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List:       wine-devel
Subject:    Re: HeapCreate flags and shared heaps
From:       Alexandre Julliard <julliard () winehq ! com>
Date:       2000-07-31 23:14:03
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Peter Ganten <peter@ganten.org> writes:

> Now, the bad thing is, that the same access permissions are expected
> by any other office application, which is started after that. They
> just map the mapping into their own address space and don`t call
> VirtualAlloc, but access the region immediately. 
> 
> I have verified under win95, that this is possible. In fact, as soon
> as pages are commited by one process, they are available to the
> other processes, which have the same section mapped, too. 

I don't know how this behaves under NT. Do you have a small test app
to check this?

Anyway it should be possible to ignore SEC_RESERVE in this case and
commit everything at once. 

>  > If we really want to do this we could create a huge temp file, map it
>  > into all processes on startup (praying that the mapping address we
>  > choose is always free), and then put all shared allocations in there
>  > with some kind of synchronization mechanism. And then of course any
>  > application with a wild pointer will crash all the others, since there
>  > is no longer any memory protection in the whole shared area.
> 
> Yes, like on windows. But how could this approach solve the second
> problem?

If we do it this way then all shared mappings would be allocated from
the global shared area, and always be read/write for everybody, so we
wouldn't have this problem. But then of course, even Win95 will seem
quite stable compared to us.

-- 
Alexandre Julliard
julliard@winehq.com

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