src/os/file_windows.go - go - Git at Google

 // Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

 package os

 import (
 	"errors"
 	"internal/syscall/windows"
 	"io"
 	"runtime"
 	"sync"
 	"syscall"
 	"unicode/utf16"
 	"unicode/utf8"
 	"unsafe"
 )

 // file is the real representation of *File.
 // The extra level of indirection ensures that no clients of os
 // can overwrite this data, which could cause the finalizer
 // to close the wrong file descriptor.
 type file struct {
 	fd      syscall.Handle
 	name    string
 	dirinfo *dirInfo   // nil unless directory being read
 	l       sync.Mutex // used to implement windows pread/pwrite

 	// only for console io
 	isConsole bool
 	lastbits  []byte // first few bytes of the last incomplete rune in last write
 	readbuf   []byte // last few bytes of the last read that did not fit in the user buffer
 }

 // Fd returns the Windows handle referencing the open file.
 // The handle is valid only until f.Close is called or f is garbage collected.
 func (file *File) Fd() uintptr {
 	if file == nil {
 		return uintptr(syscall.InvalidHandle)
 	}
 	return uintptr(file.fd)
 }

 // newFile returns a new File with the given file handle and name.
 // Unlike NewFile, it does not check that h is syscall.InvalidHandle.
 func newFile(h syscall.Handle, name string) *File {
 	f := &File{&file{fd: h, name: name}}
 	runtime.SetFinalizer(f.file, (*file).close)
 	return f
 }

 // newConsoleFile creates new File that will be used as console.
 func newConsoleFile(h syscall.Handle, name string) *File {
 	f := newFile(h, name)
 	f.isConsole = true
 	f.readbuf = make([]byte, 0, 4)
 	return f
 }

 // NewFile returns a new File with the given file descriptor and name.
 func NewFile(fd uintptr, name string) *File {
 	h := syscall.Handle(fd)
 	if h == syscall.InvalidHandle {
 		return nil
 	}
 	var m uint32
 	if syscall.GetConsoleMode(h, &m) == nil {
 		return newConsoleFile(h, name)
 	}
 	return newFile(h, name)
 }

 // Auxiliary information if the File describes a directory
 type dirInfo struct {
 	data     syscall.Win32finddata
 	needdata bool
 	path     string
 	isempty  bool // set if FindFirstFile returns ERROR_FILE_NOT_FOUND
 }

 func epipecheck(file *File, e error) {
 }

 const DevNull = "NUL"

 func (f *file) isdir() bool { return f != nil && f.dirinfo != nil }

 func openFile(name string, flag int, perm FileMode) (file *File, err error) {
 	r, e := syscall.Open(fixLongPath(name), flag|syscall.O_CLOEXEC, syscallMode(perm))
 	if e != nil {
 		return nil, e
 	}
 	return NewFile(uintptr(r), name), nil
 }

 func openDir(name string) (file *File, err error) {
 	var mask string

 	path := fixLongPath(name)

 	if len(path) == 2 && path[1] == ':' || (len(path) > 0 && path[len(path)-1] == '\\') { // it is a drive letter, like C:
 		mask = path + `*`
 	} else {
 		mask = path + `\*`
 	}
 	maskp, e := syscall.UTF16PtrFromString(mask)
 	if e != nil {
 		return nil, e
 	}
 	d := new(dirInfo)
 	r, e := syscall.FindFirstFile(maskp, &d.data)
 	if e != nil {
 		// FindFirstFile returns ERROR_FILE_NOT_FOUND when
 		// no matching files can be found. Then, if directory
 		// exists, we should proceed.
 		if e != syscall.ERROR_FILE_NOT_FOUND {
 			return nil, e
 		}
 		var fa syscall.Win32FileAttributeData
 		pathp, e := syscall.UTF16PtrFromString(path)
 		if e != nil {
 			return nil, e
 		}
 		e = syscall.GetFileAttributesEx(pathp, syscall.GetFileExInfoStandard, (*byte)(unsafe.Pointer(&fa)))
 		if e != nil {
 			return nil, e
 		}
 		if fa.FileAttributes&syscall.FILE_ATTRIBUTE_DIRECTORY == 0 {
 			return nil, e
 		}
 		d.isempty = true
 	}
 	d.path = path
 	if !isAbs(d.path) {
 		d.path, e = syscall.FullPath(d.path)
 		if e != nil {
 			return nil, e
 		}
 	}
 	f := newFile(r, name)
 	f.dirinfo = d
 	return f, nil
 }

