The getitimer function returns the current value for the timer
    specified by the which argument in the structure pointed to by
    value.

    A timer value is defined by the itimerval structure:

           struct itimerval {
                   struct  timeval it_interval;
                   struct  timeval it_value;
           };

    The following table lists the values for the itimerval structure
    members:

    itimerval Member
    Value              Meaning

    it_interval = 0    Disables a timer after its next expiration and
                       assumes it_value is nonzero.
    it_interval =      Specifies a value used in reloading it_value
    nonzero            when the timer expires.
    it_value = 0       Disables a timer.
    it_value =         Indicates the time to the next timer
    nonzero            expiration.

    Time values smaller than the resolution of the system clock are
    rounded up to this resolution.

    The C RTL provides each process with one interval timer,
    defined in the <time.h> header file as ITIMER_REAL. This timer
    decrements in real time and delivers a SIGALRM signal when the
    timer expires.