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      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 #include "chrome/browser/sync_file_system/drive_backend/metadata_db_migration_util.h"
      6 
      7 #include "base/files/file_path.h"
      8 #include "base/memory/scoped_ptr.h"
      9 #include "base/strings/string_util.h"
     10 #include "chrome/browser/sync_file_system/drive_backend/drive_backend_util.h"
     11 #include "storage/common/fileapi/file_system_types.h"
     12 #include "storage/common/fileapi/file_system_util.h"
     13 #include "third_party/leveldatabase/src/include/leveldb/db.h"
     14 #include "third_party/leveldatabase/src/include/leveldb/write_batch.h"
     15 #include "url/gurl.h"
     16 
     17 namespace sync_file_system {
     18 namespace drive_backend {
     19 
     20 SyncStatusCode MigrateDatabaseFromV4ToV3(leveldb::DB* db) {
     21   // Rollback from version 4 to version 3.
     22   // Please see metadata_database_index.cc for version 3 format, and
     23   // metadata_database_index_on_disk.cc for version 4 format.
     24 
     25   const char kDatabaseVersionKey[] = "VERSION";
     26   const char kServiceMetadataKey[] = "SERVICE";
     27   const char kFileMetadataKeyPrefix[] = "FILE: ";
     28   const char kFileTrackerKeyPrefix[] = "TRACKER: ";
     29 
     30   // Key prefixes used in version 4.
     31   const char kAppRootIDByAppIDKeyPrefix[] = "APP_ROOT: ";
     32   const char kActiveTrackerIDByFileIDKeyPrefix[] = "ACTIVE_FILE: ";
     33   const char kTrackerIDByFileIDKeyPrefix[] = "TRACKER_FILE: ";
     34   const char kMultiTrackerByFileIDKeyPrefix[] = "MULTI_FILE: ";
     35   const char kActiveTrackerIDByParentAndTitleKeyPrefix[] = "ACTIVE_PATH: ";
     36   const char kTrackerIDByParentAndTitleKeyPrefix[] = "TRACKER_PATH: ";
     37   const char kMultiBackingParentAndTitleKeyPrefix[] = "MULTI_PATH: ";
     38   const char kDirtyIDKeyPrefix[] = "DIRTY: ";
     39   const char kDemotedDirtyIDKeyPrefix[] = "DEMOTED_DIRTY: ";
     40 
     41   leveldb::WriteBatch write_batch;
     42   write_batch.Put(kDatabaseVersionKey, "3");
     43 
     44   scoped_ptr<leveldb::Iterator> itr(db->NewIterator(leveldb::ReadOptions()));
     45   for (itr->SeekToFirst(); itr->Valid(); itr->Next()) {
     46     std::string key = itr->key().ToString();
     47 
     48     // Do nothing for valid entries in both versions.
     49     if (StartsWithASCII(key, kServiceMetadataKey, true) ||
     50         StartsWithASCII(key, kFileMetadataKeyPrefix, true) ||
     51         StartsWithASCII(key, kFileTrackerKeyPrefix, true)) {
     52       continue;
     53     }
     54 
     55     // Drop entries used in version 4 only.
     56     if (StartsWithASCII(key, kAppRootIDByAppIDKeyPrefix, true) ||
     57         StartsWithASCII(key, kActiveTrackerIDByFileIDKeyPrefix, true) ||
     58         StartsWithASCII(key, kTrackerIDByFileIDKeyPrefix, true) ||
     59         StartsWithASCII(key, kMultiTrackerByFileIDKeyPrefix, true) ||
     60         StartsWithASCII(key, kActiveTrackerIDByParentAndTitleKeyPrefix, true) ||
     61         StartsWithASCII(key, kTrackerIDByParentAndTitleKeyPrefix, true) ||
     62         StartsWithASCII(key, kMultiBackingParentAndTitleKeyPrefix, true) ||
     63         StartsWithASCII(key, kDirtyIDKeyPrefix, true) ||
     64         StartsWithASCII(key, kDemotedDirtyIDKeyPrefix, true)) {
     65       write_batch.Delete(key);
     66       continue;
     67     }
     68 
     69     DVLOG(3) << "Unknown key: " << key << " was found.";
     70   }
     71 
     72   return LevelDBStatusToSyncStatusCode(
     73       db->Write(leveldb::WriteOptions(), &write_batch));
     74 }
     75 
     76 }  // namespace drive_backend
     77 }  // namespace sync_file_system
     78