Home | History | Annotate | Line # | Download | only in librt
sem.c revision 1.5 
      1 /*	$NetBSD: sem.c,v 1.5 2008/11/14 15:49:20 ad Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2003 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Jason R. Thorpe.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 /*
     33  * Copyright (C) 2000 Jason Evans <jasone (at) freebsd.org>.
     34  * All rights reserved.
     35  *
     36  * Redistribution and use in source and binary forms, with or without
     37  * modification, are permitted provided that the following conditions
     38  * are met:
     39  * 1. Redistributions of source code must retain the above copyright
     40  *    notice(s), this list of conditions and the following disclaimer as
     41  *    the first lines of this file unmodified other than the possible
     42  *    addition of one or more copyright notices.
     43  * 2. Redistributions in binary form must reproduce the above copyright
     44  *    notice(s), this list of conditions and the following disclaimer in
     45  *    the documentation and/or other materials provided with the
     46  *    distribution.
     47  *
     48  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
     49  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     50  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     51  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
     52  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     53  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     54  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
     55  * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
     56  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
     57  * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
     58  * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     59  */
     60 
     61 #include <sys/cdefs.h>
     62 __RCSID("$NetBSD: sem.c,v 1.5 2008/11/14 15:49:20 ad Exp $");
     63 
     64 /*
     65  * If an application is linked against both librt and libpthread, the
     66  * libpthread versions must be used.  Provide weak aliases to cause
     67  * this behavior.
     68  */
     69 #define	sem_init	_librt_sem_init
     70 #define	sem_destroy	_librt_sem_destroy
     71 #define	sem_open	_librt_sem_open
     72 #define	sem_close	_librt_sem_close
     73 #define	sem_unlink	_librt_sem_unlink
     74 #define	sem_wait	_librt_sem_wait
     75 #define	sem_trywait	_librt_sem_trywait
     76 #define	sem_post	_librt_sem_post
     77 #define	sem_getvalue	_librt_sem_getvalue
     78 
     79 #define	_LIBC
     80 
     81 #include <sys/types.h>
     82 #include <sys/ksem.h>
     83 #include <sys/queue.h>
     84 #include <stdlib.h>
     85 #include <errno.h>
     86 #include <fcntl.h>
     87 #include <semaphore.h>
     88 #include <stdarg.h>
     89 
     90 struct _sem_st {
     91 	unsigned int	ksem_magic;
     92 #define	KSEM_MAGIC	0x90af0421U
     93 
     94 	LIST_ENTRY(_sem_st) ksem_list;
     95 	intptr_t		ksem_semid;	/* 0 -> user (non-shared) */
     96 	sem_t		*ksem_identity;
     97 };
     98 
     99 static int sem_alloc(unsigned int value, intptr_t semid, sem_t *semp);
    100 static void sem_free(sem_t sem);
    101 
    102 static LIST_HEAD(, _sem_st) named_sems = LIST_HEAD_INITIALIZER(&named_sems);
    103 
    104 #ifdef __weak_alias
    105 __weak_alias(sem_init,_librt_sem_init)
    106 __weak_alias(sem_destroy,_librt_sem_destroy)
    107 __weak_alias(sem_open,_librt_sem_open)
    108 __weak_alias(sem_close,_librt_sem_close)
    109 __weak_alias(sem_unlink,_librt_sem_unlink)
    110 __weak_alias(sem_wait,_librt_sem_wait)
    111 __weak_alias(sem_trywait,_librt_sem_trywait)
    112 __weak_alias(sem_post,_librt_sem_post)
    113 __weak_alias(sem_getvalue,_librt_sem_getvalue)
    114 #endif
    115 
    116 static void
    117 sem_free(sem_t sem)
    118 {
    119 
    120 	sem->ksem_magic = 0;
    121 	free(sem);
    122 }
    123 
    124 static int
    125 sem_alloc(unsigned int value, intptr_t semid, sem_t *semp)
    126 {
    127 	sem_t sem;
    128 
    129 	if (value > SEM_VALUE_MAX)
    130 		return (EINVAL);
    131 
    132 	if ((sem = malloc(sizeof(struct _sem_st))) == NULL)
    133 		return (ENOSPC);
    134 
    135 	sem->ksem_magic = KSEM_MAGIC;
    136 	sem->ksem_semid = semid;
    137 
    138 	*semp = sem;
    139 	return (0);
    140 }
    141 
    142 /* ARGSUSED */
    143 int
    144 sem_init(sem_t *sem, int pshared, unsigned int value)
    145 {
    146 	intptr_t	semid;
    147 	int error;
    148 
    149 	if (_ksem_init(value, &semid) == -1)
    150 		return (-1);
    151 
    152 	if ((error = sem_alloc(value, semid, sem)) != 0) {
    153 		_ksem_destroy(semid);
    154 		errno = error;
    155 		return (-1);
    156 	}
    157 
    158 	return (0);
    159 }
    160 
    161 int
    162 sem_destroy(sem_t *sem)
    163 {
    164 
    165 #ifdef ERRORCHECK
    166 	if (sem == NULL || *sem == NULL || (*sem)->ksem_magic != KSEM_MAGIC) {
    167 		errno = EINVAL;
    168 		return (-1);
    169 	}
    170 #endif
    171 
    172 	if (_ksem_destroy((*sem)->ksem_semid) == -1)
    173 		return (-1);
    174 
    175 	sem_free(*sem);
    176 
    177 	return (0);
    178 }
    179 
    180 sem_t *
    181 sem_open(const char *name, int oflag, ...)
