1 files changed, 78 insertions, 0 deletions
diff --git a/src/net/sock_cloexec.go b/src/net/sock_cloexec.go
new file mode 100644
index 000000000..dec81855b
--- /dev/null
+++ b/src/net/sock_cloexec.go
@@ -0,0 +1,78 @@
+// 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 sysSocket and accept for platforms that
+// provide a fast path for setting SetNonblock and CloseOnExec.
+
+// +build freebsd linux
+
+package net
+
+import "syscall"
+
+// Wrapper around the socket system call that marks the returned file
+// descriptor as nonblocking and close-on-exec.
+func sysSocket(family, sotype, proto int) (int, error) {
+	s, err := syscall.Socket(family, sotype|syscall.SOCK_NONBLOCK|syscall.SOCK_CLOEXEC, proto)
+	// On Linux the SOCK_NONBLOCK and SOCK_CLOEXEC flags were
+	// introduced in 2.6.27 kernel and on FreeBSD both flags were
+	// introduced in 10 kernel. If we get an EINVAL error on Linux
+	// or EPROTONOSUPPORT error on FreeBSD, fall back to using
+	// socket without them.
+	if err == nil || (err != syscall.EPROTONOSUPPORT && err != syscall.EINVAL) {
+		return s, err
+	}
+
+	// See ../syscall/exec_unix.go for description of ForkLock.
+	syscall.ForkLock.RLock()
+	s, err = syscall.Socket(family, sotype, proto)
+	if err == nil {
+		syscall.CloseOnExec(s)
+	}
+	syscall.ForkLock.RUnlock()
+	if err != nil {
+		return -1, err
+	}
+	if err = syscall.SetNonblock(s, true); err != nil {
+		syscall.Close(s)
+		return -1, err
+	}
+	return s, nil
+}
+
+// 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, error) {
+	ns, sa, err := syscall.Accept4(s, syscall.SOCK_NONBLOCK|syscall.SOCK_CLOEXEC)
+	// On Linux the accept4 system call was introduced in 2.6.28
+	// kernel and on FreeBSD it was introduced in 10 kernel. If we
+	// get an ENOSYS error on both Linux and FreeBSD, or EINVAL
+	// error on Linux, fall back to using accept.
+	switch err {
+	default: // nil and errors other than the ones listed
+		return ns, sa, 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 = syscall.Accept(s)
+	if err == nil {
+		syscall.CloseOnExec(ns)
+	}
+	if err != nil {
+		return -1, nil, err
+	}
+	if err = syscall.SetNonblock(ns, true); err != nil {
+		syscall.Close(ns)
+		return -1, nil, err
+	}
+	return ns, sa, nil
+}