1 ;;; filenotify.el --- watch files for changes on disk -*- lexical-binding:t -*-
3 ;; Copyright (C) 2013-2015 Free Software Foundation, Inc.
5 ;; Author: Michael Albinus <michael.albinus@gmx.de>
7 ;; This file is part of GNU Emacs.
9 ;; GNU Emacs is free software: you can redistribute it and/or modify
10 ;; it under the terms of the GNU General Public License as published by
11 ;; the Free Software Foundation, either version 3 of the License, or
12 ;; (at your option) any later version.
14 ;; GNU Emacs is distributed in the hope that it will be useful,
15 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
16 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 ;; GNU General Public License for more details.
19 ;; You should have received a copy of the GNU General Public License
20 ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
24 ;; This package is an abstraction layer from the different low-level
25 ;; file notification packages `gfilenotify', `inotify' and
30 (defconst file-notify--library
32 ((featurep 'gfilenotify) 'gfilenotify)
33 ((featurep 'inotify) 'inotify)
34 ((featurep 'w32notify) 'w32notify))
35 "Non-nil when Emacs has been compiled with file notification support.
36 The value is the name of the low-level file notification package
37 to be used for local file systems. Remote file notifications
38 could use another implementation.")
40 (defvar file-notify-descriptors (make-hash-table :test 'equal)
41 "Hash table for registered file notification descriptors.
42 A key in this hash table is the descriptor as returned from
43 `gfilenotify', `inotify', `w32notify' or a file name handler.
44 The value in the hash table is a list
46 (DIR (FILE . CALLBACK) (FILE . CALLBACK) ...)
48 Several values for a given DIR happen only for `inotify', when
49 different files from the same directory are watched.")
51 (defun file-notify--rm-descriptor (descriptor &optional what)
52 "Remove DESCRIPTOR from `file-notify-descriptors'.
53 DESCRIPTOR should be an object returned by `file-notify-add-watch'.
54 If it is registered in `file-notify-descriptors', a stopped event is sent.
55 WHAT is a file or directory name to be removed, needed just for `inotify'."
56 (let* ((desc (if (consp descriptor) (car descriptor) descriptor))
57 (file (if (consp descriptor) (cdr descriptor)))
58 (registered (gethash desc file-notify-descriptors))
59 (dir (car registered)))
61 (when (and (consp registered) (or (null what) (string-equal dir what)))
62 ;; Send `stopped' event.
63 (dolist (entry (cdr registered))
66 ,(or (and (stringp (car entry))
67 (expand-file-name (car entry) dir))
70 ;; Modify `file-notify-descriptors'.
72 (remhash desc file-notify-descriptors)
74 (delete (assoc file (cdr registered)) (cdr registered)))
75 (if (null (cdr registered))
76 (remhash desc file-notify-descriptors)
77 (puthash desc registered file-notify-descriptors))))))
79 ;; This function is used by `gfilenotify', `inotify' and `w32notify' events.
81 (defun file-notify-handle-event (event)
82 "Handle file system monitoring event.
83 If EVENT is a filewatch event, call its callback. It has the format
85 (file-notify (DESCRIPTOR ACTIONS FILE [FILE1-OR-COOKIE]) CALLBACK)
87 Otherwise, signal a `file-notify-error'."
89 ;;(message "file-notify-handle-event %S" event)
90 (if (and (eq (car event) 'file-notify)
91 (>= (length event) 3))
92 (funcall (nth 2 event) (nth 1 event))
93 (signal 'file-notify-error
94 (cons "Not a valid file-notify event" event))))
96 ;; Needed for `inotify' and `w32notify'. In the latter case, COOKIE is nil.
97 (defvar file-notify--pending-event nil
98 "A pending file notification events for a future `renamed' action.
99 It is a form ((DESCRIPTOR ACTION FILE [FILE1-OR-COOKIE]) CALLBACK).")
101 (defun file-notify--event-file-name (event)
102 "Return file name of file notification event, or nil."
105 (or (and (stringp (nth 2 event)) (nth 2 event)) "")
106 (car (gethash (car event) file-notify-descriptors)))))
108 ;; Only `gfilenotify' could return two file names.
109 (defun file-notify--event-file1-name (event)
110 "Return second file name of file notification event, or nil.
111 This is available in case a file has been moved."
112 (and (stringp (nth 3 event))
115 (nth 3 event) (car (gethash (car event) file-notify-descriptors))))))
117 ;; Cookies are offered by `inotify' only.
118 (defun file-notify--event-cookie (event)
119 "Return cookie of file notification event, or nil.
120 This is available in case a file has been moved."
123 ;; `inotify' returns the same descriptor when the file (directory)
124 ;; uses the same inode. We want to distinguish, and apply a virtual
125 ;; descriptor which make the difference.
126 (defun file-notify--descriptor (desc file)
127 "Return the descriptor to be used in `file-notify-*-watch'.
128 For `gfilenotify' and `w32notify' it is the same descriptor as
129 used in the low-level file notification package."
