[Scummvm-devel] simon1 windows - 64 bit segfault

[Max Horn]

Am 19.08.2007 um 23:48 schrieb Mark Weaver:

> The attached patch fixes a segfault on x86_64 on entering the room  
> with the blacksmith (from start, out of cottage, right) in Simon  
> the Sorcerer 1 (CD/Windows/English).
>
> Basically x is negative there, so cast to a uint this is a large  
> value.  On ia32 when added to getBackground() this will overflow  
> and become a valid pointer again (I believe, not tested), on x86_64  
> it does not overflow and so segfaults when dereferencing the  
> pointer.  I have fixed this simply by using a signed int for xoffs/ 
> yoffs, which promotes correctly.
> Index: draw.cpp
> ===================================================================
> --- draw.cpp	(revision 28664)
> +++ draw.cpp	(working copy)
> @@ -503,8 +503,8 @@
>  	if (_window3Flag == 1) {
>  		animTable->srcPtr = (const byte *)_window4BackScn;
>  	} else {
> -		uint xoffs = (_videoWindows[vsp->windowNum * 4 + 0] * 2 + x) * 8;
> -		uint yoffs = (_videoWindows[vsp->windowNum * 4 + 1] + y);
> +		int xoffs = (_videoWindows[vsp->windowNum * 4 + 0] * 2 + x) * 8;
> +		int yoffs = (_videoWindows[vsp->windowNum * 4 + 1] + y);
>  		animTable->srcPtr = getBackGround() + xoffs + yoffs * _screenWidth;
>  	}
>

Great, sounds reasonable. Does this by chance fix bug #1769644?  
(https://sourceforge.net/tracker/index.php? 
func=detail&aid=1769644&group_id=37116&atid=418820)

Cheers,
Max