Re: [PATCH] make memcmp arguments const

[Stefan Assmann <sassmann@suse.de>]

Hi Simon,

Simon Horman wrote:
> On Mon, Nov 03, 2008 at 03:34:36PM +0100, Stefan Assmann wrote:
>> In purgatory/string.c the definition of memcmp is
>> 	int memcmp(void *src1, void *src2, size_t len)
>> man memcmp reveals
>> 	int memcmp(const void *s1, const void *s2, size_t n)
>>
>> Signed-off-by: Stefan Assmann <sassmann@suse.de>
>>
>> ---
>>  purgatory/string.c |    4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> --- a/purgatory/string.c
>> +++ b/purgatory/string.c
>> @@ -36,9 +36,9 @@ void* memcpy(void *dest, const void *src
>>  }
>>
>>
>> -int memcmp(void *src1, void *src2, size_t len)
>> +int memcmp(const void *src1, const void *src2, size_t len)
>>  {
>> -	unsigned char *s1, *s2;
>> +	const unsigned char *s1, *s2;
>>  	size_t i;
>>  	s1 = src1;
>>  	s2 = src2;
> 
> Hi Stefan,
> 
> this change seems reasonable to me, but I think that
> the declaration also needs to be updated. If the change
> below is fine by you, could you please add it to your patch
> and repost ?

You're right, I forgot to change that. New patch is appended.

> 
> # gcc --version
> gcc (Debian 4.3.2-1) 4.3.2
> Copyright (C) 2008 Free Software Foundation, Inc.
> This is free software; see the source for copying conditions.  There is NO
> warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
> 
> # make
> ...
> gcc -Wall -O2 -fomit-frame-pointer -pipe -fno-strict-aliasing -Wall -Wstrict-prototypes -fno-zero-initialized-in-bss  -Os -fno-builtin -ffreestanding  -I./purgatory/include -I./purgatory/arch/i386/include -I./util_lib/include -I/usr/lib/gcc/i486-linux-gnu/4.3.2/include  -c -MD -o purgatory/string.o purgatory/string.c
> purgatory/string.c:39: error: conflicting types for ‘memcmp’
> ./purgatory/include/string.h:9: error: previous declaration of ‘memcmp’ was
> here
> make: *** [purgatory/string.o] Error 1
> 
> Index: kexec-tools/purgatory/include/string.h
> ===================================================================
> --- kexec-tools.orig/purgatory/include/string.h	2008-11-04 09:07:48.000000000 +1100
> +++ kexec-tools/purgatory/include/string.h	2008-11-04 09:08:02.000000000 +1100
> @@ -6,7 +6,7 @@
>  size_t strnlen(const char *s, size_t max);
>  void* memset(void* s, int c, size_t n);
>  void* memcpy(void *dest, const void *src, size_t len);
> -int memcmp(void *src1, void *src2, size_t len);
> +int memcmp(const void *src1, const void *src2, size_t len);
>  
>  
>  #endif /* STRING_H */
> 

Signed-off-by: Stefan Assmann <sassmann@suse.de>

---
 purgatory/include/string.h |    2 +-
 purgatory/string.c         |    4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

--- a/purgatory/string.c
+++ b/purgatory/string.c
@@ -36,9 +36,9 @@ void* memcpy(void *dest, const void *src
 }


-int memcmp(void *src1, void *src2, size_t len)
+int memcmp(const void *src1, const void *src2, size_t len)
 {
-	unsigned char *s1, *s2;
+	const unsigned char *s1, *s2;
 	size_t i;
 	s1 = src1;
 	s2 = src2;
--- a/purgatory/include/string.h
+++ b/purgatory/include/string.h
@@ -6,7 +6,7 @@
 size_t strnlen(const char *s, size_t max);
 void* memset(void* s, int c, size_t n);
 void* memcpy(void *dest, const void *src, size_t len);
-int memcmp(void *src1, void *src2, size_t len);
+int memcmp(const void *src1, const void *src2, size_t len);


 #endif /* STRING_H */
-- 
Stefan Assmann          | SUSE LINUX Products GmbH
Software Engineer       | Maxfeldstr. 5, D-90409 Nuernberg
Mail : sassmann@suse.de | GF: Markus Rex, HRB 16746 (AG Nuernberg)

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