Give channel descriptions in flutter channel, use branch instead of upstream for channel name

packages/flutter_tools/lib/src/base/user_messages.dart

@@ -21,7 +21,7 @@ class UserMessages {
 
   // Messages used in FlutterValidator
   String flutterStatusInfo(String? channel, String? version, String os, String locale) =>
-      'Channel ${channel ?? 'unknown'}, ${version ?? 'Unknown'}, on $os, locale $locale';
+      'Channel ${channel ?? 'unknown'}, ${version ?? 'unknown version'}, on $os, locale $locale';
   String flutterVersion(String version, String channel, String flutterRoot) =>
       'Flutter version $version on channel $channel at $flutterRoot';
   String get flutterUnknownChannel =>

packages/flutter_tools/lib/src/commands/channel.dart

@@ -53,13 +53,12 @@ class ChannelCommand extends FlutterCommand {
 
   Future<void> _listChannels({ required bool showAll, required bool verbose }) async {
     // Beware: currentBranch could contain PII. See getBranchName().
-    final String currentChannel = globals.flutterVersion.channel;
+    final String currentChannel = globals.flutterVersion.channel; // limited to known branch names
+    assert(kOfficialChannels.contains(currentChannel) || kObsoleteBranches.containsKey(currentChannel) || currentChannel == kUserBranch, 'potential PII leak in channel name: "$currentChannel"');
     final String currentBranch = globals.flutterVersion.getBranchName();
     final Set<String> seenUnofficialChannels = <String>{};
     final List<String> rawOutput = <String>[];
 
-    showAll = showAll || currentChannel != currentBranch;
-
     globals.printStatus('Flutter channels:');
     final int result = await globals.processUtils.stream(
       <String>['git', 'branch', '-r'],
@@ -74,8 +73,7 @@ class ChannelCommand extends FlutterCommand {
       throwToolExit('List channels failed: $result$details', exitCode: result);
     }
 
-    final List<String> officialChannels = kOfficialChannels.toList();
-    final List<bool> availableChannels = List<bool>.filled(officialChannels.length, false);
+    final Set<String> availableChannels = <String>{};
 
     for (final String line in rawOutput) {
       final List<String> split = line.split('/');
@@ -84,27 +82,25 @@ class ChannelCommand extends FlutterCommand {
         continue;
       }
       final String branch = split[1];
-      if (split.length > 1) {
-        final int index = officialChannels.indexOf(branch);
-
-        if (index != -1) { // Mark all available channels official channels from output
-          availableChannels[index] = true;
-        } else if (showAll && !seenUnofficialChannels.contains(branch)) {
-        // add other branches to seenUnofficialChannels if --all flag is given (to print later)
-          seenUnofficialChannels.add(branch);
-        }
+      if (kOfficialChannels.contains(branch)) {
+        availableChannels.add(branch);
+      } else if (showAll) {
+        seenUnofficialChannels.add(branch);
       }
     }
 
+    bool currentChannelIsOfficial = false;
+
     // print all available official channels in sorted manner
-    for (int i = 0; i < officialChannels.length; i++) {
+    for (final String channel in kOfficialChannels) {
       // only print non-missing channels
-      if (availableChannels[i]) {
+      if (availableChannels.contains(channel)) {
         String currentIndicator = ' ';
-        if (officialChannels[i] == currentChannel) {
+        if (channel == currentChannel) {
           currentIndicator = '*';
+          currentChannelIsOfficial = true;
         }
-        globals.printStatus('$currentIndicator ${officialChannels[i]}');
+        globals.printStatus('$currentIndicator $channel (${kChannelDescriptions[channel]})');
       }
     }
 
@@ -117,9 +113,12 @@ class ChannelCommand extends FlutterCommand {
           globals.printStatus('  $branch');
         }
       }
+    } else if (!currentChannelIsOfficial) {
+      globals.printStatus('* $currentBranch');
     }
 
