golang/mikael/madonctl: comparison vendor/github.com/fsnotify/fsnotify/backend

equal deleted inserted replaced

-:8f478162d991
+:05c40b36d3b2
+//go:build freebsd || openbsd || netbsd || dragonfly || darwin
+// +build freebsd openbsd netbsd dragonfly darwin
+package fsnotify
+import (
+	"errors"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"sync"
+	"golang.org/x/sys/unix"
+)
+// Watcher watches a set of paths, delivering events on a channel.
+//
+// A watcher should not be copied (e.g. pass it by pointer, rather than by
+// value).
+//
+// # Linux notes
+//
+// When a file is removed a Remove event won't be emitted until all file
+// descriptors are closed, and deletes will always emit a Chmod. For example:
+//
+//     fp := os.Open("file")
+//     os.Remove("file")        // Triggers Chmod
+//     fp.Close()               // Triggers Remove
+//
+// This is the event that inotify sends, so not much can be changed about this.
+//
+// The fs.inotify.max_user_watches sysctl variable specifies the upper limit
+// for the number of watches per user, and fs.inotify.max_user_instances
+// specifies the maximum number of inotify instances per user. Every Watcher you
+// create is an "instance", and every path you add is a "watch".
+//
+// These are also exposed in /proc as /proc/sys/fs/inotify/max_user_watches and
+// /proc/sys/fs/inotify/max_user_instances
+//
+// To increase them you can use sysctl or write the value to the /proc file:
+//
+//     # Default values on Linux 5.18
+//     sysctl fs.inotify.max_user_watches=124983
+//     sysctl fs.inotify.max_user_instances=128
+//
+// To make the changes persist on reboot edit /etc/sysctl.conf or
+// /usr/lib/sysctl.d/50-default.conf (details differ per Linux distro; check
+// your distro's documentation):
+//
+//     fs.inotify.max_user_watches=124983
+//     fs.inotify.max_user_instances=128
+//
+// Reaching the limit will result in a "no space left on device" or "too many open
+// files" error.
+//
+// # kqueue notes (macOS, BSD)
+//
+// kqueue requires opening a file descriptor for every file that's being watched;
+// so if you're watching a directory with five files then that's six file
+// descriptors. You will run in to your system's "max open files" limit faster on
+// these platforms.
+//
+// The sysctl variables kern.maxfiles and kern.maxfilesperproc can be used to
+// control the maximum number of open files, as well as /etc/login.conf on BSD
+// systems.
+//
+// # macOS notes
+//
+// Spotlight indexing on macOS can result in multiple events (see [#15]). A
+// temporary workaround is to add your folder(s) to the "Spotlight Privacy
+// Settings" until we have a native FSEvents implementation (see [#11]).
+//
+// [#11]: https://github.com/fsnotify/fsnotify/issues/11
+// [#15]: https://github.com/fsnotify/fsnotify/issues/15
+type Watcher struct {
+	// Events sends the filesystem change events.
+	//
+	// fsnotify can send the following events; a "path" here can refer to a
+	// file, directory, symbolic link, or special file like a FIFO.
+	//
+	//   fsnotify.Create    A new path was created; this may be followed by one
+	//                      or more Write events if data also gets written to a
+	//                      file.
+	//
+	//   fsnotify.Remove    A path was removed.
+	//
+	//   fsnotify.Rename    A path was renamed. A rename is always sent with the
+	//                      old path as Event.Name, and a Create event will be
+	//                      sent with the new name. Renames are only sent for
+	//                      paths that are currently watched; e.g. moving an
+	//                      unmonitored file into a monitored directory will
+	//                      show up as just a Create. Similarly, renaming a file
+	//                      to outside a monitored directory will show up as
+	//                      only a Rename.
+	//
+	//   fsnotify.Write     A file or named pipe was written to. A Truncate will
+	//                      also trigger a Write. A single "write action"
+	//                      initiated by the user may show up as one or multiple
+	//                      writes, depending on when the system syncs things to
+	//                      disk. For example when compiling a large Go program
+	//                      you may get hundreds of Write events, so you
+	//                      probably want to wait until you've stopped receiving
+	//                      them (see the dedup example in cmd/fsnotify).
