pthread_rwlockattr_getpshared - Man Page

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


This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.


#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);


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 Section 2.9.9, Synchronization Object Copies and Alternative Mappings 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.


The pthread_rwlockattr_setpshared() function may fail if:


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.



Application Usage




Future Directions


See Also

pthread_rwlock_destroy(), pthread_rwlockattr_destroy()

The Base Definitions volume of POSIX.1-2017, <pthread.h>

Referenced By

pthread.h(0p), pthread_rwlockattr_destroy(3p).

2017 IEEE/The Open Group POSIX Programmer's Manual