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// Copyright 2011 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.
// +build windows
// Package fsnotify allows the user to receive
// file system event notifications on Windows.
package fsnotify
import (
"errors"
"fmt"
"os"
"path/filepath"
"runtime"
"syscall"
"unsafe"
)
// Event is the type of the notification messages
// received on the watcher's Event channel.
type FileEvent struct {
mask uint32 // Mask of events
cookie uint32 // Unique cookie associating related events (for rename)
Name string // File name (optional)
}
// IsCreate reports whether the FileEvent was triggerd by a creation
func (e *FileEvent) IsCreate() bool { return (e.mask & FS_CREATE) == FS_CREATE }
// IsDelete reports whether the FileEvent was triggerd by a delete
func (e *FileEvent) IsDelete() bool {
return ((e.mask&FS_DELETE) == FS_DELETE || (e.mask&FS_DELETE_SELF) == FS_DELETE_SELF)
}
// IsModify reports whether the FileEvent was triggerd by a file modification or attribute change
func (e *FileEvent) IsModify() bool {
return ((e.mask&FS_MODIFY) == FS_MODIFY || (e.mask&FS_ATTRIB) == FS_ATTRIB)
}
// IsRename reports whether the FileEvent was triggerd by a change name
func (e *FileEvent) IsRename() bool {
return ((e.mask&FS_MOVE) == FS_MOVE || (e.mask&FS_MOVE_SELF) == FS_MOVE_SELF || (e.mask&FS_MOVED_FROM) == FS_MOVED_FROM || (e.mask&FS_MOVED_TO) == FS_MOVED_TO)
}
const (
opAddWatch = iota
opRemoveWatch
)
const (
provisional uint64 = 1 << (32 + iota)
)
type input struct {
op int
path string
flags uint32
reply chan error
}
type inode struct {
handle syscall.Handle
volume uint32
index uint64
}
type watch struct {
ov syscall.Overlapped
ino *inode // i-number
path string // Directory path
mask uint64 // Directory itself is being watched with these notify flags
names map[string]uint64 // Map of names being watched and their notify flags
rename string // Remembers the old name while renaming a file
buf [4096]byte
}
type indexMap map[uint64]*watch
type watchMap map[uint32]indexMap
// A Watcher waits for and receives event notifications
// for a specific set of files and directories.
type Watcher struct {
port syscall.Handle // Handle to completion port
watches watchMap // Map of watches (key: i-number)
fsnFlags map[string]uint32 // Map of watched files to flags used for filter
input chan *input // Inputs to the reader are sent on this channel
internalEvent chan *FileEvent // Events are queued on this channel
Event chan *FileEvent // Events are returned on this channel
Error chan error // Errors are sent on this channel
isClosed bool // Set to true when Close() is first called
quit chan chan<- error
cookie uint32
}
// NewWatcher creates and returns a Watcher.
func NewWatcher() (*Watcher, error) {
port, e := syscall.CreateIoCompletionPort(syscall.InvalidHandle, 0, 0, 0)
if e != nil {
return nil, os.NewSyscallError("CreateIoCompletionPort", e)
}
w := &Watcher{
port: port,
watches: make(watchMap),
fsnFlags: make(map[string]uint32),
input: make(chan *input, 1),
Event: make(chan *FileEvent, 50),
internalEvent: make(chan *FileEvent),
Error: make(chan error),
quit: make(chan chan<- error, 1),
}
go w.readEvents()
go w.purgeEvents()
return w, nil
}
// Close closes a Watcher.
// It sends a message to the reader goroutine to quit and removes all watches
// associated with the watcher.
func (w *Watcher) Close() error {
if w.isClosed {
return nil
}
w.isClosed = true
// Send "quit" message to the reader goroutine
ch := make(chan error)
w.quit <- ch
if err := w.wakeupReader(); err != nil {
return err
}
return <-ch
}
// AddWatch adds path to the watched file set.
func (w *Watcher) AddWatch(path string, flags uint32) error {
if w.isClosed {
return errors.New("watcher already closed")
}
in := &input{
op: opAddWatch,
path: filepath.Clean(path),
flags: flags,
reply: make(chan error),
}
w.input <- in
if err := w.wakeupReader(); err != nil {
return err
}
return <-in.reply
}
// Watch adds path to the watched file set, watching all events.
