ST_Subdivide: don't crash if on some iteration you need to subdivide Empty

Closes #4217
Closes postgis#321


git-svn-id: http://svn.osgeo.org/postgis/trunk@16955 b70326c6-7e19-0410-871a-916f4a2858ee

Author: Komzpa

liblwgeom/lwgeom.c

@@ -2342,43 +2342,30 @@ lwgeom_subdivide_recursive(const LWGEOM *geom,
 
 	++depth;
 
-	LWCOLLECTION *col1 =
-	    lwcollection_construct_empty(COLLECTIONTYPE, geom->srid, lwgeom_has_z(geom), lwgeom_has_m(geom));
-	LWCOLLECTION *col2 =
-	    lwcollection_construct_empty(COLLECTIONTYPE, geom->srid, lwgeom_has_z(geom), lwgeom_has_m(geom));
-	//#pragma omp parallel sections
 	{
-		//#pragma omp section
+		LWGEOM *subbox = (LWGEOM *)lwpoly_construct_envelope(
+		    geom->srid, subbox1.xmin, subbox1.ymin, subbox1.xmax, subbox1.ymax);
+		LWGEOM *clipped = lwgeom_intersection(geom, subbox);
+		lwgeom_simplify_in_place(clipped, 0.0, LW_TRUE);
+		lwgeom_free(subbox);
+		if (clipped && !lwgeom_is_empty(clipped))
 		{
-			LWGEOM *subbox = (LWGEOM *)lwpoly_construct_envelope(
-			    geom->srid, subbox1.xmin, subbox1.ymin, subbox1.xmax, subbox1.ymax);
-			LWGEOM *clipped = lwgeom_intersection(geom, subbox);
-			lwgeom_simplify_in_place(clipped, 0.0, LW_TRUE);
-			lwgeom_free(subbox);
-			if (clipped)
-			{
-				lwgeom_subdivide_recursive(clipped, dimension, maxvertices, depth, col1);
-				lwgeom_free(clipped);
-			}
+			lwgeom_subdivide_recursive(clipped, dimension, maxvertices, depth, col);
+			lwgeom_free(clipped);
 		}
-		//#pragma omp section
+	}
+	{
+		LWGEOM *subbox = (LWGEOM *)lwpoly_construct_envelope(
+		    geom->srid, subbox2.xmin, subbox2.ymin, subbox2.xmax, subbox2.ymax);
+		LWGEOM *clipped = lwgeom_intersection(geom, subbox);
+		lwgeom_simplify_in_place(clipped, 0.0, LW_TRUE);
+		lwgeom_free(subbox);
+		if (clipped && !lwgeom_is_empty(clipped))
 		{
-			LWGEOM *subbox = (LWGEOM *)lwpoly_construct_envelope(
-			    geom->srid, subbox2.xmin, subbox2.ymin, subbox2.xmax, subbox2.ymax);
-			LWGEOM *clipped = lwgeom_intersection(geom, subbox);
-			lwgeom_simplify_in_place(clipped, 0.0, LW_TRUE);
-			lwgeom_free(subbox);
-			if (clipped)
-			{
-				lwgeom_subdivide_recursive(clipped, dimension, maxvertices, depth, col2);
-				lwgeom_free(clipped);
-			}
+			lwgeom_subdivide_recursive(clipped, dimension, maxvertices, depth, col);
+			lwgeom_free(clipped);
 		}
 	}
-	col = lwcollection_concat_in_place(col, col1);
-	lwcollection_release(col1);
-	col = lwcollection_concat_in_place(col, col2);
-	lwcollection_release(col2);
 }
 
 LWCOLLECTION *

regress/core/subdivide.sql

@@ -60,3 +60,6 @@ drop table big_polygon;
 drop table big_polygon_sliced;
 
 select '#4211', (select sum(ST_Area(geom))::numeric(12,11) from ST_Subdivide('MULTIPOLYGON(((-88.2059 41.7325,-88.2060 41.7244,-88.1959 41.7241,-88.1959 41.7326,-88.2059 41.7325),(-88.1997 41.7289,-88.1996 41.7285,-88.1990 41.7285,-88.1990 41.7289,-88.1997 41.7289)))') geom );
+
+select '#4217', (select sum(ST_Area(geom))::numeric(12,11) from ST_Subdivide('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10) geom);
+

regress/core/subdivide_expected

@@ -6,3 +6,4 @@ ERROR:  lwgeom_subdivide: cannot subdivide to fewer than 5 vertices per output
 #3744|1600000000000000
 4|29321996468.6|29321996468.6|1857|256
 #4211|0.00008316000
+#4217|0.00002463668