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

Documentation: golang.org/x/sys/unix

     1  // Copyright 2009 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  //go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris
     6  
     7  package unix
     8  
     9  import (
    10  	"bytes"
    11  	"sort"
    12  	"sync"
    13  	"syscall"
    14  	"unsafe"
    15  )
    16  
    17  var (
    18  	Stdin  = 0
    19  	Stdout = 1
    20  	Stderr = 2
    21  )
    22  
    23  // Do the interface allocations only once for common
    24  // Errno values.
    25  var (
    26  	errEAGAIN error = syscall.EAGAIN
    27  	errEINVAL error = syscall.EINVAL
    28  	errENOENT error = syscall.ENOENT
    29  )
    30  
    31  var (
    32  	signalNameMapOnce sync.Once
    33  	signalNameMap     map[string]syscall.Signal
    34  )
    35  
    36  // errnoErr returns common boxed Errno values, to prevent
    37  // allocations at runtime.
    38  func errnoErr(e syscall.Errno) error {
    39  	switch e {
    40  	case 0:
    41  		return nil
    42  	case EAGAIN:
    43  		return errEAGAIN
    44  	case EINVAL:
    45  		return errEINVAL
    46  	case ENOENT:
    47  		return errENOENT
    48  	}
    49  	return e
    50  }
    51  
    52  // ErrnoName returns the error name for error number e.
    53  func ErrnoName(e syscall.Errno) string {
    54  	i := sort.Search(len(errorList), func(i int) bool {
    55  		return errorList[i].num >= e
    56  	})
    57  	if i < len(errorList) && errorList[i].num == e {
    58  		return errorList[i].name
    59  	}
    60  	return ""
    61  }
    62  
    63  // SignalName returns the signal name for signal number s.
    64  func SignalName(s syscall.Signal) string {
    65  	i := sort.Search(len(signalList), func(i int) bool {
    66  		return signalList[i].num >= s
    67  	})
    68  	if i < len(signalList) && signalList[i].num == s {
    69  		return signalList[i].name
    70  	}
    71  	return ""
    72  }
    73  
    74  // SignalNum returns the syscall.Signal for signal named s,
    75  // or 0 if a signal with such name is not found.
    76  // The signal name should start with "SIG".
    77  func SignalNum(s string) syscall.Signal {
    78  	signalNameMapOnce.Do(func() {
    79  		signalNameMap = make(map[string]syscall.Signal, len(signalList))
    80  		for _, signal := range signalList {
    81  			signalNameMap[signal.name] = signal.num
    82  		}
    83  	})
    84  	return signalNameMap[s]
    85  }
    86  
    87  // clen returns the index of the first NULL byte in n or len(n) if n contains no NULL byte.
    88  func clen(n []byte) int {
    89  	i := bytes.IndexByte(n, 0)
    90  	if i == -1 {
    91  		i = len(n)
    92  	}
    93  	return i
    94  }
    95  
    96  // Mmap manager, for use by operating system-specific implementations.
    97  
    98  type mmapper struct {
    99  	sync.Mutex
   100  	active map[*byte][]byte // active mappings; key is last byte in mapping
   101  	mmap   func(addr, length uintptr, prot, flags, fd int, offset int64) (uintptr, error)
   102  	munmap func(addr uintptr, length uintptr) error
   103  }
   104  
   105  func (m *mmapper) Mmap(fd int, offset int64, length int, prot int, flags int) (data []byte, err error) {
   106  	if length <= 0 {
   107  		return nil, EINVAL
   108  	}
   109  
   110  	// Map the requested memory.
   111  	addr, errno := m.mmap(0, uintptr(length), prot, flags, fd, offset)
   112  	if errno != nil {
   113  		return nil, errno
   114  	}
   115  
   116  	// Use unsafe to convert addr into a []byte.
   117  	b := unsafe.Slice((*byte)(unsafe.Pointer(addr)), length)
   118  
   119  	// Register mapping in m and return it.
