Merge pull request #6 from TotemArts/dinput8_fix

Work around dinput8.dll not existing in System32 by using COM

Cargo.toml

@@ -26,6 +26,7 @@ features = [
 	"interface",
 	"implement",
     "Data_Xml_Dom",
+    "Win32_Devices_HumanInterfaceDevice",
     "Win32_Foundation",
     "Win32_Security",
     "Win32_System_Com",

src/dinput8.rs

@@ -1,22 +1,52 @@
 //! This module handles functionality related to the original dinput8.dll
-use lazy_static::lazy_static;
-use libloading::Library;
-
-lazy_static! {
-    static ref DINPUT8_DLL: Library = unsafe { Library::new("C:\\Windows\\System32\\dinput8.dll") }.unwrap();
-    static ref DINPUT8CREATE_PTR: libloading::Symbol<'static, unsafe extern "C" fn(usize, u32, usize, usize, usize) -> u32> =
-        unsafe { DINPUT8_DLL.get(b"DirectInput8Create\0") }.unwrap();
-}
+use windows::{
+    core::{IUnknown, Interface, GUID, HRESULT},
+    Win32::{
+        Devices::HumanInterfaceDevice::{CLSID_DirectInput8, IDirectInput8A, IDirectInput8W},
+        Foundation::{E_NOINTERFACE, HINSTANCE, S_OK},
+        System::Com::{CoCreateInstance, CLSCTX_INPROC_SERVER},
+    },
+};
 
 /// This function simply redirects the one and only DirectInput8Create call to the real dinput8 DLL.
 #[no_mangle]
 #[export_name = "DirectInput8Create"]
 pub unsafe extern "C" fn directinput8_create(
-    hinst: usize,
+    hinst: HINSTANCE,
     dwversion: u32,
-    riid: usize,
-    out: usize,
-    outer: usize,
-) -> u32 {
-    (DINPUT8CREATE_PTR)(hinst, dwversion, riid, out, outer)
+    riid: *const GUID,
+    out: *mut 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> {
+        match unsafe { riid.as_ref() } {
+            Some(&IDirectInput8A::IID) => {
+                let dinput: IDirectInput8A =
+                    CoCreateInstance(&CLSID_DirectInput8, None, CLSCTX_INPROC_SERVER)?;
+
+                dinput.Initialize(hinst, dwversion)?;
+                Ok(dinput.cast()?)
+            }
+            Some(&IDirectInput8W::IID) => {
+                let dinput: IDirectInput8W =
+                    CoCreateInstance(&CLSID_DirectInput8, None, CLSCTX_INPROC_SERVER)?;
+
+                dinput.Initialize(hinst, dwversion)?;
+                Ok(dinput.cast()?)
+            }
+            _ => return Err(E_NOINTERFACE.into()),
+        }
+    };
+
+    *out = match f() {
+        Ok(v) => Some(v),
+        Err(e) => return e.code(),
+    };
+
+    S_OK
 }

src/lib.rs

@@ -16,6 +16,7 @@ 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::{
@@ -94,6 +95,9 @@ 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")?;
 
@@ -140,6 +144,7 @@ pub extern "stdcall" fn DllMain(
         DLL_PROCESS_ATTACH => {
             if let Err(e) = dll_attach() {
                 // Print a debug message for anyone who's listening.
+                output_debug_string(&format!("{:?}\n", e));
                 eprintln!("{:?}", e);
             }
         }

src/xaudio27.rs

@@ -26,7 +26,7 @@ fn debug_log(msg: std::fmt::Arguments) {
     // Only bother logging when debug assertions are on.
     #[cfg(debug_assertions)]
     {
-        use windows::core::PCSWSTR;
+        use windows::core::PCWSTR;
         use windows::Win32::System::Diagnostics::Debug::OutputDebugStringW;
 
         // OutputDebugString does not append newlines.