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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_flags  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 descriptor.

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 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.