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