2 * Copyright (C) 2000 Jason Evans <jasone@freebsd.org>.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice(s), this list of conditions and the following disclaimer as
10 * the first lines of this file unmodified other than the possible
11 * addition of one or more copyright notices.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice(s), this list of conditions and the following disclaimer in
14 * the documentation and/or other materials provided with the
17 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
18 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
20 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
21 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
22 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
23 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
24 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
25 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
26 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
27 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 * $FreeBSD: src/lib/libc_r/uthread/uthread_sem.c,v 1.3.2.5 2002/10/22 14:44:03 fjoe Exp $
30 * $DragonFly: src/lib/libc_r/uthread/uthread_sem.c,v 1.4 2007/06/26 23:30:05 josepht Exp $
33 #include <sys/semaphore.h>
39 #include "pthread_private.h"
41 #define _SEM_CHECK_VALIDITY(sem) \
42 if ((*(sem))->magic != SEM_MAGIC) { \
49 _sem_init(sem_t *sem, int pshared, unsigned int value)
54 * Range check the arguments.
58 * The user wants a semaphore that can be shared among
59 * processes, which this implementation can't do. Sounds like a
60 * permissions problem to me (yeah right).
67 if (value > SEM_VALUE_MAX) {
73 *sem = (sem_t)malloc(sizeof(struct sem));
81 * Initialize the semaphore.
83 if (pthread_mutex_init(&(*sem)->lock, NULL) != 0) {
90 if (pthread_cond_init(&(*sem)->gtzero, NULL) != 0) {
91 pthread_mutex_destroy(&(*sem)->lock);
98 (*sem)->count = (u_int32_t)value;
100 (*sem)->magic = SEM_MAGIC;
108 _sem_destroy(sem_t *sem)
112 _SEM_CHECK_VALIDITY(sem);
114 /* Make sure there are no waiters. */
115 pthread_mutex_lock(&(*sem)->lock);
116 if ((*sem)->nwaiters > 0) {
117 pthread_mutex_unlock(&(*sem)->lock);
122 pthread_mutex_unlock(&(*sem)->lock);
124 pthread_mutex_destroy(&(*sem)->lock);
125 pthread_cond_destroy(&(*sem)->gtzero);
136 _sem_open(const char *name, int oflag, ...)
143 _sem_close(sem_t *sem)
150 _sem_unlink(const char *name)
157 _sem_wait(sem_t *sem)
161 _thread_enter_cancellation_point();
163 _SEM_CHECK_VALIDITY(sem);
165 pthread_mutex_lock(&(*sem)->lock);
167 while ((*sem)->count == 0) {
169 pthread_cond_wait(&(*sem)->gtzero, &(*sem)->lock);
174 pthread_mutex_unlock(&(*sem)->lock);
178 _thread_leave_cancellation_point();
183 _sem_trywait(sem_t *sem)
187 _SEM_CHECK_VALIDITY(sem);
189 pthread_mutex_lock(&(*sem)->lock);
191 if ((*sem)->count > 0) {
199 pthread_mutex_unlock(&(*sem)->lock);
206 _sem_post(sem_t *sem)
210 _SEM_CHECK_VALIDITY(sem);
213 * sem_post() is required to be safe to call from within signal
214 * handlers. Thus, we must defer signals.
216 _thread_kern_sig_defer();
218 pthread_mutex_lock(&(*sem)->lock);
221 if ((*sem)->nwaiters > 0)
222 pthread_cond_signal(&(*sem)->gtzero);
224 pthread_mutex_unlock(&(*sem)->lock);
226 _thread_kern_sig_undefer();
233 _sem_getvalue(sem_t *sem, int *sval)
237 _SEM_CHECK_VALIDITY(sem);
239 pthread_mutex_lock(&(*sem)->lock);
240 *sval = (int)(*sem)->count;
241 pthread_mutex_unlock(&(*sem)->lock);
248 __strong_reference(_sem_init, sem_init);
249 __strong_reference(_sem_destroy, sem_destroy);
250 __strong_reference(_sem_open, sem_open);
251 __strong_reference(_sem_close, sem_close);
252 __strong_reference(_sem_unlink, sem_unlink);
253 __strong_reference(_sem_wait, sem_wait);
254 __strong_reference(_sem_trywait, sem_trywait);
255 __strong_reference(_sem_post, sem_post);
256 __strong_reference(_sem_getvalue, sem_getvalue);