lisp/autorevert.el

   1 ;;; autorevert.el --- revert buffers when files on disk change
   2
   3 ;; Copyright (C) 1997-1999, 2001-2013 Free Software Foundation, Inc.
   4
   5 ;; Author: Anders Lindgren <andersl@andersl.com>
   6 ;; Keywords: convenience
   7 ;; Created: 1997-06-01
   8 ;; Date: 1999-11-30
   9
  10 ;; This file is part of GNU Emacs.
  11
  12 ;; GNU Emacs is free software: you can redistribute it and/or modify
  13 ;; it under the terms of the GNU General Public License as published by
  14 ;; the Free Software Foundation, either version 3 of the License, or
  15 ;; (at your option) any later version.
  16
  17 ;; GNU Emacs is distributed in the hope that it will be useful,
  18 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20 ;; GNU General Public License for more details.
  21
  22 ;; You should have received a copy of the GNU General Public License
  23 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  24
  25 ;;; Commentary:
  26
  27 ;; Introduction:
  28 ;;
  29 ;; Whenever a file that Emacs is editing has been changed by another
  30 ;; program the user normally has to execute the command `revert-buffer'
  31 ;; to load the new content of the file into Emacs.
  32 ;;
  33 ;; This package contains two minor modes: Global Auto-Revert Mode and
  34 ;; Auto-Revert Mode.  Both modes automatically revert buffers
  35 ;; whenever the corresponding files have been changed on disk and the
  36 ;; buffer contains no unsaved changes.
  37 ;;
  38 ;; Auto-Revert Mode can be activated for individual buffers.  Global
  39 ;; Auto-Revert Mode applies to all file buffers. (If the user option
  40 ;; `global-auto-revert-non-file-buffers' is non-nil, it also applies
  41 ;; to some non-file buffers.  This option is disabled by default.)
  42 ;; Since checking a remote file is too slow, these modes do not check
  43 ;; or revert remote files.
  44 ;;
  45 ;; Both modes operate by checking the time stamp of all files at
  46 ;; intervals of `auto-revert-interval'.  The default is every five
  47 ;; seconds.  The check is aborted whenever the user actually uses
  48 ;; Emacs.  You should never even notice that this package is active
  49 ;; (except that your buffers will be reverted, of course).
  50 ;;
  51 ;; If Emacs is compiled with file watch support, notifications are
  52 ;; used instead of checking the time stamp of the files.  You can
  53 ;; disable this by setting the user option `auto-revert-use-notify' to
  54 ;; nil.
  55 ;;
  56 ;; After reverting a file buffer, Auto Revert Mode normally puts point
  57 ;; at the same position that a regular manual revert would.  However,
  58 ;; there is one exception to this rule.  If point is at the end of the
  59 ;; buffer before reverting, it stays at the end.  Similarly if point
  60 ;; is displayed at the end of a file buffer in any window, it will stay
  61 ;; at the end of the buffer in that window, even if the window is not
  62 ;; selected.  This way, you can use Auto Revert Mode to `tail' a file.
  63 ;; Just put point at the end of the buffer and it will stay there.
  64 ;; These rules apply to file buffers. For non-file buffers, the
  65 ;; behavior may be mode dependent.
  66 ;;
  67 ;; While you can use Auto Revert Mode to tail a file, this package
  68 ;; contains a third minor mode, Auto Revert Tail Mode, which does so
  69 ;; more efficiently, as long as you are sure that the file will only
  70 ;; change by growing at the end.  It only appends the new output,
  71 ;; instead of reverting the entire buffer.  It does so even if the
  72 ;; buffer contains unsaved changes.  (Because they will not be lost.)
  73 ;; Auto Revert Tail Mode works also for remote files.
