Fix crash on recursive self-referral in <use> element

Referring to an ancestor in a <use> element would lead to endless
recursion. Add checks to avoid recursion, and also emit a warning
while parsing.

Task-number: QTBUG-64425
Change-Id: I9ee1b9bfef13796cc3f387ff8579c6b13bc4ae9a
Reviewed-by: Andy Shaw <andy.shaw@qt.io>

1 files changed, 11 insertions, 0 deletions

diff --git a/src/svg/qsvgnode.cpp b/src/svg/qsvgnode.cpp
index e504522..14aaea4 100644
--- a/src/svg/qsvgnode.cpp
+++ b/src/svg/qsvgnode.cpp
@@ -57,6 +57,17 @@ QSvgNode::~QSvgNode()
 
 }
 
+bool QSvgNode::isDescendantOf(const QSvgNode *parent) const
+{
+    const QSvgNode *n = this;
+    while (n) {
+        if (n == parent)
+            return true;
+        n = n->m_parent;
+    }
+    return false;
+}
+
 void QSvgNode::appendStyleProperty(QSvgStyleProperty *prop, const QString &id)
 {
     //qDebug()<<"appending "<<prop->type()<< " ("<< id <<") "<<"to "<<this<<this->type();