exp/winfsnotify: filesystem watcher for Windows

R=rsc, alex.brainman, bradfitz
CC=bsiegert, go.peter.90, golang-dev
https://golang.org/cl/4188047

src/pkg/exp/winfsnotify/Makefile

@@ -0,0 +1,11 @@
+# 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.
+
+include ../../../Make.inc
+
+TARG=exp/winfsnotify
+GOFILES=\
+	winfsnotify.go\
+
+include ../../../Make.pkg

src/pkg/exp/winfsnotify/winfsnotify.go

@@ -0,0 +1,569 @@
+// 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.
+
+// Package winfsnotify allows the user to receive
+// file system event notifications on Windows.
+package winfsnotify
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"runtime"
+	"syscall"
+	"unsafe"
+)
+
+// Event is the type of the notification messages
+// received on the watcher's Event channel.
+type Event struct {
+	Mask   uint32 // Mask of events
+	Cookie uint32 // Unique cookie associating related events (for rename)
+	Name   string // File name (optional)
+}
+
+const (
+	opAddWatch = iota
+	opRemoveWatch
+)
+
+const (
+	provisional uint64 = 1 << (32 + iota)
+)
+
+type input struct {
+	op    int
+	path  string
+	flags uint32
+	reply chan os.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)
+	input    chan *input    // Inputs to the reader are sent on this channel
+	Event    chan *Event    // Events are returned on this channel
+	Error    chan os.Error  // Errors are sent on this channel
+	isClosed bool           // Set to true when Close() is first called
+	quit     chan chan<- os.Error
+	cookie   uint32
+}
+
+// NewWatcher creates and returns a Watcher.
+func NewWatcher() (*Watcher, os.Error) {
+	port, e := syscall.CreateIoCompletionPort(syscall.InvalidHandle, 0, 0, 0)
+	if e != 0 {
+		return nil, os.NewSyscallError("CreateIoCompletionPort", e)
+	}
+	w := &Watcher{
+		port:    port,
+		watches: make(watchMap),
+		input:   make(chan *input, 1),
+		Event:   make(chan *Event, 50),
+		Error:   make(chan os.Error),
+		quit:    make(chan chan<- os.Error, 1),
+	}
+	go w.readEvents()
+	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() os.Error {
+	if w.isClosed {
+		return nil
+	}
+	w.isClosed = true
+
+	// Send "quit" message to the reader goroutine
+	ch := make(chan os.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) os.Error {
+	if w.isClosed {
+		return os.NewError("watcher already closed")
+	}
+	in := &input{
+		op:    opAddWatch,
+		path:  filepath.Clean(path),
+		flags: flags,
+		reply: make(chan os.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) os.Error {
+	return w.AddWatch(path, FS_ALL_EVENTS)
+}
+
+// RemoveWatch removes path from the watched file set.
+func (w *Watcher) RemoveWatch(path string) os.Error {
+	in := &input{
+		op:    opRemoveWatch,
+		path:  filepath.Clean(path),
+		reply: make(chan os.Error),
+	}
+	w.input <- in
+	if err := w.wakeupReader(); err != nil {
+		return err
+	}
+	return <-in.reply
+}
+
+func (w *Watcher) wakeupReader() os.Error {
+	e := syscall.PostQueuedCompletionStatus(w.port, 0, 0, nil)
+	if e != 0 {
+		return os.NewSyscallError("PostQueuedCompletionStatus", e)
+	}
+	return nil
+}
+
+func getDir(pathname string) (dir string, err os.Error) {
+	attr, e := syscall.GetFileAttributes(syscall.StringToUTF16Ptr(pathname))
+	if e != 0 {
+		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 os.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 != 0 {
+		return nil, os.NewSyscallError("CreateFile", e)
+	}
+	var fi syscall.ByHandleFileInformation
+	if e = syscall.GetFileInformationByHandle(h, &fi); e != 0 {
+		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) os.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 != 0 {
+			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) removeWatch(pathname string) os.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) os.Error {
+	if e := syscall.CancelIo(watch.ino.handle); e != 0 {
+		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 != 0 {
+			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 != 0 {
+		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 os.Error
+				if e := syscall.CloseHandle(w.port); e != 0 {
+					err = os.NewSyscallError("CloseHandle", e)
+				}
+				close(w.Event)
+				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.removeWatch(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 0:
+		}
+
+		var offset uint32
+		for {
+			if n == 0 {
+				w.Event <- &Event{Mask: FS_Q_OVERFLOW}
+				w.Error <- os.NewError("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 := &Event{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
+}
+
+// String formats the event e in the form
+// "filename: 0xEventMask = FS_ACCESS|FS_ATTRIB_|..."
+func (e *Event) String() string {
+	var events string
+	m := e.Mask
+	for _, b := range eventBits {
+		if m&b.Value != 0 {
+			m &^= b.Value
+			events += "|" + b.Name
+		}
+	}
+	if m != 0 {
+		events += fmt.Sprintf("|%#x", m)
+	}
+	if len(events) > 0 {
+		events = " == " + events[1:]
+	}
+	return fmt.Sprintf("%q: %#x%s", e.Name, e.Mask, events)
+}
+
+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"},
+}

