From 0b81e828add7e77fd3aecaf46955f7d1a84321ae Mon Sep 17 00:00:00 2001
From: Paolo Angelelli <paolo.angelelli.qt@gmail.com>
Date: Wed, 12 Feb 2020 23:50:23 +0100
Subject: Fix segmentation fault due to null pointer usage

Change-Id: I3b030728b32af6e340738583f78b2cfb0d2df11a
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: Alex Blasche <alexander.blasche@qt.io>
---
 .../qdeclarativepolylinemapitem.cpp                | 41 +++++++++++++++++++---
 .../qdeclarativepolylinemapitem_p_p.h              | 26 ++------------
 2 files changed, 39 insertions(+), 28 deletions(-)

diff --git a/src/location/declarativemaps/qdeclarativepolylinemapitem.cpp b/src/location/declarativemaps/qdeclarativepolylinemapitem.cpp
index f914b36d..d40c1b79 100644
--- a/src/location/declarativemaps/qdeclarativepolylinemapitem.cpp
+++ b/src/location/declarativemaps/qdeclarativepolylinemapitem.cpp
@@ -1947,8 +1947,8 @@ bool QGeoMapItemLODGeometry::isLODActive(unsigned int lod) const
 class PolylineSimplifyTask : public QRunnable
 {
 public:
-    PolylineSimplifyTask(QSharedPointer<QVector<QDeclarativeGeoMapItemUtils::vec2> > &input, // reference as it gets copied in the nested call
-                         QSharedPointer<QVector<QDeclarativeGeoMapItemUtils::vec2> > &output,
+    PolylineSimplifyTask(const QSharedPointer<QVector<QDeclarativeGeoMapItemUtils::vec2> > &input, // reference as it gets copied in the nested call
+                         const QSharedPointer<QVector<QDeclarativeGeoMapItemUtils::vec2> > &output,
                          double leftBound,
                          unsigned int zoom,
                          QSharedPointer<unsigned int> &working)
@@ -1958,6 +1958,8 @@ public:
         , m_output(output)
         , m_working(working)
     {
+        Q_ASSERT(!input.isNull());
+        Q_ASSERT(!output.isNull());
     }
 
     ~PolylineSimplifyTask() override;
@@ -1967,9 +1969,11 @@ public:
         // Skip sending notifications for now. Updated data will be picked up eventually.
         // ToDo: figure out how to connect a signal from here to a slot in the item.
         *m_working = QGeoMapPolylineGeometryOpenGL::zoomToLOD(m_zoom);
-        *m_output = QGeoMapPolylineGeometryOpenGL::getSimplified( *m_input,
+        const QVector<QDeclarativeGeoMapItemUtils::vec2> res =
+                QGeoMapPolylineGeometryOpenGL::getSimplified( *m_input,
                                    m_leftBound,
                                    QGeoMapPolylineGeometryOpenGL::zoomForLOD(m_zoom));
+        *m_output = res;
         *m_working = 0;
     }
 
@@ -1979,12 +1983,14 @@ public:
     QSharedPointer<unsigned int> m_working;
 };
 
-void QGeoMapItemLODGeometry::enqueueSimplificationTask(QSharedPointer<QVector<QDeclarativeGeoMapItemUtils::vec2> > &input,
-                                                  QSharedPointer<QVector<QDeclarativeGeoMapItemUtils::vec2> > &output,
+void QGeoMapItemLODGeometry::enqueueSimplificationTask(const QSharedPointer<QVector<QDeclarativeGeoMapItemUtils::vec2> > &input,
+                                                  const QSharedPointer<QVector<QDeclarativeGeoMapItemUtils::vec2> > &output,
                                                   double leftBound,
                                                   unsigned int zoom,
                                                   QSharedPointer<unsigned int> &working)
 {
+    Q_ASSERT(!input.isNull());
+    Q_ASSERT(!output.isNull());
     PolylineSimplifyTask *task = new PolylineSimplifyTask(input,
                                                           output,
                                                           leftBound,
@@ -2032,6 +2038,31 @@ void QGeoMapItemLODGeometry::selectLOD(unsigned int zoom, double leftBound, bool
     }
 }
 
