Fixing crash when stopping poll loop

When stopping the neard adapter poll loop without
starting it from the same QNearFieldManagerPrivateImpl
instance the m_adapter variable does not hold a
valid pointer to an instance of OrgNeardAdapterInterface.

This patch fixes that issue by creating a temporary
instance on the stack to call the appropriate function
on the D-Bus interface.

Change-Id: I42ced8d00ca9f87756c8f3f81ca78969702344c1
Reviewed-by: Martin Leutelt <martin.leutelt@basyskom.com>
Reviewed-by: Alex Blasche <alexander.blasche@digia.com>

2 files changed, 32 insertions, 30 deletions

diff --git a/src/nfc/qnearfieldmanager_neard.cpp b/src/nfc/qnearfieldmanager_neard.cpp
index 41331a23..65cf0ee3 100644
--- a/src/nfc/qnearfieldmanager_neard.cpp
+++ b/src/nfc/qnearfieldmanager_neard.cpp
@@ -54,8 +54,6 @@ Q_DECLARE_LOGGING_CATEGORY(QT_NFC_NEARD)
 // TODO We need a constructor that lets us select an adapter
 QNearFieldManagerPrivateImpl::QNearFieldManagerPrivateImpl()
     : QNearFieldManagerPrivate(),
-      m_adapter(0),
-      m_dbusProperties(0),
       m_neardHelper(NeardHelper::instance())
 {
     QDBusPendingReply<ManagedObjectList> reply = m_neardHelper->dbusObjectManager()->GetManagedObjects();
@@ -124,21 +122,18 @@ bool QNearFieldManagerPrivateImpl::startTargetDetection()
     if (!isAvailable())
         return false;
 
-    if (!m_dbusProperties) {
-        m_dbusProperties = new OrgFreedesktopDBusPropertiesInterface(QStringLiteral("org.neard"),
-                                                                     m_adapterPath,
-                                                                     QDBusConnection::systemBus(),
-                                                                     this);
-    }
+    OrgFreedesktopDBusPropertiesInterface dbusProperties(QStringLiteral("org.neard"),
+                                                         m_adapterPath,
+                                                         QDBusConnection::systemBus());
 
-    if (!m_dbusProperties->isValid()) {
+    if (!dbusProperties.isValid()) {
         qCWarning(QT_NFC_NEARD) << "dbus property interface invalid";
         return false;
     }
 
     // check if the adapter is currently polling
-    QDBusPendingReply<QDBusVariant> replyPolling = m_dbusProperties->Get(QStringLiteral("org.neard.Adapter"),
-                                                                         QStringLiteral("Polling"));
+    QDBusPendingReply<QDBusVariant> replyPolling = dbusProperties.Get(QStringLiteral("org.neard.Adapter"),
+                                                                      QStringLiteral("Polling"));
     replyPolling.waitForFinished();
     if (!replyPolling.isError()) {
         if (replyPolling.value().variant().toBool()) {
@@ -151,16 +146,16 @@ bool QNearFieldManagerPrivateImpl::startTargetDetection()
     }
 
     // check if the adapter it powered
-    QDBusPendingReply<QDBusVariant> replyPowered = m_dbusProperties->Get(QStringLiteral("org.neard.Adapter"),
-                                                                         QStringLiteral("Powered"));
+    QDBusPendingReply<QDBusVariant> replyPowered = dbusProperties.Get(QStringLiteral("org.neard.Adapter"),
+                                                                      QStringLiteral("Powered"));
     replyPowered.waitForFinished();
     if (!replyPowered.isError()) {
         if (replyPowered.value().variant().toBool()) {
             qCDebug(QT_NFC_NEARD) << "adapter is already powered";
         } else {
-            QDBusPendingReply<QDBusVariant> replyTryPowering = m_dbusProperties->Set(QStringLiteral("org.neard.Adapter"),
-                                                                                     QStringLiteral("Powered"),
-                                                                                     QDBusVariant(true));
+            QDBusPendingReply<QDBusVariant> replyTryPowering = dbusProperties.Set(QStringLiteral("org.neard.Adapter"),
+                                                                                  QStringLiteral("Powered"),
+                                                                                  QDBusVariant(true));
             replyTryPowering.waitForFinished();
             if (!replyTryPowering.isError()) {
                 qCDebug(QT_NFC_NEARD) << "powering adapter";
@@ -172,15 +167,12 @@ bool QNearFieldManagerPrivateImpl::startTargetDetection()
     }
 
