[devtools] Add update license command

tool/lib/commands/update_licenses.dart

@@ -0,0 +1,78 @@
+// Copyright 2024 The Flutter Authors
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file or at https://developers.google.com/open-source/licenses/bsd.
+import 'dart:io';
+
+import 'package:args/command_runner.dart';
+import 'package:cli_util/cli_logging.dart';
+import 'package:path/path.dart' as p;
+
+import '../license_utils.dart';
+
+const _argConfig = 'config';
+const _argDirectory = 'directory';
+const _dryRun = 'dry-run';
+
+/// This command updates license headers for the configured files.
+///
+/// The config file is a YAML file as defined in [LicenseConfig].
+///
+/// If directory is not set, it will default to the current directory.
+///
+/// When the '--dry-run' flag is passed in, a list of files to update will
+/// be logged, but no files will be modified.
+///
+/// To run this script
+/// `dt update-licenses [--f <config-file>] [--d <directory>] [--dry-run]`
+class UpdateLicensesCommand extends Command {
+  UpdateLicensesCommand() {
+    argParser
+      ..addOption(
+        _argConfig,
+        abbr: 'c',
+        defaultsTo: p.join(Directory.current.path, 'update_licenses.yaml'),
+        help:
+            'The path to the YAML license config file. Defaults to '
+            'update_licenses.yaml',
+      )
+      ..addOption(
+        _argDirectory,
+        defaultsTo: Directory.current.path,
+        abbr: 'd',
+        help: 'Update license headers for files in the directory.',
+      )
+      ..addFlag(
+        _dryRun,
+        negatable: false,
+        defaultsTo: false,
+        help:
+            'If set, log a list of files that require an update, but do not '
+            'modify any files.',
+      );
+  }
+
+  @override
+  String get description => 'Update license headers as configured.';
+
+  @override
+  String get name => 'update-licenses';
+
+  @override
+  Future run() async {
+    final config = LicenseConfig.fromYamlFile(
+      File(argResults![_argConfig] as String),
+    );
+    final directory = Directory(argResults![_argDirectory] as String);
+    final dryRun = argResults![_dryRun] as bool;
+    final log = Logger.standard();
+    final header = LicenseHeader();
+    final results = await header.bulkUpdate(
+      directory: directory,
+      config: config,
+      dryRun: dryRun,
+    );
+    final updatedPaths = results.updatedPaths;
+    final prefix = dryRun ? 'Requires update: ' : 'Updated: ';
+    log.stdout('$prefix ${updatedPaths.join(", ")}');
+  }
+}

tool/lib/devtools_command_runner.dart

@@ -13,6 +13,7 @@ import 'package:devtools_tool/commands/serve.dart';
 import 'package:devtools_tool/commands/sync.dart';
 import 'package:devtools_tool/commands/tag_version.dart';
 import 'package:devtools_tool/commands/update_flutter_sdk.dart';
+import 'package:devtools_tool/commands/update_licenses.dart';
 import 'package:devtools_tool/commands/update_perfetto.dart';
 import 'package:devtools_tool/model.dart';
 
@@ -47,6 +48,7 @@ class DevToolsCommandRunner extends CommandRunner {
     addCommand(UpdateDartSdkDepsCommand());
     addCommand(UpdateDevToolsVersionCommand());
     addCommand(UpdateFlutterSdkCommand());
+    addCommand(UpdateLicensesCommand());
     addCommand(UpdatePerfettoCommand());
 
