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windows: replace syscall with golang.org/x/sys/windows
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Specifically to address #364; syscall.GetQueuedCompletionStatus()
contains a bug that can't be fixed in a backwards-compatible way, so
they didn't. Once you use sys/windows for one thing, you gotta use it
for everything.

I ran the tests with -count=100 locally, and it all seems fine.

Fixes #364
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@arp242
arp242 committed Aug 4, 2022
1 parent 1f8edaf commit 5dcbfba
Showing 1 changed file with 52 additions and 50 deletions.
102 changes: 52 additions & 50 deletions windows.go
View file
Expand Up @@ -16,16 +16,17 @@ import (
"runtime"
"strings"
"sync"
"syscall"
"unsafe"

"golang.org/x/sys/windows"
)

// Watcher watches a set of files, delivering events to a channel.
type Watcher struct {
Events chan Event
Errors chan error

port syscall.Handle // Handle to completion port
port windows.Handle // Handle to completion port
input chan *input // Inputs to the reader are sent on this channel
quit chan chan<- error

Expand All @@ -36,7 +37,7 @@ type Watcher struct {

// NewWatcher establishes a new watcher with the underlying OS and begins waiting for events.
func NewWatcher() (*Watcher, error) {
port, err := syscall.CreateIoCompletionPort(syscall.InvalidHandle, 0, 0, 0)
port, err := windows.CreateIoCompletionPort(windows.InvalidHandle, 0, 0, 0)
if err != nil {
return nil, os.NewSyscallError("CreateIoCompletionPort", err)
}
Expand Down Expand Up @@ -183,13 +184,13 @@ type input struct {
}

type inode struct {
handle syscall.Handle
handle windows.Handle
volume uint32
index uint64
}

type watch struct {
ov syscall.Overlapped
ov windows.Overlapped
ino *inode // i-number
path string // Directory path
mask uint64 // Directory itself is being watched with these notify flags
Expand All @@ -204,19 +205,19 @@ type (
)

func (w *Watcher) wakeupReader() error {
err := syscall.PostQueuedCompletionStatus(w.port, 0, 0, nil)
err := windows.PostQueuedCompletionStatus(w.port, 0, 0, nil)
if err != nil {
return os.NewSyscallError("PostQueuedCompletionStatus", err)
}
return nil
}

func getDir(pathname string) (dir string, err error) {
attr, err := syscall.GetFileAttributes(syscall.StringToUTF16Ptr(pathname))
attr, err := windows.GetFileAttributes(windows.StringToUTF16Ptr(pathname))
if err != nil {
return "", os.NewSyscallError("GetFileAttributes", err)
}
if attr&syscall.FILE_ATTRIBUTE_DIRECTORY != 0 {
if attr&windows.FILE_ATTRIBUTE_DIRECTORY != 0 {
dir = pathname
} else {
dir, _ = filepath.Split(pathname)
Expand All @@ -226,19 +227,19 @@ func getDir(pathname string) (dir string, err error) {
}

func getIno(path string) (ino *inode, err error) {
h, err := 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)
h, err := windows.CreateFile(windows.StringToUTF16Ptr(path),
windows.FILE_LIST_DIRECTORY,
windows.FILE_SHARE_READ|windows.FILE_SHARE_WRITE|windows.FILE_SHARE_DELETE,
nil, windows.OPEN_EXISTING,
windows.FILE_FLAG_BACKUP_SEMANTICS|windows.FILE_FLAG_OVERLAPPED, 0)
if err != nil {
return nil, os.NewSyscallError("CreateFile", err)
}

var fi syscall.ByHandleFileInformation
err = syscall.GetFileInformationByHandle(h, &fi)
var fi windows.ByHandleFileInformation
err = windows.GetFileInformationByHandle(h, &fi)
if err != nil {
syscall.CloseHandle(h)
windows.CloseHandle(h)
return nil, os.NewSyscallError("GetFileInformationByHandle", err)
}
ino = &inode{
Expand Down Expand Up @@ -285,9 +286,9 @@ func (w *Watcher) addWatch(pathname string, flags uint64) error {
watchEntry := w.watches.get(ino)
w.mu.Unlock()
if watchEntry == nil {
_, err := syscall.CreateIoCompletionPort(ino.handle, w.port, 0, 0)
_, err := windows.CreateIoCompletionPort(ino.handle, w.port, 0, 0)
if err != nil {
syscall.CloseHandle(ino.handle)
windows.CloseHandle(ino.handle)
return os.NewSyscallError("CreateIoCompletionPort", err)
}
watchEntry = &watch{
Expand All @@ -300,7 +301,7 @@ func (w *Watcher) addWatch(pathname string, flags uint64) error {
w.mu.Unlock()
flags |= provisional
} else {
syscall.CloseHandle(ino.handle)
windows.CloseHandle(ino.handle)
}
if pathname == dir {
watchEntry.mask |= flags
Expand Down Expand Up @@ -336,7 +337,7 @@ func (w *Watcher) remWatch(pathname string) error {
watch := w.watches.get(ino)
w.mu.Unlock()

