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sem.c revision 1.6 
      1 /*	$NetBSD: sem.c,v 1.6 2012/03/08 21:59:29 joerg 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 1.6 2012/03/08 21:59:29 joerg 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_timedwait	_librt_sem_timedwait
     76 #define	sem_trywait	_librt_sem_trywait
     77 #define	sem_post	_librt_sem_post
     78 #define	sem_getvalue	_librt_sem_getvalue
     79 
     80 #define	_LIBC
     81 
     82 #include <sys/types.h>
     83 #include <sys/ksem.h>
     84 #include <sys/queue.h>
     85 #include <stdlib.h>
     86 #include <errno.h>
     87 #include <fcntl.h>
     88 #include <semaphore.h>
     89 #include <stdarg.h>
     90 
     91 struct _sem_st {
     92 	unsigned int	ksem_magic;
     93 #define	KSEM_MAGIC	0x90af0421U
     94 
     95 	LIST_ENTRY(_sem_st) ksem_list;
     96 	intptr_t		ksem_semid;	/* 0 -> user (non-shared) */
     97 	sem_t		*ksem_identity;
     98 };
     99 
    100 static int sem_alloc(unsigned int value, intptr_t semid, sem_t *semp);
    101 static void sem_free(sem_t sem);
    102 
    103 static LIST_HEAD(, _sem_st) named_sems = LIST_HEAD_INITIALIZER(&named_sems);
    104 
    105 #ifdef __weak_alias
    106 __weak_alias(sem_init,_librt_sem_init)
    107 __weak_alias(sem_destroy,_librt_sem_destroy)
    108 __weak_alias(sem_open,_librt_sem_open)
    109 __weak_alias(sem_close,_librt_sem_close)
    110 __weak_alias(sem_unlink,_librt_sem_unlink)
    111 __weak_alias(sem_wait,_librt_sem_wait)
    112 __weak_alias(sem_timedwait,_librt_sem_timedwait)
    113 __weak_alias(sem_trywait,_librt_sem_trywait)
    114 __weak_alias(sem_post,_librt_sem_post)
    115 __weak_alias(sem_getvalue,_librt_sem_getvalue)
    116 #endif
    117 
    118 static void
    119 sem_free(sem_t sem)
    120 {
    121 
    122 	sem->ksem_magic = 0;
    123 	free(sem);
    124 }
    125 
    126 static int
    127 sem_alloc(unsigned int value, intptr_t semid, sem_t *semp)
    128 {
    129 	sem_t sem;
    130 
    131 	if (value > SEM_VALUE_MAX)
    132 		return (EINVAL);
    133 
    134 	if ((sem = malloc(sizeof(struct _sem_st))) == NULL)
    135 		return (ENOSPC);
    136 
    137 	sem->ksem_magic = KSEM_MAGIC;
    138 	sem->ksem_semid = semid;
    139 
    140 	*semp = sem;
    141 	return (0);
    142 }
    143 
    144 /* ARGSUSED */
    145 int
    146 sem_init(sem_t *sem, int pshared, unsigned int value)
    147 {
    148 	intptr_t	semid;
    149 	int error;
    150 
    151 	if (_ksem_init(value, &semid) == -1)
    152 		return (-1);
    153 
    154 	if ((error = sem_alloc(value, semid, sem)) != 0) {
    155 		_ksem_destroy(semid);
    156 		errno = error;
    157 		return (-1);
    158 	}
    159 
    160 	return (0);
    161 }
    162 
    163 int
    164 sem_destroy(sem_t *sem)
    165 {
    166 
    167 #ifdef ERRORCHECK
    168 	if (sem == NULL || *sem == NULL || (*sem)->ksem_magic != KSEM_MAGIC) {
    169 		errno = EINVAL;
    170 		return (-1);
    171 	}
    172 #endif
    173 
    174 	if (_ksem_destroy((*sem)->ksem_semid) == -1)
    175 		return (-1);
    176 
    177 	sem_free(*sem);
    178 
    179 	return (0);
    180 }
    181 
    182 sem_t *
    183 sem_open(const char *name, int oflag, ...)
    184 {
    185 	sem_t *sem, s;
    186 	intptr_t semid;
    187 	mode_t mode;
    188 	unsigned int value;
    189 	int error;
    190 	va_list ap;
    191 
    192 	mode = 0;
    193 	value = 0;
    194 
    195 	if (oflag & O_CREAT) {
    196 		va_start(ap, oflag);
    197 		mode = va_arg(ap, int);
    198 		value = va_arg(ap, unsigned int);
    199 		va_end(ap);
    200 	}
    201 
    202 	/*
    203 	 * We can be lazy and let the kernel handle the oflag,
    204 	 * we'll just merge duplicate IDs into our list.
