Fix #1192: Use custom ResourcesFile implementation

This avoids deserializing objects embedded in .resources files within the ILSpy process.

ICSharpCode.Decompiler/CSharp/WholeProjectDecompiler.cs

@@ -21,7 +21,6 @@ using System.Collections;
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
-using System.Resources;
 using System.Threading.Tasks;
 using System.Xml;
 using ICSharpCode.Decompiler.CSharp.OutputVisitor;
@@ -31,6 +30,7 @@ using ICSharpCode.Decompiler.TypeSystem;
 using ICSharpCode.Decompiler.Util;
 using Mono.Cecil;
 using System.Threading;
+using System.Text;
 
 namespace ICSharpCode.Decompiler.CSharp
 {
@@ -330,20 +330,29 @@ namespace ICSharpCode.Decompiler.CSharp
 				Stream stream = r.GetResourceStream();
 				stream.Position = 0;
 
-				IEnumerable<DictionaryEntry> entries;
 				if (r.Name.EndsWith(".resources", StringComparison.OrdinalIgnoreCase)) {
-					if (GetEntries(stream, out entries) && entries.All(e => e.Value is Stream)) {
+					bool decodedIntoIndividualFiles;
-						foreach (var pair in entries) {
+					try {
-							string fileName = Path.Combine(((string)pair.Key).Split('/').Select(p => CleanUpFileName(p)).ToArray());
+						var resourcesFile = new ResourcesFile(stream);
-							string dirName = Path.GetDirectoryName(fileName);
+						if (resourcesFile.AllEntriesAreStreams()) {
-							if (!string.IsNullOrEmpty(dirName) && directories.Add(dirName)) {
+							foreach (var (name, value) in resourcesFile) {
-								Directory.CreateDirectory(Path.Combine(targetDirectory, dirName));
+								string fileName = Path.Combine(name.Split('/').Select(p => CleanUpFileName(p)).ToArray());
+								string dirName = Path.GetDirectoryName(fileName);
+								if (!string.IsNullOrEmpty(dirName) && directories.Add(dirName)) {
+									Directory.CreateDirectory(Path.Combine(targetDirectory, dirName));
+								}
+								Stream entryStream = (Stream)value;
+								entryStream.Position = 0;
+								WriteResourceToFile(Path.Combine(targetDirectory, fileName), (string)name, entryStream);
 							}
-							Stream entryStream = (Stream)pair.Value;
+							decodedIntoIndividualFiles = true;
-							entryStream.Position = 0;
+						} else {
-							WriteResourceToFile(Path.Combine(targetDirectory, fileName), (string)pair.Key, entryStream);
+							decodedIntoIndividualFiles = false;
 						}
-					} else {
+					} catch (BadImageFormatException) {
+						decodedIntoIndividualFiles = false;
+					}
+					if (!decodedIntoIndividualFiles) {
 						stream.Position = 0;
 						string fileName = Path.ChangeExtension(GetFileNameForResource(r.Name), ".resource");
 						WriteResourceToFile(fileName, r.Name, stream);
@@ -381,17 +390,6 @@ namespace ICSharpCode.Decompiler.CSharp
 			}
 			return fileName;
 		}
-
-		bool GetEntries(Stream stream, out IEnumerable<DictionaryEntry> entries)
-		{
-			try {
-				entries = new ResourceSet(stream).Cast<DictionaryEntry>();
-				return true;
-			} catch (ArgumentException) {
-				entries = null;
-				return false;
-			}
-		}
 		#endregion
 
 		/// <summary>
@@ -406,9 +404,21 @@ namespace ICSharpCode.Decompiler.CSharp
 			if (pos > 0)
 				text = text.Substring(0, pos);
 			text = text.Trim();
-			foreach (char c in Path.GetInvalidFileNameChars())
+			// Whitelist allowed characters, replace everything else:
-				text = text.Replace(c, '-');
+			StringBuilder b = new StringBuilder(text.Length);
-			return text;
+			foreach (var c in text) {
+				if (char.IsLetterOrDigit(c) || c == '-' || c == '_')
+					b.Append(c);
+				else if (c == '.' && b.Length > 0 && b[b.Length - 1] != '.')
+					b.Append('.'); // allow dot, but never two in a row
+				else
+					b.Append('-');
+				if (b.Length >= 64)
+					break; // limit to 64 chars
+			}
+			if (b.Length == 0)
+				b.Append('-');
+			return b.ToString();
 		}
 
 		public static string GetPlatformName(ModuleDefinition module)

