Fix #2038: Add proper support for Long paths on Windows 10 and limit path segments to 255 characters (with long path support) or 30 characters. If a PathTooLongException is thrown display a better error message on project export.

ICSharpCode.Decompiler.Tests/TestCases/PdbGen/ForLoopTests.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <symbols>
   <files>
-    <file id="1" name="ICSharpCode.Decompiler.Tests.TestCases.PdbGen\ForLoopTests.cs" language="C#" checksumAlgorithm="SHA256"><![CDATA[using System;
+    <file id="1" name="ICSharpCode\Decompiler\Tests\TestCases\PdbGen\ForLoopTests.cs" language="C#" checksumAlgorithm="SHA256"><![CDATA[using System;
 
 namespace ICSharpCode.Decompiler.Tests.TestCases.PdbGen
 {

ICSharpCode.Decompiler.Tests/TestCases/PdbGen/HelloWorld.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <symbols>
   <files>
-    <file id="1" name="ICSharpCode.Decompiler.Tests.TestCases.PdbGen\HelloWorld.cs" language="C#" checksumAlgorithm="SHA256"><![CDATA[using System;
+    <file id="1" name="ICSharpCode\Decompiler\Tests\TestCases\PdbGen\HelloWorld.cs" language="C#" checksumAlgorithm="SHA256"><![CDATA[using System;
 
 namespace ICSharpCode.Decompiler.Tests.TestCases.PdbGen
 {

ICSharpCode.Decompiler.Tests/TestCases/PdbGen/LambdaCapturing.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <symbols>
   <files>
-    <file id="1" name="ICSharpCode.Decompiler.Tests.TestCases.PdbGen\LambdaCapturing.cs" language="C#" checksumAlgorithm="SHA256"><![CDATA[using System;
+    <file id="1" name="ICSharpCode\Decompiler\Tests\TestCases\PdbGen\LambdaCapturing.cs" language="C#" checksumAlgorithm="SHA256"><![CDATA[using System;
 
 namespace ICSharpCode.Decompiler.Tests.TestCases.PdbGen
 {

ICSharpCode.Decompiler/CSharp/ProjectDecompiler/WholeProjectDecompiler.cs

@@ -36,6 +36,8 @@ using ICSharpCode.Decompiler.Solution;
 using ICSharpCode.Decompiler.TypeSystem;
 using ICSharpCode.Decompiler.Util;
 
+using Microsoft.Win32;
+
 using static ICSharpCode.Decompiler.Metadata.MetadataExtensions;
 
 namespace ICSharpCode.Decompiler.CSharp.ProjectDecompiler
@@ -126,7 +128,6 @@ namespace ICSharpCode.Decompiler.CSharp.ProjectDecompiler
 
 		// per-run members
 		HashSet<string> directories = new HashSet<string>(Platform.FileNameComparer);
-
 		readonly IProjectFileWriter projectWriter;
 
 		public void DecompileProject(PEFile moduleDefinition, string targetDirectory, CancellationToken cancellationToken = default(CancellationToken))
@@ -252,7 +253,7 @@ namespace ICSharpCode.Decompiler.CSharp.ProjectDecompiler
 		#region WriteResourceFilesInProject
 		protected virtual IEnumerable<(string itemType, string fileName)> WriteResourceFilesInProject(Metadata.PEFile module)
 		{
-			foreach (var r in module.Resources.Where(r => r.ResourceType == Metadata.ResourceType.Embedded))
+			foreach (var r in module.Resources.Where(r => r.ResourceType == ResourceType.Embedded))
 			{
 				Stream stream = r.TryOpenStream();
 				stream.Position = 0;
@@ -268,7 +269,8 @@ namespace ICSharpCode.Decompiler.CSharp.ProjectDecompiler
 						{
 							foreach (var (name, value) in resourcesFile)
 							{
-								string fileName = Path.Combine(name.Split('/').Select(p => CleanUpFileName(p)).ToArray());
+								string fileName = CleanUpFileName(name)
+									.Replace('/', Path.DirectorySeparatorChar);
 								string dirName = Path.GetDirectoryName(fileName);
 								if (!string.IsNullOrEmpty(dirName) && directories.Add(dirName))
 								{
@@ -359,8 +361,15 @@ namespace ICSharpCode.Decompiler.CSharp.ProjectDecompiler
 
