1.\" Copyright (c) 2005 David Xu <davidxu@FreeBSD.org> 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice(s), this list of conditions and the following disclaimer as 9.\" the first lines of this file unmodified other than the possible 10.\" addition of one or more copyright notices. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice(s), this list of conditions and the following disclaimer in 13.\" the documentation and/or other materials provided with the 14.\" distribution. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY 17.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 19.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE 20.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 21.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 22.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR 23.\" BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 24.\" WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE 25.\" OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, 26.\" EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27.\" 28.\" Portions of this text are reprinted and reproduced in electronic form 29.\" from IEEE Std 1003.1, 2004 Edition, Standard for Information Technology -- 30.\" Portable Operating System Interface (POSIX), The Open Group Base 31.\" Specifications Issue 6, Copyright (C) 2001-2004 by the Institute of 32.\" Electrical and Electronics Engineers, Inc and The Open Group. In the 33.\" event of any discrepancy between this version and the original IEEE and 34.\" The Open Group Standard, the original IEEE and The Open Group Standard is 35.\" the referee document. The original Standard can be obtained online at 36.\" http://www.opengroup.org/unix/online.html. 37.\" 38.Dd February 21, 2014 39.Dt MQ_GETATTR 2 40.Os 41.Sh NAME 42.Nm mq_getattr 43.Nd "get message queue attributes (REALTIME)" 44.Sh LIBRARY 45.Lb librt 46.Sh SYNOPSIS 47.In mqueue.h 48.Ft int 49.Fn mq_getattr "mqd_t mqdes" "struct mq_attr *mqstat" 50.Sh DESCRIPTION 51The 52.Fn mq_getattr 53system call obtains status information and attributes of the message queue and 54the open message queue description associated with the message queue 55descriptor. 56.Pp 57The 58.Fa mqdes 59argument specifies a message queue descriptor. 60.Pp 61The results are returned in the 62.Vt mq_attr 63structure referenced by the 64.Fa mqstat 65argument. 66.Pp 67Upon return, the following members will have the values associated with the 68open message queue description as set when the message queue was opened and 69as modified by subsequent 70.Fn mq_setattr 71calls: 72.Va mq_flags . 73.Pp 74The following attributes of the message queue will be returned as set at 75message queue creation: 76.Va mq_maxmsg , mq_msgsize . 77.Pp 78Upon return, the following members within the 79.Vt mq_attr 80structure referenced by the 81.Fa mqstat 82argument will be set to the current state 83of the message queue: 84.Bl -tag -width ".Va mq_curmsgs" 85.It Va mq_curmsgs 86The number of messages currently on the queue. 87.El 88.Sh RETURN VALUES 89.Rv -std 90.Sh ERRORS 91The 92.Fn mq_getattr 93system call 94will fail if: 95.Bl -tag -width Er 96.It Bq Er EBADF 97The 98.Fa mqdes 99argument is not a valid message queue descriptor. 100.El 101.Sh SEE ALSO 102.Xr mq_open 2 , 103.Xr mq_send 2 , 104.Xr mq_setattr 2 , 105.Xr mq_timedsend 2 106.Sh STANDARDS 107The 108.Fn mq_getattr 109system call conforms to 110.St -p1003.1-2004 . 111.Sh HISTORY 112Support for 113.Tn POSIX 114message queues first appeared in 115.Fx 7.0 . 116.Sh COPYRIGHT 117Portions of this text are reprinted and reproduced in electronic form 118from IEEE Std 1003.1, 2004 Edition, Standard for Information Technology -- 119Portable Operating System Interface (POSIX), The Open Group Base 120Specifications Issue 6, Copyright (C) 2001-2004 by the Institute of 121Electrical and Electronics Engineers, Inc and The Open Group. In the 122event of any discrepancy between this version and the original IEEE and 123The Open Group Standard, the original IEEE and The Open Group Standard is 124the referee document. The original Standard can be obtained online at 125http://www.opengroup.org/unix/online.html. 126