Re: [2.6 patch] kill IN_STRING_C

[Adrian Bunk]

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

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed

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