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

From: Andreas Schwab <schwab@linux-m68k.org>
Date: Apr 9, 2012, 15:09 UTC
Message-ID: <m2fwcdc57q.fsf@igel.home>
In-Reply-To: <1333977812-sup-4111@pinkfloyd.chass.utoronto.ca>

Ben Walton <bwalton@artsci.utoronto.ca> writes:

Show 20 quoted lines

> 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.

AFAICS the variables at this point never contain a value with a leading slash.

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
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