If a function can return a null pointer. That pointer

From: Erik Hovland <erik@hovland.org>

should be checked for validity.
---

 mythtv/programs/mythtranscode/main.cpp |   16 +++++++++++-----
 1 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/mythtv/programs/mythtranscode/main.cpp b/mythtv/programs/mythtranscode/main.cpp
index 97a381e..0b9545b 100644
--- a/mythtv/programs/mythtranscode/main.cpp
+++ b/mythtv/programs/mythtranscode/main.cpp
@@ -683,11 +683,17 @@ void UpdatePositionMap(QMap <long long, long long> &posMap, QString mapfile,
     else if (!mapfile.isEmpty())
     {
         FILE *mapfh = fopen(mapfile, "w");
-        QMap<long long, long long>::Iterator i;
-        fprintf (mapfh, "Type: %d\n", MARK_GOP_BYFRAME);
-        for (i = posMap.begin(); i != posMap.end(); ++i)
-            fprintf(mapfh, "%lld %lld\n", i.key(), i.data());
-        fclose(mapfh);
+        if (mapfh)
+        {
+            QMap<long long, long long>::Iterator i;
+            fprintf (mapfh, "Type: %d\n", MARK_GOP_BYFRAME);
+            for (i = posMap.begin(); i != posMap.end(); ++i)
+                fprintf(mapfh, "%lld %lld\n", i.key(), i.data());
+            fclose(mapfh);
+        }
+        else
+            VERBOSE(VB_GENERAL,
+                    QString("Could not open map file %1").arg(mapfile));
     }
 }