[Bug 2608] Might and Magic VI wont run until "DeShrinker" program is run on mss32.dll

[wine-bugs at winehq.org]

http://bugs.winehq.org/show_bug.cgi?id=2608





--- Comment #10 from Anastasius Focht <focht at gmx.net>  2007-10-26 04:10:43 ---
Created an attachment (id=8777)
 --> (http://bugs.winehq.org/attachment.cgi?id=8777)
patch which fixes shrinker 3.x issues, making it fully wine compatible

Hello,

this bug seemed interesting to me - so I looked into it ;-)

Attached is a patch which fixes remaining shinker 3.x issue.
For reference I tested another target compressed with shrinker 3.4 which
suffers from same problem: "Astrosoft Vision 4"
(http://astrosoft.ch/vision.htm).

Shrinker depends on specific API entry (opcode) layout of following functions:

LdrAccessResource
EXC_CallHandler/ExceptionHandler2 (windows)
ExitProcess

The patch mimics windows API entry opcodes for ExitProcess by using __asm__
wrapper to let shrinker successfully hook.
The opcode sequences must be located between first 0x20 bytes of API entry.
Shrinker usually overwrites push <imm32> (5 byte) instructions, large enough to
fit jmp/call dword ptr opcode.
If any 3rd party software hooks one of these entries on standard way (detour on
first bytes), Shrinker will obviously fail.
Same goes to wine +relay feature - do not use it while running shrinker
protected programs.

The patch was tested with Might & Magic 6 (with shrinked mss32.dll) under
NT/2K/XP configurations.
It successfully starts up, no more manual deshrinking needed.
Should apply to all other Shrinker 3.x protected apps/games.
The latest known Shrinker version is 3.4 - development probably abandoned some
time ago.

Additional notes for this game:

1.)

You might run into "More diskspace needed" error when starting up the game.
This is due to GetDiskFreeSpaceA/W() cluster overflow.
Wine fixes overflow (cap 2 GB) only for Win9X/Me systems, which is IMHO wrong.
This API is broken on all windows versions (should not make any difference -
cap by default).
You can fix this by removing GetVersion() check in
"dlls/kernel32/volume.c:GetDiskFreeSpaceW()".
The game will then successfully start on larger disk partitions.

2.)

If it asks for "CD2", just make directory containing ANIMS/AUTORUN/AUTORUN.INF
data and add directory to winecfg, setting type as CDROM.

Regards

PS: I hope the developers of Shrinker burn in hell for writing such intrusive
code.
That api entry trickery has no benefit at all but makes life of customers/users
harder (hooking problems with other 3rd party software).
Protection level? Zero. All this stuff can be easily recognized/bypassed by
advanced reversers. ;-)


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