summaryrefslogtreecommitdiff
path: root/lisp/shadowfile.el
blob: 6d432f6caba0d5cf1922df7c374c37eb537aee0e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
;;; shadowfile.el --- automatic file copying

;; Copyright (C) 1993-1994, 2001-2012 Free Software Foundation, Inc.

;; Author: Boris Goldowsky <boris@gnu.org>
;; Keywords: comm files

;; This file is part of GNU Emacs.

;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.

;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.

;;; Commentary:

;;  This package helps you to keep identical copies of files in more than one
;;  place - possibly on different machines.  When you save a file, it checks
;;  whether it is on the list of files with "shadows", and if so, it tries to
;;  copy it when you exit Emacs (or use the shadow-copy-files command).

;; Installation & Use:

;;  Add clusters (if necessary) and file groups with shadow-define-cluster,
;;  shadow-define-literal-group, and shadow-define-regexp-group (see the
;;  documentation for these functions for information on how and when to use
;;  them).  After doing this once, everything should be automatic.

;;  The lists of clusters and shadows are saved in a file called .shadows,
;;  so that they can be remembered from one Emacs session to another, even
;;  (as much as possible) if the Emacs session terminates abnormally.  The
;;  files needing to be copied are stored in .shadow_todo; if a file cannot
;;  be copied for any reason, it will stay on the list to be tried again
;;  next time.  The .shadows file should itself have shadows on all your
;;  accounts so that the information in it is consistent everywhere, but
;;  .shadow_todo is local information and should have no shadows.

;;  If you do not want to copy a particular file, you can answer "no" and
;;  be asked again next time you hit C-x 4 s or exit Emacs.  If you do not
;;  want to be asked again, use shadow-cancel, and you will not be asked
;;  until you change the file and save it again.  If you do not want to
;;  shadow that file ever again, you can edit it out of the .shadows
;;  buffer.  Anytime you edit the .shadows buffer, you must type M-x
;;  shadow-read-files to load in the new information, or your changes will
;;  be overwritten!

;; Bugs & Warnings:
;;
;;  - It is bad to have two emacses both running shadowfile at the same
;;  time.  It tries to detect this condition, but is not always successful.
;;
;;  - You have to be careful not to edit a file in two locations
;;  before shadowfile has had a chance to copy it; otherwise
;;  "updating shadows" will overwrite one of the changed versions.
;;
;;  - It ought to check modification times of both files to make sure
;;  it is doing the right thing.  This will have to wait until
;;  file-newer-than-file-p works between machines.
;;
;;  - It will not make directories for you, it just fails to copy files
;;  that belong in non-existent directories.
;;
;;  Please report any bugs to me (boris@gnu.org).  Also let me know
;;  if you have suggestions or would like to be informed of updates.


;;; Code:

(require 'ange-ftp)

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Variables
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defgroup shadow nil
  "Automatic file copying when saving a file."
  :prefix "shadow-"
  :link '(emacs-commentary-link "shadowfile")
  :group 'files)

(defcustom shadow-noquery nil
  "If t, always copy shadow files without asking.
If nil (the default), always ask.  If not nil and not t, ask only if there
is no buffer currently visiting the file."
  :type '(choice (const t) (const nil) (other :tag "Ask if no buffer" maybe))
  :group 'shadow)

(defcustom shadow-inhibit-message nil
  "If non-nil, do not display a message when a file needs copying."
  :type 'boolean
  :group 'shadow)

(defcustom shadow-inhibit-overload nil
  "If non-nil, shadowfile won't redefine \\[save-buffers-kill-emacs].
Normally it overloads the function `save-buffers-kill-emacs' to check for
files that have been changed and need to be copied to other systems."
  :type 'boolean
  :group 'shadow)

(defcustom shadow-info-file nil
  "File to keep shadow information in.
The `shadow-info-file' should be shadowed to all your accounts to
ensure consistency.  Default: ~/.shadows"
  :type '(choice (const nil) file)
  :group 'shadow)

