From 8867a9327c9612692bf0686a5052a3111c6caca0 Mon Sep 17 00:00:00 2001
From: Carles Fernandez <carles.fernandez@gmail.com>
Date: Tue, 13 Aug 2019 13:52:43 +0200
Subject: [PATCH] Avoid null pointer argument in call to string comparison
 function

---
 src/algorithms/libs/rtklib/rtklib_solution.cc | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/src/algorithms/libs/rtklib/rtklib_solution.cc b/src/algorithms/libs/rtklib/rtklib_solution.cc
index f27f1d6d1..13a48a1bf 100644
--- a/src/algorithms/libs/rtklib/rtklib_solution.cc
+++ b/src/algorithms/libs/rtklib/rtklib_solution.cc
@@ -388,13 +388,16 @@ int decode_nmea(char *buff, sol_t *sol)
                 }
         }
     /* decode nmea sentence */
-    if (!strcmp(val[0], "$GPRMC"))
+    if (val[0])
         {
-            return decode_nmearmc(val + 1, n - 1, sol);
-        }
-    if (!strcmp(val[0], "$GPGGA"))
-        {
-            return decode_nmeagga(val + 1, n - 1, sol);
+            if (!strcmp(val[0], "$GPRMC"))
+                {
+                    return decode_nmearmc(val + 1, n - 1, sol);
+                }
+            if (!strcmp(val[0], "$GPGGA"))
+                {
+                    return decode_nmeagga(val + 1, n - 1, sol);
+                }
         }
     return 0;
 }