Source file src/syscall/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 syscall
    13  
    14  import (
    15  	"internal/itoa"
    16  	"runtime"
    17  	"unsafe"
    18  )
    19  
    20  // N.B. RawSyscall6 is provided via linkname by runtime/internal/syscall.
    21  //
    22  // Errno is uintptr and thus compatible with the runtime/internal/syscall
    23  // definition.
    24  
    25  func RawSyscall6(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err Errno)
    26  
    27  // Pull in entersyscall/exitsyscall for Syscall/Syscall6.
    28  //
    29  // Note that this can't be a push linkname because the runtime already has a
    30  // nameless linkname to export to assembly here and in x/sys. Additionally,
    31  // entersyscall fetches the caller PC and SP and thus can't have a wrapper
    32  // inbetween.
    33  
    34  //go:linkname runtime_entersyscall runtime.entersyscall
    35  func runtime_entersyscall()
    36  
    37  //go:linkname runtime_exitsyscall runtime.exitsyscall
    38  func runtime_exitsyscall()
    39  
    40  // N.B. For the Syscall functions below:
    41  //
    42  // //go:uintptrkeepalive because the uintptr argument may be converted pointers
    43  // that need to be kept alive in the caller (this is implied for RawSyscall6
    44  // since it has no body).
    45  //
    46  // //go:nosplit because stack copying does not account for uintptrkeepalive, so
    47  // the stack must not grow. Stack copying cannot blindly assume that all
    48  // uintptr arguments are pointers, because some values may look like pointers,
    49  // but not really be pointers, and adjusting their value would break the call.
    50  //
    51  // //go:norace, on RawSyscall, to avoid race instrumentation if RawSyscall is
    52  // called after fork, or from a signal handler.
    53  //
    54  // //go:linkname to ensure ABI wrappers are generated for external callers
    55  // (notably x/sys/unix assembly).
    56  
    57  //go:uintptrkeepalive
    58  //go:nosplit
    59  //go:norace
    60  //go:linkname RawSyscall
    61  func RawSyscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err Errno) {
    62  	return RawSyscall6(trap, a1, a2, a3, 0, 0, 0)
    63  }
    64  
    65  //go:uintptrkeepalive
    66  //go:nosplit
    67  //go:linkname Syscall
    68  func Syscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err Errno) {
    69  	runtime_entersyscall()
    70  	// N.B. Calling RawSyscall here is unsafe with atomic coverage
    71  	// instrumentation and race mode.
    72  	//
    73  	// Coverage instrumentation will add a sync/atomic call to RawSyscall.
    74  	// Race mode will add race instrumentation to sync/atomic. Race
    75  	// instrumentation requires a P, which we no longer have.
    76  	//
    77  	// RawSyscall6 is fine because it is implemented in assembly and thus
    78  	// has no coverage instrumentation.
    79  	//
    80  	// This is typically not a problem in the runtime because cmd/go avoids
    81  	// adding coverage instrumentation to the runtime in race mode.
    82  	r1, r2, err = RawSyscall6(trap, a1, a2, a3, 0, 0, 0)
    83  	runtime_exitsyscall()
    84  	return
    85  }
    86  
    87  //go:uintptrkeepalive
    88  //go:nosplit
    89  //go:linkname Syscall6
    90  func Syscall6(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err Errno) {
    91  	runtime_entersyscall()
    92  	r1, r2, err = RawSyscall6(trap, a1, a2, a3, a4, a5, a6)
    93  	runtime_exitsyscall()
    94  	return
    95  }
    96  
    97  func rawSyscallNoError(trap, a1, a2, a3 uintptr) (r1, r2 uintptr)
    98  func rawVforkSyscall(trap, a1, a2 uintptr) (r1 uintptr, err Errno)
    99  
   100  /*
   101   * Wrapped
   102   */
   103  
   104  func Access(path string, mode uint32) (err error) {
   105  	return Faccessat(_AT_FDCWD, path, mode, 0)
   106  }
   107  
   108  func Chmod(path string, mode uint32) (err error) {
   109  	return Fchmodat(_AT_FDCWD, path, mode, 0)
   110  }
   111  
   112  func Chown(path string, uid int, gid int) (err error) {
   113  	return Fchownat(_AT_FDCWD, path, uid, gid, 0)
   114  }
   115  
   116  func Creat(path string, mode uint32) (fd int, err error) {
   117  	return Open(path, O_CREAT|O_WRONLY|O_TRUNC, mode)
   118  }
   119  
   120  func EpollCreate(size int) (fd int, err error) {
   121  	if size <= 0 {
   122  		return -1, EINVAL
   123  	}
   124  	return EpollCreate1(0)
   125  }
   126  
   127  func isGroupMember(gid int) bool {
   128  	groups, err := Getgroups()
   129  	if err != nil {
   130  		return false
   131  	}
   132  
   133  	for _, g := range groups {
   134  		if g == gid {
   135  			return true
   136  		}
   137  	}
   138  	return false
   139  }
   140  
   141  func isCapDacOverrideSet() bool {
   142  	const _CAP_DAC_OVERRIDE = 1
   143  	var c caps
   144  	c.hdr.version = _LINUX_CAPABILITY_VERSION_3
   145  
   146  	_, _, err := RawSyscall(SYS_CAPGET, uintptr(unsafe.Pointer(&c.hdr)), uintptr(unsafe.Pointer(&c.data[0])), 0)
   147  
   148  	return err == 0 && c.data[0].effective&capToMask(_CAP_DAC_OVERRIDE) != 0
   149  }
   150  
   151  //sys	faccessat(dirfd int, path string, mode uint32) (err error)
   152  //sys	faccessat2(dirfd int, path string, mode uint32, flags int) (err error) = _SYS_faccessat2
   153  
   154  func Faccessat(dirfd int, path string, mode uint32, flags int) (err error) {
   155  	if flags == 0 {
   156  		return faccessat(dirfd, path, mode)
   157  	}
   158  
   159  	// Attempt to use the newer faccessat2, which supports flags directly,
   160  	// falling back if it doesn't exist.
   161  	//
   162  	// Don't attempt on Android, which does not allow faccessat2 through
   163  	// its seccomp policy [1] on any version of Android as of 2022-12-20.
   164  	//
   165  	// [1] https://cs.android.com/android/platform/superproject/+/master:bionic/libc/SECCOMP_BLOCKLIST_APP.TXT;l=4;drc=dbb8670dfdcc677f7e3b9262e93800fa14c4e417
   166  	if runtime.GOOS != "android" {
   167  		if err := faccessat2(dirfd, path, mode, flags); err != ENOSYS && err != EPERM {
   168  			return err
   169  		}
   170  	}
   171  
   172  	// The Linux kernel faccessat system call does not take any flags.
   173  	// The glibc faccessat implements the flags itself; see
   174  	// https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/unix/sysv/linux/faccessat.c;hb=HEAD
   175  	// Because people naturally expect syscall.Faccessat to act
   176  	// like C faccessat, we do the same.
