/*-------------------------------------------------------------------*/
/* testalarm.c                                                       */
/* The alarm system call.                                            */
/*-------------------------------------------------------------------*/

#include <stdio.h>
#include <assert.h>
#include <signal.h>
#include <unistd.h>

/*-------------------------------------------------------------------*/

void mySignalHandler(int iSignal)

/* This function is intended to be a handler for signals of type 
   SIGALRM.  Print iSignal to stdout, re-register this function as the 
   handler for signals of type SIGALRM, and reset the alarm. */
 
{
   void (*pfRet)(int); 
   printf("In mySignalHandler with argument %d\n", iSignal);

   /* Re-register the signal handler. */
   pfRet = signal(SIGALRM, mySignalHandler);
   assert(pfRet != SIG_ERR);

   /* Reset the alarm. */
   alarm(3);
}

/*-------------------------------------------------------------------*/

int main(int argc, char *argv[])

/* Illustrate the alarm system call. */

{
   void (*pfRet)(int); 

   /* Register mySignalHandler as the  handler for SIGALRM signals. */
   pfRet = signal(SIGALRM, mySignalHandler);
   assert(pfRet != SIG_ERR);

   /* Set a 3 second alarm.  After 3 seconds of real time, send a 
   SIGALRM signal to this process. */
   alarm(3);

   printf("Entering an infinite loop\n");
   for (;;)
      ;

   return 0;
}


/* Sample execution:

$ gcc -Wall -ansi -pedantic -o testalarm testalarm.c
$ testalarm
Entering an infinite loop
In mySignalHandler with argument 14
In mySignalHandler with argument 14
In mySignalHandler with argument 14
...
^C

*/