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

     1  // Copyright 2009 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // Linux system calls.
     6  // This file is compiled as ordinary Go code,
     7  // but it is also input to mksyscall,
     8  // which parses the //sys lines and generates system call stubs.
     9  // Note that sometimes we use a lowercase //sys name and
    10  // wrap it in our own nicer implementation.
    11  
    12  package unix
    13  
    14  import (
    15  	"encoding/binary"
    16  	"slices"
    17  	"strconv"
    18  	"syscall"
    19  	"time"
    20  	"unsafe"
    21  )
    22  
    23  /*
    24   * Wrapped
    25   */
    26  
    27  func Access(path string, mode uint32) (err error) {
    28  	return Faccessat(AT_FDCWD, path, mode, 0)
    29  }
    30  
    31  func Chmod(path string, mode uint32) (err error) {
    32  	return Fchmodat(AT_FDCWD, path, mode, 0)
    33  }
    34  
    35  func Chown(path string, uid int, gid int) (err error) {
    36  	return Fchownat(AT_FDCWD, path, uid, gid, 0)
    37  }
    38  
    39  func Creat(path string, mode uint32) (fd int, err error) {
    40  	return Open(path, O_CREAT|O_WRONLY|O_TRUNC, mode)
    41  }
    42  
    43  func EpollCreate(size int) (fd int, err error) {
    44  	if size <= 0 {
    45  		return -1, EINVAL
    46  	}
    47  	return EpollCreate1(0)
    48  }
    49  
    50  //sys	FanotifyInit(flags uint, event_f_flags uint) (fd int, err error)
    51  //sys	fanotifyMark(fd int, flags uint, mask uint64, dirFd int, pathname *byte) (err error)
    52  
    53  func FanotifyMark(fd int, flags uint, mask uint64, dirFd int, pathname string) (err error) {
    54  	if pathname == "" {
    55  		return fanotifyMark(fd, flags, mask, dirFd, nil)
    56  	}
    57  	p, err := BytePtrFromString(pathname)
    58  	if err != nil {
    59  		return err
    60  	}
    61  	return fanotifyMark(fd, flags, mask, dirFd, p)
    62  }
    63  
    64  //sys	fchmodat(dirfd int, path string, mode uint32) (err error)
    65  //sys	fchmodat2(dirfd int, path string, mode uint32, flags int) (err error)
    66  
    67  func Fchmodat(dirfd int, path string, mode uint32, flags int) error {
    68  	// Linux fchmodat doesn't support the flags parameter, but fchmodat2 does.
    69  	// Try fchmodat2 if flags are specified.
    70  	if flags != 0 {
    71  		err := fchmodat2(dirfd, path, mode, flags)
    72  		if err == ENOSYS {
    73  			// fchmodat2 isn't available. If the flags are known to be valid,
    74  			// return EOPNOTSUPP to indicate that fchmodat doesn't support them.
    75  			if flags&^(AT_SYMLINK_NOFOLLOW|AT_EMPTY_PATH) != 0 {
    76  				return EINVAL
    77  			} else if flags&(AT_SYMLINK_NOFOLLOW|AT_EMPTY_PATH) != 0 {
    78  				return EOPNOTSUPP
    79  			}
    80  		}
    81  		return err
    82  	}
    83  	return fchmodat(dirfd, path, mode)
    84  }
    85  
    86  func InotifyInit() (fd int, err error) {
    87  	return InotifyInit1(0)
    88  }
    89  
    90  //sys	ioctl(fd int, req uint, arg uintptr) (err error) = SYS_IOCTL
    91  //sys	ioctlPtr(fd int, req uint, arg unsafe.Pointer) (err error) = SYS_IOCTL
    92  
    93  // ioctl itself should not be exposed directly, but additional get/set functions
    94  // for specific types are permissible. These are defined in ioctl.go and
    95  // ioctl_linux.go.
    96  //
    97  // The third argument to ioctl is often a pointer but sometimes an integer.
    98  // Callers should use ioctlPtr when the third argument is a pointer and ioctl
    99  // when the third argument is an integer.
   100  //
   101  // TODO: some existing code incorrectly uses ioctl when it should use ioctlPtr.
   102  
   103  //sys	Linkat(olddirfd int, oldpath string, newdirfd int, newpath string, flags int) (err error)
   104  
   105  func Link(oldpath string, newpath string) (err error) {
   106  	return Linkat(AT_FDCWD, oldpath, AT_FDCWD, newpath, 0)
   107  }
   108  
   109  func Mkdir(path string, mode uint32) (err error) {
   110  	return Mkdirat(AT_FDCWD, path, mode)
   111  }
   112  
   113  func Mknod(path string, mode uint32, dev int) (err error) {
   114  	return Mknodat(AT_FDCWD, path, mode, dev)
   115  }
   116  
   117  func Open(path string, mode int, perm uint32) (fd int, err error) {
   118  	return openat(AT_FDCWD, path, mode|O_LARGEFILE, perm)
   119  }
   120  
   121  //sys	openat(dirfd int, path string, flags int, mode uint32) (fd int, err error)
   122  
   123  func Openat(dirfd int, path string, flags int, mode uint32) (fd int, err error) {
   124  	return openat(dirfd, path, flags|O_LARGEFILE, mode)
   125  }
   126  
   127  //sys	openat2(dirfd int, path string, open_how *OpenHow, size int) (fd int, err error)
   128  
   129  func Openat2(dirfd int, path string, how *OpenHow) (fd int, err error) {
   130  	return openat2(dirfd, path, how, SizeofOpenHow)
   131  }
   132  
   133  func Pipe(p []int) error {
   134  	return Pipe2(p, 0)
   135  }
   136  
   137  //sysnb	pipe2(p *[2]_C_int, flags int) (err error)
   138  
   139  func Pipe2(p []int, flags int) error {
   140  	if len(p) != 2 {
   141  		return EINVAL
   142  	}
   143  	var pp [2]_C_int
   144  	err := pipe2(&pp, flags)
   145  	if err == nil {
   146  		p[0] = int(pp[0])
   147  		p[1] = int(pp[1])
   148  	}
   149  	return err
   150  }
   151  
   152  //sys	ppoll(fds *PollFd, nfds int, timeout *Timespec, sigmask *Sigset_t) (n int, err error)
   153  
   154  func Ppoll(fds []PollFd, timeout *Timespec, sigmask *Sigset_t) (n int, err error) {
   155  	if len(fds) == 0 {
   156  		return ppoll(nil, 0, timeout, sigmask)
   157  	}
   158  	return ppoll(&fds[0], len(fds), timeout, sigmask)
   159  }
   160  
   161  func Poll(fds []PollFd, timeout int) (n int, err error) {
   162  	var ts *Timespec
   163  	if timeout >= 0 {
   164  		ts = new(Timespec)
   165  		*ts = NsecToTimespec(int64(timeout) * 1e6)
   166  	}
   167  	return Ppoll(fds, ts, nil)
   168  }
   169  
   170  //sys	Readlinkat(dirfd int, path string, buf []byte) (n int, err error)
   171  
   172  func Readlink(path string, buf []byte) (n int, err error) {
   173  	return Readlinkat(AT_FDCWD, path, buf)
   174  }
   175  
   176  func Rename(oldpath string, newpath string) (err error) {
   177  	return Renameat(AT_FDCWD, oldpath, AT_FDCWD, newpath)
   178  }
   179  
   180  func Rmdir(path string) error {
   181  	return Unlinkat(AT_FDCWD, path, AT_REMOVEDIR)
   182  }
   183  
   184  //sys	Symlinkat(oldpath string, newdirfd int, newpath string) (err error)
   185  
   186  func Symlink(oldpath string, newpath string) (err error) {
   187  	return Symlinkat(oldpath, AT_FDCWD, newpath)
   188  }
   189  
   190  func Unlink(path string) error {
   191  	return Unlinkat(AT_FDCWD, path, 0)
   192  }
   193  
   194  //sys	Unlinkat(dirfd int, path string, flags int) (err error)
   195  
   196  func Utimes(path string, tv []Timeval) error {
   197  	if tv == nil {
   198  		err := utimensat(AT_FDCWD, path, nil, 0)
   199  		if err != ENOSYS {
   200  			return err
   201  		}
   202  		return utimes(path, nil)
   203  	}
   204  	if len(tv) != 2 {
   205  		return EINVAL
   206  	}
   207  	var ts [2]Timespec
   208  	ts[0] = NsecToTimespec(TimevalToNsec(tv[0]))
   209  	ts[1] = NsecToTimespec(TimevalToNsec(tv[1]))
   210  	err := utimensat(AT_FDCWD, path, (*[2]Timespec)(unsafe.Pointer(&ts[0])), 0)
   211  	if err != ENOSYS {
   212  		return err
   213  	}
   214  	return utimes(path, (*[2]Timeval)(unsafe.Pointer(&tv[0])))
   215  }
   216  
   217  //sys	utimensat(dirfd int, path string, times *[2]Timespec, flags int) (err error)
   218  
   219  func UtimesNano(path string, ts []Timespec) error {
   220  	return UtimesNanoAt(AT_FDCWD, path, ts, 0)
   221  }
   222  
   223  func UtimesNanoAt(dirfd int, path string, ts []Timespec, flags int) error {
   224  	if ts == nil {
   225  		return utimensat(dirfd, path, nil, flags)
   226  	}
   227  	if len(ts) != 2 {
   228  		return EINVAL
   229  	}
   230  	return utimensat(dirfd, path, (*[2]Timespec)(unsafe.Pointer(&ts[0])), flags)
   231  }
   232  
   233  func Futimesat(dirfd int, path string, tv []Timeval) error {
   234  	if tv == nil {
   235  		return futimesat(dirfd, path, nil)
   236  	}
   237  	if len(tv) != 2 {
   238  		return EINVAL
   239  	}
   240  	return futimesat(dirfd, path, (*[2]Timeval)(unsafe.Pointer(&tv[0])))
   241  }
   242  
   243  func Futimes(fd int, tv []Timeval) (err error) {
   244  	// Believe it or not, this is the best we can do on Linux
   245  	// (and is what glibc does).
   246  	return Utimes("/proc/self/fd/"+strconv.Itoa(fd), tv)
   247  }
   248  
   249  const ImplementsGetwd = true
   250  
   251  //sys	Getcwd(buf []byte) (n int, err error)
   252  
   253  func Getwd() (wd string, err error) {
   254  	var buf [PathMax]byte
   255  	n, err := Getcwd(buf[0:])
   256  	if err != nil {
   257  		return "", err
   258  	}
   259  	// Getcwd returns the number of bytes written to buf, including the NUL.
   260  	if n < 1 || n > len(buf) || buf[n-1] != 0 {
   261  		return "", EINVAL
   262  	}
   263  	// In some cases, Linux can return a path that starts with the
   264  	// "(unreachable)" prefix, which can potentially be a valid relative
   265  	// path. To work around that, return ENOENT if path is not absolute.
   266  	if buf[0] != '/' {
   267  		return "", ENOENT
   268  	}
   269  
   270  	return string(buf[0 : n-1]), nil
   271  }
   272  
   273  func Getgroups() (gids []int, err error) {
   274  	n, err := getgroups(0, nil)
   275  	if err != nil {
   276  		return nil, err
   277  	}
   278  	if n == 0 {
   279  		return nil, nil
   280  	}
   281  
   282  	// Sanity check group count. Max is 1<<16 on Linux.
   283  	if n < 0 || n > 1<<20 {
   284  		return nil, EINVAL
   285  	}
   286  
   287  	a := make([]_Gid_t, n)
   288  	n, err = getgroups(n, &a[0])
   289  	if err != nil {
   290  		return nil, err
   291  	}
   292  	gids = make([]int, n)
   293  	for i, v := range a[0:n] {
   294  		gids[i] = int(v)
   295  	}
   296  	return
   297  }
   298  
   299  func Setgroups(gids []int) (err error) {
   300  	if len(gids) == 0 {
   301  		return setgroups(0, nil)
   302  	}
   303  
   304  	a := make([]_Gid_t, len(gids))
   305  	for i, v := range gids {
   306  		a[i] = _Gid_t(v)
   307  	}
   308  	return setgroups(len(a), &a[0])
   309  }
   310  
   311  type WaitStatus uint32
   312  
   313  // Wait status is 7 bits at bottom, either 0 (exited),
   314  // 0x7F (stopped), or a signal number that caused an exit.
   315  // The 0x80 bit is whether there was a core dump.
   316  // An extra number (exit code, signal causing a stop)
   317  // is in the high bits. At least that's the idea.
   318  // There are various irregularities. For example, the
   319  // "continued" status is 0xFFFF, distinguishing itself
   320  // from stopped via the core dump bit.
   321  
   322  const (
   323  	mask    = 0x7F
   324  	core    = 0x80
   325  	exited  = 0x00
   326  	stopped = 0x7F
   327  	shift   = 8
   328  )
   329  
   330  func (w WaitStatus) Exited() bool { return w&mask == exited }
   331  
   332  func (w WaitStatus) Signaled() bool { return w&mask != stopped && w&mask != exited }
   333  
   334  func (w WaitStatus) Stopped() bool { return w&0xFF == stopped }
   335  
   336  func (w WaitStatus) Continued() bool { return w == 0xFFFF }
   337  
   338  func (w WaitStatus) CoreDump() bool { return w.Signaled() && w&core != 0 }
   339  
   340  func (w WaitStatus) ExitStatus() int {
   341  	if !w.Exited() {
   342  		return -1
   343  	}
   344  	return int(w>>shift) & 0xFF
   345  }
   346  
   347  func (w WaitStatus) Signal() syscall.Signal {
   348  	if !w.Signaled() {
   349  		return -1
   350  	}
   351  	return syscall.Signal(w & mask)
   352  }
   353  
   354  func (w WaitStatus) StopSignal() syscall.Signal {
   355  	if !w.Stopped() {
   356  		return -1
   357  	}
   358  	return syscall.Signal(w>>shift) & 0xFF
   359  }
   360  
   361  func (w WaitStatus) TrapCause() int {
   362  	if w.StopSignal() != SIGTRAP {
   363  		return -1
   364  	}
   365  	return int(w>>shift) >> 8
   366  }
   367  
   368  //sys	wait4(pid int, wstatus *_C_int, options int, rusage *Rusage) (wpid int, err error)
   369  
   370  func Wait4(pid int, wstatus *WaitStatus, options int, rusage *Rusage) (wpid int, err error) {
   371  	var status _C_int
   372  	wpid, err = wait4(pid, &status, options, rusage)
   373  	if wstatus != nil {
   374  		*wstatus = WaitStatus(status)
   375  	}
   376  	return
   377  }
   378  
   379  //sys	Waitid(idType int, id int, info *Siginfo, options int, rusage *Rusage) (err error)
   380  
   381  func Mkfifo(path string, mode uint32) error {
   382  	return Mknod(path, mode|S_IFIFO, 0)
   383  }
   384  
   385  func Mkfifoat(dirfd int, path string, mode uint32) error {
   386  	return Mknodat(dirfd, path, mode|S_IFIFO, 0)
   387  }
   388  
   389  func (sa *SockaddrInet4) sockaddr() (unsafe.Pointer, _Socklen, error) {
   390  	if sa.Port < 0 || sa.Port > 0xFFFF {
   391  		return nil, 0, EINVAL
   392  	}
   393  	sa.raw.Family = AF_INET
   394  	p := (*[2]byte)(unsafe.Pointer(&sa.raw.Port))
   395  	p[0] = byte(sa.Port >> 8)
   396  	p[1] = byte(sa.Port)
   397  	sa.raw.Addr = sa.Addr
   398  	return unsafe.Pointer(&sa.raw), SizeofSockaddrInet4, nil
   399  }
   400  
   401  func (sa *SockaddrInet6) sockaddr() (unsafe.Pointer, _Socklen, error) {
   402  	if sa.Port < 0 || sa.Port > 0xFFFF {
   403  		return nil, 0, EINVAL
   404  	}
   405  	sa.raw.Family = AF_INET6
   406  	p := (*[2]byte)(unsafe.Pointer(&sa.raw.Port))
   407  	p[0] = byte(sa.Port >> 8)
   408  	p[1] = byte(sa.Port)
   409  	sa.raw.Scope_id = sa.ZoneId
   410  	sa.raw.Addr = sa.Addr
   411  	return unsafe.Pointer(&sa.raw), SizeofSockaddrInet6, nil
   412  }
   413  
   414  func (sa *SockaddrUnix) sockaddr() (unsafe.Pointer, _Socklen, error) {
   415  	name := sa.Name
   416  	n := len(name)
   417  	if n >= len(sa.raw.Path) {
   418  		return nil, 0, EINVAL
   419  	}
   420  	sa.raw.Family = AF_UNIX
   421  	for i := range n {
   422  		sa.raw.Path[i] = int8(name[i])
   423  	}
   424  	// length is family (uint16), name, NUL.
