From 4a98497529eb6f5a07d334583962bdffd65dd380 Mon Sep 17 00:00:00 2001
From: sumeerbhola <sumeer@cockroachlabs.com>
Date: Wed, 2 Sep 2020 09:45:45 -0400
Subject: [PATCH] Fix segfault in SimplePointInAreaLocator caused by casting
 MultiPolygon to Polygon

References https://trac.osgeo.org/geos/ticket/1047
References https://github.com/cockroachdb/cockroach/issues/53254
---
 .../locate/SimplePointInAreaLocator.cpp       | 20 ++++++++++---------
 tests/unit/algorithm/PointLocatorTest.cpp     | 19 ++++++++++++++++++
 2 files changed, 30 insertions(+), 9 deletions(-)

diff --git a/src/algorithm/locate/SimplePointInAreaLocator.cpp b/src/algorithm/locate/SimplePointInAreaLocator.cpp
index 93e9482872..399bab308c 100644
--- a/src/algorithm/locate/SimplePointInAreaLocator.cpp
+++ b/src/algorithm/locate/SimplePointInAreaLocator.cpp
@@ -67,15 +67,17 @@ SimplePointInAreaLocator::locateInGeometry(const Coordinate& p, const Geometry*
     }
 
     if (geom->getNumGeometries() == 1) {
-        return locatePointInPolygon(p, dynamic_cast<const Polygon*>(geom->getGeometryN(0)));
-    } else {
-        for (size_t i = 0; i < geom->getNumGeometries(); i++) {
-            const Geometry* gi = geom->getGeometryN(i);
-
-            auto loc = locateInGeometry(p, gi);
-            if(loc != Location::EXTERIOR) {
-                return loc;
-            }
+        auto poly = dynamic_cast<const Polygon*>(geom->getGeometryN(0));
+        if (poly) {
+            return locatePointInPolygon(p, poly);
+        }
+        // Else it is a collection with a single element. Will be handled below.
+    }
+    for (size_t i = 0; i < geom->getNumGeometries(); i++) {
+        const Geometry* gi = geom->getGeometryN(i);
+        auto loc = locateInGeometry(p, gi);
+        if(loc != Location::EXTERIOR) {
+            return loc;
         }
     }
 
diff --git a/tests/unit/algorithm/PointLocatorTest.cpp b/tests/unit/algorithm/PointLocatorTest.cpp
index bc63b0776d..a230d96864 100644
--- a/tests/unit/algorithm/PointLocatorTest.cpp
+++ b/tests/unit/algorithm/PointLocatorTest.cpp
@@ -5,6 +5,7 @@
 #include <tut/tut.hpp>
 // geos
 #include <geos/io/WKTReader.h>
+#include <geos/algorithm/locate/SimplePointInAreaLocator.h>
 #include <geos/algorithm/PointLocator.h>
 #include <geos/geom/PrecisionModel.h>
 #include <geos/geom/GeometryFactory.h>
@@ -56,6 +57,14 @@ runPtLocator(Location expected, const Coordinate& pt,
     ensure_equals(loc, expected);
 }
 
+void
+runSimplePtLocator(Location expected, const Coordinate& pt,
+             const std::string& wkt)
+{
+    GeomPtr geom(reader.read(wkt));
+    Location loc = geos::algorithm::locate::SimplePointInAreaLocator::locate(pt, geom.get());
+    ensure_equals(loc, expected);
+}
 
 //
 // Test Cases
@@ -111,5 +120,15 @@ void object::test<5>
                  "MULTIPOINT ((1 1), (0 0))");
 }
 
+// 6 - TestPointLocator Point inside GeometryCollection containing MultiPolygon, using SimplePointInAreaLocator.
+template<>
+template<>
+void object::test<6>
+()
+{
+    runSimplePtLocator(Location::INTERIOR, Coordinate(0, 0),
+                       "GEOMETRYCOLLECTION (MULTIPOLYGON (((-1 -1, 1 -1, 1 1, -1 1, -1 -1))))");
+}
+
 } // namespace tut