bionic (3) mq_getattr.3posix.gz

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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.1‐2008, <mqueue.h>


       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2013 Edition,
       Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open  Group  Base
       Specifications  Issue 7, Copyright (C) 2013 by the Institute of Electrical and Electronics Engineers, Inc
       and The Open Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/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 .