   425  	sl := _Socklen(2)
   426  	if n > 0 {
   427  		sl += _Socklen(n) + 1
   428  	}
   429  	if sa.raw.Path[0] == '@' || (sa.raw.Path[0] == 0 && sl > 3) {
   430  		// Check sl > 3 so we don't change unnamed socket behavior.
   431  		sa.raw.Path[0] = 0
   432  		// Don't count trailing NUL for abstract address.
   433  		sl--
   434  	}
   435  
   436  	return unsafe.Pointer(&sa.raw), sl, nil
   437  }
   438  
   439  // SockaddrLinklayer implements the Sockaddr interface for AF_PACKET type sockets.
   440  type SockaddrLinklayer struct {
   441  	Protocol uint16
   442  	Ifindex  int
   443  	Hatype   uint16
   444  	Pkttype  uint8
   445  	Halen    uint8
   446  	Addr     [8]byte
   447  	raw      RawSockaddrLinklayer
   448  }
   449  
   450  func (sa *SockaddrLinklayer) sockaddr() (unsafe.Pointer, _Socklen, error) {
   451  	if sa.Ifindex < 0 || sa.Ifindex > 0x7fffffff {
   452  		return nil, 0, EINVAL
   453  	}
   454  	sa.raw.Family = AF_PACKET
   455  	sa.raw.Protocol = sa.Protocol
   456  	sa.raw.Ifindex = int32(sa.Ifindex)
   457  	sa.raw.Hatype = sa.Hatype
   458  	sa.raw.Pkttype = sa.Pkttype
   459  	sa.raw.Halen = sa.Halen
   460  	sa.raw.Addr = sa.Addr
   461  	return unsafe.Pointer(&sa.raw), SizeofSockaddrLinklayer, nil
   462  }
   463  
   464  // SockaddrNetlink implements the Sockaddr interface for AF_NETLINK type sockets.
   465  type SockaddrNetlink struct {
   466  	Family uint16
   467  	Pad    uint16
   468  	Pid    uint32
   469  	Groups uint32
   470  	raw    RawSockaddrNetlink
   471  }
   472  
   473  func (sa *SockaddrNetlink) sockaddr() (unsafe.Pointer, _Socklen, error) {
   474  	sa.raw.Family = AF_NETLINK
   475  	sa.raw.Pad = sa.Pad
   476  	sa.raw.Pid = sa.Pid
   477  	sa.raw.Groups = sa.Groups
   478  	return unsafe.Pointer(&sa.raw), SizeofSockaddrNetlink, nil
   479  }
   480  
   481  // SockaddrHCI implements the Sockaddr interface for AF_BLUETOOTH type sockets
   482  // using the HCI protocol.
   483  type SockaddrHCI struct {
   484  	Dev     uint16
   485  	Channel uint16
   486  	raw     RawSockaddrHCI
   487  }
   488  
   489  func (sa *SockaddrHCI) sockaddr() (unsafe.Pointer, _Socklen, error) {
   490  	sa.raw.Family = AF_BLUETOOTH
   491  	sa.raw.Dev = sa.Dev
   492  	sa.raw.Channel = sa.Channel
   493  	return unsafe.Pointer(&sa.raw), SizeofSockaddrHCI, nil
   494  }
   495  
   496  // SockaddrL2 implements the Sockaddr interface for AF_BLUETOOTH type sockets
   497  // using the L2CAP protocol.
   498  type SockaddrL2 struct {
   499  	PSM      uint16
   500  	CID      uint16
   501  	Addr     [6]uint8
   502  	AddrType uint8
   503  	raw      RawSockaddrL2
   504  }
   505  
   506  func (sa *SockaddrL2) sockaddr() (unsafe.Pointer, _Socklen, error) {
   507  	sa.raw.Family = AF_BLUETOOTH
   508  	psm := (*[2]byte)(unsafe.Pointer(&sa.raw.Psm))
   509  	psm[0] = byte(sa.PSM)
   510  	psm[1] = byte(sa.PSM >> 8)
   511  	for i := range len(sa.Addr) {
   512  		sa.raw.Bdaddr[i] = sa.Addr[len(sa.Addr)-1-i]
   513  	}
   514  	cid := (*[2]byte)(unsafe.Pointer(&sa.raw.Cid))
   515  	cid[0] = byte(sa.CID)
   516  	cid[1] = byte(sa.CID >> 8)
   517  	sa.raw.Bdaddr_type = sa.AddrType
   518  	return unsafe.Pointer(&sa.raw), SizeofSockaddrL2, nil
   519  }
   520  
   521  // SockaddrRFCOMM implements the Sockaddr interface for AF_BLUETOOTH type sockets
   522  // using the RFCOMM protocol.
   523  //
   524  // Server example:
   525  //
   526  //	fd, _ := Socket(AF_BLUETOOTH, SOCK_STREAM, BTPROTO_RFCOMM)
   527  //	_ = unix.Bind(fd, &unix.SockaddrRFCOMM{
   528  //		Channel: 1,
   529  //		Addr:    [6]uint8{0, 0, 0, 0, 0, 0}, // BDADDR_ANY or 00:00:00:00:00:00
   530  //	})
   531  //	_ = Listen(fd, 1)
   532  //	nfd, sa, _ := Accept(fd)
   533  //	fmt.Printf("conn addr=%v fd=%d", sa.(*unix.SockaddrRFCOMM).Addr, nfd)
   534  //	Read(nfd, buf)
   535  //
   536  // Client example:
   537  //
   538  //	fd, _ := Socket(AF_BLUETOOTH, SOCK_STREAM, BTPROTO_RFCOMM)
   539  //	_ = Connect(fd, &SockaddrRFCOMM{
   540  //		Channel: 1,
   541  //		Addr:    [6]byte{0x11, 0x22, 0x33, 0xaa, 0xbb, 0xcc}, // CC:BB:AA:33:22:11
   542  //	})
   543  //	Write(fd, []byte(`hello`))
   544  type SockaddrRFCOMM struct {
   545  	// Addr represents a bluetooth address, byte ordering is little-endian.
   546  	Addr [6]uint8
   547  
   548  	// Channel is a designated bluetooth channel, only 1-30 are available for use.
   549  	// Since Linux 2.6.7 and further zero value is the first available channel.
   550  	Channel uint8
   551  
   552  	raw RawSockaddrRFCOMM
   553  }
   554  
   555  func (sa *SockaddrRFCOMM) sockaddr() (unsafe.Pointer, _Socklen, error) {
   556  	sa.raw.Family = AF_BLUETOOTH
   557  	sa.raw.Channel = sa.Channel
   558  	sa.raw.Bdaddr = sa.Addr
   559  	return unsafe.Pointer(&sa.raw), SizeofSockaddrRFCOMM, nil
   560  }
   561  
   562  // SockaddrCAN implements the Sockaddr interface for AF_CAN type sockets.
   563  // The RxID and TxID fields are used for transport protocol addressing in
   564  // (CAN_TP16, CAN_TP20, CAN_MCNET, and CAN_ISOTP), they can be left with
   565  // zero values for CAN_RAW and CAN_BCM sockets as they have no meaning.
   566  //
   567  // The SockaddrCAN struct must be bound to the socket file descriptor
   568  // using Bind before the CAN socket can be used.
   569  //
   570  //	// Read one raw CAN frame
   571  //	fd, _ := Socket(AF_CAN, SOCK_RAW, CAN_RAW)
   572  //	addr := &SockaddrCAN{Ifindex: index}
   573  //	Bind(fd, addr)
   574  //	frame := make([]byte, 16)
   575  //	Read(fd, frame)
   576  //
   577  // The full SocketCAN documentation can be found in the linux kernel
   578  // archives at: https://www.kernel.org/doc/Documentation/networking/can.txt
   579  type SockaddrCAN struct {
   580  	Ifindex int
   581  	RxID    uint32
   582  	TxID    uint32
   583  	raw     RawSockaddrCAN
   584  }
   585  
   586  func (sa *SockaddrCAN) sockaddr() (unsafe.Pointer, _Socklen, error) {
   587  	if sa.Ifindex < 0 || sa.Ifindex > 0x7fffffff {
   588  		return nil, 0, EINVAL
   589  	}
   590  	sa.raw.Family = AF_CAN
   591  	sa.raw.Ifindex = int32(sa.Ifindex)
   592  	rx := (*[4]byte)(unsafe.Pointer(&sa.RxID))
   593  	for i := range 4 {
   594  		sa.raw.Addr[i] = rx[i]
   595  	}
   596  	tx := (*[4]byte)(unsafe.Pointer(&sa.TxID))
   597  	for i := range 4 {
   598  		sa.raw.Addr[i+4] = tx[i]
   599  	}
   600  	return unsafe.Pointer(&sa.raw), SizeofSockaddrCAN, nil
   601  }
   602  
   603  // SockaddrCANJ1939 implements the Sockaddr interface for AF_CAN using J1939
   604  // protocol (https://en.wikipedia.org/wiki/SAE_J1939). For more information
   605  // on the purposes of the fields, check the official linux kernel documentation
   606  // available here: https://www.kernel.org/doc/Documentation/networking/j1939.rst
   607  type SockaddrCANJ1939 struct {
   608  	Ifindex int
   609  	Name    uint64
   610  	PGN     uint32
   611  	Addr    uint8
   612  	raw     RawSockaddrCAN
   613  }
   614  
   615  func (sa *SockaddrCANJ1939) sockaddr() (unsafe.Pointer, _Socklen, error) {
   616  	if sa.Ifindex < 0 || sa.Ifindex > 0x7fffffff {
   617  		return nil, 0, EINVAL
   618  	}
   619  	sa.raw.Family = AF_CAN
   620  	sa.raw.Ifindex = int32(sa.Ifindex)
   621  	n := (*[8]byte)(unsafe.Pointer(&sa.Name))
   622  	for i := range 8 {
   623  		sa.raw.Addr[i] = n[i]
   624  	}
   625  	p := (*[4]byte)(unsafe.Pointer(&sa.PGN))
   626  	for i := range 4 {
   627  		sa.raw.Addr[i+8] = p[i]
   628  	}
   629  	sa.raw.Addr[12] = sa.Addr
   630  	return unsafe.Pointer(&sa.raw), SizeofSockaddrCAN, nil
   631  }
   632  
   633  // SockaddrALG implements the Sockaddr interface for AF_ALG type sockets.
   634  // SockaddrALG enables userspace access to the Linux kernel's cryptography
   635  // subsystem. The Type and Name fields specify which type of hash or cipher
   636  // should be used with a given socket.
   637  //
   638  // To create a file descriptor that provides access to a hash or cipher, both
   639  // Bind and Accept must be used. Once the setup process is complete, input
   640  // data can be written to the socket, processed by the kernel, and then read
   641  // back as hash output or ciphertext.
   642  //
   643  // Here is an example of using an AF_ALG socket with SHA1 hashing.
   644  // The initial socket setup process is as follows:
   645  //
   646  //	// Open a socket to perform SHA1 hashing.
   647  //	fd, _ := unix.Socket(unix.AF_ALG, unix.SOCK_SEQPACKET, 0)
   648  //	addr := &unix.SockaddrALG{Type: "hash", Name: "sha1"}
   649  //	unix.Bind(fd, addr)
   650  //	// Note: unix.Accept does not work at this time; must invoke accept()
   651  //	// manually using unix.Syscall.
   652  //	hashfd, _, _ := unix.Syscall(unix.SYS_ACCEPT, uintptr(fd), 0, 0)
   653  //
   654  // Once a file descriptor has been returned from Accept, it may be used to
   655  // perform SHA1 hashing. The descriptor is not safe for concurrent use, but
   656  // may be re-used repeatedly with subsequent Write and Read operations.
   657  //
   658  // When hashing a small byte slice or string, a single Write and Read may
   659  // be used:
   660  //
   661  //	// Assume hashfd is already configured using the setup process.
   662  //	hash := os.NewFile(hashfd, "sha1")
   663  //	// Hash an input string and read the results. Each Write discards
   664  //	// previous hash state. Read always reads the current state.
   665  //	b := make([]byte, 20)
   666  //	for i := 0; i < 2; i++ {
   667  //	    io.WriteString(hash, "Hello, world.")
   668  //	    hash.Read(b)
   669  //	    fmt.Println(hex.EncodeToString(b))
   670  //	}
   671  //	// Output:
   672  //	// 2ae01472317d1935a84797ec1983ae243fc6aa28
   673  //	// 2ae01472317d1935a84797ec1983ae243fc6aa28
   674  //
   675  // For hashing larger byte slices, or byte streams such as those read from
   676  // a file or socket, use Sendto with MSG_MORE to instruct the kernel to update
   677  // the hash digest instead of creating a new one for a given chunk and finalizing it.
   678  //
   679  //	// Assume hashfd and addr are already configured using the setup process.
   680  //	hash := os.NewFile(hashfd, "sha1")
   681  //	// Hash the contents of a file.
   682  //	f, _ := os.Open("/tmp/linux-4.10-rc7.tar.xz")
   683  //	b := make([]byte, 4096)
   684  //	for {
   685  //	    n, err := f.Read(b)
   686  //	    if err == io.EOF {
   687  //	        break
   688  //	    }
   689  //	    unix.Sendto(hashfd, b[:n], unix.MSG_MORE, addr)
   690  //	}
   691  //	hash.Read(b)
   692  //	fmt.Println(hex.EncodeToString(b))
   693  //	// Output: 85cdcad0c06eef66f805ecce353bec9accbeecc5
   694  //
   695  // For more information, see: http://www.chronox.de/crypto-API/crypto/userspace-if.html.
   696  type SockaddrALG struct {
   697  	Type    string
   698  	Name    string
   699  	Feature uint32
   700  	Mask    uint32
   701  	raw     RawSockaddrALG
   702  }
   703  
   704  func (sa *SockaddrALG) sockaddr() (unsafe.Pointer, _Socklen, error) {
   705  	// Leave room for NUL byte terminator.
   706  	if len(sa.Type) > len(sa.raw.Type)-1 {
   707  		return nil, 0, EINVAL
   708  	}
   709  	if len(sa.Name) > len(sa.raw.Name)-1 {
   710  		return nil, 0, EINVAL
   711  	}
   712  
   713  	sa.raw.Family = AF_ALG
   714  	sa.raw.Feat = sa.Feature
   715  	sa.raw.Mask = sa.Mask
   716  
   717  	copy(sa.raw.Type[:], sa.Type)
   718  	copy(sa.raw.Name[:], sa.Name)
   719  
   720  	return unsafe.Pointer(&sa.raw), SizeofSockaddrALG, nil
   721  }
   722  
   723  // SockaddrVM implements the Sockaddr interface for AF_VSOCK type sockets.
   724  // SockaddrVM provides access to Linux VM sockets: a mechanism that enables
   725  // bidirectional communication between a hypervisor and its guest virtual
   726  // machines.
   727  type SockaddrVM struct {
   728  	// CID and Port specify a context ID and port address for a VM socket.
   729  	// Guests have a unique CID, and hosts may have a well-known CID of:
   730  	//  - VMADDR_CID_HYPERVISOR: refers to the hypervisor process.