   120  	p := &b[cap(b)-1]
   121  	m.Lock()
   122  	defer m.Unlock()
   123  	m.active[p] = b
   124  	return b, nil
   125  }
   126  
   127  func (m *mmapper) Munmap(data []byte) (err error) {
   128  	if len(data) == 0 || len(data) != cap(data) {
   129  		return EINVAL
   130  	}
   131  
   132  	// Find the base of the mapping.
   133  	p := &data[cap(data)-1]
   134  	m.Lock()
   135  	defer m.Unlock()
   136  	b := m.active[p]
   137  	if b == nil || &b[0] != &data[0] {
   138  		return EINVAL
   139  	}
   140  
   141  	// Unmap the memory and update m.
   142  	if errno := m.munmap(uintptr(unsafe.Pointer(&b[0])), uintptr(len(b))); errno != nil {
   143  		return errno
   144  	}
   145  	delete(m.active, p)
   146  	return nil
   147  }
   148  
   149  func Mmap(fd int, offset int64, length int, prot int, flags int) (data []byte, err error) {
   150  	return mapper.Mmap(fd, offset, length, prot, flags)
   151  }
   152  
   153  func Munmap(b []byte) (err error) {
   154  	return mapper.Munmap(b)
   155  }
   156  
   157  func Read(fd int, p []byte) (n int, err error) {
   158  	n, err = read(fd, p)
   159  	if raceenabled {
   160  		if n > 0 {
   161  			raceWriteRange(unsafe.Pointer(&p[0]), n)
   162  		}
   163  		if err == nil {
   164  			raceAcquire(unsafe.Pointer(&ioSync))
   165  		}
   166  	}
   167  	return
   168  }
   169  
   170  func Write(fd int, p []byte) (n int, err error) {
   171  	if raceenabled {
   172  		raceReleaseMerge(unsafe.Pointer(&ioSync))
   173  	}
   174  	n, err = write(fd, p)
   175  	if raceenabled && n > 0 {
   176  		raceReadRange(unsafe.Pointer(&p[0]), n)
   177  	}
   178  	return
   179  }
   180  
   181  func Pread(fd int, p []byte, offset int64) (n int, err error) {
   182  	n, err = pread(fd, p, offset)
   183  	if raceenabled {
   184  		if n > 0 {
   185  			raceWriteRange(unsafe.Pointer(&p[0]), n)
   186  		}
   187  		if err == nil {
   188  			raceAcquire(unsafe.Pointer(&ioSync))
   189  		}
   190  	}
   191  	return
   192  }
   193  
   194  func Pwrite(fd int, p []byte, offset int64) (n int, err error) {
   195  	if raceenabled {
   196  		raceReleaseMerge(unsafe.Pointer(&ioSync))
   197  	}
   198  	n, err = pwrite(fd, p, offset)
   199  	if raceenabled && n > 0 {
   200  		raceReadRange(unsafe.Pointer(&p[0]), n)
   201  	}
   202  	return
   203  }
   204  
   205  // For testing: clients can set this flag to force
   206  // creation of IPv6 sockets to return EAFNOSUPPORT.
   207  var SocketDisableIPv6 bool
   208  
   209  // Sockaddr represents a socket address.
   210  type Sockaddr interface {
   211  	sockaddr() (ptr unsafe.Pointer, len _Socklen, err error) // lowercase; only we can define Sockaddrs
   212  }
   213  
   214  // SockaddrInet4 implements the Sockaddr interface for AF_INET type sockets.
   215  type SockaddrInet4 struct {
   216  	Port int
   217  	Addr [4]byte
   218  	raw  RawSockaddrInet4
   219  }
   220  
   221  // SockaddrInet6 implements the Sockaddr interface for AF_INET6 type sockets.
   222  type SockaddrInet6 struct {
   223  	Port   int
   224  	ZoneId uint32
   225  	Addr   [16]byte
   226  	raw    RawSockaddrInet6
   227  }
   228  
   229  // SockaddrUnix implements the Sockaddr interface for AF_UNIX type sockets.
