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

PROLOG
       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.

NAME
       mq_getattr -- get message queue attributes (REALTIME)

SYNOPSIS
       #include <mqueue.h>

       int mq_getattr(mqd_t mqdes, struct mq_attr *mqstat);

DESCRIPTION
       The mq_getattr() function shall obtain status information and
       attributes of the message queue and the open message queue description
       associated with the message queue descriptor.

       The mqdes argument specifies a message queue descriptor.

       The results shall be returned in the mq_attr structure referenced by
       the mqstat argument.

       Upon return, the following members shall have the values associated
       with the open message queue description as set when the message queue
       was opened and as modified by subsequent mq_setattr() calls: mq_flags.

       The following attributes of the message queue shall be returned as set
       at message queue creation: mq_maxmsg, mq_msgsize.

       Upon return, the following members within the mq_attr structure
       referenced by the mqstat argument shall be set to the current state of
       the message queue:

       mq_curmsgs
                 The number of messages currently on the queue.

RETURN VALUE
       Upon successful completion, the mq_getattr() function shall return
       zero. Otherwise, the function shall return -1 and set errno to indicate
       the error.

ERRORS
       The mq_getattr() function may fail if:

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

       The following sections are informative.

EXAMPLES
       See mq_notify().

APPLICATION USAGE
       None.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       mq_notify(), mq_open(), mq_send(), mq_setattr(), 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_GETATTR(3P)