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  	runtimesyscall "internal/runtime/syscall"
    17  	"runtime"
    18  	"unsafe"
    19  )
    20  
    21  // Pull in entersyscall/exitsyscall for Syscall/Syscall6.
    22  //
    23  // Note that this can't be a push linkname because the runtime already has a
    24  // nameless linkname to export to assembly here and in x/sys. Additionally,
    25  // entersyscall fetches the caller PC and SP and thus can't have a wrapper
    26  // inbetween.
    27  
    28  //go:linkname runtime_entersyscall runtime.entersyscall
    29  func runtime_entersyscall()
    30  
    31  //go:linkname runtime_exitsyscall runtime.exitsyscall
    32  func runtime_exitsyscall()
    33  
    34  // N.B. For the Syscall functions below:
    35  //
    36  // //go:uintptrkeepalive because the uintptr argument may be converted pointers
    37  // that need to be kept alive in the caller.
    38  //
    39  // //go:nosplit because stack copying does not account for uintptrkeepalive, so
    40  // the stack must not grow. Stack copying cannot blindly assume that all
    41  // uintptr arguments are pointers, because some values may look like pointers,
    42  // but not really be pointers, and adjusting their value would break the call.
    43  //
    44  // //go:norace, on RawSyscall, to avoid race instrumentation if RawSyscall is
    45  // called after fork, or from a signal handler.
    46  //
    47  // //go:linkname to ensure ABI wrappers are generated for external callers
    48  // (notably x/sys/unix assembly).
    49  
    50  //go:uintptrkeepalive
    51  //go:nosplit
    52  //go:norace
    53  //go:linkname RawSyscall
    54  func RawSyscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err Errno) {
    55  	return RawSyscall6(trap, a1, a2, a3, 0, 0, 0)
    56  }
    57  
    58  //go:uintptrkeepalive
    59  //go:nosplit
    60  //go:norace
    61  //go:linkname RawSyscall6
    62  func RawSyscall6(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err Errno) {
    63  	var errno uintptr
    64  	r1, r2, errno = runtimesyscall.Syscall6(trap, a1, a2, a3, a4, a5, a6)
    65  	err = Errno(errno)
    66  	return
    67  }
    68  
    69  //go:uintptrkeepalive
    70  //go:nosplit
    71  //go:linkname Syscall
    72  func Syscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err Errno) {
    73  	runtime_entersyscall()
    74  	// N.B. Calling RawSyscall here is unsafe with atomic coverage
    75  	// instrumentation and race mode.
    76  	//
    77  	// Coverage instrumentation will add a sync/atomic call to RawSyscall.
    78  	// Race mode will add race instrumentation to sync/atomic. Race
    79  	// instrumentation requires a P, which we no longer have.
    80  	//
    81  	// RawSyscall6 is fine because it is implemented in assembly and thus
    82  	// has no coverage instrumentation.
    83  	//
    84  	// This is typically not a problem in the runtime because cmd/go avoids
    85  	// adding coverage instrumentation to the runtime in race mode.
    86  	r1, r2, err = RawSyscall6(trap, a1, a2, a3, 0, 0, 0)
    87  	runtime_exitsyscall()
    88  	return
    89  }
    90  
    91  //go:uintptrkeepalive
    92  //go:nosplit
    93  //go:linkname Syscall6
    94  func Syscall6(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err Errno) {
    95  	runtime_entersyscall()
    96  	r1, r2, err = RawSyscall6(trap, a1, a2, a3, a4, a5, a6)
    97  	runtime_exitsyscall()
    98  	return
    99  }
   100  
   101  func rawSyscallNoError(trap, a1, a2, a3 uintptr) (r1, r2 uintptr)
   102  func rawVforkSyscall(trap, a1, a2, a3 uintptr) (r1 uintptr, err Errno)
   103  
   104  /*
   105   * Wrapped
   106   */
   107  
   108  func Access(path string, mode uint32) (err error) {
   109  	return Faccessat(_AT_FDCWD, path, mode, 0)
   110  }
   111  
   112  func Chmod(path string, mode uint32) (err error) {
   113  	return Fchmodat(_AT_FDCWD, path, mode, 0)
   114  }
   115  
   116  func Chown(path string, uid int, gid int) (err error) {
   117  	return Fchownat(_AT_FDCWD, path, uid, gid, 0)
   118  }
   119  
   120  func Creat(path string, mode uint32) (fd int, err error) {
   121  	return Open(path, O_CREAT|O_WRONLY|O_TRUNC, mode)
   122  }
   123  
   124  func EpollCreate(size int) (fd int, err error) {
   125  	if size <= 0 {
   126  		return -1, EINVAL
   127  	}
   128  	return EpollCreate1(0)
   129  }
   130  
   131  func isGroupMember(gid int) bool {
   132  	groups, err := Getgroups()
   133  	if err != nil {
   134  		return false
   135  	}
   136  
   137  	for _, g := range groups {
   138  		if g == gid {
   139  			return true
   140  		}
   141  	}
   142  	return false
   143  }
   144  
   145  func isCapDacOverrideSet() bool {
   146  	const _CAP_DAC_OVERRIDE = 1
   147  	var c caps
   148  	c.hdr.version = _LINUX_CAPABILITY_VERSION_3
   149  
   150  	_, _, err := RawSyscall(SYS_CAPGET, uintptr(unsafe.Pointer(&c.hdr)), uintptr(unsafe.Pointer(&c.data[0])), 0)
   151  
   152  	return err == 0 && c.data[0].effective&capToMask(_CAP_DAC_OVERRIDE) != 0
   153  }
   154  
   155  //sys	faccessat(dirfd int, path string, mode uint32) (err error)
   156  //sys	faccessat2(dirfd int, path string, mode uint32, flags int) (err error) = _SYS_faccessat2
   157  
   158  func Faccessat(dirfd int, path string, mode uint32, flags int) (err error) {
   159  	if flags == 0 {
   160  		return faccessat(dirfd, path, mode)
   161  	}
   162  
   163  	// Attempt to use the newer faccessat2, which supports flags directly,
   164  	// falling back if it doesn't exist.
   165  	//
   166  	// Don't attempt on Android, which does not allow faccessat2 through
   167  	// its seccomp policy [1] on any version of Android as of 2022-12-20.
   168  	//
   169  	// [1] https://cs.android.com/android/platform/superproject/+/master:bionic/libc/SECCOMP_BLOCKLIST_APP.TXT;l=4;drc=dbb8670dfdcc677f7e3b9262e93800fa14c4e417
   170  	if runtime.GOOS != "android" {
   171  		if err := faccessat2(dirfd, path, mode, flags); err != ENOSYS && err != EPERM {
   172  			return err
   173  		}
   174  	}
   175  
   176  	// The Linux kernel faccessat system call does not take any flags.
   177  	// The glibc faccessat implements the flags itself; see
   178  	// https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/unix/sysv/linux/faccessat.c;hb=HEAD
   179  	// Because people naturally expect syscall.Faccessat to act
   180  	// like C faccessat, we do the same.
