// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file implements sysSocket and accept for platforms that
// provide a fast path for setting SetNonblock and CloseOnExec.

// +build dragonfly freebsd illumos linux netbsd openbsd

package poll


// Wrapper around the accept system call that marks the returned file
// descriptor as nonblocking and close-on-exec.
func accept( int) (int, syscall.Sockaddr, string, error) {
	, ,  := Accept4Func(, syscall.SOCK_NONBLOCK|syscall.SOCK_CLOEXEC)
	// On Linux the accept4 system call was introduced in 2.6.28
	// kernel and on FreeBSD it was introduced in 10 kernel. If we
	// get an ENOSYS error on both Linux and FreeBSD, or EINVAL
	// error on Linux, fall back to using accept.
	switch  {
	case nil:
		return , , "", nil
	default: // errors other than the ones listed
		return -1, , "accept4", 
	case syscall.ENOSYS: // syscall missing
	case syscall.EINVAL: // some Linux use this instead of ENOSYS
	case syscall.EACCES: // some Linux use this instead of ENOSYS
	case syscall.EFAULT: // some Linux use this instead of ENOSYS

	// See ../syscall/exec_unix.go for description of ForkLock.
	// It is probably okay to hold the lock across syscall.Accept
	// because we have put fd.sysfd into non-blocking mode.
	// However, a call to the File method will put it back into
	// blocking mode. We can't take that risk, so no use of ForkLock here.
	, ,  = AcceptFunc()
	if  == nil {
	if  != nil {
		return -1, nil, "accept", 
	if  = syscall.SetNonblock(, true);  != nil {
		return -1, nil, "setnonblock", 
	return , , "", nil