NAME

pthread_rwlock_init — initialize a read/write lock

LIBRARY

POSIX Threads Library (libpthread, -lpthread)

SYNOPSIS

#include < pthread.h>

int
pthread_rwlock_init( pthread_rwlock_t *lock, const pthread_rwlockattr_t *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 Version 2 of the Single UNIX Specification (“SUSv2”).

HISTORY

The pthread_rwlock_init() function first appeared in FreeBSD 3.0.

BUGS

The PTHREAD_PROCESS_SHARED attribute is not supported.