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From: ekrell@hector..UUCP (Eduardo Krell)
Newsgroups: comp.unix.wizards
Subject: Re: Symbolic Links
Message-ID: <2865@ulysses.homer.nj.att.com>
Date: Tue, 25-Aug-87 20:47:10 EDT
Article-I.D.: ulysses.2865
Posted: Tue Aug 25 20:47:10 1987
Date-Received: Thu, 27-Aug-87 03:28:56 EDT
References: <8731@brl-adm.ARPA> <2789@ulysses.homer.nj.att.com> <1781@munnari.oz> <2854@ulysses.homer.nj.att.com> <8137@mimsy.UUCP>
Sender: daemon@ulysses.homer.nj.att.com
Reply-To: ekrell@ulysses (Eduardo Krell)
Organization: AT&T Bell Labs, Murray Hill
Lines: 40

In article <8137@mimsy.UUCP> chris@mimsy.UUCP writes:

>Mount points are (1) required to be on a leaf and (2) mount the root
>of a tree.  (That (1) is enforced by hiding anything that is under
>the mount point is irrelevant.)  This means that mount points leave
>the file system tree-structured.

The point I was making is that .. is already being treated in a special
way in the kernel. You don't always get the i-node pointed by the .. entry
in the directory.

>If you wish to treat all path names as strings before attempting to
>apply them to the file system itself, and resolve `..' as `up one
>level'

But isn't this EXACTLY what's done when the ".." is at a mount point?.
The .. entry at the root of the mounted file system points to the root
directory of the file system (i-node 2), yet when you "cd ..", you get
to a different place.

>There is no need for `.' and `..' directory entries.  These become
>magic strings.  There is no need for the file system to be implemented
>as a directed graph (although it may still be convenient).

I believe "." is already treated specially by the kernel in namei().
That is, no search is made in the directory for ".". It just returns
u.u_cdir. It already is a magic string.

I have seen many programs that use canonical pathnames. They get rid of
both "." and ".."s before resolving the pathname. They currently break
because of symbolic links.

>It may be convenient, but it does not feel like Unix.

Somehow I feel you'll have a hard time convincing the thousands of ksh
users that they're not running Unix ...
    
    Eduardo Krell                   AT&T Bell Laboratories, Murray Hill

    {ihnp4,seismo,ucbvax}!ulysses!ekrell