gdi32/bitblt: GdiAlphaBlend - Check for NULL Pointer (incl. testcase)

[Markus Stockhausen]

Am Freitag, den 18.09.2009, 14:09 +0200 schrieb Paul Vriens:
> On 09/18/2009 01:42 PM, Markus Stockhausen wrote:
> > Hi,
> >
> > as I was encouraged to resent the patch from last week in git format I
> > hope it will be better this time.
> >
> > Best regards
> >
> >
> > ------------------------------------------------------------------------
> >
> >
> Hi Markus,
> 
> After reading this patch again, it seems to me it's not a 100% correct. 
> There is a slight difference in passing hdcSrc as NULL compared to 
> retrieving dcSrc via get_dc_ptr.
> 
> The actual test sets hdcSrc to NULL, so the corresponding test in the 
> implementation should be:
> 
> if (!hdcSrc)
>      return FALSE;
> 
> dcSrc = get_dc_ptr ( hdcSrc );
> 
> Now, I don't know whether get_dc_ptr can fail but that's a different matter.
> 

Hi Paul,

thanks for your attention but if I go through the whole dc_* stuff I can
see that it will return NULL to dcSrc if an error occurs somewhere. This
maybe because auf hdcSrc being NULL (other cases included). This would
result in two cases to check:

1. Check if hdcSrc is not NULL (will be done in the dc_ functions).
2. Check if dcSrc is not NULL (that is missing)

I'm a little bit lost if more testcases are needed.

Best regards.