+	//
+	//   fsnotify.Chmod     Attributes were changed. On Linux this is also sent
+	//                      when a file is removed (or more accurately, when a
+	//                      link to an inode is removed). On kqueue it's sent
+	//                      and on kqueue when a file is truncated. On Windows
+	//                      it's never sent.
+	Events chan Event
+	// Errors sends any errors.
+	Errors chan error
+	done         chan struct{}
+	kq           int                         // File descriptor (as returned by the kqueue() syscall).
+	closepipe    [2]int                      // Pipe used for closing.
+	mu           sync.Mutex                  // Protects access to watcher data
+	watches      map[string]int              // Watched file descriptors (key: path).
+	watchesByDir map[string]map[int]struct{} // Watched file descriptors indexed by the parent directory (key: dirname(path)).
+	userWatches  map[string]struct{}         // Watches added with Watcher.Add()
+	dirFlags     map[string]uint32           // Watched directories to fflags used in kqueue.
+	paths        map[int]pathInfo            // File descriptors to path names for processing kqueue events.
+	fileExists   map[string]struct{}         // Keep track of if we know this file exists (to stop duplicate create events).
+	isClosed     bool                        // Set to true when Close() is first called
+}
+type pathInfo struct {
+	name  string
+	isDir bool
+}
+// NewWatcher creates a new Watcher.
+func NewWatcher() (*Watcher, error) {
+	kq, closepipe, err := newKqueue()
+	if err != nil {
+		return nil, err
+	}
+	w := &Watcher{
+		kq:           kq,
+		closepipe:    closepipe,
+		watches:      make(map[string]int),
+		watchesByDir: make(map[string]map[int]struct{}),
+		dirFlags:     make(map[string]uint32),
+		paths:        make(map[int]pathInfo),
+		fileExists:   make(map[string]struct{}),
+		userWatches:  make(map[string]struct{}),
+		Events:       make(chan Event),
+		Errors:       make(chan error),
+		done:         make(chan struct{}),
+	}
+	go w.readEvents()
+	return w, nil
+}
+// newKqueue creates a new kernel event queue and returns a descriptor.
+//
+// This registers a new event on closepipe, which will trigger an event when
+// it's closed. This way we can use kevent() without timeout/polling; without
+// the closepipe, it would block forever and we wouldn't be able to stop it at
+// all.
+func newKqueue() (kq int, closepipe [2]int, err error) {
+	kq, err = unix.Kqueue()
+	if kq == -1 {
+		return kq, closepipe, err
+	}
+	// Register the close pipe.
+	err = unix.Pipe(closepipe[:])
+	if err != nil {
+		unix.Close(kq)
+		return kq, closepipe, err
+	}
+	// Register changes to listen on the closepipe.
+	changes := make([]unix.Kevent_t, 1)
+	// SetKevent converts int to the platform-specific types.
+	unix.SetKevent(&changes[0], closepipe[0], unix.EVFILT_READ,
+		unix.EV_ADD|unix.EV_ENABLE|unix.EV_ONESHOT)
+	ok, err := unix.Kevent(kq, changes, nil, nil)
+	if ok == -1 {
+		unix.Close(kq)
+		unix.Close(closepipe[0])
+		unix.Close(closepipe[1])
+		return kq, closepipe, err
+	}
+	return kq, closepipe, nil
+}
+// Returns true if the event was sent, or false if watcher is closed.
+func (w *Watcher) sendEvent(e Event) bool {
+	select {
+	case w.Events <- e:
+		return true
+	case <-w.done:
+	}
+	return false
+}
+// Returns true if the error was sent, or false if watcher is closed.
+func (w *Watcher) sendError(err error) bool {
+	select {
+	case w.Errors <- err:
+		return true
+	case <-w.done:
+	}
+	return false
+}
+// Close removes all watches and closes the events channel.
