#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <string.h>
#include <sys/time.h>

volatile sig_atomic_t alrm_count = 10;

void alrm(int signum)
{
        alrm_count--;
}

int main(void)
{
        struct sigaction sa_alarm;
        struct itimerval itimer;

        memset(&sa_alarm, 0, sizeof(sa_alarm));
        sa_alarm.sa_handler = alrm;
        sa_alarm.sa_flags = SA_RESTART;

        if (sigaction(SIGALRM, &sa_alarm, NULL) < 0) {
                perror("sigaction");
                exit(1);
        }

        itimer.it_value.tv_sec  = itimer.it_interval.tv_sec  = 1;
        itimer.it_value.tv_usec = itimer.it_interval.tv_usec = 0;

        if (setitimer(ITIMER_REAL, &itimer, NULL) < 0) {
                perror("setitimer");
                exit(1);
        }

        while (alrm_count) {
                pause();
                printf("%d: %ld\n", alrm_count, time(NULL));
        }

        itimer.it_value.tv_sec  = itimer.it_interval.tv_sec  = 0;
        itimer.it_value.tv_usec = itimer.it_interval.tv_usec = 0;

        if (setitimer(ITIMER_REAL, &itimer, NULL) < 0) {
                perror("setitimer");
                exit(1);
        }

        return 0;
}