src/pkg/exp/winfsnotify/winfsnotify_test.go

@@ -0,0 +1,124 @@
+// 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.
+
+package winfsnotify
+
+import (
+	"os"
+	"time"
+	"testing"
+)
+
+func expect(t *testing.T, eventstream <-chan *Event, name string, mask uint32) {
+	t.Logf(`expected: "%s": 0x%x`, name, mask)
+	select {
+	case event := <-eventstream:
+		if event == nil {
+			t.Fatal("nil event received")
+		}
+		t.Logf("received: %s", event)
+		if event.Name != name || event.Mask != mask {
+			t.Fatal("did not receive expected event")
+		}
+	case <-time.After(1e9):
+		t.Fatal("timed out waiting for event")
+	}
+}
+
+func TestNotifyEvents(t *testing.T) {
+	watcher, err := NewWatcher()
+	if err != nil {
+		t.Fatalf("NewWatcher() failed: %s", err)
+	}
+
+	testDir := "TestNotifyEvents.testdirectory"
+	testFile := testDir + "/TestNotifyEvents.testfile"
+	testFile2 := testFile + ".new"
+	const mask = FS_ALL_EVENTS & ^(FS_ATTRIB|FS_CLOSE) | FS_IGNORED
+
+	// Add a watch for testDir
+	os.RemoveAll(testDir)
+	if err = os.Mkdir(testDir, 0777); err != nil {
+		t.Fatalf("Failed to create test directory", err)
+	}
+	defer os.RemoveAll(testDir)
+	err = watcher.AddWatch(testDir, mask)
+	if err != nil {
+		t.Fatalf("Watcher.Watch() failed: %s", err)
+	}
+
+	// Receive errors on the error channel on a separate goroutine
+	go func() {
+		for err := range watcher.Error {
+			t.Fatalf("error received: %s", err)
+		}
+	}()
+
+	// Create a file
+	file, err := os.Create(testFile)
+	if err != nil {
+		t.Fatalf("creating test file failed: %s", err)
+	}
+	expect(t, watcher.Event, testFile, FS_CREATE)
+
+	err = watcher.AddWatch(testFile, mask)
+	if err != nil {
+		t.Fatalf("Watcher.Watch() failed: %s", err)
+	}
+
+	if _, err = file.WriteString("hello, world"); err != nil {
+		t.Fatalf("failed to write to test file: %s", err)
+	}
+	if err = file.Sync(); err != nil {
+		t.Fatalf("failed to sync test file: %s", err)
+	}
+	expect(t, watcher.Event, testFile, FS_MODIFY)
+	expect(t, watcher.Event, testFile, FS_MODIFY)
+
+	if err = file.Close(); err != nil {
+		t.Fatalf("failed to close test file: %s", err)
+	}
+
+	if err = os.Rename(testFile, testFile2); err != nil {
+		t.Fatalf("failed to rename test file: %s", err)
+	}
+	expect(t, watcher.Event, testFile, FS_MOVED_FROM)
+	expect(t, watcher.Event, testFile2, FS_MOVED_TO)
+	expect(t, watcher.Event, testFile, FS_MOVE_SELF)
+
+	if err = os.RemoveAll(testDir); err != nil {
+		t.Fatalf("failed to remove test directory: %s", err)
+	}
+	expect(t, watcher.Event, testFile2, FS_DELETE_SELF)
+	expect(t, watcher.Event, testFile2, FS_IGNORED)
+	expect(t, watcher.Event, testFile2, FS_DELETE)
+	expect(t, watcher.Event, testDir, FS_DELETE_SELF)
+	expect(t, watcher.Event, testDir, FS_IGNORED)
+
+	t.Log("calling Close()")
+	if err = watcher.Close(); err != nil {
+		t.Fatalf("failed to close watcher: %s", err)
+	}
+}
+
+func TestNotifyClose(t *testing.T) {
+	watcher, _ := NewWatcher()
+	watcher.Close()
+
+	done := false
+	go func() {
+		watcher.Close()
+		done = true
+	}()
+
+	time.Sleep(50e6) // 50 ms
+	if !done {
+		t.Fatal("double Close() test failed: second Close() call didn't return")
+	}
+
+	err := watcher.Watch("_test")
+	if err == nil {
+		t.Fatal("expected error on Watch() after Close(), got nil")
+	}
+}

