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

equal deleted inserted replaced

-:8f478162d991
+:05c40b36d3b2
+//go:build linux
+// +build linux
+package fsnotify
+import (
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+	"sync"
+	"unsafe"
+	"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
+	// Store fd here as os.File.Read() will no longer return on close after
+	// calling Fd(). See: https://github.com/golang/go/issues/26439
+	fd          int
+	mu          sync.Mutex // Map access
+	inotifyFile *os.File
+	watches     map[string]*watch // Map of inotify watches (key: path)
+	paths       map[int]string    // Map of watched paths (key: watch descriptor)
+	done        chan struct{}     // Channel for sending a "quit message" to the reader goroutine
+	doneResp    chan struct{}     // Channel to respond to Close
+}
+// NewWatcher creates a new Watcher.
+func NewWatcher() (*Watcher, error) {
+	// Create inotify fd
+	// Need to set the FD to nonblocking mode in order for SetDeadline methods to work
+	// Otherwise, blocking i/o operations won't terminate on close
+	fd, errno := unix.InotifyInit1(unix.IN_CLOEXEC | unix.IN_NONBLOCK)
+	if fd == -1 {
+		return nil, errno
+	}
+	w := &Watcher{
+		fd:          fd,
+		inotifyFile: os.NewFile(uintptr(fd), ""),
+		watches:     make(map[string]*watch),
+		paths:       make(map[int]string),
+		Events:      make(chan Event),
+		Errors:      make(chan error),
+		done:        make(chan struct{}),
+		doneResp:    make(chan struct{}),
+	}
+	go w.readEvents()
+	return w, 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
+	}
+}
+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 {
+	w.mu.Lock()
+	if w.isClosed() {
+		w.mu.Unlock()
+		return nil
+	}
+	// Send 'close' signal to goroutine, and set the Watcher to closed.
+	close(w.done)
+	w.mu.Unlock()
+	// Causes any blocking reads to return with an error, provided the file
+	// still supports deadline operations.
+	err := w.inotifyFile.Close()
+	if err != nil {
+		return err
+	}
+	// Wait for goroutine to close
+	<-w.doneResp
+	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 {
+	name = filepath.Clean(name)
+	if w.isClosed() {
+		return errors.New("inotify instance already closed")
+	}
+	var flags uint32 = unix.IN_MOVED_TO | unix.IN_MOVED_FROM |
+		unix.IN_CREATE | unix.IN_ATTRIB | unix.IN_MODIFY |
+		unix.IN_MOVE_SELF | unix.IN_DELETE | unix.IN_DELETE_SELF
+	w.mu.Lock()
+	defer w.mu.Unlock()
+	watchEntry := w.watches[name]
+	if watchEntry != nil {
+		flags |= watchEntry.flags | unix.IN_MASK_ADD
+	}
+	wd, errno := unix.InotifyAddWatch(w.fd, name, flags)
+	if wd == -1 {
+		return errno
+	}
+	if watchEntry == nil {
+		w.watches[name] = &watch{wd: uint32(wd), flags: flags}
+		w.paths[wd] = name
+	} else {
+		watchEntry.wd = uint32(wd)
+		watchEntry.flags = flags
+	}
+	return nil
+}
+// 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)
+	// Fetch the watch.
+	w.mu.Lock()
+	defer w.mu.Unlock()
+	watch, ok := w.watches[name]
+	// Remove it from inotify.
+	if !ok {
+		return fmt.Errorf("%w: %s", ErrNonExistentWatch, name)
+	}
+	// We successfully removed the watch if InotifyRmWatch doesn't return an
+	// error, we need to clean up our internal state to ensure it matches
+	// inotify's kernel state.
+	delete(w.paths, int(watch.wd))
+	delete(w.watches, name)
+	// inotify_rm_watch will return EINVAL if the file has been deleted;
+	// the inotify will already have been removed.
+	// watches and pathes are deleted in ignoreLinux() implicitly and asynchronously
+	// by calling inotify_rm_watch() below. e.g. readEvents() goroutine receives IN_IGNORE
+	// so that EINVAL means that the wd is being rm_watch()ed or its file removed
+	// by another thread and we have not received IN_IGNORE event.
+	success, errno := unix.InotifyRmWatch(w.fd, watch.wd)
+	if success == -1 {
+		// TODO: Perhaps it's not helpful to return an error here in every case;
+		//       The only two possible errors are:
+		//
+		//       - EBADF, which happens when w.fd is not a valid file descriptor
+		//         of any kind.
+		//       - EINVAL, which is when fd is not an inotify descriptor or wd
+		//         is not a valid watch descriptor. Watch descriptors are
+		//         invalidated when they are removed explicitly or implicitly;
+		//         explicitly by inotify_rm_watch, implicitly when the file they
+		//         are watching is deleted.