func (w *Watcher) watch(path string) error {
return w.AddWatch(path, FS_ALL_EVENTS)
}
// RemoveWatch removes path from the watched file set.
func (w *Watcher) removeWatch(path string) error {
in := &input{
op: opRemoveWatch,
path: filepath.Clean(path),
reply: make(chan error),
}
w.input <- in
if err := w.wakeupReader(); err != nil {
return err
}
return <-in.reply
}
func (w *Watcher) wakeupReader() error {
e := syscall.PostQueuedCompletionStatus(w.port, 0, 0, nil)
if e != nil {
return os.NewSyscallError("PostQueuedCompletionStatus", e)
}
return nil
}
func getDir(pathname string) (dir string, err error) {
attr, e := syscall.GetFileAttributes(syscall.StringToUTF16Ptr(pathname))
if e != nil {
return "", os.NewSyscallError("GetFileAttributes", e)
}
if attr&syscall.FILE_ATTRIBUTE_DIRECTORY != 0 {
dir = pathname
} else {
dir, _ = filepath.Split(pathname)
dir = filepath.Clean(dir)
}
return
}
func getIno(path string) (ino *inode, err error) {
h, e := syscall.CreateFile(syscall.StringToUTF16Ptr(path),
syscall.FILE_LIST_DIRECTORY,
syscall.FILE_SHARE_READ|syscall.FILE_SHARE_WRITE|syscall.FILE_SHARE_DELETE,
nil, syscall.OPEN_EXISTING,
syscall.FILE_FLAG_BACKUP_SEMANTICS|syscall.FILE_FLAG_OVERLAPPED, 0)
if e != nil {
return nil, os.NewSyscallError("CreateFile", e)
}
var fi syscall.ByHandleFileInformation
if e = syscall.GetFileInformationByHandle(h, &fi); e != nil {
syscall.CloseHandle(h)
return nil, os.NewSyscallError("GetFileInformationByHandle", e)
}
ino = &inode{
handle: h,
volume: fi.VolumeSerialNumber,
index: uint64(fi.FileIndexHigh)<<32 | uint64(fi.FileIndexLow),
}
return ino, nil
}
// Must run within the I/O thread.
func (m watchMap) get(ino *inode) *watch {
if i := m[ino.volume]; i != nil {
return i[ino.index]
}
return nil
}
// Must run within the I/O thread.
func (m watchMap) set(ino *inode, watch *watch) {
i := m[ino.volume]
if i == nil {
i = make(indexMap)
m[ino.volume] = i
}
i[ino.index] = watch
}
// Must run within the I/O thread.
func (w *Watcher) addWatch(pathname string, flags uint64) error {
dir, err := getDir(pathname)
if err != nil {
return err
}
if flags&FS_ONLYDIR != 0 && pathname != dir {
return nil
}
ino, err := getIno(dir)
if err != nil {
return err
}
watchEntry := w.watches.get(ino)
if watchEntry == nil {
if _, e := syscall.CreateIoCompletionPort(ino.handle, w.port, 0, 0); e != nil {
syscall.CloseHandle(ino.handle)
return os.NewSyscallError("CreateIoCompletionPort", e)
}
watchEntry = &watch{
ino: ino,
path: dir,
names: make(map[string]uint64),
}
w.watches.set(ino, watchEntry)
flags |= provisional
} else {
syscall.CloseHandle(ino.handle)
}
if pathname == dir {
watchEntry.mask |= flags
} else {
watchEntry.names[filepath.Base(pathname)] |= flags
}
if err = w.startRead(watchEntry); err != nil {
return err
}
if pathname == dir {
watchEntry.mask &= ^provisional
} else {
watchEntry.names[filepath.Base(pathname)] &= ^provisional
}
return nil
}
// Must run within the I/O thread.
func (w *Watcher) remWatch(pathname string) error {
dir, err := getDir(pathname)
if err != nil {
return err
}
ino, err := getIno(dir)
if err != nil {
return err
}
watch := w.watches.get(ino)
if watch == nil {
return fmt.Errorf("can't remove non-existent watch for: %s", pathname)
}
if pathname == dir {
w.sendEvent(watch.path, watch.mask&FS_IGNORED)
watch.mask = 0
} else {
name := filepath.Base(pathname)
w.sendEvent(watch.path+"/"+name, watch.names[name]&FS_IGNORED)
delete(watch.names, name)
}
return w.startRead(watch)
}
// Must run within the I/O thread.
