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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¶
Themq_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¶
Themq_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¶
Themq_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.February 21, 2014 | Debian |