1 // Copyright 2010 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
6 Package inotify implements a wrapper for the Linux inotify system.
9 watcher, err := inotify.NewWatcher()
13 err = watcher.Watch("/tmp")
19 case ev := <-watcher.Event:
20 log.Println("event:", ev)
21 case err := <-watcher.Error:
22 log.Println("error:", err)
39 Mask uint32 // Mask of events
40 Cookie uint32 // Unique cookie associating related events (for rename(2))
41 Name string // File name (optional)
45 wd uint32 // Watch descriptor (as returned by the inotify_add_watch() syscall)
46 flags uint32 // inotify flags of this watch (see inotify(7) for the list of valid flags)
50 fd int // File descriptor (as returned by the inotify_init() syscall)
51 watches map[string]*watch // Map of inotify watches (key: path)
52 paths map[int]string // Map of watched paths (key: watch descriptor)
53 Error chan error // Errors are sent on this channel
54 Event chan *Event // Events are returned on this channel
55 done chan bool // Channel for sending a "quit message" to the reader goroutine
56 isClosed bool // Set to true when Close() is first called
59 // NewWatcher creates and returns a new inotify instance using inotify_init(2)
60 func NewWatcher() (*Watcher, error) {
61 fd, errno := syscall.InotifyInit()
63 return nil, os.NewSyscallError("inotify_init", errno)
67 watches: make(map[string]*watch),
68 paths: make(map[int]string),
69 Event: make(chan *Event),
70 Error: make(chan error),
71 done: make(chan bool, 1),
78 // Close closes an inotify watcher instance
79 // It sends a message to the reader goroutine to quit and removes all watches
80 // associated with the inotify instance
81 func (w *Watcher) Close() error {
87 // Send "quit" message to the reader goroutine
89 for path := range w.watches {
96 // AddWatch adds path to the watched file set.
97 // The flags are interpreted as described in inotify_add_watch(2).
98 func (w *Watcher) AddWatch(path string, flags uint32) error {
100 return errors.New("inotify instance already closed")
103 watchEntry, found := w.watches[path]
105 watchEntry.flags |= flags
106 flags |= syscall.IN_MASK_ADD
108 wd, errno := syscall.InotifyAddWatch(w.fd, path, flags)
110 return &os.PathError{"inotify_add_watch", path, os.Errno(errno)}
114 w.watches[path] = &watch{wd: uint32(wd), flags: flags}
120 // Watch adds path to the watched file set, watching all events.
121 func (w *Watcher) Watch(path string) error {
122 return w.AddWatch(path, IN_ALL_EVENTS)
125 // RemoveWatch removes path from the watched file set.
126 func (w *Watcher) RemoveWatch(path string) error {
127 watch, ok := w.watches[path]
129 return errors.New(fmt.Sprintf("can't remove non-existent inotify watch for: %s", path))
131 success, errno := syscall.InotifyRmWatch(w.fd, watch.wd)
133 return os.NewSyscallError("inotify_rm_watch", errno)
135 delete(w.watches, path)
139 // readEvents reads from the inotify file descriptor, converts the
140 // received events into Event objects and sends them via the Event channel
141 func (w *Watcher) readEvents() {
143 buf [syscall.SizeofInotifyEvent * 4096]byte // Buffer for a maximum of 4096 raw events
144 n int // Number of bytes read with read()
145 errno int // Syscall errno
149 n, errno = syscall.Read(w.fd, buf[0:])
150 // See if there is a message on the "done" channel
153 case done = <-w.done:
157 // If EOF or a "done" message is received
159 errno := syscall.Close(w.fd)
161 w.Error <- os.NewSyscallError("close", errno)
168 w.Error <- os.NewSyscallError("read", errno)
171 if n < syscall.SizeofInotifyEvent {
172 w.Error <- errors.New("inotify: short read in readEvents()")
176 var offset uint32 = 0
177 // We don't know how many events we just read into the buffer
178 // While the offset points to at least one whole event...
179 for offset <= uint32(n-syscall.SizeofInotifyEvent) {
180 // Point "raw" to the event in the buffer
181 raw := (*syscall.InotifyEvent)(unsafe.Pointer(&buf[offset]))
183 event.Mask = uint32(raw.Mask)
184 event.Cookie = uint32(raw.Cookie)
185 nameLen := uint32(raw.Len)
186 // If the event happened to the watched directory or the watched file, the kernel
187 // doesn't append the filename to the event, but we would like to always fill the
188 // the "Name" field with a valid filename. We retrieve the path of the watch from
190 event.Name = w.paths[int(raw.Wd)]
192 // Point "bytes" at the first byte of the filename
193 bytes := (*[syscall.PathMax]byte)(unsafe.Pointer(&buf[offset+syscall.SizeofInotifyEvent]))
194 // The filename is padded with NUL bytes. TrimRight() gets rid of those.
