const (
	sysTCP_KEEPIDLE  = 0x1D
	sysTCP_KEEPINTVL = 0x1E
	sysTCP_KEEPCNT   = 0x1F
)

func setKeepAliveIdle(fd *netFD, d time.Duration) error {
	if !unix.SupportTCPKeepAliveIdleIntvlCNT() {
		return setKeepAliveIdleAndIntervalAndCount(fd, d, -1, -1)
	}

	if d == 0 {
		d = defaultTCPKeepAliveIdle
	} else if d < 0 {
		return nil
	}

	}

	var (
		tcpKeepAliveIdle         int
		tcpKeepAliveInterval     int
		tcpKeepAliveIdleTime     time.Duration
		tcpKeepAliveIntervalTime time.Duration
		tcpKeepAliveCount        int
	)
	if unix.SupportTCPKeepAliveIdleIntvlCNT() {
		tcpKeepAliveIdle, err = syscall.GetsockoptInt(fd, syscall.IPPROTO_TCP, syscall_TCP_KEEPIDLE)
		if err != nil {
			return
		}
		tcpKeepAliveIdleTime = time.Duration(tcpKeepAliveIdle) * time.Second

		if err == syscall.EINTR {
			continue
		}
		return err != syscall.ENOSYS
	}
})

// SupportTCPKeepAliveIdleIntvlCNT determines whether the TCP_KEEPIDLE, TCP_KEEPINTVL and TCP_KEEPCNT
// are available by checking the kernel version for Solaris 11.4.
var SupportTCPKeepAliveIdleIntvlCNT = sync.OnceValue(func() bool {
	major, minor := KernelVersion()
	return major > 11 || (major == 11 && minor >= 4)

	if !c.ok() {
		return syscall.EINVAL
	}

	if err := setKeepAlive(c.fd, config.Enable); err != nil {
		return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
	}
	if unix.SupportTCPKeepAliveIdleIntvlCNT() {
		if err := setKeepAliveIdle(c.fd, config.Idle); err != nil {
			return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
		}