   230  type SockaddrUnix struct {
   231  	Name string
   232  	raw  RawSockaddrUnix
   233  }
   234  
   235  func Bind(fd int, sa Sockaddr) (err error) {
   236  	ptr, n, err := sa.sockaddr()
   237  	if err != nil {
   238  		return err
   239  	}
   240  	return bind(fd, ptr, n)
   241  }
   242  
   243  func Connect(fd int, sa Sockaddr) (err error) {
   244  	ptr, n, err := sa.sockaddr()
   245  	if err != nil {
   246  		return err
   247  	}
   248  	return connect(fd, ptr, n)
   249  }
   250  
   251  func Getpeername(fd int) (sa Sockaddr, err error) {
   252  	var rsa RawSockaddrAny
   253  	var len _Socklen = SizeofSockaddrAny
   254  	if err = getpeername(fd, &rsa, &len); err != nil {
   255  		return
   256  	}
   257  	return anyToSockaddr(fd, &rsa)
   258  }
   259  
   260  func GetsockoptByte(fd, level, opt int) (value byte, err error) {
   261  	var n byte
   262  	vallen := _Socklen(1)
   263  	err = getsockopt(fd, level, opt, unsafe.Pointer(&n), &vallen)
   264  	return n, err
   265  }
   266  
   267  func GetsockoptInt(fd, level, opt int) (value int, err error) {
   268  	var n int32
   269  	vallen := _Socklen(4)
   270  	err = getsockopt(fd, level, opt, unsafe.Pointer(&n), &vallen)
   271  	return int(n), err
   272  }
   273  
   274  func GetsockoptInet4Addr(fd, level, opt int) (value [4]byte, err error) {
   275  	vallen := _Socklen(4)
   276  	err = getsockopt(fd, level, opt, unsafe.Pointer(&value[0]), &vallen)
   277  	return value, err
   278  }
   279  
   280  func GetsockoptIPMreq(fd, level, opt int) (*IPMreq, error) {
   281  	var value IPMreq
   282  	vallen := _Socklen(SizeofIPMreq)
   283  	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
   284  	return &value, err
   285  }
   286  
   287  func GetsockoptIPv6Mreq(fd, level, opt int) (*IPv6Mreq, error) {
   288  	var value IPv6Mreq
   289  	vallen := _Socklen(SizeofIPv6Mreq)
   290  	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
   291  	return &value, err
   292  }
   293  
   294  func GetsockoptIPv6MTUInfo(fd, level, opt int) (*IPv6MTUInfo, error) {
   295  	var value IPv6MTUInfo
   296  	vallen := _Socklen(SizeofIPv6MTUInfo)
   297  	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
   298  	return &value, err
   299  }
   300  
   301  func GetsockoptICMPv6Filter(fd, level, opt int) (*ICMPv6Filter, error) {
   302  	var value ICMPv6Filter
   303  	vallen := _Socklen(SizeofICMPv6Filter)
   304  	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
   305  	return &value, err
   306  }
   307  
   308  func GetsockoptLinger(fd, level, opt int) (*Linger, error) {
   309  	var linger Linger
   310  	vallen := _Socklen(SizeofLinger)
   311  	err := getsockopt(fd, level, opt, unsafe.Pointer(&linger), &vallen)
   312  	return &linger, err
   313  }
   314  
   315  func GetsockoptTimeval(fd, level, opt int) (*Timeval, error) {
   316  	var tv Timeval
   317  	vallen := _Socklen(unsafe.Sizeof(tv))
   318  	err := getsockopt(fd, level, opt, unsafe.Pointer(&tv), &vallen)
   319  	return &tv, err
   320  }
   321  
   322  func GetsockoptUint64(fd, level, opt int) (value uint64, err error) {
   323  	var n uint64
   324  	vallen := _Socklen(8)
   325  	err = getsockopt(fd, level, opt, unsafe.Pointer(&n), &vallen)
   326  	return n, err
   327  }
   328  
   329  func Recvfrom(fd int, p []byte, flags int) (n int, from Sockaddr, err error) {
   330  	var rsa RawSockaddrAny
   331  	var len _Socklen = SizeofSockaddrAny
   332  	if n, err = recvfrom(fd, p, flags, &rsa, &len); err != nil {
   333  		return
   334  	}
   335  	if rsa.Addr.Family != AF_UNSPEC {
   336  		from, err = anyToSockaddr(fd, &rsa)
   337  	}
   338  	return
   339  }
   340  
   341  // Recvmsg receives a message from a socket using the recvmsg system call. The
   342  // received non-control data will be written to p, and any "out of band"
   343  // control data will be written to oob. The flags are passed to recvmsg.
