Properly handle QGenericReturnArgument

Using the memory address of the QVariant that acts as buffer is bad. While we got
lucky with Qt4, and this worked by accident, it leads to subtle and not-so-subtle segfaults
when used with Qt5.

Instead, using QVariant::data() makes sure that implicitly shared data is properly detached.

diff --git a/src/common/syncableobject.cpp b/src/common/syncableobject.cpp
index 8667a59..ac62f08 100644 (file)
--- a/src/common/syncableobject.cpp
+++ b/src/common/syncableobject.cpp
@@ -105,15 +105,14 @@ QVariantMap SyncableObject::toVariantMap() {
       qWarning() << "SyncableObject::toVariantMap(): cannot fetch init data for:" << this << method.signature() << "- Returntype is unknown to Qt's MetaSystem:" << QByteArray(method.typeName());
       continue;
     }
-    QVariant value = QVariant(variantType);
-    QGenericReturnArgument genericvalue = QGenericReturnArgument(method.typeName(), &value);
+
+    QVariant value(variantType, (const void *) 0);
+    QGenericReturnArgument genericvalue = QGenericReturnArgument(method.typeName(), value.data());
     QMetaObject::invokeMethod(this, methodname.toAscii(), genericvalue);
 
     properties[SignalProxy::ExtendedMetaObject::methodBaseName(method)] = value;
   }
-  // properties["Payload"] = QByteArray(10000000, 'a');  // for testing purposes
   return properties;
-
 }
 
 void SyncableObject::fromVariantMap(const QVariantMap &properties) {