usr/src/lib/libc/port/rt/sem.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21
  22 /*
  23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 #pragma ident   "%Z%%M% %I%     %E% SMI"
  28
  29 #include "lint.h"
  30 #include "mtlib.h"
  31 #include <sys/types.h>
  32 #include <semaphore.h>
  33 #include <synch.h>
  34 #include <errno.h>
  35 #include <stdarg.h>
  36 #include <limits.h>
  37 #include <stdlib.h>
  38 #include <string.h>
  39 #include <sys/stat.h>
  40 #include <sys/mman.h>
  41 #include <unistd.h>
  42 #include <thread.h>
  43 #include "pos4obj.h"
  44
  45 typedef struct  semaddr {
  46         struct  semaddr *sad_next;      /* next in the link */
  47         char            sad_name[PATH_MAX + 1]; /* name of sem object */
  48         sem_t           *sad_addr;      /* mmapped address of semaphore */
  49         ino64_t         sad_inode;      /* inode # of the mmapped file */
  50 } semaddr_t;
  51
  52 static long semvaluemax = 0;
  53 static semaddr_t *semheadp = NULL;
  54 static mutex_t semlock = DEFAULTMUTEX;
  55
  56 sem_t *
  57 sem_open(const char *path, int oflag, /* mode_t mode, int value */ ...)
  58 {
  59         va_list ap;
  60         mode_t  crmode = 0;
  61         sem_t   *sem = NULL;
  62         struct  stat statbuf;
  63         semaddr_t *next = NULL;
  64         int     fd = 0;
  65         int     error = 0;
  66         int     cr_flag = 0;
  67         uint_t  value = 0;
  68
  69         if (__pos4obj_check(path) == -1)
  70                 return (SEM_FAILED);
  71
  72         /* acquire semaphore lock to have atomic operation */
  73         if (__pos4obj_lock(path, SEM_LOCK_TYPE) < 0)
  74                 return (SEM_FAILED);
  75
  76         /* modify oflag to have RDWR and filter CREATE mode only */
  77         oflag = (oflag & (O_CREAT|O_EXCL)) | (O_RDWR);
  78         if (oflag & O_CREAT) {
  79                 if (semvaluemax == 0 &&
  80                     (semvaluemax = _sysconf(_SC_SEM_VALUE_MAX)) <= 0)
  81                         semvaluemax = -1;
  82                 va_start(ap, oflag);
  83                 crmode = va_arg(ap, mode_t);
  84                 value = va_arg(ap, uint_t);
  85                 va_end(ap);
  86                 /* check value < the max for a named semaphore */
  87                 if (semvaluemax < 0 ||
  88                     (ulong_t)value > (ulong_t)semvaluemax) {
  89                         errno = EINVAL;
  90                         goto out;
  91                 }
  92         }
  93
  94         errno = 0;
  95
  96         if ((fd = __pos4obj_open(path, SEM_DATA_TYPE,
  97             oflag, crmode, &cr_flag)) < 0)
  98                 goto out;
  99
 100         if (cr_flag)
 101                 cr_flag = DFILE_CREATE | DFILE_OPEN;
 102         else
 103                 cr_flag = DFILE_OPEN;
 104
 105         /* find out inode # for the opened file */
 106         if (fstat(fd, &statbuf) < 0)
 107                 goto out;
 108
 109         /* if created, acquire total_size in the file */
 110         if ((cr_flag & DFILE_CREATE) != 0) {
 111                 if (ftruncate(fd, (off64_t)sizeof (sem_t)) < 0)
 112                         goto out;
 113         } else {
 114                 /*
 115                  * if this semaphore has already been opened, inode
 116                  * will indicate then return the same semaphore address
 117                  */
 118                 lmutex_lock(&semlock);
 119                 for (next = semheadp; next != NULL; next = next->sad_next) {
 120                         if (statbuf.st_ino == next->sad_inode &&
 121                             strcmp(path, next->sad_name) == 0) {
 122                                 (void) __close_nc(fd);
 123                                 lmutex_unlock(&semlock);
 124                                 (void) __pos4obj_unlock(path, SEM_LOCK_TYPE);
 125                                 return (next->sad_addr);
 126                         }
 127                 }
 128                 lmutex_unlock(&semlock);
 129         }
 130
 131
 132         /* new sem descriptor to be allocated and new address to be mapped */
 133         if ((next = malloc(sizeof (semaddr_t))) == NULL) {
 134                 errno = ENOMEM;
 135                 goto out;
 136         }
 137         cr_flag |= ALLOC_MEM;
 138
 139         /* LINTED */
 140         sem = mmap(NULL, sizeof (sem_t), PROT_READ|PROT_WRITE,
 141             MAP_SHARED, fd, (off64_t)0);
 142         (void) __close_nc(fd);
 143         cr_flag &= ~DFILE_OPEN;
 144         if (sem == MAP_FAILED)
 145                 goto out;
 146         cr_flag |= DFILE_MMAP;
 147
 148         /* if created, initialize */
 149         if (cr_flag & DFILE_CREATE) {
 150                 error = sema_init((sema_t *)sem, value, USYNC_PROCESS, 0);
 151                 if (error) {
 152                         errno = error;
 153                         goto out;
 154                 }
 155         }
 156
 157         if (__pos4obj_unlock(path, SEM_LOCK_TYPE) == 0) {
 158                 /* add to the list pointed by semheadp */
 159                 lmutex_lock(&semlock);
 160                 next->sad_next = semheadp;
 161                 semheadp = next;
 162                 next->sad_addr = sem;
 163                 next->sad_inode = statbuf.st_ino;
 164                 (void) strcpy(next->sad_name, path);
