mq_getattr(3)mq_getattr(3)NAMEmq_getattr - Returns the status and attributes of a message queue
(P1003.1b)
SYNOPSIS
#include <mqueue.h>
int mq_getattr ( mqd_t mqdes, struct mq_attr *mqstat);
LIBRARY
Realtime Library (librt.so, librt.a)
PARAMETERS
Specifies the message queue descriptor whose attributes are obtained.
Specifies a pointer to a structure that is updated to contain the val‐
ues that were set when the message queue was created or modified by a
call to the mq_setattr function.
When the mq_getattr function returns, the following three members of
the mq_attr structure specified by mqstat will have the values that
were set when the message queue was created, but with modifications
made by subsequent calls to the mq_setattr function: The mq_maxmsg mem‐
ber specifies the maximum number of messages that can be held in the
queue specified by the mqdes argument. The mq_msgsize member specifies
the maximum size of any message in the queue. The mq_options member
specifies whether the message operation is blocking or nonblocking
(MQ_NONBLOCK).
The mq_curmsgs member of the mq_attr structure indicates the number of
messages currently on the queue.
DESCRIPTION
The mq_getattr function returns the status and attributes of a message
queue. Use the mq_setattr function to set message queue attributes.
RETURN VALUES
On successful completion, the function returns the value 0 (zero); oth‐
erwise, the function returns the value -1 and sets errno to indicate
the error.
ERRORS
The mq_getattr function fails under the following conditions: The
fildes argument is an invalid file descriptor. The mqstat argument is
a null pointer.
SEE ALSO
Functions: mq_open(3), mq_receive(3), mq_send(3), mq_setattr(3)
Guide to Realtime Programming
mq_getattr(3)
