| 1 | /* Signal Handlers that Return |
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| 2 | Copyright (C) 1991-2022 Free Software Foundation, Inc. |
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| 3 | |
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| 4 | This program is free software; you can redistribute it and/or |
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| 5 | modify it under the terms of the GNU General Public License |
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| 6 | as published by the Free Software Foundation; either version 2 |
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| 7 | of the License, or (at your option) any later version. |
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| 8 | |
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| 9 | This program is distributed in the hope that it will be useful, |
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| 10 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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| 12 | GNU General Public License for more details. |
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| 13 | |
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| 14 | You should have received a copy of the GNU General Public License |
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| 15 | along with this program; if not, see <https://www.gnu.org/licenses/>. |
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| 16 | */ |
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| 17 | |
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| 18 | #include <signal.h> |
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| 19 | #include <stdio.h> |
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| 20 | #include <stdlib.h> |
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| 21 | |
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| 22 | /* This flag controls termination of the main loop. */ |
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| 23 | volatile sig_atomic_t keep_going = 1; |
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| 24 | |
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| 25 | /* The signal handler just clears the flag and re-enables itself. */ |
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| 26 | void |
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| 27 | catch_alarm (int sig) |
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| 28 | { |
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| 29 | keep_going = 0; |
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| 30 | signal (sig: sig, handler: catch_alarm); |
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| 31 | } |
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| 32 | |
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| 33 | void |
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| 34 | do_stuff (void) |
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| 35 | { |
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| 36 | puts (s: "Doing stuff while waiting for alarm...." ); |
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| 37 | } |
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| 38 | |
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| 39 | int |
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| 40 | main (void) |
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| 41 | { |
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| 42 | /* Establish a handler for SIGALRM signals. */ |
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| 43 | signal (SIGALRM, handler: catch_alarm); |
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| 44 | |
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| 45 | /* Set an alarm to go off in a little while. */ |
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| 46 | alarm (2); |
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| 47 | |
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| 48 | /* Check the flag once in a while to see when to quit. */ |
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| 49 | while (keep_going) |
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| 50 | do_stuff (); |
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| 51 | |
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| 52 | return EXIT_SUCCESS; |
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| 53 | } |
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| 54 | |
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