PTHREAD_RWLOCK_INIT(3)

NAME
pthread_rwlock_init - initialize a read/write lock

LIBRARY
libpthread

SYNOPSIS
#include <pthread.h>
int
pthread_rwlock_init(pthread_rwlock_t * restrict lock, const pthread_rwlockattr_t * restrict attr);

DESCRIPTION
The pthread_rwlock_init() function is used to initialize a read/write lock, with attributes specified by attr. If attr is NULL, the default read/write lock attributes are used.

The results of calling pthread_rwlock_init() with an already initialized lock are undefined.

RETURN VALUES
If successful, the pthread_rwlock_init() function will return zero. Otherwise an error number will be returned to indicate the error.

ERRORS
The pthread_rwlock_init() function will fail if:

[EAGAIN]
    The system lacked the necessary resources (other than memory) to initialize the lock.

[ENOMEM]
    Insufficient memory exists to initialize the lock.

[EPERM]
    The caller does not have sufficient privilege to perform the operation.

The pthread_rwlock_init() function may fail if:

[EBUSY]
    The system has detected an attempt to re-initialize the object referenced by lock, a previously initialized but not yet destroyed read/write lock.

[EINVAL]
    The value specified by attr is invalid.

SEE ALSO
pthread_rwlockattr_init(3), pthread_rwlockattr_setpshared(3), pthread_rwlock_destroy(3)

STANDARDS
The pthread_rwlock_init() function is expected to conform to susv2.

HISTORY
The pthread_rwlock_init() function first appeared in FreeBSD 3.0.

BUGS
The PTHREAD_PROCESS_SHARED attribute is not supported.