mono/io-layer/semaphores.c

   1 /*
   2  * semaphores.c:  Semaphore handles
   3  *
   4  * Author:
   5  *      Dick Porter (dick@ximian.com)
   6  *
   7  * (C) 2002 Ximian, Inc.
   8  */
   9
  10 #include <config.h>
  11 #include <glib.h>
  12 #include <pthread.h>
  13 #ifdef HAVE_SEMAPHORE_H
  14 #include <semaphore.h>
  15 #endif
  16 #include <errno.h>
  17 #include <string.h>
  18 #include <sys/time.h>
  19
  20 #include <mono/io-layer/wapi.h>
  21 #include <mono/io-layer/wapi-private.h>
  22 #include <mono/io-layer/misc-private.h>
  23 #include <mono/io-layer/handles-private.h>
  24 #include <mono/io-layer/semaphore-private.h>
  25
  26 #include <mono/utils/mono-mutex.h>
  27
  28 #if 0
  29 #define DEBUG(...) g_message(__VA_ARGS__)
  30 #else
  31 #define DEBUG(...)
  32 #endif
  33
  34 static void sema_signal(gpointer handle);
  35 static gboolean sema_own (gpointer handle);
  36
  37 static void namedsema_signal (gpointer handle);
  38 static gboolean namedsema_own (gpointer handle);
  39
  40 struct _WapiHandleOps _wapi_sem_ops = {
  41         NULL,                   /* close */
  42         sema_signal,            /* signal */
  43         sema_own,               /* own */
  44         NULL,                   /* is_owned */
  45         NULL,                   /* special_wait */
  46         NULL                    /* prewait */
  47 };
  48
  49 void _wapi_sem_details (gpointer handle_info)
  50 {
  51         struct _WapiHandle_sem *sem = (struct _WapiHandle_sem *)handle_info;
  52
  53         g_print ("val: %5u, max: %5d", sem->val, sem->max);
  54 }
  55
  56 struct _WapiHandleOps _wapi_namedsem_ops = {
  57         NULL,                   /* close */
  58         namedsema_signal,       /* signal */
  59         namedsema_own,          /* own */
  60         NULL,                   /* is_owned */
  61         NULL,                   /* special_wait */
  62         NULL                    /* prewait */
  63 };
  64
  65 static gboolean sem_release (gpointer handle, gint32 count, gint32 *prev);
  66 static gboolean namedsem_release (gpointer handle, gint32 count, gint32 *prev);
  67
  68 static struct
  69 {
  70         gboolean (*release)(gpointer handle, gint32 count, gint32 *prev);
  71 } sem_ops[WAPI_HANDLE_COUNT] = {
  72         {NULL},
  73         {NULL},
  74         {NULL},
  75         {NULL},
  76         {sem_release},
  77         {NULL},
  78         {NULL},
  79         {NULL},
  80         {NULL},
  81         {NULL},
  82         {NULL},
  83         {NULL},
  84         {namedsem_release},
  85 };
  86
  87 static mono_once_t sem_ops_once=MONO_ONCE_INIT;
  88
  89 static void sem_ops_init (void)
  90 {
  91         _wapi_handle_register_capabilities (WAPI_HANDLE_SEM,
  92                                             WAPI_HANDLE_CAP_WAIT |
  93                                             WAPI_HANDLE_CAP_SIGNAL);
  94         _wapi_handle_register_capabilities (WAPI_HANDLE_NAMEDSEM,
  95                                             WAPI_HANDLE_CAP_WAIT |
  96                                             WAPI_HANDLE_CAP_SIGNAL);
  97 }
  98
  99 static void sema_signal(gpointer handle)
 100 {
 101         ReleaseSemaphore(handle, 1, NULL);
 102 }
 103
 104 static gboolean sema_own (gpointer handle)
 105 {
 106         struct _WapiHandle_sem *sem_handle;
 107         gboolean ok;
 108
 109         ok=_wapi_lookup_handle (handle, WAPI_HANDLE_SEM,
 110                                 (gpointer *)&sem_handle);
 111         if(ok==FALSE) {
 112                 g_warning ("%s: error looking up sem handle %p", __func__,
 113                            handle);
 114                 return(FALSE);
 115         }
 116
 117         DEBUG("%s: owning sem handle %p", __func__, handle);
 118
 119         sem_handle->val--;
 120
 121         DEBUG ("%s: sem %p val now %d", __func__, handle, sem_handle->val);
 122
 123         if(sem_handle->val==0) {
