diff options
Diffstat (limited to 'rwlock.c')
| -rw-r--r-- | rwlock.c | 231 |
1 files changed, 231 insertions, 0 deletions
@@ -254,6 +254,237 @@ pthread_rwlock_destroy(pthread_rwlock_t *rwlock) return ((result != 0) ? result : ((result1 != 0) ? result1 : result2)); } + +int +pthread_rwlockattr_init (pthread_rwlockattr_t * attr) + /* + * ------------------------------------------------------ + * DOCPUBLIC + * Initializes a rwlock attributes object with default + * attributes. + * + * PARAMETERS + * attr + * pointer to an instance of pthread_rwlockattr_t + * + * + * DESCRIPTION + * Initializes a rwlock attributes object with default + * attributes. + * + * RESULTS + * 0 successfully initialized attr, + * ENOMEM insufficient memory for attr. + * + * ------------------------------------------------------ + */ +{ + int result = 0; + pthread_rwlockattr_t rwa; + + rwa = (pthread_rwlockattr_t) calloc (1, sizeof (*rwa)); + + if (rwa == NULL) + { + result = ENOMEM; + } + else + { + rwa->pshared = PTHREAD_PROCESS_PRIVATE; + } + + *attr = rwa; + + return(result); +} /* pthread_rwlockattr_init */ + + +int +pthread_rwlockattr_destroy (pthread_rwlockattr_t * attr) + /* + * ------------------------------------------------------ + * DOCPUBLIC + * Destroys a rwlock attributes object. The object can + * no longer be used. + * + * PARAMETERS + * attr + * pointer to an instance of pthread_rwlockattr_t + * + * + * DESCRIPTION + * Destroys a rwlock attributes object. The object can + * no longer be used. + * + * NOTES: + * 1) Does not affect rwlockss created using 'attr' + * + * RESULTS + * 0 successfully released attr, + * EINVAL 'attr' is invalid. + * + * ------------------------------------------------------ + */ +{ + int result = 0; + + if (attr == NULL || *attr == NULL) + { + result = EINVAL; + } + else + { + pthread_rwlockattr_t rwa = *attr; + + *attr = NULL; + free (rwa); + } + + return(result); +} /* pthread_rwlockattr_destroy */ + + +int +pthread_rwlockattr_getpshared (const pthread_rwlockattr_t * attr, + int *pshared) + /* + * ------------------------------------------------------ + * DOCPUBLIC + * Determine whether rwlocks created with 'attr' can be + * shared between processes. + * + * PARAMETERS + * attr + * pointer to an instance of pthread_rwlockattr_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 + * Rwlocks creatd with 'attr' can be shared between + * processes if pthread_rwlock_t variable is allocated + * in memory shared by these processes. + * NOTES: + * 1) pshared rwlocks MUST be allocated in shared + * memory. + * 2) The following macro is defined if shared rwlocks + * 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); + +} /* pthread_rwlockattr_getpshared */ + + +int +pthread_rwlockattr_setpshared (pthread_rwlockattr_t * attr, + int pshared) + /* + * ------------------------------------------------------ + * DOCPUBLIC + * Rwlocks created with 'attr' can be shared between + * processes if pthread_rwlock_t variable is allocated + * in memory shared by these processes. + * + * PARAMETERS + * attr + * pointer to an instance of pthread_rwlockattr_t + * + * pshared + * must be one of: + * + * PTHREAD_PROCESS_SHARED + * May be shared if in shared memory + * + * PTHREAD_PROCESS_PRIVATE + * Cannot be shared. + * + * DESCRIPTION + * Rwlocks creatd with 'attr' can be shared between + * processes if pthread_rwlock_t variable is allocated + * in memory shared by these processes. + * + * NOTES: + * 1) pshared rwlocks MUST be allocated in shared + * memory. + * + * 2) The following macro is defined if shared rwlocks + * 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); + +} /* pthread_rwlockattr_setpshared */ + + int pthread_rwlock_rdlock(pthread_rwlock_t *rwlock) { |