 // OpenFile is the generalized open call; most users will use Open
 // or Create instead. It opens the named file with specified flag
 // (O_RDONLY etc.) and perm, (0666 etc.) if applicable. If successful,
 // methods on the returned File can be used for I/O.
 // If there is an error, it will be of type *PathError.
 func OpenFile(name string, flag int, perm FileMode) (*File, error) {
 	if name == "" {
 		return nil, &PathError{"open", name, syscall.ENOENT}
 	}
 	r, errf := openFile(name, flag, perm)
 	if errf == nil {
 		return r, nil
 	}
 	r, errd := openDir(name)
 	if errd == nil {
 		if flag&O_WRONLY != 0 || flag&O_RDWR != 0 {
 			r.Close()
 			return nil, &PathError{"open", name, syscall.EISDIR}
 		}
 		return r, nil
 	}
 	return nil, &PathError{"open", name, errf}
 }

 // Close closes the File, rendering it unusable for I/O.
 // It returns an error, if any.
 func (file *File) Close() error {
 	if file == nil {
 		return ErrInvalid
 	}
 	return file.file.close()
 }

 func (file *file) close() error {
 	if file == nil {
 		return syscall.EINVAL
 	}
 	if file.isdir() && file.dirinfo.isempty {
 		// "special" empty directories
 		return nil
 	}
 	if file.fd == syscall.InvalidHandle {
 		return syscall.EINVAL
 	}
 	var e error
 	if file.isdir() {
 		e = syscall.FindClose(file.fd)
 	} else {
 		e = syscall.CloseHandle(file.fd)
 	}
 	var err error
 	if e != nil {
 		err = &PathError{"close", file.name, e}
 	}
 	file.fd = badFd // so it can't be closed again

 	// no need for a finalizer anymore
 	runtime.SetFinalizer(file, nil)
 	return err
 }

 var (
 	// These variables are used for testing readConsole.
 	getCP    = windows.GetConsoleCP
 	readFile = syscall.ReadFile
 )

 func resetGetConsoleCPAndReadFileFuncs() {
 	getCP = windows.GetConsoleCP
 	readFile = syscall.ReadFile
 }

 // copyReadConsoleBuffer copies data stored in f.readbuf into buf.
 // It adjusts f.readbuf accordingly and returns number of bytes copied.
 func (f *File) copyReadConsoleBuffer(buf []byte) (n int, err error) {
 	n = copy(buf, f.readbuf)
 	newsize := copy(f.readbuf, f.readbuf[n:])
 	f.readbuf = f.readbuf[:newsize]
 	return n, nil
 }

 // readOneUTF16FromConsole reads single character from console,
 // converts it into utf16 and return it to the caller.
 func (f *File) readOneUTF16FromConsole() (uint16, error) {
 	var buf [1]byte
 	mbytes := make([]byte, 0, 4)
 	cp := getCP()
 	for {
 		var nmb uint32
 		err := readFile(f.fd, buf[:], &nmb, nil)
 		if err != nil {
 			return 0, err
 		}
 		if nmb == 0 {
 			continue
 		}
 		mbytes = append(mbytes, buf[0])

 		// Convert from 8-bit console encoding to UTF16.
 		// MultiByteToWideChar defaults to Unicode NFC form, which is the expected one.
 		nwc, err := windows.MultiByteToWideChar(cp, windows.MB_ERR_INVALID_CHARS, &mbytes[0], int32(len(mbytes)), nil, 0)
 		if err != nil {
 			if err == windows.ERROR_NO_UNICODE_TRANSLATION {
 				continue
 			}
 			return 0, err
 		}
 		if nwc != 1 {
 			return 0, errors.New("MultiByteToWideChar returns " + itoa(int(nwc)) + " characters, but only 1 expected")
 		}
 		var wchars [1]uint16
 		nwc, err = windows.MultiByteToWideChar(cp, windows.MB_ERR_INVALID_CHARS, &mbytes[0], int32(len(mbytes)), &wchars[0], nwc)
 		if err != nil {
 			return 0, err
 		}
 		return wchars[0], nil
 	}
 }

 // readConsole reads utf16 characters from console File,
 // encodes them into utf8 and stores them in buffer buf.
 // It returns the number of utf8 bytes read and an error, if any.
 func (f *File) readConsole(buf []byte) (n int, err error) {
 	if len(buf) == 0 {
 		return 0, nil
 	}
 	if len(f.readbuf) > 0 {
 		return f.copyReadConsoleBuffer(buf)
 	}
 	wchar, err := f.readOneUTF16FromConsole()
 	if err != nil {
 		return 0, err
 	}
 	r := rune(wchar)
 	if utf16.IsSurrogate(r) {
 		wchar, err := f.readOneUTF16FromConsole()
 		if err != nil {
 			return 0, err
 		}
 		r = utf16.DecodeRune(r, rune(wchar))
 	}
 	if nr := utf8.RuneLen(r); nr > len(buf) {
 		start := len(f.readbuf)
 		for ; nr > 0; nr-- {
 			f.readbuf = append(f.readbuf, 0)
 		}
 		utf8.EncodeRune(f.readbuf[start:cap(f.readbuf)], r)
 	} else {
 		utf8.EncodeRune(buf, r)
 		buf = buf[nr:]
 		n += nr
 	}
 	if n > 0 {
 		return n, nil
 	}
 	return f.copyReadConsoleBuffer(buf)
 }

