(Snippit) How To Make a Dll Unload Its Self

[bubzuru]

i was looking for code to make a dll unload itself, and foud some broken code
problem was the coder was pushing a handle to the exe not the dll

here is the fixed code 

Code: (c) [Select]

void UnloadSelf(HMODULE hdl)
{
   LPVOID FP_ExitThread = (LPVOID)GetProcAddress(GetModuleHandle("kernel32.dll"), "ExitThread");
   __asm
   {
      push hdl
      push FP_ExitThread
      jmp dword ptr [FreeLibrary]
   }
}

to get the handle to the loaded dll you can just grab it from main

example:

Code: (c) [Select]

BOOL WINAPI DllMain(HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpvReserved)
{
    switch (fdwReason)
    {
        case DLL_PROCESS_ATTACH:
            MessageBox(0,"hello","world",0);
            UnloadSelf(hinstDLL);
            break;
        case DLL_PROCESS_DETACH:
        case DLL_THREAD_ATTACH:
        case DLL_THREAD_DETACH:
            break;
    }
    return TRUE;
}

beats injecting code to call FreeLibrary

[Satan911]

Why can't the WinAPI be more simple..

[Xires]

Because it's WinAPI?  Have a look at intermixing MFC with custom WinAPI class wrappers for use w/ DirectX.  It's atrocious.  Oh, how simple & elegant is the world of FOSS.

[TETYYS]

Sorry for reviving thread, but this method causes application to crash, or unlass FileZilla to crash. I used this and it worked.

Code: (C++) [Select]

EXTERN_C IMAGE_DOS_HEADER __ImageBase;
CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)FreeLibrary, &__ImageBase, 0, NULL);


[Xires]

No need to feel sorry when adding important/useful information.