Patch 2024 executables to bypass resource verification

Adds code for the new April 2024 Update executable patches, which
bypass the resource verification done with ".verify" files. This makes
it possible to load mods without using devmode or needing DOOMLauncher.

The patching functions check the executable status, and if it is
detected to be an unpatched 2024 executable, it creates a backup and
applies the corresponding patch.

DOOMModLoader/PatchGameExecutables.cs

@@ -22,14 +22,99 @@ enum GameExeStatus // Whether the game executables have been patched, and whethe
 	// Gets the current version and patch status of the game executables
 	static GameExeStatus CheckGameExecutables()
 	{
-		return GameExeStatus.Unknown;
+		if (!File.Exists("./DOOMx64.exe") || !File.Exists("./DOOMx64vk.exe"))
+			return GameExeStatus.VFR;
+
+		GameExeStatus statusGl     = GameExeStatus.Unknown;
+		GameExeStatus statusVulkan = GameExeStatus.Unknown;
+
+		try
+		{
+			// Check the OpenGL executable
+			using (FileStream stream = File.OpenRead("./DOOMx64.exe"))
+			{
+				if (stream.Length < 0x169C0E0 + 7)
+					return GameExeStatus.Unknown; // Too short for the byte sequence check
+
+				if (Utility.StreamCheckBytes(stream, 0x169C0E0, [0xB8, 0x01, 0x00, 0x00, 0x00, 0xC3, 0x90]))
+					statusGl = GameExeStatus.Patched_New; // 2024 version, already patched
+				else if (Utility.StreamCheckBytes(stream, 0x169C0E0, [0x40, 0x55, 0x53, 0x56, 0x57, 0x41, 0x56]))
+					statusGl = GameExeStatus.Vanilla_New; // 2024 version, not yet patched
+				else if (stream.Length == 76_022_480)
+					statusGl = GameExeStatus.Vanilla_Old; // 2018 version, unpatchable
+			}
+			// Check the Vulkan executable
+			using (FileStream stream = File.OpenRead("./DOOMx64vk.exe"))
+			{
+				if (stream.Length < 0x169B260 + 7)
+					return GameExeStatus.Unknown;
+
+				if (Utility.StreamCheckBytes(stream, 0x169B260, [0xB8, 0x01, 0x00, 0x00, 0x00, 0xC3, 0x90]))
+					statusVulkan = GameExeStatus.Patched_New;
+				else if (Utility.StreamCheckBytes(stream, 0x169B260, [0x40, 0x55, 0x53, 0x56, 0x57, 0x41, 0x56]))
+					statusVulkan = GameExeStatus.Vanilla_New;
+				else if (stream.Length == 100_128_464)
+					statusVulkan = GameExeStatus.Vanilla_Old;
+			}
+		}
+		catch (Exception e) when (e is IOException or UnauthorizedAccessException)
+			{return GameExeStatus.Unknown;}
+
+		if (statusGl == statusVulkan)
+			return statusGl;
+		else
+			return GameExeStatus.Unknown; // Version/Patch status mismatch?
 	}
 
 	// Patches the 2024 game executables to not require developer mode to load mods,
 	// and to allow earning achievements and saving settings while mods are installed
 	// Returns true if the executables are patched successfully
 	static bool PatchGameExecutables()
 	{
-		return false;
+		if (!File.Exists("./DOOMx64.exe") || !File.Exists("./DOOMx64vk.exe"))
+			return false;
+
+		try
+		{
+			// Back up the original executables
+			Console.WriteLine("Backing up game executables to the \"base\" folder...");
+			File.Copy("./DOOMx64.exe",   "./base/DOOMx64 (Pre-DOOMModLoader backup).exe",   true);
+			File.Copy("./DOOMx64vk.exe", "./base/DOOMx64vk (Pre-DOOMModLoader backup).exe", true);
+
+			Console.WriteLine("Patching game executables to load mods...");
+
+			// Patch the OpenGL executable
+			using (FileStream stream = File.Open("./DOOMx64.exe", FileMode.Open))
+			{
+				if (stream.Length < 0x169C0E0 + 7)
+					return false; // Too short for the byte sequence check
+
+				if (Utility.StreamCheckBytes(stream, 0x169C0E0, [0x40, 0x55, 0x53, 0x56, 0x57, 0x41, 0x56]))
+				{
+					stream.Position = 0x169C0E0;
+					stream.Write([0xB8, 0x01, 0x00, 0x00, 0x00, 0xC3, 0x90]); // mov eax, 1; ret; nop;
+				}
+				else
+					return false;
+			}
+			// Patch the Vulkan executable
+			using (FileStream stream = File.Open("./DOOMx64vk.exe", FileMode.Open))
+			{
+				if (stream.Length < 0x169B260 + 7)
+					return false;
+
+				if (Utility.StreamCheckBytes(stream, 0x169B260, [0x40, 0x55, 0x53, 0x56, 0x57, 0x41, 0x56]))
+				{
+					stream.Position = 0x169B260;
+					stream.Write([0xB8, 0x01, 0x00, 0x00, 0x00, 0xC3, 0x90]);
+				}
+				else
+					return false;
+			}
+		}
+		catch (Exception e) when (e is ArgumentException or IOException or UnauthorizedAccessException)
+			{return false;}
+
+		return true;
 	}
 }