summaryrefslogtreecommitdiff
path: root/lisp/jka-compr.el
blob: ef1a25f591a29645ab09ad78d194fb4ba08ac7c1 (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
834
835
836
837
838
839
840
841
842
;;; jka-compr.el --- reading/writing/loading compressed files

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

;; Author: jka@ece.cmu.edu (Jay K. Adams)
;; Keywords: data

;; 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 2, 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; see the file COPYING.  If not, write to the
;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.

;;; Commentary: 

;; This package implements low-level support for reading, writing,
;; and loading compressed files.  It hooks into the low-level file
;; I/O functions (including write-region and insert-file-contents) so
;; that they automatically compress or uncompress a file if the file
;; appears to need it (based on the extension of the file name).
;; Packages like Rmail, VM, GNUS, and Info should be able to work
;; with compressed files without modification.


;; INSTRUCTIONS:
;;
;; To use jka-compr, simply load this package, and edit as usual.
;; Its operation should be transparent to the user (except for
;; messages appearing when a file is being compressed or
;; uncompressed).
;;
;; The variable, jka-compr-compression-info-list can be used to
;; customize jka-compr to work with other compression programs.
;; The default value of this variable allows jka-compr to work with
;; Unix compress and gzip.
;;
;; If you are concerned about the stderr output of gzip and other
;; compression/decompression programs showing up in your buffers, you
;; should set the discard-error flag in the compression-info-list.
;; This will cause the stderr of all programs to be discarded.
;; However, it also causes emacs to call compression/uncompression
;; programs through a shell (which is specified by jka-compr-shell).
;; This may be a drag if, on your system, starting up a shell is
;; slow.
;;
;; If you don't want messages about compressing and decompressing
;; to show up in the echo area, you can set the compress-name and
;; decompress-name fields of the jka-compr-compression-info-list to
;; nil.


;; APPLICATION NOTES:
;;
;; crypt++
;;   jka-compr can coexist with crpyt++ if you take all the decompression
;;   entries out of the crypt-encoding-list.  Clearly problems will arise if
;;   you have two programs trying to compress/decompress files.  jka-compr
;;   will not "work with" crypt++ in the following sense: you won't be able to
;;   decode encrypted compressed files--that is, files that have been
;;   compressed then encrypted (in that order).  Theoretically, crypt++ and
;;   jka-compr could properly handle a file that has been encrypted then
;;   compressed, but there is little point in trying to compress an encrypted
;;   file.
;;


;; ACKNOWLEDGMENTS
;; 
;; jka-compr is a V19 adaptation of jka-compr for V18 of Emacs.  Many people
;; have made helpful suggestions, reported bugs, and even fixed bugs in 
;; jka-compr.  I recall the following people as being particularly helpful.
;;
;;   Jean-loup Gailly
;;   David Hughes
;;   Richard Pieri
;;   Daniel Quinlan
;;   Chris P. Ross
;;   Rick Sladkey
;;
;; Andy Norman's ange-ftp was the inspiration for the original jka-compr for
;; Version 18 of Emacs.
;;
;; After I had made progress on the original jka-compr for V18, I learned of a
;; package written by Kazushi Jam Marukawa, called jam-zcat, that did exactly
;; what I was trying to do.  I looked over the jam-zcat source code and
;; probably got some ideas from it.
;;

;;; Code:

(defvar jka-compr-shell "sh"
  "*Shell to be used for calling compression programs.
The value of this variable only matters if you want to discard the
stderr of a compression/decompression program (see the documentation
for `jka-compr-compression-info-list').")


(defvar jka-compr-use-shell t)


;;; I have this defined so that .Z files are assumed to be in unix
;;; compress format; and .gz files, in gzip format.
(defvar jka-compr-compression-info-list
  ;;[regexp
  ;; compr-message  compr-prog  compr-args
  ;; uncomp-message uncomp-prog uncomp-args
  ;; can-append auto-mode-flag]
  '(["\\.Z\\(~\\|\\.~[0-9]+~\\)?\\'"
     "compressing"    "compress"     ("-c")
     "uncompressing"  "uncompress"   ("-c")
     nil t]
    ["\\.tgz\\'"
     "zipping"        "gzip"         ("-c" "-q")
     "unzipping"      "gzip"         ("-c" "-q" "-d")
     t nil]
    ["\\.gz\\(~\\|\\.~[0-9]+~\\)?\\'"
     "zipping"        "gzip"         ("-c" "-q")
     "unzipping"      "gzip"         ("-c" "-q" "-d")
     t t])

