gnss/common/utils/default/DeviceFileReader.cpp

/*
 * Copyright (C) 2021 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 "DeviceFileReader.h"

namespace android {
namespace hardware {
namespace gnss {
namespace common {

void DeviceFileReader::getDataFromDeviceFile(const std::string& command, int mMinIntervalMs) {
    char inputBuffer[INPUT_BUFFER_SIZE];
    int mGnssFd = open(ReplayUtils::getGnssPath().c_str(),
                       O_RDWR | O_NONBLOCK);

    if (mGnssFd == -1) {
        return;
    }

    int bytes_write = write(mGnssFd, command.c_str(), command.size());
    if (bytes_write <= 0) {
        close(mGnssFd);
        return;
    }

    struct epoll_event ev, events[1];
    ev.data.fd = mGnssFd;
    ev.events = EPOLLIN;
    int epoll_fd = epoll_create1(0);
    epoll_ctl(epoll_fd, EPOLL_CTL_ADD, mGnssFd, &ev);
    int bytes_read = -1;
    std::string inputStr = "";
    int epoll_ret = epoll_wait(epoll_fd, events, 1, mMinIntervalMs);

    if (epoll_ret == -1) {
        close(mGnssFd);
        return;
    }
    while (true) {
        memset(inputBuffer, 0, INPUT_BUFFER_SIZE);
        bytes_read = read(mGnssFd, &inputBuffer, INPUT_BUFFER_SIZE);
        if (bytes_read <= 0) {
            break;
        }
        s_buffer_ += std::string(inputBuffer, bytes_read);
    }
    close(mGnssFd);

    // Trim end of file mark(\n\n\n\n).
    auto pos = s_buffer_.find("\n\n\n\n");
    if (pos != std::string::npos) {
        inputStr = s_buffer_.substr(0, pos);
        s_buffer_ = s_buffer_.substr(pos + 4);
    } else {
        return;
    }

    // Cache the injected data.
    if (ReplayUtils::isGnssRawMeasurement(inputStr)) {
        data_[CMD_GET_RAWMEASUREMENT] = inputStr;
    } else if (ReplayUtils::isNMEA(inputStr)) {
        data_[CMD_GET_LOCATION] = inputStr;
    }
}

std::string DeviceFileReader::getLocationData() {
    std::unique_lock<std::mutex> lock(mMutex);
    getDataFromDeviceFile(CMD_GET_LOCATION, 20);
    return data_[CMD_GET_LOCATION];
}

std::string DeviceFileReader::getGnssRawMeasurementData() {
    std::unique_lock<std::mutex> lock(mMutex);
    getDataFromDeviceFile(CMD_GET_RAWMEASUREMENT, 20);
    return data_[CMD_GET_RAWMEASUREMENT];
}

DeviceFileReader::DeviceFileReader() {}

DeviceFileReader::~DeviceFileReader() {}

}  // namespace common
}  // namespace gnss
}  // namespace hardware
}  // namespace android