Re: [Chromium-dev] crfaker fix

[Brian P. <bri...@tu...>]

There must be _some_ WGL function being called before glViewport.  At 
least wglMakeCurrent() must be called to bind a rendering context. 
Otherwise, the glViewport call is invalid.

We can call stubInit() from all the wgl/glx functions in the faker. 
It returns immediately if it's been called before.

-Brian


Ricky Uy wrote:
> You're right, I found the article you mentioned on MSDN. But if that is 
> the case, then are applications like Celestia doomed to be able to work 
> on Chromium in their original, unmodified state? In it's unmodified 
> state, stubInit() is never going to be called before the glViewport() 
> call, and I don't see any other areas of the crfaker dll where the call 
> to stubInit() would make sense. Celestia will just call glViewport and 
> it will immediately get intercepted by windows_exports.c and try to jmp 
> to an invalid location. I suppose checks could be made in the 
> windows_exports file to see if stubInit has already been called or not, 
> but it wouldn't be good to make function calls like that inside of NAKED 
> functions. Do you know any other places that might be okay for it?
> 
> */Greg Humphreys <hu...@cs...>/* wrote:
> 
>     If I recall correctly, this is (was?) explicitly documented in MSDN as
>     being illegal (manual loading of other DLL's within DLLMain). It USED
>     to be there, and then I discovered this, and moved it.
> 
>     --
>     Greg Humphreys, Assistant Professor
>     Department of Computer Science, University of Virginia
>     http://www.cs.virginia.edu/~humper/
> 
> 
>     On Jun 23, 2004, at 11:37 AM, Ricky Uy wrote:
> 
>      > Hi,
>      >
>      > For the Windows version of this library, there should be a call to
>      > stubInit() just before the return in DLLMain() in load.c, and all
>     the
>      > calls to stubInit() should be removed from the wgl functions in
>     wgl.c.
>      > There were several applications that would bail out because of this,
>      > including Celestia for Windows. However with this patch, they all
>      > work.
>      >
>      > The problem was that some applications d on't call wgl functions
>     before
>      > trying to do other things. For example, especially in direct
>     response
>      > to Alicia's post, Celestia would try to call ShowWindow() before
>      > calling ChoosePixelFormat(). This caused a crash because ShowWindow
>      > makes a call to glViewport, and because stubInit() had not yet been
>      > called, the glim dispatch table was nulled out. So there was a
>     crash.
>      > By having stubInit() in DLLMain, issues like these are resolved.
>      >
>      > Now there was a comment above DLLMain saying that Windows didn't
>     allow
>      > the loading of other libraries in DLLMain, and I'm not sure what has
>      > happened since, but it works fine. Hope this helps some people with
>      > their applications.
>      >
>      > Ricky
>      >
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> 
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