  "List of vectors that describe available compression techniques.
Each element, which describes a compression technique, is a vector of
the form [REGEXP COMPRESS-MSG COMPRESS-PROGRAM COMPRESS-ARGS
UNCOMPRESS-MSG UNCOMPRESS-PROGRAM UNCOMPRESS-ARGS
APPEND-FLAG EXTENSION], where:

   regexp                is a regexp that matches filenames that are
                         compressed with this format

   compress-msg          is the message to issue to the user when doing this
                         type of compression (nil means no message)

   compress-program      is a program that performs this compression

   compress-args         is a list of args to pass to the compress program

   uncompress-msg        is the message to issue to the user when doing this
                         type of uncompression (nil means no message)

   uncompress-program    is a program that performs this compression

   uncompress-args       is a list of args to pass to the uncompress program

   append-flag           is non-nil if this compression technique can be
                         appended

   auto-mode flag        non-nil means strip the regexp from file names
                         before attempting to set the mode.

Because of the way `call-process' is defined, discarding the stderr output of
a program adds the overhead of starting a shell each time the program is
invoked.")

(defvar jka-compr-mode-alist-additions
  (list (cons "\\.tgz\\'" 'tar-mode))
  "A list of pairs to add to auto-mode-alist when jka-compr is installed.")

(defvar jka-compr-file-name-handler-entry
  nil
  "The entry in `file-name-handler-alist' used by the jka-compr I/O functions.")

;;; Functions for accessing the return value of jka-compr-get-compression-info
(defun jka-compr-info-regexp               (info)  (aref info 0))
(defun jka-compr-info-compress-message     (info)  (aref info 1))
(defun jka-compr-info-compress-program     (info)  (aref info 2))
(defun jka-compr-info-compress-args        (info)  (aref info 3))
(defun jka-compr-info-uncompress-message   (info)  (aref info 4))
(defun jka-compr-info-uncompress-program   (info)  (aref info 5))
(defun jka-compr-info-uncompress-args      (info)  (aref info 6))
(defun jka-compr-info-can-append           (info)  (aref info 7))
(defun jka-compr-info-strip-extension      (info)  (aref info 8))


(defun jka-compr-get-compression-info (filename)
  "Return information about the compression scheme of FILENAME.
The determination as to which compression scheme, if any, to use is
based on the filename itself and `jka-compr-compression-info-list'."
  (catch 'compression-info
    (let ((case-fold-search nil))
      (mapcar
       (function (lambda (x)
		   (and (string-match (jka-compr-info-regexp x) filename)
			(throw 'compression-info x))))
       jka-compr-compression-info-list)
      nil)))


(put 'compression-error 'error-conditions '(compression-error file-error error))


(defvar jka-compr-acceptable-retval-list '(0 2 141))


(defun jka-compr-error (prog args infile message &optional errfile)

  (let ((errbuf (get-buffer-create " *jka-compr-error*"))
	(curbuf (current-buffer)))
    (set-buffer errbuf)
    (widen) (erase-buffer)
    (insert (format "Error while executing \"%s %s < %s\"\n\n"
		     prog
		     (mapconcat 'identity args " ")
		     infile))

     (and errfile
	  (insert-file-contents errfile))

     (set-buffer curbuf)
     (display-buffer errbuf))

  (signal 'compression-error (list "Opening input file" (format "error %s" message) infile)))
			
   
(defvar jka-compr-dd-program
  "/bin/dd")


(defvar jka-compr-dd-blocksize 256)


(defun jka-compr-partial-uncompress (prog message args infile beg len)
  "Call program PROG with ARGS args taking input from INFILE.
Fourth and fifth args, BEG and LEN, specify which part of the output
to keep: LEN chars starting BEG chars from the beginning."
  (let* ((skip (/ beg jka-compr-dd-blocksize))
	 (prefix (- beg (* skip jka-compr-dd-blocksize)))
	 (count (and len (1+ (/ (+ len prefix) jka-compr-dd-blocksize))))
	 (start (point))
	 (err-file (jka-compr-make-temp-name))
	 (run-string (format "%s %s 2> %s | %s bs=%d skip=%d %s 2> /dev/null"
			     prog
			     (mapconcat 'identity args " ")
			     err-file
			     jka-compr-dd-program
			     jka-compr-dd-blocksize
			     skip
			     ;; dd seems to be unreliable about
			     ;; providing the last block.  So, always
			     ;; read one more than you think you need.
			     (if count (concat "count=" (1+ count)) ""))))

