QtQuick.LocalStorage: Make plugin optional

This moves the LocalStorage types into a new library and is meant to make
them availabe to the QML compiler at some point in the future.

Task-number: QTBUG-90487
Change-Id: I57ae8dc45a9ef3d5221520f656a2475bca2eb453
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

4 files changed, 969 insertions, 0 deletions

diff --git a/src/qmllocalstorage/CMakeLists.txt b/src/qmllocalstorage/CMakeLists.txt
new file mode 100644
index 0000000000..7c6846dce1
--- /dev/null
+++ b/src/qmllocalstorage/CMakeLists.txt
@@ -0,0 +1,23 @@
+qt_internal_add_module(QmlLocalStorage
+    GENERATE_METATYPES
+    SOURCES
+        qqmllocalstorage.cpp qqmllocalstorage_p.h
+        qqmllocalstorageglobal_p.h
+    DEFINES
+        QT_BUILD_QMLLOCALSTORAGE_LIB
+    PUBLIC_LIBRARIES
+        Qt::CorePrivate
+        Qt::QmlPrivate
+        Qt::Sql
+)
+
+set_target_properties(QmlLocalStorage PROPERTIES
+    QT_QML_MODULE_INSTALL_QMLTYPES TRUE
+    QT_QML_MODULE_VERSION ${CMAKE_PROJECT_VERSION}
+    QT_QML_MODULE_URI QtQuick.LocalStorage
+    QT_QMLTYPES_FILENAME plugins.qmltypes
+    QT_QML_MODULE_INSTALL_DIR "${INSTALL_QMLDIR}/QtQuick/LocalStorage"
+)
+
+
+qt6_qml_type_registration(QmlLocalStorage)
diff --git a/src/qmllocalstorage/qqmllocalstorage.cpp b/src/qmllocalstorage/qqmllocalstorage.cpp
new file mode 100644
index 0000000000..56b48189ba
--- /dev/null
+++ b/src/qmllocalstorage/qqmllocalstorage.cpp
@@ -0,0 +1,793 @@
+/****************************************************************************
+**
+** Copyright (C) 2019 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qqmllocalstorage_p.h"
+
+#include <QtQml/private/qqmlengine_p.h>
+#include <QtQml/private/qv4global_p.h>
+#include <QtQml/private/qv4scopedvalue_p.h>
+#include <QtQml/private/qv4object_p.h>
+#include <QtQml/private/qv4sqlerrors_p.h>
+#include <QtQml/private/qv4jscall_p.h>
+#include <QtQml/private/qv4objectiterator_p.h>
+
+#include <QtCore/qfileinfo.h>
+#include <QtCore/qdir.h>
+
+#include <QtSql/qsqldatabase.h>
+#include <QtSql/qsqlquery.h>
+#include <QtSql/qsqlrecord.h>
+#include <QtSql/qsqlerror.h>
+
+#if QT_CONFIG(settings)
+#include <QtCore/qsettings.h>
+#endif
+
+QT_BEGIN_NAMESPACE
+
+#define V4THROW_SQL(error, desc) { \
+    QV4::ScopedString v(scope, scope.engine->newString(desc)); \
+    QV4::ScopedObject ex(scope, scope.engine->newErrorObject(v)); \
+    ex->put(QV4::ScopedString(scope, scope.engine->newIdentifier(QStringLiteral("code"))).getPointer(), QV4::ScopedValue(scope, Value::fromInt32(error))); \
+    scope.engine->throwError(ex); \
+    RETURN_UNDEFINED(); \
+}
+
+#define V4THROW_SQL2(error, desc) { \
+    QV4::ScopedString v(scope, scope.engine->newString(desc)); \
+    QV4::ScopedObject ex(scope, scope.engine->newErrorObject(v)); \
+    ex->put(QV4::ScopedString(scope, scope.engine->newIdentifier(QStringLiteral("code"))).getPointer(), QV4::ScopedValue(scope, Value::fromInt32(error))); \
+    args->setReturnValue(scope.engine->throwError(ex)); \
+    return; \
+}
+
+#define V4THROW_REFERENCE(string) { \
+    QV4::ScopedString v(scope, scope.engine->newString(string)); \
+    scope.engine->throwReferenceError(v); \
+    RETURN_UNDEFINED(); \
+}
+
+
+class QQmlSqlDatabaseData : public QV4::ExecutionEngine::Deletable
+{
+public:
+    QQmlSqlDatabaseData(QV4::ExecutionEngine *engine);
+    ~QQmlSqlDatabaseData() override;
+
+    QV4::PersistentValue databaseProto;
+    QV4::PersistentValue queryProto;
+    QV4::PersistentValue rowsProto;
+};
+
+V4_DEFINE_EXTENSION(QQmlSqlDatabaseData, databaseData)
+
+namespace QV4 {
+
+namespace Heap {
+    struct QQmlSqlDatabaseWrapper : public Object {
+        enum Type { Database, Query, Rows };
+        void init()
+        {
+            Object::init();
+            type = Database;
+            database = new QSqlDatabase;
+            version = new QString;
+            sqlQuery = new QSqlQuery;
