MQ_GETATTR
Section: POSIX Programmer's Manual (3P)
Updated: 2017
Page Index
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 .