From: Sergei Organov <osv@javad.com>
To: Bodo Eggert <7eggert@gmx.de>
Cc: "Linus Torvalds" <torvalds@linux-foundation.org>,
"J.A. MagallÃÃón" <jamagallon@ono.com>,
"Jan Engelhardt" <jengelh@linux01.gwdg.de>,
"Jeff Garzik" <jeff@garzik.org>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
"Andrew Morton" <akpm@linux-foundation.org>
Subject: Re: somebody dropped a (warning) bomb
Date: Mon, 19 Feb 2007 15:17:03 +0300 [thread overview]
Message-ID: <87ejomgx4w.fsf@javad.com> (raw)
In-Reply-To: <Pine.LNX.4.58.0702161553050.2481@be1.lrz> (Bodo Eggert's message of "Fri, 16 Feb 2007 18:40:02 +0100 (CET)")
Bodo Eggert <7eggert@gmx.de> writes:
> On Fri, 16 Feb 2007, Sergei Organov wrote:
[...]
> I'll say it again: Either the code using unspecified chars is correct, or
> it isn't. If it's correct, neither using with signed nor with unsigned
> chars is a bug and you should not warn at all, and if it's not correct,
> you should always warn. Instead, gcc warns on "code compiles for
> $arch".
Here is where we disagree. In my opinion, no matter what the sign of
char for given architecture is, it's incorrect to pass either "signed
char*" or "unsigned char*" argument to a function expecting "char*".
>> > Therefore it's either always wrong to call your char* function with char*,
>> > unsigned char* _and_ signed char unless you can guarantee not to overflow any
>> > of them, or it's always correct to call char* functions with any kind
>> > of these.
>>
>> How are you sure those who wrote foo(char*) agrees with your opinion or
>> even understands all the involved issues?
>
> Let's asume we have this piece of buggy code. We compile it on an unsigned
> char architecture. No warning. *BOOM*
There should be warning, -- that's my point. "char" is different. "char"
is distinct from either "signed char" or "unsigned char". Always. At
least it's how C is defined.
> Let's asume there is correct code, and we use it as designed:
> Warning: Wrong arch
> Warning: Wrong arch
> Warning: Wrong arch
> Warning: real issue
> Warning: Wrong arch
> Warning: Wrong arch
> Warning: Wrong arch
> Warning: Wrong arch
> <scroll off screen/>
> Warning: Wrong arch
> Warning: Wrong arch
> Warning: Wrong arch
> Warning: Wrong arch
> Warning: Wrong arch
>
> You don't see "real issue". *BOOM*
>
>
> What can you do about this warning? Let's asume we cast everywhere:
I already gave an answer in response to Linus:
static inline size_t ustrlen(const unsigned char *s)
{
return strlen((const char *)s);
}
>
> struct foo * p;
> printf(strlen(char*)p); *BOOM*
printf(ustrlen(p)); *NO BOOM*
unsigned char* u;
printf(ustrlen(u)); *NO WARNING*
-- Sergei.
