| // Copyright 2010 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| // +build linux |
| |
| package fsnotify |
| |
| import ( |
| "errors" |
| "fmt" |
| "os" |
| "strings" |
| "sync" |
| "syscall" |
| "unsafe" |
| ) |
| |
| const ( |
| // Options for inotify_init() are not exported |
| // sys_IN_CLOEXEC uint32 = syscall.IN_CLOEXEC |
| // sys_IN_NONBLOCK uint32 = syscall.IN_NONBLOCK |
| |
| // Options for AddWatch |
| sys_IN_DONT_FOLLOW uint32 = syscall.IN_DONT_FOLLOW |
| sys_IN_ONESHOT uint32 = syscall.IN_ONESHOT |
| sys_IN_ONLYDIR uint32 = syscall.IN_ONLYDIR |
| |
| // The "sys_IN_MASK_ADD" option is not exported, as AddWatch |
| // adds it automatically, if there is already a watch for the given path |
| // sys_IN_MASK_ADD uint32 = syscall.IN_MASK_ADD |
| |
| // Events |
| sys_IN_ACCESS uint32 = syscall.IN_ACCESS |
| sys_IN_ALL_EVENTS uint32 = syscall.IN_ALL_EVENTS |
| sys_IN_ATTRIB uint32 = syscall.IN_ATTRIB |
| sys_IN_CLOSE uint32 = syscall.IN_CLOSE |
| sys_IN_CLOSE_NOWRITE uint32 = syscall.IN_CLOSE_NOWRITE |
| sys_IN_CLOSE_WRITE uint32 = syscall.IN_CLOSE_WRITE |
| sys_IN_CREATE uint32 = syscall.IN_CREATE |
| sys_IN_DELETE uint32 = syscall.IN_DELETE |
| sys_IN_DELETE_SELF uint32 = syscall.IN_DELETE_SELF |
| sys_IN_MODIFY uint32 = syscall.IN_MODIFY |
| sys_IN_MOVE uint32 = syscall.IN_MOVE |
| sys_IN_MOVED_FROM uint32 = syscall.IN_MOVED_FROM |
| sys_IN_MOVED_TO uint32 = syscall.IN_MOVED_TO |
| sys_IN_MOVE_SELF uint32 = syscall.IN_MOVE_SELF |
| sys_IN_OPEN uint32 = syscall.IN_OPEN |
| |
| sys_AGNOSTIC_EVENTS = sys_IN_MOVED_TO | sys_IN_MOVED_FROM | sys_IN_CREATE | sys_IN_ATTRIB | sys_IN_MODIFY | sys_IN_MOVE_SELF | sys_IN_DELETE | sys_IN_DELETE_SELF |
| |
| // Special events |
| sys_IN_ISDIR uint32 = syscall.IN_ISDIR |
| sys_IN_IGNORED uint32 = syscall.IN_IGNORED |
| sys_IN_Q_OVERFLOW uint32 = syscall.IN_Q_OVERFLOW |
| sys_IN_UNMOUNT uint32 = syscall.IN_UNMOUNT |
| ) |
| |
| type FileEvent struct { |
| mask uint32 // Mask of events |
| cookie uint32 // Unique cookie associating related events (for rename(2)) |
| Name string // File name (optional) |
| } |
| |
| // IsCreate reports whether the FileEvent was triggered by a creation |
| func (e *FileEvent) IsCreate() bool { |
| return (e.mask&sys_IN_CREATE) == sys_IN_CREATE || (e.mask&sys_IN_MOVED_TO) == sys_IN_MOVED_TO |
| } |
| |
| // IsDelete reports whether the FileEvent was triggered by a delete |
| func (e *FileEvent) IsDelete() bool { |
| return (e.mask&sys_IN_DELETE_SELF) == sys_IN_DELETE_SELF || (e.mask&sys_IN_DELETE) == sys_IN_DELETE |
| } |
| |
| // IsModify reports whether the FileEvent was triggered by a file modification or attribute change |
| func (e *FileEvent) IsModify() bool { |
| return ((e.mask&sys_IN_MODIFY) == sys_IN_MODIFY || (e.mask&sys_IN_ATTRIB) == sys_IN_ATTRIB) |
| } |
| |
| // IsRename reports whether the FileEvent was triggered by a change name |
| func (e *FileEvent) IsRename() bool { |
| return ((e.mask&sys_IN_MOVE_SELF) == sys_IN_MOVE_SELF || (e.mask&sys_IN_MOVED_FROM) == sys_IN_MOVED_FROM) |
| } |
| |
| // IsAttrib reports whether the FileEvent was triggered by a change in the file metadata. |
| func (e *FileEvent) IsAttrib() bool { |
| return (e.mask & sys_IN_ATTRIB) == sys_IN_ATTRIB |
| } |