ICSharpCode.Decompiler/ICSharpCode.Decompiler.csproj

@@ -336,6 +336,7 @@
     <Compile Include="Util\GraphVizGraph.cs" />
     <Compile Include="Util\KeyComparer.cs" />
     <Compile Include="Util\LongDict.cs" />
+    <Compile Include="Util\ResourcesFile.cs" />
     <Compile Include="Util\UnicodeNewline.cs" />
     <Compile Include="FlowAnalysis\ControlFlowNode.cs" />
     <Compile Include="FlowAnalysis\DataFlowVisitor.cs" />

ICSharpCode.Decompiler/Util/ResourcesFile.cs

@@ -0,0 +1,466 @@
+// Copyright (c) 2018 Daniel Grunwald
+// Based on the .NET Core ResourceReader; make available under the MIT license
+// by the .NET Foundation.
+// 
+// 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.
+
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.IO;
+using System.Text;
+
+namespace ICSharpCode.Decompiler.Util
+{
+	/// <summary>
+	/// .resources file.
+	/// </summary>
+	public class ResourcesFile : IEnumerable<KeyValuePair<string, object>>, IDisposable
+	{
+		sealed class MyBinaryReader : BinaryReader
+		{
+			public MyBinaryReader(Stream input, bool leaveOpen) : base(input, Encoding.UTF8, leaveOpen)
+			{
+			}
+
+			// upgrade from protected to public visibility
+			public new int Read7BitEncodedInt()
+			{
+				return base.Read7BitEncodedInt();
+			}
+
+			public void Seek(long pos, SeekOrigin origin)
+			{
+				BaseStream.Seek(pos, origin);
+			}
+		}
+
+		enum ResourceTypeCode
+		{
+			Null = 0,
+			String = 1,
+			Boolean = 2,
+			Char = 3,
+			Byte = 4,
+			SByte = 5,
+			Int16 = 6,
+			UInt16 = 7,
+			Int32 = 8,
+			UInt32 = 9,
+			Int64 = 10,
+			UInt64 = 11,
+			Single = 12,
+			Double = 13,
+			Decimal = 14,
+			DateTime = 0xF,
+			TimeSpan = 0x10,
+			LastPrimitive = 0x10,
+			ByteArray = 0x20,
+			Stream = 33,
+			StartOfUserTypes = 0x40
+		}
+
+		/// <summary>Holds the number used to identify resource files.</summary>
+		public const int MagicNumber = unchecked((int)0xBEEFCACE);
+		const int ResourceSetVersion = 2;
+
+		readonly MyBinaryReader reader;
+		readonly int version;
+		readonly int numResources;
+		readonly string[] typeTable;
+		readonly int[] namePositions;
+		readonly long fileStartPosition;
+		readonly long nameSectionPosition;
+		readonly long dataSectionPosition;
+
+		/// <summary>
+		/// Creates a new ResourcesFile.
+		/// </summary>
+		/// <param name="stream">Input stream.</param>
+		/// <param name="leaveOpen">Whether the stream should be help open when the ResourcesFile is disposed.</param>
+		/// <remarks>
+		/// The stream is must be held open while the ResourcesFile is in use.
+		/// The stream must be seekable; any operation using the ResourcesFile will end up seeking the stream.
+		/// </remarks>
+		public ResourcesFile(Stream stream, bool leaveOpen = true)
+		{
+			fileStartPosition = stream.Position;
+			reader = new MyBinaryReader(stream, leaveOpen);
+
+			const string ResourcesHeaderCorrupted = "Resources header corrupted.";
+
+			// Read ResourceManager header
+			// Check for magic number
+			int magicNum = reader.ReadInt32();
+			if (magicNum != MagicNumber)
+				throw new BadImageFormatException("Not a .resources file - invalid magic number");
+			// Assuming this is ResourceManager header V1 or greater, hopefully
+			// after the version number there is a number of bytes to skip
+			// to bypass the rest of the ResMgr header. For V2 or greater, we
+			// use this to skip to the end of the header
+			int resMgrHeaderVersion = reader.ReadInt32();
+			int numBytesToSkip = reader.ReadInt32();
