Ensure module is only loaded once

Resources/BuildNo.rc

@@ -1 +1 @@
-#define BUILD_NUMBER 2147 
+#define BUILD_NUMBER 2148 

dllmain.cpp

@@ -17,6 +17,7 @@
 #define DLLMAIN_CPP
 #define WIN32_LEAN_AND_MEAN
 #include <Windows.h>
+#include <sstream>
 #include <shlwapi.h>
 #include "winmm.h"
 #include "Patches\Patches.h"
@@ -39,6 +40,7 @@ std::ofstream LOG;
 HMODULE m_hModule = nullptr;
 SH2VERSION GameVersion = SH2V_UNKNOWN;
 HMODULE wrapper_dll = nullptr;
+HANDLE g_hMutex = nullptr;
 EXECUTION_STATE esFlags = 0;
 bool CustomExeStrSet = false;
 bool EnableCustomShaders = false;
@@ -53,6 +55,13 @@ extern "C" BOOL WINAPI DSOAL_DllMain(HINSTANCE hInstDLL, DWORD fdwReason, LPVOID
 
 void VerifySH2EE(){}
 
+std::wstring CreateUniqueMutexName()
+{
+	std::wstringstream ss;
+	ss << L"SH2EECoreModule_" << GetCurrentProcessId();
+	return ss.str();
+}
+
 void GetConfig()
 {
 	// Get config file path
@@ -120,6 +129,14 @@ void GetGameVersion()
 
 void DelayedStart()
 {
+	// Only allow function to run once
+	static bool AlreadyRun = false;
+	if (AlreadyRun)
+	{
+		return;
+	}
+	AlreadyRun = true;
+
 	// Init Logs
 	Logging::LogComputerManufacturer();
 	Logging::LogOSVersion();
@@ -794,6 +811,21 @@ BOOL APIENTRY DllMain(HMODULE hModule, DWORD fdwReason, LPVOID lpReserved)
 	{
 	case DLL_PROCESS_ATTACH:
 	{
+		// Create a unique mutex name using the process ID
+		std::wstring mutexName = CreateUniqueMutexName();
+		g_hMutex = CreateMutex(nullptr, TRUE, mutexName.c_str());
+
+		// Check if the mutex already exists
+		if (GetLastError() == ERROR_ALREADY_EXISTS)
+		{
+			// Clear the error code
+			SetLastError(ERROR_SUCCESS);
+
+			// Mutex already exists, another instance of the DLL is loaded in this process
+			g_hMutex = nullptr;
+			return FALSE; // Return FALSE to prevent the DLL from loading
+		}
+
 		// Store Module handle
 		m_hModule = hModule;
 
@@ -843,6 +875,14 @@ BOOL APIENTRY DllMain(HMODULE hModule, DWORD fdwReason, LPVOID lpReserved)
 		break;
 	case DLL_PROCESS_DETACH:
 	{
+		// Release the mutex when the DLL is unloaded
+		if (g_hMutex)
+		{
+			ReleaseMutex(g_hMutex);
+			CloseHandle(g_hMutex);
+			g_hMutex = nullptr;
+		}
+
 		// Stop thread
 		m_StopThreadFlag = true;