     argParser.addFlag(

tool/lib/license_utils.dart

@@ -25,27 +25,27 @@ import 'package:yaml/yaml.dart';
 /// ```yaml
 /// # sequence of license text strings that should be matched against at the top of a file and removed. <value>, which normally represents a date, will be stored.
 /// remove_licenses:
-///   - |
-///     // This is some <value1> multiline license
+///   - |-
+///     // This is some <value> multiline license
 ///     // text that should be removed from the file.
-///   - |
-///     /* This is other <value2> multiline license
+///   - |-
+///     /* This is other <value> multiline license
 ///     text that should be removed from the file. */
-///   - |
-///     # This is more <value3> multiline license
+///   - |-
+///     # This is more <value> multiline license
 ///     # text that should be removed from the file.
-///   - |
+///   - |-
 ///     // This is some multiline license text to
 ///     // remove that does not contain a stored value.
-/// # sequence of license text strings that should be added to the top of a file. {value} will be replaced.
+/// # sequence of license text strings that should be added to the top of a file. <value> will be replaced.
 /// add_licenses:
-///   - |
-///     // This is some <value1> multiline license
+///   - |-
+///     // This is some <value> multiline license
 ///     // text that should be added to the file.
-///   - |
-///     # This is other <value3> multiline license
+///   - |-
+///     # This is other <value> multiline license
 ///     # text that should be added to the file.
-///   - |
+///   - |-
 ///     // This is some multiline license text to
 ///     // add that does not contain a stored value.
 /// # defines which files should have license text added or updated.
@@ -121,17 +121,23 @@ class LicenseConfig {
   final YamlMap fileTypes;
 
   /// Returns the list of indices for the given [ext] of [removeLicenses]
-  /// containing the license text to remove.
+  /// containing the license text to remove if they exist or an empty YamlList.
   YamlList getRemoveIndicesForExtension(String ext) {
     final fileType = fileTypes[_removeDotFromExtension(ext)];
-    return fileType['remove'] as YamlList;
+    if (fileType != null) {
+      return fileType['remove'] as YamlList;
+    }
+    return YamlList();
   }
 
   /// Returns the index for the given [ext] of [addLicenses] containing the
-  /// license text to add.
+  /// license text to add if it exists or -1.
   int getAddIndexForExtension(String ext) {
     final fileType = fileTypes[_removeDotFromExtension(ext)];
-    return fileType['add'];
+    if (fileType != null) {
+      return fileType['add'];
+    }
+    return -1;
   }
 
   /// Returns whether the file should be excluded according to the config.
@@ -202,7 +208,7 @@ class LicenseHeader {
         .handleError(
           (e) =>
               throw StateError(
-                'License header expected, but error reading file - $e',
+                'License header expected, but error reading $file - $e',
               ),
         );
     await for (final content in stream) {
@@ -254,6 +260,24 @@ class LicenseHeader {
     return rewrittenFile;
   }
 
