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 accept for platforms that provide a fast path for 6 // setting SetNonblock and CloseOnExec, but don't necessarily have accept4. 7 // This is the code we used for accept in Go 1.17 and earlier. 8 // On Linux the accept4 system call was introduced in 2.6.28 kernel, 9 // and our minimum requirement is 2.6.32, so we simplified the function. 10 // Unfortunately, on ARM accept4 wasn't added until 2.6.36, so for ARM 11 // only we continue using the older code. 12 13 //go:build linux && arm 14 15 package poll 16 17 import "syscall" 18 19 // Wrapper around the accept system call that marks the returned file 20 // descriptor as nonblocking and close-on-exec. 21 func accept(s int) (int, syscall.Sockaddr, string, error) { 22 ns, sa, err := Accept4Func(s, syscall.SOCK_NONBLOCK|syscall.SOCK_CLOEXEC) 23 switch err { 24 case nil: 25 return ns, sa, "", nil 26 default: // errors other than the ones listed 27 return -1, sa, "accept4", err 28 case syscall.ENOSYS: // syscall missing 29 case syscall.EINVAL: // some Linux use this instead of ENOSYS 30 case syscall.EACCES: // some Linux use this instead of ENOSYS 31 case syscall.EFAULT: // some Linux use this instead of ENOSYS 32 } 33 34 // See ../syscall/exec_unix.go for description of ForkLock. 35 // It is probably okay to hold the lock across syscall.Accept 36 // because we have put fd.sysfd into non-blocking mode. 37 // However, a call to the File method will put it back into 38 // blocking mode. We can't take that risk, so no use of ForkLock here. 39 ns, sa, err = AcceptFunc(s) 40 if err == nil { 41 syscall.CloseOnExec(ns) 42 } 43 if err != nil { 44 return -1, nil, "accept", err 45 } 46 if err = syscall.SetNonblock(ns, true); err != nil { 47 CloseFunc(ns) 48 return -1, nil, "setnonblock", err 49 } 50 return ns, sa, "", nil 51 } 52