1 files changed, 51 insertions, 0 deletions
diff --git a/src/internal/poll/sock_cloexec_accept.go b/src/internal/poll/sock_cloexec_accept.go
new file mode 100644
index 0000000000..4b86de59e0
--- /dev/null
+++ b/src/internal/poll/sock_cloexec_accept.go
@@ -0,0 +1,51 @@
+// 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 accept for platforms that provide a fast path for
+// setting SetNonblock and CloseOnExec, but don't necessarily have accept4.
+// This is the code we used for accept in Go 1.17 and earlier.
+// On Linux the accept4 system call was introduced in 2.6.28 kernel,
+// and our minimum requirement is 2.6.32, so we simplified the function.
+// Unfortunately, on ARM accept4 wasn't added until 2.6.36, so for ARM
+// only we continue using the older code.
+
+//go:build linux && arm
+
+package poll
+
+import "syscall"
+
+// Wrapper around the accept system call that marks the returned file
+// descriptor as nonblocking and close-on-exec.
+func accept(s int) (int, syscall.Sockaddr, string, error) {
+	ns, sa, err := Accept4Func(s, syscall.SOCK_NONBLOCK|syscall.SOCK_CLOEXEC)
+	switch err {
+	case nil:
+		return ns, sa, "", nil
+	default: // errors other than the ones listed
+		return -1, sa, "accept4", err
+	case syscall.ENOSYS: // syscall missing
+	case syscall.EINVAL: // some Linux use this instead of ENOSYS
+	case syscall.EACCES: // some Linux use this instead of ENOSYS
+	case syscall.EFAULT: // some Linux use this instead of ENOSYS
+	}
+
+	// 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.
+	ns, sa, err = AcceptFunc(s)
+	if err == nil {
+		syscall.CloseOnExec(ns)
+	}
+	if err != nil {
+		return -1, nil, "accept", err
+	}
+	if err = syscall.SetNonblock(ns, true); err != nil {
+		CloseFunc(ns)
+		return -1, nil, "setnonblock", err
+	}
+	return ns, sa, "", nil
+}