github-label-notifier/symbolizer/lib/parser.dart - dart_ci - Git at Google

 // Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.

 /// Logic for extracting crashes from text.
 library symbolizer.parser;

 import 'package:meta/meta.dart';

 import 'package:symbolizer/model.dart';

 /// Returns [true] if the given text is likely to contain a crash.
 bool containsCrash(String text) {
   return text.contains(_CrashExtractor._androidCrashMarker) ||
       text.contains(_CrashExtractor._iosCrashMarker);
 }

 /// Extract all crashes from the given [text] using [overrides].
 List<Crash> extractCrashes(String text, {SymbolizationOverrides overrides}) =>
     _CrashExtractor(text: text, overrides: overrides).crashes;

 class _CrashExtractor {
   final List<String> lines;
   final SymbolizationOverrides overrides;

   final List<Crash> crashes = <Crash>[];

   int lineNo = 0;

   String os;
   String arch;
   String mode;
   String format;
   List<CrashFrame> frames;

   RegExp logLinePattern;
   bool collectingFrames = false;
   int androidMajorVersion;

   _CrashExtractor({@required String text, this.overrides})
       : lines = text.split(_lineEnding) {
     if (overrides?.format == 'internal' && overrides?.os != null) {
       parseAsCustomBacktrace(_internalFramePattern, overrides.os);
     } else if (overrides?.force == true && overrides.os == 'ios') {
       parseAsIosBacktrace();
     } else {
       processLines();
     }
   }

   // 0x00000001003cb6b4(ios_prod_global -main.m:35)main
   // 0x000000010539eb10(Flutter + 0x00312b10)
   final _internalFramePattern = RegExp(
       r'(?<pc>0x[a-f0-9]+)\s*\((?<binary>\S+)\s+(\+\s+(?<offset>0x[a-f0-9]+)|(?<location>[^+][^\)]+))\)(?<symbol>.*)');

   /// Extract only stack traces from the text which match the given regexp.
   /// Used when 'internal' override is in effect.
   void parseAsCustomBacktrace(RegExp pattern, String os) {
     for (; lineNo < lines.length; lineNo++) {
       final line = lines[lineNo];
       final frameMatch = pattern.firstMatch(line);

       if (frameMatch == null) {
         if (collectingFrames) {
           endCrash();
         }
         continue;
       }

       if (!collectingFrames) {
         startCrash(os);
         mode = 'release';
         format = 'custom';
         collectingFrames = true;
       }

       frames.add(CrashFrame.custom(
         no: frames.length.toString().padLeft(2, '0'),
         binary: frameMatch.namedGroup('binary'),
         pc: int.parse(frameMatch.namedGroup('pc')),
         symbol: frameMatch.namedGroup('symbol'),
         offset: frameMatch.namedGroup('offset') != null
             ? int.parse(frameMatch.namedGroup('offset'))
             : null,
         location: frameMatch.namedGroup('location'),
       ));
     }
     endCrash();
   }

   /// Extract only iOS like stack traces from the text. Used when
   /// 'force ios' override is in effect.
   void parseAsIosBacktrace() {
     for (; lineNo < lines.length; lineNo++) {
       final line = lines[lineNo];

       final frame = parseIosFrame(line);

       if (frame == null) {
         if (collectingFrames) {
           endCrash();
         }
         continue;
       }

       // Allow frames that miss offset and instead contain `(Missing)`
       // instead of symbol name. This can happen in crashalytics output.
       if (frame.offset == null &&
           frame.symbol != CrashFrame.crashalyticsMissingSymbol) {
         continue;
       }

       if (!collectingFrames) {
         startCrash('ios');
         mode = 'release';
         collectingFrames = true;
       }

       frames.add(frame);
     }
     endCrash();
   }

   IosCrashFrame parseIosFrame(String line) {
     final frameMatch = _iosFramePattern.firstMatch(line);
     if (frameMatch == null) {
       return null;
     }
     var rest = frameMatch.namedGroup('rest').trim();
     var location = '';
     if (rest.endsWith(')')) {
       final open = rest.lastIndexOf('(');
       if (open > 0) {
         location = rest.substring(open + 1, rest.length - 2);
         rest = rest.substring(0, open).trim();
       }
     }
     final offsetMatch = _offsetSuffixPattern.firstMatch(rest);
     String symbol;
     int offset;
     if (offsetMatch != null) {
       offset = int.parse(offsetMatch.namedGroup('offset'));
       symbol = offsetMatch.namedGroup('symbol').trim();
     } else {
       symbol = rest.trim();
     }

