Add function for finding what a InputStream or OutputStream is attached to

sdk/lib/io/stdio.dart

-// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// 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;
 
 const int _STDIO_HANDLE_TYPE_TERMINAL = 0;
 const int _STDIO_HANDLE_TYPE_PIPE = 1;
 const int _STDIO_HANDLE_TYPE_FILE = 2;
 const int _STDIO_HANDLE_TYPE_SOCKET = 3;
 const int _STDIO_HANDLE_TYPE_OTHER = -1;
 
 
+class StdioType {
+  static const StdioType TERMINAL = const StdioType._("terminal");
+  static const StdioType PIPE = const StdioType._("pipe");
+  static const StdioType FILE = const StdioType._("file");
+  static const StdioType OTHER = const StdioType._("other");
+  const StdioType._(String this.name);
+  final String name;
+}
+
+
 InputStream _stdin;
 OutputStream _stdout;
 OutputStream _stderr;
 
 
 InputStream get stdin {
   if (_stdin == null) {
     _stdin = _StdIOUtils._getStdioInputStream();
   }
   return _stdin;
 }
 
 
 OutputStream get stdout {
   if (_stdout == null) {
     _stdout = _StdIOUtils._getStdioOutputStream(1);
   }
   return _stdout;
 }
 
 
 OutputStream get stderr {
   if (_stderr == null) {
     _stderr = _StdIOUtils._getStdioOutputStream(2);
   }
   return _stderr;
 }
 
 
+StdioType stdioType(object) {
+  if (object is _FileOutputStream || object is _FileInputStream) {
+    return StdioType.FILE;
+  }
+  if (object is !_SocketOutputStream && object is !_SocketInputStream) {
+    return StdioType.OTHER;
+  }
+  switch (_StdIOUtils._socketType(object._socket)) {
+    case _STDIO_HANDLE_TYPE_TERMINAL: return StdioType.TERMINAL;
+    case _STDIO_HANDLE_TYPE_PIPE: return StdioType.PIPE;
+    case _STDIO_HANDLE_TYPE_FILE:  return StdioType.FILE;
+    default: return StdioType.OTHER;
+  }
+}
+
+
 class _StdIOUtils {
   external static OutputStream _getStdioOutputStream(int fd);
   external static InputStream _getStdioInputStream();
+  external static int _socketType(Socket socket);
 }