libgo/go/net/sock_cloexec.go

   1 // Copyright 2013 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 // This file implements sysSocket and accept for platforms that
   6 // provide a fast path for setting SetNonblock and CloseOnExec.
   7
   8 // +build dragonfly freebsd linux netbsd openbsd
   9
  10 package net
  11
  12 import (
  13         "internal/poll"
  14         "os"
  15         "syscall"
  16 )
  17
  18 // Wrapper around the socket system call that marks the returned file
  19 // descriptor as nonblocking and close-on-exec.
  20 func sysSocket(family, sotype, proto int) (int, error) {
  21         s, err := socketFunc(family, sotype|syscall.SOCK_NONBLOCK|syscall.SOCK_CLOEXEC, proto)
  22         // On Linux the SOCK_NONBLOCK and SOCK_CLOEXEC flags were
  23         // introduced in 2.6.27 kernel and on FreeBSD both flags were
  24         // introduced in 10 kernel. If we get an EINVAL error on Linux
  25         // or EPROTONOSUPPORT error on FreeBSD, fall back to using
  26         // socket without them.
  27         switch err {
  28         case nil:
  29                 return s, nil
  30         default:
  31                 return -1, os.NewSyscallError("socket", err)
  32         case syscall.EPROTONOSUPPORT, syscall.EINVAL:
  33         }
  34
  35         // See ../syscall/exec_unix.go for description of ForkLock.
  36         syscall.ForkLock.RLock()
  37         s, err = socketFunc(family, sotype, proto)
  38         if err == nil {
  39                 syscall.CloseOnExec(s)
  40         }
  41         syscall.ForkLock.RUnlock()
  42         if err != nil {
  43                 return -1, os.NewSyscallError("socket", err)
  44         }
  45         if err = syscall.SetNonblock(s, true); err != nil {
  46                 poll.CloseFunc(s)
  47                 return -1, os.NewSyscallError("setnonblock", err)
  48         }
  49         return s, nil
  50 }