Encapsulate GetProcAddress in a way that avoids undefined and conditionally

defined behaviour.

3 files changed, 38 insertions, 31 deletions

diff --git a/win32/PlatWin.cxx b/win32/PlatWin.cxx
index 2206c026e..f09cdfcf1 100644
--- a/win32/PlatWin.cxx
+++ b/win32/PlatWin.cxx
@@ -81,7 +81,7 @@ bool LoadD2D() {
 	static bool triedLoadingD2D = false;
 	if (!triedLoadingD2D) {
 		DWORD loadLibraryFlags = 0;
-		HMODULE kernel32 = ::GetModuleHandle(TEXT("kernel32.dll"));
+		HMODULE kernel32 = ::GetModuleHandleW(L"kernel32.dll");
 		if (kernel32) {
 			if (::GetProcAddress(kernel32, "SetDefaultDllDirectories")) {
 				// Availability of SetDefaultDllDirectories implies Windows 8+ or
@@ -97,34 +97,30 @@ bool LoadD2D() {
 			IUnknown **factory);
 
 		hDLLD2D = ::LoadLibraryEx(TEXT("D2D1.DLL"), 0, loadLibraryFlags);
-		if (hDLLD2D) {
-			D2D1CFSig fnD2DCF = reinterpret_cast<D2D1CFSig>(::GetProcAddress(hDLLD2D, "D2D1CreateFactory"));
-			if (fnD2DCF) {
-				// A single threaded factory as Scintilla always draw on the GUI thread
-				fnD2DCF(D2D1_FACTORY_TYPE_SINGLE_THREADED,
-					__uuidof(ID2D1Factory),
-					nullptr,
-					reinterpret_cast<IUnknown**>(&pD2DFactory));
-			}
+		D2D1CFSig fnD2DCF = DLLFunction<D2D1CFSig>(hDLLD2D, "D2D1CreateFactory");
+		if (fnD2DCF) {
+			// A single threaded factory as Scintilla always draw on the GUI thread
+			fnD2DCF(D2D1_FACTORY_TYPE_SINGLE_THREADED,
+				__uuidof(ID2D1Factory),
+				nullptr,
+				reinterpret_cast<IUnknown**>(&pD2DFactory));
 		}
 		hDLLDWrite = ::LoadLibraryEx(TEXT("DWRITE.DLL"), 0, loadLibraryFlags);
-		if (hDLLDWrite) {
-			DWriteCFSig fnDWCF = reinterpret_cast<DWriteCFSig>(::GetProcAddress(hDLLDWrite, "DWriteCreateFactory"));
-			if (fnDWCF) {
-				const GUID IID_IDWriteFactory2 = // 0439fc60-ca44-4994-8dee-3a9af7b732ec
-				{ 0x0439fc60, 0xca44, 0x4994, { 0x8d, 0xee, 0x3a, 0x9a, 0xf7, 0xb7, 0x32, 0xec } };
-
-				const HRESULT hr = fnDWCF(DWRITE_FACTORY_TYPE_SHARED,
-					IID_IDWriteFactory2,
+		DWriteCFSig fnDWCF = DLLFunction<DWriteCFSig>(hDLLDWrite, "DWriteCreateFactory");
+		if (fnDWCF) {
+			const GUID IID_IDWriteFactory2 = // 0439fc60-ca44-4994-8dee-3a9af7b732ec
+			{ 0x0439fc60, 0xca44, 0x4994, { 0x8d, 0xee, 0x3a, 0x9a, 0xf7, 0xb7, 0x32, 0xec } };
+
+			const HRESULT hr = fnDWCF(DWRITE_FACTORY_TYPE_SHARED,
+				IID_IDWriteFactory2,
+				reinterpret_cast<IUnknown**>(&pIDWriteFactory));
+			if (SUCCEEDED(hr)) {
+				// D2D1_DRAW_TEXT_OPTIONS_ENABLE_COLOR_FONT
+				d2dDrawTextOptions = static_cast<D2D1_DRAW_TEXT_OPTIONS>(0x00000004);
+			} else {
+				fnDWCF(DWRITE_FACTORY_TYPE_SHARED,
+					__uuidof(IDWriteFactory),
 					reinterpret_cast<IUnknown**>(&pIDWriteFactory));
-				if (SUCCEEDED(hr)) {
-					// D2D1_DRAW_TEXT_OPTIONS_ENABLE_COLOR_FONT
-					d2dDrawTextOptions = static_cast<D2D1_DRAW_TEXT_OPTIONS>(0x00000004);
-				} else {
-					fnDWCF(DWRITE_FACTORY_TYPE_SHARED,
-						__uuidof(IDWriteFactory),
-						reinterpret_cast<IUnknown**>(&pIDWriteFactory));
-				}
 			}
 		}
 
diff --git a/win32/PlatWin.h b/win32/PlatWin.h
index d7e544da6..9d17dff69 100644
--- a/win32/PlatWin.h
+++ b/win32/PlatWin.h
@@ -38,6 +38,20 @@ inline HWND HwndFromWindow(const Window &w) noexcept {
 void *PointerFromWindow(HWND hWnd) noexcept;
 void SetWindowPointer(HWND hWnd, void *ptr) noexcept;
 
+/// Find a function in a DLL and convert to a function pointer.
+/// This avoids undefined and conditionally defined behaviour.
+template<typename T>
+T DLLFunction(HMODULE hModule, LPCSTR lpProcName) noexcept {
+	if (!hModule) {
+		return nullptr;
+	}
+	FARPROC function = ::GetProcAddress(hModule, lpProcName);
+	static_assert(sizeof(T) == sizeof(function));
+	T fp;
+	memcpy(&fp, &function, sizeof(T));
+	return fp;
+}
+
 #if defined(USE_D2D)
 extern bool LoadD2D();
 extern ID2D1Factory *pD2DFactory;
diff --git a/win32/ScintillaWin.cxx b/win32/ScintillaWin.cxx
index 9f6066cb9..01ffcbe76 100644
--- a/win32/ScintillaWin.cxx
+++ b/win32/ScintillaWin.cxx
@@ -527,11 +527,8 @@ void ScintillaWin::Init() {
 	hrOle = ::OleInitialize(nullptr);
 
 	// Find SetCoalescableTimer which is only available from Windows 8+
-	HMODULE user32 = ::GetModuleHandle(TEXT("user32.dll"));
-	if (user32) {
-		SetCoalescableTimerFn = reinterpret_cast<SetCoalescableTimerSig>(
-			::GetProcAddress(user32, "SetCoalescableTimer"));
-	}
+	HMODULE user32 = ::GetModuleHandleW(L"user32.dll");
+	SetCoalescableTimerFn = DLLFunction<SetCoalescableTimerSig>(user32, "SetCoalescableTimer");
 
 	vs.indicators[SC_INDICATOR_UNKNOWN] = Indicator(INDIC_HIDDEN, ColourDesired(0, 0, 0xff));
 	vs.indicators[SC_INDICATOR_INPUT] = Indicator(INDIC_DOTS, ColourDesired(0, 0, 0xff));