     return CrashFrame.ios(
       no: frameMatch.namedGroup('no'),
       binary: frameMatch.namedGroup('binary'),
       pc: int.parse(frameMatch.namedGroup('pc')),
       symbol: symbol,
       offset: offset,
       location: location,
     );
   }

   void processLines() {
     for (; lineNo < lines.length; lineNo++) {
       var line = lines[lineNo];

       // Strip markdown quote.
       if (line.startsWith('> ')) {
         line = line.substring(2);
       }

       // If we have an indication that we are processing raw logcat or flutter
       // verbose output then strip the prefix characteristic for those log
       // types.
       if (logLinePattern != null) {
         final m = logLinePattern.firstMatch(line);
         if (m != null) {
           line = m.namedGroup('rest');
         } else {
           // No longer in the raw log output. If we started collecting a crash
           // flush it and continue handling the line.
           endCrash();
         }
       }

       if (line.isEmpty) {
         continue;
       }

       // First check for crash markers.
       if (line.contains(_androidCrashMarker)) {
         // Start of the Android crash.
         startCrash('android');
         continue;
       }

       if (line.contains(_iosCrashMarker)) {
         // Start of the iOS crash.
         startCrash('ios');
         continue;
       }

       final dartvmCrashMatch = _dartvmCrashMarker.firstMatch(line);
       if (dartvmCrashMatch != null) {
         startCrash(dartvmCrashMatch.namedGroup('os'));
         format = 'dartvm';
         arch = dartvmCrashMatch.namedGroup('arch');
         if (arch == 'ia32') {
           arch = 'x86';
         }
         continue;
       }

       if (format == 'dartvm') {
         if (line.contains(_endOfDumpStackTracePattern)) {
           endCrash();
           continue;
         }

         final frameMatch = _dartvmFramePattern.firstMatch(line);
         if (frameMatch != null) {
           frames.add(CrashFrame.dartvm(
             pc: int.parse(frameMatch.namedGroup('pc')),
             binary: frameMatch.namedGroup('binary'),
             offset: int.parse(frameMatch.namedGroup('offset')),
           ));
         }
       }

       if (os == 'android') {
         // Handle `Build fingerprint: '...'` line.
         final androidVersion = _androidBuildFingerprintPattern
             .firstMatch(line)
             ?.namedGroup('version');
         if (androidVersion != null) {
           androidMajorVersion = int.tryParse(androidVersion.split('.').first);
         }

         // Handle `ABI: '...'` line.
         final abiMatch = _androidAbiPattern.firstMatch(line);
         if (abiMatch != null) {
           arch = abiMatch.namedGroup('abi');
           if (arch == 'x86_64') {
             arch = 'x64';
           }
           continue;
         }

         // Handle backtrace: start.
         if (_backtraceStartPattern.hasMatch(line)) {
           collectingFrames = true;
           continue;
         }

         // If backtrace has started then process line corresponding for a frame.
         if (collectingFrames) {
           final frameMatch = _androidFramePattern.firstMatch(line);
           if (frameMatch != null) {
             final rest = frameMatch.namedGroup('rest');
             final buildIdMatch = _buildIdPattern.firstMatch(rest);
             frames.add(CrashFrame.android(
               no: frameMatch.namedGroup('no'),
               pc: int.parse(frameMatch.namedGroup('pc'), radix: 16),
               binary: frameMatch.namedGroup('binary'),
               rest: rest,
               buildId: buildIdMatch?.namedGroup('id'),
             ));
           } else {
             endCrash();
           }
         }
         continue;
       }

       if (os == 'ios') {
         // Handle EOF marking the end of crash report.
         if (line.contains(_eofPattern)) {
           endCrash();
           continue;
         }

         // Handle line that describes App.framework binary image.
         // We use it as a marker to detect release mode builds.
         if (line.contains(_appFrameworkPattern)) {
           mode = 'release';
           continue;
         }

