strtou(3) handling of negative input

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From: Alejandro Colomar <[email protected]>
To: Bruno Haible <[email protected]>
Cc: [email protected], [email protected], 
	[email protected], [email protected], christos <[email protected]>, 
	=?utf-8?B?xJBvw6BuIFRy4bqnbiBDw7RuZw==?= Danh <[email protected]>, Paul Eggert <[email protected]>, 
	Eli Schwartz <[email protected]>, Guillem Jover <[email protected]>, 
	Iker Pedrosa <[email protected]>, Michael Vetter <[email protected]>, Robert Elz <[email protected]>, 
	[email protected], Sam James <[email protected]>, "Serge E. Hallyn" <[email protected]>
Subject: strtou(3) handling of negative input
References: <mgcfwxfmv3kpfnkkf6uj63kx5tdzl64p2zg2us4ntsu6q5xkwj@k52z5yyiywoo>
 <3237498.fEcJ0Lxnt5@nimes>
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 <4085563.2iPT33SAM4@nimes>
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In-Reply-To: <x34jdlyb6gf6asojjhzwpol5schyz4llk2ebrtzpb7ryje52u6@smbvzpoqcf6v>

Hi Bruno,

On Thu, Mar 20, 2025 at 12:12:10AM +0100, Alejandro Colomar wrote:
> > At the same time, disallowing a leading '-' sign
> > is a benefit as well. I consider it a misfeature that strtoul() parses
> > "-3" successfully and returns ULONG_MAX-2, which was most certainly
> > not intended by the user.
>=20
> Agree; it is a misfeature.  In my API a2i(), when the type passed in the
> first parameter is an unsigned type, negative values are rejected.
>=20
> I wonder if there's any legitimate user of that misfeature.  I didn't
> want to rule it out from a fundamental API just because I can't think of
> a good use of it.
>=20
> Maybe since we have people from many systems here, anyone who has even
> seen a good use of strtoul(3) parsing negative values into an unsigned
> type can comment.  Maybe if we don't hear about it, we could consider it
> useless and tighten it?  Especially for an API that has explicit range
> checks.
>=20
> Would NetBSD be open to changing the implementation of strtou(3) to
> reject negative input?

I have filed a bug in NetBSD for reforming strtou(3):
<https://gnats.netbsd.org/cgi-bin/query-pr-single.pl?number=3D59198>

Let's see what they think about it.


Cheers,
Alex

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

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