  74
  75 ;; Usage:
  76 ;;
  77 ;; Go to the appropriate buffer and press either of:
  78 ;;   M-x auto-revert-mode RET
  79 ;;   M-x auto-revert-tail-mode RET
  80 ;;
  81 ;; To activate Global Auto-Revert Mode, press:
  82 ;;   M-x global-auto-revert-mode RET
  83 ;;
  84 ;; To activate Global Auto-Revert Mode every time Emacs is started
  85 ;; customize the option `global-auto-revert-mode' or the following
  86 ;; line could be added to your ~/.emacs:
  87 ;;   (global-auto-revert-mode 1)
  88 ;;
  89 ;; The function `turn-on-auto-revert-mode' could be added to any major
  90 ;; mode hook to activate Auto-Revert Mode for all buffers in that
  91 ;; mode.  For example, the following line will activate Auto-Revert
  92 ;; Mode in all C mode buffers:
  93 ;;
  94 ;; (add-hook 'c-mode-hook 'turn-on-auto-revert-mode)
  95
  96 ;;; Code:
  97
  98 ;; Dependencies:
  99
 100 (eval-when-compile (require 'cl-lib))
 101 (require 'timer)
 102
 103 ;; Custom Group:
 104 ;;
 105 ;; The two modes will be placed next to Auto Save Mode under the
 106 ;; Files group under Emacs.
 107
 108 (defgroup auto-revert nil
 109   "Revert individual buffers when files on disk change.
 110 Auto-Revert mode enables auto-revert in individual buffers.
 111 Global Auto-Revert mode does so in all buffers."
 112   :group 'files
 113   :group 'convenience)
 114
 115
 116 ;; Variables:
 117
 118 ;;; What's this?: ;; Autoload for the benefit of `make-mode-line-mouse-sensitive'.
 119 ;;; What's this?: ;;;###autoload
 120 (defvar auto-revert-mode nil
 121   "Non-nil when Auto-Revert Mode is active.
 122 Never set this variable directly, use the command `auto-revert-mode' instead.")
 123 (put 'auto-revert-mode 'permanent-local t)
 124
 125 (defvar auto-revert-tail-mode nil
 126   "Non-nil when Auto-Revert Tail Mode is active.
 127 Never set this variable directly, use the command
 128 `auto-revert-tail-mode' instead.")
 129 (put 'auto-revert-tail-mode 'permanent-local t)
 130
 131 (defvar auto-revert-timer nil
 132   "Timer used by Auto-Revert Mode.")
 133
 134 (defcustom auto-revert-interval 5
 135   "Time, in seconds, between Auto-Revert Mode file checks.
 136 The value may be an integer or floating point number.
 137
 138 If a timer is already active, there are two ways to make sure
 139 that the new value will take effect immediately.  You can set
 140 this variable through Custom or you can call the command
 141 `auto-revert-set-timer' after setting the variable.  Otherwise,
 142 the new value will take effect the first time Auto Revert Mode
 143 calls `auto-revert-set-timer' for internal reasons or in your
 144 next editing session."
 145   :group 'auto-revert
 146   :type 'number
 147   :set (lambda (variable value)
 148          (set-default variable value)
 149          (and (boundp 'auto-revert-timer)
 150               auto-revert-timer
 151               (auto-revert-set-timer))))
 152
 153 (defcustom auto-revert-stop-on-user-input t
 154   "When non-nil, user input temporarily interrupts Auto-Revert Mode.
 155 With this setting, Auto-Revert Mode checks for user input after
 156 handling each buffer and does not process any further buffers
 157 \(until the next run of the timer) if user input is available.
 158 When nil, Auto-Revert Mode checks files and reverts buffers,
 159 with quitting disabled, without paying attention to user input.
 160 Thus, with this setting, Emacs might be non-responsive at times."
 161   :group 'auto-revert
 162   :type 'boolean)
 163
 164 (defcustom auto-revert-verbose t
 165   "When nil, Auto-Revert Mode does not generate any messages.
 166 When non-nil, a message is generated whenever a file is reverted."
 167   :group 'auto-revert
 168   :type 'boolean)
 169
 170 (defcustom auto-revert-mode-text " ARev"
 171   "String to display in the mode line when Auto-Revert Mode is active.
 172
 173 \(When the string is not empty, make sure that it has a leading space.)"
 174   :tag "Auto Revert Mode Text"          ; To separate it from `global-...'
 175   :group 'auto-revert
 176   :type 'string)
 177
 178 (defcustom auto-revert-tail-mode-text " Tail"
 179   "String to display in the mode line when Auto-Revert Tail Mode is active.
 180
 181 \(When the string is not empty, make sure that it has a leading space.)"