+func (w *Watcher) Close() error {
+	w.mu.Lock()
+	if w.isClosed {
+		w.mu.Unlock()
+		return nil
+	}
+	w.isClosed = true
+	// copy paths to remove while locked
+	pathsToRemove := make([]string, 0, len(w.watches))
+	for name := range w.watches {
+		pathsToRemove = append(pathsToRemove, name)
+	}
+	w.mu.Unlock() // Unlock before calling Remove, which also locks
+	for _, name := range pathsToRemove {
+		w.Remove(name)
+	}
+	// Send "quit" message to the reader goroutine.
+	unix.Close(w.closepipe[1])
+	close(w.done)
+	return nil
+}
+// Add starts monitoring the path for changes.
+//
+// A path can only be watched once; attempting to watch it more than once will
+// return an error. Paths that do not yet exist on the filesystem cannot be
+// added. A watch will be automatically removed if the path is deleted.
+//
+// A path will remain watched if it gets renamed to somewhere else on the same
+// filesystem, but the monitor will get removed if the path gets deleted and
+// re-created, or if it's moved to a different filesystem.
+//
+// Notifications on network filesystems (NFS, SMB, FUSE, etc.) or special
+// filesystems (/proc, /sys, etc.) generally don't work.
+//
+// # Watching directories
+//
+// All files in a directory are monitored, including new files that are created
+// after the watcher is started. Subdirectories are not watched (i.e. it's
+// non-recursive).
+//
+// # Watching files
+//
+// Watching individual files (rather than directories) is generally not
+// recommended as many tools update files atomically. Instead of "just" writing
+// to the file a temporary file will be written to first, and if successful the
+// temporary file is moved to to destination removing the original, or some
+// variant thereof. The watcher on the original file is now lost, as it no
+// longer exists.
+//
+// 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 {
+	w.mu.Lock()
+	w.userWatches[name] = struct{}{}
+	w.mu.Unlock()
+	_, err := w.addWatch(name, noteAllEvents)
+	return err
+}
+// Remove stops monitoring the path for changes.
+//
+// Directories are always removed non-recursively. For example, if you added
+// /tmp/dir and /tmp/dir/subdir then you will need to remove both.
+//
+// Removing a path that has not yet been added returns [ErrNonExistentWatch].
+func (w *Watcher) Remove(name string) error {
+	name = filepath.Clean(name)
+	w.mu.Lock()
+	watchfd, ok := w.watches[name]
+	w.mu.Unlock()
+	if !ok {
+		return fmt.Errorf("%w: %s", ErrNonExistentWatch, name)
+	}
+	err := w.register([]int{watchfd}, unix.EV_DELETE, 0)
+	if err != nil {
+		return err
+	}
+	unix.Close(watchfd)
+	w.mu.Lock()
+	isDir := w.paths[watchfd].isDir
+	delete(w.watches, name)
+	delete(w.userWatches, name)
+	parentName := filepath.Dir(name)
+	delete(w.watchesByDir[parentName], watchfd)
+	if len(w.watchesByDir[parentName]) == 0 {
+		delete(w.watchesByDir, parentName)
+	}
+	delete(w.paths, watchfd)
+	delete(w.dirFlags, name)
+	delete(w.fileExists, name)
+	w.mu.Unlock()
+	// Find all watched paths that are in this directory that are not external.
+	if isDir {
+		var pathsToRemove []string
+		w.mu.Lock()
+		for fd := range w.watchesByDir[name] {
+			path := w.paths[fd]
+			if _, ok := w.userWatches[path.name]; !ok {
+				pathsToRemove = append(pathsToRemove, path.name)
+			}
+		}
+		w.mu.Unlock()
+		for _, name := range pathsToRemove {
+			// Since these are internal, not much sense in propagating error
+			// to the user, as that will just confuse them with an error about
+			// a path they did not explicitly watch themselves.