 124                 _wapi_handle_set_signal_state (handle, FALSE, FALSE);
 125         }
 126
 127         return(TRUE);
 128 }
 129
 130 static void namedsema_signal (gpointer handle)
 131 {
 132         ReleaseSemaphore (handle, 1, NULL);
 133 }
 134
 135 /* NB, always called with the shared handle lock held */
 136 static gboolean namedsema_own (gpointer handle)
 137 {
 138         struct _WapiHandle_namedsem *namedsem_handle;
 139         gboolean ok;
 140
 141         DEBUG ("%s: owning named sem handle %p", __func__, handle);
 142
 143         ok = _wapi_lookup_handle (handle, WAPI_HANDLE_NAMEDSEM,
 144                                   (gpointer *)&namedsem_handle);
 145         if (ok == FALSE) {
 146                 g_warning ("%s: error looking up named sem handle %p",
 147                            __func__, handle);
 148                 return (FALSE);
 149         }
 150
 151         namedsem_handle->val--;
 152
 153         DEBUG ("%s: named sem %p val now %d", __func__, handle,
 154                    namedsem_handle->val);
 155
 156         if (namedsem_handle->val == 0) {
 157                 _wapi_shared_handle_set_signal_state (handle, FALSE);
 158         }
 159
 160         return (TRUE);
 161 }
 162 static gpointer sem_create (WapiSecurityAttributes *security G_GNUC_UNUSED,
 163                             gint32 initial, gint32 max)
 164 {
 165         struct _WapiHandle_sem sem_handle = {0};
 166         gpointer handle;
 167         int thr_ret;
 168
 169         /* Need to blow away any old errors here, because code tests
 170          * for ERROR_ALREADY_EXISTS on success (!) to see if a
 171          * semaphore was freshly created
 172          */
 173         SetLastError (ERROR_SUCCESS);
 174
 175         sem_handle.val = initial;
 176         sem_handle.max = max;
 177
 178         handle = _wapi_handle_new (WAPI_HANDLE_SEM, &sem_handle);
 179         if (handle == _WAPI_HANDLE_INVALID) {
 180                 g_warning ("%s: error creating semaphore handle", __func__);
 181                 SetLastError (ERROR_GEN_FAILURE);
 182                 return(NULL);
 183         }
 184
 185         thr_ret = _wapi_handle_lock_handle (handle);
 186         g_assert (thr_ret == 0);
 187
 188         if (initial != 0) {
 189                 _wapi_handle_set_signal_state (handle, TRUE, FALSE);
 190         }
 191
 192         DEBUG ("%s: Created semaphore handle %p initial %d max %d",
 193                    __func__, handle, initial, max);
 194
 195         thr_ret = _wapi_handle_unlock_handle (handle);
 196         g_assert (thr_ret == 0);
 197
 198         return(handle);
 199 }
 200
 201 static gpointer namedsem_create (WapiSecurityAttributes *security G_GNUC_UNUSED, gint32 initial, gint32 max, const gunichar2 *name G_GNUC_UNUSED)
 202 {
 203         struct _WapiHandle_namedsem namedsem_handle = {{{0}}, 0};
 204         gpointer handle;
 205         gchar *utf8_name;
 206         int thr_ret;
 207         gpointer ret = NULL;
 208         guint32 namelen;
 209         gint32 offset;
 210
 211         /* w32 seems to guarantee that opening named objects can't
 212          * race each other
 213          */
 214         thr_ret = _wapi_namespace_lock ();
 215         g_assert (thr_ret == 0);
 216
 217         /* Need to blow away any old errors here, because code tests
 218          * for ERROR_ALREADY_EXISTS on success (!) to see if a
 219          * semaphore was freshly created
 220          */
 221         SetLastError (ERROR_SUCCESS);
 222
 223         utf8_name = g_utf16_to_utf8 (name, -1, NULL, NULL, NULL);
 224
 225         DEBUG ("%s: Creating named sem [%s]", __func__, utf8_name);
 226
 227         offset = _wapi_search_handle_namespace (WAPI_HANDLE_NAMEDSEM,
 228                                                 utf8_name);
 229         if (offset == -1) {
 230                 /* The name has already been used for a different
 231                  * object.