 182   :group 'auto-revert
 183   :type 'string
 184   :version "22.1")
 185
 186 (defcustom auto-revert-mode-hook nil
 187   "Functions to run when Auto-Revert Mode is activated."
 188   :tag "Auto Revert Mode Hook"          ; To separate it from `global-...'
 189   :group 'auto-revert
 190   :type 'hook)
 191
 192 (defcustom global-auto-revert-mode-text ""
 193   "String to display when Global Auto-Revert Mode is active.
 194
 195 The default is nothing since when this mode is active this text doesn't
 196 vary over time, or between buffers.  Hence mode line text
 197 would only waste precious space."
 198   :group 'auto-revert
 199   :type 'string)
 200
 201 (defcustom global-auto-revert-mode-hook nil
 202   "Hook called when Global Auto-Revert Mode is activated."
 203   :group 'auto-revert
 204   :type 'hook)
 205
 206 (defcustom global-auto-revert-non-file-buffers nil
 207   "When nil, Global Auto-Revert mode operates only on file-visiting buffers.
 208
 209 When non-nil, both file buffers and buffers with a custom
 210 `revert-buffer-function' and a `buffer-stale-function' are
 211 reverted by Global Auto-Revert mode.  These include the Buffer
 212 List buffer displayed by `buffer-menu', and Dired buffers showing
 213 complete local directories.  The Buffer List buffer reverts every
 214 `auto-revert-interval' seconds; Dired buffers when the file list of
 215 the main directory changes.  Dired buffers do not auto-revert as
 216 a result of changes in subdirectories, or in the contents, size,
 217 modes, etc., of files.  You may still sometimes want to revert
 218 them manually.
 219
 220 Use this option with care since it could lead to excessive auto-reverts.
 221 For more information, see Info node `(emacs)Autorevert'."
 222   :group 'auto-revert
 223   :type 'boolean
 224   :link '(info-link "(emacs)Autorevert"))
 225
 226 (defcustom global-auto-revert-ignore-modes ()
 227   "List of major modes Global Auto-Revert Mode should not check."
 228   :group 'auto-revert
 229   :type '(repeat sexp))
 230
 231 (defcustom auto-revert-load-hook nil
 232   "Functions to run when Auto-Revert Mode is first loaded."
 233   :tag "Load Hook"
 234   :group 'auto-revert
 235   :type 'hook)
 236
 237 (defcustom auto-revert-check-vc-info nil
 238   "If non-nil Auto Revert Mode reliably updates version control info.
 239 Auto Revert Mode updates version control info whenever the buffer
 240 needs reverting, regardless of the value of this variable.
 241 However, the version control state can change without changes to
 242 the work file.  If the change is made from the current Emacs
 243 session, all info is updated.  But if, for instance, a new
 244 version is checked in from outside the current Emacs session, the
 245 version control number in the mode line, as well as other version
 246 control related information, may not be properly updated.  If you
 247 are worried about this, set this variable to a non-nil value.
 248
 249 This currently works by automatically updating the version
 250 control info every `auto-revert-interval' seconds.  Nevertheless,
 251 it should not cause excessive CPU usage on a reasonably fast
 252 machine, if it does not apply to too many version controlled
 253 buffers.  CPU usage depends on the version control system."
 254   :group 'auto-revert
 255   :type 'boolean
 256   :version "22.1")
 257
 258 (defvar global-auto-revert-ignore-buffer nil
 259   "When non-nil, Global Auto-Revert Mode will not revert this buffer.
 260 This variable becomes buffer local when set in any fashion.")
 261 (make-variable-buffer-local 'global-auto-revert-ignore-buffer)
 262
 263 (defconst auto-revert-notify-enabled
 264   (or (featurep 'inotify) (featurep 'w32notify))
 265   "Non-nil when Emacs has been compiled with file watch support.")
 266
 267 (defcustom auto-revert-use-notify auto-revert-notify-enabled
 268   "If non-nil Auto Revert Mode uses file watch functions.
 269 This requires Emacs being compiled with file watch support (see
 270 `auto-revert-notify-enabled').  You should set this variable
 271 through Custom only."
 272   :group 'auto-revert
 273   :type 'boolean
 274   :set (lambda (variable value)
 275          (set-default variable (and auto-revert-notify-enabled value))
 276          (if (symbol-value variable)
 277              (add-hook 'kill-buffer-hook 'auto-revert-notify-rm-watch)
 278            (remove-hook 'kill-buffer-hook 'auto-revert-notify-rm-watch)
 279            (when auto-revert-notify-enabled
 280              (dolist (buf (buffer-list))
 281                (with-current-buffer buf
 282                  (auto-revert-notify-rm-watch))))))
 283   :version "24.4")
 284
 285 ;; Internal variables:
 286
 287 (defvar auto-revert-buffer-list ()
 288   "List of buffers in Auto-Revert Mode.
 289
 290 Note that only Auto-Revert Mode, never Global Auto-Revert Mode, adds
 291 buffers to this list.
 292
 293 The timer function `auto-revert-buffers' is responsible for purging
 294 the list of old buffers.")
 295
 296 (defvar auto-revert-remaining-buffers ()
 297   "Buffers not checked when user input stopped execution.")
 298
 299 (defvar auto-revert-tail-pos 0
 300   "Position of last known end of file.")
 301
 302 (add-hook 'find-file-hook
 303           (lambda ()
 304             (set (make-local-variable 'auto-revert-tail-pos)
 305                  (nth 7 (file-attributes buffer-file-name)))))
 306
 307 (defvar auto-revert-notify-watch-descriptor-hash-list
 308   (make-hash-table :test 'equal)
 309   "A hash table collecting all file watch descriptors.
 310 Hash key is a watch descriptor, hash value is the corresponding buffer.")
 311
 312 (defvar auto-revert-notify-watch-descriptor nil
 313   "The file watch descriptor active for the current buffer.")
 314 (put 'auto-revert-notify-watch-descriptor 'permanent-local t)
 315
 316 (defvar auto-revert-notify-modified-p nil
 317   "Non-nil when file has been modified on the file system.
 318 This has been reported by a file watch event.")
 319 (make-variable-buffer-local 'auto-revert-notify-modified-p)
 320
 321 ;; Functions:
 322
 323 ;;;###autoload
 324 (define-minor-mode auto-revert-mode
 325   "Toggle reverting buffer when the file changes (Auto Revert mode).
 326 With a prefix argument ARG, enable Auto Revert mode if ARG is
 327 positive, and disable it otherwise.  If called from Lisp, enable
 328 the mode if ARG is omitted or nil.
 329
 330 Auto Revert mode is a minor mode that affects only the current
 331 buffer.  When enabled, it reverts the buffer when the file on
 332 disk changes.
 333
 334 Use `global-auto-revert-mode' to automatically revert all buffers.
 335 Use `auto-revert-tail-mode' if you know that the file will only grow
 336 without being changed in the part that is already in the buffer."
 337   :group 'auto-revert :lighter auto-revert-mode-text
 338   (if auto-revert-mode
 339       (if (not (memq (current-buffer) auto-revert-buffer-list))
 340           (push (current-buffer) auto-revert-buffer-list))
 341     (when auto-revert-use-notify (auto-revert-notify-rm-watch))
 342     (setq auto-revert-buffer-list
 343           (delq (current-buffer) auto-revert-buffer-list)))
 344   (auto-revert-set-timer)
 345   (when auto-revert-mode
 346     (auto-revert-buffers)
 347     (setq auto-revert-tail-mode nil)))
 348
 349
 350 ;;;###autoload
 351 (defun turn-on-auto-revert-mode ()
 352   "Turn on Auto-Revert Mode.
 353
 354 This function is designed to be added to hooks, for example:
 355   (add-hook 'c-mode-hook 'turn-on-auto-revert-mode)"
 356   (auto-revert-mode 1))
 357
 358
 359 ;;;###autoload
 360 (define-minor-mode auto-revert-tail-mode
 361   "Toggle reverting tail of buffer when the file grows.
 362 With a prefix argument ARG, enable Auto-Revert Tail mode if ARG
 363 is positive, and disable it otherwise.  If called from Lisp,
 364 enable the mode if ARG is omitted or nil.
 365
 366 When Auto Revert Tail mode is enabled, the tail of the file is
 367 constantly followed, as with the shell command `tail -f'.  This
 368 means that whenever the file grows on disk (presumably because
 369 some background process is appending to it from time to time),
 370 this is reflected in the current buffer.
 371
 372 You can edit the buffer and turn this mode off and on again as
 373 you please.  But make sure the background process has stopped
 374 writing before you save the file!
 375
 376 Use `auto-revert-mode' for changes other than appends!"
 377   :group 'find-file :lighter auto-revert-tail-mode-text
 378   (when auto-revert-tail-mode
 379     (unless buffer-file-name
 380       (auto-revert-tail-mode 0)
 381       (error "This buffer is not visiting a file"))
 382     (if (and (buffer-modified-p)
 383              (zerop auto-revert-tail-pos) ; library was loaded only after finding file
 384              (not (y-or-n-p "Buffer is modified, so tail offset may be wrong.  Proceed? ")))
 385         (auto-revert-tail-mode 0)
 386       ;; a-r-tail-pos stores the size of the file at the time of the
 387       ;; last revert. After this package loads, it adds a
 388       ;; find-file-hook to set this variable every time a file is
 389       ;; loaded.  If the package is loaded only _after_ visiting the
 390       ;; file to be reverted, then we have no idea what the value of
 391       ;; a-r-tail-pos should have been when the file was visited.  If
 392       ;; the file has changed on disk in the meantime, all we can do
 393       ;; is offer to revert the whole thing. If you choose not to
 394       ;; revert, then you might miss some output then happened
 395       ;; between visiting the file and activating a-r-t-mode.
 396       (and (zerop auto-revert-tail-pos)
 397            (not (verify-visited-file-modtime (current-buffer)))
 398            (y-or-n-p "File changed on disk, content may be missing.  \
 399 Perform a full revert? ")
 400            ;; Use this (not just revert-buffer) for point-preservation.
 401            (auto-revert-handler))
 402       ;; else we might reappend our own end when we save
 403       (add-hook 'before-save-hook (lambda () (auto-revert-tail-mode 0)) nil t)
 404       (or (local-variable-p 'auto-revert-tail-pos) ; don't lose prior position
 405           (set (make-local-variable 'auto-revert-tail-pos)
 406                (nth 7 (file-attributes buffer-file-name))))
 407       ;; let auto-revert-mode set up the mechanism for us if it isn't already
 408       (or auto-revert-mode
 409           (let ((auto-revert-tail-mode t))
 410             (auto-revert-mode 1)))
 411       (setq auto-revert-mode nil))))
 412
 413
 414 ;;;###autoload
 415 (defun turn-on-auto-revert-tail-mode ()
 416   "Turn on Auto-Revert Tail mode.
 417
 418 This function is designed to be added to hooks, for example:
 419   (add-hook 'my-logfile-mode-hook 'turn-on-auto-revert-tail-mode)"
 420   (auto-revert-tail-mode 1))
 421
 422
 423 ;;;###autoload
 424 (define-minor-mode global-auto-revert-mode
 425   "Toggle Global Auto Revert mode.
 426 With a prefix argument ARG, enable Global Auto Revert mode if ARG
 427 is positive, and disable it otherwise.  If called from Lisp,
 428 enable the mode if ARG is omitted or nil.
 429
 430 Global Auto Revert mode is a global minor mode that reverts any
 431 buffer associated with a file when the file changes on disk.  Use
 432 `auto-revert-mode' to revert a particular buffer.
 433
 434 If `global-auto-revert-non-file-buffers' is non-nil, this mode
 435 may also revert some non-file buffers, as described in the
 436 documentation of that variable.  It ignores buffers with modes
 437 matching `global-auto-revert-ignore-modes', and buffers with a
 438 non-nil vale of `global-auto-revert-ignore-buffer'.
 439
 440 This function calls the hook `global-auto-revert-mode-hook'.
 441 It displays the text that `global-auto-revert-mode-text'
 442 specifies in the mode line."
 443   :global t :group 'auto-revert :lighter global-auto-revert-mode-text
 444   (auto-revert-set-timer)
 445   (if global-auto-revert-mode
 446       (auto-revert-buffers)
 447     (when auto-revert-use-notify
 448       (dolist (buf (buffer-list))
 449         (with-current-buffer buf
 450           (auto-revert-notify-rm-watch))))))
 451
 452 (defun auto-revert-set-timer ()
 453   "Restart or cancel the timer used by Auto-Revert Mode.
