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sem.c revision 1.2 
      1 /*	$NetBSD: sem.c,v 1.2 2003/03/09 00:44:43 lukem 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  * 3. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *        This product includes software developed by the NetBSD
     21  *        Foundation, Inc. and its contributors.
     22  * 4. Neither the name of The NetBSD Foundation nor the names of its
     23  *    contributors may be used to endorse or promote products derived
     24  *    from this software without specific prior written permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     27  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     28  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     29  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     30  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     31  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     32  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     33  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     34  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     35  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     36  * POSSIBILITY OF SUCH DAMAGE.
     37  */
     38 
     39 /*
     40  * Copyright (C) 2000 Jason Evans <jasone (at) freebsd.org>.
     41  * All rights reserved.
     42  *
     43  * Redistribution and use in source and binary forms, with or without
     44  * modification, are permitted provided that the following conditions
     45  * are met:
     46  * 1. Redistributions of source code must retain the above copyright
     47  *    notice(s), this list of conditions and the following disclaimer as
     48  *    the first lines of this file unmodified other than the possible
     49  *    addition of one or more copyright notices.
     50  * 2. Redistributions in binary form must reproduce the above copyright
     51  *    notice(s), this list of conditions and the following disclaimer in
     52  *    the documentation and/or other materials provided with the
     53  *    distribution.
     54  *
     55  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
     56  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     57  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     58  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
     59  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     60  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     61  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
     62  * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
     63  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
     64  * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
     65  * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     66  */
     67 
     68 #include <sys/cdefs.h>
     69 __RCSID("$NetBSD: sem.c,v 1.2 2003/03/09 00:44:43 lukem Exp $");
     70 
     71 /*
     72  * If an application is linked against both librt and libpthread, the
     73  * libpthread versions must be used.  Provide weak aliases to cause
     74  * this behavior.
     75  */
     76 #define	sem_init	_librt_sem_init
     77 #define	sem_destroy	_librt_sem_destroy
     78 #define	sem_open	_librt_sem_open
     79 #define	sem_close	_librt_sem_close
     80 #define	sem_unlink	_librt_sem_unlink
     81 #define	sem_wait	_librt_sem_wait
     82 #define	sem_trywait	_librt_sem_trywait
     83 #define	sem_post	_librt_sem_post
     84 #define	sem_getvalue	_librt_sem_getvalue
     85 
     86 #define	_LIBC		/* XXX to get semid_t type */
     87 
     88 #include <sys/types.h>
     89 #include <sys/ksem.h>
     90 #include <sys/queue.h>
     91 #include <stdlib.h>
     92 #include <errno.h>
     93 #include <fcntl.h>
     94 #include <semaphore.h>
     95 #include <stdarg.h>
     96 
     97 struct _sem_st {
     98 	unsigned int	ksem_magic;
     99 #define	KSEM_MAGIC	0x90af0421U
    100 
    101 	LIST_ENTRY(_sem_st) ksem_list;
    102 	semid_t		ksem_semid;	/* 0 -> user (non-shared) */
    103 	sem_t		*ksem_identity;
    104 };
    105 
    106 static int sem_alloc(unsigned int value, semid_t semid, sem_t *semp);
    107 static void sem_free(sem_t sem);
    108 
    109 static LIST_HEAD(, _sem_st) named_sems = LIST_HEAD_INITIALIZER(&named_sems);
    110 
    111 __weak_alias(sem_init,_librt_sem_init)
    112 __weak_alias(sem_destroy,_librt_sem_destroy)
    113 __weak_alias(sem_open,_librt_sem_open)
    114 __weak_alias(sem_close,_librt_sem_close)
    115 __weak_alias(sem_unlink,_librt_sem_unlink)
    116 __weak_alias(sem_wait,_librt_sem_wait)
    117 __weak_alias(sem_trywait,_librt_sem_trywait)
    118 __weak_alias(sem_post,_librt_sem_post)
    119 __weak_alias(sem_getvalue,_librt_sem_getvalue)
    120 
    121 static void
    122 sem_free(sem_t sem)
    123 {
    124 
    125 	sem->ksem_magic = 0;
    126 	free(sem);
    127 }
    128 
    129 static int
    130 sem_alloc(unsigned int value, semid_t semid, sem_t *semp)
    131 {
    132 	sem_t sem;
    133 
    134 	if (value > SEM_VALUE_MAX)
    135 		return (EINVAL);
    136 
    137 	if ((sem = malloc(sizeof(struct _sem_st))) == NULL)
    138 		return (ENOSPC);
    139 
    140 	sem->ksem_magic = KSEM_MAGIC;
    141 	sem->ksem_semid = semid;
    142 
    143 	*semp = sem;
    144 	return (0);
    145 }
    146 
    147 /* ARGSUSED */
    148 int
    149 sem_init(sem_t *sem, int pshared, unsigned int value)
    150 {
    151 	semid_t	semid;
    152 	int error;
    153 
    154 	if (_ksem_init(value, &semid) == -1)
    155 		return (-1);
    156 
    157 	if ((error = sem_alloc(value, semid, sem)) != 0) {
    158 		_ksem_destroy(semid);
    159 		errno = error;
    160 		return (-1);
    161 	}
    162 
    163 	return (0);
    164 }
    165 
    166 int
    167 sem_destroy(sem_t *sem)
    168 {
    169 
    170 #ifdef ERRORCHECK
    171 	if (sem == NULL || *sem == NULL || (*sem)->ksem_magic != KSEM_MAGIC) {
    172 		errno = EINVAL;
    173 		return (-1);
    174 	}
    175 #endif
    176 
    177 	if (_ksem_destroy((*sem)->ksem_semid) == -1)
    178 		return (-1);
    179 
    180 	sem_free(*sem);
    181 
    182 	return (0);
    183 }
    184 
    185 sem_t *
    186 sem_open(const char *name, int oflag, ...)
