[OT] Re: Windows DLLs and TLS

[Rainer Schuetze]

On 10/9/2012 6:59 PM, Denis Shelomovskij wrote:
> 09.10.2012 0:51, Rainer Schuetze пишет:
>>
>>
>> On 10/8/2012 8:13 PM, Denis Shelomovskij wrote:
>>> 08.10.2012 21:47, Rainer Schuetze пишет:
>>>> Is your code doing callbacks into the host application in static
>>>> initializers? With the XP workaround, the runtime initialization
>>>> "impersonates" all threads that exist before loading the DLL, by
>>>> switching the TLS-pointer array of the current thread, and that
>>>> might be
>>>> unexpected in a callback (but not doing this might produce even more
>>>> unexpected results).
>>>
>>> Here you are! Just want to mention that I'm currently managed to publish
>>> my (continuation of your) TLS fix I did half a year before. It will
>>> finally solve this XP/Sever 2003 problem. It is available here but isn't
>>> finished now (fill be in few days):
>>> https://github.com/denis-sh/hooking/tree/master/tlsfixer
>>
>> Will this fix both issues (not being able to unload and that imperfect
>> simulation of DLL_THREAD_ATTACH for existing threads)? That would be
>> very cool.
>>
>
> Unloading is fixed. I can't remember any problems with DLL_THREAD_ATTACH
> (but it was half year ago so I can miss something I did that time), can
> you concretize the problem?

What I meant is the "impersonation" of existing threads from the thread 
that executes DLL_PROCESS_ATTACH to run the thread-local static 
constructors. Even though the TLS pointers are switched, they are still 
executed in the context of the current thread. Looking it up again, this 
is not an XP problem, those threads don't get a DLL_THREAD_ATTACH 
callback on newer systems aswell.

So I guess we will have to live with possible issues, but you are 
supposed to not really do a lot in DllMain anyway.