Source file src/pkg/cmd/vendor/golang.org/x/sys/unix/syscall_linux.go

     1	// Copyright 2009 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	// Linux system calls.
     6	// This file is compiled as ordinary Go code,
     7	// but it is also input to mksyscall,
     8	// which parses the //sys lines and generates system call stubs.
     9	// Note that sometimes we use a lowercase //sys name and
    10	// wrap it in our own nicer implementation.
    11	
    12	package unix
    13	
    14	import (
    15		"encoding/binary"
    16		"net"
    17		"runtime"
    18		"syscall"
    19		"unsafe"
    20	)
    21	
    22	/*
    23	 * Wrapped
    24	 */
    25	
    26	func Access(path string, mode uint32) (err error) {
    27		return Faccessat(AT_FDCWD, path, mode, 0)
    28	}
    29	
    30	func Chmod(path string, mode uint32) (err error) {
    31		return Fchmodat(AT_FDCWD, path, mode, 0)
    32	}
    33	
    34	func Chown(path string, uid int, gid int) (err error) {
    35		return Fchownat(AT_FDCWD, path, uid, gid, 0)
    36	}
    37	
    38	func Creat(path string, mode uint32) (fd int, err error) {
    39		return Open(path, O_CREAT|O_WRONLY|O_TRUNC, mode)
    40	}
    41	
    42	//sys	FanotifyInit(flags uint, event_f_flags uint) (fd int, err error)
    43	//sys	fanotifyMark(fd int, flags uint, mask uint64, dirFd int, pathname *byte) (err error)
    44	
    45	func FanotifyMark(fd int, flags uint, mask uint64, dirFd int, pathname string) (err error) {
    46		if pathname == "" {
    47			return fanotifyMark(fd, flags, mask, dirFd, nil)
    48		}
    49		p, err := BytePtrFromString(pathname)
    50		if err != nil {
    51			return err
    52		}
    53		return fanotifyMark(fd, flags, mask, dirFd, p)
    54	}
    55	
    56	//sys	fchmodat(dirfd int, path string, mode uint32) (err error)
    57	
    58	func Fchmodat(dirfd int, path string, mode uint32, flags int) (err error) {
    59		// Linux fchmodat doesn't support the flags parameter. Mimick glibc's behavior
    60		// and check the flags. Otherwise the mode would be applied to the symlink
    61		// destination which is not what the user expects.
    62		if flags&^AT_SYMLINK_NOFOLLOW != 0 {
    63			return EINVAL
    64		} else if flags&AT_SYMLINK_NOFOLLOW != 0 {
    65			return EOPNOTSUPP
    66		}
    67		return fchmodat(dirfd, path, mode)
    68	}
    69	
    70	//sys	ioctl(fd int, req uint, arg uintptr) (err error)
    71	
    72	// ioctl itself should not be exposed directly, but additional get/set
    73	// functions for specific types are permissible.
    74	
    75	// IoctlSetPointerInt performs an ioctl operation which sets an
    76	// integer value on fd, using the specified request number. The ioctl
    77	// argument is called with a pointer to the integer value, rather than
    78	// passing the integer value directly.
    79	func IoctlSetPointerInt(fd int, req uint, value int) error {
    80		v := int32(value)
    81		return ioctl(fd, req, uintptr(unsafe.Pointer(&v)))
    82	}
    83	
    84	// IoctlSetInt performs an ioctl operation which sets an integer value
    85	// on fd, using the specified request number.
    86	func IoctlSetInt(fd int, req uint, value int) error {
    87		return ioctl(fd, req, uintptr(value))
    88	}
    89	
    90	func ioctlSetWinsize(fd int, req uint, value *Winsize) error {
    91		return ioctl(fd, req, uintptr(unsafe.Pointer(value)))
    92	}
    93	
    94	func ioctlSetTermios(fd int, req uint, value *Termios) error {
    95		return ioctl(fd, req, uintptr(unsafe.Pointer(value)))
    96	}
    97	
    98	func IoctlSetRTCTime(fd int, value *RTCTime) error {
    99		err := ioctl(fd, RTC_SET_TIME, uintptr(unsafe.Pointer(value)))
   100		runtime.KeepAlive(value)
   101		return err
   102	}
   103	
   104	// IoctlGetInt performs an ioctl operation which gets an integer value
   105	// from fd, using the specified request number.
   106	func IoctlGetInt(fd int, req uint) (int, error) {
   107		var value int
   108		err := ioctl(fd, req, uintptr(unsafe.Pointer(&value)))
   109		return value, err
   110	}
   111	
   112	func IoctlGetWinsize(fd int, req uint) (*Winsize, error) {
   113		var value Winsize
   114		err := ioctl(fd, req, uintptr(unsafe.Pointer(&value)))
   115		return &value, err
   116	}
   117	
   118	func IoctlGetTermios(fd int, req uint) (*Termios, error) {
   119		var value Termios
   120		err := ioctl(fd, req, uintptr(unsafe.Pointer(&value)))
   121		return &value, err
   122	}
   123	
   124	func IoctlGetRTCTime(fd int) (*RTCTime, error) {
   125		var value RTCTime
   126		err := ioctl(fd, RTC_RD_TIME, uintptr(unsafe.Pointer(&value)))
   127		return &value, err
   128	}
   129	
   130	//sys	Linkat(olddirfd int, oldpath string, newdirfd int, newpath string, flags int) (err error)
   131	
   132	func Link(oldpath string, newpath string) (err error) {
   133		return Linkat(AT_FDCWD, oldpath, AT_FDCWD, newpath, 0)
   134	}
   135	
   136	func Mkdir(path string, mode uint32) (err error) {
   137		return Mkdirat(AT_FDCWD, path, mode)
   138	}
   139	
   140	func Mknod(path string, mode uint32, dev int) (err error) {
   141		return Mknodat(AT_FDCWD, path, mode, dev)
   142	}
   143	
   144	func Open(path string, mode int, perm uint32) (fd int, err error) {
   145		return openat(AT_FDCWD, path, mode|O_LARGEFILE, perm)
   146	}
   147	
   148	//sys	openat(dirfd int, path string, flags int, mode uint32) (fd int, err error)
   149	
   150	func Openat(dirfd int, path string, flags int, mode uint32) (fd int, err error) {
   151		return openat(dirfd, path, flags|O_LARGEFILE, mode)
   152	}
   153	
   154	//sys	ppoll(fds *PollFd, nfds int, timeout *Timespec, sigmask *Sigset_t) (n int, err error)
   155	
   156	func Ppoll(fds []PollFd, timeout *Timespec, sigmask *Sigset_t) (n int, err error) {
   157		if len(fds) == 0 {
   158			return ppoll(nil, 0, timeout, sigmask)
   159		}
   160		return ppoll(&fds[0], len(fds), timeout, sigmask)
   161	}
   162	
   163	//sys	Readlinkat(dirfd int, path string, buf []byte) (n int, err error)
   164	
   165	func Readlink(path string, buf []byte) (n int, err error) {
   166		return Readlinkat(AT_FDCWD, path, buf)
   167	}
   168	
   169	func Rename(oldpath string, newpath string) (err error) {
   170		return Renameat(AT_FDCWD, oldpath, AT_FDCWD, newpath)
   171	}
   172	
   173	func Rmdir(path string) error {
   174		return Unlinkat(AT_FDCWD, path, AT_REMOVEDIR)
   175	}
   176	
   177	//sys	Symlinkat(oldpath string, newdirfd int, newpath string) (err error)
   178	
   179	func Symlink(oldpath string, newpath string) (err error) {
   180		return Symlinkat(oldpath, AT_FDCWD, newpath)
   181	}
   182	
   183	func Unlink(path string) error {
   184		return Unlinkat(AT_FDCWD, path, 0)
   185	}
   186	
   187	//sys	Unlinkat(dirfd int, path string, flags int) (err error)
   188	
   189	func Utimes(path string, tv []Timeval) error {
   190		if tv == nil {
   191			err := utimensat(AT_FDCWD, path, nil, 0)
   192			if err != ENOSYS {
   193				return err
   194			}
   195			return utimes(path, nil)
   196		}
   197		if len(tv) != 2 {
   198			return EINVAL
   199		}
   200		var ts [2]Timespec
   201		ts[0] = NsecToTimespec(TimevalToNsec(tv[0]))
   202		ts[1] = NsecToTimespec(TimevalToNsec(tv[1]))
   203		err := utimensat(AT_FDCWD, path, (*[2]Timespec)(unsafe.Pointer(&ts[0])), 0)
   204		if err != ENOSYS {
   205			return err
   206		}
   207		return utimes(path, (*[2]Timeval)(unsafe.Pointer(&tv[0])))
   208	}
   209	
   210	//sys	utimensat(dirfd int, path string, times *[2]Timespec, flags int) (err error)
   211	
   212	func UtimesNano(path string, ts []Timespec) error {
   213		if ts == nil {
   214			err := utimensat(AT_FDCWD, path, nil, 0)
   215			if err != ENOSYS {
   216				return err
   217			}
   218			return utimes(path, nil)
   219		}
   220		if len(ts) != 2 {
   221			return EINVAL
   222		}
   223		err := utimensat(AT_FDCWD, path, (*[2]Timespec)(unsafe.Pointer(&ts[0])), 0)
   224		if err != ENOSYS {
   225			return err
   226		}
   227		// If the utimensat syscall isn't available (utimensat was added to Linux
   228		// in 2.6.22, Released, 8 July 2007) then fall back to utimes
   229		var tv [2]Timeval
   230		for i := 0; i < 2; i++ {
   231			tv[i] = NsecToTimeval(TimespecToNsec(ts[i]))
   232		}
   233		return utimes(path, (*[2]Timeval)(unsafe.Pointer(&tv[0])))
   234	}
   235	
   236	func UtimesNanoAt(dirfd int, path string, ts []Timespec, flags int) error {
   237		if ts == nil {
   238			return utimensat(dirfd, path, nil, flags)
   239		}
   240		if len(ts) != 2 {
   241			return EINVAL
   242		}
   243		return utimensat(dirfd, path, (*[2]Timespec)(unsafe.Pointer(&ts[0])), flags)
   244	}
   245	
   246	func Futimesat(dirfd int, path string, tv []Timeval) error {
   247		if tv == nil {
   248			return futimesat(dirfd, path, nil)
   249		}
   250		if len(tv) != 2 {
   251			return EINVAL
   252		}
   253		return futimesat(dirfd, path, (*[2]Timeval)(unsafe.Pointer(&tv[0])))
   254	}
   255	
   256	func Futimes(fd int, tv []Timeval) (err error) {
   257		// Believe it or not, this is the best we can do on Linux
   258		// (and is what glibc does).
   259		return Utimes("/proc/self/fd/"+itoa(fd), tv)
   260	}
   261	
   262	const ImplementsGetwd = true
   263	
   264	//sys	Getcwd(buf []byte) (n int, err error)
   265	
   266	func Getwd() (wd string, err error) {
   267		var buf [PathMax]byte
   268		n, err := Getcwd(buf[0:])
   269		if err != nil {
   270			return "", err
   271		}
   272		// Getcwd returns the number of bytes written to buf, including the NUL.
   273		if n < 1 || n > len(buf) || buf[n-1] != 0 {
   274			return "", EINVAL
   275		}
   276		return string(buf[0 : n-1]), nil
   277	}
   278	
   279	func Getgroups() (gids []int, err error) {
   280		n, err := getgroups(0, nil)
   281		if err != nil {
   282			return nil, err
   283		}
   284		if n == 0 {
   285			return nil, nil
   286		}
   287	
   288		// Sanity check group count. Max is 1<<16 on Linux.
   289		if n < 0 || n > 1<<20 {
   290			return nil, EINVAL
   291		}
   292	
   293		a := make([]_Gid_t, n)
   294		n, err = getgroups(n, &a[0])
   295		if err != nil {
   296			return nil, err
   297		}
   298		gids = make([]int, n)
   299		for i, v := range a[0:n] {
   300			gids[i] = int(v)
   301		}
   302		return
   303	}
   304	
   305	func Setgroups(gids []int) (err error) {
   306		if len(gids) == 0 {
   307			return setgroups(0, nil)
   308		}
   309	
   310		a := make([]_Gid_t, len(gids))
   311		for i, v := range gids {
   312			a[i] = _Gid_t(v)
   313		}
   314		return setgroups(len(a), &a[0])
   315	}
   316	
   317	type WaitStatus uint32
   318	
   319	// Wait status is 7 bits at bottom, either 0 (exited),
   320	// 0x7F (stopped), or a signal number that caused an exit.
   321	// The 0x80 bit is whether there was a core dump.
   322	// An extra number (exit code, signal causing a stop)
   323	// is in the high bits. At least that's the idea.
   324	// There are various irregularities. For example, the
   325	// "continued" status is 0xFFFF, distinguishing itself
   326	// from stopped via the core dump bit.
   327	
   328	const (
   329		mask    = 0x7F
   330		core    = 0x80
   331		exited  = 0x00
   332		stopped = 0x7F
   333		shift   = 8
   334	)
   335	
   336	func (w WaitStatus) Exited() bool { return w&mask == exited }
   337	
   338	func (w WaitStatus) Signaled() bool { return w&mask != stopped && w&mask != exited }
   339	
   340	func (w WaitStatus) Stopped() bool { return w&0xFF == stopped }
   341	
   342	func (w WaitStatus) Continued() bool { return w == 0xFFFF }
   343	
   344	func (w WaitStatus) CoreDump() bool { return w.Signaled() && w&core != 0 }
   345	
   346	func (w WaitStatus) ExitStatus() int {
   347		if !w.Exited() {
   348			return -1
   349		}
   350		return int(w>>shift) & 0xFF
   351	}
   352	
   353	func (w WaitStatus) Signal() syscall.Signal {
   354		if !w.Signaled() {
   355			return -1
   356		}
   357		return syscall.Signal(w & mask)
   358	}
   359	
   360	func (w WaitStatus) StopSignal() syscall.Signal {
   361		if !w.Stopped() {
   362			return -1
   363		}
   364		return syscall.Signal(w>>shift) & 0xFF
   365	}
   366	
   367	func (w WaitStatus) TrapCause() int {
   368		if w.StopSignal() != SIGTRAP {
   369			return -1
   370		}
   371		return int(w>>shift) >> 8
   372	}
   373	
   374	//sys	wait4(pid int, wstatus *_C_int, options int, rusage *Rusage) (wpid int, err error)
   375	
   376	func Wait4(pid int, wstatus *WaitStatus, options int, rusage *Rusage) (wpid int, err error) {
   377		var status _C_int
   378		wpid, err = wait4(pid, &status, options, rusage)
   379		if wstatus != nil {
   380			*wstatus = WaitStatus(status)
   381		}
   382		return
   383	}
   384	
   385	func Mkfifo(path string, mode uint32) error {
   386		return Mknod(path, mode|S_IFIFO, 0)
   387	}
   388	
   389	func Mkfifoat(dirfd int, path string, mode uint32) error {
   390		return Mknodat(dirfd, path, mode|S_IFIFO, 0)
   391	}
   392	
   393	func (sa *SockaddrInet4) sockaddr() (unsafe.Pointer, _Socklen, error) {
   394		if sa.Port < 0 || sa.Port > 0xFFFF {
   395			return nil, 0, EINVAL
   396		}
   397		sa.raw.Family = AF_INET
   398		p := (*[2]byte)(unsafe.Pointer(&sa.raw.Port))
   399		p[0] = byte(sa.Port >> 8)
   400		p[1] = byte(sa.Port)
   401		for i := 0; i < len(sa.Addr); i++ {
   402			sa.raw.Addr[i] = sa.Addr[i]
   403		}
   404		return unsafe.Pointer(&sa.raw), SizeofSockaddrInet4, nil
   405	}
   406	
   407	func (sa *SockaddrInet6) sockaddr() (unsafe.Pointer, _Socklen, error) {
   408		if sa.Port < 0 || sa.Port > 0xFFFF {
   409			return nil, 0, EINVAL
   410		}
   411		sa.raw.Family = AF_INET6
   412		p := (*[2]byte)(unsafe.Pointer(&sa.raw.Port))
   413		p[0] = byte(sa.Port >> 8)
   414		p[1] = byte(sa.Port)
   415		sa.raw.Scope_id = sa.ZoneId
   416		for i := 0; i < len(sa.Addr); i++ {
   417			sa.raw.Addr[i] = sa.Addr[i]
   418		}
   419		return unsafe.Pointer(&sa.raw), SizeofSockaddrInet6, nil
   420	}
   421	
   422	func (sa *SockaddrUnix) sockaddr() (unsafe.Pointer, _Socklen, error) {
   423		name := sa.Name
   424		n := len(name)
   425		if n >= len(sa.raw.Path) {
   426			return nil, 0, EINVAL
   427		}
   428		sa.raw.Family = AF_UNIX
   429		for i := 0; i < n; i++ {
   430			sa.raw.Path[i] = int8(name[i])
   431		}
   432		// length is family (uint16), name, NUL.
   433		sl := _Socklen(2)
   434		if n > 0 {
   435			sl += _Socklen(n) + 1
   436		}
   437		if sa.raw.Path[0] == '@' {
   438			sa.raw.Path[0] = 0
   439			// Don't count trailing NUL for abstract address.
   440			sl--
   441		}
   442	
   443		return unsafe.Pointer(&sa.raw), sl, nil
   444	}
   445	
   446	// SockaddrLinklayer implements the Sockaddr interface for AF_PACKET type sockets.
   447	type SockaddrLinklayer struct {
   448		Protocol uint16
   449		Ifindex  int
   450		Hatype   uint16
   451		Pkttype  uint8
   452		Halen    uint8
   453		Addr     [8]byte
   454		raw      RawSockaddrLinklayer
   455	}
   456	
   457	func (sa *SockaddrLinklayer) sockaddr() (unsafe.Pointer, _Socklen, error) {
   458		if sa.Ifindex < 0 || sa.Ifindex > 0x7fffffff {
   459			return nil, 0, EINVAL
   460		}
   461		sa.raw.Family = AF_PACKET
   462		sa.raw.Protocol = sa.Protocol
   463		sa.raw.Ifindex = int32(sa.Ifindex)
   464		sa.raw.Hatype = sa.Hatype
   465		sa.raw.Pkttype = sa.Pkttype
   466		sa.raw.Halen = sa.Halen
   467		for i := 0; i < len(sa.Addr); i++ {
   468			sa.raw.Addr[i] = sa.Addr[i]
   469		}
   470		return unsafe.Pointer(&sa.raw), SizeofSockaddrLinklayer, nil
   471	}
   472	
   473	// SockaddrNetlink implements the Sockaddr interface for AF_NETLINK type sockets.
   474	type SockaddrNetlink struct {
   475		Family uint16
   476		Pad    uint16
   477		Pid    uint32
   478		Groups uint32
   479		raw    RawSockaddrNetlink
   480	}
   481	
   482	func (sa *SockaddrNetlink) sockaddr() (unsafe.Pointer, _Socklen, error) {
   483		sa.raw.Family = AF_NETLINK
   484		sa.raw.Pad = sa.Pad
   485		sa.raw.Pid = sa.Pid
   486		sa.raw.Groups = sa.Groups
   487		return unsafe.Pointer(&sa.raw), SizeofSockaddrNetlink, nil
   488	}
   489	
   490	// SockaddrHCI implements the Sockaddr interface for AF_BLUETOOTH type sockets
   491	// using the HCI protocol.
   492	type SockaddrHCI struct {
   493		Dev     uint16
   494		Channel uint16
   495		raw     RawSockaddrHCI
   496	}
   497	
   498	func (sa *SockaddrHCI) sockaddr() (unsafe.Pointer, _Socklen, error) {
   499		sa.raw.Family = AF_BLUETOOTH
   500		sa.raw.Dev = sa.Dev
   501		sa.raw.Channel = sa.Channel
   502		return unsafe.Pointer(&sa.raw), SizeofSockaddrHCI, nil
   503	}
   504	
   505	// SockaddrL2 implements the Sockaddr interface for AF_BLUETOOTH type sockets
   506	// using the L2CAP protocol.
   507	type SockaddrL2 struct {
   508		PSM      uint16
   509		CID      uint16
   510		Addr     [6]uint8
   511		AddrType uint8
   512		raw      RawSockaddrL2
   513	}
   514	
   515	func (sa *SockaddrL2) sockaddr() (unsafe.Pointer, _Socklen, error) {
   516		sa.raw.Family = AF_BLUETOOTH
   517		psm := (*[2]byte)(unsafe.Pointer(&sa.raw.Psm))
   518		psm[0] = byte(sa.PSM)
   519		psm[1] = byte(sa.PSM >> 8)
   520		for i := 0; i < len(sa.Addr); i++ {
   521			sa.raw.Bdaddr[i] = sa.Addr[len(sa.Addr)-1-i]
   522		}
   523		cid := (*[2]byte)(unsafe.Pointer(&sa.raw.Cid))
   524		cid[0] = byte(sa.CID)
   525		cid[1] = byte(sa.CID >> 8)
   526		sa.raw.Bdaddr_type = sa.AddrType
   527		return unsafe.Pointer(&sa.raw), SizeofSockaddrL2, nil
   528	}
   529	
   530	// SockaddrRFCOMM implements the Sockaddr interface for AF_BLUETOOTH type sockets
   531	// using the RFCOMM protocol.
   532	//
   533	// Server example:
   534	//
   535	//      fd, _ := Socket(AF_BLUETOOTH, SOCK_STREAM, BTPROTO_RFCOMM)
   536	//      _ = unix.Bind(fd, &unix.SockaddrRFCOMM{
   537	//      	Channel: 1,
   538	//      	Addr:    [6]uint8{0, 0, 0, 0, 0, 0}, // BDADDR_ANY or 00:00:00:00:00:00
   539	//      })
   540	//      _ = Listen(fd, 1)
   541	//      nfd, sa, _ := Accept(fd)
   542	//      fmt.Printf("conn addr=%v fd=%d", sa.(*unix.SockaddrRFCOMM).Addr, nfd)
   543	//      Read(nfd, buf)
   544	//
   545	// Client example:
   546	//
   547	//      fd, _ := Socket(AF_BLUETOOTH, SOCK_STREAM, BTPROTO_RFCOMM)
   548	//      _ = Connect(fd, &SockaddrRFCOMM{
   549	//      	Channel: 1,
   550	//      	Addr:    [6]byte{0x11, 0x22, 0x33, 0xaa, 0xbb, 0xcc}, // CC:BB:AA:33:22:11
   551	//      })
   552	//      Write(fd, []byte(`hello`))
   553	type SockaddrRFCOMM struct {
   554		// Addr represents a bluetooth address, byte ordering is little-endian.
   555		Addr [6]uint8
   556	
   557		// Channel is a designated bluetooth channel, only 1-30 are available for use.
   558		// Since Linux 2.6.7 and further zero value is the first available channel.
   559		Channel uint8
   560	
   561		raw RawSockaddrRFCOMM
   562	}
   563	
   564	func (sa *SockaddrRFCOMM) sockaddr() (unsafe.Pointer, _Socklen, error) {
   565		sa.raw.Family = AF_BLUETOOTH
   566		sa.raw.Channel = sa.Channel
   567		sa.raw.Bdaddr = sa.Addr
   568		return unsafe.Pointer(&sa.raw), SizeofSockaddrRFCOMM, nil
   569	}
   570	
   571	// SockaddrCAN implements the Sockaddr interface for AF_CAN type sockets.
   572	// The RxID and TxID fields are used for transport protocol addressing in
   573	// (CAN_TP16, CAN_TP20, CAN_MCNET, and CAN_ISOTP), they can be left with
   574	// zero values for CAN_RAW and CAN_BCM sockets as they have no meaning.
   575	//
   576	// The SockaddrCAN struct must be bound to the socket file descriptor
   577	// using Bind before the CAN socket can be used.
   578	//
   579	//      // Read one raw CAN frame
   580	//      fd, _ := Socket(AF_CAN, SOCK_RAW, CAN_RAW)
   581	//      addr := &SockaddrCAN{Ifindex: index}
   582	//      Bind(fd, addr)
   583	//      frame := make([]byte, 16)
   584	//      Read(fd, frame)
   585	//
   586	// The full SocketCAN documentation can be found in the linux kernel
   587	// archives at: https://www.kernel.org/doc/Documentation/networking/can.txt
   588	type SockaddrCAN struct {
   589		Ifindex int
   590		RxID    uint32
   591		TxID    uint32
   592		raw     RawSockaddrCAN
   593	}
   594	
   595	func (sa *SockaddrCAN) sockaddr() (unsafe.Pointer, _Socklen, error) {
   596		if sa.Ifindex < 0 || sa.Ifindex > 0x7fffffff {
   597			return nil, 0, EINVAL
   598		}
   599		sa.raw.Family = AF_CAN
   600		sa.raw.Ifindex = int32(sa.Ifindex)
   601		rx := (*[4]byte)(unsafe.Pointer(&sa.RxID))
   602		for i := 0; i < 4; i++ {
   603			sa.raw.Addr[i] = rx[i]
   604		}
   605		tx := (*[4]byte)(unsafe.Pointer(&sa.TxID))
   606		for i := 0; i < 4; i++ {
   607			sa.raw.Addr[i+4] = tx[i]
   608		}
   609		return unsafe.Pointer(&sa.raw), SizeofSockaddrCAN, nil
   610	}
   611	
   612	// SockaddrALG implements the Sockaddr interface for AF_ALG type sockets.
   613	// SockaddrALG enables userspace access to the Linux kernel's cryptography
   614	// subsystem. The Type and Name fields specify which type of hash or cipher
   615	// should be used with a given socket.
   616	//
   617	// To create a file descriptor that provides access to a hash or cipher, both
   618	// Bind and Accept must be used. Once the setup process is complete, input
   619	// data can be written to the socket, processed by the kernel, and then read
   620	// back as hash output or ciphertext.
   621	//
   622	// Here is an example of using an AF_ALG socket with SHA1 hashing.
   623	// The initial socket setup process is as follows:
   624	//
   625	//      // Open a socket to perform SHA1 hashing.
   626	//      fd, _ := unix.Socket(unix.AF_ALG, unix.SOCK_SEQPACKET, 0)
   627	//      addr := &unix.SockaddrALG{Type: "hash", Name: "sha1"}
   628	//      unix.Bind(fd, addr)
   629	//      // Note: unix.Accept does not work at this time; must invoke accept()
   630	//      // manually using unix.Syscall.
   631	//      hashfd, _, _ := unix.Syscall(unix.SYS_ACCEPT, uintptr(fd), 0, 0)
   632	//
   633	// Once a file descriptor has been returned from Accept, it may be used to
   634	// perform SHA1 hashing. The descriptor is not safe for concurrent use, but
   635	// may be re-used repeatedly with subsequent Write and Read operations.
   636	//
   637	// When hashing a small byte slice or string, a single Write and Read may
   638	// be used:
   639	//
   640	//      // Assume hashfd is already configured using the setup process.
   641	//      hash := os.NewFile(hashfd, "sha1")
   642	//      // Hash an input string and read the results. Each Write discards
   643	//      // previous hash state. Read always reads the current state.
   644	//      b := make([]byte, 20)
   645	//      for i := 0; i < 2; i++ {
   646	//          io.WriteString(hash, "Hello, world.")
   647	//          hash.Read(b)
   648	//          fmt.Println(hex.EncodeToString(b))
   649	//      }
   650	//      // Output:
   651	//      // 2ae01472317d1935a84797ec1983ae243fc6aa28
   652	//      // 2ae01472317d1935a84797ec1983ae243fc6aa28
   653	//
   654	// For hashing larger byte slices, or byte streams such as those read from
   655	// a file or socket, use Sendto with MSG_MORE to instruct the kernel to update
   656	// the hash digest instead of creating a new one for a given chunk and finalizing it.
   657	//
   658	//      // Assume hashfd and addr are already configured using the setup process.
   659	//      hash := os.NewFile(hashfd, "sha1")
   660	//      // Hash the contents of a file.
   661	//      f, _ := os.Open("/tmp/linux-4.10-rc7.tar.xz")
   662	//      b := make([]byte, 4096)
   663	//      for {
   664	//          n, err := f.Read(b)
   665	//          if err == io.EOF {
   666	//              break
   667	//          }
   668	//          unix.Sendto(hashfd, b[:n], unix.MSG_MORE, addr)
   669	//      }
   670	//      hash.Read(b)
   671	//      fmt.Println(hex.EncodeToString(b))
   672	//      // Output: 85cdcad0c06eef66f805ecce353bec9accbeecc5
   673	//
   674	// For more information, see: http://www.chronox.de/crypto-API/crypto/userspace-if.html.
   675	type SockaddrALG struct {
   676		Type    string
   677		Name    string
   678		Feature uint32
   679		Mask    uint32
   680		raw     RawSockaddrALG
   681	}
   682	
   683	func (sa *SockaddrALG) sockaddr() (unsafe.Pointer, _Socklen, error) {
   684		// Leave room for NUL byte terminator.
   685		if len(sa.Type) > 13 {
   686			return nil, 0, EINVAL
   687		}
   688		if len(sa.Name) > 63 {
   689			return nil, 0, EINVAL
   690		}
   691	
   692		sa.raw.Family = AF_ALG
   693		sa.raw.Feat = sa.Feature
   694		sa.raw.Mask = sa.Mask
   695	
   696		typ, err := ByteSliceFromString(sa.Type)
   697		if err != nil {
   698			return nil, 0, err
   699		}
   700		name, err := ByteSliceFromString(sa.Name)
   701		if err != nil {
   702			return nil, 0, err
   703		}
   704	
   705		copy(sa.raw.Type[:], typ)
   706		copy(sa.raw.Name[:], name)
   707	
   708		return unsafe.Pointer(&sa.raw), SizeofSockaddrALG, nil
   709	}
   710	
   711	// SockaddrVM implements the Sockaddr interface for AF_VSOCK type sockets.
   712	// SockaddrVM provides access to Linux VM sockets: a mechanism that enables
   713	// bidirectional communication between a hypervisor and its guest virtual
   714	// machines.
   715	type SockaddrVM struct {
   716		// CID and Port specify a context ID and port address for a VM socket.
   717		// Guests have a unique CID, and hosts may have a well-known CID of:
   718		//  - VMADDR_CID_HYPERVISOR: refers to the hypervisor process.
   719		//  - VMADDR_CID_HOST: refers to other processes on the host.
   720		CID  uint32
   721		Port uint32
   722		raw  RawSockaddrVM
   723	}
   724	
   725	func (sa *SockaddrVM) sockaddr() (unsafe.Pointer, _Socklen, error) {
   726		sa.raw.Family = AF_VSOCK
   727		sa.raw.Port = sa.Port
   728		sa.raw.Cid = sa.CID
   729	
   730		return unsafe.Pointer(&sa.raw), SizeofSockaddrVM, nil
   731	}
   732	
   733	type SockaddrXDP struct {
   734		Flags        uint16
   735		Ifindex      uint32
   736		QueueID      uint32
   737		SharedUmemFD uint32
   738		raw          RawSockaddrXDP
   739	}
   740	
   741	func (sa *SockaddrXDP) sockaddr() (unsafe.Pointer, _Socklen, error) {
   742		sa.raw.Family = AF_XDP
   743		sa.raw.Flags = sa.Flags
   744		sa.raw.Ifindex = sa.Ifindex
   745		sa.raw.Queue_id = sa.QueueID
   746		sa.raw.Shared_umem_fd = sa.SharedUmemFD
   747	
   748		return unsafe.Pointer(&sa.raw), SizeofSockaddrXDP, nil
   749	}
   750	
   751	// This constant mirrors the #define of PX_PROTO_OE in
   752	// linux/if_pppox.h. We're defining this by hand here instead of
   753	// autogenerating through mkerrors.sh because including
   754	// linux/if_pppox.h causes some declaration conflicts with other
   755	// includes (linux/if_pppox.h includes linux/in.h, which conflicts
   756	// with netinet/in.h). Given that we only need a single zero constant
   757	// out of that file, it's cleaner to just define it by hand here.
   758	const px_proto_oe = 0
   759	
   760	type SockaddrPPPoE struct {
   761		SID    uint16
   762		Remote net.HardwareAddr
   763		Dev    string
   764		raw    RawSockaddrPPPoX
   765	}
   766	
   767	func (sa *SockaddrPPPoE) sockaddr() (unsafe.Pointer, _Socklen, error) {
   768		if len(sa.Remote) != 6 {
   769			return nil, 0, EINVAL
   770		}
   771		if len(sa.Dev) > IFNAMSIZ-1 {
   772			return nil, 0, EINVAL
   773		}
   774	
   775		*(*uint16)(unsafe.Pointer(&sa.raw[0])) = AF_PPPOX
   776		// This next field is in host-endian byte order. We can't use the
   777		// same unsafe pointer cast as above, because this value is not
   778		// 32-bit aligned and some architectures don't allow unaligned
   779		// access.
   780		//
   781		// However, the value of px_proto_oe is 0, so we can use
   782		// encoding/binary helpers to write the bytes without worrying
   783		// about the ordering.
   784		binary.BigEndian.PutUint32(sa.raw[2:6], px_proto_oe)
   785		// This field is deliberately big-endian, unlike the previous
   786		// one. The kernel expects SID to be in network byte order.
   787		binary.BigEndian.PutUint16(sa.raw[6:8], sa.SID)
   788		copy(sa.raw[8:14], sa.Remote)
   789		for i := 14; i < 14+IFNAMSIZ; i++ {
   790			sa.raw[i] = 0
   791		}
   792		copy(sa.raw[14:], sa.Dev)
   793		return unsafe.Pointer(&sa.raw), SizeofSockaddrPPPoX, nil
   794	}
   795	
   796	func anyToSockaddr(fd int, rsa *RawSockaddrAny) (Sockaddr, error) {
   797		switch rsa.Addr.Family {
   798		case AF_NETLINK:
   799			pp := (*RawSockaddrNetlink)(unsafe.Pointer(rsa))
   800			sa := new(SockaddrNetlink)
   801			sa.Family = pp.Family
   802			sa.Pad = pp.Pad
   803			sa.Pid = pp.Pid
   804			sa.Groups = pp.Groups
   805			return sa, nil
   806	
   807		case AF_PACKET:
   808			pp := (*RawSockaddrLinklayer)(unsafe.Pointer(rsa))
   809			sa := new(SockaddrLinklayer)
   810			sa.Protocol = pp.Protocol
   811			sa.Ifindex = int(pp.Ifindex)
   812			sa.Hatype = pp.Hatype
   813			sa.Pkttype = pp.Pkttype
   814			sa.Halen = pp.Halen
   815			for i := 0; i < len(sa.Addr); i++ {
   816				sa.Addr[i] = pp.Addr[i]
   817			}
   818			return sa, nil
   819	
   820		case AF_UNIX:
   821			pp := (*RawSockaddrUnix)(unsafe.Pointer(rsa))
   822			sa := new(SockaddrUnix)
   823			if pp.Path[0] == 0 {
   824				// "Abstract" Unix domain socket.
   825				// Rewrite leading NUL as @ for textual display.
   826				// (This is the standard convention.)
   827				// Not friendly to overwrite in place,
   828				// but the callers below don't care.
   829				pp.Path[0] = '@'
   830			}
   831	
   832			// Assume path ends at NUL.
   833			// This is not technically the Linux semantics for
   834			// abstract Unix domain sockets--they are supposed
   835			// to be uninterpreted fixed-size binary blobs--but
   836			// everyone uses this convention.
   837			n := 0
   838			for n < len(pp.Path) && pp.Path[n] != 0 {
   839				n++
   840			}
   841			bytes := (*[10000]byte)(unsafe.Pointer(&pp.Path[0]))[0:n]
   842			sa.Name = string(bytes)
   843			return sa, nil
   844	
   845		case AF_INET:
   846			pp := (*RawSockaddrInet4)(unsafe.Pointer(rsa))
   847			sa := new(SockaddrInet4)
   848			p := (*[2]byte)(unsafe.Pointer(&pp.Port))
   849			sa.Port = int(p[0])<<8 + int(p[1])
   850			for i := 0; i < len(sa.Addr); i++ {
   851				sa.Addr[i] = pp.Addr[i]
   852			}
   853			return sa, nil
   854	
   855		case AF_INET6:
   856			pp := (*RawSockaddrInet6)(unsafe.Pointer(rsa))
   857			sa := new(SockaddrInet6)
   858			p := (*[2]byte)(unsafe.Pointer(&pp.Port))
   859			sa.Port = int(p[0])<<8 + int(p[1])
   860			sa.ZoneId = pp.Scope_id
   861			for i := 0; i < len(sa.Addr); i++ {
   862				sa.Addr[i] = pp.Addr[i]
   863			}
   864			return sa, nil
   865	
   866		case AF_VSOCK:
   867			pp := (*RawSockaddrVM)(unsafe.Pointer(rsa))
   868			sa := &SockaddrVM{
   869				CID:  pp.Cid,
   870				Port: pp.Port,
   871			}
   872			return sa, nil
   873		case AF_BLUETOOTH:
   874			proto, err := GetsockoptInt(fd, SOL_SOCKET, SO_PROTOCOL)
   875			if err != nil {
   876				return nil, err
   877			}
   878			// only BTPROTO_L2CAP and BTPROTO_RFCOMM can accept connections
   879			switch proto {
   880			case BTPROTO_L2CAP:
   881				pp := (*RawSockaddrL2)(unsafe.Pointer(rsa))
   882				sa := &SockaddrL2{
   883					PSM:      pp.Psm,
   884					CID:      pp.Cid,
   885					Addr:     pp.Bdaddr,
   886					AddrType: pp.Bdaddr_type,
   887				}
   888				return sa, nil
   889			case BTPROTO_RFCOMM:
   890				pp := (*RawSockaddrRFCOMM)(unsafe.Pointer(rsa))
   891				sa := &SockaddrRFCOMM{
   892					Channel: pp.Channel,
   893					Addr:    pp.Bdaddr,
   894				}
   895				return sa, nil
   896			}
   897		case AF_XDP:
   898			pp := (*RawSockaddrXDP)(unsafe.Pointer(rsa))
   899			sa := &SockaddrXDP{
   900				Flags:        pp.Flags,
   901				Ifindex:      pp.Ifindex,
   902				QueueID:      pp.Queue_id,
   903				SharedUmemFD: pp.Shared_umem_fd,
   904			}
   905			return sa, nil
   906		case AF_PPPOX:
   907			pp := (*RawSockaddrPPPoX)(unsafe.Pointer(rsa))
   908			if binary.BigEndian.Uint32(pp[2:6]) != px_proto_oe {
   909				return nil, EINVAL
   910			}
   911			sa := &SockaddrPPPoE{
   912				SID:    binary.BigEndian.Uint16(pp[6:8]),
   913				Remote: net.HardwareAddr(pp[8:14]),
   914			}
   915			for i := 14; i < 14+IFNAMSIZ; i++ {
   916				if pp[i] == 0 {
   917					sa.Dev = string(pp[14:i])
   918					break
   919				}
   920			}
   921			return sa, nil
   922		}
   923		return nil, EAFNOSUPPORT
   924	}
   925	
   926	func Accept(fd int) (nfd int, sa Sockaddr, err error) {
   927		var rsa RawSockaddrAny
   928		var len _Socklen = SizeofSockaddrAny
   929		nfd, err = accept(fd, &rsa, &len)
   930		if err != nil {
   931			return
   932		}
   933		sa, err = anyToSockaddr(fd, &rsa)
   934		if err != nil {
   935			Close(nfd)
   936			nfd = 0
   937		}
   938		return
   939	}
   940	
   941	func Accept4(fd int, flags int) (nfd int, sa Sockaddr, err error) {
   942		var rsa RawSockaddrAny
   943		var len _Socklen = SizeofSockaddrAny
   944		nfd, err = accept4(fd, &rsa, &len, flags)
   945		if err != nil {
   946			return
   947		}
   948		if len > SizeofSockaddrAny {
   949			panic("RawSockaddrAny too small")
   950		}
   951		sa, err = anyToSockaddr(fd, &rsa)
   952		if err != nil {
   953			Close(nfd)
   954			nfd = 0
   955		}
   956		return
   957	}
   958	
   959	func Getsockname(fd int) (sa Sockaddr, err error) {
   960		var rsa RawSockaddrAny
   961		var len _Socklen = SizeofSockaddrAny
   962		if err = getsockname(fd, &rsa, &len); err != nil {
   963			return
   964		}
   965		return anyToSockaddr(fd, &rsa)
   966	}
   967	
   968	func GetsockoptIPMreqn(fd, level, opt int) (*IPMreqn, error) {
   969		var value IPMreqn
   970		vallen := _Socklen(SizeofIPMreqn)
   971		err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
   972		return &value, err
   973	}
   974	
   975	func GetsockoptUcred(fd, level, opt int) (*Ucred, error) {
   976		var value Ucred
   977		vallen := _Socklen(SizeofUcred)
   978		err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
   979		return &value, err
   980	}
   981	
   982	func GetsockoptTCPInfo(fd, level, opt int) (*TCPInfo, error) {
   983		var value TCPInfo
   984		vallen := _Socklen(SizeofTCPInfo)
   985		err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
   986		return &value, err
   987	}
   988	
   989	// GetsockoptString returns the string value of the socket option opt for the
   990	// socket associated with fd at the given socket level.
   991	func GetsockoptString(fd, level, opt int) (string, error) {
   992		buf := make([]byte, 256)
   993		vallen := _Socklen(len(buf))
   994		err := getsockopt(fd, level, opt, unsafe.Pointer(&buf[0]), &vallen)
   995		if err != nil {
   996			if err == ERANGE {
   997				buf = make([]byte, vallen)
   998				err = getsockopt(fd, level, opt, unsafe.Pointer(&buf[0]), &vallen)
   999			}
  1000			if err != nil {
  1001				return "", err
  1002			}
  1003		}
  1004		return string(buf[:vallen-1]), nil
  1005	}
  1006	
  1007	func GetsockoptTpacketStats(fd, level, opt int) (*TpacketStats, error) {
  1008		var value TpacketStats
  1009		vallen := _Socklen(SizeofTpacketStats)
  1010		err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
  1011		return &value, err
  1012	}
  1013	
  1014	func GetsockoptTpacketStatsV3(fd, level, opt int) (*TpacketStatsV3, error) {
  1015		var value TpacketStatsV3
  1016		vallen := _Socklen(SizeofTpacketStatsV3)
  1017		err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
  1018		return &value, err
  1019	}
  1020	
  1021	func SetsockoptIPMreqn(fd, level, opt int, mreq *IPMreqn) (err error) {
  1022		return setsockopt(fd, level, opt, unsafe.Pointer(mreq), unsafe.Sizeof(*mreq))
  1023	}
  1024	
  1025	func SetsockoptPacketMreq(fd, level, opt int, mreq *PacketMreq) error {
  1026		return setsockopt(fd, level, opt, unsafe.Pointer(mreq), unsafe.Sizeof(*mreq))
  1027	}
  1028	
  1029	// SetsockoptSockFprog attaches a classic BPF or an extended BPF program to a
  1030	// socket to filter incoming packets.  See 'man 7 socket' for usage information.
  1031	func SetsockoptSockFprog(fd, level, opt int, fprog *SockFprog) error {
  1032		return setsockopt(fd, level, opt, unsafe.Pointer(fprog), unsafe.Sizeof(*fprog))
  1033	}
  1034	
  1035	func SetsockoptCanRawFilter(fd, level, opt int, filter []CanFilter) error {
  1036		var p unsafe.Pointer
  1037		if len(filter) > 0 {
  1038			p = unsafe.Pointer(&filter[0])
  1039		}
  1040		return setsockopt(fd, level, opt, p, uintptr(len(filter)*SizeofCanFilter))
  1041	}
  1042	
  1043	func SetsockoptTpacketReq(fd, level, opt int, tp *TpacketReq) error {
  1044		return setsockopt(fd, level, opt, unsafe.Pointer(tp), unsafe.Sizeof(*tp))
  1045	}
  1046	
  1047	func SetsockoptTpacketReq3(fd, level, opt int, tp *TpacketReq3) error {
  1048		return setsockopt(fd, level, opt, unsafe.Pointer(tp), unsafe.Sizeof(*tp))
  1049	}
  1050	
  1051	// Keyctl Commands (http://man7.org/linux/man-pages/man2/keyctl.2.html)
  1052	
  1053	// KeyctlInt calls keyctl commands in which each argument is an int.
  1054	// These commands are KEYCTL_REVOKE, KEYCTL_CHOWN, KEYCTL_CLEAR, KEYCTL_LINK,
  1055	// KEYCTL_UNLINK, KEYCTL_NEGATE, KEYCTL_SET_REQKEY_KEYRING, KEYCTL_SET_TIMEOUT,
  1056	// KEYCTL_ASSUME_AUTHORITY, KEYCTL_SESSION_TO_PARENT, KEYCTL_REJECT,
  1057	// KEYCTL_INVALIDATE, and KEYCTL_GET_PERSISTENT.
  1058	//sys	KeyctlInt(cmd int, arg2 int, arg3 int, arg4 int, arg5 int) (ret int, err error) = SYS_KEYCTL
  1059	
  1060	// KeyctlBuffer calls keyctl commands in which the third and fourth
  1061	// arguments are a buffer and its length, respectively.
  1062	// These commands are KEYCTL_UPDATE, KEYCTL_READ, and KEYCTL_INSTANTIATE.
  1063	//sys	KeyctlBuffer(cmd int, arg2 int, buf []byte, arg5 int) (ret int, err error) = SYS_KEYCTL
  1064	
  1065	// KeyctlString calls keyctl commands which return a string.
  1066	// These commands are KEYCTL_DESCRIBE and KEYCTL_GET_SECURITY.
  1067	func KeyctlString(cmd int, id int) (string, error) {
  1068		// We must loop as the string data may change in between the syscalls.
  1069		// We could allocate a large buffer here to reduce the chance that the
  1070		// syscall needs to be called twice; however, this is unnecessary as
  1071		// the performance loss is negligible.
  1072		var buffer []byte
  1073		for {
  1074			// Try to fill the buffer with data
  1075			length, err := KeyctlBuffer(cmd, id, buffer, 0)
  1076			if err != nil {
  1077				return "", err
  1078			}
  1079	
  1080			// Check if the data was written
  1081			if length <= len(buffer) {
  1082				// Exclude the null terminator
  1083				return string(buffer[:length-1]), nil
  1084			}
  1085	
  1086			// Make a bigger buffer if needed
  1087			buffer = make([]byte, length)
  1088		}
  1089	}
  1090	
  1091	// Keyctl commands with special signatures.
  1092	
  1093	// KeyctlGetKeyringID implements the KEYCTL_GET_KEYRING_ID command.
  1094	// See the full documentation at:
  1095	// http://man7.org/linux/man-pages/man3/keyctl_get_keyring_ID.3.html
  1096	func KeyctlGetKeyringID(id int, create bool) (ringid int, err error) {
  1097		createInt := 0
  1098		if create {
  1099			createInt = 1
  1100		}
  1101		return KeyctlInt(KEYCTL_GET_KEYRING_ID, id, createInt, 0, 0)
  1102	}
  1103	
  1104	// KeyctlSetperm implements the KEYCTL_SETPERM command. The perm value is the
  1105	// key handle permission mask as described in the "keyctl setperm" section of
  1106	// http://man7.org/linux/man-pages/man1/keyctl.1.html.
  1107	// See the full documentation at:
  1108	// http://man7.org/linux/man-pages/man3/keyctl_setperm.3.html
  1109	func KeyctlSetperm(id int, perm uint32) error {
  1110		_, err := KeyctlInt(KEYCTL_SETPERM, id, int(perm), 0, 0)
  1111		return err
  1112	}
  1113	
  1114	//sys	keyctlJoin(cmd int, arg2 string) (ret int, err error) = SYS_KEYCTL
  1115	
  1116	// KeyctlJoinSessionKeyring implements the KEYCTL_JOIN_SESSION_KEYRING command.
  1117	// See the full documentation at:
  1118	// http://man7.org/linux/man-pages/man3/keyctl_join_session_keyring.3.html
  1119	func KeyctlJoinSessionKeyring(name string) (ringid int, err error) {
  1120		return keyctlJoin(KEYCTL_JOIN_SESSION_KEYRING, name)
  1121	}
  1122	
  1123	//sys	keyctlSearch(cmd int, arg2 int, arg3 string, arg4 string, arg5 int) (ret int, err error) = SYS_KEYCTL
  1124	
  1125	// KeyctlSearch implements the KEYCTL_SEARCH command.
  1126	// See the full documentation at:
  1127	// http://man7.org/linux/man-pages/man3/keyctl_search.3.html
  1128	func KeyctlSearch(ringid int, keyType, description string, destRingid int) (id int, err error) {
  1129		return keyctlSearch(KEYCTL_SEARCH, ringid, keyType, description, destRingid)
  1130	}
  1131	
  1132	//sys	keyctlIOV(cmd int, arg2 int, payload []Iovec, arg5 int) (err error) = SYS_KEYCTL
  1133	
  1134	// KeyctlInstantiateIOV implements the KEYCTL_INSTANTIATE_IOV command. This
  1135	// command is similar to KEYCTL_INSTANTIATE, except that the payload is a slice
  1136	// of Iovec (each of which represents a buffer) instead of a single buffer.
  1137	// See the full documentation at:
  1138	// http://man7.org/linux/man-pages/man3/keyctl_instantiate_iov.3.html
  1139	func KeyctlInstantiateIOV(id int, payload []Iovec, ringid int) error {
  1140		return keyctlIOV(KEYCTL_INSTANTIATE_IOV, id, payload, ringid)
  1141	}
  1142	
  1143	//sys	keyctlDH(cmd int, arg2 *KeyctlDHParams, buf []byte) (ret int, err error) = SYS_KEYCTL
  1144	
  1145	// KeyctlDHCompute implements the KEYCTL_DH_COMPUTE command. This command
  1146	// computes a Diffie-Hellman shared secret based on the provide params. The
  1147	// secret is written to the provided buffer and the returned size is the number
  1148	// of bytes written (returning an error if there is insufficient space in the
  1149	// buffer). If a nil buffer is passed in, this function returns the minimum
  1150	// buffer length needed to store the appropriate data. Note that this differs
  1151	// from KEYCTL_READ's behavior which always returns the requested payload size.
  1152	// See the full documentation at:
  1153	// http://man7.org/linux/man-pages/man3/keyctl_dh_compute.3.html
  1154	func KeyctlDHCompute(params *KeyctlDHParams, buffer []byte) (size int, err error) {
  1155		return keyctlDH(KEYCTL_DH_COMPUTE, params, buffer)
  1156	}
  1157	
  1158	func Recvmsg(fd int, p, oob []byte, flags int) (n, oobn int, recvflags int, from Sockaddr, err error) {
  1159		var msg Msghdr
  1160		var rsa RawSockaddrAny
  1161		msg.Name = (*byte)(unsafe.Pointer(&rsa))
  1162		msg.Namelen = uint32(SizeofSockaddrAny)
  1163		var iov Iovec
  1164		if len(p) > 0 {
  1165			iov.Base = &p[0]
  1166			iov.SetLen(len(p))
  1167		}
  1168		var dummy byte
  1169		if len(oob) > 0 {
  1170			if len(p) == 0 {
  1171				var sockType int
  1172				sockType, err = GetsockoptInt(fd, SOL_SOCKET, SO_TYPE)
  1173				if err != nil {
  1174					return
  1175				}
  1176				// receive at least one normal byte
  1177				if sockType != SOCK_DGRAM {
  1178					iov.Base = &dummy
  1179					iov.SetLen(1)
  1180				}
  1181			}
  1182			msg.Control = &oob[0]
  1183			msg.SetControllen(len(oob))
  1184		}
  1185		msg.Iov = &iov
  1186		msg.Iovlen = 1
  1187		if n, err = recvmsg(fd, &msg, flags); err != nil {
  1188			return
  1189		}
  1190		oobn = int(msg.Controllen)
  1191		recvflags = int(msg.Flags)
  1192		// source address is only specified if the socket is unconnected
  1193		if rsa.Addr.Family != AF_UNSPEC {
  1194			from, err = anyToSockaddr(fd, &rsa)
  1195		}
  1196		return
  1197	}
  1198	
  1199	func Sendmsg(fd int, p, oob []byte, to Sockaddr, flags int) (err error) {
  1200		_, err = SendmsgN(fd, p, oob, to, flags)
  1201		return
  1202	}
  1203	
  1204	func SendmsgN(fd int, p, oob []byte, to Sockaddr, flags int) (n int, err error) {
  1205		var ptr unsafe.Pointer
  1206		var salen _Socklen
  1207		if to != nil {
  1208			var err error
  1209			ptr, salen, err = to.sockaddr()
  1210			if err != nil {
  1211				return 0, err
  1212			}
  1213		}
  1214		var msg Msghdr
  1215		msg.Name = (*byte)(ptr)
  1216		msg.Namelen = uint32(salen)
  1217		var iov Iovec
  1218		if len(p) > 0 {
  1219			iov.Base = &p[0]
  1220			iov.SetLen(len(p))
  1221		}
  1222		var dummy byte
  1223		if len(oob) > 0 {
  1224			if len(p) == 0 {
  1225				var sockType int
  1226				sockType, err = GetsockoptInt(fd, SOL_SOCKET, SO_TYPE)
  1227				if err != nil {
  1228					return 0, err
  1229				}
  1230				// send at least one normal byte
  1231				if sockType != SOCK_DGRAM {
  1232					iov.Base = &dummy
  1233					iov.SetLen(1)
  1234				}
  1235			}
  1236			msg.Control = &oob[0]
  1237			msg.SetControllen(len(oob))
  1238		}
  1239		msg.Iov = &iov
  1240		msg.Iovlen = 1
  1241		if n, err = sendmsg(fd, &msg, flags); err != nil {
  1242			return 0, err
  1243		}
  1244		if len(oob) > 0 && len(p) == 0 {
  1245			n = 0
  1246		}
  1247		return n, nil
  1248	}
  1249	
  1250	// BindToDevice binds the socket associated with fd to device.
  1251	func BindToDevice(fd int, device string) (err error) {
  1252		return SetsockoptString(fd, SOL_SOCKET, SO_BINDTODEVICE, device)
  1253	}
  1254	
  1255	//sys	ptrace(request int, pid int, addr uintptr, data uintptr) (err error)
  1256	
  1257	func ptracePeek(req int, pid int, addr uintptr, out []byte) (count int, err error) {
  1258		// The peek requests are machine-size oriented, so we wrap it
  1259		// to retrieve arbitrary-length data.
  1260	
  1261		// The ptrace syscall differs from glibc's ptrace.
  1262		// Peeks returns the word in *data, not as the return value.
  1263	
  1264		var buf [SizeofPtr]byte
  1265	
  1266		// Leading edge. PEEKTEXT/PEEKDATA don't require aligned
  1267		// access (PEEKUSER warns that it might), but if we don't
  1268		// align our reads, we might straddle an unmapped page
  1269		// boundary and not get the bytes leading up to the page
  1270		// boundary.
  1271		n := 0
  1272		if addr%SizeofPtr != 0 {
  1273			err = ptrace(req, pid, addr-addr%SizeofPtr, uintptr(unsafe.Pointer(&buf[0])))
  1274			if err != nil {
  1275				return 0, err
  1276			}
  1277			n += copy(out, buf[addr%SizeofPtr:])
  1278			out = out[n:]
  1279		}
  1280	
  1281		// Remainder.
  1282		for len(out) > 0 {
  1283			// We use an internal buffer to guarantee alignment.
  1284			// It's not documented if this is necessary, but we're paranoid.
  1285			err = ptrace(req, pid, addr+uintptr(n), uintptr(unsafe.Pointer(&buf[0])))
  1286			if err != nil {
  1287				return n, err
  1288			}
  1289			copied := copy(out, buf[0:])
  1290			n += copied
  1291			out = out[copied:]
  1292		}
  1293	
  1294		return n, nil
  1295	}
  1296	
  1297	func PtracePeekText(pid int, addr uintptr, out []byte) (count int, err error) {
  1298		return ptracePeek(PTRACE_PEEKTEXT, pid, addr, out)
  1299	}
  1300	
  1301	func PtracePeekData(pid int, addr uintptr, out []byte) (count int, err error) {
  1302		return ptracePeek(PTRACE_PEEKDATA, pid, addr, out)
  1303	}
  1304	
  1305	func PtracePeekUser(pid int, addr uintptr, out []byte) (count int, err error) {
  1306		return ptracePeek(PTRACE_PEEKUSR, pid, addr, out)
  1307	}
  1308	
  1309	func ptracePoke(pokeReq int, peekReq int, pid int, addr uintptr, data []byte) (count int, err error) {
  1310		// As for ptracePeek, we need to align our accesses to deal
  1311		// with the possibility of straddling an invalid page.
  1312	
  1313		// Leading edge.
  1314		n := 0
  1315		if addr%SizeofPtr != 0 {
  1316			var buf [SizeofPtr]byte
  1317			err = ptrace(peekReq, pid, addr-addr%SizeofPtr, uintptr(unsafe.Pointer(&buf[0])))
  1318			if err != nil {
  1319				return 0, err
  1320			}
  1321			n += copy(buf[addr%SizeofPtr:], data)
  1322			word := *((*uintptr)(unsafe.Pointer(&buf[0])))
  1323			err = ptrace(pokeReq, pid, addr-addr%SizeofPtr, word)
  1324			if err != nil {
  1325				return 0, err
  1326			}
  1327			data = data[n:]
  1328		}
  1329	
  1330		// Interior.
  1331		for len(data) > SizeofPtr {
  1332			word := *((*uintptr)(unsafe.Pointer(&data[0])))
  1333			err = ptrace(pokeReq, pid, addr+uintptr(n), word)
  1334			if err != nil {
  1335				return n, err
  1336			}
  1337			n += SizeofPtr
  1338			data = data[SizeofPtr:]
  1339		}
  1340	
  1341		// Trailing edge.
  1342		if len(data) > 0 {
  1343			var buf [SizeofPtr]byte
  1344			err = ptrace(peekReq, pid, addr+uintptr(n), uintptr(unsafe.Pointer(&buf[0])))
  1345			if err != nil {
  1346				return n, err
  1347			}
  1348			copy(buf[0:], data)
  1349			word := *((*uintptr)(unsafe.Pointer(&buf[0])))
  1350			err = ptrace(pokeReq, pid, addr+uintptr(n), word)
  1351			if err != nil {
  1352				return n, err
  1353			}
  1354			n += len(data)
  1355		}
  1356	
  1357		return n, nil
  1358	}
  1359	
  1360	func PtracePokeText(pid int, addr uintptr, data []byte) (count int, err error) {
  1361		return ptracePoke(PTRACE_POKETEXT, PTRACE_PEEKTEXT, pid, addr, data)
  1362	}
  1363	
  1364	func PtracePokeData(pid int, addr uintptr, data []byte) (count int, err error) {
  1365		return ptracePoke(PTRACE_POKEDATA, PTRACE_PEEKDATA, pid, addr, data)
  1366	}
  1367	
  1368	func PtracePokeUser(pid int, addr uintptr, data []byte) (count int, err error) {
  1369		return ptracePoke(PTRACE_POKEUSR, PTRACE_PEEKUSR, pid, addr, data)
  1370	}
  1371	
  1372	func PtraceGetRegs(pid int, regsout *PtraceRegs) (err error) {
  1373		return ptrace(PTRACE_GETREGS, pid, 0, uintptr(unsafe.Pointer(regsout)))
  1374	}
  1375	
  1376	func PtraceSetRegs(pid int, regs *PtraceRegs) (err error) {
  1377		return ptrace(PTRACE_SETREGS, pid, 0, uintptr(unsafe.Pointer(regs)))
  1378	}
  1379	
  1380	func PtraceSetOptions(pid int, options int) (err error) {
  1381		return ptrace(PTRACE_SETOPTIONS, pid, 0, uintptr(options))
  1382	}
  1383	
  1384	func PtraceGetEventMsg(pid int) (msg uint, err error) {
  1385		var data _C_long
  1386		err = ptrace(PTRACE_GETEVENTMSG, pid, 0, uintptr(unsafe.Pointer(&data)))
  1387		msg = uint(data)
  1388		return
  1389	}
  1390	
  1391	func PtraceCont(pid int, signal int) (err error) {
  1392		return ptrace(PTRACE_CONT, pid, 0, uintptr(signal))
  1393	}
  1394	
  1395	func PtraceSyscall(pid int, signal int) (err error) {
  1396		return ptrace(PTRACE_SYSCALL, pid, 0, uintptr(signal))
  1397	}
  1398	
  1399	func PtraceSingleStep(pid int) (err error) { return ptrace(PTRACE_SINGLESTEP, pid, 0, 0) }
  1400	
  1401	func PtraceAttach(pid int) (err error) { return ptrace(PTRACE_ATTACH, pid, 0, 0) }
  1402	
  1403	func PtraceDetach(pid int) (err error) { return ptrace(PTRACE_DETACH, pid, 0, 0) }
  1404	
  1405	//sys	reboot(magic1 uint, magic2 uint, cmd int, arg string) (err error)
  1406	
  1407	func Reboot(cmd int) (err error) {
  1408		return reboot(LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2, cmd, "")
  1409	}
  1410	
  1411	func ReadDirent(fd int, buf []byte) (n int, err error) {
  1412		return Getdents(fd, buf)
  1413	}
  1414	
  1415	//sys	mount(source string, target string, fstype string, flags uintptr, data *byte) (err error)
  1416	
  1417	func Mount(source string, target string, fstype string, flags uintptr, data string) (err error) {
  1418		// Certain file systems get rather angry and EINVAL if you give
  1419		// them an empty string of data, rather than NULL.
  1420		if data == "" {
  1421			return mount(source, target, fstype, flags, nil)
  1422		}
  1423		datap, err := BytePtrFromString(data)
  1424		if err != nil {
  1425			return err
  1426		}
  1427		return mount(source, target, fstype, flags, datap)
  1428	}
  1429	
  1430	func Sendfile(outfd int, infd int, offset *int64, count int) (written int, err error) {
  1431		if raceenabled {
  1432			raceReleaseMerge(unsafe.Pointer(&ioSync))
  1433		}
  1434		return sendfile(outfd, infd, offset, count)
  1435	}
  1436	
  1437	// Sendto
  1438	// Recvfrom
  1439	// Socketpair
  1440	
  1441	/*
  1442	 * Direct access
  1443	 */
  1444	//sys	Acct(path string) (err error)
  1445	//sys	AddKey(keyType string, description string, payload []byte, ringid int) (id int, err error)
  1446	//sys	Adjtimex(buf *Timex) (state int, err error)
  1447	//sys	Chdir(path string) (err error)
  1448	//sys	Chroot(path string) (err error)
  1449	//sys	ClockGetres(clockid int32, res *Timespec) (err error)
  1450	//sys	ClockGettime(clockid int32, time *Timespec) (err error)
  1451	//sys	ClockNanosleep(clockid int32, flags int, request *Timespec, remain *Timespec) (err error)
  1452	//sys	Close(fd int) (err error)
  1453	//sys	CopyFileRange(rfd int, roff *int64, wfd int, woff *int64, len int, flags int) (n int, err error)
  1454	//sys	DeleteModule(name string, flags int) (err error)
  1455	//sys	Dup(oldfd int) (fd int, err error)
  1456	//sys	Dup3(oldfd int, newfd int, flags int) (err error)
  1457	//sysnb	EpollCreate1(flag int) (fd int, err error)
  1458	//sysnb	EpollCtl(epfd int, op int, fd int, event *EpollEvent) (err error)
  1459	//sys	Eventfd(initval uint, flags int) (fd int, err error) = SYS_EVENTFD2
  1460	//sys	Exit(code int) = SYS_EXIT_GROUP
  1461	//sys	Fallocate(fd int, mode uint32, off int64, len int64) (err error)
  1462	//sys	Fchdir(fd int) (err error)
  1463	//sys	Fchmod(fd int, mode uint32) (err error)
  1464	//sys	Fchownat(dirfd int, path string, uid int, gid int, flags int) (err error)
  1465	//sys	fcntl(fd int, cmd int, arg int) (val int, err error)
  1466	//sys	Fdatasync(fd int) (err error)
  1467	//sys	Fgetxattr(fd int, attr string, dest []byte) (sz int, err error)
  1468	//sys	FinitModule(fd int, params string, flags int) (err error)
  1469	//sys	Flistxattr(fd int, dest []byte) (sz int, err error)
  1470	//sys	Flock(fd int, how int) (err error)
  1471	//sys	Fremovexattr(fd int, attr string) (err error)
  1472	//sys	Fsetxattr(fd int, attr string, dest []byte, flags int) (err error)
  1473	//sys	Fsync(fd int) (err error)
  1474	//sys	Getdents(fd int, buf []byte) (n int, err error) = SYS_GETDENTS64
  1475	//sysnb	Getpgid(pid int) (pgid int, err error)
  1476	
  1477	func Getpgrp() (pid int) {
  1478		pid, _ = Getpgid(0)
  1479		return
  1480	}
  1481	
  1482	//sysnb	Getpid() (pid int)
  1483	//sysnb	Getppid() (ppid int)
  1484	//sys	Getpriority(which int, who int) (prio int, err error)
  1485	//sys	Getrandom(buf []byte, flags int) (n int, err error)
  1486	//sysnb	Getrusage(who int, rusage *Rusage) (err error)
  1487	//sysnb	Getsid(pid int) (sid int, err error)
  1488	//sysnb	Gettid() (tid int)
  1489	//sys	Getxattr(path string, attr string, dest []byte) (sz int, err error)
  1490	//sys	InitModule(moduleImage []byte, params string) (err error)
  1491	//sys	InotifyAddWatch(fd int, pathname string, mask uint32) (watchdesc int, err error)
  1492	//sysnb	InotifyInit1(flags int) (fd int, err error)
  1493	//sysnb	InotifyRmWatch(fd int, watchdesc uint32) (success int, err error)
  1494	//sysnb	Kill(pid int, sig syscall.Signal) (err error)
  1495	//sys	Klogctl(typ int, buf []byte) (n int, err error) = SYS_SYSLOG
  1496	//sys	Lgetxattr(path string, attr string, dest []byte) (sz int, err error)
  1497	//sys	Listxattr(path string, dest []byte) (sz int, err error)
  1498	//sys	Llistxattr(path string, dest []byte) (sz int, err error)
  1499	//sys	Lremovexattr(path string, attr string) (err error)
  1500	//sys	Lsetxattr(path string, attr string, data []byte, flags int) (err error)
  1501	//sys	MemfdCreate(name string, flags int) (fd int, err error)
  1502	//sys	Mkdirat(dirfd int, path string, mode uint32) (err error)
  1503	//sys	Mknodat(dirfd int, path string, mode uint32, dev int) (err error)
  1504	//sys	Nanosleep(time *Timespec, leftover *Timespec) (err error)
  1505	//sys	PerfEventOpen(attr *PerfEventAttr, pid int, cpu int, groupFd int, flags int) (fd int, err error)
  1506	//sys	PivotRoot(newroot string, putold string) (err error) = SYS_PIVOT_ROOT
  1507	//sysnb prlimit(pid int, resource int, newlimit *Rlimit, old *Rlimit) (err error) = SYS_PRLIMIT64
  1508	//sys   Prctl(option int, arg2 uintptr, arg3 uintptr, arg4 uintptr, arg5 uintptr) (err error)
  1509	//sys	Pselect(nfd int, r *FdSet, w *FdSet, e *FdSet, timeout *Timespec, sigmask *Sigset_t) (n int, err error) = SYS_PSELECT6
  1510	//sys	read(fd int, p []byte) (n int, err error)
  1511	//sys	Removexattr(path string, attr string) (err error)
  1512	//sys	Renameat2(olddirfd int, oldpath string, newdirfd int, newpath string, flags uint) (err error)
  1513	//sys	RequestKey(keyType string, description string, callback string, destRingid int) (id int, err error)
  1514	//sys	Setdomainname(p []byte) (err error)
  1515	//sys	Sethostname(p []byte) (err error)
  1516	//sysnb	Setpgid(pid int, pgid int) (err error)
  1517	//sysnb	Setsid() (pid int, err error)
  1518	//sysnb	Settimeofday(tv *Timeval) (err error)
  1519	//sys	Setns(fd int, nstype int) (err error)
  1520	
  1521	// issue 1435.
  1522	// On linux Setuid and Setgid only affects the current thread, not the process.
  1523	// This does not match what most callers expect so we must return an error
  1524	// here rather than letting the caller think that the call succeeded.
  1525	
  1526	func Setuid(uid int) (err error) {
  1527		return EOPNOTSUPP
  1528	}
  1529	
  1530	func Setgid(uid int) (err error) {
  1531		return EOPNOTSUPP
  1532	}
  1533	
  1534	//sys	Setpriority(which int, who int, prio int) (err error)
  1535	//sys	Setxattr(path string, attr string, data []byte, flags int) (err error)
  1536	//sys	Signalfd(fd int, mask *Sigset_t, flags int) = SYS_SIGNALFD4
  1537	//sys	Statx(dirfd int, path string, flags int, mask int, stat *Statx_t) (err error)
  1538	//sys	Sync()
  1539	//sys	Syncfs(fd int) (err error)
  1540	//sysnb	Sysinfo(info *Sysinfo_t) (err error)
  1541	//sys	Tee(rfd int, wfd int, len int, flags int) (n int64, err error)
  1542	//sysnb	Tgkill(tgid int, tid int, sig syscall.Signal) (err error)
  1543	//sysnb	Times(tms *Tms) (ticks uintptr, err error)
  1544	//sysnb	Umask(mask int) (oldmask int)
  1545	//sysnb	Uname(buf *Utsname) (err error)
  1546	//sys	Unmount(target string, flags int) (err error) = SYS_UMOUNT2
  1547	//sys	Unshare(flags int) (err error)
  1548	//sys	write(fd int, p []byte) (n int, err error)
  1549	//sys	exitThread(code int) (err error) = SYS_EXIT
  1550	//sys	readlen(fd int, p *byte, np int) (n int, err error) = SYS_READ
  1551	//sys	writelen(fd int, p *byte, np int) (n int, err error) = SYS_WRITE
  1552	
  1553	// mmap varies by architecture; see syscall_linux_*.go.
  1554	//sys	munmap(addr uintptr, length uintptr) (err error)
  1555	
  1556	var mapper = &mmapper{
  1557		active: make(map[*byte][]byte),
  1558		mmap:   mmap,
  1559		munmap: munmap,
  1560	}
  1561	
  1562	func Mmap(fd int, offset int64, length int, prot int, flags int) (data []byte, err error) {
  1563		return mapper.Mmap(fd, offset, length, prot, flags)
  1564	}
  1565	
  1566	func Munmap(b []byte) (err error) {
  1567		return mapper.Munmap(b)
  1568	}
  1569	
  1570	//sys	Madvise(b []byte, advice int) (err error)
  1571	//sys	Mprotect(b []byte, prot int) (err error)
  1572	//sys	Mlock(b []byte) (err error)
  1573	//sys	Mlockall(flags int) (err error)
  1574	//sys	Msync(b []byte, flags int) (err error)
  1575	//sys	Munlock(b []byte) (err error)
  1576	//sys	Munlockall() (err error)
  1577	
  1578	// Vmsplice splices user pages from a slice of Iovecs into a pipe specified by fd,
  1579	// using the specified flags.
  1580	func Vmsplice(fd int, iovs []Iovec, flags int) (int, error) {
  1581		var p unsafe.Pointer
  1582		if len(iovs) > 0 {
  1583			p = unsafe.Pointer(&iovs[0])
  1584		}
  1585	
  1586		n, _, errno := Syscall6(SYS_VMSPLICE, uintptr(fd), uintptr(p), uintptr(len(iovs)), uintptr(flags), 0, 0)
  1587		if errno != 0 {
  1588			return 0, syscall.Errno(errno)
  1589		}
  1590	
  1591		return int(n), nil
  1592	}
  1593	
  1594	//sys	faccessat(dirfd int, path string, mode uint32) (err error)
  1595	
  1596	func Faccessat(dirfd int, path string, mode uint32, flags int) (err error) {
  1597		if flags & ^(AT_SYMLINK_NOFOLLOW|AT_EACCESS) != 0 {
  1598			return EINVAL
  1599		}
  1600	
  1601		// The Linux kernel faccessat system call does not take any flags.
  1602		// The glibc faccessat implements the flags itself; see
  1603		// https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/unix/sysv/linux/faccessat.c;hb=HEAD
  1604		// Because people naturally expect syscall.Faccessat to act
  1605		// like C faccessat, we do the same.
  1606	
  1607		if flags == 0 {
  1608			return faccessat(dirfd, path, mode)
  1609		}
  1610	
  1611		var st Stat_t
  1612		if err := Fstatat(dirfd, path, &st, flags&AT_SYMLINK_NOFOLLOW); err != nil {
  1613			return err
  1614		}
  1615	
  1616		mode &= 7
  1617		if mode == 0 {
  1618			return nil
  1619		}
  1620	
  1621		var uid int
  1622		if flags&AT_EACCESS != 0 {
  1623			uid = Geteuid()
  1624		} else {
  1625			uid = Getuid()
  1626		}
  1627	
  1628		if uid == 0 {
  1629			if mode&1 == 0 {
  1630				// Root can read and write any file.
  1631				return nil
  1632			}
  1633			if st.Mode&0111 != 0 {
  1634				// Root can execute any file that anybody can execute.
  1635				return nil
  1636			}
  1637			return EACCES
  1638		}
  1639	
  1640		var fmode uint32
  1641		if uint32(uid) == st.Uid {
  1642			fmode = (st.Mode >> 6) & 7
  1643		} else {
  1644			var gid int
  1645			if flags&AT_EACCESS != 0 {
  1646				gid = Getegid()
  1647			} else {
  1648				gid = Getgid()
  1649			}
  1650	
  1651			if uint32(gid) == st.Gid {
  1652				fmode = (st.Mode >> 3) & 7
  1653			} else {
  1654				fmode = st.Mode & 7
  1655			}
  1656		}
  1657	
  1658		if fmode&mode == mode {
  1659			return nil
  1660		}
  1661	
  1662		return EACCES
  1663	}
  1664	
  1665	//sys nameToHandleAt(dirFD int, pathname string, fh *fileHandle, mountID *_C_int, flags int) (err error) = SYS_NAME_TO_HANDLE_AT
  1666	//sys openByHandleAt(mountFD int, fh *fileHandle, flags int) (fd int, err error) = SYS_OPEN_BY_HANDLE_AT
  1667	
  1668	// fileHandle is the argument to nameToHandleAt and openByHandleAt. We
  1669	// originally tried to generate it via unix/linux/types.go with "type
  1670	// fileHandle C.struct_file_handle" but that generated empty structs
  1671	// for mips64 and mips64le. Instead, hard code it for now (it's the
  1672	// same everywhere else) until the mips64 generator issue is fixed.
  1673	type fileHandle struct {
  1674		Bytes uint32
  1675		Type  int32
  1676	}
  1677	
  1678	// FileHandle represents the C struct file_handle used by
  1679	// name_to_handle_at (see NameToHandleAt) and open_by_handle_at (see
  1680	// OpenByHandleAt).
  1681	type FileHandle struct {
  1682		*fileHandle
  1683	}
  1684	
  1685	// NewFileHandle constructs a FileHandle.
  1686	func NewFileHandle(handleType int32, handle []byte) FileHandle {
  1687		const hdrSize = unsafe.Sizeof(fileHandle{})
  1688		buf := make([]byte, hdrSize+uintptr(len(handle)))
  1689		copy(buf[hdrSize:], handle)
  1690		fh := (*fileHandle)(unsafe.Pointer(&buf[0]))
  1691		fh.Type = handleType
  1692		fh.Bytes = uint32(len(handle))
  1693		return FileHandle{fh}
  1694	}
  1695	
  1696	func (fh *FileHandle) Size() int   { return int(fh.fileHandle.Bytes) }
  1697	func (fh *FileHandle) Type() int32 { return fh.fileHandle.Type }
  1698	func (fh *FileHandle) Bytes() []byte {
  1699		n := fh.Size()
  1700		if n == 0 {
  1701			return nil
  1702		}
  1703		return (*[1 << 30]byte)(unsafe.Pointer(uintptr(unsafe.Pointer(&fh.fileHandle.Type)) + 4))[:n:n]
  1704	}
  1705	
  1706	// NameToHandleAt wraps the name_to_handle_at system call; it obtains
  1707	// a handle for a path name.
  1708	func NameToHandleAt(dirfd int, path string, flags int) (handle FileHandle, mountID int, err error) {
  1709		var mid _C_int
  1710		// Try first with a small buffer, assuming the handle will
  1711		// only be 32 bytes.
  1712		size := uint32(32 + unsafe.Sizeof(fileHandle{}))
  1713		didResize := false
  1714		for {
  1715			buf := make([]byte, size)
  1716			fh := (*fileHandle)(unsafe.Pointer(&buf[0]))
  1717			fh.Bytes = size - uint32(unsafe.Sizeof(fileHandle{}))
  1718			err = nameToHandleAt(dirfd, path, fh, &mid, flags)
  1719			if err == EOVERFLOW {
  1720				if didResize {
  1721					// We shouldn't need to resize more than once
  1722					return
  1723				}
  1724				didResize = true
  1725				size = fh.Bytes + uint32(unsafe.Sizeof(fileHandle{}))
  1726				continue
  1727			}
  1728			if err != nil {
  1729				return
  1730			}
  1731			return FileHandle{fh}, int(mid), nil
  1732		}
  1733	}
  1734	
  1735	// OpenByHandleAt wraps the open_by_handle_at system call; it opens a
  1736	// file via a handle as previously returned by NameToHandleAt.
  1737	func OpenByHandleAt(mountFD int, handle FileHandle, flags int) (fd int, err error) {
  1738		return openByHandleAt(mountFD, handle.fileHandle, flags)
  1739	}
  1740	
  1741	/*
  1742	 * Unimplemented
  1743	 */
  1744	// AfsSyscall
  1745	// Alarm
  1746	// ArchPrctl
  1747	// Brk
  1748	// Capget
  1749	// Capset
  1750	// ClockNanosleep
  1751	// ClockSettime
  1752	// Clone
  1753	// EpollCtlOld
  1754	// EpollPwait
  1755	// EpollWaitOld
  1756	// Execve
  1757	// Fork
  1758	// Futex
  1759	// GetKernelSyms
  1760	// GetMempolicy
  1761	// GetRobustList
  1762	// GetThreadArea
  1763	// Getitimer
  1764	// Getpmsg
  1765	// IoCancel
  1766	// IoDestroy
  1767	// IoGetevents
  1768	// IoSetup
  1769	// IoSubmit
  1770	// IoprioGet
  1771	// IoprioSet
  1772	// KexecLoad
  1773	// LookupDcookie
  1774	// Mbind
  1775	// MigratePages
  1776	// Mincore
  1777	// ModifyLdt
  1778	// Mount
  1779	// MovePages
  1780	// MqGetsetattr
  1781	// MqNotify
  1782	// MqOpen
  1783	// MqTimedreceive
  1784	// MqTimedsend
  1785	// MqUnlink
  1786	// Mremap
  1787	// Msgctl
  1788	// Msgget
  1789	// Msgrcv
  1790	// Msgsnd
  1791	// Nfsservctl
  1792	// Personality
  1793	// Pselect6
  1794	// Ptrace
  1795	// Putpmsg
  1796	// Quotactl
  1797	// Readahead
  1798	// Readv
  1799	// RemapFilePages
  1800	// RestartSyscall
  1801	// RtSigaction
  1802	// RtSigpending
  1803	// RtSigprocmask
  1804	// RtSigqueueinfo
  1805	// RtSigreturn
  1806	// RtSigsuspend
  1807	// RtSigtimedwait
  1808	// SchedGetPriorityMax
  1809	// SchedGetPriorityMin
  1810	// SchedGetparam
  1811	// SchedGetscheduler
  1812	// SchedRrGetInterval
  1813	// SchedSetparam
  1814	// SchedYield
  1815	// Security
  1816	// Semctl
  1817	// Semget
  1818	// Semop
  1819	// Semtimedop
  1820	// SetMempolicy
  1821	// SetRobustList
  1822	// SetThreadArea
  1823	// SetTidAddress
  1824	// Shmat
  1825	// Shmctl
  1826	// Shmdt
  1827	// Shmget
  1828	// Sigaltstack
  1829	// Swapoff
  1830	// Swapon
  1831	// Sysfs
  1832	// TimerCreate
  1833	// TimerDelete
  1834	// TimerGetoverrun
  1835	// TimerGettime
  1836	// TimerSettime
  1837	// Timerfd
  1838	// Tkill (obsolete)
  1839	// Tuxcall
  1840	// Umount2
  1841	// Uselib
  1842	// Utimensat
  1843	// Vfork
  1844	// Vhangup
  1845	// Vserver
  1846	// Waitid
  1847	// _Sysctl
  1848	

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