(defcustom shadow-todo-file nil
  "File to store the list of uncopied shadows in.
This means that if a remote system is down, or for any reason you cannot or
decide not to copy your shadow files at the end of one Emacs session, it will
remember and ask you again in your next Emacs session.
This file must NOT be shadowed to any other system, it is host-specific.
Default: ~/.shadow_todo"
  :type '(choice (const nil) file)
  :group 'shadow)


;;; The following two variables should in most cases initialize themselves
;;; correctly.  They are provided as variables in case the defaults are wrong
;;; on your machine (and for efficiency).

(defvar shadow-system-name (system-name)
  "The complete hostname of this machine.")

(defvar shadow-homedir nil
  "Your home directory on this machine.")

;;;
;;; Internal variables whose values are stored in the info and todo files:
;;;

(defvar shadow-clusters nil
  "List of host clusters (see `shadow-define-cluster').")

(defvar shadow-literal-groups nil
  "List of files that are shared between hosts.
This list contains shadow structures with literal filenames, created by
`shadow-define-literal-group'.")

(defvar shadow-regexp-groups nil
  "List of file types that are shared between hosts.
This list contains shadow structures with regexps matching filenames,
created by `shadow-define-regexp-group'.")

;;;
;;; Other internal variables:
;;;

(defvar shadow-files-to-copy nil)	; List of files that need to
					; be copied to remote hosts.

(defvar shadow-hashtable nil)		; for speed

(defvar shadow-info-buffer nil)		; buf visiting shadow-info-file
(defvar shadow-todo-buffer nil)		; buf visiting shadow-todo-file

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Syntactic sugar; General list and string manipulation
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defun shadow-union (a b)
  "Add members of list A to list B if not equal to items already in B."
  (if (null a)
      b
    (if (member (car a) b)
	(shadow-union (cdr a) b)
      (shadow-union (cdr a) (cons (car a) b)))))

(defun shadow-find (func list)
  "If FUNC applied to some element of LIST is non-nil, return first such element."
  (while (and list (not (funcall func (car list))))
    (setq list (cdr list)))
  (car list))

(defun shadow-remove-if (func list)
  "Remove elements satisfying FUNC from LIST.
Nondestructive; actually returns a copy of the list with the elements removed."
  (if list
      (if (funcall func (car list))
	  (shadow-remove-if func (cdr list))
	(cons (car list) (shadow-remove-if func (cdr list))))
    nil))

(defun shadow-regexp-superquote (string)
  "Like `regexp-quote', but includes the ^ and $.
This makes sure regexp matches nothing but STRING."
  (concat "^" (regexp-quote string) "$"))

(defun shadow-suffix (prefix string)
  "If PREFIX begins STRING, return the rest.
Return value is non-nil if PREFIX and STRING are `string=' up to the length of
PREFIX."
  (let ((lp (length prefix))
	(ls (length string)))
    (if (and (>= ls lp)
	     (string= prefix (substring string 0 lp)))
	(substring string lp))))

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Clusters and sites
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;;; I use the term `site' to refer to a string which may be the name of a
;;; cluster or a literal hostname.  All user-level commands should accept
;;; either.

(defun shadow-make-cluster (name primary regexp)
  "Create a shadow cluster.
It is called NAME, uses the PRIMARY hostname and REGEXP matching all
hosts in the cluster.  The variable `shadow-clusters' associates the
names of clusters to these structures.  This function is for program
use: to create clusters interactively, use `shadow-define-cluster'
instead."
  (list name primary regexp))

(defmacro shadow-cluster-name (cluster)
  "Return the name of the CLUSTER."
  (list 'elt cluster 0))

(defmacro shadow-cluster-primary (cluster)
  "Return the primary hostname of a CLUSTER."
  (list 'elt cluster 1))

