From 55f3776fc1adab5ca0ccd4671ea839a691babe88 Mon Sep 17 00:00:00 2001
From: Holger Vogt <holger.vogt@uni-due.de>
Date: Mon, 13 Apr 2020 10:26:05 +0200
Subject: [PATCH] add a warning if file with modified parameters has not been
 found. Then ignore the altermod command.

---
 src/frontend/device.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/frontend/device.c b/src/frontend/device.c
index 77c5e0a1c..603ecf69a 100644
--- a/src/frontend/device.c
+++ b/src/frontend/device.c
@@ -1403,7 +1403,15 @@ com_alter_mod(wordlist *wl)
         }
         filename = copy(eqword);
     }
+
     modfile = inp_pathopen(filename, readmode);
+
+    if (modfile == NULL) {
+        fprintf(cp_err, "Warning: Could not open file %s, altermod ignored\n", filename);
+        tfree(input);
+        tfree(filename);
+        return;
+    }
     {
         char *dir_name = ngdirname(filename);
         modeldeck = inp_readall(modfile, dir_name, 0, 0, NULL);