+        }
+
+        void destroy() {
+            delete database;
+            delete version;
+            delete sqlQuery;
+            Object::destroy();
+        }
+
+        Type type;
+        QSqlDatabase *database;
+
+        QString *version; // type == Database
+
+        bool inTransaction; // type == Query
+        bool readonly;   // type == Query
+
+        QSqlQuery *sqlQuery; // type == Rows
+        bool forwardOnly; // type == Rows
+    };
+}
+
+class QQmlSqlDatabaseWrapper : public Object
+{
+public:
+    V4_OBJECT2(QQmlSqlDatabaseWrapper, Object)
+    V4_NEEDS_DESTROY
+
+    static Heap::QQmlSqlDatabaseWrapper *create(QV4::ExecutionEngine *engine)
+    {
+        return engine->memoryManager->allocate<QQmlSqlDatabaseWrapper>();
+    }
+
+    ~QQmlSqlDatabaseWrapper() {
+    }
+
+    static ReturnedValue virtualGet(const Managed *m, PropertyKey id, const Value *receiver, bool *hasProperty);
+};
+
+}
+
+using namespace QV4;
+
+DEFINE_OBJECT_VTABLE(QV4::QQmlSqlDatabaseWrapper);
+
+
+
+static ReturnedValue qmlsqldatabase_version(const FunctionObject *b, const Value *thisObject, const QV4::Value *, int)
+{
+    Scope scope(b);
+    QV4::Scoped<QQmlSqlDatabaseWrapper> r(scope, thisObject->as<QQmlSqlDatabaseWrapper>());
+    if (!r || r->d()->type != Heap::QQmlSqlDatabaseWrapper::Database)
+        V4THROW_REFERENCE("Not a SQLDatabase object");
+
+    RETURN_RESULT(Encode(scope.engine->newString(*r->d()->version)));
+}
+
+static ReturnedValue qmlsqldatabase_rows_length(const FunctionObject *b, const Value *thisObject, const QV4::Value *, int)
+{
+    Scope scope(b);
+    QV4::Scoped<QQmlSqlDatabaseWrapper> r(scope, thisObject->as<QQmlSqlDatabaseWrapper>());
+    if (!r || r->d()->type != Heap::QQmlSqlDatabaseWrapper::Rows)
+        V4THROW_REFERENCE("Not a SQLDatabase::Rows object");
+
+    int s = r->d()->sqlQuery->size();
+    if (s < 0) {
+        // Inefficient
+        if (r->d()->sqlQuery->last()) {
+            s = r->d()->sqlQuery->at() + 1;
+        } else {
+            s = 0;
+        }
+    }
+    RETURN_RESULT(Encode(s));
+}
+
+static ReturnedValue qmlsqldatabase_rows_forwardOnly(const FunctionObject *b, const Value *thisObject, const QV4::Value *, int)
+{
+    Scope scope(b);
+    QV4::Scoped<QQmlSqlDatabaseWrapper> r(scope, thisObject->as<QQmlSqlDatabaseWrapper>());
+    if (!r || r->d()->type != Heap::QQmlSqlDatabaseWrapper::Rows)
+        V4THROW_REFERENCE("Not a SQLDatabase::Rows object");
+    RETURN_RESULT(Encode(r->d()->sqlQuery->isForwardOnly()));
+}
+
+static ReturnedValue qmlsqldatabase_rows_setForwardOnly(const FunctionObject *b, const Value *thisObject, const Value *argv, int argc)
+{
+    Scope scope(b);
+    QV4::Scoped<QQmlSqlDatabaseWrapper> r(scope, thisObject->as<QQmlSqlDatabaseWrapper>());
+    if (!r || r->d()->type != Heap::QQmlSqlDatabaseWrapper::Rows)
+        V4THROW_REFERENCE("Not a SQLDatabase::Rows object");
+    if (argc < 1)
+        RETURN_RESULT(scope.engine->throwTypeError());
+
+    r->d()->sqlQuery->setForwardOnly(argv[0].toBoolean());
+    RETURN_UNDEFINED();
+}
+
+QQmlSqlDatabaseData::~QQmlSqlDatabaseData()
+{
+}
+
+static ReturnedValue qmlsqldatabase_rows_index(const QQmlSqlDatabaseWrapper *r, ExecutionEngine *v4, quint32 index, bool *hasProperty = nullptr)
+{
+    Scope scope(v4);
+
+    if (r->d()->sqlQuery->at() == (int)index || r->d()->sqlQuery->seek(index)) {
+        QSqlRecord record = r->d()->sqlQuery->record();
+        // XXX optimize
+        ScopedObject row(scope, v4->newObject());
+        for (int ii = 0; ii < record.count(); ++ii) {
+            QVariant v = record.value(ii);
+            ScopedString s(scope, v4->newIdentifier(record.fieldName(ii)));
+            ScopedValue val(scope, v.isNull() ? Encode::null() : v4->fromVariant(v));
+            row->put(s.getPointer(), val);
+        }
+        if (hasProperty)
+            *hasProperty = true;
