Merge pull request #9 from TotemArts/comfix2

Avoid initializing COM on behalf of the application

src/dinput8.rs

@@ -16,27 +16,38 @@ pub unsafe extern "C" fn directinput8_create(
     dwversion: u32,
     riid: *const GUID,
     out: *mut Option<IUnknown>,
-    _outer: Option<IUnknown>,
+    outer: Option<IUnknown>,
 ) -> HRESULT {
     // Instead of trying to load the original dinput8.dll and calling the original `DirectInput8Create`,
     // we can simply load the dinput8 interface via COM and return it up to our caller. This is basically
     // what DirectInput8Create does noawadays anyway.
     //
     // Reference: https://learn.microsoft.com/en-us/previous-versions/windows/desktop/ee416756(v=vs.85)
     let f = || -> Result<IUnknown, windows::core::Error> {
+        // Initialize COM with the default apartment type.
+        // NOTE: Disabled for now. The documentation does not really specify what the original `DirectInput8Create`
+        // does in this case, and I'm too lazy to disassemble dinput8.dll to figure it out.
+        // unsafe { CoInitializeEx(None, COINIT_MULTITHREADED)? };
+
         match unsafe { riid.as_ref() } {
             Some(&IDirectInput8A::IID) => {
                 let dinput: IDirectInput8A =
-                    CoCreateInstance(&CLSID_DirectInput8, None, CLSCTX_INPROC_SERVER)?;
+                    CoCreateInstance(&CLSID_DirectInput8, outer.as_ref(), CLSCTX_INPROC_SERVER)?;
 
-                dinput.Initialize(hinst, dwversion)?;
+                // Per the documentation, if pUnkOuter != NULL then the resulting object must be initialized manually.
+                if outer.is_none() {
+                    dinput.Initialize(hinst, dwversion)?;
+                }
                 Ok(dinput.cast()?)
             }
             Some(&IDirectInput8W::IID) => {
                 let dinput: IDirectInput8W =
-                    CoCreateInstance(&CLSID_DirectInput8, None, CLSCTX_INPROC_SERVER)?;
+                    CoCreateInstance(&CLSID_DirectInput8, outer.as_ref(), CLSCTX_INPROC_SERVER)?;
 
-                dinput.Initialize(hinst, dwversion)?;
+                // Per the documentation, if pUnkOuter != NULL then the resulting object must be initialized manually.
+                if outer.is_none() {
+                    dinput.Initialize(hinst, dwversion)?;
+                }
                 Ok(dinput.cast()?)
             }
             _ => return Err(E_NOINTERFACE.into()),

src/lib.rs

@@ -23,7 +23,6 @@ use anyhow::Context;
 use sha2::{Digest, Sha256};
 
 use windows::core::PCWSTR;
-use windows::Win32::System::Com::{CoInitializeEx, COINIT_MULTITHREADED};
 use windows::Win32::{
     Foundation::{HANDLE, HINSTANCE},
     System::{
@@ -102,9 +101,6 @@ fn get_module_slice(info: &MODULEINFO) -> *const [u8] {
 /// Called upon DLL attach. This function verifies the UDK and initializes
 /// hooks if the UDK matches our known hash.
 fn dll_attach() -> anyhow::Result<()> {
-    // Ensure that COM is initialized.
-    unsafe { CoInitializeEx(None, COINIT_MULTITHREADED) }.context("failed to initialize COM")?;
-
     let process = unsafe { GetCurrentProcess() };
     let module = unsafe { GetModuleHandleA(None) }.context("failed to get module handle")?;