Fix null pointer dereferencing coverity issues in qdoc

This patch fixes potential null pointer derefencing issues all
over qdoc project that has been found via coverity scan and has been
assigned to "Dereference after null check" category.

Fix include coverity issues with REVERSE_NULL as well as FOWARD_NULL
cases.

Change-Id: Icb6f413ea7bbfae76f8e68139baa31b15575a49a
Coverity-Id: 163245
Coverity-Id: 11133
Coverity-Id: 185270
Coverity-Id: 226086
Reviewed-by: Topi Reiniö <topi.reinio@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

3 files changed, 12 insertions, 7 deletions

diff --git a/src/qdoc/htmlgenerator.cpp b/src/qdoc/htmlgenerator.cpp
index 2114d6a8c..5bfa2daeb 100644
--- a/src/qdoc/htmlgenerator.cpp
+++ b/src/qdoc/htmlgenerator.cpp
@@ -1909,7 +1909,7 @@ void HtmlGenerator::generateNavigationBar(const QString &title,
                                           const QString &buildversion,
                                           bool tableItems)
 {
-    if (noNavigationBar)
+    if (noNavigationBar || node == nullptr)
         return;
 
     Text navigationbar;
@@ -2879,7 +2879,7 @@ void HtmlGenerator::generateAnnotatedList(const Node *relative,
                                           CodeMarker *marker,
                                           const NodeMultiMap &nmm)
 {
-    if (nmm.isEmpty())
+    if (nmm.isEmpty() || relative == nullptr)
         return;
     generateAnnotatedList(relative, marker, nmm.values());
 }
diff --git a/src/qdoc/qdocindexfiles.cpp b/src/qdoc/qdocindexfiles.cpp
index 9ea7d9f86..9ded66abb 100644
--- a/src/qdoc/qdocindexfiles.cpp
+++ b/src/qdoc/qdocindexfiles.cpp
@@ -157,6 +157,11 @@ void QDocIndexFiles::readIndexFile(const QString &path)
     basesList_.clear();
 
     NamespaceNode *root = qdb_->newIndexTree(project_);
+    if (!root) {
+        qWarning() << "Issue parsing index tree" << path;
+        return;
+    }
+
     root->tree()->setIndexTitle(indexTitle);
 
     // Scan all elements in the XML file, constructing a map that contains
@@ -387,7 +392,7 @@ void QDocIndexFiles::readIndexSection(QXmlStreamReader& reader,
         } else
             goto done;
 
-        if (current && current->isExample()) {
+        if (current->isExample()) {
             ExampleNode *en = static_cast<ExampleNode *>(current);
             if (subtype == QDocAttrFile) {
                 en->appendFile(name);
diff --git a/src/qdoc/webxmlgenerator.cpp b/src/qdoc/webxmlgenerator.cpp
index 73f6f6268..4b649820f 100644
--- a/src/qdoc/webxmlgenerator.cpp
+++ b/src/qdoc/webxmlgenerator.cpp
@@ -289,6 +289,9 @@ const Atom *WebXMLGenerator::addAtomElements(QXmlStreamWriter &writer,
 {
     bool keepQuoting = false;
 
+    if (!atom)
+        return nullptr;
+
     switch (atom->type()) {
     case Atom::AnnotatedList:
     {
@@ -750,11 +753,8 @@ const Atom *WebXMLGenerator::addAtomElements(QXmlStreamWriter &writer,
     }
 
     hasQuotingInformation = keepQuoting;
+    return atom->next();
 
-    if (atom)
-        return atom->next();
-
-    return nullptr;
 }
 
 void WebXMLGenerator::startLink(QXmlStreamWriter &writer, const Atom *atom,