Android lint to NNBD (#26826)

Author: dnfield

tools/android_lint/bin/main.dart

@@ -2,11 +2,227 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart=2.9
+import 'dart:io';
 
-import 'sound_main.dart' as m;
+import 'package:args/args.dart';
+import 'package:path/path.dart' as path;
+import 'package:process/process.dart';
 
-// TODO(dnfield): Migrate the deps in pubspec.yaml to null-safety versions.
-// In particular see the ongoing work on package:args here:
-// https://github.com/flutter/flutter/issues/72542
-Future<void> main(List<String> args) => m.main(args);
+const LocalProcessManager processManager = LocalProcessManager();
+
+/// Runs the Android SDK Lint tool on flutter/shell/platform/android.
+///
+/// This script scans the flutter/shell/platform/android directory for Java
+/// files to build a `project.xml` file.  This file is then passed to the lint
+/// tool. If an `--html` flag is also passed in, HTML output is reqeusted in the
+/// directory for the optional `--out` parameter, which defaults to
+/// `lint_report`. Otherwise the output is printed to STDOUT.
+///
+/// The `--in` parameter may be specified to force this script to scan a
+/// specific location for the engine repository, and expects to be given the
+/// `src` directory that contains both `third_party` and `flutter`.
+///
+/// At the time of this writing, the Android Lint tool doesn't work well with
+/// Java > 1.8.  This script will print a warning if you are not running
+/// Java 1.8.
+Future<void> main(List<String> args) async {
+  final ArgParser argParser = setupOptions();
+  await checkJava1_8();
+  final int exitCode = await runLint(argParser, argParser.parse(args));
+  exit(exitCode);
+}
+
+Future<int> runLint(ArgParser argParser, ArgResults argResults) async {
+  final String inArgument = argResults['in'] as String;
+  final Directory androidDir = Directory(path.join(
+    inArgument,
+    'flutter',
+    'shell',
+    'platform',
+    'android',
+  ));
+  if (!androidDir.existsSync()) {
+    print('This command must be run from the engine/src directory, '
+        'or be passed that directory as the --in parameter.\n');
+    print(argParser.usage);
+    return -1;
+  }
+
+  final Directory androidSdkDir = Directory(
+    path.join(inArgument, 'third_party', 'android_tools', 'sdk'),
+  );
+
+  if (!androidSdkDir.existsSync()) {
+    print('The Android SDK for this engine is missing from the '
+        'third_party/android_tools directory. Have you run gclient sync?\n');
+    print(argParser.usage);
+    return -1;
+  }
+
+  final bool rebaseline = argResults['rebaseline'] as bool;
+  if (rebaseline) {
+    print('Removing previous baseline.xml...');
+    final File baselineXml = File(baselineXmlPath);
+    if (baselineXml.existsSync()) {
+      await baselineXml.delete();
+    }
+  }
+  print('Preparing project.xml...');
+  final IOSink projectXml = File(projectXmlPath).openWrite();
+  projectXml.write('''
+<!-- THIS FILE IS GENERATED. PLEASE USE THE INCLUDED DART PROGRAM  WHICH -->
+<!-- WILL AUTOMATICALLY FIND ALL .java FILES AND INCLUDE THEM HERE       -->
+<project>
+  <sdk dir="${androidSdkDir.path}" />
+  <module name="FlutterEngine" android="true" library="true" compile-sdk-version="android-P">
+  <manifest file="${path.join(androidDir.path, 'AndroidManifest.xml')}" />
+''');
+  for (final FileSystemEntity entity in androidDir.listSync(recursive: true)) {
+    if (!entity.path.endsWith('.java')) {
+      continue;
+    }
+    projectXml.writeln('    <src file="${entity.path}" />');
+  }
+
+  projectXml.write('''
+  </module>
+</project>
+''');
+  await projectXml.close();
+
+  print('Wrote project.xml, starting lint...');
+  final List<String> lintArgs = <String>[
+    path.join(androidSdkDir.path, 'tools', 'bin', 'lint'),
+    '--project',
