MQ_SETATTR(3)              POSIX Programmer's Manual             MQ_SETATTR(3)



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

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 message 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 message 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(), msgctl(), msgget(), msgrcv(), msgsnd()

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

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1-2017, Standard for Information Technology --
       Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 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.opengroup.org/unix/online.html .

       Any typographical or formatting errors that appear in this page are
       most likely to have been introduced during the conversion of the source
       files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .



IEEE/The Open Group                  2017                        MQ_SETATTR(3)
