fix: avoid deadlock in the thread invoking the CancelKeyPress handler

Author: natemcmaster

CHANGELOG.md

@@ -2,6 +2,11 @@
 
 [See unreleased changes][unreleased].
 
+## [v2.4.2]
+* Fix [#286] - fix deadlock in CTRL+C handling on Windows
+
+[#286]: https://github.com/natemcmaster/CommandLineUtils/issues/286
+
 ## [v2.4.1]
 
 * Fix [#277] - workaround a bug in NuGet's 'deterministic packaging' feature which causes issues based on your timezone

src/CommandLineUtils/CommandLineApplication.cs

@@ -882,11 +882,12 @@ public async Task<int> ExecuteAsync(string[] args, CancellationToken cancellatio
             void cancelHandler(object o, ConsoleCancelEventArgs e)
             {
                 handlerCancellationTokenSource.Cancel();
-                handlerCompleted.Wait();
+                // Stops the process from exiting forcefully
+                e.Cancel = true;
             }
 
 #if !NETSTANDARD1_6
-            void unloadingHandler(object o, EventArgs e)
+            void processExitHandler(object o, EventArgs e)
             {
                 handlerCancellationTokenSource.Cancel();
                 handlerCompleted.Wait();
@@ -899,7 +900,7 @@ void unloadingHandler(object o, EventArgs e)
                 _context.Console.CancelKeyPress += cancelHandler;
 #if !NETSTANDARD1_6
                 // blocks .NET's process unloading from completing until after async completions are done
-                AppDomain.CurrentDomain.DomainUnload += unloadingHandler;
+                AppDomain.CurrentDomain.ProcessExit += processExitHandler;
 #endif
 
                 return await command._handler(handlerCancellationTokenSource.Token);
@@ -912,7 +913,7 @@ void unloadingHandler(object o, EventArgs e)
             {
                 _context.Console.CancelKeyPress -= cancelHandler;
 #if !NETSTANDARD1_6
-                AppDomain.CurrentDomain.DomainUnload -= unloadingHandler;
+                AppDomain.CurrentDomain.ProcessExit -= processExitHandler;
 #endif
                 handlerCompleted.Set();
             }

src/CommandLineUtils/releasenotes.props

@@ -1,6 +1,6 @@
 <Project>
   <PropertyGroup>
-    <PackageReleaseNotes Condition="'$(VersionPrefix)' == '2.4.1'">
+    <PackageReleaseNotes Condition="$(VersionPrefix.StartsWith('2.4.'))">
 Features and bug fixes by some awesome contributors:
 
 * @IanG: Attributes for files and directories that must not exist
@@ -16,6 +16,15 @@ Other things I fixed:
 * Add async methods that accept cancellation tokens
 * Handle CTRL+C by default
 * Support calling CommandLineApplication.Execute multiple times
+    </PackageReleaseNotes>
+    <PackageReleaseNotes Condition="'$(VersionPrefix)' == '2.4.2'">
+$(PackageReleaseNotes)
+
+2.4.2 hot fix:
+* Fix deadlock in CTRL+C handling on Windows
+    </PackageReleaseNotes>
+    <PackageReleaseNotes Condition="'$(VersionPrefix)' == '2.4.1'">
+$(PackageReleaseNotes)
 
 2.4.1 hot fix:
 * Workaround a bizarre NuGet bug which causes problems for users in Europe and Asia

test/CommandLineUtils.Tests/Utilities/TestConsole.cs

@@ -3,6 +3,8 @@
 
 using System;
 using System.IO;
+using System.Linq;
+using System.Reflection;
 using Xunit.Abstractions;
 
 namespace McMaster.Extensions.CommandLineUtils.Tests
@@ -38,7 +40,12 @@ public void ResetColor()
 
         public void RaiseCancelKeyPress()
         {
-            CancelKeyPress?.Invoke(this, default);
+            // See https://github.com/dotnet/corefx/blob/f2292af3a1794378339d6f5c8adcc0f2019a2cf9/src/System.Console/src/System/ConsoleCancelEventArgs.cs#L14
+            var eventArgs = typeof(ConsoleCancelEventArgs)
+                .GetConstructors(BindingFlags.NonPublic | BindingFlags.Instance)
+                .First()
+                .Invoke(new object[] { ConsoleSpecialKey.ControlC });
+            CancelKeyPress?.Invoke(this, (ConsoleCancelEventArgs)eventArgs);
         }
     }
 }