NAME

pthread_rwlockattr_destroy, pthread_rwlockattr_init — destroy and initialize the read-write lock attributes object

SYNOPSIS

#include <pthread.h>

int pthread_rwlockattr_destroy(pthread_rwlockattr_t *attr);
int pthread_rwlockattr_init(pthread_rwlockattr_t *attr);


DESCRIPTION

The pthread_rwlockattr_destroy() function shall destroy a read-write lock attributes object. A destroyed attr attributes object can be reinitialized using pthread_rwlockattr_init(); the results of otherwise referencing the object after it has been destroyed are undefined. An implementation may cause pthread_rwlockattr_destroy() to set the object referenced by attr to an invalid value.

The pthread_rwlockattr_init() function shall initialize a read-write lock attributes object attr with the default value for all of the attributes defined by the implementation.

Results are undefined if pthread_rwlockattr_init() is called specifying an already initialized attr attributes object.

After a read-write lock attributes object has been used to initialize one or more read-write locks, any function affecting the attributes object (including destruction) shall not affect any previously initialized read-write locks.

The behavior is undefined if the value specified by the attr argument to pthread_rwlockattr_destroy() does not refer to an initialized read-write lock attributes object.

RETURN VALUE

If successful, the pthread_rwlockattr_destroy() and pthread_rwlockattr_init() functions shall return zero; otherwise, an error number shall be returned to indicate the error.

ERRORS

The pthread_rwlockattr_init() function shall fail if:

[ENOMEM]

Insufficient memory exists to initialize the read-write lock attributes object.

These functions shall not return an error code of [EINTR].

EXAMPLES

None.

APPLICATION USAGE

None.

RATIONALE

If an implementation detects that the value specified by the attr argument to pthread_rwlockattr_destroy() does not refer to an initialized read-write lock attributes object, it is recommended that the function should fail and report an [EINVAL] error.

FUTURE DIRECTIONS

None.

SEE ALSO

pthread_rwlock_destroy, pthread_rwlockattr_getpshared

XBD <pthread.h>

CHANGE HISTORY

First released in Issue 5.

Issue 6

The following changes are made for alignment with IEEE Std 1003.1j-2000:

• The margin code in the SYNOPSIS is changed to THR to indicate that the functionality is now part of the Threads option (previously it was part of the Read-Write Locks option in IEEE Std 1003.1j-2000 and also part of the XSI extension).

• The SEE ALSO section is updated.

Issue 7

The pthread_rwlockattr_destroy() and pthread_rwlockattr_init() functions are moved from the Threads option to the Base.

The [EINVAL] error for an uninitialized read-write lock attributes object is removed; this condition results in undefined behavior.