// Copyright 2020 lesismal. All rights reserved.
// Use of this source code is governed by an MIT-style
// license that can be found in the LICENSE file.

//go:build linux || darwin || netbsd || freebsd || openbsd || dragonfly
// +build linux darwin netbsd freebsd openbsd dragonfly

package nbio

import (
	"errors"
	"net"
	"syscall"
)

func dupStdConn(conn net.Conn) (*Conn, error) {
	sc, ok := conn.(interface {
		SyscallConn() (syscall.RawConn, error)
	})
	if !ok {
		return nil, errors.New("RawConn Unsupported")
	}
	rc, err := sc.SyscallConn()
	if err != nil {
		return nil, errors.New("RawConn Unsupported")
	}

	var newFd int
	errCtrl := rc.Control(func(fd uintptr) {
		newFd, err = syscall.Dup(int(fd))
	})

	if errCtrl != nil {
		return nil, errCtrl
	}

	if err != nil {
		return nil, err
	}

	conn.Close()

	// err = syscall.SetNonblock(newFd, true)
	// if err != nil {
	// 	syscall.Close(newFd)
	// 	return nil, err
	// }

	return &Conn{
		fd:    newFd,
		lAddr: conn.LocalAddr(),
		rAddr: conn.RemoteAddr(),
	}, nil
}