From 4ef0b834d73931a65ad7b058159f09f246bea19e Mon Sep 17 00:00:00 2001
From: Sandro Santilli <strk@keybit.net>
Date: Fri, 4 May 2012 08:06:16 +0000
Subject: [PATCH] Protect ST_Segmentize from max_length=0  (#1799)

git-svn-id: http://svn.osgeo.org/postgis/trunk@9712 b70326c6-7e19-0410-871a-916f4a2858ee
---
 postgis/lwgeom_functions_basic.c | 7 +++++++
 regress/tickets.sql              | 3 +++
 regress/tickets_expected         | 1 +
 3 files changed, 11 insertions(+)

diff --git a/postgis/lwgeom_functions_basic.c b/postgis/lwgeom_functions_basic.c
index 5a3398f17..2e31c57da 100644
--- a/postgis/lwgeom_functions_basic.c
+++ b/postgis/lwgeom_functions_basic.c
@@ -1824,6 +1824,13 @@ Datum LWGEOM_segmentize2d(PG_FUNCTION_ARGS)
 		PG_RETURN_POINTER(ingeom);
 	}
 
+	if ( dist <= 0 ) {
+		/* Protect from knowingly infinite loops, see #1799 */
+		/* Note that we'll end out of memory anyway for other small distances */
+		elog(ERROR, "ST_Segmentize: invalid max_distance %g (must be >= 0)", dist);
+		PG_RETURN_NULL();
+	}
+
 	inlwgeom = lwgeom_from_gserialized(ingeom);
 	outlwgeom = lwgeom_segmentize2d(inlwgeom, dist);
 
diff --git a/regress/tickets.sql b/regress/tickets.sql
index fa07a57e0..c6f0dfab0 100644
--- a/regress/tickets.sql
+++ b/regress/tickets.sql
@@ -677,5 +677,8 @@ with inp as ( SELECT
 ) SELECT '#1791', round(ST_Azimuth(a,b)*10)/10 from inp;
 
 
+-- #1799 --
+SELECT '#1799', ST_Segmentize('LINESTRING(0 0, 10 0)'::geometry, 0);
+
 -- Clean up
 DELETE FROM spatial_ref_sys;
diff --git a/regress/tickets_expected b/regress/tickets_expected
index 50ee58d60..31d24b6f3 100644
--- a/regress/tickets_expected
+++ b/regress/tickets_expected
@@ -219,3 +219,4 @@ NOTICE:  SRID value -1 converted to the officially unknown SRID value 0
 #1755|01010000A0E6100000000000000040554000000000008041400000000000000000
 #1776|POLYGON((0 0,10 0,10 10,0 0))|POLYGON((0 0,10 0,10 10,0 0))
 #1791|4.7
+ERROR:  ST_Segmentize: invalid max_distance 0 (must be >= 0)
-- 
2.40.0