1 | /* Signal Handlers that Return |
2 | Copyright (C) 1991-2024 Free Software Foundation, Inc. |
3 | |
4 | This program is free software; you can redistribute it and/or |
5 | modify it under the terms of the GNU General Public License |
6 | as published by the Free Software Foundation; either version 2 |
7 | of the License, or (at your option) any later version. |
8 | |
9 | This program is distributed in the hope that it will be useful, |
10 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
12 | GNU General Public License for more details. |
13 | |
14 | You should have received a copy of the GNU General Public License |
15 | along with this program; if not, see <https://www.gnu.org/licenses/>. |
16 | */ |
17 | |
18 | #include <signal.h> |
19 | #include <stdio.h> |
20 | #include <stdlib.h> |
21 | |
22 | /* This flag controls termination of the main loop. */ |
23 | volatile sig_atomic_t keep_going = 1; |
24 | |
25 | /* The signal handler just clears the flag and re-enables itself. */ |
26 | void |
27 | catch_alarm (int sig) |
28 | { |
29 | keep_going = 0; |
30 | signal (sig: sig, handler: catch_alarm); |
31 | } |
32 | |
33 | void |
34 | do_stuff (void) |
35 | { |
36 | puts (s: "Doing stuff while waiting for alarm...." ); |
37 | } |
38 | |
39 | int |
40 | main (void) |
41 | { |
42 | /* Establish a handler for SIGALRM signals. */ |
43 | signal (SIGALRM, handler: catch_alarm); |
44 | |
45 | /* Set an alarm to go off in a little while. */ |
46 | alarm (2); |
47 | |
48 | /* Check the flag once in a while to see when to quit. */ |
49 | while (keep_going) |
50 | do_stuff (); |
51 | |
52 | return EXIT_SUCCESS; |
53 | } |
54 | |