From: Paul Ramsey <pramsey@cleverelephant.ca>
Date: Fri, 26 Jan 2018 14:55:44 +0000 (+0000)
Subject: lwpoly_construct_circle: Avoid division by zero (Raúl Marín Rodríguez)
X-Git-Tag: 2.4.4~25
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=79e92a391693942f06a399013fae54ce6d08f6d1;p=postgis

lwpoly_construct_circle: Avoid division by zero (Raúl Marín Rodríguez)
References #4003


git-svn-id: http://svn.osgeo.org/postgis/branches/2.4@16362 b70326c6-7e19-0410-871a-916f4a2858ee
---

diff --git a/NEWS b/NEWS
index ada83ba4e..53f40b336 100644
--- a/NEWS
+++ b/NEWS
@@ -4,6 +4,7 @@ PostGIS 2.4.4dev
  * Bug fixes *
   - #3978, Fix KNN when upgrading from 2.1 or older (Sandro Santilli)
   - #4004, Avoid memory exhaustion when building a btree index (Edmund Horner)
+  - #4003, lwpoly_construct_circle: Avoid division by zero (Raúl Marín Rodríguez)
 
 PostGIS 2.3.6
 2018/01/17
diff --git a/liblwgeom/lwpoly.c b/liblwgeom/lwpoly.c
index bb8097c48..81135621e 100644
--- a/liblwgeom/lwpoly.c
+++ b/liblwgeom/lwpoly.c
@@ -120,13 +120,13 @@ LWPOLY*
 lwpoly_construct_circle(int srid, double x, double y, double radius, uint32_t segments_per_quarter, char exterior)
 {
 	const int segments = 4*segments_per_quarter;
-	const double theta = 2*M_PI / segments;
+	double theta;
 	LWPOLY *lwpoly;
 	POINTARRAY *pa;
 	POINT4D pt;
 	uint32_t i;
 
-	if (segments_per_quarter < 1)
+	if (segments_per_quarter == 0)
 	{
 		lwerror("Need at least one segment per quarter-circle.");
 		return NULL;
@@ -138,6 +138,8 @@ lwpoly_construct_circle(int srid, double x, double y, double radius, uint32_t se
 		return NULL;
 	}
 
+	theta = 2*M_PI / segments;
+
 	lwpoly = lwpoly_construct_empty(srid, LW_FALSE, LW_FALSE);
 	pa = ptarray_construct_empty(LW_FALSE, LW_FALSE, segments + 1);