1 files changed, 37 insertions, 0 deletions
diff --git a/src/net/sock_bsd.go b/src/net/sock_bsd.go
new file mode 100644
index 000000000..6c37109f5
--- /dev/null
+++ b/src/net/sock_bsd.go
@@ -0,0 +1,37 @@
+// Copyright 2009 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.
+
+// +build darwin dragonfly freebsd netbsd openbsd
+
+package net
+
+import (
+	"runtime"
+	"syscall"
+)
+
+func maxListenerBacklog() int {
+	var (
+		n   uint32
+		err error
+	)
+	switch runtime.GOOS {
+	case "darwin", "freebsd":
+		n, err = syscall.SysctlUint32("kern.ipc.somaxconn")
+	case "netbsd":
+		// NOTE: NetBSD has no somaxconn-like kernel state so far
+	case "openbsd":
+		n, err = syscall.SysctlUint32("kern.somaxconn")
+	}
+	if n == 0 || err != nil {
+		return syscall.SOMAXCONN
+	}
+	// FreeBSD stores the backlog in a uint16, as does Linux.
+	// Assume the other BSDs do too. Truncate number to avoid wrapping.
+	// See issue 5030.
+	if n > 1<<16-1 {
+		n = 1<<16 - 1
+	}
+	return int(n)
+}