[Offline Pages] Fix crash due to table inconsistency.

components/offline_pages/offline_page_metadata_store_sql.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 "components/offline_pages/offline_page_metadata_store_sql.h"
 
 #include "base/bind.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/sequenced_task_runner.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "components/offline_pages/offline_page_item.h"
 #include "sql/connection.h"
 #include "sql/statement.h"
 #include "sql/transaction.h"
 
 namespace offline_pages {
 
 namespace {
 
 // This is a macro instead of a const so that
 // it can be used inline in other SQL statements below.
 #define OFFLINE_PAGES_TABLE_NAME "offlinepages_v1"
 
+// New columns should be added at the end of the list in order to avoid
+// complicated table upgrade.
 const char kOfflinePagesColumns[] =
     "(offline_id INTEGER PRIMARY KEY NOT NULL,"
     " creation_time INTEGER NOT NULL,"
     " file_size INTEGER NOT NULL,"
     " version INTEGER NOT NULL,"
     " last_access_time INTEGER NOT NULL,"
     " access_count INTEGER NOT NULL,"
     " status INTEGER NOT NULL DEFAULT 0,"
     // A note on this field:  It will be NULL for now and is reserved for
     // later use.  We will treat NULL as "Unknown" in any subsequent queries
     // for user_initiated values.
     " user_initiated INTEGER,"  // this is actually a boolean
-    " expiration_time INTEGER NOT NULL,"
+    " expiration_time INTEGER NOT NULL DEFAULT 0,"
     " client_namespace VARCHAR NOT NULL,"
     " client_id VARCHAR NOT NULL,"
     " online_url VARCHAR NOT NULL,"
     " offline_url VARCHAR NOT NULL DEFAULT '',"
     " file_path VARCHAR NOT NULL"
     ")";
 
 // This is cloned from //content/browser/appcache/appcache_database.cc
 struct TableInfo {
   const char* table_name;
@@ skipping 22 matching lines @@
   OP_FILE_PATH,
 };
 
 bool CreateTable(sql::Connection* db, const TableInfo& table_info) {
   std::string sql("CREATE TABLE ");
   sql += table_info.table_name;
   sql += table_info.columns;
   return db->Execute(sql.c_str());
 }
 
+bool RefreshColumns(sql::Connection* db) {
+  if (!db->Execute("ALTER TABLE " OFFLINE_PAGES_TABLE_NAME
+                   " RENAME TO temp_" OFFLINE_PAGES_TABLE_NAME)) {
+    return false;
+  }
+  if (!CreateTable(db, kOfflinePagesTable))
+    return false;
+  if (!db->Execute(
+          "INSERT INTO " OFFLINE_PAGES_TABLE_NAME
+          " (offline_id, creation_time, file_size, version, last_access_time, "
+          "access_count, status, user_initiated, client_namespace, client_id, "
+          "online_url, offline_url, file_path) "
+          "SELECT offline_id, creation_time, file_size, version, "
+          "last_access_time, "
+          "access_count, status, user_initiated, client_namespace, client_id, "
+          "online_url, offline_url, file_path "
+          "FROM temp_" OFFLINE_PAGES_TABLE_NAME)) {
+    return false;
+  }
+  if (!db->Execute("DROP TABLE IF EXISTS temp_" OFFLINE_PAGES_TABLE_NAME))
+    return false;
+
+  return true;
+}
+
 bool CreateSchema(sql::Connection* db) {
   // If you create a transaction but don't Commit() it is automatically
   // rolled back by its destructor when it falls out of scope.
   sql::Transaction transaction(db);
   if (!transaction.Begin())
     return false;
-  if (db->DoesTableExist(kOfflinePagesTable.table_name))
-    return true;
 
-  if (!CreateTable(db, kOfflinePagesTable))
-    return false;
+  if (!db->DoesTableExist(kOfflinePagesTable.table_name)) {
+    if (!CreateTable(db, kOfflinePagesTable))
+      return false;
+  }
+
+  if (!db->DoesColumnExist(kOfflinePagesTable.table_name, "expiration_time")) {
+    if (!RefreshColumns(db))
+      return false;
+  }
 
   // TODO(bburns): Add indices here.
   return transaction.Commit();
 }
 
 bool DeleteByOfflineId(sql::Connection* db, int64_t offline_id) {
   static const char kSql[] =
       "DELETE FROM " OFFLINE_PAGES_TABLE_NAME " WHERE offline_id=?";
   sql::Statement statement(db->GetCachedStatement(SQL_FROM_HERE, kSql));
   statement.BindInt64(0, offline_id);
@@ skipping 224 matching lines @@
 }
 
 void OfflinePageMetadataStoreSQL::Reset(const ResetCallback& callback) {
   background_task_runner_->PostTask(
       FROM_HERE,
       base::Bind(&OfflinePageMetadataStoreSQL::ResetSync, base::Passed(&db_),
                  base::ThreadTaskRunnerHandle::Get(), callback));
 }
 
 }  // namespace offline_pages