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

Documentation: golang.org/x/sys/unix

     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  	"strconv"
    17  	"syscall"
    18  	"time"
    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  func EpollCreate(size int) (fd int, err error) {
    43  	if size <= 0 {
    44  		return -1, EINVAL
    45  	}
    46  	return EpollCreate1(0)
    47  }
    48  
    49  //sys	FanotifyInit(flags uint, event_f_flags uint) (fd int, err error)
    50  //sys	fanotifyMark(fd int, flags uint, mask uint64, dirFd int, pathname *byte) (err error)
    51  
    52  func FanotifyMark(fd int, flags uint, mask uint64, dirFd int, pathname string) (err error) {
    53  	if pathname == "" {
    54  		return fanotifyMark(fd, flags, mask, dirFd, nil)
    55  	}
    56  	p, err := BytePtrFromString(pathname)
    57  	if err != nil {
    58  		return err
    59  	}
    60  	return fanotifyMark(fd, flags, mask, dirFd, p)
    61  }
    62  
    63  //sys	fchmodat(dirfd int, path string, mode uint32) (err error)
    64  
    65  func Fchmodat(dirfd int, path string, mode uint32, flags int) (err error) {
    66  	// Linux fchmodat doesn't support the flags parameter. Mimick glibc's behavior
    67  	// and check the flags. Otherwise the mode would be applied to the symlink
    68  	// destination which is not what the user expects.
    69  	if flags&^AT_SYMLINK_NOFOLLOW != 0 {
    70  		return EINVAL
    71  	} else if flags&AT_SYMLINK_NOFOLLOW != 0 {
    72  		return EOPNOTSUPP
    73  	}
    74  	return fchmodat(dirfd, path, mode)
    75  }
    76  
    77  func InotifyInit() (fd int, err error) {
    78  	return InotifyInit1(0)
    79  }
    80  
    81  //sys	ioctl(fd int, req uint, arg uintptr) (err error) = SYS_IOCTL
    82  //sys	ioctlPtr(fd int, req uint, arg unsafe.Pointer) (err error) = SYS_IOCTL
    83  
    84  // ioctl itself should not be exposed directly, but additional get/set functions
    85  // for specific types are permissible. These are defined in ioctl.go and
    86  // ioctl_linux.go.
    87  //
    88  // The third argument to ioctl is often a pointer but sometimes an integer.
    89  // Callers should use ioctlPtr when the third argument is a pointer and ioctl
    90  // when the third argument is an integer.
    91  //
    92  // TODO: some existing code incorrectly uses ioctl when it should use ioctlPtr.
    93  
    94  //sys	Linkat(olddirfd int, oldpath string, newdirfd int, newpath string, flags int) (err error)
    95  
    96  func Link(oldpath string, newpath string) (err error) {
    97  	return Linkat(AT_FDCWD, oldpath, AT_FDCWD, newpath, 0)
    98  }
    99  
   100  func Mkdir(path string, mode uint32) (err error) {
   101  	return Mkdirat(AT_FDCWD, path, mode)
   102  }
   103  
   104  func Mknod(path string, mode uint32, dev int) (err error) {
   105  	return Mknodat(AT_FDCWD, path, mode, dev)
   106  }
   107  
   108  func Open(path string, mode int, perm uint32) (fd int, err error) {
   109  	return openat(AT_FDCWD, path, mode|O_LARGEFILE, perm)
   110  }
   111  
   112  //sys	openat(dirfd int, path string, flags int, mode uint32) (fd int, err error)
   113  
   114  func Openat(dirfd int, path string, flags int, mode uint32) (fd int, err error) {
   115  	return openat(dirfd, path, flags|O_LARGEFILE, mode)
   116  }
   117  
   118  //sys	openat2(dirfd int, path string, open_how *OpenHow, size int) (fd int, err error)
   119  
   120  func Openat2(dirfd int, path string, how *OpenHow) (fd int, err error) {
   121  	return openat2(dirfd, path, how, SizeofOpenHow)
   122  }
   123  
   124  func Pipe(p []int) error {
   125  	return Pipe2(p, 0)
   126  }
   127  
   128  //sysnb	pipe2(p *[2]_C_int, flags int) (err error)
   129  
   130  func Pipe2(p []int, flags int) error {
   131  	if len(p) != 2 {
   132  		return EINVAL
   133  	}
   134  	var pp [2]_C_int
   135  	err := pipe2(&pp, flags)
   136  	if err == nil {
   137  		p[0] = int(pp[0])
   138  		p[1] = int(pp[1])
   139  	}
   140  	return err
   141  }
   142  
   143  //sys	ppoll(fds *PollFd, nfds int, timeout *Timespec, sigmask *Sigset_t) (n int, err error)
   144  
   145  func Ppoll(fds []PollFd, timeout *Timespec, sigmask *Sigset_t) (n int, err error) {
   146  	if len(fds) == 0 {
   147  		return ppoll(nil, 0, timeout, sigmask)
   148  	}
   149  	return ppoll(&fds[0], len(fds), timeout, sigmask)
   150  }
   151  
   152  func Poll(fds []PollFd, timeout int) (n int, err error) {
   153  	var ts *Timespec
   154  	if timeout >= 0 {
   155  		ts = new(Timespec)
   156  		*ts = NsecToTimespec(int64(timeout) * 1e6)
   157  	}
   158  	return Ppoll(fds, ts, nil)
   159  }
   160  
   161  //sys	Readlinkat(dirfd int, path string, buf []byte) (n int, err error)
   162  
   163  func Readlink(path string, buf []byte) (n int, err error) {
   164  	return Readlinkat(AT_FDCWD, path, buf)
   165  }
   166  
   167  func Rename(oldpath string, newpath string) (err error) {
   168  	return Renameat(AT_FDCWD, oldpath, AT_FDCWD, newpath)
   169  }
   170  
   171  func Rmdir(path string) error {
   172  	return Unlinkat(AT_FDCWD, path, AT_REMOVEDIR)
   173  }
   174  
   175  //sys	Symlinkat(oldpath string, newdirfd int, newpath string) (err error)
   176  
   177  func Symlink(oldpath string, newpath string) (err error) {
   178  	return Symlinkat(oldpath, AT_FDCWD, newpath)
   179  }
   180  
   181  func Unlink(path string) error {
   182  	return Unlinkat(AT_FDCWD, path, 0)
   183  }
   184  
   185  //sys	Unlinkat(dirfd int, path string, flags int) (err error)
   186  
   187  func Utimes(path string, tv []Timeval) error {
   188  	if tv == nil {
   189  		err := utimensat(AT_FDCWD, path, nil, 0)
   190  		if err != ENOSYS {
   191  			return err
   192  		}
   193  		return utimes(path, nil)
   194  	}
   195  	if len(tv) != 2 {
   196  		return EINVAL
   197  	}
   198  	var ts [2]Timespec
   199  	ts[0] = NsecToTimespec(TimevalToNsec(tv[0]))
   200  	ts[1] = NsecToTimespec(TimevalToNsec(tv[1]))
   201  	err := utimensat(AT_FDCWD, path, (*[2]Timespec)(unsafe.Pointer(&ts[0])), 0)
   202  	if err != ENOSYS {
   203  		return err
   204  	}
   205  	return utimes(path, (*[2]Timeval)(unsafe.Pointer(&tv[0])))
   206  }
   207  
   208  //sys	utimensat(dirfd int, path string, times *[2]Timespec, flags int) (err error)
   209  
   210  func UtimesNano(path string, ts []Timespec) error {
   211  	return UtimesNanoAt(AT_FDCWD, path, ts, 0)
   212  }
   213  
   214  func UtimesNanoAt(dirfd int, path string, ts []Timespec, flags int) error {
   215  	if ts == nil {
   216  		return utimensat(dirfd, path, nil, flags)
   217  	}
   218  	if len(ts) != 2 {
   219  		return EINVAL
   220  	}
   221  	return utimensat(dirfd, path, (*[2]Timespec)(unsafe.Pointer(&ts[0])), flags)
   222  }
   223  
   224  func Futimesat(dirfd int, path string, tv []Timeval) error {
   225  	if tv == nil {
   226  		return futimesat(dirfd, path, nil)
   227  	}
   228  	if len(tv) != 2 {
   229  		return EINVAL
   230  	}
   231  	return futimesat(dirfd, path, (*[2]Timeval)(unsafe.Pointer(&tv[0])))
   232  }
   233  
   234  func Futimes(fd int, tv []Timeval) (err error) {
   235  	// Believe it or not, this is the best we can do on Linux
   236  	// (and is what glibc does).
   237  	return Utimes("/proc/self/fd/"+strconv.Itoa(fd), tv)
   238  }
   239  
   240  const ImplementsGetwd = true
   241  
   242  //sys	Getcwd(buf []byte) (n int, err error)
   243  
   244  func Getwd() (wd string, err error) {
   245  	var buf [PathMax]byte
   246  	n, err := Getcwd(buf[0:])
   247  	if err != nil {
   248  		return "", err
   249  	}
   250  	// Getcwd returns the number of bytes written to buf, including the NUL.
   251  	if n < 1 || n > len(buf) || buf[n-1] != 0 {
   252  		return "", EINVAL
   253  	}
   254  	// In some cases, Linux can return a path that starts with the
   255  	// "(unreachable)" prefix, which can potentially be a valid relative
   256  	// path. To work around that, return ENOENT if path is not absolute.
   257  	if buf[0] != '/' {
   258  		return "", ENOENT
   259  	}
   260  
   261  	return string(buf[0 : n-1]), nil
   262  }
   263  
   264  func Getgroups() (gids []int, err error) {
   265  	n, err := getgroups(0, nil)
   266  	if err != nil {
   267  		return nil, err
   268  	}
   269  	if n == 0 {
   270  		return nil, nil
   271  	}
   272  
   273  	// Sanity check group count. Max is 1<<16 on Linux.
   274  	if n < 0 || n > 1<<20 {
   275  		return nil, EINVAL
   276  	}
   277  
   278  	a := make([]_Gid_t, n)
   279  	n, err = getgroups(n, &a[0])
   280  	if err != nil {
   281  		return nil, err
   282  	}
   283  	gids = make([]int, n)
   284  	for i, v := range a[0:n] {
   285  		gids[i] = int(v)
   286  	}
   287  	return
   288  }
   289  
   290  func Setgroups(gids []int) (err error) {
   291  	if len(gids) == 0 {
   292  		return setgroups(0, nil)
   293  	}
   294  
   295  	a := make([]_Gid_t, len(gids))
   296  	for i, v := range gids {
   297  		a[i] = _Gid_t(v)
   298  	}
   299  	return setgroups(len(a), &a[0])
   300  }
   301  
   302  type WaitStatus uint32
   303  
   304  // Wait status is 7 bits at bottom, either 0 (exited),
   305  // 0x7F (stopped), or a signal number that caused an exit.
   306  // The 0x80 bit is whether there was a core dump.
   307  // An extra number (exit code, signal causing a stop)
   308  // is in the high bits. At least that's the idea.
   309  // There are various irregularities. For example, the
   310  // "continued" status is 0xFFFF, distinguishing itself
   311  // from stopped via the core dump bit.
   312  
   313  const (
   314  	mask    = 0x7F
   315  	core    = 0x80
   316  	exited  = 0x00
   317  	stopped = 0x7F
   318  	shift   = 8
   319  )
   320  
   321  func (w WaitStatus) Exited() bool { return w&mask == exited }
   322  
   323  func (w WaitStatus) Signaled() bool { return w&mask != stopped && w&mask != exited }
   324  
   325  func (w WaitStatus) Stopped() bool { return w&0xFF == stopped }
   326  
   327  func (w WaitStatus) Continued() bool { return w == 0xFFFF }
   328  
   329  func (w WaitStatus) CoreDump() bool { return w.Signaled() && w&core != 0 }
   330  
   331  func (w WaitStatus) ExitStatus() int {
   332  	if !w.Exited() {
   333  		return -1
   334  	}
   335  	return int(w>>shift) & 0xFF
   336  }
   337  
   338  func (w WaitStatus) Signal() syscall.Signal {
   339  	if !w.Signaled() {
   340  		return -1
   341  	}
   342  	return syscall.Signal(w & mask)
   343  }
   344  
   345  func (w WaitStatus) StopSignal() syscall.Signal {
   346  	if !w.Stopped() {
   347  		return -1
   348  	}
   349  	return syscall.Signal(w>>shift) & 0xFF
   350  }
   351  
   352  func (w WaitStatus) TrapCause() int {
   353  	if w.StopSignal() != SIGTRAP {
   354  		return -1
   355  	}
   356  	return int(w>>shift) >> 8
   357  }
   358  
   359  //sys	wait4(pid int, wstatus *_C_int, options int, rusage *Rusage) (wpid int, err error)
   360  
   361  func Wait4(pid int, wstatus *WaitStatus, options int, rusage *Rusage) (wpid int, err error) {
   362  	var status _C_int
   363  	wpid, err = wait4(pid, &status, options, rusage)
   364  	if wstatus != nil {
   365  		*wstatus = WaitStatus(status)
   366  	}
   367  	return
   368  }
   369  
   370  //sys	Waitid(idType int, id int, info *Siginfo, options int, rusage *Rusage) (err error)
   371  
   372  func Mkfifo(path string, mode uint32) error {
   373  	return Mknod(path, mode|S_IFIFO, 0)
   374  }
   375  
   376  func Mkfifoat(dirfd int, path string, mode uint32) error {
   377  	return Mknodat(dirfd, path, mode|S_IFIFO, 0)
   378  }
   379  
   380  func (sa *SockaddrInet4) sockaddr() (unsafe.Pointer, _Socklen, error) {
   381  	if sa.Port < 0 || sa.Port > 0xFFFF {
   382  		return nil, 0, EINVAL
   383  	}
   384  	sa.raw.Family = AF_INET
   385  	p := (*[2]byte)(unsafe.Pointer(&sa.raw.Port))
   386  	p[0] = byte(sa.Port >> 8)
   387  	p[1] = byte(sa.Port)
   388  	sa.raw.Addr = sa.Addr
   389  	return unsafe.Pointer(&sa.raw), SizeofSockaddrInet4, nil
   390  }
   391  
   392  func (sa *SockaddrInet6) sockaddr() (unsafe.Pointer, _Socklen, error) {
   393  	if sa.Port < 0 || sa.Port > 0xFFFF {
   394  		return nil, 0, EINVAL
   395  	}
   396  	sa.raw.Family = AF_INET6
   397  	p := (*[2]byte)(unsafe.Pointer(&sa.raw.Port))
   398  	p[0] = byte(sa.Port >> 8)
   399  	p[1] = byte(sa.Port)
   400  	sa.raw.Scope_id = sa.ZoneId
   401  	sa.raw.Addr = sa.Addr
   402  	return unsafe.Pointer(&sa.raw), SizeofSockaddrInet6, nil
   403  }
   404  
   405  func (sa *SockaddrUnix) sockaddr() (unsafe.Pointer, _Socklen, error) {
   406  	name := sa.Name
   407  	n := len(name)
   408  	if n >= len(sa.raw.Path) {
   409  		return nil, 0, EINVAL
   410  	}
   411  	sa.raw.Family = AF_UNIX
   412  	for i := 0; i < n; i++ {
   413  		sa.raw.Path[i] = int8(name[i])
   414  	}
   415  	// length is family (uint16), name, NUL.