   181  
   182  	if flags & ^(_AT_SYMLINK_NOFOLLOW|_AT_EACCESS) != 0 {
   183  		return EINVAL
   184  	}
   185  
   186  	var st Stat_t
   187  	if err := fstatat(dirfd, path, &st, flags&_AT_SYMLINK_NOFOLLOW); err != nil {
   188  		return err
   189  	}
   190  
   191  	mode &= 7
   192  	if mode == 0 {
   193  		return nil
   194  	}
   195  
   196  	// Fallback to checking permission bits.
   197  	var uid int
   198  	if flags&_AT_EACCESS != 0 {
   199  		uid = Geteuid()
   200  		if uid != 0 && isCapDacOverrideSet() {
   201  			// If CAP_DAC_OVERRIDE is set, file access check is
   202  			// done by the kernel in the same way as for root
   203  			// (see generic_permission() in the Linux sources).
   204  			uid = 0
   205  		}
   206  	} else {
   207  		uid = Getuid()
   208  	}
   209  
   210  	if uid == 0 {
   211  		if mode&1 == 0 {
   212  			// Root can read and write any file.
   213  			return nil
   214  		}
   215  		if st.Mode&0111 != 0 {
   216  			// Root can execute any file that anybody can execute.
   217  			return nil
   218  		}
   219  		return EACCES
   220  	}
   221  
   222  	var fmode uint32
   223  	if uint32(uid) == st.Uid {
   224  		fmode = (st.Mode >> 6) & 7
   225  	} else {
   226  		var gid int
   227  		if flags&_AT_EACCESS != 0 {
   228  			gid = Getegid()
   229  		} else {
   230  			gid = Getgid()
   231  		}
   232  
   233  		if uint32(gid) == st.Gid || isGroupMember(int(st.Gid)) {
   234  			fmode = (st.Mode >> 3) & 7
   235  		} else {
   236  			fmode = st.Mode & 7
   237  		}
   238  	}
   239  
   240  	if fmode&mode == mode {
   241  		return nil
   242  	}
   243  
   244  	return EACCES
   245  }
   246  
   247  //sys	fchmodat(dirfd int, path string, mode uint32) (err error)
   248  //sys	fchmodat2(dirfd int, path string, mode uint32, flags int) (err error) = _SYS_fchmodat2
   249  
   250  func Fchmodat(dirfd int, path string, mode uint32, flags int) error {
   251  	// Linux fchmodat doesn't support the flags parameter, but fchmodat2 does.
   252  	// Try fchmodat2 if flags are specified.
   253  	if flags != 0 {
   254  		err := fchmodat2(dirfd, path, mode, flags)
   255  		if err == ENOSYS {
   256  			// fchmodat2 isn't available. If the flags are known to be valid,
   257  			// return EOPNOTSUPP to indicate that fchmodat doesn't support them.
   258  			if flags&^(_AT_SYMLINK_NOFOLLOW|_AT_EMPTY_PATH) != 0 {
   259  				return EINVAL
   260  			} else if flags&(_AT_SYMLINK_NOFOLLOW|_AT_EMPTY_PATH) != 0 {
   261  				return EOPNOTSUPP
   262  			}
   263  		}
   264  		return err
   265  	}
   266  	return fchmodat(dirfd, path, mode)
   267  }
   268  
   269  //sys	linkat(olddirfd int, oldpath string, newdirfd int, newpath string, flags int) (err error)
   270  
   271  func Link(oldpath string, newpath string) (err error) {
   272  	return linkat(_AT_FDCWD, oldpath, _AT_FDCWD, newpath, 0)
   273  }
   274  
   275  func Mkdir(path string, mode uint32) (err error) {
   276  	return Mkdirat(_AT_FDCWD, path, mode)
   277  }
   278  
   279  func Mknod(path string, mode uint32, dev int) (err error) {
   280  	return Mknodat(_AT_FDCWD, path, mode, dev)
   281  }
   282  
   283  func Open(path string, mode int, perm uint32) (fd int, err error) {
   284  	return openat(_AT_FDCWD, path, mode|O_LARGEFILE, perm)
   285  }
   286  
   287  //sys	openat(dirfd int, path string, flags int, mode uint32) (fd int, err error)
   288  
   289  func Openat(dirfd int, path string, flags int, mode uint32) (fd int, err error) {
   290  	return openat(dirfd, path, flags|O_LARGEFILE, mode)
   291  }
   292  
   293  func Pipe(p []int) error {
   294  	return Pipe2(p, 0)
   295  }
   296  
   297  //sysnb pipe2(p *[2]_C_int, flags int) (err error)
   298  
   299  func Pipe2(p []int, flags int) error {
   300  	if len(p) != 2 {
   301  		return EINVAL
   302  	}
   303  	var pp [2]_C_int
   304  	err := pipe2(&pp, flags)
   305  	if err == nil {
   306  		p[0] = int(pp[0])
   307  		p[1] = int(pp[1])
   308  	}
   309  	return err
   310  }
   311  
   312  //sys	readlinkat(dirfd int, path string, buf []byte) (n int, err error)
   313  
   314  func Readlink(path string, buf []byte) (n int, err error) {
   315  	return readlinkat(_AT_FDCWD, path, buf)
   316  }
   317  
   318  func Rename(oldpath string, newpath string) (err error) {
   319  	return Renameat(_AT_FDCWD, oldpath, _AT_FDCWD, newpath)
   320  }
   321  
   322  func Rmdir(path string) error {
   323  	return unlinkat(_AT_FDCWD, path, _AT_REMOVEDIR)
   324  }
   325  
   326  //sys	symlinkat(oldpath string, newdirfd int, newpath string) (err error)
   327  
   328  func Symlink(oldpath string, newpath string) (err error) {
   329  	return symlinkat(oldpath, _AT_FDCWD, newpath)
   330  }
   331  
   332  func Unlink(path string) error {
   333  	return unlinkat(_AT_FDCWD, path, 0)
   334  }
   335  
   336  //sys	unlinkat(dirfd int, path string, flags int) (err error)
   337  
   338  func Unlinkat(dirfd int, path string) error {
   339  	return unlinkat(dirfd, path, 0)
   340  }
   341  
   342  func Utimes(path string, tv []Timeval) (err error) {
   343  	if len(tv) != 2 {
   344  		return EINVAL
   345  	}
   346  	return utimes(path, (*[2]Timeval)(unsafe.Pointer(&tv[0])))
   347  }
   348  
   349  //sys	utimensat(dirfd int, path string, times *[2]Timespec, flag int) (err error)
   350  
   351  func UtimesNano(path string, ts []Timespec) (err error) {
   352  	if len(ts) != 2 {
   353  		return EINVAL
   354  	}
   355  	return utimensat(_AT_FDCWD, path, (*[2]Timespec)(unsafe.Pointer(&ts[0])), 0)
   356  }
   357  
   358  func Futimesat(dirfd int, path string, tv []Timeval) (err error) {
   359  	if len(tv) != 2 {
   360  		return EINVAL
   361  	}
   362  	return futimesat(dirfd, path, (*[2]Timeval)(unsafe.Pointer(&tv[0])))
   363  }
   364  
   365  func Futimes(fd int, tv []Timeval) (err error) {
   366  	// Believe it or not, this is the best we can do on Linux
   367  	// (and is what glibc does).
