usleep.c revision 25890 
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#endif
50
51#define	setvec(vec, a) \
52	vec.sv_handler = a; vec.sv_mask = vec.sv_onstack = 0
53
54#if !defined(_THREAD_SAFE) && !defined(USE_NANOSLEEP)
55static int ringring;
56#endif
57
58static void
59sleephandler()
60{
61#if !defined(_THREAD_SAFE) && !defined(USE_NANOSLEEP)
62	ringring = 1;
63#endif
64}
65
66
67void
68usleep(useconds)
69	unsigned int useconds;
70{
71#if defined(_THREAD_SAFE) || defined(USE_NANOSLEEP)
72	struct timespec time_to_sleep;
73	struct timespec time_remaining;
74	struct sigvec vec, ovec;
75
76	if (useconds) {
77		time_to_sleep.tv_nsec = (useconds % 1000000) * 1000;
78		time_to_sleep.tv_sec = useconds / 1000000;
79		setvec(vec, sleephandler);
80		(void) sigvec(SIGALRM, &vec, &ovec);
81		do {
82			nanosleep(&time_to_sleep, &time_remaining);
83			time_to_sleep = time_remaining;
84		} while (time_to_sleep.tv_sec != 0 &&
85			 time_to_sleep.tv_nsec != 0);
86		(void) sigvec(SIGALRM, &ovec, (struct sigvec *)0);
87	}
88#else
89	register struct itimerval *itp;
90	struct itimerval itv, oitv;
91	struct sigvec vec, ovec;
92	long omask;
93	static void sleephandler();
94
95	itp = &itv;
96	if (!useconds)
97		return;
98	timerclear(&itp->it_interval);
99	timerclear(&itp->it_value);
100	if (setitimer(ITIMER_REAL, itp, &oitv) < 0)
101		return;
102	itp->it_value.tv_sec = useconds / USPS;
103	itp->it_value.tv_usec = useconds % USPS;
104	if (timerisset(&oitv.it_value)) {
105		if (timercmp(&oitv.it_value, &itp->it_value, >)) {
106			oitv.it_value.tv_sec -= itp->it_value.tv_sec;
107			oitv.it_value.tv_usec -= itp->it_value.tv_usec;
108			if (oitv.it_value.tv_usec < 0) {
109				oitv.it_value.tv_usec += USPS;
110				oitv.it_value.tv_sec--;
111			}
112		} else {
113			itp->it_value = oitv.it_value;
114			oitv.it_value.tv_sec = 0;
115			oitv.it_value.tv_usec = 2 * TICK;
116		}
117	}
118	setvec(vec, sleephandler);
119	(void) sigvec(SIGALRM, &vec, &ovec);
120	omask = sigblock(sigmask(SIGALRM));
121	ringring = 0;
122	(void) setitimer(ITIMER_REAL, itp, (struct itimerval *)0);
123	while (!ringring)
124		sigpause(omask &~ sigmask(SIGALRM));
125	(void) sigvec(SIGALRM, &ovec, (struct sigvec *)0);
126	(void) sigsetmask(omask);
127	(void) setitimer(ITIMER_REAL, &oitv, (struct itimerval *)0);
128#endif
129}
130