130 (if (and (natnump desc) (eq file-notify--library 'inotify))
134 (file-name-nondirectory file)
135 (gethash desc file-notify-descriptors)))))
138 ;; The callback function used to map between specific flags of the
139 ;; respective file notifications, and the ones we return.
140 (defun file-notify-callback (event)
141 "Handle an EVENT returned from file notification.
142 EVENT is the cadr of the event in `file-notify-handle-event'
143 \(DESCRIPTOR ACTIONS FILE [FILE1-OR-COOKIE])."
144 (let* ((desc (car event))
145 (registered (gethash desc file-notify-descriptors))
146 (actions (nth 1 event))
147 (file (file-notify--event-file-name event))
148 file1 callback pending-event stopped)
150 ;; Make actions a list.
151 (unless (consp actions) (setq actions (cons actions nil)))
153 ;; Loop over registered entries. In fact, more than one entry
154 ;; happens only for `inotify'.
155 (dolist (entry (cdr registered))
157 ;; Check, that event is meant for us.
158 (unless (setq callback (cdr entry))
161 ;; Loop over actions. In fact, more than one action happens only
163 (dolist (action actions)
165 ;; Send pending event, if it doesn't match.
166 (when (and file-notify--pending-event
167 ;; The cookie doesn't match.
168 (not (eq (file-notify--event-cookie
169 (car file-notify--pending-event))
170 (file-notify--event-cookie event)))
173 (and (eq (nth 1 (car file-notify--pending-event))
175 (not (eq action 'moved-to)))
177 (and (eq (nth 1 (car file-notify--pending-event))
179 (not (eq action 'renamed-to)))))
180 (setq pending-event file-notify--pending-event
181 file-notify--pending-event nil)
182 (setcar (cdar pending-event) 'deleted))
184 ;; Map action. We ignore all events which cannot be mapped.
188 ((memq action '(attribute-changed changed created deleted))
191 (setq file1 (file-notify--event-file1-name event))
194 ;; inotify, w32notify.
195 ((eq action 'ignored)
196 (setq stopped t actions nil))
197 ((eq action 'attrib) 'attribute-changed)
198 ((memq action '(create added)) 'created)
199 ((memq action '(modify modified)) 'changed)
200 ((memq action '(delete delete-self move-self removed)) 'deleted)
201 ;; Make the event pending.
202 ((memq action '(moved-from renamed-from))
203 (setq file-notify--pending-event
204 `((,desc ,action ,file ,(file-notify--event-cookie event))
207 ;; Look for pending event.
208 ((memq action '(moved-to renamed-to))
209 (if (null file-notify--pending-event)
212 file (file-notify--event-file-name
213 (car file-notify--pending-event)))
214 ;; If the source is handled by another watch, we
215 ;; must fire the rename event there as well.
216 (when (not (equal (file-notify--descriptor desc file1)
217 (file-notify--descriptor
218 (caar file-notify--pending-event)
219 (file-notify--event-file-name
220 file-notify--pending-event))))
222 `((,(caar file-notify--pending-event)
223 renamed ,file ,file1)
224 ,(cadr file-notify--pending-event))))
225 (setq file-notify--pending-event nil)
228 ;; Apply pending callback.
232 (file-notify--descriptor
234 (file-notify--event-file-name file-notify--pending-event)))
235 (funcall (cadr pending-event) (car pending-event))
236 (setq pending-event nil))
238 ;; Check for stopped.
239 ;;(message "file-notify-callback %S %S" file registered)
245 (memq action '(deleted renamed))
246 (= (length (cdr registered)) 1)
248 (file-name-nondirectory file)
249 (or (file-name-nondirectory (car registered))
250 (car (cadr registered)))))))
255 ;; If there is no relative file name for that watch,
256 ;; we watch the whole directory.
260 (nth 0 entry) (file-name-nondirectory file))
264 (nth 0 entry) (file-name-nondirectory file1)))))
268 `(,(file-notify--descriptor desc file) ,action ,file ,file1))
271 `(,(file-notify--descriptor desc file) ,action ,file)))))
273 ;; Modify `file-notify-descriptors'.
275 (file-notify--rm-descriptor
276 (file-notify--descriptor desc file) file)))))
278 ;; `gfilenotify' and `w32notify' return a unique descriptor for every
279 ;; `file-notify-add-watch', while `inotify' returns a unique
280 ;; descriptor per inode only.
281 (defun file-notify-add-watch (file flags callback)
282 "Add a watch for filesystem events pertaining to FILE.
283 This arranges for filesystem events pertaining to FILE to be reported
284 to Emacs. Use `file-notify-rm-watch' to cancel the watch.
286 The returned value is a descriptor for the added watch. If the
287 file cannot be watched for some reason, this function signals a
288 `file-notify-error' error.
290 FLAGS is a list of conditions to set what will be watched for. It can
291 include the following symbols:
293 `change' -- watch for file changes
294 `attribute-change' -- watch for file attributes changes, like
295 permissions or modification time
297 If FILE is a directory, `change' watches for file creation or
298 deletion in that directory. This does not work recursively.