(defmacro shadow-cluster-regexp (cluster)
  "Return the regexp matching hosts in a CLUSTER."
  (list 'elt cluster 2))

(defun shadow-set-cluster (name primary regexp)
  "Put cluster NAME on the list of clusters.
Replace old definition, if any.  PRIMARY and REGEXP are the
information defining the cluster.  For interactive use, call
`shadow-define-cluster' instead."
  (let ((rest (shadow-remove-if
	       (function (lambda (x) (equal name (car x))))
	       shadow-clusters)))
    (setq shadow-clusters
	  (cons (shadow-make-cluster name primary regexp)
		rest))))

(defmacro shadow-get-cluster (name)
  "Return cluster named NAME, or nil."
  (list 'assoc name 'shadow-clusters))

(defun shadow-site-primary (site)
  "If SITE is a cluster, return primary host, otherwise return SITE."
  (let ((c (shadow-get-cluster site)))
    (if c
	(shadow-cluster-primary c)
      site)))

;;; SITES

(defun shadow-site-cluster (site)
  "Given a SITE (hostname or cluster name), return cluster it is in, or nil."
  (or (assoc site shadow-clusters)
      (shadow-find
       (function (lambda (x)
		   (string-match (shadow-cluster-regexp x)
				 site)))
       shadow-clusters)))

(defun shadow-read-site ()
  "Read a cluster name or hostname from the minibuffer."
  (let ((ans (completing-read "Host or cluster name [RET when done]: "
			      shadow-clusters)))
    (if (equal "" ans)
	nil
      ans)))

(defun shadow-site-match (site1 site2)
  "Non-nil if SITE1 is or includes SITE2.
Each may be a host or cluster name; if they are clusters, regexp of SITE1 will
be matched against the primary of SITE2."
  (or (string-equal site1 site2) ; quick check
      (let* ((cluster1 (shadow-get-cluster site1))
	     (primary2 (shadow-site-primary site2)))
	(if cluster1
	    (string-match (shadow-cluster-regexp cluster1) primary2)
	  (string-equal site1 primary2)))))

(defun shadow-get-user (site)
  "Return the default username for a SITE."
  (ange-ftp-get-user (shadow-site-primary site)))

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Filename manipulation
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defun shadow-parse-fullname (fullname)
  "Parse FULLNAME into (site user path) list.
Leave it alone if it already is one.  Return nil if the argument is
not a full ange-ftp pathname."
  (if (listp fullname)
      fullname
    (ange-ftp-ftp-name fullname)))

(defun shadow-parse-name (name)
  "Parse any NAME into (site user name) list.
Argument can be a simple name, full ange-ftp name, or already a hup list."
  (or (shadow-parse-fullname name)
      (list shadow-system-name
	    (user-login-name)
	    name)))

(defsubst shadow-make-fullname (host user name)
  "Make an ange-ftp style fullname out of HOST, USER (optional), and NAME.
This is probably not as general as it ought to be."
  (concat "/"
	  (if user (concat user "@"))
	  host ":"
	  name))

(defun shadow-replace-name-component (fullname newname)
  "Return FULLNAME with the name component changed to NEWNAME."
  (let ((hup (shadow-parse-fullname fullname)))
    (shadow-make-fullname (nth 0 hup) (nth 1 hup) newname)))

(defun shadow-local-file (file)
  "If FILE is at this site, remove /user@host part.
If refers to a different system or a different user on this system,
return nil."
  (let ((hup (shadow-parse-fullname file)))
    (cond ((null hup) file)
	  ((and (shadow-site-match (nth 0 hup) shadow-system-name)
		(string-equal (nth 1 hup) (user-login-name)))
	   (nth 2 hup))
	  (t nil))))

