pthread_rwlock_wrlock(3T)												 pthread_rwlock_wrlock(3T)

NAME

       pthread_rwlock_wrlock(), pthread_rwlock_trywrlock() - lock or attempt to lock a read-write lock for writing

SYNOPSIS

PARAMETERS

	      rwlock	Pointer to the read-write lock to be locked for writing.

DESCRIPTION

       The  function  applies  a  write lock to the read-write lock object referenced by rwlock.  The calling thread acquires the write lock if no
       other thread (reader or writer) holds the read-write lock rwlock.  Otherwise, the thread blocks (that is, it does not return from the call)
       until  it  can acquire the lock.  Results are undefined if the calling thread holds the read-write lock (whether a read or a write lock) at
       the time the call is made.

       The function applies a write lock as in the function with the exception that the function fails if any thread currently holds  rwlock  (for
       reading or writing).

       Results are undefined if any of these functions are called with an uninitialized read-write lock.

       If  a  signal  is delivered to a thread waiting for a read-write lock, upon return from the signal handler, the thread shall resume waiting
       for the read-write lock as if it was not interrupted.

RETURN VALUE

       Upon successful completion, and return zero. Otherwise, an error number is returned to indicate the error (the variable is not set).

ERRORS

       If any of the following occur, the function returns the corresponding error number:

	      [EBUSY]	     The read-write lock rwlock could not be acquired for writing because it was already locked for reading or writing.

       For each of the following conditions, if the condition is detected, the and functions return the corresponding error number:

	      [EINVAL]	     The value specified by rwlock does not refer to an initialized read-write lock.

	      [EDEADLK]      The current thread already owns the read-write lock for reading or writing.

AUTHOR

       and were developed by X/Open.

SEE ALSO

       pthread_rwlock_init(3T), pthread_rwlock_destroy(3T), pthread_rwlock_tryrdlock(3T), pthread_rwlock_rdlock(3T), pthread_rwlock_unlock(3T).

STANDARDS CONFORMANCE

								  Pthread Library					 pthread_rwlock_wrlock(3T)