+        return row.asReturnedValue();
+    } else {
+        if (hasProperty)
+            *hasProperty = false;
+        return Encode::undefined();
+    }
+}
+
+ReturnedValue QQmlSqlDatabaseWrapper::virtualGet(const Managed *m, PropertyKey id, const Value *receiver, bool *hasProperty)
+{
+    if (!id.isArrayIndex())
+        return Object::virtualGet(m, id, receiver, hasProperty);
+
+    uint index = id.asArrayIndex();
+    Q_ASSERT(m->as<QQmlSqlDatabaseWrapper>());
+    const QQmlSqlDatabaseWrapper *r = static_cast<const QQmlSqlDatabaseWrapper *>(m);
+    if (!r || r->d()->type != Heap::QQmlSqlDatabaseWrapper::Rows)
+        return Object::virtualGet(m, id, receiver, hasProperty);
+
+    return qmlsqldatabase_rows_index(r, r->engine(), index, hasProperty);
+}
+
+static ReturnedValue qmlsqldatabase_rows_item(const FunctionObject *b, const Value *thisObject, const Value *argv, int argc)
+{
+    Scope scope(b);
+    QV4::Scoped<QQmlSqlDatabaseWrapper> r(scope, thisObject->as<QQmlSqlDatabaseWrapper>());
+    if (!r || r->d()->type != Heap::QQmlSqlDatabaseWrapper::Rows)
+        V4THROW_REFERENCE("Not a SQLDatabase::Rows object");
+
+    RETURN_RESULT(qmlsqldatabase_rows_index(r, scope.engine, argc ? argv[0].toUInt32() : 0));
+}
+
+static QVariant toSqlVariant(QV4::ExecutionEngine *engine, const QV4::ScopedValue &value)
+{
+    // toVariant() maps a null JS value to QVariant(VoidStar), but the SQL module
+    // expects a null variant. (this is because of QTBUG-40880)
+    if (value->isNull())
+        return QVariant();
+    return engine->toVariant(value, /*typehint*/-1);
+}
+
+static ReturnedValue qmlsqldatabase_executeSql(const FunctionObject *b, const Value *thisObject, const Value *argv, int argc)
+{
+    Scope scope(b);
+    QV4::Scoped<QQmlSqlDatabaseWrapper> r(scope, thisObject->as<QQmlSqlDatabaseWrapper>());
+    if (!r || r->d()->type != Heap::QQmlSqlDatabaseWrapper::Query)
+        V4THROW_REFERENCE("Not a SQLDatabase::Query object");
+
+    if (!r->d()->inTransaction)
+        V4THROW_SQL(SQLEXCEPTION_DATABASE_ERR,QQmlEngine::tr("executeSql called outside transaction()"));
+
+    QSqlDatabase db = *r->d()->database;
+
+    QString sql = argc ? argv[0].toQString() : QString();
+
+    if (r->d()->readonly && !sql.startsWith(QLatin1String("SELECT"),Qt::CaseInsensitive)) {
+        V4THROW_SQL(SQLEXCEPTION_SYNTAX_ERR, QQmlEngine::tr("Read-only Transaction"));
+    }
+
+    QSqlQuery query(db);
+    bool err = false;
+
+    ScopedValue result(scope, Value::undefinedValue());
+
+    if (query.prepare(sql)) {
+        if (argc > 1) {
+            ScopedValue values(scope, argv[1]);
+            if (values->as<ArrayObject>()) {
+                ScopedArrayObject array(scope, values);
+                quint32 size = array->getLength();
+                QV4::ScopedValue v(scope);
+                for (quint32 ii = 0; ii < size; ++ii) {
+                    query.bindValue(ii, toSqlVariant(scope.engine, (v = array->get(ii))));
+                }
+            } else if (values->as<Object>()) {
+                ScopedObject object(scope, values);
+                ObjectIterator it(scope, object, ObjectIterator::EnumerableOnly);
+                ScopedValue key(scope);
+                QV4::ScopedValue val(scope);
+                while (1) {
+                    key = it.nextPropertyName(val);
+                    if (key->isNull())
+                        break;
+                    QVariant v = toSqlVariant(scope.engine, val);
+                    if (key->isString()) {
+                        query.bindValue(key->stringValue()->toQString(), v);
+                    } else {
+                        Q_ASSERT(key->isInteger());
+                        query.bindValue(key->integerValue(), v);
+                    }
+                }
+            } else {
+                query.bindValue(0, toSqlVariant(scope.engine, values));
+            }
