Path: utzoo!utgpu!water!watmath!clyde!rutgers!sri-spam!ames!sdcsvax!ucsdhub!esosun!seismo!uunet!mcvax!unido!pcsbst!jh
From: jh@pcsbst
Newsgroups: comp.unix.wizards
Subject: nonstandard '..' and '.' entries - (nf)
Message-ID: <4300010@pcsbst.UUCP>
Date: 26 Jan 88 10:29:00 GMT
Lines: 36
Nf-ID: #N:pcsbst:4300010:000:1141
Nf-From: pcsbst!jh    Jan 26 11:29:00 1988
Posted: Tue Jan 26 11:29:00 1988

I got a question for UNIX wizzards, but following facts first:

	AT&Ts UNIX SVR3.* in too many places silently assumes that
	a '..' directory entry refers to a parent directory (except roots)
	and a '.' entry refers to the directory itself.


	Yet, try following (being superuser):

	   mkdir t
	   /etc/unlink t/..
	   /etc/link t t/..
	   rmdir t

	If your rmdir uses the rmdir() system call as in standard SVR3
	enough garbage will be left in order to keep fsck happy in an
	infinite loop. Thus, don't make the test without having a fsdb
	at hand ....

Now the question:
We at PCS use '..' entries different from the standard for a
special purpose (superroots etc.).

1)      Who else in the world uses non-standard '.' or '..' entries
	and for what reasons?

2)      If the operating system silently implies these standard
	relations, why not drop the explicit '..' and '.' entries
	altogether and consequently forbid (ignore for the sake of
	compability) linking and unlinking of such entries?

I know that there was a similar discussion on the net half a year
ago, but it never came to a conclusion.

	Johannes Heuft
	unido!pcsbst!jh