 232                  */
 233                 SetLastError (ERROR_INVALID_HANDLE);
 234                 goto cleanup;
 235         } else if (offset != 0) {
 236                 /* Not an error, but this is how the caller is
 237                  * informed that the semaphore wasn't freshly created
 238                  */
 239                 SetLastError (ERROR_ALREADY_EXISTS);
 240         }
 241         /* Fall through to create the semaphore handle */
 242
 243         if (offset == 0) {
 244                 /* A new named semaphore, so create both the private
 245                  * and shared parts
 246                  */
 247                 if (strlen (utf8_name) < MAX_PATH) {
 248                         namelen = strlen (utf8_name);
 249                 } else {
 250                         namelen = MAX_PATH;
 251                 }
 252
 253                 memcpy (&namedsem_handle.sharedns.name, utf8_name, namelen);
 254
 255                 namedsem_handle.val = initial;
 256                 namedsem_handle.max = max;
 257
 258                 handle = _wapi_handle_new (WAPI_HANDLE_NAMEDSEM,
 259                                            &namedsem_handle);
 260         } else {
 261                 /* A new reference to an existing named semaphore, so
 262                  * just create the private part
 263                  */
 264                 handle = _wapi_handle_new_from_offset (WAPI_HANDLE_NAMEDSEM,
 265                                                        offset, TRUE);
 266         }
 267
 268         if (handle == _WAPI_HANDLE_INVALID) {
 269                 g_warning ("%s: error creating named sem handle", __func__);
 270                 SetLastError (ERROR_GEN_FAILURE);
 271                 goto cleanup;
 272         }
 273         ret = handle;
 274
 275         if (offset == 0) {
 276                 /* Set the initial state, as this is a completely new
 277                  * handle
 278                  */
 279                 thr_ret = _wapi_handle_lock_shared_handles ();
 280                 g_assert (thr_ret == 0);
 281
 282                 if (initial != 0) {
 283                         _wapi_shared_handle_set_signal_state (handle, TRUE);
 284                 }
 285
 286                 _wapi_handle_unlock_shared_handles ();
 287         }
 288
 289         DEBUG ("%s: returning named sem handle %p", __func__, handle);
 290
 291 cleanup:
 292         g_free (utf8_name);
 293
 294         _wapi_namespace_unlock (NULL);
 295
 296         return (ret);
 297 }
 298
 299
 300 /**
 301  * CreateSemaphore:
 302  * @security: Ignored for now.
 303  * @initial: The initial count for the semaphore.  The value must be
 304  * greater than or equal to zero, and less than or equal to @max.
 305  * @max: The maximum count for this semaphore.  The value must be
 306  * greater than zero.
 307  * @name: Pointer to a string specifying the name of this semaphore,
 308  * or %NULL.  Currently ignored.
 309  *
 310  * Creates a new semaphore handle.  A semaphore is signalled when its
 311  * count is greater than zero, and unsignalled otherwise.  The count
 312  * is decreased by one whenever a wait function releases a thread that
 313  * was waiting for the semaphore.  The count is increased by calling
 314  * ReleaseSemaphore().
