Merge pull request #359 from dotnet/copilot/fix-emulator-boot-error

simonrozsival · web-flow · commit 482a9bbeb5e8 · 2026-05-08T11:30:39.000+02:00
Handle InvalidOperationException in emulator boot and improve Process disposal
diff --git a/src/Xamarin.Android.Tools.AndroidSdk/Runners/EmulatorRunner.cs b/src/Xamarin.Android.Tools.AndroidSdk/Runners/EmulatorRunner.cs
@@ -85,7 +85,10 @@ public Process LaunchEmulator (string avdName, bool coldBoot = false, List<strin
 				logger.Invoke (TraceLevel.Warning, $"[emulator] {e.Data}");
 		};
 
-		process.Start ();
+		if (!process.Start ()) {
+			process.Dispose ();
+			throw new InvalidOperationException ($"Failed to start emulator process '{emulatorPath}'.");
+		}
 
 		// Drain redirected streams asynchronously to prevent pipe buffer deadlocks
 		process.BeginOutputReadLine ();
@@ -209,51 +212,59 @@ public async Task<EmulatorBootResult> BootEmulatorAsync (
 		// code 0 immediately. The real emulator continues as a separate process and
 		// will eventually appear in 'adb devices'. We only treat non-zero exit codes
 		// as immediate failures; exit code 0 means we continue polling.
-		try {
-			string? newSerial = null;
-			bool processExitedWithZero = false;
-			while (newSerial == null) {
-				timeoutCts.Token.ThrowIfCancellationRequested ();
-
-				// Detect early process exit for fast failure
-				if (emulatorProcess.HasExited && !processExitedWithZero) {
-					if (emulatorProcess.ExitCode != 0) {
-						emulatorProcess.Dispose ();
+		//
+		// Dispose the Process handle when done &mdash; the emulator process keeps running.
+		using (emulatorProcess) {
+			try {
+				string? newSerial = null;
+				bool processExitedWithZero = false;
+				while (newSerial == null) {
+					timeoutCts.Token.ThrowIfCancellationRequested ();
+
+					// Detect early process exit for fast failure.
+					// Guard against InvalidOperationException in case no OS process
+					// is associated with the object (e.g. broken emulator binary).
+					try {
+						if (emulatorProcess.HasExited && !processExitedWithZero) {
+							if (emulatorProcess.ExitCode != 0) {
+								return new EmulatorBootResult {
+									Success = false,
+									ErrorKind = EmulatorBootErrorKind.LaunchFailed,
+									ErrorMessage = $"Emulator process for '{deviceOrAvdName}' exited with code {emulatorProcess.ExitCode} before becoming available.",
+								};
+							}
+							// Exit code 0: emulator likely forked (common on macOS).
+							// The real emulator runs as a separate process &mdash; keep polling.
+							logger.Invoke (TraceLevel.Verbose, $"Emulator launcher process exited with code 0 (likely forked). Continuing to poll adb devices.");
+							processExitedWithZero = true;
+						}
+					} catch (InvalidOperationException ex) {
 						return new EmulatorBootResult {
 							Success = false,
 							ErrorKind = EmulatorBootErrorKind.LaunchFailed,
-							ErrorMessage = $"Emulator process for '{deviceOrAvdName}' exited with code {emulatorProcess.ExitCode} before becoming available.",
+							ErrorMessage = $"Emulator process for '{deviceOrAvdName}' is no longer available: {ex.Message}",
 						};
 					}
-					// Exit code 0: emulator likely forked (common on macOS).
-					// The real emulator runs as a separate process &mdash; keep polling.
-					logger.Invoke (TraceLevel.Verbose, $"Emulator launcher process exited with code 0 (likely forked). Continuing to poll adb devices.");
-					processExitedWithZero = true;
-				}
-
-				await Task.Delay (options.PollInterval, timeoutCts.Token).ConfigureAwait (false);
 
-				devices = await adbRunner.ListDevicesAsync (timeoutCts.Token).ConfigureAwait (false);
-				newSerial = FindRunningAvdSerial (devices, deviceOrAvdName);
-			}
+					await Task.Delay (options.PollInterval, timeoutCts.Token).ConfigureAwait (false);
 