         // Handle `Code Type: ...` line.
         final abiMatch = _iosAbiPattern.firstMatch(line);
         if (abiMatch != null) {
           arch = abiMatch.namedGroup('abi') == 'ARM-64' ? 'arm64' : 'arm32';
           continue;
         }

         // Handle `Thread ... Crashed:` line
         if (line.contains(_crashedThreadPattern)) {
           collectingFrames = true;
           continue;
         }

         if (collectingFrames) {
           final frame = parseIosFrame(line);
           if (frame != null) {
             frames.add(frame);
           } else {
             collectingFrames = false;
             // Don't flush the crash yet - we want to read report until the
             // end and check if it is a release build or not.
           }
         }

         continue;
       }
     }

     endCrash();
   }

   void startCrash(String os) {
     endCrash();
     this.os = os;
     frames = <CrashFrame>[];
     arch = mode = null;
     logLinePattern = null;
     collectingFrames = false;
     format = 'native';
     androidMajorVersion = null;
     if (os == 'android') {
       detectAndroidLogFormat();
     }
   }

   void endCrash() {
     // We are not interested in crashes where we did not collect any frames.
     if (frames != null && frames.isNotEmpty) {
       crashes.add(Crash(
         engineVariant: EngineVariant(
           os: os,
           arch: overrides?.arch ?? arch,
           mode: overrides?.mode ?? mode,
         ),
         frames: frames,
         format: format,
         androidMajorVersion: androidMajorVersion,
       ));
     }
     frames = null;
     collectingFrames = false;
     logLinePattern = null;
   }

   /// Android crashes might come from `adb logcat` or `flutter run -v`
   /// output. In which case we need to strip prefix characteristic for
   /// those.
   void detectAndroidLogFormat() {
     final line = lines[lineNo];
     if (line.contains(_flutterLogPattern)) {
       logLinePattern = _flutterLogPattern;
       guessLaunchMode();
     } else if (line.contains(_deviceLabPattern)) {
       logLinePattern = _deviceLabPattern;
       guessLaunchMode();
     } else if (line.contains(_logcatPattern)) {
       logLinePattern = _logcatPattern;
     }
   }

   void guessLaunchMode() {
     if (overrides?.mode != null) {
       return;
     }

     // Try to look backwards through log lines to determine launch mode.
     for (var i = lineNo - 1; i >= 0; i--) {
       final logLineMatch = logLinePattern.firstMatch(lines[i]);
       if (logLineMatch == null) {
         break;
       }
       final modeMatch =
           _launchModePattern.firstMatch(logLineMatch.namedGroup('rest'));
       if (modeMatch != null) {
         mode = modeMatch.namedGroup('mode');
         return;
       }
     }
   }

   static final _androidCrashMarker =
       '*** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***';

   static final _iosCrashMarker =
       RegExp(r'Incident Identifier:\s+([A-F0-9]+-?)+');

   static final _dartvmCrashMarker =
       RegExp(r'version=.*on "(?<os>android)_(?<arch>arm|arm64|ia32|x64)"\s*$');

   static final _lineEnding = RegExp(r'\r?\n');
   static final _logcatPattern = RegExp(r'^.*?:(?=$|\s)\s*(?<rest>.*)$');
   static final _flutterLogPattern =
       RegExp(r'^\s*\[\s*(\+?\s*\d+\s*(s|ms|h))?\]\s+(?<rest>.*)$');
   static final _deviceLabPattern = RegExp(
       r'(\d+-\d+-\d+T\d+:\d+:\d+.\d+: )?(stdout|stderr):\s*\[\s*(\+?\s*\d+\s*(s|ms|h))?\]\s+(?<rest>.*)');

   static final _androidAbiPattern =
       RegExp(r"^\s*ABI: '(?<abi>x86|x86_64|x64|arm|arm64)'\s*$");

