Implement a support for getting return arguments out of invokeMethod

with QDBusInterface.

The problem was that I didn't know how to implement the operator= for
all types. But it turns out that this was possible all along: the only
types I have to implement the operator= for are the basic types, which
are already demarshalled.

The complex types are left in QDBusArgument semi-demarshalling, but we
have QDBusMetaType::demarshall, which takes a void* to an
already-constructed type and demarshalls into it. That's exactly what
the doctor ordered.

Task-number: 206765
Reviewed-By: Marius Bugge Monsen

2 files changed, 209 insertions, 9 deletions

diff --git a/src/dbus/qdbusinterface.cpp b/src/dbus/qdbusinterface.cpp
index 6f61847..5f6df0a 100644
--- a/src/dbus/qdbusinterface.cpp
+++ b/src/dbus/qdbusinterface.cpp
@@ -51,6 +51,102 @@
 
 QT_BEGIN_NAMESPACE
 
+static void copyArgument(void *to, int id, const QVariant &arg)
+{
+    if (id == arg.userType()) {
+        switch (id) {
+        case QVariant::Bool:
+            *reinterpret_cast<bool *>(to) = arg.toBool();
+            return;
+
+        case QMetaType::UChar:
+            *reinterpret_cast<uchar *>(to) = arg.value<uchar>();
+            return;
+
+        case QMetaType::Short:
+            *reinterpret_cast<short *>(to) = arg.value<short>();
+            return;
+
+        case QMetaType::UShort:
+            *reinterpret_cast<ushort *>(to) = arg.value<ushort>();
+            return;
+
+        case QVariant::Int:
+            *reinterpret_cast<int *>(to) = arg.toInt();
+            return;
+
+        case QVariant::UInt:
+            *reinterpret_cast<uint *>(to) = arg.toUInt();
+            return;
+
+        case QVariant::LongLong:
+            *reinterpret_cast<qlonglong *>(to) = arg.toLongLong();
+            return;
+
+        case QVariant::ULongLong:
+            *reinterpret_cast<qulonglong *>(to) = arg.toULongLong();
+            return;
+
+        case QVariant::Double:
+            *reinterpret_cast<double *>(to) = arg.toDouble();
+            return;
+
+        case QVariant::String:
+            *reinterpret_cast<QString *>(to) = arg.toString();
+            return;
+
+        case QVariant::ByteArray:
+            *reinterpret_cast<QByteArray *>(to) = arg.toByteArray();
+            return;
+
+        case QVariant::StringList:
+            *reinterpret_cast<QStringList *>(to) = arg.toStringList();
+            return;
+        }
+
+        if (id == QDBusMetaTypeId::variant) {
+            *reinterpret_cast<QDBusVariant *>(to) = arg.value<QDBusVariant>();
+            return;
+        } else if (id == QDBusMetaTypeId::objectpath) {
+            *reinterpret_cast<QDBusObjectPath *>(to) = arg.value<QDBusObjectPath>();
+            return;
+        } else if (id == QDBusMetaTypeId::signature) {
+            *reinterpret_cast<QDBusSignature *>(to) = arg.value<QDBusSignature>();
+            return;
+        }
+
+        // those above are the only types possible
+        // the demarshaller code doesn't demarshall anything else
+        qFatal("Found a decoded basic type in a D-Bus reply that shouldn't be there");
+    }
+
+    // if we got here, it's either an un-dermarshalled type or a mismatch
+    if (arg.userType() != QDBusMetaTypeId::argument) {
+        // it's a mismatch
+        //qWarning?
+        return;
+    }
+
+    // is this type registered?
+    const char *userSignature = QDBusMetaType::typeToSignature(id);
+    if (!userSignature || !*userSignature) {
+        // type not registered
+        //qWarning?
+        return;
+    }
+
+    // is it the same signature?
+    QDBusArgument dbarg = arg.value<QDBusArgument>();
+    if (dbarg.currentSignature() != QLatin1String(userSignature)) {
+        // not the same signature, another mismatch
+        //qWarning?
+        return;
+    }
+
+    // we can demarshall
+    QDBusMetaType::demarshall(dbarg, id, to);
+}
+
 QDBusInterfacePrivate::QDBusInterfacePrivate(const QString &serv, const QString &p,
                                              const QString &iface, const QDBusConnection &con)
     : QDBusAbstractInterfacePrivate(serv, p, iface, con, true), metaObject(0)
@@ -186,23 +282,37 @@ int QDBusInterfacePrivate::metacall(QMetaObject::Call c, int id, void **argv)
 
