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// 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 "webkit/dom_storage/dom_storage_database.h"
#include "base/file_util.h"
#include "base/logging.h"
#include "sql/diagnostic_error_delegate.h"
#include "sql/statement.h"
#include "sql/transaction.h"
#include "third_party/sqlite/sqlite3.h"
namespace {
const base::FilePath::CharType kJournal[] = FILE_PATH_LITERAL("-journal");
class HistogramUniquifier {
public:
static const char* name() { return "Sqlite.DomStorageDatabase.Error"; }
};
sql::ErrorDelegate* GetErrorHandlerForDomStorageDatabase() {
return new sql::DiagnosticErrorDelegate<HistogramUniquifier>();
}
} // anon namespace
namespace dom_storage {
// static
base::FilePath DomStorageDatabase::GetJournalFilePath(
const base::FilePath& database_path) {
base::FilePath::StringType journal_file_name =
database_path.BaseName().value() + kJournal;
return database_path.DirName().Append(journal_file_name);
}
DomStorageDatabase::DomStorageDatabase(const base::FilePath& file_path)
: file_path_(file_path) {
// Note: in normal use we should never get an empty backing path here.
// However, the unit test for this class can contruct an instance
// with an empty path.
Init();
}
DomStorageDatabase::DomStorageDatabase() {
Init();
}
void DomStorageDatabase::Init() {
failed_to_open_ = false;
tried_to_recreate_ = false;
known_to_be_empty_ = false;
}
DomStorageDatabase::~DomStorageDatabase() {
if (known_to_be_empty_ && !file_path_.empty()) {
// Delete the db and any lingering journal file from disk.
Close();
file_util::Delete(file_path_, false);
file_util::Delete(GetJournalFilePath(file_path_), false);
}
}
void DomStorageDatabase::ReadAllValues(ValuesMap* result) {
if (!LazyOpen(false))
return;
sql::Statement statement(db_->GetCachedStatement(SQL_FROM_HERE,
"SELECT * from ItemTable"));
DCHECK(statement.is_valid());
while (statement.Step()) {
string16 key = statement.ColumnString16(0);
string16 value;
statement.ColumnBlobAsString16(1, &value);
(*result)[key] = NullableString16(value, false);
}
known_to_be_empty_ = result->empty();
}
bool DomStorageDatabase::CommitChanges(bool clear_all_first,
const ValuesMap& changes) {
if (!LazyOpen(!changes.empty())) {
// If we're being asked to commit changes that will result in an
// empty database, we return true if the database file doesn't exist.
return clear_all_first && changes.empty() &&
!file_util::PathExists(file_path_);
}
bool old_known_to_be_empty = known_to_be_empty_;
sql::Transaction transaction(db_.get());
if (!transaction.Begin())
return false;
if (clear_all_first) {
if (!db_->Execute("DELETE FROM ItemTable"))
return false;
known_to_be_empty_ = true;
}
bool did_delete = false;
bool did_insert = false;
ValuesMap::const_iterator it = changes.begin();
for(; it != changes.end(); ++it) {
sql::Statement statement;
string16 key = it->first;
NullableString16 value = it->second;
if (value.is_null()) {
statement.Assign(db_->GetCachedStatement(SQL_FROM_HERE,
"DELETE FROM ItemTable WHERE key=?"));
statement.BindString16(0, key);
did_delete = true;
} else {
statement.Assign(db_->GetCachedStatement(SQL_FROM_HERE,
"INSERT INTO ItemTable VALUES (?,?)"));
statement.BindString16(0, key);
statement.BindBlob(1, value.string().data(),
value.string().length() * sizeof(char16));
known_to_be_empty_ = false;
did_insert = true;
}
DCHECK(statement.is_valid());
statement.Run();
}
if (!known_to_be_empty_ && did_delete && !did_insert) {
sql::Statement statement(db_->GetCachedStatement(SQL_FROM_HERE,
"SELECT count(key) from ItemTable"));
if (statement.Step())
known_to_be_empty_ = statement.ColumnInt(0) == 0;
}
bool success = transaction.Commit();
if (!success)
known_to_be_empty_ = old_known_to_be_empty;
return success;
}
bool DomStorageDatabase::LazyOpen(bool create_if_needed) {
if (failed_to_open_) {
// Don't try to open a database that we know has failed
// already.
return false;
}
if (IsOpen())
return true;
bool database_exists = file_util::PathExists(file_path_);
if (!database_exists && !create_if_needed) {
// If the file doesn't exist already and we haven't been asked to create
// a file on disk, then we don't bother opening the database. This means
// we wait until we absolutely need to put something onto disk before we
// do so.