+			w.Remove(name)
+		}
+	}
+	return nil
+}
+// 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.userWatches))
+	for pathname := range w.userWatches {
+		entries = append(entries, pathname)
+	}
+	return entries
+}
+// Watch all events (except NOTE_EXTEND, NOTE_LINK, NOTE_REVOKE)
+const noteAllEvents = unix.NOTE_DELETE | unix.NOTE_WRITE | unix.NOTE_ATTRIB | unix.NOTE_RENAME
+// addWatch adds name to the watched file set.
+// The flags are interpreted as described in kevent(2).
+// Returns the real path to the file which was added, if any, which may be different from the one passed in the case of symlinks.
+func (w *Watcher) addWatch(name string, flags uint32) (string, error) {
+	var isDir bool
+	// Make ./name and name equivalent
+	name = filepath.Clean(name)
+	w.mu.Lock()
+	if w.isClosed {
+		w.mu.Unlock()
+		return "", errors.New("kevent instance already closed")
+	}
+	watchfd, alreadyWatching := w.watches[name]
+	// We already have a watch, but we can still override flags.
+	if alreadyWatching {
+		isDir = w.paths[watchfd].isDir
+	}
+	w.mu.Unlock()
+	if !alreadyWatching {
+		fi, err := os.Lstat(name)
+		if err != nil {
+			return "", err
+		}
+		// Don't watch sockets or named pipes
+		if (fi.Mode()&os.ModeSocket == os.ModeSocket) || (fi.Mode()&os.ModeNamedPipe == os.ModeNamedPipe) {
+			return "", nil
+		}
+		// Follow Symlinks
+		//
+		// Linux can add unresolvable symlinks to the watch list without issue,
+		// and Windows can't do symlinks period. To maintain consistency, we
+		// will act like everything is fine if the link can't be resolved.
+		// There will simply be no file events for broken symlinks. Hence the
+		// returns of nil on errors.
+		if fi.Mode()&os.ModeSymlink == os.ModeSymlink {
+			name, err = filepath.EvalSymlinks(name)
+			if err != nil {
+				return "", nil
+			}
+			w.mu.Lock()
+			_, alreadyWatching = w.watches[name]
+			w.mu.Unlock()
+			if alreadyWatching {
+				return name, nil
+			}
+			fi, err = os.Lstat(name)
+			if err != nil {
+				return "", nil
+			}
+		}
+		// Retry on EINTR; open() can return EINTR in practice on macOS.
+		// See #354, and go issues 11180 and 39237.
+		for {
+			watchfd, err = unix.Open(name, openMode, 0)
+			if err == nil {
+				break
+			}
+			if errors.Is(err, unix.EINTR) {
+				continue
+			}
+			return "", err
+		}
+		isDir = fi.IsDir()
+	}
+	err := w.register([]int{watchfd}, unix.EV_ADD|unix.EV_CLEAR|unix.EV_ENABLE, flags)
+	if err != nil {
+		unix.Close(watchfd)
+		return "", err
+	}
+	if !alreadyWatching {
+		w.mu.Lock()
+		parentName := filepath.Dir(name)
+		w.watches[name] = watchfd
+		watchesByDir, ok := w.watchesByDir[parentName]
+		if !ok {
+			watchesByDir = make(map[int]struct{}, 1)
+			w.watchesByDir[parentName] = watchesByDir
+		}
+		watchesByDir[watchfd] = struct{}{}
+		w.paths[watchfd] = pathInfo{name: name, isDir: isDir}
+		w.mu.Unlock()
+	}
+	if isDir {
+		// Watch the directory if it has not been watched before,
+		// or if it was watched before, but perhaps only a NOTE_DELETE (watchDirectoryFiles)
+		w.mu.Lock()
+		watchDir := (flags&unix.NOTE_WRITE) == unix.NOTE_WRITE &&
+			(!alreadyWatching || (w.dirFlags[name]&unix.NOTE_WRITE) != unix.NOTE_WRITE)
+		// Store flags so this watch can be updated later
+		w.dirFlags[name] = flags
+		w.mu.Unlock()
+		if watchDir {
+			if err := w.watchDirectoryFiles(name); err != nil {
+				return "", err
+			}
+		}
+	}
+	return name, nil
+}
+// readEvents reads from kqueue and converts the received kevents into
+// Event values that it sends down the Events channel.