   731  	//  - VMADDR_CID_LOCAL: refers to local communication (loopback).
   732  	//  - VMADDR_CID_HOST: refers to other processes on the host.
   733  	CID   uint32
   734  	Port  uint32
   735  	Flags uint8
   736  	raw   RawSockaddrVM
   737  }
   738  
   739  func (sa *SockaddrVM) sockaddr() (unsafe.Pointer, _Socklen, error) {
   740  	sa.raw.Family = AF_VSOCK
   741  	sa.raw.Port = sa.Port
   742  	sa.raw.Cid = sa.CID
   743  	sa.raw.Flags = sa.Flags
   744  
   745  	return unsafe.Pointer(&sa.raw), SizeofSockaddrVM, nil
   746  }
   747  
   748  type SockaddrXDP struct {
   749  	Flags        uint16
   750  	Ifindex      uint32
   751  	QueueID      uint32
   752  	SharedUmemFD uint32
   753  	raw          RawSockaddrXDP
   754  }
   755  
   756  func (sa *SockaddrXDP) sockaddr() (unsafe.Pointer, _Socklen, error) {
   757  	sa.raw.Family = AF_XDP
   758  	sa.raw.Flags = sa.Flags
   759  	sa.raw.Ifindex = sa.Ifindex
   760  	sa.raw.Queue_id = sa.QueueID
   761  	sa.raw.Shared_umem_fd = sa.SharedUmemFD
   762  
   763  	return unsafe.Pointer(&sa.raw), SizeofSockaddrXDP, nil
   764  }
   765  
   766  // This constant mirrors the #define of PX_PROTO_OE in
   767  // linux/if_pppox.h. We're defining this by hand here instead of
   768  // autogenerating through mkerrors.sh because including
   769  // linux/if_pppox.h causes some declaration conflicts with other
   770  // includes (linux/if_pppox.h includes linux/in.h, which conflicts
   771  // with netinet/in.h). Given that we only need a single zero constant
   772  // out of that file, it's cleaner to just define it by hand here.
   773  const px_proto_oe = 0
   774  
   775  type SockaddrPPPoE struct {
   776  	SID    uint16
   777  	Remote []byte
   778  	Dev    string
   779  	raw    RawSockaddrPPPoX
   780  }
   781  
   782  func (sa *SockaddrPPPoE) sockaddr() (unsafe.Pointer, _Socklen, error) {
   783  	if len(sa.Remote) != 6 {
   784  		return nil, 0, EINVAL
   785  	}
   786  	if len(sa.Dev) > IFNAMSIZ-1 {
   787  		return nil, 0, EINVAL
   788  	}
   789  
   790  	*(*uint16)(unsafe.Pointer(&sa.raw[0])) = AF_PPPOX
   791  	// This next field is in host-endian byte order. We can't use the
   792  	// same unsafe pointer cast as above, because this value is not
   793  	// 32-bit aligned and some architectures don't allow unaligned
   794  	// access.
   795  	//
   796  	// However, the value of px_proto_oe is 0, so we can use
   797  	// encoding/binary helpers to write the bytes without worrying
   798  	// about the ordering.
   799  	binary.BigEndian.PutUint32(sa.raw[2:6], px_proto_oe)
   800  	// This field is deliberately big-endian, unlike the previous
   801  	// one. The kernel expects SID to be in network byte order.
   802  	binary.BigEndian.PutUint16(sa.raw[6:8], sa.SID)
   803  	copy(sa.raw[8:14], sa.Remote)
   804  	clear(sa.raw[14 : 14+IFNAMSIZ])
   805  	copy(sa.raw[14:], sa.Dev)
   806  	return unsafe.Pointer(&sa.raw), SizeofSockaddrPPPoX, nil
   807  }
   808  
   809  // SockaddrTIPC implements the Sockaddr interface for AF_TIPC type sockets.
   810  // For more information on TIPC, see: http://tipc.sourceforge.net/.
   811  type SockaddrTIPC struct {
   812  	// Scope is the publication scopes when binding service/service range.
   813  	// Should be set to TIPC_CLUSTER_SCOPE or TIPC_NODE_SCOPE.
   814  	Scope int
   815  
   816  	// Addr is the type of address used to manipulate a socket. Addr must be
   817  	// one of:
   818  	//  - *TIPCSocketAddr: "id" variant in the C addr union
   819  	//  - *TIPCServiceRange: "nameseq" variant in the C addr union
   820  	//  - *TIPCServiceName: "name" variant in the C addr union
   821  	//
   822  	// If nil, EINVAL will be returned when the structure is used.
   823  	Addr TIPCAddr
   824  
   825  	raw RawSockaddrTIPC
   826  }
   827  
   828  // TIPCAddr is implemented by types that can be used as an address for
   829  // SockaddrTIPC. It is only implemented by *TIPCSocketAddr, *TIPCServiceRange,
   830  // and *TIPCServiceName.
   831  type TIPCAddr interface {
   832  	tipcAddrtype() uint8
   833  	tipcAddr() [12]byte
   834  }
   835  
   836  func (sa *TIPCSocketAddr) tipcAddr() [12]byte {
   837  	var out [12]byte
   838  	copy(out[:], (*(*[unsafe.Sizeof(TIPCSocketAddr{})]byte)(unsafe.Pointer(sa)))[:])
   839  	return out
   840  }
   841  
   842  func (sa *TIPCSocketAddr) tipcAddrtype() uint8 { return TIPC_SOCKET_ADDR }
   843  
   844  func (sa *TIPCServiceRange) tipcAddr() [12]byte {
   845  	var out [12]byte
   846  	copy(out[:], (*(*[unsafe.Sizeof(TIPCServiceRange{})]byte)(unsafe.Pointer(sa)))[:])
   847  	return out
   848  }
   849  
   850  func (sa *TIPCServiceRange) tipcAddrtype() uint8 { return TIPC_SERVICE_RANGE }
   851  
   852  func (sa *TIPCServiceName) tipcAddr() [12]byte {
   853  	var out [12]byte
   854  	copy(out[:], (*(*[unsafe.Sizeof(TIPCServiceName{})]byte)(unsafe.Pointer(sa)))[:])
   855  	return out
   856  }
   857  
   858  func (sa *TIPCServiceName) tipcAddrtype() uint8 { return TIPC_SERVICE_ADDR }
   859  
   860  func (sa *SockaddrTIPC) sockaddr() (unsafe.Pointer, _Socklen, error) {
   861  	if sa.Addr == nil {
   862  		return nil, 0, EINVAL
   863  	}
   864  	sa.raw.Family = AF_TIPC
   865  	sa.raw.Scope = int8(sa.Scope)
   866  	sa.raw.Addrtype = sa.Addr.tipcAddrtype()
   867  	sa.raw.Addr = sa.Addr.tipcAddr()
   868  	return unsafe.Pointer(&sa.raw), SizeofSockaddrTIPC, nil
   869  }
   870  
   871  // SockaddrL2TPIP implements the Sockaddr interface for IPPROTO_L2TP/AF_INET sockets.
   872  type SockaddrL2TPIP struct {
   873  	Addr   [4]byte
   874  	ConnId uint32
   875  	raw    RawSockaddrL2TPIP
   876  }
   877  
   878  func (sa *SockaddrL2TPIP) sockaddr() (unsafe.Pointer, _Socklen, error) {
   879  	sa.raw.Family = AF_INET
   880  	sa.raw.Conn_id = sa.ConnId
   881  	sa.raw.Addr = sa.Addr
   882  	return unsafe.Pointer(&sa.raw), SizeofSockaddrL2TPIP, nil
   883  }
   884  
   885  // SockaddrL2TPIP6 implements the Sockaddr interface for IPPROTO_L2TP/AF_INET6 sockets.
   886  type SockaddrL2TPIP6 struct {
   887  	Addr   [16]byte
   888  	ZoneId uint32
   889  	ConnId uint32
   890  	raw    RawSockaddrL2TPIP6
   891  }
   892  
   893  func (sa *SockaddrL2TPIP6) sockaddr() (unsafe.Pointer, _Socklen, error) {
   894  	sa.raw.Family = AF_INET6
   895  	sa.raw.Conn_id = sa.ConnId
   896  	sa.raw.Scope_id = sa.ZoneId
   897  	sa.raw.Addr = sa.Addr
   898  	return unsafe.Pointer(&sa.raw), SizeofSockaddrL2TPIP6, nil
   899  }
   900  
   901  // SockaddrIUCV implements the Sockaddr interface for AF_IUCV sockets.
   902  type SockaddrIUCV struct {
   903  	UserID string
   904  	Name   string
   905  	raw    RawSockaddrIUCV
   906  }
   907  
   908  func (sa *SockaddrIUCV) sockaddr() (unsafe.Pointer, _Socklen, error) {
   909  	sa.raw.Family = AF_IUCV
   910  	// These are EBCDIC encoded by the kernel, but we still need to pad them
   911  	// with blanks. Initializing with blanks allows the caller to feed in either
   912  	// a padded or an unpadded string.
   913  	for i := range 8 {
   914  		sa.raw.Nodeid[i] = ' '
   915  		sa.raw.User_id[i] = ' '
   916  		sa.raw.Name[i] = ' '
   917  	}
   918  	if len(sa.UserID) > 8 || len(sa.Name) > 8 {
   919  		return nil, 0, EINVAL
   920  	}
   921  	for i, b := range []byte(sa.UserID[:]) {
   922  		sa.raw.User_id[i] = int8(b)
   923  	}
   924  	for i, b := range []byte(sa.Name[:]) {
   925  		sa.raw.Name[i] = int8(b)
   926  	}
   927  	return unsafe.Pointer(&sa.raw), SizeofSockaddrIUCV, nil
   928  }
   929  
   930  type SockaddrNFC struct {
   931  	DeviceIdx   uint32
   932  	TargetIdx   uint32
   933  	NFCProtocol uint32
   934  	raw         RawSockaddrNFC
   935  }
   936  
   937  func (sa *SockaddrNFC) sockaddr() (unsafe.Pointer, _Socklen, error) {
   938  	sa.raw.Sa_family = AF_NFC
   939  	sa.raw.Dev_idx = sa.DeviceIdx
   940  	sa.raw.Target_idx = sa.TargetIdx
   941  	sa.raw.Nfc_protocol = sa.NFCProtocol
   942  	return unsafe.Pointer(&sa.raw), SizeofSockaddrNFC, nil
   943  }
   944  
   945  type SockaddrNFCLLCP struct {
   946  	DeviceIdx      uint32
   947  	TargetIdx      uint32
   948  	NFCProtocol    uint32
   949  	DestinationSAP uint8
   950  	SourceSAP      uint8
   951  	ServiceName    string
   952  	raw            RawSockaddrNFCLLCP
   953  }
   954  
   955  func (sa *SockaddrNFCLLCP) sockaddr() (unsafe.Pointer, _Socklen, error) {
   956  	sa.raw.Sa_family = AF_NFC
   957  	sa.raw.Dev_idx = sa.DeviceIdx
   958  	sa.raw.Target_idx = sa.TargetIdx
   959  	sa.raw.Nfc_protocol = sa.NFCProtocol
   960  	sa.raw.Dsap = sa.DestinationSAP
   961  	sa.raw.Ssap = sa.SourceSAP
   962  	if len(sa.ServiceName) > len(sa.raw.Service_name) {
   963  		return nil, 0, EINVAL
   964  	}
   965  	copy(sa.raw.Service_name[:], sa.ServiceName)
   966  	sa.raw.SetServiceNameLen(len(sa.ServiceName))
   967  	return unsafe.Pointer(&sa.raw), SizeofSockaddrNFCLLCP, nil
   968  }
   969  
   970  var socketProtocol = func(fd int) (int, error) {
   971  	return GetsockoptInt(fd, SOL_SOCKET, SO_PROTOCOL)
   972  }
   973  
   974  func anyToSockaddr(fd int, rsa *RawSockaddrAny) (Sockaddr, error) {
   975  	switch rsa.Addr.Family {
   976  	case AF_NETLINK:
   977  		pp := (*RawSockaddrNetlink)(unsafe.Pointer(rsa))
   978  		sa := new(SockaddrNetlink)
   979  		sa.Family = pp.Family
   980  		sa.Pad = pp.Pad
   981  		sa.Pid = pp.Pid
   982  		sa.Groups = pp.Groups
   983  		return sa, nil
   984  
   985  	case AF_PACKET:
   986  		pp := (*RawSockaddrLinklayer)(unsafe.Pointer(rsa))
   987  		sa := new(SockaddrLinklayer)
   988  		sa.Protocol = pp.Protocol
   989  		sa.Ifindex = int(pp.Ifindex)
   990  		sa.Hatype = pp.Hatype
   991  		sa.Pkttype = pp.Pkttype
   992  		sa.Halen = pp.Halen
   993  		sa.Addr = pp.Addr
   994  		return sa, nil
   995  
   996  	case AF_UNIX:
   997  		pp := (*RawSockaddrUnix)(unsafe.Pointer(rsa))
   998  		sa := new(SockaddrUnix)
   999  		if pp.Path[0] == 0 {
  1000  			// "Abstract" Unix domain socket.
  1001  			// Rewrite leading NUL as @ for textual display.
  1002  			// (This is the standard convention.)
  1003  			// Not friendly to overwrite in place,
  1004  			// but the callers below don't care.
  1005  			pp.Path[0] = '@'
  1006  		}
  1007  
  1008  		// Assume path ends at NUL.
  1009  		// This is not technically the Linux semantics for
  1010  		// abstract Unix domain sockets--they are supposed
  1011  		// to be uninterpreted fixed-size binary blobs--but
  1012  		// everyone uses this convention.