   177  
   178  	if flags & ^(_AT_SYMLINK_NOFOLLOW|_AT_EACCESS) != 0 {
   179  		return EINVAL
   180  	}
   181  
   182  	var st Stat_t
   183  	if err := fstatat(dirfd, path, &st, flags&_AT_SYMLINK_NOFOLLOW); err != nil {
   184  		return err
   185  	}
   186  
   187  	mode &= 7
   188  	if mode == 0 {
   189  		return nil
   190  	}
   191  
   192  	// Fallback to checking permission bits.
   193  	var uid int
   194  	if flags&_AT_EACCESS != 0 {
   195  		uid = Geteuid()
   196  		if uid != 0 && isCapDacOverrideSet() {
   197  			// If CAP_DAC_OVERRIDE is set, file access check is
   198  			// done by the kernel in the same way as for root
   199  			// (see generic_permission() in the Linux sources).
   200  			uid = 0
   201  		}
   202  	} else {
   203  		uid = Getuid()
   204  	}
   205  
   206  	if uid == 0 {
   207  		if mode&1 == 0 {
   208  			// Root can read and write any file.
   209  			return nil
   210  		}
   211  		if st.Mode&0111 != 0 {
   212  			// Root can execute any file that anybody can execute.
   213  			return nil
   214  		}
   215  		return EACCES
   216  	}
   217  
   218  	var fmode uint32
   219  	if uint32(uid) == st.Uid {
   220  		fmode = (st.Mode >> 6) & 7
   221  	} else {
   222  		var gid int
   223  		if flags&_AT_EACCESS != 0 {
   224  			gid = Getegid()
   225  		} else {
   226  			gid = Getgid()
   227  		}
   228  
   229  		if uint32(gid) == st.Gid || isGroupMember(int(st.Gid)) {
   230  			fmode = (st.Mode >> 3) & 7
   231  		} else {
   232  			fmode = st.Mode & 7
   233  		}
   234  	}
   235  
   236  	if fmode&mode == mode {
   237  		return nil
   238  	}
   239  
   240  	return EACCES
   241  }
   242  
   243  //sys	fchmodat(dirfd int, path string, mode uint32) (err error)
   244  
   245  func Fchmodat(dirfd int, path string, mode uint32, flags int) (err error) {
   246  	// Linux fchmodat doesn't support the flags parameter. Mimick glibc's behavior
   247  	// and check the flags. Otherwise the mode would be applied to the symlink
   248  	// destination which is not what the user expects.
   249  	if flags&^_AT_SYMLINK_NOFOLLOW != 0 {
   250  		return EINVAL
   251  	} else if flags&_AT_SYMLINK_NOFOLLOW != 0 {
   252  		return EOPNOTSUPP
   253  	}
   254  	return fchmodat(dirfd, path, mode)
   255  }
   256  
   257  //sys	linkat(olddirfd int, oldpath string, newdirfd int, newpath string, flags int) (err error)
   258  
   259  func Link(oldpath string, newpath string) (err error) {
   260  	return linkat(_AT_FDCWD, oldpath, _AT_FDCWD, newpath, 0)
   261  }
   262  
   263  func Mkdir(path string, mode uint32) (err error) {
   264  	return Mkdirat(_AT_FDCWD, path, mode)
   265  }
   266  
   267  func Mknod(path string, mode uint32, dev int) (err error) {
   268  	return Mknodat(_AT_FDCWD, path, mode, dev)
   269  }
   270  
   271  func Open(path string, mode int, perm uint32) (fd int, err error) {
   272  	return openat(_AT_FDCWD, path, mode|O_LARGEFILE, perm)
   273  }
   274  
   275  //sys	openat(dirfd int, path string, flags int, mode uint32) (fd int, err error)
   276  
   277  func Openat(dirfd int, path string, flags int, mode uint32) (fd int, err error) {
   278  	return openat(dirfd, path, flags|O_LARGEFILE, mode)
   279  }
   280  
   281  func Pipe(p []int) error {
   282  	return Pipe2(p, 0)
   283  }
   284  
   285  //sysnb pipe2(p *[2]_C_int, flags int) (err error)
   286  
   287  func Pipe2(p []int, flags int) error {
   288  	if len(p) != 2 {
   289  		return EINVAL
   290  	}
   291  	var pp [2]_C_int
   292  	err := pipe2(&pp, flags)
   293  	if err == nil {
   294  		p[0] = int(pp[0])
   295  		p[1] = int(pp[1])
   296  	}
   297  	return err
   298  }
   299  
   300  //sys	readlinkat(dirfd int, path string, buf []byte) (n int, err error)
   301  
   302  func Readlink(path string, buf []byte) (n int, err error) {
   303  	return readlinkat(_AT_FDCWD, path, buf)
   304  }
   305  
   306  func Rename(oldpath string, newpath string) (err error) {
   307  	return Renameat(_AT_FDCWD, oldpath, _AT_FDCWD, newpath)
   308  }
   309  
   310  func Rmdir(path string) error {
   311  	return unlinkat(_AT_FDCWD, path, _AT_REMOVEDIR)
   312  }
   313  
   314  //sys	symlinkat(oldpath string, newdirfd int, newpath string) (err error)
   315  
   316  func Symlink(oldpath string, newpath string) (err error) {
   317  	return symlinkat(oldpath, _AT_FDCWD, newpath)
   318  }
   319  
   320  func Unlink(path string) error {
   321  	return unlinkat(_AT_FDCWD, path, 0)
   322  }
   323  
   324  //sys	unlinkat(dirfd int, path string, flags int) (err error)
   325  
   326  func Unlinkat(dirfd int, path string) error {
   327  	return unlinkat(dirfd, path, 0)
   328  }
   329  
   330  func Utimes(path string, tv []Timeval) (err error) {
   331  	if len(tv) != 2 {
   332  		return EINVAL
   333  	}
   334  	return utimes(path, (*[2]Timeval)(unsafe.Pointer(&tv[0])))
   335  }
   336  
   337  //sys	utimensat(dirfd int, path string, times *[2]Timespec, flag int) (err error)
   338  
   339  func UtimesNano(path string, ts []Timespec) (err error) {
   340  	if len(ts) != 2 {
   341  		return EINVAL
   342  	}
   343  	return utimensat(_AT_FDCWD, path, (*[2]Timespec)(unsafe.Pointer(&ts[0])), 0)
   344  }
   345  
   346  func Futimesat(dirfd int, path string, tv []Timeval) (err error) {
   347  	if len(tv) != 2 {
   348  		return EINVAL
   349  	}
   350  	return futimesat(dirfd, path, (*[2]Timeval)(unsafe.Pointer(&tv[0])))
   351  }
   352  
   353  func Futimes(fd int, tv []Timeval) (err error) {
   354  	// Believe it or not, this is the best we can do on Linux
   355  	// (and is what glibc does).
