Re: [PATCH v3 2/7] lib/vsprintf: Add support for generic FOURCCs by extending %p4cc

["Russell King (Oracle)" <linux@xxxxxxxxxxxxxxx>]

On Mon, Nov 14, 2022 at 04:15:50PM +0000, Russell King (Oracle) wrote:
> On Mon, Nov 14, 2022 at 04:34:07PM +0100, Petr Mladek wrote:
> > >  	orig = get_unaligned(fourcc);
> > > -	val = orig & ~BIT(31);
> > > +	switch (fmt[2]) {
> > > +	case 'h':
> > > +		val = orig;
> > > +		break;
> > > +	case 'r':
> > > +		val = orig = swab32(orig);
> > 
> > I do not like much these multi assignments. I think that the result
> > was not even defined in some older C standards. Though, I can't find
> > it now. And even make W=3 does not warn about it.
> 
> Err.
> 
> It's been supported for decades. I learnt about it back in 1992 when
> I was introduced to C by another experienced C programmer. It's been
> supported in ANSI C compilers. The Norcroft C compiler (which is
> strict ANSI) on Acorn platforms back in the late 1980s/1990s even
> supported it.
> 
> I think you're a bit out of date.

Oh, and it's not like there isn't precedent for doing this in
lib/vsprintf.c:

841a915d20c7 vsprintf: Do not have bprintf dereference pointers

+                                       len = copy = strlen(args);

If you grep lib/, there's many more examples. So, what is in Hectors
patch is in no way any different from lots of other examples already
merged into the kernel code.

-- 
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