(defun shadow-expand-cluster-in-file-name (file)
  "If hostname part of FILE is a cluster, expand it to cluster's primary hostname.
Will return the name bare if it is a local file."
  (let ((hup (shadow-parse-name file)))
    (cond ((null hup) file)
	  ((shadow-local-file hup))
	  ((shadow-make-fullname (shadow-site-primary (nth 0 hup))
				 (nth 1 hup)
				 (nth 2 hup))))))

(defun shadow-expand-file-name (file &optional default)
  "Expand file name and get FILE's true name."
  (file-truename (expand-file-name file default)))

(defun shadow-contract-file-name (file)
  "Simplify FILE.
Do so by replacing (when possible) home directory with ~, and hostname
with cluster name that includes it.  Filename should be absolute and
true."
  (let* ((hup (shadow-parse-name file))
	 (homedir (if (shadow-local-file hup)
		      shadow-homedir
		    (file-name-as-directory
		     (nth 2 (shadow-parse-fullname
			     (expand-file-name
			      (shadow-make-fullname
			       (nth 0 hup) (nth 1 hup) "~")))))))
	 (suffix (shadow-suffix homedir (nth 2 hup)))
	 (cluster (shadow-site-cluster (nth 0 hup))))
    (shadow-make-fullname
     (if cluster
	 (shadow-cluster-name cluster)
       (nth 0 hup))
     (nth 1 hup)
     (if suffix
	 (concat "~/" suffix)
       (nth 2 hup)))))

(defun shadow-same-site (pattern file)
  "True if the site of PATTERN and of FILE are on the same site.
If usernames are supplied, they must also match exactly.  PATTERN and FILE may
be lists of host, user, name, or ange-ftp file names.  FILE may also be just a
local filename."
  (let ((pattern-sup (shadow-parse-fullname pattern))
	(file-sup    (shadow-parse-name file)))
    (and
     (shadow-site-match (nth 0 pattern-sup) (nth 0 file-sup))
     (or (null (nth 1 pattern-sup))
	 (string-equal (nth 1 pattern-sup) (nth 1 file-sup))))))

(defun shadow-file-match (pattern file &optional regexp)
 "Return t if PATTERN matches FILE.
If REGEXP is supplied and non-nil, the file part of the pattern is a regular
expression, otherwise it must match exactly.  The sites and usernames must
match---see `shadow-same-site'.  The pattern must be in full ange-ftp format,
but the file can be any valid filename.  This function does not do any
filename expansion or contraction, you must do that yourself first."
 (let* ((pattern-sup (shadow-parse-fullname pattern))
	(file-sup (shadow-parse-name file)))
   (and (shadow-same-site pattern-sup file-sup)
	(if regexp
	    (string-match (nth 2 pattern-sup) (nth 2 file-sup))
	  (string-equal (nth 2 pattern-sup) (nth 2 file-sup))))))

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; User-level Commands
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;;;###autoload
(defun shadow-define-cluster (name)
  "Edit (or create) the definition of a cluster NAME.
This is a group of hosts that share directories, so that copying to or from
one of them is sufficient to update the file on all of them.  Clusters are
defined by a name, the network address of a primary host (the one we copy
files to), and a regular expression that matches the hostnames of all the
sites in the cluster."
  (interactive (list (completing-read "Cluster name: " shadow-clusters () ())))
  (let* ((old (shadow-get-cluster name))
	 (primary (read-string "Primary host: "
			       (if old (shadow-cluster-primary old)
				 name)))
	 (regexp   (let (try-regexp)
		     (while (not
			     (string-match
			      (setq try-regexp
				    (read-string
				     "Regexp matching all host names: "
				     (if old (shadow-cluster-regexp old)
				       (shadow-regexp-superquote primary))))
			      primary))
		       (message "Regexp doesn't include the primary host!")
		       (sit-for 2))
		     try-regexp))
;	 (username (read-no-blanks-input
;		    (format "Username (default %s): "
;			    (shadow-get-user primary))
;		    (if old (or (shadow-cluster-username old) "")
;		      (user-login-name))))
	 )
;    (if (string-equal "" username) (setq username nil))
    (shadow-set-cluster name primary regexp)))