+        }
+        if (query.exec()) {
+            QV4::Scoped<QQmlSqlDatabaseWrapper> rows(scope, QQmlSqlDatabaseWrapper::create(scope.engine));
+            QV4::ScopedObject p(scope, databaseData(scope.engine)->rowsProto.value());
+            rows->setPrototypeUnchecked(p.getPointer());
+            rows->d()->type = Heap::QQmlSqlDatabaseWrapper::Rows;
+            *rows->d()->database = db;
+            *rows->d()->sqlQuery = query;
+
+            ScopedObject resultObject(scope, scope.engine->newObject());
+            result = resultObject.asReturnedValue();
+            // XXX optimize
+            ScopedString s(scope);
+            ScopedValue v(scope);
+            resultObject->put((s = scope.engine->newIdentifier("rowsAffected")).getPointer(), (v = Value::fromInt32(query.numRowsAffected())));
+            resultObject->put((s = scope.engine->newIdentifier("insertId")).getPointer(), (v = scope.engine->newString(query.lastInsertId().toString())));
+            resultObject->put((s = scope.engine->newIdentifier("rows")).getPointer(), rows);
+        } else {
+            err = true;
+        }
+    } else {
+        err = true;
+    }
+    if (err)
+        V4THROW_SQL(SQLEXCEPTION_DATABASE_ERR,query.lastError().text());
+
+    RETURN_RESULT(result->asReturnedValue());
+}
+
+struct TransactionRollback {
+    QSqlDatabase *db;
+    bool *inTransactionFlag;
+
+    TransactionRollback(QSqlDatabase *database, bool *transactionFlag)
+        : db(database)
+        , inTransactionFlag(transactionFlag)
+    {
+        if (inTransactionFlag)
+            *inTransactionFlag = true;
+    }
+
+    ~TransactionRollback()
+    {
+        if (inTransactionFlag)
+            *inTransactionFlag = false;
+        if (db)
+            db->rollback();
+    }
+
+    void clear() {
+        db = nullptr;
+        if (inTransactionFlag)
+            *inTransactionFlag = false;
+        inTransactionFlag = nullptr;
+    }
+};
+
+
+static ReturnedValue qmlsqldatabase_changeVersion(const FunctionObject *b, const Value *thisObject, const Value *argv, int argc)
+{
+    Scope scope(b);
+    if (argc < 2)
+        RETURN_UNDEFINED();
+
+    Scoped<QQmlSqlDatabaseWrapper> r(scope, *thisObject);
+    if (!r || r->d()->type != Heap::QQmlSqlDatabaseWrapper::Database)
+        V4THROW_REFERENCE("Not a SQLDatabase object");
+
+    QSqlDatabase db = *r->d()->database;
+    QString from_version = argv[0].toQString();
+    QString to_version = argv[1].toQString();
+    ScopedFunctionObject callback(scope, argc > 2 ? argv[2] : Value::undefinedValue());
+
+    if (from_version != *r->d()->version)
+        V4THROW_SQL(SQLEXCEPTION_VERSION_ERR, QQmlEngine::tr("Version mismatch: expected %1, found %2").arg(from_version).arg(*r->d()->version));
+
+    bool ok = true;
+    if (!!callback) {
+        Scoped<QQmlSqlDatabaseWrapper> query(scope, QQmlSqlDatabaseWrapper::create(scope.engine));
+        ScopedObject p(scope, databaseData(scope.engine)->queryProto.value());
+        query->setPrototypeUnchecked(p.getPointer());
+        query->d()->type = Heap::QQmlSqlDatabaseWrapper::Query;
+        *query->d()->database = db;
+        *query->d()->version = *r->d()->version;
+
+        ok = false;
+        db.transaction();
+
+        JSCallData jsCall(scope, 1);
+        *jsCall->thisObject = scope.engine->globalObject;
+        jsCall->args[0] = query;
+
+        TransactionRollback rollbackOnException(&db, &query->d()->inTransaction);
+        callback->call(jsCall);
+        rollbackOnException.clear();
+        if (!db.commit()) {
+            db.rollback();
+            V4THROW_SQL(SQLEXCEPTION_UNKNOWN_ERR,QQmlEngine::tr("SQL transaction failed"));
+        } else {
+            ok = true;
+        }
+    }
+
+    if (ok) {
+        Scoped<QQmlSqlDatabaseWrapper> w(scope, QQmlSqlDatabaseWrapper::create(scope.engine));
+        ScopedObject p(scope, databaseData(scope.engine)->databaseProto.value());
