func WriteFile(c *net.UnixConn, file *os.File, timeout time.Duration) error {
if timeout > 0 {
deadline := time.Now().Add(timeout)
if err := c.SetWriteDeadline(deadline); err != nil {
return err
}
}
oob := syscall.UnixRights(int(file.Fd()))
_, _, err := c.WriteMsgUnix(nil, oob, nil)
return err
}