err = syscall.CloseHandle(ino.handle)
err = windows.CloseHandle(ino.handle)
if err != nil {
w.Errors <- os.NewSyscallError("CloseHandle", err)
}
Expand Down Expand Up @@ -372,7 +373,7 @@ func (w *Watcher) deleteWatch(watch *watch) {

// Must run within the I/O thread.
func (w *Watcher) startRead(watch *watch) error {
err := syscall.CancelIo(watch.ino.handle)
err := windows.CancelIo(watch.ino.handle)
if err != nil {
w.Errors <- os.NewSyscallError("CancelIo", err)
w.deleteWatch(watch)
Expand All @@ -382,7 +383,7 @@ func (w *Watcher) startRead(watch *watch) error {
mask |= toWindowsFlags(m)
}
if mask == 0 {
err := syscall.CloseHandle(watch.ino.handle)
err := windows.CloseHandle(watch.ino.handle)
if err != nil {
w.Errors <- os.NewSyscallError("CloseHandle", err)
}
Expand All @@ -392,11 +393,11 @@ func (w *Watcher) startRead(watch *watch) error {
return nil
}

rdErr := syscall.ReadDirectoryChanges(watch.ino.handle, &watch.buf[0],
rdErr := windows.ReadDirectoryChanges(watch.ino.handle, &watch.buf[0],
uint32(unsafe.Sizeof(watch.buf)), false, mask, nil, &watch.ov, 0)
if rdErr != nil {
err := os.NewSyscallError("ReadDirectoryChanges", rdErr)
if rdErr == syscall.ERROR_ACCESS_DENIED && watch.mask&provisional == 0 {
if rdErr == windows.ERROR_ACCESS_DENIED && watch.mask&provisional == 0 {
// Watched directory was probably removed
if w.sendEvent(watch.path, watch.mask&sysFSDELETESELF) {
if watch.mask&sysFSONESHOT != 0 {
Expand All @@ -417,13 +418,14 @@ func (w *Watcher) startRead(watch *watch) error {
// Entry point to the I/O thread.
func (w *Watcher) readEvents() {
var (
n, key uint32
ov *syscall.Overlapped
n uint32
key uintptr
ov *windows.Overlapped
)
runtime.LockOSThread()

for {
qErr := syscall.GetQueuedCompletionStatus(w.port, &n, &key, &ov, syscall.INFINITE)
qErr := windows.GetQueuedCompletionStatus(w.port, &n, &key, &ov, windows.INFINITE)
// This error is handled after the watch == nil check below. NOTE: this
// seems odd, note sure if it's correct.

Expand All @@ -444,7 +446,7 @@ func (w *Watcher) readEvents() {
}
}

err := syscall.CloseHandle(w.port)
err := windows.CloseHandle(w.port)
if err != nil {
err = os.NewSyscallError("CloseHandle", err)
}
Expand All @@ -465,7 +467,7 @@ func (w *Watcher) readEvents() {
}

switch qErr {
case syscall.ERROR_MORE_DATA:
case windows.ERROR_MORE_DATA:
if watch == nil {
w.Errors <- errors.New("ERROR_MORE_DATA has unexpectedly null lpOverlapped buffer")
} else {
Expand All @@ -474,13 +476,13 @@ func (w *Watcher) readEvents() {
// In practice we can get away with just carrying on.
n = uint32(unsafe.Sizeof(watch.buf))
}
case syscall.ERROR_ACCESS_DENIED:
case windows.ERROR_ACCESS_DENIED:
// Watched directory was probably removed
w.sendEvent(watch.path, watch.mask&sysFSDELETESELF)
w.deleteWatch(watch)
w.startRead(watch)
continue
case syscall.ERROR_OPERATION_ABORTED:
case windows.ERROR_OPERATION_ABORTED:
// CancelIo was called on this handle
continue
default:
Expand All @@ -498,28 +500,28 @@ func (w *Watcher) readEvents() {
}

