home | help 
MQ_GETATTR(2)		       System Calls Manual		   MQ_GETATTR(2)

NAME
     mq_getattr -- get message queue attributes (REALTIME)

LIBRARY
     POSIX Real-time Library (librt, -lrt)

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 mqdes argument specifies a message queue descriptor.

     The  results are returned in the mq_attr structure referenced by the 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 mq_attr structure referenced
     by the 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
     Upon successful completion, the value 0 is returned; otherwise the value -1
     is returned and the global variable errno is set to indicate the error.

ERRORS
     The mq_getattr() system call will fail if:

     [EBADF]		The mqdes argument is not a valid message queue descrip-
			tor.

SEE ALSO
     mq_open(2), mq_send(2), mq_setattr(2), mq_timedsend(2)

STANDARDS
     The mq_getattr() 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 Specifica-
     tions  Issue  6, Copyright (C) 2001-2004 by the Institute of Electrical and
     Electronics Engineers, Inc and The Open Group.  In the event  of  any  dis-
     crepancy  between	this  version  and  the original IEEE and The Open Group
     Standard, the original IEEE and The Open Group Standard is the referee doc-
     ument.  The original Standard can be obtained  online  at	http://www.open-
     group.org/unix/online.html.

FreeBSD 15.1			February 21, 2014		   MQ_GETATTR(2)
home | help