From: oliskoli <oliskoli@f51c46e8-681c-474f-0cfe-069cfd0219fb>
Date: Sat, 29 Apr 2006 16:41:30 +0000 (+0000)
Subject: Check valid range for n before calling acos(n). Set errno always to zero.
X-Git-Tag: archive/raspbian/1.10.0+ds-2+rpi1~1^2~12^2~11^2~2908
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=644c09b5ef6774831841c607a99199cfe0e0becf;p=gpsbabel.git

Check valid range for n before calling acos(n). Set errno always to zero.
---

diff --git a/gpsbabel/grtcirc.c b/gpsbabel/grtcirc.c
index d2cd3a7fc..752e3f229 100644
--- a/gpsbabel/grtcirc.c
+++ b/gpsbabel/grtcirc.c
@@ -59,10 +59,18 @@ double radtometers( double rads ) {
 
 double gcdist( double lat1, double lon1, double lat2, double lon2 ) {
   double res;
-  res = acos(sin(lat1)*sin(lat2)+cos(lat1)*cos(lat2)*cos(lon1-lon2));
-  if (errno == EDOM) { /* Math argument out of domain of function */
-    errno = 0;
-    return 0;
+
+  errno = 0;
+
+  res = sin(lat1)*sin(lat2)+cos(lat1)*cos(lat2)*cos(lon1-lon2);
+  if (res > 1.0) res = 1.0;
+  else if (res < -1.0) res = -1.0;
+
+  res = acos(res);
+
+  if ((isnan(res)) || (errno == EDOM)) { /* this should never happen: */
+    errno = 0;                           /* Math argument out of domain of function, */
+    return 0;                            /* or value returned is not a number */
   }
   return res;
 }