Possible issue in dlls/d3dx9_36/surface.c?

[Matteo Bruni]

On Sat, 2011-04-02 at 23:54 +0200, Gerald Pfeifer wrote:
> Matteo et al,
> 
> there is some code in dlls/d3dx9_36/surface.c which GCC struggles with
> (in the sense of warning about it), and so do I, so I am wondering whether
> you can have a look?
> 
> Specifically, in point_filter_simple_data we have:
> 
>        DWORD val = 0, pixel;
> 
>        /* extract source color components */
>        if(srcformat->type == FORMAT_ARGB) {
>            pixel = dword_from_bytes(srcptr, srcformat->bytes_per_pixel);
>            get_relevant_argb_components(&conv_info, pixel, channels);
>        }
> 
> So, pixel is uninitialized, except when we have FORMAT_ARGB.
> 
> However, directly below we then have
> 
>        /* recombine the components */
>        if(destformat->type == FORMAT_ARGB) val = make_argb_color(&conv_info, channels);
> 
>        if(colorkey) {
>            get_relevant_argb_components(&ck_conv_info, pixel, channels);
> 
> where pixel is passed to get_relevant_argb_components.  This is guarded
> by colorkey, a parameter to this function, so indeed I can see pixel being
> unused here.
> 

Currently that is not a real problem, as every pixel format has type
FORMAT_ARGB (you can see that from the formats array in util.c). Surely
the code could be nicer though.

> 
> (I'd naively propose a patch like the one below; this may not be 
> sufficient though.)
> 
> Gerald
> 
> 
> diff --git a/dlls/d3dx9_36/surface.c b/dlls/d3dx9_36/surface.c
> index a3e6e68..cc36818 100644
> --- a/dlls/d3dx9_36/surface.c
> +++ b/dlls/d3dx9_36/surface.c
> @@ -701,7 +701,7 @@ static void copy_simple_data(CONST BYTE *src, UINT srcpitch, POINT srcsize,
>          DWORD val = 0;
>  
>          for(x = 0;x < minwidth;x++) {
> -            DWORD pixel;
> +            DWORD pixel = 0xFFFFFFFF;
>  
>              /* extract source color components */
>              if(srcformat->type == FORMAT_ARGB) {
> @@ -768,7 +768,7 @@ static void point_filter_simple_data(CONST BYTE *src, UINT srcpitch, POINT srcsi
>  
>          for(x = 0;x < destsize.x;x++) {
>              const BYTE *srcptr = bufptr + (x * srcsize.x / destsize.x) * srcformat->bytes_per_pixel;
> -            DWORD val = 0, pixel;
> +            DWORD val = 0, pixel = 0xFFFFFFFF;
>  
>              /* extract source color components */
>              if(srcformat->type == FORMAT_ARGB) {

That would silence the warnings but it doesn't look to me as the right
fix. I think the easiest is to just move the format type checks from
copy_simple_data and point_filter_simple_data to
D3DXLoadSurfaceFromMemory (which is the only caller) and bail out if the
source or the destination format is not FORMAT_ARGB.

I can prepare a patch for that, if you don't feel like giving it a try.
Thanks for the heads-up in any case. :)