import (
"errors"
+ "fmt"
+ "os"
+ "path/filepath"
+ "sync"
+
+ "golang.org/x/sys/unix"
)
// Watcher watches a set of paths, delivering events on a channel.
// Errors sends any errors.
Errors chan error
+
+ mu sync.Mutex
+ port *unix.EventPort
+ done chan struct{} // Channel for sending a "quit message" to the reader goroutine
+ dirs map[string]struct{} // Explicitly watched directories
+ watches map[string]struct{} // Explicitly watched non-directories
}
// NewWatcher creates a new Watcher.
func NewWatcher() (*Watcher, error) {
- return nil, errors.New("FEN based watcher not yet supported for fsnotify\n")
+ w := &Watcher{
+ Events: make(chan Event),
+ Errors: make(chan error),
+ dirs: make(map[string]struct{}),
+ watches: make(map[string]struct{}),
+ done: make(chan struct{}),
+ }
+
+ var err error
+ w.port, err = unix.NewEventPort()
+ if err != nil {
+ return nil, fmt.Errorf("fsnotify.NewWatcher: %w", err)
+ }
+
+ go w.readEvents()
+ return w, nil
+}
+
+// sendEvent attempts to send an event to the user, returning true if the event
+// was put in the channel successfully and false if the watcher has been closed.
+func (w *Watcher) sendEvent(e Event) (sent bool) {
+ select {
+ case w.Events <- e:
+ return true
+ case <-w.done:
+ return false
+ }
+}
+
+// sendError attempts to send an error to the user, returning true if the error
+// was put in the channel successfully and false if the watcher has been closed.
+func (w *Watcher) sendError(err error) (sent bool) {
+ select {
+ case w.Errors <- err:
+ return true
+ case <-w.done:
+ return false
+ }
+}
+
+func (w *Watcher) isClosed() bool {
+ select {
+ case <-w.done:
+ return true
+ default:
+ return false
+ }
}
// Close removes all watches and closes the events channel.
func (w *Watcher) Close() error {
- return nil
+ // Take the lock used by associateFile to prevent
+ // lingering events from being processed after the close
+ w.mu.Lock()
+ defer w.mu.Unlock()
+ if w.isClosed() {
+ return nil
+ }
+ close(w.done)
+ return w.port.Close()
}
// Add starts monitoring the path for changes.
// Instead, watch the parent directory and use Event.Name to filter out files
// you're not interested in. There is an example of this in [cmd/fsnotify/file.go].
func (w *Watcher) Add(name string) error {
+ if w.isClosed() {
+ return errors.New("FEN watcher already closed")
+ }
+ if w.port.PathIsWatched(name) {
+ return nil
+ }
+
+ // Currently we resolve symlinks that were explicitly requested to be
+ // watched. Otherwise we would use LStat here.
+ stat, err := os.Stat(name)
+ if err != nil {
+ return err
+ }
+
+ // Associate all files in the directory.
+ if stat.IsDir() {
+ err := w.handleDirectory(name, stat, true, w.associateFile)
+ if err != nil {
+ return err
+ }
+
+ w.mu.Lock()
+ w.dirs[name] = struct{}{}
+ w.mu.Unlock()
+ return nil
+ }
+
+ err = w.associateFile(name, stat, true)
+ if err != nil {
+ return err
+ }
+
+ w.mu.Lock()
+ w.watches[name] = struct{}{}
+ w.mu.Unlock()
return nil
}
//
// Removing a path that has not yet been added returns [ErrNonExistentWatch].
func (w *Watcher) Remove(name string) error {
+ if w.isClosed() {
+ return errors.New("FEN watcher already closed")
+ }
+ if !w.port.PathIsWatched(name) {
+ return fmt.Errorf("%w: %s", ErrNonExistentWatch, name)
+ }
+
+ // The user has expressed an intent. Immediately remove this name
+ // from whichever watch list it might be in. If it's not in there
+ // the delete doesn't cause harm.
+ w.mu.Lock()
+ delete(w.watches, name)
+ delete(w.dirs, name)
+ w.mu.Unlock()
+
+ stat, err := os.Stat(name)
+ if err != nil {
+ return err
+ }
+
+ // Remove associations for every file in the directory.
+ if stat.IsDir() {
+ err := w.handleDirectory(name, stat, false, w.dissociateFile)
+ if err != nil {
+ return err
+ }
+ return nil
+ }
+
+ err = w.port.DissociatePath(name)
+ if err != nil {
+ return err
+ }
+
+ return nil
+}
+
+// readEvents contains the main loop that runs in a goroutine watching for events.
