Get HModule from inside a DLL

问题:

I need to load some resource from my DLL (i need to load them from the DLL code), for doing that I'm using FindResource.

To do that i need the HModule of the DLL. How to find that?

(I do not know the name (filename) of the DLL (the user can change it))

回答1:

The first argument to DllMain() is the HMODULE of the DLL.

回答2:

You get it from the DllMain() entrypoint, 1st argument. Write one, store it in a global variable:

HMODULE DllHandle;

BOOL APIENTRY DllMain(HMODULE hModule, DWORD dwReason, LPVOID lpReserved) {
  if (dwReason == DLL_PROCESS_ATTACH) DllHandle = hModule;
  return TRUE;
}

There's an undocumented hack that works on any version of 32-bit and 64-bit Windows that I've seen. The HMODULE of a DLL is the same value as the module's base address:

static HMODULE GetThisDllHandle()
{
  MEMORY_BASIC_INFORMATION info;
  size_t len = VirtualQueryEx(GetCurrentProcess(), (void*)GetThisDllHandle, &info, sizeof(info));
  assert(len == sizeof(info));
  return len ? (HMODULE)info.AllocationBase : NULL;
}

回答3:

Depending upon how your software is architected, you may not have access to DllMain or the code that wants the resource may not even know it's inside a DLL or exe!

The DLLMain function is given the DLL's module handle. Store it in a globally accessible variable.

Or, lookup the module based upon a function known to the local code:

// Determine the module handle by locating a function
// you know resides in that DLL or exe
HMODULE hModule;
GetModuleHandleExA(GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS |
                   GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT,
                   (LPCSTR)&myDLLfuncName, &hModule);

HRSRC hRscr = FindResource(hModule, ............);