mq_setattr
- set message queue attributes (REALTIME)
LIBRARY
Lb librt
SYNOPSIS
#include <mqueue.h> int
Fo mq_setattr
Fa mqd_t mqdes
Fa struct mq_attr *restrict mqstat
Fa struct mq_attr *restrict omqstat
Fc
DESCRIPTION
The
mq_setattr ();
system call sets attributes associated with the open message queue description
referenced by the message queue descriptor specified by
Fa mqdes .
The message queue attributes corresponding to the following members defined
in the
Vt 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
Vt 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:
Bq Er EBADF
The
Fa mqdes
argument is not a valid message queue descriptor.
SEE ALSO
mq_open2,
mq_send2,
mq_timedsend2
STANDARDS
The
mq_setattr ();
system call conforms to
St -p1003.1-2004 .
HISTORY
Support for
POSIX
message queues first appeared in
Fx 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.
