xref: /freebsd/lib/libsys/mq_setattr.2 (revision 7fdf597e96a02165cfe22ff357b857d5fa15ed8a)
1.\" Copyright (c) 2005 David Xu <davidxu@FreeBSD.org>
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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 May 17, 2011
39.Dt MQ_SETATTR 2
40.Os
41.Sh NAME
42.Nm mq_setattr
43.Nd "set message queue attributes (REALTIME)"
44.Sh LIBRARY
45.Lb librt
46.Sh SYNOPSIS
47.In mqueue.h
48.Ft int
49.Fo mq_setattr
50.Fa "mqd_t mqdes"
51.Fa "const struct mq_attr *restrict mqstat"
52.Fa "struct mq_attr *restrict omqstat"
53.Fc
54.Sh DESCRIPTION
55The
56.Fn mq_setattr
57system call sets attributes associated with the open message queue description
58referenced by the message queue descriptor specified by
59.Fa mqdes .
60The message queue attributes corresponding to the following members defined
61in the
62.Vt mq_attr
63structure will be set to the specified values upon successful completion of
64.Fn mq_setattr :
65.Bl -tag -width ".Va mq_flags"
66.It Va mq_flags
67The value of this member is zero or
68.Dv O_NONBLOCK .
69.El
70.Pp
71The values of the
72.Va mq_maxmsg , mq_msgsize ,
73and
74.Va mq_curmsgs
75members of the
76.Vt mq_attr
77structure are ignored by
78.Fn mq_setattr .
79.Sh RETURN VALUES
80Upon successful completion, the function returns a value of zero and the
81attributes of the message queue will have been changed as specified.
82.Pp
83Otherwise, the message queue attributes are unchanged, and the function
84returns a value of \-1 and sets the global variable
85.Va errno
86to indicate the error.
87.Sh ERRORS
88The
89.Fn mq_setattr
90system call
91will fail if:
92.Bl -tag -width Er
93.It Bq Er EBADF
94The
95.Fa mqdes
96argument is not a valid message queue descriptor.
97.El
98.Sh SEE ALSO
99.Xr mq_open 2 ,
100.Xr mq_send 2 ,
101.Xr mq_timedsend 2
102.Sh STANDARDS
103The
104.Fn mq_setattr
105system call conforms to
106.St -p1003.1-2004 .
107.Sh HISTORY
108Support for
109.Tn POSIX
110message queues first appeared in
111.Fx 7.0 .
112.Sh COPYRIGHT
113Portions of this text are reprinted and reproduced in electronic form
114from IEEE Std 1003.1, 2004 Edition, Standard for Information Technology --
115Portable Operating System Interface (POSIX), The Open Group Base
116Specifications Issue 6, Copyright (C) 2001-2004 by the Institute of
117Electrical and Electronics Engineers, Inc and The Open Group.  In the
118event of any discrepancy between this version and the original IEEE and
119The Open Group Standard, the original IEEE and The Open Group Standard is
120the referee document.  The original Standard can be obtained online at
121http://www.opengroup.org/unix/online.html.
122