[PATCH v2 0/1] MR2723: evr: Fix incorrect integral computation.

[eric pouech (＠epo)]

Note: typeof (int * unsigned) is unsigned.
So:
- on 64bit CPUs, where sizeof(int) = 4 < sizeof(void*) = 8,
- when the result of the multiplication is supposed to be negative
- there's no progation of the negative sign from 32bit to 64 bit integers

Fixes a crash in Age of Empire II.

Signed-off-by: Eric Pouech

--
  v2: evr: Fix incorrect integral computation.

https://gitlab.winehq.org/wine/wine/-/merge_requests/2723

[PATCH v2 1/1] evr: Fix incorrect integral computation.

[Eric Pouech]

From: Eric Pouech

Note: typeof (int * unsigned) is unsigned.
So:
- on 64bit CPUs, where sizeof(int) = 4 < sizeof(void*) = 8,
- when the result of the multiplication is supposed to be negative
- there's no progation of the negative sign from 32bit to 64 bit integers

Fixes a crash in Age of Empire II.

Signed-off-by: Eric Pouech 
---
 dlls/evr/evr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/dlls/evr/evr.c b/dlls/evr/evr.c
index 26a2a3a1eb5..803c1d2dff9 100644
--- a/dlls/evr/evr.c
+++ b/dlls/evr/evr.c
@@ -382,7 +382,7 @@ static HRESULT evr_copy_sample_buffer(struct evr *filter, IMediaSample *input_sa
         {
             if (SUCCEEDED(hr = IDirect3DSurface9_LockRect(surface, &locked_rect, NULL, D3DLOCK_DISCARD)))
             {
-                if (src_stride < 0) src -= src_stride * (lines - 1);
+                if (src_stride < 0) src += (-src_stride) * (lines - 1);
                 MFCopyImage(locked_rect.pBits, locked_rect.Pitch, src, src_stride, width * 4, lines);
                 IDirect3DSurface9_UnlockRect(surface);
             }

[eric pouech (＠epo)]

On Wed May  3 07:00:46 2023 +0000, Alexandre Julliard wrote:
> > one could event prefer adding a positive integer to subtracting a
>
> negative one:
> > if (src_stride < 0) src += (-src_stride) * (lines - 1);
> >
> > which I find more readable to show to intent to walk the image
>
> starting from last line in memory order
> Yes, that's definitely better.

V2 pushed with that change instead

[PATCH v2 0/1] MR2723: evr: Fix incorrect integral computation. - approved

[Nikolay Sivov (＠nsivov)]

This merge request was approved by Nikolay Sivov.