mq_getattr
- get message queue attributes (REALTIME)
LIBRARY
Lb librt
SYNOPSIS
#include <mqueue.h> int
mq_getattr (mqd_t mqdes struct mq_attr *mqstat);
DESCRIPTION
The
mq_getattr ();
system call obtains status information and attributes of the message queue and
the open message queue description associated with the message queue
descriptor.
The
Fa mqdes
argument specifies a message queue descriptor.
The results are returned in the
Vt mq_attr
structure referenced by the
Fa mqstat
argument.
Upon return, the following members will have the values associated with the
open message queue description as set when the message queue was opened and
as modified by subsequent
mq_setattr ();
calls:
mq_flags
The following attributes of the message queue will be returned as set at
message queue creation:
mq_maxmsg , mq_msgsize
Upon return, the following members within the
Vt mq_attr
structure referenced by the
Fa mqstat
argument will be set to the current state
of the message queue:
mq_flags
The number of messages currently on the queue.
RETURN VALUES
Rv -std
ERRORS
The
mq_getattr ();
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_setattr2,
mq_timedsend2
STANDARDS
The
mq_getattr ();
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.