   // Android Compatibility Definition mandates build fingerprint format to be:
   //
   //   $(BRAND)/$(PRODUCT)/$(DEVICE):
   //     $(VERSION.RELEASE)/$(ID)/$(VERSION.INCREMENTAL):$(TYPE)/$(TAGS)
   //
   // For our purposes we are only interested in VERSION.RELEASE component of the
   // fingerprint.
   //
   // See https://source.android.com/compatibility/11/android-11-cdd
   static final _androidBuildFingerprintPattern =
       RegExp(r"Build fingerprint: '[^:']+:(?<version>[\d\.]+)/[^']*'");
   static final _backtraceStartPattern = RegExp(r'^\s*backtrace:\s*$');
   static final _androidFramePattern = RegExp(
       r'^\s*#(?<no>\d+)\s+pc\s+(?<pc>[0-9a-f]+)\s+(?<binary>[^\s]+)(?<rest>.*)$');
   static final _buildIdPattern = RegExp(r'\(BuildId: (?<id>[0-9a-f]+)\)');
   static final _launchModePattern =
       RegExp(r'^\s*Launching .* on .* in (?<mode>debug|release|profile) mode');

   static final _eofPattern = RegExp(r'^\s*EOF\s*$');
   static final _appFrameworkPattern = RegExp(
       r'^\s*0x[a-f0-9]+\s+-\s+0x[a-f0-9]+\s+App\s+arm\w+\s+<[a-f0-9]+>\s+/var/containers');
   static final _iosAbiPattern = RegExp(r'\s*Code\s+Type:\s+(?<abi>[\-\w]+)\s+');
   static final _crashedThreadPattern = RegExp(r'^\s*Thread \d+ Crashed:');
   static final _iosFramePattern = RegExp(
       r'^\s*(?<no>\d+)\s+(?<binary>\S+)\s+(?<pc>0x[a-f0-9]+)\s+(?<rest>.*)$',
       unicode: true);
   static final _offsetSuffixPattern =
       RegExp(r'^(?<symbol>.*)\s+\+\s+(?<offset>\d+)$');

   static final _endOfDumpStackTracePattern = '-- End of DumpStackTrace';
   static final _dartvmFramePattern = RegExp(
       r'(^|\s+)pc\s+(?<pc>0x[a-f0-9]+)\s+fp\s+(?<fp>0x[a-f0-9]+)\s+(?<binary>[^\s+]+)\+(?<offset>0x[a-f0-9]+)');
 }
	// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
	// for details. All rights reserved. Use of this source code is governed by a
	// BSD-style license that can be found in the LICENSE file.

	/// Logic for extracting crashes from text.
	library symbolizer.parser;

	import 'package:meta/meta.dart';

	import 'package:symbolizer/model.dart';

	/// Returns [true] if the given text is likely to contain a crash.
	bool containsCrash(String text) {
	return text.contains(_CrashExtractor._androidCrashMarker) \|\|
	text.contains(_CrashExtractor._iosCrashMarker);
	}

	/// Extract all crashes from the given [text] using [overrides].
	List<Crash> extractCrashes(String text, {SymbolizationOverrides overrides}) =>
	_CrashExtractor(text: text, overrides: overrides).crashes;

	class _CrashExtractor {
	final List<String> lines;
	final SymbolizationOverrides overrides;

	final List<Crash> crashes = <Crash>[];

	int lineNo = 0;

	String os;
	String arch;
	String mode;
	String format;
	List<CrashFrame> frames;

	RegExp logLinePattern;
	bool collectingFrames = false;
	int androidMajorVersion;

	_CrashExtractor({@required String text, this.overrides})
	: lines = text.split(_lineEnding) {
	if (overrides?.format == 'internal' && overrides?.os != null) {
	parseAsCustomBacktrace(_internalFramePattern, overrides.os);
	} else if (overrides?.force == true && overrides.os == 'ios') {
	parseAsIosBacktrace();
	} else {
	processLines();
	}
	}

	// 0x00000001003cb6b4(ios_prod_global -main.m:35)main
	// 0x000000010539eb10(Flutter + 0x00312b10)
	final _internalFramePattern = RegExp(
	r'(?<pc>0x[a-f0-9]+)\s\((?<binary>\S+)\s+(\+\s+(?<offset>0x[a-f0-9]+)\|(?<location>[^+][^\)]+))\)(?<symbol>.)');

