diff --git a/vendor/golang.org/x/sys/unix/syscall_linux.go b/vendor/golang.org/x/sys/unix/syscall_linux.go
new file mode 100644
index 0000000..e50e4cb
--- /dev/null
+++ b/vendor/golang.org/x/sys/unix/syscall_linux.go
@@ -0,0 +1,2228 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Linux system calls.
+// This file is compiled as ordinary Go code,
+// but it is also input to mksyscall,
+// which parses the //sys lines and generates system call stubs.
+// Note that sometimes we use a lowercase //sys name and
+// wrap it in our own nicer implementation.
+
+package unix
+
+import (
+	"encoding/binary"
+	"runtime"
+	"syscall"
+	"unsafe"
+)
+
+/*
+ * Wrapped
+ */
+
+func Access(path string, mode uint32) (err error) {
+	return Faccessat(AT_FDCWD, path, mode, 0)
+}
+
+func Chmod(path string, mode uint32) (err error) {
+	return Fchmodat(AT_FDCWD, path, mode, 0)
+}
+
+func Chown(path string, uid int, gid int) (err error) {
+	return Fchownat(AT_FDCWD, path, uid, gid, 0)
+}
+
+func Creat(path string, mode uint32) (fd int, err error) {
+	return Open(path, O_CREAT|O_WRONLY|O_TRUNC, mode)
+}
+
+//sys	FanotifyInit(flags uint, event_f_flags uint) (fd int, err error)
+//sys	fanotifyMark(fd int, flags uint, mask uint64, dirFd int, pathname *byte) (err error)
+
+func FanotifyMark(fd int, flags uint, mask uint64, dirFd int, pathname string) (err error) {
+	if pathname == "" {
+		return fanotifyMark(fd, flags, mask, dirFd, nil)
+	}
+	p, err := BytePtrFromString(pathname)
+	if err != nil {
+		return err
+	}
+	return fanotifyMark(fd, flags, mask, dirFd, p)
+}
+
+//sys	fchmodat(dirfd int, path string, mode uint32) (err error)
+
+func Fchmodat(dirfd int, path string, mode uint32, flags int) (err error) {
+	// Linux fchmodat doesn't support the flags parameter. Mimick glibc's behavior
+	// and check the flags. Otherwise the mode would be applied to the symlink
+	// destination which is not what the user expects.
+	if flags&^AT_SYMLINK_NOFOLLOW != 0 {
+		return EINVAL
+	} else if flags&AT_SYMLINK_NOFOLLOW != 0 {
+		return EOPNOTSUPP
+	}
+	return fchmodat(dirfd, path, mode)
+}
+
+//sys	ioctl(fd int, req uint, arg uintptr) (err error)
+
+// ioctl itself should not be exposed directly, but additional get/set
+// functions for specific types are permissible.
+
+// IoctlRetInt performs an ioctl operation specified by req on a device
+// associated with opened file descriptor fd, and returns a non-negative
+// integer that is returned by the ioctl syscall.
+func IoctlRetInt(fd int, req uint) (int, error) {
+	ret, _, err := Syscall(SYS_IOCTL, uintptr(fd), uintptr(req), 0)
+	if err != 0 {
+		return 0, err
+	}
+	return int(ret), nil
+}
+
+// IoctlSetPointerInt performs an ioctl operation which sets an
+// integer value on fd, using the specified request number. The ioctl
+// argument is called with a pointer to the integer value, rather than
+// passing the integer value directly.
+func IoctlSetPointerInt(fd int, req uint, value int) error {
+	v := int32(value)
+	return ioctl(fd, req, uintptr(unsafe.Pointer(&v)))
+}
+
+func IoctlSetRTCTime(fd int, value *RTCTime) error {
+	err := ioctl(fd, RTC_SET_TIME, uintptr(unsafe.Pointer(value)))
+	runtime.KeepAlive(value)
+	return err
+}
+
+func IoctlSetRTCWkAlrm(fd int, value *RTCWkAlrm) error {
+	err := ioctl(fd, RTC_WKALM_SET, uintptr(unsafe.Pointer(value)))
+	runtime.KeepAlive(value)
+	return err
+}
+
+func IoctlGetUint32(fd int, req uint) (uint32, error) {
+	var value uint32
+	err := ioctl(fd, req, uintptr(unsafe.Pointer(&value)))
+	return value, err
+}
+
+func IoctlGetRTCTime(fd int) (*RTCTime, error) {
+	var value RTCTime
+	err := ioctl(fd, RTC_RD_TIME, uintptr(unsafe.Pointer(&value)))
+	return &value, err
+}
+
+func IoctlGetRTCWkAlrm(fd int) (*RTCWkAlrm, error) {
+	var value RTCWkAlrm
+	err := ioctl(fd, RTC_WKALM_RD, uintptr(unsafe.Pointer(&value)))
+	return &value, err
+}
+
+//sys	Linkat(olddirfd int, oldpath string, newdirfd int, newpath string, flags int) (err error)
+
+func Link(oldpath string, newpath string) (err error) {
+	return Linkat(AT_FDCWD, oldpath, AT_FDCWD, newpath, 0)
+}
+
+func Mkdir(path string, mode uint32) (err error) {
+	return Mkdirat(AT_FDCWD, path, mode)
+}
+
+func Mknod(path string, mode uint32, dev int) (err error) {
+	return Mknodat(AT_FDCWD, path, mode, dev)
+}
+
+func Open(path string, mode int, perm uint32) (fd int, err error) {
+	return openat(AT_FDCWD, path, mode|O_LARGEFILE, perm)
+}
+
+//sys	openat(dirfd int, path string, flags int, mode uint32) (fd int, err error)
+
+func Openat(dirfd int, path string, flags int, mode uint32) (fd int, err error) {
+	return openat(dirfd, path, flags|O_LARGEFILE, mode)
+}
+
+//sys	ppoll(fds *PollFd, nfds int, timeout *Timespec, sigmask *Sigset_t) (n int, err error)
+
+func Ppoll(fds []PollFd, timeout *Timespec, sigmask *Sigset_t) (n int, err error) {
+	if len(fds) == 0 {
+		return ppoll(nil, 0, timeout, sigmask)
+	}
+	return ppoll(&fds[0], len(fds), timeout, sigmask)
+}
+
+//sys	Readlinkat(dirfd int, path string, buf []byte) (n int, err error)
+
+func Readlink(path string, buf []byte) (n int, err error) {
+	return Readlinkat(AT_FDCWD, path, buf)
+}
+
+func Rename(oldpath string, newpath string) (err error) {
+	return Renameat(AT_FDCWD, oldpath, AT_FDCWD, newpath)
+}
+
+func Rmdir(path string) error {
+	return Unlinkat(AT_FDCWD, path, AT_REMOVEDIR)
+}
+
+//sys	Symlinkat(oldpath string, newdirfd int, newpath string) (err error)
+
+func Symlink(oldpath string, newpath string) (err error) {
+	return Symlinkat(oldpath, AT_FDCWD, newpath)
+}
+
+func Unlink(path string) error {
+	return Unlinkat(AT_FDCWD, path, 0)
+}
+
+//sys	Unlinkat(dirfd int, path string, flags int) (err error)
+
+func Utimes(path string, tv []Timeval) error {
+	if tv == nil {
+		err := utimensat(AT_FDCWD, path, nil, 0)
+		if err != ENOSYS {
+			return err
+		}
+		return utimes(path, nil)
+	}
+	if len(tv) != 2 {
+		return EINVAL
+	}
+	var ts [2]Timespec
+	ts[0] = NsecToTimespec(TimevalToNsec(tv[0]))
+	ts[1] = NsecToTimespec(TimevalToNsec(tv[1]))
+	err := utimensat(AT_FDCWD, path, (*[2]Timespec)(unsafe.Pointer(&ts[0])), 0)
+	if err != ENOSYS {
+		return err
+	}
+	return utimes(path, (*[2]Timeval)(unsafe.Pointer(&tv[0])))
+}
+
+//sys	utimensat(dirfd int, path string, times *[2]Timespec, flags int) (err error)
+
+func UtimesNano(path string, ts []Timespec) error {
+	if ts == nil {
+		err := utimensat(AT_FDCWD, path, nil, 0)
+		if err != ENOSYS {
+			return err
+		}
+		return utimes(path, nil)
+	}
+	if len(ts) != 2 {
+		return EINVAL
+	}
+	err := utimensat(AT_FDCWD, path, (*[2]Timespec)(unsafe.Pointer(&ts[0])), 0)
+	if err != ENOSYS {
+		return err
+	}
+	// If the utimensat syscall isn't available (utimensat was added to Linux
+	// in 2.6.22, Released, 8 July 2007) then fall back to utimes
+	var tv [2]Timeval
+	for i := 0; i < 2; i++ {
+		tv[i] = NsecToTimeval(TimespecToNsec(ts[i]))
+	}
+	return utimes(path, (*[2]Timeval)(unsafe.Pointer(&tv[0])))
+}
+
+func UtimesNanoAt(dirfd int, path string, ts []Timespec, flags int) error {
+	if ts == nil {
+		return utimensat(dirfd, path, nil, flags)
+	}
+	if len(ts) != 2 {
+		return EINVAL
+	}
+	return utimensat(dirfd, path, (*[2]Timespec)(unsafe.Pointer(&ts[0])), flags)
+}
+
+func Futimesat(dirfd int, path string, tv []Timeval) error {
+	if tv == nil {
+		return futimesat(dirfd, path, nil)
+	}
+	if len(tv) != 2 {
+		return EINVAL
+	}
+	return futimesat(dirfd, path, (*[2]Timeval)(unsafe.Pointer(&tv[0])))
+}
+
+func Futimes(fd int, tv []Timeval) (err error) {
+	// Believe it or not, this is the best we can do on Linux
+	// (and is what glibc does).
+	return Utimes("/proc/self/fd/"+itoa(fd), tv)
+}
+
+const ImplementsGetwd = true
+
+//sys	Getcwd(buf []byte) (n int, err error)
+
+func Getwd() (wd string, err error) {
+	var buf [PathMax]byte
+	n, err := Getcwd(buf[0:])
+	if err != nil {
+		return "", err
+	}
+	// Getcwd returns the number of bytes written to buf, including the NUL.
+	if n < 1 || n > len(buf) || buf[n-1] != 0 {
+		return "", EINVAL
+	}
+	return string(buf[0 : n-1]), nil
+}
+
+func Getgroups() (gids []int, err error) {
+	n, err := getgroups(0, nil)
+	if err != nil {
+		return nil, err
+	}
+	if n == 0 {
+		return nil, nil
+	}
+
+	// Sanity check group count. Max is 1<<16 on Linux.
+	if n < 0 || n > 1<<20 {
+		return nil, EINVAL
+	}
+
+	a := make([]_Gid_t, n)
+	n, err = getgroups(n, &a[0])
+	if err != nil {
+		return nil, err
+	}
+	gids = make([]int, n)
+	for i, v := range a[0:n] {
+		gids[i] = int(v)
+	}
+	return
+}
+
+func Setgroups(gids []int) (err error) {
+	if len(gids) == 0 {
+		return setgroups(0, nil)
+	}
+
+	a := make([]_Gid_t, len(gids))
+	for i, v := range gids {
+		a[i] = _Gid_t(v)
+	}
+	return setgroups(len(a), &a[0])
+}
+
+type WaitStatus uint32
+
+// Wait status is 7 bits at bottom, either 0 (exited),
+// 0x7F (stopped), or a signal number that caused an exit.
+// The 0x80 bit is whether there was a core dump.
+// An extra number (exit code, signal causing a stop)
+// is in the high bits. At least that's the idea.
+// There are various irregularities. For example, the
+// "continued" status is 0xFFFF, distinguishing itself
+// from stopped via the core dump bit.
+
+const (
+	mask    = 0x7F
+	core    = 0x80
+	exited  = 0x00
+	stopped = 0x7F
+	shift   = 8
+)
+
+func (w WaitStatus) Exited() bool { return w&mask == exited }
+
+func (w WaitStatus) Signaled() bool { return w&mask != stopped && w&mask != exited }
+
+func (w WaitStatus) Stopped() bool { return w&0xFF == stopped }
+
+func (w WaitStatus) Continued() bool { return w == 0xFFFF }
+
+func (w WaitStatus) CoreDump() bool { return w.Signaled() && w&core != 0 }
+
+func (w WaitStatus) ExitStatus() int {
+	if !w.Exited() {
+		return -1
+	}
+	return int(w>>shift) & 0xFF
+}
+
+func (w WaitStatus) Signal() syscall.Signal {
+	if !w.Signaled() {
+		return -1
+	}
+	return syscall.Signal(w & mask)
+}
+
+func (w WaitStatus) StopSignal() syscall.Signal {
+	if !w.Stopped() {
+		return -1
+	}
+	return syscall.Signal(w>>shift) & 0xFF
+}
+
+func (w WaitStatus) TrapCause() int {
+	if w.StopSignal() != SIGTRAP {
+		return -1
+	}
+	return int(w>>shift) >> 8
+}
+
+//sys	wait4(pid int, wstatus *_C_int, options int, rusage *Rusage) (wpid int, err error)
+
+func Wait4(pid int, wstatus *WaitStatus, options int, rusage *Rusage) (wpid int, err error) {
+	var status _C_int
+	wpid, err = wait4(pid, &status, options, rusage)
+	if wstatus != nil {
+		*wstatus = WaitStatus(status)
+	}
+	return
+}
+
+func Mkfifo(path string, mode uint32) error {
+	return Mknod(path, mode|S_IFIFO, 0)
+}
+
+func Mkfifoat(dirfd int, path string, mode uint32) error {
+	return Mknodat(dirfd, path, mode|S_IFIFO, 0)
+}
+
+func (sa *SockaddrInet4) sockaddr() (unsafe.Pointer, _Socklen, error) {
+	if sa.Port < 0 || sa.Port > 0xFFFF {
+		return nil, 0, EINVAL
+	}
+	sa.raw.Family = AF_INET
+	p := (*[2]byte)(unsafe.Pointer(&sa.raw.Port))
+	p[0] = byte(sa.Port >> 8)
+	p[1] = byte(sa.Port)
+	for i := 0; i < len(sa.Addr); i++ {
+		sa.raw.Addr[i] = sa.Addr[i]
+	}
+	return unsafe.Pointer(&sa.raw), SizeofSockaddrInet4, nil
+}
+
+func (sa *SockaddrInet6) sockaddr() (unsafe.Pointer, _Socklen, error) {
+	if sa.Port < 0 || sa.Port > 0xFFFF {
+		return nil, 0, EINVAL
+	}
+	sa.raw.Family = AF_INET6
+	p := (*[2]byte)(unsafe.Pointer(&sa.raw.Port))
+	p[0] = byte(sa.Port >> 8)
+	p[1] = byte(sa.Port)
+	sa.raw.Scope_id = sa.ZoneId
+	for i := 0; i < len(sa.Addr); i++ {
+		sa.raw.Addr[i] = sa.Addr[i]
+	}
+	return unsafe.Pointer(&sa.raw), SizeofSockaddrInet6, nil
+}
+
+func (sa *SockaddrUnix) sockaddr() (unsafe.Pointer, _Socklen, error) {
+	name := sa.Name
+	n := len(name)
+	if n >= len(sa.raw.Path) {
+		return nil, 0, EINVAL
+	}
+	sa.raw.Family = AF_UNIX
+	for i := 0; i < n; i++ {
+		sa.raw.Path[i] = int8(name[i])
+	}
+	// length is family (uint16), name, NUL.
+	sl := _Socklen(2)
+	if n > 0 {
+		sl += _Socklen(n) + 1
+	}
+	if sa.raw.Path[0] == '@' {
+		sa.raw.Path[0] = 0
+		// Don't count trailing NUL for abstract address.
+		sl--
+	}
+
+	return unsafe.Pointer(&sa.raw), sl, nil
+}
+
+// SockaddrLinklayer implements the Sockaddr interface for AF_PACKET type sockets.
+type SockaddrLinklayer struct {
+	Protocol uint16
+	Ifindex  int
+	Hatype   uint16
+	Pkttype  uint8
+	Halen    uint8
+	Addr     [8]byte
+	raw      RawSockaddrLinklayer
+}
+
+func (sa *SockaddrLinklayer) sockaddr() (unsafe.Pointer, _Socklen, error) {
+	if sa.Ifindex < 0 || sa.Ifindex > 0x7fffffff {
+		return nil, 0, EINVAL
+	}
+	sa.raw.Family = AF_PACKET
+	sa.raw.Protocol = sa.Protocol
+	sa.raw.Ifindex = int32(sa.Ifindex)
+	sa.raw.Hatype = sa.Hatype
+	sa.raw.Pkttype = sa.Pkttype
+	sa.raw.Halen = sa.Halen
+	for i := 0; i < len(sa.Addr); i++ {
+		sa.raw.Addr[i] = sa.Addr[i]
+	}
+	return unsafe.Pointer(&sa.raw), SizeofSockaddrLinklayer, nil
+}
+
+// SockaddrNetlink implements the Sockaddr interface for AF_NETLINK type sockets.
+type SockaddrNetlink struct {
+	Family uint16
+	Pad    uint16
+	Pid    uint32
+	Groups uint32
+	raw    RawSockaddrNetlink
+}
+
+func (sa *SockaddrNetlink) sockaddr() (unsafe.Pointer, _Socklen, error) {
+	sa.raw.Family = AF_NETLINK
+	sa.raw.Pad = sa.Pad
+	sa.raw.Pid = sa.Pid
+	sa.raw.Groups = sa.Groups
+	return unsafe.Pointer(&sa.raw), SizeofSockaddrNetlink, nil
+}
+
+// SockaddrHCI implements the Sockaddr interface for AF_BLUETOOTH type sockets
+// using the HCI protocol.
+type SockaddrHCI struct {
+	Dev     uint16
+	Channel uint16
+	raw     RawSockaddrHCI
+}
+
+func (sa *SockaddrHCI) sockaddr() (unsafe.Pointer, _Socklen, error) {
+	sa.raw.Family = AF_BLUETOOTH
+	sa.raw.Dev = sa.Dev
+	sa.raw.Channel = sa.Channel
+	return unsafe.Pointer(&sa.raw), SizeofSockaddrHCI, nil
+}
+
+// SockaddrL2 implements the Sockaddr interface for AF_BLUETOOTH type sockets
+// using the L2CAP protocol.
+type SockaddrL2 struct {
+	PSM      uint16
+	CID      uint16
+	Addr     [6]uint8
+	AddrType uint8
+	raw      RawSockaddrL2
+}
+
+func (sa *SockaddrL2) sockaddr() (unsafe.Pointer, _Socklen, error) {
+	sa.raw.Family = AF_BLUETOOTH
+	psm := (*[2]byte)(unsafe.Pointer(&sa.raw.Psm))
+	psm[0] = byte(sa.PSM)
+	psm[1] = byte(sa.PSM >> 8)
+	for i := 0; i < len(sa.Addr); i++ {
+		sa.raw.Bdaddr[i] = sa.Addr[len(sa.Addr)-1-i]
+	}
+	cid := (*[2]byte)(unsafe.Pointer(&sa.raw.Cid))
+	cid[0] = byte(sa.CID)
+	cid[1] = byte(sa.CID >> 8)
+	sa.raw.Bdaddr_type = sa.AddrType
+	return unsafe.Pointer(&sa.raw), SizeofSockaddrL2, nil
+}
+
+// SockaddrRFCOMM implements the Sockaddr interface for AF_BLUETOOTH type sockets
+// using the RFCOMM protocol.
+//
+// Server example:
+//
+//      fd, _ := Socket(AF_BLUETOOTH, SOCK_STREAM, BTPROTO_RFCOMM)
+//      _ = unix.Bind(fd, &unix.SockaddrRFCOMM{
+//      	Channel: 1,
+//      	Addr:    [6]uint8{0, 0, 0, 0, 0, 0}, // BDADDR_ANY or 00:00:00:00:00:00
+//      })
+//      _ = Listen(fd, 1)
+//      nfd, sa, _ := Accept(fd)
+//      fmt.Printf("conn addr=%v fd=%d", sa.(*unix.SockaddrRFCOMM).Addr, nfd)
+//      Read(nfd, buf)
+//
+// Client example:
+//
+//      fd, _ := Socket(AF_BLUETOOTH, SOCK_STREAM, BTPROTO_RFCOMM)
+//      _ = Connect(fd, &SockaddrRFCOMM{
+//      	Channel: 1,
+//      	Addr:    [6]byte{0x11, 0x22, 0x33, 0xaa, 0xbb, 0xcc}, // CC:BB:AA:33:22:11
+//      })
+//      Write(fd, []byte(`hello`))
+type SockaddrRFCOMM struct {
+	// Addr represents a bluetooth address, byte ordering is little-endian.
+	Addr [6]uint8
+
+	// Channel is a designated bluetooth channel, only 1-30 are available for use.
+	// Since Linux 2.6.7 and further zero value is the first available channel.
+	Channel uint8
+
+	raw RawSockaddrRFCOMM
+}
+
+func (sa *SockaddrRFCOMM) sockaddr() (unsafe.Pointer, _Socklen, error) {
+	sa.raw.Family = AF_BLUETOOTH
+	sa.raw.Channel = sa.Channel
+	sa.raw.Bdaddr = sa.Addr
+	return unsafe.Pointer(&sa.raw), SizeofSockaddrRFCOMM, nil
+}
+
+// SockaddrCAN implements the Sockaddr interface for AF_CAN type sockets.
+// The RxID and TxID fields are used for transport protocol addressing in
+// (CAN_TP16, CAN_TP20, CAN_MCNET, and CAN_ISOTP), they can be left with
+// zero values for CAN_RAW and CAN_BCM sockets as they have no meaning.
+//
+// The SockaddrCAN struct must be bound to the socket file descriptor
+// using Bind before the CAN socket can be used.
+//
+//      // Read one raw CAN frame
+//      fd, _ := Socket(AF_CAN, SOCK_RAW, CAN_RAW)
+//      addr := &SockaddrCAN{Ifindex: index}
+//      Bind(fd, addr)
+//      frame := make([]byte, 16)
+//      Read(fd, frame)
+//
+// The full SocketCAN documentation can be found in the linux kernel
+// archives at: https://www.kernel.org/doc/Documentation/networking/can.txt
+type SockaddrCAN struct {
+	Ifindex int
+	RxID    uint32
+	TxID    uint32
+	raw     RawSockaddrCAN
+}
+
+func (sa *SockaddrCAN) sockaddr() (unsafe.Pointer, _Socklen, error) {
+	if sa.Ifindex < 0 || sa.Ifindex > 0x7fffffff {
+		return nil, 0, EINVAL
+	}
+	sa.raw.Family = AF_CAN
+	sa.raw.Ifindex = int32(sa.Ifindex)
+	rx := (*[4]byte)(unsafe.Pointer(&sa.RxID))
+	for i := 0; i < 4; i++ {
+		sa.raw.Addr[i] = rx[i]
+	}
+	tx := (*[4]byte)(unsafe.Pointer(&sa.TxID))
+	for i := 0; i < 4; i++ {
+		sa.raw.Addr[i+4] = tx[i]
+	}
+	return unsafe.Pointer(&sa.raw), SizeofSockaddrCAN, nil
+}
+
+// SockaddrALG implements the Sockaddr interface for AF_ALG type sockets.
+// SockaddrALG enables userspace access to the Linux kernel's cryptography
+// subsystem. The Type and Name fields specify which type of hash or cipher
+// should be used with a given socket.
+//
+// To create a file descriptor that provides access to a hash or cipher, both
+// Bind and Accept must be used. Once the setup process is complete, input
+// data can be written to the socket, processed by the kernel, and then read
+// back as hash output or ciphertext.
+//
+// Here is an example of using an AF_ALG socket with SHA1 hashing.
+// The initial socket setup process is as follows:
+//
+//      // Open a socket to perform SHA1 hashing.
+//      fd, _ := unix.Socket(unix.AF_ALG, unix.SOCK_SEQPACKET, 0)
+//      addr := &unix.SockaddrALG{Type: "hash", Name: "sha1"}
+//      unix.Bind(fd, addr)
+//      // Note: unix.Accept does not work at this time; must invoke accept()
+//      // manually using unix.Syscall.
+//      hashfd, _, _ := unix.Syscall(unix.SYS_ACCEPT, uintptr(fd), 0, 0)
+//
+// Once a file descriptor has been returned from Accept, it may be used to
+// perform SHA1 hashing. The descriptor is not safe for concurrent use, but
+// may be re-used repeatedly with subsequent Write and Read operations.
+//
+// When hashing a small byte slice or string, a single Write and Read may
+// be used:
+//
+//      // Assume hashfd is already configured using the setup process.
+//      hash := os.NewFile(hashfd, "sha1")
+//      // Hash an input string and read the results. Each Write discards
+//      // previous hash state. Read always reads the current state.
+//      b := make([]byte, 20)
+//      for i := 0; i < 2; i++ {
+//          io.WriteString(hash, "Hello, world.")
+//          hash.Read(b)
+//          fmt.Println(hex.EncodeToString(b))
+//      }
+//      // Output:
+//      // 2ae01472317d1935a84797ec1983ae243fc6aa28
+//      // 2ae01472317d1935a84797ec1983ae243fc6aa28
+//
+// For hashing larger byte slices, or byte streams such as those read from
+// a file or socket, use Sendto with MSG_MORE to instruct the kernel to update
+// the hash digest instead of creating a new one for a given chunk and finalizing it.
+//
+//      // Assume hashfd and addr are already configured using the setup process.
+//      hash := os.NewFile(hashfd, "sha1")
+//      // Hash the contents of a file.
+//      f, _ := os.Open("/tmp/linux-4.10-rc7.tar.xz")
+//      b := make([]byte, 4096)
+//      for {
+//          n, err := f.Read(b)
+//          if err == io.EOF {
+//              break
+//          }
+//          unix.Sendto(hashfd, b[:n], unix.MSG_MORE, addr)
+//      }
+//      hash.Read(b)
+//      fmt.Println(hex.EncodeToString(b))
+//      // Output: 85cdcad0c06eef66f805ecce353bec9accbeecc5
+//
+// For more information, see: http://www.chronox.de/crypto-API/crypto/userspace-if.html.
+type SockaddrALG struct {
+	Type    string
+	Name    string
+	Feature uint32
+	Mask    uint32
+	raw     RawSockaddrALG
+}
+
+func (sa *SockaddrALG) sockaddr() (unsafe.Pointer, _Socklen, error) {
+	// Leave room for NUL byte terminator.
+	if len(sa.Type) > 13 {
+		return nil, 0, EINVAL
+	}
+	if len(sa.Name) > 63 {
+		return nil, 0, EINVAL
+	}
+
+	sa.raw.Family = AF_ALG
+	sa.raw.Feat = sa.Feature
+	sa.raw.Mask = sa.Mask
+
+	typ, err := ByteSliceFromString(sa.Type)
+	if err != nil {
+		return nil, 0, err
+	}
+	name, err := ByteSliceFromString(sa.Name)
+	if err != nil {
+		return nil, 0, err
+	}
+
+	copy(sa.raw.Type[:], typ)
+	copy(sa.raw.Name[:], name)
+
+	return unsafe.Pointer(&sa.raw), SizeofSockaddrALG, nil
+}
+
+// SockaddrVM implements the Sockaddr interface for AF_VSOCK type sockets.
+// SockaddrVM provides access to Linux VM sockets: a mechanism that enables
+// bidirectional communication between a hypervisor and its guest virtual
+// machines.
+type SockaddrVM struct {
+	// CID and Port specify a context ID and port address for a VM socket.
+	// Guests have a unique CID, and hosts may have a well-known CID of:
+	//  - VMADDR_CID_HYPERVISOR: refers to the hypervisor process.
+	//  - VMADDR_CID_HOST: refers to other processes on the host.
+	CID  uint32
+	Port uint32
+	raw  RawSockaddrVM
+}
+
+func (sa *SockaddrVM) sockaddr() (unsafe.Pointer, _Socklen, error) {
+	sa.raw.Family = AF_VSOCK
+	sa.raw.Port = sa.Port
+	sa.raw.Cid = sa.CID
+
+	return unsafe.Pointer(&sa.raw), SizeofSockaddrVM, nil
+}
+
+type SockaddrXDP struct {
+	Flags        uint16
+	Ifindex      uint32
+	QueueID      uint32
+	SharedUmemFD uint32
+	raw          RawSockaddrXDP
+}
+
+func (sa *SockaddrXDP) sockaddr() (unsafe.Pointer, _Socklen, error) {
+	sa.raw.Family = AF_XDP
+	sa.raw.Flags = sa.Flags
+	sa.raw.Ifindex = sa.Ifindex
+	sa.raw.Queue_id = sa.QueueID
+	sa.raw.Shared_umem_fd = sa.SharedUmemFD
+
+	return unsafe.Pointer(&sa.raw), SizeofSockaddrXDP, nil
+}
+
+// This constant mirrors the #define of PX_PROTO_OE in
+// linux/if_pppox.h. We're defining this by hand here instead of
+// autogenerating through mkerrors.sh because including
+// linux/if_pppox.h causes some declaration conflicts with other
+// includes (linux/if_pppox.h includes linux/in.h, which conflicts
+// with netinet/in.h). Given that we only need a single zero constant
+// out of that file, it's cleaner to just define it by hand here.
+const px_proto_oe = 0
+
+type SockaddrPPPoE struct {
+	SID    uint16
+	Remote []byte
+	Dev    string
+	raw    RawSockaddrPPPoX
+}
+
+func (sa *SockaddrPPPoE) sockaddr() (unsafe.Pointer, _Socklen, error) {
+	if len(sa.Remote) != 6 {
+		return nil, 0, EINVAL
+	}
+	if len(sa.Dev) > IFNAMSIZ-1 {
+		return nil, 0, EINVAL
+	}
+
+	*(*uint16)(unsafe.Pointer(&sa.raw[0])) = AF_PPPOX
+	// This next field is in host-endian byte order. We can't use the
+	// same unsafe pointer cast as above, because this value is not
+	// 32-bit aligned and some architectures don't allow unaligned
+	// access.
+	//
+	// However, the value of px_proto_oe is 0, so we can use
+	// encoding/binary helpers to write the bytes without worrying
+	// about the ordering.
+	binary.BigEndian.PutUint32(sa.raw[2:6], px_proto_oe)
+	// This field is deliberately big-endian, unlike the previous
+	// one. The kernel expects SID to be in network byte order.
+	binary.BigEndian.PutUint16(sa.raw[6:8], sa.SID)
+	copy(sa.raw[8:14], sa.Remote)
+	for i := 14; i < 14+IFNAMSIZ; i++ {
+		sa.raw[i] = 0
+	}
+	copy(sa.raw[14:], sa.Dev)
+	return unsafe.Pointer(&sa.raw), SizeofSockaddrPPPoX, nil
+}
+
+// SockaddrTIPC implements the Sockaddr interface for AF_TIPC type sockets.
+// For more information on TIPC, see: http://tipc.sourceforge.net/.
+type SockaddrTIPC struct {
+	// Scope is the publication scopes when binding service/service range.
+	// Should be set to TIPC_CLUSTER_SCOPE or TIPC_NODE_SCOPE.
+	Scope int
+
+	// Addr is the type of address used to manipulate a socket. Addr must be
+	// one of:
+	//  - *TIPCSocketAddr: "id" variant in the C addr union
+	//  - *TIPCServiceRange: "nameseq" variant in the C addr union
+	//  - *TIPCServiceName: "name" variant in the C addr union
+	//
+	// If nil, EINVAL will be returned when the structure is used.
+	Addr TIPCAddr
+
+	raw RawSockaddrTIPC
+}
+
+// TIPCAddr is implemented by types that can be used as an address for
+// SockaddrTIPC. It is only implemented by *TIPCSocketAddr, *TIPCServiceRange,
+// and *TIPCServiceName.
+type TIPCAddr interface {
+	tipcAddrtype() uint8
+	tipcAddr() [12]byte
+}
+
+func (sa *TIPCSocketAddr) tipcAddr() [12]byte {
+	var out [12]byte
+	copy(out[:], (*(*[unsafe.Sizeof(TIPCSocketAddr{})]byte)(unsafe.Pointer(sa)))[:])
+	return out
+}
+
+func (sa *TIPCSocketAddr) tipcAddrtype() uint8 { return TIPC_SOCKET_ADDR }
+
+func (sa *TIPCServiceRange) tipcAddr() [12]byte {
+	var out [12]byte
+	copy(out[:], (*(*[unsafe.Sizeof(TIPCServiceRange{})]byte)(unsafe.Pointer(sa)))[:])
+	return out
+}
+
+func (sa *TIPCServiceRange) tipcAddrtype() uint8 { return TIPC_SERVICE_RANGE }
+
+func (sa *TIPCServiceName) tipcAddr() [12]byte {
+	var out [12]byte
+	copy(out[:], (*(*[unsafe.Sizeof(TIPCServiceName{})]byte)(unsafe.Pointer(sa)))[:])
+	return out
+}
+
+func (sa *TIPCServiceName) tipcAddrtype() uint8 { return TIPC_SERVICE_ADDR }
+
+func (sa *SockaddrTIPC) sockaddr() (unsafe.Pointer, _Socklen, error) {
+	if sa.Addr == nil {
+		return nil, 0, EINVAL
+	}
+
+	sa.raw.Family = AF_TIPC
+	sa.raw.Scope = int8(sa.Scope)
+	sa.raw.Addrtype = sa.Addr.tipcAddrtype()
+	sa.raw.Addr = sa.Addr.tipcAddr()
+
+	return unsafe.Pointer(&sa.raw), SizeofSockaddrTIPC, nil
+}
+
+// SockaddrL2TPIP implements the Sockaddr interface for IPPROTO_L2TP/AF_INET sockets.
+type SockaddrL2TPIP struct {
+	Addr   [4]byte
+	ConnId uint32
+	raw    RawSockaddrL2TPIP
+}
+
+func (sa *SockaddrL2TPIP) sockaddr() (unsafe.Pointer, _Socklen, error) {
+	sa.raw.Family = AF_INET
+	sa.raw.Conn_id = sa.ConnId
+	for i := 0; i < len(sa.Addr); i++ {
+		sa.raw.Addr[i] = sa.Addr[i]
+	}
+	return unsafe.Pointer(&sa.raw), SizeofSockaddrL2TPIP, nil
+}
+
+// SockaddrL2TPIP6 implements the Sockaddr interface for IPPROTO_L2TP/AF_INET6 sockets.
+type SockaddrL2TPIP6 struct {
+	Addr   [16]byte
+	ZoneId uint32
+	ConnId uint32
+	raw    RawSockaddrL2TPIP6
+}
+
+func (sa *SockaddrL2TPIP6) sockaddr() (unsafe.Pointer, _Socklen, error) {
+	sa.raw.Family = AF_INET6
+	sa.raw.Conn_id = sa.ConnId
+	sa.raw.Scope_id = sa.ZoneId
+	for i := 0; i < len(sa.Addr); i++ {
+		sa.raw.Addr[i] = sa.Addr[i]
+	}
+	return unsafe.Pointer(&sa.raw), SizeofSockaddrL2TPIP6, nil
+}
+
+func anyToSockaddr(fd int, rsa *RawSockaddrAny) (Sockaddr, error) {
+	switch rsa.Addr.Family {
+	case AF_NETLINK:
+		pp := (*RawSockaddrNetlink)(unsafe.Pointer(rsa))
+		sa := new(SockaddrNetlink)
+		sa.Family = pp.Family
+		sa.Pad = pp.Pad
+		sa.Pid = pp.Pid
+		sa.Groups = pp.Groups
+		return sa, nil
+
+	case AF_PACKET:
+		pp := (*RawSockaddrLinklayer)(unsafe.Pointer(rsa))
+		sa := new(SockaddrLinklayer)
+		sa.Protocol = pp.Protocol
+		sa.Ifindex = int(pp.Ifindex)
+		sa.Hatype = pp.Hatype
+		sa.Pkttype = pp.Pkttype
+		sa.Halen = pp.Halen
+		for i := 0; i < len(sa.Addr); i++ {
+			sa.Addr[i] = pp.Addr[i]
+		}
+		return sa, nil
+
+	case AF_UNIX:
+		pp := (*RawSockaddrUnix)(unsafe.Pointer(rsa))
+		sa := new(SockaddrUnix)
+		if pp.Path[0] == 0 {
+			// "Abstract" Unix domain socket.
+			// Rewrite leading NUL as @ for textual display.
+			// (This is the standard convention.)
+			// Not friendly to overwrite in place,
+			// but the callers below don't care.
+			pp.Path[0] = '@'
+		}
+
+		// Assume path ends at NUL.
+		// This is not technically the Linux semantics for
+		// abstract Unix domain sockets--they are supposed
+		// to be uninterpreted fixed-size binary blobs--but
+		// everyone uses this convention.
+		n := 0
+		for n < len(pp.Path) && pp.Path[n] != 0 {
+			n++
+		}
+		bytes := (*[len(pp.Path)]byte)(unsafe.Pointer(&pp.Path[0]))[0:n]
+		sa.Name = string(bytes)
+		return sa, nil
+
+	case AF_INET:
+		proto, err := GetsockoptInt(fd, SOL_SOCKET, SO_PROTOCOL)
+		if err != nil {
+			return nil, err
+		}
+
+		switch proto {
+		case IPPROTO_L2TP:
+			pp := (*RawSockaddrL2TPIP)(unsafe.Pointer(rsa))
+			sa := new(SockaddrL2TPIP)
+			sa.ConnId = pp.Conn_id
+			for i := 0; i < len(sa.Addr); i++ {
+				sa.Addr[i] = pp.Addr[i]
+			}
+			return sa, nil
+		default:
+			pp := (*RawSockaddrInet4)(unsafe.Pointer(rsa))
+			sa := new(SockaddrInet4)
+			p := (*[2]byte)(unsafe.Pointer(&pp.Port))
+			sa.Port = int(p[0])<<8 + int(p[1])
+			for i := 0; i < len(sa.Addr); i++ {
+				sa.Addr[i] = pp.Addr[i]
+			}
+			return sa, nil
+		}
+
+	case AF_INET6:
+		proto, err := GetsockoptInt(fd, SOL_SOCKET, SO_PROTOCOL)
+		if err != nil {
+			return nil, err
+		}
+
+		switch proto {
+		case IPPROTO_L2TP:
+			pp := (*RawSockaddrL2TPIP6)(unsafe.Pointer(rsa))
+			sa := new(SockaddrL2TPIP6)
+			sa.ConnId = pp.Conn_id
+			sa.ZoneId = pp.Scope_id
+			for i := 0; i < len(sa.Addr); i++ {
+				sa.Addr[i] = pp.Addr[i]
+			}
+			return sa, nil
+		default:
+			pp := (*RawSockaddrInet6)(unsafe.Pointer(rsa))
+			sa := new(SockaddrInet6)
+			p := (*[2]byte)(unsafe.Pointer(&pp.Port))
+			sa.Port = int(p[0])<<8 + int(p[1])
+			sa.ZoneId = pp.Scope_id
+			for i := 0; i < len(sa.Addr); i++ {
+				sa.Addr[i] = pp.Addr[i]
+			}
+			return sa, nil
+		}
+
+	case AF_VSOCK:
+		pp := (*RawSockaddrVM)(unsafe.Pointer(rsa))
+		sa := &SockaddrVM{
+			CID:  pp.Cid,
+			Port: pp.Port,
+		}
+		return sa, nil
+	case AF_BLUETOOTH:
+		proto, err := GetsockoptInt(fd, SOL_SOCKET, SO_PROTOCOL)
+		if err != nil {
+			return nil, err
+		}
+		// only BTPROTO_L2CAP and BTPROTO_RFCOMM can accept connections
+		switch proto {
+		case BTPROTO_L2CAP:
+			pp := (*RawSockaddrL2)(unsafe.Pointer(rsa))
+			sa := &SockaddrL2{
+				PSM:      pp.Psm,
+				CID:      pp.Cid,
+				Addr:     pp.Bdaddr,
+				AddrType: pp.Bdaddr_type,
+			}
+			return sa, nil
+		case BTPROTO_RFCOMM:
+			pp := (*RawSockaddrRFCOMM)(unsafe.Pointer(rsa))
+			sa := &SockaddrRFCOMM{
+				Channel: pp.Channel,
+				Addr:    pp.Bdaddr,
+			}
+			return sa, nil
+		}
+	case AF_XDP:
+		pp := (*RawSockaddrXDP)(unsafe.Pointer(rsa))
+		sa := &SockaddrXDP{
+			Flags:        pp.Flags,
+			Ifindex:      pp.Ifindex,
+			QueueID:      pp.Queue_id,
+			SharedUmemFD: pp.Shared_umem_fd,
+		}
+		return sa, nil
+	case AF_PPPOX:
+		pp := (*RawSockaddrPPPoX)(unsafe.Pointer(rsa))
+		if binary.BigEndian.Uint32(pp[2:6]) != px_proto_oe {
+			return nil, EINVAL
+		}
+		sa := &SockaddrPPPoE{
+			SID:    binary.BigEndian.Uint16(pp[6:8]),
+			Remote: pp[8:14],
+		}
+		for i := 14; i < 14+IFNAMSIZ; i++ {
+			if pp[i] == 0 {
+				sa.Dev = string(pp[14:i])
+				break
+			}
+		}
+		return sa, nil
+	case AF_TIPC:
+		pp := (*RawSockaddrTIPC)(unsafe.Pointer(rsa))
+
+		sa := &SockaddrTIPC{
+			Scope: int(pp.Scope),
+		}
+
+		// Determine which union variant is present in pp.Addr by checking
+		// pp.Addrtype.
+		switch pp.Addrtype {
+		case TIPC_SERVICE_RANGE:
+			sa.Addr = (*TIPCServiceRange)(unsafe.Pointer(&pp.Addr))
+		case TIPC_SERVICE_ADDR:
+			sa.Addr = (*TIPCServiceName)(unsafe.Pointer(&pp.Addr))
+		case TIPC_SOCKET_ADDR:
+			sa.Addr = (*TIPCSocketAddr)(unsafe.Pointer(&pp.Addr))
+		default:
+			return nil, EINVAL
+		}
+
+		return sa, nil
+	}
+	return nil, EAFNOSUPPORT
+}
+
+func Accept(fd int) (nfd int, sa Sockaddr, err error) {
+	var rsa RawSockaddrAny
+	var len _Socklen = SizeofSockaddrAny
+	nfd, err = accept(fd, &rsa, &len)
+	if err != nil {
+		return
+	}
+	sa, err = anyToSockaddr(fd, &rsa)
+	if err != nil {
+		Close(nfd)
+		nfd = 0
+	}
+	return
+}
+
+func Accept4(fd int, flags int) (nfd int, sa Sockaddr, err error) {
+	var rsa RawSockaddrAny
+	var len _Socklen = SizeofSockaddrAny
+	nfd, err = accept4(fd, &rsa, &len, flags)
+	if err != nil {
+		return
+	}
+	if len > SizeofSockaddrAny {
+		panic("RawSockaddrAny too small")
+	}
+	sa, err = anyToSockaddr(fd, &rsa)
+	if err != nil {
+		Close(nfd)
+		nfd = 0
+	}
+	return
+}
+
+func Getsockname(fd int) (sa Sockaddr, err error) {
+	var rsa RawSockaddrAny
+	var len _Socklen = SizeofSockaddrAny
+	if err = getsockname(fd, &rsa, &len); err != nil {
+		return
+	}
+	return anyToSockaddr(fd, &rsa)
+}
+
+func GetsockoptIPMreqn(fd, level, opt int) (*IPMreqn, error) {
+	var value IPMreqn
+	vallen := _Socklen(SizeofIPMreqn)
+	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
+	return &value, err
+}
+
+func GetsockoptUcred(fd, level, opt int) (*Ucred, error) {
+	var value Ucred
+	vallen := _Socklen(SizeofUcred)
+	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
+	return &value, err
+}
+
+func GetsockoptTCPInfo(fd, level, opt int) (*TCPInfo, error) {
+	var value TCPInfo
+	vallen := _Socklen(SizeofTCPInfo)
+	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
+	return &value, err
+}
+
+// GetsockoptString returns the string value of the socket option opt for the
+// socket associated with fd at the given socket level.
+func GetsockoptString(fd, level, opt int) (string, error) {
+	buf := make([]byte, 256)
+	vallen := _Socklen(len(buf))
+	err := getsockopt(fd, level, opt, unsafe.Pointer(&buf[0]), &vallen)
+	if err != nil {
+		if err == ERANGE {
+			buf = make([]byte, vallen)
+			err = getsockopt(fd, level, opt, unsafe.Pointer(&buf[0]), &vallen)
+		}
+		if err != nil {
+			return "", err
+		}
+	}
+	return string(buf[:vallen-1]), nil
+}
+
+func GetsockoptTpacketStats(fd, level, opt int) (*TpacketStats, error) {
+	var value TpacketStats
+	vallen := _Socklen(SizeofTpacketStats)
+	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
+	return &value, err
+}
+
+func GetsockoptTpacketStatsV3(fd, level, opt int) (*TpacketStatsV3, error) {
+	var value TpacketStatsV3
+	vallen := _Socklen(SizeofTpacketStatsV3)
+	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
+	return &value, err
+}
+
+func SetsockoptIPMreqn(fd, level, opt int, mreq *IPMreqn) (err error) {
+	return setsockopt(fd, level, opt, unsafe.Pointer(mreq), unsafe.Sizeof(*mreq))
+}
+
+func SetsockoptPacketMreq(fd, level, opt int, mreq *PacketMreq) error {
+	return setsockopt(fd, level, opt, unsafe.Pointer(mreq), unsafe.Sizeof(*mreq))
+}
+
+// SetsockoptSockFprog attaches a classic BPF or an extended BPF program to a
+// socket to filter incoming packets.  See 'man 7 socket' for usage information.
+func SetsockoptSockFprog(fd, level, opt int, fprog *SockFprog) error {
+	return setsockopt(fd, level, opt, unsafe.Pointer(fprog), unsafe.Sizeof(*fprog))
+}
+
+func SetsockoptCanRawFilter(fd, level, opt int, filter []CanFilter) error {
+	var p unsafe.Pointer
+	if len(filter) > 0 {
+		p = unsafe.Pointer(&filter[0])
+	}
+	return setsockopt(fd, level, opt, p, uintptr(len(filter)*SizeofCanFilter))
+}
+
+func SetsockoptTpacketReq(fd, level, opt int, tp *TpacketReq) error {
+	return setsockopt(fd, level, opt, unsafe.Pointer(tp), unsafe.Sizeof(*tp))
+}
+
+func SetsockoptTpacketReq3(fd, level, opt int, tp *TpacketReq3) error {
+	return setsockopt(fd, level, opt, unsafe.Pointer(tp), unsafe.Sizeof(*tp))
+}
+
+// Keyctl Commands (http://man7.org/linux/man-pages/man2/keyctl.2.html)
+
+// KeyctlInt calls keyctl commands in which each argument is an int.
+// These commands are KEYCTL_REVOKE, KEYCTL_CHOWN, KEYCTL_CLEAR, KEYCTL_LINK,
+// KEYCTL_UNLINK, KEYCTL_NEGATE, KEYCTL_SET_REQKEY_KEYRING, KEYCTL_SET_TIMEOUT,
+// KEYCTL_ASSUME_AUTHORITY, KEYCTL_SESSION_TO_PARENT, KEYCTL_REJECT,
+// KEYCTL_INVALIDATE, and KEYCTL_GET_PERSISTENT.
+//sys	KeyctlInt(cmd int, arg2 int, arg3 int, arg4 int, arg5 int) (ret int, err error) = SYS_KEYCTL
+
+// KeyctlBuffer calls keyctl commands in which the third and fourth
+// arguments are a buffer and its length, respectively.
+// These commands are KEYCTL_UPDATE, KEYCTL_READ, and KEYCTL_INSTANTIATE.
+//sys	KeyctlBuffer(cmd int, arg2 int, buf []byte, arg5 int) (ret int, err error) = SYS_KEYCTL
+
+// KeyctlString calls keyctl commands which return a string.
+// These commands are KEYCTL_DESCRIBE and KEYCTL_GET_SECURITY.
+func KeyctlString(cmd int, id int) (string, error) {
+	// We must loop as the string data may change in between the syscalls.
+	// We could allocate a large buffer here to reduce the chance that the
+	// syscall needs to be called twice; however, this is unnecessary as
+	// the performance loss is negligible.
+	var buffer []byte
+	for {
+		// Try to fill the buffer with data
+		length, err := KeyctlBuffer(cmd, id, buffer, 0)
+		if err != nil {
+			return "", err
+		}
+
+		// Check if the data was written
+		if length <= len(buffer) {
+			// Exclude the null terminator
+			return string(buffer[:length-1]), nil
+		}
+
+		// Make a bigger buffer if needed
+		buffer = make([]byte, length)
+	}
+}
+
+// Keyctl commands with special signatures.
+
+// KeyctlGetKeyringID implements the KEYCTL_GET_KEYRING_ID command.
+// See the full documentation at:
+// http://man7.org/linux/man-pages/man3/keyctl_get_keyring_ID.3.html
+func KeyctlGetKeyringID(id int, create bool) (ringid int, err error) {
+	createInt := 0
+	if create {
+		createInt = 1
+	}
+	return KeyctlInt(KEYCTL_GET_KEYRING_ID, id, createInt, 0, 0)
+}
+
+// KeyctlSetperm implements the KEYCTL_SETPERM command. The perm value is the
+// key handle permission mask as described in the "keyctl setperm" section of
+// http://man7.org/linux/man-pages/man1/keyctl.1.html.
+// See the full documentation at:
+// http://man7.org/linux/man-pages/man3/keyctl_setperm.3.html
+func KeyctlSetperm(id int, perm uint32) error {
+	_, err := KeyctlInt(KEYCTL_SETPERM, id, int(perm), 0, 0)
+	return err
+}
+
+//sys	keyctlJoin(cmd int, arg2 string) (ret int, err error) = SYS_KEYCTL
+
+// KeyctlJoinSessionKeyring implements the KEYCTL_JOIN_SESSION_KEYRING command.
+// See the full documentation at:
+// http://man7.org/linux/man-pages/man3/keyctl_join_session_keyring.3.html
+func KeyctlJoinSessionKeyring(name string) (ringid int, err error) {
+	return keyctlJoin(KEYCTL_JOIN_SESSION_KEYRING, name)
+}
+
+//sys	keyctlSearch(cmd int, arg2 int, arg3 string, arg4 string, arg5 int) (ret int, err error) = SYS_KEYCTL
+
+// KeyctlSearch implements the KEYCTL_SEARCH command.
+// See the full documentation at:
+// http://man7.org/linux/man-pages/man3/keyctl_search.3.html
+func KeyctlSearch(ringid int, keyType, description string, destRingid int) (id int, err error) {
+	return keyctlSearch(KEYCTL_SEARCH, ringid, keyType, description, destRingid)
+}
+
+//sys	keyctlIOV(cmd int, arg2 int, payload []Iovec, arg5 int) (err error) = SYS_KEYCTL
+
+// KeyctlInstantiateIOV implements the KEYCTL_INSTANTIATE_IOV command. This
+// command is similar to KEYCTL_INSTANTIATE, except that the payload is a slice
+// of Iovec (each of which represents a buffer) instead of a single buffer.
+// See the full documentation at:
+// http://man7.org/linux/man-pages/man3/keyctl_instantiate_iov.3.html
+func KeyctlInstantiateIOV(id int, payload []Iovec, ringid int) error {
+	return keyctlIOV(KEYCTL_INSTANTIATE_IOV, id, payload, ringid)
+}
+
+//sys	keyctlDH(cmd int, arg2 *KeyctlDHParams, buf []byte) (ret int, err error) = SYS_KEYCTL
+
+// KeyctlDHCompute implements the KEYCTL_DH_COMPUTE command. This command
+// computes a Diffie-Hellman shared secret based on the provide params. The
+// secret is written to the provided buffer and the returned size is the number
+// of bytes written (returning an error if there is insufficient space in the
+// buffer). If a nil buffer is passed in, this function returns the minimum
+// buffer length needed to store the appropriate data. Note that this differs
+// from KEYCTL_READ's behavior which always returns the requested payload size.
+// See the full documentation at:
+// http://man7.org/linux/man-pages/man3/keyctl_dh_compute.3.html
+func KeyctlDHCompute(params *KeyctlDHParams, buffer []byte) (size int, err error) {
+	return keyctlDH(KEYCTL_DH_COMPUTE, params, buffer)
+}
+
+// KeyctlRestrictKeyring implements the KEYCTL_RESTRICT_KEYRING command. This
+// command limits the set of keys that can be linked to the keyring, regardless
+// of keyring permissions. The command requires the "setattr" permission.
+//
+// When called with an empty keyType the command locks the keyring, preventing
+// any further keys from being linked to the keyring.
+//
+// The "asymmetric" keyType defines restrictions requiring key payloads to be
+// DER encoded X.509 certificates signed by keys in another keyring. Restrictions
+// for "asymmetric" include "builtin_trusted", "builtin_and_secondary_trusted",
+// "key_or_keyring:<key>", and "key_or_keyring:<key>:chain".
+//
+// As of Linux 4.12, only the "asymmetric" keyType defines type-specific
+// restrictions.
+//
+// See the full documentation at:
+// http://man7.org/linux/man-pages/man3/keyctl_restrict_keyring.3.html
+// http://man7.org/linux/man-pages/man2/keyctl.2.html
+func KeyctlRestrictKeyring(ringid int, keyType string, restriction string) error {
+	if keyType == "" {
+		return keyctlRestrictKeyring(KEYCTL_RESTRICT_KEYRING, ringid)
+	}
+	return keyctlRestrictKeyringByType(KEYCTL_RESTRICT_KEYRING, ringid, keyType, restriction)
+}
+
+//sys keyctlRestrictKeyringByType(cmd int, arg2 int, keyType string, restriction string) (err error) = SYS_KEYCTL
+//sys keyctlRestrictKeyring(cmd int, arg2 int) (err error) = SYS_KEYCTL
+
+func Recvmsg(fd int, p, oob []byte, flags int) (n, oobn int, recvflags int, from Sockaddr, err error) {
+	var msg Msghdr
+	var rsa RawSockaddrAny
+	msg.Name = (*byte)(unsafe.Pointer(&rsa))
+	msg.Namelen = uint32(SizeofSockaddrAny)
+	var iov Iovec
+	if len(p) > 0 {
+		iov.Base = &p[0]
+		iov.SetLen(len(p))
+	}
+	var dummy byte
+	if len(oob) > 0 {
+		if len(p) == 0 {
+			var sockType int
+			sockType, err = GetsockoptInt(fd, SOL_SOCKET, SO_TYPE)
+			if err != nil {
+				return
+			}
+			// receive at least one normal byte
+			if sockType != SOCK_DGRAM {
+				iov.Base = &dummy
+				iov.SetLen(1)
+			}
+		}
+		msg.Control = &oob[0]
+		msg.SetControllen(len(oob))
+	}
+	msg.Iov = &iov
+	msg.Iovlen = 1
+	if n, err = recvmsg(fd, &msg, flags); err != nil {
+		return
+	}
+	oobn = int(msg.Controllen)
+	recvflags = int(msg.Flags)
+	// source address is only specified if the socket is unconnected
+	if rsa.Addr.Family != AF_UNSPEC {
+		from, err = anyToSockaddr(fd, &rsa)
+	}
+	return
+}
+
+func Sendmsg(fd int, p, oob []byte, to Sockaddr, flags int) (err error) {
+	_, err = SendmsgN(fd, p, oob, to, flags)
+	return
+}
+
+func SendmsgN(fd int, p, oob []byte, to Sockaddr, flags int) (n int, err error) {
+	var ptr unsafe.Pointer
+	var salen _Socklen
+	if to != nil {
+		var err error
+		ptr, salen, err = to.sockaddr()
+		if err != nil {
+			return 0, err
+		}
+	}
+	var msg Msghdr
+	msg.Name = (*byte)(ptr)
+	msg.Namelen = uint32(salen)
+	var iov Iovec
+	if len(p) > 0 {
+		iov.Base = &p[0]
+		iov.SetLen(len(p))
+	}
+	var dummy byte
+	if len(oob) > 0 {
+		if len(p) == 0 {
+			var sockType int
+			sockType, err = GetsockoptInt(fd, SOL_SOCKET, SO_TYPE)
+			if err != nil {
+				return 0, err
+			}
+			// send at least one normal byte
+			if sockType != SOCK_DGRAM {
+				iov.Base = &dummy
+				iov.SetLen(1)
+			}
+		}
+		msg.Control = &oob[0]
+		msg.SetControllen(len(oob))
+	}
+	msg.Iov = &iov
+	msg.Iovlen = 1
+	if n, err = sendmsg(fd, &msg, flags); err != nil {
+		return 0, err
+	}
+	if len(oob) > 0 && len(p) == 0 {
+		n = 0
+	}
+	return n, nil
+}
+
+// BindToDevice binds the socket associated with fd to device.
+func BindToDevice(fd int, device string) (err error) {
+	return SetsockoptString(fd, SOL_SOCKET, SO_BINDTODEVICE, device)
+}
+
+//sys	ptrace(request int, pid int, addr uintptr, data uintptr) (err error)
+
+func ptracePeek(req int, pid int, addr uintptr, out []byte) (count int, err error) {
+	// The peek requests are machine-size oriented, so we wrap it
+	// to retrieve arbitrary-length data.
+
+	// The ptrace syscall differs from glibc's ptrace.
+	// Peeks returns the word in *data, not as the return value.
+
+	var buf [SizeofPtr]byte
+
+	// Leading edge. PEEKTEXT/PEEKDATA don't require aligned
+	// access (PEEKUSER warns that it might), but if we don't
+	// align our reads, we might straddle an unmapped page
+	// boundary and not get the bytes leading up to the page
+	// boundary.
+	n := 0
+	if addr%SizeofPtr != 0 {
+		err = ptrace(req, pid, addr-addr%SizeofPtr, uintptr(unsafe.Pointer(&buf[0])))
+		if err != nil {
+			return 0, err
+		}
+		n += copy(out, buf[addr%SizeofPtr:])
+		out = out[n:]
+	}
+
+	// Remainder.
+	for len(out) > 0 {
+		// We use an internal buffer to guarantee alignment.
+		// It's not documented if this is necessary, but we're paranoid.
+		err = ptrace(req, pid, addr+uintptr(n), uintptr(unsafe.Pointer(&buf[0])))
+		if err != nil {
+			return n, err
+		}
+		copied := copy(out, buf[0:])
+		n += copied
+		out = out[copied:]
+	}
+
+	return n, nil
+}
+
+func PtracePeekText(pid int, addr uintptr, out []byte) (count int, err error) {
+	return ptracePeek(PTRACE_PEEKTEXT, pid, addr, out)
+}
+
+func PtracePeekData(pid int, addr uintptr, out []byte) (count int, err error) {
+	return ptracePeek(PTRACE_PEEKDATA, pid, addr, out)
+}
+
+func PtracePeekUser(pid int, addr uintptr, out []byte) (count int, err error) {
+	return ptracePeek(PTRACE_PEEKUSR, pid, addr, out)
+}
+
+func ptracePoke(pokeReq int, peekReq int, pid int, addr uintptr, data []byte) (count int, err error) {
+	// As for ptracePeek, we need to align our accesses to deal
+	// with the possibility of straddling an invalid page.
+
+	// Leading edge.
+	n := 0
+	if addr%SizeofPtr != 0 {
+		var buf [SizeofPtr]byte
+		err = ptrace(peekReq, pid, addr-addr%SizeofPtr, uintptr(unsafe.Pointer(&buf[0])))
+		if err != nil {
+			return 0, err
+		}
+		n += copy(buf[addr%SizeofPtr:], data)
+		word := *((*uintptr)(unsafe.Pointer(&buf[0])))
+		err = ptrace(pokeReq, pid, addr-addr%SizeofPtr, word)
+		if err != nil {
+			return 0, err
+		}
+		data = data[n:]
+	}
+
+	// Interior.
+	for len(data) > SizeofPtr {
+		word := *((*uintptr)(unsafe.Pointer(&data[0])))
+		err = ptrace(pokeReq, pid, addr+uintptr(n), word)
+		if err != nil {
+			return n, err
+		}
+		n += SizeofPtr
+		data = data[SizeofPtr:]
+	}
+
+	// Trailing edge.
+	if len(data) > 0 {
+		var buf [SizeofPtr]byte
+		err = ptrace(peekReq, pid, addr+uintptr(n), uintptr(unsafe.Pointer(&buf[0])))
+		if err != nil {
+			return n, err
+		}
+		copy(buf[0:], data)
+		word := *((*uintptr)(unsafe.Pointer(&buf[0])))
+		err = ptrace(pokeReq, pid, addr+uintptr(n), word)
+		if err != nil {
+			return n, err
+		}
+		n += len(data)
+	}
+
+	return n, nil
+}
+
+func PtracePokeText(pid int, addr uintptr, data []byte) (count int, err error) {
+	return ptracePoke(PTRACE_POKETEXT, PTRACE_PEEKTEXT, pid, addr, data)
+}
+
+func PtracePokeData(pid int, addr uintptr, data []byte) (count int, err error) {
+	return ptracePoke(PTRACE_POKEDATA, PTRACE_PEEKDATA, pid, addr, data)
+}
+
+func PtracePokeUser(pid int, addr uintptr, data []byte) (count int, err error) {
+	return ptracePoke(PTRACE_POKEUSR, PTRACE_PEEKUSR, pid, addr, data)
+}
+
+func PtraceGetRegs(pid int, regsout *PtraceRegs) (err error) {
+	return ptrace(PTRACE_GETREGS, pid, 0, uintptr(unsafe.Pointer(regsout)))
+}
+
+func PtraceSetRegs(pid int, regs *PtraceRegs) (err error) {
+	return ptrace(PTRACE_SETREGS, pid, 0, uintptr(unsafe.Pointer(regs)))
+}
+
+func PtraceSetOptions(pid int, options int) (err error) {
+	return ptrace(PTRACE_SETOPTIONS, pid, 0, uintptr(options))
+}
+
+func PtraceGetEventMsg(pid int) (msg uint, err error) {
+	var data _C_long
+	err = ptrace(PTRACE_GETEVENTMSG, pid, 0, uintptr(unsafe.Pointer(&data)))
+	msg = uint(data)
+	return
+}
+
+func PtraceCont(pid int, signal int) (err error) {
+	return ptrace(PTRACE_CONT, pid, 0, uintptr(signal))
+}
+
+func PtraceSyscall(pid int, signal int) (err error) {
+	return ptrace(PTRACE_SYSCALL, pid, 0, uintptr(signal))
+}
+
+func PtraceSingleStep(pid int) (err error) { return ptrace(PTRACE_SINGLESTEP, pid, 0, 0) }
+
+func PtraceInterrupt(pid int) (err error) { return ptrace(PTRACE_INTERRUPT, pid, 0, 0) }
+
+func PtraceAttach(pid int) (err error) { return ptrace(PTRACE_ATTACH, pid, 0, 0) }
+
+func PtraceSeize(pid int) (err error) { return ptrace(PTRACE_SEIZE, pid, 0, 0) }
+
+func PtraceDetach(pid int) (err error) { return ptrace(PTRACE_DETACH, pid, 0, 0) }
+
+//sys	reboot(magic1 uint, magic2 uint, cmd int, arg string) (err error)
+
+func Reboot(cmd int) (err error) {
+	return reboot(LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2, cmd, "")
+}
+
+func direntIno(buf []byte) (uint64, bool) {
+	return readInt(buf, unsafe.Offsetof(Dirent{}.Ino), unsafe.Sizeof(Dirent{}.Ino))
+}
+
+func direntReclen(buf []byte) (uint64, bool) {
+	return readInt(buf, unsafe.Offsetof(Dirent{}.Reclen), unsafe.Sizeof(Dirent{}.Reclen))
+}
+
+func direntNamlen(buf []byte) (uint64, bool) {
+	reclen, ok := direntReclen(buf)
+	if !ok {
+		return 0, false
+	}
+	return reclen - uint64(unsafe.Offsetof(Dirent{}.Name)), true
+}
+
+//sys	mount(source string, target string, fstype string, flags uintptr, data *byte) (err error)
+
+func Mount(source string, target string, fstype string, flags uintptr, data string) (err error) {
+	// Certain file systems get rather angry and EINVAL if you give
+	// them an empty string of data, rather than NULL.
+	if data == "" {
+		return mount(source, target, fstype, flags, nil)
+	}
+	datap, err := BytePtrFromString(data)
+	if err != nil {
+		return err
+	}
+	return mount(source, target, fstype, flags, datap)
+}
+
+func Sendfile(outfd int, infd int, offset *int64, count int) (written int, err error) {
+	if raceenabled {
+		raceReleaseMerge(unsafe.Pointer(&ioSync))
+	}
+	return sendfile(outfd, infd, offset, count)
+}
+
+// Sendto
+// Recvfrom
+// Socketpair
+
+/*
+ * Direct access
+ */
+//sys	Acct(path string) (err error)
+//sys	AddKey(keyType string, description string, payload []byte, ringid int) (id int, err error)
+//sys	Adjtimex(buf *Timex) (state int, err error)
+//sysnb	Capget(hdr *CapUserHeader, data *CapUserData) (err error)
+//sysnb	Capset(hdr *CapUserHeader, data *CapUserData) (err error)
+//sys	Chdir(path string) (err error)
+//sys	Chroot(path string) (err error)
+//sys	ClockGetres(clockid int32, res *Timespec) (err error)
+//sys	ClockGettime(clockid int32, time *Timespec) (err error)
+//sys	ClockNanosleep(clockid int32, flags int, request *Timespec, remain *Timespec) (err error)
+//sys	Close(fd int) (err error)
+//sys	CopyFileRange(rfd int, roff *int64, wfd int, woff *int64, len int, flags int) (n int, err error)
+//sys	DeleteModule(name string, flags int) (err error)
+//sys	Dup(oldfd int) (fd int, err error)
+
+func Dup2(oldfd, newfd int) error {
+	// Android O and newer blocks dup2; riscv and arm64 don't implement dup2.
+	if runtime.GOOS == "android" || runtime.GOARCH == "riscv64" || runtime.GOARCH == "arm64" {
+		return Dup3(oldfd, newfd, 0)
+	}
+	return dup2(oldfd, newfd)
+}
+
+//sys	Dup3(oldfd int, newfd int, flags int) (err error)
+//sysnb	EpollCreate1(flag int) (fd int, err error)
+//sysnb	EpollCtl(epfd int, op int, fd int, event *EpollEvent) (err error)
+//sys	Eventfd(initval uint, flags int) (fd int, err error) = SYS_EVENTFD2
+//sys	Exit(code int) = SYS_EXIT_GROUP
+//sys	Fallocate(fd int, mode uint32, off int64, len int64) (err error)
+//sys	Fchdir(fd int) (err error)
+//sys	Fchmod(fd int, mode uint32) (err error)
+//sys	Fchownat(dirfd int, path string, uid int, gid int, flags int) (err error)
+//sys	Fdatasync(fd int) (err error)
+//sys	Fgetxattr(fd int, attr string, dest []byte) (sz int, err error)
+//sys	FinitModule(fd int, params string, flags int) (err error)
+//sys	Flistxattr(fd int, dest []byte) (sz int, err error)
+//sys	Flock(fd int, how int) (err error)
+//sys	Fremovexattr(fd int, attr string) (err error)
+//sys	Fsetxattr(fd int, attr string, dest []byte, flags int) (err error)
+//sys	Fsync(fd int) (err error)
+//sys	Getdents(fd int, buf []byte) (n int, err error) = SYS_GETDENTS64
+//sysnb	Getpgid(pid int) (pgid int, err error)
+
+func Getpgrp() (pid int) {
+	pid, _ = Getpgid(0)
+	return
+}
+
+//sysnb	Getpid() (pid int)
+//sysnb	Getppid() (ppid int)
+//sys	Getpriority(which int, who int) (prio int, err error)
+//sys	Getrandom(buf []byte, flags int) (n int, err error)
+//sysnb	Getrusage(who int, rusage *Rusage) (err error)
+//sysnb	Getsid(pid int) (sid int, err error)
+//sysnb	Gettid() (tid int)
+//sys	Getxattr(path string, attr string, dest []byte) (sz int, err error)
+//sys	InitModule(moduleImage []byte, params string) (err error)
+//sys	InotifyAddWatch(fd int, pathname string, mask uint32) (watchdesc int, err error)
+//sysnb	InotifyInit1(flags int) (fd int, err error)
+//sysnb	InotifyRmWatch(fd int, watchdesc uint32) (success int, err error)
+//sysnb	Kill(pid int, sig syscall.Signal) (err error)
+//sys	Klogctl(typ int, buf []byte) (n int, err error) = SYS_SYSLOG
+//sys	Lgetxattr(path string, attr string, dest []byte) (sz int, err error)
+//sys	Listxattr(path string, dest []byte) (sz int, err error)
+//sys	Llistxattr(path string, dest []byte) (sz int, err error)
+//sys	Lremovexattr(path string, attr string) (err error)
+//sys	Lsetxattr(path string, attr string, data []byte, flags int) (err error)
+//sys	MemfdCreate(name string, flags int) (fd int, err error)
+//sys	Mkdirat(dirfd int, path string, mode uint32) (err error)
+//sys	Mknodat(dirfd int, path string, mode uint32, dev int) (err error)
+//sys	Nanosleep(time *Timespec, leftover *Timespec) (err error)
+//sys	PerfEventOpen(attr *PerfEventAttr, pid int, cpu int, groupFd int, flags int) (fd int, err error)
+//sys	PivotRoot(newroot string, putold string) (err error) = SYS_PIVOT_ROOT
+//sysnb prlimit(pid int, resource int, newlimit *Rlimit, old *Rlimit) (err error) = SYS_PRLIMIT64
+//sys   Prctl(option int, arg2 uintptr, arg3 uintptr, arg4 uintptr, arg5 uintptr) (err error)
+//sys	Pselect(nfd int, r *FdSet, w *FdSet, e *FdSet, timeout *Timespec, sigmask *Sigset_t) (n int, err error) = SYS_PSELECT6
+//sys	read(fd int, p []byte) (n int, err error)
+//sys	Removexattr(path string, attr string) (err error)
+//sys	Renameat2(olddirfd int, oldpath string, newdirfd int, newpath string, flags uint) (err error)
+//sys	RequestKey(keyType string, description string, callback string, destRingid int) (id int, err error)
+//sys	Setdomainname(p []byte) (err error)
+//sys	Sethostname(p []byte) (err error)
+//sysnb	Setpgid(pid int, pgid int) (err error)
+//sysnb	Setsid() (pid int, err error)
+//sysnb	Settimeofday(tv *Timeval) (err error)
+//sys	Setns(fd int, nstype int) (err error)
+
+// PrctlRetInt performs a prctl operation specified by option and further
+// optional arguments arg2 through arg5 depending on option. It returns a
+// non-negative integer that is returned by the prctl syscall.
+func PrctlRetInt(option int, arg2 uintptr, arg3 uintptr, arg4 uintptr, arg5 uintptr) (int, error) {
+	ret, _, err := Syscall6(SYS_PRCTL, uintptr(option), uintptr(arg2), uintptr(arg3), uintptr(arg4), uintptr(arg5), 0)
+	if err != 0 {
+		return 0, err
+	}
+	return int(ret), nil
+}
+
+// issue 1435.
+// On linux Setuid and Setgid only affects the current thread, not the process.
+// This does not match what most callers expect so we must return an error
+// here rather than letting the caller think that the call succeeded.
+
+func Setuid(uid int) (err error) {
+	return EOPNOTSUPP
+}
+
+func Setgid(uid int) (err error) {
+	return EOPNOTSUPP
+}
+
+// SetfsgidRetGid sets fsgid for current thread and returns previous fsgid set.
+// setfsgid(2) will return a non-nil error only if its caller lacks CAP_SETUID capability.
+// If the call fails due to other reasons, current fsgid will be returned.
+func SetfsgidRetGid(gid int) (int, error) {
+	return setfsgid(gid)
+}
+
+// SetfsuidRetUid sets fsuid for current thread and returns previous fsuid set.
+// setfsgid(2) will return a non-nil error only if its caller lacks CAP_SETUID capability
+// If the call fails due to other reasons, current fsuid will be returned.
+func SetfsuidRetUid(uid int) (int, error) {
+	return setfsuid(uid)
+}
+
+func Setfsgid(gid int) error {
+	_, err := setfsgid(gid)
+	return err
+}
+
+func Setfsuid(uid int) error {
+	_, err := setfsuid(uid)
+	return err
+}
+
+func Signalfd(fd int, sigmask *Sigset_t, flags int) (newfd int, err error) {
+	return signalfd(fd, sigmask, _C__NSIG/8, flags)
+}
+
+//sys	Setpriority(which int, who int, prio int) (err error)
+//sys	Setxattr(path string, attr string, data []byte, flags int) (err error)
+//sys	signalfd(fd int, sigmask *Sigset_t, maskSize uintptr, flags int) (newfd int, err error) = SYS_SIGNALFD4
+//sys	Statx(dirfd int, path string, flags int, mask int, stat *Statx_t) (err error)
+//sys	Sync()
+//sys	Syncfs(fd int) (err error)
+//sysnb	Sysinfo(info *Sysinfo_t) (err error)
+//sys	Tee(rfd int, wfd int, len int, flags int) (n int64, err error)
+//sysnb TimerfdCreate(clockid int, flags int) (fd int, err error)
+//sysnb TimerfdGettime(fd int, currValue *ItimerSpec) (err error)
+//sysnb TimerfdSettime(fd int, flags int, newValue *ItimerSpec, oldValue *ItimerSpec) (err error)
+//sysnb	Tgkill(tgid int, tid int, sig syscall.Signal) (err error)
+//sysnb	Times(tms *Tms) (ticks uintptr, err error)
+//sysnb	Umask(mask int) (oldmask int)
+//sysnb	Uname(buf *Utsname) (err error)
+//sys	Unmount(target string, flags int) (err error) = SYS_UMOUNT2
+//sys	Unshare(flags int) (err error)
+//sys	write(fd int, p []byte) (n int, err error)
+//sys	exitThread(code int) (err error) = SYS_EXIT
+//sys	readlen(fd int, p *byte, np int) (n int, err error) = SYS_READ
+//sys	writelen(fd int, p *byte, np int) (n int, err error) = SYS_WRITE
+//sys	readv(fd int, iovs []Iovec) (n int, err error) = SYS_READV
+//sys	writev(fd int, iovs []Iovec) (n int, err error) = SYS_WRITEV
+//sys	preadv(fd int, iovs []Iovec, offs_l uintptr, offs_h uintptr) (n int, err error) = SYS_PREADV
+//sys	pwritev(fd int, iovs []Iovec, offs_l uintptr, offs_h uintptr) (n int, err error) = SYS_PWRITEV
+//sys	preadv2(fd int, iovs []Iovec, offs_l uintptr, offs_h uintptr, flags int) (n int, err error) = SYS_PREADV2
+//sys	pwritev2(fd int, iovs []Iovec, offs_l uintptr, offs_h uintptr, flags int) (n int, err error) = SYS_PWRITEV2
+
+func bytes2iovec(bs [][]byte) []Iovec {
+	iovecs := make([]Iovec, len(bs))
+	for i, b := range bs {
+		iovecs[i].SetLen(len(b))
+		if len(b) > 0 {
+			iovecs[i].Base = &b[0]
+		} else {
+			iovecs[i].Base = (*byte)(unsafe.Pointer(&_zero))
+		}
+	}
+	return iovecs
+}
+
+// offs2lohi splits offs into its lower and upper unsigned long. On 64-bit
+// systems, hi will always be 0. On 32-bit systems, offs will be split in half.
+// preadv/pwritev chose this calling convention so they don't need to add a
+// padding-register for alignment on ARM.
+func offs2lohi(offs int64) (lo, hi uintptr) {
+	return uintptr(offs), uintptr(uint64(offs) >> SizeofLong)
+}
+
+func Readv(fd int, iovs [][]byte) (n int, err error) {
+	iovecs := bytes2iovec(iovs)
+	n, err = readv(fd, iovecs)
+	readvRacedetect(iovecs, n, err)
+	return n, err
+}
+
+func Preadv(fd int, iovs [][]byte, offset int64) (n int, err error) {
+	iovecs := bytes2iovec(iovs)
+	lo, hi := offs2lohi(offset)
+	n, err = preadv(fd, iovecs, lo, hi)
+	readvRacedetect(iovecs, n, err)
+	return n, err
+}
+
+func Preadv2(fd int, iovs [][]byte, offset int64, flags int) (n int, err error) {
+	iovecs := bytes2iovec(iovs)
+	lo, hi := offs2lohi(offset)
+	n, err = preadv2(fd, iovecs, lo, hi, flags)
+	readvRacedetect(iovecs, n, err)
+	return n, err
+}
+
+func readvRacedetect(iovecs []Iovec, n int, err error) {
+	if !raceenabled {
+		return
+	}
+	for i := 0; n > 0 && i < len(iovecs); i++ {
+		m := int(iovecs[i].Len)
+		if m > n {
+			m = n
+		}
+		n -= m
+		if m > 0 {
+			raceWriteRange(unsafe.Pointer(iovecs[i].Base), m)
+		}
+	}
+	if err == nil {
+		raceAcquire(unsafe.Pointer(&ioSync))
+	}
+}
+
+func Writev(fd int, iovs [][]byte) (n int, err error) {
+	iovecs := bytes2iovec(iovs)
+	if raceenabled {
+		raceReleaseMerge(unsafe.Pointer(&ioSync))
+	}
+	n, err = writev(fd, iovecs)
+	writevRacedetect(iovecs, n)
+	return n, err
+}
+
+func Pwritev(fd int, iovs [][]byte, offset int64) (n int, err error) {
+	iovecs := bytes2iovec(iovs)
+	if raceenabled {
+		raceReleaseMerge(unsafe.Pointer(&ioSync))
+	}
+	lo, hi := offs2lohi(offset)
+	n, err = pwritev(fd, iovecs, lo, hi)
+	writevRacedetect(iovecs, n)
+	return n, err
+}
+
+func Pwritev2(fd int, iovs [][]byte, offset int64, flags int) (n int, err error) {
+	iovecs := bytes2iovec(iovs)
+	if raceenabled {
+		raceReleaseMerge(unsafe.Pointer(&ioSync))
+	}
+	lo, hi := offs2lohi(offset)
+	n, err = pwritev2(fd, iovecs, lo, hi, flags)
+	writevRacedetect(iovecs, n)
+	return n, err
+}
+
+func writevRacedetect(iovecs []Iovec, n int) {
+	if !raceenabled {
+		return
+	}
+	for i := 0; n > 0 && i < len(iovecs); i++ {
+		m := int(iovecs[i].Len)
+		if m > n {
+			m = n
+		}
+		n -= m
+		if m > 0 {
+			raceReadRange(unsafe.Pointer(iovecs[i].Base), m)
+		}
+	}
+}
+
+// mmap varies by architecture; see syscall_linux_*.go.
+//sys	munmap(addr uintptr, length uintptr) (err error)
+
+var mapper = &mmapper{
+	active: make(map[*byte][]byte),
+	mmap:   mmap,
+	munmap: munmap,
+}
+
+func Mmap(fd int, offset int64, length int, prot int, flags int) (data []byte, err error) {
+	return mapper.Mmap(fd, offset, length, prot, flags)
+}
+
+func Munmap(b []byte) (err error) {
+	return mapper.Munmap(b)
+}
+
+//sys	Madvise(b []byte, advice int) (err error)
+//sys	Mprotect(b []byte, prot int) (err error)
+//sys	Mlock(b []byte) (err error)
+//sys	Mlockall(flags int) (err error)
+//sys	Msync(b []byte, flags int) (err error)
+//sys	Munlock(b []byte) (err error)
+//sys	Munlockall() (err error)
+
+// Vmsplice splices user pages from a slice of Iovecs into a pipe specified by fd,
+// using the specified flags.
+func Vmsplice(fd int, iovs []Iovec, flags int) (int, error) {
+	var p unsafe.Pointer
+	if len(iovs) > 0 {
+		p = unsafe.Pointer(&iovs[0])
+	}
+
+	n, _, errno := Syscall6(SYS_VMSPLICE, uintptr(fd), uintptr(p), uintptr(len(iovs)), uintptr(flags), 0, 0)
+	if errno != 0 {
+		return 0, syscall.Errno(errno)
+	}
+
+	return int(n), nil
+}
+
+func isGroupMember(gid int) bool {
+	groups, err := Getgroups()
+	if err != nil {
+		return false
+	}
+
+	for _, g := range groups {
+		if g == gid {
+			return true
+		}
+	}
+	return false
+}
+
+//sys	faccessat(dirfd int, path string, mode uint32) (err error)
+
+func Faccessat(dirfd int, path string, mode uint32, flags int) (err error) {
+	if flags & ^(AT_SYMLINK_NOFOLLOW|AT_EACCESS) != 0 {
+		return EINVAL
+	}
+
+	// The Linux kernel faccessat system call does not take any flags.
+	// The glibc faccessat implements the flags itself; see
+	// https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/unix/sysv/linux/faccessat.c;hb=HEAD
+	// Because people naturally expect syscall.Faccessat to act
+	// like C faccessat, we do the same.
+
+	if flags == 0 {
+		return faccessat(dirfd, path, mode)
+	}
+
+	var st Stat_t
+	if err := Fstatat(dirfd, path, &st, flags&AT_SYMLINK_NOFOLLOW); err != nil {
+		return err
+	}
+
+	mode &= 7
+	if mode == 0 {
+		return nil
+	}
+
+	var uid int
+	if flags&AT_EACCESS != 0 {
+		uid = Geteuid()
+	} else {
+		uid = Getuid()
+	}
+
+	if uid == 0 {
+		if mode&1 == 0 {
+			// Root can read and write any file.
+			return nil
+		}
+		if st.Mode&0111 != 0 {
+			// Root can execute any file that anybody can execute.
+			return nil
+		}
+		return EACCES
+	}
+
+	var fmode uint32
+	if uint32(uid) == st.Uid {
+		fmode = (st.Mode >> 6) & 7
+	} else {
+		var gid int
+		if flags&AT_EACCESS != 0 {
+			gid = Getegid()
+		} else {
+			gid = Getgid()
+		}
+
+		if uint32(gid) == st.Gid || isGroupMember(gid) {
+			fmode = (st.Mode >> 3) & 7
+		} else {
+			fmode = st.Mode & 7
+		}
+	}
+
+	if fmode&mode == mode {
+		return nil
+	}
+
+	return EACCES
+}
+
+//sys nameToHandleAt(dirFD int, pathname string, fh *fileHandle, mountID *_C_int, flags int) (err error) = SYS_NAME_TO_HANDLE_AT
+//sys openByHandleAt(mountFD int, fh *fileHandle, flags int) (fd int, err error) = SYS_OPEN_BY_HANDLE_AT
+
+// fileHandle is the argument to nameToHandleAt and openByHandleAt. We
+// originally tried to generate it via unix/linux/types.go with "type
+// fileHandle C.struct_file_handle" but that generated empty structs
+// for mips64 and mips64le. Instead, hard code it for now (it's the
+// same everywhere else) until the mips64 generator issue is fixed.
+type fileHandle struct {
+	Bytes uint32
+	Type  int32
+}
+
+// FileHandle represents the C struct file_handle used by
+// name_to_handle_at (see NameToHandleAt) and open_by_handle_at (see
+// OpenByHandleAt).
+type FileHandle struct {
+	*fileHandle
+}
+
+// NewFileHandle constructs a FileHandle.
+func NewFileHandle(handleType int32, handle []byte) FileHandle {
+	const hdrSize = unsafe.Sizeof(fileHandle{})
+	buf := make([]byte, hdrSize+uintptr(len(handle)))
+	copy(buf[hdrSize:], handle)
+	fh := (*fileHandle)(unsafe.Pointer(&buf[0]))
+	fh.Type = handleType
+	fh.Bytes = uint32(len(handle))
+	return FileHandle{fh}
+}
+
+func (fh *FileHandle) Size() int   { return int(fh.fileHandle.Bytes) }
+func (fh *FileHandle) Type() int32 { return fh.fileHandle.Type }
+func (fh *FileHandle) Bytes() []byte {
+	n := fh.Size()
+	if n == 0 {
+		return nil
+	}
+	return (*[1 << 30]byte)(unsafe.Pointer(uintptr(unsafe.Pointer(&fh.fileHandle.Type)) + 4))[:n:n]
+}
+
+// NameToHandleAt wraps the name_to_handle_at system call; it obtains
+// a handle for a path name.
+func NameToHandleAt(dirfd int, path string, flags int) (handle FileHandle, mountID int, err error) {
+	var mid _C_int
+	// Try first with a small buffer, assuming the handle will
+	// only be 32 bytes.
+	size := uint32(32 + unsafe.Sizeof(fileHandle{}))
+	didResize := false
+	for {
+		buf := make([]byte, size)
+		fh := (*fileHandle)(unsafe.Pointer(&buf[0]))
+		fh.Bytes = size - uint32(unsafe.Sizeof(fileHandle{}))
+		err = nameToHandleAt(dirfd, path, fh, &mid, flags)
+		if err == EOVERFLOW {
+			if didResize {
+				// We shouldn't need to resize more than once
+				return
+			}
+			didResize = true
+			size = fh.Bytes + uint32(unsafe.Sizeof(fileHandle{}))
+			continue
+		}
+		if err != nil {
+			return
+		}
+		return FileHandle{fh}, int(mid), nil
+	}
+}
+
+// OpenByHandleAt wraps the open_by_handle_at system call; it opens a
+// file via a handle as previously returned by NameToHandleAt.
+func OpenByHandleAt(mountFD int, handle FileHandle, flags int) (fd int, err error) {
+	return openByHandleAt(mountFD, handle.fileHandle, flags)
+}
+
+// Klogset wraps the sys_syslog system call; it sets console_loglevel to
+// the value specified by arg and passes a dummy pointer to bufp.
+func Klogset(typ int, arg int) (err error) {
+	var p unsafe.Pointer
+	_, _, errno := Syscall(SYS_SYSLOG, uintptr(typ), uintptr(p), uintptr(arg))
+	if errno != 0 {
+		return errnoErr(errno)
+	}
+	return nil
+}
+
+/*
+ * Unimplemented
+ */
+// AfsSyscall
+// Alarm
+// ArchPrctl
+// Brk
+// ClockNanosleep
+// ClockSettime
+// Clone
+// EpollCtlOld
+// EpollPwait
+// EpollWaitOld
+// Execve
+// Fork
+// Futex
+// GetKernelSyms
+// GetMempolicy
+// GetRobustList
+// GetThreadArea
+// Getitimer
+// Getpmsg
+// IoCancel
+// IoDestroy
+// IoGetevents
+// IoSetup
+// IoSubmit
+// IoprioGet
+// IoprioSet
+// KexecLoad
+// LookupDcookie
+// Mbind
+// MigratePages
+// Mincore
+// ModifyLdt
+// Mount
+// MovePages
+// MqGetsetattr
+// MqNotify
+// MqOpen
+// MqTimedreceive
+// MqTimedsend
+// MqUnlink
+// Mremap
+// Msgctl
+// Msgget
+// Msgrcv
+// Msgsnd
+// Nfsservctl
+// Personality
+// Pselect6
+// Ptrace
+// Putpmsg
+// Quotactl
+// Readahead
+// Readv
+// RemapFilePages
+// RestartSyscall
+// RtSigaction
+// RtSigpending
+// RtSigprocmask
+// RtSigqueueinfo
+// RtSigreturn
+// RtSigsuspend
+// RtSigtimedwait
+// SchedGetPriorityMax
+// SchedGetPriorityMin
+// SchedGetparam
+// SchedGetscheduler
+// SchedRrGetInterval
+// SchedSetparam
+// SchedYield
+// Security
+// Semctl
+// Semget
+// Semop
+// Semtimedop
+// SetMempolicy
+// SetRobustList
+// SetThreadArea
+// SetTidAddress
+// Shmat
+// Shmctl
+// Shmdt
+// Shmget
+// Sigaltstack
+// Swapoff
+// Swapon
+// Sysfs
+// TimerCreate
+// TimerDelete
+// TimerGetoverrun
+// TimerGettime
+// TimerSettime
+// Tkill (obsolete)
+// Tuxcall
+// Umount2
+// Uselib
+// Utimensat
+// Vfork
+// Vhangup
+// Vserver
+// Waitid
+// _Sysctl