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/*
* Copyright (C) 2020 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#pragma once
#include <span>
#include <brotli/decode.h>
#include <brotli/encode.h>
#include "types.h"
enum class BrotliDecodeResult {
Error,
Done,
NeedInput,
MoreOutput,
};
struct BrotliDecoder {
explicit BrotliDecoder(std::span<char> output_buffer)
: output_buffer_(output_buffer),
decoder_(BrotliDecoderCreateInstance(nullptr, nullptr, nullptr),
BrotliDecoderDestroyInstance) {}
void Append(Block&& block) { input_buffer_.append(std::move(block)); }
BrotliDecodeResult Decode(std::span<char>* output) {
size_t available_in = input_buffer_.front_size();
const uint8_t* next_in = reinterpret_cast<const uint8_t*>(input_buffer_.front_data());
size_t available_out = output_buffer_.size();
uint8_t* next_out = reinterpret_cast<uint8_t*>(output_buffer_.data());
BrotliDecoderResult r = BrotliDecoderDecompressStream(
decoder_.get(), &available_in, &next_in, &available_out, &next_out, nullptr);
size_t bytes_consumed = input_buffer_.front_size() - available_in;
input_buffer_.drop_front(bytes_consumed);
size_t bytes_emitted = output_buffer_.size() - available_out;
*output = std::span<char>(output_buffer_.data(), bytes_emitted);
switch (r) {
case BROTLI_DECODER_RESULT_SUCCESS:
return BrotliDecodeResult::Done;
case BROTLI_DECODER_RESULT_ERROR:
return BrotliDecodeResult::Error;
case BROTLI_DECODER_RESULT_NEEDS_MORE_INPUT:
// Brotli guarantees as one of its invariants that if it returns NEEDS_MORE_INPUT,
// it will consume the entire input buffer passed in, so we don't have to worry
// about bytes left over in the front block with more input remaining.
return BrotliDecodeResult::NeedInput;
case BROTLI_DECODER_RESULT_NEEDS_MORE_OUTPUT:
return BrotliDecodeResult::MoreOutput;
}
}
private:
IOVector input_buffer_;
std::span<char> output_buffer_;
std::unique_ptr<BrotliDecoderState, void (*)(BrotliDecoderState*)> decoder_;
};
enum class BrotliEncodeResult {
Error,
Done,
NeedInput,
MoreOutput,
};
template <size_t OutputBlockSize>
struct BrotliEncoder {
explicit BrotliEncoder()
: output_block_(OutputBlockSize),
output_bytes_left_(OutputBlockSize),
encoder_(BrotliEncoderCreateInstance(nullptr, nullptr, nullptr),
BrotliEncoderDestroyInstance) {
BrotliEncoderSetParameter(encoder_.get(), BROTLI_PARAM_QUALITY, 1);
}
void Append(Block input) { input_buffer_.append(std::move(input)); }
void Finish() { finished_ = true; }
BrotliEncodeResult Encode(Block* output) {
output->clear();
while (true) {
size_t available_in = input_buffer_.front_size();
const uint8_t* next_in = reinterpret_cast<const uint8_t*>(input_buffer_.front_data());
size_t available_out = output_bytes_left_;
uint8_t* next_out = reinterpret_cast<uint8_t*>(output_block_.data() +
(OutputBlockSize - output_bytes_left_));
BrotliEncoderOperation op = BROTLI_OPERATION_PROCESS;
if (finished_) {
op = BROTLI_OPERATION_FINISH;
}
if (!BrotliEncoderCompressStream(encoder_.get(), op, &available_in, &next_in,
&available_out, &next_out, nullptr)) {
return BrotliEncodeResult::Error;
}
size_t bytes_consumed = input_buffer_.front_size() - available_in;
input_buffer_.drop_front(bytes_consumed);
output_bytes_left_ = available_out;
if (BrotliEncoderIsFinished(encoder_.get())) {
output_block_.resize(OutputBlockSize - output_bytes_left_);
*output = std::move(output_block_);
return BrotliEncodeResult::Done;
} else if (output_bytes_left_ == 0) {
*output = std::move(output_block_);
output_block_.resize(OutputBlockSize);
output_bytes_left_ = OutputBlockSize;
return BrotliEncodeResult::MoreOutput;
} else if (input_buffer_.empty()) {
return BrotliEncodeResult::NeedInput;
}
}
}
private:
bool finished_ = false;
IOVector input_buffer_;
Block output_block_;
size_t output_bytes_left_;
std::unique_ptr<BrotliEncoderState, void (*)(BrotliEncoderState*)> encoder_;
};
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