Source file src/internal/poll/fd_windows.go

Documentation: internal/poll

     1  // Copyright 2017 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  package poll
     6  
     7  import (
     8  	"errors"
     9  	"internal/race"
    10  	"internal/syscall/windows"
    11  	"io"
    12  	"sync"
    13  	"syscall"
    14  	"unicode/utf16"
    15  	"unicode/utf8"
    16  	"unsafe"
    17  )
    18  
    19  var (
    20  	initErr error
    21  	ioSync  uint64
    22  )
    23  
    24  // This package uses the SetFileCompletionNotificationModes Windows
    25  // API to skip calling GetQueuedCompletionStatus if an IO operation
    26  // completes synchronously. There is a known bug where
    27  // SetFileCompletionNotificationModes crashes on some systems (see
    28  // https://support.microsoft.com/kb/2568167 for details).
    29  
    30  var useSetFileCompletionNotificationModes bool // determines is SetFileCompletionNotificationModes is present and safe to use
    31  
    32  // checkSetFileCompletionNotificationModes verifies that
    33  // SetFileCompletionNotificationModes Windows API is present
    34  // on the system and is safe to use.
    35  // See https://support.microsoft.com/kb/2568167 for details.
    36  func checkSetFileCompletionNotificationModes() {
    37  	err := syscall.LoadSetFileCompletionNotificationModes()
    38  	if err != nil {
    39  		return
    40  	}
    41  	protos := [2]int32{syscall.IPPROTO_TCP, 0}
    42  	var buf [32]syscall.WSAProtocolInfo
    43  	len := uint32(unsafe.Sizeof(buf))
    44  	n, err := syscall.WSAEnumProtocols(&protos[0], &buf[0], &len)
    45  	if err != nil {
    46  		return
    47  	}
    48  	for i := int32(0); i < n; i++ {
    49  		if buf[i].ServiceFlags1&syscall.XP1_IFS_HANDLES == 0 {
    50  			return
    51  		}
    52  	}
    53  	useSetFileCompletionNotificationModes = true
    54  }
    55  
    56  func init() {
    57  	var d syscall.WSAData
    58  	e := syscall.WSAStartup(uint32(0x202), &d)
    59  	if e != nil {
    60  		initErr = e
    61  	}
    62  	checkSetFileCompletionNotificationModes()
    63  }
    64  
    65  // operation contains superset of data necessary to perform all async IO.
    66  type operation struct {
    67  	// Used by IOCP interface, it must be first field
    68  	// of the struct, as our code rely on it.
    69  	o syscall.Overlapped
    70  
    71  	// fields used by runtime.netpoll
    72  	runtimeCtx uintptr
    73  	mode       int32
    74  	errno      int32
    75  	qty        uint32
    76  
    77  	// fields used only by net package
    78  	fd     *FD
    79  	buf    syscall.WSABuf
    80  	msg    windows.WSAMsg
    81  	sa     syscall.Sockaddr
    82  	rsa    *syscall.RawSockaddrAny
    83  	rsan   int32
    84  	handle syscall.Handle
    85  	flags  uint32
    86  	bufs   []syscall.WSABuf
    87  }
    88  
    89  func (o *operation) InitBuf(buf []byte) {
    90  	o.buf.Len = uint32(len(buf))
    91  	o.buf.Buf = nil
    92  	if len(buf) != 0 {
    93  		o.buf.Buf = &buf[0]
    94  	}
    95  }
    96  
    97  func (o *operation) InitBufs(buf *[][]byte) {
    98  	if o.bufs == nil {
    99  		o.bufs = make([]syscall.WSABuf, 0, len(*buf))
   100  	} else {
   101  		o.bufs = o.bufs[:0]
   102  	}
   103  	for _, b := range *buf {
   104  		if len(b) == 0 {
   105  			o.bufs = append(o.bufs, syscall.WSABuf{})
   106  			continue
   107  		}
   108  		for len(b) > maxRW {
   109  			o.bufs = append(o.bufs, syscall.WSABuf{Len: maxRW, Buf: &b[0]})
   110  			b = b[maxRW:]
   111  		}
   112  		if len(b) > 0 {
   113  			o.bufs = append(o.bufs, syscall.WSABuf{Len: uint32(len(b)), Buf: &b[0]})
   114  		}
   115  	}
   116  }
   117  
   118  // ClearBufs clears all pointers to Buffers parameter captured
   119  // by InitBufs, so it can be released by garbage collector.
   120  func (o *operation) ClearBufs() {
   121  	for i := range o.bufs {
   122  		o.bufs[i].Buf = nil
   123  	}
   124  	o.bufs = o.bufs[:0]
   125  }
   126  
   127  func (o *operation) InitMsg(p []byte, oob []byte) {
   128  	o.InitBuf(p)
   129  	o.msg.Buffers = &o.buf
   130  	o.msg.BufferCount = 1
   131  
   132  	o.msg.Name = nil
   133  	o.msg.Namelen = 0
   134  
   135  	o.msg.Flags = 0
   136  	o.msg.Control.Len = uint32(len(oob))
   137  	o.msg.Control.Buf = nil
   138  	if len(oob) != 0 {
   139  		o.msg.Control.Buf = &oob[0]
   140  	}
   141  }
   142  
   143  // execIO executes a single IO operation o. It submits and cancels
   144  // IO in the current thread for systems where Windows CancelIoEx API
   145  // is available. Alternatively, it passes the request onto
   146  // runtime netpoll and waits for completion or cancels request.
