p9p_ver2str
if (strncmp(str, p9p_ver2str(p9p->protover), P9PROTO_VERSTR_MAXLEN) != 0) {
errx(1, "server doesn't support %s", p9p_ver2str(p9p->protover));
p9pbuf_put_str(pb, p9p_ver2str(p9p->protover));