// Point "raw" to the event in the buffer
raw := (*syscall.FileNotifyInformation)(unsafe.Pointer(&watch.buf[offset]))
raw := (*windows.FileNotifyInformation)(unsafe.Pointer(&watch.buf[offset]))
// TODO: Consider using unsafe.Slice that is available from go1.17
// https://stackoverflow.com/questions/51187973/how-to-create-an-array-or-a-slice-from-an-array-unsafe-pointer-in-golang
// instead of using a fixed syscall.MAX_PATH buf, we create a buf that is the size of the path name
// instead of using a fixed windows.MAX_PATH buf, we create a buf that is the size of the path name
size := int(raw.FileNameLength / 2)
var buf []uint16
sh := (*reflect.SliceHeader)(unsafe.Pointer(&buf))
sh.Data = uintptr(unsafe.Pointer(&raw.FileName))
sh.Len = size
sh.Cap = size
name := syscall.UTF16ToString(buf)
name := windows.UTF16ToString(buf)
fullname := filepath.Join(watch.path, name)

var mask uint64
switch raw.Action {
case syscall.FILE_ACTION_REMOVED:
case windows.FILE_ACTION_REMOVED:
mask = sysFSDELETESELF
case syscall.FILE_ACTION_MODIFIED:
case windows.FILE_ACTION_MODIFIED:
mask = sysFSMODIFY
case syscall.FILE_ACTION_RENAMED_OLD_NAME:
case windows.FILE_ACTION_RENAMED_OLD_NAME:
watch.rename = name
case syscall.FILE_ACTION_RENAMED_NEW_NAME:
case windows.FILE_ACTION_RENAMED_NEW_NAME:
// Update saved path of all sub-watches.
old := filepath.Join(watch.path, watch.rename)
w.mu.Lock()
Expand All @@ -546,10 +548,10 @@ func (w *Watcher) readEvents() {
}
}
}
if raw.Action != syscall.FILE_ACTION_RENAMED_NEW_NAME {
if raw.Action != windows.FILE_ACTION_RENAMED_NEW_NAME {
sendNameEvent()
}
if raw.Action == syscall.FILE_ACTION_REMOVED {
if raw.Action == windows.FILE_ACTION_REMOVED {
w.sendEvent(fullname, watch.names[name]&sysFSIGNORED)
delete(watch.names, name)
}
Expand All @@ -558,7 +560,7 @@ func (w *Watcher) readEvents() {
watch.mask = 0
}
}
if raw.Action == syscall.FILE_ACTION_RENAMED_NEW_NAME {
if raw.Action == windows.FILE_ACTION_RENAMED_NEW_NAME {
fullname = filepath.Join(watch.path, watch.rename)
sendNameEvent()
}
Expand Down Expand Up @@ -598,31 +600,31 @@ func (w *Watcher) sendEvent(name string, mask uint64) bool {
func toWindowsFlags(mask uint64) uint32 {
var m uint32
if mask&sysFSACCESS != 0 {
m |= syscall.FILE_NOTIFY_CHANGE_LAST_ACCESS
m |= windows.FILE_NOTIFY_CHANGE_LAST_ACCESS
}
if mask&sysFSMODIFY != 0 {
m |= syscall.FILE_NOTIFY_CHANGE_LAST_WRITE
m |= windows.FILE_NOTIFY_CHANGE_LAST_WRITE
}
if mask&sysFSATTRIB != 0 {
m |= syscall.FILE_NOTIFY_CHANGE_ATTRIBUTES
m |= windows.FILE_NOTIFY_CHANGE_ATTRIBUTES
}
if mask&(sysFSMOVE|sysFSCREATE|sysFSDELETE) != 0 {
m |= syscall.FILE_NOTIFY_CHANGE_FILE_NAME | syscall.FILE_NOTIFY_CHANGE_DIR_NAME
m |= windows.FILE_NOTIFY_CHANGE_FILE_NAME | windows.FILE_NOTIFY_CHANGE_DIR_NAME
}
return m
}

func toFSnotifyFlags(action uint32) uint64 {
switch action {
case syscall.FILE_ACTION_ADDED:
case windows.FILE_ACTION_ADDED:
return sysFSCREATE
case syscall.FILE_ACTION_REMOVED:
case windows.FILE_ACTION_REMOVED:
return sysFSDELETE
case syscall.FILE_ACTION_MODIFIED:
case windows.FILE_ACTION_MODIFIED:
return sysFSMODIFY
case syscall.FILE_ACTION_RENAMED_OLD_NAME:
case windows.FILE_ACTION_RENAMED_OLD_NAME:
return sysFSMOVEDFROM
case syscall.FILE_ACTION_RENAMED_NEW_NAME:
case windows.FILE_ACTION_RENAMED_NEW_NAME:
return sysFSMOVEDTO
}
return 0
Expand Down

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