mq_getattr (2)

Leading comments

Copyright (c) 2005 David Xu <davidxu@FreeBSD.org>
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
   notice(s), this list of conditions and the following disclaimer as
   the first lines of this file unmodified other than the possible
   addition of one or more copyright notices.
2. Redistributions in b...

(The comments found at the beginning of the groff file "man2/mq_getattr.2freebsd".)

NAME

mq_getattr - get message queue attributes (REALTIME)

LIBRARY

Lb librt

SYNOPSIS

In mqueue.h Ft int Fn mq_getattr mqd_t mqdes struct mq_attr *mqstat

DESCRIPTION

The Fn 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 Fn 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_curmsgs

The number of messages currently on the queue.

RETURN VALUES

Rv -std

ERRORS

The Fn 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 Fn 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 www.opengroup.org/unix/online.html