MQ_GETATTR(P) POSIX Programmer's Manual MQ_GETATTR(P)
mq_getattr - get message queue attributes (REALTIME)
int mq_getattr(mqd_t mqdes, struct mq_attr *mqstat);
The mq_getattr() function shall 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 shall be returned in the mq_attr structure referenced by the mqstat argument.
Upon return, the following members shall 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 shall 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 shall be set to the current state of the message queue:
The number of messages currently on the queue.
Upon successful completion, the mq_getattr() function shall return zero. Otherwise, the
function shall return -1 and set errno to indicate the error.
The mq_getattr() function shall fail if:
EBADF The mqdes argument is not a valid message queue descriptor.
The following sections are informative.
mq_open() , mq_send() , mq_setattr() , mq_timedsend() , msgctl() , msgget() , msgrcv() ,
msgsnd() , the Base Definitions volume of IEEE Std 1003.1-2001, <mqueue.h>
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 Specifications Issue 6, Copyright (C) 2001-2003 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 orig-
inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .
IEEE/The Open Group 2003 MQ_GETATTR(P)