/*
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* Copyright (C) 2016 The Android Open Source Project
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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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#include <cinttypes>
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#include <cstring>
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#include "android-base/logging.h"
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#include "wifilogd/message_buffer.h"
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namespace android {
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namespace wifilogd {
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using local_utils::CopyFromBufferOrDie;
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MessageBuffer::MessageBuffer(size_t size)
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: data_(new uint8_t[size]), capacity_(size), read_pos_(0), write_pos_(0) {
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CHECK(size > GetHeaderSize());
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}
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bool MessageBuffer::Append(const uint8_t* message, uint16_t message_len) {
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CHECK(message_len);
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if (!CanFitNow(message_len)) {
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return false;
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}
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AppendHeader(message_len);
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AppendRawBytes(message, message_len);
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return true;
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}
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bool MessageBuffer::CanFitEver(uint16_t length) const {
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// This unusual formulation is intended to avoid overflow.
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return capacity_ - GetHeaderSize() >= length;
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}
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bool MessageBuffer::CanFitNow(uint16_t length) const {
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// This unusual formulation is intended to avoid overflow/underflow.
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return GetFreeSize() >= GetHeaderSize() &&
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GetFreeSize() - GetHeaderSize() >= length;
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}
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void MessageBuffer::Clear() {
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read_pos_ = 0;
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write_pos_ = 0;
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}
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std::tuple<const uint8_t*, size_t> MessageBuffer::ConsumeNextMessage() {
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if (read_pos_ == write_pos_) {
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return {nullptr, 0};
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}
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const auto& header = CopyFromBufferOrDie<LengthHeader>(
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data_.get() + read_pos_, GetReadableSize());
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read_pos_ += sizeof(header);
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const uint8_t* payload_start = data_.get() + read_pos_;
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read_pos_ += header.payload_len;
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CHECK(read_pos_ <= write_pos_);
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return {payload_start, header.payload_len};
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}
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void MessageBuffer::Rewind() { read_pos_ = 0; }
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// Private methods below.
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void MessageBuffer::AppendHeader(uint16_t message_len) {
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LengthHeader header;
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header.payload_len = message_len;
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AppendRawBytes(&header, sizeof(header));
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}
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void MessageBuffer::AppendRawBytes(const void* data_start, size_t data_len) {
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std::memcpy(data_.get() + write_pos_, data_start, data_len);
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write_pos_ += data_len;
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CHECK(write_pos_ <= capacity_);
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}
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} // namespace wifilogd
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} // namespace android
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