   416  	sl := _Socklen(2)
   417  	if n > 0 {
   418  		sl += _Socklen(n) + 1
   419  	}
   420  	if sa.raw.Path[0] == '@' {
   421  		sa.raw.Path[0] = 0
   422  		// Don't count trailing NUL for abstract address.
   423  		sl--
   424  	}
   425  
   426  	return unsafe.Pointer(&sa.raw), sl, nil
   427  }
   428  
   429  // SockaddrLinklayer implements the Sockaddr interface for AF_PACKET type sockets.
   430  type SockaddrLinklayer struct {
   431  	Protocol uint16
   432  	Ifindex  int
   433  	Hatype   uint16
   434  	Pkttype  uint8
   435  	Halen    uint8
   436  	Addr     [8]byte
   437  	raw      RawSockaddrLinklayer
   438  }
   439  
   440  func (sa *SockaddrLinklayer) sockaddr() (unsafe.Pointer, _Socklen, error) {
   441  	if sa.Ifindex < 0 || sa.Ifindex > 0x7fffffff {
   442  		return nil, 0, EINVAL
   443  	}
   444  	sa.raw.Family = AF_PACKET
   445  	sa.raw.Protocol = sa.Protocol
   446  	sa.raw.Ifindex = int32(sa.Ifindex)
   447  	sa.raw.Hatype = sa.Hatype
   448  	sa.raw.Pkttype = sa.Pkttype
   449  	sa.raw.Halen = sa.Halen
   450  	sa.raw.Addr = sa.Addr
   451  	return unsafe.Pointer(&sa.raw), SizeofSockaddrLinklayer, nil
   452  }
   453  
   454  // SockaddrNetlink implements the Sockaddr interface for AF_NETLINK type sockets.
   455  type SockaddrNetlink struct {
   456  	Family uint16
   457  	Pad    uint16
   458  	Pid    uint32
   459  	Groups uint32
   460  	raw    RawSockaddrNetlink
   461  }
   462  
   463  func (sa *SockaddrNetlink) sockaddr() (unsafe.Pointer, _Socklen, error) {
   464  	sa.raw.Family = AF_NETLINK
   465  	sa.raw.Pad = sa.Pad
   466  	sa.raw.Pid = sa.Pid
   467  	sa.raw.Groups = sa.Groups
   468  	return unsafe.Pointer(&sa.raw), SizeofSockaddrNetlink, nil
   469  }
   470  
   471  // SockaddrHCI implements the Sockaddr interface for AF_BLUETOOTH type sockets
   472  // using the HCI protocol.
   473  type SockaddrHCI struct {
   474  	Dev     uint16
   475  	Channel uint16
   476  	raw     RawSockaddrHCI
   477  }
   478  
   479  func (sa *SockaddrHCI) sockaddr() (unsafe.Pointer, _Socklen, error) {
   480  	sa.raw.Family = AF_BLUETOOTH
   481  	sa.raw.Dev = sa.Dev
   482  	sa.raw.Channel = sa.Channel
   483  	return unsafe.Pointer(&sa.raw), SizeofSockaddrHCI, nil
   484  }
   485  
   486  // SockaddrL2 implements the Sockaddr interface for AF_BLUETOOTH type sockets
   487  // using the L2CAP protocol.
   488  type SockaddrL2 struct {
   489  	PSM      uint16
   490  	CID      uint16
   491  	Addr     [6]uint8
   492  	AddrType uint8
   493  	raw      RawSockaddrL2
   494  }
   495  
   496  func (sa *SockaddrL2) sockaddr() (unsafe.Pointer, _Socklen, error) {
   497  	sa.raw.Family = AF_BLUETOOTH
   498  	psm := (*[2]byte)(unsafe.Pointer(&sa.raw.Psm))
   499  	psm[0] = byte(sa.PSM)
   500  	psm[1] = byte(sa.PSM >> 8)
   501  	for i := 0; i < len(sa.Addr); i++ {
   502  		sa.raw.Bdaddr[i] = sa.Addr[len(sa.Addr)-1-i]
   503  	}
   504  	cid := (*[2]byte)(unsafe.Pointer(&sa.raw.Cid))
   505  	cid[0] = byte(sa.CID)
   506  	cid[1] = byte(sa.CID >> 8)
   507  	sa.raw.Bdaddr_type = sa.AddrType
   508  	return unsafe.Pointer(&sa.raw), SizeofSockaddrL2, nil
   509  }
   510  
   511  // SockaddrRFCOMM implements the Sockaddr interface for AF_BLUETOOTH type sockets
   512  // using the RFCOMM protocol.
   513  //
   514  // Server example:
   515  //
   516  //	fd, _ := Socket(AF_BLUETOOTH, SOCK_STREAM, BTPROTO_RFCOMM)
   517  //	_ = unix.Bind(fd, &unix.SockaddrRFCOMM{
   518  //		Channel: 1,
   519  //		Addr:    [6]uint8{0, 0, 0, 0, 0, 0}, // BDADDR_ANY or 00:00:00:00:00:00
   520  //	})
   521  //	_ = Listen(fd, 1)
   522  //	nfd, sa, _ := Accept(fd)
   523  //	fmt.Printf("conn addr=%v fd=%d", sa.(*unix.SockaddrRFCOMM).Addr, nfd)
   524  //	Read(nfd, buf)
   525  //
   526  // Client example:
   527  //
   528  //	fd, _ := Socket(AF_BLUETOOTH, SOCK_STREAM, BTPROTO_RFCOMM)
   529  //	_ = Connect(fd, &SockaddrRFCOMM{
   530  //		Channel: 1,
   531  //		Addr:    [6]byte{0x11, 0x22, 0x33, 0xaa, 0xbb, 0xcc}, // CC:BB:AA:33:22:11
   532  //	})
   533  //	Write(fd, []byte(`hello`))
   534  type SockaddrRFCOMM struct {
   535  	// Addr represents a bluetooth address, byte ordering is little-endian.
   536  	Addr [6]uint8
   537  
   538  	// Channel is a designated bluetooth channel, only 1-30 are available for use.
   539  	// Since Linux 2.6.7 and further zero value is the first available channel.
   540  	Channel uint8
   541  
   542  	raw RawSockaddrRFCOMM
   543  }
   544  
   545  func (sa *SockaddrRFCOMM) sockaddr() (unsafe.Pointer, _Socklen, error) {
   546  	sa.raw.Family = AF_BLUETOOTH
   547  	sa.raw.Channel = sa.Channel
   548  	sa.raw.Bdaddr = sa.Addr
   549  	return unsafe.Pointer(&sa.raw), SizeofSockaddrRFCOMM, nil
   550  }
   551  
   552  // SockaddrCAN implements the Sockaddr interface for AF_CAN type sockets.
   553  // The RxID and TxID fields are used for transport protocol addressing in
   554  // (CAN_TP16, CAN_TP20, CAN_MCNET, and CAN_ISOTP), they can be left with
   555  // zero values for CAN_RAW and CAN_BCM sockets as they have no meaning.
   556  //
   557  // The SockaddrCAN struct must be bound to the socket file descriptor
   558  // using Bind before the CAN socket can be used.
   559  //
   560  //	// Read one raw CAN frame
   561  //	fd, _ := Socket(AF_CAN, SOCK_RAW, CAN_RAW)
   562  //	addr := &SockaddrCAN{Ifindex: index}
   563  //	Bind(fd, addr)
   564  //	frame := make([]byte, 16)
   565  //	Read(fd, frame)
   566  //
   567  // The full SocketCAN documentation can be found in the linux kernel
   568  // archives at: https://www.kernel.org/doc/Documentation/networking/can.txt
   569  type SockaddrCAN struct {
   570  	Ifindex int
   571  	RxID    uint32
   572  	TxID    uint32
   573  	raw     RawSockaddrCAN
   574  }
   575  
   576  func (sa *SockaddrCAN) sockaddr() (unsafe.Pointer, _Socklen, error) {
   577  	if sa.Ifindex < 0 || sa.Ifindex > 0x7fffffff {
   578  		return nil, 0, EINVAL
   579  	}
   580  	sa.raw.Family = AF_CAN
   581  	sa.raw.Ifindex = int32(sa.Ifindex)
   582  	rx := (*[4]byte)(unsafe.Pointer(&sa.RxID))
   583  	for i := 0; i < 4; i++ {
   584  		sa.raw.Addr[i] = rx[i]
   585  	}
   586  	tx := (*[4]byte)(unsafe.Pointer(&sa.TxID))
   587  	for i := 0; i < 4; i++ {
   588  		sa.raw.Addr[i+4] = tx[i]
   589  	}
   590  	return unsafe.Pointer(&sa.raw), SizeofSockaddrCAN, nil
   591  }
   592  
   593  // SockaddrCANJ1939 implements the Sockaddr interface for AF_CAN using J1939
   594  // protocol (https://en.wikipedia.org/wiki/SAE_J1939). For more information
   595  // on the purposes of the fields, check the official linux kernel documentation
   596  // available here: https://www.kernel.org/doc/Documentation/networking/j1939.rst
   597  type SockaddrCANJ1939 struct {
   598  	Ifindex int
   599  	Name    uint64
   600  	PGN     uint32
   601  	Addr    uint8
   602  	raw     RawSockaddrCAN
   603  }
   604  
   605  func (sa *SockaddrCANJ1939) sockaddr() (unsafe.Pointer, _Socklen, error) {
   606  	if sa.Ifindex < 0 || sa.Ifindex > 0x7fffffff {
   607  		return nil, 0, EINVAL
   608  	}
   609  	sa.raw.Family = AF_CAN
   610  	sa.raw.Ifindex = int32(sa.Ifindex)
   611  	n := (*[8]byte)(unsafe.Pointer(&sa.Name))
   612  	for i := 0; i < 8; i++ {
   613  		sa.raw.Addr[i] = n[i]
   614  	}
   615  	p := (*[4]byte)(unsafe.Pointer(&sa.PGN))
   616  	for i := 0; i < 4; i++ {
   617  		sa.raw.Addr[i+8] = p[i]
   618  	}
   619  	sa.raw.Addr[12] = sa.Addr
   620  	return unsafe.Pointer(&sa.raw), SizeofSockaddrCAN, nil
   621  }
   622  
   623  // SockaddrALG implements the Sockaddr interface for AF_ALG type sockets.
   624  // SockaddrALG enables userspace access to the Linux kernel's cryptography
   625  // subsystem. The Type and Name fields specify which type of hash or cipher
   626  // should be used with a given socket.
   627  //
   628  // To create a file descriptor that provides access to a hash or cipher, both
   629  // Bind and Accept must be used. Once the setup process is complete, input
   630  // data can be written to the socket, processed by the kernel, and then read
   631  // back as hash output or ciphertext.
   632  //
   633  // Here is an example of using an AF_ALG socket with SHA1 hashing.
   634  // The initial socket setup process is as follows:
   635  //
   636  //	// Open a socket to perform SHA1 hashing.
   637  //	fd, _ := unix.Socket(unix.AF_ALG, unix.SOCK_SEQPACKET, 0)
   638  //	addr := &unix.SockaddrALG{Type: "hash", Name: "sha1"}
   639  //	unix.Bind(fd, addr)
   640  //	// Note: unix.Accept does not work at this time; must invoke accept()
   641  //	// manually using unix.Syscall.
   642  //	hashfd, _, _ := unix.Syscall(unix.SYS_ACCEPT, uintptr(fd), 0, 0)
   643  //
   644  // Once a file descriptor has been returned from Accept, it may be used to
   645  // perform SHA1 hashing. The descriptor is not safe for concurrent use, but
   646  // may be re-used repeatedly with subsequent Write and Read operations.
   647  //
   648  // When hashing a small byte slice or string, a single Write and Read may
   649  // be used:
   650  //
   651  //	// Assume hashfd is already configured using the setup process.
   652  //	hash := os.NewFile(hashfd, "sha1")
   653  //	// Hash an input string and read the results. Each Write discards
   654  //	// previous hash state. Read always reads the current state.
   655  //	b := make([]byte, 20)
   656  //	for i := 0; i < 2; i++ {
   657  //	    io.WriteString(hash, "Hello, world.")
   658  //	    hash.Read(b)
   659  //	    fmt.Println(hex.EncodeToString(b))
   660  //	}
   661  //	// Output:
   662  //	// 2ae01472317d1935a84797ec1983ae243fc6aa28
   663  //	// 2ae01472317d1935a84797ec1983ae243fc6aa28
   664  //
   665  // For hashing larger byte slices, or byte streams such as those read from
   666  // a file or socket, use Sendto with MSG_MORE to instruct the kernel to update
   667  // the hash digest instead of creating a new one for a given chunk and finalizing it.
   668  //
   669  //	// Assume hashfd and addr are already configured using the setup process.
   670  //	hash := os.NewFile(hashfd, "sha1")
   671  //	// Hash the contents of a file.
   672  //	f, _ := os.Open("/tmp/linux-4.10-rc7.tar.xz")
   673  //	b := make([]byte, 4096)
   674  //	for {
   675  //	    n, err := f.Read(b)
   676  //	    if err == io.EOF {
   677  //	        break
   678  //	    }
   679  //	    unix.Sendto(hashfd, b[:n], unix.MSG_MORE, addr)
   680  //	}
   681  //	hash.Read(b)
   682  //	fmt.Println(hex.EncodeToString(b))
   683  //	// Output: 85cdcad0c06eef66f805ecce353bec9accbeecc5
   684  //
   685  // For more information, see: http://www.chronox.de/crypto-API/crypto/userspace-if.html.