  1013  		n := 0
  1014  		for n < len(pp.Path) && pp.Path[n] != 0 {
  1015  			n++
  1016  		}
  1017  		sa.Name = string(unsafe.Slice((*byte)(unsafe.Pointer(&pp.Path[0])), n))
  1018  		return sa, nil
  1019  
  1020  	case AF_INET:
  1021  		proto, err := socketProtocol(fd)
  1022  		if err != nil {
  1023  			return nil, err
  1024  		}
  1025  
  1026  		switch proto {
  1027  		case IPPROTO_L2TP:
  1028  			pp := (*RawSockaddrL2TPIP)(unsafe.Pointer(rsa))
  1029  			sa := new(SockaddrL2TPIP)
  1030  			sa.ConnId = pp.Conn_id
  1031  			sa.Addr = pp.Addr
  1032  			return sa, nil
  1033  		default:
  1034  			pp := (*RawSockaddrInet4)(unsafe.Pointer(rsa))
  1035  			sa := new(SockaddrInet4)
  1036  			p := (*[2]byte)(unsafe.Pointer(&pp.Port))
  1037  			sa.Port = int(p[0])<<8 + int(p[1])
  1038  			sa.Addr = pp.Addr
  1039  			return sa, nil
  1040  		}
  1041  
  1042  	case AF_INET6:
  1043  		proto, err := socketProtocol(fd)
  1044  		if err != nil {
  1045  			return nil, err
  1046  		}
  1047  
  1048  		switch proto {
  1049  		case IPPROTO_L2TP:
  1050  			pp := (*RawSockaddrL2TPIP6)(unsafe.Pointer(rsa))
  1051  			sa := new(SockaddrL2TPIP6)
  1052  			sa.ConnId = pp.Conn_id
  1053  			sa.ZoneId = pp.Scope_id
  1054  			sa.Addr = pp.Addr
  1055  			return sa, nil
  1056  		default:
  1057  			pp := (*RawSockaddrInet6)(unsafe.Pointer(rsa))
  1058  			sa := new(SockaddrInet6)
  1059  			p := (*[2]byte)(unsafe.Pointer(&pp.Port))
  1060  			sa.Port = int(p[0])<<8 + int(p[1])
  1061  			sa.ZoneId = pp.Scope_id
  1062  			sa.Addr = pp.Addr
  1063  			return sa, nil
  1064  		}
  1065  
  1066  	case AF_VSOCK:
  1067  		pp := (*RawSockaddrVM)(unsafe.Pointer(rsa))
  1068  		sa := &SockaddrVM{
  1069  			CID:   pp.Cid,
  1070  			Port:  pp.Port,
  1071  			Flags: pp.Flags,
  1072  		}
  1073  		return sa, nil
  1074  	case AF_BLUETOOTH:
  1075  		proto, err := socketProtocol(fd)
  1076  		if err != nil {
  1077  			return nil, err
  1078  		}
  1079  		// only BTPROTO_L2CAP and BTPROTO_RFCOMM can accept connections
  1080  		switch proto {
  1081  		case BTPROTO_L2CAP:
  1082  			pp := (*RawSockaddrL2)(unsafe.Pointer(rsa))
  1083  			sa := &SockaddrL2{
  1084  				PSM:      pp.Psm,
  1085  				CID:      pp.Cid,
  1086  				Addr:     pp.Bdaddr,
  1087  				AddrType: pp.Bdaddr_type,
  1088  			}
  1089  			return sa, nil
  1090  		case BTPROTO_RFCOMM:
  1091  			pp := (*RawSockaddrRFCOMM)(unsafe.Pointer(rsa))
  1092  			sa := &SockaddrRFCOMM{
  1093  				Channel: pp.Channel,
  1094  				Addr:    pp.Bdaddr,
  1095  			}
  1096  			return sa, nil
  1097  		}
  1098  	case AF_XDP:
  1099  		pp := (*RawSockaddrXDP)(unsafe.Pointer(rsa))
  1100  		sa := &SockaddrXDP{
  1101  			Flags:        pp.Flags,
  1102  			Ifindex:      pp.Ifindex,
  1103  			QueueID:      pp.Queue_id,
  1104  			SharedUmemFD: pp.Shared_umem_fd,
  1105  		}
  1106  		return sa, nil
  1107  	case AF_PPPOX:
  1108  		pp := (*RawSockaddrPPPoX)(unsafe.Pointer(rsa))
  1109  		if binary.BigEndian.Uint32(pp[2:6]) != px_proto_oe {
  1110  			return nil, EINVAL
  1111  		}
  1112  		sa := &SockaddrPPPoE{
  1113  			SID:    binary.BigEndian.Uint16(pp[6:8]),
  1114  			Remote: pp[8:14],
  1115  		}
  1116  		for i := 14; i < 14+IFNAMSIZ; i++ {
  1117  			if pp[i] == 0 {
  1118  				sa.Dev = string(pp[14:i])
  1119  				break
  1120  			}
  1121  		}
  1122  		return sa, nil
  1123  	case AF_TIPC:
  1124  		pp := (*RawSockaddrTIPC)(unsafe.Pointer(rsa))
  1125  
  1126  		sa := &SockaddrTIPC{
  1127  			Scope: int(pp.Scope),
  1128  		}
  1129  
  1130  		// Determine which union variant is present in pp.Addr by checking
  1131  		// pp.Addrtype.
  1132  		switch pp.Addrtype {
  1133  		case TIPC_SERVICE_RANGE:
  1134  			sa.Addr = (*TIPCServiceRange)(unsafe.Pointer(&pp.Addr))
  1135  		case TIPC_SERVICE_ADDR:
  1136  			sa.Addr = (*TIPCServiceName)(unsafe.Pointer(&pp.Addr))
  1137  		case TIPC_SOCKET_ADDR:
  1138  			sa.Addr = (*TIPCSocketAddr)(unsafe.Pointer(&pp.Addr))
  1139  		default:
  1140  			return nil, EINVAL
  1141  		}
  1142  
  1143  		return sa, nil
  1144  	case AF_IUCV:
  1145  		pp := (*RawSockaddrIUCV)(unsafe.Pointer(rsa))
  1146  
  1147  		var user [8]byte
  1148  		var name [8]byte
  1149  
  1150  		for i := range 8 {
  1151  			user[i] = byte(pp.User_id[i])
  1152  			name[i] = byte(pp.Name[i])
  1153  		}
  1154  
  1155  		sa := &SockaddrIUCV{
  1156  			UserID: string(user[:]),
  1157  			Name:   string(name[:]),
  1158  		}
  1159  		return sa, nil
  1160  
  1161  	case AF_CAN:
  1162  		proto, err := socketProtocol(fd)
  1163  		if err != nil {
  1164  			return nil, err
  1165  		}
  1166  
  1167  		pp := (*RawSockaddrCAN)(unsafe.Pointer(rsa))
  1168  
  1169  		switch proto {
  1170  		case CAN_J1939:
  1171  			sa := &SockaddrCANJ1939{
  1172  				Ifindex: int(pp.Ifindex),
  1173  			}
  1174  			name := (*[8]byte)(unsafe.Pointer(&sa.Name))
  1175  			for i := range 8 {
  1176  				name[i] = pp.Addr[i]
  1177  			}
  1178  			pgn := (*[4]byte)(unsafe.Pointer(&sa.PGN))
  1179  			for i := range 4 {
  1180  				pgn[i] = pp.Addr[i+8]
  1181  			}
  1182  			addr := (*[1]byte)(unsafe.Pointer(&sa.Addr))
  1183  			addr[0] = pp.Addr[12]
  1184  			return sa, nil
  1185  		default:
  1186  			sa := &SockaddrCAN{
  1187  				Ifindex: int(pp.Ifindex),
  1188  			}
  1189  			rx := (*[4]byte)(unsafe.Pointer(&sa.RxID))
  1190  			for i := range 4 {
  1191  				rx[i] = pp.Addr[i]
  1192  			}
  1193  			tx := (*[4]byte)(unsafe.Pointer(&sa.TxID))
  1194  			for i := range 4 {
  1195  				tx[i] = pp.Addr[i+4]
  1196  			}
  1197  			return sa, nil
  1198  		}
  1199  	case AF_NFC:
  1200  		proto, err := socketProtocol(fd)
  1201  		if err != nil {
  1202  			return nil, err
  1203  		}
  1204  		switch proto {
  1205  		case NFC_SOCKPROTO_RAW:
  1206  			pp := (*RawSockaddrNFC)(unsafe.Pointer(rsa))
  1207  			sa := &SockaddrNFC{
  1208  				DeviceIdx:   pp.Dev_idx,
  1209  				TargetIdx:   pp.Target_idx,
  1210  				NFCProtocol: pp.Nfc_protocol,
  1211  			}
  1212  			return sa, nil
  1213  		case NFC_SOCKPROTO_LLCP:
  1214  			pp := (*RawSockaddrNFCLLCP)(unsafe.Pointer(rsa))
  1215  			if uint64(pp.Service_name_len) > uint64(len(pp.Service_name)) {
  1216  				return nil, EINVAL
  1217  			}
  1218  			sa := &SockaddrNFCLLCP{
  1219  				DeviceIdx:      pp.Dev_idx,
  1220  				TargetIdx:      pp.Target_idx,
  1221  				NFCProtocol:    pp.Nfc_protocol,
  1222  				DestinationSAP: pp.Dsap,
  1223  				SourceSAP:      pp.Ssap,
  1224  				ServiceName:    string(pp.Service_name[:pp.Service_name_len]),
  1225  			}
  1226  			return sa, nil
  1227  		default:
  1228  			return nil, EINVAL
  1229  		}
  1230  	}
  1231  	return nil, EAFNOSUPPORT
  1232  }
  1233  
  1234  func Accept(fd int) (nfd int, sa Sockaddr, err error) {
  1235  	var rsa RawSockaddrAny
  1236  	var len _Socklen = SizeofSockaddrAny
  1237  	nfd, err = accept4(fd, &rsa, &len, 0)
  1238  	if err != nil {
  1239  		return
  1240  	}
  1241  	sa, err = anyToSockaddr(fd, &rsa)
  1242  	if err != nil {
  1243  		Close(nfd)
  1244  		nfd = 0
  1245  	}
  1246  	return
  1247  }
  1248  
  1249  func Accept4(fd int, flags int) (nfd int, sa Sockaddr, err error) {
  1250  	var rsa RawSockaddrAny
  1251  	var len _Socklen = SizeofSockaddrAny
  1252  	nfd, err = accept4(fd, &rsa, &len, flags)
  1253  	if err != nil {
  1254  		return
  1255  	}
  1256  	if len > SizeofSockaddrAny {
  1257  		panic("RawSockaddrAny too small")
  1258  	}
  1259  	sa, err = anyToSockaddr(fd, &rsa)
  1260  	if err != nil {
  1261  		Close(nfd)
  1262  		nfd = 0
  1263  	}
  1264  	return
  1265  }
  1266  
  1267  func Getsockname(fd int) (sa Sockaddr, err error) {
  1268  	var rsa RawSockaddrAny
  1269  	var len _Socklen = SizeofSockaddrAny
  1270  	if err = getsockname(fd, &rsa, &len); err != nil {
  1271  		return
  1272  	}
  1273  	return anyToSockaddr(fd, &rsa)
  1274  }
  1275  
  1276  func GetsockoptIPMreqn(fd, level, opt int) (*IPMreqn, error) {
  1277  	var value IPMreqn
  1278  	vallen := _Socklen(SizeofIPMreqn)
  1279  	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
  1280  	return &value, err
  1281  }
  1282  
  1283  func GetsockoptUcred(fd, level, opt int) (*Ucred, error) {
  1284  	var value Ucred
  1285  	vallen := _Socklen(SizeofUcred)
  1286  	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
  1287  	return &value, err
  1288  }
  1289  
  1290  func GetsockoptTCPInfo(fd, level, opt int) (*TCPInfo, error) {
  1291  	var value TCPInfo
  1292  	vallen := _Socklen(SizeofTCPInfo)
  1293  	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
  1294  	return &value, err
  1295  }
  1296  
  1297  // GetsockoptTCPCCVegasInfo returns algorithm specific congestion control information for a socket using the "vegas"
  1298  // algorithm.
  1299  //
  1300  // The socket's congestion control algorighm can be retrieved via [GetsockoptString] with the [TCP_CONGESTION] option:
  1301  //
  1302  //	algo, err := unix.GetsockoptString(fd, unix.IPPROTO_TCP, unix.TCP_CONGESTION)
  1303  func GetsockoptTCPCCVegasInfo(fd, level, opt int) (*TCPVegasInfo, error) {
  1304  	var value [SizeofTCPCCInfo / 4]uint32 // ensure proper alignment
  1305  	vallen := _Socklen(SizeofTCPCCInfo)
  1306  	err := getsockopt(fd, level, opt, unsafe.Pointer(&value[0]), &vallen)
  1307  	out := (*TCPVegasInfo)(unsafe.Pointer(&value[0]))
  1308  	return out, err
  1309  }
  1310  
  1311  // GetsockoptTCPCCDCTCPInfo returns algorithm specific congestion control information for a socket using the "dctp"
  1312  // algorithm.
  1313  //
  1314  // The socket's congestion control algorighm can be retrieved via [GetsockoptString] with the [TCP_CONGESTION] option:
  1315  //
  1316  //	algo, err := unix.GetsockoptString(fd, unix.IPPROTO_TCP, unix.TCP_CONGESTION)
  1317  func GetsockoptTCPCCDCTCPInfo(fd, level, opt int) (*TCPDCTCPInfo, error) {
  1318  	var value [SizeofTCPCCInfo / 4]uint32 // ensure proper alignment
  1319  	vallen := _Socklen(SizeofTCPCCInfo)
  1320  	err := getsockopt(fd, level, opt, unsafe.Pointer(&value[0]), &vallen)
  1321  	out := (*TCPDCTCPInfo)(unsafe.Pointer(&value[0]))
  1322  	return out, err
  1323  }
  1324  
  1325  // GetsockoptTCPCCBBRInfo returns algorithm specific congestion control information for a socket using the "bbr"
  1326  // algorithm.
  1327  //
  1328  // The socket's congestion control algorighm can be retrieved via [GetsockoptString] with the [TCP_CONGESTION] option:
  1329  //
  1330  //	algo, err := unix.GetsockoptString(fd, unix.IPPROTO_TCP, unix.TCP_CONGESTION)
  1331  func GetsockoptTCPCCBBRInfo(fd, level, opt int) (*TCPBBRInfo, error) {
  1332  	var value [SizeofTCPCCInfo / 4]uint32 // ensure proper alignment
  1333  	vallen := _Socklen(SizeofTCPCCInfo)
  1334  	err := getsockopt(fd, level, opt, unsafe.Pointer(&value[0]), &vallen)
  1335  	out := (*TCPBBRInfo)(unsafe.Pointer(&value[0]))
  1336  	return out, err
  1337  }
  1338  
  1339  // GetsockoptString returns the string value of the socket option opt for the
  1340  // socket associated with fd at the given socket level.
  1341  func GetsockoptString(fd, level, opt int) (string, error) {
  1342  	buf := make([]byte, 256)
  1343  	vallen := _Socklen(len(buf))
  1344  	err := getsockopt(fd, level, opt, unsafe.Pointer(&buf[0]), &vallen)
  1345  	if err != nil {
  1346  		if err == ERANGE {
  1347  			buf = make([]byte, vallen)
  1348  			err = getsockopt(fd, level, opt, unsafe.Pointer(&buf[0]), &vallen)
  1349  		}
  1350  		if err != nil {
  1351  			return "", err
  1352  		}
  1353  	}
  1354  	return ByteSliceToString(buf[:vallen]), nil
  1355  }
  1356  
  1357  func GetsockoptTpacketStats(fd, level, opt int) (*TpacketStats, error) {
  1358  	var value TpacketStats
  1359  	vallen := _Socklen(SizeofTpacketStats)
  1360  	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
  1361  	return &value, err
  1362  }
  1363  
  1364  func GetsockoptTpacketStatsV3(fd, level, opt int) (*TpacketStatsV3, error) {
  1365  	var value TpacketStatsV3
  1366  	vallen := _Socklen(SizeofTpacketStatsV3)
  1367  	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
  1368  	return &value, err
  1369  }
  1370  
  1371  func SetsockoptIPMreqn(fd, level, opt int, mreq *IPMreqn) (err error) {
  1372  	return setsockopt(fd, level, opt, unsafe.Pointer(mreq), unsafe.Sizeof(*mreq))
  1373  }
  1374  
  1375  func SetsockoptPacketMreq(fd, level, opt int, mreq *PacketMreq) error {
  1376  	return setsockopt(fd, level, opt, unsafe.Pointer(mreq), unsafe.Sizeof(*mreq))
  1377  }
  1378  
  1379  // SetsockoptSockFprog attaches a classic BPF or an extended BPF program to a
  1380  // socket to filter incoming packets.  See 'man 7 socket' for usage information.
  1381  func SetsockoptSockFprog(fd, level, opt int, fprog *SockFprog) error {
  1382  	return setsockopt(fd, level, opt, unsafe.Pointer(fprog), unsafe.Sizeof(*fprog))
  1383  }
  1384  
  1385  func SetsockoptCanRawFilter(fd, level, opt int, filter []CanFilter) error {
  1386  	var p unsafe.Pointer
  1387  	if len(filter) > 0 {
  1388  		p = unsafe.Pointer(&filter[0])
  1389  	}
  1390  	return setsockopt(fd, level, opt, p, uintptr(len(filter)*SizeofCanFilter))
  1391  }
  1392  
  1393  func SetsockoptTpacketReq(fd, level, opt int, tp *TpacketReq) error {
  1394  	return setsockopt(fd, level, opt, unsafe.Pointer(tp), unsafe.Sizeof(*tp))
  1395  }
  1396  
  1397  func SetsockoptTpacketReq3(fd, level, opt int, tp *TpacketReq3) error {
  1398  	return setsockopt(fd, level, opt, unsafe.Pointer(tp), unsafe.Sizeof(*tp))
  1399  }
  1400  
  1401  func SetsockoptTCPRepairOpt(fd, level, opt int, o []TCPRepairOpt) (err error) {
  1402  	if len(o) == 0 {
  1403  		return EINVAL
  1404  	}
  1405  	return setsockopt(fd, level, opt, unsafe.Pointer(&o[0]), uintptr(SizeofTCPRepairOpt*len(o)))
  1406  }
  1407  
  1408  func SetsockoptTCPMD5Sig(fd, level, opt int, s *TCPMD5Sig) error {
  1409  	return setsockopt(fd, level, opt, unsafe.Pointer(s), unsafe.Sizeof(*s))
  1410  }
  1411  
  1412  // Keyctl Commands (http://man7.org/linux/man-pages/man2/keyctl.2.html)
  1413  
  1414  // KeyctlInt calls keyctl commands in which each argument is an int.