 165                 lmutex_unlock(&semlock);
 166                 return (sem);
 167         }
 168         /* fall into the error case */
 169 out:
 170         error = errno;
 171         if ((cr_flag & DFILE_OPEN) != 0)
 172                 (void) __close_nc(fd);
 173         if ((cr_flag & DFILE_CREATE) != 0)
 174                 (void) __pos4obj_unlink(path, SEM_DATA_TYPE);
 175         if ((cr_flag & ALLOC_MEM) != 0)
 176                 free(next);
 177         if ((cr_flag & DFILE_MMAP) != 0)
 178                 (void) munmap((caddr_t)sem, sizeof (sem_t));
 179         (void) __pos4obj_unlock(path, SEM_LOCK_TYPE);
 180         errno = error;
 181         return (SEM_FAILED);
 182 }
 183
 184 int
 185 sem_close(sem_t *sem)
 186 {
 187         semaddr_t       **next;
 188         semaddr_t       *freeit;
 189
 190         lmutex_lock(&semlock);
 191         for (next = &semheadp; (freeit = *next) != NULL;
 192             next = &(freeit->sad_next)) {
 193                 if (freeit->sad_addr == sem) {
 194                         *next = freeit->sad_next;
 195                         lmutex_unlock(&semlock);
 196                         free(freeit);
 197                         return (munmap((caddr_t)sem, sizeof (sem_t)));
 198                 }
 199         }
 200         lmutex_unlock(&semlock);
 201         errno = EINVAL;
 202         return (-1);
 203 }
 204
 205 int
 206 sem_unlink(const char *path)
 207 {
 208         int     error;
 209         int     oerrno;
 210
 211         if (__pos4obj_check(path) < 0)
 212                 return (-1);
 213
 214         if (__pos4obj_lock(path, SEM_LOCK_TYPE) < 0)
 215                 return (-1);
 216
 217         error =  __pos4obj_unlink(path, SEM_DATA_TYPE);
 218
 219         oerrno = errno;
 220
 221         (void) __pos4obj_unlock(path, SEM_LOCK_TYPE);
 222
 223         errno = oerrno;
 224
 225         return (error);
 226 }
 227
 228 /*
 229  * SUSV3 requires ("shall fail") an EINVAL failure for operations
 230  * on invalid semaphores, including uninitialized unnamed semaphores.
 231  * The best we can do is check that the magic number is correct.
 232  * This is not perfect, but it allows the test suite to pass.
 233  * (Standards bodies are filled with fools and idiots.)
 234  */
 235 static int
 236 sem_invalid(sem_t *sem)
 237 {
 238         if (sem->sem_magic != SEMA_MAGIC) {
 239                 errno = EINVAL;
 240                 return (-1);
 241         }
 242         return (0);
 243 }
 244
 245 int
 246 sem_init(sem_t *sem, int pshared, uint_t value)
 247 {
 248         int     error;
 249
 250         if ((error = sema_init((sema_t *)sem, value,
 251             pshared ? USYNC_PROCESS : USYNC_THREAD, NULL)) != 0) {
 252                 errno = error;
 253                 return (-1);
 254         }
 255         return (0);
 256 }
 257
 258 int
 259 sem_destroy(sem_t *sem)
 260 {
 261         int     error;
 262
 263         if (sem_invalid(sem))
 264                 return (-1);
 265         if ((error = sema_destroy((sema_t *)sem)) != 0) {
 266                 errno = error;
 267                 return (-1);
 268         }
 269         return (0);
 270 }
 271
 272 int
 273 sem_post(sem_t *sem)
 274 {
 275         int     error;
 276
 277         if (sem_invalid(sem))
 278                 return (-1);
 279         if ((error = sema_post((sema_t *)sem)) != 0) {
 280                 errno = error;
 281                 return (-1);
 282         }
 283         return (0);
 284 }
 285
 286 int
 287 sem_wait(sem_t *sem)
 288 {
 289         int     error;
 290
 291         if (sem_invalid(sem))
 292                 return (-1);
 293         if ((error = sema_wait((sema_t *)sem)) != 0) {
 294                 errno = error;
 295                 return (-1);
 296         }
 297         return (0);
 298 }
 299
 300 int
 301 sem_timedwait(sem_t *sem, const timespec_t *abstime)
 302 {
 303         int     error;
 304
 305         if (sem_invalid(sem))
 306                 return (-1);
 307         if ((error = sema_timedwait((sema_t *)sem, abstime)) != 0) {
 308                 if (error == ETIME)
 309                         error = ETIMEDOUT;
 310                 errno = error;
 311                 return (-1);
 312         }
 313         return (0);
 314 }
 315
 316 int
 317 sem_reltimedwait_np(sem_t *sem, const timespec_t *reltime)
 318 {
 319         int     error;
 320
 321         if (sem_invalid(sem))
 322                 return (-1);
 323         if ((error = sema_reltimedwait((sema_t *)sem, reltime)) != 0) {
 324                 if (error == ETIME)
 325                         error = ETIMEDOUT;
 326                 errno = error;
 327                 return (-1);
 328         }
 329         return (0);
 330 }
 331
 332 int
 333 sem_trywait(sem_t *sem)
 334 {
 335         int     error;
 336
 337         if (sem_invalid(sem))
 338                 return (-1);
 339         if ((error = sema_trywait((sema_t *)sem)) != 0) {
 340                 if (error == EBUSY)
 341                         error = EAGAIN;
 342                 errno = error;
 343                 return (-1);
 344         }
 345         return (0);
 346 }
 347
 348 int
 349 sem_getvalue(sem_t *sem, int *sval)
 350 {
 351         if (sem_invalid(sem))
 352                 return (-1);
 353         *sval = (int)sem->sem_count;
 354         return (0);
 355 }