     // create adapter and start poll loop
-    if (!m_adapter) {
-        m_adapter = new OrgNeardAdapterInterface(QStringLiteral("org.neard"),
-                                                 m_adapterPath,
-                                                 QDBusConnection::systemBus(),
-                                                 this);
-    }
+    OrgNeardAdapterInterface neardAdapter(QStringLiteral("org.neard"),
+                                          m_adapterPath,
+                                          QDBusConnection::systemBus());
 
     // possible modes: "Target", "Initiator", "Dual"
-    QDBusPendingReply<> replyPollLoop = m_adapter->StartPollLoop(QStringLiteral("Dual"));
+    QDBusPendingReply<> replyPollLoop = neardAdapter.StartPollLoop(QStringLiteral("Dual"));
     replyPollLoop.waitForFinished();
     if (replyPollLoop.isError()) {
         qCWarning(QT_NFC_NEARD) << "error when starting polling";
@@ -198,13 +190,27 @@ void QNearFieldManagerPrivateImpl::stopTargetDetection()
     if (!isAvailable())
         return;
 
+    OrgFreedesktopDBusPropertiesInterface dbusProperties(QStringLiteral("org.neard"),
+                                                         m_adapterPath,
+                                                         QDBusConnection::systemBus());
+
+    if (!dbusProperties.isValid()) {
+        qCWarning(QT_NFC_NEARD) << "dbus property interface invalid";
+        return;
+    }
+
     // check if the adapter is currently polling
-    QDBusPendingReply<QDBusVariant> replyPolling = m_dbusProperties->Get(QStringLiteral("org.neard.Adapter"),
-                                                                         QStringLiteral("Polling"));
+    QDBusPendingReply<QDBusVariant> replyPolling = dbusProperties.Get(QStringLiteral("org.neard.Adapter"),
+                                                                      QStringLiteral("Polling"));
     replyPolling.waitForFinished();
     if (!replyPolling.isError()) {
         if (replyPolling.value().variant().toBool()) {
-            QDBusPendingReply<> replyStopPolling = m_adapter->StopPollLoop();
+            // create adapter and stop poll loop
+            OrgNeardAdapterInterface neardAdapter(QStringLiteral("org.neard"),
+                                                  m_adapterPath,
+                                                  QDBusConnection::systemBus());
+
+            QDBusPendingReply<> replyStopPolling = neardAdapter.StopPollLoop();
             replyStopPolling.waitForFinished();
             if (replyStopPolling.isError())
                 qCWarning(QT_NFC_NEARD) << "error when stopping polling";
diff --git a/src/nfc/qnearfieldmanager_neard_p.h b/src/nfc/qnearfieldmanager_neard_p.h
index ee72595c..8df4149b 100644
--- a/src/nfc/qnearfieldmanager_neard_p.h
+++ b/src/nfc/qnearfieldmanager_neard_p.h
@@ -52,9 +52,7 @@
 #include <QDBusVariant>
 #include <QMap>
 
-class OrgNeardAdapterInterface;
 class OrgNeardManagerInterface;
-class OrgFreedesktopDBusPropertiesInterface;
 
 QT_BEGIN_NAMESPACE
 
@@ -89,8 +87,6 @@ private Q_SLOTS:
 
 private:
     QString m_adapterPath;
-    OrgNeardAdapterInterface *m_adapter;
-    OrgFreedesktopDBusPropertiesInterface *m_dbusProperties;
     QMap<QString, QNearFieldTarget*> m_activeTags;
     NeardHelper *m_neardHelper;
 };