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()
system call 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 zero or
O_NONBLOCK.
The values of the
mq_maxmsg, mq_msgsize, and
mq_curmsgs members of the
mq_attr structure are ignored by
mq_setattr().
RETURN VALUES
Upon successful completion, the function returns a value of 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() system call will fail
if:
- [
EBADF] - The mqdes argument is not a valid message queue descriptor.
SEE ALSO
STANDARDS
The mq_setattr() system call conforms to
IEEE Std 1003.1-2004 (“POSIX.1”).
HISTORY
Support for POSIX message queues first appeared in FreeBSD 7.0.
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2004 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2004 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.