   686  type SockaddrALG struct {
   687  	Type    string
   688  	Name    string
   689  	Feature uint32
   690  	Mask    uint32
   691  	raw     RawSockaddrALG
   692  }
   693  
   694  func (sa *SockaddrALG) sockaddr() (unsafe.Pointer, _Socklen, error) {
   695  	// Leave room for NUL byte terminator.
   696  	if len(sa.Type) > 13 {
   697  		return nil, 0, EINVAL
   698  	}
   699  	if len(sa.Name) > 63 {
   700  		return nil, 0, EINVAL
   701  	}
   702  
   703  	sa.raw.Family = AF_ALG
   704  	sa.raw.Feat = sa.Feature
   705  	sa.raw.Mask = sa.Mask
   706  
   707  	typ, err := ByteSliceFromString(sa.Type)
   708  	if err != nil {
   709  		return nil, 0, err
   710  	}
   711  	name, err := ByteSliceFromString(sa.Name)
   712  	if err != nil {
   713  		return nil, 0, err
   714  	}
   715  
   716  	copy(sa.raw.Type[:], typ)
   717  	copy(sa.raw.Name[:], name)
   718  
   719  	return unsafe.Pointer(&sa.raw), SizeofSockaddrALG, nil
   720  }
   721  
   722  // SockaddrVM implements the Sockaddr interface for AF_VSOCK type sockets.
   723  // SockaddrVM provides access to Linux VM sockets: a mechanism that enables
   724  // bidirectional communication between a hypervisor and its guest virtual
   725  // machines.
   726  type SockaddrVM struct {
   727  	// CID and Port specify a context ID and port address for a VM socket.
   728  	// Guests have a unique CID, and hosts may have a well-known CID of:
   729  	//  - VMADDR_CID_HYPERVISOR: refers to the hypervisor process.
   730  	//  - VMADDR_CID_LOCAL: refers to local communication (loopback).
   731  	//  - VMADDR_CID_HOST: refers to other processes on the host.
   732  	CID   uint32
   733  	Port  uint32
   734  	Flags uint8
   735  	raw   RawSockaddrVM
   736  }
   737  
   738  func (sa *SockaddrVM) sockaddr() (unsafe.Pointer, _Socklen, error) {
   739  	sa.raw.Family = AF_VSOCK
   740  	sa.raw.Port = sa.Port
   741  	sa.raw.Cid = sa.CID
   742  	sa.raw.Flags = sa.Flags
   743  
   744  	return unsafe.Pointer(&sa.raw), SizeofSockaddrVM, nil
   745  }
   746  
   747  type SockaddrXDP struct {
   748  	Flags        uint16
   749  	Ifindex      uint32
   750  	QueueID      uint32
   751  	SharedUmemFD uint32
   752  	raw          RawSockaddrXDP
   753  }
   754  
   755  func (sa *SockaddrXDP) sockaddr() (unsafe.Pointer, _Socklen, error) {
   756  	sa.raw.Family = AF_XDP
   757  	sa.raw.Flags = sa.Flags
   758  	sa.raw.Ifindex = sa.Ifindex
   759  	sa.raw.Queue_id = sa.QueueID
   760  	sa.raw.Shared_umem_fd = sa.SharedUmemFD
   761  
   762  	return unsafe.Pointer(&sa.raw), SizeofSockaddrXDP, nil
   763  }
   764  
   765  // This constant mirrors the #define of PX_PROTO_OE in
   766  // linux/if_pppox.h. We're defining this by hand here instead of
   767  // autogenerating through mkerrors.sh because including
   768  // linux/if_pppox.h causes some declaration conflicts with other
   769  // includes (linux/if_pppox.h includes linux/in.h, which conflicts
   770  // with netinet/in.h). Given that we only need a single zero constant
   771  // out of that file, it's cleaner to just define it by hand here.
   772  const px_proto_oe = 0
   773  
   774  type SockaddrPPPoE struct {
   775  	SID    uint16
   776  	Remote []byte
   777  	Dev    string
   778  	raw    RawSockaddrPPPoX
   779  }
   780  
   781  func (sa *SockaddrPPPoE) sockaddr() (unsafe.Pointer, _Socklen, error) {
   782  	if len(sa.Remote) != 6 {
   783  		return nil, 0, EINVAL
   784  	}
   785  	if len(sa.Dev) > IFNAMSIZ-1 {
   786  		return nil, 0, EINVAL
   787  	}
   788  
   789  	*(*uint16)(unsafe.Pointer(&sa.raw[0])) = AF_PPPOX
   790  	// This next field is in host-endian byte order. We can't use the
   791  	// same unsafe pointer cast as above, because this value is not
   792  	// 32-bit aligned and some architectures don't allow unaligned
   793  	// access.
   794  	//
   795  	// However, the value of px_proto_oe is 0, so we can use
   796  	// encoding/binary helpers to write the bytes without worrying
   797  	// about the ordering.
   798  	binary.BigEndian.PutUint32(sa.raw[2:6], px_proto_oe)
   799  	// This field is deliberately big-endian, unlike the previous
   800  	// one. The kernel expects SID to be in network byte order.
   801  	binary.BigEndian.PutUint16(sa.raw[6:8], sa.SID)
   802  	copy(sa.raw[8:14], sa.Remote)
   803  	for i := 14; i < 14+IFNAMSIZ; i++ {
   804  		sa.raw[i] = 0
   805  	}
   806  	copy(sa.raw[14:], sa.Dev)
   807  	return unsafe.Pointer(&sa.raw), SizeofSockaddrPPPoX, nil
   808  }
   809  
   810  // SockaddrTIPC implements the Sockaddr interface for AF_TIPC type sockets.
   811  // For more information on TIPC, see: http://tipc.sourceforge.net/.
   812  type SockaddrTIPC struct {
   813  	// Scope is the publication scopes when binding service/service range.
   814  	// Should be set to TIPC_CLUSTER_SCOPE or TIPC_NODE_SCOPE.
   815  	Scope int
   816  
   817  	// Addr is the type of address used to manipulate a socket. Addr must be
   818  	// one of:
   819  	//  - *TIPCSocketAddr: "id" variant in the C addr union
   820  	//  - *TIPCServiceRange: "nameseq" variant in the C addr union
   821  	//  - *TIPCServiceName: "name" variant in the C addr union
   822  	//
   823  	// If nil, EINVAL will be returned when the structure is used.
   824  	Addr TIPCAddr
   825  
   826  	raw RawSockaddrTIPC
   827  }
   828  
   829  // TIPCAddr is implemented by types that can be used as an address for
   830  // SockaddrTIPC. It is only implemented by *TIPCSocketAddr, *TIPCServiceRange,
   831  // and *TIPCServiceName.
   832  type TIPCAddr interface {
   833  	tipcAddrtype() uint8
   834  	tipcAddr() [12]byte
   835  }
   836  
   837  func (sa *TIPCSocketAddr) tipcAddr() [12]byte {
   838  	var out [12]byte
   839  	copy(out[:], (*(*[unsafe.Sizeof(TIPCSocketAddr{})]byte)(unsafe.Pointer(sa)))[:])
   840  	return out
   841  }
   842  
   843  func (sa *TIPCSocketAddr) tipcAddrtype() uint8 { return TIPC_SOCKET_ADDR }
   844  
   845  func (sa *TIPCServiceRange) tipcAddr() [12]byte {
   846  	var out [12]byte
   847  	copy(out[:], (*(*[unsafe.Sizeof(TIPCServiceRange{})]byte)(unsafe.Pointer(sa)))[:])
   848  	return out
   849  }
   850  
   851  func (sa *TIPCServiceRange) tipcAddrtype() uint8 { return TIPC_SERVICE_RANGE }
   852  
   853  func (sa *TIPCServiceName) tipcAddr() [12]byte {
   854  	var out [12]byte
   855  	copy(out[:], (*(*[unsafe.Sizeof(TIPCServiceName{})]byte)(unsafe.Pointer(sa)))[:])
   856  	return out
   857  }
   858  
   859  func (sa *TIPCServiceName) tipcAddrtype() uint8 { return TIPC_SERVICE_ADDR }
   860  
   861  func (sa *SockaddrTIPC) sockaddr() (unsafe.Pointer, _Socklen, error) {
   862  	if sa.Addr == nil {
   863  		return nil, 0, EINVAL
   864  	}
   865  	sa.raw.Family = AF_TIPC
   866  	sa.raw.Scope = int8(sa.Scope)
   867  	sa.raw.Addrtype = sa.Addr.tipcAddrtype()
   868  	sa.raw.Addr = sa.Addr.tipcAddr()
   869  	return unsafe.Pointer(&sa.raw), SizeofSockaddrTIPC, nil
   870  }
   871  
   872  // SockaddrL2TPIP implements the Sockaddr interface for IPPROTO_L2TP/AF_INET sockets.
   873  type SockaddrL2TPIP struct {
   874  	Addr   [4]byte
   875  	ConnId uint32
   876  	raw    RawSockaddrL2TPIP
   877  }
   878  
   879  func (sa *SockaddrL2TPIP) sockaddr() (unsafe.Pointer, _Socklen, error) {
   880  	sa.raw.Family = AF_INET
   881  	sa.raw.Conn_id = sa.ConnId
   882  	sa.raw.Addr = sa.Addr
   883  	return unsafe.Pointer(&sa.raw), SizeofSockaddrL2TPIP, nil
   884  }
   885  
   886  // SockaddrL2TPIP6 implements the Sockaddr interface for IPPROTO_L2TP/AF_INET6 sockets.
   887  type SockaddrL2TPIP6 struct {
   888  	Addr   [16]byte
   889  	ZoneId uint32
   890  	ConnId uint32
   891  	raw    RawSockaddrL2TPIP6
   892  }
   893  
   894  func (sa *SockaddrL2TPIP6) sockaddr() (unsafe.Pointer, _Socklen, error) {
   895  	sa.raw.Family = AF_INET6
   896  	sa.raw.Conn_id = sa.ConnId
   897  	sa.raw.Scope_id = sa.ZoneId
   898  	sa.raw.Addr = sa.Addr
   899  	return unsafe.Pointer(&sa.raw), SizeofSockaddrL2TPIP6, nil
   900  }
   901  
   902  // SockaddrIUCV implements the Sockaddr interface for AF_IUCV sockets.
   903  type SockaddrIUCV struct {
   904  	UserID string
   905  	Name   string
   906  	raw    RawSockaddrIUCV
   907  }
   908  
   909  func (sa *SockaddrIUCV) sockaddr() (unsafe.Pointer, _Socklen, error) {
   910  	sa.raw.Family = AF_IUCV
   911  	// These are EBCDIC encoded by the kernel, but we still need to pad them
   912  	// with blanks. Initializing with blanks allows the caller to feed in either
   913  	// a padded or an unpadded string.
   914  	for i := 0; i < 8; i++ {
   915  		sa.raw.Nodeid[i] = ' '
   916  		sa.raw.User_id[i] = ' '
   917  		sa.raw.Name[i] = ' '
   918  	}
   919  	if len(sa.UserID) > 8 || len(sa.Name) > 8 {
   920  		return nil, 0, EINVAL
   921  	}
   922  	for i, b := range []byte(sa.UserID[:]) {
   923  		sa.raw.User_id[i] = int8(b)
   924  	}
   925  	for i, b := range []byte(sa.Name[:]) {
   926  		sa.raw.Name[i] = int8(b)
   927  	}
   928  	return unsafe.Pointer(&sa.raw), SizeofSockaddrIUCV, nil
   929  }
   930  
   931  type SockaddrNFC struct {
   932  	DeviceIdx   uint32
   933  	TargetIdx   uint32
   934  	NFCProtocol uint32
   935  	raw         RawSockaddrNFC
   936  }
   937  
   938  func (sa *SockaddrNFC) sockaddr() (unsafe.Pointer, _Socklen, error) {
   939  	sa.raw.Sa_family = AF_NFC
   940  	sa.raw.Dev_idx = sa.DeviceIdx
   941  	sa.raw.Target_idx = sa.TargetIdx
   942  	sa.raw.Nfc_protocol = sa.NFCProtocol
   943  	return unsafe.Pointer(&sa.raw), SizeofSockaddrNFC, nil
   944  }
   945  
   946  type SockaddrNFCLLCP struct {
   947  	DeviceIdx      uint32
   948  	TargetIdx      uint32
   949  	NFCProtocol    uint32
   950  	DestinationSAP uint8
   951  	SourceSAP      uint8
   952  	ServiceName    string
   953  	raw            RawSockaddrNFCLLCP
   954  }
   955  
   956  func (sa *SockaddrNFCLLCP) sockaddr() (unsafe.Pointer, _Socklen, error) {
   957  	sa.raw.Sa_family = AF_NFC
   958  	sa.raw.Dev_idx = sa.DeviceIdx
   959  	sa.raw.Target_idx = sa.TargetIdx
   960  	sa.raw.Nfc_protocol = sa.NFCProtocol
   961  	sa.raw.Dsap = sa.DestinationSAP
   962  	sa.raw.Ssap = sa.SourceSAP
   963  	if len(sa.ServiceName) > len(sa.raw.Service_name) {
   964  		return nil, 0, EINVAL
   965  	}
   966  	copy(sa.raw.Service_name[:], sa.ServiceName)
   967  	sa.raw.SetServiceNameLen(len(sa.ServiceName))
   968  	return unsafe.Pointer(&sa.raw), SizeofSockaddrNFCLLCP, nil
   969  }
   970  
   971  var socketProtocol = func(fd int) (int, error) {
   972  	return GetsockoptInt(fd, SOL_SOCKET, SO_PROTOCOL)
   973  }
   974  
   975  func anyToSockaddr(fd int, rsa *RawSockaddrAny) (Sockaddr, error) {
   976  	switch rsa.Addr.Family {
   977  	case AF_NETLINK:
   978  		pp := (*RawSockaddrNetlink)(unsafe.Pointer(rsa))
   979  		sa := new(SockaddrNetlink)
   980  		sa.Family = pp.Family
   981  		sa.Pad = pp.Pad
   982  		sa.Pid = pp.Pid
   983  		sa.Groups = pp.Groups
   984  		return sa, nil
   985  
   986  	case AF_PACKET:
   987  		pp := (*RawSockaddrLinklayer)(unsafe.Pointer(rsa))
   988  		sa := new(SockaddrLinklayer)
   989  		sa.Protocol = pp.Protocol
   990  		sa.Ifindex = int(pp.Ifindex)
   991  		sa.Hatype = pp.Hatype
   992  		sa.Pkttype = pp.Pkttype
   993  		sa.Halen = pp.Halen
   994  		sa.Addr = pp.Addr
   995  		return sa, nil
   996  
   997  	case AF_UNIX:
   998  		pp := (*RawSockaddrUnix)(unsafe.Pointer(rsa))
   999  		sa := new(SockaddrUnix)
  1000  		if pp.Path[0] == 0 {
  1001  			// "Abstract" Unix domain socket.
