NAME

mq_close — close a message queue (REALTIME)

SYNOPSIS

[MSG] #include <mqueue.h>

int mq_close(mqd_t mqdes);

DESCRIPTION

The mq_close() function shall remove the association between the message queue descriptor, mqdes, and its message queue. The results of using this message queue descriptor after successful return from this mq_close(), and until the return of this message queue descriptor from a subsequent mq_open(), are undefined.

If a message queue descriptor is implemented using a file descriptor, mq_close() shall close the file descriptor.

If the process has successfully attached a notification request to the message queue via this mqdes, this attachment shall be removed, and the message queue is available for another process to attach for notification.

RETURN VALUE

Upon successful completion, the mq_close() function shall return a value of zero; otherwise, the function shall return a value of -1 and set errno to indicate the error.

ERRORS

The mq_close() function shall fail if:

[EBADF]

The mqdes argument is not a valid message queue descriptor.

EXAMPLES

None.

APPLICATION USAGE

None.

RATIONALE

None.

FUTURE DIRECTIONS

None.

SEE ALSO

mq_open, mq_unlink, msgctl, msgget, msgrcv, msgsnd

XBD <mqueue.h>

CHANGE HISTORY

First released in Issue 5. Included for alignment with the POSIX Realtime Extension.

Issue 6

The mq_close() function is marked as part of the Message Passing option.

The [ENOSYS] error condition has been removed as stubs need not be provided if an implementation does not support the Message Passing option.

Issue 8

Austin Group Defect 368 is applied, adding a requirement that if a message queue descriptor is implemented using a file descriptor, mq_close() closes the file descriptor.