sync: Attempt to recover from directory corruption

sync/syncable/directory_backing_store.cc

 // Copyright (c) 2012 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.
 
 #include "sync/syncable/directory_backing_store.h"
 
 #include "build/build_config.h"
 
 #include <limits>
 
 #include "base/base64.h"
+#include "base/debug/trace_event.h"
 #include "base/file_util.h"
 #include "base/hash_tables.h"
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
 #include "base/rand_util.h"
 #include "base/stl_util.h"
 #include "base/string_number_conversions.h"
 #include "base/stringprintf.h"
 #include "base/time.h"
 #include "sql/connection.h"
@@ skipping 1054 matching lines @@
       "id TEXT primary key, "
       "name TEXT, "
       "store_birthday TEXT, "
       "db_create_version TEXT, "
       "db_create_time INT, "
       "next_id INT default -2, "
       "cache_guid TEXT )");
   return db_->Execute(query.c_str());
 }
 
+// This function checks to see if the given list of Metahandles has any nodes
+// whose PREV_ID, PARENT_ID or NEXT_ID values refer to ID values that do not
+// actually exist.  Returns true on success.
+bool DirectoryBackingStore::VerifyReferenceIntegrity(
+    const syncable::MetahandlesIndex &index) {
+  TRACE_EVENT0("sync", "SyncDatabaseIntegrityCheck");
+  using namespace syncable;
+  typedef base::hash_set<std::string> IdsSet;
+
+  IdsSet ids_set;
+  bool is_ok = true;
+
+  for (MetahandlesIndex::const_iterator it = index.begin();
+       it != index.end(); ++it) {
+    EntryKernel* entry = *it;
+    bool is_duplicate_id = !(ids_set.insert(entry->ref(ID).value()).second);
+    is_ok = is_ok && !is_duplicate_id;
+  }
+
+  IdsSet::iterator end = ids_set.end();
+  for (MetahandlesIndex::const_iterator it = index.begin();
+       it != index.end(); ++it) {
+    EntryKernel* entry = *it;
+    bool prev_exists = (ids_set.find(entry->ref(PREV_ID).value()) != end);
+    bool parent_exists = (ids_set.find(entry->ref(PARENT_ID).value()) != end);
+    bool next_exists = (ids_set.find(entry->ref(NEXT_ID).value()) != end);
+    is_ok = is_ok && prev_exists && parent_exists && next_exists;
+  }
+  return is_ok;
+}
+
 }  // namespace syncable
 }  // namespace syncer