+        w->setPrototypeUnchecked(p.getPointer());
+        w->d()->type = Heap::QQmlSqlDatabaseWrapper::Database;
+        *w->d()->database = db;
+        *w->d()->version = to_version;
+#if QT_CONFIG(settings)
+        const QQmlEnginePrivate *enginePrivate = QQmlEnginePrivate::get(scope.engine->qmlEngine());
+        QSettings ini(enginePrivate->offlineStorageDatabaseDirectory() + db.connectionName() + QLatin1String(".ini"), QSettings::IniFormat);
+        ini.setValue(QLatin1String("Version"), to_version);
+#endif
+        RETURN_RESULT(w.asReturnedValue());
+    }
+
+    RETURN_UNDEFINED();
+}
+
+static ReturnedValue qmlsqldatabase_transaction_shared(const FunctionObject *b, const Value *thisObject, const Value *argv, int argc, bool readOnly)
+{
+    Scope scope(b);
+    QV4::Scoped<QQmlSqlDatabaseWrapper> r(scope, thisObject->as<QQmlSqlDatabaseWrapper>());
+    if (!r || r->d()->type != Heap::QQmlSqlDatabaseWrapper::Database)
+        V4THROW_REFERENCE("Not a SQLDatabase object");
+
+    const FunctionObject *callback = argc ? argv[0].as<FunctionObject>() : nullptr;
+    if (!callback)
+        V4THROW_SQL(SQLEXCEPTION_UNKNOWN_ERR, QQmlEngine::tr("transaction: missing callback"));
+
+    QSqlDatabase db = *r->d()->database;
+
+    Scoped<QQmlSqlDatabaseWrapper> w(scope, QQmlSqlDatabaseWrapper::create(scope.engine));
+    QV4::ScopedObject p(scope, databaseData(scope.engine)->queryProto.value());
+    w->setPrototypeUnchecked(p.getPointer());
+    w->d()->type = Heap::QQmlSqlDatabaseWrapper::Query;
+    *w->d()->database = db;
+    *w->d()->version = *r->d()->version;
+    w->d()->readonly = readOnly;
+
+    db.transaction();
+    if (callback) {
+        JSCallData jsCall(scope, 1);
+        *jsCall->thisObject = scope.engine->globalObject;
+        jsCall->args[0] = w;
+        TransactionRollback rollbackOnException(&db, &w->d()->inTransaction);
+        callback->call(jsCall);
+        rollbackOnException.clear();
+
+        if (!db.commit())
+            db.rollback();
+    }
+
+    RETURN_UNDEFINED();
+}
+
+static ReturnedValue qmlsqldatabase_transaction(const FunctionObject *f, const Value *thisObject, const Value *argv, int argc)
+{
+    return qmlsqldatabase_transaction_shared(f, thisObject, argv, argc, false);
+}
+
+static ReturnedValue qmlsqldatabase_read_transaction(const FunctionObject *f, const Value *thisObject, const Value *argv, int argc)
+{
+    return qmlsqldatabase_transaction_shared(f, thisObject, argv, argc, true);
+}
+
+QQmlSqlDatabaseData::QQmlSqlDatabaseData(ExecutionEngine *v4)
+{
+    Scope scope(v4);
+    {
+        ScopedObject proto(scope, v4->newObject());
+        proto->defineDefaultProperty(QStringLiteral("transaction"), qmlsqldatabase_transaction);
+        proto->defineDefaultProperty(QStringLiteral("readTransaction"), qmlsqldatabase_read_transaction);
+        proto->defineAccessorProperty(QStringLiteral("version"), qmlsqldatabase_version, nullptr);
+        proto->defineDefaultProperty(QStringLiteral("changeVersion"), qmlsqldatabase_changeVersion);
+        databaseProto = proto;
+    }
+
+    {
+        ScopedObject proto(scope, v4->newObject());
+        proto->defineDefaultProperty(QStringLiteral("executeSql"), qmlsqldatabase_executeSql);
+        queryProto = proto;
+    }
+    {
+        ScopedObject proto(scope, v4->newObject());
+        proto->defineDefaultProperty(QStringLiteral("item"), qmlsqldatabase_rows_item);
+        proto->defineAccessorProperty(QStringLiteral("length"), qmlsqldatabase_rows_length, nullptr);
+        proto->defineAccessorProperty(QStringLiteral("forwardOnly"),
+                                      qmlsqldatabase_rows_forwardOnly, qmlsqldatabase_rows_setForwardOnly);
+        rowsProto = proto;
+    }
+}
+
+/*
+HTML5 "spec" says "rs.rows[n]", but WebKit only impelments "rs.rows.item(n)". We do both (and property iterator).