   147  func execIO(o *operation, submit func(o *operation) error) (int, error) {
   148  	if o.fd.pd.runtimeCtx == 0 {
   149  		return 0, errors.New("internal error: polling on unsupported descriptor type")
   150  	}
   151  
   152  	fd := o.fd
   153  	// Notify runtime netpoll about starting IO.
   154  	err := fd.pd.prepare(int(o.mode), fd.isFile)
   155  	if err != nil {
   156  		return 0, err
   157  	}
   158  	// Start IO.
   159  	err = submit(o)
   160  	switch err {
   161  	case nil:
   162  		// IO completed immediately
   163  		if o.fd.skipSyncNotif {
   164  			// No completion message will follow, so return immediately.
   165  			return int(o.qty), nil
   166  		}
   167  		// Need to get our completion message anyway.
   168  	case syscall.ERROR_IO_PENDING:
   169  		// IO started, and we have to wait for its completion.
   170  		err = nil
   171  	default:
   172  		return 0, err
   173  	}
   174  	// Wait for our request to complete.
   175  	err = fd.pd.wait(int(o.mode), fd.isFile)
   176  	if err == nil {
   177  		// All is good. Extract our IO results and return.
   178  		if o.errno != 0 {
   179  			err = syscall.Errno(o.errno)
   180  			// More data available. Return back the size of received data.
   181  			if err == syscall.ERROR_MORE_DATA || err == windows.WSAEMSGSIZE {
   182  				return int(o.qty), err
   183  			}
   184  			return 0, err
   185  		}
   186  		return int(o.qty), nil
   187  	}
   188  	// IO is interrupted by "close" or "timeout"
   189  	netpollErr := err
   190  	switch netpollErr {
   191  	case ErrNetClosing, ErrFileClosing, ErrDeadlineExceeded:
   192  		// will deal with those.
   193  	default:
   194  		panic("unexpected runtime.netpoll error: " + netpollErr.Error())
   195  	}
   196  	// Cancel our request.
   197  	err = syscall.CancelIoEx(fd.Sysfd, &o.o)
   198  	// Assuming ERROR_NOT_FOUND is returned, if IO is completed.
   199  	if err != nil && err != syscall.ERROR_NOT_FOUND {
   200  		// TODO(brainman): maybe do something else, but panic.
   201  		panic(err)
   202  	}
   203  	// Wait for cancellation to complete.
   204  	fd.pd.waitCanceled(int(o.mode))
   205  	if o.errno != 0 {
   206  		err = syscall.Errno(o.errno)
   207  		if err == syscall.ERROR_OPERATION_ABORTED { // IO Canceled
   208  			err = netpollErr
   209  		}
   210  		return 0, err
   211  	}
   212  	// We issued a cancellation request. But, it seems, IO operation succeeded
   213  	// before the cancellation request run. We need to treat the IO operation as
   214  	// succeeded (the bytes are actually sent/recv from network).
   215  	return int(o.qty), nil
   216  }
   217  
   218  // FD is a file descriptor. The net and os packages embed this type in
   219  // a larger type representing a network connection or OS file.
   220  type FD struct {
   221  	// Lock sysfd and serialize access to Read and Write methods.
   222  	fdmu fdMutex
   223  
   224  	// System file descriptor. Immutable until Close.
   225  	Sysfd syscall.Handle
   226  
   227  	// Read operation.
   228  	rop operation
   229  	// Write operation.
   230  	wop operation
   231  
   232  	// I/O poller.
   233  	pd pollDesc
   234  
   235  	// Used to implement pread/pwrite.
   236  	l sync.Mutex
   237  
   238  	// For console I/O.
   239  	lastbits       []byte   // first few bytes of the last incomplete rune in last write
   240  	readuint16     []uint16 // buffer to hold uint16s obtained with ReadConsole
   241  	readbyte       []byte   // buffer to hold decoding of readuint16 from utf16 to utf8
   242  	readbyteOffset int      // readbyte[readOffset:] is yet to be consumed with file.Read
   243  
   244  	// Semaphore signaled when file is closed.
   245  	csema uint32
   246  
   247  	skipSyncNotif bool
   248  
   249  	// Whether this is a streaming descriptor, as opposed to a
   250  	// packet-based descriptor like a UDP socket.
   251  	IsStream bool
   252  
   253  	// Whether a zero byte read indicates EOF. This is false for a
   254  	// message based socket connection.
   255  	ZeroReadIsEOF bool
   256  
   257  	// Whether this is a file rather than a network socket.
   258  	isFile bool
   259  
   260  	// The kind of this file.
   261  	kind fileKind
   262  }
   263  
   264  // fileKind describes the kind of file.
   265  type fileKind byte
   266  
   267  const (
   268  	kindNet fileKind = iota
   269  	kindFile
   270  	kindConsole
   271  	kindDir
   272  	kindPipe
   273  )
   274  
   275  // logInitFD is set by tests to enable file descriptor initialization logging.
   276  var logInitFD func(net string, fd *FD, err error)
   277  
   278  // Init initializes the FD. The Sysfd field should already be set.
   279  // This can be called multiple times on a single FD.
   280  // The net argument is a network name from the net package (e.g., "tcp"),
   281  // or "file" or "console" or "dir".
   282  // Set pollable to true if fd should be managed by runtime netpoll.
   283  func (fd *FD) Init(net string, pollable bool) (string, error) {
   284  	if initErr != nil {
   285  		return "", initErr
   286  	}
   287  
   288  	switch net {
   289  	case "file":
   290  		fd.kind = kindFile
   291  	case "console":
   292  		fd.kind = kindConsole
   293  	case "dir":
   294  		fd.kind = kindDir
   295  	case "pipe":
   296  		fd.kind = kindPipe
   297  	case "tcp", "tcp4", "tcp6",
   298  		"udp", "udp4", "udp6",
   299  		"ip", "ip4", "ip6",
   300  		"unix", "unixgram", "unixpacket":
   301  		fd.kind = kindNet
   302  	default:
   303  		return "", errors.New("internal error: unknown network type " + net)
   304  	}
   305  	fd.isFile = fd.kind != kindNet
   306  
   307  	var err error
   308  	if pollable {
   309  		// Only call init for a network socket.
   310  		// This means that we don't add files to the runtime poller.
   311  		// Adding files to the runtime poller can confuse matters
   312  		// if the user is doing their own overlapped I/O.
   313  		// See issue #21172.
   314  		//
   315  		// In general the code below avoids calling the execIO
   316  		// function for non-network sockets. If some method does
   317  		// somehow call execIO, then execIO, and therefore the
   318  		// calling method, will return an error, because
   319  		// fd.pd.runtimeCtx will be 0.
   320  		err = fd.pd.init(fd)
   321  	}
   322  	if logInitFD != nil {
   323  		logInitFD(net, fd, err)
   324  	}
   325  	if err != nil {
   326  		return "", err
   327  	}
   328  	if pollable && useSetFileCompletionNotificationModes {
   329  		// We do not use events, so we can skip them always.
   330  		flags := uint8(syscall.FILE_SKIP_SET_EVENT_ON_HANDLE)
   331  		// It's not safe to skip completion notifications for UDP:
   332  		// https://docs.microsoft.com/en-us/archive/blogs/winserverperformance/designing-applications-for-high-performance-part-iii
   333  		if net == "tcp" {
   334  			flags |= syscall.FILE_SKIP_COMPLETION_PORT_ON_SUCCESS
   335  		}
   336  		err := syscall.SetFileCompletionNotificationModes(fd.Sysfd, flags)
   337  		if err == nil && flags&syscall.FILE_SKIP_COMPLETION_PORT_ON_SUCCESS != 0 {
   338  			fd.skipSyncNotif = true
   339  		}
   340  	}
   341  	// Disable SIO_UDP_CONNRESET behavior.
   342  	// http://support.microsoft.com/kb/263823
   343  	switch net {
   344  	case "udp", "udp4", "udp6":
   345  		ret := uint32(0)
   346  		flag := uint32(0)
   347  		size := uint32(unsafe.Sizeof(flag))
   348  		err := syscall.WSAIoctl(fd.Sysfd, syscall.SIO_UDP_CONNRESET, (*byte)(unsafe.Pointer(&flag)), size, nil, 0, &ret, nil, 0)
   349  		if err != nil {
   350  			return "wsaioctl", err
   351  		}
   352  	}
   353  	fd.rop.mode = 'r'
   354  	fd.wop.mode = 'w'
   355  	fd.rop.fd = fd
   356  	fd.wop.fd = fd
   357  	fd.rop.runtimeCtx = fd.pd.runtimeCtx
   358  	fd.wop.runtimeCtx = fd.pd.runtimeCtx
   359  	return "", nil
   360  }
   361  
   362  func (fd *FD) destroy() error {
   363  	if fd.Sysfd == syscall.InvalidHandle {
   364  		return syscall.EINVAL
   365  	}
   366  	// Poller may want to unregister fd in readiness notification mechanism,
   367  	// so this must be executed before fd.CloseFunc.
   368  	fd.pd.close()
   369  	var err error
   370  	switch fd.kind {
   371  	case kindNet:
   372  		// The net package uses the CloseFunc variable for testing.
   373  		err = CloseFunc(fd.Sysfd)
   374  	case kindDir:
   375  		err = syscall.FindClose(fd.Sysfd)
   376  	default:
   377  		err = syscall.CloseHandle(fd.Sysfd)
   378  	}
   379  	fd.Sysfd = syscall.InvalidHandle
   380  	runtime_Semrelease(&fd.csema)
   381  	return err
   382  }
   383  
   384  // Close closes the FD. The underlying file descriptor is closed by
   385  // the destroy method when there are no remaining references.
   386  func (fd *FD) Close() error {
   387  	if !fd.fdmu.increfAndClose() {
   388  		return errClosing(fd.isFile)
   389  	}
   390  	if fd.kind == kindPipe {
   391  		syscall.CancelIoEx(fd.Sysfd, nil)
   392  	}
   393  	// unblock pending reader and writer
   394  	fd.pd.evict()
   395  	err := fd.decref()
   396  	// Wait until the descriptor is closed. If this was the only
   397  	// reference, it is already closed.
   398  	runtime_Semacquire(&fd.csema)
   399  	return err
   400  }
   401  
   402  // Windows ReadFile and WSARecv use DWORD (uint32) parameter to pass buffer length.
   403  // This prevents us reading blocks larger than 4GB.
   404  // See golang.org/issue/26923.
   405  const maxRW = 1 << 30 // 1GB is large enough and keeps subsequent reads aligned
   406  
   407  // Read implements io.Reader.