195 event.Name += "/" + strings.TrimRight(string(bytes[0:nameLen]), "\000")
197 // Send the event on the events channel
200 // Move to the next event in the buffer
201 offset += syscall.SizeofInotifyEvent + nameLen
206 // String formats the event e in the form
207 // "filename: 0xEventMask = IN_ACCESS|IN_ATTRIB_|..."
208 func (e *Event) String() string {
209 var events string = ""
212 for _, b := range eventBits {
215 events += "|" + b.Name
220 events += fmt.Sprintf("|%#x", m)
223 events = " == " + events[1:]
226 return fmt.Sprintf("%q: %#x%s", e.Name, e.Mask, events)
230 // Options for inotify_init() are not exported
231 // IN_CLOEXEC uint32 = syscall.IN_CLOEXEC
232 // IN_NONBLOCK uint32 = syscall.IN_NONBLOCK
234 // Options for AddWatch
235 IN_DONT_FOLLOW uint32 = syscall.IN_DONT_FOLLOW
236 IN_ONESHOT uint32 = syscall.IN_ONESHOT
237 IN_ONLYDIR uint32 = syscall.IN_ONLYDIR
239 // The "IN_MASK_ADD" option is not exported, as AddWatch
240 // adds it automatically, if there is already a watch for the given path
241 // IN_MASK_ADD uint32 = syscall.IN_MASK_ADD
244 IN_ACCESS uint32 = syscall.IN_ACCESS
245 IN_ALL_EVENTS uint32 = syscall.IN_ALL_EVENTS
246 IN_ATTRIB uint32 = syscall.IN_ATTRIB
247 IN_CLOSE uint32 = syscall.IN_CLOSE
248 IN_CLOSE_NOWRITE uint32 = syscall.IN_CLOSE_NOWRITE
249 IN_CLOSE_WRITE uint32 = syscall.IN_CLOSE_WRITE
250 IN_CREATE uint32 = syscall.IN_CREATE
251 IN_DELETE uint32 = syscall.IN_DELETE
252 IN_DELETE_SELF uint32 = syscall.IN_DELETE_SELF
253 IN_MODIFY uint32 = syscall.IN_MODIFY
254 IN_MOVE uint32 = syscall.IN_MOVE
255 IN_MOVED_FROM uint32 = syscall.IN_MOVED_FROM
256 IN_MOVED_TO uint32 = syscall.IN_MOVED_TO
257 IN_MOVE_SELF uint32 = syscall.IN_MOVE_SELF
258 IN_OPEN uint32 = syscall.IN_OPEN
261 IN_ISDIR uint32 = syscall.IN_ISDIR
262 IN_IGNORED uint32 = syscall.IN_IGNORED
263 IN_Q_OVERFLOW uint32 = syscall.IN_Q_OVERFLOW
264 IN_UNMOUNT uint32 = syscall.IN_UNMOUNT
267 var eventBits = []struct {
271 {IN_ACCESS, "IN_ACCESS"},
272 {IN_ATTRIB, "IN_ATTRIB"},
273 {IN_CLOSE, "IN_CLOSE"},
274 {IN_CLOSE_NOWRITE, "IN_CLOSE_NOWRITE"},
275 {IN_CLOSE_WRITE, "IN_CLOSE_WRITE"},
276 {IN_CREATE, "IN_CREATE"},
277 {IN_DELETE, "IN_DELETE"},
278 {IN_DELETE_SELF, "IN_DELETE_SELF"},
279 {IN_MODIFY, "IN_MODIFY"},
280 {IN_MOVE, "IN_MOVE"},
281 {IN_MOVED_FROM, "IN_MOVED_FROM"},
282 {IN_MOVED_TO, "IN_MOVED_TO"},
283 {IN_MOVE_SELF, "IN_MOVE_SELF"},
284 {IN_OPEN, "IN_OPEN"},
285 {IN_ISDIR, "IN_ISDIR"},
286 {IN_IGNORED, "IN_IGNORED"},
287 {IN_Q_OVERFLOW, "IN_Q_OVERFLOW"},
288 {IN_UNMOUNT, "IN_UNMOUNT"},