Allow tailing '\0'

Remove potentially user induced buffer overflow by replacing
sprintf by snprintf.

src/frontend/inp.c

@@ -475,7 +475,7 @@ inp_spsource(FILE *fp, bool comfile, char *filename, bool intfile)
 {
     struct card *deck = NULL, *dd, *ld, *prev_param = NULL, *prev_card = NULL;
     struct card *realdeck = NULL, *options = NULL, *curr_meas = NULL;
-    char *tt = NULL, name[BSIZE_SP], *s, *t, *temperature = NULL;
+    char *tt = NULL, name[BSIZE_SP + 1], *s, *t, *temperature = NULL;
     double testemp = 0.0;
     bool commands = FALSE;
     wordlist *wl = NULL, *end = NULL, *wl_first = NULL;
@@ -1621,7 +1621,9 @@ doedit(char *filename)
                 editor = "/usr/bin/vi";
         }
     }
-    sprintf(buf, "%s %s", editor, filename);
+    int len = snprintf(buf, BSIZE_SP - 1, "%s %s", editor, filename);
+    if (len > BSIZE_SP - 1)
+        fprintf(stderr, "Error: the filename is probably tuncated\n");
     return (system(buf) ? FALSE : TRUE);
 }