ExplorerPatcher/ep_extra/main.asm

EXTERN worker : PROC

.CODE

ep_extra_EntryPoint PROC EXPORT
  PUSH RBP
  MOV RBP, RSP
  SUB RSP, 30H
  CALL worker
  CMP RAX, 0
  JE finish
  JMP RAX
finish:
  LEAVE
  RET
ep_extra_EntryPoint ENDP

END
ep_extra: Implemented an `ep_extra`-based loader ExplorerPatcher includes a mechanism which allows the user to load a single DLL, named `ep_extra.dll` and placed in `C:\Windows` when `explorer.exe` loads. This was long requested by some users who wanted to perform their own code/initializations/hooks when `explorer` started. In the mean time, I thought `ep_extra.dll` would work nicely as a loader for any number of modules. I could've included this functionality in the main ExplorerPatcher code, but I decided to take it up as a challenge instead and offer a robust implementation without changing ExplorerPatcher's main code. Thus, when using this as `ep_extra.dll`, it will also load DLLs that match the `ep_extra_*.dll` pattern. These DLLs must export a function called `setup` which the loader will execute on the thread that is loading the DLLs. Although not currently checked, return 0 from this function if your initialization succeeded, or some error code when it fails. What's up with the assembly and shell codes and weird threads that I create? Well, I realized I kind of did a mistake when coding ExplorerPatcher, in that I should have loaded and executed `ep_extra` on a seprate thread, not in `explorer`'s main thread. But since I said I'd do this challenge without changing EP, this was my solution towards having this `ep_extra` loader do its work, load the other DLLs, if any, and then unload itself from memory safely and (almost) cleanly without disturbing the main application right after it does its job. This way, you can update it seamlessly when `explorer` is running, which is much more convenient than having to kill `explorer`, replace the DLL, and then manually reload `explorer`. I don't know if this is the best way, but it is the way I thought about when realizing that I cannot call `FreeLibrary` simply, since the "next line" (which would have been a "return") is well outside of valid memory at that point. `FreeLibraryAndExitThread` also can't be used since I do not want to exit `explorer`'s main thread which the loader's function is called on. 2023-03-01 19:27:44 +01:00			`EXTERN worker : PROC`

			`.CODE`

			`ep_extra_EntryPoint PROC EXPORT`
			`PUSH RBP`
			`MOV RBP, RSP`
			`SUB RSP, 30H`
			`CALL worker`
			`CMP RAX, 0`
			`JE finish`
			`JMP RAX`
			`finish:`
			`LEAVE`
			`RET`
			`ep_extra_EntryPoint ENDP`

			`END`