return false;
}
db_.reset(new sql::Connection());
db_->set_error_delegate(GetErrorHandlerForDomStorageDatabase());
if (file_path_.empty()) {
// This code path should only be triggered by unit tests.
if (!db_->OpenInMemory()) {
NOTREACHED() << "Unable to open DOM storage database in memory.";
failed_to_open_ = true;
return false;
}
} else {
if (!db_->Open(file_path_)) {
LOG(ERROR) << "Unable to open DOM storage database at "
<< file_path_.value()
<< " error: " << db_->GetErrorMessage();
if (database_exists && !tried_to_recreate_)
return DeleteFileAndRecreate();
failed_to_open_ = true;
return false;
}
}
// sql::Connection uses UTF-8 encoding, but WebCore style databases use
// UTF-16, so ensure we match.
ignore_result(db_->Execute("PRAGMA encoding=\"UTF-16\""));
if (!database_exists) {
// This is a new database, create the table and we're done!
if (CreateTableV2())
return true;
} else {
// The database exists already - check if we need to upgrade
// and whether it's usable (i.e. not corrupted).
SchemaVersion current_version = DetectSchemaVersion();
if (current_version == V2) {
return true;
} else if (current_version == V1) {
if (UpgradeVersion1To2())
return true;
}
}
// This is the exceptional case - to try and recover we'll attempt
// to delete the file and start again.
Close();
return DeleteFileAndRecreate();
}
DomStorageDatabase::SchemaVersion DomStorageDatabase::DetectSchemaVersion() {
DCHECK(IsOpen());
// Connection::Open() may succeed even if the file we try and open is not a
// database, however in the case that the database is corrupted to the point
// that SQLite doesn't actually think it's a database,
// sql::Connection::GetCachedStatement will DCHECK when we later try and
// run statements. So we run a query here that will not DCHECK but fail
// on an invalid database to verify that what we've opened is usable.
if (db_->ExecuteAndReturnErrorCode("PRAGMA auto_vacuum") != SQLITE_OK)
return INVALID;
// Look at the current schema - if it doesn't look right, assume corrupt.
if (!db_->DoesTableExist("ItemTable") ||
!db_->DoesColumnExist("ItemTable", "key") ||
!db_->DoesColumnExist("ItemTable", "value"))
return INVALID;
// We must use a unique statement here as we aren't going to step it.
sql::Statement statement(
db_->GetUniqueStatement("SELECT key,value from ItemTable LIMIT 1"));
if (statement.DeclaredColumnType(0) != sql::COLUMN_TYPE_TEXT)
return INVALID;
switch (statement.DeclaredColumnType(1)) {
case sql::COLUMN_TYPE_BLOB:
return V2;
case sql::COLUMN_TYPE_TEXT:
return V1;
default:
return INVALID;
}
NOTREACHED();
return INVALID;
}
bool DomStorageDatabase::CreateTableV2() {
DCHECK(IsOpen());
return db_->Execute(
"CREATE TABLE ItemTable ("
"key TEXT UNIQUE ON CONFLICT REPLACE, "
"value BLOB NOT NULL ON CONFLICT FAIL)");
}
bool DomStorageDatabase::DeleteFileAndRecreate() {
DCHECK(!IsOpen());
DCHECK(file_util::PathExists(file_path_));
// We should only try and do this once.
if (tried_to_recreate_)
return false;
tried_to_recreate_ = true;
// If it's not a directory and we can delete the file, try and open it again.
if (!file_util::DirectoryExists(file_path_) &&
file_util::Delete(file_path_, false))
return LazyOpen(true);
failed_to_open_ = true;
return false;
}
bool DomStorageDatabase::UpgradeVersion1To2() {
DCHECK(IsOpen());
DCHECK(DetectSchemaVersion() == V1);
sql::Statement statement(db_->GetCachedStatement(SQL_FROM_HERE,
"SELECT * FROM ItemTable"));
DCHECK(statement.is_valid());
// Need to migrate from TEXT value column to BLOB.
// Store the current database content so we can re-insert
// the data into the new V2 table.
ValuesMap values;
while (statement.Step()) {
string16 key = statement.ColumnString16(0);
NullableString16 value(statement.ColumnString16(1), false);
values[key] = value;
}
sql::Transaction migration(db_.get());
return migration.Begin() &&
db_->Execute("DROP TABLE ItemTable") &&
CreateTableV2() &&
CommitChanges(false, values) &&
migration.Commit();
}
void DomStorageDatabase::Close() {
db_.reset(NULL);
}
} // namespace dom_storage
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