	/// Extract only stack traces from the text which match the given regexp.
	/// Used when 'internal' override is in effect.
	void parseAsCustomBacktrace(RegExp pattern, String os) {
	for (; lineNo < lines.length; lineNo++) {
	final line = lines[lineNo];
	final frameMatch = pattern.firstMatch(line);

	if (frameMatch == null) {
	if (collectingFrames) {
	endCrash();
	}
	continue;
	}

	if (!collectingFrames) {
	startCrash(os);
	mode = 'release';
	format = 'custom';
	collectingFrames = true;
	}

	frames.add(CrashFrame.custom(
	no: frames.length.toString().padLeft(2, '0'),
	binary: frameMatch.namedGroup('binary'),
	pc: int.parse(frameMatch.namedGroup('pc')),
	symbol: frameMatch.namedGroup('symbol'),
	offset: frameMatch.namedGroup('offset') != null
	? int.parse(frameMatch.namedGroup('offset'))
	: null,
	location: frameMatch.namedGroup('location'),
	));
	}
	endCrash();
	}

	/// Extract only iOS like stack traces from the text. Used when
	/// 'force ios' override is in effect.
	void parseAsIosBacktrace() {
	for (; lineNo < lines.length; lineNo++) {
	final line = lines[lineNo];

	final frame = parseIosFrame(line);

	if (frame == null) {
	if (collectingFrames) {
	endCrash();
	}
	continue;
	}

	// Allow frames that miss offset and instead contain `(Missing)`
	// instead of symbol name. This can happen in crashalytics output.
	if (frame.offset == null &&
	frame.symbol != CrashFrame.crashalyticsMissingSymbol) {
	continue;
	}

	if (!collectingFrames) {
	startCrash('ios');
	mode = 'release';
	collectingFrames = true;
	}

	frames.add(frame);
	}
	endCrash();
	}

	IosCrashFrame parseIosFrame(String line) {
	final frameMatch = _iosFramePattern.firstMatch(line);
	if (frameMatch == null) {
	return null;
	}
	var rest = frameMatch.namedGroup('rest').trim();
	var location = '';
	if (rest.endsWith(')')) {
	final open = rest.lastIndexOf('(');
	if (open > 0) {
	location = rest.substring(open + 1, rest.length - 2);
	rest = rest.substring(0, open).trim();
	}
	}
	final offsetMatch = _offsetSuffixPattern.firstMatch(rest);
	String symbol;
	int offset;
	if (offsetMatch != null) {
	offset = int.parse(offsetMatch.namedGroup('offset'));
	symbol = offsetMatch.namedGroup('symbol').trim();
	} else {
	symbol = rest.trim();
	}

	return CrashFrame.ios(
	no: frameMatch.namedGroup('no'),
	binary: frameMatch.namedGroup('binary'),
	pc: int.parse(frameMatch.namedGroup('pc')),
	symbol: symbol,
	offset: offset,
	location: location,
	);
	}

	void processLines() {
	for (; lineNo < lines.length; lineNo++) {
	var line = lines[lineNo];

	// Strip markdown quote.
	if (line.startsWith('> ')) {
	line = line.substring(2);
	}

	// If we have an indication that we are processing raw logcat or flutter
	// verbose output then strip the prefix characteristic for those log
	// types.
	if (logLinePattern != null) {
	final m = logLinePattern.firstMatch(line);
	if (m != null) {
	line = m.namedGroup('rest');
	} else {
	// No longer in the raw log output. If we started collecting a crash
	// flush it and continue handling the line.
	endCrash();
	}
	}

	if (line.isEmpty) {
	continue;
	}

	// First check for crash markers.
	if (line.contains(_androidCrashMarker)) {
	// Start of the Android crash.
	startCrash('android');
	continue;
	}

	if (line.contains(_iosCrashMarker)) {
	// Start of the iOS crash.
	startCrash('ios');
	continue;
	}

	final dartvmCrashMatch = _dartvmCrashMarker.firstMatch(line);
	if (dartvmCrashMatch != null) {
	startCrash(dartvmCrashMatch.namedGroup('os'));
	format = 'dartvm';
	arch = dartvmCrashMatch.namedGroup('arch');
	if (arch == 'ia32') {
	arch = 'x86';
	}
	continue;
	}

	if (format == 'dartvm') {
	if (line.contains(_endOfDumpStackTracePattern)) {
	endCrash();
	continue;
	}

