lisp/jka-compr.el

   1 ;;; jka-compr.el --- reading/writing/loading compressed files
   2
   3 ;; Copyright (C) 1993, 1994, 1995, 1997, 1999, 2000, 2001, 2002, 2003,
   4 ;;   2004, 2005, 2006, 2007, 2008 Free Software Foundation, Inc.
   5
   6 ;; Author: jka@ece.cmu.edu (Jay K. Adams)
   7 ;; Maintainer: FSF
   8 ;; Keywords: data
   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 ;; This package implements low-level support for reading, writing,
  28 ;; and loading compressed files.  It hooks into the low-level file
  29 ;; I/O functions (including write-region and insert-file-contents) so
  30 ;; that they automatically compress or uncompress a file if the file
  31 ;; appears to need it (based on the extension of the file name).
  32 ;; Packages like Rmail, VM, GNUS, and Info should be able to work
  33 ;; with compressed files without modification.
  34
  35
  36 ;; INSTRUCTIONS:
  37 ;;
  38 ;; To use jka-compr, invoke the command `auto-compression-mode' (which
  39 ;; see), or customize the variable of the same name.  Its operation
  40 ;; should be transparent to the user (except for messages appearing when
  41 ;; a file is being compressed or uncompressed).
  42 ;;
  43 ;; The variable, jka-compr-compression-info-list can be used to
  44 ;; customize jka-compr to work with other compression programs.
  45 ;; The default value of this variable allows jka-compr to work with
  46 ;; Unix compress and gzip.
  47 ;;
  48 ;; If you don't want messages about compressing and decompressing
  49 ;; to show up in the echo area, you can set the compress-msg and
  50 ;; decompress-msg fields of the jka-compr-compression-info-list to
  51 ;; nil.
  52
  53
  54 ;; APPLICATION NOTES:
  55 ;;
  56 ;; crypt++
  57 ;;   jka-compr can coexist with crypt++ if you take all the decompression
  58 ;;   entries out of the crypt-encoding-list.  Clearly problems will arise if
  59 ;;   you have two programs trying to compress/decompress files.  jka-compr
  60 ;;   will not "work with" crypt++ in the following sense: you won't be able to
  61 ;;   decode encrypted compressed files--that is, files that have been
  62 ;;   compressed then encrypted (in that order).  Theoretically, crypt++ and
  63 ;;   jka-compr could properly handle a file that has been encrypted then
  64 ;;   compressed, but there is little point in trying to compress an encrypted
  65 ;;   file.
  66 ;;
  67
  68
  69 ;; ACKNOWLEDGMENTS
  70 ;;
  71 ;; jka-compr is a V19 adaptation of jka-compr for V18 of Emacs.  Many people
  72 ;; have made helpful suggestions, reported bugs, and even fixed bugs in
  73 ;; jka-compr.  I recall the following people as being particularly helpful.
  74 ;;
  75 ;;   Jean-loup Gailly
  76 ;;   David Hughes
  77 ;;   Richard Pieri
  78 ;;   Daniel Quinlan
  79 ;;   Chris P. Ross
  80 ;;   Rick Sladkey
  81 ;;
  82 ;; Andy Norman's ange-ftp was the inspiration for the original jka-compr for
  83 ;; Version 18 of Emacs.
  84 ;;
  85 ;; After I had made progress on the original jka-compr for V18, I learned of a
  86 ;; package written by Kazushi Jam Marukawa, called jam-zcat, that did exactly
  87 ;; what I was trying to do.  I looked over the jam-zcat source code and
  88 ;; probably got some ideas from it.
  89 ;;
  90
  91 ;;; Code:
  92
  93 (require 'jka-cmpr-hook)
  94
  95 (defcustom jka-compr-shell "sh"
  96   "Shell to be used for calling compression programs.
