The pthread_rwlockattr_init() function initializes a read-write lock attributes object attr with the default value for all of the attributes defined by the implementation.

Results are undefined if pthread_rwlockattr_init() is called specifying an already initialized read-write lock attributes object.

After a read-write lock attributes object has been used to initialize one or more read-write locks, any function affecting the attributes object (including destruction) does not affect any previously initialized read-write locks.

The pthread_rwlockattr_destroy() function destroys a read-write lock attributes object. The effect of subsequent use of the object is undefined until the object is re-initialized by another call to pthread_rwlockattr_init(). An implementation may cause pthread_rwlockattr_destroy() to set the object referenced by attr to an invalid value.

If successful, the pthread_rwlockattr_init() and pthread_rwlockattr_destroy() functions return 0. Otherwise, an error number is returned to indicate the error.

The pthread_rwlockattr_init() function will fail if:

ENOMEM

Insufficient memory exists to initialize the read-write lock attributes object.

The pthread_rwlockattr_destroy() function may fail if:

EINVAL

The value specified by attr is invalid.

See attributes(5) for descriptions of the following attributes:

pthread_rwlock_init(3THR), pthread_rwlock_rdlock(3THR), pthread_rwlock_unlock(3THR), pthread_rwlock_wrlock(3THR), pthread_rwlockattr_getpshared(3THR), attributes(5)