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SubjectRe: [2.6 patch] kill IN_STRING_C
On Mon, 8 Nov 2004, Adrian Bunk wrote:

> On Mon, Nov 08, 2004 at 07:04:13PM +0100, Pawe?? Sikora wrote:
>> On Monday 08 of November 2004 17:31, you wrote:
>>> On Mon, Nov 08, 2004 at 05:19:35PM +0100, Andi Kleen wrote:
>>>>> Rethinking it, I don't even understand the sprintf example in your
>>>>> changelog entry - shouldn't an inclusion of kernel.h always get it
>>>>> right?
>>>>
>>>> Newer gcc rewrites sprintf(buf,"%s",str) to strcpy(buf,str)
>>>> transparently.
>>>
>>> Which gcc is "Newer"?
>>>
>>> My gcc 3.4.2 didn't show this problem.
>>
>> #include <stdio.h>
>> #include <string.h>
>> char buf[128];
>> void test(char *str)
>> {
>> sprintf(buf, "%s", str);
>> }
>> ...
>> jmp strcpy
>> ...
>
>
> This is the userspace example.
>
> The kernel example is:
>
> #include <linux/string.h>
> #include <linux/kernel.h>
>
> char buf[128];
> void test(char *str)
> {
> sprintf(buf, "%s", str);
> }
>
>
> This results with gcc-3.4 (GCC) 3.4.2 (Debian 3.4.2-3) in:
>
> .file "test.c"
> .section .rodata.str1.1,"aMS",@progbits,1
> .LC0:
> .string "%s"
> .text
> .p2align 4,,15
> .globl test
> .type test, @function
> test:
> pushl %eax
> pushl $.LC0
> pushl $buf
> call sprintf
> addl $12, %esp
> ret
> .size test, .-test
> .globl buf
> .bss
> .align 32
> .type buf, @object
> .size buf, 128
> buf:
> .zero 128
> .section .note.GNU-stack,"",@progbits
> .ident "GCC: (GNU) 3.4.2 (Debian 3.4.2-3)"
>
>
>
> cu
> Adrian
>

On this compiler 3.3.3, -O2 will cause it to use strcpy().

Cheers,
Dick Johnson
Penguin : Linux version 2.6.9 on an i686 machine (5537.79 BogoMips).
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