 // read reads up to len(b) bytes from the File.
 // It returns the number of bytes read and an error, if any.
 func (f *File) read(b []byte) (n int, err error) {
 	f.l.Lock()
 	defer f.l.Unlock()
 	if f.isConsole {
 		return f.readConsole(b)
 	}
 	return fixCount(syscall.Read(f.fd, b))
 }

 // pread reads len(b) bytes from the File starting at byte offset off.
 // It returns the number of bytes read and the error, if any.
 // EOF is signaled by a zero count with err set to 0.
 func (f *File) pread(b []byte, off int64) (n int, err error) {
 	f.l.Lock()
 	defer f.l.Unlock()
 	curoffset, e := syscall.Seek(f.fd, 0, io.SeekCurrent)
 	if e != nil {
 		return 0, e
 	}
 	defer syscall.Seek(f.fd, curoffset, io.SeekStart)
 	o := syscall.Overlapped{
 		OffsetHigh: uint32(off >> 32),
 		Offset:     uint32(off),
 	}
 	var done uint32
 	e = syscall.ReadFile(f.fd, b, &done, &o)
 	if e != nil {
 		if e == syscall.ERROR_HANDLE_EOF {
 			// end of file
 			return 0, nil
 		}
 		return 0, e
 	}
 	return int(done), nil
 }

 // writeConsole writes len(b) bytes to the console File.
 // It returns the number of bytes written and an error, if any.
 func (f *File) writeConsole(b []byte) (n int, err error) {
 	n = len(b)
 	runes := make([]rune, 0, 256)
 	if len(f.lastbits) > 0 {
 		b = append(f.lastbits, b...)
 		f.lastbits = nil

 	}
 	for len(b) >= utf8.UTFMax || utf8.FullRune(b) {
 		r, l := utf8.DecodeRune(b)
 		runes = append(runes, r)
 		b = b[l:]
 	}
 	if len(b) > 0 {
 		f.lastbits = make([]byte, len(b))
 		copy(f.lastbits, b)
 	}
 	// syscall.WriteConsole seems to fail, if given large buffer.
 	// So limit the buffer to 16000 characters. This number was
 	// discovered by experimenting with syscall.WriteConsole.
 	const maxWrite = 16000
 	for len(runes) > 0 {
 		m := len(runes)
 		if m > maxWrite {
 			m = maxWrite
 		}
 		chunk := runes[:m]
 		runes = runes[m:]
 		uint16s := utf16.Encode(chunk)
 		for len(uint16s) > 0 {
 			var written uint32
 			err = syscall.WriteConsole(f.fd, &uint16s[0], uint32(len(uint16s)), &written, nil)
 			if err != nil {
 				return 0, nil
 			}
 			uint16s = uint16s[written:]
 		}
 	}
 	return n, nil
 }

 // write writes len(b) bytes to the File.
 // It returns the number of bytes written and an error, if any.
 func (f *File) write(b []byte) (n int, err error) {
 	f.l.Lock()
 	defer f.l.Unlock()
 	if f.isConsole {
 		return f.writeConsole(b)
 	}
 	return fixCount(syscall.Write(f.fd, b))
 }

 // pwrite writes len(b) bytes to the File starting at byte offset off.
 // It returns the number of bytes written and an error, if any.
 func (f *File) pwrite(b []byte, off int64) (n int, err error) {
 	f.l.Lock()
 	defer f.l.Unlock()
 	curoffset, e := syscall.Seek(f.fd, 0, io.SeekCurrent)
 	if e != nil {
 		return 0, e
 	}
 	defer syscall.Seek(f.fd, curoffset, io.SeekStart)
 	o := syscall.Overlapped{
 		OffsetHigh: uint32(off >> 32),
 		Offset:     uint32(off),
 	}
 	var done uint32
 	e = syscall.WriteFile(f.fd, b, &done, &o)
 	if e != nil {
 		return 0, e
 	}
 	return int(done), nil
 }

 // seek sets the offset for the next Read or Write on file to offset, interpreted
 // according to whence: 0 means relative to the origin of the file, 1 means
 // relative to the current offset, and 2 means relative to the end.
 // It returns the new offset and an error, if any.
 func (f *File) seek(offset int64, whence int) (ret int64, err error) {
 	f.l.Lock()
 	defer f.l.Unlock()
 	return syscall.Seek(f.fd, offset, whence)
 }

