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MQ_GETATTR(2)            DragonFly 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() function will obtain 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 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(2) 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 refer-
     enced by the mqstat argument will be set to the current state of the mes-
     sage queue:

     mq_curmsgs  The number of messages currently on the queue.


RETURN VALUES

     The mq_getattr() function returns the value 0 if successful; otherwise
     the value -1 is returned and the global variable errno is set to indicate
     the error.


ERRORS

     The mq_getattr() function may fail if:

     [EBADF]            The mqdes argument is not a valid message queue
                        descriptor.


SEE ALSO

     mq_close(2), mq_notify(2), mq_open(2), mq_receive(2), mq_send(2),
     mq_setattr(2), mq_unlink(2)


STANDARDS

     This function conforms to the IEEE Std 1003.1-2001 (``POSIX.1'') stan-
     dard.


HISTORY

     This function first appeared in DragonFly 2.5.


COPYRIGHT

     Portions of this text are reprinted and reproduced in electronic form
     from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
     -- Portable Operating System Interface (POSIX), The Open Group Base Spec-
     ifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electri-
     cal 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 ref-
     eree document.  The original Standard can be obtained online at
     http://www.opengroup.org/unix/online.html .

DragonFly 3.5                   August 19, 2009                  DragonFly 3.5

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