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SubjectRe: [2.6 patch] kill IN_STRING_C
Date
On Monday 08 of November 2004 19:31, you 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)"

[~/rpm/BUILD] # cat sp.c

#include <linux/string.h>
#include <linux/kernel.h>

char buf[128];
void test(char *str)
{
sprintf(buf, "%s", str);
}

[~/rpm/BUILD] # gcc -Wall sp.c -S -O2 -fomit-frame-pointer -mregparm=3
-nostdinc -isystem /usr/src/linux/include

sp.c: In function `test':
sp.c:7: warning: implicit declaration of function `sprintf'

[~/rpm/BUILD] # cat sp.s

.file "sp.c"
.text
.p2align 4,,15
.globl test
.type test, @function
test:
movl %eax, %edx
movl $buf, %eax
jmp strcpy
.size test, .-test
.comm buf,128,32
.section .note.GNU-stack,"",@progbits
.ident "GCC: (GNU) 3.4.3 (PLD Linux)"


What now?

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/* Copyright (C) 2003, SCO, Inc. This is valuable Intellectual Property. */

#define say(x) lie(x)
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