text: // Copyright 2013 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.
  
  #ifndef NET_DISK_CACHE_SIMPLE_SIMPLE_VERSION_UPGRADE_H_
  #define NET_DISK_CACHE_SIMPLE_SIMPLE_VERSION_UPGRADE_H_
  
  // Defines functionality to upgrade the file structure of the Simple Cache
  // Backend on disk. Assumes no backend operations are running simultaneously.
  // Hence must be run at cache initialization step.
  
  #include "base/basictypes.h"
  #include "net/base/net_export.h"
  
  namespace base {
  class FilePath;
  }
  
  namespace disk_cache {
  
  // Performs all necessary disk IO to upgrade the cache structure if it is
  // needed.
  //
  // Returns true iff no errors were found during consistency checks and all
  // necessary transitions succeeded. If this function fails, there is nothing
  // left to do other than dropping the whole cache directory.
  NET_EXPORT_PRIVATE bool UpgradeSimpleCacheOnDisk(const base::FilePath& path);
  
  // The format for the fake index has mistakenly acquired two extra fields that
  // do not contain any useful data. Since they were equal to zero, they are now
  // mandatated to be zero.
  struct NET_EXPORT_PRIVATE FakeIndexData {
    FakeIndexData();
  
    // Must be equal to simplecache_v4::kSimpleInitialMagicNumber.
    uint64 initial_magic_number;
  
    // Must be equal kSimpleVersion when the cache backend is instantiated.
    uint32 version;
  
    uint32 unused_must_be_zero1;
    uint32 unused_must_be_zero2;
  };
  
  // Exposed for testing.
  NET_EXPORT_PRIVATE bool UpgradeIndexV5V6(const base::FilePath& cache_directory);
  
  }  // namespace disk_cache
  
  #endif  // NET_DISK_CACHE_SIMPLE_SIMPLE_VERSION_UPGRADE_H_
  