Path: utzoo!yunexus!geac!daveb
From: daveb@geac.UUCP (David Collier-Brown)
Newsgroups: comp.unix.wizards
Subject: Re: FileNames with the high bit set.
Summary: Multics.
Message-ID: <2644@geac.UUCP>
Date: 25 Apr 88 12:24:10 GMT
Article-I.D.: geac.2644
Posted: Mon Apr 25 08:24:10 1988
References: <8120010@eecs.nwu.edu> <48993@sun.uucp> <6258@cit-vax.Caltech.Edu>
Reply-To: daveb@geac.UUCP (David Collier-Brown)
Organization: The Geac His(Her)story Department
Lines: 26

In article <6258@cit-vax.Caltech.Edu> mangler@cit-vax.Caltech.Edu (Don Speck) writes:
>One of the beautiful things about the filename syntax of older
>Unixes is that there was no such thing as an illegal filename.
>
>As the TCP people say, "be liberal in what input you accept".

  The "filenames with the high bit set" problem was seen and dealt
with, once upon a time, by both Multics and Unix, by permitting the
mv-equivalent command to accept **any** string as a "from" name, but
only a "legal" string as a "to" name.  This tends to decrease the
difficulty of switching to an 8- (or 9-)bit character set, as the
charset-sensitive code is rather centralized.

  (In Unix the problem was both easier and harder: almost any
character is legal in a "to" name, and the shell interferes in
typing some characters directly.  I confess I do not remember what
happens if the "from" name contains a slash or null.  My reading of
the kernel implementation implies that it REALLY "can't happen": you
get an invalid path to the file.)

--dave (but what if a filesystem does it "wrong"?) c-b
-- 
 David Collier-Brown.                 {mnetor yunexus utgpu}!geac!daveb
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