  1415  // These commands are KEYCTL_REVOKE, KEYCTL_CHOWN, KEYCTL_CLEAR, KEYCTL_LINK,
  1416  // KEYCTL_UNLINK, KEYCTL_NEGATE, KEYCTL_SET_REQKEY_KEYRING, KEYCTL_SET_TIMEOUT,
  1417  // KEYCTL_ASSUME_AUTHORITY, KEYCTL_SESSION_TO_PARENT, KEYCTL_REJECT,
  1418  // KEYCTL_INVALIDATE, and KEYCTL_GET_PERSISTENT.
  1419  //sys	KeyctlInt(cmd int, arg2 int, arg3 int, arg4 int, arg5 int) (ret int, err error) = SYS_KEYCTL
  1420  
  1421  // KeyctlBuffer calls keyctl commands in which the third and fourth
  1422  // arguments are a buffer and its length, respectively.
  1423  // These commands are KEYCTL_UPDATE, KEYCTL_READ, and KEYCTL_INSTANTIATE.
  1424  //sys	KeyctlBuffer(cmd int, arg2 int, buf []byte, arg5 int) (ret int, err error) = SYS_KEYCTL
  1425  
  1426  // KeyctlString calls keyctl commands which return a string.
  1427  // These commands are KEYCTL_DESCRIBE and KEYCTL_GET_SECURITY.
  1428  func KeyctlString(cmd int, id int) (string, error) {
  1429  	// We must loop as the string data may change in between the syscalls.
  1430  	// We could allocate a large buffer here to reduce the chance that the
  1431  	// syscall needs to be called twice; however, this is unnecessary as
  1432  	// the performance loss is negligible.
  1433  	var buffer []byte
  1434  	for {
  1435  		// Try to fill the buffer with data
  1436  		length, err := KeyctlBuffer(cmd, id, buffer, 0)
  1437  		if err != nil {
  1438  			return "", err
  1439  		}
  1440  
  1441  		// Check if the data was written
  1442  		if length <= len(buffer) {
  1443  			// Exclude the null terminator
  1444  			return string(buffer[:length-1]), nil
  1445  		}
  1446  
  1447  		// Make a bigger buffer if needed
  1448  		buffer = make([]byte, length)
  1449  	}
  1450  }
  1451  
  1452  // Keyctl commands with special signatures.
  1453  
  1454  // KeyctlGetKeyringID implements the KEYCTL_GET_KEYRING_ID command.
  1455  // See the full documentation at:
  1456  // http://man7.org/linux/man-pages/man3/keyctl_get_keyring_ID.3.html
  1457  func KeyctlGetKeyringID(id int, create bool) (ringid int, err error) {
  1458  	createInt := 0
  1459  	if create {
  1460  		createInt = 1
  1461  	}
  1462  	return KeyctlInt(KEYCTL_GET_KEYRING_ID, id, createInt, 0, 0)
  1463  }
  1464  
  1465  // KeyctlSetperm implements the KEYCTL_SETPERM command. The perm value is the
  1466  // key handle permission mask as described in the "keyctl setperm" section of
  1467  // http://man7.org/linux/man-pages/man1/keyctl.1.html.
  1468  // See the full documentation at:
  1469  // http://man7.org/linux/man-pages/man3/keyctl_setperm.3.html
  1470  func KeyctlSetperm(id int, perm uint32) error {
  1471  	_, err := KeyctlInt(KEYCTL_SETPERM, id, int(perm), 0, 0)
  1472  	return err
  1473  }
  1474  
  1475  //sys	keyctlJoin(cmd int, arg2 string) (ret int, err error) = SYS_KEYCTL
  1476  
  1477  // KeyctlJoinSessionKeyring implements the KEYCTL_JOIN_SESSION_KEYRING command.
  1478  // See the full documentation at:
  1479  // http://man7.org/linux/man-pages/man3/keyctl_join_session_keyring.3.html
  1480  func KeyctlJoinSessionKeyring(name string) (ringid int, err error) {
  1481  	return keyctlJoin(KEYCTL_JOIN_SESSION_KEYRING, name)
  1482  }
  1483  
  1484  //sys	keyctlSearch(cmd int, arg2 int, arg3 string, arg4 string, arg5 int) (ret int, err error) = SYS_KEYCTL
  1485  
  1486  // KeyctlSearch implements the KEYCTL_SEARCH command.
  1487  // See the full documentation at:
  1488  // http://man7.org/linux/man-pages/man3/keyctl_search.3.html
  1489  func KeyctlSearch(ringid int, keyType, description string, destRingid int) (id int, err error) {
  1490  	return keyctlSearch(KEYCTL_SEARCH, ringid, keyType, description, destRingid)
  1491  }
  1492  
  1493  //sys	keyctlIOV(cmd int, arg2 int, payload []Iovec, arg5 int) (err error) = SYS_KEYCTL
  1494  
  1495  // KeyctlInstantiateIOV implements the KEYCTL_INSTANTIATE_IOV command. This
  1496  // command is similar to KEYCTL_INSTANTIATE, except that the payload is a slice
  1497  // of Iovec (each of which represents a buffer) instead of a single buffer.
  1498  // See the full documentation at:
  1499  // http://man7.org/linux/man-pages/man3/keyctl_instantiate_iov.3.html
  1500  func KeyctlInstantiateIOV(id int, payload []Iovec, ringid int) error {
  1501  	return keyctlIOV(KEYCTL_INSTANTIATE_IOV, id, payload, ringid)
  1502  }
  1503  
  1504  //sys	keyctlDH(cmd int, arg2 *KeyctlDHParams, buf []byte) (ret int, err error) = SYS_KEYCTL
  1505  
  1506  // KeyctlDHCompute implements the KEYCTL_DH_COMPUTE command. This command
  1507  // computes a Diffie-Hellman shared secret based on the provide params. The
  1508  // secret is written to the provided buffer and the returned size is the number
  1509  // of bytes written (returning an error if there is insufficient space in the
  1510  // buffer). If a nil buffer is passed in, this function returns the minimum
  1511  // buffer length needed to store the appropriate data. Note that this differs
  1512  // from KEYCTL_READ's behavior which always returns the requested payload size.
  1513  // See the full documentation at:
  1514  // http://man7.org/linux/man-pages/man3/keyctl_dh_compute.3.html
  1515  func KeyctlDHCompute(params *KeyctlDHParams, buffer []byte) (size int, err error) {
  1516  	return keyctlDH(KEYCTL_DH_COMPUTE, params, buffer)
  1517  }
  1518  
  1519  // KeyctlRestrictKeyring implements the KEYCTL_RESTRICT_KEYRING command. This
  1520  // command limits the set of keys that can be linked to the keyring, regardless
  1521  // of keyring permissions. The command requires the "setattr" permission.
  1522  //
  1523  // When called with an empty keyType the command locks the keyring, preventing
  1524  // any further keys from being linked to the keyring.
  1525  //
  1526  // The "asymmetric" keyType defines restrictions requiring key payloads to be
  1527  // DER encoded X.509 certificates signed by keys in another keyring. Restrictions
  1528  // for "asymmetric" include "builtin_trusted", "builtin_and_secondary_trusted",
  1529  // "key_or_keyring:<key>", and "key_or_keyring:<key>:chain".
  1530  //
  1531  // As of Linux 4.12, only the "asymmetric" keyType defines type-specific
  1532  // restrictions.
  1533  //
  1534  // See the full documentation at:
  1535  // http://man7.org/linux/man-pages/man3/keyctl_restrict_keyring.3.html
  1536  // http://man7.org/linux/man-pages/man2/keyctl.2.html
  1537  func KeyctlRestrictKeyring(ringid int, keyType string, restriction string) error {
  1538  	if keyType == "" {
  1539  		return keyctlRestrictKeyring(KEYCTL_RESTRICT_KEYRING, ringid)
  1540  	}
  1541  	return keyctlRestrictKeyringByType(KEYCTL_RESTRICT_KEYRING, ringid, keyType, restriction)
  1542  }
  1543  
  1544  //sys	keyctlRestrictKeyringByType(cmd int, arg2 int, keyType string, restriction string) (err error) = SYS_KEYCTL
  1545  //sys	keyctlRestrictKeyring(cmd int, arg2 int) (err error) = SYS_KEYCTL
  1546  
  1547  func recvmsgRaw(fd int, iov []Iovec, oob []byte, flags int, rsa *RawSockaddrAny) (n, oobn int, recvflags int, err error) {
  1548  	var msg Msghdr
  1549  	msg.Name = (*byte)(unsafe.Pointer(rsa))
  1550  	msg.Namelen = uint32(SizeofSockaddrAny)
  1551  	var dummy byte
  1552  	if len(oob) > 0 {
  1553  		if emptyIovecs(iov) {
  1554  			var sockType int
  1555  			sockType, err = GetsockoptInt(fd, SOL_SOCKET, SO_TYPE)
  1556  			if err != nil {
  1557  				return
  1558  			}
  1559  			// receive at least one normal byte
  1560  			if sockType != SOCK_DGRAM {
  1561  				var iova [1]Iovec
  1562  				iova[0].Base = &dummy
  1563  				iova[0].SetLen(1)
  1564  				iov = iova[:]
  1565  			}
  1566  		}
  1567  		msg.Control = &oob[0]
  1568  		msg.SetControllen(len(oob))
  1569  	}
  1570  	if len(iov) > 0 {
  1571  		msg.Iov = &iov[0]
  1572  		msg.SetIovlen(len(iov))
  1573  	}
  1574  	if n, err = recvmsg(fd, &msg, flags); err != nil {
  1575  		return
  1576  	}
  1577  	oobn = int(msg.Controllen)
  1578  	recvflags = int(msg.Flags)
  1579  	return
  1580  }
  1581  
  1582  func sendmsgN(fd int, iov []Iovec, oob []byte, ptr unsafe.Pointer, salen _Socklen, flags int) (n int, err error) {
  1583  	var msg Msghdr
  1584  	msg.Name = (*byte)(ptr)
  1585  	msg.Namelen = uint32(salen)
  1586  	var dummy byte
  1587  	var empty bool
  1588  	if len(oob) > 0 {
  1589  		empty = emptyIovecs(iov)
  1590  		if empty {
  1591  			var sockType int
  1592  			sockType, err = GetsockoptInt(fd, SOL_SOCKET, SO_TYPE)
  1593  			if err != nil {
  1594  				return 0, err
  1595  			}
  1596  			// send at least one normal byte
  1597  			if sockType != SOCK_DGRAM {
  1598  				var iova [1]Iovec
  1599  				iova[0].Base = &dummy
  1600  				iova[0].SetLen(1)
  1601  				iov = iova[:]
  1602  			}
  1603  		}
  1604  		msg.Control = &oob[0]
  1605  		msg.SetControllen(len(oob))
  1606  	}
  1607  	if len(iov) > 0 {
  1608  		msg.Iov = &iov[0]
  1609  		msg.SetIovlen(len(iov))
  1610  	}
  1611  	if n, err = sendmsg(fd, &msg, flags); err != nil {
  1612  		return 0, err
  1613  	}
  1614  	if len(oob) > 0 && empty {
  1615  		n = 0
  1616  	}
  1617  	return n, nil
  1618  }
  1619  
  1620  // BindToDevice binds the socket associated with fd to device.
  1621  func BindToDevice(fd int, device string) (err error) {
  1622  	return SetsockoptString(fd, SOL_SOCKET, SO_BINDTODEVICE, device)
  1623  }
  1624  
  1625  //sys	ptrace(request int, pid int, addr uintptr, data uintptr) (err error)
  1626  //sys	ptracePtr(request int, pid int, addr uintptr, data unsafe.Pointer) (err error) = SYS_PTRACE
  1627  
  1628  func ptracePeek(req int, pid int, addr uintptr, out []byte) (count int, err error) {
  1629  	// The peek requests are machine-size oriented, so we wrap it
  1630  	// to retrieve arbitrary-length data.
  1631  
  1632  	// The ptrace syscall differs from glibc's ptrace.
  1633  	// Peeks returns the word in *data, not as the return value.
  1634  
  1635  	var buf [SizeofPtr]byte
  1636  
  1637  	// Leading edge. PEEKTEXT/PEEKDATA don't require aligned
  1638  	// access (PEEKUSER warns that it might), but if we don't
  1639  	// align our reads, we might straddle an unmapped page
  1640  	// boundary and not get the bytes leading up to the page
  1641  	// boundary.
  1642  	n := 0
  1643  	if addr%SizeofPtr != 0 {
  1644  		err = ptracePtr(req, pid, addr-addr%SizeofPtr, unsafe.Pointer(&buf[0]))
  1645  		if err != nil {
  1646  			return 0, err
  1647  		}
  1648  		n += copy(out, buf[addr%SizeofPtr:])
  1649  		out = out[n:]
  1650  	}
  1651  
  1652  	// Remainder.
  1653  	for len(out) > 0 {
  1654  		// We use an internal buffer to guarantee alignment.
  1655  		// It's not documented if this is necessary, but we're paranoid.
  1656  		err = ptracePtr(req, pid, addr+uintptr(n), unsafe.Pointer(&buf[0]))
  1657  		if err != nil {
  1658  			return n, err
  1659  		}
  1660  		copied := copy(out, buf[0:])
  1661  		n += copied
  1662  		out = out[copied:]
  1663  	}
  1664  
  1665  	return n, nil
  1666  }
  1667  
  1668  func PtracePeekText(pid int, addr uintptr, out []byte) (count int, err error) {
  1669  	return ptracePeek(PTRACE_PEEKTEXT, pid, addr, out)
  1670  }
  1671  
  1672  func PtracePeekData(pid int, addr uintptr, out []byte) (count int, err error) {
  1673  	return ptracePeek(PTRACE_PEEKDATA, pid, addr, out)
  1674  }
  1675  
  1676  func PtracePeekUser(pid int, addr uintptr, out []byte) (count int, err error) {
  1677  	return ptracePeek(PTRACE_PEEKUSR, pid, addr, out)
  1678  }
  1679  
  1680  func ptracePoke(pokeReq int, peekReq int, pid int, addr uintptr, data []byte) (count int, err error) {
  1681  	// As for ptracePeek, we need to align our accesses to deal
  1682  	// with the possibility of straddling an invalid page.
  1683  
  1684  	// Leading edge.
  1685  	n := 0
  1686  	if addr%SizeofPtr != 0 {
  1687  		var buf [SizeofPtr]byte
  1688  		err = ptracePtr(peekReq, pid, addr-addr%SizeofPtr, unsafe.Pointer(&buf[0]))
  1689  		if err != nil {
  1690  			return 0, err
  1691  		}
  1692  		n += copy(buf[addr%SizeofPtr:], data)
  1693  		word := *((*uintptr)(unsafe.Pointer(&buf[0])))
  1694  		err = ptrace(pokeReq, pid, addr-addr%SizeofPtr, word)
  1695  		if err != nil {
  1696  			return 0, err
  1697  		}
  1698  		data = data[n:]
  1699  	}
  1700  
  1701  	// Interior.
  1702  	for len(data) > SizeofPtr {
  1703  		word := *((*uintptr)(unsafe.Pointer(&data[0])))
  1704  		err = ptrace(pokeReq, pid, addr+uintptr(n), word)
  1705  		if err != nil {
  1706  			return n, err
  1707  		}
  1708  		n += SizeofPtr
  1709  		data = data[SizeofPtr:]
  1710  	}
  1711  
  1712  	// Trailing edge.
