linux-kernel - Re: [PATCH] x86: small unifications of address printing

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Message-ID: <19f34abd0807011212w5e95f58aw998c74014f1d6632@mail.gmail.com>
Date:	Tue, 1 Jul 2008 21:12:26 +0200
From:	"Vegard Nossum" <vegard.nossum@...il.com>
To:	"Andi Kleen" <andi@...stfloor.org>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86: small unifications of address printing

On Tue, Jul 1, 2008 at 8:58 PM, Andi Kleen <andi@...stfloor.org> wrote:
>
>> Yes, it will, and correctly too:
>>
>>         case 'p':
>>                 flags |= SMALL;
>>                 if (field_width == -1) {
>>                         field_width = 2*sizeof(void *);
>>                         flags |= ZEROPAD;
>>                 }
>>
>> Or did I read this code wrong? field_width is initialized to -1 by
>> default unless overridden. The SMALL flag means lowercase hexadecimal
>> digits.
>
> You're right. The kernel differs from user space/traditional behaviour
> in this regard.

...in this regard _too_ ;-)

I just ran a short test with glibc, and I'm surprised to see that this
implementation is not zero-padding the number.

The C99 standard has this to say:

  "The argument shall be a pointer to void. The value of the pointer is
  converted to a sequence of printing characters, in an implementation-defined
  manner."

so I suppose it's quite alright after all.

Thanks for looking.


Vegard

-- 
"The animistic metaphor of the bug that maliciously sneaked in while
the programmer was not looking is intellectually dishonest as it
disguises that the error is the programmer's own creation."
	-- E. W. Dijkstra, EWD1036
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