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

static int handler_run;
static const union sigval my_sigval = { .sival_int = 42, };

#define bail(msg) \
	do { perror(msg); exit(EXIT_FAILURE); } while (0);

static void handler(int sig, siginfo_t *si, void *notused)
{
	assert(si->si_code == SI_TIMER);
	assert(si->si_ptr == my_sigval.sival_ptr); /* Succeeds */
	assert(si->si_int == my_sigval.sival_int); /* Succeeds */

	/* This should run only once */
	assert(handler_run == 0);
	handler_run++;
}

int main(void)
{
	struct signalfd_siginfo fdsi;
	struct sigaction newact;
	struct itimerspec its;
	struct sigevent sev;
	timer_t timerid;
	sigset_t mask;
	ssize_t s;
	int sfd;

	newact.sa_flags = SA_SIGINFO | SA_RESETHAND;
	newact.sa_sigaction = handler;
	sigemptyset(&newact.sa_mask);

	if (sigaction(SIGRTMIN, &newact, NULL) == -1)
		bail("sigaction");

	memset(&sev, 0, sizeof(sev));
	sev.sigev_notify = SIGEV_SIGNAL;
	sev.sigev_signo = SIGRTMIN;
	sev.sigev_value = my_sigval;

	if (timer_create(CLOCK_REALTIME, &sev, &timerid) == -1)
		bail("timer_create");

	/* Timer expires just once */
	its.it_value.tv_sec = 0;
	its.it_value.tv_nsec = 100;
	its.it_interval.tv_sec = 0;
	its.it_interval.tv_nsec = 0;

	/* Arm timer */
	if (timer_settime(timerid, 0, &its, NULL) == -1)
                bail("timer_settime");

	/* Wait for timer to expire, which executes the handler */
	while (!handler_run)
		usleep(100000);

	/* Inhibit default SIGRTMIN handling */
	sigemptyset(&mask);
	sigaddset(&mask, SIGRTMIN);
	if (sigprocmask(SIG_BLOCK, &mask, NULL) == -1)
		bail("sigprocmask");

	sfd = signalfd(-1, &mask, 0);
	if (sfd == -1)
		bail("signalfd");

	/* Re-arm timer */
	if (timer_settime(timerid, 0, &its, NULL) == -1)
                bail("timer_settime");

	/* Block until timer expiration */
	s = read(sfd, &fdsi, sizeof(struct signalfd_siginfo));
	if (s != sizeof(struct signalfd_siginfo))
		bail("read");

	assert(fdsi.ssi_code == SI_TIMER);
	assert(fdsi.ssi_ptr ==
	       (unsigned long)my_sigval.sival_ptr); /* Succeeds */
	assert(fdsi.ssi_int == my_sigval.sival_int); /* Fails */

	return EXIT_SUCCESS;
}