   356  	return Utimes("/proc/self/fd/"+itoa.Itoa(fd), tv)
   357  }
   358  
   359  const ImplementsGetwd = true
   360  
   361  //sys	Getcwd(buf []byte) (n int, err error)
   362  
   363  func Getwd() (wd string, err error) {
   364  	var buf [PathMax]byte
   365  	n, err := Getcwd(buf[0:])
   366  	if err != nil {
   367  		return "", err
   368  	}
   369  	// Getcwd returns the number of bytes written to buf, including the NUL.
   370  	if n < 1 || n > len(buf) || buf[n-1] != 0 {
   371  		return "", EINVAL
   372  	}
   373  	// In some cases, Linux can return a path that starts with the
   374  	// "(unreachable)" prefix, which can potentially be a valid relative
   375  	// path. To work around that, return ENOENT if path is not absolute.
   376  	if buf[0] != '/' {
   377  		return "", ENOENT
   378  	}
   379  
   380  	return string(buf[0 : n-1]), nil
   381  }
   382  
   383  func Getgroups() (gids []int, err error) {
   384  	n, err := getgroups(0, nil)
   385  	if err != nil {
   386  		return nil, err
   387  	}
   388  	if n == 0 {
   389  		return nil, nil
   390  	}
   391  
   392  	// Sanity check group count. Max is 1<<16 on Linux.
   393  	if n < 0 || n > 1<<20 {
   394  		return nil, EINVAL
   395  	}
   396  
   397  	a := make([]_Gid_t, n)
   398  	n, err = getgroups(n, &a[0])
   399  	if err != nil {
   400  		return nil, err
   401  	}
   402  	gids = make([]int, n)
   403  	for i, v := range a[0:n] {
   404  		gids[i] = int(v)
   405  	}
   406  	return
   407  }
   408  
   409  var cgo_libc_setgroups unsafe.Pointer // non-nil if cgo linked.
   410  
   411  func Setgroups(gids []int) (err error) {
   412  	n := uintptr(len(gids))
   413  	if n == 0 {
   414  		if cgo_libc_setgroups == nil {
   415  			if _, _, e1 := AllThreadsSyscall(_SYS_setgroups, 0, 0, 0); e1 != 0 {
   416  				err = errnoErr(e1)
   417  			}
   418  			return
   419  		}
   420  		if ret := cgocaller(cgo_libc_setgroups, 0, 0); ret != 0 {
   421  			err = errnoErr(Errno(ret))
   422  		}
   423  		return
   424  	}
   425  
   426  	a := make([]_Gid_t, len(gids))
   427  	for i, v := range gids {
   428  		a[i] = _Gid_t(v)
   429  	}
   430  	if cgo_libc_setgroups == nil {
   431  		if _, _, e1 := AllThreadsSyscall(_SYS_setgroups, n, uintptr(unsafe.Pointer(&a[0])), 0); e1 != 0 {
   432  			err = errnoErr(e1)
   433  		}
   434  		return
   435  	}
   436  	if ret := cgocaller(cgo_libc_setgroups, n, uintptr(unsafe.Pointer(&a[0]))); ret != 0 {
   437  		err = errnoErr(Errno(ret))
   438  	}
   439  	return
   440  }
   441  
   442  type WaitStatus uint32
   443  
   444  // Wait status is 7 bits at bottom, either 0 (exited),
   445  // 0x7F (stopped), or a signal number that caused an exit.
   446  // The 0x80 bit is whether there was a core dump.
   447  // An extra number (exit code, signal causing a stop)
   448  // is in the high bits. At least that's the idea.
   449  // There are various irregularities. For example, the
   450  // "continued" status is 0xFFFF, distinguishing itself
   451  // from stopped via the core dump bit.
   452  
   453  const (
   454  	mask    = 0x7F
   455  	core    = 0x80
   456  	exited  = 0x00
   457  	stopped = 0x7F
   458  	shift   = 8
   459  )
   460  
   461  func (w WaitStatus) Exited() bool { return w&mask == exited }
   462  
   463  func (w WaitStatus) Signaled() bool { return w&mask != stopped && w&mask != exited }
   464  
   465  func (w WaitStatus) Stopped() bool { return w&0xFF == stopped }
   466  
   467  func (w WaitStatus) Continued() bool { return w == 0xFFFF }
   468  
   469  func (w WaitStatus) CoreDump() bool { return w.Signaled() && w&core != 0 }
   470  
   471  func (w WaitStatus) ExitStatus() int {
   472  	if !w.Exited() {
   473  		return -1
   474  	}
   475  	return int(w>>shift) & 0xFF
   476  }
   477  
   478  func (w WaitStatus) Signal() Signal {
   479  	if !w.Signaled() {
   480  		return -1
   481  	}
   482  	return Signal(w & mask)
   483  }
   484  
   485  func (w WaitStatus) StopSignal() Signal {
   486  	if !w.Stopped() {
   487  		return -1
   488  	}
   489  	return Signal(w>>shift) & 0xFF
   490  }
   491  
   492  func (w WaitStatus) TrapCause() int {
   493  	if w.StopSignal() != SIGTRAP {
   494  		return -1
   495  	}
   496  	return int(w>>shift) >> 8
   497  }
   498  
   499  //sys	wait4(pid int, wstatus *_C_int, options int, rusage *Rusage) (wpid int, err error)
   500  
   501  func Wait4(pid int, wstatus *WaitStatus, options int, rusage *Rusage) (wpid int, err error) {
   502  	var status _C_int
   503  	wpid, err = wait4(pid, &status, options, rusage)
   504  	if wstatus != nil {
   505  		*wstatus = WaitStatus(status)
   506  	}
   507  	return
   508  }
   509  
   510  func Mkfifo(path string, mode uint32) (err error) {
   511  	return Mknod(path, mode|S_IFIFO, 0)
   512  }
   513  
   514  func (sa *SockaddrInet4) sockaddr() (unsafe.Pointer, _Socklen, error) {
   515  	if sa.Port < 0 || sa.Port > 0xFFFF {
   516  		return nil, 0, EINVAL
   517  	}
   518  	sa.raw.Family = AF_INET
   519  	p := (*[2]byte)(unsafe.Pointer(&sa.raw.Port))
   520  	p[0] = byte(sa.Port >> 8)
   521  	p[1] = byte(sa.Port)
   522  	sa.raw.Addr = sa.Addr
   523  	return unsafe.Pointer(&sa.raw), SizeofSockaddrInet4, nil
   524  }
   525  
   526  func (sa *SockaddrInet6) sockaddr() (unsafe.Pointer, _Socklen, error) {
   527  	if sa.Port < 0 || sa.Port > 0xFFFF {
   528  		return nil, 0, EINVAL
   529  	}
   530  	sa.raw.Family = AF_INET6
   531  	p := (*[2]byte)(unsafe.Pointer(&sa.raw.Port))
   532  	p[0] = byte(sa.Port >> 8)
   533  	p[1] = byte(sa.Port)
   534  	sa.raw.Scope_id = sa.ZoneId
   535  	sa.raw.Addr = sa.Addr
   536  	return unsafe.Pointer(&sa.raw), SizeofSockaddrInet6, nil
   537  }
   538  
   539  func (sa *SockaddrUnix) sockaddr() (unsafe.Pointer, _Socklen, error) {
   540  	name := sa.Name
   541  	n := len(name)
   542  	if n > len(sa.raw.Path) {
   543  		return nil, 0, EINVAL
   544  	}
   545  	if n == len(sa.raw.Path) && name[0] != '@' {
   546  		return nil, 0, EINVAL
   547  	}
   548  	sa.raw.Family = AF_UNIX
   549  	for i := 0; i < n; i++ {
   550  		sa.raw.Path[i] = int8(name[i])
   551  	}
   552  	// length is family (uint16), name, NUL.
