From cc4e4d9bad2805750eed69a4f41f1ae0a1ea7e84 Mon Sep 17 00:00:00 2001
From: dwarning <dwarning>
Date: Wed, 31 Oct 2018 08:55:30 +0100
Subject: [PATCH] verify pointer before utilization

---
 src/frontend/inp.c          | 6 ++++--
 src/frontend/plotting/x11.c | 3 ++-
 src/frontend/runcoms.c      | 3 ++-
 3 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/src/frontend/inp.c b/src/frontend/inp.c
index 83e83f094..813edea46 100644
--- a/src/frontend/inp.c
+++ b/src/frontend/inp.c
@@ -815,8 +815,10 @@ inp_spsource(FILE *fp, bool comfile, char *filename, bool intfile)
             /* now load deck into ft_curckt -- the current circuit. */
             inp_dodeck(deck, tt, wl_first, FALSE, options, filename);
 
-            ft_curckt->devtlist = devtlist;
-            ft_curckt->modtlist = modtlist;
+            if (ft_curckt) {
+                ft_curckt->devtlist = devtlist;
+                ft_curckt->modtlist = modtlist;
+            }
 
             /* inp_dodeck did take ownership */
             tt = NULL;
diff --git a/src/frontend/plotting/x11.c b/src/frontend/plotting/x11.c
index 5f6720cb7..65687b54d 100644
--- a/src/frontend/plotting/x11.c
+++ b/src/frontend/plotting/x11.c
@@ -1058,7 +1058,8 @@ X11_Input(REQUEST *request, RESPONSE *response)
 
     default:
         internalerror("unrecognized input type");
-        response->option = error_option;
+        if (response)
+            response->option = error_option;
         return 1;
         break;
     }
diff --git a/src/frontend/runcoms.c b/src/frontend/runcoms.c
index 1e7bdc67d..17c28e032 100644
--- a/src/frontend/runcoms.c
+++ b/src/frontend/runcoms.c
@@ -342,7 +342,8 @@ dosim(
     if (rawfileFp) {
         if (ftell(rawfileFp) == 0) {
             (void) fclose(rawfileFp);
-            (void) unlink(wl->wl_word);
+            if (wl)
+                (void) unlink(wl->wl_word);
         } else {
             (void) fclose(rawfileFp);
         }