/* Signal Handlers that Return

   Copyright (C) 1991-2018 Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or

   modify it under the terms of the GNU General Public License

   as published by the Free Software Foundation; either version 2

   of the License, or (at your option) any later version.

   This program is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License

   along with this program; if not, if not, see <http://www.gnu.org/licenses/>.

*/

#include <signal.h>

#include <stdio.h>

#include <stdlib.h>

/* This flag controls termination of the main loop. */

volatile sig_atomic_t keep_going = 1;

/* The signal handler just clears the flag and re-enables itself. */

void

catch_alarm (int sig)

{

  keep_going = 0;

  signal (sig, catch_alarm);

}

void

do_stuff (void)

{

  puts ("Doing stuff while waiting for alarm....");

}

int

main (void)

{

  /* Establish a handler for SIGALRM signals. */

  signal (SIGALRM, catch_alarm);

  /* Set an alarm to go off in a little while. */

  alarm (2);

  /* Check the flag once in a while to see when to quit. */

  while (keep_going)

    do_stuff ();

  return EXIT_SUCCESS;

}