   408  func (fd *FD) Read(buf []byte) (int, error) {
   409  	if err := fd.readLock(); err != nil {
   410  		return 0, err
   411  	}
   412  	defer fd.readUnlock()
   413  
   414  	if len(buf) > maxRW {
   415  		buf = buf[:maxRW]
   416  	}
   417  
   418  	var n int
   419  	var err error
   420  	if fd.isFile {
   421  		fd.l.Lock()
   422  		defer fd.l.Unlock()
   423  		switch fd.kind {
   424  		case kindConsole:
   425  			n, err = fd.readConsole(buf)
   426  		default:
   427  			n, err = syscall.Read(fd.Sysfd, buf)
   428  			if fd.kind == kindPipe && err == syscall.ERROR_OPERATION_ABORTED {
   429  				// Close uses CancelIoEx to interrupt concurrent I/O for pipes.
   430  				// If the fd is a pipe and the Read was interrupted by CancelIoEx,
   431  				// we assume it is interrupted by Close.
   432  				err = ErrFileClosing
   433  			}
   434  		}
   435  		if err != nil {
   436  			n = 0
   437  		}
   438  	} else {
   439  		o := &fd.rop
   440  		o.InitBuf(buf)
   441  		n, err = execIO(o, func(o *operation) error {
   442  			return syscall.WSARecv(o.fd.Sysfd, &o.buf, 1, &o.qty, &o.flags, &o.o, nil)
   443  		})
   444  		if race.Enabled {
   445  			race.Acquire(unsafe.Pointer(&ioSync))
   446  		}
   447  	}
   448  	if len(buf) != 0 {
   449  		err = fd.eofError(n, err)
   450  	}
   451  	return n, err
   452  }
   453  
   454  var ReadConsole = syscall.ReadConsole // changed for testing
   455  
   456  // readConsole reads utf16 characters from console File,
   457  // encodes them into utf8 and stores them in buffer b.
   458  // It returns the number of utf8 bytes read and an error, if any.
   459  func (fd *FD) readConsole(b []byte) (int, error) {
   460  	if len(b) == 0 {
   461  		return 0, nil
   462  	}
   463  
   464  	if fd.readuint16 == nil {
   465  		// Note: syscall.ReadConsole fails for very large buffers.
   466  		// The limit is somewhere around (but not exactly) 16384.
   467  		// Stay well below.
   468  		fd.readuint16 = make([]uint16, 0, 10000)
   469  		fd.readbyte = make([]byte, 0, 4*cap(fd.readuint16))
   470  	}
   471  
   472  	for fd.readbyteOffset >= len(fd.readbyte) {
   473  		n := cap(fd.readuint16) - len(fd.readuint16)
   474  		if n > len(b) {
   475  			n = len(b)
   476  		}
   477  		var nw uint32
   478  		err := ReadConsole(fd.Sysfd, &fd.readuint16[:len(fd.readuint16)+1][len(fd.readuint16)], uint32(n), &nw, nil)
   479  		if err != nil {
   480  			return 0, err
   481  		}
   482  		uint16s := fd.readuint16[:len(fd.readuint16)+int(nw)]
   483  		fd.readuint16 = fd.readuint16[:0]
   484  		buf := fd.readbyte[:0]
   485  		for i := 0; i < len(uint16s); i++ {
   486  			r := rune(uint16s[i])
   487  			if utf16.IsSurrogate(r) {
   488  				if i+1 == len(uint16s) {
   489  					if nw > 0 {
   490  						// Save half surrogate pair for next time.
   491  						fd.readuint16 = fd.readuint16[:1]
   492  						fd.readuint16[0] = uint16(r)
   493  						break
   494  					}
   495  					r = utf8.RuneError
   496  				} else {
   497  					r = utf16.DecodeRune(r, rune(uint16s[i+1]))
   498  					if r != utf8.RuneError {
   499  						i++
   500  					}
   501  				}
   502  			}
   503  			n := utf8.EncodeRune(buf[len(buf):cap(buf)], r)
   504  			buf = buf[:len(buf)+n]
   505  		}
   506  		fd.readbyte = buf
   507  		fd.readbyteOffset = 0
   508  		if nw == 0 {
   509  			break
   510  		}
   511  	}
   512  
   513  	src := fd.readbyte[fd.readbyteOffset:]
   514  	var i int
   515  	for i = 0; i < len(src) && i < len(b); i++ {
   516  		x := src[i]
   517  		if x == 0x1A { // Ctrl-Z
   518  			if i == 0 {
   519  				fd.readbyteOffset++
   520  			}
   521  			break
   522  		}
   523  		b[i] = x
   524  	}
   525  	fd.readbyteOffset += i
   526  	return i, nil
   527  }
   528  
   529  // Pread emulates the Unix pread system call.
   530  func (fd *FD) Pread(b []byte, off int64) (int, error) {
   531  	// Call incref, not readLock, because since pread specifies the
   532  	// offset it is independent from other reads.
