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, 2 insertions, 13 deletions

diff --git a/src/xmlpatterns/api/qabstractxmlnodemodel.cpp b/src/xmlpatterns/api/qabstractxmlnodemodel.cpp
index 27240f9..6c299dd 100644
--- a/src/xmlpatterns/api/qabstractxmlnodemodel.cpp
+++ b/src/xmlpatterns/api/qabstractxmlnodemodel.cpp
@@ -1138,9 +1138,7 @@ bool QAbstractXmlNodeModel::isDeepEqual(const QXmlNodeModelIndex &n1,
  */
 QXmlItem::QXmlItem()
 {
-    m_node.model = 0;
-    m_node.data = 0;
-    m_node.additionalData = 0;
+    m_node.reset();
 }
 
 bool QXmlItem::internalIsAtomicValue() const
@@ -1164,12 +1162,10 @@ QXmlItem::QXmlItem(const QXmlItem &other) : m_node(other.m_node)
  */
 QXmlItem::QXmlItem(const QVariant &atomicValue)
 {
+    m_node.reset();
     if(atomicValue.isNull())
     {
         /* Then we behave just like the default constructor. */
-        m_node.model = 0;
-        m_node.data = 0;
-        m_node.additionalData = 0;
         return;
     }
 
@@ -1185,13 +1181,6 @@ QXmlItem::QXmlItem(const QVariant &atomicValue)
         m_node.model = reinterpret_cast<const QAbstractXmlNodeModel *>(~0);
         m_atomicValue = temp.asAtomicValue();
     }
-    else
-    {
-        m_atomicValue = 0;
-        m_node.model = 0;
-    }
-
-    m_node.additionalData = 0;
 }
 
 /*!