Stream logs from devicectl and lldb (flutter#173724)

When debugging with `devicectl` and `lldb` (exclusive to Xcode 26+),
stream logs from both processes instead of using `idevicesyslog`, which
does not work with Xcode 26.

Fixes flutter#173365.

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Author: vashworth

packages/flutter_tools/lib/src/ios/core_devices.dart

@@ -2,6 +2,9 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+/// @docImport '../resident_runner.dart';
+library;
+
 import 'dart:async';
 
 import 'package:meta/meta.dart';
@@ -28,6 +31,7 @@ import '../device_vm_service_discovery_for_attach.dart';
 import '../features.dart';
 import '../globals.dart' as globals;
 import '../macos/xcdevice.dart';
+import '../macos/xcode.dart';
 import '../mdns_discovery.dart';
 import '../project.dart';
 import '../protocol_discovery.dart';
@@ -37,6 +41,7 @@ import 'core_devices.dart';
 import 'ios_deploy.dart';
 import 'ios_workflow.dart';
 import 'iproxy.dart';
+import 'lldb.dart';
 import 'mac.dart';
 import 'xcode_build_settings.dart';
 import 'xcode_debug.dart';
@@ -414,8 +419,11 @@ class IOSDevice extends Device {
     int installationResult;
     try {
       if (isCoreDevice) {
-        installationResult =
-            await _coreDeviceControl.installApp(deviceId: id, bundlePath: bundle.path) ? 0 : 1;
+        final (bool installSuccess, _) = await _coreDeviceControl.installApp(
+          deviceId: id,
+          bundlePath: bundle.path,
+        );
+        installationResult = installSuccess ? 0 : 1;
       } else {
         installationResult = await _iosDeploy.installApp(
           deviceId: id,
@@ -964,7 +972,7 @@ class IOSDevice extends Device {
       // Release mode
 
       // Install app to device
-      final bool installSuccess = await _coreDeviceControl.installApp(
+      final (bool installSuccess, _) = await _coreDeviceControl.installApp(
         deviceId: id,
         bundlePath: package.deviceBundlePath,
       );
@@ -991,6 +999,14 @@ class IOSDevice extends Device {
     final Version? xcodeVersion = globals.xcode?.currentVersion;
     final bool lldbFeatureEnabled = featureFlags.isLLDBDebuggingEnabled;
     if (xcodeVersion != null && xcodeVersion.major >= 26 && lldbFeatureEnabled) {
+      final DeviceLogReader deviceLogReader = getLogReader(
+        app: package,
+        usingCISystem: debuggingOptions.usingCISystem,
+      );
+      if (deviceLogReader is IOSDeviceLogReader) {
+        await deviceLogReader.listenToCoreDeviceLauncher(_coreDeviceLauncher);
+      }
+
       final bool launchSuccess = await _coreDeviceLauncher.launchAppWithLLDBDebugger(
         deviceId: id,
         bundlePath: package.deviceBundlePath,
@@ -1138,6 +1154,7 @@ class IOSDevice extends Device {
         app: app,
         iMobileDevice: _iMobileDevice,
         usingCISystem: usingCISystem,
+        xcode: globals.xcode,
       ),
     );
   }
@@ -1291,8 +1308,21 @@ String decodeSyslog(String line) {
   }
 }
 
+/// Listens to multiple logging sources to get the logs from the physical iOS device.
+///
+/// Potential logging sources include:
+///   * `idevicesyslog`
+///   * `ios-deploy`
+///   * `devicectl` and `lldb`
+///   * Unified Logging (Dart VM)
+///
+/// Not all logging sources work on all devices. See [logSources] for limitations.
+///
+/// Logs are added to the [linesController] and consumed through the [logLines] stream by
+/// [FlutterDevice.startEchoingDeviceLog].
 class IOSDeviceLogReader extends DeviceLogReader {
   IOSDeviceLogReader._(
+    this._xcode,
     this._iMobileDevice,
     this._majorSdkVersion,
     this._deviceId,
@@ -1313,10 +1343,12 @@ class IOSDeviceLogReader extends DeviceLogReader {
     required IOSDevice device,
     IOSApp? app,
     required IMobileDevice iMobileDevice,
+    required Xcode? xcode,
     bool usingCISystem = false,
   }) {
     final String appName = app?.name?.replaceAll('.app', '') ?? '';
     return IOSDeviceLogReader._(
+      xcode,
       iMobileDevice,
       device.majorSdkVersion,
       device.id,
@@ -1331,6 +1363,7 @@ class IOSDeviceLogReader extends DeviceLogReader {
   /// Create an [IOSDeviceLogReader] for testing.
   factory IOSDeviceLogReader.test({
     required IMobileDevice iMobileDevice,
+    required Xcode? xcode,
     bool useSyslog = true,
     bool usingCISystem = false,
     int? majorSdkVersion,
@@ -1339,6 +1372,7 @@ class IOSDeviceLogReader extends DeviceLogReader {
   }) {
     final int sdkVersion = majorSdkVersion ?? (useSyslog ? 12 : 13);
     return IOSDeviceLogReader._(
+      xcode,
       iMobileDevice,
       sdkVersion,
       '1234',
@@ -1357,6 +1391,7 @@ class IOSDeviceLogReader extends DeviceLogReader {
   final bool _isWirelesslyConnected;
   final bool _isCoreDevice;
   final IMobileDevice _iMobileDevice;
+  final Xcode? _xcode;
   final bool _usingCISystem;
 
   // Matches a syslog line from the runner.
@@ -1448,6 +1483,15 @@ class IOSDeviceLogReader extends DeviceLogReader {
   @override
   Stream<String> get logLines => linesController.stream;
 