  1713  	if len(data) > 0 {
  1714  		var buf [SizeofPtr]byte
  1715  		err = ptracePtr(peekReq, pid, addr+uintptr(n), unsafe.Pointer(&buf[0]))
  1716  		if err != nil {
  1717  			return n, err
  1718  		}
  1719  		copy(buf[0:], data)
  1720  		word := *((*uintptr)(unsafe.Pointer(&buf[0])))
  1721  		err = ptrace(pokeReq, pid, addr+uintptr(n), word)
  1722  		if err != nil {
  1723  			return n, err
  1724  		}
  1725  		n += len(data)
  1726  	}
  1727  
  1728  	return n, nil
  1729  }
  1730  
  1731  func PtracePokeText(pid int, addr uintptr, data []byte) (count int, err error) {
  1732  	return ptracePoke(PTRACE_POKETEXT, PTRACE_PEEKTEXT, pid, addr, data)
  1733  }
  1734  
  1735  func PtracePokeData(pid int, addr uintptr, data []byte) (count int, err error) {
  1736  	return ptracePoke(PTRACE_POKEDATA, PTRACE_PEEKDATA, pid, addr, data)
  1737  }
  1738  
  1739  func PtracePokeUser(pid int, addr uintptr, data []byte) (count int, err error) {
  1740  	return ptracePoke(PTRACE_POKEUSR, PTRACE_PEEKUSR, pid, addr, data)
  1741  }
  1742  
  1743  // elfNT_PRSTATUS is a copy of the debug/elf.NT_PRSTATUS constant so
  1744  // x/sys/unix doesn't need to depend on debug/elf and thus
  1745  // compress/zlib, debug/dwarf, and other packages.
  1746  const elfNT_PRSTATUS = 1
  1747  
  1748  func PtraceGetRegs(pid int, regsout *PtraceRegs) (err error) {
  1749  	var iov Iovec
  1750  	iov.Base = (*byte)(unsafe.Pointer(regsout))
  1751  	iov.SetLen(int(unsafe.Sizeof(*regsout)))
  1752  	return ptracePtr(PTRACE_GETREGSET, pid, uintptr(elfNT_PRSTATUS), unsafe.Pointer(&iov))
  1753  }
  1754  
  1755  func PtraceSetRegs(pid int, regs *PtraceRegs) (err error) {
  1756  	var iov Iovec
  1757  	iov.Base = (*byte)(unsafe.Pointer(regs))
  1758  	iov.SetLen(int(unsafe.Sizeof(*regs)))
  1759  	return ptracePtr(PTRACE_SETREGSET, pid, uintptr(elfNT_PRSTATUS), unsafe.Pointer(&iov))
  1760  }
  1761  
  1762  func PtraceSetOptions(pid int, options int) (err error) {
  1763  	return ptrace(PTRACE_SETOPTIONS, pid, 0, uintptr(options))
  1764  }
  1765  
  1766  func PtraceGetEventMsg(pid int) (msg uint, err error) {
  1767  	var data _C_long
  1768  	err = ptracePtr(PTRACE_GETEVENTMSG, pid, 0, unsafe.Pointer(&data))
  1769  	msg = uint(data)
  1770  	return
  1771  }
  1772  
  1773  func PtraceCont(pid int, signal int) (err error) {
  1774  	return ptrace(PTRACE_CONT, pid, 0, uintptr(signal))
  1775  }
  1776  
  1777  func PtraceSyscall(pid int, signal int) (err error) {
  1778  	return ptrace(PTRACE_SYSCALL, pid, 0, uintptr(signal))
  1779  }
  1780  
  1781  func PtraceSingleStep(pid int) (err error) { return ptrace(PTRACE_SINGLESTEP, pid, 0, 0) }
  1782  
  1783  func PtraceInterrupt(pid int) (err error) { return ptrace(PTRACE_INTERRUPT, pid, 0, 0) }
  1784  
  1785  func PtraceAttach(pid int) (err error) { return ptrace(PTRACE_ATTACH, pid, 0, 0) }
  1786  
  1787  func PtraceSeize(pid int) (err error) { return ptrace(PTRACE_SEIZE, pid, 0, 0) }
  1788  
  1789  func PtraceDetach(pid int) (err error) { return ptrace(PTRACE_DETACH, pid, 0, 0) }
  1790  
  1791  //sys	reboot(magic1 uint, magic2 uint, cmd int, arg string) (err error)
  1792  
  1793  func Reboot(cmd int) (err error) {
  1794  	return reboot(LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2, cmd, "")
  1795  }
  1796  
  1797  func direntIno(buf []byte) (uint64, bool) {
  1798  	return readInt(buf, unsafe.Offsetof(Dirent{}.Ino), unsafe.Sizeof(Dirent{}.Ino))
  1799  }
  1800  
  1801  func direntReclen(buf []byte) (uint64, bool) {
  1802  	return readInt(buf, unsafe.Offsetof(Dirent{}.Reclen), unsafe.Sizeof(Dirent{}.Reclen))
  1803  }
  1804  
  1805  func direntNamlen(buf []byte) (uint64, bool) {
  1806  	reclen, ok := direntReclen(buf)
  1807  	if !ok {
  1808  		return 0, false
  1809  	}
  1810  	return reclen - uint64(unsafe.Offsetof(Dirent{}.Name)), true
  1811  }
  1812  
  1813  //sys	mount(source string, target string, fstype string, flags uintptr, data *byte) (err error)
  1814  
  1815  func Mount(source string, target string, fstype string, flags uintptr, data string) (err error) {
  1816  	// Certain file systems get rather angry and EINVAL if you give
  1817  	// them an empty string of data, rather than NULL.
  1818  	if data == "" {
  1819  		return mount(source, target, fstype, flags, nil)
  1820  	}
  1821  	datap, err := BytePtrFromString(data)
  1822  	if err != nil {
  1823  		return err
  1824  	}
  1825  	return mount(source, target, fstype, flags, datap)
  1826  }
  1827  
  1828  //sys	mountSetattr(dirfd int, pathname string, flags uint, attr *MountAttr, size uintptr) (err error) = SYS_MOUNT_SETATTR
  1829  
  1830  // MountSetattr is a wrapper for mount_setattr(2).
  1831  // https://man7.org/linux/man-pages/man2/mount_setattr.2.html
  1832  //
  1833  // Requires kernel >= 5.12.
  1834  func MountSetattr(dirfd int, pathname string, flags uint, attr *MountAttr) error {
  1835  	return mountSetattr(dirfd, pathname, flags, attr, unsafe.Sizeof(*attr))
  1836  }
  1837  
  1838  func Sendfile(outfd int, infd int, offset *int64, count int) (written int, err error) {
  1839  	if raceenabled {
  1840  		raceReleaseMerge(unsafe.Pointer(&ioSync))
  1841  	}
  1842  	return sendfile(outfd, infd, offset, count)
  1843  }
  1844  
  1845  // Sendto
  1846  // Recvfrom
  1847  // Socketpair
  1848  
  1849  /*
  1850   * Direct access
  1851   */
  1852  //sys	Acct(path string) (err error)
  1853  //sys	AddKey(keyType string, description string, payload []byte, ringid int) (id int, err error)
  1854  //sys	Adjtimex(buf *Timex) (state int, err error)
  1855  //sysnb	Capget(hdr *CapUserHeader, data *CapUserData) (err error)
  1856  //sysnb	Capset(hdr *CapUserHeader, data *CapUserData) (err error)
  1857  //sys	Chdir(path string) (err error)
  1858  //sys	Chroot(path string) (err error)
  1859  //sys	ClockAdjtime(clockid int32, buf *Timex) (state int, err error)
  1860  //sys	ClockGetres(clockid int32, res *Timespec) (err error)
  1861  //sys	ClockGettime(clockid int32, time *Timespec) (err error)
  1862  //sys	ClockSettime(clockid int32, time *Timespec) (err error)
  1863  //sys	ClockNanosleep(clockid int32, flags int, request *Timespec, remain *Timespec) (err error)
  1864  //sys	Close(fd int) (err error)
  1865  //sys	CloseRange(first uint, last uint, flags uint) (err error)
  1866  //sys	CopyFileRange(rfd int, roff *int64, wfd int, woff *int64, len int, flags int) (n int, err error)
  1867  //sys	DeleteModule(name string, flags int) (err error)
  1868  //sys	Dup(oldfd int) (fd int, err error)
  1869  
  1870  func Dup2(oldfd, newfd int) error {
  1871  	return Dup3(oldfd, newfd, 0)
  1872  }
  1873  
  1874  //sys	Dup3(oldfd int, newfd int, flags int) (err error)
  1875  //sysnb	EpollCreate1(flag int) (fd int, err error)
  1876  //sysnb	EpollCtl(epfd int, op int, fd int, event *EpollEvent) (err error)
  1877  //sys	Eventfd(initval uint, flags int) (fd int, err error) = SYS_EVENTFD2
  1878  //sys	Exit(code int) = SYS_EXIT_GROUP
  1879  //sys	Fallocate(fd int, mode uint32, off int64, len int64) (err error)
  1880  //sys	Fchdir(fd int) (err error)
  1881  //sys	Fchmod(fd int, mode uint32) (err error)
  1882  //sys	Fchownat(dirfd int, path string, uid int, gid int, flags int) (err error)
  1883  //sys	Fdatasync(fd int) (err error)
  1884  //sys	Fgetxattr(fd int, attr string, dest []byte) (sz int, err error)
  1885  //sys	FinitModule(fd int, params string, flags int) (err error)
  1886  //sys	Flistxattr(fd int, dest []byte) (sz int, err error)
  1887  //sys	Flock(fd int, how int) (err error)
  1888  //sys	Fremovexattr(fd int, attr string) (err error)
  1889  //sys	Fsetxattr(fd int, attr string, dest []byte, flags int) (err error)
  1890  //sys	Fsync(fd int) (err error)
  1891  //sys	Fsmount(fd int, flags int, mountAttrs int) (fsfd int, err error)
  1892  //sys	Fsopen(fsName string, flags int) (fd int, err error)
  1893  //sys	Fspick(dirfd int, pathName string, flags int) (fd int, err error)
  1894  
  1895  //sys	fsconfig(fd int, cmd uint, key *byte, value *byte, aux int) (err error)
  1896  
  1897  func fsconfigCommon(fd int, cmd uint, key string, value *byte, aux int) (err error) {
  1898  	var keyp *byte
  1899  	if keyp, err = BytePtrFromString(key); err != nil {
  1900  		return
  1901  	}
  1902  	return fsconfig(fd, cmd, keyp, value, aux)
  1903  }
  1904  
  1905  // FsconfigSetFlag is equivalent to fsconfig(2) called
  1906  // with cmd == FSCONFIG_SET_FLAG.
  1907  //
  1908  // fd is the filesystem context to act upon.
  1909  // key the parameter key to set.
  1910  func FsconfigSetFlag(fd int, key string) (err error) {
  1911  	return fsconfigCommon(fd, FSCONFIG_SET_FLAG, key, nil, 0)
  1912  }
  1913  
  1914  // FsconfigSetString is equivalent to fsconfig(2) called
  1915  // with cmd == FSCONFIG_SET_STRING.
  1916  //
  1917  // fd is the filesystem context to act upon.
  1918  // key the parameter key to set.
  1919  // value is the parameter value to set.
  1920  func FsconfigSetString(fd int, key string, value string) (err error) {
  1921  	var valuep *byte
  1922  	if valuep, err = BytePtrFromString(value); err != nil {
  1923  		return
  1924  	}
  1925  	return fsconfigCommon(fd, FSCONFIG_SET_STRING, key, valuep, 0)
  1926  }
  1927  
  1928  // FsconfigSetBinary is equivalent to fsconfig(2) called
  1929  // with cmd == FSCONFIG_SET_BINARY.
  1930  //
  1931  // fd is the filesystem context to act upon.
  1932  // key the parameter key to set.
  1933  // value is the parameter value to set.
  1934  func FsconfigSetBinary(fd int, key string, value []byte) (err error) {
  1935  	if len(value) == 0 {
  1936  		return EINVAL
  1937  	}
  1938  	return fsconfigCommon(fd, FSCONFIG_SET_BINARY, key, &value[0], len(value))
  1939  }
  1940  
  1941  // FsconfigSetPath is equivalent to fsconfig(2) called
  1942  // with cmd == FSCONFIG_SET_PATH.
  1943  //
  1944  // fd is the filesystem context to act upon.
  1945  // key the parameter key to set.
  1946  // path is a non-empty path for specified key.
  1947  // atfd is a file descriptor at which to start lookup from or AT_FDCWD.
  1948  func FsconfigSetPath(fd int, key string, path string, atfd int) (err error) {
  1949  	var valuep *byte
  1950  	if valuep, err = BytePtrFromString(path); err != nil {
  1951  		return
  1952  	}
  1953  	return fsconfigCommon(fd, FSCONFIG_SET_PATH, key, valuep, atfd)
  1954  }
  1955  
  1956  // FsconfigSetPathEmpty is equivalent to fsconfig(2) called
  1957  // with cmd == FSCONFIG_SET_PATH_EMPTY. The same as
  1958  // FconfigSetPath but with AT_PATH_EMPTY implied.
  1959  func FsconfigSetPathEmpty(fd int, key string, path string, atfd int) (err error) {
  1960  	var valuep *byte
  1961  	if valuep, err = BytePtrFromString(path); err != nil {
  1962  		return
  1963  	}
  1964  	return fsconfigCommon(fd, FSCONFIG_SET_PATH_EMPTY, key, valuep, atfd)
  1965  }
  1966  
  1967  // FsconfigSetFd is equivalent to fsconfig(2) called
  1968  // with cmd == FSCONFIG_SET_FD.
  1969  //
  1970  // fd is the filesystem context to act upon.
  1971  // key the parameter key to set.
  1972  // value is a file descriptor to be assigned to specified key.
  1973  func FsconfigSetFd(fd int, key string, value int) (err error) {
  1974  	return fsconfigCommon(fd, FSCONFIG_SET_FD, key, nil, value)
  1975  }
  1976  
  1977  // FsconfigCreate is equivalent to fsconfig(2) called
  1978  // with cmd == FSCONFIG_CMD_CREATE.
  1979  //
  1980  // fd is the filesystem context to act upon.
  1981  func FsconfigCreate(fd int) (err error) {
  1982  	return fsconfig(fd, FSCONFIG_CMD_CREATE, nil, nil, 0)
  1983  }
  1984  
  1985  // FsconfigReconfigure is equivalent to fsconfig(2) called
  1986  // with cmd == FSCONFIG_CMD_RECONFIGURE.
  1987  //
  1988  // fd is the filesystem context to act upon.
