Small correction for name->FQDN converting code.

refs #1423

src/knot/conf/cf-parse.y

@@ -477,20 +477,28 @@ zone_start: TEXT {
    this_zone->notify_retries = 0; // Default policy applies
    this_zone->ixfr_fslimit = -1; // Default policy applies
    this_zone->dbsync_timeout = -1; // Default policy applies
-   this_zone->name = $1.t;
 
    // Append mising dot to ensure FQDN
-   size_t nlen = strlen(this_zone->name);
-   if (this_zone->name[nlen - 1] != '.') {
-     this_zone->name = realloc(this_zone->name, nlen + 1 + 1);
-     strcat(this_zone->name, ".");
+   char *name = $1.t;
+   size_t nlen = strlen(name);
+   if (name[nlen - 1] != '.') {
+      this_zone->name = malloc(nlen + 2);
+      if (this_zone->name != NULL) {
+	memcpy(this_zone->name, name, nlen);
+	this_zone->name[nlen] = '.';
+	this_zone->name[nlen + 1] = '\0';
+     }
+     free(name);
+   } else {
+      this_zone->name = name; /* Already FQDN */
    }
 
    /* Check domain name. */
-   knot_dname_t *dn = knot_dname_new_from_str(this_zone->name,
-                                                  nlen + 1,
-                                                  0);
-   if (dn == 0) {
+   knot_dname_t *dn = NULL;
+   if (this_zone->name != NULL) {
+      dn = knot_dname_new_from_str(this_zone->name, nlen + 1, 0);
+   }
+   if (dn == NULL) {
      free(this_zone->name);
      free(this_zone);
      cf_error(scanner, "invalid zone origin");