Re: [PATCH] Avoid bug in Solaris xpg4/sed as used in submodule

From: Ben Walton <bwalton@artsci.utoronto.ca>
Date: Apr 9, 2012, 13:30 UTC
Message-ID: <1333977812-sup-4111@pinkfloyd.chass.utoronto.ca>
In-Reply-To: <m2sjgde7cs.fsf@linux-m68k.org>

Excerpts from Andreas Schwab's message of Mon Apr 09 02:40:03 -0400 2012:

> How about using 's|[^/][^/]*|..|g' instead, which should avoid the bug
> as well.

I'd be ok with that change if the changed semantics of the regex are ok in this application. It's essentially the same as s|[^/]+|..|g, which requires at least one character.

In the current code, if you do:

echo '/' | sed -e 's|[^]*|..|g'

you get: ../.. (from a working implementation).

Your regex would see the result  be: /

I don't think we'd ever be passing a plain /, but we might pass a fully qualified path /path/to/foo, which would see the result change from ../../../.. to /../../.. and that could have unintended impact.

I'd need to look more closely to see if this is a problem in reality. Others more familiar with this code likely know the answer already.

Thanks -Ben -- Ben Walton Systems Programmer - CHASS University of Toronto C:416.407.5610 | W:416.978.4302