-    if (currentChannel == 'unknown') {
+    if (!currentChannelIsOfficial) {
+      assert(currentChannel == kUserBranch, 'Current channel is "$currentChannel", which is not an official branch. (Current branch is "$currentBranch".)');
       globals.printStatus('');
       globals.printStatus('Currently not on an official channel.');
     }

packages/flutter_tools/lib/src/commands/create_base.dart

@@ -407,8 +407,8 @@ abstract class CreateBase extends FlutterCommand {
       'iosLanguage': iosLanguage,
       'hasIosDevelopmentTeam': iosDevelopmentTeam != null && iosDevelopmentTeam.isNotEmpty,
       'iosDevelopmentTeam': iosDevelopmentTeam ?? '',
-      'flutterRevision': globals.flutterVersion.frameworkRevision,
-      'flutterChannel': globals.flutterVersion.channel,
+      'flutterRevision': escapeYamlString(globals.flutterVersion.frameworkRevision),
+      'flutterChannel': escapeYamlString(globals.flutterVersion.getBranchName()), // may contain PII
       'ios': ios,
       'android': android,
       'web': web,
@@ -571,10 +571,11 @@ abstract class CreateBase extends FlutterCommand {
       final FlutterProjectMetadata metadata = FlutterProjectMetadata.explicit(
         file: metadataFile,
         versionRevision: globals.flutterVersion.frameworkRevision,
-        versionChannel: globals.flutterVersion.channel,
+        versionChannel: globals.flutterVersion.getBranchName(), // may contain PII
         projectType: projectType,
         migrateConfig: MigrateConfig(),
-        logger: globals.logger);
+        logger: globals.logger,
+      );
       metadata.populate(
         platforms: platformsForMigrateConfig,
         projectDirectory: directory,

packages/flutter_tools/lib/src/commands/downgrade.dart

@@ -47,15 +47,15 @@ class DowngradeCommand extends FlutterCommand {
       'working-directory',
       hide: !verboseHelp,
       help: 'Override the downgrade working directory. '
-            'This is only intended to enable integration testing of the tool itself.'
+            'This is only intended to enable integration testing of the tool itself. '
+            'It allows one to use the flutter tool from one checkout to downgrade a '
+            'different checkout.'
     );
     argParser.addFlag(
       'prompt',
       defaultsTo: true,
       hide: !verboseHelp,
-      help: 'Show the downgrade prompt. '
-            'The ability to disable this using "--no-prompt" is only provided for '
-            'integration testing of the tool itself.'
+      help: 'Show the downgrade prompt.'
     );
   }
 
@@ -99,8 +99,8 @@ class DowngradeCommand extends FlutterCommand {
     final Channel? channel = getChannelForName(currentChannel);
     if (channel == null) {
       throwToolExit(
-        'Flutter is not currently on a known channel. Use "flutter channel <name>" '
-        'to switch to an official channel.',
+        'Flutter is not currently on a known channel. '
+        'Use "flutter channel" to switch to an official channel. '
       );
     }
     final PersistentToolState persistentToolState = _persistentToolState!;
@@ -153,23 +153,23 @@ class DowngradeCommand extends FlutterCommand {
     } on ProcessException catch (error) {
       throwToolExit(
         'Unable to downgrade Flutter: The tool could not update to the version '
-        '$humanReadableVersion. This may be due to git not being installed or an '
-        'internal error. Please ensure that git is installed on your computer and '
-        'retry again.\nError: $error.'
+        '$humanReadableVersion.\n'
+        'Error: $error'
       );
     }
     try {
       await processUtils.run(
+        // The `--` bit (because it's followed by nothing) means that we don't actually change
+        // anything in the working tree, which avoids the need to first go into detached HEAD mode.
         <String>['git', 'checkout', currentChannel, '--'],
         throwOnError: true,
         workingDirectory: workingDirectory,
       );
     } on ProcessException catch (error) {
       throwToolExit(
         'Unable to downgrade Flutter: The tool could not switch to the channel '
-        '$currentChannel. This may be due to git not being installed or an '
-        'internal error. Please ensure that git is installed on your computer '
-        'and retry again.\nError: $error.'
+        '$currentChannel.\n'
+        'Error: $error'
       );
     }
     await FlutterVersion.resetFlutterVersionFreshnessCheck();

packages/flutter_tools/lib/src/doctor.dart

@@ -577,14 +577,14 @@ class FlutterValidator extends DoctorValidator {
   ValidationMessage _getFlutterVersionMessage(String frameworkVersion, String versionChannel, String flutterRoot) {
     String flutterVersionMessage = _userMessages.flutterVersion(frameworkVersion, versionChannel, flutterRoot);
 
