socketpair

static VALUE
sock_s_socketpair(VALUE klass, VALUE domain, VALUE type, VALUE protocol)
{
#if defined HAVE_SOCKETPAIR
    int d, t, p, sp[2];
    int ret;

    setup_domain_and_type(domain, &d, type, &t);
    p = NUM2INT(protocol);
    ret = socketpair(d, t, p, sp);
    if (ret < 0 && (errno == EMFILE || errno == ENFILE)) {
        rb_gc();
        ret = socketpair(d, t, p, sp);
    }
    if (ret < 0) {
        rb_sys_fail("socketpair(2)");
    }

    return rb_assoc_new(init_sock(rb_obj_alloc(klass), sp[0]),
                        init_sock(rb_obj_alloc(klass), sp[1]));
#else
    rb_notimplement();
#endif
}