| |
| 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) |
| } |
| |
| type Watcher struct { |
| mu sync.Mutex // Map access |
| fd int // File descriptor (as returned by the inotify_init() syscall) |
| watches map[string]*watch // Map of inotify watches (key: path) |
| fsnFlags map[string]uint32 // Map of watched files to flags used for filter |
| fsnmut sync.Mutex // Protects access to fsnFlags. |
| paths map[int]string // Map of watched paths (key: watch descriptor) |
| Error chan error // Errors are sent on this channel |
| internalEvent chan *FileEvent // Events are queued on this channel |
| Event chan *FileEvent // Events are returned on this channel |
| done chan bool // Channel for sending a "quit message" to the reader goroutine |
| isClosed bool // Set to true when Close() is first called |
| } |
| |
| // NewWatcher creates and returns a new inotify instance using inotify_init(2) |
| func NewWatcher() (*Watcher, error) { |
| fd, errno := syscall.InotifyInit() |
| if fd == -1 { |
| return nil, os.NewSyscallError("inotify_init", errno) |
| } |
| w := &Watcher{ |
| fd: fd, |
| watches: make(map[string]*watch), |
| fsnFlags: make(map[string]uint32), |
| paths: make(map[int]string), |
| internalEvent: make(chan *FileEvent), |
| Event: make(chan *FileEvent), |
| Error: make(chan error), |
| done: make(chan bool, 1), |
| } |
| |
| go w.readEvents() |
| go w.purgeEvents() |
| return w, nil |
| } |
| |
| // Close closes an inotify watcher instance |
| // It sends a message to the reader goroutine to quit and removes all watches |
| // associated with the inotify instance |
| func (w *Watcher) Close() error { |
| if w.isClosed { |
| return nil |
| } |
| w.isClosed = true |
| |
| // Remove all watches |
| for path := range w.watches { |
| w.RemoveWatch(path) |
| } |
| |
| // Send "quit" message to the reader goroutine |
| w.done <- true |
| |
| return nil |
| } |
| |
| // AddWatch adds path to the watched file set. |
| // The flags are interpreted as described in inotify_add_watch(2). |
| func (w *Watcher) addWatch(path string, flags uint32) error { |
| if w.isClosed { |
| return errors.New("inotify instance already closed") |
| } |
| |
| w.mu.Lock() |
| watchEntry, found := w.watches[path] |
| w.mu.Unlock() |
| if found { |
| watchEntry.flags |= flags |
| flags |= syscall.IN_MASK_ADD |
| } |
| wd, errno := syscall.InotifyAddWatch(w.fd, path, flags) |
| if wd == -1 { |
| return errno |
| } |
| |
| w.mu.Lock() |
| w.watches[path] = &watch{wd: uint32(wd), flags: flags} |
| w.paths[wd] = path |
| w.mu.Unlock() |
| |
| return nil |
| } |
| |
| // Watch adds path to the watched file set, watching all events. |
| func (w *Watcher) watch(path string) error { |
| return w.addWatch(path, sys_AGNOSTIC_EVENTS) |
| } |
| |
| // RemoveWatch removes path from the watched file set. |
| func (w *Watcher) removeWatch(path string) error { |
| w.mu.Lock() |
| defer w.mu.Unlock() |
| watch, ok := w.watches[path] |
| if !ok { |
| return errors.New(fmt.Sprintf("can't remove non-existent inotify watch for: %s", path)) |
| } |
| success, errno := syscall.InotifyRmWatch(w.fd, watch.wd) |
| if success == -1 { |
| return os.NewSyscallError("inotify_rm_watch", errno) |
| } |
| delete(w.watches, path) |
