Parse the hash prefix map from the V4Store on disk.

components/safe_browsing_db/v4_store.cc

 // Copyright 2016 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 "base/base64.h"
 #include "base/bind.h"
 #include "base/files/file_util.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/metrics/sparse_histogram.h"
 #include "base/strings/stringprintf.h"
@@ skipping 22 matching lines @@
 void RecordStoreWriteResult(StoreWriteResult result) {
   UMA_HISTOGRAM_ENUMERATION("SafeBrowsing.V4StoreWriteResult", result,
                             STORE_WRITE_RESULT_MAX);
 }
 
 void RecordApplyUpdateResult(ApplyUpdateResult result) {
   UMA_HISTOGRAM_ENUMERATION("SafeBrowsing.V4ApplyUpdateResult", result,
                             APPLY_UPDATE_RESULT_MAX);
 }
 
+void RecordApplyUpdateResultWhenReadingFromDisk(ApplyUpdateResult result) {
+  UMA_HISTOGRAM_ENUMERATION(
+      "SafeBrowsing.V4ApplyUpdateResultWhenReadingFromDisk", result,
+      APPLY_UPDATE_RESULT_MAX);
+}
+
 // Returns the name of the temporary file used to buffer data for
 // |filename|.  Exported for unit tests.
 const base::FilePath TemporaryFileForFilename(const base::FilePath& filename) {
   return base::FilePath(filename.value() + FILE_PATH_LITERAL("_new"));
 }
 
 }  // namespace
 
 std::ostream& operator<<(std::ostream& os, const V4Store& store) {
   os << store.DebugString();
@@ skipping 299 matching lines @@
   if (file_format.version_number() != kFileVersion) {
     DVLOG(1) << "File version incompatible: " << file_format.version_number()
              << "; expected: " << kFileVersion;
     return FILE_VERSION_INCOMPATIBLE_FAILURE;
   }
 
   if (!file_format.has_list_update_response()) {
     return HASH_PREFIX_INFO_MISSING_FAILURE;
   }
 
-  ListUpdateResponse list_update_response = file_format.list_update_response();
-  state_ = list_update_response.new_client_state();
-  // TODO(vakh): Do more with what's read from the disk.
+  const ListUpdateResponse& response = file_format.list_update_response();
+  ApplyUpdateResult apply_update_result = UpdateHashPrefixMapFromAdditions(
+      response.additions(), &hash_prefix_map_);
+  RecordApplyUpdateResultWhenReadingFromDisk(apply_update_result);
+  if (apply_update_result != APPLY_UPDATE_SUCCESS) {
+    hash_prefix_map_.clear();
+    return HASH_PREFIX_MAP_GENERATION_FAILURE;
+  }
 
+  state_ = response.new_client_state();
   return READ_SUCCESS;
 }
 
 StoreWriteResult V4Store::WriteToDisk(
     std::unique_ptr<ListUpdateResponse> response) const {
   // Do not write partial updates to the disk.
   // After merging the updates, the ListUpdateResponse passed to this method
   // should be a FULL_UPDATE.
   if (!response->has_response_type() ||
       response->response_type() != ListUpdateResponse::FULL_UPDATE) {
@@ skipping 20 matching lines @@
 
   if (!base::Move(new_filename, store_path_)) {
     DVLOG(1) << "store_path_: " << store_path_.value();
     return UNABLE_TO_RENAME_FAILURE;
   }
 
   return WRITE_SUCCESS;
 }
 
 }  // namespace safe_browsing