-    // The tool sets the channel as "unknown", if the current branch is on a
-    // "detached HEAD" state or doesn't have an upstream, and sets the
-    // frameworkVersion as "0.0.0-unknown" if  "git describe" on HEAD doesn't
-    // produce an expected format to be parsed for the frameworkVersion.
-    if (versionChannel != 'unknown' && frameworkVersion != '0.0.0-unknown') {
+    // The tool sets the channel as kUserBranch, if the current branch is on a
+    // "detached HEAD" state, doesn't have an upstream, or is on a user branch,
+    // and sets the frameworkVersion as "0.0.0-unknown" if "git describe" on
+    // HEAD doesn't produce an expected format to be parsed for the frameworkVersion.
+    if (versionChannel != kUserBranch && frameworkVersion != '0.0.0-unknown') {
       return ValidationMessage(flutterVersionMessage);
     }
-    if (versionChannel == 'unknown') {
+    if (versionChannel == kUserBranch) {
       flutterVersionMessage = '$flutterVersionMessage\n${_userMessages.flutterUnknownChannel}';
     }
     if (frameworkVersion == '0.0.0-unknown') {

packages/flutter_tools/lib/src/flutter_project_metadata.dart

@@ -8,6 +8,7 @@ import 'base/file_system.dart';
 import 'base/logger.dart';
 import 'base/utils.dart';
 import 'project.dart';
+import 'template.dart';
 import 'version.dart';
 
 enum FlutterProjectType implements CliEnum {
@@ -172,11 +173,11 @@ class FlutterProjectMetadata {
 # This file tracks properties of this Flutter project.
 # Used by Flutter tool to assess capabilities and perform upgrades etc.
 #
-# This file should be version controlled.
+# This file should be version controlled and should not be manually edited.
 
 version:
-  revision: $_versionRevision
-  channel: $_versionChannel
+  revision: ${escapeYamlString(_versionRevision ?? '')}
+  channel: ${escapeYamlString(_versionChannel ?? kUserBranch)}
 
 project_type: ${projectType == null ? '' : projectType!.cliName}
 ${migrateConfig.getOutputFileString()}''';

packages/flutter_tools/lib/src/globals.dart

@@ -300,9 +300,6 @@ CustomDevicesConfig get customDevicesConfig => context.get<CustomDevicesConfig>(
 
 PreRunValidator get preRunValidator => context.get<PreRunValidator>() ?? const NoOpPreRunValidator();
 
-// TODO(fujino): Migrate to 'main' https://github.com/flutter/flutter/issues/95041
-const String kDefaultFrameworkChannel = 'master';
-
 // Used to build RegExp instances which can detect the VM service message.
 final RegExp kVMServiceMessageRegExp = RegExp(r'The Dart VM service is listening on ((http|//)[a-zA-Z0-9:/=_\-\.\[\]]+)');
 

packages/flutter_tools/lib/src/template.dart

@@ -375,3 +375,24 @@ String _escapeKotlinKeywords(String androidIdentifier) {
   ).toList();
   return correctedSegments.join('.');
 }
+
+String escapeYamlString(String value) {
+  final StringBuffer result = StringBuffer();
+  result.write('"');
+  for (final int rune in value.runes) {
+    result.write(
+      switch (rune) {
+        0x00 => r'\0',
+        0x09 => r'\t',
+        0x0A => r'\n',
+        0x0D => r'\r',
+        0x22 => r'\"',
+        0x5C => r'\\',
+        < 0x20 => '\\x${rune.toRadixString(16).padLeft(2, "0")}',
+        _ => String.fromCharCode(rune),
+      }
+    );
+  }
+  result.write('"');
+  return result.toString();
+}

packages/flutter_tools/lib/src/version.dart

@@ -22,6 +22,9 @@ const String _unknownFrameworkVersion = '0.0.0-unknown';
 /// See `man gitrevisions` for more information.
 const String kGitTrackingUpstream = '@{upstream}';
 
+/// Replacement name when the branch is user-specific.
+const String kUserBranch = '[user-branch]';
+
 /// This maps old branch names to the names of branches that replaced them.
 ///
 /// For example, in 2021 we deprecated the "dev" channel and transitioned "dev"
@@ -40,12 +43,24 @@ enum Channel {
 
 // Beware: Keep order in accordance with stability
 const Set<String> kOfficialChannels = <String>{
-  globals.kDefaultFrameworkChannel,
+  'master',
   'main',
   'beta',
   'stable',
 };
 
