ddraw: Don't release ddraw if a surface is still using it.

[Jens Albretsen]

On Saturday 31 May 2008 14:57:25 Michael Karcher wrote:
> Am Samstag, den 31.05.2008, 12:08 +0200 schrieb Jens Albretsen:
> The patch looks like it would work as advertised, but the following
>
> snippet in the testcase smells fishy:
> > +static unsigned long getRefcount(IUnknown *iface)
> > +{
> > +    IUnknown_AddRef(iface);
> > +    return IUnknown_Release(iface);
> > +}
>
> [...]
>
> > +    IDirectDraw_Release(lpDD);
> > +
> > +    ref = getRefcount(lpDD);
> > +    ok(ref == 0, "Got refcount %ld, expected 0\n", ref);
> > +
> > +    IUnknown_Release(surface);
>
> The IDirectDraw_Release seems to be dropping the reference count of the
> DirectDraw object to zero. This is OK, of course, as you might well drop
> the last reference. But this might put the DirectDraw object into a
> state where AddRef crashes, as parts of the object might get destroyed
> when the reference count drops down to zero.
>
> On wine, there is obviously no problem, as wine keeps the DirectDraw
> object itself alive for longer. On Windows, it is not clear to me that
> the DirectDraw object is not destroyed at the IDirectDraw_Release, the
> only thing we know is, that Direct Draw still is working (perhaps
> implemented by a subobject of the DirectDraw object which keeps living).

Someone please run the test on windows, I have no windows installation.

> I suggest to alternatively write the second part as
> 
> +    ref = IDirectDraw_Release(lpDD);
> +    ok(ref == 0, "Got refcount %ld, expected 0\n", ref);
> +
> +    IUnknown_Release(surface);

It would pretty much kill the idea of the test.

The game demo does this, and runs in windows.
I'm trying to emulated the behavior of windows, it fails miserably in wine as 
the ddraw object suddenly disappears.
I can only see what the demo tries to do and make a fix for that, since I have 
no way of checking it in windows myself.
Anyway it makes wine stop crashing when programs tries to do something crazy 
like this. Stefan Dösinger asked me to put a HeapAlloc all memory between the 
two Release's to check if the memory of ddraw object would be corrupt in 
Windows. It really doesn't matter if programs live by chance in windows, if 
we can implement it so it's not by chance anymore. Isn't that better. 

> Regards,
>   Michael Karcher

Cheers,
Jens Albretsen