  1989  func FsconfigReconfigure(fd int) (err error) {
  1990  	return fsconfig(fd, FSCONFIG_CMD_RECONFIGURE, nil, nil, 0)
  1991  }
  1992  
  1993  //sys	Getdents(fd int, buf []byte) (n int, err error) = SYS_GETDENTS64
  1994  //sysnb	Getpgid(pid int) (pgid int, err error)
  1995  
  1996  func Getpgrp() (pid int) {
  1997  	pid, _ = Getpgid(0)
  1998  	return
  1999  }
  2000  
  2001  //sysnb	Getpid() (pid int)
  2002  //sysnb	Getppid() (ppid int)
  2003  //sys	Getpriority(which int, who int) (prio int, err error)
  2004  
  2005  func Getrandom(buf []byte, flags int) (n int, err error) {
  2006  	vdsoRet, supported := vgetrandom(buf, uint32(flags))
  2007  	if supported {
  2008  		if vdsoRet < 0 {
  2009  			return 0, errnoErr(syscall.Errno(-vdsoRet))
  2010  		}
  2011  		return vdsoRet, nil
  2012  	}
  2013  	var p *byte
  2014  	if len(buf) > 0 {
  2015  		p = &buf[0]
  2016  	}
  2017  	r, _, e := Syscall(SYS_GETRANDOM, uintptr(unsafe.Pointer(p)), uintptr(len(buf)), uintptr(flags))
  2018  	if e != 0 {
  2019  		return 0, errnoErr(e)
  2020  	}
  2021  	return int(r), nil
  2022  }
  2023  
  2024  //sysnb	Getrusage(who int, rusage *Rusage) (err error)
  2025  //sysnb	Getsid(pid int) (sid int, err error)
  2026  //sysnb	Gettid() (tid int)
  2027  //sys	Getxattr(path string, attr string, dest []byte) (sz int, err error)
  2028  //sys	InitModule(moduleImage []byte, params string) (err error)
  2029  //sys	InotifyAddWatch(fd int, pathname string, mask uint32) (watchdesc int, err error)
  2030  //sysnb	InotifyInit1(flags int) (fd int, err error)
  2031  //sysnb	InotifyRmWatch(fd int, watchdesc uint32) (success int, err error)
  2032  //sysnb	Kill(pid int, sig syscall.Signal) (err error)
  2033  //sys	Klogctl(typ int, buf []byte) (n int, err error) = SYS_SYSLOG
  2034  //sys	Lgetxattr(path string, attr string, dest []byte) (sz int, err error)
  2035  //sys	Listxattr(path string, dest []byte) (sz int, err error)
  2036  //sys	Llistxattr(path string, dest []byte) (sz int, err error)
  2037  //sys	Lremovexattr(path string, attr string) (err error)
  2038  //sys	Lsetxattr(path string, attr string, data []byte, flags int) (err error)
  2039  //sys	MemfdCreate(name string, flags int) (fd int, err error)
  2040  //sys	Mkdirat(dirfd int, path string, mode uint32) (err error)
  2041  //sys	Mknodat(dirfd int, path string, mode uint32, dev int) (err error)
  2042  //sys	MoveMount(fromDirfd int, fromPathName string, toDirfd int, toPathName string, flags int) (err error)
  2043  //sys	Nanosleep(time *Timespec, leftover *Timespec) (err error)
  2044  //sys	OpenTree(dfd int, fileName string, flags uint) (r int, err error)
  2045  //sys	PerfEventOpen(attr *PerfEventAttr, pid int, cpu int, groupFd int, flags int) (fd int, err error)
  2046  //sys	PivotRoot(newroot string, putold string) (err error) = SYS_PIVOT_ROOT
  2047  //sys	Prctl(option int, arg2 uintptr, arg3 uintptr, arg4 uintptr, arg5 uintptr) (err error)
  2048  //sys	pselect6(nfd int, r *FdSet, w *FdSet, e *FdSet, timeout *Timespec, sigmask *sigset_argpack) (n int, err error)
  2049  //sys	read(fd int, p []byte) (n int, err error)
  2050  //sys	Removexattr(path string, attr string) (err error)
  2051  //sys	Renameat2(olddirfd int, oldpath string, newdirfd int, newpath string, flags uint) (err error)
  2052  //sys	RequestKey(keyType string, description string, callback string, destRingid int) (id int, err error)
  2053  //sys	Setdomainname(p []byte) (err error)
  2054  //sys	Sethostname(p []byte) (err error)
  2055  //sysnb	Setpgid(pid int, pgid int) (err error)
  2056  //sysnb	Setsid() (pid int, err error)
  2057  //sysnb	Settimeofday(tv *Timeval) (err error)
  2058  //sys	Setns(fd int, nstype int) (err error)
  2059  
  2060  //go:linkname syscall_prlimit syscall.prlimit
  2061  func syscall_prlimit(pid, resource int, newlimit, old *syscall.Rlimit) error
  2062  
  2063  func Prlimit(pid, resource int, newlimit, old *Rlimit) error {
  2064  	// Just call the syscall version, because as of Go 1.21
  2065  	// it will affect starting a new process.
  2066  	return syscall_prlimit(pid, resource, (*syscall.Rlimit)(newlimit), (*syscall.Rlimit)(old))
  2067  }
  2068  
  2069  // PrctlRetInt performs a prctl operation specified by option and further
  2070  // optional arguments arg2 through arg5 depending on option. It returns a
  2071  // non-negative integer that is returned by the prctl syscall.
  2072  func PrctlRetInt(option int, arg2 uintptr, arg3 uintptr, arg4 uintptr, arg5 uintptr) (int, error) {
  2073  	ret, _, err := Syscall6(SYS_PRCTL, uintptr(option), uintptr(arg2), uintptr(arg3), uintptr(arg4), uintptr(arg5), 0)
  2074  	if err != 0 {
  2075  		return 0, err
  2076  	}
  2077  	return int(ret), nil
  2078  }
  2079  
  2080  func Setuid(uid int) (err error) {
  2081  	return syscall.Setuid(uid)
  2082  }
  2083  
  2084  func Setgid(gid int) (err error) {
  2085  	return syscall.Setgid(gid)
  2086  }
  2087  
  2088  func Setreuid(ruid, euid int) (err error) {
  2089  	return syscall.Setreuid(ruid, euid)
  2090  }
  2091  
  2092  func Setregid(rgid, egid int) (err error) {
  2093  	return syscall.Setregid(rgid, egid)
  2094  }
  2095  
  2096  func Setresuid(ruid, euid, suid int) (err error) {
  2097  	return syscall.Setresuid(ruid, euid, suid)
  2098  }
  2099  
  2100  func Setresgid(rgid, egid, sgid int) (err error) {
  2101  	return syscall.Setresgid(rgid, egid, sgid)
  2102  }
  2103  
  2104  // SetfsgidRetGid sets fsgid for current thread and returns previous fsgid set.
  2105  // setfsgid(2) will return a non-nil error only if its caller lacks CAP_SETUID capability.
  2106  // If the call fails due to other reasons, current fsgid will be returned.
  2107  func SetfsgidRetGid(gid int) (int, error) {
  2108  	return setfsgid(gid)
  2109  }
  2110  
  2111  // SetfsuidRetUid sets fsuid for current thread and returns previous fsuid set.
  2112  // setfsgid(2) will return a non-nil error only if its caller lacks CAP_SETUID capability
  2113  // If the call fails due to other reasons, current fsuid will be returned.
  2114  func SetfsuidRetUid(uid int) (int, error) {
  2115  	return setfsuid(uid)
  2116  }
  2117  
  2118  func Setfsgid(gid int) error {
  2119  	_, err := setfsgid(gid)
  2120  	return err
  2121  }
  2122  
  2123  func Setfsuid(uid int) error {
  2124  	_, err := setfsuid(uid)
  2125  	return err
  2126  }
  2127  
  2128  func Signalfd(fd int, sigmask *Sigset_t, flags int) (newfd int, err error) {
  2129  	return signalfd(fd, sigmask, _C__NSIG/8, flags)
  2130  }
  2131  
  2132  //sys	Setpriority(which int, who int, prio int) (err error)
  2133  //sys	Setxattr(path string, attr string, data []byte, flags int) (err error)
  2134  //sys	signalfd(fd int, sigmask *Sigset_t, maskSize uintptr, flags int) (newfd int, err error) = SYS_SIGNALFD4
  2135  //sys	Statx(dirfd int, path string, flags int, mask int, stat *Statx_t) (err error)
  2136  //sys	Sync()
  2137  //sys	Syncfs(fd int) (err error)
  2138  //sysnb	Sysinfo(info *Sysinfo_t) (err error)
  2139  //sys	Tee(rfd int, wfd int, len int, flags int) (n int64, err error)
  2140  //sysnb	TimerfdCreate(clockid int, flags int) (fd int, err error)
  2141  //sysnb	TimerfdGettime(fd int, currValue *ItimerSpec) (err error)
  2142  //sysnb	TimerfdSettime(fd int, flags int, newValue *ItimerSpec, oldValue *ItimerSpec) (err error)
  2143  //sysnb	Tgkill(tgid int, tid int, sig syscall.Signal) (err error)
  2144  //sysnb	Times(tms *Tms) (ticks uintptr, err error)
  2145  //sysnb	Umask(mask int) (oldmask int)
  2146  //sysnb	Uname(buf *Utsname) (err error)
  2147  //sys	Unmount(target string, flags int) (err error) = SYS_UMOUNT2
  2148  //sys	Unshare(flags int) (err error)
  2149  //sys	write(fd int, p []byte) (n int, err error)
  2150  //sys	exitThread(code int) (err error) = SYS_EXIT
  2151  //sys	readv(fd int, iovs []Iovec) (n int, err error) = SYS_READV
  2152  //sys	writev(fd int, iovs []Iovec) (n int, err error) = SYS_WRITEV
  2153  //sys	preadv(fd int, iovs []Iovec, offs_l uintptr, offs_h uintptr) (n int, err error) = SYS_PREADV
  2154  //sys	pwritev(fd int, iovs []Iovec, offs_l uintptr, offs_h uintptr) (n int, err error) = SYS_PWRITEV
  2155  //sys	preadv2(fd int, iovs []Iovec, offs_l uintptr, offs_h uintptr, flags int) (n int, err error) = SYS_PREADV2
  2156  //sys	pwritev2(fd int, iovs []Iovec, offs_l uintptr, offs_h uintptr, flags int) (n int, err error) = SYS_PWRITEV2
  2157  
  2158  // minIovec is the size of the small initial allocation used by
  2159  // Readv, Writev, etc.
  2160  //
  2161  // This small allocation gets stack allocated, which lets the
  2162  // common use case of len(iovs) <= minIovs avoid more expensive
  2163  // heap allocations.
  2164  const minIovec = 8
  2165  
  2166  // appendBytes converts bs to Iovecs and appends them to vecs.
  2167  func appendBytes(vecs []Iovec, bs [][]byte) []Iovec {
  2168  	for _, b := range bs {
  2169  		var v Iovec
  2170  		v.SetLen(len(b))
  2171  		if len(b) > 0 {
  2172  			v.Base = &b[0]
  2173  		} else {
  2174  			v.Base = (*byte)(unsafe.Pointer(&_zero))
  2175  		}
  2176  		vecs = append(vecs, v)
  2177  	}
  2178  	return vecs
  2179  }
  2180  
  2181  // offs2lohi splits offs into its low and high order bits.
  2182  func offs2lohi(offs int64) (lo, hi uintptr) {
  2183  	const longBits = SizeofLong * 8
  2184  	return uintptr(offs), uintptr(uint64(offs) >> (longBits - 1) >> 1) // two shifts to avoid false positive in vet
  2185  }
  2186  
  2187  func Readv(fd int, iovs [][]byte) (n int, err error) {
  2188  	iovecs := make([]Iovec, 0, minIovec)
  2189  	iovecs = appendBytes(iovecs, iovs)
  2190  	n, err = readv(fd, iovecs)
  2191  	readvRacedetect(iovecs, n, err)
  2192  	return n, err
  2193  }
  2194  
  2195  func Preadv(fd int, iovs [][]byte, offset int64) (n int, err error) {
  2196  	iovecs := make([]Iovec, 0, minIovec)
  2197  	iovecs = appendBytes(iovecs, iovs)
  2198  	lo, hi := offs2lohi(offset)
  2199  	n, err = preadv(fd, iovecs, lo, hi)
  2200  	readvRacedetect(iovecs, n, err)
  2201  	return n, err
  2202  }
  2203  
  2204  func Preadv2(fd int, iovs [][]byte, offset int64, flags int) (n int, err error) {
  2205  	iovecs := make([]Iovec, 0, minIovec)
  2206  	iovecs = appendBytes(iovecs, iovs)
  2207  	lo, hi := offs2lohi(offset)
  2208  	n, err = preadv2(fd, iovecs, lo, hi, flags)
  2209  	readvRacedetect(iovecs, n, err)
  2210  	return n, err
  2211  }
  2212  
  2213  func readvRacedetect(iovecs []Iovec, n int, err error) {
  2214  	if !raceenabled {
  2215  		return
  2216  	}
  2217  	for i := 0; n > 0 && i < len(iovecs); i++ {
  2218  		m := min(int(iovecs[i].Len), n)
  2219  		n -= m
  2220  		if m > 0 {
  2221  			raceWriteRange(unsafe.Pointer(iovecs[i].Base), m)
  2222  		}
  2223  	}
  2224  	if err == nil {
  2225  		raceAcquire(unsafe.Pointer(&ioSync))
  2226  	}
  2227  }
  2228  
  2229  func Writev(fd int, iovs [][]byte) (n int, err error) {
  2230  	iovecs := make([]Iovec, 0, minIovec)
  2231  	iovecs = appendBytes(iovecs, iovs)
  2232  	if raceenabled {
  2233  		raceReleaseMerge(unsafe.Pointer(&ioSync))
  2234  	}
  2235  	n, err = writev(fd, iovecs)
  2236  	writevRacedetect(iovecs, n)
  2237  	return n, err
  2238  }
  2239  
  2240  func Pwritev(fd int, iovs [][]byte, offset int64) (n int, err error) {
  2241  	iovecs := make([]Iovec, 0, minIovec)
  2242  	iovecs = appendBytes(iovecs, iovs)
  2243  	if raceenabled {
  2244  		raceReleaseMerge(unsafe.Pointer(&ioSync))
  2245  	}
  2246  	lo, hi := offs2lohi(offset)
  2247  	n, err = pwritev(fd, iovecs, lo, hi)
  2248  	writevRacedetect(iovecs, n)
  2249  	return n, err
  2250  }
  2251  
  2252  func Pwritev2(fd int, iovs [][]byte, offset int64, flags int) (n int, err error) {
  2253  	iovecs := make([]Iovec, 0, minIovec)
  2254  	iovecs = appendBytes(iovecs, iovs)
  2255  	if raceenabled {
  2256  		raceReleaseMerge(unsafe.Pointer(&ioSync))
  2257  	}
  2258  	lo, hi := offs2lohi(offset)
  2259  	n, err = pwritev2(fd, iovecs, lo, hi, flags)
  2260  	writevRacedetect(iovecs, n)
  2261  	return n, err
  2262  }
  2263  
  2264  func writevRacedetect(iovecs []Iovec, n int) {
  2265  	if !raceenabled {
  2266  		return
  2267  	}
  2268  	for i := 0; n > 0 && i < len(iovecs); i++ {
  2269  		m := min(int(iovecs[i].Len), n)
  2270  		n -= m
  2271  		if m > 0 {
  2272  			raceReadRange(unsafe.Pointer(iovecs[i].Base), m)
  2273  		}
  2274  	}
  2275  }
  2276  
  2277  // mmap varies by architecture; see syscall_linux_*.go.
  2278  //sys	munmap(addr uintptr, length uintptr) (err error)
  2279  //sys	mremap(oldaddr uintptr, oldlength uintptr, newlength uintptr, flags int, newaddr uintptr) (xaddr uintptr, err error)
  2280  //sys	Madvise(b []byte, advice int) (err error)
  2281  //sys	Mprotect(b []byte, prot int) (err error)
  2282  //sys	Mlock(b []byte) (err error)
  2283  //sys	Mlockall(flags int) (err error)
  2284  //sys	Msync(b []byte, flags int) (err error)
  2285  //sys	Munlock(b []byte) (err error)
  2286  //sys	Munlockall() (err error)
  2287  
  2288  const (
  2289  	mremapFixed     = MREMAP_FIXED
  2290  	mremapDontunmap = MREMAP_DONTUNMAP
  2291  	mremapMaymove   = MREMAP_MAYMOVE
  2292  )
  2293  
  2294  // Vmsplice splices user pages from a slice of Iovecs into a pipe specified by fd,
  2295  // using the specified flags.
