From bf3a4e6b0baa411beda7056db5ad01fa330fb0d4 Mon Sep 17 00:00:00 2001
From: Sandro Santilli <strk@keybit.net>
Date: Fri, 3 Oct 2014 09:34:43 +0000
Subject: [PATCH] ST_ClipByBox2D: do not use gbox_overlaps with BOX2DF objects

Fixes use of uninitialized memory (#2954)

git-svn-id: http://svn.osgeo.org/postgis/trunk@13034 b70326c6-7e19-0410-871a-916f4a2858ee
---
 postgis/lwgeom_geos.c        | 9 ++++++---
 regress/clipbybox2d.sql      | 2 ++
 regress/clipbybox2d_expected | 1 +
 3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/postgis/lwgeom_geos.c b/postgis/lwgeom_geos.c
index ce3a5092f..3a81d9862 100644
--- a/postgis/lwgeom_geos.c
+++ b/postgis/lwgeom_geos.c
@@ -1665,10 +1665,13 @@ Datum ST_ClipByBox2d(PG_FUNCTION_ARGS)
 		PG_RETURN_POINTER(geom1);
 	}
 
+	/* WARNING: this is really a BOX2DF, use only xmin and ymin fields */
 	bbox2 = (GBOX *)PG_GETARG_POINTER(1);
 
-	/* If bbox1 outside of bbox, return empty */
-	if ( LW_FALSE == gbox_overlaps_2d(bbox1, bbox2) ) {
+	/* If bbox1 outside of bbox2, return empty */
+	if ( bbox1->xmin > bbox2->xmax || bbox1->xmax < bbox2->xmin ||
+			 bbox1->ymin > bbox2->ymax || bbox1->ymax < bbox2->ymin )
+	{
 		lwresult = lwgeom_construct_empty(lwgeom1->type, lwgeom1->srid, 0, 0);
 		lwgeom_free(lwgeom1);
 		PG_FREE_IF_COPY(geom1, 0);
@@ -1677,7 +1680,7 @@ Datum ST_ClipByBox2d(PG_FUNCTION_ARGS)
 		PG_RETURN_POINTER(result);
 	}
 
-	/* if bbox1 is covered by bbox, return lwgeom1 */
+	/* if bbox1 is covered by bbox2, return lwgeom1 */
 	if ( bbox1->xmax <= bbox2->xmax && bbox1->xmin >= bbox2->xmin &&
 			 bbox1->ymax <= bbox2->ymax && bbox1->ymin >= bbox2->ymin )
 	{
diff --git a/regress/clipbybox2d.sql b/regress/clipbybox2d.sql
index 1c9a4a6f7..b82207d7d 100644
--- a/regress/clipbybox2d.sql
+++ b/regress/clipbybox2d.sql
@@ -21,3 +21,5 @@ CREATE TEMPORARY TABLE t AS SELECT
 'SRID=3857;POLYGON((41 20,41 0,21 0,1 20,1 40,21 40,41 20))'
 ::geometry g;
 SELECT ST_AsEWKT(ST_ClipByBox2d(g, ST_MakeEnvelope(-20,-20,-10,-10))) FROM t;
+-- See http://trac.osgeo.org/postgis/ticket/2954
+SELECT ST_AsEWKT(ST_ClipByBox2D('SRID=4326;POINT(0 0)','BOX3D(-1 -1,1 1)'::box3d::box2d));
diff --git a/regress/clipbybox2d_expected b/regress/clipbybox2d_expected
index 8243e44fa..e58bf780c 100644
--- a/regress/clipbybox2d_expected
+++ b/regress/clipbybox2d_expected
@@ -6,3 +6,4 @@ POLYGON((2 2,8 2,2 8,8 8,2 2))
 POLYGON((2.5 2,5 4,5 5,5 4,7.5 2,2.5 2))
 POLYGON((2 2,2 5,5 5,5 2,2 2))
 SRID=3857;POLYGON EMPTY
+SRID=4326;POINT(0 0)
-- 
2.40.0