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 (at) 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 */ 136