   344  //
   345  // The results are:
   346  //   - n is the number of non-control data bytes read into p
   347  //   - oobn is the number of control data bytes read into oob; this may be interpreted using [ParseSocketControlMessage]
   348  //   - recvflags is flags returned by recvmsg
   349  //   - from is the address of the sender
   350  //
   351  // If the underlying socket type is not SOCK_DGRAM, a received message
   352  // containing oob data and a single '\0' of non-control data is treated as if
   353  // the message contained only control data, i.e. n will be zero on return.
   354  func Recvmsg(fd int, p, oob []byte, flags int) (n, oobn int, recvflags int, from Sockaddr, err error) {
   355  	var iov [1]Iovec
   356  	if len(p) > 0 {
   357  		iov[0].Base = &p[0]
   358  		iov[0].SetLen(len(p))
   359  	}
   360  	var rsa RawSockaddrAny
   361  	n, oobn, recvflags, err = recvmsgRaw(fd, iov[:], oob, flags, &rsa)
   362  	// source address is only specified if the socket is unconnected
   363  	if rsa.Addr.Family != AF_UNSPEC {
   364  		from, err = anyToSockaddr(fd, &rsa)
   365  	}
   366  	return
   367  }
   368  
   369  // RecvmsgBuffers receives a message from a socket using the recvmsg system
   370  // call. This function is equivalent to Recvmsg, but non-control data read is
   371  // scattered into the buffers slices.
   372  func RecvmsgBuffers(fd int, buffers [][]byte, oob []byte, flags int) (n, oobn int, recvflags int, from Sockaddr, err error) {
   373  	iov := make([]Iovec, len(buffers))
   374  	for i := range buffers {
   375  		if len(buffers[i]) > 0 {
   376  			iov[i].Base = &buffers[i][0]
   377  			iov[i].SetLen(len(buffers[i]))
   378  		} else {
   379  			iov[i].Base = (*byte)(unsafe.Pointer(&_zero))
   380  		}
   381  	}
   382  	var rsa RawSockaddrAny
   383  	n, oobn, recvflags, err = recvmsgRaw(fd, iov, oob, flags, &rsa)
   384  	if err == nil && rsa.Addr.Family != AF_UNSPEC {
   385  		from, err = anyToSockaddr(fd, &rsa)
   386  	}
   387  	return
   388  }
   389  
   390  // Sendmsg sends a message on a socket to an address using the sendmsg system
   391  // call. This function is equivalent to SendmsgN, but does not return the
   392  // number of bytes actually sent.
   393  func Sendmsg(fd int, p, oob []byte, to Sockaddr, flags int) (err error) {
   394  	_, err = SendmsgN(fd, p, oob, to, flags)
   395  	return
   396  }
   397  
   398  // SendmsgN sends a message on a socket to an address using the sendmsg system
   399  // call. p contains the non-control data to send, and oob contains the "out of
   400  // band" control data. The flags are passed to sendmsg. The number of
   401  // non-control bytes actually written to the socket is returned.
   402  //
   403  // Some socket types do not support sending control data without accompanying
   404  // non-control data. If p is empty, and oob contains control data, and the
   405  // underlying socket type is not SOCK_DGRAM, p will be treated as containing a
   406  // single '\0' and the return value will indicate zero bytes sent.
   407  //
   408  // The Go function Recvmsg, if called with an empty p and a non-empty oob,
   409  // will read and ignore this additional '\0'.  If the message is received by
   410  // code that does not use Recvmsg, or that does not use Go at all, that code
   411  // will need to be written to expect and ignore the additional '\0'.