	final frameMatch = _dartvmFramePattern.firstMatch(line);
	if (frameMatch != null) {
	frames.add(CrashFrame.dartvm(
	pc: int.parse(frameMatch.namedGroup('pc')),
	binary: frameMatch.namedGroup('binary'),
	offset: int.parse(frameMatch.namedGroup('offset')),
	));
	}
	}

	if (os == 'android') {
	// Handle `Build fingerprint: '...'` line.
	final androidVersion = _androidBuildFingerprintPattern
	.firstMatch(line)
	?.namedGroup('version');
	if (androidVersion != null) {
	androidMajorVersion = int.tryParse(androidVersion.split('.').first);
	}

	// Handle `ABI: '...'` line.
	final abiMatch = _androidAbiPattern.firstMatch(line);
	if (abiMatch != null) {
	arch = abiMatch.namedGroup('abi');
	if (arch == 'x86_64') {
	arch = 'x64';
	}
	continue;
	}

	// Handle backtrace: start.
	if (_backtraceStartPattern.hasMatch(line)) {
	collectingFrames = true;
	continue;
	}

	// If backtrace has started then process line corresponding for a frame.
	if (collectingFrames) {
	final frameMatch = _androidFramePattern.firstMatch(line);
	if (frameMatch != null) {
	final rest = frameMatch.namedGroup('rest');
	final buildIdMatch = _buildIdPattern.firstMatch(rest);
	frames.add(CrashFrame.android(
	no: frameMatch.namedGroup('no'),
	pc: int.parse(frameMatch.namedGroup('pc'), radix: 16),
	binary: frameMatch.namedGroup('binary'),
	rest: rest,
	buildId: buildIdMatch?.namedGroup('id'),
	));
	} else {
	endCrash();
	}
	}
	continue;
	}

	if (os == 'ios') {
	// Handle EOF marking the end of crash report.
	if (line.contains(_eofPattern)) {
	endCrash();
	continue;
	}

	// Handle line that describes App.framework binary image.
	// We use it as a marker to detect release mode builds.
	if (line.contains(_appFrameworkPattern)) {
	mode = 'release';
	continue;
	}

	// Handle `Code Type: ...` line.
	final abiMatch = _iosAbiPattern.firstMatch(line);
	if (abiMatch != null) {
	arch = abiMatch.namedGroup('abi') == 'ARM-64' ? 'arm64' : 'arm32';
	continue;
	}

	// Handle `Thread ... Crashed:` line
	if (line.contains(_crashedThreadPattern)) {
	collectingFrames = true;
	continue;
	}

	if (collectingFrames) {
	final frame = parseIosFrame(line);
	if (frame != null) {
	frames.add(frame);
	} else {
	collectingFrames = false;
	// Don't flush the crash yet - we want to read report until the
	// end and check if it is a release build or not.
	}
	}

	continue;
	}
	}

	endCrash();
	}

	void startCrash(String os) {
	endCrash();
	this.os = os;
	frames = <CrashFrame>[];
	arch = mode = null;
	logLinePattern = null;
	collectingFrames = false;
	format = 'native';
	androidMajorVersion = null;
	if (os == 'android') {
	detectAndroidLogFormat();
	}
	}

	void endCrash() {
	// We are not interested in crashes where we did not collect any frames.
	if (frames != null && frames.isNotEmpty) {
	crashes.add(Crash(
	engineVariant: EngineVariant(
	os: os,
	arch: overrides?.arch ?? arch,
	mode: overrides?.mode ?? mode,
	),
	frames: frames,
	format: format,
	androidMajorVersion: androidMajorVersion,
	));
	}
	frames = null;
	collectingFrames = false;
	logLinePattern = null;
	}

