From 63c4e6ff57d53a807feec2222e1199f5b6fcdb42 Mon Sep 17 00:00:00 2001
From: FunkyFr3sh <cc.red.alert.1@googlemail.com>
Date: Thu, 6 May 2021 01:24:07 +0200
Subject: [PATCH] fix DeleteAttachedSurface and add some NULL checks

---
 src/ddsurface.c | 22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/src/ddsurface.c b/src/ddsurface.c
index 6dc684c..b520577 100644
--- a/src/ddsurface.c
+++ b/src/ddsurface.c
@@ -14,14 +14,17 @@
 
 HRESULT dds_AddAttachedSurface(IDirectDrawSurfaceImpl *This, LPDIRECTDRAWSURFACE lpDDSurface)
 {
-    IDirectDrawSurface_AddRef(lpDDSurface);
-
-    if (g_ddraw->backbuffer && !This->backbuffer)
+    if (lpDDSurface)
     {
-        IDirectDrawSurfaceImpl* surface = (IDirectDrawSurfaceImpl*)lpDDSurface;
-        surface->caps |= DDSCAPS_BACKBUFFER;
+        IDirectDrawSurface_AddRef(lpDDSurface);
 
-        This->backbuffer = surface;
+        if (g_ddraw->backbuffer && !This->backbuffer)
+        {
+            IDirectDrawSurfaceImpl* surface = (IDirectDrawSurfaceImpl*)lpDDSurface;
+            surface->caps |= DDSCAPS_BACKBUFFER;
+
+            This->backbuffer = surface;
+        }
     }
 
     return DD_OK;
@@ -611,7 +614,12 @@ HRESULT dds_BltFast(IDirectDrawSurfaceImpl *This, DWORD dst_x, DWORD dst_y, LPDI
 
 HRESULT dds_DeleteAttachedSurface(IDirectDrawSurfaceImpl *This, DWORD dwFlags, LPDIRECTDRAWSURFACE lpDDSurface)
 {
-    IDirectDrawSurface_Release(lpDDSurface);
+    if (lpDDSurface)
+    {
+        IDirectDrawSurface_Release(lpDDSurface);
+        This->backbuffer = NULL;
+    }
+
     return DD_OK;
 }