   412  //
   413  // If you need to send non-empty oob with p actually empty, and if the
   414  // underlying socket type supports it, you can do so via a raw system call as
   415  // follows:
   416  //
   417  //	msg := &unix.Msghdr{
   418  //	    Control: &oob[0],
   419  //	}
   420  //	msg.SetControllen(len(oob))
   421  //	n, _, errno := unix.Syscall(unix.SYS_SENDMSG, uintptr(fd), uintptr(unsafe.Pointer(msg)), flags)
   422  func SendmsgN(fd int, p, oob []byte, to Sockaddr, flags int) (n int, err error) {
   423  	var iov [1]Iovec
   424  	if len(p) > 0 {
   425  		iov[0].Base = &p[0]
   426  		iov[0].SetLen(len(p))
   427  	}
   428  	var ptr unsafe.Pointer
   429  	var salen _Socklen
   430  	if to != nil {
   431  		ptr, salen, err = to.sockaddr()
   432  		if err != nil {
   433  			return 0, err
   434  		}
   435  	}
   436  	return sendmsgN(fd, iov[:], oob, ptr, salen, flags)
   437  }
   438  
   439  // SendmsgBuffers sends a message on a socket to an address using the sendmsg
   440  // system call. This function is equivalent to SendmsgN, but the non-control
   441  // data is gathered from buffers.
   442  func SendmsgBuffers(fd int, buffers [][]byte, oob []byte, to Sockaddr, flags int) (n int, err error) {
   443  	iov := make([]Iovec, len(buffers))
   444  	for i := range buffers {
   445  		if len(buffers[i]) > 0 {
   446  			iov[i].Base = &buffers[i][0]
   447  			iov[i].SetLen(len(buffers[i]))
   448  		} else {
   449  			iov[i].Base = (*byte)(unsafe.Pointer(&_zero))
   450  		}
   451  	}
   452  	var ptr unsafe.Pointer
   453  	var salen _Socklen
   454  	if to != nil {
   455  		ptr, salen, err = to.sockaddr()
   456  		if err != nil {
   457  			return 0, err
   458  		}
   459  	}
   460  	return sendmsgN(fd, iov, oob, ptr, salen, flags)
   461  }
   462  
   463  func Send(s int, buf []byte, flags int) (err error) {
   464  	return sendto(s, buf, flags, nil, 0)
   465  }
   466  
   467  func Sendto(fd int, p []byte, flags int, to Sockaddr) (err error) {
   468  	var ptr unsafe.Pointer
   469  	var salen _Socklen
   470  	if to != nil {
   471  		ptr, salen, err = to.sockaddr()
   472  		if err != nil {
   473  			return err
   474  		}
   475  	}
   476  	return sendto(fd, p, flags, ptr, salen)
   477  }
   478  
   479  func SetsockoptByte(fd, level, opt int, value byte) (err error) {
   480  	return setsockopt(fd, level, opt, unsafe.Pointer(&value), 1)
   481  }
   482  
   483  func SetsockoptInt(fd, level, opt int, value int) (err error) {
   484  	var n = int32(value)
   485  	return setsockopt(fd, level, opt, unsafe.Pointer(&n), 4)
   486  }
   487  
   488  func SetsockoptInet4Addr(fd, level, opt int, value [4]byte) (err error) {
   489  	return setsockopt(fd, level, opt, unsafe.Pointer(&value[0]), 4)
   490  }
   491  
   492  func SetsockoptIPMreq(fd, level, opt int, mreq *IPMreq) (err error) {
   493  	return setsockopt(fd, level, opt, unsafe.Pointer(mreq), SizeofIPMreq)
   494  }
   495  
   496  func SetsockoptIPv6Mreq(fd, level, opt int, mreq *IPv6Mreq) (err error) {
   497  	return setsockopt(fd, level, opt, unsafe.Pointer(mreq), SizeofIPv6Mreq)
   498  }
   499  
   500  func SetsockoptICMPv6Filter(fd, level, opt int, filter *ICMPv6Filter) error {
   501  	return setsockopt(fd, level, opt, unsafe.Pointer(filter), SizeofICMPv6Filter)
   502  }
   503  
   504  func SetsockoptLinger(fd, level, opt int, l *Linger) (err error) {
   505  	return setsockopt(fd, level, opt, unsafe.Pointer(l), SizeofLinger)
   506  }
   507  
   508  func SetsockoptString(fd, level, opt int, s string) (err error) {
   509  	var p unsafe.Pointer