   368  	return Utimes("/proc/self/fd/"+itoa.Itoa(fd), tv)
   369  }
   370  
   371  const ImplementsGetwd = true
   372  
   373  //sys	Getcwd(buf []byte) (n int, err error)
   374  
   375  func Getwd() (wd string, err error) {
   376  	var buf [PathMax]byte
   377  	n, err := Getcwd(buf[0:])
   378  	if err != nil {
   379  		return "", err
   380  	}
   381  	// Getcwd returns the number of bytes written to buf, including the NUL.
   382  	if n < 1 || n > len(buf) || buf[n-1] != 0 {
   383  		return "", EINVAL
   384  	}
   385  	// In some cases, Linux can return a path that starts with the
   386  	// "(unreachable)" prefix, which can potentially be a valid relative
   387  	// path. To work around that, return ENOENT if path is not absolute.
   388  	if buf[0] != '/' {
   389  		return "", ENOENT
   390  	}
   391  
   392  	return string(buf[0 : n-1]), nil
   393  }
   394  
   395  func Getgroups() (gids []int, err error) {
   396  	n, err := getgroups(0, nil)
   397  	if err != nil {
   398  		return nil, err
   399  	}
   400  	if n == 0 {
   401  		return nil, nil
   402  	}
   403  
   404  	// Sanity check group count. Max is 1<<16 on Linux.
   405  	if n < 0 || n > 1<<20 {
   406  		return nil, EINVAL
   407  	}
   408  
   409  	a := make([]_Gid_t, n)
   410  	n, err = getgroups(n, &a[0])
   411  	if err != nil {
   412  		return nil, err
   413  	}
   414  	gids = make([]int, n)
   415  	for i, v := range a[0:n] {
   416  		gids[i] = int(v)
   417  	}
   418  	return
   419  }
   420  
   421  var cgo_libc_setgroups unsafe.Pointer // non-nil if cgo linked.
   422  
   423  func Setgroups(gids []int) (err error) {
   424  	n := uintptr(len(gids))
   425  	if n == 0 {
   426  		if cgo_libc_setgroups == nil {
   427  			if _, _, e1 := AllThreadsSyscall(_SYS_setgroups, 0, 0, 0); e1 != 0 {
   428  				err = errnoErr(e1)
   429  			}
   430  			return
   431  		}
   432  		if ret := cgocaller(cgo_libc_setgroups, 0, 0); ret != 0 {
   433  			err = errnoErr(Errno(ret))
   434  		}
   435  		return
   436  	}
   437  
   438  	a := make([]_Gid_t, len(gids))
   439  	for i, v := range gids {
   440  		a[i] = _Gid_t(v)
   441  	}
   442  	if cgo_libc_setgroups == nil {
   443  		if _, _, e1 := AllThreadsSyscall(_SYS_setgroups, n, uintptr(unsafe.Pointer(&a[0])), 0); e1 != 0 {
   444  			err = errnoErr(e1)
   445  		}
   446  		return
   447  	}
   448  	if ret := cgocaller(cgo_libc_setgroups, n, uintptr(unsafe.Pointer(&a[0]))); ret != 0 {
   449  		err = errnoErr(Errno(ret))
   450  	}
   451  	return
   452  }
   453  
   454  type WaitStatus uint32
   455  
   456  // Wait status is 7 bits at bottom, either 0 (exited),
   457  // 0x7F (stopped), or a signal number that caused an exit.
   458  // The 0x80 bit is whether there was a core dump.
   459  // An extra number (exit code, signal causing a stop)
   460  // is in the high bits. At least that's the idea.
   461  // There are various irregularities. For example, the
   462  // "continued" status is 0xFFFF, distinguishing itself
   463  // from stopped via the core dump bit.
   464  
   465  const (
   466  	mask    = 0x7F
   467  	core    = 0x80
   468  	exited  = 0x00
   469  	stopped = 0x7F
   470  	shift   = 8
   471  )
   472  
   473  func (w WaitStatus) Exited() bool { return w&mask == exited }
   474  
   475  func (w WaitStatus) Signaled() bool { return w&mask != stopped && w&mask != exited }
   476  
   477  func (w WaitStatus) Stopped() bool { return w&0xFF == stopped }
   478  
   479  func (w WaitStatus) Continued() bool { return w == 0xFFFF }
   480  
   481  func (w WaitStatus) CoreDump() bool { return w.Signaled() && w&core != 0 }
   482  
   483  func (w WaitStatus) ExitStatus() int {
   484  	if !w.Exited() {
   485  		return -1
   486  	}
   487  	return int(w>>shift) & 0xFF
   488  }
   489  
   490  func (w WaitStatus) Signal() Signal {
   491  	if !w.Signaled() {
   492  		return -1
   493  	}
   494  	return Signal(w & mask)
   495  }
   496  
   497  func (w WaitStatus) StopSignal() Signal {
   498  	if !w.Stopped() {
   499  		return -1
   500  	}
   501  	return Signal(w>>shift) & 0xFF
   502  }
   503  
   504  func (w WaitStatus) TrapCause() int {
   505  	if w.StopSignal() != SIGTRAP {
   506  		return -1
   507  	}
   508  	return int(w>>shift) >> 8
   509  }
   510  
   511  //sys	wait4(pid int, wstatus *_C_int, options int, rusage *Rusage) (wpid int, err error)
   512  
   513  func Wait4(pid int, wstatus *WaitStatus, options int, rusage *Rusage) (wpid int, err error) {
   514  	var status _C_int
   515  	wpid, err = wait4(pid, &status, options, rusage)
   516  	if wstatus != nil {
   517  		*wstatus = WaitStatus(status)
   518  	}
   519  	return
   520  }
   521  
   522  func Mkfifo(path string, mode uint32) (err error) {
   523  	return Mknod(path, mode|S_IFIFO, 0)
   524  }
   525  
   526  func (sa *SockaddrInet4) sockaddr() (unsafe.Pointer, _Socklen, error) {
   527  	if sa.Port < 0 || sa.Port > 0xFFFF {
   528  		return nil, 0, EINVAL
   529  	}
   530  	sa.raw.Family = AF_INET
   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.Addr = sa.Addr
   535  	return unsafe.Pointer(&sa.raw), SizeofSockaddrInet4, nil
   536  }
   537  
   538  func (sa *SockaddrInet6) sockaddr() (unsafe.Pointer, _Socklen, error) {
   539  	if sa.Port < 0 || sa.Port > 0xFFFF {
   540  		return nil, 0, EINVAL
   541  	}
   542  	sa.raw.Family = AF_INET6
   543  	p := (*[2]byte)(unsafe.Pointer(&sa.raw.Port))
   544  	p[0] = byte(sa.Port >> 8)
   545  	p[1] = byte(sa.Port)
   546  	sa.raw.Scope_id = sa.ZoneId
   547  	sa.raw.Addr = sa.Addr
   548  	return unsafe.Pointer(&sa.raw), SizeofSockaddrInet6, nil
   549  }
   550  
   551  func (sa *SockaddrUnix) sockaddr() (unsafe.Pointer, _Socklen, error) {
   552  	name := sa.Name
   553  	n := len(name)
   554  	if n > len(sa.raw.Path) {
   555  		return nil, 0, EINVAL
   556  	}
   557  	if n == len(sa.raw.Path) && name[0] != '@' {
   558  		return nil, 0, EINVAL
   559  	}
   560  	sa.raw.Family = AF_UNIX
   561  	for i := 0; i < n; i++ {
   562  		sa.raw.Path[i] = int8(name[i])
   563  	}
   564  	// length is family (uint16), name, NUL.
