diff -r 8f478162d991 -r 05c40b36d3b2 vendor/github.com/fsnotify/fsnotify/backend_inotify.go --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/vendor/github.com/fsnotify/fsnotify/backend_inotify.go Sat Feb 04 12:58:35 2023 +0100 @@ -0,0 +1,459 @@ +//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 +}