+			if (numBytesToSkip < 0 || resMgrHeaderVersion < 0) {
+				throw new BadImageFormatException(ResourcesHeaderCorrupted);
+			}
+			if (resMgrHeaderVersion > 1) {
+				reader.BaseStream.Seek(numBytesToSkip, SeekOrigin.Current);
+			} else {
+				// We don't care about numBytesToSkip; read the rest of the header
+
+				// readerType:
+				reader.ReadString();
+				// resourceSetType:
+				reader.ReadString();
+			}
+
+			// Read RuntimeResourceSet header
+			// Do file version check
+			version = reader.ReadInt32();
+			if (version != ResourceSetVersion && version != 1)
+				throw new BadImageFormatException($"Unsupported resource set version: {version}");
+
+			numResources = reader.ReadInt32();
+			if (numResources < 0) {
+				throw new BadImageFormatException(ResourcesHeaderCorrupted);
+			}
+
+			// Read type positions into type positions array.
+			// But delay initialize the type table.
+			int numTypes = reader.ReadInt32();
+			if (numTypes < 0) {
+				throw new BadImageFormatException(ResourcesHeaderCorrupted);
+			}
+			typeTable = new string[numTypes];
+			for (int i = 0; i < numTypes; i++) {
+				typeTable[i] = reader.ReadString();
+			}
+
+			// Prepare to read in the array of name hashes
+			//  Note that the name hashes array is aligned to 8 bytes so 
+			//  we can use pointers into it on 64 bit machines. (4 bytes 
+			//  may be sufficient, but let's plan for the future)
+			//  Skip over alignment stuff.  All public .resources files
+			//  should be aligned   No need to verify the byte values.
+			long pos = reader.BaseStream.Position - fileStartPosition;
+			int alignBytes = unchecked((int)pos) & 7;
+			if (alignBytes != 0) {
+				for (int i = 0; i < 8 - alignBytes; i++) {
+					reader.ReadByte();
+				}
+			}
+
+			// Skip over the array of name hashes
+			try {
+				reader.Seek(checked(4 * numResources), SeekOrigin.Current);
+			} catch (OverflowException) {
+				throw new BadImageFormatException(ResourcesHeaderCorrupted);
+			}
+
+			// Read in the array of relative positions for all the names.
+			namePositions = new int[numResources];
+			for (int i = 0; i < numResources; i++) {
+				int namePosition = reader.ReadInt32();
+				if (namePosition < 0) {
+					throw new BadImageFormatException(ResourcesHeaderCorrupted);
+				}
+				namePositions[i] = namePosition;
+			}
+
+			// Read location of data section.
+			int dataSectionOffset = reader.ReadInt32();
+			if (dataSectionOffset < 0) {
+				throw new BadImageFormatException(ResourcesHeaderCorrupted);
+			}
+
+			// Store current location as start of name section
+			nameSectionPosition = reader.BaseStream.Position;
+			dataSectionPosition = fileStartPosition + dataSectionOffset;
+
+			// _nameSectionOffset should be <= _dataSectionOffset; if not, it's corrupt
+			if (dataSectionPosition < nameSectionPosition) {
+				throw new BadImageFormatException(ResourcesHeaderCorrupted);
+			}
+		}
+
+		public void Dispose()
+		{
+			reader.Dispose();
+		}
+
+		public int ResourceCount => numResources;
+
+		public string GetResourceName(int index)
+		{
+			return GetResourceName(index, out _);
+		}
+
+		string GetResourceName(int index, out int dataOffset)
+		{
+			long pos = nameSectionPosition + namePositions[index];
+			byte[] bytes;
+			lock (reader) {
+				reader.Seek(pos, SeekOrigin.Begin);
+				// Can't use reader.ReadString, since it's using UTF-8!
+				int byteLen = reader.Read7BitEncodedInt();
+				if (byteLen < 0) {
+					throw new BadImageFormatException("Resource name has negative length");
