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sem.c revision 1.3 
      1 /*	$NetBSD: sem.c,v 1.3 2003/12/07 12:53:19 simonb 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 1.3 2003/12/07 12:53:19 simonb 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 #ifdef __weak_alias
    112 __weak_alias(sem_init,_librt_sem_init)
    113 __weak_alias(sem_destroy,_librt_sem_destroy)
    114 __weak_alias(sem_open,_librt_sem_open)
    115 __weak_alias(sem_close,_librt_sem_close)
    116 __weak_alias(sem_unlink,_librt_sem_unlink)
    117 __weak_alias(sem_wait,_librt_sem_wait)
    118 __weak_alias(sem_trywait,_librt_sem_trywait)
    119 __weak_alias(sem_post,_librt_sem_post)
    120 __weak_alias(sem_getvalue,_librt_sem_getvalue)
    121 #endif
    122 
    123 static void
    124 sem_free(sem_t sem)
    125 {
    126 
    127 	sem->ksem_magic = 0;
    128 	free(sem);
    129 }
    130 
    131 static int
    132 sem_alloc(unsigned int value, semid_t semid, sem_t *semp)
    133 {
    134 	sem_t sem;
    135 
    136 	if (value > SEM_VALUE_MAX)
    137 		return (EINVAL);
    138 
    139 	if ((sem = malloc(sizeof(struct _sem_st))) == NULL)
    140 		return (ENOSPC);
    141 
    142 	sem->ksem_magic = KSEM_MAGIC;
    143 	sem->ksem_semid = semid;
    144 
    145 	*semp = sem;
    146 	return (0);
    147 }
    148 
    149 /* ARGSUSED */
    150 int
    151 sem_init(sem_t *sem, int pshared, unsigned int value)
    152 {
    153 	semid_t	semid;
    154 	int error;
    155 
    156 	if (_ksem_init(value, &semid) == -1)
    157 		return (-1);
    158 
    159 	if ((error = sem_alloc(value, semid, sem)) != 0) {
    160 		_ksem_destroy(semid);
    161 		errno = error;
    162 		return (-1);
    163 	}
    164 
    165 	return (0);
    166 }
    167 
    168 int
    169 sem_destroy(sem_t *sem)
    170 {
    171 
    172 #ifdef ERRORCHECK
    173 	if (sem == NULL || *sem == NULL || (*sem)->ksem_magic != KSEM_MAGIC) {
    174 		errno = EINVAL;
    175 		return (-1);
    176 	}
    177 #endif
    178 
    179 	if (_ksem_destroy((*sem)->ksem_semid) == -1)
    180 		return (-1);
    181 
    182 	sem_free(*sem);
    183 
    184 	return (0);
    185 }
    186 
    187 sem_t *
    188 sem_open(const char *name, int oflag, ...)
    189 {
    190 	sem_t *sem, s;
    191 	semid_t semid;
    192 	mode_t mode;
    193 	unsigned int value;
    194 	int error;
    195 	va_list ap;
    196 
    197 	mode = 0;
    198 	value = 0;
    199 
    200 	if (oflag & O_CREAT) {
    201 		va_start(ap, oflag);
    202 		mode = va_arg(ap, int);
    203 		value = va_arg(ap, unsigned int);
    204 		va_end(ap);
    205 	}
    206 
    207 	/*
    208 	 * We can be lazy and let the kernel handle the oflag,
    209 	 * we'll just merge duplicate IDs into our list.
    210 	 */
    211 	if (_ksem_open(name, oflag, mode, value, &semid) == -1)
    212 		return (SEM_FAILED);
    213 
    214 	/*
    215 	 * Search for a duplicate ID, we must return the same sem_t *
    216 	 * if we locate one.
    217 	 */
    218 	LIST_FOREACH(s, &named_sems, ksem_list) {
    219 		if (s->ksem_semid == semid)
    220 			return (s->ksem_identity);
    221 	}
    222 
    223 	if ((sem = malloc(sizeof(*sem))) == NULL) {
    224 		error = ENOSPC;
    225 		goto bad;
    226 	}
    227 	if ((error = sem_alloc(value, semid, sem)) != 0)
    228 		goto bad;
    229 
    230 	LIST_INSERT_HEAD(&named_sems, *sem, ksem_list);
    231 	(*sem)->ksem_identity = sem;
    232 
    233 	return (sem);
    234 
    235  bad:
    236 	_ksem_close(semid);
    237 	if (sem != NULL) {
    238 		if (*sem != NULL)
    239 			sem_free(*sem);
    240 		free(sem);
    241 	}
    242 	errno = error;
    243 	return (SEM_FAILED);
    244 }
    245 
    246 int
    247 sem_close(sem_t *sem)
    248 {
    249 
    250 #ifdef ERRORCHECK
    251 	if (sem == NULL || *sem == NULL || (*sem)->ksem_magic != KSEM_MAGIC) {
    252 		errno = EINVAL;
    253 		return (-1);
    254 	}
    255 #endif
    256 
    257 	if (_ksem_close((*sem)->ksem_semid) == -1)
    258 		return (-1);
    259 
    260 	LIST_REMOVE((*sem), ksem_list);
    261 	sem_free(*sem);
    262 	free(sem);
    263 	return (0);
    264 }
    265 
    266 int
    267 sem_unlink(const char *name)
    268 {
    269 
    270 	return (_ksem_unlink(name));
    271 }
    272 
    273 int
    274 sem_wait(sem_t *sem)
    275 {
    276 
    277 #ifdef ERRORCHECK
    278 	if (sem == NULL || *sem == NULL || (*sem)->ksem_magic != KSEM_MAGIC) {
    279 		errno = EINVAL;
    280 		return (-1);
    281 	}
    282 #endif
    283 
    284 	return (_ksem_wait((*sem)->ksem_semid));
    285 }
    286 
    287 int
    288 sem_trywait(sem_t *sem)
    289 {
    290 
    291 #ifdef ERRORCHECK
    292 	if (sem == NULL || *sem == NULL || (*sem)->ksem_magic != KSEM_MAGIC) {
    293 		errno = EINVAL;
    294 		return (-1);
    295 	}
    296 #endif
    297 
    298 	return (_ksem_trywait((*sem)->ksem_semid));
    299 }
    300 
    301 int
    302 sem_post(sem_t *sem)
    303 {
    304 
    305 #ifdef ERRORCHECK
    306 	if (sem == NULL || *sem == NULL || (*sem)->ksem_magic != KSEM_MAGIC) {
    307 		errno = EINVAL;
    308 		return (-1);
    309 	}
    310 #endif
    311 
    312 	return (_ksem_post((*sem)->ksem_semid));
    313 }
    314 
    315 int
    316 sem_getvalue(sem_t * __restrict sem, int * __restrict sval)
    317 {
    318 
    319 #ifdef ERRORCHECK
    320 	if (sem == NULL || *sem == NULL || (*sem)->ksem_magic != KSEM_MAGIC) {
    321 		errno = EINVAL;
    322 		return (-1);
    323 	}
    324 #endif
    325 	return (_ksem_getvalue((*sem)->ksem_semid, sval));
    326 }
    327