/* * pthread_mutexattr.c * * Description: * This translation unit implements mutual exclusion (mutex) primitives. * * -------------------------------------------------------------------------- * * Pthreads-embedded (PTE) - POSIX Threads Library for embedded systems * Copyright(C) 2008 Jason Schmidlapp * * Contact Email: jschmidlapp@users.sourceforge.net * * * Based upon Pthreads-win32 - POSIX Threads Library for Win32 * Copyright(C) 1998 John E. Bossom * Copyright(C) 1999,2005 Pthreads-win32 contributors * * Contact Email: rpj@callisto.canberra.edu.au * * The original list of contributors to the Pthreads-win32 project * is contained in the file CONTRIBUTORS.ptw32 included with the * source code distribution. The list can also be seen at the * following World Wide Web location: * http://sources.redhat.com/pthreads-win32/contributors.html * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2 of the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library in the file COPYING.LIB; * if not, write to the Free Software Foundation, Inc., * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA */ #include #include "pthread.h" #include "implement.h" int pthread_mutexattr_destroy (pthread_mutexattr_t * attr) /* * ------------------------------------------------------ * DOCPUBLIC * Destroys a mutex attributes object. The object can * no longer be used. * * PARAMETERS * attr * pointer to an instance of pthread_mutexattr_t * * * DESCRIPTION * Destroys a mutex attributes object. The object can * no longer be used. * * NOTES: * 1) Does not affect mutexes created using 'attr' * * RESULTS * 0 successfully released attr, * EINVAL 'attr' is invalid. * * ------------------------------------------------------ */ { int result = 0; if (attr == NULL || *attr == NULL) result = EINVAL; else { pthread_mutexattr_t ma = *attr; *attr = NULL; free (ma); } return (result); } int pthread_mutexattr_getkind_np (pthread_mutexattr_t * attr, int *kind) { return pthread_mutexattr_gettype (attr, kind); } int pthread_mutexattr_gettype (pthread_mutexattr_t * attr, int *kind) { int result = 0; if (attr != NULL && *attr != NULL && kind != NULL) *kind = (*attr)->kind; else result = EINVAL; return (result); } int pthread_mutexattr_getpshared (const pthread_mutexattr_t * attr, int *pshared) /* * ------------------------------------------------------ * DOCPUBLIC * Determine whether mutexes created with 'attr' can be * shared between processes. * * PARAMETERS * attr * pointer to an instance of pthread_mutexattr_t * * pshared * will be set to one of: * * PTHREAD_PROCESS_SHARED * May be shared if in shared memory * * PTHREAD_PROCESS_PRIVATE * Cannot be shared. * * * DESCRIPTION * Mutexes creatd with 'attr' can be shared between * processes if pthread_mutex_t variable is allocated * in memory shared by these processes. * NOTES: * 1) pshared mutexes MUST be allocated in shared * memory. * 2) The following macro is defined if shared mutexes * are supported: * _POSIX_THREAD_PROCESS_SHARED * * RESULTS * 0 successfully retrieved attribute, * EINVAL 'attr' is invalid, * * ------------------------------------------------------ */ { int result; if ((attr != NULL && *attr != NULL) && (pshared != NULL)) { *pshared = (*attr)->pshared; result = 0; } else result = EINVAL; return (result); } int pthread_mutexattr_init (pthread_mutexattr_t * attr) /* * ------------------------------------------------------ * DOCPUBLIC * Initializes a mutex attributes object with default * attributes. * * PARAMETERS * attr * pointer to an instance of pthread_mutexattr_t * * * DESCRIPTION * Initializes a mutex attributes object with default * attributes. * * NOTES: * 1) Used to define mutex types * * RESULTS * 0 successfully initialized attr, * ENOMEM insufficient memory for attr. * * ------------------------------------------------------ */ { int result = 0; pthread_mutexattr_t ma = (pthread_mutexattr_t) calloc (1, sizeof (*ma)); if (ma == NULL) result = ENOMEM; else { ma->pshared = PTHREAD_PROCESS_PRIVATE; ma->kind = PTHREAD_MUTEX_DEFAULT; } *attr = ma; return (result); } int pthread_mutexattr_setkind_np (pthread_mutexattr_t * attr, int kind) { return pthread_mutexattr_settype (attr, kind); } int