    187 {
    188 	sem_t *sem, s;
    189 	semid_t semid;
    190 	mode_t mode;
    191 	unsigned int value;
    192 	int error;
    193 	va_list ap;
    194 
    195 	mode = 0;
    196 	value = 0;
    197 
    198 	if (oflag & O_CREAT) {
    199 		va_start(ap, oflag);
    200 		mode = va_arg(ap, int);
    201 		value = va_arg(ap, unsigned int);
    202 		va_end(ap);
    203 	}
    204 
    205 	/*
    206 	 * We can be lazy and let the kernel handle the oflag,
    207 	 * we'll just merge duplicate IDs into our list.
    208 	 */
    209 	if (_ksem_open(name, oflag, mode, value, &semid) == -1)
    210 		return (SEM_FAILED);
    211 
    212 	/*
    213 	 * Search for a duplicate ID, we must return the same sem_t *
    214 	 * if we locate one.
    215 	 */
    216 	LIST_FOREACH(s, &named_sems, ksem_list) {
    217 		if (s->ksem_semid == semid)
    218 			return (s->ksem_identity);
    219 	}
    220 
    221 	if ((sem = malloc(sizeof(*sem))) == NULL) {
    222 		error = ENOSPC;
    223 		goto bad;
    224 	}
    225 	if ((error = sem_alloc(value, semid, sem)) != 0)
    226 		goto bad;
    227 
    228 	LIST_INSERT_HEAD(&named_sems, *sem, ksem_list);
    229 	(*sem)->ksem_identity = sem;
    230 
    231 	return (sem);
    232 
    233  bad:
    234 	_ksem_close(semid);
    235 	if (sem != NULL) {
    236 		if (*sem != NULL)
    237 			sem_free(*sem);
    238 		free(sem);
    239 	}
    240 	errno = error;
    241 	return (SEM_FAILED);
    242 }
    243 
    244 int
    245 sem_close(sem_t *sem)
    246 {
    247 
    248 #ifdef ERRORCHECK
    249 	if (sem == NULL || *sem == NULL || (*sem)->ksem_magic != KSEM_MAGIC) {
    250 		errno = EINVAL;
    251 		return (-1);
    252 	}
    253 #endif
    254 
    255 	if (_ksem_close((*sem)->ksem_semid) == -1)
    256 		return (-1);
    257 
    258 	LIST_REMOVE((*sem), ksem_list);
    259 	sem_free(*sem);
    260 	free(sem);
    261 	return (0);
    262 }
    263 
    264 int
    265 sem_unlink(const char *name)
    266 {
    267 
    268 	return (_ksem_unlink(name));
    269 }
    270 
    271 int
    272 sem_wait(sem_t *sem)
    273 {
    274 
    275 #ifdef ERRORCHECK
    276 	if (sem == NULL || *sem == NULL || (*sem)->ksem_magic != KSEM_MAGIC) {
    277 		errno = EINVAL;
    278 		return (-1);
    279 	}
    280 #endif
    281 
    282 	return (_ksem_wait((*sem)->ksem_semid));
    283 }
    284 
    285 int
    286 sem_trywait(sem_t *sem)
    287 {
    288 
    289 #ifdef ERRORCHECK
    290 	if (sem == NULL || *sem == NULL || (*sem)->ksem_magic != KSEM_MAGIC) {
    291 		errno = EINVAL;
    292 		return (-1);
    293 	}
    294 #endif
    295 
    296 	return (_ksem_trywait((*sem)->ksem_semid));
    297 }
    298 
    299 int
    300 sem_post(sem_t *sem)
    301 {
    302 
    303 #ifdef ERRORCHECK
    304 	if (sem == NULL || *sem == NULL || (*sem)->ksem_magic != KSEM_MAGIC) {
    305 		errno = EINVAL;
    306 		return (-1);
    307 	}
    308 #endif
    309 
    310 	return (_ksem_post((*sem)->ksem_semid));
    311 }
    312 
    313 int
    314 sem_getvalue(sem_t * __restrict sem, int * __restrict sval)
    315 {
    316 
    317 #ifdef ERRORCHECK
    318 	if (sem == NULL || *sem == NULL || (*sem)->ksem_magic != KSEM_MAGIC) {
    319 		errno = EINVAL;
    320 		return (-1);
    321 	}
    322 #endif
    323 	return (_ksem_getvalue((*sem)->ksem_semid, sval));
    324 }
    325