1 /* 2 * pthread_rwlock_unlock.c 3 * 4 * Description: 5 * This translation unit implements read/write lock 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 #include <limits.h> 38 39 #include "pthread.h" 40 #include "implement.h" 41 42 int 43 pthread_rwlock_unlock (pthread_rwlock_t * rwlock) 44 { 45 int result, result1; 46 pthread_rwlock_t rwl; 47 48 if (rwlock == NULL || *rwlock == NULL) 49 { 50 return (EINVAL); 51 } 52 53 if (*rwlock == PTHREAD_RWLOCK_INITIALIZER) 54 { 55 /* 56 * Assume any race condition here is harmless. 57 */ 58 return 0; 59 } 60 61 rwl = *rwlock; 62 63 if (rwl->nMagic != PTW32_RWLOCK_MAGIC) 64 { 65 return EINVAL; 66 } 67 68 if (rwl->nExclusiveAccessCount == 0) 69 { 70 if ((result = 71 pthread_mutex_lock (&(rwl->mtxSharedAccessCompleted))) != 0) 72 { 73 return result; 74 } 75 76 if (++rwl->nCompletedSharedAccessCount == 0) 77 { 78 result = pthread_cond_signal (&(rwl->cndSharedAccessCompleted)); 79 } 80 81 result1 = pthread_mutex_unlock (&(rwl->mtxSharedAccessCompleted)); 82 } 83 else 84 { 85 rwl->nExclusiveAccessCount--; 86 87 result = pthread_mutex_unlock (&(rwl->mtxSharedAccessCompleted)); 88 result1 = pthread_mutex_unlock (&(rwl->mtxExclusiveAccess)); 89 90 } 91 92 return ((result != 0) ? result : result1); 93 } 94