mirror of
https://github.com/google/brotli.git
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666 lines
24 KiB
C++
666 lines
24 KiB
C++
// Copyright 2013 Google Inc. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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// Implementation of Brotli compressor.
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#include "./encode.h"
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#include <algorithm>
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#include <limits>
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#include "./backward_references.h"
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#include "./bit_cost.h"
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#include "./block_splitter.h"
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#include "./brotli_bit_stream.h"
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#include "./cluster.h"
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#include "./context.h"
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#include "./metablock.h"
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#include "./transform.h"
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#include "./entropy_encode.h"
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#include "./fast_log.h"
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#include "./hash.h"
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#include "./histogram.h"
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#include "./literal_cost.h"
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#include "./prefix.h"
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#include "./write_bits.h"
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namespace brotli {
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static const double kMinUTF8Ratio = 0.75;
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static const int kMinQualityForBlockSplit = 4;
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static const int kMinQualityForContextModeling = 5;
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static const int kMinQualityForOptimizeHistograms = 4;
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int ParseAsUTF8(int* symbol, const uint8_t* input, int size) {
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// ASCII
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if ((input[0] & 0x80) == 0) {
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*symbol = input[0];
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if (*symbol > 0) {
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return 1;
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}
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}
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// 2-byte UTF8
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if (size > 1 &&
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(input[0] & 0xe0) == 0xc0 &&
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(input[1] & 0xc0) == 0x80) {
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*symbol = (((input[0] & 0x1f) << 6) |
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(input[1] & 0x3f));
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if (*symbol > 0x7f) {
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return 2;
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}
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}
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// 3-byte UFT8
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if (size > 2 &&
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(input[0] & 0xf0) == 0xe0 &&
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(input[1] & 0xc0) == 0x80 &&
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(input[2] & 0xc0) == 0x80) {
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*symbol = (((input[0] & 0x0f) << 12) |
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((input[1] & 0x3f) << 6) |
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(input[2] & 0x3f));
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if (*symbol > 0x7ff) {
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return 3;
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}
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}
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// 4-byte UFT8
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if (size > 3 &&
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(input[0] & 0xf8) == 0xf0 &&
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(input[1] & 0xc0) == 0x80 &&
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(input[2] & 0xc0) == 0x80 &&
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(input[3] & 0xc0) == 0x80) {
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*symbol = (((input[0] & 0x07) << 18) |
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((input[1] & 0x3f) << 12) |
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((input[2] & 0x3f) << 6) |
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(input[3] & 0x3f));
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if (*symbol > 0xffff && *symbol <= 0x10ffff) {
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return 4;
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}
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}
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// Not UTF8, emit a special symbol above the UTF8-code space
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*symbol = 0x110000 | input[0];
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return 1;
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}
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// Returns true if at least min_fraction of the data is UTF8-encoded.
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bool IsMostlyUTF8(const uint8_t* data, size_t length, double min_fraction) {
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size_t size_utf8 = 0;
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size_t pos = 0;
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while (pos < length) {
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int symbol;
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int bytes_read = ParseAsUTF8(&symbol, data + pos, length - pos);
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pos += bytes_read;
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if (symbol < 0x110000) size_utf8 += bytes_read;
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}
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return size_utf8 > min_fraction * length;
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}
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void RecomputeDistancePrefixes(Command* cmds,
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size_t num_commands,
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int num_direct_distance_codes,
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int distance_postfix_bits) {
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if (num_direct_distance_codes == 0 &&
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distance_postfix_bits == 0) {
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return;
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}
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for (int i = 0; i < num_commands; ++i) {
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Command* cmd = &cmds[i];
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if (cmd->copy_len_ > 0 && cmd->cmd_prefix_ >= 128) {
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PrefixEncodeCopyDistance(cmd->DistanceCode(),
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num_direct_distance_codes,
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distance_postfix_bits,
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&cmd->dist_prefix_,
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&cmd->dist_extra_);
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}
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}
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}
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uint8_t* BrotliCompressor::GetBrotliStorage(size_t size) {
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if (storage_size_ < size) {
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storage_.reset(new uint8_t[size]);
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storage_size_ = size;
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}
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return &storage_[0];
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}
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BrotliCompressor::BrotliCompressor(BrotliParams params)
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: params_(params),
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hashers_(new Hashers()),
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input_pos_(0),
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num_commands_(0),
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num_literals_(0),
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last_insert_len_(0),
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last_flush_pos_(0),
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last_processed_pos_(0),
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prev_byte_(0),
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prev_byte2_(0),
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storage_size_(0) {
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// Sanitize params.