func (w *Watcher) deleteWatch(watch *watch) {
for name, mask := range watch.names {
if mask&provisional == 0 {
w.sendEvent(watch.path+"/"+name, mask&FS_IGNORED)
}
delete(watch.names, name)
}
if watch.mask != 0 {
if watch.mask&provisional == 0 {
w.sendEvent(watch.path, watch.mask&FS_IGNORED)
}
watch.mask = 0
}
}
// Must run within the I/O thread.
func (w *Watcher) startRead(watch *watch) error {
if e := syscall.CancelIo(watch.ino.handle); e != nil {
w.Error <- os.NewSyscallError("CancelIo", e)
w.deleteWatch(watch)
}
mask := toWindowsFlags(watch.mask)
for _, m := range watch.names {
mask |= toWindowsFlags(m)
}
if mask == 0 {
if e := syscall.CloseHandle(watch.ino.handle); e != nil {
w.Error <- os.NewSyscallError("CloseHandle", e)
}
delete(w.watches[watch.ino.volume], watch.ino.index)
return nil
}
e := syscall.ReadDirectoryChanges(watch.ino.handle, &watch.buf[0],
uint32(unsafe.Sizeof(watch.buf)), false, mask, nil, &watch.ov, 0)
if e != nil {
err := os.NewSyscallError("ReadDirectoryChanges", e)
if e == syscall.ERROR_ACCESS_DENIED && watch.mask&provisional == 0 {
// Watched directory was probably removed
if w.sendEvent(watch.path, watch.mask&FS_DELETE_SELF) {
if watch.mask&FS_ONESHOT != 0 {
watch.mask = 0
}
}
err = nil
}
w.deleteWatch(watch)
w.startRead(watch)
return err
}
return nil
}
// readEvents reads from the I/O completion port, converts the
// received events into Event objects and sends them via the Event channel.
// Entry point to the I/O thread.
func (w *Watcher) readEvents() {
var (
n, key uint32
ov *syscall.Overlapped
)
runtime.LockOSThread()
for {
e := syscall.GetQueuedCompletionStatus(w.port, &n, &key, &ov, syscall.INFINITE)
watch := (*watch)(unsafe.Pointer(ov))
if watch == nil {
select {
case ch := <-w.quit:
for _, index := range w.watches {
for _, watch := range index {
w.deleteWatch(watch)
w.startRead(watch)
}
}
var err error
if e := syscall.CloseHandle(w.port); e != nil {
err = os.NewSyscallError("CloseHandle", e)
}
close(w.internalEvent)
close(w.Error)
ch <- err
return
case in := <-w.input:
switch in.op {
case opAddWatch:
in.reply <- w.addWatch(in.path, uint64(in.flags))
case opRemoveWatch:
in.reply <- w.remWatch(in.path)
}
default:
}
continue
}
switch e {
case syscall.ERROR_ACCESS_DENIED:
// Watched directory was probably removed
w.sendEvent(watch.path, watch.mask&FS_DELETE_SELF)
w.deleteWatch(watch)
w.startRead(watch)
continue
case syscall.ERROR_OPERATION_ABORTED:
// CancelIo was called on this handle
continue
default:
w.Error <- os.NewSyscallError("GetQueuedCompletionPort", e)
continue
case nil:
}
var offset uint32
for {
if n == 0 {
w.internalEvent <- &FileEvent{mask: FS_Q_OVERFLOW}
w.Error <- errors.New("short read in readEvents()")
break
}
// Point "raw" to the event in the buffer
raw := (*syscall.FileNotifyInformation)(unsafe.Pointer(&watch.buf[offset]))
buf := (*[syscall.MAX_PATH]uint16)(unsafe.Pointer(&raw.FileName))
name := syscall.UTF16ToString(buf[:raw.FileNameLength/2])
fullname := watch.path + "/" + name
var mask uint64
