128 lines
4.3 KiB
Groff
128 lines
4.3 KiB
Groff
.\" Copyright (c) 2005 David Xu <davidxu@FreeBSD.org>
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice(s), this list of conditions and the following disclaimer as
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.\" the first lines of this file unmodified other than the possible
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.\" addition of one or more copyright notices.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice(s), this list of conditions and the following disclaimer in
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.\" the documentation and/or other materials provided with the
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.\" distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
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.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
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.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
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.\" BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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.\" WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
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.\" OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
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.\" EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" Portions of this text are reprinted and reproduced in electronic form
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.\" from IEEE Std 1003.1, 2004 Edition, Standard for Information Technology --
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.\" Portable Operating System Interface (POSIX), The Open Group Base
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.\" Specifications Issue 6, Copyright (C) 2001-2004 by the Institute of
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.\" Electrical and Electronics Engineers, Inc and The Open Group. In the
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.\" event of any discrepancy between this version and the original IEEE and
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.\" The Open Group Standard, the original IEEE and The Open Group Standard is
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.\" the referee document. The original Standard can be obtained online at
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.\" http://www.opengroup.org/unix/online.html.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd February 21, 2014
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.Dt MQ_GETATTR 2
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.Os
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.Sh NAME
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.Nm mq_getattr
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.Nd "get message queue attributes (REALTIME)"
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.Sh LIBRARY
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.Lb librt
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.Sh SYNOPSIS
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.In mqueue.h
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.Ft int
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.Fn mq_getattr "mqd_t mqdes" "struct mq_attr *mqstat"
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.Sh DESCRIPTION
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The
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.Fn mq_getattr
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system call obtains status information and attributes of the message queue and
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the open message queue description associated with the message queue
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descriptor.
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.Pp
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The
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.Fa mqdes
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argument specifies a message queue descriptor.
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.Pp
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The results are returned in the
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.Vt mq_attr
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structure referenced by the
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.Fa mqstat
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argument.
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.Pp
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Upon return, the following members will have the values associated with the
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open message queue description as set when the message queue was opened and
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as modified by subsequent
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.Fn mq_setattr
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calls:
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.Va mq_flags .
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.Pp
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The following attributes of the message queue will be returned as set at
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message queue creation:
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.Va mq_maxmsg , mq_msgsize .
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.Pp
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Upon return, the following members within the
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.Vt mq_attr
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structure referenced by the
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.Fa mqstat
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argument will be set to the current state
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of the message queue:
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.Bl -tag -width ".Va mq_curmsgs"
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.It Va mq_curmsgs
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The number of messages currently on the queue.
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.El
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.Sh RETURN VALUES
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.Rv -std
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.Sh ERRORS
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The
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.Fn mq_getattr
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system call
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will fail if:
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.Bl -tag -width Er
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.It Bq Er EBADF
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The
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.Fa mqdes
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argument is not a valid message queue descriptor.
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.El
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.Sh SEE ALSO
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.Xr mq_open 2 ,
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.Xr mq_send 2 ,
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.Xr mq_setattr 2 ,
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.Xr mq_timedsend 2
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.Sh STANDARDS
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The
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.Fn mq_getattr
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system call conforms to
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.St -p1003.1-2004 .
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.Sh HISTORY
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Support for
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.Tn POSIX
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message queues first appeared in
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.Fx 7.0 .
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.Sh COPYRIGHT
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Portions of this text are reprinted and reproduced in electronic form
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from IEEE Std 1003.1, 2004 Edition, Standard for Information Technology --
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Portable Operating System Interface (POSIX), The Open Group Base
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Specifications Issue 6, Copyright (C) 2001-2004 by the Institute of
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Electrical and Electronics Engineers, Inc and The Open Group. In the
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event of any discrepancy between this version and the original IEEE and
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The Open Group Standard, the original IEEE and The Open Group Standard is
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the referee document. The original Standard can be obtained online at
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http://www.opengroup.org/unix/online.html.
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