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

   1 /*
   2  * -------------------------------------------------------------
   3  *
   4  * Module: sem_post.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_post (sem_t * sem)
  51      /*
  52       * ------------------------------------------------------
  53       * DOCPUBLIC
  54       *      This function posts a wakeup to a semaphore.
  55       *
  56       * PARAMETERS
  57       *      sem
  58       *              pointer to an instance of sem_t
  59       *
  60       * DESCRIPTION
  61       *      This function posts a wakeup to a semaphore. If there
  62       *      are waiting threads (or processes), one is awakened;
  63       *      otherwise, the semaphore value is incremented by one.
  64       *
  65       * RESULTS
  66       *              0               successfully posted semaphore,
  67       *              -1              failed, error in errno
  68       * ERRNO
  69       *              EINVAL          'sem' is not a valid semaphore,
  70       *              ENOSYS          semaphores are not supported,
  71       *              ERANGE          semaphore count is too big
  72       *
  73       * ------------------------------------------------------
  74       */
  75 {
  76   int result = 0;
  77   sem_t s = *sem;
  78
  79   if (s == NULL)
  80     {
  81       result = EINVAL;
  82     }
  83   else if ((result = pthread_mutex_lock (&s->lock)) == 0)
  84     {
  85       /* See sem_destroy.c
  86        */
  87       if (*sem == NULL)
  88         {
  89           (void) pthread_mutex_unlock (&s->lock);
  90           result = EINVAL;
  91           return -1;
  92         }
  93
  94       if (s->value < SEM_VALUE_MAX)
  95         {
  96 #if defined(NEED_SEM)
  97           if (++s->value <= 0
  98               && !SetEvent(s->sem))
  99             {
 100               s->value--;
 101               result = EINVAL;
 102             }
 103 #else
 104           if (++s->value <= 0
 105               && !ReleaseSemaphore (s->sem, 1, NULL))
 106             {
 107               s->value--;
 108               result = EINVAL;
 109             }
 110 #endif /* NEED_SEM */
 111         }
 112       else
 113         {
 114           result = ERANGE;
 115         }
 116
 117       (void) pthread_mutex_unlock (&s->lock);
 118     }
 119
 120   if (result != 0)
 121     {
 122       errno = result;
 123       return -1;
 124     }
 125
 126   return 0;
 127
 128 }                               /* sem_post */