#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <semaphore.h>
#include <time.h>
#include <assert.h>
#include <errno.h>
#include <signal.h>

sem_t sem;

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

static void
handler(int sig)
{
  puts("sig handler\n");
  // write(STDOUT_FILENO, "sem_post() from handler\n", 24);
  // if (sem_post(&sem) == -1)
  // {
  //   write(STDERR_FILENO, "sem_post() failed\n", 18);
  //   _exit(EXIT_FAILURE);
  // }
}

int
main(int argc, char *argv[])
{
  struct sigaction sa;
  struct timespec ts;
  int s;

 


  if (sem_init(&sem, 0, 0) == -1)
    handle_error("sem_init");

  /* Establish SIGALRM handler; set alarm timer using argv[1] */

  sa.sa_handler = handler;
  sigemptyset(&sa.sa_mask);
  sa.sa_flags = 0;
  if (sigaction(SIGINT, &sa, NULL) == -1)
    handle_error("sigaction");

 

  /* Calculate relative interval as current time plus
     number of seconds given argv[2] */

  if (clock_gettime(CLOCK_REALTIME, &ts) == -1)
    handle_error("clock_gettime");

  ts.tv_sec += atoi(argv[2]);

  printf("main() about to call sem_wait()\n");
  while ((s = sem_wait(&sem)) == -1 )
    printf("%d , %d\n", errno, errno == EINTR);


 
}