components/webdata/common/web_database.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "components/webdata/common/web_database.h"
   6
   7 #include <algorithm>
   8
   9 #include "base/stl_util.h"
  10 #include "sql/statement.h"
  11 #include "sql/transaction.h"
  12
  13 // Current version number.  Note: when changing the current version number,
  14 // corresponding changes must happen in the unit tests, and new migration test
  15 // added.  See |WebDatabaseMigrationTest::kCurrentTestedVersionNumber|.
  16 // static
  17 const int WebDatabase::kCurrentVersionNumber = 56;
  18
  19 namespace {
  20
  21 const int kCompatibleVersionNumber = 56;
  22
  23 // Change the version number and possibly the compatibility version of
  24 // |meta_table_|.
  25 void ChangeVersion(sql::MetaTable* meta_table,
  26                    int version_num,
  27                    bool update_compatible_version_num) {
  28   meta_table->SetVersionNumber(version_num);
  29   if (update_compatible_version_num) {
  30     meta_table->SetCompatibleVersionNumber(
  31           std::min(version_num, kCompatibleVersionNumber));
  32   }
  33 }
  34
  35 // Outputs the failed version number as a warning and always returns
  36 // |sql::INIT_FAILURE|.
  37 sql::InitStatus FailedMigrationTo(int version_num) {
  38   LOG(WARNING) << "Unable to update web database to version "
  39                << version_num << ".";
  40   NOTREACHED();
  41   return sql::INIT_FAILURE;
  42 }
  43
  44 }  // namespace
  45
  46 WebDatabase::WebDatabase() {}
  47
  48 WebDatabase::~WebDatabase() {
  49 }
  50
  51 void WebDatabase::AddTable(WebDatabaseTable* table) {
  52   tables_[table->GetTypeKey()] = table;
  53 }
  54
  55 WebDatabaseTable* WebDatabase::GetTable(WebDatabaseTable::TypeKey key) {
  56   return tables_[key];
  57 }
  58
  59 void WebDatabase::BeginTransaction() {
  60   db_.BeginTransaction();
  61 }
  62
  63 void WebDatabase::CommitTransaction() {
  64   db_.CommitTransaction();
  65 }
  66
  67 sql::Connection* WebDatabase::GetSQLConnection() {
  68   return &db_;
  69 }
  70
  71 sql::InitStatus WebDatabase::Init(const base::FilePath& db_name) {
  72   db_.set_histogram_tag("Web");
  73
  74   // We don't store that much data in the tables so use a small page size.
  75   // This provides a large benefit for empty tables (which is very likely with
  76   // the tables we create).
  77   db_.set_page_size(2048);
  78
  79   // We shouldn't have much data and what access we currently have is quite
  80   // infrequent. So we go with a small cache size.
  81   db_.set_cache_size(32);
  82
  83   // Run the database in exclusive mode. Nobody else should be accessing the
  84   // database while we're running, and this will give somewhat improved perf.
  85   db_.set_exclusive_locking();
  86
  87   if (!db_.Open(db_name))
  88     return sql::INIT_FAILURE;
  89
  90   // Initialize various tables
  91   sql::Transaction transaction(&db_);
  92   if (!transaction.Begin())
  93     return sql::INIT_FAILURE;
  94
  95   // Version check.
  96   if (!meta_table_.Init(&db_, kCurrentVersionNumber, kCompatibleVersionNumber))
  97     return sql::INIT_FAILURE;
  98   if (meta_table_.GetCompatibleVersionNumber() > kCurrentVersionNumber) {
  99     LOG(WARNING) << "Web database is too new.";
 100     return sql::INIT_TOO_NEW;
 101   }
 102
 103   // Initialize the tables.
 104   for (TableMap::iterator it = tables_.begin(); it != tables_.end(); ++it) {
 105     it->second->Init(&db_, &meta_table_);
 106   }
 107
 108   // If the file on disk is an older database version, bring it up to date.
 109   // If the migration fails we return an error to caller and do not commit
 110   // the migration.
 111   sql::InitStatus migration_status = MigrateOldVersionsAsNeeded();
 112   if (migration_status != sql::INIT_OK)
 113     return migration_status;
 114
 115   // Create the desired SQL tables if they do not already exist.
 116   // It's important that this happen *after* the migration code runs.
 117   // Otherwise, the migration code would have to explicitly check for empty
 118   // tables created in the new format, and skip the migration in that case.
 119   for (TableMap::iterator it = tables_.begin(); it != tables_.end(); ++it) {
 120     if (!it->second->CreateTablesIfNecessary()) {
 121       LOG(WARNING) << "Unable to initialize the web database.";
 122       return sql::INIT_FAILURE;
 123     }
 124   }
 125
 126   return transaction.Commit() ? sql::INIT_OK : sql::INIT_FAILURE;
 127 }
 128
 129 sql::InitStatus WebDatabase::MigrateOldVersionsAsNeeded() {
 130   // Some malware used to lower the version number, causing migration to
 131   // fail. Ensure the version number is at least as high as the compatible
 132   // version number.
 133   int current_version = std::max(meta_table_.GetVersionNumber(),
 134                                  meta_table_.GetCompatibleVersionNumber());
 135   if (current_version > meta_table_.GetVersionNumber())
 136     ChangeVersion(&meta_table_, current_version, false);
 137
 138   if (current_version < 20) {
 139     // Versions 1 - 19 are unhandled.  Version numbers greater than
 140     // kCurrentVersionNumber should have already been weeded out by the caller.
 141     //
 142     // When the version is too old, we return failure error code.  The schema
 143     // is too out of date to migrate.
 144     //
 145     // There should not be a released product that makes a database too old to
 146     // migrate. If we do encounter such a legacy database, we will need a
 147     // better solution to handle it (i.e., pop up a dialog to tell the user,
 148     // erase all their prefs and start over, etc.).
 149     LOG(WARNING) << "Web database version " << current_version
 150                  << " is too old to handle.";
 151     NOTREACHED();
 152     return sql::INIT_FAILURE;
 153   }
 154
 155   for (int next_version = current_version + 1;
 156        next_version <= kCurrentVersionNumber;
 157        ++next_version) {
 158     // Give each table a chance to migrate to this version.
 159     for (TableMap::iterator it = tables_.begin(); it != tables_.end(); ++it) {
 160       // Any of the tables may set this to true, but by default it is false.
 161       bool update_compatible_version = false;
 162       if (!it->second->MigrateToVersion(next_version,
 163                                         &update_compatible_version)) {
 164         return FailedMigrationTo(next_version);
 165       }
 166
 167       ChangeVersion(&meta_table_, next_version, update_compatible_version);
 168     }
 169   }
 170   return sql::INIT_OK;
 171 }