native_client_sdk/src/libraries/third_party/pthreads-win32/sem_destroy.c

   1 /*
   2  * -------------------------------------------------------------
   3  *
   4  * Module: sem_destroy.c
   5  *
   6  * Purpose:
   7  *      Semaphores aren't actually part of the PThreads standard.
   8  *      They are defined by the POSIX Standard:
   9  *
  10  *              POSIX 1003.1b-1993      (POSIX.1b)
  11  *
  12  * -------------------------------------------------------------
  13  *
  14  * --------------------------------------------------------------------------
  15  *
  16  *      Pthreads-win32 - POSIX Threads Library for Win32
  17  *      Copyright(C) 1998 John E. Bossom
  18  *      Copyright(C) 1999,2005 Pthreads-win32 contributors
  19  *
  20  *      Contact Email: rpj@callisto.canberra.edu.au
  21  *
  22  *      The current list of contributors is contained
  23  *      in the file CONTRIBUTORS included with the source
  24  *      code distribution. The list can also be seen at the
  25  *      following World Wide Web location:
  26  *      http://sources.redhat.com/pthreads-win32/contributors.html
  27  *
  28  *      This library is free software; you can redistribute it and/or
  29  *      modify it under the terms of the GNU Lesser General Public
  30  *      License as published by the Free Software Foundation; either
  31  *      version 2 of the License, or (at your option) any later version.
  32  *
  33  *      This library is distributed in the hope that it will be useful,
  34  *      but WITHOUT ANY WARRANTY; without even the implied warranty of
  35  *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  36  *      Lesser General Public License for more details.
  37  *
  38  *      You should have received a copy of the GNU Lesser General Public
  39  *      License along with this library in the file COPYING.LIB;
  40  *      if not, write to the Free Software Foundation, Inc.,
  41  *      59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  42  */
  43
  44 #include "pthread.h"
  45 #include "semaphore.h"
  46 #include "implement.h"
  47
  48
  49 int
  50 sem_destroy (sem_t * sem)
  51      /*
  52       * ------------------------------------------------------
  53       * DOCPUBLIC
  54       *      This function destroys an unnamed semaphore.
  55       *
  56       * PARAMETERS
  57       *      sem
  58       *              pointer to an instance of sem_t
  59       *
  60       * DESCRIPTION
  61       *      This function destroys an unnamed semaphore.
  62       *
  63       * RESULTS
  64       *              0               successfully destroyed semaphore,
  65       *              -1              failed, error in errno
  66       * ERRNO
  67       *              EINVAL          'sem' is not a valid semaphore,
  68       *              ENOSYS          semaphores are not supported,
  69       *              EBUSY           threads (or processes) are currently
  70       *                                      blocked on 'sem'
  71       *
  72       * ------------------------------------------------------
  73       */
  74 {
  75   int result = 0;
  76   sem_t s = NULL;
  77
  78   if (sem == NULL || *sem == NULL)
  79     {
  80       result = EINVAL;
  81     }
  82   else
  83     {
  84       s = *sem;
  85
  86       if ((result = pthread_mutex_lock (&s->lock)) == 0)
  87         {
  88           if (s->value < 0)
  89             {
  90               (void) pthread_mutex_unlock (&s->lock);
  91               result = EBUSY;
  92             }
  93           else
  94             {
  95               /* There are no threads currently blocked on this semaphore. */
  96
  97               if (!CloseHandle (s->sem))
  98                 {
  99                   (void) pthread_mutex_unlock (&s->lock);
 100                   result = EINVAL;
 101                 }
 102               else
 103                 {
 104                   /*
 105                    * Invalidate the semaphore handle when we have the lock.
 106                    * Other sema operations should test this after acquiring the lock
 107                    * to check that the sema is still valid, i.e. before performing any
 108                    * operations. This may only be necessary before the sema op routine
 109                    * returns so that the routine can return EINVAL - e.g. if setting
 110                    * s->value to SEM_VALUE_MAX below does force a fall-through.
 111                    */
 112                   *sem = NULL;
 113
 114                   /* Prevent anyone else actually waiting on or posting this sema.
 115                    */
 116                   s->value = SEM_VALUE_MAX;
 117
 118                   (void) pthread_mutex_unlock (&s->lock);
 119
 120                   do
 121                     {
 122                       /* Give other threads a chance to run and exit any sema op
 123                        * routines. Due to the SEM_VALUE_MAX value, if sem_post or
 124                        * sem_wait were blocked by us they should fall through.
 125                        */
 126                       Sleep(0);
 127                     }
 128                   while (pthread_mutex_destroy (&s->lock) == EBUSY);
 129                 }
 130             }
 131         }
 132     }
 133
 134   if (result != 0)
 135     {
 136       errno = result;
 137       return -1;
 138     }
 139
 140   free (s);
 141
 142   return 0;
 143
 144 }                               /* sem_destroy */