Fix crash when converting empty array variants (open62541)

If arrayLength is 0, the variant can contain a scalar value or
an empty array. Empty arrays are indicated by setting data to 1.
This must be checked before calling scalarToQVariant().

Change-Id: Ia62c4acf258fb0e080334504d105de1a898e3e6a
Reviewed-by: Frank Meerkoetter <frank.meerkoetter@basyskom.com>

5 files changed, 67 insertions, 5 deletions

diff --git a/src/plugins/opcua/open62541/qopen62541valueconverter.cpp b/src/plugins/opcua/open62541/qopen62541valueconverter.cpp
index 7024523..226b8b7 100644
--- a/src/plugins/opcua/open62541/qopen62541valueconverter.cpp
+++ b/src/plugins/opcua/open62541/qopen62541valueconverter.cpp
@@ -412,16 +412,24 @@ QVariant scalarToQVariant<QVariant, UA_ExtensionObject>(UA_ExtensionObject *data
 template<typename TARGETTYPE, typename UATYPE>
 QVariant arrayToQVariant(const UA_Variant &var, QMetaType::Type type)
 {
-    if (var.arrayLength > 1) {
+    UATYPE *temp = static_cast<UATYPE *>(var.data);
+
+    if (var.arrayLength > 0) {
         QVariantList list;
         for (size_t i = 0; i < var.arrayLength; ++i) {
-            UATYPE *temp = static_cast<UATYPE *>(var.data);
             list.append(scalarToQVariant<TARGETTYPE, UATYPE>(&temp[i], type));
         }
-        return list;
+        if (list.size() == 1)
+            return list.at(0);
+        else
+            return list;
+    } else if (UA_Variant_isScalar(&var)) {
+        return scalarToQVariant<TARGETTYPE, UATYPE>(temp, type);
+    } else if (var.arrayLength == 0 && var.data == UA_EMPTY_ARRAY_SENTINEL) {
+        return QVariantList(); // Return empty QVariantList for empty array
     }
-    UATYPE *temp = static_cast<UATYPE *>(var.data);
-    return scalarToQVariant<TARGETTYPE, UATYPE>(temp, type);
+
+    return QVariant(); // Return empty QVariant for empty scalar variant
 }
 
 template<typename TARGETTYPE, typename QTTYPE>
diff --git a/tests/auto/qopcuaclient/tst_client.cpp b/tests/auto/qopcuaclient/tst_client.cpp
index 069ea75..b9b0d99 100644
--- a/tests/auto/qopcuaclient/tst_client.cpp
+++ b/tests/auto/qopcuaclient/tst_client.cpp
@@ -188,6 +188,8 @@ private slots:
     void writeInvalidNode();
     defineDataMethod(writeMultipleAttributes_data)
     void writeMultipleAttributes();
+    defineDataMethod(readEmptyArrayVariable_data)
+    void readEmptyArrayVariable();
 
     defineDataMethod(getRootNode_data)
     void getRootNode();
@@ -506,6 +508,19 @@ void Tst_QOpcUaClient::writeMultipleAttributes()
     QVERIFY(node->attribute(QOpcUa::NodeAttribute::Value).value<QOpcUa::QQualifiedName>() == QOpcUa::QQualifiedName(2, QStringLiteral("TestString")));
 }
 
+void Tst_QOpcUaClient::readEmptyArrayVariable()
+{
+    QFETCH(QOpcUaClient *, opcuaClient);
+    OpcuaConnector connector(opcuaClient, m_endpoint);
+
+    QScopedPointer<QOpcUaNode> node(opcuaClient->node("ns=2;s=EmptyBoolArray"));
+    QVERIFY(node != 0);
+
+    READ_MANDATORY_VARIABLE_NODE(node);
+    QCOMPARE(node->attribute(QOpcUa::NodeAttribute::Value).type(), QVariant::List);
+    QVERIFY(node->attribute(QOpcUa::NodeAttribute::Value).toList().isEmpty());
+}
+
 void Tst_QOpcUaClient::getRootNode()
 {
     QFETCH(QOpcUaClient *, opcuaClient);
diff --git a/tests/open62541-testserver/main.cpp b/tests/open62541-testserver/main.cpp
index 55907fa..8f41763 100644
--- a/tests/open62541-testserver/main.cpp
+++ b/tests/open62541-testserver/main.cpp
@@ -156,5 +156,7 @@ int main(int argc, char **argv)
 
     server.addMethod(testFolder, "ns=3;s=Test.Method.Multiply", "MultiplyDoubles");
 
