native_client_sdk/src/libraries/third_party/pthreads-win32/ptw32_semwait.c

   1 /*
   2  * ptw32_semwait.c
   3  *
   4  * Description:
   5  * This translation unit implements mutual exclusion (mutex) primitives.
   6  *
   7  * --------------------------------------------------------------------------
   8  *
   9  *      Pthreads-win32 - POSIX Threads Library for Win32
  10  *      Copyright(C) 1998 John E. Bossom
  11  *      Copyright(C) 1999,2005 Pthreads-win32 contributors
  12  *
  13  *      Contact Email: rpj@callisto.canberra.edu.au
  14  *
  15  *      The current list of contributors is contained
  16  *      in the file CONTRIBUTORS included with the source
  17  *      code distribution. The list can also be seen at the
  18  *      following World Wide Web location:
  19  *      http://sources.redhat.com/pthreads-win32/contributors.html
  20  *
  21  *      This library is free software; you can redistribute it and/or
  22  *      modify it under the terms of the GNU Lesser General Public
  23  *      License as published by the Free Software Foundation; either
  24  *      version 2 of the License, or (at your option) any later version.
  25  *
  26  *      This library is distributed in the hope that it will be useful,
  27  *      but WITHOUT ANY WARRANTY; without even the implied warranty of
  28  *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  29  *      Lesser General Public License for more details.
  30  *
  31  *      You should have received a copy of the GNU Lesser General Public
  32  *      License along with this library in the file COPYING.LIB;
  33  *      if not, write to the Free Software Foundation, Inc.,
  34  *      59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  35  */
  36
  37 #if !defined(_UWIN)
  38 /*#   include <process.h> */
  39 #endif
  40 #include "pthread.h"
  41 #include "implement.h"
  42
  43
  44 int
  45 ptw32_semwait (sem_t * sem)
  46      /*
  47       * ------------------------------------------------------
  48       * DESCRIPTION
  49       *      This function waits on a POSIX semaphore. If the
  50       *      semaphore value is greater than zero, it decreases
  51       *      its value by one. If the semaphore value is zero, then
  52       *      the calling thread (or process) is blocked until it can
  53       *      successfully decrease the value.
  54       *
  55       *      Unlike sem_wait(), this routine is non-cancelable.
  56       *
  57       * RESULTS
  58       *              0               successfully decreased semaphore,
  59       *              -1              failed, error in errno.
  60       * ERRNO
  61       *              EINVAL          'sem' is not a valid semaphore,
  62       *              ENOSYS          semaphores are not supported,
  63       *              EINTR           the function was interrupted by a signal,
  64       *              EDEADLK         a deadlock condition was detected.
  65       *
  66       * ------------------------------------------------------
  67       */
  68 {
  69   int result = 0;
  70   sem_t s = *sem;
  71
  72   if (s == NULL)
  73     {
  74       result = EINVAL;
  75     }
  76   else
  77     {
  78       if ((result = pthread_mutex_lock (&s->lock)) == 0)
  79         {
  80           int v;
  81
  82           /* See sem_destroy.c
  83            */
  84           if (*sem == NULL)
  85             {
  86               (void) pthread_mutex_unlock (&s->lock);
  87               errno = EINVAL;
  88               return -1;
  89             }
  90
  91           v = --s->value;
  92           (void) pthread_mutex_unlock (&s->lock);
  93
  94           if (v < 0)
  95             {
  96               /* Must wait */
  97               if (WaitForSingleObject (s->sem, INFINITE) == WAIT_OBJECT_0)
  98                 {
  99 #if defined(NEED_SEM)
 100                   if (pthread_mutex_lock (&s->lock) == 0)
 101                     {
 102                       if (*sem == NULL)
 103                         {
 104                           (void) pthread_mutex_unlock (&s->lock);
 105                           errno = EINVAL;
 106                           return -1;
 107                         }
 108
 109                       if (s->leftToUnblock > 0)
 110                         {
 111                           --s->leftToUnblock;
 112                           SetEvent(s->sem);
 113                         }
 114                       (void) pthread_mutex_unlock (&s->lock);
 115                     }
 116 #endif
 117                   return 0;
 118                 }
 119             }
 120           else
 121             {
 122               return 0;
 123             }
 124         }
 125     }
 126
 127   if (result != 0)
 128     {
 129       errno = result;
 130       return -1;
 131     }
 132
 133   return 0;
 134
 135 }                               /* ptw32_semwait */