  1002  			// Rewrite leading NUL as @ for textual display.
  1003  			// (This is the standard convention.)
  1004  			// Not friendly to overwrite in place,
  1005  			// but the callers below don't care.
  1006  			pp.Path[0] = '@'
  1007  		}
  1008  
  1009  		// Assume path ends at NUL.
  1010  		// This is not technically the Linux semantics for
  1011  		// abstract Unix domain sockets--they are supposed
  1012  		// to be uninterpreted fixed-size binary blobs--but
  1013  		// everyone uses this convention.
  1014  		n := 0
  1015  		for n < len(pp.Path) && pp.Path[n] != 0 {
  1016  			n++
  1017  		}
  1018  		bytes := (*[len(pp.Path)]byte)(unsafe.Pointer(&pp.Path[0]))[0:n]
  1019  		sa.Name = string(bytes)
  1020  		return sa, nil
  1021  
  1022  	case AF_INET:
  1023  		proto, err := socketProtocol(fd)
  1024  		if err != nil {
  1025  			return nil, err
  1026  		}
  1027  
  1028  		switch proto {
  1029  		case IPPROTO_L2TP:
  1030  			pp := (*RawSockaddrL2TPIP)(unsafe.Pointer(rsa))
  1031  			sa := new(SockaddrL2TPIP)
  1032  			sa.ConnId = pp.Conn_id
  1033  			sa.Addr = pp.Addr
  1034  			return sa, nil
  1035  		default:
  1036  			pp := (*RawSockaddrInet4)(unsafe.Pointer(rsa))
  1037  			sa := new(SockaddrInet4)
  1038  			p := (*[2]byte)(unsafe.Pointer(&pp.Port))
  1039  			sa.Port = int(p[0])<<8 + int(p[1])
  1040  			sa.Addr = pp.Addr
  1041  			return sa, nil
  1042  		}
  1043  
  1044  	case AF_INET6:
  1045  		proto, err := socketProtocol(fd)
  1046  		if err != nil {
  1047  			return nil, err
  1048  		}
  1049  
  1050  		switch proto {
  1051  		case IPPROTO_L2TP:
  1052  			pp := (*RawSockaddrL2TPIP6)(unsafe.Pointer(rsa))
  1053  			sa := new(SockaddrL2TPIP6)
  1054  			sa.ConnId = pp.Conn_id
  1055  			sa.ZoneId = pp.Scope_id
  1056  			sa.Addr = pp.Addr
  1057  			return sa, nil
  1058  		default:
  1059  			pp := (*RawSockaddrInet6)(unsafe.Pointer(rsa))
  1060  			sa := new(SockaddrInet6)
  1061  			p := (*[2]byte)(unsafe.Pointer(&pp.Port))
  1062  			sa.Port = int(p[0])<<8 + int(p[1])
  1063  			sa.ZoneId = pp.Scope_id
  1064  			sa.Addr = pp.Addr
  1065  			return sa, nil
  1066  		}
  1067  
  1068  	case AF_VSOCK:
  1069  		pp := (*RawSockaddrVM)(unsafe.Pointer(rsa))
  1070  		sa := &SockaddrVM{
  1071  			CID:   pp.Cid,
  1072  			Port:  pp.Port,
  1073  			Flags: pp.Flags,
  1074  		}
  1075  		return sa, nil
  1076  	case AF_BLUETOOTH:
  1077  		proto, err := socketProtocol(fd)
  1078  		if err != nil {
  1079  			return nil, err
  1080  		}
  1081  		// only BTPROTO_L2CAP and BTPROTO_RFCOMM can accept connections
  1082  		switch proto {
  1083  		case BTPROTO_L2CAP:
  1084  			pp := (*RawSockaddrL2)(unsafe.Pointer(rsa))
  1085  			sa := &SockaddrL2{
  1086  				PSM:      pp.Psm,
  1087  				CID:      pp.Cid,
  1088  				Addr:     pp.Bdaddr,
  1089  				AddrType: pp.Bdaddr_type,
  1090  			}
  1091  			return sa, nil
  1092  		case BTPROTO_RFCOMM:
  1093  			pp := (*RawSockaddrRFCOMM)(unsafe.Pointer(rsa))
  1094  			sa := &SockaddrRFCOMM{
  1095  				Channel: pp.Channel,
  1096  				Addr:    pp.Bdaddr,
  1097  			}
  1098  			return sa, nil
  1099  		}
  1100  	case AF_XDP:
  1101  		pp := (*RawSockaddrXDP)(unsafe.Pointer(rsa))
  1102  		sa := &SockaddrXDP{
  1103  			Flags:        pp.Flags,
  1104  			Ifindex:      pp.Ifindex,
  1105  			QueueID:      pp.Queue_id,
  1106  			SharedUmemFD: pp.Shared_umem_fd,
  1107  		}
  1108  		return sa, nil
  1109  	case AF_PPPOX:
  1110  		pp := (*RawSockaddrPPPoX)(unsafe.Pointer(rsa))
  1111  		if binary.BigEndian.Uint32(pp[2:6]) != px_proto_oe {
  1112  			return nil, EINVAL
  1113  		}
  1114  		sa := &SockaddrPPPoE{
  1115  			SID:    binary.BigEndian.Uint16(pp[6:8]),
  1116  			Remote: pp[8:14],
  1117  		}
  1118  		for i := 14; i < 14+IFNAMSIZ; i++ {
  1119  			if pp[i] == 0 {
  1120  				sa.Dev = string(pp[14:i])
  1121  				break
  1122  			}
  1123  		}
  1124  		return sa, nil
  1125  	case AF_TIPC:
  1126  		pp := (*RawSockaddrTIPC)(unsafe.Pointer(rsa))
  1127  
  1128  		sa := &SockaddrTIPC{
  1129  			Scope: int(pp.Scope),
  1130  		}
  1131  
  1132  		// Determine which union variant is present in pp.Addr by checking
  1133  		// pp.Addrtype.
  1134  		switch pp.Addrtype {
  1135  		case TIPC_SERVICE_RANGE:
  1136  			sa.Addr = (*TIPCServiceRange)(unsafe.Pointer(&pp.Addr))
  1137  		case TIPC_SERVICE_ADDR:
  1138  			sa.Addr = (*TIPCServiceName)(unsafe.Pointer(&pp.Addr))
  1139  		case TIPC_SOCKET_ADDR:
  1140  			sa.Addr = (*TIPCSocketAddr)(unsafe.Pointer(&pp.Addr))
  1141  		default:
  1142  			return nil, EINVAL
  1143  		}
  1144  
  1145  		return sa, nil
  1146  	case AF_IUCV:
  1147  		pp := (*RawSockaddrIUCV)(unsafe.Pointer(rsa))
  1148  
  1149  		var user [8]byte
  1150  		var name [8]byte
  1151  
  1152  		for i := 0; i < 8; i++ {
  1153  			user[i] = byte(pp.User_id[i])
  1154  			name[i] = byte(pp.Name[i])
  1155  		}
  1156  
  1157  		sa := &SockaddrIUCV{
  1158  			UserID: string(user[:]),
  1159  			Name:   string(name[:]),
  1160  		}
  1161  		return sa, nil
  1162  
  1163  	case AF_CAN:
  1164  		proto, err := socketProtocol(fd)
  1165  		if err != nil {
  1166  			return nil, err
  1167  		}
  1168  
  1169  		pp := (*RawSockaddrCAN)(unsafe.Pointer(rsa))
  1170  
  1171  		switch proto {
  1172  		case CAN_J1939:
  1173  			sa := &SockaddrCANJ1939{
  1174  				Ifindex: int(pp.Ifindex),
  1175  			}
  1176  			name := (*[8]byte)(unsafe.Pointer(&sa.Name))
  1177  			for i := 0; i < 8; i++ {
  1178  				name[i] = pp.Addr[i]
  1179  			}
  1180  			pgn := (*[4]byte)(unsafe.Pointer(&sa.PGN))
  1181  			for i := 0; i < 4; i++ {
  1182  				pgn[i] = pp.Addr[i+8]
  1183  			}
  1184  			addr := (*[1]byte)(unsafe.Pointer(&sa.Addr))
  1185  			addr[0] = pp.Addr[12]
  1186  			return sa, nil
  1187  		default:
  1188  			sa := &SockaddrCAN{
  1189  				Ifindex: int(pp.Ifindex),
  1190  			}
  1191  			rx := (*[4]byte)(unsafe.Pointer(&sa.RxID))
  1192  			for i := 0; i < 4; i++ {
  1193  				rx[i] = pp.Addr[i]
  1194  			}
  1195  			tx := (*[4]byte)(unsafe.Pointer(&sa.TxID))
  1196  			for i := 0; i < 4; i++ {
  1197  				tx[i] = pp.Addr[i+4]
  1198  			}
  1199  			return sa, nil
  1200  		}
  1201  	case AF_NFC:
  1202  		proto, err := socketProtocol(fd)
  1203  		if err != nil {
  1204  			return nil, err
  1205  		}
  1206  		switch proto {
  1207  		case NFC_SOCKPROTO_RAW:
  1208  			pp := (*RawSockaddrNFC)(unsafe.Pointer(rsa))
  1209  			sa := &SockaddrNFC{
  1210  				DeviceIdx:   pp.Dev_idx,
  1211  				TargetIdx:   pp.Target_idx,
  1212  				NFCProtocol: pp.Nfc_protocol,
  1213  			}
  1214  			return sa, nil
  1215  		case NFC_SOCKPROTO_LLCP:
  1216  			pp := (*RawSockaddrNFCLLCP)(unsafe.Pointer(rsa))
  1217  			if uint64(pp.Service_name_len) > uint64(len(pp.Service_name)) {
  1218  				return nil, EINVAL
  1219  			}
  1220  			sa := &SockaddrNFCLLCP{
  1221  				DeviceIdx:      pp.Dev_idx,
  1222  				TargetIdx:      pp.Target_idx,
  1223  				NFCProtocol:    pp.Nfc_protocol,
  1224  				DestinationSAP: pp.Dsap,
  1225  				SourceSAP:      pp.Ssap,
  1226  				ServiceName:    string(pp.Service_name[:pp.Service_name_len]),
  1227  			}
  1228  			return sa, nil
  1229  		default:
  1230  			return nil, EINVAL
  1231  		}
  1232  	}
  1233  	return nil, EAFNOSUPPORT
  1234  }
  1235  
  1236  func Accept(fd int) (nfd int, sa Sockaddr, err error) {
  1237  	var rsa RawSockaddrAny
  1238  	var len _Socklen = SizeofSockaddrAny
  1239  	nfd, err = accept4(fd, &rsa, &len, 0)
  1240  	if err != nil {
  1241  		return
  1242  	}
  1243  	sa, err = anyToSockaddr(fd, &rsa)
  1244  	if err != nil {
  1245  		Close(nfd)
  1246  		nfd = 0
  1247  	}
  1248  	return
  1249  }
  1250  
  1251  func Accept4(fd int, flags int) (nfd int, sa Sockaddr, err error) {
  1252  	var rsa RawSockaddrAny
  1253  	var len _Socklen = SizeofSockaddrAny
  1254  	nfd, err = accept4(fd, &rsa, &len, flags)
  1255  	if err != nil {
  1256  		return
  1257  	}
  1258  	if len > SizeofSockaddrAny {
  1259  		panic("RawSockaddrAny too small")
  1260  	}
  1261  	sa, err = anyToSockaddr(fd, &rsa)
  1262  	if err != nil {
  1263  		Close(nfd)
  1264  		nfd = 0
  1265  	}
  1266  	return
  1267  }
  1268  
  1269  func Getsockname(fd int) (sa Sockaddr, err error) {
  1270  	var rsa RawSockaddrAny
  1271  	var len _Socklen = SizeofSockaddrAny
  1272  	if err = getsockname(fd, &rsa, &len); err != nil {
  1273  		return
  1274  	}
  1275  	return anyToSockaddr(fd, &rsa)
  1276  }
  1277  
  1278  func GetsockoptIPMreqn(fd, level, opt int) (*IPMreqn, error) {
  1279  	var value IPMreqn
  1280  	vallen := _Socklen(SizeofIPMreqn)
  1281  	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
  1282  	return &value, err
  1283  }
  1284  
  1285  func GetsockoptUcred(fd, level, opt int) (*Ucred, error) {
  1286  	var value Ucred
  1287  	vallen := _Socklen(SizeofUcred)
  1288  	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
  1289  	return &value, err
  1290  }
  1291  
  1292  func GetsockoptTCPInfo(fd, level, opt int) (*TCPInfo, error) {
  1293  	var value TCPInfo
  1294  	vallen := _Socklen(SizeofTCPInfo)
  1295  	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
  1296  	return &value, err
  1297  }
  1298  
  1299  // GetsockoptString returns the string value of the socket option opt for the
  1300  // socket associated with fd at the given socket level.
