Don't create default constructed entries in m_attributeMapping (uacpp)

Using QHash::operator[] with a key that does not exist inserts a default
constructed value.
modifyMonitoring() and disableMonitoring() in uacppbackend.cpp use
m_attributeMapping[handle][attr] to check if an entry exists. Calling
these methods for handle/attribute pairs that are not being monitored
fills m_attributeMapping with default constructed values.
Checking if the QHash contains the expected values avoids that.

Change-Id: I80804a1b3af5d7f9fa86a14c6f9a371a36614f6e
Reviewed-by: Maurice Kalinowski <maurice.kalinowski@qt.io>

2 files changed, 17 insertions, 3 deletions

diff --git a/src/plugins/opcua/uacpp/quacppbackend.cpp b/src/plugins/opcua/uacpp/quacppbackend.cpp
index 694ead1..8f4bc2d 100644
--- a/src/plugins/opcua/uacpp/quacppbackend.cpp
+++ b/src/plugins/opcua/uacpp/quacppbackend.cpp
@@ -358,7 +358,7 @@ void UACppAsyncBackend::enableMonitoring(uintptr_t handle, const UaNodeId &id, Q
 
 void UACppAsyncBackend::modifyMonitoring(uintptr_t handle, QOpcUa::NodeAttribute attr, QOpcUaMonitoringParameters::Parameter item, QVariant value)
 {
-    QUACppSubscription *subscription = m_attributeMapping[handle][attr];
+    QUACppSubscription *subscription = getSubscriptionForItem(handle, attr);
     if (!subscription) {
         qCWarning(QT_OPCUA_PLUGINS_UACPP, "Could not modify parameter for %lu, the monitored item does not exist", handle);
         QOpcUaMonitoringParameters p;
@@ -373,7 +373,7 @@ void UACppAsyncBackend::modifyMonitoring(uintptr_t handle, QOpcUa::NodeAttribute
 void UACppAsyncBackend::disableMonitoring(uintptr_t handle, QOpcUa::NodeAttributes attr)
 {
     qt_forEachAttribute(attr, [&](QOpcUa::NodeAttribute attribute){
-        QUACppSubscription *sub = m_attributeMapping[handle][attribute];
+        QUACppSubscription *sub = getSubscriptionForItem(handle, attribute);
         if (sub) {
             sub->removeAttributeMonitoredItem(handle, attribute);
             if (sub->monitoredItemsCount() == 0)
@@ -438,6 +438,18 @@ QUACppSubscription *UACppAsyncBackend::getSubscription(const QOpcUaMonitoringPar
     return sub;
 }
 
+QUACppSubscription *UACppAsyncBackend::getSubscriptionForItem(uintptr_t handle, QOpcUa::NodeAttribute attr)
+{
+    auto entriesForHandle = m_attributeMapping.find(handle);
+    if (entriesForHandle == m_attributeMapping.end())
+        return nullptr;
+    auto subscription = entriesForHandle->find(attr);
+    if (subscription == entriesForHandle->end())
+        return nullptr;
+
+    return subscription.value();
+}
+
 bool UACppAsyncBackend::removeSubscription(quint32 subscriptionId)
 {
     auto sub = m_subscriptions.find(subscriptionId);
diff --git a/src/plugins/opcua/uacpp/quacppbackend.h b/src/plugins/opcua/uacpp/quacppbackend.h
index df5edea..241f86c 100644
--- a/src/plugins/opcua/uacpp/quacppbackend.h
+++ b/src/plugins/opcua/uacpp/quacppbackend.h
@@ -60,10 +60,12 @@ public Q_SLOTS:
     void disableMonitoring(uintptr_t handle, QOpcUa::NodeAttributes attr);
     void callMethod(uintptr_t handle, const UaNodeId &objectId, const UaNodeId &methodId, QVector<QOpcUa::TypedVariant> args);
 
-    QUACppSubscription *getSubscription(const QOpcUaMonitoringParameters &settings);
     bool removeSubscription(quint32 subscriptionId);
 
 public:
+    QUACppSubscription *getSubscription(const QOpcUaMonitoringParameters &settings);
+    QUACppSubscription *getSubscriptionForItem(uintptr_t handle, QOpcUa::NodeAttribute attr);
+
     Q_DISABLE_COPY(UACppAsyncBackend);
     UaClientSdk::UaSession *m_nativeSession;
     QUACppClient *m_clientImpl;