+				}
+				bytes = new byte[byteLen];
+				// We must read byteLen bytes, or we have a corrupted file.
+				// Use a blocking read in case the stream doesn't give us back
+				// everything immediately.
+				int count = byteLen;
+				while (count > 0) {
+					int n = reader.Read(bytes, byteLen - count, count);
+					if (n == 0)
+						throw new BadImageFormatException("End of stream within a resource name");
+					count -= n;
+				}
+				dataOffset = reader.ReadInt32();
+				if (dataOffset < 0) {
+					throw new BadImageFormatException("Negative data offset");
+				}
+			}
+			return Encoding.Unicode.GetString(bytes);
+		}
+		
+		internal bool AllEntriesAreStreams()
+		{
+			if (version != 2)
+				return false;
+			for (int i = 0; i < numResources; i++) {
+				GetResourceName(i, out int dataOffset);
+				lock (reader) {
+					reader.Seek(dataSectionPosition + dataOffset, SeekOrigin.Begin);
+					var typeCode = (ResourceTypeCode)reader.Read7BitEncodedInt();
+					if (typeCode != ResourceTypeCode.Stream)
+						return false;
+				}
+			}
+			return true;
+		}
+
+		object LoadObject(int dataOffset)
+		{
+			try {
+				lock (reader) {
+					if (version == 1) {
+						return LoadObjectV1(dataOffset);
+					} else {
+						return LoadObjectV2(dataOffset);
+					}
+				}
+			} catch (EndOfStreamException e) {
+				throw new BadImageFormatException("Invalid resource file", e);
+			}
+		}
+
+		string FindType(int typeIndex)
+		{
+			if (typeIndex < 0 || typeIndex >= typeTable.Length)
+				throw new BadImageFormatException("Type index out of bounds");
+			return typeTable[typeIndex];
+		}
+
+		// This takes a virtual offset into the data section and reads an Object
+		// from that location.
+		// Anyone who calls LoadObject should make sure they take a lock so 
+		// no one can cause us to do a seek in here.
+		private object LoadObjectV1(int dataOffset)
+		{
+			Debug.Assert(System.Threading.Monitor.IsEntered(reader));
+			reader.Seek(dataSectionPosition + dataOffset, SeekOrigin.Begin);
+			int typeIndex = reader.Read7BitEncodedInt();
+			if (typeIndex == -1)
+				return null;
+			string typeName = FindType(typeIndex);
+			int comma = typeName.IndexOf(',');
+			if (comma > 0) {
+				// strip assembly name
+				typeName = typeName.Substring(0, comma);
+			}
+			switch (typeName) {
+				case "System.String":
+					return reader.ReadString();
+				case "System.Byte":
+					return reader.ReadByte();
+				case "System.SByte":
+					return reader.ReadSByte();
+				case "System.Int16":
+					return reader.ReadInt16();
+				case "System.UInt16":
+					return reader.ReadUInt16();
+				case "System.Int32":
+					return reader.ReadInt32();
+				case "System.UInt32":
+					return reader.ReadUInt32();
+				case "System.Int64":
+					return reader.ReadInt64();
+				case "System.UInt64":
+					return reader.ReadUInt64();
+				case "System.Single":
+					return reader.ReadSingle();
+				case "System.Double":
+					return reader.ReadDouble();
+				case "System.DateTime":
+					// Ideally we should use DateTime's ToBinary & FromBinary,
+					// but we can't for compatibility reasons.
+					return new DateTime(reader.ReadInt64());
+				case "System.TimeSpan":
+					return new TimeSpan(reader.ReadInt64());
+				case "System.Decimal":
+					int[] bits = new int[4];
+					for (int i = 0; i < bits.Length; i++)
+						bits[i] = reader.ReadInt32();
+					return new decimal(bits);
+				default:
+					return new ResourceSerializedObject(FindType(typeIndex), reader);