 // Truncate changes the size of the named file.
 // If the file is a symbolic link, it changes the size of the link's target.
 func Truncate(name string, size int64) error {
 	f, e := OpenFile(name, O_WRONLY|O_CREATE, 0666)
 	if e != nil {
 		return e
 	}
 	defer f.Close()
 	e1 := f.Truncate(size)
 	if e1 != nil {
 		return e1
 	}
 	return nil
 }

 // Remove removes the named file or directory.
 // If there is an error, it will be of type *PathError.
 func Remove(name string) error {
 	p, e := syscall.UTF16PtrFromString(fixLongPath(name))
 	if e != nil {
 		return &PathError{"remove", name, e}
 	}

 	// Go file interface forces us to know whether
 	// name is a file or directory. Try both.
 	e = syscall.DeleteFile(p)
 	if e == nil {
 		return nil
 	}
 	e1 := syscall.RemoveDirectory(p)
 	if e1 == nil {
 		return nil
 	}

 	// Both failed: figure out which error to return.
 	if e1 != e {
 		a, e2 := syscall.GetFileAttributes(p)
 		if e2 != nil {
 			e = e2
 		} else {
 			if a&syscall.FILE_ATTRIBUTE_DIRECTORY != 0 {
 				e = e1
 			} else if a&syscall.FILE_ATTRIBUTE_READONLY != 0 {
 				if e1 = syscall.SetFileAttributes(p, a&^syscall.FILE_ATTRIBUTE_READONLY); e1 == nil {
 					if e = syscall.DeleteFile(p); e == nil {
 						return nil
 					}
 				}
 			}
 		}
 	}
 	return &PathError{"remove", name, e}
 }

 func rename(oldname, newname string) error {
 	e := windows.Rename(fixLongPath(oldname), fixLongPath(newname))
 	if e != nil {
 		return &LinkError{"rename", oldname, newname, e}
 	}
 	return nil
 }

 // Pipe returns a connected pair of Files; reads from r return bytes written to w.
 // It returns the files and an error, if any.
 func Pipe() (r *File, w *File, err error) {
 	var p [2]syscall.Handle

 	// See ../syscall/exec.go for description of lock.
 	syscall.ForkLock.RLock()
 	e := syscall.Pipe(p[0:])
 	if e != nil {
 		syscall.ForkLock.RUnlock()
 		return nil, nil, NewSyscallError("pipe", e)
 	}
 	syscall.CloseOnExec(p[0])
 	syscall.CloseOnExec(p[1])
 	syscall.ForkLock.RUnlock()

 	return NewFile(uintptr(p[0]), "|0"), NewFile(uintptr(p[1]), "|1"), nil
 }

 // TempDir returns the default directory to use for temporary files.
 func TempDir() string {
 	n := uint32(syscall.MAX_PATH)
 	for {
 		b := make([]uint16, n)
 		n, _ = syscall.GetTempPath(uint32(len(b)), &b[0])
 		if n > uint32(len(b)) {
 			continue
 		}
 		if n > 0 && b[n-1] == '\\' {
 			n--
 		}
 		return string(utf16.Decode(b[:n]))
 	}
 }

 // Link creates newname as a hard link to the oldname file.
 // If there is an error, it will be of type *LinkError.
 func Link(oldname, newname string) error {
 	n, err := syscall.UTF16PtrFromString(fixLongPath(newname))
 	if err != nil {
 		return &LinkError{"link", oldname, newname, err}
 	}
 	o, err := syscall.UTF16PtrFromString(fixLongPath(oldname))
 	if err != nil {
 		return &LinkError{"link", oldname, newname, err}
 	}
 	err = syscall.CreateHardLink(n, o, 0)
 	if err != nil {
 		return &LinkError{"link", oldname, newname, err}
 	}
 	return nil
 }

 // Symlink creates newname as a symbolic link to oldname.
 // If there is an error, it will be of type *LinkError.
 func Symlink(oldname, newname string) error {
 	// CreateSymbolicLink is not supported before Windows Vista
 	if syscall.LoadCreateSymbolicLink() != nil {
 		return &LinkError{"symlink", oldname, newname, syscall.EWINDOWS}
 	}

 	// '/' does not work in link's content
 	oldname = fromSlash(oldname)

