Addrinfo#unix_path

static VALUE
addrinfo_unix_path(VALUE self)
{
    rb_addrinfo_t *rai = get_addrinfo(self);
    int family = ai_get_afamily(rai);
    struct sockaddr_un *addr;
    long n;

    if (family != AF_UNIX)
        rb_raise(rb_eSocket, "need AF_UNIX address");

    addr = &rai->addr.un;

    n = rai_unixsocket_len(rai);
    if (n < 0)
        rb_raise(rb_eSocket, "too short AF_UNIX address: %"PRIuSIZE" bytes given for minimum %"PRIuSIZE" bytes.",
                 (size_t)rai->sockaddr_len, offsetof(struct sockaddr_un, sun_path));
    if ((long)sizeof(addr->sun_path) < n)
        rb_raise(rb_eSocket,
            "too long AF_UNIX path (%"PRIuSIZE" bytes given but %"PRIuSIZE" bytes max)",
            (size_t)n, sizeof(addr->sun_path));
    return rb_str_new(addr->sun_path, n);
}