+    projectXmlPath,
+    '--showall',
+    '--exitcode', // Set non-zero exit code on errors
+    '-Wall',
+    '-Werror',
+    '--baseline',
+    baselineXmlPath,
+  ];
+  final bool html = argResults['html'] as bool;
+  if (html) {
+    lintArgs.addAll(<String>['--html', argResults['out'] as String]);
+  }
+  final String? javaHome = await getJavaHome();
+  final Process lintProcess = await processManager.start(
+    lintArgs,
+    environment: javaHome != null
+        ? <String, String>{
+            'JAVA_HOME': javaHome,
+          }
+        : null,
+  );
+  lintProcess.stdout.pipe(stdout);
+  lintProcess.stderr.pipe(stderr);
+  return lintProcess.exitCode;
+}
+
+/// Prepares an [ArgParser] for this script.
+ArgParser setupOptions() {
+  final ArgParser argParser = ArgParser();
+  argParser
+    ..addOption(
+      'in',
+      help: 'The path to `engine/src`.',
+      defaultsTo: path.relative(
+        path.join(
+          projectDir,
+          '..',
+          '..',
+          '..',
+        ),
+      ),
+    )
+    ..addFlag(
+      'help',
+      help: 'Print usage of the command.',
+      negatable: false,
+      defaultsTo: false,
+    )
+    ..addFlag(
+      'rebaseline',
+      help: 'Recalculates the baseline for errors and warnings '
+          'in this project.',
+      negatable: false,
+      defaultsTo: false,
+    )
+    ..addFlag(
+      'html',
+      help: 'Creates an HTML output for this report instead of printing '
+          'command line output.',
+      negatable: false,
+      defaultsTo: false,
+    )
+    ..addOption(
+      'out',
+      help: 'The path to write the generated HTML report. Ignored if '
+          '--html is not also true.',
+      defaultsTo: path.join(projectDir, 'lint_report'),
+    );
+
+  return argParser;
+}
+
+/// On macOS, we can try to find Java 1.8.
+///
+/// Otherwise, default to whatever JAVA_HOME is already.
+Future<String?> getJavaHome() async {
+  if (Platform.isMacOS) {
+    final ProcessResult result = await processManager.run(
+      <String>['/usr/libexec/java_home', '-v', '1.8', '-F'],
+    );
+    if (result.exitCode == 0) {
+      return (result.stdout as String).trim();
+    }
+  }
+  return Platform.environment['JAVA_HOME'];
+}
+
+/// Checks that `java` points to Java 1.8.
+///
+/// The SDK lint tool may not work with Java > 1.8.
+Future<void> checkJava1_8() async {
+  print('Checking Java version...');
+
+  if (Platform.isMacOS) {
+    final ProcessResult result = await processManager.run(
+      <String>['/usr/libexec/java_home', '-v', '1.8', '-F'],
+    );
+    if (result.exitCode != 0) {
+      print('Java 1.8 not available - the linter may not work properly.');
+    }
+    return;
+  }
+  final ProcessResult javaResult = await processManager.run(
+    <String>['java', '-version'],
+  );
+  if (javaResult.exitCode != 0) {
+    print('Could not run "java -version". '
+        'Ensure Java is installed and available on your path.');
+    print(javaResult.stderr);
+  }
+  // `java -version` writes to stderr.
+  final String javaVersionStdout = javaResult.stderr as String;
+  if (!javaVersionStdout.contains('"1.8')) {
+    print('The Android SDK tools may not work properly with your Java version. '
+        'If this process fails, please retry using Java 1.8.');
+  }
+}
+
+/// The root directory of this project.
+String get projectDir => path.dirname(
+      path.dirname(
+        path.fromUri(Platform.script),
+      ),
+    );
+
+/// The path to use for project.xml, which tells the linter where to find source
+/// files.
+String get projectXmlPath => path.join(projectDir, 'project.xml');
+
+/// The path to use for baseline.xml, which tells the linter what errors or
+/// warnings to ignore.
+String get baselineXmlPath => path.join(projectDir, 'baseline.xml');