Locks the specified reader-writer lock in the write mode.
#include <synch.h>
int rw_wrlock (
rwlock_t *rwlp );
(IN) Points to the reader-writer lock to acquire in the write mode.
Returns 0; no error conditions have been defined.
If the lock cannot be acquired immediately, the calling thread waits until the lock can be acquired. No assumptions can be made about the way in which the calling thread might wait for the lock to become free. On return, the calling thread will have acquired the specified lock in the write mode.
UNIX International reader-writer locks are not recursive. Attempting to acquire a recursive write lock causes deadlock.