chromeos: Perform strict check on parent-shild relationship of DriveResourceMetadata DB

chrome/browser/chromeos/drive/drive_resource_metadata_storage.cc

 // 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.
 
 #include "chrome/browser/chromeos/drive/drive_resource_metadata_storage.h"
 
 #include "base/callback.h"
 #include "base/file_util.h"
 #include "base/logging.h"
 #include "base/threading/thread_restrictions.h"
@@ skipping 432 matching lines @@
       it->key() != GetHeaderDBKey() ||  // Header entry must come first.
       !header.ParseFromArray(it->value().data(), it->value().size()) ||
       header.version() != kDBVersion) {
     DLOG(ERROR) << "Invalid header detected. version = " << header.version();
     return false;
   }
 
   // Check all entires.
   size_t num_checked_child_map_entries = 0;
   DriveEntryProto entry;
+  std::string serialized_parent_entry;
   std::string child_resource_id;
   for (it->Next(); it->Valid(); it->Next()) {
     // Check if stored data is broken.
     if (!entry.ParseFromArray(it->value().data(), it->value().size()) ||
         entry.resource_id() != it->key()) {
       DLOG(ERROR) << "Broken entry detected";
       return false;
     }
 
-    // Check if parent-child relationship is stored correctly.
     if (!entry.parent_resource_id().empty()) {
-      leveldb::Status status = child_map_->Get(
+      // Check if the parent entry is stored.
+      leveldb::Status status = resource_map_->Get(
+          options,
+          leveldb::Slice(entry.parent_resource_id()),
+          &serialized_parent_entry);
+      if (!status.ok()) {
+        DLOG(ERROR) << "Can't get parent entry. status = " << status.ToString();
+        return false;
+      }
+
+      // Check if parent-child relationship is stored correctly.
+      status = child_map_->Get(
           options,
           leveldb::Slice(GetChildMapKey(entry.parent_resource_id(),
                                         entry.base_name())),
           &child_resource_id);
       if (!status.ok() || child_resource_id != entry.resource_id()) {
         DLOG(ERROR) << "Child map is broken. status = " << status.ToString();
         return false;
       }
       ++num_checked_child_map_entries;
     }
@@ skipping 14 matching lines @@
       num_child_map_entries != num_checked_child_map_entries) {
     DLOG(ERROR) << "Error during checking child map. status = "
                 << it->status().ToString();
     return false;
   }
 
   return true;
 }
 
 }  // namespace drive