    182 {
    183 	sem_t *sem, s;
    184 	intptr_t semid;
    185 	mode_t mode;
    186 	unsigned int value;
    187 	int error;
    188 	va_list ap;
    189 
    190 	mode = 0;
    191 	value = 0;
    192 
    193 	if (oflag & O_CREAT) {
    194 		va_start(ap, oflag);
    195 		mode = va_arg(ap, int);
    196 		value = va_arg(ap, unsigned int);
    197 		va_end(ap);
    198 	}
    199 
    200 	/*
    201 	 * We can be lazy and let the kernel handle the oflag,
    202 	 * we'll just merge duplicate IDs into our list.
    203 	 */
    204 	if (_ksem_open(name, oflag, mode, value, &semid) == -1)
    205 		return (SEM_FAILED);
    206 
    207 	/*
    208 	 * Search for a duplicate ID, we must return the same sem_t *
    209 	 * if we locate one.
    210 	 */
    211 	LIST_FOREACH(s, &named_sems, ksem_list) {
    212 		if (s->ksem_semid == semid)
    213 			return (s->ksem_identity);
    214 	}
    215 
    216 	if ((sem = malloc(sizeof(*sem))) == NULL) {
    217 		error = ENOSPC;
    218 		goto bad;
    219 	}
    220 	if ((error = sem_alloc(value, semid, sem)) != 0)
    221 		goto bad;
    222 
    223 	LIST_INSERT_HEAD(&named_sems, *sem, ksem_list);
    224 	(*sem)->ksem_identity = sem;
    225 
    226 	return (sem);
    227 
    228  bad:
    229 	_ksem_close(semid);
    230 	if (sem != NULL) {
    231 		if (*sem != NULL)
    232 			sem_free(*sem);
    233 		free(sem);
    234 	}
    235 	errno = error;
    236 	return (SEM_FAILED);
    237 }
    238 
    239 int
    240 sem_close(sem_t *sem)
    241 {
    242 
    243 #ifdef ERRORCHECK
    244 	if (sem == NULL || *sem == NULL || (*sem)->ksem_magic != KSEM_MAGIC) {
    245 		errno = EINVAL;
    246 		return (-1);
    247 	}
    248 #endif
    249 
    250 	if (_ksem_close((*sem)->ksem_semid) == -1)
    251 		return (-1);
    252 
    253 	LIST_REMOVE((*sem), ksem_list);
    254 	sem_free(*sem);
    255 	free(sem);
    256 	return (0);
    257 }
    258 
    259 int
    260 sem_unlink(const char *name)
    261 {
    262 
    263 	return (_ksem_unlink(name));
    264 }
    265 
    266 int
    267 sem_wait(sem_t *sem)
    268 {
    269 
    270 #ifdef ERRORCHECK
    271 	if (sem == NULL || *sem == NULL || (*sem)->ksem_magic != KSEM_MAGIC) {
    272 		errno = EINVAL;
    273 		return (-1);
    274 	}
    275 #endif
    276 
    277 	return (_ksem_wait((*sem)->ksem_semid));
    278 }
    279 
    280 int
    281 sem_trywait(sem_t *sem)
    282 {
    283 
    284 #ifdef ERRORCHECK
    285 	if (sem == NULL || *sem == NULL || (*sem)->ksem_magic != KSEM_MAGIC) {
    286 		errno = EINVAL;
    287 		return (-1);
    288 	}
    289 #endif
    290 
    291 	return (_ksem_trywait((*sem)->ksem_semid));
    292 }
    293 
    294 int
    295 sem_post(sem_t *sem)
    296 {
    297 
    298 #ifdef ERRORCHECK
    299 	if (sem == NULL || *sem == NULL || (*sem)->ksem_magic != KSEM_MAGIC) {
    300 		errno = EINVAL;
    301 		return (-1);
    302 	}
    303 #endif
    304 
    305 	return (_ksem_post((*sem)->ksem_semid));
    306 }
    307 
    308 int
    309 sem_getvalue(sem_t * __restrict sem, int * __restrict sval)
    310 {
    311 
    312 #ifdef ERRORCHECK
    313 	if (sem == NULL || *sem == NULL || (*sem)->ksem_magic != KSEM_MAGIC) {
    314 		errno = EINVAL;
    315 		return (-1);
    316 	}
    317 #endif
    318 	return (_ksem_getvalue((*sem)->ksem_semid, sval));
    319 }
    320