1/*
2 * pthread_mutex_destroy.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#include "pthread.h"
38#include "implement.h"
39
40
41int
42pthread_mutex_destroy (pthread_mutex_t * mutex)
43{
44  int result = 0;
45  pthread_mutex_t mx;
46
47  /*
48   * Let the system deal with invalid pointers.
49   */
50
51  /*
52   * Check to see if we have something to delete.
53   */
54  if (*mutex < PTHREAD_ERRORCHECK_MUTEX_INITIALIZER)
55    {
56      mx = *mutex;
57
58      result = pthread_mutex_trylock (&mx);
59
60      /*
61       * If trylock succeeded and the mutex is not recursively locked it
62       * can be destroyed.
63       */
64      if (0 == result || ENOTRECOVERABLE == result)
65	{
66	  if (mx->kind != PTHREAD_MUTEX_RECURSIVE || 1 == mx->recursive_count)
67	    {
68	      /*
69	       * FIXME!!!
70	       * The mutex isn't held by another thread but we could still
71	       * be too late invalidating the mutex below since another thread
72	       * may already have entered mutex_lock and the check for a valid
73	       * *mutex != NULL.
74	       */
75	      *mutex = NULL;
76
77	      result = (0 == result)?pthread_mutex_unlock(&mx):0;
78
79	      if (0 == result)
80		{
81                  if (mx->robustNode != NULL)
82                    {
83                      free(mx->robustNode);
84                    }
85		  if (!CloseHandle (mx->event))
86		    {
87		      *mutex = mx;
88		      result = EINVAL;
89		    }
90		  else
91		    {
92		      free (mx);
93		    }
94		}
95	      else
96		{
97		  /*
98		   * Restore the mutex before we return the error.
99		   */
100		  *mutex = mx;
101		}
102	    }
103	  else			/* mx->recursive_count > 1 */
104	    {
105	      /*
106	       * The mutex must be recursive and already locked by us (this thread).
107	       */
108	      mx->recursive_count--;	/* Undo effect of pthread_mutex_trylock() above */
109	      result = EBUSY;
110	    }
111	}
112    }
113  else
114    {
115      ptw32_mcs_local_node_t node;
116
117      /*
118       * See notes in ptw32_mutex_check_need_init() above also.
119       */
120
121      ptw32_mcs_lock_acquire(&ptw32_mutex_test_init_lock, &node);
122
123      /*
124       * Check again.
125       */
126      if (*mutex >= PTHREAD_ERRORCHECK_MUTEX_INITIALIZER)
127	{
128	  /*
129	   * This is all we need to do to destroy a statically
130	   * initialised mutex that has not yet been used (initialised).
131	   * If we get to here, another thread
132	   * waiting to initialise this mutex will get an EINVAL.
133	   */
134	  *mutex = NULL;
135	}
136      else
137	{
138	  /*
139	   * The mutex has been initialised while we were waiting
140	   * so assume it's in use.
141	   */
142	  result = EBUSY;
143	}
144      ptw32_mcs_lock_release(&node);
145    }
146
147  return (result);
148}
149