next prev parent reply other threads:[~2007-02-19 12:17 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <7Mj5f-3oz-21@gated-at.bofh.it>
[not found] ` <7MktH-5EW-35@gated-at.bofh.it>
[not found] ` <7Mmvy-vj-17@gated-at.bofh.it>
[not found] ` <7MnBC-2fk-13@gated-at.bofh.it>
[not found] ` <7MoQx-4p8-11@gated-at.bofh.it>
[not found] ` <7MpjE-50z-7@gated-at.bofh.it>
[not found] ` <7MpCS-5Fe-9@gated-at.bofh.it>
[not found] ` <7MDd7-17w-1@gated-at.bofh.it>
[not found] ` <7MGkB-62k-31@gated-at.bofh.it>
[not found] ` <7NHoe-2Mb-37@gated-at.bofh.it>
[not found] ` <7NMe9-1ZN-7@gated-at.bofh.it>
[not found] ` <7Oagl-6bO-1@gated-at.bofh.it>
[not found] ` <7ObvW-89N-23@gated-at.bofh.it>
[not found] ` <7Oc8t-NS-1@gated-at.bofh.it>
2007-02-15 20:08 ` somebody dropped a (warning) bomb Bodo Eggert
2007-02-16 11:21 ` Sergei Organov
2007-02-16 14:51 ` Bodo Eggert
2007-02-19 11:56 ` Sergei Organov
2007-02-16 12:46 ` Sergei Organov
2007-02-16 17:40 ` Bodo Eggert
2007-02-19 12:17 ` Sergei Organov [this message]
2007-02-08 15:00 Jeff Garzik
2007-02-08 16:33 ` Linus Torvalds
2007-02-08 18:42 ` Jan Engelhardt
2007-02-08 19:53 ` Linus Torvalds
2007-02-08 21:10 ` Jan Engelhardt
2007-02-08 21:37 ` Linus Torvalds
2007-02-08 23:12 ` David Rientjes
2007-02-08 23:37 ` Linus Torvalds
2007-02-09 0:24 ` David Rientjes
2007-02-09 0:42 ` Linus Torvalds
2007-02-09 0:59 ` Linus Torvalds
2007-02-09 0:59 ` David Rientjes
2007-02-09 1:11 ` Linus Torvalds
2007-02-09 1:18 ` David Rientjes
2007-02-09 15:38 ` Linus Torvalds
2007-02-09 3:27 ` D. Hazelton
2007-02-09 19:54 ` Pete Zaitcev
2007-02-09 12:34 ` Jan Engelhardt
2007-02-09 13:16 ` linux-os (Dick Johnson)
2007-02-09 17:45 ` Jan Engelhardt
2007-02-09 20:29 ` linux-os (Dick Johnson)
2007-02-09 22:05 ` Jan Engelhardt
2007-02-09 22:58 ` Martin Mares
2007-02-12 18:50 ` linux-os (Dick Johnson)
2007-02-13 15:14 ` Dick Streefland
2007-02-08 21:13 ` J.A. Magallón
2007-02-08 21:42 ` Linus Torvalds
2007-02-08 22:03 ` Linus Torvalds
2007-02-08 22:19 ` Willy Tarreau
2007-02-09 0:03 ` J.A. Magallón
2007-02-09 0:22 ` Linus Torvalds
2007-02-09 12:38 ` Sergei Organov
2007-02-09 15:58 ` Linus Torvalds
2007-02-12 11:12 ` Sergei Organov
2007-02-12 16:26 ` Linus Torvalds
2007-02-13 18:06 ` Sergei Organov
2007-02-13 18:26 ` Pekka Enberg
2007-02-13 19:14 ` Sergei Organov
2007-02-13 19:43 ` Pekka Enberg
2007-02-13 20:29 ` Sergei Organov
2007-02-13 21:31 ` Jeff Garzik
2007-02-13 23:21 ` Linus Torvalds
2007-02-15 13:20 ` Sergei Organov
2007-02-15 15:57 ` Linus Torvalds
2007-02-15 18:53 ` Sergei Organov
2007-02-15 19:02 ` Linus Torvalds
2007-02-16 4:26 ` Rene Herman
2007-02-19 11:58 ` Sergei Organov
2007-02-19 13:58 ` Sergei Organov
2007-02-15 22:32 ` Lennart Sorensen
2007-02-13 19:25 ` Linus Torvalds
2007-02-13 19:59 ` Sergei Organov
2007-02-13 20:24 ` Linus Torvalds
2007-02-15 15:15 ` Sergei Organov
2007-02-13 21:13 ` Rob Landley
2007-02-13 22:21 ` Olivier Galibert
2007-02-14 12:52 ` Sergei Organov
2007-02-15 20:06 ` Sergei Organov
2007-02-09 15:10 ` Sergei Organov
2007-02-08 16:35 ` Kumar Gala
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