  1301  func GetsockoptString(fd, level, opt int) (string, error) {
  1302  	buf := make([]byte, 256)
  1303  	vallen := _Socklen(len(buf))
  1304  	err := getsockopt(fd, level, opt, unsafe.Pointer(&buf[0]), &vallen)
  1305  	if err != nil {
  1306  		if err == ERANGE {
  1307  			buf = make([]byte, vallen)
  1308  			err = getsockopt(fd, level, opt, unsafe.Pointer(&buf[0]), &vallen)
  1309  		}
  1310  		if err != nil {
  1311  			return "", err
  1312  		}
  1313  	}
  1314  	return string(buf[:vallen-1]), nil
  1315  }
  1316  
  1317  func GetsockoptTpacketStats(fd, level, opt int) (*TpacketStats, error) {
  1318  	var value TpacketStats
  1319  	vallen := _Socklen(SizeofTpacketStats)
  1320  	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
  1321  	return &value, err
  1322  }
  1323  
  1324  func GetsockoptTpacketStatsV3(fd, level, opt int) (*TpacketStatsV3, error) {
  1325  	var value TpacketStatsV3
  1326  	vallen := _Socklen(SizeofTpacketStatsV3)
  1327  	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
  1328  	return &value, err
  1329  }
  1330  
  1331  func SetsockoptIPMreqn(fd, level, opt int, mreq *IPMreqn) (err error) {
  1332  	return setsockopt(fd, level, opt, unsafe.Pointer(mreq), unsafe.Sizeof(*mreq))
  1333  }
  1334  
  1335  func SetsockoptPacketMreq(fd, level, opt int, mreq *PacketMreq) error {
  1336  	return setsockopt(fd, level, opt, unsafe.Pointer(mreq), unsafe.Sizeof(*mreq))
  1337  }
  1338  
  1339  // SetsockoptSockFprog attaches a classic BPF or an extended BPF program to a
  1340  // socket to filter incoming packets.  See 'man 7 socket' for usage information.
  1341  func SetsockoptSockFprog(fd, level, opt int, fprog *SockFprog) error {
  1342  	return setsockopt(fd, level, opt, unsafe.Pointer(fprog), unsafe.Sizeof(*fprog))
  1343  }
  1344  
  1345  func SetsockoptCanRawFilter(fd, level, opt int, filter []CanFilter) error {
  1346  	var p unsafe.Pointer
  1347  	if len(filter) > 0 {
  1348  		p = unsafe.Pointer(&filter[0])
  1349  	}
  1350  	return setsockopt(fd, level, opt, p, uintptr(len(filter)*SizeofCanFilter))
  1351  }
  1352  
  1353  func SetsockoptTpacketReq(fd, level, opt int, tp *TpacketReq) error {
  1354  	return setsockopt(fd, level, opt, unsafe.Pointer(tp), unsafe.Sizeof(*tp))
  1355  }
  1356  
  1357  func SetsockoptTpacketReq3(fd, level, opt int, tp *TpacketReq3) error {
  1358  	return setsockopt(fd, level, opt, unsafe.Pointer(tp), unsafe.Sizeof(*tp))
  1359  }
  1360  
  1361  func SetsockoptTCPRepairOpt(fd, level, opt int, o []TCPRepairOpt) (err error) {
  1362  	if len(o) == 0 {
  1363  		return EINVAL
  1364  	}
  1365  	return setsockopt(fd, level, opt, unsafe.Pointer(&o[0]), uintptr(SizeofTCPRepairOpt*len(o)))
  1366  }
  1367  
  1368  // Keyctl Commands (http://man7.org/linux/man-pages/man2/keyctl.2.html)
  1369  
  1370  // KeyctlInt calls keyctl commands in which each argument is an int.
  1371  // These commands are KEYCTL_REVOKE, KEYCTL_CHOWN, KEYCTL_CLEAR, KEYCTL_LINK,
  1372  // KEYCTL_UNLINK, KEYCTL_NEGATE, KEYCTL_SET_REQKEY_KEYRING, KEYCTL_SET_TIMEOUT,
  1373  // KEYCTL_ASSUME_AUTHORITY, KEYCTL_SESSION_TO_PARENT, KEYCTL_REJECT,
  1374  // KEYCTL_INVALIDATE, and KEYCTL_GET_PERSISTENT.
  1375  //sys	KeyctlInt(cmd int, arg2 int, arg3 int, arg4 int, arg5 int) (ret int, err error) = SYS_KEYCTL
  1376  
  1377  // KeyctlBuffer calls keyctl commands in which the third and fourth
  1378  // arguments are a buffer and its length, respectively.
  1379  // These commands are KEYCTL_UPDATE, KEYCTL_READ, and KEYCTL_INSTANTIATE.
  1380  //sys	KeyctlBuffer(cmd int, arg2 int, buf []byte, arg5 int) (ret int, err error) = SYS_KEYCTL
  1381  
  1382  // KeyctlString calls keyctl commands which return a string.
  1383  // These commands are KEYCTL_DESCRIBE and KEYCTL_GET_SECURITY.
  1384  func KeyctlString(cmd int, id int) (string, error) {
  1385  	// We must loop as the string data may change in between the syscalls.
  1386  	// We could allocate a large buffer here to reduce the chance that the
  1387  	// syscall needs to be called twice; however, this is unnecessary as
  1388  	// the performance loss is negligible.
  1389  	var buffer []byte
  1390  	for {
  1391  		// Try to fill the buffer with data
  1392  		length, err := KeyctlBuffer(cmd, id, buffer, 0)
  1393  		if err != nil {
  1394  			return "", err
  1395  		}
  1396  
  1397  		// Check if the data was written
  1398  		if length <= len(buffer) {
  1399  			// Exclude the null terminator
  1400  			return string(buffer[:length-1]), nil
  1401  		}
  1402  
  1403  		// Make a bigger buffer if needed
  1404  		buffer = make([]byte, length)
  1405  	}
  1406  }
  1407  
  1408  // Keyctl commands with special signatures.
  1409  
  1410  // KeyctlGetKeyringID implements the KEYCTL_GET_KEYRING_ID command.
  1411  // See the full documentation at:
  1412  // http://man7.org/linux/man-pages/man3/keyctl_get_keyring_ID.3.html
  1413  func KeyctlGetKeyringID(id int, create bool) (ringid int, err error) {
  1414  	createInt := 0
  1415  	if create {
  1416  		createInt = 1
  1417  	}
  1418  	return KeyctlInt(KEYCTL_GET_KEYRING_ID, id, createInt, 0, 0)
  1419  }
  1420  
  1421  // KeyctlSetperm implements the KEYCTL_SETPERM command. The perm value is the
  1422  // key handle permission mask as described in the "keyctl setperm" section of
  1423  // http://man7.org/linux/man-pages/man1/keyctl.1.html.
  1424  // See the full documentation at:
  1425  // http://man7.org/linux/man-pages/man3/keyctl_setperm.3.html
  1426  func KeyctlSetperm(id int, perm uint32) error {
  1427  	_, err := KeyctlInt(KEYCTL_SETPERM, id, int(perm), 0, 0)
  1428  	return err
  1429  }
  1430  
  1431  //sys	keyctlJoin(cmd int, arg2 string) (ret int, err error) = SYS_KEYCTL
  1432  
  1433  // KeyctlJoinSessionKeyring implements the KEYCTL_JOIN_SESSION_KEYRING command.
  1434  // See the full documentation at:
  1435  // http://man7.org/linux/man-pages/man3/keyctl_join_session_keyring.3.html
  1436  func KeyctlJoinSessionKeyring(name string) (ringid int, err error) {
  1437  	return keyctlJoin(KEYCTL_JOIN_SESSION_KEYRING, name)
  1438  }
  1439  
  1440  //sys	keyctlSearch(cmd int, arg2 int, arg3 string, arg4 string, arg5 int) (ret int, err error) = SYS_KEYCTL
  1441  
  1442  // KeyctlSearch implements the KEYCTL_SEARCH command.
  1443  // See the full documentation at:
  1444  // http://man7.org/linux/man-pages/man3/keyctl_search.3.html
  1445  func KeyctlSearch(ringid int, keyType, description string, destRingid int) (id int, err error) {
  1446  	return keyctlSearch(KEYCTL_SEARCH, ringid, keyType, description, destRingid)
  1447  }
  1448  
  1449  //sys	keyctlIOV(cmd int, arg2 int, payload []Iovec, arg5 int) (err error) = SYS_KEYCTL
  1450  
  1451  // KeyctlInstantiateIOV implements the KEYCTL_INSTANTIATE_IOV command. This
  1452  // command is similar to KEYCTL_INSTANTIATE, except that the payload is a slice
  1453  // of Iovec (each of which represents a buffer) instead of a single buffer.
  1454  // See the full documentation at:
  1455  // http://man7.org/linux/man-pages/man3/keyctl_instantiate_iov.3.html
  1456  func KeyctlInstantiateIOV(id int, payload []Iovec, ringid int) error {
  1457  	return keyctlIOV(KEYCTL_INSTANTIATE_IOV, id, payload, ringid)
  1458  }
  1459  
  1460  //sys	keyctlDH(cmd int, arg2 *KeyctlDHParams, buf []byte) (ret int, err error) = SYS_KEYCTL
  1461  
  1462  // KeyctlDHCompute implements the KEYCTL_DH_COMPUTE command. This command
  1463  // computes a Diffie-Hellman shared secret based on the provide params. The
  1464  // secret is written to the provided buffer and the returned size is the number
  1465  // of bytes written (returning an error if there is insufficient space in the
  1466  // buffer). If a nil buffer is passed in, this function returns the minimum
  1467  // buffer length needed to store the appropriate data. Note that this differs
  1468  // from KEYCTL_READ's behavior which always returns the requested payload size.
  1469  // See the full documentation at:
  1470  // http://man7.org/linux/man-pages/man3/keyctl_dh_compute.3.html
  1471  func KeyctlDHCompute(params *KeyctlDHParams, buffer []byte) (size int, err error) {
  1472  	return keyctlDH(KEYCTL_DH_COMPUTE, params, buffer)
  1473  }
  1474  
  1475  // KeyctlRestrictKeyring implements the KEYCTL_RESTRICT_KEYRING command. This
  1476  // command limits the set of keys that can be linked to the keyring, regardless
  1477  // of keyring permissions. The command requires the "setattr" permission.
  1478  //
  1479  // When called with an empty keyType the command locks the keyring, preventing
  1480  // any further keys from being linked to the keyring.
  1481  //
  1482  // The "asymmetric" keyType defines restrictions requiring key payloads to be
  1483  // DER encoded X.509 certificates signed by keys in another keyring. Restrictions
  1484  // for "asymmetric" include "builtin_trusted", "builtin_and_secondary_trusted",
  1485  // "key_or_keyring:<key>", and "key_or_keyring:<key>:chain".
  1486  //
  1487  // As of Linux 4.12, only the "asymmetric" keyType defines type-specific
  1488  // restrictions.
  1489  //
  1490  // See the full documentation at:
  1491  // http://man7.org/linux/man-pages/man3/keyctl_restrict_keyring.3.html
  1492  // http://man7.org/linux/man-pages/man2/keyctl.2.html
  1493  func KeyctlRestrictKeyring(ringid int, keyType string, restriction string) error {
  1494  	if keyType == "" {
  1495  		return keyctlRestrictKeyring(KEYCTL_RESTRICT_KEYRING, ringid)
  1496  	}
  1497  	return keyctlRestrictKeyringByType(KEYCTL_RESTRICT_KEYRING, ringid, keyType, restriction)
  1498  }
  1499  
  1500  //sys	keyctlRestrictKeyringByType(cmd int, arg2 int, keyType string, restriction string) (err error) = SYS_KEYCTL
  1501  //sys	keyctlRestrictKeyring(cmd int, arg2 int) (err error) = SYS_KEYCTL
  1502  
  1503  func recvmsgRaw(fd int, iov []Iovec, oob []byte, flags int, rsa *RawSockaddrAny) (n, oobn int, recvflags int, err error) {
  1504  	var msg Msghdr
  1505  	msg.Name = (*byte)(unsafe.Pointer(rsa))
  1506  	msg.Namelen = uint32(SizeofSockaddrAny)
  1507  	var dummy byte
  1508  	if len(oob) > 0 {
  1509  		if emptyIovecs(iov) {
  1510  			var sockType int
  1511  			sockType, err = GetsockoptInt(fd, SOL_SOCKET, SO_TYPE)
  1512  			if err != nil {
  1513  				return
  1514  			}
  1515  			// receive at least one normal byte
  1516  			if sockType != SOCK_DGRAM {
  1517  				var iova [1]Iovec
  1518  				iova[0].Base = &dummy
  1519  				iova[0].SetLen(1)
  1520  				iov = iova[:]
  1521  			}
  1522  		}
  1523  		msg.Control = &oob[0]
  1524  		msg.SetControllen(len(oob))
  1525  	}
  1526  	if len(iov) > 0 {
  1527  		msg.Iov = &iov[0]
  1528  		msg.SetIovlen(len(iov))
  1529  	}
  1530  	if n, err = recvmsg(fd, &msg, flags); err != nil {
  1531  		return
  1532  	}
  1533  	oobn = int(msg.Controllen)
  1534  	recvflags = int(msg.Flags)
  1535  	return
  1536  }
  1537  
  1538  func sendmsgN(fd int, iov []Iovec, oob []byte, ptr unsafe.Pointer, salen _Socklen, flags int) (n int, err error) {
  1539  	var msg Msghdr
  1540  	msg.Name = (*byte)(ptr)
  1541  	msg.Namelen = uint32(salen)
  1542  	var dummy byte
  1543  	var empty bool
  1544  	if len(oob) > 0 {
  1545  		empty = emptyIovecs(iov)
  1546  		if empty {
  1547  			var sockType int
  1548  			sockType, err = GetsockoptInt(fd, SOL_SOCKET, SO_TYPE)
  1549  			if err != nil {
  1550  				return 0, err
  1551  			}
  1552  			// send at least one normal byte
  1553  			if sockType != SOCK_DGRAM {
  1554  				var iova [1]Iovec
  1555  				iova[0].Base = &dummy
  1556  				iova[0].SetLen(1)
  1557  				iov = iova[:]
  1558  			}
  1559  		}
  1560  		msg.Control = &oob[0]
  1561  		msg.SetControllen(len(oob))
  1562  	}
  1563  	if len(iov) > 0 {
  1564  		msg.Iov = &iov[0]
  1565  		msg.SetIovlen(len(iov))
  1566  	}
  1567  	if n, err = sendmsg(fd, &msg, flags); err != nil {
  1568  		return 0, err
  1569  	}
  1570  	if len(oob) > 0 && empty {
  1571  		n = 0
  1572  	}
  1573  	return n, nil
  1574  }
  1575  
  1576  // BindToDevice binds the socket associated with fd to device.
