Add error handling to directory

runtime/bin/file_impl.dart

 // Copyright (c) 2012, 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.
 
 class _FileInputStream extends _BaseDataInputStream implements InputStream {
   _FileInputStream(String name) {
     _file = new File(name);
     _data = [];
     _position = 0;
     _file.onError = (e) {
@@ skipping 211 matching lines @@
   static final kWriteByteRequest = 13;
   static final kReadListRequest = 14;
   static final kWriteListRequest = 15;
   static final kWriteStringRequest = 16;
 
   static final kSuccessResponse = 0;
   static final kIllegalArgumentResponse = 1;
   static final kOSErrorResponse = 2;
   static final kFileClosedResponse = 3;
 
+  static final kErrorResponseErrorType = 0;
+  static final kOSErrorResponseErrorCode = 1;
+  static final kOSErrorResponseMessage = 2;
+
   static List ensureFastAndSerializableBuffer(
       List buffer, int offset, int bytes) {
     // When using the Dart C API to access raw data, using a ByteArray is
     // currently much faster. This function will make a copy of the
     // supplied List to a ByteArray if it isn't already.
     List outBuffer;
     int outOffset = offset;
     if (buffer is ByteArray || buffer is ObjectArray) {
       outBuffer = buffer;
     } else {
@@ skipping 124 matching lines @@
 
 // Base class for _File and _RandomAccessFile with shared functions.
 class _FileBase {
   bool _isErrorResponse(response) {
     return response is List && response[0] != _FileUtils.kSuccessResponse;
   }
 
   bool _reportError(response, String message) {
     assert(_isErrorResponse(response));
     if (_onError != null) {
-      switch (response[0]) {
+      switch (response[_FileUtil.kErrorResponseErrorType]) {
         case _FileUtils.kIllegalArgumentResponse:
           _onError(new IllegalArgumentException());
           break;
         case _FileUtils.kOSErrorResponse:
-          _onError(new FileIOException(message,
-                                       new OSError(response[2], response[1])));
+          var err = new OSError(response[_FileUtils.kOSErrorResponseErrorCode],
+                                response[_FileUtils.kOSErrorResponseMessage]);
+          _onError(new FileIOException(message, err));
           break;
         case _FileUtils.kFileClosedResponse:
           _onError(new FileIOException("File closed"));
           break;
         default:
           _onError(new Exception("Unknown error"));
           break;
       }
     }
   }
@@ skipping 660 matching lines @@
   String _name;
   int _id;
   int _pendingWrites = 0;
 
   SendPort _fileService;
 
   Timer _noPendingWriteTimer;
 
   Function _onNoPendingWrites;
 }