NAME
mq_setattr —
set message queue
attributes (REALTIME)
LIBRARY
POSIX Real-time Library (librt, -lrt)
SYNOPSIS
#include <mqueue.h>
int
mq_setattr(
mqd_t mqdes,
const struct mq_attr *restrict mqstat,
struct mq_attr *restrict omqstat);
DESCRIPTION
The
mq_setattr() function sets attributes associated with the
open message queue description referenced by the message queue descriptor
specified by
mqdes.
The message queue attributes corresponding to the following members defined in
the
mq_attr structure will be set to the specified
values upon successful completion of
mq_setattr():
-
-
- mq_flags
- The value of this member is the bitwise-logical OR of zero
or more of
O_NONBLOCK
and any
implementation-defined flags.
The values of the
mq_maxmsg,
mq_msgsize, and
mq_curmsgs members
of the
mq_attr structure will be ignored by
mq_setattr().
If
omqstat is
non-NULL
, the
mq_setattr() function will store, in the location referenced
by
omqstat the previous message queue attributes and the
current queue status. These values are the same as would be returned by a call
to
mq_getattr(3) at that
point.
RETURN VALUES
Upon successful completion, the
mq_setattr() function returns
zero and the attributes of the message queue will have been changed as
specified. Otherwise, the message queue attributes are unchanged, and the
function returns a value of -1 and sets the global variable
errno to indicate the error.
ERRORS
The
mq_setattr() function fails if:
-
-
- [
EBADF
]
- The mqdes argument is not a valid
message queue descriptor.
SEE ALSO
mq(3),
mq_getattr(3)
STANDARDS
This function conforms to the
IEEE Std 1003.1-2001
(“POSIX.1”) standard.
HISTORY
This function first appeared in
NetBSD 5.0.
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE
Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable
Operating System Interface (POSIX), The Open Group Base Specifications Issue
6, Copyright (C) 2001-2003 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.