Implement the memory mapped file class for posix.

base/file_util.h

 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This file contains utility functions for dealing with the local
 // filesystem.
 
 #ifndef BASE_FILE_UTIL_H_
 #define BASE_FILE_UTIL_H_
 
@@ skipping 396 matching lines @@
   WIN32_FIND_DATA find_data_;
   HANDLE find_handle_;
 #elif defined(OS_POSIX)
   FTS* fts_;
   FTSENT* fts_ent_;
 #endif
 
   DISALLOW_EVIL_CONSTRUCTORS(FileEnumerator);
 };
 
-// TODO(port): port this class to posix.
-#if defined(OS_WIN)
 class MemoryMappedFile {
  public:
   // The default constructor sets all members to invalid/null values.
   MemoryMappedFile();
   ~MemoryMappedFile();
 
   // Opens an existing file and maps it into memory. Access is restricted to
   // read only. If this object already points to a valid memory mapped file
   // then this method will fail and return false. If it cannot open the file,
   // the file does not exist, or the memory mapping fails, it will return false.
   // Later we may want to allow the user to specify access.
   bool Initialize(const FilePath& file_name);
 
-  const uint8* Data() const { return data_; }
-  size_t Length() const { return length_; }
+  const uint8* data() const { return data_; }
+  size_t length() const { return length_; }
 
   // Is file_ a valid file handle that points to an open, memory mapped file?
   bool IsValid();
 
  private:
   // Map the file to memory, set data_ to that memory address. Return true on
   // success, false on any kind of failure. This is a helper for Initialize().
   bool MapFileToMemory(const FilePath& file_name);
 
   // Closes all open handles. Later we may want to make this public.
   void CloseHandles();
 
+#if defined(OS_WIN)
   HANDLE file_;
   HANDLE file_mapping_;
-  const uint8* data_;
+#elif defined(OS_POSIX)
+  // The file descriptor.
+  int file_;
+#endif
+  uint8* data_;
   size_t length_;
 
   DISALLOW_COPY_AND_ASSIGN(MemoryMappedFile);
 };
-#endif  // defined(OS_WIN)
 
 // Renames a file using the SHFileOperation API to ensure that the target file
 // gets the correct default security descriptor in the new path.
 bool RenameFileAndResetSecurityDescriptor(
     const std::wstring& source_file_path,
     const std::wstring& target_file_path);
 
 }  // namespace file_util
 
 #endif  // BASE_FILE_UTIL_H_