From db964d126caa0da0f8c62890404e73820fde73ab Mon Sep 17 00:00:00 2001
From: Mark Pizzolato <mark@infocomm.com>
Date: Thu, 17 Oct 2013 07:04:04 -0700
Subject: [PATCH] SCP/TMXR: Fix crashing bug when a multiplexer line has
 logging enabled before a mux attach,

---
 sim_tmxr.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/sim_tmxr.c b/sim_tmxr.c
index d0c6b717..e7474e73 100644
--- a/sim_tmxr.c
+++ b/sim_tmxr.c
@@ -3437,7 +3437,8 @@ if (lp->txlog == NULL) {                                /* error? */
     free (lp->txlogname);                               /* free buffer */
     return SCPE_OPENERR;
     }
-lp->mp->uptr->filename = tmxr_mux_attach_string (lp->mp->uptr->filename, lp->mp);
+if (mp->uptr)                                           /* attached?, then update attach string */
+    lp->mp->uptr->filename = tmxr_mux_attach_string (lp->mp->uptr->filename, lp->mp);
 return SCPE_OK;
 }