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From: casper@uva.UUCP (Casper H.S. Dik)
Newsgroups: comp.unix.wizards
Subject: Re: Nullpath in system calls considered harmful?
Message-ID: <613@uva.UUCP>
Date: 4 Feb 89 11:53:29 GMT
References: <88368@sun.uucp>
Sender: news@uva.UUCP
Reply-To: dik@uva.UUCP (Casper H.S. Dik)
Organization: Faculteit Wiskunde & Informatica, Universiteit van Amsterdam
Lines: 31

In article <88368@sun.uucp> lm@sun.UUCP (Larry McVoy) writes:
>Hi-
>	A question for oldtimers: is there any good reason that null paths
>    (ie, open("", flags)) should NOT be considered an error.  If you don't
>    already know that many kernels translate "" into "." you probably
>    can't answer this question.  POSIX wants "" to be an error.
>
>Thanks,
>
>Larry McVoy, Lachman Associates.			  My opinions are that.

I'm not an oldtimer, but I think that disallowing the null path
would break many programs.

The main reason why kernels translate "" into "." is beacause of paths
containing //. Try:
% cp -i vmunix /
it responds with:
replace //vmunix?

Many more programs are affected by this. They all think
<validdir>/<file> will always give a valid pathname.
If validdir = "/" this breaks.

If POSIX still allows // in pathnames (do they?), then they disallow only
one special case of null paths, I would say that that's a bad idea.
--cd
____________________________________________________________________________
Casper H.S. Dik
University of Amsterdam     |		      dik@uva.uucp
The Netherlands             |                 ...!uunet!mcvax!uva!dik