// Copyright 2017 The Chromium OS Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "puffin/src/puff_reader.h"
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#include <algorithm>
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#include <memory>
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#include <string>
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#include <vector>
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#include "puffin/src/logging.h"
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namespace puffin {
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namespace {
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// Reads a value from the buffer in big-endian mode.
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inline uint16_t ReadByteArrayToUint16(const uint8_t* buffer) {
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return (*buffer << 8) | *(buffer + 1);
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}
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} // namespace
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bool BufferPuffReader::GetNext(PuffData* data) {
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PuffData& pd = *data;
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size_t length = 0;
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if (state_ == State::kReadingLenDist) {
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// Boundary check
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TEST_AND_RETURN_FALSE(index_ < puff_size_);
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if (puff_buf_in_[index_] & 0x80) { // Reading length/distance.
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if ((puff_buf_in_[index_] & 0x7F) < 127) {
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length = puff_buf_in_[index_] & 0x7F;
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} else {
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index_++;
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// Boundary check
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TEST_AND_RETURN_FALSE(index_ < puff_size_);
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length = puff_buf_in_[index_] + 127;
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}
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length += 3;
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TEST_AND_RETURN_FALSE(length <= 259);
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index_++;
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// End of block. End of block is similar to length/distance but without
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// distance value and length value set to 259.
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if (length == 259) {
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pd.type = PuffData::Type::kEndOfBlock;
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state_ = State::kReadingBlockMetadata;
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DVLOG(2) << "Read end of block";
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return true;
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}
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// Boundary check
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TEST_AND_RETURN_FALSE(index_ + 1 < puff_size_);
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auto distance = ReadByteArrayToUint16(&puff_buf_in_[index_]);
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// The distance in RFC is in the range [1..32768], but in the puff spec,
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// we write zero-based distance in the puff stream.
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TEST_AND_RETURN_FALSE(distance < (1 << 15));
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distance++;
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index_ += 2;
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pd.type = PuffData::Type::kLenDist;
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pd.length = length;
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pd.distance = distance;
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DVLOG(2) << "Read length: " << length << " distance: " << distance;
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return true;
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} else { // Reading literals.
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// Boundary check
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TEST_AND_RETURN_FALSE(index_ < puff_size_);
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if ((puff_buf_in_[index_] & 0x7F) < 127) {
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length = puff_buf_in_[index_] & 0x7F;
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index_++;
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} else {
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index_++;
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// Boundary check
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TEST_AND_RETURN_FALSE(index_ + 1 < puff_size_);
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length = ReadByteArrayToUint16(&puff_buf_in_[index_]) + 127;
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index_ += 2;
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}
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length++;
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DVLOG(2) << "Read literals length: " << length;
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// Boundary check
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TEST_AND_RETURN_FALSE(index_ + length <= puff_size_);
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pd.type = PuffData::Type::kLiterals;
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pd.length = length;
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pd.read_fn = [this, length](uint8_t* buffer, size_t count) mutable {
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TEST_AND_RETURN_FALSE(count <= length);
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memcpy(buffer, &puff_buf_in_[index_], count);
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index_ += count;
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length -= count;
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return true;
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};
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return true;
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}
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} else { // Block metadata
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pd.type = PuffData::Type::kBlockMetadata;
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// Boundary check
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TEST_AND_RETURN_FALSE(index_ + 2 < puff_size_);
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length = ReadByteArrayToUint16(&puff_buf_in_[index_]) + 1;
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index_ += 2;
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DVLOG(2) << "Read block metadata length: " << length;
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// Boundary check
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TEST_AND_RETURN_FALSE(index_ + length <= puff_size_);
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TEST_AND_RETURN_FALSE(length <= sizeof(pd.block_metadata));
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memcpy(pd.block_metadata, &puff_buf_in_[index_], length);
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index_ += length;
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pd.length = length;
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state_ = State::kReadingLenDist;
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}
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return true;
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}
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size_t BufferPuffReader::BytesLeft() const {
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return puff_size_ - index_;
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}
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} // namespace puffin
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