  97 NOTE: Not used in MS-DOS and Windows systems."
  98   :type 'string
  99   :group 'jka-compr)
 100
 101 (defvar jka-compr-use-shell
 102   (not (memq system-type '(ms-dos windows-nt))))
 103
 104 (defvar jka-compr-really-do-compress nil
 105   "Non-nil in a buffer whose visited file was uncompressed on visiting it.
 106 This means compress the data on writing the file, even if the
 107 data appears to be compressed already.")
 108 (make-variable-buffer-local 'jka-compr-really-do-compress)
 109 (put 'jka-compr-really-do-compress 'permanent-local t)
 110 \f
 111
 112 (put 'compression-error 'error-conditions '(compression-error file-error error))
 113
 114
 115 (defvar jka-compr-acceptable-retval-list '(0 2 141))
 116
 117
 118 (defun jka-compr-error (prog args infile message &optional errfile)
 119
 120   (let ((errbuf (get-buffer-create " *jka-compr-error*")))
 121     (with-current-buffer errbuf
 122       (widen) (erase-buffer)
 123       (insert (format "Error while executing \"%s %s < %s\"\n\n"
 124                       prog
 125                       (mapconcat 'identity args " ")
 126                       infile))
 127
 128       (and errfile
 129            (insert-file-contents errfile)))
 130      (display-buffer errbuf))
 131
 132   (signal 'compression-error
 133           (list "Opening input file" (format "error %s" message) infile)))
 134
 135
 136 (defcustom jka-compr-dd-program "/bin/dd"
 137   "How to invoke `dd'."
 138   :type 'string
 139   :group 'jka-compr)
 140
 141
 142 (defvar jka-compr-dd-blocksize 256)
 143
 144
 145 (defun jka-compr-partial-uncompress (prog message args infile beg len)
 146   "Call program PROG with ARGS args taking input from INFILE.
 147 Fourth and fifth args, BEG and LEN, specify which part of the output
 148 to keep: LEN chars starting BEG chars from the beginning."
 149   (let ((start (point))
 150         (prefix beg))
 151     (if (and jka-compr-use-shell jka-compr-dd-program)
 152         ;; Put the uncompression output through dd
 153         ;; to discard the part we don't want.
 154         (let ((skip (/ beg jka-compr-dd-blocksize))
 155               (err-file (jka-compr-make-temp-name))
 156               ;; call-process barfs if default-directory is inaccessible.
 157               (default-directory
 158                 (if (and default-directory
 159                          (file-accessible-directory-p default-directory))
 160                     default-directory
 161                   (file-name-directory infile)))
 162               count)
 163           ;; Update PREFIX based on the text that we won't read in.
 164           (setq prefix (- beg (* skip jka-compr-dd-blocksize))
 165                 count (and len (1+ (/ (+ len prefix) jka-compr-dd-blocksize))))
 166           (unwind-protect
 167               (or (memq (call-process
 168                          jka-compr-shell infile t nil "-c"
 169                          (format
 170                           "%s %s 2> %s | %s bs=%d skip=%d %s 2> %s"
 171                           prog
 172                           (mapconcat 'identity args " ")
 173                           err-file
 174                           jka-compr-dd-program
 175                           jka-compr-dd-blocksize
 176                           skip
 177                           ;; dd seems to be unreliable about
 178                           ;; providing the last block.  So, always
 179                           ;; read one more than you think you need.
 180                           (if count (format "count=%d" (1+ count)) "")
 181                           null-device))
 182                         jka-compr-acceptable-retval-list)
 183                   (jka-compr-error prog args infile message err-file))
 184             (jka-compr-delete-temp-file err-file)))
 185       ;; Run the uncompression program directly.
 186       ;; We get the whole file and must delete what we don't want.
 187       (jka-compr-call-process prog message infile t nil args))
 188
 189     ;; Delete the stuff after what we want, if there is any.
 190     (and
 191      len
 192      (< (+ start prefix len) (point))
 193      (delete-region (+ start prefix len) (point)))
 194
 195     ;; Delete the stuff before what we want.
