workaround for clock_gettime in os x (mach)

current_utc_time.cpp

#include <time.h>
#include <sys/time.h>
#include <iostream>
#include <ostream>

// POSIX           Mach
// clock_gettime   clock_get_time
// CLOCK_REALTIME  CALENDAR_CLOCK
// CLOCK_MONOTONIC REALTIME_CLOCK

#ifdef __MACH__
#include <mach/clock.h>
#include <mach/mach.h>

timespec get_time()
{
    clock_serv_t cclock;
    mach_timespec_t mts;
    host_get_clock_service(mach_host_self(), CALENDAR_CLOCK, &cclock);
    clock_get_time(cclock, &mts);
    mach_port_deallocate(mach_task_self(), cclock);  // notice mach_task_self as opposed to mach_host_self

    timespec ts = {mts.tv_sec, mts.tv_nsec};
    return ts;
}

#else

timespec get_time()
{
    timespec ts;
    clock_gettime(CLOCK_REALTIME, &ts);
    return ts;
}

#endif

int main()
{
    using namespace std;

    timespec ts(get_time());
    cout << "seconds    : " << ts.tv_sec << endl
         << "nanoseconds: " << ts.tv_nsec << endl;
}