Fixed NULL pointer dereference

--HG--
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/trunk%403496

CREDITS

@@ -25,8 +25,9 @@ Thanks to everyone who made this possible, including:
 * Szymon "Wilku" Wilczek for adding support for multiple mice and tablets
   during the Google Summer of Code 2008
 
-* Marty Leisner, Andrew, Will, Edgar Simo, Donny Viszneki, and Couriersud
-  for helping find SDL 1.3 bugs in the great SDL Bug Hunt of January 2009!
+* Marty Leisner, Andrew, Will, Edgar Simo, Donny Viszneki, Andrea Mazzoleni,
+  and Couriersud for helping find SDL 1.3 bugs in the great SDL Bug Hunt
+  of January 2009!
 
 * Donny Viszneki for helping fix SDL 1.3 bugs in the great SDL Bug Hunt of
   January 2009!

include/SDL_compat.h

@@ -228,8 +228,7 @@ extern DECLSPEC const SDL_VideoInfo *SDLCALL SDL_GetVideoInfo(void);
 extern DECLSPEC int SDLCALL SDL_VideoModeOK(int width,
                                             int height,
                                             int bpp, Uint32 flags);
-extern DECLSPEC SDL_Rect **SDLCALL SDL_ListModes(SDL_PixelFormat * format,
-                                                 Uint32 flags);
+extern DECLSPEC SDL_Rect **SDLCALL SDL_ListModes(const SDL_PixelFormat * format, Uint32 flags);
 extern DECLSPEC SDL_Surface *SDLCALL SDL_SetVideoMode(int width,
                                                       int height,
                                                       int bpp, Uint32 flags);

src/SDL_compat.c

@@ -114,7 +114,7 @@ SDL_VideoModeOK(int width, int height, int bpp, Uint32 flags)
 }
 
 SDL_Rect **
-SDL_ListModes(SDL_PixelFormat * format, Uint32 flags)
+SDL_ListModes(const SDL_PixelFormat * format, Uint32 flags)
 {
     int i, nmodes;
     SDL_Rect **modes;
@@ -127,6 +127,10 @@ SDL_ListModes(SDL_PixelFormat * format, Uint32 flags)
         return (SDL_Rect **) (-1);
     }
 
+    if (!format) {
+        format = SDL_GetVideoInfo()->vfmt;
+    }
+
     /* Memory leak, but this is a compatibility function, who cares? */
     nmodes = 0;
     modes = NULL;