    (unwind-protect
	(or (memq (call-process jka-compr-shell
				infile t nil "-c"
				run-string)
		  jka-compr-acceptable-retval-list)
	    
	    (jka-compr-error prog args infile message err-file))

      (jka-compr-delete-temp-file err-file))

    ;; Delete the stuff after what we want, if there is any.
    (and
     len
     (< (+ start prefix len) (point))
     (delete-region (+ start prefix len) (point)))

    ;; Delete the stuff before what we want.
    (delete-region start (+ start prefix))))


(defun jka-compr-call-process (prog message infile output temp args)
  (if jka-compr-use-shell

      (let ((err-file (jka-compr-make-temp-name)))
	    
	(unwind-protect

	    (or (memq
		 (call-process jka-compr-shell infile
			       (if (stringp output) nil output)
			       nil
			       "-c"
			       (format "%s %s 2> %s %s"
				       prog
				       (mapconcat 'identity args " ")
				       err-file
				       (if (stringp output)
					   (concat "> " output)
					 "")))
		 jka-compr-acceptable-retval-list)

		(jka-compr-error prog args infile message err-file))

	  (jka-compr-delete-temp-file err-file)))

    (or (zerop
	 (apply 'call-process
		prog
		infile
		(if (stringp output) temp output)
		nil
		args))
	(jka-compr-error prog args infile message))

    (and (stringp output)
	 (let ((cbuf (current-buffer)))
	   (set-buffer temp)
	   (write-region (point-min) (point-max) output)
	   (erase-buffer)
	   (set-buffer cbuf)))))


;;; Support for temp files.  Much of this was inspired if not lifted
;;; from ange-ftp.

(defvar jka-compr-temp-name-template
  (expand-file-name "jka-com"
		    (or (getenv "TMPDIR") "/tmp/"))
  "Prefix added to all temp files created by jka-compr.
There should be no more than seven characters after the final `/'")

(defvar jka-compr-temp-name-table (make-vector 31 nil))

(defun jka-compr-make-temp-name (&optional local-copy)
  "This routine will return the name of a new file."
  (let* ((lastchar ?a)
	 (prevchar ?a)
	 (template (concat jka-compr-temp-name-template "aa"))
	 (lastpos (1- (length template)))
	 (not-done t)
	 file
	 entry)

    (while not-done
      (aset template lastpos lastchar)
      (setq file (concat (make-temp-name template) "#"))
      (setq entry (intern file jka-compr-temp-name-table))
      (if (or (get entry 'active)
	      (file-exists-p file))

	  (progn
	    (setq lastchar (1+ lastchar))
	    (if (> lastchar ?z)
		(progn
		  (setq prevchar (1+ prevchar))
		  (setq lastchar ?a)
		  (if (> prevchar ?z)
		      (error "Can't allocate temp file.")
		    (aset template (1- lastpos) prevchar)))))

	(put entry 'active (not local-copy))
	(setq not-done nil)))

    file))


(defun jka-compr-delete-temp-file (temp)

  (put (intern temp jka-compr-temp-name-table)
       'active nil)

  (condition-case ()
      (delete-file temp)
    (error nil)))


(defun jka-compr-write-region (start end file &optional append visit)
  (let* ((filename (expand-file-name file))
	 (visit-file (if (stringp visit) (expand-file-name visit) filename))
	 (info (jka-compr-get-compression-info visit-file)))
      
      (if info

	  (let ((can-append (jka-compr-info-can-append info))
		(compress-program (jka-compr-info-compress-program info))
		(compress-message (jka-compr-info-compress-message info))
		(uncompress-program (jka-compr-info-uncompress-program info))
		(uncompress-message (jka-compr-info-uncompress-message info))
		(compress-args (jka-compr-info-compress-args info))
		(uncompress-args (jka-compr-info-uncompress-args info))
		(base-name (file-name-nondirectory visit-file))
		temp-file cbuf temp-buffer)

	    (setq cbuf (current-buffer)
		  temp-buffer (get-buffer-create " *jka-compr-wr-temp*"))
	    (set-buffer temp-buffer)
	    (widen) (erase-buffer)
	    (set-buffer cbuf)

	    (if (and append
		     (not can-append)
		     (file-exists-p filename))
		
		(let* ((local-copy (file-local-copy filename))
		       (local-file (or local-copy filename)))
		  
		  (setq temp-file local-file))

	      (setq temp-file (jka-compr-make-temp-name)))