src/pkg/syscall/syscall_windows.go

@@ -114,6 +114,7 @@ func NewCallback(fn interface{}) uintptr
 //sys	GetTimeZoneInformation(tzi *Timezoneinformation) (rc uint32, errno int) [failretval==0xffffffff]
 //sys	CreateIoCompletionPort(filehandle Handle, cphandle Handle, key uint32, threadcnt uint32) (handle Handle, errno int)
 //sys	GetQueuedCompletionStatus(cphandle Handle, qty *uint32, key *uint32, overlapped **Overlapped, timeout uint32) (errno int)
+//sys	PostQueuedCompletionStatus(cphandle Handle, qty uint32, key uint32, overlapped *Overlapped) (errno int)
 //sys	CancelIo(s Handle) (errno int)
 //sys	CreateProcess(appName *uint16, commandLine *uint16, procSecurity *SecurityAttributes, threadSecurity *SecurityAttributes, inheritHandles bool, creationFlags uint32, env *uint16, currentDir *uint16, startupInfo *StartupInfo, outProcInfo *ProcessInformation) (errno int) = CreateProcessW
 //sys	OpenProcess(da uint32, inheritHandle bool, pid uint32) (handle Handle, errno int)
@@ -150,6 +151,7 @@ func NewCallback(fn interface{}) uintptr
 //sys	VirtualLock(addr uintptr, length uintptr) (errno int)
 //sys	VirtualUnlock(addr uintptr, length uintptr) (errno int)
 //sys	TransmitFile(s Handle, handle Handle, bytesToWrite uint32, bytsPerSend uint32, overlapped *Overlapped, transmitFileBuf *TransmitFileBuffers, flags uint32) (errno int) = mswsock.TransmitFile
+//sys	ReadDirectoryChanges(handle Handle, buf *byte, buflen uint32, watchSubTree bool, mask uint32, retlen *uint32, overlapped *Overlapped, completionRoutine uintptr) (errno int) = kernel32.ReadDirectoryChangesW
 //sys	CertOpenSystemStore(hprov Handle, name *uint16) (store Handle, errno int) = crypt32.CertOpenSystemStoreW
 //sys	CertEnumCertificatesInStore(store Handle, prevContext *CertContext) (context *CertContext) = crypt32.CertEnumCertificatesInStore
 //sys	CertCloseStore(store Handle, flags uint32) (errno int) = crypt32.CertCloseStore

src/pkg/syscall/zsyscall_windows_386.go

@@ -45,6 +45,7 @@ var (
 	procGetTimeZoneInformation      = modkernel32.NewProc("GetTimeZoneInformation")
 	procCreateIoCompletionPort      = modkernel32.NewProc("CreateIoCompletionPort")
 	procGetQueuedCompletionStatus   = modkernel32.NewProc("GetQueuedCompletionStatus")
+	procPostQueuedCompletionStatus  = modkernel32.NewProc("PostQueuedCompletionStatus")
 	procCancelIo                    = modkernel32.NewProc("CancelIo")
 	procCreateProcessW              = modkernel32.NewProc("CreateProcessW")
 	procOpenProcess                 = modkernel32.NewProc("OpenProcess")
@@ -81,6 +82,7 @@ var (
 	procVirtualLock                 = modkernel32.NewProc("VirtualLock")
 	procVirtualUnlock               = modkernel32.NewProc("VirtualUnlock")
 	procTransmitFile                = modmswsock.NewProc("TransmitFile")
+	procReadDirectoryChangesW       = modkernel32.NewProc("ReadDirectoryChangesW")
 	procCertOpenSystemStoreW        = modcrypt32.NewProc("CertOpenSystemStoreW")
 	procCertEnumCertificatesInStore = modcrypt32.NewProc("CertEnumCertificatesInStore")
 	procCertCloseStore              = modcrypt32.NewProc("CertCloseStore")
@@ -520,6 +522,20 @@ func GetQueuedCompletionStatus(cphandle Handle, qty *uint32, key *uint32, overla
 	return
 }
 