             // we will assume that the input arguments were passed correctly
             QVariantList args;
-            for (int i = 1; i <= inputTypesCount; ++i)
+            int i = 1;
+            for ( ; i <= inputTypesCount; ++i)
                 args << QVariant(inputTypes[i], argv[i]);
 
             // make the call
-            QPointer<QDBusInterface> qq = q;
             QDBusMessage reply = q->callWithArgumentList(QDBus::Block, methodName, args);
-            args.clear();
 
-            // we ignore return values
+            if (reply.type() == QDBusMessage::ReplyMessage) {
+                // attempt to demarshall the return values
+                args = reply.arguments();
+                QVariantList::ConstIterator it = args.constBegin();
+                const int *outputTypes = metaObject->outputTypesForMethod(id);
+                int outputTypesCount = *outputTypes++;
+
+                if (*mm.typeName()) {
+                    // this method has a return type
+                    if (argv[0] && it != args.constEnd())
+                        copyArgument(argv[0], *outputTypes++, *it);
 
-            // access to "this" or to "q" below this point must check for "qq"
-            // we may have been deleted!
+                    // skip this argument even if we didn't copy it
+                    --outputTypesCount;
+                    ++it;
+                }
 
-            if (!qq.isNull())
-                lastError = reply;
+                for (int j = 0; j < outputTypesCount && it != args.constEnd(); ++i, ++j, ++it) {
+                    copyArgument(argv[i], outputTypes[j], *it);
+                }
+            }
 
             // done
+            lastError = reply;
             return -1;
         }
     }
diff --git a/tests/auto/qdbusinterface/tst_qdbusinterface.cpp b/tests/auto/qdbusinterface/tst_qdbusinterface.cpp
index 718ba18..60afe4e 100644
--- a/tests/auto/qdbusinterface/tst_qdbusinterface.cpp
+++ b/tests/auto/qdbusinterface/tst_qdbusinterface.cpp
@@ -76,6 +76,12 @@ class MyObject: public QObject
 "      <arg direction=\"out\" type=\"v\" name=\"pong1\" />\n"
 "      <arg direction=\"out\" type=\"v\" name=\"pong2\" />\n"
 "    </method>\n"
+"    <method name=\"ping\" >\n"
+"      <arg direction=\"in\" type=\"ai\" name=\"ping\" />\n"
+"      <arg direction=\"out\" type=\"ai\" name=\"ping\" />\n"
+"      <annotation name=\"com.trolltech.QtDBus.QtTypeName.In0\" value=\"QList&lt;int&gt;\"/>\n"
+"      <annotation name=\"com.trolltech.QtDBus.QtTypeName.Out0\" value=\"QList&lt;int&gt;\"/>\n"
+"    </method>\n"
 "  </interface>\n"
         "")
     Q_PROPERTY(int prop1 READ prop1 WRITE setProp1)
@@ -174,6 +180,9 @@ private slots:
     void introspect();
     void callMethod();
     void invokeMethod();
+    void invokeMethodWithReturn();
+    void invokeMethodWithMultiReturn();
+    void invokeMethodWithComplexReturn();
 
     void signal();
 
@@ -263,7 +272,7 @@ void tst_QDBusInterface::introspect()
 
     const QMetaObject *mo = iface.metaObject();
 
-    QCOMPARE(mo->methodCount() - mo->methodOffset(), 3);
+    QCOMPARE(mo->methodCount() - mo->methodOffset(), 4);
     QVERIFY(mo->indexOfSignal(TEST_SIGNAL_NAME "(QString)") != -1);
 
     QCOMPARE(mo->propertyCount() - mo->propertyOffset(), 2);
@@ -317,6 +326,87 @@ void tst_QDBusInterface::invokeMethod()
     QCOMPARE(dv.variant().toString(), QString("foo"));
 }
 
