1 /* $OpenBSD: ualarm.c,v 1.7 2005/08/08 08:05:34 espie Exp $ */
2 /*
3 * Copyright (c) 1985, 1993
4 * The Regents of the University of California. All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * 3. Neither the name of the University nor the names of its contributors
15 * may be used to endorse or promote products derived from this software
16 * without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 */
30
31 #include <sys/types.h>
32 #include <sys/time.h>
33 #include <unistd.h>
34
35 #define USPS 1000000 /* # of microseconds in a second */
36
37 /*
38 * Generate a SIGALRM signal in ``usecs'' microseconds.
39 * If ``reload'' is non-zero, keep generating SIGALRM
40 * every ``reload'' microseconds after the first signal.
41 */
42 useconds_t
ualarm(useconds_t usecs,useconds_t reload)43 ualarm(useconds_t usecs, useconds_t reload)
44 {
45 struct itimerval new, old;
46
47 new.it_interval.tv_usec = reload % USPS;
48 new.it_interval.tv_sec = reload / USPS;
49
50 new.it_value.tv_usec = usecs % USPS;
51 new.it_value.tv_sec = usecs / USPS;
52
53 if (setitimer(ITIMER_REAL, &new, &old) == 0)
54 return ((useconds_t)(old.it_value.tv_sec * USPS + old.it_value.tv_usec));
55 /* else */
56 return ((useconds_t)-1);
57 }
58