Replaced hardcoded SourceType with custom defined ISourceResolver.

OpenRA.Mods.Common/Installer/SourceResolvers/DiscSourceResolver.cs

@@ -0,0 +1,60 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2022 The OpenRA Developers (see AUTHORS)
+ * This file is part of OpenRA, which is free software. It is made
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version. For more
+ * information, see COPYING.
+ */
+#endregion
+
+using System;
+using System.IO;
+using System.Linq;
+
+namespace OpenRA.Mods.Common.Installer
+{
+	public class DiscSourceResolver : ISourceResolver
+	{
+		public string FindSourcePath(ModContent.ModSource source)
+		{
+			var volumes = DriveInfo.GetDrives()
+				.Where(d =>
+				{
+					if (d.DriveType == DriveType.CDRom && d.IsReady)
+						return true;
+
+					// HACK: the "TFD" DVD is detected as a fixed udf-formatted drive on OSX
+					if (d.DriveType == DriveType.Fixed && d.DriveFormat == "udf")
+						return true;
+
+					return false;
+				})
+				.Select(v => v.RootDirectory.FullName);
+
+			if (Platform.CurrentPlatform == PlatformType.Linux)
+			{
+				// Outside of Gnome, most mounting tools on Linux don't set DriveType.CDRom
+				// so provide a fallback by allowing users to manually mount images on known paths
+				volumes = volumes.Concat(new[]
+				{
+					"/media/openra",
+					"/media/" + Environment.UserName + "/openra",
+					"/mnt/openra"
+				});
+			}
+
+			foreach (var volume in volumes)
+				if (InstallerUtils.IsValidSourcePath(volume, source))
+					return volume;
+
+			return null;
+		}
+
+		public Availability GetAvailability()
+		{
+			return Availability.GameSource;
+		}
+	}
+}