+We add a "forwardOnly" property that stops Qt caching results (code promises to only go forward
+through the data.
+*/
+
+/*!
+    \qmlmodule QtQuick.LocalStorage 2.\QtMinorVersion
+    \title Qt Quick Local Storage QML Types
+    \ingroup qmlmodules
+    \brief Provides a JavaScript object singleton type for accessing a local
+    SQLite database
+
+    This is a singleton type for reading and writing to SQLite databases.
+
+
+    \section1 Methods
+
+    \list
+    \li object \b{\l{#openDatabaseSync}{openDatabaseSync}}(string name, string version, string
+description, int estimated_size, jsobject callback(db)) \endlist
+
+
+    \section1 Detailed Description
+
+    To use the types in this module, import the module and call the
+    relevant functions using the \c LocalStorage type:
+
+    \qml
+    import QtQuick
+    import QtQuick.LocalStorage
+
+    Item {
+        Component.onCompleted: {
+            var db = LocalStorage.openDatabaseSync(...)
+        }
+    }
+    \endqml
+
+
+These databases are user-specific and QML-specific, but accessible to all QML applications.
+They are stored in the \c Databases subdirectory
+of QQmlEngine::offlineStoragePath(), currently as SQLite databases.
+
+Database connections are automatically closed during Javascript garbage collection.
+
+The API can be used from JavaScript functions in your QML:
+
+\snippet qml/localstorage/hello.qml 0
+
+The API conforms to the Synchronous API of the HTML5 Web Database API,
+\link http://www.w3.org/TR/2009/WD-webdatabase-20091029/ W3C Working Draft 29 October 2009\endlink.
+
+The \l{Qt Quick Examples - Local Storage}{SQL Local Storage example} demonstrates the basics of
+using the Offline Storage API.
+
+\section3 Open or Create a Database
+
+\qml
+import QtQuick.LocalStorage as Sql
+
+db = Sql.openDatabaseSync(identifier, version, description, estimated_size, callback(db))
+\endqml
+
+The above code returns the database identified by \e identifier. If the database does not already
+exist, it is created, and the function \e callback is called with the database as a parameter. \e
+identifier is the name of the physical file (with or without full path) containing the database.  \e
+description and \e estimated_size are written to the INI file (described below), but are currently
+unused.
+
+May throw exception with code property SQLException.DATABASE_ERR, or SQLException.VERSION_ERR.
+
+When a database is first created, an INI file is also created specifying its characteristics:
+
+\table
+\header \li \b {Key} \li \b {Value}
+\row \li Identifier \li The name of the database passed to \c openDatabase()
+\row \li Version \li The version of the database passed to \c openDatabase()
+\row \li Description \li The description of the database passed to \c openDatabase()
+\row \li EstimatedSize \li The estimated size (in bytes) of the database passed to \c openDatabase()
+\row \li Driver \li Currently "QSQLITE"
+\endtable
+
+This data can be used by application tools.
+
+\section3 db.changeVersion(from, to, callback(tx))
+
+This method allows you to perform a \e{Scheme Upgrade}. If it succeeds it returns a new
+database object of version \e to. Otherwise it returns \e undefined.
+
+If the current version of \e db is not \e from, then an exception is thrown.
+
+Otherwise, a database transaction is created and passed to \e callback. In this function,
+you can call \e executeSql on \e tx to upgrade the database.
+
+May throw exception with code property SQLException.DATABASE_ERR or SQLException.UNKNOWN_ERR.
+
+See example below.
+
+\badcode
+    var db = LocalStorage.openDatabaseSync("ActivityTrackDB", "", "Database tracking sports
+activities", 1000000); if (db.version == "0.1") { db.changeVersion("0.1", "0.2", function(tx) {
+            tx.executeSql("INSERT INTO trip_log VALUES(?, ?, ?)",
+                        [ "01/10/2016","Sylling - Vikersund", "53" ]);
+        }
+    });
+\endcode
+
+\section3 db.transaction(callback(tx))
+
+This method creates a read/write transaction and passed to \e callback. In this function,
+you can call \e executeSql on \e tx to read and modify the database.
+
+If the callback throws exceptions, the transaction is rolled back.
+Below you will find an example of a database transaction which catches exceptions.
+
+
+\quotefromfile localstorage/localstorage/Database.js
+\skipuntil dbInit()
+\printto dbGetHandle
+
+In the example you can see an \c insert statement where values are assigned to the fields,
+and the record is written into the table. That is an \c insert statement with a syntax that is usual
+for a relational database. It is however also possible to work with JSON objects and
+store them in a table.