	    (and 
	     compress-message
	     (message "%s %s..." compress-message base-name))
	    
	    (jka-compr-run-real-handler 'write-region
					(list start end temp-file t 'dont))

	    (jka-compr-call-process compress-program
				    (concat compress-message
					    " " base-name)
				    temp-file
				    temp-buffer
				    nil
				    compress-args)

	    (set-buffer temp-buffer)
	    (jka-compr-run-real-handler 'write-region
					(list (point-min) (point-max)
					      filename
					      (and append can-append) 'dont))
	    (erase-buffer)
	    (set-buffer cbuf)

	    (jka-compr-delete-temp-file temp-file)

	    (and
	     compress-message
	     (message "%s %s...done" compress-message base-name))

	    (cond
	     ((eq visit t)
	      (setq buffer-file-name filename)
	      (set-visited-file-modtime))
	     ((stringp visit)
	      (setq buffer-file-name visit)
	      (let ((buffer-file-name filename))
		(set-visited-file-modtime))))

	    (and (or (eq visit t)
		     (eq visit nil)
		     (stringp visit))
		 (message "Wrote %s" visit-file))

	    nil)
	      
	(jka-compr-run-real-handler 'write-region
				    (list start end filename append visit)))))


(defun jka-compr-insert-file-contents (file &optional visit beg end replace)
  (barf-if-buffer-read-only)

  (and (or beg end)
       visit
       (error "Attempt to visit less than an entire file"))

  (let* ((filename (expand-file-name file))
	 (info (jka-compr-get-compression-info filename)))

    (if info

	(let ((uncompress-message (jka-compr-info-uncompress-message info))
	      (uncompress-program (jka-compr-info-uncompress-program info))
	      (uncompress-args (jka-compr-info-uncompress-args info))
	      (base-name (file-name-nondirectory filename))
	      (notfound nil)
	      (local-copy
	       (jka-compr-run-real-handler 'file-local-copy (list filename)))
	      local-file
	      size start)

	  (setq local-file (or local-copy filename))

	  (and
	   visit
	   (setq buffer-file-name filename))

	  (unwind-protect		; to make sure local-copy gets deleted

	      (progn
		  
		(and
		 uncompress-message
		 (message "%s %s..." uncompress-message base-name))

		(condition-case error-code

		    (progn
		      (if replace
			  (goto-char (point-min)))
		      (setq start (point))
		      (if (or beg end)
			  (jka-compr-partial-uncompress uncompress-program
							(concat uncompress-message
								" " base-name)
							uncompress-args
							local-file
							(or beg 0)
							(if (and beg end)
							    (- end beg)
							  end))
			;; If visiting, bind off buffer-file-name so that
			;; file-locking will not ask whether we should
			;; really edit the buffer.
			(let ((buffer-file-name
			       (if visit nil buffer-file-name)))
			  (jka-compr-call-process uncompress-program
						  (concat uncompress-message
							  " " base-name)
						  local-file
						  t
						  nil
						  uncompress-args)))
		      (setq size (- (point) start))
		      (if replace
			  (let* ((del-beg (point))
				 (del-end (+ del-beg size)))
			    (delete-region del-beg
					   (min del-end (point-max)))))
		      (goto-char start))
		  (error
		   (if (and (eq (car error-code) 'file-error)
			    (eq (nth 3 error-code) local-file))
		       (if visit
			   (setq notfound error-code)
			 (signal 'file-error 
				 (cons "Opening input file"
				       (nthcdr 2 error-code))))
		     (signal (car error-code) (cdr error-code))))))

	    (and
	     local-copy
	     (file-exists-p local-copy)
	     (delete-file local-copy)))

	  (and
	   visit
	   (progn
	     (unlock-buffer)
	     (setq buffer-file-name filename)
	     (set-visited-file-modtime)))
	    
	  (and
	   uncompress-message
	   (message "%s %s...done" uncompress-message base-name))

	  (and
	   visit
	   notfound
	   (signal 'file-error
		   (cons "Opening input file" (nth 2 notfound))))

	  ;; Run the functions that insert-file-contents would.
	  (let ((p after-insert-file-functions)
		(insval size))
	    (while p
	      (setq insval (funcall (car p) size))
	      (if insval
		  (progn
		    (or (integerp insval)
			(signal 'wrong-type-argument
				(list 'integerp insval)))
		    (setq size insval)))
	      (setq p (cdr p))))

	  (list filename size))

