PTHREAD_RWLOCKATTR_GETPSHARED(3P)                   POSIX Programmer's Manual                  PTHREAD_RWLOCKATTR_GETPSHARED(3P)



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

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

SYNOPSIS
       #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. If the process-shared attribute  is  PTHREAD_PROCESS_PRIVATE,  the  read-
       write  lock  shall  only  be  operated upon by threads created within the same process as the thread that initialized the
       read-write lock; if threads of differing processes attempt to operate on such a read-write lock, the  behavior  is  unde-
       fined. 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.

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_getpshared() and pthread_rwlockattr_setpshared() functions may fail if:

       EINVAL The value specified by attr is invalid.


       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(),   pthread_rwlockattr_destroy(),  pthread_rwlockattr_init(),  the  Base  Definitions  volume  of
       IEEE Std 1003.1-2001, <pthread.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003  Edition,  Standard  for
       Information  Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copy-
       right (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any
       discrepancy  between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group
       Standard  is  the  referee   document.   The   original   Standard   can   be   obtained   online   at   http://www.open-
       group.org/unix/online.html .



IEEE/The Open Group                                           2003                             PTHREAD_RWLOCKATTR_GETPSHARED(3P)