	/// Android crashes might come from `adb logcat` or `flutter run -v`
	/// output. In which case we need to strip prefix characteristic for
	/// those.
	void detectAndroidLogFormat() {
	final line = lines[lineNo];
	if (line.contains(_flutterLogPattern)) {
	logLinePattern = _flutterLogPattern;
	guessLaunchMode();
	} else if (line.contains(_deviceLabPattern)) {
	logLinePattern = _deviceLabPattern;
	guessLaunchMode();
	} else if (line.contains(_logcatPattern)) {
	logLinePattern = _logcatPattern;
	}
	}

	void guessLaunchMode() {
	if (overrides?.mode != null) {
	return;
	}

	// Try to look backwards through log lines to determine launch mode.
	for (var i = lineNo - 1; i >= 0; i--) {
	final logLineMatch = logLinePattern.firstMatch(lines[i]);
	if (logLineMatch == null) {
	break;
	}
	final modeMatch =
	_launchModePattern.firstMatch(logLineMatch.namedGroup('rest'));
	if (modeMatch != null) {
	mode = modeMatch.namedGroup('mode');
	return;
	}
	}
	}

	static final _androidCrashMarker =
	'* * * * * * * * * * * * * * * *';

	static final _iosCrashMarker =
	RegExp(r'Incident Identifier:\s+([A-F0-9]+-?)+');

	static final _dartvmCrashMarker =
	RegExp(r'version=.on "(?<os>android)_(?<arch>arm\|arm64\|ia32\|x64)"\s$');

	static final _lineEnding = RegExp(r'\r?\n');
	static final _logcatPattern = RegExp(r'^.?:(?=$\|\s)\s(?<rest>.*)$');
	static final _flutterLogPattern =
	RegExp(r'^\s\[\s(\+?\s\d+\s(s\|ms\|h))?\]\s+(?<rest>.*)$');
	static final _deviceLabPattern = RegExp(
	r'(\d+-\d+-\d+T\d+:\d+:\d+.\d+: )?(stdout\|stderr):\s\[\s(\+?\s\d+\s(s\|ms\|h))?\]\s+(?<rest>.*)');

	static final _androidAbiPattern =
	RegExp(r"^\sABI: '(?<abi>x86\|x86_64\|x64\|arm\|arm64)'\s$");

	// Android Compatibility Definition mandates build fingerprint format to be:
	//
	// $(BRAND)/$(PRODUCT)/$(DEVICE):
	// $(VERSION.RELEASE)/$(ID)/$(VERSION.INCREMENTAL):$(TYPE)/$(TAGS)
	//
	// For our purposes we are only interested in VERSION.RELEASE component of the
	// fingerprint.
	//
	// See https://source.android.com/compatibility/11/android-11-cdd
	static final _androidBuildFingerprintPattern =
	RegExp(r"Build fingerprint: '[^:']+:(?<version>[\d\.]+)/[^']*'");
	static final _backtraceStartPattern = RegExp(r'^\sbacktrace:\s$');
	static final _androidFramePattern = RegExp(
	r'^\s#(?<no>\d+)\s+pc\s+(?<pc>[0-9a-f]+)\s+(?<binary>[^\s]+)(?<rest>.)$');
	static final _buildIdPattern = RegExp(r'\(BuildId: (?<id>[0-9a-f]+)\)');
	static final _launchModePattern =
	RegExp(r'^\sLaunching . on .* in (?<mode>debug\|release\|profile) mode');

	static final _eofPattern = RegExp(r'^\sEOF\s$');
	static final _appFrameworkPattern = RegExp(
	r'^\s*0x[a-f0-9]+\s+-\s+0x[a-f0-9]+\s+App\s+arm\w+\s+<[a-f0-9]+>\s+/var/containers');
	static final _iosAbiPattern = RegExp(r'\s*Code\s+Type:\s+(?<abi>[\-\w]+)\s+');
	static final _crashedThreadPattern = RegExp(r'^\s*Thread \d+ Crashed:');
	static final _iosFramePattern = RegExp(
	r'^\s(?<no>\d+)\s+(?<binary>\S+)\s+(?<pc>0x[a-f0-9]+)\s+(?<rest>.)$',
	unicode: true);
	static final _offsetSuffixPattern =
	RegExp(r'^(?<symbol>.*)\s+\+\s+(?<offset>\d+)$');

	static final _endOfDumpStackTracePattern = '-- End of DumpStackTrace';
	static final _dartvmFramePattern = RegExp(
	r'(^\|\s+)pc\s+(?<pc>0x[a-f0-9]+)\s+fp\s+(?<fp>0x[a-f0-9]+)\s+(?<binary>[^\s+]+)\+(?<offset>0x[a-f0-9]+)');
	}