sockcmsg_unix_other.go

     1  // Copyright 2019 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 aix || darwin || freebsd || linux || netbsd || openbsd || solaris || zos
     6  // +build aix darwin freebsd linux netbsd openbsd solaris zos
     7  
     8  package unix
     9  
    10  import (
    11  	"runtime"
    12  )
    13  
    14  // Round the length of a raw sockaddr up to align it properly.
    15  func cmsgAlignOf(salen int) int {
    16  	salign := SizeofPtr
    17  
    18  	// dragonfly needs to check ABI version at runtime, see cmsgAlignOf in
    19  	// sockcmsg_dragonfly.go
    20  	switch runtime.GOOS {
    21  	case "aix":
    22  		// There is no alignment on AIX.
    23  		salign = 1
    24  	case "darwin", "ios", "illumos", "solaris":
    25  		// NOTE: It seems like 64-bit Darwin, Illumos and Solaris
    26  		// kernels still require 32-bit aligned access to network
    27  		// subsystem.
    28  		if SizeofPtr == 8 {
    29  			salign = 4
    30  		}
    31  	case "netbsd", "openbsd":
    32  		// NetBSD and OpenBSD armv7 require 64-bit alignment.
    33  		if runtime.GOARCH == "arm" {
    34  			salign = 8
    35  		}
    36  		// NetBSD aarch64 requires 128-bit alignment.
    37  		if runtime.GOOS == "netbsd" && runtime.GOARCH == "arm64" {
    38  			salign = 16
    39  		}
    40  	case "zos":
    41  		// z/OS socket macros use [32-bit] sizeof(int) alignment,
    42  		// not pointer width.
    43  		salign = SizeofInt
    44  	}
    45  
    46  	return (salen + salign - 1) & ^(salign - 1)
    47  }
    48
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