 454 If such a timer is active, cancel it.  Start a new timer if
 455 Global Auto-Revert Mode is active or if Auto-Revert Mode is active
 456 in some buffer.  Restarting the timer ensures that Auto-Revert Mode
 457 will use an up-to-date value of `auto-revert-interval'"
 458   (interactive)
 459   (if (timerp auto-revert-timer)
 460       (cancel-timer auto-revert-timer))
 461   (setq auto-revert-timer
 462         (if (or global-auto-revert-mode auto-revert-buffer-list)
 463             (run-with-timer auto-revert-interval
 464                             auto-revert-interval
 465                             'auto-revert-buffers))))
 466
 467 (defun auto-revert-notify-rm-watch ()
 468   "Disable file watch for current buffer's associated file."
 469   (when auto-revert-notify-watch-descriptor
 470     (ignore-errors
 471       (funcall (if (fboundp 'inotify-rm-watch)
 472                    'inotify-rm-watch 'w32notify-rm-watch)
 473                auto-revert-notify-watch-descriptor))
 474     (remhash auto-revert-notify-watch-descriptor
 475              auto-revert-notify-watch-descriptor-hash-list))
 476   (setq auto-revert-notify-watch-descriptor nil
 477         auto-revert-notify-modified-p nil))
 478
 479 (defun auto-revert-notify-add-watch ()
 480   "Enable file watch for current buffer's associated file."
 481   (when (and buffer-file-name auto-revert-use-notify)
 482     (auto-revert-notify-rm-watch)
 483     (let ((func (if (fboundp 'inotify-add-watch)
 484                     'inotify-add-watch 'w32notify-add-watch))
 485           (aspect (if (fboundp 'inotify-add-watch)
 486                       '(modify) '(size last-write-time))))
 487       (setq auto-revert-notify-watch-descriptor
 488             (ignore-errors
 489               (funcall
 490                func buffer-file-name aspect 'auto-revert-notify-handler)))
 491       (if auto-revert-notify-watch-descriptor
 492           (puthash auto-revert-notify-watch-descriptor
 493                    (current-buffer)
 494                    auto-revert-notify-watch-descriptor-hash-list)
 495         ;; Fallback to file checks.
 496         (set (make-local-variable 'auto-revert-use-notify) nil)))))
 497
 498 (defun auto-revert-notify-event-p (event)
 499   "Check that event is a file watch event."
 500   (cond ((featurep 'inotify)
 501          (and (listp event) (= (length event) 4)))
 502         ((featurep 'w32notify)
 503          (and (listp event) (= (length event) 3) (stringp (nth 2 event))))))
 504
 505 (defun auto-revert-notify-event-descriptor (event)
 506   "Return watch descriptor of notification event, or nil."
 507   (and (auto-revert-notify-event-p event) (car event)))
 508
 509 (defun auto-revert-notify-event-action (event)
 510   "Return action of notification event, or nil."
 511   (and (auto-revert-notify-event-p event) (nth 1 event)))
 512
 513 (defun auto-revert-notify-event-file-name (event)
 514   "Return file name of notification event, or nil."
 515   (and (auto-revert-notify-event-p event)
 516        (cond ((featurep 'inotify) (nth 3 event))
 517              ((featurep 'w32notify) (nth 2 event)))))
 518
 519 (defun auto-revert-notify-handler (event)
 520   "Handle an event returned from file watch."
 521   (when (auto-revert-notify-event-p event)
 522     (let* ((descriptor (auto-revert-notify-event-descriptor event))
 523            (action (auto-revert-notify-event-action event))
 524            (file (auto-revert-notify-event-file-name event))
 525            (buffer (gethash descriptor
 526                             auto-revert-notify-watch-descriptor-hash-list)))
 527       (ignore-errors
 528         ;; Check, that event is meant for us.
 529         ;; TODO: Filter events which stop watching, like `move' or `removed'.