+func PostQueuedCompletionStatus(cphandle Handle, qty uint32, key uint32, overlapped *Overlapped) (errno int) {
+	r1, _, e1 := Syscall6(procPostQueuedCompletionStatus.Addr(), 4, uintptr(cphandle), uintptr(qty), uintptr(key), uintptr(unsafe.Pointer(overlapped)), 0, 0)
+	if int(r1) == 0 {
+		if e1 != 0 {
+			errno = int(e1)
+		} else {
+			errno = EINVAL
+		}
+	} else {
+		errno = 0
+	}
+	return
+}
+
 func CancelIo(s Handle) (errno int) {
 	r1, _, e1 := Syscall(procCancelIo.Addr(), 1, uintptr(s), 0, 0)
 	if int(r1) == 0 {
@@ -1047,6 +1063,26 @@ func TransmitFile(s Handle, handle Handle, bytesToWrite uint32, bytsPerSend uint
 	return
 }
 
+func ReadDirectoryChanges(handle Handle, buf *byte, buflen uint32, watchSubTree bool, mask uint32, retlen *uint32, overlapped *Overlapped, completionRoutine uintptr) (errno int) {
+	var _p0 uint32
+	if watchSubTree {
+		_p0 = 1
+	} else {
+		_p0 = 0
+	}
+	r1, _, e1 := Syscall9(procReadDirectoryChangesW.Addr(), 8, uintptr(handle), uintptr(unsafe.Pointer(buf)), uintptr(buflen), uintptr(_p0), uintptr(mask), uintptr(unsafe.Pointer(retlen)), uintptr(unsafe.Pointer(overlapped)), uintptr(completionRoutine), 0)
+	if int(r1) == 0 {
+		if e1 != 0 {
+			errno = int(e1)
+		} else {
+			errno = EINVAL
+		}
+	} else {
+		errno = 0
+	}
+	return
+}
+
 func CertOpenSystemStore(hprov Handle, name *uint16) (store Handle, errno int) {
 	r0, _, e1 := Syscall(procCertOpenSystemStoreW.Addr(), 2, uintptr(hprov), uintptr(unsafe.Pointer(name)), 0)
 	store = Handle(r0)

src/pkg/syscall/zsyscall_windows_amd64.go

@@ -45,6 +45,7 @@ var (
 	procGetTimeZoneInformation      = modkernel32.NewProc("GetTimeZoneInformation")
 	procCreateIoCompletionPort      = modkernel32.NewProc("CreateIoCompletionPort")
 	procGetQueuedCompletionStatus   = modkernel32.NewProc("GetQueuedCompletionStatus")
+	procPostQueuedCompletionStatus  = modkernel32.NewProc("PostQueuedCompletionStatus")
 	procCancelIo                    = modkernel32.NewProc("CancelIo")
 	procCreateProcessW              = modkernel32.NewProc("CreateProcessW")
 	procOpenProcess                 = modkernel32.NewProc("OpenProcess")
@@ -81,6 +82,7 @@ var (
 	procVirtualLock                 = modkernel32.NewProc("VirtualLock")
 	procVirtualUnlock               = modkernel32.NewProc("VirtualUnlock")
 	procTransmitFile                = modmswsock.NewProc("TransmitFile")
+	procReadDirectoryChangesW       = modkernel32.NewProc("ReadDirectoryChangesW")
 	procCertOpenSystemStoreW        = modcrypt32.NewProc("CertOpenSystemStoreW")
 	procCertEnumCertificatesInStore = modcrypt32.NewProc("CertEnumCertificatesInStore")
 	procCertCloseStore              = modcrypt32.NewProc("CertCloseStore")
@@ -520,6 +522,20 @@ func GetQueuedCompletionStatus(cphandle Handle, qty *uint32, key *uint32, overla
 	return
 }
 
