A GetModuleHandle implementation

Question

I need to do it this way because I am in DllMain() therefore, loader lock is held. I've read that GetModuleHandle() also uses the loader lock [page #6] which would result in deadlock.

How could GetModuleHandle() implemented? Some code would be a plus.

Update: Since I am using SetWindowsHookEx on WinXP only. Just going to take advice in the comments, go the easy way, and use GetModuleHandle() the first time the callback gets called.

Can't you just export an `Init` function that will do all the "dangerous" stuff, and call it from the outside after `DllMain` was completed? You're looking for trouble if you're doing complicated things in `DllMain`. — Eran, Sep 14 '11 at 13:52
@eran, no not with my mode of API injection. It is legacy 'API hooking' code, to support WinXP. — unixman83, Sep 14 '11 at 14:08
Try it the easy way before trying it the hard way. Just add a few lines of code to the target program to have it load your DLL if a special debugging switch is passed, say. — Raymond Chen, Sep 14 '11 at 14:18
Windows XP SP2 adds ASLR, otherwise I could read 0x7ffdf000 which used to be the PEB, and walk that to get the loaded module's base address. — unixman83, Sep 14 '11 at 14:33

score 0 · Accepted Answer · answered Sep 14 '11 at 13:51

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You can call GetModuleHandle from DllMain. It doesn't load any libraries and doesn't increment module reference count. Other story is with LoadLibrary. Never call it from DllMain.

answered Sep 14 '11 at 13:51

Sergey Podobry

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A Microsoft document implies that `GetModuleHandle()` **can** hold a loader lock. (Page 6) http://msdn.microsoft.com/en-us/windows/hardware/gg487379.aspx – unixman83 Sep 14 '11 at 14:06
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It is ok as long as you stay in the dllmain thread. Loader lock is reenterable. – Sergey Podobry Sep 14 '11 at 14:43
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It does increment the reference count, the reason the lock must acquired. Review GetModuleHandleEx() and the GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT option. – Hans Passant Sep 14 '11 at 14:53
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GetModuleHandleEx does but GetModuleHandle doesn't. – Sergey Podobry Sep 14 '11 at 16:17

A GetModuleHandle implementation

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