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 (at) 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 */ 145
