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 poll 11 12 import "syscall" 13 14 // Wrapper around the accept system call that marks the returned file 15 // descriptor as nonblocking and close-on-exec. 16 func accept(s int) (int, syscall.Sockaddr, string, error) { 17 ns, sa, err := Accept4Func(s, syscall.SOCK_NONBLOCK|syscall.SOCK_CLOEXEC) 18 // On Linux the accept4 system call was introduced in 2.6.28 19 // kernel and on FreeBSD it was introduced in 10 kernel. If we 20 // get an ENOSYS error on both Linux and FreeBSD, or EINVAL 21 // error on Linux, fall back to using accept. 22 switch err { 23 case nil: 24 return ns, sa, "", nil 25 default: // errors other than the ones listed 26 return -1, sa, "accept4", err 27 case syscall.ENOSYS: // syscall missing 28 case syscall.EINVAL: // some Linux use this instead of ENOSYS 29 case syscall.EACCES: // some Linux use this instead of ENOSYS 30 case syscall.EFAULT: // some Linux use this instead of ENOSYS 31 } 32 33 // See ../syscall/exec_unix.go for description of ForkLock. 34 // It is probably okay to hold the lock across syscall.Accept 35 // because we have put fd.sysfd into non-blocking mode. 36 // However, a call to the File method will put it back into 37 // blocking mode. We can't take that risk, so no use of ForkLock here. 38 ns, sa, err = AcceptFunc(s) 39 if err == nil { 40 syscall.CloseOnExec(ns) 41 } 42 if err != nil { 43 return -1, nil, "accept", err 44 } 45 if err = syscall.SetNonblock(ns, true); err != nil { 46 CloseFunc(ns) 47 return -1, nil, "setnonblock", err 48 } 49 return ns, sa, "", nil 50 } 51