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// +build aix darwin freebsd linux netbsd openbsd solaris
6
7package syscall
8
9import (
10	"runtime"
11)
12
13// Round the length of a raw sockaddr up to align it properly.
14func cmsgAlignOf(salen int) int {
15	salign := sizeofPtr
16
17	// dragonfly needs to check ABI version at runtime, see cmsgAlignOf in
18	// sockcmsg_dragonfly.go
19	switch runtime.GOOS {
20	case "aix":
21		// There is no alignment on AIX.
22		salign = 1
23	case "darwin", "illumos", "solaris":
24		// NOTE: It seems like 64-bit Darwin, Illumos and Solaris
25		// kernels still require 32-bit aligned access to network
26		// subsystem.
27		if sizeofPtr == 8 {
28			salign = 4
29		}
30	case "netbsd", "openbsd":
31		// NetBSD and OpenBSD armv7 require 64-bit alignment.
32		if runtime.GOARCH == "arm" {
33			salign = 8
34		}
35	}
36
37	return (salen + salign - 1) & ^(salign - 1)
38}
39