usleep.c revision 25871
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#if defined(_THREAD_SAFE) || defined(USE_NANOSLEEP) 68 struct timespec time_to_sleep; 69 struct timespec time_remaining; 70 71 if (useconds) { 72 time_to_sleep.tv_nsec = (useconds % 1000000) * 1000; 73 time_to_sleep.tv_sec = useconds / 1000000; 74 do { 75 nanosleep(&time_to_sleep, &time_remaining); 76 time_to_sleep = time_remaining; 77 } while (time_to_sleep.tv_sec != 0 && 78 time_to_sleep.tv_nsec != 0); 79 } 80#else 81 register struct itimerval *itp; 82 struct itimerval itv, oitv; 83 struct sigvec vec, ovec; 84 long omask; 85 static void sleephandler(); 86 87 itp = &itv; 88 if (!useconds) 89 return; 90 timerclear(&itp->it_interval); 91 timerclear(&itp->it_value); 92 if (setitimer(ITIMER_REAL, itp, &oitv) < 0) 93 return; 94 itp->it_value.tv_sec = useconds / USPS; 95 itp->it_value.tv_usec = useconds % USPS; 96 if (timerisset(&oitv.it_value)) { 97 if (timercmp(&oitv.it_value, &itp->it_value, >)) { 98 oitv.it_value.tv_sec -= itp->it_value.tv_sec; 99 oitv.it_value.tv_usec -= itp->it_value.tv_usec; 100 if (oitv.it_value.tv_usec < 0) { 101 oitv.it_value.tv_usec += USPS; 102 oitv.it_value.tv_sec--; 103 } 104 } else { 105 itp->it_value = oitv.it_value; 106 oitv.it_value.tv_sec = 0; 107 oitv.it_value.tv_usec = 2 * TICK; 108 } 109 } 110 setvec(vec, sleephandler); 111 (void) sigvec(SIGALRM, &vec, &ovec); 112 omask = sigblock(sigmask(SIGALRM)); 113 ringring = 0; 114 (void) setitimer(ITIMER_REAL, itp, (struct itimerval *)0); 115 while (!ringring) 116 sigpause(omask &~ sigmask(SIGALRM)); 117 (void) sigvec(SIGALRM, &ovec, (struct sigvec *)0); 118 (void) sigsetmask(omask); 119 (void) setitimer(ITIMER_REAL, &oitv, (struct itimerval *)0); 120#endif 121} 122