rem: const char *p;
add: size_t validlen = strspn (file, ("/" "ABCDEFGHIJKLMNOPQRSTUVWXYZ" "abcdefghijklmnopqrstuvwxyz" "0123456789._-")); char const *invalid = file + validlen;
context: portable_chars_only (const char *path){  const char *p;  for (p = path; *p; ++p)    if (portable_chars[(unsigned char) *p] == 0)      {	error (0, 0, _("path `%s' contains nonportable character `%c'"),	       path, *p);	return 0;      }  return 1;}