1 // Copyright 2024 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 // The accept4(3c) function was added to Oracle Solaris in the Solaris 11.4.0
8 // release. Thus, on releases prior to 11.4, we fall back to the combination
9 // of accept(3c) and fcntl(2).
10 11 package poll
12 13 import (
14 "internal/syscall/unix"
15 "syscall"
16 )
17 18 // Wrapper around the accept system call that marks the returned file
19 // descriptor as nonblocking and close-on-exec.
20 func accept(s int) (int, syscall.Sockaddr, []byte, error) {
21 // Perform a cheap test and try the fast path first.
22 if unix.SupportAccept4() {
23 ns, sa, err := Accept4Func(s, syscall.SOCK_NONBLOCK|syscall.SOCK_CLOEXEC)
24 if err != nil {
25 return -1, nil, "accept4", err
26 }
27 return ns, sa, "", nil
28 }
29 30 // See ../syscall/exec_unix.go for description of ForkLock.
31 // It is probably okay to hold the lock across syscall.Accept
32 // because we have put fd.sysfd into non-blocking mode.
33 // However, a call to the File method will put it back into
34 // blocking mode. We can't take that risk, so no use of ForkLock here.
35 ns, sa, err := AcceptFunc(s)
36 if err == nil {
37 syscall.CloseOnExec(ns)
38 }
39 if err != nil {
40 return -1, nil, "accept", err
41 }
42 if err = syscall.SetNonblock(ns, true); err != nil {
43 CloseFunc(ns)
44 return -1, nil, "setnonblock", err
45 }
46 return ns, sa, "", nil
47 }
48