Re: [PATCH v1] xstrtol: 1 is not a valid base

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From: Alejandro Colomar <[email protected]>
To: Bruno Haible <[email protected]>
Cc: [email protected], Paul Eggert <[email protected]>, 
	=?utf-8?B?xJBvw6BuIFRy4bqnbiBDw7RuZw==?= Danh <[email protected]>, Eli Schwartz <[email protected]>, Sam James <[email protected]>, 
	Serge Hallyn <[email protected]>, Iker Pedrosa <[email protected]>, 
	"Andrew J. Hesford" <[email protected]>, Michael Vetter <[email protected]>, [email protected]
Subject: Re: [PATCH v1] xstrtol: 1 is not a valid base
References: <[email protected]>
 <2143892.otsE0voPBg@nimes>
MIME-Version: 1.0
In-Reply-To: <2143892.otsE0voPBg@nimes>

Hi Bruno,

On Thu, Jul 18, 2024 at 08:06:07PM GMT, Bruno Haible wrote:
> Alejandro Colomar wrote:
> > If xstrtol() was being called with a base of 1, under some conditions it
> > would invoke Undefined Behavior.
>=20
> Yes, sure. A numeric base of 1 makes no sense, mathematically.
>=20
> Thanks for the patch; applied.
>=20
> Note that I disagree with the statement from
> https://github.com/void-linux/void-packages/issues/51261#issuecomment-223=
7055195 :
> > Yet he introduced that bug a decade ago
>=20
> I wouldn't call it a bug. Gnulib does not document that passing a base of=
 1
> to xstrtol is valid.

While it's your api, borrowing the name of strtol(3) comes with implied
semantics.  I think it'd be common to assume that unless specifically
documented, you behave like POSIX's strtol(3), which produces defined
behavior for a base of 1.  If not a bug, it was at least misleading.

I don't claim that POSIX's choice was good; actually I think it makes
little sense, and ISO C's choice of leaving it undefined was probably
better.

BTW, does gnulib have documentation for xstrtol()?  I couldn't find it.
And for MALLOC()?  I'm interested in reading both.

> It's known to everyone in the field that a base of 1
> makes no sense. So, what you saw here was a slightly incomplete input
> validation check.
>=20
> Thanks for the improvement.

You're welcome!

Have a lovely night!
Alex

> Bruno

--=20
<https://www.alejandro-colomar.es/>

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