+			}
+		}
+
+		private object LoadObjectV2(int dataOffset)
+		{
+			Debug.Assert(System.Threading.Monitor.IsEntered(reader));
+			reader.Seek(dataSectionPosition + dataOffset, SeekOrigin.Begin);
+			var typeCode = (ResourceTypeCode)reader.Read7BitEncodedInt();
+			switch (typeCode) {
+				case ResourceTypeCode.Null:
+					return null;
+
+				case ResourceTypeCode.String:
+					return reader.ReadString();
+
+				case ResourceTypeCode.Boolean:
+					return reader.ReadBoolean();
+
+				case ResourceTypeCode.Char:
+					return (char)reader.ReadUInt16();
+
+				case ResourceTypeCode.Byte:
+					return reader.ReadByte();
+
+				case ResourceTypeCode.SByte:
+					return reader.ReadSByte();
+
+				case ResourceTypeCode.Int16:
+					return reader.ReadInt16();
+
+				case ResourceTypeCode.UInt16:
+					return reader.ReadUInt16();
+
+				case ResourceTypeCode.Int32:
+					return reader.ReadInt32();
+
+				case ResourceTypeCode.UInt32:
+					return reader.ReadUInt32();
+
+				case ResourceTypeCode.Int64:
+					return reader.ReadInt64();
+
+				case ResourceTypeCode.UInt64:
+					return reader.ReadUInt64();
+
+				case ResourceTypeCode.Single:
+					return reader.ReadSingle();
+
+				case ResourceTypeCode.Double:
+					return reader.ReadDouble();
+
+				case ResourceTypeCode.Decimal:
+					return reader.ReadDecimal();
+
+				case ResourceTypeCode.DateTime:
+					// Use DateTime's ToBinary & FromBinary.
+					long data = reader.ReadInt64();
+					return DateTime.FromBinary(data);
+
+				case ResourceTypeCode.TimeSpan:
+					long ticks = reader.ReadInt64();
+					return new TimeSpan(ticks);
+
+				// Special types
+				case ResourceTypeCode.ByteArray: {
+						int len = reader.ReadInt32();
+						if (len < 0) {
+							throw new BadImageFormatException("Resource with negative length");
+						}
+						return reader.ReadBytes(len);
+					}
+
+				case ResourceTypeCode.Stream: {
+						int len = reader.ReadInt32();
+						if (len < 0) {
+							throw new BadImageFormatException("Resource with negative length");
+						}
+						byte[] bytes = reader.ReadBytes(len);
+						return new MemoryStream(bytes, writable: false);
+					}
+
+				default:
+					if (typeCode < ResourceTypeCode.StartOfUserTypes) {
+						throw new BadImageFormatException("Invalid typeCode");
+					}
+					return new ResourceSerializedObject(FindType(typeCode - ResourceTypeCode.StartOfUserTypes), reader);
+			}
+		}
+
+		public object GetResourceValue(int index)
+		{
+			GetResourceName(index, out int dataOffset);
+			return LoadObject(dataOffset);
+		}
+
+		public IEnumerator<KeyValuePair<string, object>> GetEnumerator()
+		{
+			for (int i = 0; i < numResources; i++) {
+				string name = GetResourceName(i, out int dataOffset);
+				object val = LoadObject(dataOffset);
+				yield return new KeyValuePair<string, object>(name, val);
+			}
+		}
+
+		IEnumerator IEnumerable.GetEnumerator()
+		{
+			return GetEnumerator();
+		}
+	}
+
+	public class ResourceSerializedObject
+	{
+		public string TypeName { get; }
+		readonly Stream stream;
+		readonly long position;
+		
+		internal ResourceSerializedObject(string typeName, BinaryReader reader)
+		{
+			this.TypeName = typeName;
+			this.stream = reader.BaseStream;
+			this.position = stream.Position;
+		}
+
+		/// <summary>
+		/// Gets a stream that starts with the serialized object data.
+		/// </summary>
+		public Stream GetStream()
+		{
+			stream.Seek(position, SeekOrigin.Begin);
+			return stream;
+		}
+	}
+}

