[U-Boot] [PATCH V2] memcpy/memmove: Do not copy to same address

Alexander Holler
2011-05-23T22:12:06Z

Am 23.05.2011 23:55, schrieb Wolfgang Denk:
> Dear Alexander Holler,
>
> In message<4DDACC8B.6090507@ahsoftware.de> you wrote:
>>
>>> --- a/lib/string.c
>>> +++ b/lib/string.c
>>> @@ -467,6 +467,9 @@ void * memcpy(void *dest, const void *src, size_t count)
>>> unsigned long *dl = (unsigned long *)dest, *sl = (unsigned long *)src;
>>> char *d8, *s8;
>>>
>>> + if (src == dest)
>>> + return dest;
>>> +
>>
>> here is the same, as in the patch I've commented before. There exist no
>> reason to add a check for identity to memcpy() because memcpy doesn't
>> support overlapping regions (and identity is just a special case of
>> overlapping regions). If something might call memcpy() with overlapping
>> or identical regions, it should use memmove().
>
> In an ideal world, nobody will ever use any interfces in a
> non-compliant or incorrect way.
>
> In reality, all kind of errors happen. A little defensive programming
> like the one above helps a lot, so please stop complaining even if you
> think you don't need this.

So you I will look forward to checks for NULL pointers and similiar in
all C standard functions implemented in u-boot to circumvent tons of
possible real world bugs in all callers of strcpy, strlen, mem* and
whatever.

Reads promising,

regards,

Alexander