[OGR provider] Make changeGeometryValues() accept null geometry

Fixes #15081

src/providers/ogr/qgsogrprovider.cpp

@@ -1323,9 +1323,6 @@ bool QgsOgrProvider::changeGeometryValues( const QgsGeometryMap &geometry_map )
   if ( !doInitialActionsForEdition() )
     return false;
 
-  OGRFeatureH theOGRFeature = nullptr;
-  OGRGeometryH theNewGeometry = nullptr;
-
   setRelevantFields( ogrLayer, true, attributeIndexes() );
 
   for ( QgsGeometryMap::const_iterator it = geometry_map.constBegin(); it != geometry_map.constEnd(); ++it )
@@ -1336,46 +1333,55 @@ bool QgsOgrProvider::changeGeometryValues( const QgsGeometryMap &geometry_map )
       continue;
     }
 
-    theOGRFeature = OGR_L_GetFeature( ogrLayer, static_cast<long>( FID_TO_NUMBER( it.key() ) ) );
+    OGRFeatureH theOGRFeature = OGR_L_GetFeature( ogrLayer, static_cast<long>( FID_TO_NUMBER( it.key() ) ) );
     if ( !theOGRFeature )
     {
       pushError( tr( "OGR error changing geometry: feature %1 not found" ).arg( it.key() ) );
       continue;
     }
 
-    //create an OGRGeometry
-    if ( OGR_G_CreateFromWkb( const_cast<unsigned char*>( it->asWkb() ),
-                              OGR_L_GetSpatialRef( ogrLayer ),
-                              &theNewGeometry,
-                              it->wkbSize() ) != OGRERR_NONE )
+    OGRGeometryH theNewGeometry = nullptr;
+    // We might receive null geometries. It is ok, but don't go through the
+    // OGR_G_CreateFromWkb() route then
+    if ( it->wkbSize() != 0 )
     {
-      pushError( tr( "OGR error creating geometry for feature %1: %2" ).arg( it.key() ).arg( CPLGetLastErrorMsg() ) );
-      OGR_G_DestroyGeometry( theNewGeometry );
-      theNewGeometry = nullptr;
-      continue;
-    }
+      //create an OGRGeometry
+      if ( OGR_G_CreateFromWkb( const_cast<unsigned char*>( it->asWkb() ),
+                                OGR_L_GetSpatialRef( ogrLayer ),
+                                &theNewGeometry,
+                                it->wkbSize() ) != OGRERR_NONE )
+      {
+        pushError( tr( "OGR error creating geometry for feature %1: %2" ).arg( it.key() ).arg( CPLGetLastErrorMsg() ) );
+        OGR_G_DestroyGeometry( theNewGeometry );
+        theNewGeometry = nullptr;
+        OGR_F_Destroy( theOGRFeature );
+        continue;
+      }
 
-    if ( !theNewGeometry )
-    {
-      pushError( tr( "OGR error in feature %1: geometry is null" ).arg( it.key() ) );
-      continue;
+      if ( !theNewGeometry )
+      {
+        pushError( tr( "OGR error in feature %1: geometry is null" ).arg( it.key() ) );
+        OGR_F_Destroy( theOGRFeature );
+        continue;
+      }
     }
 
     //set the new geometry
     if ( OGR_F_SetGeometryDirectly( theOGRFeature, theNewGeometry ) != OGRERR_NONE )
     {
       pushError( tr( "OGR error setting geometry of feature %1: %2" ).arg( it.key() ).arg( CPLGetLastErrorMsg() ) );
-      OGR_G_DestroyGeometry( theNewGeometry );
-      theNewGeometry = nullptr;
+      // Shouldn't happen normally. If it happens, ownership of the geometry
+      // may be not really well defined, so better not destroy it, but just
+      // the feature.
+      OGR_F_Destroy( theOGRFeature );
       continue;
     }
 
 
     if ( OGR_L_SetFeature( ogrLayer, theOGRFeature ) != OGRERR_NONE )
     {
       pushError( tr( "OGR error setting feature %1: %2" ).arg( it.key() ).arg( CPLGetLastErrorMsg() ) );
-      OGR_G_DestroyGeometry( theNewGeometry );
-      theNewGeometry = nullptr;
+      OGR_F_Destroy( theOGRFeature );
       continue;
     }
     mShapefileMayBeCorrupted = true;

tests/src/python/test_provider_shapefile.py

@@ -244,5 +244,23 @@ def testreloadData(self):
         # And now check that fields are up-to-date
         self.assertEquals(len(vl1.fields()), len(vl2.fields()))
 
+    def testDeleteGeometry(self):
+        ''' Test changeGeometryValues() with a null geometry '''
+
+        tmpdir = tempfile.mkdtemp()
+        self.dirs_to_cleanup.append(tmpdir)
+        srcpath = os.path.join(TEST_DATA_DIR, 'provider')
+        for file in glob.glob(os.path.join(srcpath, 'shapefile.*')):
+            shutil.copy(os.path.join(srcpath, file), tmpdir)
+        datasource = os.path.join(tmpdir, 'shapefile.shp')
+
+        vl = QgsVectorLayer(u'{}|layerid=0'.format(datasource), u'test', u'ogr')
+        self.assertTrue(vl.dataProvider().changeGeometryValues({0: QgsGeometry()}))
+        vl = None
+
+        vl = QgsVectorLayer(u'{}|layerid=0'.format(datasource), u'test', u'ogr')
+        fet = next(vl.getFeatures())
+        self.assertIsNone(fet.geometry())
+
 if __name__ == '__main__':
     unittest.main()