 	// need the exact location of the oldname when its relative to determine if its a directory
 	destpath := oldname
 	if !isAbs(oldname) {
 		destpath = dirname(newname) + `\` + oldname
 	}

 	fi, err := Lstat(destpath)
 	isdir := err == nil && fi.IsDir()

 	n, err := syscall.UTF16PtrFromString(fixLongPath(newname))
 	if err != nil {
 		return &LinkError{"symlink", oldname, newname, err}
 	}
 	o, err := syscall.UTF16PtrFromString(fixLongPath(oldname))
 	if err != nil {
 		return &LinkError{"symlink", oldname, newname, err}
 	}

 	var flags uint32
 	if isdir {
 		flags |= syscall.SYMBOLIC_LINK_FLAG_DIRECTORY
 	}
 	err = syscall.CreateSymbolicLink(n, o, flags)
 	if err != nil {
 		return &LinkError{"symlink", oldname, newname, err}
 	}
 	return nil
 }

 const badFd = syscall.InvalidHandle
	// Copyright 2009 The Go Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style
	// license that can be found in the LICENSE file.

	package os

	import (
	"errors"
	"internal/syscall/windows"
	"io"
	"runtime"
	"sync"
	"syscall"
	"unicode/utf16"
	"unicode/utf8"
	"unsafe"
	)

	// file is the real representation of *File.
	// The extra level of indirection ensures that no clients of os
	// can overwrite this data, which could cause the finalizer
	// to close the wrong file descriptor.
	type file struct {
	fd syscall.Handle
	name string
	dirinfo *dirInfo // nil unless directory being read
	l sync.Mutex // used to implement windows pread/pwrite

	// only for console io
	isConsole bool
	lastbits []byte // first few bytes of the last incomplete rune in last write
	readbuf []byte // last few bytes of the last read that did not fit in the user buffer
	}

	// Fd returns the Windows handle referencing the open file.
	// The handle is valid only until f.Close is called or f is garbage collected.
	func (file *File) Fd() uintptr {
	if file == nil {
	return uintptr(syscall.InvalidHandle)
	}
	return uintptr(file.fd)
	}

	// newFile returns a new File with the given file handle and name.
	// Unlike NewFile, it does not check that h is syscall.InvalidHandle.
	func newFile(h syscall.Handle, name string) *File {
	f := &File{&file{fd: h, name: name}}
	runtime.SetFinalizer(f.file, (*file).close)
	return f
	}

	// newConsoleFile creates new File that will be used as console.
	func newConsoleFile(h syscall.Handle, name string) *File {
	f := newFile(h, name)
	f.isConsole = true
	f.readbuf = make([]byte, 0, 4)
	return f
	}

	// NewFile returns a new File with the given file descriptor and name.
	func NewFile(fd uintptr, name string) *File {
	h := syscall.Handle(fd)
	if h == syscall.InvalidHandle {
	return nil
	}
	var m uint32
	if syscall.GetConsoleMode(h, &m) == nil {
	return newConsoleFile(h, name)
	}
	return newFile(h, name)
	}

	// Auxiliary information if the File describes a directory
	type dirInfo struct {
	data syscall.Win32finddata
	needdata bool
	path string
	isempty bool // set if FindFirstFile returns ERROR_FILE_NOT_FOUND
	}

	func epipecheck(file *File, e error) {
	}

	const DevNull = "NUL"

	func (f *file) isdir() bool { return f != nil && f.dirinfo != nil }

	func openFile(name string, flag int, perm FileMode) (file *File, err error) {
	r, e := syscall.Open(fixLongPath(name), flag\|syscall.O_CLOEXEC, syscallMode(perm))
	if e != nil {
	return nil, e
	}
	return NewFile(uintptr(r), name), nil
	}

	func openDir(name string) (file *File, err error) {
	var mask string

	path := fixLongPath(name)

	if len(path) == 2 && path[1] == ':' \|\| (len(path) > 0 && path[len(path)-1] == '\\') { // it is a drive letter, like C:
	mask = path + `*`
	} else {
	mask = path + `\*`
	}
	maskp, e := syscall.UTF16PtrFromString(mask)
	if e != nil {
	return nil, e
	}
	d := new(dirInfo)
	r, e := syscall.FindFirstFile(maskp, &d.data)
	if e != nil {
	// FindFirstFile returns ERROR_FILE_NOT_FOUND when
	// no matching files can be found. Then, if directory
	// exists, we should proceed.
	if e != syscall.ERROR_FILE_NOT_FOUND {
	return nil, e
	}
	var fa syscall.Win32FileAttributeData
	pathp, e := syscall.UTF16PtrFromString(path)
	if e != nil {
	return nil, e
	}
	e = syscall.GetFileAttributesEx(pathp, syscall.GetFileExInfoStandard, (*byte)(unsafe.Pointer(&fa)))
	if e != nil {
	return nil, e
	}
	if fa.FileAttributes&syscall.FILE_ATTRIBUTE_DIRECTORY == 0 {
	return nil, e
	}
	d.isempty = true
	}
	d.path = path
	if !isAbs(d.path) {
	d.path, e = syscall.FullPath(d.path)
	if e != nil {
	return nil, e
	}
	}
	f := newFile(r, name)
	f.dirinfo = d
	return f, nil
	}

