Zero Detours if Detours isn't needed (#5784)

If Detours isn't needed (no functions hooked) we'd still call DetourRestoreAfterWith(), DetourTransactionBegin() and DetourTransactionCommit(). Omit these unnecessary calls if Detours isn't needed.

Also removed some old dead (unused) code not used (excluded via #if)

Author: DrusTheAxe

dev/DynamicDependency/API/MddDetourPackageGraph.cpp

@@ -110,10 +110,22 @@ HRESULT WINAPI DynamicGetPackageGraphRevisionId();
 
 typedef UINT32 (WINAPI* GetPackageGraphRevisionIdFunction)();
 
+static bool MddUseOSImplementation()
+{
+    // Use the Win11 APIs if available (instead of Detour'ing to our own implementation)
+    return MddCore::Win11::IsSupported();
+}
+
+bool MddNeedsDetours() noexcept
+{
+    // Detour to our own implementation if Windows doesn't provide a sufficient implementation
+    return !MddUseOSImplementation();
+}
+
 HRESULT WINAPI MddDetourPackageGraphInitialize() noexcept
 {
     // Use the Win11 APIs if available (instead of Detour'ing to our own implementation)
-    if (MddCore::Win11::IsSupported())
+    if (MddUseOSImplementation())
     {
         RETURN_IF_FAILED(MddWin11Initialize());
         return S_OK;

dev/DynamicDependency/API/MddDetourPackageGraph.h

@@ -6,6 +6,8 @@
 
 #include "appmodel_msixdynamicdependency.h"
 
+bool MddNeedsDetours() noexcept;
+
 HRESULT WINAPI MddDetourPackageGraphInitialize() noexcept;
 
 void WINAPI MddDetourPackageGraphShutdown() noexcept;

dev/UndockedRegFreeWinRT/urfw.cpp

@@ -405,29 +405,25 @@ HRESULT ExtRoLoadCatalog()
     return S_OK;
 }
 
-HRESULT UrfwInitialize() noexcept
+static bool UrfwUseOSImplementation() noexcept
 {
-#if defined(TODO_URFW_DELEGATE_TO_OS_19H1PLUS)
-    // Windows' Reg-Free WinRT first appeared in Windows 10 Version 1903, May 2019 Update (aka 19H1)
-    // https://blogs.windows.com/windowsdeveloper/2019/04/30/enhancing-non-packaged-desktop-apps-using-windows-runtime-components/
-    // Delegate to the OS' implementation when available
-    if (WindowsVersion::IsWindows10_19H1OrGreater())
-    {
-        return S_OK;
-    }
-#elif defined(TODO_SEEME_PRODUCT_TARGET)
-    // Delegate to the OS' implementation on >= Windows 11 24H1
-    if (WindowsVersion::IsWindows11_22H2OrGreater())
-    {
-        return S_OK;
-    }
-#else
     // Delegate to the OS' implementation on >= Windows 11 24H1
-    if (WindowsVersion::IsWindows11_24H1OrGreater())
+    return WindowsVersion::IsWindows11_24H1OrGreater();
+}
+
+bool UrfwNeedsDetours() noexcept
+{
+    // Detour to our own implementation if Windows doesn't provide a sufficient implementation
+    return !UrfwUseOSImplementation();
+}
+
+HRESULT UrfwInitialize() noexcept
+{
+    // Delegate to the OS' implementation if we can
+    if (UrfwUseOSImplementation())
     {
         return S_OK;
     }
-#endif
 
     // OS Reg-Free WinRT isn't available so let's do it ourselves...
     DetourAttach(&(PVOID&)TrueRoActivateInstance, RoActivateInstanceDetour);

dev/UndockedRegFreeWinRT/urfw.h

@@ -4,6 +4,8 @@
 #if !defined(URFW_H)
 #define URFW_H
 
+bool UrfwNeedsDetours() noexcept;
+
 HRESULT UrfwInitialize() noexcept;
 
 void UrfwShutdown() noexcept;

dev/WindowsAppRuntime_DLL/dllmain.cpp

@@ -22,6 +22,12 @@ static HRESULT DetoursInitialize()
     }
 
     // Do we need to detour APIs?
+    if (!MddNeedsDetours() && !UrfwNeedsDetours())
+    {
+        return S_OK;
+    }
+
+    // No detours needed in a 'detours helper process'
     if (DetourIsHelperProcess())
     {
         return S_OK;