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579a7b498c
Bug: webrtc:14801 Change-Id: I7c14597e39b312c26573f034dca444cc1d90e332 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/295480 Commit-Queue: Philip Eliasson <philipel@webrtc.org> Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org> Reviewed-by: Björn Terelius <terelius@webrtc.org> Cr-Commit-Position: refs/heads/main@{#39449}
113 lines
3 KiB
C++
113 lines
3 KiB
C++
/*
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* Copyright (c) 2023 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include "logging/rtc_event_log/encoder/optional_blob_encoding.h"
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#include <cstdint>
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#include "rtc_base/bit_buffer.h"
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#include "rtc_base/bitstream_reader.h"
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#include "rtc_base/checks.h"
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#include "rtc_base/logging.h"
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namespace webrtc {
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std::string EncodeOptionalBlobs(
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const std::vector<absl::optional<std::string>>& blobs) {
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if (blobs.empty()) {
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return {};
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}
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size_t reserve_size_bits = 1;
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size_t num_blobs_present = 0;
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for (const auto& blob : blobs) {
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if (blob.has_value()) {
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++num_blobs_present;
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reserve_size_bits +=
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(rtc::BitBufferWriter::kMaxLeb128Length.bytes() + blob->size()) * 8;
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}
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}
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const bool all_blobs_present = num_blobs_present == blobs.size();
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if (!all_blobs_present) {
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reserve_size_bits += blobs.size();
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}
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std::vector<uint8_t> buffer((reserve_size_bits + 7) / 8);
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rtc::BitBufferWriter writer(buffer.data(), buffer.size());
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// Write present bits if all blobs are not present.
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writer.WriteBits(all_blobs_present, 1);
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if (!all_blobs_present) {
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for (const auto& blob : blobs) {
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writer.WriteBits(blob.has_value(), 1);
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}
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}
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// Byte align the writer.
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writer.ConsumeBits(writer.RemainingBitCount() % 8);
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// Write blobs.
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for (const auto& blob : blobs) {
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if (blob.has_value()) {
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writer.WriteLeb128(blob->length());
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writer.WriteString(*blob);
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}
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}
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size_t bytes_written;
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size_t bits_written;
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writer.GetCurrentOffset(&bytes_written, &bits_written);
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RTC_CHECK_EQ(bits_written, 0);
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RTC_CHECK_LE(bytes_written, buffer.size());
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return std::string(buffer.data(), buffer.data() + bytes_written);
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}
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std::vector<absl::optional<std::string>> DecodeOptionalBlobs(
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absl::string_view encoded_blobs,
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size_t num_of_blobs) {
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if (encoded_blobs.empty() || num_of_blobs == 0) {
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return {};
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}
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std::vector<absl::optional<std::string>> res(num_of_blobs);
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BitstreamReader reader(encoded_blobs);
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const bool all_blobs_present = reader.ReadBit();
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// Read present bits if all blobs are not present.
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std::vector<uint8_t> present;
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if (!all_blobs_present) {
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present.resize(num_of_blobs);
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for (size_t i = 0; i < num_of_blobs; ++i) {
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present[i] = reader.ReadBit();
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}
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}
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// Byte align the reader.
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reader.ConsumeBits(reader.RemainingBitCount() % 8);
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// Read the blobs.
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for (size_t i = 0; i < num_of_blobs; ++i) {
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if (!all_blobs_present && !present[i]) {
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continue;
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}
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res[i] = reader.ReadString(reader.ReadLeb128());
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}
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// The result is only valid if exactly all bits was consumed during decoding.
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if (!reader.Ok() || reader.RemainingBitCount() > 0) {
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return {};
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}
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return res;
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}
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} // namespace webrtc
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