ILSpy.BamlDecompiler.Tests/BamlTestRunner.cs

@@ -5,7 +5,6 @@ using System;
 using System.Collections;
 using System.IO;
 using System.Linq;
-using System.Resources;
 using System.Threading;
 using System.Xml.Linq;
 using ICSharpCode.Decompiler.Tests.Helpers;

ILSpy/Languages/CSharpLanguage.cs

@@ -22,7 +22,6 @@ using System.Collections.Generic;
 using System.ComponentModel.Composition;
 using System.IO;
 using System.Linq;
-using System.Resources;
 
 using ICSharpCode.Decompiler;
 using Mono.Cecil;
@@ -34,6 +33,8 @@ using System.Windows;
 using System.Windows.Controls;
 using ICSharpCode.ILSpy.TreeNodes;
 using ICSharpCode.Decompiler.CSharp.Transforms;
+using System.Resources;
+using ICSharpCode.Decompiler.Util;
 
 namespace ICSharpCode.ILSpy
 {
@@ -400,11 +401,10 @@ namespace ICSharpCode.ILSpy
 			protected override IEnumerable<Tuple<string, string>> WriteResourceToFile(string fileName, string resourceName, Stream entryStream)
 			{
 				if (fileName.EndsWith(".resource", StringComparison.OrdinalIgnoreCase)) {
-					using (ResourceReader reader = new ResourceReader(entryStream))
 					using (FileStream fs = new FileStream(Path.Combine(targetDirectory, fileName), FileMode.Create, FileAccess.Write))
 					using (ResXResourceWriter writer = new ResXResourceWriter(fs)) {
-						foreach (DictionaryEntry entry in reader) {
+						foreach (var entry in new ResourcesFile(entryStream)) {
-							writer.AddResource((string)entry.Key, entry.Value);
+							writer.AddResource(entry.Key, entry.Value);
 						}
 					}
 					return new[] { Tuple.Create("EmbeddedResource", fileName) };

ILSpy/TreeNodes/ResourceNodes/ResourcesFileTreeNode.cs

@@ -24,8 +24,8 @@ using System.ComponentModel.Composition;
 using System.IO;
 using System.Linq;
 using System.Resources;
-
 using ICSharpCode.Decompiler;
+using ICSharpCode.Decompiler.Util;
 using ICSharpCode.ILSpy.Controls;
 using ICSharpCode.ILSpy.TextView;
 using Microsoft.Win32;
@@ -73,44 +73,40 @@ namespace ICSharpCode.ILSpy.TreeNodes
 			if (er != null) {
 				Stream s = er.GetResourceStream();
 				s.Position = 0;
-				ResourceReader reader;
 				try {
-					reader = new ResourceReader(s);
+					foreach (var entry in new ResourcesFile(s)) {
-				}
+						ProcessResourceEntry(entry);
-				catch (ArgumentException) {
+					}
-					return;
+				} catch (BadImageFormatException) {
-				}
+					// ignore errors
-				foreach (DictionaryEntry entry in reader.Cast<DictionaryEntry>().OrderBy(e => e.Key.ToString())) {
-					ProcessResourceEntry(entry);
 				}
 			}
 		}
 
-		private void ProcessResourceEntry(DictionaryEntry entry)
+		private void ProcessResourceEntry(KeyValuePair<string, object> entry)
 		{
-			var keyString = entry.Key.ToString();
-
 			if (entry.Value is String) {
-				stringTableEntries.Add(new KeyValuePair<string, string>(keyString, (string)entry.Value));
+				stringTableEntries.Add(new KeyValuePair<string, string>(entry.Key, (string)entry.Value));
 				return;
 			}
 
 			if (entry.Value is byte[]) {
-				Children.Add(ResourceEntryNode.Create(keyString, new MemoryStream((byte[])entry.Value)));
+				Children.Add(ResourceEntryNode.Create(entry.Key, new MemoryStream((byte[])entry.Value)));
 				return;
 			}
 
-			var node = ResourceEntryNode.Create(keyString, entry.Value);
+			var node = ResourceEntryNode.Create(entry.Key, entry.Value);
 			if (node != null) {
 				Children.Add(node);
 				return;
 			}
 
-			string entryType = entry.Value.GetType().FullName;
+			if (entry.Value == null) {
-			if (entry.Value is System.Globalization.CultureInfo) {
+				otherEntries.Add(new SerializedObjectRepresentation(entry.Key, "null", ""));
-				otherEntries.Add(new SerializedObjectRepresentation(keyString, entryType, ((System.Globalization.CultureInfo)entry.Value).DisplayName));
+			} else if (entry.Value is ResourceSerializedObject so) {
+				otherEntries.Add(new SerializedObjectRepresentation(entry.Key, so.TypeName, "<serialized>"));
 			} else {
-				otherEntries.Add(new SerializedObjectRepresentation(keyString, entryType, entry.Value.ToString()));
+				otherEntries.Add(new SerializedObjectRepresentation(entry.Key, entry.Value.GetType().FullName, entry.Value.ToString()));
 			}
 		}
 		
