_data_ = NULL;
if ('\0' != dictionary_hash_[kServerIdLength - 1] ||
(kServerIdLength - 1) != strlen(dictionary_hash_.data())) {
decoding_status_ = DECODING_ERROR;
return FILTER_ERROR; // No dictionary hash.
}
dictionary_hash_.erase(kServerIdLength - 1);
DCHECK(!dictionary_);
SdchManager::Global()->GetVcdiffDictionary(dictionary_hash_, url(),
&dictionary_);
if (!dictionary_) {
decoding_status_ = DECODING_ERROR;
return FILTER_ERROR;
}
dictionary_->AddRef();
vcdiff_streaming_decoder_.reset(new open_vcdiff::VCDiffStreamingDecoder);
vcdiff_streaming_decoder_->StartDecoding(dictionary_->text().data(),
dictionary_->text().size());
decoding_status_ = DECODING_IN_PROGRESS;
return FILTER_OK;
}
int SdchFilter::OutputBufferExcess(char* const dest_buffer,
size_t available_space) {
if (dest_buffer_excess_.empty())
return 0;
DCHECK(dest_buffer_excess_.size() > dest_buffer_excess_index_);
size_t amount = std::min(available_space,
dest_buffer_excess_.size() - dest_buffer_excess_index_);
memcpy(dest_buffer, dest_buffer_excess_.data() + dest_buffer_excess_index_,
amount);
dest_buffer_excess_index_ += amount;
if (dest_buffer_excess_.size() <= dest_buffer_excess_index_) {
DCHECK(dest_buffer_excess_.size() == dest_buffer_excess_index_);
dest_buffer_excess_.clear();
dest_buffer_excess_index_ = 0;
}
return amount;
}
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