      (jka-compr-run-real-handler 'insert-file-contents
				  (list file visit beg end replace)))))


(defun jka-compr-file-local-copy (file)
  (let* ((filename (expand-file-name file))
	 (info (jka-compr-get-compression-info filename)))

    (if info

	(let ((uncompress-message (jka-compr-info-uncompress-message info))
	      (uncompress-program (jka-compr-info-uncompress-program info))
	      (uncompress-args (jka-compr-info-uncompress-args info))
	      (base-name (file-name-nondirectory filename))
	      (local-copy
	       (jka-compr-run-real-handler 'file-local-copy (list filename)))
	      (temp-file (jka-compr-make-temp-name t))
	      (temp-buffer (get-buffer-create " *jka-compr-flc-temp*"))
	      (notfound nil)
	      (cbuf (current-buffer))
	      local-file)

	  (setq local-file (or local-copy filename))

	  (unwind-protect

	      (progn
		  
		(and
		 uncompress-message
		 (message "%s %s..." uncompress-message base-name))

		(set-buffer temp-buffer)
		  
		(jka-compr-call-process uncompress-program
					(concat uncompress-message
						" " base-name)
					local-file
					t
					nil
					uncompress-args)

		(and
		 uncompress-message
		 (message "%s %s...done" uncompress-message base-name))

		(write-region
		 (point-min) (point-max) temp-file nil 'dont))

	    (and
	     local-copy
	     (file-exists-p local-copy)
	     (delete-file local-copy))

	    (set-buffer cbuf)
	    (kill-buffer temp-buffer))

	  temp-file)
	    
      (jka-compr-run-real-handler 'file-local-copy (list filename)))))


;;; Support for loading compressed files.
(defun jka-compr-load (file &optional noerror nomessage nosuffix)
  "Documented as original."

  (let* ((local-copy (jka-compr-file-local-copy file))
	 (load-file (or local-copy file)))

    (unwind-protect

	(let (inhibit-file-name-operation
	      inhibit-file-name-handlers)
	  (or nomessage
	      (message "Loading %s..." file))

	  (let ((load-force-doc-strings t))
	    (load load-file noerror t t))

	  (or nomessage
	      (message "Loading %s...done." file)))

      (jka-compr-delete-temp-file local-copy))

    t))

(defun jka-compr-byte-compiler-base-file-name (file)
  (let ((info (jka-compr-get-compression-info file)))
    (if (and info (jka-compr-info-strip-extension info))
	(save-match-data
	  (substring file 0 (string-match (jka-compr-info-regexp info) file)))
      file)))

(put 'write-region 'jka-compr 'jka-compr-write-region)
(put 'insert-file-contents 'jka-compr 'jka-compr-insert-file-contents)
(put 'file-local-copy 'jka-compr 'jka-compr-file-local-copy)
(put 'load 'jka-compr 'jka-compr-load)
(put 'byte-compiler-base-file-name 'jka-compr
     'jka-compr-byte-compiler-base-file-name)

(defun jka-compr-handler (operation &rest args)
  (save-match-data
    (let ((jka-op (get operation 'jka-compr)))
      (if jka-op
	  (apply jka-op args)
	(jka-compr-run-real-handler operation args)))))

;; If we are given an operation that we don't handle,
;; call the Emacs primitive for that operation,
;; and manipulate the inhibit variables
;; to prevent the primitive from calling our handler again.
(defun jka-compr-run-real-handler (operation args)
  (let ((inhibit-file-name-handlers
	 (cons 'jka-compr-handler
	       (and (eq inhibit-file-name-operation operation)
		    inhibit-file-name-handlers)))
	(inhibit-file-name-operation operation))
    (apply operation args)))

;;;###autoload(defun auto-compression-mode (&optional arg)
;;;###autoload  "\
;;;###autoloadToggle automatic file compression and uncompression.
;;;###autoloadWith prefix argument ARG, turn auto compression on if positive, else off.
;;;###autoloadReturns the new status of auto compression (non-nil means on)."
;;;###autoload  (interactive "P")
;;;###autoload  (if (not (fboundp 'jka-compr-installed-p))
;;;###autoload      (progn
;;;###autoload        (require 'jka-compr)
;;;###autoload        ;; That turned the mode on, so make it initially off.
;;;###autoload        (toggle-auto-compression)))
;;;###autoload  (toggle-auto-compression arg t))

(defun toggle-auto-compression (&optional arg message)
  "Toggle automatic file compression and uncompression.
With prefix argument ARG, turn auto compression on if positive, else off.
Returns the new status of auto compression (non-nil means on).
If the argument MESSAGE is non-nil, it means to print a message
saying whether the mode is now on or off."
  (interactive "P\np")
  (let* ((installed (jka-compr-installed-p))
	 (flag (if (null arg)
		   (not installed)
		 (or (eq arg t) (listp arg) (and (integerp arg) (> arg 0))))))

    (cond
     ((and flag installed) t)		; already installed

     ((and (not flag) (not installed)) nil) ; already not installed

     (flag
      (jka-compr-install))

     (t
      (jka-compr-uninstall)))


    (and message
	 (if flag
	     (message "Automatic file (de)compression is now ON.")
	   (message "Automatic file (de)compression is now OFF.")))

    flag))

(defun jka-compr-build-file-regexp ()
  (concat
   "\\("
   (mapconcat
    'jka-compr-info-regexp
    jka-compr-compression-info-list
    "\\)\\|\\(")
   "\\)"))


(defun jka-compr-install ()
  "Install jka-compr.
This adds entries to `file-name-handler-alist' and `auto-mode-alist'
and `inhibit-first-line-modes-suffixes'."

  (setq jka-compr-file-name-handler-entry
	(cons (jka-compr-build-file-regexp) 'jka-compr-handler))

  (setq file-name-handler-alist (cons jka-compr-file-name-handler-entry
				      file-name-handler-alist))

  (mapcar
   (function (lambda (x)
	       (and (jka-compr-info-strip-extension x)
		    ;; Make entries in auto-mode-alist so that modes
		    ;; are chosen right according to the file names
		    ;; sans `.gz'.
		    (setq auto-mode-alist
			  (cons (list (jka-compr-info-regexp x)
				      nil 'jka-compr)
				auto-mode-alist))
		    ;; Also add these regexps to
		    ;; inhibit-first-line-modes-suffixes, so that a
		    ;; -*- line in the first file of a compressed tar
		    ;; file doesn't override tar-mode.
		    (setq inhibit-first-line-modes-suffixes
			  (cons (jka-compr-info-regexp x)
				inhibit-first-line-modes-suffixes)))))
   jka-compr-compression-info-list)
  (setq auto-mode-alist
	(append auto-mode-alist jka-compr-mode-alist-additions)))


(defun jka-compr-uninstall ()
  "Uninstall jka-compr.
This removes the entries in `file-name-handler-alist' and `auto-mode-alist'
and `inhibit-first-line-modes-suffixes' that were added
by `jka-compr-installed'."
  ;; Delete from inhibit-first-line-modes-suffixes
  ;; what jka-compr-install added.
  (mapcar
     (function (lambda (x)
		 (and (jka-compr-info-strip-extension x)
		      (setq inhibit-first-line-modes-suffixes
			    (delete (jka-compr-info-regexp x)
				    inhibit-first-line-modes-suffixes)))))
     jka-compr-compression-info-list)

  (let* ((fnha (cons nil file-name-handler-alist))
	 (last fnha))

    (while (cdr last)
      (if (eq (cdr (car (cdr last))) 'jka-compr-handler)
	  (setcdr last (cdr (cdr last)))
	(setq last (cdr last))))

    (setq file-name-handler-alist (cdr fnha)))

  (let* ((ama (cons nil auto-mode-alist))
	 (last ama)
	 entry)

    (while (cdr last)
      (setq entry (car (cdr last)))
      (if (or (member entry jka-compr-mode-alist-additions)
	      (and (consp (cdr entry))
		   (eq (nth 2 entry) 'jka-compr)))
	  (setcdr last (cdr (cdr last)))
	(setq last (cdr last))))
    
    (setq auto-mode-alist (cdr ama))))

      
(defun jka-compr-installed-p ()
  "Return non-nil if jka-compr is installed.
The return value is the entry in `file-name-handler-alist' for jka-compr."

  (let ((fnha file-name-handler-alist)
	(installed nil))

    (while (and fnha (not installed))
     (and (eq (cdr (car fnha)) 'jka-compr-handler)
	   (setq installed (car fnha)))
      (setq fnha (cdr fnha)))

    installed))


;;; Add the file I/O hook if it does not already exist.
;;; Make sure that jka-compr-file-name-handler-entry is eq to the
;;; entry for jka-compr in file-name-handler-alist.
(and (jka-compr-installed-p)
     (jka-compr-uninstall))

(jka-compr-install)


(provide 'jka-compr)

;; jka-compr.el ends here.