+  /// Returns a copy of the given [file] that is missing a license header
+  /// with the [replacementHeader] added to the top.
+  ///
+  /// Reads and writes the entire file contents all at once, so performance may
+  /// degrade for large files.
+  File addLicenseHeader({
+    required File file,
+    required String replacementHeader,
+  }) {
+    final rewrittenFile = File('${file.path}.tmp');
+    final contents = file.readAsStringSync();
+    rewrittenFile.writeAsStringSync(
+      '$replacementHeader${Platform.lineTerminator}$contents',
+      flush: true,
+    );
+    return rewrittenFile;
+  }
+
   /// Bulk update license headers for files in the [directory] as configured
   /// in the [config] and return a processed paths Record containing:
   /// - list of included paths
@@ -274,27 +298,50 @@ class LicenseHeader {
       if (!config.shouldExclude(file)) {
         includedPathsList.add(file.path);
         final extension = p.extension(file.path);
+        final addIndex = config.getAddIndexForExtension(extension);
+        if (addIndex == -1) {
+          // skip if add index doesn't exist for extension
+          continue;
+        }
+        final fileLength = file.lengthSync();
+        const bufferSize = 20;
+        final replacementLicenseText = config.addLicenses[addIndex];
+        final byteCount = min(
+          bufferSize + replacementLicenseText.length,
+          fileLength,
+        );
+        var replacementInfo = await getReplacementInfo(
+          file: file,
+          existingLicenseText: replacementLicenseText,
+          replacementLicenseText: replacementLicenseText,
+          byteCount: byteCount as int,
+        );
+        if (replacementInfo.existingHeader.isNotEmpty &&
+            replacementInfo.replacementHeader.isNotEmpty &&
+            replacementInfo.existingHeader ==
+                replacementInfo.replacementHeader) {
+          // Do nothing if the replacement header is the same as the
+          // existing header
+          continue;
+        }
         final removeIndices = config.getRemoveIndicesForExtension(extension);
         for (final removeIndex in removeIndices) {
           final existingLicenseText = config.removeLicenses[removeIndex];
-          final addIndex = config.getAddIndexForExtension(extension);
-          final replacementLicenseText = config.addLicenses[addIndex];
-          final fileLength = file.lengthSync();
-          const bufferSize = 20;
           // Assume that the license text will be near the start of the file,
           // but add in some buffer.
           final byteCount = min(
             bufferSize + existingLicenseText.length,
             fileLength,
           );
-          final replacementInfo = await getReplacementInfo(
+          replacementInfo = await getReplacementInfo(
             file: file,
             existingLicenseText: existingLicenseText,
             replacementLicenseText: replacementLicenseText,
             byteCount: byteCount as int,
           );
           if (replacementInfo.existingHeader.isNotEmpty &&
               replacementInfo.replacementHeader.isNotEmpty) {
+            // Case 1: Existing header needs to be replaced
             if (dryRun) {
               updatedPathsList.add(file.path);
             } else {
@@ -303,15 +350,27 @@ class LicenseHeader {
                 existingHeader: replacementInfo.existingHeader,
                 replacementHeader: replacementInfo.replacementHeader,
               );
-              if (rewrittenFile.lengthSync() > 0) {
-                file.writeAsStringSync(
-                  rewrittenFile.readAsStringSync(),
-                  mode: FileMode.writeOnly,
-                  flush: true,
-                );
-                updatedPathsList.add(file.path);
-              }
-              rewrittenFile.deleteSync();
+              _updateLicense(rewrittenFile, file, updatedPathsList);
+            }
+          }
+        }
+        if (!updatedPathsList.contains(file.path)) {
+          final licenseHeaders = _processHeaders(
+            storedName: '',
+            existingLicenseText: '',
+            replacementLicenseText: replacementLicenseText,
+            content: '',
+          );
+          if (licenseHeaders.replacementHeader.isNotEmpty) {
+            // Case 2: Missing header needs to be added
+            if (dryRun) {
+              updatedPathsList.add(file.path);
+            } else {
+              final rewrittenFile = addLicenseHeader(
+                file: file,
+                replacementHeader: licenseHeaders.replacementHeader,
+              );
+              _updateLicense(rewrittenFile, file, updatedPathsList);
             }
           }
         }
@@ -320,12 +379,35 @@ class LicenseHeader {
     return (includedPaths: includedPathsList, updatedPaths: updatedPathsList);
   }
 
+  void _updateLicense(
+    File rewrittenFile,
+    File file,
+    List<String> updatedPathsList,
+  ) {
+    if (rewrittenFile.lengthSync() > 0) {
+      file.writeAsStringSync(
+        rewrittenFile.readAsStringSync(),
+        mode: FileMode.writeOnly,
+        flush: true,
+      );
+      updatedPathsList.add(file.path);
+    }
+    rewrittenFile.deleteSync();
+  }
+
   ({String existingHeader, String replacementHeader}) _processHeaders({
     required String storedName,
     required String existingLicenseText,
     required String replacementLicenseText,
     required String content,
   }) {
+    if (existingLicenseText.isEmpty) {
+      final defaultReplacementHeader = replacementLicenseText.replaceAll(
+        '<$storedName>',
+        DateTime.now().year.toString(),
+      );
+      return (existingHeader: '', replacementHeader: defaultReplacementHeader);
+    }
     final matchStr = RegExp.escape(existingLicenseText);
     final storedNameIndex = matchStr.indexOf('<$storedName>');
     if (storedNameIndex != -1) {