macOS unzip then rsync to delete stale artifacts (#85075)

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

@@ -427,6 +427,45 @@ class _MacOSUtils extends _PosixUtils {
     }
     return _hostPlatform!;
   }
+
+  // unzip, then rsync
+  @override
+  void unzip(File file, Directory targetDirectory) {
+    if (!_processManager.canRun('unzip')) {
+      // unzip is not available. this error message is modeled after the download
+      // error in bin/internal/update_dart_sdk.sh
+      throwToolExit('Missing "unzip" tool. Unable to extract ${file.path}.\nConsider running "brew install unzip".');
+    }
+    if (_processManager.canRun('rsync')) {
+      final Directory tempDirectory = _fileSystem.systemTempDirectory.createTempSync('flutter_${file.basename}.');
+      try {
+        // Unzip to a temporary directory.
+        _processUtils.runSync(
+          <String>['unzip', '-o', '-q', file.path, '-d', tempDirectory.path],
+          throwOnError: true,
+          verboseExceptions: true,
+        );
+        for (final FileSystemEntity unzippedFile in tempDirectory.listSync(followLinks: false)) {
+          // rsync --delete the unzipped files so files removed from the archive are also removed from the target.
+          _processUtils.runSync(
+            <String>['rsync', '-av', '--delete', unzippedFile.path, targetDirectory.path],
+            throwOnError: true,
+            verboseExceptions: true,
+          );
+        }
+      } finally {
+        tempDirectory.deleteSync(recursive: true);
+      }
+    } else {
+      // Fall back to just unzipping.
+      _logger.printTrace('Unable to find rsync, falling back to direct unzipping.');
+      _processUtils.runSync(
+        <String>['unzip', '-o', '-q', file.path, '-d', targetDirectory.path],
+        throwOnError: true,
+        verboseExceptions: true,
+      );
+    }
+  }
 }
 
 class _WindowsUtils extends OperatingSystemUtils {

packages/flutter_tools/test/general.shard/base/os_test.dart

@@ -4,6 +4,7 @@
 
 import 'package:file/file.dart';
 import 'package:file/memory.dart';
+import 'package:file_testing/file_testing.dart';
 import 'package:flutter_tools/src/base/file_system.dart';
 import 'package:flutter_tools/src/base/logger.dart';
 import 'package:flutter_tools/src/base/os.dart';
@@ -536,6 +537,79 @@ void main() {
     );
   });
 
+  group('unzip on macOS', () {
+    testWithoutContext('falls back to unzip when rsync cannot run', () {
+      final FileSystem fileSystem = MemoryFileSystem.test();
+      fakeProcessManager.excludedExecutables.add('rsync');
+
+      final BufferLogger logger = BufferLogger.test();
+      final OperatingSystemUtils macOSUtils = OperatingSystemUtils(
+        fileSystem: fileSystem,
+        logger: logger,
+        platform: FakePlatform(operatingSystem: 'macos'),
+        processManager: fakeProcessManager,
+      );
+
+      final Directory targetDirectory = fileSystem.currentDirectory;
+      fakeProcessManager.addCommand(FakeCommand(
+        command: <String>['unzip', '-o', '-q', 'foo.zip', '-d', targetDirectory.path],
+      ));
+
+      macOSUtils.unzip(fileSystem.file('foo.zip'), targetDirectory);
+      expect(fakeProcessManager, hasNoRemainingExpectations);
+      expect(logger.traceText, contains('Unable to find rsync'));
+    });
+
+    testWithoutContext('unzip and rsyncs', () {
+      final FileSystem fileSystem = MemoryFileSystem.test();
+
+      final OperatingSystemUtils macOSUtils = OperatingSystemUtils(
+        fileSystem: fileSystem,
+        logger: BufferLogger.test(),
+        platform: FakePlatform(operatingSystem: 'macos'),
+        processManager: fakeProcessManager,
+      );
+
+      final Directory targetDirectory = fileSystem.currentDirectory;
+      final Directory tempDirectory = fileSystem.systemTempDirectory.childDirectory('flutter_foo.zip.rand0');
+      fakeProcessManager.addCommands(<FakeCommand>[
+        FakeCommand(
+          command: <String>[
+            'unzip',
+            '-o',
+            '-q',
+            'foo.zip',
+            '-d',
+            tempDirectory.path,
+          ],
+          onRun: () {
+            expect(tempDirectory, exists);
+            tempDirectory.childDirectory('dirA').childFile('fileA').createSync(recursive: true);
+            tempDirectory.childDirectory('dirB').childFile('fileB').createSync(recursive: true);
+          },
+        ),
+        FakeCommand(command: <String>[
+          'rsync',
+          '-av',
+          '--delete',
+          tempDirectory.childDirectory('dirA').path,
+          targetDirectory.path,
+        ]),
+        FakeCommand(command: <String>[
+          'rsync',
+          '-av',
+          '--delete',
+          tempDirectory.childDirectory('dirB').path,
+          targetDirectory.path,
+        ]),
+      ]);
+
+      macOSUtils.unzip(fileSystem.file('foo.zip'), fileSystem.currentDirectory);
+      expect(fakeProcessManager, hasNoRemainingExpectations);
+      expect(tempDirectory, isNot(exists));
+    });
+  });
+
   group('display an install message when unzip cannot be run', () {
     testWithoutContext('Linux', () {
       final FileSystem fileSystem = MemoryFileSystem.test();