The Old New Thing

Partially eliminating the need for SetThreadpoolCallbackLibrary and reducing the cost of FreeLibraryAndExitThread

November 7, 2013 Nov 7, 2013 11/7/13

Raymond Chen

Update: Daniel points out that there is still a race condition here, so this trick won't work. Rats. The documentation for the Set­Threadpool­Callback­Library says This prevents a deadlock from occurring when one thread in DllMain is waiting for the callback to end, and another thread that is executing the callback attempts ...

CoUninitalize will ask a DLL if it is okay to unload now, but the answer is a foregone conclusion

November 6, 2013 Nov 6, 2013 11/6/13

Raymond Chen

The Dll­Can­Unload­Now entry point is exported by COM in-proc servers. COM host applications call Co­Free­Unused­Libraries periodically to ask COM to do DLL housecleaning, and in response, COM asks each DLL if it is okay to be unloaded. If so, then COM unloads the DLL. What is not well-known is that COM also does DLL...

What is the point of FreeLibraryAndExitThread?

November 5, 2013 Nov 5, 2013 11/5/13

Raymond Chen

The Free­Library­And­Exit­Thread function seems pointless. I mean, all the function does is Who needs such a trivial function? If I wanted to do that, I could just write it myself. And then you discover that occasionally your program crashes. What's going on? Let's rewind and look at the original problem. Originally...

Manipulating the zone identifier to specify where a file was download from

November 4, 2013 Nov 4, 2013 11/4/13

Raymond Chen

When you download a file via Internet Explorer, the file is tagged with a little bit of information known as a zone identifier which remembers where the file was downloaded from. This is what tells Explorer to put up the "Yo, did you really want to run this program?" prompt and which is taken into account by applications so that they can do ...