dont crash if the variable we do substitution on is not set

diff --git a/shell/hush.c b/shell/hush.c
index d6f765d6b332a6c21801e1e0cd3958336c13adf0..ac2410c485fedcb063d0d168ce6ef5689c4578f0 100644 (file)
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -2025,18 +2025,20 @@ static int expand_vars_to_list(o_string *output, int n, char *arg, char or_mask)
                                debug_printf_expand("%s\n", val);
                        } else if (exp_off) {
                                if (exp_op == '%' || exp_op == '#') {
-                                       /* we need to do a pattern match */
-                                       bool zero;
-                                       char *loc;
-                                       scan_t scan = pick_scan(exp_op, *exp_word, &zero);
-                                       if (exp_op == *exp_word)        /* ## or %% */
-                                               ++exp_word;
-                                       val = dyn_val = xstrdup(val);
-                                       loc = scan(dyn_val, exp_word, zero);
-                                       if (zero)
-                                               val = loc;
-                                       else
-                                               *loc = '\0';
+                                       if (val) {
+                                               /* we need to do a pattern match */
+                                               bool zero;
+                                               char *loc;
+                                               scan_t scan = pick_scan(exp_op, *exp_word, &zero);
+                                               if (exp_op == *exp_word)        /* ## or %% */
+                                                       ++exp_word;
+                                               val = dyn_val = xstrdup(val);
+                                               loc = scan(dyn_val, exp_word, zero);
+                                               if (zero)
+                                                       val = loc;
+                                               else
+                                                       *loc = '\0';
+                                       }
                                } else {
                                        /* we need to do an expansion */
                                        int exp_test = (!val || (exp_null && !val[0]));