+func (w *Watcher) readEvents() {
+ // If this function returns, the watcher has been closed and we can
+ // close these channels
+ defer func() {
+ close(w.Errors)
+ close(w.Events)
+ }()
+
+ pevents := make([]unix.PortEvent, 8)
+ for {
+ count, err := w.port.Get(pevents, 1, nil)
+ if err != nil && err != unix.ETIME {
+ // Interrupted system call (count should be 0) ignore and continue
+ if errors.Is(err, unix.EINTR) && count == 0 {
+ continue
+ }
+ // Get failed because we called w.Close()
+ if errors.Is(err, unix.EBADF) && w.isClosed() {
+ return
+ }
+ // There was an error not caused by calling w.Close()
+ if !w.sendError(err) {
+ return
+ }
+ }
+
+ p := pevents[:count]
+ for _, pevent := range p {
+ if pevent.Source != unix.PORT_SOURCE_FILE {
+ // Event from unexpected source received; should never happen.
+ if !w.sendError(errors.New("Event from unexpected source received")) {
+ return
+ }
+ continue
+ }
+
+ err = w.handleEvent(&pevent)
+ if err != nil {
+ if !w.sendError(err) {
+ return
+ }
+ }
+ }
+ }
+}
+
+func (w *Watcher) handleDirectory(path string, stat os.FileInfo, follow bool, handler func(string, os.FileInfo, bool) error) error {
+ files, err := os.ReadDir(path)
+ if err != nil {
+ return err
+ }
+
+ // Handle all children of the directory.
+ for _, entry := range files {
+ finfo, err := entry.Info()
+ if err != nil {
+ return err
+ }
+ err = handler(filepath.Join(path, finfo.Name()), finfo, false)
+ if err != nil {
+ return err
+ }
+ }
+
+ // And finally handle the directory itself.
+ return handler(path, stat, follow)
+}
+
+// handleEvent might need to emit more than one fsnotify event
+// if the events bitmap matches more than one event type
+// (e.g. the file was both modified and had the
+// attributes changed between when the association
+// was created and the when event was returned)
+func (w *Watcher) handleEvent(event *unix.PortEvent) error {
+ var (
+ events = event.Events
+ path = event.Path
+ fmode = event.Cookie.(os.FileMode)
+ reRegister = true
+ )
+
+ w.mu.Lock()
+ _, watchedDir := w.dirs[path]
+ _, watchedPath := w.watches[path]
+ w.mu.Unlock()
+ isWatched := watchedDir || watchedPath
+
+ if events&unix.FILE_DELETE != 0 {
+ if !w.sendEvent(Event{path, Remove}) {
+ return nil
+ }
+ reRegister = false
+ }
+ if events&unix.FILE_RENAME_FROM != 0 {
+ if !w.sendEvent(Event{path, Rename}) {
+ return nil
+ }
+ // Don't keep watching the new file name
+ reRegister = false
+ }
+ if events&unix.FILE_RENAME_TO != 0 {
+ // We don't report a Rename event for this case, because
+ // Rename events are interpreted as referring to the _old_ name
+ // of the file, and in this case the event would refer to the
+ // new name of the file. This type of rename event is not
+ // supported by fsnotify.
+
+ // inotify reports a Remove event in this case, so we simulate
+ // this here.
+ if !w.sendEvent(Event{path, Remove}) {
+ return nil
+ }
+ // Don't keep watching the file that was removed
+ reRegister = false
+ }
+
+ // The file is gone, nothing left to do.
+ if !reRegister {
+ if watchedDir {
+ w.mu.Lock()
+ delete(w.dirs, path)
+ w.mu.Unlock()
+ }
+ if watchedPath {
+ w.mu.Lock()
+ delete(w.watches, path)
+ w.mu.Unlock()
+ }
+ return nil
+ }
+
+ // If we didn't get a deletion the file still exists and we're going to have to watch it again.
+ // Let's Stat it now so that we can compare permissions and have what we need
+ // to continue watching the file
+
+ stat, err := os.Lstat(path)
+ if err != nil {
+ // This is unexpected, but we should still emit an event
+ // This happens most often on "rm -r" of a subdirectory inside a watched directory
+ // We get a modify event of something happening inside, but by the time
+ // we get here, the sudirectory is already gone. Clearly we were watching this path
+ // but now it is gone. Let's tell the user that it was removed.