+		return errno
+	}
+	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.watches))
+	for pathname := range w.watches {
+		entries = append(entries, pathname)
+	}
+	return entries
+}
+type watch struct {
+	wd    uint32 // Watch descriptor (as returned by the inotify_add_watch() syscall)
+	flags uint32 // inotify flags of this watch (see inotify(7) for the list of valid flags)
+}
+// readEvents reads from the inotify file descriptor, converts the
+// received events into Event objects and sends them via the Events channel
+func (w *Watcher) readEvents() {
+	defer func() {
+		close(w.doneResp)
+		close(w.Errors)
+		close(w.Events)
+	}()
+	var (
+		buf   [unix.SizeofInotifyEvent * 4096]byte // Buffer for a maximum of 4096 raw events
+		errno error                                // Syscall errno
+	)
+	for {
+		// See if we have been closed.
+		if w.isClosed() {
+			return
+		}
+		n, err := w.inotifyFile.Read(buf[:])
+		switch {
+		case errors.Unwrap(err) == os.ErrClosed:
+			return
+		case err != nil:
+			if !w.sendError(err) {
+				return
+			}
+			continue
+		}
+		if n < unix.SizeofInotifyEvent {
+			var err error
+			if n == 0 {
+				// If EOF is received. This should really never happen.
+				err = io.EOF
+			} else if n < 0 {
+				// If an error occurred while reading.
+				err = errno
+			} else {
+				// Read was too short.
+				err = errors.New("notify: short read in readEvents()")
+			}
+			if !w.sendError(err) {
+				return
+			}
+			continue
+		}
+		var offset uint32
+		// We don't know how many events we just read into the buffer
+		// While the offset points to at least one whole event...
+		for offset <= uint32(n-unix.SizeofInotifyEvent) {
+			var (
+				// Point "raw" to the event in the buffer
+				raw     = (*unix.InotifyEvent)(unsafe.Pointer(&buf[offset]))
+				mask    = uint32(raw.Mask)
+				nameLen = uint32(raw.Len)
+			)
+			if mask&unix.IN_Q_OVERFLOW != 0 {
+				if !w.sendError(ErrEventOverflow) {
+					return
+				}
+			}
+			// If the event happened to the watched directory or the watched file, the kernel
+			// doesn't append the filename to the event, but we would like to always fill the
+			// the "Name" field with a valid filename. We retrieve the path of the watch from
+			// the "paths" map.
+			w.mu.Lock()
+			name, ok := w.paths[int(raw.Wd)]
+			// IN_DELETE_SELF occurs when the file/directory being watched is removed.
+			// This is a sign to clean up the maps, otherwise we are no longer in sync
+			// with the inotify kernel state which has already deleted the watch
+			// automatically.
+			if ok && mask&unix.IN_DELETE_SELF == unix.IN_DELETE_SELF {
+				delete(w.paths, int(raw.Wd))
+				delete(w.watches, name)
+			}
+			w.mu.Unlock()
+			if nameLen > 0 {
+				// Point "bytes" at the first byte of the filename
+				bytes := (*[unix.PathMax]byte)(unsafe.Pointer(&buf[offset+unix.SizeofInotifyEvent]))[:nameLen:nameLen]
+				// The filename is padded with NULL bytes. TrimRight() gets rid of those.
+				name += "/" + strings.TrimRight(string(bytes[0:nameLen]), "\000")
+			}
+			event := w.newEvent(name, mask)
+			// Send the events that are not ignored on the events channel
+			if mask&unix.IN_IGNORED == 0 {
+				if !w.sendEvent(event) {
+					return
+				}
+			}
+			// Move to the next event in the buffer
+			offset += unix.SizeofInotifyEvent + nameLen
+		}
+	}
+}
+// newEvent returns an platform-independent Event based on an inotify mask.
+func (w *Watcher) newEvent(name string, mask uint32) Event {
+	e := Event{Name: name}
+	if mask&unix.IN_CREATE == unix.IN_CREATE || mask&unix.IN_MOVED_TO == unix.IN_MOVED_TO {
+		e.Op |= Create
+	}
+	if mask&unix.IN_DELETE_SELF == unix.IN_DELETE_SELF || mask&unix.IN_DELETE == unix.IN_DELETE {
+		e.Op |= Remove
+	}
+	if mask&unix.IN_MODIFY == unix.IN_MODIFY {
+		e.Op |= Write
+	}
+	if mask&unix.IN_MOVE_SELF == unix.IN_MOVE_SELF || mask&unix.IN_MOVED_FROM == unix.IN_MOVED_FROM {
+		e.Op |= Rename
+	}
+	if mask&unix.IN_ATTRIB == unix.IN_ATTRIB {
+		e.Op |= Chmod
+	}
+	return e
+}