NAME
mq_setattr —
set message queue attributes
(REALTIME)
LIBRARY
library “librt”
SYNOPSIS
#include
<mqueue.h>
int
mq_setattr(mqd_t mqdes,
const struct mq_attr *restrict mqstat,
struct mq_attr *restrict omqstat);
DESCRIPTION
Themq_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_NONBLOCKand 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
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.