1// Copyright 2009 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
5package net
6
7import "syscall"
8
9func maxListenerBacklog() int {
10	fd, err := open("/proc/sys/net/core/somaxconn")
11	if err != nil {
12		return syscall.SOMAXCONN
13	}
14	defer fd.close()
15	l, ok := fd.readLine()
16	if !ok {
17		return syscall.SOMAXCONN
18	}
19	f := getFields(l)
20	n, _, ok := dtoi(f[0])
21	if n == 0 || !ok {
22		return syscall.SOMAXCONN
23	}
24	// Linux stores the backlog in a uint16.
25	// Truncate number to avoid wrapping.
26	// See issue 5030.
27	if n > 1<<16-1 {
28		n = 1<<16 - 1
29	}
30	return n
31}
32