+
+Let's suppose a simple example where we store trips in JSON format using \c date as the unique key.
+An example of a table that could be used for that purpose:
+
+\badcode
+    create table trip_log(date text, data text)
+\endcode
+
+The assignment of values to a JSON object:
+
+\badcode
+    var obj = {description = "Vikersund - Noresund", distance = "60"}
+\endcode
+
+In that case, the data could be saved in the following way:
+
+\badcode
+    db.transaction(function(tx) {
+        result = tx.executeSQL("insert into trip_log values (?,?)",
+                               ["01/11/2016", JSON.stringify(obj)])
+
+\endcode
+
+\section3 db.readTransaction(callback(tx))
+
+This method creates a read-only transaction and passed to \e callback. In this function,
+you can call \e executeSql on \e tx to read the database (with \c select statements).
+
+\section3 results = tx.executeSql(statement, values)
+
+This method executes an SQL \e statement, binding the list of \e values to SQL positional parameters
+("?").
+
+It returns a results object, with the following properties:
+
+\table
+\header \li \b {Type} \li \b {Property} \li \b {Value} \li \b {Applicability}
+\row \li int \li rows.length \li The number of rows in the result \li SELECT
+\row \li var \li rows.item(i) \li Function that returns row \e i of the result \li SELECT
+\row \li int \li rowsAffected \li The number of rows affected by a modification \li UPDATE, DELETE
+\row \li string \li insertId \li The id of the row inserted \li INSERT
+\endtable
+
+May throw exception with code property SQLException.DATABASE_ERR, SQLException.SYNTAX_ERR, or
+SQLException.UNKNOWN_ERR.
+
+See below for an example:
+
+\quotefromfile localstorage/localstorage/Database.js
+\skipto dbReadAll()
+\printto dbUpdate(Pdate
+
+\section1 Method Documentation
+
+\target openDatabaseSync
+\code
+object openDatabaseSync(string name, string version, string description, int estimated_size,
+jsobject callback(db)) \endcode
+
+Opens or creates a local storage sql database by the given parameters.
+
+\list
+\li \c name is the database name
+\li \c version is the database version
+\li \c description is the database display name
+\li \c estimated_size is the database's estimated size, in bytes
+\li \c callback is an optional parameter, which is invoked if the database has not yet been created.
+\endlist
+
+Returns the created database object.
+
+*/
+
+void QQmlLocalStorage::openDatabaseSync(QQmlV4Function *args)
+{
+#if QT_CONFIG(settings)
+    QV4::Scope scope(args->v4engine());
+    if (scope.engine->qmlEngine()->offlineStoragePath().isEmpty())
+        V4THROW_SQL2(SQLEXCEPTION_DATABASE_ERR, QQmlEngine::tr("SQL: can't create database, offline storage is disabled."));
+
+    QV4::ScopedValue v(scope);
+    QString dbname = (v = (*args)[0])->toQStringNoThrow();
+    QString dbversion = (v = (*args)[1])->toQStringNoThrow();
+    QString dbdescription = (v = (*args)[2])->toQStringNoThrow();
+    int dbestimatedsize = (v = (*args)[3])->toInt32();
+    FunctionObject *dbcreationCallback = (v = (*args)[4])->as<FunctionObject>();
+    QString basename = args->v4engine()->qmlEngine()->offlineStorageDatabaseFilePath(dbname);
+    QFileInfo dbFile(basename);
+    if (!QDir().mkpath(dbFile.dir().absolutePath())) {
+        const QString message = QQmlEngine::tr("LocalStorage: can't create path %1").