 196     (delete-region start (+ start prefix))))
 197
 198
 199 (defun jka-compr-call-process (prog message infile output temp args)
 200   ;; call-process barfs if default-directory is inaccessible.
 201   (let ((default-directory
 202           (if (and default-directory
 203                    (file-accessible-directory-p default-directory))
 204               default-directory
 205             (file-name-directory infile))))
 206     (if jka-compr-use-shell
 207         (let ((err-file (jka-compr-make-temp-name))
 208               (coding-system-for-read (or coding-system-for-read 'undecided))
 209               (coding-system-for-write 'no-conversion))
 210           (unwind-protect
 211               (or (memq
 212                    (call-process jka-compr-shell infile
 213                                  (if (stringp output) nil output)
 214                                  nil
 215                                  "-c"
 216                                  (format "%s %s 2> %s %s"
 217                                          prog
 218                                          (mapconcat 'identity args " ")
 219                                          err-file
 220                                          (if (stringp output)
 221                                              (concat "> " output)
 222                                            "")))
 223                    jka-compr-acceptable-retval-list)
 224                   (jka-compr-error prog args infile message err-file))
 225             (jka-compr-delete-temp-file err-file)))
 226       (or (eq 0
 227               (apply 'call-process
 228                      prog infile (if (stringp output) temp output)
 229                      nil args))
 230           (jka-compr-error prog args infile message))
 231       (and (stringp output)
 232            (with-current-buffer temp
 233              (write-region (point-min) (point-max) output)
 234              (erase-buffer))))))
 235
 236
 237 ;; Support for temp files.  Much of this was inspired if not lifted
 238 ;; from ange-ftp.
 239
 240 (defcustom jka-compr-temp-name-template
 241   (expand-file-name "jka-com" temporary-file-directory)
 242   "Prefix added to all temp files created by jka-compr.
 243 There should be no more than seven characters after the final `/'."
 244   :type 'string
 245   :group 'jka-compr)
 246
 247 (defun jka-compr-make-temp-name (&optional local-copy)
 248   "This routine will return the name of a new file."
 249   (make-temp-file jka-compr-temp-name-template))
 250
 251 (defalias 'jka-compr-delete-temp-file 'delete-file)
 252
 253
 254 (defun jka-compr-write-region (start end file &optional append visit)
 255   (let* ((filename (expand-file-name file))
 256          (visit-file (if (stringp visit) (expand-file-name visit) filename))
 257          (info (jka-compr-get-compression-info visit-file))
 258          (magic (and info (jka-compr-info-file-magic-bytes info))))
 259
 260     ;; If we uncompressed this file when visiting it,
 261     ;; then recompress it when writing it
 262     ;; even if the contents look compressed already.
 263     (if (and jka-compr-really-do-compress
 264              (or (null start)
 265                  (= (- end start) (buffer-size))))
 266         (setq magic nil))
 267
 268     (if (and info
 269              ;; If the contents to be written out
 270              ;; are properly compressed already,
 271              ;; don't try to compress them over again.
 272              (not (and magic
 273                        (equal (if (stringp start)
 274                                   (substring start 0 (min (length start)
 275                                                           (length magic)))
 276                                 (let* ((from (or start (point-min)))
 277                                        (to (min (or end (point-max))
 278                                                 (+ from (length magic)))))
 279                                   (buffer-substring from to)))
 280                               magic))))
 281         (let ((can-append (jka-compr-info-can-append info))
 282               (compress-program (jka-compr-info-compress-program info))
 283               (compress-message (jka-compr-info-compress-message info))
 284               (compress-args (jka-compr-info-compress-args info))
 285               (base-name (file-name-nondirectory visit-file))
 286               temp-file temp-buffer
 287               ;; we need to leave `last-coding-system-used' set to its
 288               ;; value after calling write-region the first time, so
 289               ;; that `basic-save-buffer' sees the right value.
 290               (coding-system-used last-coding-system-used))
 291
 292           (or compress-program
 293               (error "No compression program defined"))
 294
 295           (setq temp-buffer (get-buffer-create " *jka-compr-wr-temp*"))
 296           (with-current-buffer temp-buffer
 297             (widen) (erase-buffer))
 298
 299           (if (and append
 300                    (not can-append)
 301                    (file-exists-p filename))
 302
 303               (let* ((local-copy (file-local-copy filename))
 304                      (local-file (or local-copy filename)))
 305
 306                 (setq temp-file local-file))
 307
 308             (setq temp-file (jka-compr-make-temp-name)))
 309
 310           (and
 311            compress-message
 312            (message "%s %s..." compress-message base-name))
 313
 314           (jka-compr-run-real-handler 'write-region
 315                                       (list start end temp-file t 'dont))
 316           ;; save value used by the real write-region
 317           (setq coding-system-used last-coding-system-used)
 318
 319           ;; Here we must read the output of compress program as is
 320           ;; without any code conversion.
 321           (let ((coding-system-for-read 'no-conversion))
 322             (jka-compr-call-process compress-program
 323                                     (concat compress-message
 324                                             " " base-name)
 325                                     temp-file
 326                                     temp-buffer
 327                                     nil
 328                                     compress-args))
 329
 330           (with-current-buffer temp-buffer
 331             (let ((coding-system-for-write 'no-conversion))
 332               (if (memq system-type '(ms-dos windows-nt))
 333                   (setq buffer-file-type t) )
 334               (jka-compr-run-real-handler 'write-region
 335                                           (list (point-min) (point-max)
 336                                                 filename
 337                                                 (and append can-append) 'dont))
 338               (erase-buffer)) )
 339
 340           (jka-compr-delete-temp-file temp-file)
 341
 342           (and
 343            compress-message
 344            (message "%s %s...done" compress-message base-name))
 345
 346           (cond
 347            ((eq visit t)
 348             (setq buffer-file-name filename)
 349             (setq jka-compr-really-do-compress t)
 350             (set-visited-file-modtime))
 351            ((stringp visit)
 352             (setq buffer-file-name visit)
 353             (let ((buffer-file-name filename))
 354               (set-visited-file-modtime))))
 355
 356           (and (or (eq visit t)
 357                    (eq visit nil)
 358                    (stringp visit))
 359                (message "Wrote %s" visit-file))
 360
 361           ;; ensure `last-coding-system-used' has an appropriate value
 362           (setq last-coding-system-used coding-system-used)
 363
 364           nil)
 365
 366       (jka-compr-run-real-handler 'write-region
 367                                   (list start end filename append visit)))))
 368
 369
 370 (defun jka-compr-insert-file-contents (file &optional visit beg end replace)
 371   (barf-if-buffer-read-only)
 372
 373   (and (or beg end)
 374        visit
 375        (error "Attempt to visit less than an entire file"))
 376
 377   (let* ((filename (expand-file-name file))
 378          (info (jka-compr-get-compression-info filename)))
 379
 380     (if (not info)
 381
 382         (jka-compr-run-real-handler 'insert-file-contents
 383                                     (list file visit beg end replace))
 384
 385       (let ((uncompress-message (jka-compr-info-uncompress-message info))
 386             (uncompress-program (jka-compr-info-uncompress-program info))
 387             (uncompress-args (jka-compr-info-uncompress-args info))
 388             (base-name (file-name-nondirectory filename))
 389             (notfound nil)
 390             (local-copy
 391              (jka-compr-run-real-handler 'file-local-copy (list filename)))
 392             local-file
 393             size start)
 394
 395         (setq local-file (or local-copy filename))
 396
 397         (and
 398          visit
 399          (setq buffer-file-name filename))
 400
 401         (unwind-protect               ; to make sure local-copy gets deleted
 402
 403             (progn
 404
 405               (and
 406                uncompress-message
 407                (message "%s %s..." uncompress-message base-name))
 408
 409               (condition-case error-code
 410
 411                   (let ((coding-system-for-read 'no-conversion))
 412                     (if replace
 413                         (goto-char (point-min)))
 414                     (setq start (point))
 415                     (if (or beg end)
 416                         (jka-compr-partial-uncompress uncompress-program
 417                                                       (concat uncompress-message
 418                                                               " " base-name)
 419                                                       uncompress-args
 420                                                       local-file
 421                                                       (or beg 0)
 422                                                       (if (and beg end)
 423                                                           (- end beg)
 424                                                         end))
 425                       ;; If visiting, bind off buffer-file-name so that
 426                       ;; file-locking will not ask whether we should
 427                       ;; really edit the buffer.
