[Bug 29384] Voobly fails to launch Age of Empires II multiplayer game

[wine-bugs at winehq.org]

https://bugs.winehq.org/show_bug.cgi?id=29384

--- Comment #39 from Michael Müller <michael at fds-team.de> ---
Hi,

thanks for pointing out this issue. I was able to track down the problem and
fix it.

The problem was caused by the way how the unloading of builtin dlls is handled.
In order to emulate the WRITECOPY protection correctly, we need remove the
WRITE permission from the page and change the protection flags when we get an
exception for an invalid write operation on such a page. In order to accomplish
this, we have to get the current protection flags from Wines virtual memory
management. This is usually no problem, since the required information is set
when a page is allocated and will only be removed if a page is freed.

However, there is one exception: builtin dlls. Wine does not allocate the
memory using its own memory functions, but uses dlopen / dlcose to take care of
this. In order to provide the usual memory functions for these memory areas,
Wine still keeps track of stuff like memory protection flags, but the
deallocation of the memory is detached from the usual memory functions. For
some reason Wine deleted the required memory management information _before_
unloading the builtin dll using dlclose. The destructor of the dll now tried to
write to a WRITECOPY page (which was/is part of the dll), but the exception
handler was unable to determine the protection flags of the page and thinks it
is just a usual page fault and crashes.

In order to solve this problem, I simply swapped the order of deleting the
memory management information and unloading the dll using dlclose. Now Steam
runs without problems. Moreover I fixed a possible multithreading issue. The
updated patch is available at:

https://github.com/compholio/wine-compholio/tree/master/patches/ntdll-WRITECOPY

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