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From: umueller@iiic.ethz.ch (Urban Dominik Mueller)
Newsgroups: comp.sys.amiga.programmer
Subject: Re: Checking to see if a file's a link
Message-ID: <28449@neptune.inf.ethz.ch>
Date: 2 May 91 11:27:14 GMT
References: <15127@darkstar.ucsc.edu> <MWM.91Apr29120935@raven.pa.dec.com> <1991Apr29.160901.30173@kuhub.cc.ukans.edu>
Sender: news@neptune.inf.ethz.ch
Reply-To: umueller@iiic.ethz.ch (Urban Dominik Mueller)
Organization: Departement Informatik, ETH, Zurich
Lines: 20

>2.0 dos.library has a function called SameLock() that takes two locks
>and returns TRUE if they are the same object (I think all it does is
>check for a match of the handler and header block fields).  With this,
>just keep a Lock on each level of the tree you've walked down, and if
>you step into a link, then check for a match with each parent.  If
>you get a match, you've made a cycle and skip that link, otherwise,
>you can proceed with that link safely.

>Mark Gooderum			Only...		\    Good Cheer !!!
>[huge .sig deleted]

Nice idea, really. But it has its drawbacks, too. Remember the original
question: Somebody wanted to create a 'du' type utility. Now if there
is a link that points downward in the directory tree, the contents
of that link (directory or file) will be counted twice. CSH has a 
built in 'du' like feature ('dir -v'), and there I have decided not to
look at links at all. Comments?
BTW: How fast is SameLock()?

 -U. Dominik Mueller      umueller@iiic.ethz.ch       .sig light!