Fix access to uninitialized values in QtXmlPatterns

Fixes valgrind warning like below when executing tst_QXmlQuery::copyConstructor()
  Conditional jump or move depends on uninitialised value(s)
    at: QPatternist::NodeIndexStorage::operator!=(QPatternist::NodeIndexStorage const&) const (qabstractxmlnodemodel.cpp:1220)
    by: QXmlItem::operator=(QXmlItem const&) (qabstractxmlnodemodel.cpp:1228)

Reason for the warning is that QPatternist::NodeIndexStorage::operator!=
accesses all fields of NodeIndexStorage, which are all not intialized in
every execution path of QXmlItem::QXmlItem(const QVariant &) and class
QPatternist::Item constructors.

Fixed by adding NodeIndexStorage::reset() function that resets all fields
and put a call to that function where NodeIndexStorage objects were
previously incompletely initialized. Note that unfortunately class
NodeIndexStorage cannot have a default constructor, because it is used as
a union field.

Change-Id: I758df57551ec49ce8c8b357794177b4e6c454d2f
Sanity-Review: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Dmitry Trofimov
Reviewed-by: Robin Burchell <robin+qt@viroteck.net>

1 files changed, 8 insertions, 3 deletions

diff --git a/src/xmlpatterns/api/qabstractxmlnodemodel.h b/src/xmlpatterns/api/qabstractxmlnodemodel.h
index abd94437..dcfb388c 100644
--- a/src/xmlpatterns/api/qabstractxmlnodemodel.h
+++ b/src/xmlpatterns/api/qabstractxmlnodemodel.h
@@ -104,6 +104,13 @@ namespace QPatternist
 
         /* Implementation is in qabstractxmlnodemodel.cpp. */
         inline bool operator!=(const NodeIndexStorage &other) const;
+
+        void reset()
+        {
+            data = 0;
+            additionalData = 0;
+            model = 0;
+        }
     };
 }
 
@@ -216,9 +223,7 @@ public:
 
     inline void reset()
     {
-        m_storage.data = 0;
-        m_storage.additionalData = 0;
-        m_storage.model = 0;
+        m_storage.reset();
     }
 
 private: