var (
	osreldateOnce sync.Once
	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 {

var (
	osreldateOnce sync.Once
	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
}

	ifanm := &wireFormat{extOff: sizeofIfAnnouncemsghdrDragonFlyBSD4, bodyOff: sizeofIfAnnouncemsghdrDragonFlyBSD4}
	ifanm.parse = ifanm.parseInterfaceAnnounceMessage

	rel, _ := syscall.SysctlUint32("kern.osreldate")
	if rel >= 500705 {
		// https://github.com/DragonFlyBSD/DragonFlyBSD/commit/43a373152df2d405c9940983e584e6a25e76632d
		// but only the size of struct ifa_msghdr actually changed
		rtmVersion = 7

	"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.
type SockaddrDatalink struct {
	Len    uint8

		ifanm = &wireFormat{extOff: sizeofIfAnnouncemsghdrFreeBSD10, bodyOff: sizeofIfAnnouncemsghdrFreeBSD10}
	}
	rel, _ := syscall.SysctlUint32("kern.osreldate")
	switch {
	case rel < 800000:
		if compatFreeBSD32 {
			ifm.bodyOff = sizeofIfMsghdrFreeBSD7Emu
		} else {
			ifm.bodyOff = sizeofIfMsghdrFreeBSD7
		}
	case 800000 <= rel && rel < 900000:

		},
		{
			name: "failed to read os-release file",
			readFileFunc: func(_ string) ([]byte, error) {
				return nil, errors.New("open /proc/sys/kernel/osrelease: failed to read file")
			},
			err:      errors.New("failed to read os-release file: open /proc/sys/kernel/osrelease: failed to read file"),
			expected: nil,
		},
		{
			name: "version not parsable",
			readFileFunc: func(_ string) ([]byte, error) {

	return getVersion(os.ReadFile)
}

// getVersion reads os release file from the give readFile function.
func getVersion(readFile readFileFunc) (*version.Version, error) {
	kernelVersionFile := "/proc/sys/kernel/osrelease"
	fileContent, err := readFile(kernelVersionFile)
	if err != nil {
		return nil, fmt.Errorf("failed to read os-release file: %s", err.Error())
	}

	{"kern.ngroups", []_C_int{1, 18}},
	{"kern.nosuidcoredump", []_C_int{1, 32}},
	{"kern.nprocs", []_C_int{1, 47}},
	{"kern.nthreads", []_C_int{1, 26}},
	{"kern.numvnodes", []_C_int{1, 58}},
	{"kern.osrelease", []_C_int{1, 2}},
	{"kern.osrevision", []_C_int{1, 3}},
	{"kern.ostype", []_C_int{1, 1}},
	{"kern.osversion", []_C_int{1, 27}},
	{"kern.pfstatus", []_C_int{1, 86}},
	{"kern.pool_debug", []_C_int{1, 77}},

	{"kern.ngroups", []_C_int{1, 18}},
	{"kern.nosuidcoredump", []_C_int{1, 32}},
	{"kern.nprocs", []_C_int{1, 47}},
	{"kern.nthreads", []_C_int{1, 26}},
	{"kern.numvnodes", []_C_int{1, 58}},
	{"kern.osrelease", []_C_int{1, 2}},
	{"kern.osrevision", []_C_int{1, 3}},
	{"kern.ostype", []_C_int{1, 1}},
	{"kern.osversion", []_C_int{1, 27}},
	{"kern.pfstatus", []_C_int{1, 86}},
	{"kern.pool_debug", []_C_int{1, 77}},

	{"kern.ngroups", []_C_int{1, 18}},
	{"kern.nosuidcoredump", []_C_int{1, 32}},
	{"kern.nprocs", []_C_int{1, 47}},
	{"kern.nthreads", []_C_int{1, 26}},
	{"kern.numvnodes", []_C_int{1, 58}},
	{"kern.osrelease", []_C_int{1, 2}},
	{"kern.osrevision", []_C_int{1, 3}},
	{"kern.ostype", []_C_int{1, 1}},
	{"kern.osversion", []_C_int{1, 27}},
	{"kern.pfstatus", []_C_int{1, 86}},
	{"kern.pool_debug", []_C_int{1, 77}},