Re: [PATCH] fix potential infinite loop given large unsigned integer

From: Junio C Hamano <gitster@pobox.com>
Date: Aug 9, 2009, 06:19 UTC
Message-ID: <7vy6pta4rd.fsf@alter.siamese.dyndns.org>
In-Reply-To: <a3f15ee60908082141l7b2134cg5ddcef17c45fc888@mail.gmail.com>

Ryan Flynn <parseerror@gmail.com> writes:

Show 8 quoted lines

> given n, tried to find i greater than n via i=1, iterate i *= 10.
> given n sufficiently close to UINT_MAX this will overflow; which can
> produce i==0, which results in an infinite loop. iteratively dividing
> n /= 10 does not have this problem, and though division is slower than
> multiplication this only runs once per `git format-patch
> --cover-letter`
>
> Signed-off-by: pizza <parseerror@gmail.com>

Pizza?

This is somewhat amusing.

 - digits_in_number() is called only with opt->total that is "int";

 - opt->total is the total number of patches.

 - the return value is used like this:

     sprintf(buf, "%0*d", digits_in_number(opt->total), opt->nr);

   and opt->nr runs from 1 to opt->total; the use of "d" would be already
   wrong anyway even if you computed digits_in_number() correctly.

Perhaps we should get rid of this function altogether?