   553  	sl := _Socklen(2)
   554  	if n > 0 {
   555  		sl += _Socklen(n) + 1
   556  	}
   557  	if sa.raw.Path[0] == '@' {
   558  		sa.raw.Path[0] = 0
   559  		// Don't count trailing NUL for abstract address.
   560  		sl--
   561  	}
   562  
   563  	return unsafe.Pointer(&sa.raw), sl, nil
   564  }
   565  
   566  type SockaddrLinklayer struct {
   567  	Protocol uint16
   568  	Ifindex  int
   569  	Hatype   uint16
   570  	Pkttype  uint8
   571  	Halen    uint8
   572  	Addr     [8]byte
   573  	raw      RawSockaddrLinklayer
   574  }
   575  
   576  func (sa *SockaddrLinklayer) sockaddr() (unsafe.Pointer, _Socklen, error) {
   577  	if sa.Ifindex < 0 || sa.Ifindex > 0x7fffffff {
   578  		return nil, 0, EINVAL
   579  	}
   580  	sa.raw.Family = AF_PACKET
   581  	sa.raw.Protocol = sa.Protocol
   582  	sa.raw.Ifindex = int32(sa.Ifindex)
   583  	sa.raw.Hatype = sa.Hatype
   584  	sa.raw.Pkttype = sa.Pkttype
   585  	sa.raw.Halen = sa.Halen
   586  	sa.raw.Addr = sa.Addr
   587  	return unsafe.Pointer(&sa.raw), SizeofSockaddrLinklayer, nil
   588  }
   589  
   590  type SockaddrNetlink struct {
   591  	Family uint16
   592  	Pad    uint16
   593  	Pid    uint32
   594  	Groups uint32
   595  	raw    RawSockaddrNetlink
   596  }
   597  
   598  func (sa *SockaddrNetlink) sockaddr() (unsafe.Pointer, _Socklen, error) {
   599  	sa.raw.Family = AF_NETLINK
   600  	sa.raw.Pad = sa.Pad
   601  	sa.raw.Pid = sa.Pid
   602  	sa.raw.Groups = sa.Groups
   603  	return unsafe.Pointer(&sa.raw), SizeofSockaddrNetlink, nil
   604  }
   605  
   606  func anyToSockaddr(rsa *RawSockaddrAny) (Sockaddr, error) {
   607  	switch rsa.Addr.Family {
   608  	case AF_NETLINK:
   609  		pp := (*RawSockaddrNetlink)(unsafe.Pointer(rsa))
   610  		sa := new(SockaddrNetlink)
   611  		sa.Family = pp.Family
   612  		sa.Pad = pp.Pad
   613  		sa.Pid = pp.Pid
   614  		sa.Groups = pp.Groups
   615  		return sa, nil
   616  
   617  	case AF_PACKET:
   618  		pp := (*RawSockaddrLinklayer)(unsafe.Pointer(rsa))
   619  		sa := new(SockaddrLinklayer)
   620  		sa.Protocol = pp.Protocol
   621  		sa.Ifindex = int(pp.Ifindex)
   622  		sa.Hatype = pp.Hatype
   623  		sa.Pkttype = pp.Pkttype
   624  		sa.Halen = pp.Halen
   625  		sa.Addr = pp.Addr
   626  		return sa, nil
   627  
   628  	case AF_UNIX:
   629  		pp := (*RawSockaddrUnix)(unsafe.Pointer(rsa))
   630  		sa := new(SockaddrUnix)
   631  		if pp.Path[0] == 0 {
   632  			// "Abstract" Unix domain socket.
   633  			// Rewrite leading NUL as @ for textual display.
   634  			// (This is the standard convention.)
   635  			// Not friendly to overwrite in place,
   636  			// but the callers below don't care.
   637  			pp.Path[0] = '@'
   638  		}
   639  
   640  		// Assume path ends at NUL.
   641  		// This is not technically the Linux semantics for
   642  		// abstract Unix domain sockets--they are supposed
   643  		// to be uninterpreted fixed-size binary blobs--but
   644  		// everyone uses this convention.
   645  		n := 0
   646  		for n < len(pp.Path) && pp.Path[n] != 0 {
   647  			n++
   648  		}
   649  		bytes := (*[len(pp.Path)]byte)(unsafe.Pointer(&pp.Path[0]))[0:n]
   650  		sa.Name = string(bytes)
   651  		return sa, nil
   652  
   653  	case AF_INET:
   654  		pp := (*RawSockaddrInet4)(unsafe.Pointer(rsa))
   655  		sa := new(SockaddrInet4)
   656  		p := (*[2]byte)(unsafe.Pointer(&pp.Port))
   657  		sa.Port = int(p[0])<<8 + int(p[1])
   658  		sa.Addr = pp.Addr
   659  		return sa, nil
   660  
   661  	case AF_INET6:
   662  		pp := (*RawSockaddrInet6)(unsafe.Pointer(rsa))
   663  		sa := new(SockaddrInet6)
   664  		p := (*[2]byte)(unsafe.Pointer(&pp.Port))
   665  		sa.Port = int(p[0])<<8 + int(p[1])
   666  		sa.ZoneId = pp.Scope_id
   667  		sa.Addr = pp.Addr
   668  		return sa, nil
   669  	}
   670  	return nil, EAFNOSUPPORT
   671  }
   672  
   673  func Accept4(fd int, flags int) (nfd int, sa Sockaddr, err error) {
   674  	var rsa RawSockaddrAny
   675  	var len _Socklen = SizeofSockaddrAny
   676  	nfd, err = accept4(fd, &rsa, &len, flags)
   677  	if err != nil {
   678  		return
   679  	}
   680  	if len > SizeofSockaddrAny {
   681  		panic("RawSockaddrAny too small")
   682  	}
   683  	sa, err = anyToSockaddr(&rsa)
   684  	if err != nil {
   685  		Close(nfd)
   686  		nfd = 0
   687  	}
   688  	return
   689  }
   690  
   691  func Getsockname(fd int) (sa Sockaddr, err error) {
   692  	var rsa RawSockaddrAny
   693  	var len _Socklen = SizeofSockaddrAny
   694  	if err = getsockname(fd, &rsa, &len); err != nil {
   695  		return
   696  	}
   697  	return anyToSockaddr(&rsa)
   698  }
   699  
   700  func GetsockoptInet4Addr(fd, level, opt int) (value [4]byte, err error) {
   701  	vallen := _Socklen(4)
   702  	err = getsockopt(fd, level, opt, unsafe.Pointer(&value[0]), &vallen)
   703  	return value, err
   704  }
   705  
   706  func GetsockoptIPMreq(fd, level, opt int) (*IPMreq, error) {
   707  	var value IPMreq
   708  	vallen := _Socklen(SizeofIPMreq)
   709  	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
   710  	return &value, err