+void tst_QDBusInterface::invokeMethodWithReturn()
+{
+    QDBusConnection con = QDBusConnection::sessionBus();
+    QDBusInterface iface(QDBusConnection::sessionBus().baseService(), QLatin1String("/"),
+                         TEST_INTERFACE_NAME);
+
+    // make the call without a return type
+    MyObject::callCount = 0;
+    QDBusVariant arg("foo");
+    QDBusVariant retArg;
+    QVERIFY(QMetaObject::invokeMethod(&iface, "ping", Q_RETURN_ARG(QDBusVariant, retArg), Q_ARG(QDBusVariant, arg)));
+    QCOMPARE(MyObject::callCount, 1);
+
+    // verify what the callee received
+    QCOMPARE(MyObject::callArgs.count(), 1);
+    QVariant v = MyObject::callArgs.at(0);
+    QDBusVariant dv = qdbus_cast<QDBusVariant>(v);
+    QCOMPARE(dv.variant().type(), QVariant::String);
+    QCOMPARE(dv.variant().toString(), arg.variant().toString());
+
+    // verify that we got the reply as expected
+    QCOMPARE(retArg.variant(), arg.variant());
+}
+
+void tst_QDBusInterface::invokeMethodWithMultiReturn()
+{
+    QDBusConnection con = QDBusConnection::sessionBus();
+    QDBusInterface iface(QDBusConnection::sessionBus().baseService(), QLatin1String("/"),
+                         TEST_INTERFACE_NAME);
+
+    // make the call without a return type
+    MyObject::callCount = 0;
+    QDBusVariant arg("foo"), arg2("bar");
+    QDBusVariant retArg, retArg2;
+    QVERIFY(QMetaObject::invokeMethod(&iface, "ping",
+                                      Q_RETURN_ARG(QDBusVariant, retArg),
+                                      Q_ARG(QDBusVariant, arg),
+                                      Q_ARG(QDBusVariant, arg2),
+                                      Q_ARG(QDBusVariant&, retArg2)));
+    QCOMPARE(MyObject::callCount, 1);
+
+    // verify what the callee received
+    QCOMPARE(MyObject::callArgs.count(), 2);
+    QVariant v = MyObject::callArgs.at(0);
+    QDBusVariant dv = qdbus_cast<QDBusVariant>(v);
+    QCOMPARE(dv.variant().type(), QVariant::String);
+    QCOMPARE(dv.variant().toString(), arg.variant().toString());
+
+    v = MyObject::callArgs.at(1);
+    dv = qdbus_cast<QDBusVariant>(v);
+    QCOMPARE(dv.variant().type(), QVariant::String);
+    QCOMPARE(dv.variant().toString(), arg2.variant().toString());
+
+    // verify that we got the replies as expected
+    QCOMPARE(retArg.variant(), arg.variant());
+    QCOMPARE(retArg2.variant(), arg2.variant());
+}
+
+void tst_QDBusInterface::invokeMethodWithComplexReturn()
+{
+    QDBusConnection con = QDBusConnection::sessionBus();
+    QDBusInterface iface(QDBusConnection::sessionBus().baseService(), QLatin1String("/"),
+                         TEST_INTERFACE_NAME);
+
+    // make the call without a return type
+    MyObject::callCount = 0;
+    QList<int> arg = QList<int>() << 42 << -47;
+    QList<int> retArg;
+    QVERIFY(QMetaObject::invokeMethod(&iface, "ping", Q_RETURN_ARG(QList<int>, retArg), Q_ARG(QList<int>, arg)));
+    QCOMPARE(MyObject::callCount, 1);
+
+    // verify what the callee received
+    QCOMPARE(MyObject::callArgs.count(), 1);
+    QVariant v = MyObject::callArgs.at(0);
+    QCOMPARE(v.userType(), qMetaTypeId<QDBusArgument>());
+    QCOMPARE(qdbus_cast<QList<int> >(v), arg);
+
+    // verify that we got the reply as expected
+    QCOMPARE(retArg, arg);
+}
+
 void tst_QDBusInterface::signal()
 {
     QDBusConnection con = QDBusConnection::sessionBus();