size_t orig_len = fname->len;
size_t tmp = fname->len;
static void http_app_err_file(struct Con *con, Httpd_req_data *req,                              Vstr_base *fname, size_t *vhost_prefix_len){  Vstr_base *dir = NULL;  ASSERT(con && req);  ASSERT(vhost_prefix_len && !*vhost_prefix_len);  dir = req->policy->req_err_dir;  ASSERT((dir->len   >= 1) && vstr_cmp_cstr_eq(dir,          1, 1, "/"));  ASSERT((dir->len   >= 1) && vstr_cmp_cstr_eq(dir,   dir->len, 1, "/"));  HTTPD_APP_REF_ALLVSTR(fname, dir);    vstr_add_fmt(fname, fname->len, "%u", req->error_code);    if (req->policy->use_vhosts_name)  {    Vstr_base *data = con->evnt->io_r;    Vstr_sect_node *h_h = req->http_hdrs->hdr_host;    size_t orig_len = fname->len;        if (!h_h->len)      httpd_sc_add_default_hostname(con, req, fname, 0);    else if (vstr_add_vstr(fname, 0, data, /* add as buf's, for lowercase op */                           h_h->pos, h_h->len, VSTR_TYPE_ADD_DEF))      vstr_conv_lowercase(fname, 1, h_h->len);    vstr_add_cstr_ptr(fname, 0, "/");    *vhost_prefix_len = (fname->len - orig_len);  }}