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  }
    40
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