+void QGeoMapItemLODGeometry::selectLODOnDataChanged(unsigned int zoom, double leftBound) const
+{
+    unsigned int lod = zoomToLOD(zoom);
+    if (lod > 0) {
+        // Generate ZL 1 as fallback for all cases != 0. Do not do if 0 is requested
+        // (= old behavior, LOD disabled)
+        m_verticesLOD[1] = QSharedPointer<QVector<QDeclarativeGeoMapItemUtils::vec2>>(
+                                new QVector<QDeclarativeGeoMapItemUtils::vec2>);
+        *m_verticesLOD[1] = getSimplified( *m_verticesLOD[0],
+                leftBound,
+                zoomForLOD(0));
+    }
+    if (lod > 1) {
+        if (!m_verticesLOD[lod])
+            m_verticesLOD[lod] = QSharedPointer<QVector<QDeclarativeGeoMapItemUtils::vec2>>(
+                                    new QVector<QDeclarativeGeoMapItemUtils::vec2>);
+        enqueueSimplificationTask(  m_verticesLOD.at(0),
+                                    m_verticesLOD[lod],
+                leftBound,
+                zoom,
+                m_working);
+    }
+    m_screenVertices = m_verticesLOD[qMin<unsigned int>(lod, 1)].data(); // return only 0,1 synchronously
+}
+
 unsigned int QGeoMapItemLODGeometry::zoomToLOD(unsigned int zoom)
 {
     unsigned int res;
diff --git a/src/location/declarativemaps/qdeclarativepolylinemapitem_p_p.h b/src/location/declarativemaps/qdeclarativepolylinemapitem_p_p.h
index 35d52790..2a588222 100644
--- a/src/location/declarativemaps/qdeclarativepolylinemapitem_p_p.h
+++ b/src/location/declarativemaps/qdeclarativepolylinemapitem_p_p.h
@@ -249,33 +249,13 @@ public:
                               double leftBoundWrapped,
                               unsigned int zoom);
 
-    static void enqueueSimplificationTask(QSharedPointer<QVector<QDeclarativeGeoMapItemUtils::vec2> > &input, // reference as it gets copied in the nested call
-                              QSharedPointer<QVector<QDeclarativeGeoMapItemUtils::vec2> > &output,
+    static void enqueueSimplificationTask(const QSharedPointer<QVector<QDeclarativeGeoMapItemUtils::vec2> > &input, // reference as it gets copied in the nested call
+                              const QSharedPointer<QVector<QDeclarativeGeoMapItemUtils::vec2> > &output,
                               double leftBound,
                               unsigned int zoom,
                               QSharedPointer<unsigned int> &working);
 
-    void selectLODOnDataChanged(unsigned int zoom, double leftBound) const
-    {
-        unsigned int lod = zoomToLOD(zoom);
-        if (lod > 0) {
-            // Generate ZL 1 as fallback for all cases != 0. Do not do if 0 is requested
-            // (= old behavior, LOD disabled)
-            m_verticesLOD[1] = QSharedPointer<QVector<QDeclarativeGeoMapItemUtils::vec2>>(
-                                new QVector<QDeclarativeGeoMapItemUtils::vec2>);
-            *m_verticesLOD[1] = getSimplified( *m_verticesLOD[0],
-                                       leftBound,
-                                       zoomForLOD(0));
-        }
-        if (lod > 1) {
-            enqueueSimplificationTask(  m_verticesLOD.at(0),
-                                        m_verticesLOD[zoomToLOD(zoom)],
-                                        leftBound,
-                                        zoom,
-                                        m_working);
-        }
-        m_screenVertices = m_verticesLOD[qMin<unsigned int>(lod, 1)].data();
-    }
+    void selectLODOnDataChanged(unsigned int zoom, double leftBound) const;
 
     bool selectLODOnLODMismatch(unsigned int zoom, double leftBound, bool closed) const
     {
-- 
cgit v1.2.1