+const Map<String, String> kChannelDescriptions = <String, String>{
+  'master': 'latest development branch, for contributors',
+  'main': 'latest development branch, follows master channel',
+  'beta': 'updated monthly, recommended for experienced users',
+  'stable': 'updated quarterly, for new users and for production app releases',
+};
+
+const Set<String> kDevelopmentChannels = <String>{
+  'master',
+  'main',
+};
+
 /// Retrieve a human-readable name for a given [channel].
 ///
 /// Requires [kOfficialChannels] to be correctly ordered.
@@ -101,16 +116,7 @@ class FlutterVersion {
 
   String? _repositoryUrl;
   String? get repositoryUrl {
-    final String _ = channel;
-    return _repositoryUrl;
-  }
-
-  String? _channel;
-  /// The channel is the upstream branch.
-  /// `master`, `dev`, `beta`, `stable`; or old ones, like `alpha`, `hackathon`, ...
-  String get channel {
-    String? channel = _channel;
-    if (channel == null) {
+    if (_repositoryUrl == null) {
       final String gitChannel = _runGit(
         'git rev-parse --abbrev-ref --symbolic $kGitTrackingUpstream',
         globals.processUtils,
@@ -124,14 +130,16 @@ class FlutterVersion {
           globals.processUtils,
           _workingDirectory,
         );
-        channel = gitChannel.substring(slash + 1);
-      } else if (gitChannel.isEmpty) {
-        channel = 'unknown';
-      } else {
-        channel = gitChannel;
       }
-      _channel = channel;
     }
+    return _repositoryUrl;
+  }
+
+  /// The channel is the current branch if we recognize it, or "[user-branch]" (kUserBranch).
+  /// `master`, `beta`, `stable`; or old ones, like `alpha`, `hackathon`, `dev`, ...
+  String get channel {
+    final String channel = getBranchName(redactUnknownBranches: true);
+    assert(kOfficialChannels.contains(channel) || kObsoleteBranches.containsKey(channel) || channel == kUserBranch, 'Potential PII leak in channel name: "$channel"');
     return channel;
   }
 
@@ -296,16 +304,16 @@ class FlutterVersion {
   /// Return the branch name.
   ///
   /// If [redactUnknownBranches] is true and the branch is unknown,
-  /// the branch name will be returned as `'[user-branch]'`.
+  /// the branch name will be returned as `'[user-branch]'` ([kUserBranch]).
   String getBranchName({ bool redactUnknownBranches = false }) {
     _branch ??= () {
-      final String branch = _runGit('git rev-parse --abbrev-ref HEAD', globals.processUtils);
-      return branch == 'HEAD' ? channel : branch;
+      final String branch = _runGit('git symbolic-ref --short HEAD', globals.processUtils, _workingDirectory);
+      return branch == 'HEAD' ? '' : branch;
     }();
     if (redactUnknownBranches || _branch!.isEmpty) {
       // Only return the branch names we know about; arbitrary branch names might contain PII.
       if (!kOfficialChannels.contains(_branch) && !kObsoleteBranches.containsKey(_branch)) {
-        return '[user-branch]';
+        return kUserBranch;
       }
     }
     return _branch!;
@@ -619,7 +627,7 @@ String _runSync(List<String> command, { bool lenient = true }) {
   return '';
 }
 
-String _runGit(String command, ProcessUtils processUtils, [String? workingDirectory]) {
+String _runGit(String command, ProcessUtils processUtils, String? workingDirectory) {
   return processUtils.runSync(
     command.split(' '),
     workingDirectory: workingDirectory ?? Cache.flutterRoot,
@@ -709,8 +717,8 @@ class GitTagVersion {
     String gitRef = 'HEAD'
   }) {
     if (fetchTags) {
-      final String channel = _runGit('git rev-parse --abbrev-ref HEAD', processUtils, workingDirectory);
-      if (channel == 'dev' || channel == 'beta' || channel == 'stable') {
+      final String channel = _runGit('git symbolic-ref --short HEAD', processUtils, workingDirectory);
+      if (!kDevelopmentChannels.contains(channel) && kOfficialChannels.contains(channel)) {
         globals.printTrace('Skipping request to fetchTags - on well known channel $channel.');
       } else {
         final String flutterGit = platform.environment['FLUTTER_GIT_URL'] ?? 'https://github.com/flutter/flutter.git';
@@ -918,8 +926,6 @@ class VersionFreshnessValidator {
         return const Duration(days: 365 ~/ 2); // Six months
       case 'beta':
         return const Duration(days: 7 * 8); // Eight weeks
-      case 'dev':
-        return const Duration(days: 7 * 4); // Four weeks
       default:
         return const Duration(days: 7 * 3); // Three weeks
     }