Fwd: Loader, mapping and sharing issues with main exe

[Jason Edmeades]

Does anyone have any comments on this please?

---------- Forwarded message ----------
From: Jason Edmeades <jason.edmeades at googlemail.com>
Date: Wed, Jan 27, 2010 at 1:09 AM
Subject: Loader, mapping and sharing issues with main exe
To: wine-devel at winehq.org


Hello,

I've been debugging a problem with an application which checks itself
for consistency before it runs. It does this extremely simply and
fails in a trivial way under wine, but for the life of me I do not
know how to fix it, and I would appreciate any thoughts - its not
everyday I delve into the loader and server logic!

I have cut this down to a 2 line test program, which basically fails
because a native executable called eg. test.exe subsequently calls
CreateFile(".\\test.exe", GENERIC_READ, 0 /* no share*/ - ie it's
opening itself for read access and non-shared access. It suffers a
sharing violation on wine whereas it works fine on windows

Diagnosing the wine side, we are in trouble here - the act of loading
a module ends up in load_dll which call find_dll_file which in turn
calls NtOpenFile for GENERIC_READ access. This returns a file handle
which is then used to create the in memory file mapping for the
executable code, and the handle returned from the NtOpenFile is then
closed.

However, when we come along to the application code and try the open
we end up checking the sharing and there are 3 things on the
inode->open chain:
The original open, with access of read
The mapping, with access of mapping
The open in progress (which is ignored for sharing checks) which does
not want to SHARE_READ,and hence the sharing violation occurs. For
reference we are failing in the 3rd (last) case of check_sharing
returning STATUS_SHARING_VIOLATION, ie existing access if for read
purposes, but the requested sharing doesnt allow this.

What I dont understand is why the NtClose for the handle does not
remove it from the 'open' list - I think from my reading of the
fd_destroy code it will put it onto the closed list if there are other
references to the same inode, although thats where my debugging will
head next.

This whole area has me confused now! Can anyone shed some light on how
its all supposed to work please?

Thanks,
Jason