  1577  func BindToDevice(fd int, device string) (err error) {
  1578  	return SetsockoptString(fd, SOL_SOCKET, SO_BINDTODEVICE, device)
  1579  }
  1580  
  1581  //sys	ptrace(request int, pid int, addr uintptr, data uintptr) (err error)
  1582  
  1583  func ptracePeek(req int, pid int, addr uintptr, out []byte) (count int, err error) {
  1584  	// The peek requests are machine-size oriented, so we wrap it
  1585  	// to retrieve arbitrary-length data.
  1586  
  1587  	// The ptrace syscall differs from glibc's ptrace.
  1588  	// Peeks returns the word in *data, not as the return value.
  1589  
  1590  	var buf [SizeofPtr]byte
  1591  
  1592  	// Leading edge. PEEKTEXT/PEEKDATA don't require aligned
  1593  	// access (PEEKUSER warns that it might), but if we don't
  1594  	// align our reads, we might straddle an unmapped page
  1595  	// boundary and not get the bytes leading up to the page
  1596  	// boundary.
  1597  	n := 0
  1598  	if addr%SizeofPtr != 0 {
  1599  		err = ptrace(req, pid, addr-addr%SizeofPtr, uintptr(unsafe.Pointer(&buf[0])))
  1600  		if err != nil {
  1601  			return 0, err
  1602  		}
  1603  		n += copy(out, buf[addr%SizeofPtr:])
  1604  		out = out[n:]
  1605  	}
  1606  
  1607  	// Remainder.
  1608  	for len(out) > 0 {
  1609  		// We use an internal buffer to guarantee alignment.
  1610  		// It's not documented if this is necessary, but we're paranoid.
  1611  		err = ptrace(req, pid, addr+uintptr(n), uintptr(unsafe.Pointer(&buf[0])))
  1612  		if err != nil {
  1613  			return n, err
  1614  		}
  1615  		copied := copy(out, buf[0:])
  1616  		n += copied
  1617  		out = out[copied:]
  1618  	}
  1619  
  1620  	return n, nil
  1621  }
  1622  
  1623  func PtracePeekText(pid int, addr uintptr, out []byte) (count int, err error) {
  1624  	return ptracePeek(PTRACE_PEEKTEXT, pid, addr, out)
  1625  }
  1626  
  1627  func PtracePeekData(pid int, addr uintptr, out []byte) (count int, err error) {
  1628  	return ptracePeek(PTRACE_PEEKDATA, pid, addr, out)
  1629  }
  1630  
  1631  func PtracePeekUser(pid int, addr uintptr, out []byte) (count int, err error) {
  1632  	return ptracePeek(PTRACE_PEEKUSR, pid, addr, out)
  1633  }
  1634  
  1635  func ptracePoke(pokeReq int, peekReq int, pid int, addr uintptr, data []byte) (count int, err error) {
  1636  	// As for ptracePeek, we need to align our accesses to deal
  1637  	// with the possibility of straddling an invalid page.
  1638  
  1639  	// Leading edge.
  1640  	n := 0
  1641  	if addr%SizeofPtr != 0 {
  1642  		var buf [SizeofPtr]byte
  1643  		err = ptrace(peekReq, pid, addr-addr%SizeofPtr, uintptr(unsafe.Pointer(&buf[0])))
  1644  		if err != nil {
  1645  			return 0, err
  1646  		}
  1647  		n += copy(buf[addr%SizeofPtr:], data)
  1648  		word := *((*uintptr)(unsafe.Pointer(&buf[0])))
  1649  		err = ptrace(pokeReq, pid, addr-addr%SizeofPtr, word)
  1650  		if err != nil {
  1651  			return 0, err
  1652  		}
  1653  		data = data[n:]
  1654  	}
  1655  
  1656  	// Interior.
  1657  	for len(data) > SizeofPtr {
  1658  		word := *((*uintptr)(unsafe.Pointer(&data[0])))
  1659  		err = ptrace(pokeReq, pid, addr+uintptr(n), word)
  1660  		if err != nil {
  1661  			return n, err
  1662  		}
  1663  		n += SizeofPtr
  1664  		data = data[SizeofPtr:]
  1665  	}
  1666  
  1667  	// Trailing edge.
  1668  	if len(data) > 0 {
  1669  		var buf [SizeofPtr]byte
  1670  		err = ptrace(peekReq, pid, addr+uintptr(n), uintptr(unsafe.Pointer(&buf[0])))
  1671  		if err != nil {
  1672  			return n, err
  1673  		}
  1674  		copy(buf[0:], data)
  1675  		word := *((*uintptr)(unsafe.Pointer(&buf[0])))
  1676  		err = ptrace(pokeReq, pid, addr+uintptr(n), word)
  1677  		if err != nil {
  1678  			return n, err
  1679  		}
  1680  		n += len(data)
  1681  	}
  1682  
  1683  	return n, nil
  1684  }
  1685  
  1686  func PtracePokeText(pid int, addr uintptr, data []byte) (count int, err error) {
  1687  	return ptracePoke(PTRACE_POKETEXT, PTRACE_PEEKTEXT, pid, addr, data)
  1688  }
  1689  
  1690  func PtracePokeData(pid int, addr uintptr, data []byte) (count int, err error) {
  1691  	return ptracePoke(PTRACE_POKEDATA, PTRACE_PEEKDATA, pid, addr, data)
  1692  }
  1693  
  1694  func PtracePokeUser(pid int, addr uintptr, data []byte) (count int, err error) {
  1695  	return ptracePoke(PTRACE_POKEUSR, PTRACE_PEEKUSR, pid, addr, data)
  1696  }
  1697  
  1698  func PtraceGetRegs(pid int, regsout *PtraceRegs) (err error) {
  1699  	return ptrace(PTRACE_GETREGS, pid, 0, uintptr(unsafe.Pointer(regsout)))
  1700  }
  1701  
  1702  func PtraceSetRegs(pid int, regs *PtraceRegs) (err error) {
  1703  	return ptrace(PTRACE_SETREGS, pid, 0, uintptr(unsafe.Pointer(regs)))
  1704  }
  1705  
  1706  func PtraceSetOptions(pid int, options int) (err error) {
  1707  	return ptrace(PTRACE_SETOPTIONS, pid, 0, uintptr(options))
  1708  }
  1709  
  1710  func PtraceGetEventMsg(pid int) (msg uint, err error) {
  1711  	var data _C_long
  1712  	err = ptrace(PTRACE_GETEVENTMSG, pid, 0, uintptr(unsafe.Pointer(&data)))
  1713  	msg = uint(data)
  1714  	return
  1715  }
  1716  
  1717  func PtraceCont(pid int, signal int) (err error) {
  1718  	return ptrace(PTRACE_CONT, pid, 0, uintptr(signal))
  1719  }
  1720  
  1721  func PtraceSyscall(pid int, signal int) (err error) {
  1722  	return ptrace(PTRACE_SYSCALL, pid, 0, uintptr(signal))
  1723  }
  1724  
  1725  func PtraceSingleStep(pid int) (err error) { return ptrace(PTRACE_SINGLESTEP, pid, 0, 0) }
  1726  
  1727  func PtraceInterrupt(pid int) (err error) { return ptrace(PTRACE_INTERRUPT, pid, 0, 0) }
  1728  
  1729  func PtraceAttach(pid int) (err error) { return ptrace(PTRACE_ATTACH, pid, 0, 0) }
  1730  
  1731  func PtraceSeize(pid int) (err error) { return ptrace(PTRACE_SEIZE, pid, 0, 0) }
  1732  
  1733  func PtraceDetach(pid int) (err error) { return ptrace(PTRACE_DETACH, pid, 0, 0) }
  1734  
  1735  //sys	reboot(magic1 uint, magic2 uint, cmd int, arg string) (err error)
  1736  
  1737  func Reboot(cmd int) (err error) {
  1738  	return reboot(LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2, cmd, "")
  1739  }
  1740  
  1741  func direntIno(buf []byte) (uint64, bool) {
  1742  	return readInt(buf, unsafe.Offsetof(Dirent{}.Ino), unsafe.Sizeof(Dirent{}.Ino))
  1743  }
  1744  
  1745  func direntReclen(buf []byte) (uint64, bool) {
  1746  	return readInt(buf, unsafe.Offsetof(Dirent{}.Reclen), unsafe.Sizeof(Dirent{}.Reclen))
  1747  }
  1748  
  1749  func direntNamlen(buf []byte) (uint64, bool) {
  1750  	reclen, ok := direntReclen(buf)
  1751  	if !ok {
  1752  		return 0, false
  1753  	}
  1754  	return reclen - uint64(unsafe.Offsetof(Dirent{}.Name)), true
  1755  }
  1756  
  1757  //sys	mount(source string, target string, fstype string, flags uintptr, data *byte) (err error)
  1758  
  1759  func Mount(source string, target string, fstype string, flags uintptr, data string) (err error) {
  1760  	// Certain file systems get rather angry and EINVAL if you give
  1761  	// them an empty string of data, rather than NULL.
  1762  	if data == "" {
  1763  		return mount(source, target, fstype, flags, nil)
  1764  	}
  1765  	datap, err := BytePtrFromString(data)
  1766  	if err != nil {
  1767  		return err
  1768  	}
  1769  	return mount(source, target, fstype, flags, datap)
  1770  }
  1771  
  1772  //sys	mountSetattr(dirfd int, pathname string, flags uint, attr *MountAttr, size uintptr) (err error) = SYS_MOUNT_SETATTR
  1773  
  1774  // MountSetattr is a wrapper for mount_setattr(2).
  1775  // https://man7.org/linux/man-pages/man2/mount_setattr.2.html
  1776  //
  1777  // Requires kernel >= 5.12.
  1778  func MountSetattr(dirfd int, pathname string, flags uint, attr *MountAttr) error {
  1779  	return mountSetattr(dirfd, pathname, flags, attr, unsafe.Sizeof(*attr))
  1780  }
  1781  
  1782  func Sendfile(outfd int, infd int, offset *int64, count int) (written int, err error) {
  1783  	if raceenabled {
  1784  		raceReleaseMerge(unsafe.Pointer(&ioSync))
  1785  	}
  1786  	return sendfile(outfd, infd, offset, count)
  1787  }
  1788  
  1789  // Sendto
  1790  // Recvfrom
  1791  // Socketpair
  1792  
  1793  /*
  1794   * Direct access
  1795   */
  1796  //sys	Acct(path string) (err error)
  1797  //sys	AddKey(keyType string, description string, payload []byte, ringid int) (id int, err error)
  1798  //sys	Adjtimex(buf *Timex) (state int, err error)
  1799  //sysnb	Capget(hdr *CapUserHeader, data *CapUserData) (err error)
  1800  //sysnb	Capset(hdr *CapUserHeader, data *CapUserData) (err error)
  1801  //sys	Chdir(path string) (err error)
  1802  //sys	Chroot(path string) (err error)
  1803  //sys	ClockGetres(clockid int32, res *Timespec) (err error)
  1804  //sys	ClockGettime(clockid int32, time *Timespec) (err error)
  1805  //sys	ClockNanosleep(clockid int32, flags int, request *Timespec, remain *Timespec) (err error)
  1806  //sys	Close(fd int) (err error)
  1807  //sys	CloseRange(first uint, last uint, flags uint) (err error)
  1808  //sys	CopyFileRange(rfd int, roff *int64, wfd int, woff *int64, len int, flags int) (n int, err error)
  1809  //sys	DeleteModule(name string, flags int) (err error)
  1810  //sys	Dup(oldfd int) (fd int, err error)
  1811  
  1812  func Dup2(oldfd, newfd int) error {
  1813  	return Dup3(oldfd, newfd, 0)
  1814  }
  1815  
  1816  //sys	Dup3(oldfd int, newfd int, flags int) (err error)
  1817  //sysnb	EpollCreate1(flag int) (fd int, err error)
  1818  //sysnb	EpollCtl(epfd int, op int, fd int, event *EpollEvent) (err error)
  1819  //sys	Eventfd(initval uint, flags int) (fd int, err error) = SYS_EVENTFD2
  1820  //sys	Exit(code int) = SYS_EXIT_GROUP
  1821  //sys	Fallocate(fd int, mode uint32, off int64, len int64) (err error)
  1822  //sys	Fchdir(fd int) (err error)
  1823  //sys	Fchmod(fd int, mode uint32) (err error)
  1824  //sys	Fchownat(dirfd int, path string, uid int, gid int, flags int) (err error)
  1825  //sys	Fdatasync(fd int) (err error)
  1826  //sys	Fgetxattr(fd int, attr string, dest []byte) (sz int, err error)
  1827  //sys	FinitModule(fd int, params string, flags int) (err error)
  1828  //sys	Flistxattr(fd int, dest []byte) (sz int, err error)
  1829  //sys	Flock(fd int, how int) (err error)
  1830  //sys	Fremovexattr(fd int, attr string) (err error)
  1831  //sys	Fsetxattr(fd int, attr string, dest []byte, flags int) (err error)
  1832  //sys	Fsync(fd int) (err error)
  1833  //sys	Fsmount(fd int, flags int, mountAttrs int) (fsfd int, err error)
  1834  //sys	Fsopen(fsName string, flags int) (fd int, err error)
  1835  //sys	Fspick(dirfd int, pathName string, flags int) (fd int, err error)
  1836  //sys	Getdents(fd int, buf []byte) (n int, err error) = SYS_GETDENTS64
  1837  //sysnb	Getpgid(pid int) (pgid int, err error)
  1838  
  1839  func Getpgrp() (pid int) {
  1840  	pid, _ = Getpgid(0)
  1841  	return
  1842  }
  1843  
  1844  //sysnb	Getpid() (pid int)
  1845  //sysnb	Getppid() (ppid int)
  1846  //sys	Getpriority(which int, who int) (prio int, err error)
  1847  //sys	Getrandom(buf []byte, flags int) (n int, err error)
  1848  //sysnb	Getrusage(who int, rusage *Rusage) (err error)
  1849  //sysnb	Getsid(pid int) (sid int, err error)
  1850  //sysnb	Gettid() (tid int)
  1851  //sys	Getxattr(path string, attr string, dest []byte) (sz int, err error)
  1852  //sys	InitModule(moduleImage []byte, params string) (err error)
  1853  //sys	InotifyAddWatch(fd int, pathname string, mask uint32) (watchdesc int, err error)
  1854  //sysnb	InotifyInit1(flags int) (fd int, err error)
  1855  //sysnb	InotifyRmWatch(fd int, watchdesc uint32) (success int, err error)
  1856  //sysnb	Kill(pid int, sig syscall.Signal) (err error)
  1857  //sys	Klogctl(typ int, buf []byte) (n int, err error) = SYS_SYSLOG
  1858  //sys	Lgetxattr(path string, attr string, dest []byte) (sz int, err error)
  1859  //sys	Listxattr(path string, dest []byte) (sz int, err error)
  1860  //sys	Llistxattr(path string, dest []byte) (sz int, err error)
  1861  //sys	Lremovexattr(path string, attr string) (err error)
  1862  //sys	Lsetxattr(path string, attr string, data []byte, flags int) (err error)
  1863  //sys	MemfdCreate(name string, flags int) (fd int, err error)
  1864  //sys	Mkdirat(dirfd int, path string, mode uint32) (err error)
  1865  //sys	Mknodat(dirfd int, path string, mode uint32, dev int) (err error)
  1866  //sys	MoveMount(fromDirfd int, fromPathName string, toDirfd int, toPathName string, flags int) (err error)
  1867  //sys	Nanosleep(time *Timespec, leftover *Timespec) (err error)
  1868  //sys	OpenTree(dfd int, fileName string, flags uint) (r int, err error)
  1869  //sys	PerfEventOpen(attr *PerfEventAttr, pid int, cpu int, groupFd int, flags int) (fd int, err error)
  1870  //sys	PivotRoot(newroot string, putold string) (err error) = SYS_PIVOT_ROOT
  1871  //sysnb	Prlimit(pid int, resource int, newlimit *Rlimit, old *Rlimit) (err error) = SYS_PRLIMIT64
  1872  //sys	Prctl(option int, arg2 uintptr, arg3 uintptr, arg4 uintptr, arg5 uintptr) (err error)
  1873  //sys	Pselect(nfd int, r *FdSet, w *FdSet, e *FdSet, timeout *Timespec, sigmask *Sigset_t) (n int, err error) = SYS_PSELECT6
  1874  //sys	read(fd int, p []byte) (n int, err error)
  1875  //sys	Removexattr(path string, attr string) (err error)
  1876  //sys	Renameat2(olddirfd int, oldpath string, newdirfd int, newpath string, flags uint) (err error)
  1877  //sys	RequestKey(keyType string, description string, callback string, destRingid int) (id int, err error)
  1878  //sys	Setdomainname(p []byte) (err error)
  1879  //sys	Sethostname(p []byte) (err error)
  1880  //sysnb	Setpgid(pid int, pgid int) (err error)
  1881  //sysnb	Setsid() (pid int, err error)
  1882  //sysnb	Settimeofday(tv *Timeval) (err error)
  1883  //sys	Setns(fd int, nstype int) (err error)
  1884  
  1885  // PrctlRetInt performs a prctl operation specified by option and further
  1886  // optional arguments arg2 through arg5 depending on option. It returns a
  1887  // non-negative integer that is returned by the prctl syscall.
