From: Björn Harrtell <bjorn@wololo.org>
Date: Thu, 5 Oct 2017 10:50:16 +0000 (+0000)
Subject: ST_AsMVTGeom clarification on semantics of mvt_geom
X-Git-Tag: 2.5.0alpha~461
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=ac0a690ff26d70b650b7b38254189205542fa446;p=postgis

ST_AsMVTGeom clarification on semantics of mvt_geom

git-svn-id: http://svn.osgeo.org/postgis/trunk@15893 b70326c6-7e19-0410-871a-916f4a2858ee
---

diff --git a/postgis/lwgeom_out_mvt.c b/postgis/lwgeom_out_mvt.c
index d3a0b7300..8dacd2d2d 100644
--- a/postgis/lwgeom_out_mvt.c
+++ b/postgis/lwgeom_out_mvt.c
@@ -60,11 +60,13 @@ Datum ST_AsMVTGeom(PG_FUNCTION_ARGS)
 	extent = PG_ARGISNULL(2) ? 4096 : PG_GETARG_INT32(2);
 	buffer = PG_ARGISNULL(3) ? 256 : PG_GETARG_INT32(3);
 	clip_geom = PG_ARGISNULL(4) ? true : PG_GETARG_BOOL(4);
+	// NOTE: can both return in clone and in place modification so
+	// not known if lwgeom_in can be freed
 	lwgeom_out = mvt_geom(lwgeom_in, bounds, extent, buffer, clip_geom);
-	lwgeom_free(lwgeom_in);
 	if (lwgeom_out == NULL)
 		PG_RETURN_NULL();
 	geom_out = geometry_serialize(lwgeom_out);
+	lwgeom_free(lwgeom_out);
 	PG_FREE_IF_COPY(geom_in, 0);
 	PG_RETURN_POINTER(geom_out);
 #endif
diff --git a/postgis/mvt.c b/postgis/mvt.c
index 018096912..6f69b0e78 100644
--- a/postgis/mvt.c
+++ b/postgis/mvt.c
@@ -657,6 +657,8 @@ static int max_type(LWCOLLECTION *lwcoll)
  *
  * Makes best effort to keep validity. Might collapse geometry into lower
  * dimension.
+ *
+ * NOTE: modifies in place if possible (not currently possible for polygons)
  */
 LWGEOM *mvt_geom(LWGEOM *lwgeom, const GBOX *gbox, uint32_t extent, uint32_t buffer,
 	bool clip_geom)