   533  	if err := fd.incref(); err != nil {
   534  		return 0, err
   535  	}
   536  	defer fd.decref()
   537  
   538  	if len(b) > maxRW {
   539  		b = b[:maxRW]
   540  	}
   541  
   542  	fd.l.Lock()
   543  	defer fd.l.Unlock()
   544  	curoffset, e := syscall.Seek(fd.Sysfd, 0, io.SeekCurrent)
   545  	if e != nil {
   546  		return 0, e
   547  	}
   548  	defer syscall.Seek(fd.Sysfd, curoffset, io.SeekStart)
   549  	o := syscall.Overlapped{
   550  		OffsetHigh: uint32(off >> 32),
   551  		Offset:     uint32(off),
   552  	}
   553  	var done uint32
   554  	e = syscall.ReadFile(fd.Sysfd, b, &done, &o)
   555  	if e != nil {
   556  		done = 0
   557  		if e == syscall.ERROR_HANDLE_EOF {
   558  			e = io.EOF
   559  		}
   560  	}
   561  	if len(b) != 0 {
   562  		e = fd.eofError(int(done), e)
   563  	}
   564  	return int(done), e
   565  }
   566  
   567  // ReadFrom wraps the recvfrom network call.
   568  func (fd *FD) ReadFrom(buf []byte) (int, syscall.Sockaddr, error) {
   569  	if len(buf) == 0 {
   570  		return 0, nil, nil
   571  	}
   572  	if len(buf) > maxRW {
   573  		buf = buf[:maxRW]
   574  	}
   575  	if err := fd.readLock(); err != nil {
   576  		return 0, nil, err
   577  	}
   578  	defer fd.readUnlock()
   579  	o := &fd.rop
   580  	o.InitBuf(buf)
   581  	n, err := execIO(o, func(o *operation) error {
   582  		if o.rsa == nil {
   583  			o.rsa = new(syscall.RawSockaddrAny)
   584  		}
   585  		o.rsan = int32(unsafe.Sizeof(*o.rsa))
   586  		return syscall.WSARecvFrom(o.fd.Sysfd, &o.buf, 1, &o.qty, &o.flags, o.rsa, &o.rsan, &o.o, nil)
   587  	})
   588  	err = fd.eofError(n, err)
   589  	if err != nil {
   590  		return n, nil, err
   591  	}
   592  	sa, _ := o.rsa.Sockaddr()
   593  	return n, sa, nil
   594  }
   595  
   596  // Write implements io.Writer.
   597  func (fd *FD) Write(buf []byte) (int, error) {
   598  	if err := fd.writeLock(); err != nil {
   599  		return 0, err
   600  	}
   601  	defer fd.writeUnlock()
   602  	if fd.isFile {
   603  		fd.l.Lock()
   604  		defer fd.l.Unlock()
   605  	}
   606  
   607  	ntotal := 0
   608  	for len(buf) > 0 {
   609  		b := buf
   610  		if len(b) > maxRW {
   611  			b = b[:maxRW]
   612  		}
   613  		var n int
   614  		var err error
   615  		if fd.isFile {
   616  			switch fd.kind {
   617  			case kindConsole:
   618  				n, err = fd.writeConsole(b)
   619  			default:
   620  				n, err = syscall.Write(fd.Sysfd, b)
   621  				if fd.kind == kindPipe && err == syscall.ERROR_OPERATION_ABORTED {
   622  					// Close uses CancelIoEx to interrupt concurrent I/O for pipes.
   623  					// If the fd is a pipe and the Write was interrupted by CancelIoEx,
   624  					// we assume it is interrupted by Close.
   625  					err = ErrFileClosing
   626  				}
   627  			}
   628  			if err != nil {
   629  				n = 0
   630  			}
   631  		} else {
   632  			if race.Enabled {
   633  				race.ReleaseMerge(unsafe.Pointer(&ioSync))
   634  			}
   635  			o := &fd.wop
   636  			o.InitBuf(b)
   637  			n, err = execIO(o, func(o *operation) error {
   638  				return syscall.WSASend(o.fd.Sysfd, &o.buf, 1, &o.qty, 0, &o.o, nil)
   639  			})
   640  		}
   641  		ntotal += n
   642  		if err != nil {
   643  			return ntotal, err
   644  		}
   645  		buf = buf[n:]
   646  	}
   647  	return ntotal, nil
   648  }
   649  
   650  // writeConsole writes len(b) bytes to the console File.
   651  // It returns the number of bytes written and an error, if any.
   652  func (fd *FD) writeConsole(b []byte) (int, error) {
   653  	n := len(b)
   654  	runes := make([]rune, 0, 256)
   655  	if len(fd.lastbits) > 0 {
   656  		b = append(fd.lastbits, b...)
   657  		fd.lastbits = nil
   658  
   659  	}
   660  	for len(b) >= utf8.UTFMax || utf8.FullRune(b) {
   661  		r, l := utf8.DecodeRune(b)
   662  		runes = append(runes, r)
   663  		b = b[l:]
   664  	}
   665  	if len(b) > 0 {
   666  		fd.lastbits = make([]byte, len(b))
   667  		copy(fd.lastbits, b)
   668  	}
   669  	// syscall.WriteConsole seems to fail, if given large buffer.
   670  	// So limit the buffer to 16000 characters. This number was
   671  	// discovered by experimenting with syscall.WriteConsole.
   672  	const maxWrite = 16000
   673  	for len(runes) > 0 {
   674  		m := len(runes)
   675  		if m > maxWrite {
   676  			m = maxWrite
   677  		}
   678  		chunk := runes[:m]
   679  		runes = runes[m:]
   680  		uint16s := utf16.Encode(chunk)
   681  		for len(uint16s) > 0 {
   682  			var written uint32
   683  			err := syscall.WriteConsole(fd.Sysfd, &uint16s[0], uint32(len(uint16s)), &written, nil)
   684  			if err != nil {
   685  				return 0, err
   686  			}
   687  			uint16s = uint16s[written:]
   688  		}
   689  	}
   690  	return n, nil
   691  }
   692  
   693  // Pwrite emulates the Unix pwrite system call.