 315  *
 316  * Return value: a new handle, or NULL
 317  */
 318 gpointer CreateSemaphore(WapiSecurityAttributes *security G_GNUC_UNUSED, gint32 initial, gint32 max, const gunichar2 *name)
 319 {
 320         mono_once (&sem_ops_once, sem_ops_init);
 321
 322         if (max <= 0) {
 323                 DEBUG ("%s: max <= 0", __func__);
 324
 325                 SetLastError (ERROR_INVALID_PARAMETER);
 326                 return(NULL);
 327         }
 328
 329         if (initial > max || initial < 0) {
 330                 DEBUG ("%s: initial>max or < 0", __func__);
 331
 332                 SetLastError (ERROR_INVALID_PARAMETER);
 333                 return(NULL);
 334         }
 335
 336         if (name == NULL) {
 337                 return (sem_create (security, initial, max));
 338         } else {
 339                 return (namedsem_create (security, initial, max, name));
 340         }
 341 }
 342
 343 static gboolean sem_release (gpointer handle, gint32 count, gint32 *prevcount)
 344 {
 345         struct _WapiHandle_sem *sem_handle;
 346         gboolean ok;
 347         gboolean ret=FALSE;
 348         int thr_ret;
 349
 350         ok = _wapi_lookup_handle (handle, WAPI_HANDLE_SEM,
 351                                   (gpointer *)&sem_handle);
 352         if (ok == FALSE) {
 353                 g_warning ("%s: error looking up sem handle %p", __func__,
 354                            handle);
 355                 return(FALSE);
 356         }
 357
 358         thr_ret = _wapi_handle_lock_handle (handle);
 359         g_assert (thr_ret == 0);
 360
 361         DEBUG ("%s: sem %p val %d count %d", __func__, handle,
 362                    sem_handle->val, count);
 363
 364         /* Do this before checking for count overflow, because overflowing max
 365          * is a listed technique for finding the current value
 366          */
 367         if (prevcount != NULL) {
 368                 *prevcount = sem_handle->val;
 369         }
 370
 371         /* No idea why max is signed, but thats the spec :-( */
 372         if (sem_handle->val + count > (guint32)sem_handle->max) {
 373                 DEBUG ("%s: sem %p max value would be exceeded: max %d current %d count %d", __func__, handle, sem_handle->max, sem_handle->val, count);
 374
 375                 goto end;
 376         }
 377
 378         sem_handle->val += count;
 379         _wapi_handle_set_signal_state (handle, TRUE, TRUE);
 380
 381         ret = TRUE;
 382
 383         DEBUG ("%s: sem %p val now %d", __func__, handle, sem_handle->val);
 384
 385 end:
 386         thr_ret = _wapi_handle_unlock_handle (handle);
 387         g_assert (thr_ret == 0);
 388
 389         return(ret);
 390 }
 391
 392 static gboolean namedsem_release (gpointer handle, gint32 count,
 393                                   gint32 *prevcount)
 394 {
 395         struct _WapiHandle_namedsem *sem_handle;
 396         gboolean ok;
 397         gboolean ret=FALSE;
 398         int thr_ret;
 399
 400         ok = _wapi_lookup_handle (handle, WAPI_HANDLE_NAMEDSEM,
 401                                   (gpointer *)&sem_handle);
 402         if (ok == FALSE) {
 403                 g_warning ("%s: error looking up sem handle %p", __func__,
 404                            handle);
 405                 return(FALSE);
 406         }
 407
 408         thr_ret = _wapi_handle_lock_shared_handles ();
 409         g_assert (thr_ret == 0);
 410
 411         DEBUG("%s: named sem %p val %d count %d", __func__, handle,
 412                   sem_handle->val, count);
 413
 414         /* Do this before checking for count overflow, because overflowing max
 415          * is a listed technique for finding the current value
 416          */
 417         if (prevcount != NULL) {
 418                 *prevcount = sem_handle->val;
 419         }
 420
 421         /* No idea why max is signed, but thats the spec :-( */
 422         if (sem_handle->val + count > (guint32)sem_handle->max) {
 423                 DEBUG ("%s: named sem %p max value would be exceeded: max %d current %d count %d", __func__, handle, sem_handle->max, sem_handle->val, count);
 424
 425                 goto end;
 426         }
 427
 428         sem_handle->val += count;
 429         _wapi_shared_handle_set_signal_state (handle, TRUE);
 430
 431         ret = TRUE;
 432
 433         DEBUG("%s: named sem %p val now %d", __func__, handle,
 434                   sem_handle->val);
 435
 436 end:
 437         _wapi_handle_unlock_shared_handles ();
 438
 439         return(ret);
 440 }
 441
 442 /**
 443  * ReleaseSemaphore:
 444  * @handle: The semaphore handle to release.