+  final _coreDeviceLoggingSource = CoreDeviceLoggingSource();
+  Future<void> listenToCoreDeviceLauncher(IOSCoreDeviceLauncher launcher) async {
+    if (!useCoreDeviceLogging) {
+      return;
+    }
+    _coreDeviceLoggingSource.coreDeviceLauncher = launcher;
+    await _coreDeviceLoggingSource.listenToLogs(addToLinesController, linesController);
+  }
+
   FlutterVmService? _connectedVmService;
 
   @override
@@ -1469,6 +1513,15 @@ class IOSDeviceLogReader extends DeviceLogReader {
     // Also, `idevicesyslog` does not work with iOS 17 wireless devices, so use the
     // Dart VM for wireless devices.
     if (_isCoreDevice) {
+      // `idevicesyslog` stopped working with at least Xcode 26 (may have been before).
+      // Instead, use logging from `devicectl` and `lldb`.
+      final Version? xcodeVersion = _xcode?.currentVersion;
+      if (xcodeVersion != null && xcodeVersion.major >= 26) {
+        return _IOSDeviceLogSources(
+          primarySource: IOSDeviceLogSource.devicectlAndLldb,
+          fallbackSource: IOSDeviceLogSource.unifiedLogging,
+        );
+      }
       if (_isWirelesslyConnected) {
         return _IOSDeviceLogSources(primarySource: IOSDeviceLogSource.unifiedLogging);
       }
@@ -1536,6 +1589,13 @@ class IOSDeviceLogReader extends DeviceLogReader {
         logSources.fallbackSource == IOSDeviceLogSource.iosDeploy;
   }
 
+  /// Whether `devicectl` and `lldb` are used as the primary or fallback source for device logs.
+  @visibleForTesting
+  bool get useCoreDeviceLogging {
+    return logSources.primarySource == IOSDeviceLogSource.devicectlAndLldb ||
+        logSources.fallbackSource == IOSDeviceLogSource.devicectlAndLldb;
+  }
+
   /// Listen to Dart VM for logs on iOS 13 or greater.
   Future<void> _listenToUnifiedLoggingEvents(FlutterVmService connectedVmService) async {
     if (!useUnifiedLogging) {
@@ -1671,6 +1731,7 @@ class IOSDeviceLogReader extends DeviceLogReader {
     }
     idevicesyslogProcess?.kill();
     _iosDeployDebugger?.detach();
+    _coreDeviceLoggingSource.dispose();
   }
 }
 
@@ -1683,6 +1744,9 @@ enum IOSDeviceLogSource {
 
   /// Gets logs from the Dart VM Service.
   unifiedLogging,
+
+  /// Gets logs from `devicectl` and `lldb`
+  devicectlAndLldb,
 }
 
 class _IOSDeviceLogSources {
@@ -1692,6 +1756,62 @@ class _IOSDeviceLogSources {
   final IOSDeviceLogSource? fallbackSource;
 }
 
+@visibleForTesting
+class CoreDeviceLoggingSource {
+  IOSCoreDeviceLauncher? coreDeviceLauncher;
+  final _loggingSubscriptions = <StreamSubscription<void>>[];
+
+  Future<void> listenToLogs(
+    void Function(String, IOSDeviceLogSource) onLogMessage,
+    StreamController<String> linesController,
+  ) async {
+    final IOSCoreDeviceLogForwarder? debugger = coreDeviceLauncher?.coreDeviceLogForwarder;
+    if (debugger != null) {
+      _loggingSubscriptions.add(
+        debugger.logLines.listen(
+          (String line) =>
+              onLogMessage(_debuggerLineHandler(line), IOSDeviceLogSource.devicectlAndLldb),
+          onError: linesController.addError,
+          onDone: linesController.close,
+          cancelOnError: true,
+        ),
+      );
+    }
+
+    final LLDBLogForwarder? lldbLogForwarder = coreDeviceLauncher?.lldbLogForwarder;
+    if (lldbLogForwarder != null) {
+      _loggingSubscriptions.add(
+        lldbLogForwarder.logLines.listen(
+          (String line) =>
+              onLogMessage(_debuggerLineHandler(line), IOSDeviceLogSource.devicectlAndLldb),
+          onError: linesController.addError,
+          onDone: linesController.close,
+          cancelOnError: true,
+        ),
+      );
+    }
+  }
+
+  // Logging from native code/Flutter engine is prefixed by timestamp and process metadata:
+  // 2020-09-15 19:15:10.931434-0700 Runner[541:226276] Did finish launching.
+  // 2020-09-15 19:15:10.931434-0700 Runner[541:226276] [Category] Did finish launching.
+  //
+  // Logging from the dart code has no prefixing metadata.
+  final _debuggerLoggingRegex = RegExp(r'^\S* \S* \S*\[[0-9:]*] (.*)');
+
+  // Strip off the logging metadata (leave the category), or just echo the line.
+  String _debuggerLineHandler(String line) =>
+      _debuggerLoggingRegex.firstMatch(line)?.group(1) ?? line;
+
+  void dispose() {
+    for (final StreamSubscription<void> loggingSubscription in _loggingSubscriptions) {
+      loggingSubscription.cancel();
+    }
+    coreDeviceLauncher?.lldbLogForwarder.exit();
+    coreDeviceLauncher?.coreDeviceLogForwarder.exit();
+  }
+}
+
 /// A [DevicePortForwarder] specialized for iOS usage with iproxy.
 class IOSDevicePortForwarder extends DevicePortForwarder {
   /// Create a new [IOSDevicePortForwarder].