 		string GetFileNameForResource(string fullName)
 		{
-			string[] splitName = fullName.Split('.');
-			string fileName = CleanUpFileName(fullName);
+			// Clean up the name first and ensure the length does not exceed the maximum length
+			// supported by the OS.
+			fullName = CleanUpDirectoryName(fullName);
+			// The purpose of the below algorithm is to "maximize" the directory name and "minimize" the file name.
+			// That is, a full name of the form "Namespace1.Namespace2{...}.NamespaceN.ResourceName" is split such that
+			// the directory part Namespace1\Namespace2\... reuses as many existing directories as
+			// possible, and only the remaining name parts are used as prefix for the filename.
+			string[] splitName = fullName.Split(Path.DirectorySeparatorChar);
+			string fileName = fullName;
 			string separator = Path.DirectorySeparatorChar.ToString();
 			for (int i = splitName.Length - 1; i > 0; i--)
 			{
@@ -368,7 +377,7 @@ namespace ICSharpCode.Decompiler.CSharp.ProjectDecompiler
 				if (directories.Contains(ns))
 				{
 					string name = string.Join(".", splitName, i, splitName.Length - i);
-					fileName = Path.Combine(ns, CleanUpFileName(name));
+					fileName = Path.Combine(ns, name);
 					break;
 				}
 			}
@@ -526,10 +535,50 @@ namespace ICSharpCode.Decompiler.CSharp.ProjectDecompiler
 		}
 		#endregion
 
+		static readonly Lazy<(bool longPathsEnabled, int maxPathLength, int maxSegmentLength)> longPathSupport =
+			new Lazy<(bool longPathsEnabled, int maxPathLength, int maxSegmentLength)>(GetLongPathSupport, isThreadSafe: true);
+
+		static (bool longPathsEnabled, int maxPathLength, int maxSegmentLength) GetLongPathSupport()
+		{
+			try
+			{
+				switch (Environment.OSVersion.Platform)
+				{
+					case PlatformID.MacOSX:
+					case PlatformID.Unix:
+						return (true, int.MaxValue, int.MaxValue);
+					case PlatformID.Win32NT:
+						const string key = @"SYSTEM\CurrentControlSet\Control\FileSystem";
+						var fileSystem = Registry.LocalMachine.OpenSubKey(key);
+						var value = (int?)fileSystem.GetValue("LongPathsEnabled");
+						if (value == 1)
+						{
+							return (true, int.MaxValue, 255);
+						}
+						return (false, 200, 30);
+					default:
+						return (false, 200, 30);
+				}
+			}
+			catch
+			{
+				return (false, 200, 30);
+			}
+		}
+
 		/// <summary>
 		/// Cleans up a node name for use as a file name.
 		/// </summary>
 		public static string CleanUpFileName(string text)
+		{
+			return CleanUpFileName(text, separateAtDots: false);
+		}
+
+		/// <summary>
+		/// Cleans up a node name for use as a file system name. If <paramref name="separateAtDots"/> is active,
+		/// dots are seen as segment separators. Each segment is limited to 255 characters.
+		/// </summary>
+		static string CleanUpFileName(string text, bool separateAtDots)
 		{
 			int pos = text.IndexOf(':');
 			if (pos > 0)
@@ -540,16 +589,38 @@ namespace ICSharpCode.Decompiler.CSharp.ProjectDecompiler
 			text = text.Trim();
 			// Whitelist allowed characters, replace everything else:
 			StringBuilder b = new StringBuilder(text.Length);
+			int currentSegmentLength = 0;
+			var (supportsLongPaths, maxPathLength, maxSegmentLength) = longPathSupport.Value;
 			foreach (var c in text)
 			{
+				currentSegmentLength++;
 				if (char.IsLetterOrDigit(c) || c == '-' || c == '_')
+				{
+					// if the current segment exceeds 255 characters,
+					// skip until the end of the segment.
+					if (currentSegmentLength <= maxSegmentLength)
 						b.Append(c);
+				}
 				else if (c == '.' && b.Length > 0 && b[b.Length - 1] != '.')
+				{
+					// if the current segment exceeds 255 characters,
+					// skip until the end of the segment.
+					if (separateAtDots || currentSegmentLength <= maxSegmentLength)
 						b.Append('.'); // allow dot, but never two in a row
+
+					// Reset length at end of segment.
+					if (separateAtDots)
+						currentSegmentLength = 0;
+				}
 				else
+				{
+					// if the current segment exceeds 255 characters,
+					// skip until the end of the segment.
+					if (currentSegmentLength <= maxSegmentLength)
 						b.Append('-');
-				if (b.Length >= 200)
-					break; // limit to 200 chars
+				}
+				if (b.Length >= maxPathLength && !supportsLongPaths)
+					break;  // limit to 200 chars, if long paths are not supported.
 			}
 			if (b.Length == 0)
 				b.Append('-');
@@ -567,7 +638,7 @@ namespace ICSharpCode.Decompiler.CSharp.ProjectDecompiler
 		/// </summary>
 		public static string CleanUpDirectoryName(string text)
 		{
-			return CleanUpFileName(text).Replace('.', Path.DirectorySeparatorChar);
+			return CleanUpFileName(text, separateAtDots: true).Replace('.', Path.DirectorySeparatorChar);
 		}
 
 		static bool IsReservedFileSystemName(string name)

