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Path: utzoo!utgpu!water!watnot!watmath!clyde!rutgers!ames!necntc!necis!weinberg
From: weinberg@necis.UUCP
Newsgroups: comp.bugs.sys5
Subject: Re: Unlinking "."
Message-ID: <482@necis.UUCP>
Date: Thu, 2-Apr-87 14:11:56 EST
Article-I.D.: necis.482
Posted: Thu Apr  2 14:11:56 1987
Date-Received: Sat, 4-Apr-87 15:31:05 EST
References: <1059@cci632.UUCP>
Reply-To: weinberg@necis.UUCP (Glenn Weinberg)
Organization: NEC Information Systems, Acton, MA
Lines: 19
Keywords: unlink

In article <1059@cci632.UUCP> rrw@cci632.UUCP (Rick Wessman) writes:
>Is it possible under vanilla System V to unlink "."? We have
>the source, and from what I can tell, it is legal.

Yes, it is legal.  It has to be, since (at least in versions prior to V.3)
there is no system call to create or delete a directory in one piece.  Thus,
in order to create a directory you have to do a mknod followed by explicit
creation of "." and ".."; to delete it, you must do the opposite, again one
step at a time.

>If it is legal, should it be OK to be able to remove it when the
>directory is not empty?

In my opinion, no, although I can see the "but then it's not UN*X"
responses coming now!  Of course, determining whether or not a directory
is empty is (or at least has the potential to be) a very expensive
operation.  Besides, the "correct" solution is to provide the
mkdir and rmdir system calls and then prohibit any modification of "."
and ".." from outside the kernel.