C语言获取设备开机时间

#include 
#include 
#include 
#include 
#include 
#include 
#include 

int getBootTimeAlarm();

extern "C" JNIEXPORT jstring JNICALL
Java_com_android_cpptest_MainActivity_stringFromJNI(
        JNIEnv* env,
        jobject /* this */) {
    int startMSCount;//从开机到现在的毫秒数
    startMSCount = getBootTimeAlarm();
    time_t CurSysTime, BootSysTime;
    time(&CurSysTime);
    //将开机到现在的毫秒数转换为秒数，再用当前的时间减去，获得开机时间
    BootSysTime = CurSysTime - startMSCount / 1000;
    struct tm* tm_boot;
    tm_boot = localtime(&BootSysTime);
    char bufbt[128] = { 0 };
    strftime(bufbt, 64, "%Y-%m-%d %H:%M:%S", tm_boot);
    return env->NewStringUTF(bufbt);
}

int getBootTimeAlarm() {
    timespec ts{};
    if (clock_gettime(CLOCK_BOOTTIME_ALARM, &ts) == 0) {
        return ts.tv_sec * 1000 + ts.tv_nsec / 1000000;  // 转换为毫秒
    } else {
        return -1;  // 出错返回-1
    }
}