ICSharpCode.Decompiler/DebugInfo/PortablePdbWriter.cs

@@ -66,7 +66,7 @@ namespace ICSharpCode.Decompiler.DebugInfo
 			string BuildFileNameFromTypeName(TypeDefinitionHandle handle)
 			{
 				var typeName = handle.GetFullTypeName(reader).TopLevelTypeName;
-				return Path.Combine(WholeProjectDecompiler.CleanUpFileName(typeName.Namespace), WholeProjectDecompiler.CleanUpFileName(typeName.Name) + ".cs");
+				return Path.Combine(WholeProjectDecompiler.CleanUpDirectoryName(typeName.Namespace), WholeProjectDecompiler.CleanUpFileName(typeName.Name) + ".cs");
 			}
 
 			foreach (var sourceFile in reader.GetTopLevelTypeDefinitions().GroupBy(BuildFileNameFromTypeName))

ICSharpCode.Decompiler/ICSharpCode.Decompiler.csproj

@@ -53,6 +53,7 @@
   <Import Project="..\packages.props" />
 
   <ItemGroup>
+    <PackageReference Include="Microsoft.Win32.Registry" Version="5.0.0" />
     <PackageReference Include="System.Collections.Immutable" Version="$(SystemCollectionsImmutableVersion)" />
     <PackageReference Include="System.Reflection.Metadata" Version="$(SystemReflectionMetadataVersion)" />
     <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.0.0">

ILSpy/ILSpy.csproj

@@ -13,6 +13,7 @@
     <AllowUnsafeBlocks>True</AllowUnsafeBlocks>
 
     <ApplicationIcon>Images\ILSpy-Large.ico</ApplicationIcon>
+    <ApplicationManifest>app.manifest</ApplicationManifest>
 
     <SignAssembly>True</SignAssembly>
     <AssemblyOriginatorKeyFile>..\ICSharpCode.Decompiler\ICSharpCode.Decompiler.snk</AssemblyOriginatorKeyFile>

ILSpy/Properties/Resources.Designer.cs

@@ -2010,6 +2010,17 @@ namespace ICSharpCode.ILSpy.Properties {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Failed to decompile the assemblies {0} because the namespace directory structure is nested too deep.
+        ///
+        ///If you are using Windows 10.0.14393 (Windows 10 version 1607) or later, you can enable &quot;Long path support&quot; by creating a REG_DWORD registry key named &quot;LongPathsEnabled&quot; with value 0x1 at &quot;HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\FileSystem&quot; (see https://docs.microsoft.com/en-us/windows/win32/fileio/maximum-file-path-limitation for more information)..
+        /// </summary>
+        public static string ProjectExportPathTooLong {
+            get {
+                return ResourceManager.GetString("ProjectExportPathTooLong", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to for ex. property getter/setter access. To get optimal decompilation results, please manually add the missing references to the list of loaded assemblies..
         /// </summary>

ILSpy/Properties/Resources.resx

@@ -691,6 +691,11 @@ Please disable all filters that might hide the item (i.e. activate "View > Sh
   <data name="ProjectExportFormatSDKHint" xml:space="preserve">
     <value>A SDK-style project was generated. Learn more at https://docs.microsoft.com/en-us/nuget/resources/check-project-format.</value>
   </data>
+  <data name="ProjectExportPathTooLong" xml:space="preserve">
+    <value>Failed to decompile the assemblies {0} because the namespace directory structure is nested too deep.
+
+If you are using Windows 10.0.14393 (Windows 10 version 1607) or later, you can enable "Long path support" by creating a REG_DWORD registry key named "LongPathsEnabled" with value 0x1 at "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\FileSystem" (see https://docs.microsoft.com/en-us/windows/win32/fileio/maximum-file-path-limitation for more information).</value>
+  </data>
   <data name="PropertyManuallyMissingReferencesListLoadedAssemblies" xml:space="preserve">
     <value>for ex. property getter/setter access. To get optimal decompilation results, please manually add the missing references to the list of loaded assemblies.</value>
   </data>

