base/files/memory_mapped_file.h

   1 // Copyright 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef BASE_FILES_MEMORY_MAPPED_FILE_H_
   6 #define BASE_FILES_MEMORY_MAPPED_FILE_H_
   7
   8 #include "base/base_export.h"
   9 #include "base/basictypes.h"
  10 #include "base/platform_file.h"
  11 #include "build/build_config.h"
  12
  13 #if defined(OS_WIN)
  14 #include <windows.h>
  15 #endif
  16
  17 namespace base {
  18
  19 class FilePath;
  20
  21 class BASE_EXPORT MemoryMappedFile {
  22  public:
  23   // The default constructor sets all members to invalid/null values.
  24   MemoryMappedFile();
  25   ~MemoryMappedFile();
  26
  27   // Opens an existing file and maps it into memory. Access is restricted to
  28   // read only. If this object already points to a valid memory mapped file
  29   // then this method will fail and return false. If it cannot open the file,
  30   // the file does not exist, or the memory mapping fails, it will return false.
  31   // Later we may want to allow the user to specify access.
  32   bool Initialize(const FilePath& file_name);
  33   // As above, but works with an already-opened file. MemoryMappedFile will take
  34   // ownership of |file| and close it when done.
  35   bool Initialize(PlatformFile file);
  36
  37 #if defined(OS_WIN)
  38   // Opens an existing file and maps it as an image section. Please refer to
  39   // the Initialize function above for additional information.
  40   bool InitializeAsImageSection(const FilePath& file_name);
  41 #endif  // OS_WIN
  42
  43   const uint8* data() const { return data_; }
  44   size_t length() const { return length_; }
  45
  46   // Is file_ a valid file handle that points to an open, memory mapped file?
  47   bool IsValid() const;
  48
  49  private:
  50   // Open the given file and pass it to MapFileToMemoryInternal().
  51   bool MapFileToMemory(const FilePath& file_name);
  52
  53   // Map the file to memory, set data_ to that memory address. Return true on
  54   // success, false on any kind of failure. This is a helper for Initialize().
  55   bool MapFileToMemoryInternal();
  56
  57   // Closes all open handles. Later we may want to make this public.
  58   void CloseHandles();
  59
  60 #if defined(OS_WIN)
  61   // MapFileToMemoryInternal calls this function. It provides the ability to
  62   // pass in flags which control the mapped section.
  63   bool MapFileToMemoryInternalEx(int flags);
  64
  65   HANDLE file_mapping_;
  66 #endif
  67   PlatformFile file_;
  68   uint8* data_;
  69   size_t length_;
  70
  71   DISALLOW_COPY_AND_ASSIGN(MemoryMappedFile);
  72 };
  73
  74 }  // namespace base
  75
  76 #endif  // BASE_FILES_MEMORY_MAPPED_FILE_H_