-			logger.Invoke (TraceLevel.Info, $"Emulator appeared as '{newSerial}', waiting for full boot...");
-			var result = await WaitForFullBootAsync (adbRunner, newSerial, options, timeoutCts.Token).ConfigureAwait (false);
+					devices = await adbRunner.ListDevicesAsync (timeoutCts.Token).ConfigureAwait (false);
+					newSerial = FindRunningAvdSerial (devices, deviceOrAvdName);
+				}
 
-			// Release the Process handle &mdash; the emulator process itself keeps running.
-			// We no longer need stdout/stderr forwarding since boot is complete.
-			emulatorProcess.Dispose ();
-			return result;
-		} catch (OperationCanceledException) when (!cancellationToken.IsCancellationRequested) {
-			TryKillProcess (emulatorProcess);
-			return new EmulatorBootResult {
-				Success = false,
-				ErrorKind = EmulatorBootErrorKind.Timeout,
-				ErrorMessage = $"Timed out waiting for emulator '{deviceOrAvdName}' to boot within {options.BootTimeout.TotalSeconds}s.",
-			};
-		} catch {
-			TryKillProcess (emulatorProcess);
-			throw;
+				logger.Invoke (TraceLevel.Info, $"Emulator appeared as '{newSerial}', waiting for full boot...");
+				return await WaitForFullBootAsync (adbRunner, newSerial, options, timeoutCts.Token).ConfigureAwait (false);
+			} catch (OperationCanceledException) when (!cancellationToken.IsCancellationRequested) {
+				TryKillProcess (emulatorProcess);
+				return new EmulatorBootResult {
+					Success = false,
+					ErrorKind = EmulatorBootErrorKind.Timeout,
+					ErrorMessage = $"Timed out waiting for emulator '{deviceOrAvdName}' to boot within {options.BootTimeout.TotalSeconds}s.",
+				};
+			} catch {
+				TryKillProcess (emulatorProcess);
+				throw;
+			}
 		}
 	}
 
@@ -276,8 +287,6 @@ void TryKillProcess (Process process)
 		} catch (Exception ex) {
 			// Best-effort: process may have already exited
 			logger.Invoke (TraceLevel.Verbose, $"Failed to stop emulator process: {ex.Message}");
-		} finally {
-			process.Dispose ();
 		}
 	}
 
diff --git a/tests/Xamarin.Android.Tools.AndroidSdk-Tests/EmulatorRunnerTests.cs b/tests/Xamarin.Android.Tools.AndroidSdk-Tests/EmulatorRunnerTests.cs
@@ -480,6 +480,38 @@ public void BootEmulatorAsync_EmptyDeviceName_Throws ()
 			runner.BootEmulatorAsync ("", mockAdb));
 	}
 
+	[Test]
+	public async Task InvalidEmulatorBinary_ReturnsLaunchFailed ()
+	{
+		var (tempDir, emuPath) = CreateFakeEmulatorSdk ();
+
+		// Overwrite with a script that exits immediately with error code 1
+		if (OS.IsWindows) {
+			File.WriteAllText (emuPath, "@echo off\r\nexit /b 1\r\n");
+		} else {
+			File.WriteAllText (emuPath, "#!/bin/sh\nexit 1\n");
+		}
+
+		try {
+			var devices = new List<AdbDeviceInfo> ();
+			var mockAdb = new MockAdbRunner (devices);
+
+			var runner = new EmulatorRunner (emuPath);
+			var options = new EmulatorBootOptions {
+				BootTimeout = TimeSpan.FromSeconds (5),
+				PollInterval = TimeSpan.FromMilliseconds (50),
+			};
+
+			var result = await runner.BootEmulatorAsync ("Test_AVD", mockAdb, options);
+
+			Assert.IsFalse (result.Success);
+			Assert.AreEqual (EmulatorBootErrorKind.LaunchFailed, result.ErrorKind);
+			Assert.That (result.ErrorMessage, Does.Contain ("exited with code"));
+		} finally {
+			Directory.Delete (tempDir, true);
+		}
+	}
+
 	// --- Helpers ---
 
 	static (string tempDir, string emulatorPath) CreateFakeEmulatorSdk ()
