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From: dave@murphy.UUCP (Snipe Hunter)
Newsgroups: comp.unix.wizards
Subject: Re: symbolic links are a botch
Message-ID: <390@murphy.UUCP>
Date: Wed, 10-Jun-87 09:39:29 EDT
Article-I.D.: murphy.390
Posted: Wed Jun 10 09:39:29 1987
Date-Received: Sat, 20-Jun-87 06:01:20 EDT
References: <2629@ulysses.homer.nj.att.com>
Organization: Gould CSD, Fort Lauderdale, FL
Lines: 40
Keywords: file system, file name resolution
Summary: please do it in the shell, not in the kernel

Hmmm...I've never had much trouble with this.  I have been surprised before by
passing through a symbolic link when cd'ing, and finding myself in a totally
different place, but on my personal annoyance scale it doesn't rank nearly
as high as, say, the backwards arguments to strcpy.

Treating ".." as an operator in the shell's cd command does sound like a
nice idea, though.  I assume you would have some sort of a stack of
directory names and use that to handle "..".  As long as it doesn't create
a directory-depth limitation, fine.  You might want to consider making it
an option, turned on and off by setting a variable or something.  I would
also like to see an option to have the shell issue a warning message
whenever you pass through a symlink.

I'm not so sure I feel comfortable with treating ".." specially in the
kernel, though.  The reason is that, if you do that, then if you have
a symlink which contains ".." in its resolution path, the place that ".."
refers to can be different depending on how you got there.  Here's an
example: you have a directory "/foo" which contains a file "f.c".  This
file is a symbolic link that points to "../bar/f.c".  Now, if you cd
into "/foo" without passing through a symlink, there is no problem with
"f.c"; if you more it, you get the contents of "/bar/f.c".  However,
now suppose you have another directory "/xyzzy" with a symlink "plugh"
which points to "/foo".  If I understand your proposal correctly, if you
cd to "/xyzzy" and then to "plugh", getcwd will report that your current
directory is "/xyzzy/plugh", not "/foo".  The problem comes when you try
to access "f.c"; the symlink will refer not to "/bar/f.c", but to
"/xyzzy/bar/f.c", which doesn't exist.

Does this make sense, or have I misunderstood you completely?
---
"Country beats the hell out of me" -- Jerry Dale McFadden

Dave Cornutt, Gould Computer Systems, Ft. Lauderdale, FL
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