[PATCH v2 0/1] MR10983: wined3d: Handle data aliasing when blitting to itself with FX transforms.

[Paul Gofman (＠gofman)]

--
  v2: wined3d: Handle data aliasing when blitting to itself with FX transforms.
 
https://gitlab.winehq.org/wine/wine/-/merge_requests/10983

[PATCH v2 1/1] wined3d: Handle data aliasing when blitting to itself with FX transforms.

[Paul Gofman]

From: Paul Gofman <[e-mail]>

---
 dlls/wined3d/surface.c | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/dlls/wined3d/surface.c b/dlls/wined3d/surface.c
index cf081a17c68..1e8388410cd 100644
--- a/dlls/wined3d/surface.c
+++ b/dlls/wined3d/surface.c
@@ -826,9 +826,6 @@ static HRESULT surface_cpu_blt(struct wined3d_texture *dst_texture, unsigned int
                     memcpy(dbuf, sbuf, row_byte_count);
                     dbuf += dst_map.row_pitch;
                 }
-
-                if (same_sub_resource)
-                    free(tmp_buffer);
             }
         }
         else
@@ -904,9 +901,6 @@ do { \
                 dbuf += dst_map.row_pitch;
                 last_sy = sy;
             }
-
-            if (same_sub_resource)
-                free(tmp_buffer);
         }
     }
     else
@@ -964,6 +958,18 @@ do { \
             dBottomLeft  = dTopLeft + ((dst_height - 1) * dst_map.row_pitch);
             dBottomRight = dBottomLeft + ((dst_width - 1) * bpp);
 
+            if (same_sub_resource &&
+                    !(dst_box->top < src_box->top || dst_box->right <= src_box->left || src_box->right <= dst_box->left)
+                    && fx->fx & (WINEDDBLTFX_MIRRORLEFTRIGHT | WINEDDBLTFX_MIRRORUPDOWN | WINEDDBLTFX_ROTATE180
+                    | WINEDDBLTFX_ROTATE270 | WINEDDBLTFX_ROTATE90))
+            {
+                if ((tmp_buffer = malloc(src_height * src_map.row_pitch)))
+                {
+                    memcpy(tmp_buffer, sbase, src_height * src_map.row_pitch);
+                    sbase = tmp_buffer;
+                }
+            }
+
             if (fx->fx & WINEDDBLTFX_ARITHSTRETCHY)
             {
                 /* I don't think we need to do anything about this flag. */
@@ -1112,6 +1118,8 @@ error:
         FIXME("    Unsupported flags %#x.\n", flags);
 
 release:
+    free(tmp_buffer);
+
     if (upload && hr == WINED3D_OK)
     {
         struct wined3d_bo_address data;
-- 
GitLab

https://gitlab.winehq.org/wine/wine/-/merge_requests/10983

[Paul Gofman (＠gofman)]

v2:

* free tmp_buffer in just one place throughout the function.

-- 
https://gitlab.winehq.org/wine/wine/-/merge_requests/10983#note_141131

[Henri Verbeet (＠hverbeet)]

Thanks, I think that's better.
> ```diff
> +            if (same_sub_resource &&
> +                    !(dst_box->top < src_box->top || dst_box->right <= src_box->left || src_box->right <= dst_box->left)
> +                    && fx->fx & (WINEDDBLTFX_MIRRORLEFTRIGHT | WINEDDBLTFX_MIRRORUPDOWN | WINEDDBLTFX_ROTATE180
> +                    | WINEDDBLTFX_ROTATE270 | WINEDDBLTFX_ROTATE90))
> ```

Looking a bit closer at this bit, I'm not sure "dst_box->top < src_box->top" is quite right/sufficient. E.g. suppose we have WINEDDBLTFX_MIRRORUPDOWN with
```
  src_box = {.top = 1, .bottom = 6, ...}
  dst_box = {.top = 0, .bottom = 5, ...}
```
I think we'd then copy
```
  row 1 -> 4
  row 2 -> 3
  row 3 -> 2
  row 4 -> 1
  row 5 -> 0
```
and copy data that was already overwritten.

-- 
https://gitlab.winehq.org/wine/wine/-/merge_requests/10983#note_141222