NAME

mq_getattr — get message queue attributes (REALTIME)

SYNOPSIS

#include <mqueue.h>

int mq_getattr(mqd_t mqdes, struct mq_attr *mqstat);

DESCRIPTION

The mqdes argument specifies a message queue descriptor. The mq_getattr() function is used to get status information and attributes of the message queue and the open message queue description associated with the 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 are returned as set at message queue creation.

mq_maxmsg

 

mq_msgsize

 

mq_curmsgs

The number of messages currently on the queue.

RETURN VALUE

Upon successful completion, the mq_getattr() function returns zero. Otherwise, the function returns -1 and sets errno to indicate the error.

ERRORS

The mq_getattr() function will fail if:

[EBADF]

The mqdes argument is not a valid message queue descriptor.

[ENOSYS]

The function mq_getattr() is not supported by this implementation.

EXAMPLES

None.

APPLICATION USAGE

None.

SEE ALSO

mq_open(3) , mq_send(3) , mq_setattr(3) <mqueue.h> , msgctl(3) , msgget(3) , msgrcv(3) , msgsnd(3) .

DERIVATION

Derived from the POSIX Realtime Extension (1003.1b-1993/1003.1i-1995)