2003-08-13 18:38:45

by Stephen Hemminger

[permalink] [raw]
Subject: [PATCH] get rid of bcopy warning

Get rid of warning because internal definition of bcopy
conflicts with builtin. The warning is probably a bogus
bug of GCC 3.2.3, but the workaround is simple.

Almost no driver really uses bcopy anyway, and no code
uses the return value.

diff -Nru a/lib/string.c b/lib/string.c
--- a/lib/string.c Wed Aug 13 11:31:13 2003
+++ b/lib/string.c Wed Aug 13 11:31:13 2003
@@ -432,14 +432,13 @@
* You should not use this function to access IO space, use memcpy_toio()
* or memcpy_fromio() instead.
*/
-char * bcopy(const char * src, char * dest, int count)
+void bcopy(const void * src, void * dest, size_t count)
{
+ const char *s = src;
char *tmp = dest;

while (count--)
- *tmp++ = *src++;
-
- return dest;
+ *tmp++ = *s++;
}
#endif


2003-08-13 19:17:46

by Richard B. Johnson

[permalink] [raw]
Subject: Re: [PATCH] get rid of bcopy warning

On Wed, 13 Aug 2003, Stephen Hemminger wrote:

> Get rid of warning because internal definition of bcopy
> conflicts with builtin. The warning is probably a bogus
> bug of GCC 3.2.3, but the workaround is simple.
>
> Almost no driver really uses bcopy anyway, and no code
> uses the return value.

There should never have been a return value from a function
called bcopy() anyway.

>
> diff -Nru a/lib/string.c b/lib/string.c
> --- a/lib/string.c Wed Aug 13 11:31:13 2003
> +++ b/lib/string.c Wed Aug 13 11:31:13 2003
> @@ -432,14 +432,13 @@
> * You should not use this function to access IO space, use memcpy_toio()
> * or memcpy_fromio() instead.
> */
> -char * bcopy(const char * src, char * dest, int count)
> +void bcopy(const void * src, void * dest, size_t count)
> {
> + const char *s = src;
> char *tmp = dest;
>
> while (count--)
> - *tmp++ = *src++;
> -
> - return dest;
> + *tmp++ = *s++;
> }
> #endif
>

This whole thing is bogus. bcopy() is supposed to handle
copies of overlapping buffers (IEEE Std 1003.1-2001).

This means that if destination is at a greater offset than the
source, the data has to be copied backwards. The code above
is broken.

Cheers,
Dick Johnson
Penguin : Linux version 2.4.20 on an i686 machine (797.90 BogoMips).
Note 96.31% of all statistics are fiction.