From ba6b92f34116551facd913c4cc93e457ab2b24e4 Mon Sep 17 00:00:00 2001
From: John Preston <johnprestonmail@gmail.com>
Date: Fri, 30 Aug 2019 12:42:03 +0300
Subject: [PATCH] Check for layer parent-child cycles.

---
 src/lottie/lottieitem.cpp | 15 ++++++++++++++-
 src/lottie/lottieitem.h   |  1 +
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/src/lottie/lottieitem.cpp b/src/lottie/lottieitem.cpp
index 95e8d369c9..09d14a4e67 100644
--- a/src/lottie/lottieitem.cpp
+++ b/src/lottie/lottieitem.cpp
@@ -69,6 +69,16 @@ static bool strokeProp(rlottie::Property prop)
     }
 }
 
+static bool isGoodParentLayer(LOTLayerItem *parent, LOTLayerItem *child) {
+    do {
+        if (parent == child) {
+            return false;
+        }
+        parent = parent->resolvedParentLayer();
+    } while (parent);
+    return true;
+}
+
 LOTCompItem::LOTCompItem(LOTModel *model)
     : mCurFrameNo(-1)
 {
@@ -520,7 +530,10 @@ LOTCompLayerItem::LOTCompLayerItem(LOTLayerData *layerModel)
             auto search =
                 std::find_if(mLayers.begin(), mLayers.end(),
                              [id](const auto &val) { return val->id() == id; });
-            if (search != mLayers.end()) layer->setParentLayer((*search).get());
+            if (search != mLayers.end() &&
+                isGoodParentLayer((*search).get(), layer.get())) {
+                layer->setParentLayer((*search).get());
+            }
         }
     }
 
diff --git a/src/lottie/lottieitem.h b/src/lottie/lottieitem.h
index b3165ef059..a359791291 100644
--- a/src/lottie/lottieitem.h
+++ b/src/lottie/lottieitem.h
@@ -107,6 +107,7 @@ public:
    int id() const {return mLayerData->id();}
    int parentId() const {return mLayerData->parentId();}
    void setParentLayer(LOTLayerItem *parent){mParentLayer = parent;}
+   LOTLayerItem *resolvedParentLayer() const {return mParentLayer;}
    void setComplexContent(bool value) { mComplexContent = value;}
    bool complexContent() const {return mComplexContent;}
    virtual void update(int frameNo, const VMatrix &parentMatrix, float parentAlpha);