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params_.quality = std::max(1, params_.quality);
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if (params_.lgwin < kMinWindowBits) {
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params_.lgwin = kMinWindowBits;
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} else if (params_.lgwin > kMaxWindowBits) {
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params_.lgwin = kMaxWindowBits;
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}
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if (params_.lgblock == 0) {
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params_.lgblock = params_.quality < kMinQualityForBlockSplit ? 14 : 16;
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if (params_.quality >= 9 && params_.lgwin > params_.lgblock) {
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params_.lgblock = std::min(21, params_.lgwin);
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}
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} else {
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params_.lgblock = std::min(kMaxInputBlockBits,
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std::max(kMinInputBlockBits, params_.lgblock));
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}
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if (params_.quality <= 9) {
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params_.enable_dictionary = false;
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params_.enable_transforms = false;
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params_.greedy_block_split = true;
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params_.enable_context_modeling = false;
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}
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// Set maximum distance, see section 9.1. of the spec.
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max_backward_distance_ = (1 << params_.lgwin) - 16;
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// Initialize input and literal cost ring buffers.
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// We allocate at least lgwin + 1 bits for the ring buffer so that the newly
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// added block fits there completely and we still get lgwin bits and at least
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// read_block_size_bits + 1 bits because the copy tail length needs to be
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// smaller than ringbuffer size.
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int ringbuffer_bits = std::max(params_.lgwin + 1, params_.lgblock + 1);
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ringbuffer_.reset(new RingBuffer(ringbuffer_bits, params_.lgblock));
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if (params_.quality > 9) {
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literal_cost_mask_ = (1 << params_.lgblock) - 1;
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literal_cost_.reset(new float[literal_cost_mask_ + 1]);
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}
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// Allocate command buffer.
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cmd_buffer_size_ = std::max(1 << 18, 1 << params_.lgblock);
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commands_.reset(new brotli::Command[cmd_buffer_size_]);
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// Initialize last byte with stream header.
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if (params_.lgwin == 16) {
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last_byte_ = 0;
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last_byte_bits_ = 1;
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} else if (params_.lgwin == 17) {
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last_byte_ = 1;
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last_byte_bits_ = 7;
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} else {
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last_byte_ = ((params_.lgwin - 17) << 1) | 1;
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last_byte_bits_ = 4;
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}
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// Initialize distance cache.
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dist_cache_[0] = 4;
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dist_cache_[1] = 11;
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dist_cache_[2] = 15;
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dist_cache_[3] = 16;
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// Initialize hashers.
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if (params_.quality <= 9) {
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hash_type_ = params_.quality;
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} else {
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hash_type_ = 10;
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}
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hashers_->Init(hash_type_);
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if ((params_.mode == BrotliParams::MODE_GENERIC ||
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params_.mode == BrotliParams::MODE_TEXT) &&
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params_.enable_dictionary) {
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StoreDictionaryWordHashes(params_.enable_transforms);
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}
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}
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BrotliCompressor::~BrotliCompressor() {
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}
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StaticDictionary* BrotliCompressor::static_dictionary_ = NULL;
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void BrotliCompressor::StoreDictionaryWordHashes(bool enable_transforms) {
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if (static_dictionary_ == NULL) {
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static_dictionary_ = new StaticDictionary;
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static_dictionary_->Fill(enable_transforms);
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}
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hashers_->SetStaticDictionary(static_dictionary_);
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}
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void BrotliCompressor::CopyInputToRingBuffer(const size_t input_size,
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const uint8_t* input_buffer) {
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ringbuffer_->Write(input_buffer, input_size);
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input_pos_ += input_size;
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// Erase a few more bytes in the ring buffer to make hashing not
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// depend on uninitialized data. This makes compression deterministic
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// and it prevents uninitialized memory warnings in Valgrind. Even
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// without erasing, the output would be valid (but nondeterministic).
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//
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// Background information: The compressor stores short (at most 8 bytes)
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// substrings of the input already read in a hash table, and detects
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// repetitions by looking up such substrings in the hash table. If it
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// can find a substring, it checks whether the substring is really there
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// in the ring buffer (or it's just a hash collision). Should the hash
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// table become corrupt, this check makes sure that the output is
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// still valid, albeit the compression ratio would be bad.