   711  }
   712  
   713  func GetsockoptIPMreqn(fd, level, opt int) (*IPMreqn, error) {
   714  	var value IPMreqn
   715  	vallen := _Socklen(SizeofIPMreqn)
   716  	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
   717  	return &value, err
   718  }
   719  
   720  func GetsockoptIPv6Mreq(fd, level, opt int) (*IPv6Mreq, error) {
   721  	var value IPv6Mreq
   722  	vallen := _Socklen(SizeofIPv6Mreq)
   723  	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
   724  	return &value, err
   725  }
   726  
   727  func GetsockoptIPv6MTUInfo(fd, level, opt int) (*IPv6MTUInfo, error) {
   728  	var value IPv6MTUInfo
   729  	vallen := _Socklen(SizeofIPv6MTUInfo)
   730  	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
   731  	return &value, err
   732  }
   733  
   734  func GetsockoptICMPv6Filter(fd, level, opt int) (*ICMPv6Filter, error) {
   735  	var value ICMPv6Filter
   736  	vallen := _Socklen(SizeofICMPv6Filter)
   737  	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
   738  	return &value, err
   739  }
   740  
   741  func GetsockoptUcred(fd, level, opt int) (*Ucred, error) {
   742  	var value Ucred
   743  	vallen := _Socklen(SizeofUcred)
   744  	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
   745  	return &value, err
   746  }
   747  
   748  func SetsockoptIPMreqn(fd, level, opt int, mreq *IPMreqn) (err error) {
   749  	return setsockopt(fd, level, opt, unsafe.Pointer(mreq), unsafe.Sizeof(*mreq))
   750  }
   751  
   752  func recvmsgRaw(fd int, p, oob []byte, flags int, rsa *RawSockaddrAny) (n, oobn int, recvflags int, err error) {
   753  	var msg Msghdr
   754  	msg.Name = (*byte)(unsafe.Pointer(rsa))
   755  	msg.Namelen = uint32(SizeofSockaddrAny)
   756  	var iov Iovec
   757  	if len(p) > 0 {
   758  		iov.Base = &p[0]
   759  		iov.SetLen(len(p))
   760  	}
   761  	var dummy byte
   762  	if len(oob) > 0 {
   763  		if len(p) == 0 {
   764  			var sockType int
   765  			sockType, err = GetsockoptInt(fd, SOL_SOCKET, SO_TYPE)
   766  			if err != nil {
   767  				return
   768  			}
   769  			// receive at least one normal byte
   770  			if sockType != SOCK_DGRAM {
   771  				iov.Base = &dummy
   772  				iov.SetLen(1)
   773  			}
   774  		}
   775  		msg.Control = &oob[0]
   776  		msg.SetControllen(len(oob))
   777  	}
   778  	msg.Iov = &iov
   779  	msg.Iovlen = 1
   780  	if n, err = recvmsg(fd, &msg, flags); err != nil {
   781  		return
   782  	}
   783  	oobn = int(msg.Controllen)
   784  	recvflags = int(msg.Flags)
   785  	return
   786  }
   787  
   788  func sendmsgN(fd int, p, oob []byte, ptr unsafe.Pointer, salen _Socklen, flags int) (n int, err error) {
   789  	var msg Msghdr
   790  	msg.Name = (*byte)(ptr)
   791  	msg.Namelen = uint32(salen)
   792  	var iov Iovec
   793  	if len(p) > 0 {
   794  		iov.Base = &p[0]
   795  		iov.SetLen(len(p))
   796  	}
   797  	var dummy byte
   798  	if len(oob) > 0 {
   799  		if len(p) == 0 {
   800  			var sockType int
   801  			sockType, err = GetsockoptInt(fd, SOL_SOCKET, SO_TYPE)
   802  			if err != nil {
   803  				return 0, err
   804  			}
   805  			// send at least one normal byte
   806  			if sockType != SOCK_DGRAM {
   807  				iov.Base = &dummy
   808  				iov.SetLen(1)
   809  			}
   810  		}
   811  		msg.Control = &oob[0]
   812  		msg.SetControllen(len(oob))
   813  	}
   814  	msg.Iov = &iov
   815  	msg.Iovlen = 1
   816  	if n, err = sendmsg(fd, &msg, flags); err != nil {
   817  		return 0, err
   818  	}
   819  	if len(oob) > 0 && len(p) == 0 {
   820  		n = 0
   821  	}
   822  	return n, nil
   823  }
   824  
   825  // BindToDevice binds the socket associated with fd to device.
   826  func BindToDevice(fd int, device string) (err error) {
   827  	return SetsockoptString(fd, SOL_SOCKET, SO_BINDTODEVICE, device)
   828  }
   829  
   830  //sys	ptrace(request int, pid int, addr uintptr, data uintptr) (err error)
   831  
   832  func ptracePeek(req int, pid int, addr uintptr, out []byte) (count int, err error) {
   833  	// The peek requests are machine-size oriented, so we wrap it
   834  	// to retrieve arbitrary-length data.
   835  
   836  	// The ptrace syscall differs from glibc's ptrace.
   837  	// Peeks returns the word in *data, not as the return value.
   838  
   839  	var buf [sizeofPtr]byte
   840  
   841  	// Leading edge. PEEKTEXT/PEEKDATA don't require aligned
   842  	// access (PEEKUSER warns that it might), but if we don't
   843  	// align our reads, we might straddle an unmapped page
   844  	// boundary and not get the bytes leading up to the page
   845  	// boundary.
   846  	n := 0
   847  	if addr%sizeofPtr != 0 {
   848  		err = ptrace(req, pid, addr-addr%sizeofPtr, uintptr(unsafe.Pointer(&buf[0])))
   849  		if err != nil {
   850  			return 0, err
   851  		}
   852  		n += copy(out, buf[addr%sizeofPtr:])
   853  		out = out[n:]
   854  	}
   855  
   856  	// Remainder.
   857  	for len(out) > 0 {
   858  		// We use an internal buffer to guarantee alignment.
   859  		// It's not documented if this is necessary, but we're paranoid.
