lab3.c

As you have learnt that sleep( )/usleep()/nanosleep() are not good to delay a process. Timers can pr

#include <errno.h>
#include <signal.h>
#include <stdio.h>
#include <time.h>
#include <unistd.h>
#define BILLION 1000000000L

#include <sys/types.h>
#include <linux/limits.h>


struct alarm{
	time_t hour;
	time_t min;
	time_t sec;
};

  struct alarm beeper;	
struct tm *tnow;
struct sigaction act1;
/* ARGSUSED */
static void interrupt(int signo, siginfo_t *info, void *context) {

  
   time_t tcurrent2;
   tcurrent2=time(NULL);
   tnow=localtime(&tcurrent2);
   if(tnow->tm_hour==beeper.hour&&tnow->tm_min==beeper.min)
	   {
          if(tnow->tm_sec==beeper.sec||tnow->tm_sec==beeper.sec+1||tnow->tm_sec==beeper.sec+2||tnow->tm_sec==beeper.sec+3||tnow->tm_sec==beeper.sec+4||tnow->tm_sec==beeper.sec+5||tnow->tm_sec==beeper.sec+6||tnow->tm_sec==beeper.sec+7||tnow->tm_sec==beeper.sec+8||tnow->tm_sec==beeper.sec+9)
		   {
				printf("\n%d:%d:%d  \n",tnow->tm_hour,tnow->tm_min,tnow->tm_sec);
                printf("\n");
	            printf("%d:%d:%d  alarm on \n",beeper.hour,beeper.min,beeper.sec); 
		   }
	   else{
	            printf("\n%d:%d:%d  \n",tnow->tm_hour,tnow->tm_min,tnow->tm_sec);
                printf("%d:%d:%d  alarm time \n",beeper.hour,beeper.min,beeper.sec); 
           }
      }
   else{
	   printf("\n%d:%d:%d  \n",tnow->tm_hour,tnow->tm_min,tnow->tm_sec);
       printf("%d:%d:%d  alarm time \n",beeper.hour,beeper.min,beeper.sec); 
   }
}

static int setinterrupt() { 
   struct sigaction act;

   act.sa_flags = SA_SIGINFO;
   act.sa_sigaction = interrupt;
   if ((sigemptyset(&act.sa_mask) == -1) ||
       (sigaction(SIGALRM, &act, NULL) == -1))
      return -1;
   return 0;
}

void catchctrlc(int signo) {

    printf("\ntime :%d:%d:%d \n",tnow->tm_hour,tnow->tm_min,tnow->tm_sec);
    printf("alarm :%d:%d:%d \n",beeper.hour,beeper.min,beeper.sec); 

}

static int setcatchctrlc() { 
//struct sigaction act1;
act1.sa_handler = catchctrlc;
act1.sa_flags = 0;
if ((sigemptyset(&act1.sa_mask) == -1) ||
    (sigaction(SIGINT, &act1, NULL) == -1))
   perror("Failed to set SIGINT to handle Ctrl-C");
}

static int setperiodic(double sec) {
   timer_t timerid;
   struct itimerspec value;

   if (timer_create(CLOCK_REALTIME, NULL, &timerid) == -1)
      return -1;
   value.it_interval.tv_sec = (long)sec;
   value.it_interval.tv_nsec = (sec - value.it_interval.tv_sec)*BILLION;

   if (value.it_interval.tv_nsec >= BILLION) {
      value.it_interval.tv_sec++;
      value.it_interval.tv_nsec -= BILLION;
   }
   value.it_value = value.it_interval;
   return timer_settime(timerid, 0, &value, NULL);
}

int main(void) {


	  time_t tcurrent;

   tcurrent=time(NULL);
  
   printf("date/time now: %s", ctime(&tcurrent));
   printf("Enter alarm time: (hour, min, sec):");
   scanf("%d%d%d",&beeper.hour,&beeper.min,&beeper.sec); 
   if (setinterrupt() == -1) {
      perror("Failed to setup SIGALRM handler");
      return 1;
   }
   if (setcatchctrlc(1.0) == -1) {
      perror("Failed to setup ctrl-c interrupt");
      return 1;
   }
   if (setperiodic(1.0) == -1) {
      perror("Failed to setup periodic interrupt");
      return 1;
   }
   

   for ( ; ; )
      pause();
  
}