pthread_rwlock_init(3)

NAME

pthread_rwlock_init - initialize a read/write lock

LIBRARY

library ``libc_r'' library ``libpthread'' library ``libthr''

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 re

turn zero. Otherwise an error number will be returned to indicate the er

ror.

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 priv

ilege to per

form 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 previ

ously initialized but not yet destroyed read/write

lock.

[EINVAL] The value specified by attr is invalid.

SEE ALSO

pthread_rwlockattr_init(3), pthread_rwlockattr_setp

shared(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.

BSD August 4, 1998

BSD