   694  func (fd *FD) Pwrite(buf []byte, off int64) (int, error) {
   695  	// Call incref, not writeLock, because since pwrite specifies the
   696  	// offset it is independent from other writes.
   697  	if err := fd.incref(); err != nil {
   698  		return 0, err
   699  	}
   700  	defer fd.decref()
   701  
   702  	fd.l.Lock()
   703  	defer fd.l.Unlock()
   704  	curoffset, e := syscall.Seek(fd.Sysfd, 0, io.SeekCurrent)
   705  	if e != nil {
   706  		return 0, e
   707  	}
   708  	defer syscall.Seek(fd.Sysfd, curoffset, io.SeekStart)
   709  
   710  	ntotal := 0
   711  	for len(buf) > 0 {
   712  		b := buf
   713  		if len(b) > maxRW {
   714  			b = b[:maxRW]
   715  		}
   716  		var n uint32
   717  		o := syscall.Overlapped{
   718  			OffsetHigh: uint32(off >> 32),
   719  			Offset:     uint32(off),
   720  		}
   721  		e = syscall.WriteFile(fd.Sysfd, b, &n, &o)
   722  		ntotal += int(n)
   723  		if e != nil {
   724  			return ntotal, e
   725  		}
   726  		buf = buf[n:]
   727  		off += int64(n)
   728  	}
   729  	return ntotal, nil
   730  }
   731  
   732  // Writev emulates the Unix writev system call.
   733  func (fd *FD) Writev(buf *[][]byte) (int64, error) {
   734  	if len(*buf) == 0 {
   735  		return 0, nil
   736  	}
   737  	if err := fd.writeLock(); err != nil {
   738  		return 0, err
   739  	}
   740  	defer fd.writeUnlock()
   741  	if race.Enabled {
   742  		race.ReleaseMerge(unsafe.Pointer(&ioSync))
   743  	}
   744  	o := &fd.wop
   745  	o.InitBufs(buf)
   746  	n, err := execIO(o, func(o *operation) error {
   747  		return syscall.WSASend(o.fd.Sysfd, &o.bufs[0], uint32(len(o.bufs)), &o.qty, 0, &o.o, nil)
   748  	})
   749  	o.ClearBufs()
   750  	TestHookDidWritev(n)
   751  	consume(buf, int64(n))
   752  	return int64(n), err
   753  }
   754  
   755  // WriteTo wraps the sendto network call.
   756  func (fd *FD) WriteTo(buf []byte, sa syscall.Sockaddr) (int, error) {
   757  	if err := fd.writeLock(); err != nil {
   758  		return 0, err
   759  	}
   760  	defer fd.writeUnlock()
   761  
   762  	if len(buf) == 0 {
   763  		// handle zero-byte payload
   764  		o := &fd.wop
   765  		o.InitBuf(buf)
   766  		o.sa = sa
   767  		n, err := execIO(o, func(o *operation) error {
   768  			return syscall.WSASendto(o.fd.Sysfd, &o.buf, 1, &o.qty, 0, o.sa, &o.o, nil)
   769  		})
   770  		return n, err
   771  	}
   772  
   773  	ntotal := 0
   774  	for len(buf) > 0 {
   775  		b := buf
   776  		if len(b) > maxRW {
   777  			b = b[:maxRW]
   778  		}
   779  		o := &fd.wop
   780  		o.InitBuf(b)
   781  		o.sa = sa
   782  		n, err := execIO(o, func(o *operation) error {
   783  			return syscall.WSASendto(o.fd.Sysfd, &o.buf, 1, &o.qty, 0, o.sa, &o.o, nil)
   784  		})
   785  		ntotal += int(n)
   786  		if err != nil {
   787  			return ntotal, err
   788  		}
   789  		buf = buf[n:]
   790  	}
   791  	return ntotal, nil
   792  }
   793  
   794  // Call ConnectEx. This doesn't need any locking, since it is only
   795  // called when the descriptor is first created. This is here rather
   796  // than in the net package so that it can use fd.wop.
   797  func (fd *FD) ConnectEx(ra syscall.Sockaddr) error {
   798  	o := &fd.wop
   799  	o.sa = ra
   800  	_, err := execIO(o, func(o *operation) error {
   801  		return ConnectExFunc(o.fd.Sysfd, o.sa, nil, 0, nil, &o.o)
   802  	})
   803  	return err
   804  }
   805  
   806  func (fd *FD) acceptOne(s syscall.Handle, rawsa []syscall.RawSockaddrAny, o *operation) (string, error) {
   807  	// Submit accept request.
   808  	o.handle = s
   809  	o.rsan = int32(unsafe.Sizeof(rawsa[0]))
   810  	_, err := execIO(o, func(o *operation) error {
   811  		return AcceptFunc(o.fd.Sysfd, o.handle, (*byte)(unsafe.Pointer(&rawsa[0])), 0, uint32(o.rsan), uint32(o.rsan), &o.qty, &o.o)
   812  	})
   813  	if err != nil {
   814  		CloseFunc(s)
   815  		return "acceptex", err
   816  	}
   817  
   818  	// Inherit properties of the listening socket.
