Add support for removing directories (#218)

Author: brianquinlan

pkgs/io_file/README.md

@@ -17,7 +17,7 @@ See
 |  create symbolic link |         |       |       |       |         |            |              |
 |  create tmp directory |         |       |       |       |         |            |              |
 |  create tmp file      |         |       |       |       |         |            |              |
-|  delete directory     |         |       |       |       |         |            |              |
+|  delete directory     |         |   ✓   |   ✓   |   ✓   |    ✓    |            |              |
 |  delete file          |         |       |       |       |         |            |              |
 |  delete tree          |         |       |       |       |         |            |              |
 |  enum dir contents    |         |       |       |       |         |            |              |

pkgs/io_file/lib/src/file_system.dart

@@ -43,6 +43,22 @@ base class FileSystem {
     throw UnsupportedError('createDirectory');
   }
 
+  /// Deletes the directory at the given path.
+  ///
+  /// If `path` is a directory but the directory is not empty, then
+  /// `FileSystemException` is thrown.
+  ///
+  /// TODO(bquinlan): Explain how to delete non-empty directories.
+  ///
+  /// If `path` is not directory:
+  ///
+  /// - On Windows, if `path` is a symbolic link to a directory then the
+  ///   symbolic link is deleted. Otherwise, a `FileSystemException` is thrown.
+  /// - On POSIX, a `FileSystemException` is thrown.
+  void removeDirectory(String path) {
+    throw UnsupportedError('removeDirectory');
+  }
+
   /// Renames, and possibly moves a file system object from one path to another.
   ///
   /// If `newPath` is a relative path, it is resolved against the current

pkgs/io_file/lib/src/vm_posix_file_system.dart

@@ -68,6 +68,14 @@ base class PosixFileSystem extends FileSystem {
     }
   }
 
+  @override
+  void removeDirectory(String path) {
+    if (stdlibc.unlinkat(stdlibc.AT_FDCWD, path, stdlibc.AT_REMOVEDIR) == -1) {
+      final errno = stdlibc.errno;
+      throw _getError(errno, 'remove directory failed', path);
+    }
+  }
+
   @override
   void rename(String oldPath, String newPath) {
     // See https://pubs.opengroup.org/onlinepubs/000095399/functions/rename.html

pkgs/io_file/lib/src/vm_windows_file_system.dart

@@ -79,12 +79,24 @@ base class WindowsFileSystem extends FileSystem {
   void createDirectory(String path) => using((arena) {
     _primeGetLastError();
 
-    if (win32.CreateDirectory(path.toNativeUtf16(), nullptr) == win32.FALSE) {
+    if (win32.CreateDirectory(path.toNativeUtf16(allocator: arena), nullptr) ==
+        win32.FALSE) {
       final errorCode = win32.GetLastError();
       throw _getError(errorCode, 'create directory failed', path);
     }
   });
 
+  @override
+  void removeDirectory(String path) => using((arena) {
+    _primeGetLastError();
+
+    if (win32.RemoveDirectory(path.toNativeUtf16(allocator: arena)) ==
+        win32.FALSE) {
+      final errorCode = win32.GetLastError();
+      throw _getError(errorCode, 'remove directory failed', path);
+    }
+  });
+
   @override
   void rename(String oldPath, String newPath) => using((arena) {
     _primeGetLastError();

pkgs/io_file/test/remove_directory_test.dart

@@ -0,0 +1,128 @@
+// Copyright (c) 2025, 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.
+
+@TestOn('vm')
+library;
+
+import 'dart:io';
+
+import 'package:io_file/io_file.dart';
+import 'package:stdlibc/stdlibc.dart' as stdlibc;
+import 'package:test/test.dart';
+import 'package:win32/win32.dart' as win32;
+
+import 'test_utils.dart';
+
+void main() {
+  group('removeDirectory', () {
+    late String tmp;
+
+    setUp(() => tmp = createTemp('createDirectory'));
+
+    tearDown(() => deleteTemp(tmp));
+
+    //TODO(brianquinlan): test with a very long path.
+
+    test('success', () {
+      final path = '$tmp/dir';
+      Directory(path).createSync();
+
+      fileSystem.removeDirectory(path);
+
+      expect(FileSystemEntity.typeSync(path), FileSystemEntityType.notFound);
+    });
+
+    test('non-empty directory', () {
+      final path = '$tmp/dir';
+      Directory(path).createSync();
+      File('$tmp/dir/file').writeAsStringSync('Hello World!');
+
+      expect(
+        () => fileSystem.removeDirectory(path),
+        throwsA(
+          isA<FileSystemException>()
+              .having((e) => e.message, 'message', 'remove directory failed')
+              .having(
+                (e) => e.osError?.errorCode,
+                'errorCode',
+                Platform.isWindows
+                    ? win32.ERROR_DIR_NOT_EMPTY
+                    : stdlibc.ENOTEMPTY,
+              ),
+        ),
+      );
+    });
+
+    test('non-existent directory', () {
+      final path = '$tmp/foo/dir';
+
+      expect(
+        () => fileSystem.removeDirectory(path),
+        throwsA(
+          isA<PathNotFoundException>()
+              .having((e) => e.message, 'message', 'remove directory failed')
+              .having(
+                (e) => e.osError?.errorCode,
+                'errorCode',
+                Platform.isWindows
+                    ? win32.ERROR_PATH_NOT_FOUND
+                    : stdlibc.ENOENT,
+              ),
+        ),
+      );
+    });
+
+    test('file', () {
+      final path = '$tmp/file';
+      File(path).writeAsStringSync('Hello World!');
+
+      expect(
+        () => fileSystem.removeDirectory(path),
+        throwsA(
+          isA<FileSystemException>()
+              .having((e) => e.message, 'message', 'remove directory failed')
+              .having(
+                (e) => e.osError?.errorCode,
+                'errorCode',
+                Platform.isWindows ? win32.ERROR_DIRECTORY : stdlibc.ENOTDIR,
+              ),
+        ),
+      );
+    });
+
+    test('link', () {
+      final dirPath = '$tmp/dir';
+      final linkPath = '$tmp/link';
+      Directory(dirPath).createSync();
+      Link(linkPath).createSync(dirPath);
+
+      if (Platform.isWindows) {
+        fileSystem.removeDirectory(linkPath);
+        expect(
+          FileSystemEntity.typeSync(dirPath),
+          FileSystemEntityType.directory,
+        );
+        expect(
+          FileSystemEntity.typeSync(linkPath),
+          FileSystemEntityType.notFound,
+        );
+      } else {
+        expect(
+          () => fileSystem.removeDirectory(linkPath),
+          throwsA(
+            isA<FileSystemException>()
+                .having((e) => e.message, 'message', 'remove directory failed')
+                .having(
+                  (e) => e.osError?.errorCode,
+                  'errorCode',
+                  Platform.isWindows
+                      ? win32.ERROR_PATH_NOT_FOUND
+                      : stdlibc.ENOTDIR,
+                ),
+          ),
+        );
+      }
+    });
+  });
+}