;;;###autoload
(defun shadow-define-literal-group ()
  "Declare a single file to be shared between sites.
It may have different filenames on each site.  When this file is edited, the
new version will be copied to each of the other locations.  Sites can be
specific hostnames, or names of clusters (see `shadow-define-cluster')."
  (interactive)
  (let* ((hup (shadow-parse-fullname
	       (shadow-contract-file-name (buffer-file-name))))
	 (name (nth 2 hup))
	 user site group)
    (while (setq site (shadow-read-site))
      (setq user (read-string (format "Username (default %s): "
				      (shadow-get-user site)))
	    name (read-string "Filename: " name))
      (setq group (cons (shadow-make-fullname site
					      (if (string-equal "" user)
						  (shadow-get-user site)
						user)
					      name)
			group)))
    (setq shadow-literal-groups (cons group shadow-literal-groups)))
  (shadow-write-info-file))

;;;###autoload
(defun shadow-define-regexp-group ()
  "Make each of a group of files be shared between hosts.
Prompts for regular expression; files matching this are shared between a list
of sites, which are also prompted for.  The filenames must be identical on all
hosts (if they aren't, use `shadow-define-literal-group' instead of this
function).  Each site can be either a hostname or the name of a cluster (see
`shadow-define-cluster')."
  (interactive)
  (let ((regexp (read-string
		 "Filename regexp: "
		 (if (buffer-file-name)
		     (shadow-regexp-superquote
		      (nth 2
			   (shadow-parse-name
			    (shadow-contract-file-name
			     (buffer-file-name))))))))
	site sites usernames)
    (while (setq site (shadow-read-site))
      (setq sites (cons site sites))
      (setq usernames
	    (cons (read-string (format "Username for %s: " site)
			       (shadow-get-user site))
		  usernames)))
    (setq shadow-regexp-groups
	  (cons (shadow-make-group regexp sites usernames)
		shadow-regexp-groups))
    (shadow-write-info-file)))

(defun shadow-shadows ()
  ;; Mostly for debugging.
  "Interactive function to display shadows of a buffer."
  (interactive)
  (let ((msg (mapconcat #'cdr (shadow-shadows-of (buffer-file-name)) " ")))
    (message "%s"
	     (if (zerop (length msg))
		 "No shadows."
	       msg))))

(defun shadow-copy-files (&optional arg)
  "Copy all pending shadow files.
With prefix argument, copy all pending files without query.
Pending copies are stored in variable `shadow-files-to-copy', and in
`shadow-todo-file' if necessary.  This function is invoked by
`shadow-save-buffers-kill-emacs', so it is not usually necessary to
call it manually."
  (interactive "P")
  (if (not shadow-files-to-copy)
      (if (called-interactively-p 'interactive)
	  (message "No files need to be shadowed."))
    (save-excursion
      (map-y-or-n-p (function
		     (lambda (pair)
		       (or arg shadow-noquery
			   (format "Copy shadow file %s? " (cdr pair)))))
		    (function shadow-copy-file)
		    shadow-files-to-copy
		    '("shadow" "shadows" "copy"))
      (shadow-write-todo-file t))))

(defun shadow-cancel ()
  "Cancel the instruction to copy some files.
Prompts for which copy operations to cancel.  You will not be asked to copy
them again, unless you make more changes to the files.  To cancel a shadow
permanently, remove the group from `shadow-literal-groups' or
`shadow-regexp-groups'."
  (interactive)
  (map-y-or-n-p (function (lambda (pair)
			    (format "Cancel copying %s to %s? "
				    (car pair) (cdr pair))))
		(function (lambda (pair)
			    (shadow-remove-from-todo pair)))
		shadow-files-to-copy
		'("shadow" "shadows" "cancel copy"))
  (message "There are %d shadows to be updated."
	   (length shadow-files-to-copy))
  (shadow-write-todo-file))

