/* set_time.c - save/restore system time based on mtime of current program file
 *
 * Based on fake-hwclock.c by Xan Manning from
 * https://github.com/xanmanning/alarm-fake-hwclock/fake-hwclock.c
 *
 * Original license:
 * -----------------------------------------------------------------------------
 * "THE (COFFEE)WARE LICENSE" (Rev. 1):
 * 
 * <xan.manning@gmail.com> 
 * wrote this file. As long as you retain this notice you can do whatever you
 * want with this stuff. If we meet some day, and you think this stuff is
 * worth it, you can buy me the above drink(s) in return.
 *
 * Xan Manning
 * ----------------------------------------------------------------------------- 
 */

#include <stdio.h>
#include <time.h>
#include <utime.h>
#include <sys/stat.h>
#include <sys/time.h>

int main(int argc, char *argv[])
{
	struct stat sb;
	time_t current_time;

	current_time = time(NULL);
	if (current_time == (time_t)-1) {
		fprintf(stderr, "failed to get current time\n");
		return 1;
	}

	if (stat(argv[0], &sb) == -1) {
		fprintf(stderr, "stat failed: %s\n", argv[0]);
		return 1;
	}

	if (current_time > sb.st_mtime) {
		struct utimbuf utb = { current_time, current_time };
		if (utime(argv[0], &utb) == -1) {
			fprintf(stderr, "utime failed\n");
			return 1;
		}
		printf("Current time saved\n");
	}
	else {
		struct timespec ts = { current_time + 2, 0 };
		if (clock_settime(CLOCK_REALTIME, &ts) == -1) {
			fprintf(stderr, "clock_settime failed\n");
			return 1;
		}
		printf("System time set\n");
	}

	return 0;
}