Merge pull request #2471 from cpraehaus/load-xamarin-compressed-assemblies

Fix #2137: Support loading compressed Xamarin assemblies

ILSpy/ILSpy.csproj

@@ -54,6 +54,8 @@
     <PackageReference Include="Microsoft.Xaml.Behaviors.Wpf" Version="1.1.31" />
     <PackageReference Include="TomsToolbox.Wpf.Styles" Version="$(WpfStylesToolboxVersion)" />
     <PackageReference Include="System.Runtime.Loader" Version="4.3.0" />
+    <PackageReference Include="K4os.Compression.LZ4" Version="1.2.6" />
+    <PackageReference Include="System.Buffers" Version="4.5.1" />
   </ItemGroup>
 
   <ItemGroup>

ILSpy/LoadedAssembly.cs

@@ -17,6 +17,7 @@
 // DEALINGS IN THE SOFTWARE.
 
 using System;
+using System.Buffers;
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.IO;
@@ -35,6 +36,8 @@ using ICSharpCode.Decompiler.TypeSystem.Implementation;
 using ICSharpCode.Decompiler.Util;
 using ICSharpCode.ILSpy.Options;
 
+using K4os.Compression.LZ4;
+
 #nullable enable
 
 namespace ICSharpCode.ILSpy
@@ -323,6 +326,15 @@ namespace ICSharpCode.ILSpy
 			{
 				loadAssemblyException = ex;
 			}
+			// Maybe its a compressed Xamarin/Mono assembly, see https://github.com/xamarin/xamarin-android/pull/4686
+			try
+			{
+				return LoadCompressedAssembly(fileName);
+			}
+			catch (InvalidDataException)
+			{
+				// Not a compressed module, try other options below
+			}
 			// If it's not a .NET module, maybe it's a single-file bundle
 			var bundle = LoadedPackage.FromBundle(fileName);
 			if (bundle != null)
@@ -365,6 +377,42 @@ namespace ICSharpCode.ILSpy
 			return new LoadResult(module);
 		}
 
+		LoadResult LoadCompressedAssembly(string fileName)
+		{
+			const uint CompressedDataMagic = 0x5A4C4158; // Magic used for Xamarin compressed module header ('XALZ', little-endian)
+			using (var fileStream = new FileStream(fileName, FileMode.Open, FileAccess.Read))
+			using (var fileReader = new BinaryReader(fileStream))
+			{
+				// Read compressed file header
+				var magic = fileReader.ReadUInt32();
+				if (magic != CompressedDataMagic)
+					throw new InvalidDataException($"Xamarin compressed module header magic {magic} does not match expected {CompressedDataMagic}");
+				_ = fileReader.ReadUInt32(); // skip index into descriptor table, unused
+				int uncompressedLength = (int)fileReader.ReadUInt32();
+				int compressedLength = (int)fileStream.Length;  // Ensure we read all of compressed data
+				ArrayPool<byte> pool = ArrayPool<byte>.Shared;
+				var src = pool.Rent(compressedLength);
+				var dst = pool.Rent(uncompressedLength);
+				try
+				{
+					// fileReader stream position is now at compressed module data
+					fileStream.Read(src, 0, compressedLength);
+					// Decompress
+					LZ4Codec.Decode(src, 0, compressedLength, dst, 0, uncompressedLength);
+					// Load module from decompressed data buffer
+					using (var uncompressedStream = new MemoryStream(dst, writable: false))
+					{
+						return LoadAssembly(uncompressedStream, PEStreamOptions.PrefetchEntireImage);
+					}
+				}
+				finally
+				{
+					pool.Return(dst);
+					pool.Return(src);
+				}
+			}
+		}
+
 		IDebugInfoProvider? LoadDebugInfo(PEFile module)
 		{
 			if (DecompilerSettingsPanel.CurrentDecompilerSettings.UseDebugSymbols)

doc/third-party-notices.txt

@@ -415,6 +415,34 @@ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
 
 
+License Notice for K4os.Compression.LZ4 (part of ILSpy)
+---------------------------
+
+https://github.com/MiloszKrajewski/K4os.Compression.LZ4/blob/master/LICENSE
+
+MIT License
+
+Copyright (c) 2017 Milosz Krajewski
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+
+
 License Notice for LightJson (part of ICSharpCode.Decompiler)
 ---------------------------