+func (w *Watcher) readEvents() {
+	defer func() {
+		err := unix.Close(w.kq)
+		if err != nil {
+			w.Errors <- err
+		}
+		unix.Close(w.closepipe[0])
+		close(w.Events)
+		close(w.Errors)
+	}()
+	eventBuffer := make([]unix.Kevent_t, 10)
+	for closed := false; !closed; {
+		kevents, err := w.read(eventBuffer)
+		// EINTR is okay, the syscall was interrupted before timeout expired.
+		if err != nil && err != unix.EINTR {
+			if !w.sendError(fmt.Errorf("fsnotify.readEvents: %w", err)) {
+				closed = true
+			}
+			continue
+		}
+		// Flush the events we received to the Events channel
+		for _, kevent := range kevents {
+			var (
+				watchfd = int(kevent.Ident)
+				mask    = uint32(kevent.Fflags)
+			)
+			// Shut down the loop when the pipe is closed, but only after all
+			// other events have been processed.
+			if watchfd == w.closepipe[0] {
+				closed = true
+				continue
+			}
+			w.mu.Lock()
+			path := w.paths[watchfd]
+			w.mu.Unlock()
+			event := w.newEvent(path.name, mask)
+			if path.isDir && !event.Has(Remove) {
+				// Double check to make sure the directory exists. This can
+				// happen when we do a rm -fr on a recursively watched folders
+				// and we receive a modification event first but the folder has
+				// been deleted and later receive the delete event.
+				if _, err := os.Lstat(event.Name); os.IsNotExist(err) {
+					event.Op |= Remove
+				}
+			}
+			if event.Has(Rename) || event.Has(Remove) {
+				w.Remove(event.Name)
+				w.mu.Lock()
+				delete(w.fileExists, event.Name)
+				w.mu.Unlock()
+			}
+			if path.isDir && event.Has(Write) && !event.Has(Remove) {
+				w.sendDirectoryChangeEvents(event.Name)
+			} else {
+				if !w.sendEvent(event) {
+					closed = true
+					continue
+				}
+			}
+			if event.Has(Remove) {
+				// Look for a file that may have overwritten this.
+				// For example, mv f1 f2 will delete f2, then create f2.
+				if path.isDir {
+					fileDir := filepath.Clean(event.Name)
+					w.mu.Lock()
+					_, found := w.watches[fileDir]
+					w.mu.Unlock()
+					if found {
+						// make sure the directory exists before we watch for changes. When we
+						// do a recursive watch and perform rm -fr, the parent directory might
+						// have gone missing, ignore the missing directory and let the
+						// upcoming delete event remove the watch from the parent directory.
+						if _, err := os.Lstat(fileDir); err == nil {
+							w.sendDirectoryChangeEvents(fileDir)
+						}
+					}
+				} else {
+					filePath := filepath.Clean(event.Name)
+					if fileInfo, err := os.Lstat(filePath); err == nil {
+						w.sendFileCreatedEventIfNew(filePath, fileInfo)
+					}
+				}
+			}
+		}
+	}
+}
+// newEvent returns an platform-independent Event based on kqueue Fflags.
+func (w *Watcher) newEvent(name string, mask uint32) Event {
+	e := Event{Name: name}
+	if mask&unix.NOTE_DELETE == unix.NOTE_DELETE {
+		e.Op |= Remove
+	}
+	if mask&unix.NOTE_WRITE == unix.NOTE_WRITE {
+		e.Op |= Write
+	}
+	if mask&unix.NOTE_RENAME == unix.NOTE_RENAME {
+		e.Op |= Rename
+	}
+	if mask&unix.NOTE_ATTRIB == unix.NOTE_ATTRIB {
+		e.Op |= Chmod
+	}
+	return e
+}
+// watchDirectoryFiles to mimic inotify when adding a watch on a directory
+func (w *Watcher) watchDirectoryFiles(dirPath string) error {
+	// Get all files
+	files, err := ioutil.ReadDir(dirPath)
+	if err != nil {
+		return err
+	}
+	for _, fileInfo := range files {
+		path := filepath.Join(dirPath, fileInfo.Name())
+		cleanPath, err := w.internalWatch(path, fileInfo)
+		if err != nil {
+			// No permission to read the file; that's not a problem: just skip.