   860  		err = ptrace(req, pid, addr+uintptr(n), uintptr(unsafe.Pointer(&buf[0])))
   861  		if err != nil {
   862  			return n, err
   863  		}
   864  		copied := copy(out, buf[0:])
   865  		n += copied
   866  		out = out[copied:]
   867  	}
   868  
   869  	return n, nil
   870  }
   871  
   872  func PtracePeekText(pid int, addr uintptr, out []byte) (count int, err error) {
   873  	return ptracePeek(PTRACE_PEEKTEXT, pid, addr, out)
   874  }
   875  
   876  func PtracePeekData(pid int, addr uintptr, out []byte) (count int, err error) {
   877  	return ptracePeek(PTRACE_PEEKDATA, pid, addr, out)
   878  }
   879  
   880  func ptracePoke(pokeReq int, peekReq int, pid int, addr uintptr, data []byte) (count int, err error) {
   881  	// As for ptracePeek, we need to align our accesses to deal
   882  	// with the possibility of straddling an invalid page.
   883  
   884  	// Leading edge.
   885  	n := 0
   886  	if addr%sizeofPtr != 0 {
   887  		var buf [sizeofPtr]byte
   888  		err = ptrace(peekReq, pid, addr-addr%sizeofPtr, uintptr(unsafe.Pointer(&buf[0])))
   889  		if err != nil {
   890  			return 0, err
   891  		}
   892  		n += copy(buf[addr%sizeofPtr:], data)
   893  		word := *((*uintptr)(unsafe.Pointer(&buf[0])))
   894  		err = ptrace(pokeReq, pid, addr-addr%sizeofPtr, word)
   895  		if err != nil {
   896  			return 0, err
   897  		}
   898  		data = data[n:]
   899  	}
   900  
   901  	// Interior.
   902  	for len(data) > sizeofPtr {
   903  		word := *((*uintptr)(unsafe.Pointer(&data[0])))
   904  		err = ptrace(pokeReq, pid, addr+uintptr(n), word)
   905  		if err != nil {
   906  			return n, err
   907  		}
   908  		n += sizeofPtr
   909  		data = data[sizeofPtr:]
   910  	}
   911  
   912  	// Trailing edge.
   913  	if len(data) > 0 {
   914  		var buf [sizeofPtr]byte
   915  		err = ptrace(peekReq, pid, addr+uintptr(n), uintptr(unsafe.Pointer(&buf[0])))
   916  		if err != nil {
   917  			return n, err
   918  		}
   919  		copy(buf[0:], data)
   920  		word := *((*uintptr)(unsafe.Pointer(&buf[0])))
   921  		err = ptrace(pokeReq, pid, addr+uintptr(n), word)
   922  		if err != nil {
   923  			return n, err
   924  		}
   925  		n += len(data)
   926  	}
   927  
   928  	return n, nil
   929  }
   930  
   931  func PtracePokeText(pid int, addr uintptr, data []byte) (count int, err error) {
   932  	return ptracePoke(PTRACE_POKETEXT, PTRACE_PEEKTEXT, pid, addr, data)
   933  }
   934  
   935  func PtracePokeData(pid int, addr uintptr, data []byte) (count int, err error) {
   936  	return ptracePoke(PTRACE_POKEDATA, PTRACE_PEEKDATA, pid, addr, data)
   937  }
   938  
   939  func PtraceGetRegs(pid int, regsout *PtraceRegs) (err error) {
   940  	return ptrace(PTRACE_GETREGS, pid, 0, uintptr(unsafe.Pointer(regsout)))
   941  }
   942  
   943  func PtraceSetRegs(pid int, regs *PtraceRegs) (err error) {
   944  	return ptrace(PTRACE_SETREGS, pid, 0, uintptr(unsafe.Pointer(regs)))
   945  }
   946  
   947  func PtraceSetOptions(pid int, options int) (err error) {
   948  	return ptrace(PTRACE_SETOPTIONS, pid, 0, uintptr(options))
   949  }
   950  
   951  func PtraceGetEventMsg(pid int) (msg uint, err error) {
   952  	var data _C_long
   953  	err = ptrace(PTRACE_GETEVENTMSG, pid, 0, uintptr(unsafe.Pointer(&data)))
   954  	msg = uint(data)
   955  	return
   956  }
   957  
   958  func PtraceCont(pid int, signal int) (err error) {
   959  	return ptrace(PTRACE_CONT, pid, 0, uintptr(signal))
   960  }
   961  
   962  func PtraceSyscall(pid int, signal int) (err error) {
   963  	return ptrace(PTRACE_SYSCALL, pid, 0, uintptr(signal))
   964  }
   965  
   966  func PtraceSingleStep(pid int) (err error) { return ptrace(PTRACE_SINGLESTEP, pid, 0, 0) }
   967  
   968  func PtraceAttach(pid int) (err error) { return ptrace(PTRACE_ATTACH, pid, 0, 0) }
   969  
   970  func PtraceDetach(pid int) (err error) { return ptrace(PTRACE_DETACH, pid, 0, 0) }
   971  
   972  //sys	reboot(magic1 uint, magic2 uint, cmd int, arg string) (err error)
   973  
   974  func Reboot(cmd int) (err error) {
   975  	return reboot(LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2, cmd, "")
   976  }
   977  
   978  func ReadDirent(fd int, buf []byte) (n int, err error) {
   979  	return Getdents(fd, buf)
   980  }
   981  
   982  func direntIno(buf []byte) (uint64, bool) {
   983  	return readInt(buf, unsafe.Offsetof(Dirent{}.Ino), unsafe.Sizeof(Dirent{}.Ino))
   984  }
   985  
   986  func direntReclen(buf []byte) (uint64, bool) {
   987  	return readInt(buf, unsafe.Offsetof(Dirent{}.Reclen), unsafe.Sizeof(Dirent{}.Reclen))
   988  }
   989  
   990  func direntNamlen(buf []byte) (uint64, bool) {
   991  	reclen, ok := direntReclen(buf)
   992  	if !ok {
   993  		return 0, false
   994  	}
   995  	return reclen - uint64(unsafe.Offsetof(Dirent{}.Name)), true
   996  }
   997  
   998  //sys	mount(source string, target string, fstype string, flags uintptr, data *byte) (err error)
   999  
  1000  func Mount(source string, target string, fstype string, flags uintptr, data string) (err error) {
  1001  	// Certain file systems get rather angry and EINVAL if you give
  1002  	// them an empty string of data, rather than NULL.