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//
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// The compressor populates the hash table from the ring buffer as it's
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// reading new bytes from the input. However, at the last few indexes of
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// the ring buffer, there are not enough bytes to build full-length
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// substrings from. Since the hash table always contains full-length
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// substrings, we erase with dummy 0s here to make sure that those
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// substrings will contain 0s at the end instead of uninitialized
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// data.
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//
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// Please note that erasing is not necessary (because the
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// memory region is already initialized since he ring buffer
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// has a `tail' that holds a copy of the beginning,) so we
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// skip erasing if we have already gone around at least once in
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// the ring buffer.
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size_t pos = ringbuffer_->position();
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// Only clear during the first round of ringbuffer writes. On
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// subsequent rounds data in the ringbuffer would be affected.
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if (pos <= ringbuffer_->mask()) {
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// This is the first time when the ring buffer is being written.
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// We clear 3 bytes just after the bytes that have been copied from
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// the input buffer.
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//
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// The ringbuffer has a "tail" that holds a copy of the beginning,
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// but only once the ring buffer has been fully written once, i.e.,
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// pos <= mask. For the first time, we need to write values
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// in this tail (where index may be larger than mask), so that
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// we have exactly defined behavior and don't read un-initialized
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// memory. Due to performance reasons, hashing reads data using a
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// LOAD32, which can go 3 bytes beyond the bytes written in the
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// ringbuffer.
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memset(ringbuffer_->start() + pos, 0, 3);
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}
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}
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bool BrotliCompressor::WriteBrotliData(const bool is_last,
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const bool force_flush,
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size_t* out_size,
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uint8_t** output) {
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const size_t bytes = input_pos_ - last_processed_pos_;
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const uint8_t* data = ringbuffer_->start();
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const size_t mask = ringbuffer_->mask();
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if (bytes > input_block_size()) {
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return false;
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}
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bool utf8_mode =
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params_.enable_context_modeling &&
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IsMostlyUTF8(&data[last_processed_pos_ & mask], bytes, kMinUTF8Ratio);
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if (literal_cost_.get()) {
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if (utf8_mode) {
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EstimateBitCostsForLiteralsUTF8(last_processed_pos_, bytes, mask,
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literal_cost_mask_, data,
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literal_cost_.get());
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} else {
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EstimateBitCostsForLiterals(last_processed_pos_, bytes, mask,
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literal_cost_mask_,
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data, literal_cost_.get());
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}
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}
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double base_min_score = params_.enable_context_modeling ? 8.115 : 4.0;
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CreateBackwardReferences(bytes, last_processed_pos_, data, mask,
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literal_cost_.get(),
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literal_cost_mask_,
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max_backward_distance_,
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base_min_score,
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params_.quality,
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hashers_.get(),
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hash_type_,
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dist_cache_,
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&last_insert_len_,
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&commands_[num_commands_],
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&num_commands_,
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&num_literals_);
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// For quality 1 there is no block splitting, so we buffer at most this much
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// literals and commands.
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static const int kMaxNumDelayedSymbols = 0x2fff;
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if (!is_last && !force_flush &&
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(params_.quality >= kMinQualityForBlockSplit ||
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(num_literals_ + num_commands_ < kMaxNumDelayedSymbols)) &&
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num_commands_ + (input_block_size() >> 1) < cmd_buffer_size_ &&
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input_pos_ + input_block_size() <= last_flush_pos_ + mask + 1) {
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// Everything will happen later.
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last_processed_pos_ = input_pos_;
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*out_size = 0;
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return true;
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}
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// Create the last insert-only command.
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if (last_insert_len_ > 0) {
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brotli::Command cmd(last_insert_len_);
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commands_[num_commands_++] = cmd;
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num_literals_ += last_insert_len_;
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last_insert_len_ = 0;
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}
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return WriteMetaBlockInternal(is_last, utf8_mode, out_size, output);
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}
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void DecideOverLiteralContextModeling(const uint8_t* input,
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size_t start_pos,
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size_t length,
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size_t mask,
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int quality,
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int* literal_context_mode,
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int* num_literal_contexts,
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const int** literal_context_map) {
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if (quality < kMinQualityForContextModeling || length < 64) {
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return;
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}
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// Simple heuristics to guess if the data is UTF8 or not. The goal is to
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// recognize non-UTF8 data quickly by searching for the following obvious
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// violations: a continuation byte following an ASCII byte or an ASCII or
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// lead byte following a lead byte. If we find such violation we decide that
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// the data is not UTF8. To make the analysis of UTF8 data faster we only
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// examine 64 byte long strides at every 4kB intervals, if there are no
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// violations found, we assume the whole data is UTF8.
