net/disk_cache/simple/simple_version_upgrade.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 NET_DISK_CACHE_SIMPLE_SIMPLE_VERSION_UPGRADE_H_
   6 #define NET_DISK_CACHE_SIMPLE_SIMPLE_VERSION_UPGRADE_H_
   7
   8 // Defines functionality to upgrade the file structure of the Simple Cache
   9 // Backend on disk. Assumes no backend operations are running simultaneously.
  10 // Hence must be run at cache initialization step.
  11
  12 #include "base/basictypes.h"
  13 #include "net/base/net_export.h"
  14
  15 namespace base {
  16 class FilePath;
  17 }
  18
  19 namespace disk_cache {
  20
  21 // Performs all necessary disk IO to upgrade the cache structure if it is
  22 // needed.
  23 //
  24 // Returns true iff no errors were found during consistency checks and all
  25 // necessary transitions succeeded. If this function fails, there is nothing
  26 // left to do other than dropping the whole cache directory.
  27 NET_EXPORT_PRIVATE bool UpgradeSimpleCacheOnDisk(const base::FilePath& path);
  28
  29 // The format for the fake index has mistakenly acquired two extra fields that
  30 // do not contain any useful data. Since they were equal to zero, they are now
  31 // mandatated to be zero.
  32 struct NET_EXPORT_PRIVATE FakeIndexData {
  33   FakeIndexData();
  34
  35   // Must be equal to simplecache_v4::kSimpleInitialMagicNumber.
  36   uint64 initial_magic_number;
  37
  38   // Must be equal kSimpleVersion when the cache backend is instantiated.
  39   uint32 version;
  40
  41   uint32 unused_must_be_zero1;
  42   uint32 unused_must_be_zero2;
  43 };
  44
  45 // Exposed for testing.
  46 NET_EXPORT_PRIVATE bool UpgradeIndexV5V6(const base::FilePath& cache_directory);
  47
  48 }  // namespace disk_cache
  49
  50 #endif  // NET_DISK_CACHE_SIMPLE_SIMPLE_VERSION_UPGRADE_H_