From 2b3f43d47a7766b4ad56c3384d58bd16527a178d Mon Sep 17 00:00:00 2001
From: Laurence de Bruxelles <lfdebrux@gmail.com>
Date: Tue, 24 Apr 2018 15:15:18 +0100
Subject: [PATCH] topic_tools: Check that output topic is valid in demux. Fixes
 #1366 (#1367)

---
 tools/topic_tools/src/demux.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tools/topic_tools/src/demux.cpp b/tools/topic_tools/src/demux.cpp
index 8d414d4cad..6511c25a65 100644
--- a/tools/topic_tools/src/demux.cpp
+++ b/tools/topic_tools/src/demux.cpp
@@ -152,6 +152,9 @@ void in_cb(const boost::shared_ptr<ShapeShifter const>& msg)
     ros::Duration(0.5).sleep();
   }
 
+  // check that we have a valid topic
+  if (!g_selected->pub) return;
+
   // finally: send out the message over the active publisher
   g_selected->pub->publish(msg);
   ROS_DEBUG("... and sent it out again!");
@@ -307,4 +310,3 @@ int main(int argc, char **argv)
   g_pubs.clear();
   return 0;
 }
-