void reject_cntrl_chars(const char *fname) {
	assert(fname);

	if (has_cntrl_chars(fname)) {
		char *fname_print = replace_cntrl_chars(fname, '?');

		fprintf(stderr, "Error: \"%s\" is an invalid filename: no control characters are allowed\n", fname_print);
		exit(1);
	}
}
void reject_cntrl_chars(const char *fname) {
	assert(fname);

	if (has_cntrl_chars(fname)) {
		char *fname_print = replace_cntrl_chars(fname, '?');

		fprintf(stderr, "Error: \"%s\" is an invalid filename: no control characters are allowed\n", fname_print);
		exit(1);
	}
}