   819  	err = syscall.Setsockopt(s, syscall.SOL_SOCKET, syscall.SO_UPDATE_ACCEPT_CONTEXT, (*byte)(unsafe.Pointer(&fd.Sysfd)), int32(unsafe.Sizeof(fd.Sysfd)))
   820  	if err != nil {
   821  		CloseFunc(s)
   822  		return "setsockopt", err
   823  	}
   824  
   825  	return "", nil
   826  }
   827  
   828  // Accept handles accepting a socket. The sysSocket parameter is used
   829  // to allocate the net socket.
   830  func (fd *FD) Accept(sysSocket func() (syscall.Handle, error)) (syscall.Handle, []syscall.RawSockaddrAny, uint32, string, error) {
   831  	if err := fd.readLock(); err != nil {
   832  		return syscall.InvalidHandle, nil, 0, "", err
   833  	}
   834  	defer fd.readUnlock()
   835  
   836  	o := &fd.rop
   837  	var rawsa [2]syscall.RawSockaddrAny
   838  	for {
   839  		s, err := sysSocket()
   840  		if err != nil {
   841  			return syscall.InvalidHandle, nil, 0, "", err
   842  		}
   843  
   844  		errcall, err := fd.acceptOne(s, rawsa[:], o)
   845  		if err == nil {
   846  			return s, rawsa[:], uint32(o.rsan), "", nil
   847  		}
   848  
   849  		// Sometimes we see WSAECONNRESET and ERROR_NETNAME_DELETED is
   850  		// returned here. These happen if connection reset is received
   851  		// before AcceptEx could complete. These errors relate to new
   852  		// connection, not to AcceptEx, so ignore broken connection and
   853  		// try AcceptEx again for more connections.
   854  		errno, ok := err.(syscall.Errno)
   855  		if !ok {
   856  			return syscall.InvalidHandle, nil, 0, errcall, err
   857  		}
   858  		switch errno {
   859  		case syscall.ERROR_NETNAME_DELETED, syscall.WSAECONNRESET:
   860  			// ignore these and try again
   861  		default:
   862  			return syscall.InvalidHandle, nil, 0, errcall, err
   863  		}
   864  	}
   865  }
   866  
   867  // Seek wraps syscall.Seek.
   868  func (fd *FD) Seek(offset int64, whence int) (int64, error) {
   869  	if err := fd.incref(); err != nil {
   870  		return 0, err
   871  	}
   872  	defer fd.decref()
   873  
   874  	fd.l.Lock()
   875  	defer fd.l.Unlock()
   876  
   877  	return syscall.Seek(fd.Sysfd, offset, whence)
   878  }
   879  
   880  // FindNextFile wraps syscall.FindNextFile.
   881  func (fd *FD) FindNextFile(data *syscall.Win32finddata) error {
   882  	if err := fd.incref(); err != nil {
   883  		return err
   884  	}
   885  	defer fd.decref()
   886  	return syscall.FindNextFile(fd.Sysfd, data)
   887  }
   888  
   889  // Fchmod updates syscall.ByHandleFileInformation.Fileattributes when needed.
   890  func (fd *FD) Fchmod(mode uint32) error {
   891  	if err := fd.incref(); err != nil {
   892  		return err
   893  	}
   894  	defer fd.decref()
   895  
   896  	var d syscall.ByHandleFileInformation
   897  	if err := syscall.GetFileInformationByHandle(fd.Sysfd, &d); err != nil {
   898  		return err
   899  	}
   900  	attrs := d.FileAttributes
   901  	if mode&syscall.S_IWRITE != 0 {
   902  		attrs &^= syscall.FILE_ATTRIBUTE_READONLY
   903  	} else {
   904  		attrs |= syscall.FILE_ATTRIBUTE_READONLY
   905  	}
   906  	if attrs == d.FileAttributes {
   907  		return nil
   908  	}
   909  
   910  	var du windows.FILE_BASIC_INFO
   911  	du.FileAttributes = attrs
   912  	l := uint32(unsafe.Sizeof(d))
   913  	return windows.SetFileInformationByHandle(fd.Sysfd, windows.FileBasicInfo, uintptr(unsafe.Pointer(&du)), l)
   914  }
   915  
   916  // Fchdir wraps syscall.Fchdir.
   917  func (fd *FD) Fchdir() error {
   918  	if err := fd.incref(); err != nil {
   919  		return err
   920  	}
   921  	defer fd.decref()
   922  	return syscall.Fchdir(fd.Sysfd)
   923  }
   924  
   925  // GetFileType wraps syscall.GetFileType.
   926  func (fd *FD) GetFileType() (uint32, error) {
   927  	if err := fd.incref(); err != nil {
   928  		return 0, err
   929  	}
   930  	defer fd.decref()
   931  	return syscall.GetFileType(fd.Sysfd)
   932  }
   933  
   934  // GetFileInformationByHandle wraps GetFileInformationByHandle.
   935  func (fd *FD) GetFileInformationByHandle(data *syscall.ByHandleFileInformation) error {
   936  	if err := fd.incref(); err != nil {
   937  		return err
   938  	}
   939  	defer fd.decref()
   940  	return syscall.GetFileInformationByHandle(fd.Sysfd, data)
   941  }
   942  
   943  // RawRead invokes the user-defined function f for a read operation.
