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From: Geert Uytterhoeven <geert@linux-m68k.org>
Date: Mon, 5 Feb 2024 14:07:56 +0100
Message-ID: <CAMuHMdXYri0tkVDORL468hc7_AXx4qnrT6wjKO69FpujbEehUQ@mail.gmail.com>
Subject: Re: [PATCH v2 2/4] string: Allow 2-argument strscpy()
To: Kees Cook <keescook@chromium.org>
Cc: Andy Shevchenko <andy@kernel.org>, Justin Stitt <justinstitt@google.com>, 
	linux-hardening@vger.kernel.org, Richard Weinberger <richard@nod.at>, 
	Anton Ivanov <anton.ivanov@cambridgegreys.com>, Johannes Berg <johannes@sipsolutions.net>, 
	Willem de Bruijn <willemdebruijn.kernel@gmail.com>, Jason Wang <jasowang@redhat.com>, 
	kernel test robot <lkp@intel.com>, Nathan Chancellor <nathan@kernel.org>, 
	Azeem Shaikh <azeemshaikh38@gmail.com>, linux-kernel@vger.kernel.org, 
	linux-um@lists.infradead.org
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Hi Kees,

On Mon, Feb 5, 2024 at 2:01=E2=80=AFPM Kees Cook <keescook@chromium.org> wr=
ote:
> On Mon, Feb 05, 2024 at 01:47:08PM +0100, Geert Uytterhoeven wrote:
> > > +/*
> > > + * The 2 argument style can only be used when dst is an array with a
> > > + * known size.
> > > + */
> > > +#define __strscpy0(dst, src, ...)      \
> > > +       sized_strscpy(dst, src, sizeof(dst) + __must_be_array(dst))
> > > +#define __strscpy1(dst, src, size)     sized_strscpy(dst, src, size)
> >
> > (dst), (src), (size) etc.
>
> I normally don't do this when macro args are being expanded into
> function arguments. I've only done it for when macro args are used in
> expressions. Am I missing a side-effect here, or is this more about
> stylistic consistency?

I'm not 100% sure it is needed, but I'm always wary when using macro
parameters without parentheses, except in the most simple use-cases.

Gr{oetje,eeting}s,

                        Geert

--=20
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k=
org

In personal conversations with technical people, I call myself a hacker. Bu=
t
when I'm talking to journalists I just say "programmer" or something like t=
hat.
                                -- Linus Torvalds