pthread_mutexattr_setpshared (pthread_mutexattr_t * attr, int pshared) /* * ------------------------------------------------------ * DOCPUBLIC * Mutexes created with 'attr' can be shared between * processes if pthread_mutex_t variable is allocated * in memory shared by these processes. * * PARAMETERS * attr * pointer to an instance of pthread_mutexattr_t * * pshared * must be one of: * * PTHREAD_PROCESS_SHARED * May be shared if in shared memory * * PTHREAD_PROCESS_PRIVATE * Cannot be shared. * * DESCRIPTION * Mutexes creatd with 'attr' can be shared between * processes if pthread_mutex_t variable is allocated * in memory shared by these processes. * * NOTES: * 1) pshared mutexes MUST be allocated in shared * memory. * * 2) The following macro is defined if shared mutexes * are supported: * _POSIX_THREAD_PROCESS_SHARED * * RESULTS * 0 successfully set attribute, * EINVAL 'attr' or pshared is invalid, * ENOSYS PTHREAD_PROCESS_SHARED not supported, * * ------------------------------------------------------ */ { int result; if ((attr != NULL && *attr != NULL) && ((pshared == PTHREAD_PROCESS_SHARED) || (pshared == PTHREAD_PROCESS_PRIVATE))) { if (pshared == PTHREAD_PROCESS_SHARED) { #if !defined( _POSIX_THREAD_PROCESS_SHARED ) result = ENOSYS; pshared = PTHREAD_PROCESS_PRIVATE; #else result = 0; #endif /* _POSIX_THREAD_PROCESS_SHARED */ } else result = 0; (*attr)->pshared = pshared; } else result = EINVAL; return (result); } int pthread_mutexattr_settype (pthread_mutexattr_t * attr, int kind) /* * ------------------------------------------------------ * * DOCPUBLIC * The pthread_mutexattr_settype() and * pthread_mutexattr_gettype() functions respectively set and * get the mutex type attribute. This attribute is set in the * type parameter to these functions. * * PARAMETERS * attr * pointer to an instance of pthread_mutexattr_t * * type * must be one of: * * PTHREAD_MUTEX_DEFAULT * * PTHREAD_MUTEX_NORMAL * * PTHREAD_MUTEX_ERRORCHECK * * PTHREAD_MUTEX_RECURSIVE * * DESCRIPTION * The pthread_mutexattr_settype() and * pthread_mutexattr_gettype() functions respectively set and * get the mutex type attribute. This attribute is set in the * type parameter to these functions. The default value of the * type attribute is PTHREAD_MUTEX_DEFAULT. * * The type of mutex is contained in the type attribute of the * mutex attributes. Valid mutex types include: * * PTHREAD_MUTEX_NORMAL * This type of mutex does not detect deadlock. A * thread attempting to relock this mutex without * first unlocking it will deadlock. Attempting to * unlock a mutex locked by a different thread * results in undefined behavior. Attempting to * unlock an unlocked mutex results in undefined * behavior. * * PTHREAD_MUTEX_ERRORCHECK * This type of mutex provides error checking. A * thread attempting to relock this mutex without * first unlocking it will return with an error. A * thread attempting to unlock a mutex which another * thread has locked will return with an error. A * thread attempting to unlock an unlocked mutex will * return with an error. * * PTHREAD_MUTEX_DEFAULT * Same as PTHREAD_MUTEX_NORMAL. * * PTHREAD_MUTEX_RECURSIVE * A thread attempting to relock this mutex without * first unlocking it will succeed in locking the * mutex. The relocking deadlock which can occur with * mutexes of type PTHREAD_MUTEX_NORMAL cannot occur * with this type of mutex. Multiple locks of this * mutex require the same number of unlocks to * release the mutex before another thread can * acquire the mutex. A thread attempting to unlock a * mutex which another thread has locked will return * with an error. A thread attempting to unlock an * unlocked mutex will return with an error. This * type of mutex is only supported for mutexes whose * process shared attribute is * PTHREAD_PROCESS_PRIVATE. * * RESULTS * 0 successfully set attribute, * EINVAL 'attr' or 'type' is invalid, * * ------------------------------------------------------ */ { int result = 0; if ((attr != NULL && *attr != NULL)) { switch (kind) { case PTHREAD_MUTEX_FAST_NP: case PTHREAD_MUTEX_RECURSIVE_NP: case PTHREAD_MUTEX_ERRORCHECK_NP: (*attr)->kind = kind; break; default: result = EINVAL; break; } } else result = EINVAL; return (result); }