MQ_SETATTR(3P)                                      POSIX Programmer's Manual                                     MQ_SETATTR(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
       mq_setattr - set message queue attributes (REALTIME)

SYNOPSIS
       #include <mqueue.h>

       int mq_setattr(mqd_t mqdes, const struct mq_attr *restrict mqstat,
              struct mq_attr *restrict omqstat);


DESCRIPTION
       The  mq_setattr() function shall set attributes associated with the open message queue description referenced by the mes-
       sage queue descriptor specified by mqdes.

       The message queue attributes corresponding to the following members defined in the mq_attr structure shall be set to  the
       specified values upon successful completion of mq_setattr():

       mq_flags
              The  value  of  this member is the bitwise-logical OR of zero or more of O_NONBLOCK and any implementation-defined
              flags.


       The values of the  mq_maxmsg,  mq_msgsize,  and  mq_curmsgs  members  of  the  mq_attr  structure  shall  be  ignored  by
       mq_setattr().

       If  omqstat  is non-NULL, the mq_setattr() function shall store, in the location referenced by omqstat, the previous mes-
       sage queue attributes and the current queue status. These values shall be the same as would be  returned  by  a  call  to
       mq_getattr() at that point.

RETURN VALUE
       Upon  successful completion, the function shall return a value of zero and the attributes of the message queue shall have
       been changed as specified.

       Otherwise, the message queue attributes shall be unchanged, and the function shall return a value of -1 and set errno  to
       indicate the error.

ERRORS
       The mq_setattr() function shall fail if:

       EBADF  The mqdes argument is not a valid message queue descriptor.


       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       None.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       mq_open(),   mq_send(),   mq_timedsend(),  msgctl(),  msgget(),  msgrcv(),  msgsnd(),  the  Base  Definitions  volume  of
       IEEE Std 1003.1-2001, <mqueue.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                                                MQ_SETATTR(3P)