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
44int
45ptw32_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 */
136