[update_engine] Fix file creation mask to be 0600

split_file_writer.h

 // Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROMEOS_PLATFORM_UPDATE_ENGINE_SPLIT_FILE_WRITER_H__
 #define CHROMEOS_PLATFORM_UPDATE_ENGINE_SPLIT_FILE_WRITER_H__
 
 #include "update_engine/file_writer.h"
 
 // SplitFileWriter is an implementation of FileWriter suited to our
 // full autoupdate format. The first 8 bytes read are assumed to be a
 // big-endian number describing how many of the next following bytes
 // go to the first FileWriter. After that, the rest of the bytes all
 // go to the second FileWriter.
 
 namespace chromeos_update_engine {
 
 class SplitFileWriter : public FileWriter {
  public:
   SplitFileWriter(FileWriter* first_file_writer, FileWriter* second_file_writer)
       : first_file_writer_(first_file_writer),
         first_length_(0),
         first_path_(NULL),
         first_flags_(0),
         first_mode_(0),
         second_file_writer_(second_file_writer),
         bytes_received_(0) {}
-  
+
   void SetFirstOpenArgs(const char* path, int flags, mode_t mode) {
     first_path_ = path;
     first_flags_ = flags;
     first_mode_ = mode;
   }
-  
+
   // If both succeed, returns the return value from the second Open() call.
   // On error, both files will be left closed.
   virtual int Open(const char* path, int flags, mode_t mode);
 
   virtual ssize_t Write(const void* bytes, size_t count);
 
   virtual int Close();
 
  private:
   // Data for the first file writer.
   FileWriter* const first_file_writer_;
   off_t first_length_;
   const char* first_path_;
   int first_flags_;
   mode_t first_mode_;
-  
-  // The scond file writeer.
+
+  // The second file writer.
   FileWriter* const second_file_writer_;
 
-  // Bytes written thus far
+  // Bytes written thus far.
   off_t bytes_received_;
   char first_length_buf_[sizeof(uint64_t)];
 
   DISALLOW_COPY_AND_ASSIGN(SplitFileWriter);
 };
 
 }  // namespace chromeos_update_engine
 
 #endif  // CHROMEOS_PLATFORM_UPDATE_ENGINE_SPLIT_FILE_WRITER_H__