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const size_t end_pos = start_pos + length;
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for (; start_pos + 64 < end_pos; start_pos += 4096) {
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const size_t stride_end_pos = start_pos + 64;
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uint8_t prev = input[start_pos & mask];
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for (size_t pos = start_pos + 1; pos < stride_end_pos; ++pos) {
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const uint8_t literal = input[pos & mask];
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if ((prev < 128 && (literal & 0xc0) == 0x80) ||
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(prev >= 192 && (literal & 0xc0) != 0x80)) {
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return;
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}
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prev = literal;
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}
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}
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*literal_context_mode = CONTEXT_UTF8;
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// If the data is UTF8, this static context map distinguishes between ASCII
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// or lead bytes and continuation bytes: the UTF8 context value based on the
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// last two bytes is 2 or 3 if and only if the next byte is a continuation
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// byte (see table in context.h).
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static const int kStaticContextMap[64] = {
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0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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};
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static const int kNumLiteralContexts = 2;
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*num_literal_contexts = kNumLiteralContexts;
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*literal_context_map = kStaticContextMap;
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}
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bool BrotliCompressor::WriteMetaBlockInternal(const bool is_last,
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const bool utf8_mode,
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size_t* out_size,
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uint8_t** output) {
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const size_t bytes = input_pos_ - last_flush_pos_;
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const uint8_t* data = ringbuffer_->start();
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const size_t mask = ringbuffer_->mask();
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const size_t max_out_size = 2 * bytes + 500;
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uint8_t* storage = GetBrotliStorage(max_out_size);
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storage[0] = last_byte_;
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int storage_ix = last_byte_bits_;
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bool uncompressed = false;
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if (num_commands_ < (bytes >> 8) + 2) {
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if (num_literals_ > 0.99 * bytes) {
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int literal_histo[256] = { 0 };
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static const int kSampleRate = 13;
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static const double kMinEntropy = 7.92;
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static const double kBitCostThreshold = bytes * kMinEntropy / kSampleRate;
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for (int i = last_flush_pos_; i < input_pos_; i += kSampleRate) {
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++literal_histo[data[i & mask]];
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}
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if (BitsEntropy(literal_histo, 256) > kBitCostThreshold) {
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uncompressed = true;
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}
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}
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}
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if (bytes == 0) {
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if (!StoreCompressedMetaBlockHeader(is_last, 0, &storage_ix, &storage[0])) {
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return false;
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}
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storage_ix = (storage_ix + 7) & ~7;
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} else if (uncompressed) {
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if (!StoreUncompressedMetaBlock(is_last,
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data, last_flush_pos_, mask, bytes,
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&storage_ix,
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&storage[0])) {
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return false;
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}
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} else {
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// Save the state of the distance cache in case we need to restore it for
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// emitting an uncompressed block.
