sync: Attempt to recover from directory corruption

sync/syncable/directory_backing_store_unittest.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 "testing/gtest/include/gtest/gtest.h"
 
 #include <string>
 
 #include "base/file_path.h"
 #include "base/file_util.h"
@@ skipping 2065 matching lines @@
 TEST_F(DirectoryBackingStoreTest, ModelTypeIds) {
   for (int i = FIRST_REAL_MODEL_TYPE; i < MODEL_TYPE_COUNT; ++i) {
     std::string model_id =
         TestDirectoryBackingStore::ModelTypeEnumToModelId(ModelTypeFromInt(i));
     EXPECT_EQ(i,
         TestDirectoryBackingStore::ModelIdToModelTypeEnum(model_id.data(),
                                                           model_id.size()));
   }
 }
 
-// TODO(109668): This had to be disabled because the latest API will
-// intentionally crash when a database is this badly corrupted.
-TEST_F(DirectoryBackingStoreTest, DISABLED_Corruption) {
+// This is a whitebox test intended to exercise the code path where the on-disk
+// directory load code decides to delete the current directory and start fresh.
+//
+// Unfortunately, there's no way to tell that this code path is actually
+// exercised by the test.  If the directory failed to detect the corruption, the
+// result would look exactly the same from this level of abstraction.
+//
+// This is considered "minor" corruption because the database recreation is
+// expected to succeed.  The alternative, where recreation does not succeed (ie.
+// due to read-only file system), is not tested here.
+TEST_F(DirectoryBackingStoreTest, MinorCorruption) {
   {
     scoped_ptr<OnDiskDirectoryBackingStore> dbs(
         new OnDiskDirectoryBackingStore(GetUsername(), GetDatabasePath()));
-    EXPECT_TRUE(LoadAndIgnoreReturnedData(dbs.get()));
+    EXPECT_EQ(OPENED, LoadAndIgnoreReturnedData(dbs.get()));
   }
-  std::string bad_data("BAD DATA");
-  EXPECT_TRUE(file_util::WriteFile(GetDatabasePath(), bad_data.data(),
-                                   bad_data.size()));
+
+  // Corrupt the root node.
+  {
+    sql::Connection connection;
+    ASSERT_TRUE(connection.Open(GetDatabasePath()));
+    ASSERT_TRUE(connection.Execute(
+            "UPDATE metas SET parent_id='bogus' WHERE id = 'r';"));
+  }
+
   {
     scoped_ptr<OnDiskDirectoryBackingStore> dbs(
         new OnDiskDirectoryBackingStore(GetUsername(), GetDatabasePath()));
+    dbs->AllowFailureForTest();
 
-    EXPECT_FALSE(LoadAndIgnoreReturnedData(dbs.get()));
+    EXPECT_EQ(OPENED, LoadAndIgnoreReturnedData(dbs.get()));
   }
 }
 
 TEST_F(DirectoryBackingStoreTest, DeleteEntries) {
   sql::Connection connection;
   ASSERT_TRUE(connection.OpenInMemory());
 
   SetUpCurrentDatabaseAndCheckVersion(&connection);
   scoped_ptr<TestDirectoryBackingStore> dbs(
       new TestDirectoryBackingStore(GetUsername(), &connection));
@@ skipping 41 matching lines @@
   const std::string& guid2 = TestDirectoryBackingStore::GenerateCacheGUID();
   EXPECT_EQ(24U, guid1.size());
   EXPECT_EQ(24U, guid2.size());
   // In theory this test can fail, but it won't before the universe
   // dies of heat death.
   EXPECT_NE(guid1, guid2);
 }
 
 }  // namespace syncable
 }  // namespace syncer