When creating geometry collections for GEOS, skip any empty parts

These can cause crashes in GEOS functions Fixes #37688 (cherry picked from commit 6ddff0d)
qgis · Jul 10, 2020 · 89d0211 · 89d0211
1 parent 7ac65f3
commit 89d0211
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Showing 2 changed files with 36 additions and 2 deletions.
diff --git a/src/core/geometry/qgsgeos.cpp b/src/core/geometry/qgsgeos.cpp
@@ -1059,8 +1059,18 @@ geos::unique_ptr QgsGeos::createGeosCollection( int typeId, const QVector<GEOSGe
   {
     if ( *geomIt )
     {
-      geomarr[i] = *geomIt;
-      ++i;
+      if ( GEOSisEmpty_r( geosinit.ctxt, *geomIt ) )
+      {
+        // don't add empty parts to a geos collection, it can cause crashes in GEOS
+        nNullGeoms++;
+        nNotNullGeoms--;
+        GEOSGeom_destroy_r( geosinit.ctxt, *geomIt );
+      }
+      else
+      {
+        geomarr[i] = *geomIt;
+        ++i;
+      }
     }
   }
   geos::unique_ptr geom;

diff --git a/tests/src/core/testqgsgeometry.cpp b/tests/src/core/testqgsgeometry.cpp
@@ -52,6 +52,7 @@
 #include "qgscurvepolygon.h"
 #include "qgsproject.h"
 #include "qgslinesegment.h"
+#include "qgsgeos.h"
 
 //qgs unit test utility class
 #include "qgsrenderchecker.h"
@@ -85,6 +86,7 @@ class TestQgsGeometry : public QObject
     void vertexIterator();
     void partIterator();
 
+    void geos();
 
     // geometry types
     void point(); //test QgsPointV2
@@ -522,6 +524,28 @@ void TestQgsGeometry::partIterator()
   // See test_qgsgeometry.py for geometry-type specific checks!
 }
 
+void TestQgsGeometry::geos()
+{
+  // test GEOS conversion utils
+
+  // empty parts should NOT be added to a GEOS collection -- it can cause crashes in GEOS
+  QgsMultiPolygon polyWithEmptyParts;
+  geos::unique_ptr asGeos( QgsGeos::asGeos( &polyWithEmptyParts ) );
+  QgsGeometry res( QgsGeos::fromGeos( asGeos.get() ) );
+  QCOMPARE( res.asWkt(), QStringLiteral( "MultiPolygon EMPTY" ) );
+  std::unique_ptr< QgsPolygon > emptyPolygon = qgis::make_unique< QgsPolygon >();
+  emptyPolygon->setExteriorRing( new QgsLineString() );
+  polyWithEmptyParts.addGeometry( emptyPolygon->clone() );
+  std::unique_ptr< QgsPolygon > nonEmptyPolygon = qgis::make_unique< QgsPolygon >();
+  nonEmptyPolygon->setExteriorRing( new QgsLineString( QVector< QgsPoint >() << QgsPoint( 0, 0 ) << QgsPoint( 0, 1 ) << QgsPoint( 1, 1 ) << QgsPoint( 0, 0 ) ) );
+  polyWithEmptyParts.addGeometry( nonEmptyPolygon->clone() );
+  polyWithEmptyParts.addGeometry( emptyPolygon->clone() );
+  asGeos = QgsGeos::asGeos( &polyWithEmptyParts );
+  QCOMPARE( GEOSGetNumGeometries_r( QgsGeos::getGEOSHandler(), asGeos.get() ), 1 );
+  res = QgsGeometry( QgsGeos::fromGeos( asGeos.get() ) );
+  QCOMPARE( res.asWkt(), QStringLiteral( "MultiPolygon (((0 0, 0 1, 1 1, 0 0)))" ) );
+}
+
 void TestQgsGeometry::point()
 {
   //test QgsPointV2