/* 
  alarm2.c

  Just like alarm.c , but without the csapp wrappers,
  and with explicit C library headers instead.

  Note the use of "static" here. What does that do?

*/

#include <stdio.h>              /* printf */
#include <unistd.h>             /* alarm */
#include <stdlib.h>             /* exit */
#include <signal.h>             /* signal, SIGALRM */

void handler(int sig){
    static int beeps = 0;

    printf("BEEP\n");
    if (++beeps < 5){
	alarm(1);              /* Next SIGALRM will be delivered in 1 second */
    }
    else {
	printf("BOOM!\n");
	exit(0);
    }
}

int main(){
    signal(SIGALRM, handler);  /* install SIGALRM handler */
    alarm(1);                  /* Next SIGALRM will be delivered in 1s */

    while (1){
	;                   /* Signal handler returns control here each time */
    }
    exit(0);
}