  1888  func PrctlRetInt(option int, arg2 uintptr, arg3 uintptr, arg4 uintptr, arg5 uintptr) (int, error) {
  1889  	ret, _, err := Syscall6(SYS_PRCTL, uintptr(option), uintptr(arg2), uintptr(arg3), uintptr(arg4), uintptr(arg5), 0)
  1890  	if err != 0 {
  1891  		return 0, err
  1892  	}
  1893  	return int(ret), nil
  1894  }
  1895  
  1896  func Setuid(uid int) (err error) {
  1897  	return syscall.Setuid(uid)
  1898  }
  1899  
  1900  func Setgid(gid int) (err error) {
  1901  	return syscall.Setgid(gid)
  1902  }
  1903  
  1904  func Setreuid(ruid, euid int) (err error) {
  1905  	return syscall.Setreuid(ruid, euid)
  1906  }
  1907  
  1908  func Setregid(rgid, egid int) (err error) {
  1909  	return syscall.Setregid(rgid, egid)
  1910  }
  1911  
  1912  func Setresuid(ruid, euid, suid int) (err error) {
  1913  	return syscall.Setresuid(ruid, euid, suid)
  1914  }
  1915  
  1916  func Setresgid(rgid, egid, sgid int) (err error) {
  1917  	return syscall.Setresgid(rgid, egid, sgid)
  1918  }
  1919  
  1920  // SetfsgidRetGid sets fsgid for current thread and returns previous fsgid set.
  1921  // setfsgid(2) will return a non-nil error only if its caller lacks CAP_SETUID capability.
  1922  // If the call fails due to other reasons, current fsgid will be returned.
  1923  func SetfsgidRetGid(gid int) (int, error) {
  1924  	return setfsgid(gid)
  1925  }
  1926  
  1927  // SetfsuidRetUid sets fsuid for current thread and returns previous fsuid set.
  1928  // setfsgid(2) will return a non-nil error only if its caller lacks CAP_SETUID capability
  1929  // If the call fails due to other reasons, current fsuid will be returned.
  1930  func SetfsuidRetUid(uid int) (int, error) {
  1931  	return setfsuid(uid)
  1932  }
  1933  
  1934  func Setfsgid(gid int) error {
  1935  	_, err := setfsgid(gid)
  1936  	return err
  1937  }
  1938  
  1939  func Setfsuid(uid int) error {
  1940  	_, err := setfsuid(uid)
  1941  	return err
  1942  }
  1943  
  1944  func Signalfd(fd int, sigmask *Sigset_t, flags int) (newfd int, err error) {
  1945  	return signalfd(fd, sigmask, _C__NSIG/8, flags)
  1946  }
  1947  
  1948  //sys	Setpriority(which int, who int, prio int) (err error)
  1949  //sys	Setxattr(path string, attr string, data []byte, flags int) (err error)
  1950  //sys	signalfd(fd int, sigmask *Sigset_t, maskSize uintptr, flags int) (newfd int, err error) = SYS_SIGNALFD4
  1951  //sys	Statx(dirfd int, path string, flags int, mask int, stat *Statx_t) (err error)
  1952  //sys	Sync()
  1953  //sys	Syncfs(fd int) (err error)
  1954  //sysnb	Sysinfo(info *Sysinfo_t) (err error)
  1955  //sys	Tee(rfd int, wfd int, len int, flags int) (n int64, err error)
  1956  //sysnb	TimerfdCreate(clockid int, flags int) (fd int, err error)
  1957  //sysnb	TimerfdGettime(fd int, currValue *ItimerSpec) (err error)
  1958  //sysnb	TimerfdSettime(fd int, flags int, newValue *ItimerSpec, oldValue *ItimerSpec) (err error)
  1959  //sysnb	Tgkill(tgid int, tid int, sig syscall.Signal) (err error)
  1960  //sysnb	Times(tms *Tms) (ticks uintptr, err error)
  1961  //sysnb	Umask(mask int) (oldmask int)
  1962  //sysnb	Uname(buf *Utsname) (err error)
  1963  //sys	Unmount(target string, flags int) (err error) = SYS_UMOUNT2
  1964  //sys	Unshare(flags int) (err error)
  1965  //sys	write(fd int, p []byte) (n int, err error)
  1966  //sys	exitThread(code int) (err error) = SYS_EXIT
  1967  //sys	readlen(fd int, p *byte, np int) (n int, err error) = SYS_READ
  1968  //sys	writelen(fd int, p *byte, np int) (n int, err error) = SYS_WRITE
  1969  //sys	readv(fd int, iovs []Iovec) (n int, err error) = SYS_READV
  1970  //sys	writev(fd int, iovs []Iovec) (n int, err error) = SYS_WRITEV
  1971  //sys	preadv(fd int, iovs []Iovec, offs_l uintptr, offs_h uintptr) (n int, err error) = SYS_PREADV
  1972  //sys	pwritev(fd int, iovs []Iovec, offs_l uintptr, offs_h uintptr) (n int, err error) = SYS_PWRITEV
  1973  //sys	preadv2(fd int, iovs []Iovec, offs_l uintptr, offs_h uintptr, flags int) (n int, err error) = SYS_PREADV2
  1974  //sys	pwritev2(fd int, iovs []Iovec, offs_l uintptr, offs_h uintptr, flags int) (n int, err error) = SYS_PWRITEV2
  1975  
  1976  func bytes2iovec(bs [][]byte) []Iovec {
  1977  	iovecs := make([]Iovec, len(bs))
  1978  	for i, b := range bs {
  1979  		iovecs[i].SetLen(len(b))
  1980  		if len(b) > 0 {
  1981  			iovecs[i].Base = &b[0]
  1982  		} else {
  1983  			iovecs[i].Base = (*byte)(unsafe.Pointer(&_zero))
  1984  		}
  1985  	}
  1986  	return iovecs
  1987  }
  1988  
  1989  // offs2lohi splits offs into its low and high order bits.
  1990  func offs2lohi(offs int64) (lo, hi uintptr) {
  1991  	const longBits = SizeofLong * 8
  1992  	return uintptr(offs), uintptr(uint64(offs) >> longBits)
  1993  }
  1994  
  1995  func Readv(fd int, iovs [][]byte) (n int, err error) {
  1996  	iovecs := bytes2iovec(iovs)
  1997  	n, err = readv(fd, iovecs)
  1998  	readvRacedetect(iovecs, n, err)
  1999  	return n, err
  2000  }
  2001  
  2002  func Preadv(fd int, iovs [][]byte, offset int64) (n int, err error) {
  2003  	iovecs := bytes2iovec(iovs)
  2004  	lo, hi := offs2lohi(offset)
  2005  	n, err = preadv(fd, iovecs, lo, hi)
  2006  	readvRacedetect(iovecs, n, err)
  2007  	return n, err
  2008  }
  2009  
  2010  func Preadv2(fd int, iovs [][]byte, offset int64, flags int) (n int, err error) {
  2011  	iovecs := bytes2iovec(iovs)
  2012  	lo, hi := offs2lohi(offset)
  2013  	n, err = preadv2(fd, iovecs, lo, hi, flags)
  2014  	readvRacedetect(iovecs, n, err)
  2015  	return n, err
  2016  }
  2017  
  2018  func readvRacedetect(iovecs []Iovec, n int, err error) {
  2019  	if !raceenabled {
  2020  		return
  2021  	}
  2022  	for i := 0; n > 0 && i < len(iovecs); i++ {
  2023  		m := int(iovecs[i].Len)
  2024  		if m > n {
  2025  			m = n
  2026  		}
  2027  		n -= m
  2028  		if m > 0 {
  2029  			raceWriteRange(unsafe.Pointer(iovecs[i].Base), m)
  2030  		}
  2031  	}
  2032  	if err == nil {
  2033  		raceAcquire(unsafe.Pointer(&ioSync))
  2034  	}
  2035  }
  2036  
  2037  func Writev(fd int, iovs [][]byte) (n int, err error) {
  2038  	iovecs := bytes2iovec(iovs)
  2039  	if raceenabled {
  2040  		raceReleaseMerge(unsafe.Pointer(&ioSync))
  2041  	}
  2042  	n, err = writev(fd, iovecs)
  2043  	writevRacedetect(iovecs, n)
  2044  	return n, err
  2045  }
  2046  
  2047  func Pwritev(fd int, iovs [][]byte, offset int64) (n int, err error) {
  2048  	iovecs := bytes2iovec(iovs)
  2049  	if raceenabled {
  2050  		raceReleaseMerge(unsafe.Pointer(&ioSync))
  2051  	}
  2052  	lo, hi := offs2lohi(offset)
  2053  	n, err = pwritev(fd, iovecs, lo, hi)
  2054  	writevRacedetect(iovecs, n)
  2055  	return n, err
  2056  }
  2057  
  2058  func Pwritev2(fd int, iovs [][]byte, offset int64, flags int) (n int, err error) {
  2059  	iovecs := bytes2iovec(iovs)
  2060  	if raceenabled {
  2061  		raceReleaseMerge(unsafe.Pointer(&ioSync))
  2062  	}
  2063  	lo, hi := offs2lohi(offset)
  2064  	n, err = pwritev2(fd, iovecs, lo, hi, flags)
  2065  	writevRacedetect(iovecs, n)
  2066  	return n, err
  2067  }
  2068  
  2069  func writevRacedetect(iovecs []Iovec, n int) {
  2070  	if !raceenabled {
  2071  		return
  2072  	}
  2073  	for i := 0; n > 0 && i < len(iovecs); i++ {
  2074  		m := int(iovecs[i].Len)
  2075  		if m > n {
  2076  			m = n
  2077  		}
  2078  		n -= m
  2079  		if m > 0 {
  2080  			raceReadRange(unsafe.Pointer(iovecs[i].Base), m)
  2081  		}
  2082  	}
  2083  }
  2084  
  2085  // mmap varies by architecture; see syscall_linux_*.go.
  2086  //sys	munmap(addr uintptr, length uintptr) (err error)
  2087  
  2088  var mapper = &mmapper{
  2089  	active: make(map[*byte][]byte),
  2090  	mmap:   mmap,
  2091  	munmap: munmap,
  2092  }
  2093  
  2094  func Mmap(fd int, offset int64, length int, prot int, flags int) (data []byte, err error) {
  2095  	return mapper.Mmap(fd, offset, length, prot, flags)
  2096  }
  2097  
  2098  func Munmap(b []byte) (err error) {
  2099  	return mapper.Munmap(b)
  2100  }
  2101  
  2102  //sys	Madvise(b []byte, advice int) (err error)
  2103  //sys	Mprotect(b []byte, prot int) (err error)
  2104  //sys	Mlock(b []byte) (err error)
  2105  //sys	Mlockall(flags int) (err error)
  2106  //sys	Msync(b []byte, flags int) (err error)
  2107  //sys	Munlock(b []byte) (err error)
  2108  //sys	Munlockall() (err error)
  2109  
  2110  // Vmsplice splices user pages from a slice of Iovecs into a pipe specified by fd,
  2111  // using the specified flags.
