libgo/go/net/sock_bsd.go

   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
   5 //go:build darwin || dragonfly || freebsd || netbsd || openbsd
   6
   7 package net
   8
   9 import (
  10         "runtime"
  11         "syscall"
  12 )
  13
  14 func maxListenerBacklog() int {
  15         var (
  16                 n   uint32
  17                 err error
  18         )
  19         switch runtime.GOOS {
  20         case "darwin", "ios":
  21                 n, err = syscall.SysctlUint32("kern.ipc.somaxconn")
  22         case "freebsd":
  23                 n, err = syscall.SysctlUint32("kern.ipc.soacceptqueue")
  24         case "netbsd":
  25                 // NOTE: NetBSD has no somaxconn-like kernel state so far
  26         case "openbsd":
  27                 n, err = syscall.SysctlUint32("kern.somaxconn")
  28         }
  29         if n == 0 || err != nil {
  30                 return syscall.SOMAXCONN
  31         }
  32         // FreeBSD stores the backlog in a uint16, as does Linux.
  33         // Assume the other BSDs do too. Truncate number to avoid wrapping.
  34         // See issue 5030.
  35         if n > 1<<16-1 {
  36                 n = 1<<16 - 1
  37         }
  38         return int(n)
  39 }