   565  	sl := _Socklen(2)
   566  	if n > 0 {
   567  		sl += _Socklen(n) + 1
   568  	}
   569  	if sa.raw.Path[0] == '@' || (sa.raw.Path[0] == 0 && sl > 3) {
   570  		// Check sl > 3 so we don't change unnamed socket behavior.
   571  		sa.raw.Path[0] = 0
   572  		// Don't count trailing NUL for abstract address.
   573  		sl--
   574  	}
   575  
   576  	return unsafe.Pointer(&sa.raw), sl, nil
   577  }
   578  
   579  type SockaddrLinklayer struct {
   580  	Protocol uint16
   581  	Ifindex  int
   582  	Hatype   uint16
   583  	Pkttype  uint8
   584  	Halen    uint8
   585  	Addr     [8]byte
   586  	raw      RawSockaddrLinklayer
   587  }
   588  
   589  func (sa *SockaddrLinklayer) sockaddr() (unsafe.Pointer, _Socklen, error) {
   590  	if sa.Ifindex < 0 || sa.Ifindex > 0x7fffffff {
   591  		return nil, 0, EINVAL
   592  	}
   593  	sa.raw.Family = AF_PACKET
   594  	sa.raw.Protocol = sa.Protocol
   595  	sa.raw.Ifindex = int32(sa.Ifindex)
   596  	sa.raw.Hatype = sa.Hatype
   597  	sa.raw.Pkttype = sa.Pkttype
   598  	sa.raw.Halen = sa.Halen
   599  	sa.raw.Addr = sa.Addr
   600  	return unsafe.Pointer(&sa.raw), SizeofSockaddrLinklayer, nil
   601  }
   602  
   603  type SockaddrNetlink struct {
   604  	Family uint16
   605  	Pad    uint16
   606  	Pid    uint32
   607  	Groups uint32
   608  	raw    RawSockaddrNetlink
   609  }
   610  
   611  func (sa *SockaddrNetlink) sockaddr() (unsafe.Pointer, _Socklen, error) {
   612  	sa.raw.Family = AF_NETLINK
   613  	sa.raw.Pad = sa.Pad
   614  	sa.raw.Pid = sa.Pid
   615  	sa.raw.Groups = sa.Groups
   616  	return unsafe.Pointer(&sa.raw), SizeofSockaddrNetlink, nil
   617  }
   618  
   619  func anyToSockaddr(rsa *RawSockaddrAny) (Sockaddr, error) {
   620  	switch rsa.Addr.Family {
   621  	case AF_NETLINK:
   622  		pp := (*RawSockaddrNetlink)(unsafe.Pointer(rsa))
   623  		sa := new(SockaddrNetlink)
   624  		sa.Family = pp.Family
   625  		sa.Pad = pp.Pad
   626  		sa.Pid = pp.Pid
   627  		sa.Groups = pp.Groups
   628  		return sa, nil
   629  
   630  	case AF_PACKET:
   631  		pp := (*RawSockaddrLinklayer)(unsafe.Pointer(rsa))
   632  		sa := new(SockaddrLinklayer)
   633  		sa.Protocol = pp.Protocol
   634  		sa.Ifindex = int(pp.Ifindex)
   635  		sa.Hatype = pp.Hatype
   636  		sa.Pkttype = pp.Pkttype
   637  		sa.Halen = pp.Halen
   638  		sa.Addr = pp.Addr
   639  		return sa, nil
   640  
   641  	case AF_UNIX:
   642  		pp := (*RawSockaddrUnix)(unsafe.Pointer(rsa))
   643  		sa := new(SockaddrUnix)
   644  		if pp.Path[0] == 0 {
   645  			// "Abstract" Unix domain socket.
   646  			// Rewrite leading NUL as @ for textual display.
   647  			// (This is the standard convention.)
   648  			// Not friendly to overwrite in place,
   649  			// but the callers below don't care.
   650  			pp.Path[0] = '@'
   651  		}
   652  
   653  		// Assume path ends at NUL.
   654  		// This is not technically the Linux semantics for
   655  		// abstract Unix domain sockets--they are supposed
   656  		// to be uninterpreted fixed-size binary blobs--but
   657  		// everyone uses this convention.
   658  		n := 0
   659  		for n < len(pp.Path) && pp.Path[n] != 0 {
   660  			n++
   661  		}
   662  		sa.Name = string(unsafe.Slice((*byte)(unsafe.Pointer(&pp.Path[0])), n))
   663  		return sa, nil
   664  
   665  	case AF_INET:
   666  		pp := (*RawSockaddrInet4)(unsafe.Pointer(rsa))
   667  		sa := new(SockaddrInet4)
   668  		p := (*[2]byte)(unsafe.Pointer(&pp.Port))
   669  		sa.Port = int(p[0])<<8 + int(p[1])
   670  		sa.Addr = pp.Addr
   671  		return sa, nil
   672  
   673  	case AF_INET6:
   674  		pp := (*RawSockaddrInet6)(unsafe.Pointer(rsa))
   675  		sa := new(SockaddrInet6)
   676  		p := (*[2]byte)(unsafe.Pointer(&pp.Port))
   677  		sa.Port = int(p[0])<<8 + int(p[1])
   678  		sa.ZoneId = pp.Scope_id
   679  		sa.Addr = pp.Addr
   680  		return sa, nil
   681  	}
   682  	return nil, EAFNOSUPPORT
   683  }
   684  
   685  func Accept4(fd int, flags int) (nfd int, sa Sockaddr, err error) {
   686  	var rsa RawSockaddrAny
   687  	var len _Socklen = SizeofSockaddrAny
   688  	nfd, err = accept4(fd, &rsa, &len, flags)
   689  	if err != nil {
   690  		return
   691  	}
   692  	if len > SizeofSockaddrAny {
   693  		panic("RawSockaddrAny too small")
   694  	}
   695  	sa, err = anyToSockaddr(&rsa)
   696  	if err != nil {
   697  		Close(nfd)
   698  		nfd = 0
   699  	}
   700  	return
   701  }
   702  
   703  func Getsockname(fd int) (sa Sockaddr, err error) {
   704  	var rsa RawSockaddrAny
   705  	var len _Socklen = SizeofSockaddrAny
   706  	if err = getsockname(fd, &rsa, &len); err != nil {
   707  		return
   708  	}
   709  	return anyToSockaddr(&rsa)
   710  }
   711  
   712  func GetsockoptInet4Addr(fd, level, opt int) (value [4]byte, err error) {
   713  	vallen := _Socklen(4)
   714  	err = getsockopt(fd, level, opt, unsafe.Pointer(&value[0]), &vallen)
   715  	return value, err
   716  }
   717  
   718  func GetsockoptIPMreq(fd, level, opt int) (*IPMreq, error) {
   719  	var value IPMreq
   720  	vallen := _Socklen(SizeofIPMreq)
   721  	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
   722  	return &value, err
