dart:io | Add FileSystemEntity.typeSync to test for symbolic links.

sdk/lib/io/file_system_entity.dart

 // Copyright (c) 2013, 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.
 
 part of dart.io;
 
+class FileSystemEntityType {
+  static const FILE = const FileSystemEntityType._internal(0);
+  static const DIRECTORY = const FileSystemEntityType._internal(1);
+  static const LINK = const FileSystemEntityType._internal(2);
+  static const NOT_FOUND = const FileSystemEntityType._internal(3);
+  static const _typeList = const [FileSystemEntityType.FILE,
+                                  FileSystemEntityType.DIRECTORY,
+                                  FileSystemEntityType.LINK,
+                                  FileSystemEntityType.NOT_FOUND];
+  const FileSystemEntityType._internal(int this._type);
+
+  static FileSystemEntityType _lookup(int type) => _typeList[type];
+  String toString() => const ['FILE', 'DIRECTORY', 'LINK', 'NOT_FOUND'][_type];
+
+  final int _type;
+}
+
 /**
  * A [FileSystemEntity] is a common super class for [File] and
  * [Directory] objects.
  *
  * [FileSystemEntity] objects are returned from directory listing
  * operations. To determine if a FileSystemEntity is a [File] or a
  * [Directory], perform a type check:
  *
  *     if (entity is File) (entity as File).readAsStringSync();
  */
 abstract class FileSystemEntity {
   String get path;
+
+  external static int _getType(String path, bool followLinks);
+
+  static int _getTypeSync(String path, bool followLinks) {
+    var result = _getType(path, followLinks);
+    _throwIfError(result, 'Error getting type of FileSystemEntity');
+    return result;
+  }
+
+  static FileSystemEntityType typeSync(String path, {bool followLinks: true})
+      => FileSystemEntityType._lookup(_getTypeSync(path, followLinks));
+
+  static bool isLinkSync(String path) =>
+      (_getTypeSync(path, false) == FileSystemEntityType.LINK._type);
+
+  static bool isFileSync(String path) =>
+      (_getTypeSync(path, true) == FileSystemEntityType.FILE._type);
+
+  static bool isDirectorySync(String path) =>
+      (_getTypeSync(path, true) == FileSystemEntityType.DIRECTORY._type);
+
+  static _throwIfError(Object result, String msg) {
+    if (result is OSError) {
+      throw new FileIOException(msg, result);
+    }
+  }
 }