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// 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 (
"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
readuint16 []uint16 // buffer to hold uint16s obtained with ReadConsole
readbyte []byte // buffer to hold decoding of readuint16 from utf16 to utf8
readbyteOffset int // readbyte[readOffset:] is yet to be consumed with file.Read
}
// 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
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 readConsole = syscall.ReadConsole // changed for testing
// readConsole reads utf16 characters from console File,
// encodes them into utf8 and stores them in buffer b.
// It returns the number of utf8 bytes read and an error, if any.
func (f *File) readConsole(b []byte) (n int, err error) {
if len(b) == 0 {
return 0, nil
}
if f.readuint16 == nil {
// Note: syscall.ReadConsole fails for very large buffers.
// The limit is somewhere around (but not exactly) 16384.
// Stay well below.
f.readuint16 = make([]uint16, 0, 10000)
f.readbyte = make([]byte, 0, 4*cap(f.readuint16))
}
for f.readbyteOffset >= len(f.readbyte) {
n := cap(f.readuint16) - len(f.readuint16)
if n > len(b) {
n = len(b)
}
var nw uint32
err := readConsole(f.fd, &f.readuint16[:len(f.readuint16)+1][len(f.readuint16)], uint32(n), &nw, nil)
if err != nil {
return 0, err
}
uint16s := f.readuint16[:len(f.readuint16)+int(nw)]
f.readuint16 = f.readuint16[:0]
buf := f.readbyte[:0]
for i := 0; i < len(uint16s); i++ {
r := rune(uint16s[i])
if utf16.IsSurrogate(r) {
if i+1 == len(uint16s) {
if nw > 0 {
// Save half surrogate pair for next time.
f.readuint16 = f.readuint16[:1]
f.readuint16[0] = uint16(r)
break
}
r = utf8.RuneError
} else {
r = utf16.DecodeRune(r, rune(uint16s[i+1]))
if r != utf8.RuneError {
i++
}
}
}
n := utf8.EncodeRune(buf[len(buf):cap(buf)], r)
buf = buf[:len(buf)+n]
}
f.readbyte = buf
f.readbyteOffset = 0
if nw == 0 {
break
}
}
src := f.readbyte[f.readbyteOffset:]
var i int
for i = 0; i < len(src) && i < len(b); i++ {
x := src[i]
if x == 0x1A { // Ctrl-Z
if i == 0 {
f.readbyteOffset++
}
break
}
b[i] = x
}
f.readbyteOffset += i
return i, nil
}
// 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