Re: Buffer overrun in 64 bit build: problem found, solution lacking

[Sean M. <se...@ro...>]

On 4/15/09 10:29 PM, Roger Holmes said:

>We should probably add an extra field to E3ClassInfo. I suggest it be  
>called deltaInstanceSize.
>
>We should have a new parameter in E3ClassTree::RegisterClass. When  
>called from E3ClassTree::RegisterExternalClass, this will be passed  
>straight through. When called for a built in class which merely adds a  
>single object to its base class, it would pass in the sizeof () this  
>object. When called for a class which adds more than one object to its  
>base class it would have to be the sum of the sizeof ()s of those  
>objects, however I don't think this will matter as such a class would  
>probably not call GetInstanceSize.
>
>GetInstanceSize would need to be changed to return deltaInstanceSize  
>instead of the difference of the instanceSize class and its parent.
>
>OpaqueTQ3Object::FindLeafInstanceData would need to be changed to add  
>( instanceSize - deltaInstanceSize ) to 'this' rather than the parent  
>class's instanceSize, which would then allow for the pad bytes moving  
>the data fields forward in the record.
>
>The same change would need to be made to  
>OpaqueTQ3Object::DeleteInstanceData and  
>OpaqueTQ3Object::DuplicateInstanceData.

This sounds reasonable.  I don't know Quesa well enough to attempt
this... Roger or James, do one of you have the time/inclination?  I can
certainly do a code review and testing.

Cheers,

-- 
____________________________________________________________
Sean McBride, B. Eng                 se...@ro...
Rogue Research                        www.rogue-research.com 
Mac Software Developer              Montréal, Québec, Canada