about summary refs log tree commit diff
path: root/manual/examples/sigh1.c
blob: 6d4a0752f3c6566737f0a5e3bfcf98dc67e9cd12 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
/* Signal Handlers that Return
   Copyright (C) 1991-2017 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;
}