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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 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(f, t, p int) (int, error) {
s, err := syscall.Socket(f, t|syscall.SOCK_NONBLOCK|syscall.SOCK_CLOEXEC, p)
// The SOCK_NONBLOCK and SOCK_CLOEXEC flags were introduced in
// Linux 2.6.27. If we get an EINVAL error, fall back to
// using socket without them.
if err == nil || err != syscall.EINVAL {
return s, err
}
// See ../syscall/exec_unix.go for description of ForkLock.
syscall.ForkLock.RLock()
s, err = syscall.Socket(f, t, p)
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(fd int) (int, syscall.Sockaddr, error) {
nfd, sa, err := syscall.Accept4(fd, syscall.SOCK_NONBLOCK|syscall.SOCK_CLOEXEC)
// The accept4 system call was introduced in Linux 2.6.28. If
// we get an ENOSYS or EINVAL error, fall back to using accept.
if err == nil || (err != syscall.ENOSYS && err != syscall.EINVAL) {
return nfd, sa, err
}
// 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.
nfd, sa, err = syscall.Accept(fd)
if err == nil {
syscall.CloseOnExec(nfd)
}
if err != nil {
return -1, nil, err
}
if err = syscall.SetNonblock(nfd, true); err != nil {
syscall.Close(nfd)
return -1, nil, err
}
return nfd, sa, nil
}
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