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int saved_dist_cache[4];
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memcpy(saved_dist_cache, dist_cache_, sizeof(dist_cache_));
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int num_direct_distance_codes = 0;
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int distance_postfix_bits = 0;
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if (params_.quality > 9 && params_.mode == BrotliParams::MODE_FONT) {
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num_direct_distance_codes = 12;
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distance_postfix_bits = 1;
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RecomputeDistancePrefixes(commands_.get(),
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num_commands_,
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num_direct_distance_codes,
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distance_postfix_bits);
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}
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if (params_.quality < kMinQualityForBlockSplit) {
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if (!StoreMetaBlockTrivial(data, last_flush_pos_, bytes, mask, is_last,
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commands_.get(), num_commands_,
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&storage_ix,
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&storage[0])) {
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return false;
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}
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} else {
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MetaBlockSplit mb;
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int literal_context_mode = utf8_mode ? CONTEXT_UTF8 : CONTEXT_SIGNED;
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if (params_.greedy_block_split) {
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int num_literal_contexts = 1;
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const int* literal_context_map = NULL;
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DecideOverLiteralContextModeling(data, last_flush_pos_, bytes, mask,
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params_.quality,
|
|
&literal_context_mode,
|
|
&num_literal_contexts,
|
|
&literal_context_map);
|
|
if (literal_context_map == NULL) {
|
|
BuildMetaBlockGreedy(data, last_flush_pos_, mask,
|
|
commands_.get(), num_commands_,
|
|
&mb);
|
|
} else {
|
|
BuildMetaBlockGreedyWithContexts(data, last_flush_pos_, mask,
|
|
prev_byte_, prev_byte2_,
|
|
literal_context_mode,
|
|
num_literal_contexts,
|
|
literal_context_map,
|
|
commands_.get(), num_commands_,
|
|
&mb);
|
|
}
|
|
} else {
|
|
BuildMetaBlock(data, last_flush_pos_, mask,
|
|
prev_byte_, prev_byte2_,
|
|
commands_.get(), num_commands_,
|
|
literal_context_mode,
|
|
params_.enable_context_modeling,
|
|
&mb);
|
|
}
|
|
if (params_.quality >= kMinQualityForOptimizeHistograms) {
|
|
OptimizeHistograms(num_direct_distance_codes,
|
|
distance_postfix_bits,
|
|
&mb);
|
|
}
|
|
if (!StoreMetaBlock(data, last_flush_pos_, bytes, mask,
|
|
prev_byte_, prev_byte2_,
|
|
is_last,
|
|
num_direct_distance_codes,
|
|
distance_postfix_bits,
|
|
literal_context_mode,
|
|
commands_.get(), num_commands_,
|
|
mb,
|
|
&storage_ix,
|
|
&storage[0])) {
|
|
return false;
|
|
}
|
|
}
|
|
if (bytes + 4 < (storage_ix >> 3)) {
|
|
// Restore the distance cache and last byte.
|
|
memcpy(dist_cache_, saved_dist_cache, sizeof(dist_cache_));
|
|
storage[0] = last_byte_;
|
|
storage_ix = last_byte_bits_;
|
|
if (!StoreUncompressedMetaBlock(is_last, data, last_flush_pos_, mask,
|
|
bytes, &storage_ix, &storage[0])) {
|
|
return false;
|
|
}
|
|
}
|
|
}
|
|
last_byte_ = storage[storage_ix >> 3];
|
|
last_byte_bits_ = storage_ix & 7;
|
|
last_flush_pos_ = input_pos_;
|
|
last_processed_pos_ = input_pos_;
|
|
prev_byte_ = data[(last_flush_pos_ - 1) & mask];
|
|
prev_byte2_ = data[(last_flush_pos_ - 2) & mask];
|
|
num_commands_ = 0;
|
|
num_literals_ = 0;
|
|
*output = &storage[0];
|
|
*out_size = storage_ix >> 3;
|
|
return true;
|
|
}
