Launch emulator in signal-isolated process on Unix to survive Ctrl+C

src/Xamarin.Android.Tools.AndroidSdk/Runners/EmulatorRunner.cs

@@ -6,6 +6,7 @@
 using System.Diagnostics;
 using System.IO;
 using System.Linq;
+using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
 
@@ -57,7 +58,23 @@ public Process LaunchEmulator (string avdName, bool coldBoot = false, List<strin
 		if (additionalArgs != null)
 			args.AddRange (additionalArgs);
 
-		var psi = ProcessUtils.CreateProcessStartInfo (emulatorPath, args.ToArray ());
+		ProcessStartInfo psi;
+		if (OS.IsWindows) {
+			psi = ProcessUtils.CreateProcessStartInfo (emulatorPath, args.ToArray ());
+		} else {
+			// On Unix, launch through a shell that ignores SIGINT before exec'ing
+			// the emulator. This prevents Ctrl+C in the parent terminal from killing
+			// the emulator process. 'trap "" INT' sets SIGINT to SIG_IGN, which POSIX
+			// guarantees is preserved across exec:
+			// https://pubs.opengroup.org/onlinepubs/9699919799/functions/exec.html
+			var shellCmd = new StringBuilder ("trap '' INT; exec ");
+			shellCmd.Append (ShellQuote (emulatorPath));
+			foreach (var arg in args) {
+				shellCmd.Append (' ');
+				shellCmd.Append (ShellQuote (arg));
+			}
+			psi = ProcessUtils.CreateProcessStartInfo ("/bin/sh", "-c", shellCmd.ToString ());
+		}
 
 		if (environmentVariables != null) {
 			foreach (var kvp in environmentVariables)
@@ -317,5 +334,9 @@ async Task<EmulatorBootResult> WaitForFullBootAsync (
 		cancellationToken.ThrowIfCancellationRequested ();
 		return new EmulatorBootResult { Success = false, ErrorKind = EmulatorBootErrorKind.Cancelled, ErrorMessage = "Boot cancelled." };
 	}
+
+	/// Quotes a string for safe use in a POSIX shell command.
+	/// Wraps in single quotes and escapes embedded single quotes.
+	static string ShellQuote (string arg) => "'" + arg.Replace ("'", "'\\''") + "'";
 }
 

tests/Xamarin.Android.Tools.AndroidSdk-Tests/EmulatorRunnerTests.cs

@@ -97,8 +97,6 @@ public void LaunchEmulator_ThrowsOnWhitespaceAvdName ()
 		Assert.Throws<ArgumentException> (() => runner.LaunchEmulator ("   "));
 	}
 
-	// --- BootEmulatorAsync tests (ported from dotnet/android BootAndroidEmulatorTests) ---
-
 	[Test]
 	public async Task AlreadyOnlineDevice_PassesThrough ()
 	{
@@ -205,7 +203,7 @@ public async Task LaunchFailure_ReturnsError ()
 		var result = await runner.BootEmulatorAsync ("Pixel_7_API_35", mockAdb, options);
 
 		Assert.IsFalse (result.Success);
-		Assert.That (result.ErrorMessage, Does.Contain ("Failed to launch"));
+		Assert.AreEqual (EmulatorBootErrorKind.LaunchFailed, result.ErrorKind);
 	}
 
 	[Test]
@@ -295,8 +293,6 @@ public async Task MultipleEmulators_FindsCorrectAvd ()
 		Assert.AreEqual ("emulator-5556", result.Serial, "Should find the correct AVD among multiple emulators");
 	}
 
-	// --- Tests ported from dotnet/android BootAndroidEmulatorTests ---
-
 	[Test]
 	public async Task AlreadyOnlinePhysicalDevice_PassesThrough ()
 	{
@@ -480,6 +476,36 @@ public void BootEmulatorAsync_EmptyDeviceName_Throws ()
 			runner.BootEmulatorAsync ("", mockAdb));
 	}
 
+	[Test]
+	[Platform ("Linux,MacOsX")]
+	public void LaunchEmulator_SurvivesSigint ()
+	{
+		var (tempDir, emuPath) = CreateFakeEmulatorSdk ();
+		Process? process = null;
+		try {
+			var runner = new EmulatorRunner (emuPath);
+			process = runner.LaunchEmulator ("TestAVD");
+
+			Assert.IsFalse (process.HasExited, "Process should be running after launch");
+
+			// Send SIGINT to the emulator process
+			var killPsi = ProcessUtils.CreateProcessStartInfo ("kill", "-INT", process.Id.ToString ());
+			using var kill = new Process { StartInfo = killPsi };
+			kill.Start ();
+			Assert.IsTrue (kill.WaitForExit (5000), "kill command should exit promptly");
+			Assert.AreEqual (0, kill.ExitCode, "kill -INT should succeed");
+
+			// Give the signal a moment to be delivered
+			Thread.Sleep (500);
+
+			Assert.IsFalse (process.HasExited, "Emulator process should survive SIGINT");
+		} finally {
+			try { process?.Kill (); process?.WaitForExit (5000); } catch { }
+			process?.Dispose ();
+			Directory.Delete (tempDir, true);
+		}
+	}
+
 	[Test]
 	public async Task InvalidEmulatorBinary_ReturnsLaunchFailed ()
 	{
@@ -512,6 +538,35 @@ public async Task InvalidEmulatorBinary_ReturnsLaunchFailed ()
 		}
 	}
 
+	[Test]
+	[Platform ("Linux,MacOsX")]
+	public void ShellQuote_EscapesSingleQuotes ()
+	{
+		var tempDir = Path.Combine (Path.GetTempPath (), $"emu-quote-test-{Path.GetRandomFileName ()}");
+		var emulatorDir = Path.Combine (tempDir, "emu'dir");
+		Directory.CreateDirectory (emulatorDir);
+
+		var emuPath = Path.Combine (emulatorDir, "emulator");
+		File.WriteAllText (emuPath, "#!/bin/sh\nsleep 60\n");
+		var psi = ProcessUtils.CreateProcessStartInfo ("chmod", "+x", emuPath);
+		using (var chmod = new Process { StartInfo = psi }) {
+			chmod.Start ();
+			Assert.IsTrue (chmod.WaitForExit (5000), "chmod should exit promptly");
+		}
+
+		Process? process = null;
+		try {
+			var runner = new EmulatorRunner (emuPath);
+			process = runner.LaunchEmulator ("TestAVD");
+
+			Assert.IsFalse (process.HasExited, "Process should start even with single-quote in path");
+		} finally {
+			try { process?.Kill (); process?.WaitForExit (5000); } catch { }
+			process?.Dispose ();
+			Directory.Delete (tempDir, true);
+		}
+	}
+
 	// --- Helpers ---
 
 	static (string tempDir, string emulatorPath) CreateFakeEmulatorSdk ()