Implement POSIX signal handling for DevServer to fix port release issues

src/Components/WebAssembly/DevServer/src/Program.cs

@@ -1,7 +1,9 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Runtime.InteropServices;
 using Microsoft.AspNetCore.Hosting;
+using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
 using DevServerProgram = Microsoft.AspNetCore.Components.WebAssembly.DevServer.Server.Program;
 
@@ -11,7 +13,62 @@ internal sealed class Program
 {
     static int Main(string[] args)
     {
-        DevServerProgram.BuildWebHost(args).Run();
+        var host = DevServerProgram.BuildWebHost(args);
+
+        // Register POSIX signal handlers for graceful shutdown on Unix systems
+        if (OperatingSystem.IsLinux() || OperatingSystem.IsMacOS())
+        {
+            using var lifetime = new DevServerLifetime(host.Services.GetRequiredService<IHostApplicationLifetime>());
+            host.Run();
+        }
+        else
+        {
+            host.Run();
+        }
+
         return 0;
     }
 }
+
+internal sealed class DevServerLifetime : IDisposable
+{
+    private readonly IHostApplicationLifetime _applicationLifetime;
+    private readonly PosixSignalRegistration _sigIntRegistration;
+    private readonly PosixSignalRegistration _sigQuitRegistration;
+    private readonly PosixSignalRegistration _sigTermRegistration;
+
+    private bool _disposed;
+
+    public DevServerLifetime(IHostApplicationLifetime applicationLifetime)
+    {
+        _applicationLifetime = applicationLifetime;
+
+        Action<PosixSignalContext> handler = HandlePosixSignal;
+        _sigIntRegistration = PosixSignalRegistration.Create(PosixSignal.SIGINT, handler);
+        _sigQuitRegistration = PosixSignalRegistration.Create(PosixSignal.SIGQUIT, handler);
+        _sigTermRegistration = PosixSignalRegistration.Create(PosixSignal.SIGTERM, handler);
+    }
+
+    public void Dispose()
+    {
+        if (_disposed)
+        {
+            return;
+        }
+
+        _disposed = true;
+
+        _sigIntRegistration.Dispose();
+        _sigQuitRegistration.Dispose();
+        _sigTermRegistration.Dispose();
+    }
+
+    private void HandlePosixSignal(PosixSignalContext context)
+    {
+        // Request graceful shutdown
+        _applicationLifetime.StopApplication();
+
+        // Don't terminate the process immediately, wait for the application to exit gracefully.
+        context.Cancel = true;
+    }
+}