   723  }
   724  
   725  func GetsockoptIPMreqn(fd, level, opt int) (*IPMreqn, error) {
   726  	var value IPMreqn
   727  	vallen := _Socklen(SizeofIPMreqn)
   728  	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
   729  	return &value, err
   730  }
   731  
   732  func GetsockoptIPv6Mreq(fd, level, opt int) (*IPv6Mreq, error) {
   733  	var value IPv6Mreq
   734  	vallen := _Socklen(SizeofIPv6Mreq)
   735  	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
   736  	return &value, err
   737  }
   738  
   739  func GetsockoptIPv6MTUInfo(fd, level, opt int) (*IPv6MTUInfo, error) {
   740  	var value IPv6MTUInfo
   741  	vallen := _Socklen(SizeofIPv6MTUInfo)
   742  	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
   743  	return &value, err
   744  }
   745  
   746  func GetsockoptICMPv6Filter(fd, level, opt int) (*ICMPv6Filter, error) {
   747  	var value ICMPv6Filter
   748  	vallen := _Socklen(SizeofICMPv6Filter)
   749  	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
   750  	return &value, err
   751  }
   752  
   753  func GetsockoptUcred(fd, level, opt int) (*Ucred, error) {
   754  	var value Ucred
   755  	vallen := _Socklen(SizeofUcred)
   756  	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
   757  	return &value, err
   758  }
   759  
   760  func SetsockoptIPMreqn(fd, level, opt int, mreq *IPMreqn) (err error) {
   761  	return setsockopt(fd, level, opt, unsafe.Pointer(mreq), unsafe.Sizeof(*mreq))
   762  }
   763  
   764  func recvmsgRaw(fd int, p, oob []byte, flags int, rsa *RawSockaddrAny) (n, oobn int, recvflags int, err error) {
   765  	var msg Msghdr
   766  	msg.Name = (*byte)(unsafe.Pointer(rsa))
   767  	msg.Namelen = uint32(SizeofSockaddrAny)
   768  	var iov Iovec
   769  	if len(p) > 0 {
   770  		iov.Base = &p[0]
   771  		iov.SetLen(len(p))
   772  	}
   773  	var dummy byte
   774  	if len(oob) > 0 {
   775  		if len(p) == 0 {
   776  			var sockType int
   777  			sockType, err = GetsockoptInt(fd, SOL_SOCKET, SO_TYPE)
   778  			if err != nil {
   779  				return
   780  			}
   781  			// receive at least one normal byte
   782  			if sockType != SOCK_DGRAM {
   783  				iov.Base = &dummy
   784  				iov.SetLen(1)
   785  			}
   786  		}
   787  		msg.Control = &oob[0]
   788  		msg.SetControllen(len(oob))
   789  	}
   790  	msg.Iov = &iov
   791  	msg.Iovlen = 1
   792  	if n, err = recvmsg(fd, &msg, flags); err != nil {
   793  		return
   794  	}
   795  	oobn = int(msg.Controllen)
   796  	recvflags = int(msg.Flags)
   797  	return
   798  }
   799  
   800  func sendmsgN(fd int, p, oob []byte, ptr unsafe.Pointer, salen _Socklen, flags int) (n int, err error) {
   801  	var msg Msghdr
   802  	msg.Name = (*byte)(ptr)
   803  	msg.Namelen = uint32(salen)
   804  	var iov Iovec
   805  	if len(p) > 0 {
   806  		iov.Base = &p[0]
   807  		iov.SetLen(len(p))
   808  	}
   809  	var dummy byte
   810  	if len(oob) > 0 {
   811  		if len(p) == 0 {
   812  			var sockType int
   813  			sockType, err = GetsockoptInt(fd, SOL_SOCKET, SO_TYPE)
   814  			if err != nil {
   815  				return 0, err
   816  			}
   817  			// send at least one normal byte
   818  			if sockType != SOCK_DGRAM {
   819  				iov.Base = &dummy
   820  				iov.SetLen(1)
   821  			}
   822  		}
   823  		msg.Control = &oob[0]
   824  		msg.SetControllen(len(oob))
   825  	}
   826  	msg.Iov = &iov
   827  	msg.Iovlen = 1
   828  	if n, err = sendmsg(fd, &msg, flags); err != nil {
   829  		return 0, err
   830  	}
   831  	if len(oob) > 0 && len(p) == 0 {
   832  		n = 0
   833  	}
   834  	return n, nil
   835  }
   836  
   837  // BindToDevice binds the socket associated with fd to device.
   838  func BindToDevice(fd int, device string) (err error) {
   839  	return SetsockoptString(fd, SOL_SOCKET, SO_BINDTODEVICE, device)
   840  }
   841  
   842  //sys	ptrace(request int, pid int, addr uintptr, data uintptr) (err error)
   843  //sys	ptracePtr(request int, pid int, addr uintptr, data unsafe.Pointer) (err error) = SYS_PTRACE
   844  
   845  func ptracePeek(req int, pid int, addr uintptr, out []byte) (count int, err error) {
   846  	// The peek requests are machine-size oriented, so we wrap it
   847  	// to retrieve arbitrary-length data.
   848  
   849  	// The ptrace syscall differs from glibc's ptrace.
   850  	// Peeks returns the word in *data, not as the return value.
   851  
   852  	var buf [sizeofPtr]byte
   853  
   854  	// Leading edge. PEEKTEXT/PEEKDATA don't require aligned
   855  	// access (PEEKUSER warns that it might), but if we don't
   856  	// align our reads, we might straddle an unmapped page
   857  	// boundary and not get the bytes leading up to the page
   858  	// boundary.
   859  	n := 0
   860  	if addr%sizeofPtr != 0 {
   861  		err = ptracePtr(req, pid, addr-addr%sizeofPtr, unsafe.Pointer(&buf[0]))
   862  		if err != nil {
   863  			return 0, err
   864  		}
   865  		n += copy(out, buf[addr%sizeofPtr:])
   866  		out = out[n:]
   867  	}
   868  
   869  	// Remainder.
   870  	for len(out) > 0 {
   871  		// We use an internal buffer to guarantee alignment.
   872  		// It's not documented if this is necessary, but we're paranoid.