 445  * @count: The amount by which the semaphore's count should be
 446  * increased.
 447  * @prevcount: Pointer to a location to store the previous count of
 448  * the semaphore, or %NULL.
 449  *
 450  * Increases the count of semaphore @handle by @count.
 451  *
 452  * Return value: %TRUE on success, %FALSE otherwise.
 453  */
 454 gboolean ReleaseSemaphore(gpointer handle, gint32 count, gint32 *prevcount)
 455 {
 456         WapiHandleType type;
 457
 458         if (handle == NULL) {
 459                 SetLastError (ERROR_INVALID_HANDLE);
 460                 return (FALSE);
 461         }
 462
 463         type = _wapi_handle_type (handle);
 464
 465         if (sem_ops[type].release == NULL) {
 466                 SetLastError (ERROR_INVALID_HANDLE);
 467                 return (FALSE);
 468         }
 469
 470         return (sem_ops[type].release (handle, count, prevcount));
 471 }
 472
 473 gpointer OpenSemaphore (guint32 access G_GNUC_UNUSED, gboolean inherit G_GNUC_UNUSED,
 474                         const gunichar2 *name)
 475 {
 476         gpointer handle;
 477         gchar *utf8_name;
 478         int thr_ret;
 479         gpointer ret = NULL;
 480         gint32 offset;
 481
 482         mono_once (&sem_ops_once, sem_ops_init);
 483
 484         /* w32 seems to guarantee that opening named objects can't
 485          * race each other
 486          */
 487         thr_ret = _wapi_namespace_lock ();
 488         g_assert (thr_ret == 0);
 489
 490         utf8_name = g_utf16_to_utf8 (name, -1, NULL, NULL, NULL);
 491
 492         DEBUG ("%s: Opening named sem [%s]", __func__, utf8_name);
 493
 494         offset = _wapi_search_handle_namespace (WAPI_HANDLE_NAMEDSEM,
 495                                                 utf8_name);
 496         if (offset == -1) {
 497                 /* The name has already been used for a different
 498                  * object.
 499                  */
 500                 SetLastError (ERROR_INVALID_HANDLE);
 501                 goto cleanup;
 502         } else if (offset == 0) {
 503                 /* This name doesn't exist */
 504                 SetLastError (ERROR_FILE_NOT_FOUND);    /* yes, really */
 505                 goto cleanup;
 506         }
 507
 508         /* A new reference to an existing named semaphore, so just
 509          * create the private part
 510          */
 511         handle = _wapi_handle_new_from_offset (WAPI_HANDLE_NAMEDSEM, offset,
 512                                                TRUE);
 513
 514         if (handle == _WAPI_HANDLE_INVALID) {
 515                 g_warning ("%s: error opening named sem handle", __func__);
 516                 SetLastError (ERROR_GEN_FAILURE);
 517                 goto cleanup;
 518         }
 519         ret = handle;
 520
 521         DEBUG ("%s: returning named sem handle %p", __func__, handle);
 522
 523 cleanup:
 524         g_free (utf8_name);
 525
 526         _wapi_namespace_unlock (NULL);
 527
 528         return (ret);
 529 }