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

[Roger H. <rog...@mi...>]

On 16 Apr 2009, at 22:23, Sean McBride wrote:

> 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.

I have forgotten how to use CVS (and never was very confident with it)  
and don't really want to re-learn it, sorry. I am interested in doing  
a 64 bit version of our application and and happy to advise. I guess  
its a lot of work to convert the project to SVN. I could modify my  
local files (some of which have now diverged quite a bit because I  
have none of James' recent changes, but I think this area should be  
safe) and give the changes but thats almost what I've done already. I  
can't really test on 64 bit until we do the rest of the application,  
and we are about a week away from release of a new version, so a bad  
time.

Roger.