Add file modes for opening a file write only

runtime/bin/file.h

 // 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.
 
 #ifndef BIN_FILE_H_
 #define BIN_FILE_H_
 
 #include <stdlib.h>
 #include <string.h>
 #include <stdio.h>
 #include <sys/types.h>
 
 #include "bin/builtin.h"
 #include "bin/dartutils.h"
 
 
 namespace dart {
 namespace bin {
 
 // Forward declaration.
 class FileHandle;
 
 class File {
  public:
   enum FileOpenMode {
     kRead = 0,
     kWrite = 1,
     kTruncate = 1 << 2,
-    kWriteTruncate = kWrite | kTruncate
+    kWriteOnly = 1 << 3,
+    kWriteTruncate = kWrite | kTruncate,
+    kWriteOnlyTruncate = kWriteOnly | kTruncate
   };
 
   // These values have to be kept in sync with the mode values of
-  // FileMode.READ, FileMode.WRITE and FileMode.APPEND in file.dart.
+  // FileMode.READ, FileMode.WRITE, FileMode.APPEND,
+  // FileMode.WRITE_ONLY and FileMode.WRITE_ONLY_APPEND in file.dart.
   enum DartFileOpenMode {
     kDartRead = 0,
     kDartWrite = 1,
-    kDartAppend = 2
+    kDartAppend = 2,
+    kDartWriteOnly = 3,
+    kDartWriteOnlyAppend = 4
   };
 
   enum Type {
     kIsFile = 0,
     kIsDirectory = 1,
     kIsLink = 2,
     kDoesNotExist = 3
   };
 
   enum Identical {
@@ skipping 143 matching lines @@
   // FileHandle is an OS specific class which stores data about the file.
   FileHandle* handle_;  // OS specific handle for the file.
 
   DISALLOW_COPY_AND_ASSIGN(File);
 };
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // BIN_FILE_H_