	// OpenFile is the generalized open call; most users will use Open
	// or Create instead. It opens the named file with specified flag
	// (O_RDONLY etc.) and perm, (0666 etc.) if applicable. If successful,
	// methods on the returned File can be used for I/O.
	// If there is an error, it will be of type *PathError.
	func OpenFile(name string, flag int, perm FileMode) (*File, error) {
	if name == "" {
	return nil, &PathError{"open", name, syscall.ENOENT}
	}
	r, errf := openFile(name, flag, perm)
	if errf == nil {
	return r, nil
	}
	r, errd := openDir(name)
	if errd == nil {
	if flag&O_WRONLY != 0 \|\| flag&O_RDWR != 0 {
	r.Close()
	return nil, &PathError{"open", name, syscall.EISDIR}
	}
	return r, nil
	}
	return nil, &PathError{"open", name, errf}
	}

	// Close closes the File, rendering it unusable for I/O.
	// It returns an error, if any.
	func (file *File) Close() error {
	if file == nil {
	return ErrInvalid
	}
	return file.file.close()
	}

	func (file *file) close() error {
	if file == nil {
	return syscall.EINVAL
	}
	if file.isdir() && file.dirinfo.isempty {
	// "special" empty directories
	return nil
	}
	if file.fd == syscall.InvalidHandle {
	return syscall.EINVAL
	}
	var e error
	if file.isdir() {
	e = syscall.FindClose(file.fd)
	} else {
	e = syscall.CloseHandle(file.fd)
	}
	var err error
	if e != nil {
	err = &PathError{"close", file.name, e}
	}
	file.fd = badFd // so it can't be closed again

	// no need for a finalizer anymore
	runtime.SetFinalizer(file, nil)
	return err
	}

	var (
	// These variables are used for testing readConsole.
	getCP = windows.GetConsoleCP
	readFile = syscall.ReadFile
	)

	func resetGetConsoleCPAndReadFileFuncs() {
	getCP = windows.GetConsoleCP
	readFile = syscall.ReadFile
	}

	// copyReadConsoleBuffer copies data stored in f.readbuf into buf.
	// It adjusts f.readbuf accordingly and returns number of bytes copied.
	func (f *File) copyReadConsoleBuffer(buf []byte) (n int, err error) {
	n = copy(buf, f.readbuf)
	newsize := copy(f.readbuf, f.readbuf[n:])
	f.readbuf = f.readbuf[:newsize]
	return n, nil
	}

	// readOneUTF16FromConsole reads single character from console,
	// converts it into utf16 and return it to the caller.
	func (f *File) readOneUTF16FromConsole() (uint16, error) {
	var buf [1]byte
	mbytes := make([]byte, 0, 4)
	cp := getCP()
	for {
	var nmb uint32
	err := readFile(f.fd, buf[:], &nmb, nil)
	if err != nil {
	return 0, err
	}
	if nmb == 0 {
	continue
	}
	mbytes = append(mbytes, buf[0])

	// Convert from 8-bit console encoding to UTF16.
	// MultiByteToWideChar defaults to Unicode NFC form, which is the expected one.
	nwc, err := windows.MultiByteToWideChar(cp, windows.MB_ERR_INVALID_CHARS, &mbytes[0], int32(len(mbytes)), nil, 0)
	if err != nil {
	if err == windows.ERROR_NO_UNICODE_TRANSLATION {
	continue
	}
	return 0, err
	}
	if nwc != 1 {
	return 0, errors.New("MultiByteToWideChar returns " + itoa(int(nwc)) + " characters, but only 1 expected")
	}
	var wchars [1]uint16
	nwc, err = windows.MultiByteToWideChar(cp, windows.MB_ERR_INVALID_CHARS, &mbytes[0], int32(len(mbytes)), &wchars[0], nwc)
	if err != nil {
	return 0, err
	}
	return wchars[0], nil
	}
	}

	// readConsole reads utf16 characters from console File,
	// encodes them into utf8 and stores them in buffer buf.
	// It returns the number of utf8 bytes read and an error, if any.
	func (f *File) readConsole(buf []byte) (n int, err error) {
	if len(buf) == 0 {
	return 0, nil
	}
	if len(f.readbuf) > 0 {
	return f.copyReadConsoleBuffer(buf)
	}
	wchar, err := f.readOneUTF16FromConsole()
	if err != nil {
	return 0, err
	}
	r := rune(wchar)
	if utf16.IsSurrogate(r) {
	wchar, err := f.readOneUTF16FromConsole()
	if err != nil {
	return 0, err
	}
	r = utf16.DecodeRune(r, rune(wchar))
	}
	if nr := utf8.RuneLen(r); nr > len(buf) {
	start := len(f.readbuf)
	for ; nr > 0; nr-- {
	f.readbuf = append(f.readbuf, 0)
	}
	utf8.EncodeRune(f.readbuf[start:cap(f.readbuf)], r)
	} else {
	utf8.EncodeRune(buf, r)
	buf = buf[nr:]
	n += nr
	}
	if n > 0 {
	return n, nil
	}
	return f.copyReadConsoleBuffer(buf)
	}