   944  func (fd *FD) RawRead(f func(uintptr) bool) error {
   945  	if err := fd.readLock(); err != nil {
   946  		return err
   947  	}
   948  	defer fd.readUnlock()
   949  	for {
   950  		if f(uintptr(fd.Sysfd)) {
   951  			return nil
   952  		}
   953  
   954  		// Use a zero-byte read as a way to get notified when this
   955  		// socket is readable. h/t https://stackoverflow.com/a/42019668/332798
   956  		o := &fd.rop
   957  		o.InitBuf(nil)
   958  		if !fd.IsStream {
   959  			o.flags |= windows.MSG_PEEK
   960  		}
   961  		_, err := execIO(o, func(o *operation) error {
   962  			return syscall.WSARecv(o.fd.Sysfd, &o.buf, 1, &o.qty, &o.flags, &o.o, nil)
   963  		})
   964  		if err == windows.WSAEMSGSIZE {
   965  			// expected with a 0-byte peek, ignore.
   966  		} else if err != nil {
   967  			return err
   968  		}
   969  	}
   970  }
   971  
   972  // RawWrite invokes the user-defined function f for a write operation.
   973  func (fd *FD) RawWrite(f func(uintptr) bool) error {
   974  	if err := fd.writeLock(); err != nil {
   975  		return err
   976  	}
   977  	defer fd.writeUnlock()
   978  
   979  	if f(uintptr(fd.Sysfd)) {
   980  		return nil
   981  	}
   982  
   983  	// TODO(tmm1): find a way to detect socket writability
   984  	return syscall.EWINDOWS
   985  }
   986  
   987  func sockaddrToRaw(sa syscall.Sockaddr) (unsafe.Pointer, int32, error) {
   988  	switch sa := sa.(type) {
   989  	case *syscall.SockaddrInet4:
   990  		var raw syscall.RawSockaddrInet4
   991  		raw.Family = syscall.AF_INET
   992  		p := (*[2]byte)(unsafe.Pointer(&raw.Port))
   993  		p[0] = byte(sa.Port >> 8)
   994  		p[1] = byte(sa.Port)
   995  		for i := 0; i < len(sa.Addr); i++ {
   996  			raw.Addr[i] = sa.Addr[i]
   997  		}
   998  		return unsafe.Pointer(&raw), int32(unsafe.Sizeof(raw)), nil
   999  	case *syscall.SockaddrInet6:
  1000  		var raw syscall.RawSockaddrInet6
  1001  		raw.Family = syscall.AF_INET6
  1002  		p := (*[2]byte)(unsafe.Pointer(&raw.Port))
  1003  		p[0] = byte(sa.Port >> 8)
  1004  		p[1] = byte(sa.Port)
  1005  		raw.Scope_id = sa.ZoneId
  1006  		for i := 0; i < len(sa.Addr); i++ {
  1007  			raw.Addr[i] = sa.Addr[i]
  1008  		}
  1009  		return unsafe.Pointer(&raw), int32(unsafe.Sizeof(raw)), nil
  1010  	default:
  1011  		return nil, 0, syscall.EWINDOWS
  1012  	}
  1013  }
  1014  
  1015  // ReadMsg wraps the WSARecvMsg network call.
  1016  func (fd *FD) ReadMsg(p []byte, oob []byte, flags int) (int, int, int, syscall.Sockaddr, error) {
  1017  	if err := fd.readLock(); err != nil {
  1018  		return 0, 0, 0, nil, err
  1019  	}
  1020  	defer fd.readUnlock()
  1021  
  1022  	if len(p) > maxRW {
  1023  		p = p[:maxRW]
  1024  	}
  1025  
  1026  	o := &fd.rop
  1027  	o.InitMsg(p, oob)
  1028  	o.rsa = new(syscall.RawSockaddrAny)
  1029  	o.msg.Name = (syscall.Pointer)(unsafe.Pointer(o.rsa))
  1030  	o.msg.Namelen = int32(unsafe.Sizeof(*o.rsa))
  1031  	o.msg.Flags = uint32(flags)
  1032  	n, err := execIO(o, func(o *operation) error {
  1033  		return windows.WSARecvMsg(o.fd.Sysfd, &o.msg, &o.qty, &o.o, nil)
  1034  	})
  1035  	err = fd.eofError(n, err)
  1036  	var sa syscall.Sockaddr
  1037  	if err == nil {
  1038  		sa, err = o.rsa.Sockaddr()
  1039  	}
  1040  	return n, int(o.msg.Control.Len), int(o.msg.Flags), sa, err
  1041  }
  1042  
  1043  // WriteMsg wraps the WSASendMsg network call.
  1044  func (fd *FD) WriteMsg(p []byte, oob []byte, sa syscall.Sockaddr) (int, int, error) {
  1045  	if len(p) > maxRW {
  1046  		return 0, 0, errors.New("packet is too large (only 1GB is allowed)")
  1047  	}
  1048  
  1049  	if err := fd.writeLock(); err != nil {
  1050  		return 0, 0, err
  1051  	}
  1052  	defer fd.writeUnlock()
  1053  
  1054  	o := &fd.wop
  1055  	o.InitMsg(p, oob)
  1056  	if sa != nil {
  1057  		rsa, len, err := sockaddrToRaw(sa)
  1058  		if err != nil {
  1059  			return 0, 0, err
  1060  		}
  1061  		o.msg.Name = (syscall.Pointer)(rsa)
  1062  		o.msg.Namelen = len
  1063  	}
  1064  	n, err := execIO(o, func(o *operation) error {
  1065  		return windows.WSASendMsg(o.fd.Sysfd, &o.msg, 0, &o.qty, &o.o, nil)
  1066  	})
  1067  	return n, int(o.msg.Control.Len), err
  1068  }
  1069  

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