| return nil |
| } |
| |
| // readEvents reads from the inotify file descriptor, converts the |
| // received events into Event objects and sends them via the Event channel |
| func (w *Watcher) readEvents() { |
| var ( |
| buf [syscall.SizeofInotifyEvent * 4096]byte // Buffer for a maximum of 4096 raw events |
| n int // Number of bytes read with read() |
| errno error // Syscall errno |
| ) |
| |
| for { |
| // See if there is a message on the "done" channel |
| select { |
| case <-w.done: |
| syscall.Close(w.fd) |
| close(w.internalEvent) |
| close(w.Error) |
| return |
| default: |
| } |
| |
| n, errno = syscall.Read(w.fd, buf[:]) |
| |
| // If EOF is received |
| if n == 0 { |
| syscall.Close(w.fd) |
| close(w.internalEvent) |
| close(w.Error) |
| return |
| } |
| |
| if n < 0 { |
| w.Error <- os.NewSyscallError("read", errno) |
| continue |
| } |
| if n < syscall.SizeofInotifyEvent { |
| w.Error <- errors.New("inotify: short read in readEvents()") |
| continue |
| } |
| |
| var offset uint32 = 0 |
| // 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-syscall.SizeofInotifyEvent) { |
| // Point "raw" to the event in the buffer |
| raw := (*syscall.InotifyEvent)(unsafe.Pointer(&buf[offset])) |
| event := new(FileEvent) |
| event.mask = uint32(raw.Mask) |
| event.cookie = uint32(raw.Cookie) |
| nameLen := uint32(raw.Len) |
| // 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() |
| event.Name = w.paths[int(raw.Wd)] |
| w.mu.Unlock() |
| watchedName := event.Name |
| if nameLen > 0 { |
| // Point "bytes" at the first byte of the filename |
| bytes := (*[syscall.PathMax]byte)(unsafe.Pointer(&buf[offset+syscall.SizeofInotifyEvent])) |
| // The filename is padded with NUL bytes. TrimRight() gets rid of those. |
| event.Name += "/" + strings.TrimRight(string(bytes[0:nameLen]), "\000") |
| } |
| |
| // Send the events that are not ignored on the events channel |
| if !event.ignoreLinux() { |
| // Setup FSNotify flags (inherit from directory watch) |
| w.fsnmut.Lock() |
| if _, fsnFound := w.fsnFlags[event.Name]; !fsnFound { |
| if fsnFlags, watchFound := w.fsnFlags[watchedName]; watchFound { |
| w.fsnFlags[event.Name] = fsnFlags |
| } else { |
| w.fsnFlags[event.Name] = FSN_ALL |
| } |
| } |
| w.fsnmut.Unlock() |
| |
| w.internalEvent <- event |
| } |
| |
| // Move to the next event in the buffer |
| offset += syscall.SizeofInotifyEvent + nameLen |
| } |
| } |
| } |
| |
| // Certain types of events can be "ignored" and not sent over the Event |
| // channel. Such as events marked ignore by the kernel, or MODIFY events |
| // against files that do not exist. |
| func (e *FileEvent) ignoreLinux() bool { |
| // Ignore anything the inotify API says to ignore |
| if e.mask&sys_IN_IGNORED == sys_IN_IGNORED { |
| return true |
| } |
| |
| // If the event is not a DELETE or RENAME, the file must exist. |
| // Otherwise the event is ignored. |
| // *Note*: this was put in place because it was seen that a MODIFY |
| // event was sent after the DELETE. This ignores that MODIFY and |
| // assumes a DELETE will come or has come if the file doesn't exist. |
| if !(e.IsDelete() || e.IsRename()) { |
| _, statErr := os.Lstat(e.Name) |
| return os.IsNotExist(statErr) |
| } |
| return false |
| } |