NAME

mq_unlink — remove a message queue (REALTIME)

SYNOPSIS

[MSG] #include <mqueue.h>

int mq_unlink(const char *name);

DESCRIPTION

The mq_unlink() function shall remove the message queue named by the string name. If one or more processes have the message queue open when mq_unlink() is called, destruction of the message queue shall be postponed until all references to the message queue have been closed. However, the mq_unlink() call need not block until all references have been closed; it may return immediately.

After a successful call to mq_unlink(), reuse of the name shall subsequently cause mq_open() to behave as if no message queue of this name exists (that is, mq_open() shall fail if O_CREAT is not set, or shall create a new message queue if O_CREAT is set).

RETURN VALUE

Upon successful completion, the function shall return a value of zero. Otherwise, the named message queue shall be unchanged by this function call, and the function shall return a value of -1 and set errno to indicate the error.

ERRORS

The mq_unlink() function shall fail if:

[EACCES]

Permission is denied to unlink the named message queue.

[EINTR]

The call to mq_unlink() blocked waiting for all references to the named message queue to be closed and a signal interrupted the call.

[ENOENT]

The named message queue does not exist.

The mq_unlink() function may fail if:

[ENAMETOOLONG]

The length of the name argument exceeds {_POSIX_PATH_MAX} on systems that do not support the XSI option ^[XSI]  or exceeds {_XOPEN_PATH_MAX} on XSI systems,  or has a pathname component that is longer than {_POSIX_NAME_MAX} on systems that do not support the XSI option ^[XSI]  or longer than {_XOPEN_NAME_MAX} on XSI systems.  A call to mq_unlink() with a name argument that contains the same message queue name as was previously used in a successful mq_open() call shall not give an [ENAMETOOLONG] error.

EXAMPLES

None.

APPLICATION USAGE

None.

RATIONALE

None.

FUTURE DIRECTIONS

A future version might require the mq_open() and mq_unlink() functions to have semantics similar to normal file system operations.

SEE ALSO

mq_close, mq_open, 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_unlink() function is marked as part of the Message Passing option.

The Open Group Corrigendum U021/5 is applied, clarifying that upon unsuccessful completion, the named message queue is unchanged by this function.

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

Issue 7

Austin Group Interpretation 1003.1-2001 #077 is applied, changing [ENAMETOOLONG] from a "shall fail" to a "may fail" error .

Austin Group Interpretation 1003.1-2001 #141 is applied.

POSIX.1-2008, Technical Corrigendum 2, XSH/TC2-2008/0230 [504] is applied.