/* vim: set ts=4 sw=4: */
/* Filename    : rt_timer.c
 * Description : RT timer
 * Author      : Sun Young Kim <sunyzero@yahoo.com>
 * Notes       : 
 */
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <time.h>
#define SIGNO_RTTIMER	SIGRTMIN
#define GET_TIME0(a)	get_time0(a, sizeof(a)) == NULL ? "error" : a
inline char * get_time0(char *buf, size_t sz_buf);
int inst_timer(void);
void h_rt_timer(int signum, siginfo_t *si, void *sv);

int main(int argc, char *argv[])
{
	sigset_t	sigset_timer;
	if (inst_timer() == -1) {
		return EXIT_FAILURE;
	}
	sigemptyset(&sigset_timer);
	while (1) {
		sigsuspend(&sigset_timer);
	}
	return 0;
}

int inst_timer(void)
{
	struct sigaction sa_rt1;
	struct sigevent sigev;
	timer_t	rt_timer;
	struct itimerspec rt_itspec;
	char	ts_now[20];
	memset(&sa_rt1, 0, sizeof(sa_rt1));
	sigemptyset(&sa_rt1.sa_mask);
	sa_rt1.sa_sigaction = h_rt_timer; /* rt_timer handler */
	sa_rt1.sa_flags = SA_SIGINFO;
	if (sigaction(SIGNO_RTTIMER, &sa_rt1, NULL) == -1) {
		perror("FAIL: sigaction()");
		return -1;
	}
	sigev.sigev_notify = SIGEV_SIGNAL; /* RT signal notification */
	sigev.sigev_signo = SIGNO_RTTIMER;
	/* create timer */
	if (timer_create(CLOCK_REALTIME, &sigev, &rt_timer) == -1) {
		perror("FAIL: timer_create()");
		return -1;
	}
	rt_itspec.it_value.tv_sec = 2;
	rt_itspec.it_value.tv_nsec = 500000000;
	rt_itspec.it_interval.tv_sec = 4;
	rt_itspec.it_interval.tv_nsec = 0;
	printf("Enable timer at %s.\n", GET_TIME0(ts_now));
	if (timer_settime(rt_timer, 0, &rt_itspec, NULL) == -1) {
		perror("FAIL: timer_settime()");
		return -1;
	}
	return 0;
}

inline char * get_time0(char *buf, size_t sz_buf)
{
#define STR_TIME_FORMAT		"%H:%M:%S"
	struct timespec	tspec;
	struct tm	tm_now;
	if (buf == NULL) return NULL;
	if (clock_gettime(CLOCK_REALTIME, &tspec) == -1) {
		return buf;
	}
	localtime_r((time_t *)&tspec.tv_sec, &tm_now);
	if (strftime(buf, sz_buf, STR_TIME_FORMAT, &tm_now) == 0) {
		return buf;
	}
	return buf;
}

void h_rt_timer(int signum, siginfo_t *si, void *sv)
{
	char	ts_now[20];
	printf("-> RT timer expiration at %s\n", GET_TIME0(ts_now));
}