/*--------------------------------------------------------------------*/
/* testsignalignore.c                                                 */
/* Author: Bob Dondero                                                */
/*--------------------------------------------------------------------*/

#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <unistd.h>
#include <sys/types.h>   /* Required for splint. */

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

/* Demonstrate ignoring signals and restoring default signal behavior.
   As usual, argc is the command-line argument count, and argv contains
   the command-line arguments. The function never returns. */

int main(int argc, char *argv[])
{
   void (*pfRet)(int);
   sigset_t sSet;
   int iRet;

   /* Make sure SIGINT signals are not blocked. */
   iRet = sigemptyset(&sSet);
   if (iRet == -1) {perror(argv[0]); exit(EXIT_FAILURE); }
   iRet = sigaddset(&sSet, SIGINT);
   if (iRet == -1) {perror(argv[0]); exit(EXIT_FAILURE); }   
   iRet = sigprocmask(SIG_UNBLOCK, &sSet, NULL);
   if (iRet == -1) {perror(argv[0]); exit(EXIT_FAILURE); }

   /* Ignore SIGINT signals. */
   pfRet = signal(SIGINT, SIG_IGN);
   if (pfRet == SIG_ERR) {perror(argv[0]); exit(EXIT_FAILURE); }

   /* Sleep for a while. */
   printf("Going to sleep\n");
   fflush(stdout);
   sleep(5);
   printf("Waking up\n");
   fflush(stdout);
   
   /* Restore the default behavior for SIGINT signals. */
   pfRet = signal(SIGINT, SIG_DFL);
   if (pfRet == SIG_ERR) {perror(argv[0]); exit(EXIT_FAILURE); }  

   /* Enter an infinite loop. */
   printf("Entering an infinite loop\n");
   fflush(stdout);
   for (;;)
      sleep(1);
        
   /* Will not reach this point. */
}

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

/* Sample execution:

$ gcc217 testsignalignore.c -o testsignalignore

$ testsignalignore
Going to sleep
^C^C^C^C^C^C^C^CWaking up
Entering an infinite loop
^C

*/