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

#define DEFAULT_LOOP 10

static int do_loop = 1;

void alarm_handler(int unused)
{
	do_loop = 0;
}

int main(int argc, char *argv[])
{
	struct timeval tv, last, diff;
	unsigned int timeout;

	if (argc == 2) {
		timeout = strtoul(argv[1], NULL, 10);
	} else if (argc == 1) {
		timeout = DEFAULT_LOOP;
	} else {
		fprintf(stderr, "Usage: %s [seconds]\n", argv[0]);
		return 1;
	}

	signal(SIGALRM, &alarm_handler);

	if (alarm(timeout) != 0)
		fprintf(stderr, "Warning, alarm(2) already set!\n");

	if (gettimeofday(&last, NULL) != 0) {
		perror("initial gettimeofday() failed:");
		return 1;
	}

	while(do_loop) {
		if (gettimeofday(&tv, NULL) != 0) {
			perror("loop gettimeofday() failed:");
			return 1;
		}

		timersub(&tv, &last, &diff);
		//printf("Diff of timers is %ld\n", diff.tv_usec);
#if 0
		if ((i + 1) % 1000000  == 0) {
			printf(".");
			fflush(stdout);
		}
#endif
		if (diff.tv_sec > 0) {
			fprintf(stderr, "Error: subsequent calls to gettimeofday() differed by %ld seconds\n",
					diff.tv_sec);
			return 1;
		}

		memcpy(&last, &tv, sizeof(last));
	}
	printf("\ncompleted successfully\n");

	return 0;
}