   873  		err = ptracePtr(req, pid, addr+uintptr(n), unsafe.Pointer(&buf[0]))
   874  		if err != nil {
   875  			return n, err
   876  		}
   877  		copied := copy(out, buf[0:])
   878  		n += copied
   879  		out = out[copied:]
   880  	}
   881  
   882  	return n, nil
   883  }
   884  
   885  func PtracePeekText(pid int, addr uintptr, out []byte) (count int, err error) {
   886  	return ptracePeek(PTRACE_PEEKTEXT, pid, addr, out)
   887  }
   888  
   889  func PtracePeekData(pid int, addr uintptr, out []byte) (count int, err error) {
   890  	return ptracePeek(PTRACE_PEEKDATA, pid, addr, out)
   891  }
   892  
   893  func ptracePoke(pokeReq int, peekReq int, pid int, addr uintptr, data []byte) (count int, err error) {
   894  	// As for ptracePeek, we need to align our accesses to deal
   895  	// with the possibility of straddling an invalid page.
   896  
   897  	// Leading edge.
   898  	n := 0
   899  	if addr%sizeofPtr != 0 {
   900  		var buf [sizeofPtr]byte
   901  		err = ptracePtr(peekReq, pid, addr-addr%sizeofPtr, unsafe.Pointer(&buf[0]))
   902  		if err != nil {
   903  			return 0, err
   904  		}
   905  		n += copy(buf[addr%sizeofPtr:], data)
   906  		word := *((*uintptr)(unsafe.Pointer(&buf[0])))
   907  		err = ptrace(pokeReq, pid, addr-addr%sizeofPtr, word)
   908  		if err != nil {
   909  			return 0, err
   910  		}
   911  		data = data[n:]
   912  	}
   913  
   914  	// Interior.
   915  	for len(data) > sizeofPtr {
   916  		word := *((*uintptr)(unsafe.Pointer(&data[0])))
   917  		err = ptrace(pokeReq, pid, addr+uintptr(n), word)
   918  		if err != nil {
   919  			return n, err
   920  		}
   921  		n += sizeofPtr
   922  		data = data[sizeofPtr:]
   923  	}
   924  
   925  	// Trailing edge.
   926  	if len(data) > 0 {
   927  		var buf [sizeofPtr]byte
   928  		err = ptracePtr(peekReq, pid, addr+uintptr(n), unsafe.Pointer(&buf[0]))
   929  		if err != nil {
   930  			return n, err
   931  		}
   932  		copy(buf[0:], data)
   933  		word := *((*uintptr)(unsafe.Pointer(&buf[0])))
   934  		err = ptrace(pokeReq, pid, addr+uintptr(n), word)
   935  		if err != nil {
   936  			return n, err
   937  		}
   938  		n += len(data)
   939  	}
   940  
   941  	return n, nil
   942  }
   943  
   944  func PtracePokeText(pid int, addr uintptr, data []byte) (count int, err error) {
   945  	return ptracePoke(PTRACE_POKETEXT, PTRACE_PEEKTEXT, pid, addr, data)
   946  }
   947  
   948  func PtracePokeData(pid int, addr uintptr, data []byte) (count int, err error) {
   949  	return ptracePoke(PTRACE_POKEDATA, PTRACE_PEEKDATA, pid, addr, data)
   950  }
   951  
   952  const (
   953  	_NT_PRSTATUS = 1
   954  )
   955  
   956  func PtraceGetRegs(pid int, regsout *PtraceRegs) (err error) {
   957  	var iov Iovec
   958  	iov.Base = (*byte)(unsafe.Pointer(regsout))
   959  	iov.SetLen(int(unsafe.Sizeof(*regsout)))
   960  	return ptracePtr(PTRACE_GETREGSET, pid, uintptr(_NT_PRSTATUS), unsafe.Pointer(&iov))
   961  }
   962  
   963  func PtraceSetRegs(pid int, regs *PtraceRegs) (err error) {
   964  	var iov Iovec
   965  	iov.Base = (*byte)(unsafe.Pointer(regs))
   966  	iov.SetLen(int(unsafe.Sizeof(*regs)))
   967  	return ptracePtr(PTRACE_SETREGSET, pid, uintptr(_NT_PRSTATUS), unsafe.Pointer(&iov))
   968  }
   969  
   970  func PtraceSetOptions(pid int, options int) (err error) {
   971  	return ptrace(PTRACE_SETOPTIONS, pid, 0, uintptr(options))
   972  }
   973  
   974  func PtraceGetEventMsg(pid int) (msg uint, err error) {
   975  	var data _C_long
   976  	err = ptracePtr(PTRACE_GETEVENTMSG, pid, 0, unsafe.Pointer(&data))
   977  	msg = uint(data)
   978  	return
   979  }
   980  
   981  func PtraceCont(pid int, signal int) (err error) {
   982  	return ptrace(PTRACE_CONT, pid, 0, uintptr(signal))
   983  }
   984  
   985  func PtraceSyscall(pid int, signal int) (err error) {
   986  	return ptrace(PTRACE_SYSCALL, pid, 0, uintptr(signal))
   987  }
   988  
   989  func PtraceSingleStep(pid int) (err error) { return ptrace(PTRACE_SINGLESTEP, pid, 0, 0) }
   990  
   991  func PtraceAttach(pid int) (err error) { return ptrace(PTRACE_ATTACH, pid, 0, 0) }
   992  
   993  func PtraceDetach(pid int) (err error) { return ptrace(PTRACE_DETACH, pid, 0, 0) }
   994  
   995  //sys	reboot(magic1 uint, magic2 uint, cmd int, arg string) (err error)
   996  
   997  func Reboot(cmd int) (err error) {
   998  	return reboot(LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2, cmd, "")
   999  }
  1000  
  1001  func ReadDirent(fd int, buf []byte) (n int, err error) {
  1002  	return Getdents(fd, buf)
  1003  }
  1004  
  1005  func direntIno(buf []byte) (uint64, bool) {
  1006  	return readInt(buf, unsafe.Offsetof(Dirent{}.Ino), unsafe.Sizeof(Dirent{}.Ino))
  1007  }
  1008  
  1009  func direntReclen(buf []byte) (uint64, bool) {
  1010  	return readInt(buf, unsafe.Offsetof(Dirent{}.Reclen), unsafe.Sizeof(Dirent{}.Reclen))
  1011  }
  1012  
  1013  func direntNamlen(buf []byte) (uint64, bool) {
  1014  	reclen, ok := direntReclen(buf)
  1015  	if !ok {
  1016  		return 0, false
  1017  	}
  1018  	return reclen - uint64(unsafe.Offsetof(Dirent{}.Name)), true
  1019  }
  1020  
  1021  //sys	mount(source string, target string, fstype string, flags uintptr, data *byte) (err error)
  1022  
  1023  func Mount(source string, target string, fstype string, flags uintptr, data string) (err error) {
  1024  	// Certain file systems get rather angry and EINVAL if you give
  1025  	// them an empty string of data, rather than NULL.
