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// 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 freebsd linux
package net
import "syscall"
// Wrapper around the socket system call that marks the returned file
// descriptor as nonblocking and close-on-exec.
func sysSocket(family, sotype, proto int) (int, error) {
s, err := syscall.Socket(family, sotype|syscall.SOCK_NONBLOCK|syscall.SOCK_CLOEXEC, proto)
// On Linux the SOCK_NONBLOCK and SOCK_CLOEXEC flags were
// introduced in 2.6.27 kernel and on FreeBSD both flags were
// introduced in 10 kernel. If we get an EINVAL error on Linux
// or EPROTONOSUPPORT error on FreeBSD, fall back to using
// socket without them.
if err == nil || (err != syscall.EPROTONOSUPPORT && err != syscall.EINVAL) {
return s, err
}
// See ../syscall/exec_unix.go for description of ForkLock.
syscall.ForkLock.RLock()
s, err = syscall.Socket(family, sotype, proto)
if err == nil {
syscall.CloseOnExec(s)
}
syscall.ForkLock.RUnlock()
if err != nil {
return -1, err
}
if err = syscall.SetNonblock(s, true); err != nil {
syscall.Close(s)
return -1, err
}
return s, nil
}
// Wrapper around the accept system call that marks the returned file
// descriptor as nonblocking and close-on-exec.
func accept(s int) (int, syscall.Sockaddr, error) {
ns, sa, err := syscall.Accept4(s, 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 err {
default: // nil and errors other than the ones listed
return ns, sa, err
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.
ns, sa, err = syscall.Accept(s)
if err == nil {
syscall.CloseOnExec(ns)
}
if err != nil {
return -1, nil, err
}
if err = syscall.SetNonblock(ns, true); err != nil {
syscall.Close(ns)
return -1, nil, err
}
return ns, sa, nil
}
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