+    server.addEmptyArrayVariable(testFolder, "ns=2;s=EmptyBoolArray", "EmptyBoolArrayTest");
+
     return app.exec();
 }
diff --git a/tests/open62541-testserver/testserver.cpp b/tests/open62541-testserver/testserver.cpp
index 22d3fd2..d02d5c8 100644
--- a/tests/open62541-testserver/testserver.cpp
+++ b/tests/open62541-testserver/testserver.cpp
@@ -192,6 +192,42 @@ UA_NodeId TestServer::addVariable(const UA_NodeId &folder, const QString &variab
     return resultId;
 }
 
+UA_NodeId TestServer::addEmptyArrayVariable(const UA_NodeId &folder, const QString &variableNode, const QString &name)
+{
+    UA_NodeId variableNodeId = Open62541Utils::nodeIdFromQString(variableNode);
+
+    UA_VariableAttributes attr = UA_VariableAttributes_default;
+    attr.displayName = UA_LOCALIZEDTEXT_ALLOC("en_US", name.toUtf8().constData());
+    attr.dataType = UA_TYPES[UA_TYPES_BOOLEAN].typeId;
+    attr.accessLevel = UA_ACCESSLEVELMASK_READ;
+    attr.valueRank = 1;
+    attr.value.arrayLength = 0;
+    attr.value.type = &UA_TYPES[UA_TYPES_BOOLEAN];
+    attr.value.data = UA_EMPTY_ARRAY_SENTINEL;
+
+    UA_QualifiedName variableName;
+    variableName.namespaceIndex = variableNodeId.namespaceIndex;
+    variableName.name = attr.displayName.text;
+
+    UA_NodeId resultId;
+    UA_StatusCode result = UA_Server_addVariableNode(m_server,
+                                                     variableNodeId,
+                                                     folder,
+                                                     UA_NODEID_NUMERIC(0, UA_NS0ID_ORGANIZES),
+                                                     variableName,
+                                                     UA_NODEID_NULL,
+                                                     attr,
+                                                     NULL,
+                                                     &resultId);
+
+    if (result != UA_STATUSCODE_GOOD) {
+        qWarning() << "Could not add empty array variable:" << result;
+        return UA_NODEID_NULL;
+    }
+
+    return resultId;
+}
+
 UA_StatusCode TestServer::multiplyMethod(UA_Server *server, const UA_NodeId *sessionId, void *sessionHandle, const UA_NodeId *methodId, void *methodContext, const UA_NodeId *objectId, void *objectContext, size_t inputSize, const UA_Variant *input, size_t outputSize, UA_Variant *output)
 {
     Q_UNUSED(server);
diff --git a/tests/open62541-testserver/testserver.h b/tests/open62541-testserver/testserver.h
index 046a994..9f69ab6 100644
--- a/tests/open62541-testserver/testserver.h
+++ b/tests/open62541-testserver/testserver.h
@@ -60,6 +60,7 @@ public:
     UA_NodeId addObject(const UA_NodeId &folderId, int namespaceIndex, const QString &objectName = QString());
 
     UA_NodeId addVariable(const UA_NodeId &folder, const QString &variableNode, const QString &name, const QVariant &value, QOpcUa::Types type);
+    UA_NodeId addEmptyArrayVariable(const UA_NodeId &folder, const QString &variableNode, const QString &name);
 
     UA_NodeId addMethod(const UA_NodeId &folder, const QString &variableNode, const QString &description);