usleep.c revision 25862 
1/*
2 * Copyright (c) 1989, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by the University of
16 *	California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#if defined(LIBC_SCCS) && !defined(lint)
35static char sccsid[] = "@(#)usleep.c	8.1 (Berkeley) 6/4/93";
36#endif /* LIBC_SCCS and not lint */
37
38#include <sys/time.h>
39#include <signal.h>
40#include <unistd.h>
41#ifdef  _THREAD_SAFE
42#include <pthread.h>
43#include "pthread_private.h"
44#endif
45
46#if !defined(_THREAD_SAFE) && !defined(USE_NANOSLEEP)
47#define	TICK	10000		/* system clock resolution in microseconds */
48#define	USPS	1000000		/* number of microseconds in a second */
49
50#define	setvec(vec, a) \
51	vec.sv_handler = a; vec.sv_mask = vec.sv_onstack = 0
52
53static int ringring;
54
55static void
56sleephandler()
57{
58	ringring = 1;
59}
60#endif
61
62
63void
64usleep(useconds)
65	unsigned int useconds;
66{
67#ifdef _THREAD_SAFE
68	struct timespec time_to_sleep;
69
70	if (useconds) {
71		time_to_sleep.tv_nsec = (useconds % 1000000) * 1000;
72		time_to_sleep.tv_sec = useconds / 1000000;
73		nanosleep(&time_to_sleep, NULL);
74	}
75#else
76	register struct itimerval *itp;
77	struct itimerval itv, oitv;
78	struct sigvec vec, ovec;
79	long omask;
80	static void sleephandler();
81
82	itp = &itv;
83	if (!useconds)
84		return;
85	timerclear(&itp->it_interval);
86	timerclear(&itp->it_value);
87	if (setitimer(ITIMER_REAL, itp, &oitv) < 0)
88		return;
89	itp->it_value.tv_sec = useconds / USPS;
90	itp->it_value.tv_usec = useconds % USPS;
91	if (timerisset(&oitv.it_value)) {
92		if (timercmp(&oitv.it_value, &itp->it_value, >)) {
93			oitv.it_value.tv_sec -= itp->it_value.tv_sec;
94			oitv.it_value.tv_usec -= itp->it_value.tv_usec;
95			if (oitv.it_value.tv_usec < 0) {
96				oitv.it_value.tv_usec += USPS;
97				oitv.it_value.tv_sec--;
98			}
99		} else {
100			itp->it_value = oitv.it_value;
101			oitv.it_value.tv_sec = 0;
102			oitv.it_value.tv_usec = 2 * TICK;
103		}
104	}
105	setvec(vec, sleephandler);
106	(void) sigvec(SIGALRM, &vec, &ovec);
107	omask = sigblock(sigmask(SIGALRM));
108	ringring = 0;
109	(void) setitimer(ITIMER_REAL, itp, (struct itimerval *)0);
110	while (!ringring)
111		sigpause(omask &~ sigmask(SIGALRM));
112	(void) sigvec(SIGALRM, &ovec, (struct sigvec *)0);
113	(void) sigsetmask(omask);
114	(void) setitimer(ITIMER_REAL, &oitv, (struct itimerval *)0);
115#endif
116}
117