  1026  	if data == "" {
  1027  		return mount(source, target, fstype, flags, nil)
  1028  	}
  1029  	datap, err := BytePtrFromString(data)
  1030  	if err != nil {
  1031  		return err
  1032  	}
  1033  	return mount(source, target, fstype, flags, datap)
  1034  }
  1035  
  1036  // Sendto
  1037  // Recvfrom
  1038  // Socketpair
  1039  
  1040  /*
  1041   * Direct access
  1042   */
  1043  //sys	Acct(path string) (err error)
  1044  //sys	Adjtimex(buf *Timex) (state int, err error)
  1045  //sys	Chdir(path string) (err error)
  1046  //sys	Chroot(path string) (err error)
  1047  //sys	Close(fd int) (err error)
  1048  //sys	Dup(oldfd int) (fd int, err error)
  1049  //sys	Dup3(oldfd int, newfd int, flags int) (err error)
  1050  //sysnb	EpollCreate1(flag int) (fd int, err error)
  1051  //sysnb	EpollCtl(epfd int, op int, fd int, event *EpollEvent) (err error)
  1052  //sys	Fallocate(fd int, mode uint32, off int64, len int64) (err error)
  1053  //sys	Fchdir(fd int) (err error)
  1054  //sys	Fchmod(fd int, mode uint32) (err error)
  1055  //sys	Fchownat(dirfd int, path string, uid int, gid int, flags int) (err error)
  1056  //sys	fcntl(fd int, cmd int, arg int) (val int, err error)
  1057  //sys	Fdatasync(fd int) (err error)
  1058  //sys	Flock(fd int, how int) (err error)
  1059  //sys	Fsync(fd int) (err error)
  1060  //sys	Getdents(fd int, buf []byte) (n int, err error) = SYS_GETDENTS64
  1061  //sysnb	Getpgid(pid int) (pgid int, err error)
  1062  
  1063  func Getpgrp() (pid int) {
  1064  	pid, _ = Getpgid(0)
  1065  	return
  1066  }
  1067  
  1068  //sysnb	Getpid() (pid int)
  1069  //sysnb	Getppid() (ppid int)
  1070  //sys	Getpriority(which int, who int) (prio int, err error)
  1071  //sysnb	Getrusage(who int, rusage *Rusage) (err error)
  1072  //sysnb	Gettid() (tid int)
  1073  //sys	Getxattr(path string, attr string, dest []byte) (sz int, err error)
  1074  //sys	InotifyAddWatch(fd int, pathname string, mask uint32) (watchdesc int, err error)
  1075  //sysnb	InotifyInit1(flags int) (fd int, err error)
  1076  //sysnb	InotifyRmWatch(fd int, watchdesc uint32) (success int, err error)
  1077  //sysnb	Kill(pid int, sig Signal) (err error)
  1078  //sys	Klogctl(typ int, buf []byte) (n int, err error) = SYS_SYSLOG
  1079  //sys	Listxattr(path string, dest []byte) (sz int, err error)
  1080  //sys	Mkdirat(dirfd int, path string, mode uint32) (err error)
  1081  //sys	Mknodat(dirfd int, path string, mode uint32, dev int) (err error)
  1082  //sys	Nanosleep(time *Timespec, leftover *Timespec) (err error)
  1083  //sys	PivotRoot(newroot string, putold string) (err error) = SYS_PIVOT_ROOT
  1084  //sysnb prlimit1(pid int, resource int, newlimit *Rlimit, old *Rlimit) (err error) = SYS_PRLIMIT64
  1085  //sys	read(fd int, p []byte) (n int, err error)
  1086  //sys	Removexattr(path string, attr string) (err error)
  1087  //sys	Setdomainname(p []byte) (err error)
  1088  //sys	Sethostname(p []byte) (err error)
  1089  //sysnb	Setpgid(pid int, pgid int) (err error)
  1090  //sysnb	Setsid() (pid int, err error)
  1091  //sysnb	Settimeofday(tv *Timeval) (err error)
  1092  
  1093  // Provided by runtime.syscall_runtime_doAllThreadsSyscall which stops the
  1094  // world and invokes the syscall on each OS thread. Once this function returns,
  1095  // all threads are in sync.
  1096  //
  1097  //go:uintptrescapes
  1098  func runtime_doAllThreadsSyscall(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err uintptr)
  1099  
  1100  // AllThreadsSyscall performs a syscall on each OS thread of the Go
  1101  // runtime. It first invokes the syscall on one thread. Should that
  1102  // invocation fail, it returns immediately with the error status.
  1103  // Otherwise, it invokes the syscall on all of the remaining threads
  1104  // in parallel. It will terminate the program if it observes any
  1105  // invoked syscall's return value differs from that of the first
  1106  // invocation.
  1107  //
  1108  // AllThreadsSyscall is intended for emulating simultaneous
  1109  // process-wide state changes that require consistently modifying
  1110  // per-thread state of the Go runtime.
  1111  //
  1112  // AllThreadsSyscall is unaware of any threads that are launched
  1113  // explicitly by cgo linked code, so the function always returns
  1114  // [ENOTSUP] in binaries that use cgo.
  1115  //
  1116  //go:uintptrescapes
  1117  func AllThreadsSyscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err Errno) {
  1118  	if cgo_libc_setegid != nil {
  1119  		return minus1, minus1, ENOTSUP
  1120  	}
  1121  	r1, r2, errno := runtime_doAllThreadsSyscall(trap, a1, a2, a3, 0, 0, 0)
  1122  	return r1, r2, Errno(errno)
  1123  }
  1124  
  1125  // AllThreadsSyscall6 is like [AllThreadsSyscall], but extended to six
  1126  // arguments.
  1127  //
  1128  //go:uintptrescapes
  1129  func AllThreadsSyscall6(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err Errno) {
  1130  	if cgo_libc_setegid != nil {
  1131  		return minus1, minus1, ENOTSUP
  1132  	}
  1133  	r1, r2, errno := runtime_doAllThreadsSyscall(trap, a1, a2, a3, a4, a5, a6)
  1134  	return r1, r2, Errno(errno)
  1135  }
  1136  
  1137  // linked by runtime.cgocall.go
  1138  //
  1139  //go:uintptrescapes
  1140  func cgocaller(unsafe.Pointer, ...uintptr) uintptr
  1141  
  1142  var cgo_libc_setegid unsafe.Pointer // non-nil if cgo linked.
  1143  
  1144  const minus1 = ^uintptr(0)
  1145  
  1146  func Setegid(egid int) (err error) {
  1147  	if cgo_libc_setegid == nil {
  1148  		if _, _, e1 := AllThreadsSyscall(SYS_SETRESGID, minus1, uintptr(egid), minus1); e1 != 0 {
  1149  			err = errnoErr(e1)
  1150  		}
  1151  	} else if ret := cgocaller(cgo_libc_setegid, uintptr(egid)); ret != 0 {
  1152  		err = errnoErr(Errno(ret))
  1153  	}
  1154  	return
  1155  }
  1156  
  1157  var cgo_libc_seteuid unsafe.Pointer // non-nil if cgo linked.
  1158  
  1159  func Seteuid(euid int) (err error) {
  1160  	if cgo_libc_seteuid == nil {
  1161  		if _, _, e1 := AllThreadsSyscall(SYS_SETRESUID, minus1, uintptr(euid), minus1); e1 != 0 {
  1162  			err = errnoErr(e1)
  1163  		}
  1164  	} else if ret := cgocaller(cgo_libc_seteuid, uintptr(euid)); ret != 0 {
  1165  		err = errnoErr(Errno(ret))
  1166  	}
  1167  	return
  1168  }
  1169  
  1170  var cgo_libc_setgid unsafe.Pointer // non-nil if cgo linked.