@@ -131,10 +127,9 @@ namespace ICSharpCode.ILSpy.TreeNodes
 							}
 							break;
 						case 2:
-							var reader = new ResourceReader(s);
 							using (var writer = new ResXResourceWriter(dlg.OpenFile())) {
-								foreach (DictionaryEntry entry in reader) {
+								foreach (var entry in new ResourcesFile(s)) {
-									writer.AddResource(entry.Key.ToString(), entry.Value);
+									writer.AddResource(entry.Key, entry.Value);
 								}
 							}
 							break;

doc/Resources.txt

@@ -0,0 +1,99 @@
+System.Resources.ResourceReader is unsuitable for deserializing resources in the ILSpy context,
+because it tries to deserialize custom resource types, which fails if the types are in a non-GAC assembly.
+
+So we are instead using our own "class ResourcesFile", which is based on the
+.NET Core ResourceReader implementation.
+
+struct ResourcesFileFormat {
+	int32 magicNum; [check == ResourceManager.MagicNumber]
+	
+	// ResourceManager header:
+	int32 resMgrHeaderVersion; [check >= 0]
+	int32 numBytesToSkip; [check >= 0]
+	if (resMgrHeaderVersion <= 1) {
+		string readerType;
+		string resourceSetType;
+	} else {
+		byte _[numBytesToSkip];
+	}
+	
+	// RuntimeResourceSet header:
+	int32 version; [check in (1, 2)]
+	int32 numResources; [check >=0]
+	int32 numTypes; [check >=0]
+	string typeName[numTypes];
+	.align 8;
+	int32 nameHashes[numResources];
+	int32 namePositions[numResources]; [check >= 0]
+	int32 dataSectionOffset; [check >= current position in file]
+	byte remainderOfFile[];
+}
+
+// normal strings in this file format are stored as:
+struct string {
+	compressedint len;
+	byte value[len]; // interpret as UTF-8
+}
+
+// NameEntry #i is stored starting at remainderOfFile[namePositions[i]]
+// (that is, namePositions is interpreted relative to the start of the remainderOfFile array)
+struct NameEntry {
+	compressedint len;
+	byte name[len]; // interpret as UTF-16
+	int32 dataOffset; [check >= 0]
+}
+
+// Found at position ResourcesFileFormat.dataSectionOffset+NameEntry.dataOffset in the file.
+struct ValueEntry {
+	if (version == 1) {
+		compressedint typeIndex;
+		if (typeIndex == -1) {
+			// no value stored; value is implicitly null
+		} else {
+			switch (typeName[typeIndex]) {
+				case string:
+				case int, uint, long, ulong, sbyte, byte, short, ushort:
+				case float:
+				case double:
+					T value; // value directly stored
+				case DateTime:
+					int64 value; // new DateTime(_store.ReadInt64())
+				case TimeSpan:
+					int64 value; // new TimeSpan(_store.ReadInt64())
+				case decimal:
+					int32 value[4];
+				default:
+					byte data[...]; // BinaryFormatter-serialized data using typeName[typeIndex]
+			}
+		}
+	} else if (version == 2) {
+		compressedint typeCode;
+		// note: unlike v1, no lookup into the typeName array!
+		switch (typeCode) {
+			case null:
+				// no value stored; value is implicitly null
+			case string:
+			case bool:
+			case int, uint, long, ulong, sbyte, byte, short, ushort:
+				T value;
+			case char:
+				uint16 value;
+			case float:
+			case double:
+			case decimal:
+				T value;
+			case DateTime:
+				int64 value; // DateTime.FromBinary(_store.ReadInt64())
+			case TimeSpan:
+				int64 value; // new TimeSpan(_store.ReadInt64())
+			case ResourceTypeCode.ByteArray:
+				int32 len;
+				byte value[len];
+			case ResourceTypeCode.Stream:
+				int32 len;
+				byte value[len];
+			case >= ResourceTypeCode.StartOfUserTypes:
+				byte data[...]; // BinaryFormatter-serialized data using typeName[typeCode - ResourceTypeCode.StartOfUserTypes]
+		}
+	}
+}