switch raw.Action {
case syscall.FILE_ACTION_REMOVED:
mask = FS_DELETE_SELF
case syscall.FILE_ACTION_MODIFIED:
mask = FS_MODIFY
case syscall.FILE_ACTION_RENAMED_OLD_NAME:
watch.rename = name
case syscall.FILE_ACTION_RENAMED_NEW_NAME:
if watch.names[watch.rename] != 0 {
watch.names[name] |= watch.names[watch.rename]
delete(watch.names, watch.rename)
mask = FS_MOVE_SELF
}
}
sendNameEvent := func() {
if w.sendEvent(fullname, watch.names[name]&mask) {
if watch.names[name]&FS_ONESHOT != 0 {
delete(watch.names, name)
}
}
}
if raw.Action != syscall.FILE_ACTION_RENAMED_NEW_NAME {
sendNameEvent()
}
if raw.Action == syscall.FILE_ACTION_REMOVED {
w.sendEvent(fullname, watch.names[name]&FS_IGNORED)
delete(watch.names, name)
}
if w.sendEvent(fullname, watch.mask&toFSnotifyFlags(raw.Action)) {
if watch.mask&FS_ONESHOT != 0 {
watch.mask = 0
}
}
if raw.Action == syscall.FILE_ACTION_RENAMED_NEW_NAME {
fullname = watch.path + "/" + watch.rename
sendNameEvent()
}
// Move to the next event in the buffer
if raw.NextEntryOffset == 0 {
break
}
offset += raw.NextEntryOffset
}
if err := w.startRead(watch); err != nil {
w.Error <- err
}
}
}
func (w *Watcher) sendEvent(name string, mask uint64) bool {
if mask == 0 {
return false
}
event := &FileEvent{mask: uint32(mask), Name: name}
if mask&FS_MOVE != 0 {
if mask&FS_MOVED_FROM != 0 {
w.cookie++
}
event.cookie = w.cookie
}
select {
case ch := <-w.quit:
w.quit <- ch
case w.Event <- event:
}
return true
}
func toWindowsFlags(mask uint64) uint32 {
var m uint32
if mask&FS_ACCESS != 0 {
m |= syscall.FILE_NOTIFY_CHANGE_LAST_ACCESS
}
if mask&FS_MODIFY != 0 {
m |= syscall.FILE_NOTIFY_CHANGE_LAST_WRITE
}
if mask&FS_ATTRIB != 0 {
m |= syscall.FILE_NOTIFY_CHANGE_ATTRIBUTES
}
if mask&(FS_MOVE|FS_CREATE|FS_DELETE) != 0 {
m |= syscall.FILE_NOTIFY_CHANGE_FILE_NAME | syscall.FILE_NOTIFY_CHANGE_DIR_NAME
}
return m
}
func toFSnotifyFlags(action uint32) uint64 {
switch action {
case syscall.FILE_ACTION_ADDED:
return FS_CREATE
case syscall.FILE_ACTION_REMOVED:
return FS_DELETE
case syscall.FILE_ACTION_MODIFIED:
return FS_MODIFY
case syscall.FILE_ACTION_RENAMED_OLD_NAME:
return FS_MOVED_FROM
case syscall.FILE_ACTION_RENAMED_NEW_NAME:
return FS_MOVED_TO
}
return 0
}
const (
// Options for AddWatch
FS_ONESHOT = 0x80000000
FS_ONLYDIR = 0x1000000
// Events
FS_ACCESS = 0x1
FS_ALL_EVENTS = 0xfff
FS_ATTRIB = 0x4
FS_CLOSE = 0x18
FS_CREATE = 0x100
FS_DELETE = 0x200
FS_DELETE_SELF = 0x400
FS_MODIFY = 0x2
FS_MOVE = 0xc0
FS_MOVED_FROM = 0x40
FS_MOVED_TO = 0x80
FS_MOVE_SELF = 0x800
// Special events
FS_IGNORED = 0x8000
FS_Q_OVERFLOW = 0x4000
)
var eventBits = []struct {
Value uint32
Name string
}{
{FS_ACCESS, "FS_ACCESS"},
{FS_ATTRIB, "FS_ATTRIB"},
{FS_CREATE, "FS_CREATE"},
{FS_DELETE, "FS_DELETE"},
{FS_DELETE_SELF, "FS_DELETE_SELF"},
{FS_MODIFY, "FS_MODIFY"},
{FS_MOVED_FROM, "FS_MOVED_FROM"},
{FS_MOVED_TO, "FS_MOVED_TO"},
{FS_MOVE_SELF, "FS_MOVE_SELF"},
{FS_IGNORED, "FS_IGNORED"},
{FS_Q_OVERFLOW, "FS_Q_OVERFLOW"},
}
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