	// read reads up to len(b) bytes from the File.
	// It returns the number of bytes read and an error, if any.
	func (f *File) read(b []byte) (n int, err error) {
	f.l.Lock()
	defer f.l.Unlock()
	if f.isConsole {
	return f.readConsole(b)
	}
	return fixCount(syscall.Read(f.fd, b))
	}

	// pread reads len(b) bytes from the File starting at byte offset off.
	// It returns the number of bytes read and the error, if any.
	// EOF is signaled by a zero count with err set to 0.
	func (f *File) pread(b []byte, off int64) (n int, err error) {
	f.l.Lock()
	defer f.l.Unlock()
	curoffset, e := syscall.Seek(f.fd, 0, io.SeekCurrent)
	if e != nil {
	return 0, e
	}
	defer syscall.Seek(f.fd, curoffset, io.SeekStart)
	o := syscall.Overlapped{
	OffsetHigh: uint32(off >> 32),
	Offset: uint32(off),
	}
	var done uint32
	e = syscall.ReadFile(f.fd, b, &done, &o)
	if e != nil {
	if e == syscall.ERROR_HANDLE_EOF {
	// end of file
	return 0, nil
	}
	return 0, e
	}
	return int(done), nil
	}

	// writeConsole writes len(b) bytes to the console File.
	// It returns the number of bytes written and an error, if any.
	func (f *File) writeConsole(b []byte) (n int, err error) {
	n = len(b)
	runes := make([]rune, 0, 256)
	if len(f.lastbits) > 0 {
	b = append(f.lastbits, b...)
	f.lastbits = nil

	}
	for len(b) >= utf8.UTFMax \|\| utf8.FullRune(b) {
	r, l := utf8.DecodeRune(b)
	runes = append(runes, r)
	b = b[l:]
	}
	if len(b) > 0 {
	f.lastbits = make([]byte, len(b))
	copy(f.lastbits, b)
	}
	// syscall.WriteConsole seems to fail, if given large buffer.
	// So limit the buffer to 16000 characters. This number was
	// discovered by experimenting with syscall.WriteConsole.
	const maxWrite = 16000
	for len(runes) > 0 {
	m := len(runes)
	if m > maxWrite {
	m = maxWrite
	}
	chunk := runes[:m]
	runes = runes[m:]
	uint16s := utf16.Encode(chunk)
	for len(uint16s) > 0 {
	var written uint32
	err = syscall.WriteConsole(f.fd, &uint16s[0], uint32(len(uint16s)), &written, nil)
	if err != nil {
	return 0, nil
	}
	uint16s = uint16s[written:]
	}
	}
	return n, nil
	}

	// write writes len(b) bytes to the File.
	// It returns the number of bytes written and an error, if any.
	func (f *File) write(b []byte) (n int, err error) {
	f.l.Lock()
	defer f.l.Unlock()
	if f.isConsole {
	return f.writeConsole(b)
	}
	return fixCount(syscall.Write(f.fd, b))
	}

	// pwrite writes len(b) bytes to the File starting at byte offset off.
	// It returns the number of bytes written and an error, if any.
	func (f *File) pwrite(b []byte, off int64) (n int, err error) {
	f.l.Lock()
	defer f.l.Unlock()
	curoffset, e := syscall.Seek(f.fd, 0, io.SeekCurrent)
	if e != nil {
	return 0, e
	}
	defer syscall.Seek(f.fd, curoffset, io.SeekStart)
	o := syscall.Overlapped{
	OffsetHigh: uint32(off >> 32),
	Offset: uint32(off),
	}
	var done uint32
	e = syscall.WriteFile(f.fd, b, &done, &o)
	if e != nil {
	return 0, e
	}
	return int(done), nil
	}

	// seek sets the offset for the next Read or Write on file to offset, interpreted
	// according to whence: 0 means relative to the origin of the file, 1 means
	// relative to the current offset, and 2 means relative to the end.
	// It returns the new offset and an error, if any.
	func (f *File) seek(offset int64, whence int) (ret int64, err error) {
	f.l.Lock()
	defer f.l.Unlock()
	return syscall.Seek(f.fd, offset, whence)
	}

	// Truncate changes the size of the named file.
	// If the file is a symbolic link, it changes the size of the link's target.
	func Truncate(name string, size int64) error {
	f, e := OpenFile(name, O_WRONLY\|O_CREATE, 0666)
	if e != nil {
	return e
	}
	defer f.Close()
	e1 := f.Truncate(size)
	if e1 != nil {
	return e1
	}
	return nil
	}

