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Message-ID: <CAJgzZorOVSuMitQB5zk280eVf-4u21qjm5fOMD8Wg+XRvRmd4Q@mail.gmail.com>
Date: Fri, 24 Feb 2023 09:07:00 -0800
From: enh <enh@...gle.com>
To: musl@...ts.openwall.com
Cc: Tamir Duberstein <tamird@...gle.com>, NRK <nrk@...root.org>, Rich Felker <dalias@...c.org>
Subject: Re: undefined behavior in fread.c

On Fri, Feb 24, 2023 at 9:00 AM Jₑₙₛ Gustedt <jens.gustedt@...ia.fr> wrote:

> Tamir,
>
> on Fri, 24 Feb 2023 11:42:30 -0500 you (Tamir Duberstein
> <tamird@...gle.com>) wrote:
>
> > Internal UB means "applying zero offset to null pointer" when the
> > caller passes (NULL, _, 0, _).
>
> So you mean internal misbehavior?
>
> > Does such an attribute exist?
>
> Yes, gcc has the nonnull old-style attribute, and I think that the C23
> versions of gcc and clang will have something like `[[gnu::nonnull]]`.
>
> Having this as attribute of the function and not of the pointer is a
> bit unfortunate. For non-void pointers you could also use the `[static
> 1]` array parameter notation instead of a pointer.
>

bionic's using clang's _Nullable and _Nonnull, which do let you express
this:
https://clang.llvm.org/docs/AttributeReference.html#nullability-attributes


> Jₑₙₛ
>
> --
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> <+33%203%2068%2085%2045%2036> ::
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>

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