From: David Laight <David.Laight@ACULAB.COM>
To: 'Bernd Petrovitsch' <bernd@petrovitsch.priv.at>,
'Joe Perches' <joe@perches.com>,
LKML <linux-kernel@vger.kernel.org>
Cc: kernel-janitors <kernel-janitors@vger.kernel.org>
Subject: RE: Use of '%#02x' is almost always wrong
Date: Thu, 14 Oct 2021 08:27:17 +0000 [thread overview]
Message-ID: <5cf03008e8784b7797feaf3d8ccfa303@AcuMS.aculab.com> (raw)
In-Reply-To: <9bae5c76-db1e-b9e3-cdfa-ab22f9d8b58c@petrovitsch.priv.at>
From: Bernd Petrovitsch
> Sent: 14 October 2021 00:16
>
> On 12/10/2021 23:10, David Laight wrote:
> [...]
> >> So presumably all the uses of %#02x in the kernel are not outputting
> >> what is actually expected. Perhaps all of these should use %#04x.
> >
> > Doesn't help. The definition of "%#x" is completely broken.
>
> Seconded ...
>
> > Basically 0 doesn't get the "0x" prefix, so "%#04x" outputs
> > "0000".
>
> ... just because of that.
> And if one get's in touch with tools where format strings are
> the % -stuff is not consistently used ...
>
> > "0000" if the value is zero.
> > So the correct replacement is (probably) "0x%02x".
>
> At least it's consistent that way.
>
> And in the big techie picture, I don't see what the '#' modifer
> buys and why it makes sense to use it.
It works for "%#8x" where it add the "0x" to the right-aligned
hex digits.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2021-10-14 8:27 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-10 16:45 Use of '%#02x' is almost always wrong Joe Perches
2021-10-12 21:10 ` David Laight
2021-10-13 23:16 ` Bernd Petrovitsch
2021-10-14 8:27 ` David Laight [this message]
2021-10-13 6:15 ` Dan Carpenter
2021-10-13 8:17 ` Joe Perches
2021-10-13 10:39 ` Dan Carpenter
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