 530         (cl-assert descriptor)
 531         (when (featurep 'inotify) (cl-assert (memq 'modify action)))
 532         (when (featurep 'w32notify) (cl-assert (eq 'modified action)))
 533         (cl-assert (bufferp buffer))
 534         (when (stringp file)
 535           (cl-assert (string-equal
 536                       ;; w32notify returns the basename of the file
 537                       ;; without its leading directories; inotify
 538                       ;; returns its full absolute file name.
 539                       (file-name-nondirectory (directory-file-name file))
 540                       (file-name-nondirectory (directory-file-name
 541                                                (buffer-file-name buffer))))))
 542
 543         ;; Mark buffer modified.
 544         (with-current-buffer buffer
 545           (setq auto-revert-notify-modified-p t))))))
 546
 547 (defun auto-revert-active-p ()
 548   "Check if auto-revert is active (in current buffer or globally)."
 549   (or auto-revert-mode
 550       auto-revert-tail-mode
 551       (and
 552        global-auto-revert-mode
 553        (not global-auto-revert-ignore-buffer)
 554        (not (memq major-mode
 555                   global-auto-revert-ignore-modes)))))
 556
 557 (defun auto-revert-handler ()
 558   "Revert current buffer, if appropriate.
 559 This is an internal function used by Auto-Revert Mode."
 560   (when (or auto-revert-tail-mode (not (buffer-modified-p)))
 561     (let* ((buffer (current-buffer)) size
 562            (revert
 563             (or (and buffer-file-name
 564                      (or (not auto-revert-use-notify)
 565                          auto-revert-notify-modified-p)
 566                      (if auto-revert-tail-mode
 567                          ;; Tramp caches the file attributes.  Setting
 568                          ;; `remote-file-name-inhibit-cache' forces Tramp
 569                          ;; to reread the values.
 570                          (let ((remote-file-name-inhibit-cache t))
 571                            (and (file-readable-p buffer-file-name)
 572                                 (/= auto-revert-tail-pos
 573                                     (setq size
 574                                           (nth 7 (file-attributes
 575                                                   buffer-file-name))))))
 576                        (and (not (file-remote-p buffer-file-name))
 577                             (file-readable-p buffer-file-name)
 578                             (not (verify-visited-file-modtime buffer)))))
 579                 (and (or auto-revert-mode
 580                          global-auto-revert-non-file-buffers)
 581                      revert-buffer-function
 582                      (boundp 'buffer-stale-function)
 583                      (functionp buffer-stale-function)
 584                      (funcall buffer-stale-function t))))
 585            eob eoblist)
 586       (when revert
 587         (setq auto-revert-notify-modified-p nil)
 588         (when (and auto-revert-verbose
 589                    (not (eq revert 'fast)))
 590           (message "Reverting buffer `%s'." (buffer-name)))
 591         ;; If point (or a window point) is at the end of the buffer,
 592         ;; we want to keep it at the end after reverting.  This allows
 593         ;; to tail a file.
 594         (when buffer-file-name
 595           (setq eob (eobp))
 596           (walk-windows
 597            (lambda (window)
 598              (and (eq (window-buffer window) buffer)
 599                   (= (window-point window) (point-max))
 600                   (push window eoblist)))
 601            'no-mini t))
 602         (if auto-revert-tail-mode
 603             (auto-revert-tail-handler size)
 604           ;; Bind buffer-read-only in case user has done C-x C-q,
 605           ;; so as not to forget that.  This gives undesirable results
 606           ;; when the file's mode changes, but that is less common.
 607           (let ((buffer-read-only buffer-read-only))
 608             (revert-buffer 'ignore-auto 'dont-ask 'preserve-modes)))
 609         (when buffer-file-name
 610           (when eob (goto-char (point-max)))
 611           (dolist (window eoblist)
 612             (set-window-point window (point-max)))))
 613       ;; `preserve-modes' avoids changing the (minor) modes.  But we
 614       ;; do want to reset the mode for VC, so we do it manually.
 615       (when (or revert auto-revert-check-vc-info)
 616         (vc-find-file-hook)))))
 617
 618 (defun auto-revert-tail-handler (size)
 619   (let ((modified (buffer-modified-p))
 620         (inhibit-read-only t)           ; Ignore.
