1 | /* Copyright (C) 1991-2022 Free Software Foundation, Inc. |
2 | This file is part of the GNU C Library. |
3 | |
4 | The GNU C Library is free software; you can redistribute it and/or |
5 | modify it under the terms of the GNU Lesser General Public |
6 | License as published by the Free Software Foundation; either |
7 | version 2.1 of the License, or (at your option) any later version. |
8 | |
9 | The GNU C Library 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 GNU |
12 | Lesser General Public License for more details. |
13 | |
14 | You should have received a copy of the GNU Lesser General Public |
15 | License along with the GNU C Library; if not, see |
16 | <https://www.gnu.org/licenses/>. */ |
17 | |
18 | #include <unistd.h> |
19 | #include <sys/time.h> |
20 | |
21 | /* Schedule an alarm. In SECONDS seconds, the process will get a SIGALRM. |
22 | If SECONDS is zero, any currently scheduled alarm will be cancelled. |
23 | The function returns the number of seconds remaining until the last |
24 | alarm scheduled would have signaled, or zero if there wasn't one. |
25 | There is no return value to indicate an error, but you can set `errno' |
26 | to 0 and check its value after calling `alarm', and this might tell you. |
27 | The signal may come late due to processor scheduling. */ |
28 | unsigned int |
29 | alarm (unsigned int seconds) |
30 | { |
31 | struct itimerval old, new; |
32 | unsigned int retval; |
33 | |
34 | new.it_interval.tv_usec = 0; |
35 | new.it_interval.tv_sec = 0; |
36 | new.it_value.tv_usec = 0; |
37 | new.it_value.tv_sec = (long int) seconds; |
38 | if (__setitimer (ITIMER_REAL, new: &new, old: &old) < 0) |
39 | return 0; |
40 | |
41 | retval = old.it_value.tv_sec; |
42 | /* Round to the nearest second, but never report zero seconds when |
43 | the alarm is still set. */ |
44 | if (old.it_value.tv_usec >= 500000 |
45 | || (retval == 0 && old.it_value.tv_usec > 0)) |
46 | ++retval; |
47 | return retval; |
48 | } |
49 | libc_hidden_def (alarm) |
50 | |