ILSpy/SolutionWriter.cs

@@ -229,6 +229,13 @@ namespace ICSharpCode.ILSpy
 				statusOutput.Add("-------------");
 				statusOutput.Add($"Failed to decompile the assembly '{loadedAssembly.FileName}':{Environment.NewLine}{e.Message}");
 			}
+			catch (PathTooLongException e)
+			{
+				statusOutput.Add("-------------");
+				statusOutput.Add(string.Format(Properties.Resources.ProjectExportPathTooLong, loadedAssembly.FileName)
+					+ Environment.NewLine + Environment.NewLine
+					+ e.ToString());
+			}
 			catch (Exception e) when (!(e is OperationCanceledException))
 			{
 				statusOutput.Add("-------------");

ILSpy/TextView/DecompilerTextView.cs

@@ -1079,8 +1079,14 @@ namespace ICSharpCode.ILSpy.TextView
 					{
 						bool originalProjectFormatSetting = context.Options.DecompilerSettings.UseSdkStyleProjectFormat;
 						context.Options.EscapeInvalidIdentifiers = true;
+						AvalonEditTextOutput output = new AvalonEditTextOutput {
+							EnableHyperlinks = true,
+							Title = string.Join(", ", context.TreeNodes.Select(n => n.Text))
+						};
 						Stopwatch stopwatch = new Stopwatch();
 						stopwatch.Start();
+						try
+						{
 							using (StreamWriter w = new StreamWriter(fileName))
 							{
 								try
@@ -1093,12 +1099,20 @@ namespace ICSharpCode.ILSpy.TextView
 									w.WriteLine(Properties.Resources.DecompilationWasCancelled);
 									throw;
 								}
+								catch (PathTooLongException pathTooLong) when (context.Options.SaveAsProjectDirectory != null)
+								{
+									output.WriteLine(Properties.Resources.ProjectExportPathTooLong, string.Join(", ", context.TreeNodes.Select(n => n.Text)));
+									output.WriteLine();
+									output.WriteLine(pathTooLong.ToString());
+									tcs.SetResult(output);
+									return;
+								}
+							}
 						}
+						finally
+						{
 							stopwatch.Stop();
-						AvalonEditTextOutput output = new AvalonEditTextOutput {
-							EnableHyperlinks = true,
-							Title = string.Join(", ", context.TreeNodes.Select(n => n.Text))
-						};
+						}
 
 						output.WriteLine(Properties.Resources.DecompilationCompleteInF1Seconds, stopwatch.Elapsed.TotalSeconds);
 						if (context.Options.SaveAsProjectDirectory != null)
@@ -1106,9 +1120,13 @@ namespace ICSharpCode.ILSpy.TextView
 							output.WriteLine();
 							bool useSdkStyleProjectFormat = context.Options.DecompilerSettings.UseSdkStyleProjectFormat;
 							if (useSdkStyleProjectFormat)
+							{
 								output.WriteLine(Properties.Resources.ProjectExportFormatSDKHint);
+							}
 							else
+							{
 								output.WriteLine(Properties.Resources.ProjectExportFormatNonSDKHint);
+							}
 							output.WriteLine(Properties.Resources.ProjectExportFormatChangeSettingHint);
 							if (originalProjectFormatSetting != useSdkStyleProjectFormat)
 							{

ILSpy/TreeNodes/AssemblyTreeNode.cs

@@ -342,11 +342,11 @@ namespace ICSharpCode.ILSpy.TreeNodes
 			{
 				HandleException(badImage, "This file does not contain a managed assembly.");
 			}
-			catch (FileNotFoundException fileNotFound)
+			catch (FileNotFoundException fileNotFound) when (options.SaveAsProjectDirectory == null)
 			{
 				HandleException(fileNotFound, "The file was not found.");
 			}
-			catch (DirectoryNotFoundException dirNotFound)
+			catch (DirectoryNotFoundException dirNotFound) when (options.SaveAsProjectDirectory == null)
 			{
 				HandleException(dirNotFound, "The directory was not found.");
 			}

ILSpy/app.manifest

@@ -56,7 +56,7 @@
 			<dpiAware xmlns="http://schemas.microsoft.com/SMI/2005/WindowsSettings">True</dpiAware>
 
 			<!-- Enable long path support: https://blogs.msdn.microsoft.com/jeremykuhne/2016/07/30/net-4-6-2-and-long-paths-on-windows-10/ -->
-      <longPathAware xmlns="http://schemas.microsoft.com/SMI/2016/WindowsSettings">true</longPathAware>
+			<longPathAware xmlns="http://schemas.microsoft.com/SMI/2016/WindowsSettings">True</longPathAware>
 		</windowsSettings>
 	</application>