	// Remove removes the named file or directory.
	// If there is an error, it will be of type *PathError.
	func Remove(name string) error {
	p, e := syscall.UTF16PtrFromString(fixLongPath(name))
	if e != nil {
	return &PathError{"remove", name, e}
	}

	// Go file interface forces us to know whether
	// name is a file or directory. Try both.
	e = syscall.DeleteFile(p)
	if e == nil {
	return nil
	}
	e1 := syscall.RemoveDirectory(p)
	if e1 == nil {
	return nil
	}

	// Both failed: figure out which error to return.
	if e1 != e {
	a, e2 := syscall.GetFileAttributes(p)
	if e2 != nil {
	e = e2
	} else {
	if a&syscall.FILE_ATTRIBUTE_DIRECTORY != 0 {
	e = e1
	} else if a&syscall.FILE_ATTRIBUTE_READONLY != 0 {
	if e1 = syscall.SetFileAttributes(p, a&^syscall.FILE_ATTRIBUTE_READONLY); e1 == nil {
	if e = syscall.DeleteFile(p); e == nil {
	return nil
	}
	}
	}
	}
	}
	return &PathError{"remove", name, e}
	}

	func rename(oldname, newname string) error {
	e := windows.Rename(fixLongPath(oldname), fixLongPath(newname))
	if e != nil {
	return &LinkError{"rename", oldname, newname, e}
	}
	return nil
	}

	// Pipe returns a connected pair of Files; reads from r return bytes written to w.
	// It returns the files and an error, if any.
	func Pipe() (r File, w File, err error) {
	var p [2]syscall.Handle

	// See ../syscall/exec.go for description of lock.
	syscall.ForkLock.RLock()
	e := syscall.Pipe(p[0:])
	if e != nil {
	syscall.ForkLock.RUnlock()
	return nil, nil, NewSyscallError("pipe", e)
	}
	syscall.CloseOnExec(p[0])
	syscall.CloseOnExec(p[1])
	syscall.ForkLock.RUnlock()

	return NewFile(uintptr(p[0]), "\|0"), NewFile(uintptr(p[1]), "\|1"), nil
	}

	// TempDir returns the default directory to use for temporary files.
	func TempDir() string {
	n := uint32(syscall.MAX_PATH)
	for {
	b := make([]uint16, n)
	n, _ = syscall.GetTempPath(uint32(len(b)), &b[0])
	if n > uint32(len(b)) {
	continue
	}
	if n > 0 && b[n-1] == '\\' {
	n--
	}
	return string(utf16.Decode(b[:n]))
	}
	}

	// Link creates newname as a hard link to the oldname file.
	// If there is an error, it will be of type *LinkError.
	func Link(oldname, newname string) error {
	n, err := syscall.UTF16PtrFromString(fixLongPath(newname))
	if err != nil {
	return &LinkError{"link", oldname, newname, err}
	}
	o, err := syscall.UTF16PtrFromString(fixLongPath(oldname))
	if err != nil {
	return &LinkError{"link", oldname, newname, err}
	}
	err = syscall.CreateHardLink(n, o, 0)
	if err != nil {
	return &LinkError{"link", oldname, newname, err}
	}
	return nil
	}

	// Symlink creates newname as a symbolic link to oldname.
	// If there is an error, it will be of type *LinkError.
	func Symlink(oldname, newname string) error {
	// CreateSymbolicLink is not supported before Windows Vista
	if syscall.LoadCreateSymbolicLink() != nil {
	return &LinkError{"symlink", oldname, newname, syscall.EWINDOWS}
	}

	// '/' does not work in link's content
	oldname = fromSlash(oldname)

	// need the exact location of the oldname when its relative to determine if its a directory
	destpath := oldname
	if !isAbs(oldname) {
	destpath = dirname(newname) + `\` + oldname
	}

	fi, err := Lstat(destpath)
	isdir := err == nil && fi.IsDir()

	n, err := syscall.UTF16PtrFromString(fixLongPath(newname))
	if err != nil {
	return &LinkError{"symlink", oldname, newname, err}
	}
	o, err := syscall.UTF16PtrFromString(fixLongPath(oldname))
	if err != nil {
	return &LinkError{"symlink", oldname, newname, err}
	}

	var flags uint32
	if isdir {
	flags \|= syscall.SYMBOLIC_LINK_FLAG_DIRECTORY
	}
	err = syscall.CreateSymbolicLink(n, o, flags)
	if err != nil {
	return &LinkError{"symlink", oldname, newname, err}
	}
	return nil
	}

	const badFd = syscall.InvalidHandle