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Internal functions
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defun shadow-make-group (regexp sites usernames)
  "Make a description of a file group---
actually a list of regexp ange-ftp file names---from REGEXP (name of file to
be shadowed), list of SITES, and corresponding list of USERNAMES for each
site."
  (if sites
      (cons (shadow-make-fullname (car sites) (car usernames) regexp)
	    (shadow-make-group regexp (cdr sites) (cdr usernames)))
    nil))

(defun shadow-copy-file (s)
  "Copy one shadow file."
  (let* ((buffer
	  (cond ((get-file-buffer
		  (abbreviate-file-name (shadow-expand-file-name (car s)))))
		((not (file-readable-p (car s)))
		 (if (y-or-n-p
		      (format "Cannot find file %s--cancel copy request? "
			      (car s)))
		     (shadow-remove-from-todo s))
		 nil)
		((or (eq t shadow-noquery)
		     (y-or-n-p
		      (format "No buffer for %s -- update shadow anyway? "
			      (car s))))
		 (find-file-noselect (car s)))))
	 (to (shadow-expand-cluster-in-file-name (cdr s))))
    (when buffer
      (set-buffer buffer)
      (condition-case nil
	  (progn
            (write-region nil nil to)
            (shadow-remove-from-todo s))
        (error (message "Shadow %s not updated!" (cdr s)))))))

(defun shadow-shadows-of (file)
  "Return copy operations needed to update FILE.
Filename should have clusters expanded, but otherwise can have any format.
Return value is a list of dotted pairs like (from . to), where from
and to are absolute file names."
  (or (symbol-value (intern-soft file shadow-hashtable))
      (let* ((absolute-file (shadow-expand-file-name
			     (or (shadow-local-file file) file)
			     shadow-homedir))
	     (canonical-file (shadow-contract-file-name absolute-file))
	     (shadows
	      (mapcar (function (lambda (shadow)
				  (cons absolute-file shadow)))
		      (append
		       (shadow-shadows-of-1
			canonical-file shadow-literal-groups nil)
		       (shadow-shadows-of-1
			canonical-file shadow-regexp-groups t)))))
	(set (intern file shadow-hashtable) shadows))))

(defun shadow-shadows-of-1 (file groups regexp)
  "Return list of FILE's shadows in GROUPS.
Consider them as regular expressions if third arg REGEXP is true."
  (if groups
      (let ((nonmatching
	     (shadow-remove-if
	      (function (lambda (x) (shadow-file-match x file regexp)))
	      (car groups))))
	(append (cond ((equal nonmatching (car groups)) nil)
		      (regexp
		       (let ((realname (nth 2 (shadow-parse-fullname file))))
			 (mapcar
			  (function
			   (lambda (x)
			     (shadow-replace-name-component x realname)))
			  nonmatching)))
		      (t nonmatching))
		(shadow-shadows-of-1 file (cdr groups) regexp)))))

(defun shadow-add-to-todo ()
  "If current buffer has shadows, add them to the list needing to be copied."
  (let ((shadows (shadow-shadows-of
		  (shadow-expand-file-name
		   (buffer-file-name (current-buffer))))))
    (when shadows
      (setq shadow-files-to-copy
	    (shadow-union shadows shadow-files-to-copy))
      (when (not shadow-inhibit-message)
	(message "%s" (substitute-command-keys
		       "Use \\[shadow-copy-files] to update shadows."))
	(sit-for 1))
      (shadow-write-todo-file)))
  nil)     ; Return nil for write-file-functions

(defun shadow-remove-from-todo (pair)
  "Remove PAIR from `shadow-files-to-copy'.
PAIR must be `eq' to one of the elements of that list."
  (setq shadow-files-to-copy
	(shadow-remove-if (function (lambda (s) (eq s pair)))
			  shadow-files-to-copy)))

