"Mark Salsbery [MVP]" <MarkSalsbery[MVP]@newsgroup.nospam> wrote in
message news:elTFMr%237HHA.1204@TK2MSFTNGP03.phx.gbl...
Does rundll32.exe call DllMain() by default? If so, is the reason ==
DLL_PROCESS_ATTACH?
I don't think so.
Of course it does. Any access to code in a DLL (i.e. not resource
functions) triggers DllMain. But rundll32 usually has to be passed an
argument specifying the name of a function to run, if there isn't a
function name it may not even load the DLL....
Also there are a lot of restrictions on what DllMain can do.
And finally, if rundll32 doesn't find the function requested, it will
probably unload the library and exit immediately. The immediate exit is a
problem here, nothing to do about that except provide a valid function.
The unloading the library can be worked around as follows:
Call LoadLibrary in DllMain on itself. This can be done safely under
loader lock because the DLL is already loaded. Then use
FreeLibraryAndExitThread from your worker thread to safely stop the DLL.
Without these steps, the worker thread will have an instruction pointer in
memory that once belonged to the dll but is now freed. Guaranteed access
violation (aka segmentation fault aka GPF).
However, that immediate exit is still a problem.....