append_filter
static int append_filter(struct filter **filters, int *cnt, const char *str);
err = append_filter(&env.deny_filters, &env.deny_filter_cnt, arg + 1);
err = append_filter(&env.allow_filters, &env.allow_filter_cnt, arg);
err = append_filter(&env.deny_filters, &env.deny_filter_cnt, buf + 1);
err = append_filter(&env.allow_filters, &env.allow_filter_cnt, buf);