(defun shadow-read-files ()
  "Visit and load `shadow-info-file' and `shadow-todo-file'.
Thus restores shadowfile's state from your last Emacs session.
Return t unless files were locked; then return nil."
  (interactive)
  (if (and (fboundp 'file-locked-p)
	   (or (stringp (file-locked-p shadow-info-file))
	       (stringp (file-locked-p shadow-todo-file))))
      (progn
	(message "Shadowfile is running in another Emacs; can't have two.")
	(beep)
	(sit-for 3)
	nil)
    (save-excursion
      (when shadow-info-file
	(set-buffer (setq shadow-info-buffer
			  (find-file-noselect shadow-info-file)))
	(when (and (not (buffer-modified-p))
		   (file-newer-than-file-p (make-auto-save-file-name)
					   shadow-info-file))
	  (erase-buffer)
	  (message "Data recovered from %s."
		   (car (insert-file-contents (make-auto-save-file-name))))
	  (sit-for 1))
	(eval-buffer))
      (when shadow-todo-file
	(set-buffer (setq shadow-todo-buffer
			  (find-file-noselect shadow-todo-file)))
	(when (and (not (buffer-modified-p))
		   (file-newer-than-file-p (make-auto-save-file-name)
					   shadow-todo-file))
	  (erase-buffer)
	  (message "Data recovered from %s."
		   (car (insert-file-contents (make-auto-save-file-name))))
	  (sit-for 1))
	(eval-buffer nil))
      (shadow-invalidate-hashtable))
    t))

(defun shadow-write-info-file ()
  "Write out information to `shadow-info-file'.
Also clear `shadow-hashtable', since when there are new shadows
defined, the old hashtable info is invalid."
  (shadow-invalidate-hashtable)
  (if shadow-info-file
      (save-excursion
	(if (not shadow-info-buffer)
	    (setq shadow-info-buffer (find-file-noselect shadow-info-file)))
	(set-buffer shadow-info-buffer)
	(delete-region (point-min) (point-max))
	(shadow-insert-var 'shadow-clusters)
	(shadow-insert-var 'shadow-literal-groups)
	(shadow-insert-var 'shadow-regexp-groups))))

(defun shadow-write-todo-file (&optional save)
  "Write out information to `shadow-todo-file'.
With non-nil argument also saves the buffer."
  (save-excursion
    (if (not shadow-todo-buffer)
	(setq shadow-todo-buffer (find-file-noselect shadow-todo-file)))
    (set-buffer shadow-todo-buffer)
    (delete-region (point-min) (point-max))
    (shadow-insert-var 'shadow-files-to-copy)
    (if save (shadow-save-todo-file))))

(defun shadow-save-todo-file ()
  (if (and shadow-todo-buffer (buffer-modified-p shadow-todo-buffer))
      (with-current-buffer shadow-todo-buffer
	(condition-case nil		; have to continue even in case of
	    (basic-save-buffer)		; error, otherwise kill-emacs might
	  (error			; not work!
	   (message "WARNING: Can't save shadow todo file; it is locked!")
	   (sit-for 1))))))

(defun shadow-invalidate-hashtable ()
  (setq shadow-hashtable (make-vector 37 0)))

(defun shadow-insert-var (variable)
  "Build a `setq' to restore VARIABLE.
Prettily insert a `setq' command which, when later evaluated,
will restore VARIABLE to its current setting.
VARIABLE must be the name of a variable whose value is a list."
  (let ((standard-output (current-buffer)))
    (insert (format "(setq %s" variable))
    (cond ((consp (eval variable))
	   (insert "\n  '(")
	   (prin1 (car (eval variable)))
	   (let ((rest (cdr (eval variable))))
	     (while rest
	       (insert "\n    ")
	       (prin1 (car rest))
	       (setq rest (cdr rest)))
	     (insert "))\n\n")))
	  (t (insert " ")
	     (prin1 (eval variable))
	     (insert ")\n\n")))))

(defun shadow-save-buffers-kill-emacs (&optional arg)
  "Offer to save each buffer and copy shadows, then kill this Emacs process.
With prefix arg, silently save all file-visiting buffers, then kill.