  1003  	if data == "" {
  1004  		return mount(source, target, fstype, flags, nil)
  1005  	}
  1006  	datap, err := BytePtrFromString(data)
  1007  	if err != nil {
  1008  		return err
  1009  	}
  1010  	return mount(source, target, fstype, flags, datap)
  1011  }
  1012  
  1013  // Sendto
  1014  // Recvfrom
  1015  // Socketpair
  1016  
  1017  /*
  1018   * Direct access
  1019   */
  1020  //sys	Acct(path string) (err error)
  1021  //sys	Adjtimex(buf *Timex) (state int, err error)
  1022  //sys	Chdir(path string) (err error)
  1023  //sys	Chroot(path string) (err error)
  1024  //sys	Close(fd int) (err error)
  1025  //sys	Dup(oldfd int) (fd int, err error)
  1026  //sys	Dup3(oldfd int, newfd int, flags int) (err error)
  1027  //sysnb	EpollCreate1(flag int) (fd int, err error)
  1028  //sysnb	EpollCtl(epfd int, op int, fd int, event *EpollEvent) (err error)
  1029  //sys	Fallocate(fd int, mode uint32, off int64, len int64) (err error)
  1030  //sys	Fchdir(fd int) (err error)
  1031  //sys	Fchmod(fd int, mode uint32) (err error)
  1032  //sys	Fchownat(dirfd int, path string, uid int, gid int, flags int) (err error)
  1033  //sys	fcntl(fd int, cmd int, arg int) (val int, err error)
  1034  //sys	Fdatasync(fd int) (err error)
  1035  //sys	Flock(fd int, how int) (err error)
  1036  //sys	Fsync(fd int) (err error)
  1037  //sys	Getdents(fd int, buf []byte) (n int, err error) = SYS_GETDENTS64
  1038  //sysnb	Getpgid(pid int) (pgid int, err error)
  1039  
  1040  func Getpgrp() (pid int) {
  1041  	pid, _ = Getpgid(0)
  1042  	return
  1043  }
  1044  
  1045  //sysnb	Getpid() (pid int)
  1046  //sysnb	Getppid() (ppid int)
  1047  //sys	Getpriority(which int, who int) (prio int, err error)
  1048  //sysnb	Getrusage(who int, rusage *Rusage) (err error)
  1049  //sysnb	Gettid() (tid int)
  1050  //sys	Getxattr(path string, attr string, dest []byte) (sz int, err error)
  1051  //sys	InotifyAddWatch(fd int, pathname string, mask uint32) (watchdesc int, err error)
  1052  //sysnb	InotifyInit1(flags int) (fd int, err error)
  1053  //sysnb	InotifyRmWatch(fd int, watchdesc uint32) (success int, err error)
  1054  //sysnb	Kill(pid int, sig Signal) (err error)
  1055  //sys	Klogctl(typ int, buf []byte) (n int, err error) = SYS_SYSLOG
  1056  //sys	Listxattr(path string, dest []byte) (sz int, err error)
  1057  //sys	Mkdirat(dirfd int, path string, mode uint32) (err error)
  1058  //sys	Mknodat(dirfd int, path string, mode uint32, dev int) (err error)
  1059  //sys	Nanosleep(time *Timespec, leftover *Timespec) (err error)
  1060  //sys	PivotRoot(newroot string, putold string) (err error) = SYS_PIVOT_ROOT
  1061  //sysnb prlimit1(pid int, resource int, newlimit *Rlimit, old *Rlimit) (err error) = SYS_PRLIMIT64
  1062  //sys	read(fd int, p []byte) (n int, err error)
  1063  //sys	Removexattr(path string, attr string) (err error)
  1064  //sys	Setdomainname(p []byte) (err error)
  1065  //sys	Sethostname(p []byte) (err error)
  1066  //sysnb	Setpgid(pid int, pgid int) (err error)
  1067  //sysnb	Setsid() (pid int, err error)
  1068  //sysnb	Settimeofday(tv *Timeval) (err error)
  1069  
  1070  // Provided by runtime.syscall_runtime_doAllThreadsSyscall which stops the
  1071  // world and invokes the syscall on each OS thread. Once this function returns,
  1072  // all threads are in sync.
  1073  //
  1074  //go:uintptrescapes
  1075  func runtime_doAllThreadsSyscall(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err uintptr)
  1076  
  1077  // AllThreadsSyscall performs a syscall on each OS thread of the Go
  1078  // runtime. It first invokes the syscall on one thread. Should that
  1079  // invocation fail, it returns immediately with the error status.
  1080  // Otherwise, it invokes the syscall on all of the remaining threads
  1081  // in parallel. It will terminate the program if it observes any
  1082  // invoked syscall's return value differs from that of the first
  1083  // invocation.
  1084  //
  1085  // AllThreadsSyscall is intended for emulating simultaneous
  1086  // process-wide state changes that require consistently modifying
  1087  // per-thread state of the Go runtime.
  1088  //
  1089  // AllThreadsSyscall is unaware of any threads that are launched
  1090  // explicitly by cgo linked code, so the function always returns
  1091  // ENOTSUP in binaries that use cgo.
  1092  //
  1093  //go:uintptrescapes
  1094  func AllThreadsSyscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err Errno) {
  1095  	if cgo_libc_setegid != nil {
  1096  		return minus1, minus1, ENOTSUP
  1097  	}
  1098  	r1, r2, errno := runtime_doAllThreadsSyscall(trap, a1, a2, a3, 0, 0, 0)
  1099  	return r1, r2, Errno(errno)
  1100  }
  1101  
  1102  // AllThreadsSyscall6 is like AllThreadsSyscall, but extended to six
  1103  // arguments.
  1104  //
  1105  //go:uintptrescapes
  1106  func AllThreadsSyscall6(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err Errno) {
  1107  	if cgo_libc_setegid != nil {
  1108  		return minus1, minus1, ENOTSUP
  1109  	}
  1110  	r1, r2, errno := runtime_doAllThreadsSyscall(trap, a1, a2, a3, a4, a5, a6)
  1111  	return r1, r2, Errno(errno)
  1112  }
  1113  
  1114  // linked by runtime.cgocall.go
  1115  //
  1116  //go:uintptrescapes
  1117  func cgocaller(unsafe.Pointer, ...uintptr) uintptr
  1118  
  1119  var cgo_libc_setegid unsafe.Pointer // non-nil if cgo linked.
  1120  
  1121  const minus1 = ^uintptr(0)
  1122  
  1123  func Setegid(egid int) (err error) {
  1124  	if cgo_libc_setegid == nil {
  1125  		if _, _, e1 := AllThreadsSyscall(SYS_SETRESGID, minus1, uintptr(egid), minus1); e1 != 0 {
  1126  			err = errnoErr(e1)
  1127  		}
  1128  	} else if ret := cgocaller(cgo_libc_setegid, uintptr(egid)); ret != 0 {
  1129  		err = errnoErr(Errno(ret))
  1130  	}
  1131  	return
  1132  }
  1133  
  1134  var cgo_libc_seteuid unsafe.Pointer // non-nil if cgo linked.
  1135  
  1136  func Seteuid(euid int) (err error) {
  1137  	if cgo_libc_seteuid == nil {
  1138  		if _, _, e1 := AllThreadsSyscall(SYS_SETRESUID, minus1, uintptr(euid), minus1); e1 != 0 {
  1139  			err = errnoErr(e1)
  1140  		}
  1141  	} else if ret := cgocaller(cgo_libc_seteuid, uintptr(euid)); ret != 0 {
  1142  		err = errnoErr(Errno(ret))
  1143  	}
  1144  	return
  1145  }
  1146  
  1147  var cgo_libc_setgid unsafe.Pointer // non-nil if cgo linked.