+			// But do add it to w.fileExists to prevent it from being picked up
+			// as a "new" file later (it still shows up in the directory
+			// listing).
+			switch {
+			case errors.Is(err, unix.EACCES) || errors.Is(err, unix.EPERM):
+				cleanPath = filepath.Clean(path)
+			default:
+				return fmt.Errorf("%q: %w", filepath.Join(dirPath, fileInfo.Name()), err)
+			}
+		}
+		w.mu.Lock()
+		w.fileExists[cleanPath] = struct{}{}
+		w.mu.Unlock()
+	}
+	return nil
+}
+// Search the directory for new files and send an event for them.
+//
+// This functionality is to have the BSD watcher match the inotify, which sends
+// a create event for files created in a watched directory.
+func (w *Watcher) sendDirectoryChangeEvents(dir string) {
+	// Get all files
+	files, err := ioutil.ReadDir(dir)
+	if err != nil {
+		if !w.sendError(fmt.Errorf("fsnotify.sendDirectoryChangeEvents: %w", err)) {
+			return
+		}
+	}
+	// Search for new files
+	for _, fi := range files {
+		err := w.sendFileCreatedEventIfNew(filepath.Join(dir, fi.Name()), fi)
+		if err != nil {
+			return
+		}
+	}
+}
+// sendFileCreatedEvent sends a create event if the file isn't already being tracked.
+func (w *Watcher) sendFileCreatedEventIfNew(filePath string, fileInfo os.FileInfo) (err error) {
+	w.mu.Lock()
+	_, doesExist := w.fileExists[filePath]
+	w.mu.Unlock()
+	if !doesExist {
+		if !w.sendEvent(Event{Name: filePath, Op: Create}) {
+			return
+		}
+	}
+	// like watchDirectoryFiles (but without doing another ReadDir)
+	filePath, err = w.internalWatch(filePath, fileInfo)
+	if err != nil {
+		return err
+	}
+	w.mu.Lock()
+	w.fileExists[filePath] = struct{}{}
+	w.mu.Unlock()
+	return nil
+}
+func (w *Watcher) internalWatch(name string, fileInfo os.FileInfo) (string, error) {
+	if fileInfo.IsDir() {
+		// mimic Linux providing delete events for subdirectories
+		// but preserve the flags used if currently watching subdirectory
+		w.mu.Lock()
+		flags := w.dirFlags[name]
+		w.mu.Unlock()
+		flags |= unix.NOTE_DELETE | unix.NOTE_RENAME
+		return w.addWatch(name, flags)
+	}
+	// watch file to mimic Linux inotify
+	return w.addWatch(name, noteAllEvents)
+}
+// Register events with the queue.
+func (w *Watcher) register(fds []int, flags int, fflags uint32) error {
+	changes := make([]unix.Kevent_t, len(fds))
+	for i, fd := range fds {
+		// SetKevent converts int to the platform-specific types.
+		unix.SetKevent(&changes[i], fd, unix.EVFILT_VNODE, flags)
+		changes[i].Fflags = fflags
+	}
+	// Register the events.
+	success, err := unix.Kevent(w.kq, changes, nil, nil)
+	if success == -1 {
+		return err
+	}
+	return nil
+}
+// read retrieves pending events, or waits until an event occurs.
+func (w *Watcher) read(events []unix.Kevent_t) ([]unix.Kevent_t, error) {
+	n, err := unix.Kevent(w.kq, nil, events, nil)
+	if err != nil {
+		return nil, err
+	}
+	return events[0:n], nil
+}