  2112  func Vmsplice(fd int, iovs []Iovec, flags int) (int, error) {
  2113  	var p unsafe.Pointer
  2114  	if len(iovs) > 0 {
  2115  		p = unsafe.Pointer(&iovs[0])
  2116  	}
  2117  
  2118  	n, _, errno := Syscall6(SYS_VMSPLICE, uintptr(fd), uintptr(p), uintptr(len(iovs)), uintptr(flags), 0, 0)
  2119  	if errno != 0 {
  2120  		return 0, syscall.Errno(errno)
  2121  	}
  2122  
  2123  	return int(n), nil
  2124  }
  2125  
  2126  func isGroupMember(gid int) bool {
  2127  	groups, err := Getgroups()
  2128  	if err != nil {
  2129  		return false
  2130  	}
  2131  
  2132  	for _, g := range groups {
  2133  		if g == gid {
  2134  			return true
  2135  		}
  2136  	}
  2137  	return false
  2138  }
  2139  
  2140  //sys	faccessat(dirfd int, path string, mode uint32) (err error)
  2141  //sys	Faccessat2(dirfd int, path string, mode uint32, flags int) (err error)
  2142  
  2143  func Faccessat(dirfd int, path string, mode uint32, flags int) (err error) {
  2144  	if flags == 0 {
  2145  		return faccessat(dirfd, path, mode)
  2146  	}
  2147  
  2148  	if err := Faccessat2(dirfd, path, mode, flags); err != ENOSYS && err != EPERM {
  2149  		return err
  2150  	}
  2151  
  2152  	// The Linux kernel faccessat system call does not take any flags.
  2153  	// The glibc faccessat implements the flags itself; see
  2154  	// https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/unix/sysv/linux/faccessat.c;hb=HEAD
  2155  	// Because people naturally expect syscall.Faccessat to act
  2156  	// like C faccessat, we do the same.
  2157  
  2158  	if flags & ^(AT_SYMLINK_NOFOLLOW|AT_EACCESS) != 0 {
  2159  		return EINVAL
  2160  	}
  2161  
  2162  	var st Stat_t
  2163  	if err := Fstatat(dirfd, path, &st, flags&AT_SYMLINK_NOFOLLOW); err != nil {
  2164  		return err
  2165  	}
  2166  
  2167  	mode &= 7
  2168  	if mode == 0 {
  2169  		return nil
  2170  	}
  2171  
  2172  	var uid int
  2173  	if flags&AT_EACCESS != 0 {
  2174  		uid = Geteuid()
  2175  	} else {
  2176  		uid = Getuid()
  2177  	}
  2178  
  2179  	if uid == 0 {
  2180  		if mode&1 == 0 {
  2181  			// Root can read and write any file.
  2182  			return nil
  2183  		}
  2184  		if st.Mode&0111 != 0 {
  2185  			// Root can execute any file that anybody can execute.
  2186  			return nil
  2187  		}
  2188  		return EACCES
  2189  	}
  2190  
  2191  	var fmode uint32
  2192  	if uint32(uid) == st.Uid {
  2193  		fmode = (st.Mode >> 6) & 7
  2194  	} else {
  2195  		var gid int
  2196  		if flags&AT_EACCESS != 0 {
  2197  			gid = Getegid()
  2198  		} else {
  2199  			gid = Getgid()
  2200  		}
  2201  
  2202  		if uint32(gid) == st.Gid || isGroupMember(int(st.Gid)) {
  2203  			fmode = (st.Mode >> 3) & 7
  2204  		} else {
  2205  			fmode = st.Mode & 7
  2206  		}
  2207  	}
  2208  
  2209  	if fmode&mode == mode {
  2210  		return nil
  2211  	}
  2212  
  2213  	return EACCES
  2214  }
  2215  
  2216  //sys	nameToHandleAt(dirFD int, pathname string, fh *fileHandle, mountID *_C_int, flags int) (err error) = SYS_NAME_TO_HANDLE_AT
  2217  //sys	openByHandleAt(mountFD int, fh *fileHandle, flags int) (fd int, err error) = SYS_OPEN_BY_HANDLE_AT
  2218  
  2219  // fileHandle is the argument to nameToHandleAt and openByHandleAt. We
  2220  // originally tried to generate it via unix/linux/types.go with "type
  2221  // fileHandle C.struct_file_handle" but that generated empty structs
  2222  // for mips64 and mips64le. Instead, hard code it for now (it's the
  2223  // same everywhere else) until the mips64 generator issue is fixed.
  2224  type fileHandle struct {
  2225  	Bytes uint32
  2226  	Type  int32
  2227  }
  2228  
  2229  // FileHandle represents the C struct file_handle used by
  2230  // name_to_handle_at (see NameToHandleAt) and open_by_handle_at (see
  2231  // OpenByHandleAt).
  2232  type FileHandle struct {
  2233  	*fileHandle
  2234  }
  2235  
  2236  // NewFileHandle constructs a FileHandle.
  2237  func NewFileHandle(handleType int32, handle []byte) FileHandle {
  2238  	const hdrSize = unsafe.Sizeof(fileHandle{})
  2239  	buf := make([]byte, hdrSize+uintptr(len(handle)))
  2240  	copy(buf[hdrSize:], handle)
  2241  	fh := (*fileHandle)(unsafe.Pointer(&buf[0]))
  2242  	fh.Type = handleType
  2243  	fh.Bytes = uint32(len(handle))
  2244  	return FileHandle{fh}
  2245  }
  2246  
  2247  func (fh *FileHandle) Size() int   { return int(fh.fileHandle.Bytes) }
  2248  func (fh *FileHandle) Type() int32 { return fh.fileHandle.Type }
  2249  func (fh *FileHandle) Bytes() []byte {
  2250  	n := fh.Size()
  2251  	if n == 0 {
  2252  		return nil
  2253  	}
  2254  	return unsafe.Slice((*byte)(unsafe.Pointer(uintptr(unsafe.Pointer(&fh.fileHandle.Type))+4)), n)
  2255  }
  2256  
  2257  // NameToHandleAt wraps the name_to_handle_at system call; it obtains
  2258  // a handle for a path name.
  2259  func NameToHandleAt(dirfd int, path string, flags int) (handle FileHandle, mountID int, err error) {
  2260  	var mid _C_int
  2261  	// Try first with a small buffer, assuming the handle will
  2262  	// only be 32 bytes.
  2263  	size := uint32(32 + unsafe.Sizeof(fileHandle{}))
  2264  	didResize := false
  2265  	for {
  2266  		buf := make([]byte, size)
  2267  		fh := (*fileHandle)(unsafe.Pointer(&buf[0]))
  2268  		fh.Bytes = size - uint32(unsafe.Sizeof(fileHandle{}))
  2269  		err = nameToHandleAt(dirfd, path, fh, &mid, flags)
  2270  		if err == EOVERFLOW {
  2271  			if didResize {
  2272  				// We shouldn't need to resize more than once
  2273  				return
  2274  			}
  2275  			didResize = true
  2276  			size = fh.Bytes + uint32(unsafe.Sizeof(fileHandle{}))
  2277  			continue
  2278  		}
  2279  		if err != nil {
  2280  			return
  2281  		}
  2282  		return FileHandle{fh}, int(mid), nil
  2283  	}
  2284  }
  2285  
  2286  // OpenByHandleAt wraps the open_by_handle_at system call; it opens a
  2287  // file via a handle as previously returned by NameToHandleAt.
  2288  func OpenByHandleAt(mountFD int, handle FileHandle, flags int) (fd int, err error) {
  2289  	return openByHandleAt(mountFD, handle.fileHandle, flags)
  2290  }
  2291  
  2292  // Klogset wraps the sys_syslog system call; it sets console_loglevel to
  2293  // the value specified by arg and passes a dummy pointer to bufp.
  2294  func Klogset(typ int, arg int) (err error) {
  2295  	var p unsafe.Pointer
  2296  	_, _, errno := Syscall(SYS_SYSLOG, uintptr(typ), uintptr(p), uintptr(arg))
  2297  	if errno != 0 {
  2298  		return errnoErr(errno)
  2299  	}
  2300  	return nil
  2301  }
  2302  
  2303  // RemoteIovec is Iovec with the pointer replaced with an integer.
  2304  // It is used for ProcessVMReadv and ProcessVMWritev, where the pointer
  2305  // refers to a location in a different process' address space, which
  2306  // would confuse the Go garbage collector.
  2307  type RemoteIovec struct {
  2308  	Base uintptr
  2309  	Len  int
  2310  }
  2311  
  2312  //sys	ProcessVMReadv(pid int, localIov []Iovec, remoteIov []RemoteIovec, flags uint) (n int, err error) = SYS_PROCESS_VM_READV
  2313  //sys	ProcessVMWritev(pid int, localIov []Iovec, remoteIov []RemoteIovec, flags uint) (n int, err error) = SYS_PROCESS_VM_WRITEV
  2314  
  2315  //sys	PidfdOpen(pid int, flags int) (fd int, err error) = SYS_PIDFD_OPEN
  2316  //sys	PidfdGetfd(pidfd int, targetfd int, flags int) (fd int, err error) = SYS_PIDFD_GETFD
  2317  //sys	PidfdSendSignal(pidfd int, sig Signal, info *Siginfo, flags int) (err error) = SYS_PIDFD_SEND_SIGNAL
  2318  
  2319  //sys	shmat(id int, addr uintptr, flag int) (ret uintptr, err error)
  2320  //sys	shmctl(id int, cmd int, buf *SysvShmDesc) (result int, err error)
  2321  //sys	shmdt(addr uintptr) (err error)
  2322  //sys	shmget(key int, size int, flag int) (id int, err error)
  2323  
  2324  //sys	getitimer(which int, currValue *Itimerval) (err error)
  2325  //sys	setitimer(which int, newValue *Itimerval, oldValue *Itimerval) (err error)
  2326  
  2327  // MakeItimerval creates an Itimerval from interval and value durations.
  2328  func MakeItimerval(interval, value time.Duration) Itimerval {
  2329  	return Itimerval{
  2330  		Interval: NsecToTimeval(interval.Nanoseconds()),
  2331  		Value:    NsecToTimeval(value.Nanoseconds()),
  2332  	}
  2333  }
  2334  
  2335  // A value which may be passed to the which parameter for Getitimer and
  2336  // Setitimer.
  2337  type ItimerWhich int
  2338  
  2339  // Possible which values for Getitimer and Setitimer.
  2340  const (
  2341  	ItimerReal    ItimerWhich = ITIMER_REAL
  2342  	ItimerVirtual ItimerWhich = ITIMER_VIRTUAL
  2343  	ItimerProf    ItimerWhich = ITIMER_PROF
  2344  )
  2345  
  2346  // Getitimer wraps getitimer(2) to return the current value of the timer
  2347  // specified by which.
  2348  func Getitimer(which ItimerWhich) (Itimerval, error) {
  2349  	var it Itimerval
  2350  	if err := getitimer(int(which), &it); err != nil {
  2351  		return Itimerval{}, err
  2352  	}
  2353  
  2354  	return it, nil
  2355  }
  2356  
  2357  // Setitimer wraps setitimer(2) to arm or disarm the timer specified by which.
  2358  // It returns the previous value of the timer.
  2359  //
  2360  // If the Itimerval argument is the zero value, the timer will be disarmed.
  2361  func Setitimer(which ItimerWhich, it Itimerval) (Itimerval, error) {
  2362  	var prev Itimerval
  2363  	if err := setitimer(int(which), &it, &prev); err != nil {
  2364  		return Itimerval{}, err
  2365  	}
  2366  
  2367  	return prev, nil
  2368  }
  2369  
  2370  //sysnb	rtSigprocmask(how int, set *Sigset_t, oldset *Sigset_t, sigsetsize uintptr) (err error) = SYS_RT_SIGPROCMASK
  2371  
  2372  func PthreadSigmask(how int, set, oldset *Sigset_t) error {
  2373  	if oldset != nil {
  2374  		// Explicitly clear in case Sigset_t is larger than _C__NSIG.
  2375  		*oldset = Sigset_t{}
  2376  	}
  2377  	return rtSigprocmask(how, set, oldset, _C__NSIG/8)
  2378  }
  2379  
  2380  /*
  2381   * Unimplemented
  2382   */
  2383  // AfsSyscall
  2384  // ArchPrctl
  2385  // Brk
  2386  // ClockNanosleep
  2387  // ClockSettime
  2388  // Clone
  2389  // EpollCtlOld
  2390  // EpollPwait
  2391  // EpollWaitOld
  2392  // Execve
  2393  // Fork
  2394  // Futex
  2395  // GetKernelSyms
  2396  // GetMempolicy
  2397  // GetRobustList
  2398  // GetThreadArea
  2399  // Getpmsg
  2400  // IoCancel
  2401  // IoDestroy
  2402  // IoGetevents
  2403  // IoSetup
  2404  // IoSubmit
  2405  // IoprioGet
  2406  // IoprioSet
  2407  // KexecLoad
  2408  // LookupDcookie
  2409  // Mbind
  2410  // MigratePages
  2411  // Mincore
  2412  // ModifyLdt
  2413  // Mount
  2414  // MovePages
  2415  // MqGetsetattr
  2416  // MqNotify
  2417  // MqOpen
  2418  // MqTimedreceive
  2419  // MqTimedsend
  2420  // MqUnlink
  2421  // Mremap
  2422  // Msgctl
  2423  // Msgget
  2424  // Msgrcv
  2425  // Msgsnd
  2426  // Nfsservctl
  2427  // Personality
  2428  // Pselect6
  2429  // Ptrace
  2430  // Putpmsg
  2431  // Quotactl
  2432  // Readahead
  2433  // Readv
  2434  // RemapFilePages
  2435  // RestartSyscall
  2436  // RtSigaction
  2437  // RtSigpending
  2438  // RtSigqueueinfo
  2439  // RtSigreturn
  2440  // RtSigsuspend
  2441  // RtSigtimedwait
  2442  // SchedGetPriorityMax
  2443  // SchedGetPriorityMin
  2444  // SchedGetparam
  2445  // SchedGetscheduler
  2446  // SchedRrGetInterval
  2447  // SchedSetparam
  2448  // SchedYield
  2449  // Security
  2450  // Semctl
  2451  // Semget
  2452  // Semop
  2453  // Semtimedop
  2454  // SetMempolicy
  2455  // SetRobustList
  2456  // SetThreadArea
  2457  // SetTidAddress
  2458  // Sigaltstack
  2459  // Swapoff
  2460  // Swapon
  2461  // Sysfs
  2462  // TimerCreate
  2463  // TimerDelete
  2464  // TimerGetoverrun
  2465  // TimerGettime
  2466  // TimerSettime
  2467  // Tkill (obsolete)
  2468  // Tuxcall
  2469  // Umount2
  2470  // Uselib
  2471  // Utimensat
  2472  // Vfork
  2473  // Vhangup
  2474  // Vserver
  2475  // _Sysctl
  2476  

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