January 30, 2003 PTHREAD_RWLOCK_WRLOCK 3

### NAME

pthread_rwlock_wrlock, pthread_rwlock_timedwrlock, pthread_rwlock_trywrlock - acquire a read/write lock for writing

### LIBRARY

POSIX Thread Library (libpthread, -lpthread)

### SYNOPSIS

```int` pthread_rwlock_wrlock(```pthread_rwlock_t *lock`)
```int` pthread_rwlock_timedwrlock(```pthread_rwlock_t * restrict lock``, const struct timespec * restrict abstime`)
```int` pthread_rwlock_trywrlock(```pthread_rwlock_t *lock`)

### DESCRIPTION

The pthread_rwlock_wrlock(``) function blocks until a write lock can be acquired against ```lock`.

The pthread_rwlock_timedwrlock(``) performs the same action, but will not wait beyond ```abstime` to obtain the lock before returning.

The pthread_rwlock_trywrlock(``) function performs the same action as pthread_rwlock_wrlock(``), but does not block if the lock cannot be immediately obtained.

The results are undefined if the calling thread already holds the lock at the time the call is made.

### RETURN VALUES

If successful, the pthread_rwlock_wrlock(``), pthread_rwlock_timedwrlock(``), and pthread_rwlock_trywrlock(``) functions will return zero. Otherwise an error number will be returned to indicate the error.

### ERRORS

The pthread_rwlock_trywrlock(``) function shall fail if:

[```EBUSY`]
  The calling thread is not able to acquire the lock without blocking.

The pthread_rwlock_timedrdlock(``) function shall fail if:

[```ETIMEDOUT`]
  The time specified by ```abstime` was reached before the lock could be obtained.

The pthread_rwlock_wrlock(``), pthread_rwlock_timedwrlock(``), and pthread_rwlock_trywrlock(``) functions may fail if:

[```EDEADLK`]
  The calling thread already owns the read/write lock (for reading or writing).

[```EINVAL`]
  The value specified by ```lock` is invalid.

### SEE ALSO

pthread_rwlock_destroy(3), pthread_rwlock_init(3), pthread_rwlock_rdlock(3), pthread_rwlock_unlock(3)

### STANDARDS

pthread_rwlock_wrlock(``), pthread_rwlock_timedwrlock(``), and pthread_rwlock_trywrlock(``) conform to ISO/IEC 9945-1:1996 (``POSIX.1'') .