 621         (file buffer-file-name)
 622         (buffer-file-name nil))         ; Ignore that file has changed.
 623     (when (/= auto-revert-tail-pos size)
 624       (run-hooks 'before-revert-hook)
 625       (undo-boundary)
 626       (save-restriction
 627         (widen)
 628         (save-excursion
 629           (goto-char (point-max))
 630           (insert-file-contents file nil
 631                                 (and (< auto-revert-tail-pos size)
 632                                      auto-revert-tail-pos)
 633                                 size)))
 634       (run-hooks 'after-revert-hook)
 635       (undo-boundary)
 636       (setq auto-revert-tail-pos size)
 637       (restore-buffer-modified-p modified)))
 638   (set-visited-file-modtime))
 639
 640 (defun auto-revert-buffers ()
 641   "Revert buffers as specified by Auto-Revert and Global Auto-Revert Mode.
 642
 643 Should `global-auto-revert-mode' be active all file buffers are checked.
 644
 645 Should `auto-revert-mode' be active in some buffers, those buffers
 646 are checked.
 647
 648 Non-file buffers that have a custom `revert-buffer-function' and
 649 a `buffer-stale-function' are reverted either when Auto-Revert
 650 Mode is active in that buffer, or when the variable
 651 `global-auto-revert-non-file-buffers' is non-nil and Global
 652 Auto-Revert Mode is active.
 653
 654 This function stops whenever there is user input.  The buffers not
 655 checked are stored in the variable `auto-revert-remaining-buffers'.
 656
 657 To avoid starvation, the buffers in `auto-revert-remaining-buffers'
 658 are checked first the next time this function is called.
 659
 660 This function is also responsible for removing buffers no longer in
 661 Auto-Revert mode from `auto-revert-buffer-list', and for canceling
 662 the timer when no buffers need to be checked."
 663   (save-match-data
 664     (let ((bufs (if global-auto-revert-mode
 665                     (buffer-list)
 666                   auto-revert-buffer-list))
 667           (remaining ())
 668           (new ()))
 669       ;; Partition `bufs' into two halves depending on whether or not
 670       ;; the buffers are in `auto-revert-remaining-buffers'.  The two
 671       ;; halves are then re-joined with the "remaining" buffers at the
 672       ;; head of the list.
 673       (dolist (buf auto-revert-remaining-buffers)
 674         (if (memq buf bufs)
 675             (push buf remaining)))
 676       (dolist (buf bufs)
 677         (if (not (memq buf remaining))
 678             (push buf new)))
 679       (setq bufs (nreverse (nconc new remaining)))
 680       (while (and bufs
 681                   (not (and auto-revert-stop-on-user-input
 682                             (input-pending-p))))
 683         (let ((buf (car bufs)))
 684           (if (buffer-live-p buf)
 685               (with-current-buffer buf
 686                 ;; Test if someone has turned off Auto-Revert Mode in a
 687                 ;; non-standard way, for example by changing major mode.
 688                 (if (and (not auto-revert-mode)
 689                          (not auto-revert-tail-mode)
 690                          (memq buf auto-revert-buffer-list))
 691                     (setq auto-revert-buffer-list
 692                           (delq buf auto-revert-buffer-list)))
 693                 (when (auto-revert-active-p)
 694                   ;; Enable file watches.
 695                   (when (and auto-revert-use-notify buffer-file-name
 696                              (not auto-revert-notify-watch-descriptor)
 697                       (auto-revert-notify-add-watch)))
 698                   (auto-revert-handler)))
 699             ;; Remove dead buffer from `auto-revert-buffer-list'.
 700             (setq auto-revert-buffer-list
 701                   (delq buf auto-revert-buffer-list))))
 702         (setq bufs (cdr bufs)))
 703       (setq auto-revert-remaining-buffers bufs)
 704       ;; Check if we should cancel the timer.
 705       (when (and (not global-auto-revert-mode)
 706                  (null auto-revert-buffer-list))
 707         (cancel-timer auto-revert-timer)
 708         (setq auto-revert-timer nil)))))
 709
 710
 711 ;; The end:
 712 (provide 'autorevert)
 713
 714 (run-hooks 'auto-revert-load-hook)
 715
 716 ;;; autorevert.el ends here