+func PostQueuedCompletionStatus(cphandle Handle, qty uint32, key uint32, overlapped *Overlapped) (errno int) {
+	r1, _, e1 := Syscall6(procPostQueuedCompletionStatus.Addr(), 4, uintptr(cphandle), uintptr(qty), uintptr(key), uintptr(unsafe.Pointer(overlapped)), 0, 0)
+	if int(r1) == 0 {
+		if e1 != 0 {
+			errno = int(e1)
+		} else {
+			errno = EINVAL
+		}
+	} else {
+		errno = 0
+	}
+	return
+}
+
 func CancelIo(s Handle) (errno int) {
 	r1, _, e1 := Syscall(procCancelIo.Addr(), 1, uintptr(s), 0, 0)
 	if int(r1) == 0 {
@@ -1047,6 +1063,26 @@ func TransmitFile(s Handle, handle Handle, bytesToWrite uint32, bytsPerSend uint
 	return
 }
 
+func ReadDirectoryChanges(handle Handle, buf *byte, buflen uint32, watchSubTree bool, mask uint32, retlen *uint32, overlapped *Overlapped, completionRoutine uintptr) (errno int) {
+	var _p0 uint32
+	if watchSubTree {
+		_p0 = 1
+	} else {
+		_p0 = 0
+	}
+	r1, _, e1 := Syscall9(procReadDirectoryChangesW.Addr(), 8, uintptr(handle), uintptr(unsafe.Pointer(buf)), uintptr(buflen), uintptr(_p0), uintptr(mask), uintptr(unsafe.Pointer(retlen)), uintptr(unsafe.Pointer(overlapped)), uintptr(completionRoutine), 0)
+	if int(r1) == 0 {
+		if e1 != 0 {
+			errno = int(e1)
+		} else {
+			errno = EINVAL
+		}
+	} else {
+		errno = 0
+	}
+	return
+}
+
 func CertOpenSystemStore(hprov Handle, name *uint16) (store Handle, errno int) {
 	r0, _, e1 := Syscall(procCertOpenSystemStoreW.Addr(), 2, uintptr(hprov), uintptr(unsafe.Pointer(name)), 0)
 	store = Handle(r0)

src/pkg/syscall/ztypes_windows.go

@@ -4,6 +4,7 @@ const (
 	// Windows errors.
 	ERROR_FILE_NOT_FOUND      = 2
 	ERROR_PATH_NOT_FOUND      = 3
+	ERROR_ACCESS_DENIED       = 5
 	ERROR_NO_MORE_FILES       = 18
 	ERROR_BROKEN_PIPE         = 109
 	ERROR_BUFFER_OVERFLOW     = 111
@@ -54,6 +55,7 @@ const (
 	GENERIC_EXECUTE = 0x20000000
 	GENERIC_ALL     = 0x10000000
 
+	FILE_LIST_DIRECTORY   = 0x00000001
 	FILE_APPEND_DATA      = 0x00000004
 	FILE_WRITE_ATTRIBUTES = 0x00000100
 
@@ -75,6 +77,9 @@ const (
 	OPEN_ALWAYS       = 4
 	TRUNCATE_EXISTING = 5
 
+	FILE_FLAG_BACKUP_SEMANTICS = 0x02000000
+	FILE_FLAG_OVERLAPPED       = 0x40000000
+
 	HANDLE_FLAG_INHERIT    = 0x00000001
 	STARTF_USESTDHANDLES   = 0x00000100
 	STARTF_USESHOWWINDOW   = 0x00000001
@@ -133,6 +138,24 @@ const (
 	FILE_MAP_EXECUTE = 0x20
 )
 
+const (
+	FILE_NOTIFY_CHANGE_FILE_NAME = 1 << iota
+	FILE_NOTIFY_CHANGE_DIR_NAME
+	FILE_NOTIFY_CHANGE_ATTRIBUTES
+	FILE_NOTIFY_CHANGE_SIZE
+	FILE_NOTIFY_CHANGE_LAST_WRITE
+	FILE_NOTIFY_CHANGE_LAST_ACCESS
+	FILE_NOTIFY_CHANGE_CREATION
+)
+
+const (
+	FILE_ACTION_ADDED = iota + 1
+	FILE_ACTION_REMOVED
+	FILE_ACTION_MODIFIED
+	FILE_ACTION_RENAMED_OLD_NAME
+	FILE_ACTION_RENAMED_NEW_NAME
+)
+
 const (
 	// wincrypt.h
 	PROV_RSA_FULL                    = 1
@@ -191,6 +214,13 @@ type Overlapped struct {
 	HEvent       Handle
 }
 
+type FileNotifyInformation struct {
+	NextEntryOffset uint32
+	Action          uint32
+	FileNameLength  uint32
+	FileName        uint16
+}
+
 type Filetime struct {
 	LowDateTime  uint32
 	HighDateTime uint32