+                                arg(QDir::toNativeSeparators(dbFile.dir().absolutePath()));
+        V4THROW_SQL2(SQLEXCEPTION_DATABASE_ERR, message);
+    }
+    QString dbid = dbFile.fileName();
+    bool created = false;
+    QString version = dbversion;
+    QSqlDatabase database;
+
+    {
+        QSettings ini(basename+QLatin1String(".ini"),QSettings::IniFormat);
+
+        if (QSqlDatabase::connectionNames().contains(dbid)) {
+            database = QSqlDatabase::database(dbid);
+            version = ini.value(QLatin1String("Version")).toString();
+            if (version != dbversion && !dbversion.isEmpty() && !version.isEmpty())
+                V4THROW_SQL2(SQLEXCEPTION_VERSION_ERR, QQmlEngine::tr("SQL: database version mismatch"));
+        } else {
+            created = !QFile::exists(basename+QLatin1String(".sqlite"));
+            if (created) {
+                ini.setValue(QLatin1String("Name"), dbname);
+                if (dbcreationCallback)
+                    version = QString();
+                ini.setValue(QLatin1String("Version"), version);
+                ini.setValue(QLatin1String("Description"), dbdescription);
+                ini.setValue(QLatin1String("EstimatedSize"), dbestimatedsize);
+                ini.setValue(QLatin1String("Driver"), QLatin1String("QSQLITE"));
+            } else {
+                if (!dbversion.isEmpty() && ini.value(QLatin1String("Version")) != dbversion) {
+                    // Incompatible
+                    V4THROW_SQL2(SQLEXCEPTION_VERSION_ERR,QQmlEngine::tr("SQL: database version mismatch"));
+                }
+                version = ini.value(QLatin1String("Version")).toString();
+            }
+            database = QSqlDatabase::addDatabase(QLatin1String("QSQLITE"), dbid);
+            database.setDatabaseName(basename+QLatin1String(".sqlite"));
+        }
+        if (!database.isOpen())
+            database.open();
+    }
+
+    QV4::Scoped<QQmlSqlDatabaseWrapper> db(scope, QQmlSqlDatabaseWrapper::create(scope.engine));
+    QV4::ScopedObject p(scope, databaseData(scope.engine)->databaseProto.value());
+    db->setPrototypeUnchecked(p.getPointer());
+    *db->d()->database = database;
+    *db->d()->version = version;
+
+    if (created && dbcreationCallback) {
+        JSCallData jsCall(scope, 1);
+        *jsCall->thisObject = scope.engine->globalObject;
+        jsCall->args[0] = db;
+        dbcreationCallback->call(jsCall);
+    }
+
+    args->setReturnValue(db.asReturnedValue());
+#else
+    Q_UNUSED(args);
+#endif // settings
+}
+
+QT_END_NAMESPACE
diff --git a/src/qmllocalstorage/qqmllocalstorage_p.h b/src/qmllocalstorage/qqmllocalstorage_p.h
new file mode 100644
index 0000000000..ad0ac57278
--- /dev/null
+++ b/src/qmllocalstorage/qqmllocalstorage_p.h
@@ -0,0 +1,78 @@
+/****************************************************************************
+**
+** Copyright (C) 2019 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QQMLLOCALSTORAGE_P_H
+#define QQMLLOCALSTORAGE_P_H
+
+#include "qqmllocalstorageglobal_p.h"
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include <QtCore/qobject.h>
+#include <QtQml/qqml.h>
+#include <QtQml/private/qv4engine_p.h>
+
+QT_BEGIN_NAMESPACE
+
+class Q_QMLLOCALSTORAGE_PRIVATE_EXPORT QQmlLocalStorage : public QObject
+{
+    Q_OBJECT
+    QML_NAMED_ELEMENT(LocalStorage)
+    QML_ADDED_IN_VERSION(2, 0)
+    QML_SINGLETON
+
+public:
+    QQmlLocalStorage(QObject *parent = nullptr) : QObject(parent) {}
+    ~QQmlLocalStorage() override = default;
+
+    Q_INVOKABLE void openDatabaseSync(QQmlV4Function* args);
+};
+
+QT_END_NAMESPACE
+
+#endif // QQMLLOCALSTORAGE_P_H
diff --git a/src/qmllocalstorage/qqmllocalstorageglobal_p.h b/src/qmllocalstorage/qqmllocalstorageglobal_p.h
new file mode 100644
index 0000000000..5eb13cce68
--- /dev/null
+++ b/src/qmllocalstorage/qqmllocalstorageglobal_p.h
@@ -0,0 +1,75 @@
+/****************************************************************************
+**
+** Copyright (C) 2021 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtQuick module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QQMLLOCALSTORAGEGLOBAL_P_H
+#define QQMLLOCALSTORAGEGLOBAL_P_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include <QtCore/qglobal.h>
+
+QT_BEGIN_NAMESPACE
+
+#if !defined(QT_STATIC)
+#  if defined(QT_BUILD_QMLLOCALSTORAGE_LIB)
+#    define Q_QMLLOCALSTORAGE_EXPORT Q_DECL_EXPORT
+#  else
+#    define Q_QMLLOCALSTORAGE_EXPORT Q_DECL_IMPORT
+#  endif
+#else
+#  define Q_QMLLOCALSTORAGE_EXPORT
+#endif
+
+
+#define Q_QMLLOCALSTORAGE_PRIVATE_EXPORT Q_QMLLOCALSTORAGE_EXPORT
+
+QT_END_NAMESPACE
+
+void Q_QMLLOCALSTORAGE_PRIVATE_EXPORT qml_register_types_QtQuick_LocalStorage();
+
+#endif // QQMLLOCALSTORAGEGLOBAL_P_H