NAME

pthread_rwlockattr_getpshared pthread_rwlockattr_setpshared — get and set the process-shared attribute of the read-write lock attributes object

SYNOPSIS

[TSH]
#include <pthread.h>

int pthread_rwlockattr_getpshared(const pthread_rwlockattr_t
       *restrict attr, int *restrict pshared);
int pthread_rwlockattr_setpshared(pthread_rwlockattr_t *attr,
       int pshared);

DESCRIPTION

The pthread_rwlockattr_getpshared () function shall obtain the value of the process-shared attribute from the initialized attributes object referenced by attr. The pthread_rwlockattr_setpshared () function shall set the process-shared attribute in an initialized attributes object referenced by attr.

The process-shared attribute shall be set to PTHREAD_PROCESS_SHARED to permit a read-write lock to be operated upon by any thread that has access to the memory where the read-write lock is allocated, even if the read-write lock is allocated in memory that is shared by multiple processes. See V2_chap02(3) for further requirements. The default value of the process-shared attribute shall be PTHREAD_PROCESS_PRIVATE.

Additional attributes, their default values, and the names of the associated functions to get and set those attribute values are implementation-defined.

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

RETURN VALUE

Upon successful completion, the pthread_rwlockattr_getpshared () function shall return zero and store the value of the process-shared attribute of attr into the object referenced by the pshared parameter. Otherwise, an error number shall be returned to indicate the error.

If successful, the pthread_rwlockattr_setpshared () function shall return zero; otherwise, an error number shall be returned to indicate the error.

ERRORS

The pthread_rwlockattr_setpshared () function may fail if:

[EINVAL]

The new value specified for the attribute is outside the range of legal values for that attribute.

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

The following sections are informative.

EXAMPLES

None.

APPLICATION USAGE

None.

RATIONALE

None.

FUTURE DIRECTIONS

None.

SEE ALSO

pthread_rwlock_destroy(3), pthread_rwlockattr_destroy(3)

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 TSH 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 DESCRIPTION notes that additional attributes are implementation-defined.
• The SEE ALSO section is updated.

The restrict keyword is added to the pthread_rwlockattr_getpshared () prototype for alignment with the ISO/IEC 9899:1999 (“ISO C99”) standard.

Issue 7

The pthread_rwlockattr_getpshared () and pthread_rwlockattr_setpshared () functions are marked only as part of the Thread Process-Shared Synchronization option as the Threads option is now part of the Base.

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

POSIX.1-2008, Technical Corrigendum 2, XSH/TC2-2008/0292 [972] and XSH/TC2-2008/0293 [757] are applied.

End of informative text.