   510  	if len(s) > 0 {
   511  		p = unsafe.Pointer(&[]byte(s)[0])
   512  	}
   513  	return setsockopt(fd, level, opt, p, uintptr(len(s)))
   514  }
   515  
   516  func SetsockoptTimeval(fd, level, opt int, tv *Timeval) (err error) {
   517  	return setsockopt(fd, level, opt, unsafe.Pointer(tv), unsafe.Sizeof(*tv))
   518  }
   519  
   520  func SetsockoptUint64(fd, level, opt int, value uint64) (err error) {
   521  	return setsockopt(fd, level, opt, unsafe.Pointer(&value), 8)
   522  }
   523  
   524  func Socket(domain, typ, proto int) (fd int, err error) {
   525  	if domain == AF_INET6 && SocketDisableIPv6 {
   526  		return -1, EAFNOSUPPORT
   527  	}
   528  	fd, err = socket(domain, typ, proto)
   529  	return
   530  }
   531  
   532  func Socketpair(domain, typ, proto int) (fd [2]int, err error) {
   533  	var fdx [2]int32
   534  	err = socketpair(domain, typ, proto, &fdx)
   535  	if err == nil {
   536  		fd[0] = int(fdx[0])
   537  		fd[1] = int(fdx[1])
   538  	}
   539  	return
   540  }
   541  
   542  var ioSync int64
   543  
   544  func CloseOnExec(fd int) { fcntl(fd, F_SETFD, FD_CLOEXEC) }
   545  
   546  func SetNonblock(fd int, nonblocking bool) (err error) {
   547  	flag, err := fcntl(fd, F_GETFL, 0)
   548  	if err != nil {
   549  		return err
   550  	}
   551  	if (flag&O_NONBLOCK != 0) == nonblocking {
   552  		return nil
   553  	}
   554  	if nonblocking {
   555  		flag |= O_NONBLOCK
   556  	} else {
   557  		flag &= ^O_NONBLOCK
   558  	}
   559  	_, err = fcntl(fd, F_SETFL, flag)
   560  	return err
   561  }
   562  
   563  // Exec calls execve(2), which replaces the calling executable in the process
   564  // tree. argv0 should be the full path to an executable ("/bin/ls") and the
   565  // executable name should also be the first argument in argv (["ls", "-l"]).
   566  // envv are the environment variables that should be passed to the new
   567  // process (["USER=go", "PWD=/tmp"]).
   568  func Exec(argv0 string, argv []string, envv []string) error {
   569  	return syscall.Exec(argv0, argv, envv)
   570  }
   571  
   572  // Lutimes sets the access and modification times tv on path. If path refers to
   573  // a symlink, it is not dereferenced and the timestamps are set on the symlink.
   574  // If tv is nil, the access and modification times are set to the current time.
   575  // Otherwise tv must contain exactly 2 elements, with access time as the first
   576  // element and modification time as the second element.
   577  func Lutimes(path string, tv []Timeval) error {
   578  	if tv == nil {
   579  		return UtimesNanoAt(AT_FDCWD, path, nil, AT_SYMLINK_NOFOLLOW)
   580  	}
   581  	if len(tv) != 2 {
   582  		return EINVAL
   583  	}
   584  	ts := []Timespec{
   585  		NsecToTimespec(TimevalToNsec(tv[0])),
   586  		NsecToTimespec(TimevalToNsec(tv[1])),
   587  	}
   588  	return UtimesNanoAt(AT_FDCWD, path, ts, AT_SYMLINK_NOFOLLOW)
   589  }
   590  
   591  // emptyIovecs reports whether there are no bytes in the slice of Iovec.
   592  func emptyIovecs(iov []Iovec) bool {
   593  	for i := range iov {
   594  		if iov[i].Len > 0 {
   595  			return false
   596  		}
   597  	}
   598  	return true
   599  }
   600  
   601  // Setrlimit sets a resource limit.
   602  func Setrlimit(resource int, rlim *Rlimit) error {
   603  	// Just call the syscall version, because as of Go 1.21
   604  	// it will affect starting a new process.
   605  	return syscall.Setrlimit(resource, (*syscall.Rlimit)(rlim))
   606  }
   607  

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