If an error condition occurs, this routine returns an integer value indicating the type of error. Possible return values are as follows: Return Description 0 Successful completion; the read-write lock object was acquired for read access. [EAGAIN] The lock for read access could not be acquired because the maximum number of read lock acquisitions for rwlock has been exceeded. [EBUSY] The read-write lock could not be acquired for read access because another thread already acquired it for write access or is blocked and waiting for it for write access. [EDEADLCK] The current thread already owns the read-write lock for writing. [EINVAL] The value specified by rwlock does not refer to an initialized read-write lock object.