    205 	 */
    206 	if (_ksem_open(name, oflag, mode, value, &semid) == -1)
    207 		return (SEM_FAILED);
    208 
    209 	/*
    210 	 * Search for a duplicate ID, we must return the same sem_t *
    211 	 * if we locate one.
    212 	 */
    213 	LIST_FOREACH(s, &named_sems, ksem_list) {
    214 		if (s->ksem_semid == semid)
    215 			return (s->ksem_identity);
    216 	}
    217 
    218 	if ((sem = malloc(sizeof(*sem))) == NULL) {
    219 		error = ENOSPC;
    220 		goto bad;
    221 	}
    222 	if ((error = sem_alloc(value, semid, sem)) != 0)
    223 		goto bad;
    224 
    225 	LIST_INSERT_HEAD(&named_sems, *sem, ksem_list);
    226 	(*sem)->ksem_identity = sem;
    227 
    228 	return (sem);
    229 
    230  bad:
    231 	_ksem_close(semid);
    232 	if (sem != NULL) {
    233 		if (*sem != NULL)
    234 			sem_free(*sem);
    235 		free(sem);
    236 	}
    237 	errno = error;
    238 	return (SEM_FAILED);
    239 }
    240 
    241 int
    242 sem_close(sem_t *sem)
    243 {
    244 
    245 #ifdef ERRORCHECK
    246 	if (sem == NULL || *sem == NULL || (*sem)->ksem_magic != KSEM_MAGIC) {
    247 		errno = EINVAL;
    248 		return (-1);
    249 	}
    250 #endif
    251 
    252 	if (_ksem_close((*sem)->ksem_semid) == -1)
    253 		return (-1);
    254 
    255 	LIST_REMOVE((*sem), ksem_list);
    256 	sem_free(*sem);
    257 	free(sem);
    258 	return (0);
    259 }
    260 
    261 int
    262 sem_unlink(const char *name)
    263 {
    264 
    265 	return (_ksem_unlink(name));
    266 }
    267 
    268 int
    269 sem_wait(sem_t *sem)
    270 {
    271 
    272 #ifdef ERRORCHECK
    273 	if (sem == NULL || *sem == NULL || (*sem)->ksem_magic != KSEM_MAGIC) {
    274 		errno = EINVAL;
    275 		return (-1);
    276 	}
    277 #endif
    278 
    279 	return (_ksem_wait((*sem)->ksem_semid));
    280 }
    281 
    282 int
    283 sem_timedwait(sem_t *sem, const struct timespec * __restrict abstime)
    284 {
    285 
    286 #ifdef ERRORCHECK
    287 	if (sem == NULL || *sem == NULL || (*sem)->ksem_magic != KSEM_MAGIC) {
    288 		errno = EINVAL;
    289 		return (-1);
    290 	}
    291 #endif
    292 
    293 	return (_ksem_timedwait((*sem)->ksem_semid, abstime));
    294 }
    295 
    296 int
    297 sem_trywait(sem_t *sem)
    298 {
    299 
    300 #ifdef ERRORCHECK
    301 	if (sem == NULL || *sem == NULL || (*sem)->ksem_magic != KSEM_MAGIC) {
    302 		errno = EINVAL;
    303 		return (-1);
    304 	}
    305 #endif
    306 
    307 	return (_ksem_trywait((*sem)->ksem_semid));
    308 }
    309 
    310 int
    311 sem_post(sem_t *sem)
    312 {
    313 
    314 #ifdef ERRORCHECK
    315 	if (sem == NULL || *sem == NULL || (*sem)->ksem_magic != KSEM_MAGIC) {
    316 		errno = EINVAL;
    317 		return (-1);
    318 	}
    319 #endif
    320 
    321 	return (_ksem_post((*sem)->ksem_semid));
    322 }
    323 
    324 int
    325 sem_getvalue(sem_t * __restrict sem, int * __restrict sval)
    326 {
    327 
    328 #ifdef ERRORCHECK
    329 	if (sem == NULL || *sem == NULL || (*sem)->ksem_magic != KSEM_MAGIC) {
    330 		errno = EINVAL;
    331 		return (-1);
    332 	}
    333 #endif
    334 	return (_ksem_getvalue((*sem)->ksem_semid, sval));
    335 }
    336