|
|
|
|
bool BrotliCompressor::WriteMetaBlock(const size_t input_size,
|
|
const uint8_t* input_buffer,
|
|
const bool is_last,
|
|
size_t* encoded_size,
|
|
uint8_t* encoded_buffer) {
|
|
CopyInputToRingBuffer(input_size, input_buffer);
|
|
size_t out_size = 0;
|
|
uint8_t* output;
|
|
if (!WriteBrotliData(is_last, /* force_flush = */ true, &out_size, &output) ||
|
|
out_size > *encoded_size) {
|
|
return false;
|
|
}
|
|
if (out_size > 0) {
|
|
memcpy(encoded_buffer, output, out_size);
|
|
}
|
|
*encoded_size = out_size;
|
|
return true;
|
|
}
|
|
|
|
bool BrotliCompressor::WriteMetadata(const size_t input_size,
|
|
const uint8_t* input_buffer,
|
|
const bool is_last,
|
|
size_t* encoded_size,
|
|
uint8_t* encoded_buffer) {
|
|
if (input_size > (1 << 24) || input_size + 6 > *encoded_size) {
|
|
return false;
|
|
}
|
|
int storage_ix = last_byte_bits_;
|
|
encoded_buffer[0] = last_byte_;
|
|
WriteBits(1, 0, &storage_ix, encoded_buffer);
|
|
WriteBits(2, 3, &storage_ix, encoded_buffer);
|
|
WriteBits(1, 0, &storage_ix, encoded_buffer);
|
|
if (input_size == 0) {
|
|
WriteBits(2, 0, &storage_ix, encoded_buffer);
|
|
*encoded_size = (storage_ix + 7) >> 3;
|
|
} else {
|
|
size_t nbits = Log2Floor(input_size - 1) + 1;
|
|
size_t nbytes = (nbits + 7) / 8;
|
|
WriteBits(2, nbytes, &storage_ix, encoded_buffer);
|
|
WriteBits(8 * nbytes, input_size - 1, &storage_ix, encoded_buffer);
|
|
size_t hdr_size = (storage_ix + 7) >> 3;
|
|
memcpy(&encoded_buffer[hdr_size], input_buffer, input_size);
|
|
*encoded_size = hdr_size + input_size;
|
|
}
|
|
if (is_last) {
|
|
encoded_buffer[(*encoded_size)++] = 3;
|
|
}
|
|
last_byte_ = 0;
|
|
last_byte_bits_ = 0;
|
|
return true;
|
|
}
|
|
|
|
bool BrotliCompressor::FinishStream(
|
|
size_t* encoded_size, uint8_t* encoded_buffer) {
|
|
return WriteMetaBlock(0, NULL, true, encoded_size, encoded_buffer);
|
|
}
|
|
|
|
int BrotliCompressBuffer(BrotliParams params,
|
|
size_t input_size,
|
|
const uint8_t* input_buffer,
|
|
size_t* encoded_size,
|
|
uint8_t* encoded_buffer) {
|
|
if (*encoded_size == 0) {
|
|
// Output buffer needs at least one byte.
|
|
return 0;
|
|
}
|
|
BrotliCompressor compressor(params);
|
|
BrotliMemIn in(input_buffer, input_size);
|
|
BrotliMemOut out(encoded_buffer, *encoded_size);
|
|
if (!BrotliCompress(params, &in, &out)) {
|
|
return 0;
|
|
}
|
|
*encoded_size = out.position();
|
|
return 1;
|
|
}
|
|
|
|
size_t CopyOneBlockToRingBuffer(BrotliIn* r, BrotliCompressor* compressor) {
|
|
const size_t block_size = compressor->input_block_size();
|
|
size_t bytes_read = 0;
|
|
const uint8_t* data = reinterpret_cast<const uint8_t*>(
|
|
r->Read(block_size, &bytes_read));
|
|
if (data == NULL) {
|
|
return 0;
|
|
}
|
|
compressor->CopyInputToRingBuffer(bytes_read, data);
|
|
|
|
// Read more bytes until block_size is filled or an EOF (data == NULL) is
|
|
// received. This is useful to get deterministic compressed output for the
|
|
// same input no matter how r->Read splits the input to chunks.
|
|
for (size_t remaining = block_size - bytes_read; remaining > 0; ) {
|
|
size_t more_bytes_read = 0;
|
|
data = reinterpret_cast<const uint8_t*>(
|
|
r->Read(remaining, &more_bytes_read));
|
|
if (data == NULL) {
|
|
break;
|
|
}
|
|
compressor->CopyInputToRingBuffer(more_bytes_read, data);
|
|
bytes_read += more_bytes_read;
|
|
remaining -= more_bytes_read;
|
|
}
|
|
return bytes_read;
|
|
}
|
|
|
|
bool BrotliInIsFinished(BrotliIn* r) {
|
|
size_t read_bytes;
|
|
return r->Read(0, &read_bytes) == NULL;
|
|
}
|
|
|
|
int BrotliCompress(BrotliParams params, BrotliIn* in, BrotliOut* out) {
|
|
size_t in_bytes = 0;
|
|
size_t out_bytes = 0;
|
|
uint8_t* output;
|
|
bool final_block = false;
|
|
BrotliCompressor compressor(params);
|
|
while (!final_block) {
|
|
in_bytes = CopyOneBlockToRingBuffer(in, &compressor);
|
|
final_block = in_bytes == 0 || BrotliInIsFinished(in);
|
|
out_bytes = 0;
|
|
if (!compressor.WriteBrotliData(final_block,
|
|
/* force_flush = */ false,
|
|
&out_bytes, &output)) {
|
|
return false;
|
|
}
|
|
if (out_bytes > 0 && !out->Write(output, out_bytes)) {
|
|
return false;
|
|
}
|
|
}
|
|
return true;
|
|
}
|
|
|
|
} // namespace brotli
|