/*      $OpenBSD: itimer.c,v 1.2 2013/09/12 23:06:44 krw Exp $  */
/*
 *      Written by Artur Grabowski <art@openbsd.org> 2004 Public Domain.
 */
#include <sys/types.h>
#include <sys/time.h>
#include <sys/resource.h>

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <time.h>
#include <err.h>
#include <signal.h>

void sighand(int);

volatile sig_atomic_t ticks;

#define TIMEOUT 2

int
main(int argc, char **argv)
{
        struct timeval stv, tv;
        struct itimerval itv;
        struct rusage ru;
        int which, sig;
        int ch;

        while ((ch = getopt(argc, argv, "rvp")) != -1) {
                switch (ch) {
                case 'r':
                        which = ITIMER_REAL;
                        sig = SIGALRM;
                        break;
                case 'v':
                        which = ITIMER_VIRTUAL;
                        sig = SIGVTALRM;
                        break;
                case 'p':
                        which = ITIMER_PROF;
                        sig = SIGPROF;
                        break;
                default:
                        fprintf(stderr, "Usage: itimer [-rvp]\n");
                        exit(1);
                }
        }

        signal(sig, sighand);

        itv.it_value.tv_sec = 0;
        itv.it_value.tv_usec = 100000;
        itv.it_interval = itv.it_value;

        if (setitimer(which, &itv, NULL) != 0)
                err(1, "setitimer");

        gettimeofday(&stv, NULL);
        while (ticks != TIMEOUT * 10)
                ;

        switch (which) {
        case ITIMER_REAL:
                gettimeofday(&tv, NULL);
                timersub(&tv, &stv, &tv);
                break;
        case ITIMER_VIRTUAL:
        case ITIMER_PROF:
                if (getrusage(RUSAGE_SELF, &ru) != 0)
                        err(1, "getrusage");
                tv = ru.ru_utime;
                break;
        }
        stv.tv_sec = TIMEOUT;
        stv.tv_usec = 0;

        if (timercmp(&stv, &tv, <))
                timersub(&tv, &stv, &tv);
        else
                timersub(&stv, &tv, &tv);

        if (tv.tv_sec != 0 || tv.tv_usec > 100000)
                errx(1, "timer difference too big: %lld.%ld",
                    (long long)tv.tv_sec, tv.tv_usec);

        return (0);
}

void
sighand(int signum)
{
        ticks++;
}