mq_getattr(3C)

Name

mq_getattr - get message queue attributes

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(3C) calls:

mq_flags

message queue flags

The following attributes of the message queue are returned as set at message queue creation:

mq_maxmsg

maximum number of messages

mq_msgsize

maximum message size

mq_curmsgs

number of messages currently on the queue.

Return Values

Upon successful completion, the mq_getattr() function returns 0. 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 mq_getattr() function is not supported by the system.

Attributes

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE ATTRIBUTE VALUE Interface Stability Committed MT-Level MT-Safe Standard See standards(5).

See also

msgctl(2), msgget(2), msgrcv(2), msgsnd(2), mqueue.h(3HEAD), mq_open(3C), mq_send(3C), mq_setattr(3C), attributes(5), standards(5)