usleep.c revision 18414 
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#else
45#define	TICK	10000		/* system clock resolution in microseconds */
46#define	USPS	1000000		/* number of microseconds in a second */
47
48#define	setvec(vec, a) \
49	vec.sv_handler = a; vec.sv_mask = vec.sv_onstack = 0
50
51static int ringring;
52#endif
53
54
55void
56usleep(useconds)
57	unsigned int useconds;
58{
59#ifdef _THREAD_SAFE
60    struct timespec time_to_sleep;
61
62    if (useconds) {
63        time_to_sleep.tv_nsec = (useconds % 1000000) * 1000;
64        time_to_sleep.tsvsec = useconds / 1000000;
65        nanosleep(&time_to_sleep,NULL);
66    }
67#else
68	register struct itimerval *itp;
69	struct itimerval itv, oitv;
70	struct sigvec vec, ovec;
71	long omask;
72	static void sleephandler();
73
74	itp = &itv;
75	if (!useconds)
76		return;
77	timerclear(&itp->it_interval);
78	timerclear(&itp->it_value);
79	if (setitimer(ITIMER_REAL, itp, &oitv) < 0)
80		return;
81	itp->it_value.tv_sec = useconds / USPS;
82	itp->it_value.tv_usec = useconds % USPS;
83	if (timerisset(&oitv.it_value)) {
84		if (timercmp(&oitv.it_value, &itp->it_value, >)) {
85			oitv.it_value.tv_sec -= itp->it_value.tv_sec;
86			oitv.it_value.tv_usec -= itp->it_value.tv_usec;
87			if (oitv.it_value.tv_usec < 0) {
88				oitv.it_value.tv_usec += USPS;
89				oitv.it_value.tv_sec--;
90			}
91		} else {
92			itp->it_value = oitv.it_value;
93			oitv.it_value.tv_sec = 0;
94			oitv.it_value.tv_usec = 2 * TICK;
95		}
96	}
97	setvec(vec, sleephandler);
98	(void) sigvec(SIGALRM, &vec, &ovec);
99	omask = sigblock(sigmask(SIGALRM));
100	ringring = 0;
101	(void) setitimer(ITIMER_REAL, itp, (struct itimerval *)0);
102	while (!ringring)
103		sigpause(omask &~ sigmask(SIGALRM));
104	(void) sigvec(SIGALRM, &ovec, (struct sigvec *)0);
105	(void) sigsetmask(omask);
106	(void) setitimer(ITIMER_REAL, &oitv, (struct itimerval *)0);
107#endif
108}
109
110#ifndef  _THREAD_SAFE
111static void
112sleephandler()
113{
114	ringring = 1;
115}
116#endif
117