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