Add UnpackMapCommand

This command allows either unpacking oramap files into folders, or packing folders into oramap files.

Example invocations:
"d2k --unpack-map unpack" to unpack maps of the d2k mod into folders.
"cnc --unpack-map repack" to repack maps of the cnc mod into oramap files (but will only pack folders that were unpacked previously).

OpenRA.Game/FileSystem/ZipFile.cs

@@ -21,7 +21,7 @@ namespace OpenRA.FileSystem
 	{
 		const uint ZipSignature = 0x04034b50;
 
-		class ReadOnlyZipFile : IReadOnlyPackage
+		public class ReadOnlyZipFile : IReadOnlyPackage
 		{
 			public string Name { get; protected set; }
 			protected ZipFile pkg;
@@ -68,6 +68,7 @@ namespace OpenRA.FileSystem
 			public void Dispose()
 			{
 				pkg?.Close();
+				GC.SuppressFinalize(this);
 			}
 
 			public IReadOnlyPackage OpenPackage(string filename, FileSystem context)
@@ -93,7 +94,7 @@ namespace OpenRA.FileSystem
 			}
 		}
 
-		sealed class ReadWriteZipFile : ReadOnlyZipFile, IReadWritePackage
+		public sealed class ReadWriteZipFile : ReadOnlyZipFile, IReadWritePackage
 		{
 			readonly MemoryStream pkgStream = new();
 

OpenRA.Mods.Common/UtilityCommands/UnpackMapCommand.cs

@@ -0,0 +1,65 @@
+#region Copyright & License Information
+/*
+ * Copyright (c) The OpenRA Developers and Contributors
+ * 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.IO;
+using System.Linq;
+using OpenRA.FileSystem;
+
+namespace OpenRA.Mods.Common.UtilityCommands
+{
+	sealed class UnpackMapCommand : IUtilityCommand
+	{
+		string IUtilityCommand.Name => "--unpack-map";
+
+		bool IUtilityCommand.ValidateArguments(string[] args)
+		{
+			return args.Length >= 2 && new string[] { "unpack", "repack" }.Contains(args[1]);
+		}
+
+		[Desc("(unpack|repack)", "For all maps, either unpacks oramap files into folders, or repacks folders into oramap files (only if previously unpacked).")]
+		void IUtilityCommand.Run(Utility utility, string[] args)
+		{
+			var unpack = args[1] == "unpack";
+
+			// HACK: The engine code assumes that Game.modData is set.
+			// HACK: We know that maps can only be oramap or folders, which are ReadWrite
+			var modData = Game.ModData = utility.ModData;
+			modData.MapCache.LoadMaps();
+			foreach (var kv in modData.MapCache.MapLocations)
+			{
+				foreach (var mapFilename in kv.Key.Contents)
+				{
+					var mapPackage = kv.Key.OpenPackage(mapFilename, modData.ModFiles);
+					var map = new Map(modData, mapPackage);
+
+					if (unpack)
+					{
+						if (mapPackage is ZipFileLoader.ReadWriteZipFile z)
+						{
+							map.Save(new Folder(z.Name.Replace(".oramap", "")));
+						}
+					}
+					else
+					{
+						if (mapPackage is Folder f)
+						{
+							if (File.Exists(f.Name + ".oramap"))
+							{
+								map.Save(ZipFileLoader.Create(f.Name + ".oramap"));
+								Directory.Delete(f.Name, true);
+							}
+						}
+					}
+				}
+			}
+		}
+	}
+}