300 When any event happens, Emacs will call the CALLBACK function passing
301 it a single argument EVENT, which is of the form
303 (DESCRIPTOR ACTION FILE [FILE1])
305 DESCRIPTOR is the same object as the one returned by this function.
306 ACTION is the description of the event. It could be any one of the
309 `created' -- FILE was created
310 `deleted' -- FILE was deleted
311 `changed' -- FILE has changed
312 `renamed' -- FILE has been renamed to FILE1
313 `attribute-changed' -- a FILE attribute was changed
314 `stopped' -- watching FILE has been stopped
316 FILE is the name of the file whose event is being reported."
318 (unless (stringp file)
319 (signal 'wrong-type-argument `(,file)))
320 (setq file (expand-file-name file))
321 (unless (and (consp flags)
322 (null (delq 'change (delq 'attribute-change (copy-tree flags)))))
323 (signal 'wrong-type-argument `(,flags)))
324 (unless (functionp callback)
325 (signal 'wrong-type-argument `(,callback)))
327 (let* ((handler (find-file-name-handler file 'file-notify-add-watch))
328 (dir (directory-file-name
329 (if (file-directory-p file)
331 (file-name-directory file))))
332 desc func l-flags registered)
334 (unless (file-directory-p dir)
335 (signal 'file-notify-error `("Directory does not exist" ,dir)))
338 ;; A file name handler could exist even if there is no local
339 ;; file notification support.
341 handler 'file-notify-add-watch dir flags callback))
343 ;; Check, whether Emacs has been compiled with file notification
345 (unless file-notify--library
346 (signal 'file-notify-error
347 '("No file notification package available")))
349 ;; Determine low-level function to be called.
352 ((eq file-notify--library 'gfilenotify) 'gfile-add-watch)
353 ((eq file-notify--library 'inotify) 'inotify-add-watch)
354 ((eq file-notify--library 'w32notify) 'w32notify-add-watch)))
356 ;; Determine respective flags.
357 (if (eq file-notify--library 'gfilenotify)
358 (setq l-flags (append '(watch-mounts send-moved) flags))
359 (when (memq 'change flags)
363 ((eq file-notify--library 'inotify)
364 '(create delete delete-self modify move-self move))
365 ((eq file-notify--library 'w32notify)
366 '(file-name directory-name size last-write-time)))))
367 (when (memq 'attribute-change flags)
369 ((eq file-notify--library 'inotify) 'attrib)
370 ((eq file-notify--library 'w32notify) 'attributes))
373 ;; Call low-level function.
374 (setq desc (funcall func dir l-flags 'file-notify-callback)))
376 ;; Modify `file-notify-descriptors'.
377 (setq registered (gethash desc file-notify-descriptors))
381 (,(unless (file-directory-p file) (file-name-nondirectory file))
384 file-notify-descriptors)
386 ;; Return descriptor.
387 (file-notify--descriptor
388 desc (unless (file-directory-p file) (file-name-nondirectory file)))))
390 (defun file-notify-rm-watch (descriptor)
391 "Remove an existing watch specified by its DESCRIPTOR.
392 DESCRIPTOR should be an object returned by `file-notify-add-watch'."
393 (let* ((desc (if (consp descriptor) (car descriptor) descriptor))
394 (file (if (consp descriptor) (cdr descriptor)))
395 (registered (gethash desc file-notify-descriptors))
396 (dir (car registered))
397 (handler (and (stringp dir)
398 (find-file-name-handler dir 'file-notify-rm-watch))))
401 ;; Call low-level function.
403 (and (= (length (cdr registered)) 1)
404 (assoc file (cdr registered))))
407 ;; A file name handler could exist even if there is no local
408 ;; file notification support.
409 (funcall handler 'file-notify-rm-watch descriptor)
413 ((eq file-notify--library 'gfilenotify) 'gfile-rm-watch)
414 ((eq file-notify--library 'inotify) 'inotify-rm-watch)
415 ((eq file-notify--library 'w32notify) 'w32notify-rm-watch))
417 (file-notify-error nil)))
419 ;; Modify `file-notify-descriptors'.
420 (file-notify--rm-descriptor descriptor))))
422 (defun file-notify-valid-p (descriptor)
423 "Check a watch specified by its DESCRIPTOR.
424 DESCRIPTOR should be an object returned by `file-notify-add-watch'."
425 (let* ((desc (if (consp descriptor) (car descriptor) descriptor))
426 (file (if (consp descriptor) (cdr descriptor)))
427 (registered (gethash desc file-notify-descriptors))
428 (dir (car registered))
432 (setq handler (find-file-name-handler dir 'file-notify-valid-p))
434 (and (or ;; It is a directory.
436 ;; The file is registered.
437 (assoc file (cdr registered)))
439 ;; A file name handler could exist even if there is no
440 ;; local file notification support.
441 (funcall handler 'file-notify-valid-p descriptor)
444 ((eq file-notify--library 'gfilenotify) 'gfile-valid-p)
445 ((eq file-notify--library 'inotify) 'inotify-valid-p)
446 ((eq file-notify--library 'w32notify) 'w32notify-valid-p))
451 (provide 'filenotify)
453 ;;; filenotify.el ends here