Extended by shadowfile to automatically save `shadow-todo-file' and
look for files that have been changed and need to be copied to other systems."
  ;; This function is necessary because we need to get control and save
  ;; the todo file /after/ saving other files, but /before/ the warning
  ;; message about unsaved buffers (because it can get modified by the
  ;; action of saving other buffers).  `kill-emacs-hook' is no good
  ;; because it is not called at the correct time, and also because it is
  ;; called when the terminal is disconnected and we cannot ask whether
  ;; to copy files.
  (interactive "P")
  (shadow-save-todo-file)
  (save-some-buffers arg t)
  (shadow-copy-files)
  (shadow-save-todo-file)
  (and (or (not (memq t (mapcar (function
				 (lambda (buf) (and (buffer-file-name buf)
						    (buffer-modified-p buf))))
				(buffer-list))))
	   (yes-or-no-p "Modified buffers exist; exit anyway? "))
       (or (not (fboundp 'process-list))
	   ;; process-list is not defined on MSDOS.
	   (let ((processes (process-list))
		 active)
	     (while processes
	       (and (memq (process-status (car processes)) '(run stop open listen))
		    (process-query-on-exit-flag (car processes))
		    (setq active t))
	       (setq processes (cdr processes)))
	     (or (not active)
		 (yes-or-no-p "Active processes exist; kill them and exit anyway? "))))
       (kill-emacs)))

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Lucid Emacs compatibility
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; This is on hold until someone tells me about a working version of
;; map-ynp for Lucid Emacs.

;(when (string-match "Lucid" emacs-version)
;  (require 'symlink-fix)
;  (require 'ange-ftp)
;  (require 'map-ynp)
;  (if (not (fboundp 'file-truename))
;      (fset 'shadow-expand-file-name
;	    (symbol-function 'symlink-expand-file-name)))
;  (if (not (fboundp 'ange-ftp-ftp-name))
;      (fset 'ange-ftp-ftp-name
;	    (symbol-function 'ange-ftp-ftp-name))))

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Hook us up
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;;;###autoload
(defun shadow-initialize ()
  "Set up file shadowing."
  (interactive)
  (if (null shadow-homedir)
      (setq shadow-homedir
	    (file-name-as-directory (shadow-expand-file-name "~"))))
  (if (null shadow-info-file)
      (setq shadow-info-file
	    (shadow-expand-file-name (convert-standard-filename "~/.shadows"))))
  (if (null shadow-todo-file)
      (setq shadow-todo-file
	    (shadow-expand-file-name
	     (convert-standard-filename "~/.shadow_todo"))))
  (if (not (shadow-read-files))
      (progn
	(message "Shadowfile information files not found - aborting")
	(beep)
	(sit-for 3))
    (when (and (not shadow-inhibit-overload)
	       (not (fboundp 'shadow-orig-save-buffers-kill-emacs)))
      (defalias 'shadow-orig-save-buffers-kill-emacs
	(symbol-function 'save-buffers-kill-emacs))
      (defalias 'save-buffers-kill-emacs 'shadow-save-buffers-kill-emacs))
    (add-hook 'write-file-functions 'shadow-add-to-todo)
    (define-key ctl-x-4-map "s" 'shadow-copy-files)))

(defun shadowfile-unload-function ()
  (substitute-key-definition 'shadow-copy-files nil ctl-x-4-map)
  (when (fboundp 'shadow-orig-save-buffers-kill-emacs)
    (fset 'save-buffers-kill-emacs
	  (symbol-function 'shadow-orig-save-buffers-kill-emacs)))
  ;; continue standard unloading
  nil)

(provide 'shadowfile)

;;; shadowfile.el ends here