lib/librt/sem.c

   1 /*      $NetBSD: sem.c,v 1.4 2008/04/28 20:23:02 martin 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@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 1.4 2008/04/28 20:23:02 martin 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 }