  1171  
  1172  func Setgid(gid int) (err error) {
  1173  	if cgo_libc_setgid == nil {
  1174  		if _, _, e1 := AllThreadsSyscall(sys_SETGID, uintptr(gid), 0, 0); e1 != 0 {
  1175  			err = errnoErr(e1)
  1176  		}
  1177  	} else if ret := cgocaller(cgo_libc_setgid, uintptr(gid)); ret != 0 {
  1178  		err = errnoErr(Errno(ret))
  1179  	}
  1180  	return
  1181  }
  1182  
  1183  var cgo_libc_setregid unsafe.Pointer // non-nil if cgo linked.
  1184  
  1185  func Setregid(rgid, egid int) (err error) {
  1186  	if cgo_libc_setregid == nil {
  1187  		if _, _, e1 := AllThreadsSyscall(sys_SETREGID, uintptr(rgid), uintptr(egid), 0); e1 != 0 {
  1188  			err = errnoErr(e1)
  1189  		}
  1190  	} else if ret := cgocaller(cgo_libc_setregid, uintptr(rgid), uintptr(egid)); ret != 0 {
  1191  		err = errnoErr(Errno(ret))
  1192  	}
  1193  	return
  1194  }
  1195  
  1196  var cgo_libc_setresgid unsafe.Pointer // non-nil if cgo linked.
  1197  
  1198  func Setresgid(rgid, egid, sgid int) (err error) {
  1199  	if cgo_libc_setresgid == nil {
  1200  		if _, _, e1 := AllThreadsSyscall(sys_SETRESGID, uintptr(rgid), uintptr(egid), uintptr(sgid)); e1 != 0 {
  1201  			err = errnoErr(e1)
  1202  		}
  1203  	} else if ret := cgocaller(cgo_libc_setresgid, uintptr(rgid), uintptr(egid), uintptr(sgid)); ret != 0 {
  1204  		err = errnoErr(Errno(ret))
  1205  	}
  1206  	return
  1207  }
  1208  
  1209  var cgo_libc_setresuid unsafe.Pointer // non-nil if cgo linked.
  1210  
  1211  func Setresuid(ruid, euid, suid int) (err error) {
  1212  	if cgo_libc_setresuid == nil {
  1213  		if _, _, e1 := AllThreadsSyscall(sys_SETRESUID, uintptr(ruid), uintptr(euid), uintptr(suid)); e1 != 0 {
  1214  			err = errnoErr(e1)
  1215  		}
  1216  	} else if ret := cgocaller(cgo_libc_setresuid, uintptr(ruid), uintptr(euid), uintptr(suid)); ret != 0 {
  1217  		err = errnoErr(Errno(ret))
  1218  	}
  1219  	return
  1220  }
  1221  
  1222  var cgo_libc_setreuid unsafe.Pointer // non-nil if cgo linked.
  1223  
  1224  func Setreuid(ruid, euid int) (err error) {
  1225  	if cgo_libc_setreuid == nil {
  1226  		if _, _, e1 := AllThreadsSyscall(sys_SETREUID, uintptr(ruid), uintptr(euid), 0); e1 != 0 {
  1227  			err = errnoErr(e1)
  1228  		}
  1229  	} else if ret := cgocaller(cgo_libc_setreuid, uintptr(ruid), uintptr(euid)); ret != 0 {
  1230  		err = errnoErr(Errno(ret))
  1231  	}
  1232  	return
  1233  }
  1234  
  1235  var cgo_libc_setuid unsafe.Pointer // non-nil if cgo linked.
  1236  
  1237  func Setuid(uid int) (err error) {
  1238  	if cgo_libc_setuid == nil {
  1239  		if _, _, e1 := AllThreadsSyscall(sys_SETUID, uintptr(uid), 0, 0); e1 != 0 {
  1240  			err = errnoErr(e1)
  1241  		}
  1242  	} else if ret := cgocaller(cgo_libc_setuid, uintptr(uid)); ret != 0 {
  1243  		err = errnoErr(Errno(ret))
  1244  	}
  1245  	return
  1246  }
  1247  
  1248  //sys	Setpriority(which int, who int, prio int) (err error)
  1249  //sys	Setxattr(path string, attr string, data []byte, flags int) (err error)
  1250  //sys	Sync()
  1251  //sysnb	Sysinfo(info *Sysinfo_t) (err error)
  1252  //sys	Tee(rfd int, wfd int, len int, flags int) (n int64, err error)
  1253  //sysnb	Tgkill(tgid int, tid int, sig Signal) (err error)
  1254  //sysnb	Times(tms *Tms) (ticks uintptr, err error)
  1255  //sysnb	Umask(mask int) (oldmask int)
  1256  //sysnb	Uname(buf *Utsname) (err error)
  1257  //sys	Unmount(target string, flags int) (err error) = SYS_UMOUNT2
  1258  //sys	Unshare(flags int) (err error)
  1259  //sys	write(fd int, p []byte) (n int, err error)
  1260  //sys	exitThread(code int) (err error) = SYS_EXIT
  1261  //sys	readlen(fd int, p *byte, np int) (n int, err error) = SYS_READ
  1262  
  1263  // mmap varies by architecture; see syscall_linux_*.go.
  1264  //sys	munmap(addr uintptr, length uintptr) (err error)
  1265  
  1266  var mapper = &mmapper{
  1267  	active: make(map[*byte][]byte),
  1268  	mmap:   mmap,
  1269  	munmap: munmap,
  1270  }
  1271  
  1272  func Mmap(fd int, offset int64, length int, prot int, flags int) (data []byte, err error) {
  1273  	return mapper.Mmap(fd, offset, length, prot, flags)
  1274  }
  1275  
  1276  func Munmap(b []byte) (err error) {
  1277  	return mapper.Munmap(b)
  1278  }
  1279  
  1280  //sys	Madvise(b []byte, advice int) (err error)
  1281  //sys	Mprotect(b []byte, prot int) (err error)
  1282  //sys	Mlock(b []byte) (err error)
  1283  //sys	Munlock(b []byte) (err error)
  1284  //sys	Mlockall(flags int) (err error)
  1285  //sys	Munlockall() (err error)
  1286  
  1287  // prlimit changes a resource limit. We use a single definition so that
  1288  // we can tell StartProcess to not restore the original NOFILE limit.
  1289  //
  1290  // golang.org/x/sys linknames prlimit.
  1291  // Do not remove or change the type signature.
  1292  //
  1293  //go:linkname prlimit
  1294  func prlimit(pid int, resource int, newlimit *Rlimit, old *Rlimit) (err error) {
  1295  	err = prlimit1(pid, resource, newlimit, old)
  1296  	if err == nil && newlimit != nil && resource == RLIMIT_NOFILE && (pid == 0 || pid == Getpid()) {
  1297  		origRlimitNofile.Store(nil)
  1298  	}
  1299  	return err
  1300  }
  1301  

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