  1148  
  1149  func Setgid(gid int) (err error) {
  1150  	if cgo_libc_setgid == nil {
  1151  		if _, _, e1 := AllThreadsSyscall(sys_SETGID, uintptr(gid), 0, 0); e1 != 0 {
  1152  			err = errnoErr(e1)
  1153  		}
  1154  	} else if ret := cgocaller(cgo_libc_setgid, uintptr(gid)); ret != 0 {
  1155  		err = errnoErr(Errno(ret))
  1156  	}
  1157  	return
  1158  }
  1159  
  1160  var cgo_libc_setregid unsafe.Pointer // non-nil if cgo linked.
  1161  
  1162  func Setregid(rgid, egid int) (err error) {
  1163  	if cgo_libc_setregid == nil {
  1164  		if _, _, e1 := AllThreadsSyscall(sys_SETREGID, uintptr(rgid), uintptr(egid), 0); e1 != 0 {
  1165  			err = errnoErr(e1)
  1166  		}
  1167  	} else if ret := cgocaller(cgo_libc_setregid, uintptr(rgid), uintptr(egid)); ret != 0 {
  1168  		err = errnoErr(Errno(ret))
  1169  	}
  1170  	return
  1171  }
  1172  
  1173  var cgo_libc_setresgid unsafe.Pointer // non-nil if cgo linked.
  1174  
  1175  func Setresgid(rgid, egid, sgid int) (err error) {
  1176  	if cgo_libc_setresgid == nil {
  1177  		if _, _, e1 := AllThreadsSyscall(sys_SETRESGID, uintptr(rgid), uintptr(egid), uintptr(sgid)); e1 != 0 {
  1178  			err = errnoErr(e1)
  1179  		}
  1180  	} else if ret := cgocaller(cgo_libc_setresgid, uintptr(rgid), uintptr(egid), uintptr(sgid)); ret != 0 {
  1181  		err = errnoErr(Errno(ret))
  1182  	}
  1183  	return
  1184  }
  1185  
  1186  var cgo_libc_setresuid unsafe.Pointer // non-nil if cgo linked.
  1187  
  1188  func Setresuid(ruid, euid, suid int) (err error) {
  1189  	if cgo_libc_setresuid == nil {
  1190  		if _, _, e1 := AllThreadsSyscall(sys_SETRESUID, uintptr(ruid), uintptr(euid), uintptr(suid)); e1 != 0 {
  1191  			err = errnoErr(e1)
  1192  		}
  1193  	} else if ret := cgocaller(cgo_libc_setresuid, uintptr(ruid), uintptr(euid), uintptr(suid)); ret != 0 {
  1194  		err = errnoErr(Errno(ret))
  1195  	}
  1196  	return
  1197  }
  1198  
  1199  var cgo_libc_setreuid unsafe.Pointer // non-nil if cgo linked.
  1200  
  1201  func Setreuid(ruid, euid int) (err error) {
  1202  	if cgo_libc_setreuid == nil {
  1203  		if _, _, e1 := AllThreadsSyscall(sys_SETREUID, uintptr(ruid), uintptr(euid), 0); e1 != 0 {
  1204  			err = errnoErr(e1)
  1205  		}
  1206  	} else if ret := cgocaller(cgo_libc_setreuid, uintptr(ruid), uintptr(euid)); ret != 0 {
  1207  		err = errnoErr(Errno(ret))
  1208  	}
  1209  	return
  1210  }
  1211  
  1212  var cgo_libc_setuid unsafe.Pointer // non-nil if cgo linked.
  1213  
  1214  func Setuid(uid int) (err error) {
  1215  	if cgo_libc_setuid == nil {
  1216  		if _, _, e1 := AllThreadsSyscall(sys_SETUID, uintptr(uid), 0, 0); e1 != 0 {
  1217  			err = errnoErr(e1)
  1218  		}
  1219  	} else if ret := cgocaller(cgo_libc_setuid, uintptr(uid)); ret != 0 {
  1220  		err = errnoErr(Errno(ret))
  1221  	}
  1222  	return
  1223  }
  1224  
  1225  //sys	Setpriority(which int, who int, prio int) (err error)
  1226  //sys	Setxattr(path string, attr string, data []byte, flags int) (err error)
  1227  //sys	Sync()
  1228  //sysnb	Sysinfo(info *Sysinfo_t) (err error)
  1229  //sys	Tee(rfd int, wfd int, len int, flags int) (n int64, err error)
  1230  //sysnb	Tgkill(tgid int, tid int, sig Signal) (err error)
  1231  //sysnb	Times(tms *Tms) (ticks uintptr, err error)
  1232  //sysnb	Umask(mask int) (oldmask int)
  1233  //sysnb	Uname(buf *Utsname) (err error)
  1234  //sys	Unmount(target string, flags int) (err error) = SYS_UMOUNT2
  1235  //sys	Unshare(flags int) (err error)
  1236  //sys	write(fd int, p []byte) (n int, err error)
  1237  //sys	exitThread(code int) (err error) = SYS_EXIT
  1238  //sys	readlen(fd int, p *byte, np int) (n int, err error) = SYS_READ
  1239  //sys	writelen(fd int, p *byte, np int) (n int, err error) = SYS_WRITE
  1240  
  1241  // mmap varies by architecture; see syscall_linux_*.go.
  1242  //sys	munmap(addr uintptr, length uintptr) (err error)
  1243  
  1244  var mapper = &mmapper{
  1245  	active: make(map[*byte][]byte),
  1246  	mmap:   mmap,
  1247  	munmap: munmap,
  1248  }
  1249  
  1250  func Mmap(fd int, offset int64, length int, prot int, flags int) (data []byte, err error) {
  1251  	return mapper.Mmap(fd, offset, length, prot, flags)
  1252  }
  1253  
  1254  func Munmap(b []byte) (err error) {
  1255  	return mapper.Munmap(b)
  1256  }
  1257  
  1258  //sys	Madvise(b []byte, advice int) (err error)
  1259  //sys	Mprotect(b []byte, prot int) (err error)
  1260  //sys	Mlock(b []byte) (err error)
  1261  //sys	Munlock(b []byte) (err error)
  1262  //sys	Mlockall(flags int) (err error)
  1263  //sys	Munlockall() (err error)
  1264  
  1265  // prlimit changes a resource limit. We use a single definition so that
  1266  // we can tell StartProcess to not restore the original NOFILE limit.
  1267  // This is unexported but can be called from x/sys/unix.
  1268  func prlimit(pid int, resource int, newlimit *Rlimit, old *Rlimit) (err error) {
  1269  	err = prlimit1(pid, resource, newlimit, old)
  1270  	if err == nil && newlimit != nil && resource == RLIMIT_NOFILE {
  1271  		origRlimitNofile.Store(Rlimit{0, 0})
  1272  	}
  1273  	return err
  1274  }
  1275  

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