  2296  func Vmsplice(fd int, iovs []Iovec, flags int) (int, error) {
  2297  	var p unsafe.Pointer
  2298  	if len(iovs) > 0 {
  2299  		p = unsafe.Pointer(&iovs[0])
  2300  	}
  2301  
  2302  	n, _, errno := Syscall6(SYS_VMSPLICE, uintptr(fd), uintptr(p), uintptr(len(iovs)), uintptr(flags), 0, 0)
  2303  	if errno != 0 {
  2304  		return 0, syscall.Errno(errno)
  2305  	}
  2306  
  2307  	return int(n), nil
  2308  }
  2309  
  2310  func isGroupMember(gid int) bool {
  2311  	groups, err := Getgroups()
  2312  	if err != nil {
  2313  		return false
  2314  	}
  2315  
  2316  	return slices.Contains(groups, gid)
  2317  }
  2318  
  2319  func isCapDacOverrideSet() bool {
  2320  	hdr := CapUserHeader{Version: LINUX_CAPABILITY_VERSION_3}
  2321  	data := [2]CapUserData{}
  2322  	err := Capget(&hdr, &data[0])
  2323  
  2324  	return err == nil && data[0].Effective&(1<<CAP_DAC_OVERRIDE) != 0
  2325  }
  2326  
  2327  //sys	faccessat(dirfd int, path string, mode uint32) (err error)
  2328  //sys	Faccessat2(dirfd int, path string, mode uint32, flags int) (err error)
  2329  
  2330  func Faccessat(dirfd int, path string, mode uint32, flags int) (err error) {
  2331  	if flags == 0 {
  2332  		return faccessat(dirfd, path, mode)
  2333  	}
  2334  
  2335  	if err := Faccessat2(dirfd, path, mode, flags); err != ENOSYS && err != EPERM {
  2336  		return err
  2337  	}
  2338  
  2339  	// The Linux kernel faccessat system call does not take any flags.
  2340  	// The glibc faccessat implements the flags itself; see
  2341  	// https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/unix/sysv/linux/faccessat.c;hb=HEAD
  2342  	// Because people naturally expect syscall.Faccessat to act
  2343  	// like C faccessat, we do the same.
  2344  
  2345  	if flags & ^(AT_SYMLINK_NOFOLLOW|AT_EACCESS) != 0 {
  2346  		return EINVAL
  2347  	}
  2348  
  2349  	var st Stat_t
  2350  	if err := Fstatat(dirfd, path, &st, flags&AT_SYMLINK_NOFOLLOW); err != nil {
  2351  		return err
  2352  	}
  2353  
  2354  	mode &= 7
  2355  	if mode == 0 {
  2356  		return nil
  2357  	}
  2358  
  2359  	var uid int
  2360  	if flags&AT_EACCESS != 0 {
  2361  		uid = Geteuid()
  2362  		if uid != 0 && isCapDacOverrideSet() {
  2363  			// If CAP_DAC_OVERRIDE is set, file access check is
  2364  			// done by the kernel in the same way as for root
  2365  			// (see generic_permission() in the Linux sources).
  2366  			uid = 0
  2367  		}
  2368  	} else {
  2369  		uid = Getuid()
  2370  	}
  2371  
  2372  	if uid == 0 {
  2373  		if mode&1 == 0 {
  2374  			// Root can read and write any file.
  2375  			return nil
  2376  		}
  2377  		if st.Mode&0111 != 0 {
  2378  			// Root can execute any file that anybody can execute.
  2379  			return nil
  2380  		}
  2381  		return EACCES
  2382  	}
  2383  
  2384  	var fmode uint32
  2385  	if uint32(uid) == st.Uid {
  2386  		fmode = (st.Mode >> 6) & 7
  2387  	} else {
  2388  		var gid int
  2389  		if flags&AT_EACCESS != 0 {
  2390  			gid = Getegid()
  2391  		} else {
  2392  			gid = Getgid()
  2393  		}
  2394  
  2395  		if uint32(gid) == st.Gid || isGroupMember(int(st.Gid)) {
  2396  			fmode = (st.Mode >> 3) & 7
  2397  		} else {
  2398  			fmode = st.Mode & 7
  2399  		}
  2400  	}
  2401  
  2402  	if fmode&mode == mode {
  2403  		return nil
  2404  	}
  2405  
  2406  	return EACCES
  2407  }
  2408  
  2409  //sys	nameToHandleAt(dirFD int, pathname string, fh *fileHandle, mountID *_C_int, flags int) (err error) = SYS_NAME_TO_HANDLE_AT
  2410  //sys	openByHandleAt(mountFD int, fh *fileHandle, flags int) (fd int, err error) = SYS_OPEN_BY_HANDLE_AT
  2411  
  2412  // fileHandle is the argument to nameToHandleAt and openByHandleAt. We
  2413  // originally tried to generate it via unix/linux/types.go with "type
  2414  // fileHandle C.struct_file_handle" but that generated empty structs
  2415  // for mips64 and mips64le. Instead, hard code it for now (it's the
  2416  // same everywhere else) until the mips64 generator issue is fixed.
  2417  type fileHandle struct {
  2418  	Bytes uint32
  2419  	Type  int32
  2420  }
  2421  
  2422  // FileHandle represents the C struct file_handle used by
  2423  // name_to_handle_at (see NameToHandleAt) and open_by_handle_at (see
  2424  // OpenByHandleAt).
  2425  type FileHandle struct {
  2426  	*fileHandle
  2427  }
  2428  
  2429  // NewFileHandle constructs a FileHandle.
  2430  func NewFileHandle(handleType int32, handle []byte) FileHandle {
  2431  	const hdrSize = unsafe.Sizeof(fileHandle{})
  2432  	buf := make([]byte, hdrSize+uintptr(len(handle)))
  2433  	copy(buf[hdrSize:], handle)
  2434  	fh := (*fileHandle)(unsafe.Pointer(&buf[0]))
  2435  	fh.Type = handleType
  2436  	fh.Bytes = uint32(len(handle))
  2437  	return FileHandle{fh}
  2438  }
  2439  
  2440  func (fh *FileHandle) Size() int   { return int(fh.fileHandle.Bytes) }
  2441  func (fh *FileHandle) Type() int32 { return fh.fileHandle.Type }
  2442  func (fh *FileHandle) Bytes() []byte {
  2443  	n := fh.Size()
  2444  	if n == 0 {
  2445  		return nil
  2446  	}
  2447  	return unsafe.Slice((*byte)(unsafe.Pointer(uintptr(unsafe.Pointer(&fh.fileHandle.Type))+4)), n)
  2448  }
  2449  
  2450  // NameToHandleAt wraps the name_to_handle_at system call; it obtains
  2451  // a handle for a path name.
  2452  func NameToHandleAt(dirfd int, path string, flags int) (handle FileHandle, mountID int, err error) {
  2453  	var mid _C_int
  2454  	// Try first with a small buffer, assuming the handle will
  2455  	// only be 32 bytes.
  2456  	size := uint32(32 + unsafe.Sizeof(fileHandle{}))
  2457  	didResize := false
  2458  	for {
  2459  		buf := make([]byte, size)
  2460  		fh := (*fileHandle)(unsafe.Pointer(&buf[0]))
  2461  		fh.Bytes = size - uint32(unsafe.Sizeof(fileHandle{}))
  2462  		err = nameToHandleAt(dirfd, path, fh, &mid, flags)
  2463  		if err == EOVERFLOW {
  2464  			if didResize {
  2465  				// We shouldn't need to resize more than once
  2466  				return
  2467  			}
  2468  			didResize = true
  2469  			size = fh.Bytes + uint32(unsafe.Sizeof(fileHandle{}))
  2470  			continue
  2471  		}
  2472  		if err != nil {
  2473  			return
  2474  		}
  2475  		return FileHandle{fh}, int(mid), nil
  2476  	}
  2477  }
  2478  
  2479  // OpenByHandleAt wraps the open_by_handle_at system call; it opens a
  2480  // file via a handle as previously returned by NameToHandleAt.
  2481  func OpenByHandleAt(mountFD int, handle FileHandle, flags int) (fd int, err error) {
  2482  	return openByHandleAt(mountFD, handle.fileHandle, flags)
  2483  }
  2484  
  2485  // Klogset wraps the sys_syslog system call; it sets console_loglevel to
  2486  // the value specified by arg and passes a dummy pointer to bufp.
  2487  func Klogset(typ int, arg int) (err error) {
  2488  	var p unsafe.Pointer
  2489  	_, _, errno := Syscall(SYS_SYSLOG, uintptr(typ), uintptr(p), uintptr(arg))
  2490  	if errno != 0 {
  2491  		return errnoErr(errno)
  2492  	}
  2493  	return nil
  2494  }
  2495  
  2496  // RemoteIovec is Iovec with the pointer replaced with an integer.
  2497  // It is used for ProcessVMReadv and ProcessVMWritev, where the pointer
  2498  // refers to a location in a different process' address space, which
  2499  // would confuse the Go garbage collector.
  2500  type RemoteIovec struct {
  2501  	Base uintptr
  2502  	Len  int
  2503  }
  2504  
  2505  //sys	ProcessVMReadv(pid int, localIov []Iovec, remoteIov []RemoteIovec, flags uint) (n int, err error) = SYS_PROCESS_VM_READV
  2506  //sys	ProcessVMWritev(pid int, localIov []Iovec, remoteIov []RemoteIovec, flags uint) (n int, err error) = SYS_PROCESS_VM_WRITEV
  2507  
  2508  //sys	PidfdOpen(pid int, flags int) (fd int, err error) = SYS_PIDFD_OPEN
  2509  //sys	PidfdGetfd(pidfd int, targetfd int, flags int) (fd int, err error) = SYS_PIDFD_GETFD
  2510  //sys	PidfdSendSignal(pidfd int, sig Signal, info *Siginfo, flags int) (err error) = SYS_PIDFD_SEND_SIGNAL
  2511  
  2512  //sys	shmat(id int, addr uintptr, flag int) (ret uintptr, err error)
  2513  //sys	shmctl(id int, cmd int, buf *SysvShmDesc) (result int, err error)
  2514  //sys	shmdt(addr uintptr) (err error)
  2515  //sys	shmget(key int, size int, flag int) (id int, err error)
  2516  
  2517  //sys	getitimer(which int, currValue *Itimerval) (err error)
  2518  //sys	setitimer(which int, newValue *Itimerval, oldValue *Itimerval) (err error)
  2519  
  2520  // MakeItimerval creates an Itimerval from interval and value durations.
  2521  func MakeItimerval(interval, value time.Duration) Itimerval {
  2522  	return Itimerval{
  2523  		Interval: NsecToTimeval(interval.Nanoseconds()),
  2524  		Value:    NsecToTimeval(value.Nanoseconds()),
  2525  	}
  2526  }
  2527  
  2528  // A value which may be passed to the which parameter for Getitimer and
  2529  // Setitimer.
  2530  type ItimerWhich int
  2531  
  2532  // Possible which values for Getitimer and Setitimer.
  2533  const (
  2534  	ItimerReal    ItimerWhich = ITIMER_REAL
  2535  	ItimerVirtual ItimerWhich = ITIMER_VIRTUAL
  2536  	ItimerProf    ItimerWhich = ITIMER_PROF
  2537  )
  2538  
  2539  // Getitimer wraps getitimer(2) to return the current value of the timer
  2540  // specified by which.
  2541  func Getitimer(which ItimerWhich) (Itimerval, error) {
  2542  	var it Itimerval
  2543  	if err := getitimer(int(which), &it); err != nil {
  2544  		return Itimerval{}, err
  2545  	}
  2546  
  2547  	return it, nil
  2548  }
  2549  
  2550  // Setitimer wraps setitimer(2) to arm or disarm the timer specified by which.
  2551  // It returns the previous value of the timer.
  2552  //
  2553  // If the Itimerval argument is the zero value, the timer will be disarmed.
  2554  func Setitimer(which ItimerWhich, it Itimerval) (Itimerval, error) {
  2555  	var prev Itimerval
  2556  	if err := setitimer(int(which), &it, &prev); err != nil {
  2557  		return Itimerval{}, err
  2558  	}
  2559  
  2560  	return prev, nil
  2561  }
  2562  
  2563  //sysnb	rtSigprocmask(how int, set *Sigset_t, oldset *Sigset_t, sigsetsize uintptr) (err error) = SYS_RT_SIGPROCMASK
  2564  
  2565  func PthreadSigmask(how int, set, oldset *Sigset_t) error {
  2566  	if oldset != nil {
  2567  		// Explicitly clear in case Sigset_t is larger than _C__NSIG.
  2568  		*oldset = Sigset_t{}
  2569  	}
  2570  	return rtSigprocmask(how, set, oldset, _C__NSIG/8)
  2571  }
  2572  
  2573  //sysnb	getresuid(ruid *_C_int, euid *_C_int, suid *_C_int)
  2574  //sysnb	getresgid(rgid *_C_int, egid *_C_int, sgid *_C_int)
  2575  
  2576  func Getresuid() (ruid, euid, suid int) {
  2577  	var r, e, s _C_int
  2578  	getresuid(&r, &e, &s)
  2579  	return int(r), int(e), int(s)
  2580  }
  2581  
  2582  func Getresgid() (rgid, egid, sgid int) {
  2583  	var r, e, s _C_int
  2584  	getresgid(&r, &e, &s)
  2585  	return int(r), int(e), int(s)
  2586  }
  2587  
  2588  // Pselect is a wrapper around the Linux pselect6 system call.
  2589  // This version does not modify the timeout argument.
  2590  func Pselect(nfd int, r *FdSet, w *FdSet, e *FdSet, timeout *Timespec, sigmask *Sigset_t) (n int, err error) {
  2591  	// Per https://man7.org/linux/man-pages/man2/select.2.html#NOTES,
  2592  	// The Linux pselect6() system call modifies its timeout argument.
  2593  	// [Not modifying the argument] is the behavior required by POSIX.1-2001.
  2594  	var mutableTimeout *Timespec
  2595  	if timeout != nil {
  2596  		mutableTimeout = new(Timespec)
  2597  		*mutableTimeout = *timeout
  2598  	}
  2599  
  2600  	// The final argument of the pselect6() system call is not a
  2601  	// sigset_t * pointer, but is instead a structure
  2602  	var kernelMask *sigset_argpack
  2603  	if sigmask != nil {
  2604  		wordBits := 32 << (^uintptr(0) >> 63) // see math.intSize
  2605  
  2606  		// A sigset stores one bit per signal,
  2607  		// offset by 1 (because signal 0 does not exist).
  2608  		// So the number of words needed is ⌈__C_NSIG - 1 / wordBits⌉.
  2609  		sigsetWords := (_C__NSIG - 1 + wordBits - 1) / (wordBits)
  2610  
  2611  		sigsetBytes := uintptr(sigsetWords * (wordBits / 8))
  2612  		kernelMask = &sigset_argpack{
  2613  			ss:    sigmask,
  2614  			ssLen: sigsetBytes,
  2615  		}
  2616  	}
  2617  
  2618  	return pselect6(nfd, r, w, e, mutableTimeout, kernelMask)
  2619  }
  2620  
  2621  //sys	schedSetattr(pid int, attr *SchedAttr, flags uint) (err error)
  2622  //sys	schedGetattr(pid int, attr *SchedAttr, size uint, flags uint) (err error)
  2623  
  2624  // SchedSetAttr is a wrapper for sched_setattr(2) syscall.
  2625  // https://man7.org/linux/man-pages/man2/sched_setattr.2.html
  2626  func SchedSetAttr(pid int, attr *SchedAttr, flags uint) error {
  2627  	if attr == nil {
  2628  		return EINVAL
  2629  	}
  2630  	attr.Size = SizeofSchedAttr
  2631  	return schedSetattr(pid, attr, flags)
  2632  }
  2633  
  2634  // SchedGetAttr is a wrapper for sched_getattr(2) syscall.
  2635  // https://man7.org/linux/man-pages/man2/sched_getattr.2.html
  2636  func SchedGetAttr(pid int, flags uint) (*SchedAttr, error) {
  2637  	attr := &SchedAttr{}
  2638  	if err := schedGetattr(pid, attr, SizeofSchedAttr, flags); err != nil {
  2639  		return nil, err
  2640  	}
  2641  	return attr, nil
  2642  }
  2643  
  2644  //sys	Cachestat(fd uint, crange *CachestatRange, cstat *Cachestat_t, flags uint) (err error)
  2645  //sys	Mseal(b []byte, flags uint) (err error)
  2646  

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