// license that can be found in the LICENSE file.

package unix

// Round the length of a raw sockaddr up to align it properly.
func cmsgAlignOf(salen int) int {
	salign := SizeofPtr
	if SizeofPtr == 8 && !supportsABI(_dragonflyABIChangeVersion) {
		// 64-bit Dragonfly before the September 2019 ABI changes still requires
		// 32-bit aligned access to network subsystem.
		salign = 4
	}
	return (salen + salign - 1) & ^(salign - 1)

// license that can be found in the LICENSE file.

package syscall

// Round the length of a raw sockaddr up to align it properly.
func cmsgAlignOf(salen int) int {
	salign := sizeofPtr
	if sizeofPtr == 8 && !supportsABI(_dragonflyABIChangeVersion) {
		// 64-bit Dragonfly before the September 2019 ABI changes still requires
		// 32-bit aligned access to network subsystem.
		salign = 4
	}
	return (salen + salign - 1) & ^(salign - 1)

	osreldate     uint32
)

// First __DragonFly_version after September 2019 ABI changes
// http://lists.dragonflybsd.org/pipermail/users/2019-September/358280.html
const _dragonflyABIChangeVersion = 500705

func supportsABI(ver uint32) bool {
	osreldateOnce.Do(func() { osreldate, _ = SysctlUint32("kern.osreldate") })
	return osreldate >= ver
}

type SockaddrDatalink struct {
	Len    uint8
	Family uint8
	Index  uint16

	osreldate     uint32
)

// First __DragonFly_version after September 2019 ABI changes
// http://lists.dragonflybsd.org/pipermail/users/2019-September/358280.html
const _dragonflyABIChangeVersion = 500705

func supportsABI(ver uint32) bool {
	osreldateOnce.Do(func() { osreldate, _ = SysctlUint32("kern.osreldate") })
	return osreldate >= ver
}

// SockaddrDatalink implements the Sockaddr interface for AF_LINK type sockets.

import (
	"errors"
	"sync"
	"unsafe"
)

// See https://www.freebsd.org/doc/en_US.ISO8859-1/books/porters-handbook/versions.html.
var (
	osreldateOnce sync.Once
	osreldate     uint32
)

func supportsABI(ver uint32) bool {
	osreldateOnce.Do(func() { osreldate, _ = SysctlUint32("kern.osreldate") })
	return osreldate >= ver
}

// SockaddrDatalink implements the Sockaddr interface for AF_LINK type sockets.