+ if !w.sendEvent(Event{path, Remove}) {
+ return nil
+ }
+ // Suppress extra write events on removed directories; they are not informative
+ // and can be confusing.
+ return nil
+ }
+
+ // resolve symlinks that were explicitly watched as we would have at Add() time.
+ // this helps suppress spurious Chmod events on watched symlinks
+ if isWatched {
+ stat, err = os.Stat(path)
+ if err != nil {
+ // The symlink still exists, but the target is gone. Report the Remove similar to above.
+ if !w.sendEvent(Event{path, Remove}) {
+ return nil
+ }
+ // Don't return the error
+ }
+ }
+
+ if events&unix.FILE_MODIFIED != 0 {
+ if fmode.IsDir() {
+ if watchedDir {
+ if err := w.updateDirectory(path); err != nil {
+ return err
+ }
+ } else {
+ if !w.sendEvent(Event{path, Write}) {
+ return nil
+ }
+ }
+ } else {
+ if !w.sendEvent(Event{path, Write}) {
+ return nil
+ }
+ }
+ }
+ if events&unix.FILE_ATTRIB != 0 && stat != nil {
+ // Only send Chmod if perms changed
+ if stat.Mode().Perm() != fmode.Perm() {
+ if !w.sendEvent(Event{path, Chmod}) {
+ return nil
+ }
+ }
+ }
+
+ if stat != nil {
+ // If we get here, it means we've hit an event above that requires us to
+ // continue watching the file or directory
+ return w.associateFile(path, stat, isWatched)
+ }
return nil
}
+
+func (w *Watcher) updateDirectory(path string) error {
+ // The directory was modified, so we must find unwatched entities and
+ // watch them. If something was removed from the directory, nothing will
+ // happen, as everything else should still be watched.
+ files, err := os.ReadDir(path)
+ if err != nil {
+ return err
+ }
+
+ for _, entry := range files {
+ path := filepath.Join(path, entry.Name())
+ if w.port.PathIsWatched(path) {
+ continue
+ }
+
+ finfo, err := entry.Info()
+ if err != nil {
+ return err
+ }
+ err = w.associateFile(path, finfo, false)
+ if err != nil {
+ if !w.sendError(err) {
+ return nil
+ }
+ }
+ if !w.sendEvent(Event{path, Create}) {
+ return nil
+ }
+ }
+ return nil
+}
+
+func (w *Watcher) associateFile(path string, stat os.FileInfo, follow bool) error {
+ if w.isClosed() {
+ return errors.New("FEN watcher already closed")
+ }
+ // This is primarily protecting the call to AssociatePath
+ // but it is important and intentional that the call to
+ // PathIsWatched is also protected by this mutex.
+ // Without this mutex, AssociatePath has been seen
+ // to error out that the path is already associated.
+ w.mu.Lock()
+ defer w.mu.Unlock()
+
+ if w.port.PathIsWatched(path) {
+ // Remove the old association in favor of this one
+ // If we get ENOENT, then while the x/sys/unix wrapper
+ // still thought that this path was associated,
+ // the underlying event port did not. This call will
+ // have cleared up that discrepancy. The most likely
+ // cause is that the event has fired but we haven't
+ // processed it yet.
+ err := w.port.DissociatePath(path)
+ if err != nil && err != unix.ENOENT {
+ return err
+ }
+ }
+ // FILE_NOFOLLOW means we watch symlinks themselves rather than their targets
+ events := unix.FILE_MODIFIED|unix.FILE_ATTRIB|unix.FILE_NOFOLLOW
+ if follow {
+ // We *DO* follow symlinks for explicitly watched entries
+ events = unix.FILE_MODIFIED|unix.FILE_ATTRIB
+ }
+ return w.port.AssociatePath(path, stat,
+ events,
+ stat.Mode())
+}
+
+func (w *Watcher) dissociateFile(path string, stat os.FileInfo, unused bool) error {
+ if !w.port.PathIsWatched(path) {
+ return nil
+ }
+ return w.port.DissociatePath(path)
+}
+
+// WatchList returns all paths added with Add() (and are not yet removed).
+func (w *Watcher) WatchList() []string {
+ w.mu.Lock()
+ defer w.mu.Unlock()
+
+ entries := make([]string, 0, len(w.watches)+len(w.dirs))
+ for pathname := range w.dirs {
+ entries = append(entries, pathname)
+ }
+ for pathname := range w.watches {
+ entries = append(entries, pathname)
+ }
+
+ return entries
+}
projects / fsnotify.git / commitdiff