 428                       (let ((buffer-file-name
 429                              (if visit nil buffer-file-name)))
 430                         (jka-compr-call-process uncompress-program
 431                                                 (concat uncompress-message
 432                                                         " " base-name)
 433                                                 local-file
 434                                                 t
 435                                                 nil
 436                                                 uncompress-args)))
 437                     (setq size (- (point) start))
 438                     (if replace
 439                         (delete-region (point) (point-max)))
 440                     (goto-char start))
 441                 (error
 442                  ;; If the file we wanted to uncompress does not exist,
 443                  ;; handle that according to VISIT as `insert-file-contents'
 444                  ;; would, maybe signaling the same error it normally would.
 445                  (if (and (eq (car error-code) 'file-error)
 446                           (eq (nth 3 error-code) local-file))
 447                      (if visit
 448                          (setq notfound error-code)
 449                        (signal 'file-error
 450                                (cons "Opening input file"
 451                                      (nthcdr 2 error-code))))
 452                    ;; If the uncompression program can't be found,
 453                    ;; signal that as a non-file error
 454                    ;; so that find-file-noselect-1 won't handle it.
 455                    (if (and (eq (car error-code) 'file-error)
 456                             (equal (cadr error-code) "Searching for program"))
 457                        (error "Uncompression program `%s' not found"
 458                               (nth 3 error-code)))
 459                    (signal (car error-code) (cdr error-code))))))
 460
 461           (and
 462            local-copy
 463            (file-exists-p local-copy)
 464            (delete-file local-copy)))
 465
 466         (unless notfound
 467           (decode-coding-inserted-region
 468            (point) (+ (point) size)
 469            (jka-compr-byte-compiler-base-file-name file)
 470            visit beg end replace))
 471
 472         (and
 473          visit
 474          (progn
 475            (unlock-buffer)
 476            (setq buffer-file-name filename)
 477            (setq jka-compr-really-do-compress t)
 478            (set-visited-file-modtime)))
 479
 480         (and
 481          uncompress-message
 482          (message "%s %s...done" uncompress-message base-name))
 483
 484         (and
 485          visit
 486          notfound
 487          (signal 'file-error
 488                  (cons "Opening input file" (nth 2 notfound))))
 489
 490         ;; This is done in insert-file-contents after we return.
 491         ;; That is a little weird, but better to go along with it now
 492         ;; than to change it now.
 493
 494         ;; ;; Run the functions that insert-file-contents would.
 495         ;; (let ((p after-insert-file-functions)
 496         ;;       (insval size))
 497         ;;   (while p
 498         ;;     (setq insval (funcall (car p) size))
 499         ;;     (if insval
 500         ;;         (progn
 501         ;;           (or (integerp insval)
 502         ;;              (signal 'wrong-type-argument
 503         ;;                      (list 'integerp insval)))
 504         ;;           (setq size insval)))
 505         ;;     (setq p (cdr p))))
 506
 507         (or (jka-compr-info-compress-program info)
 508             (message "You can't save this buffer because compression program is not defined"))
 509
 510         (list filename size)))))
 511
 512
 513 (defun jka-compr-file-local-copy (file)
 514   (let* ((filename (expand-file-name file))
 515          (info (jka-compr-get-compression-info filename)))
 516
 517     (if info
 518
 519         (let ((uncompress-message (jka-compr-info-uncompress-message info))
 520               (uncompress-program (jka-compr-info-uncompress-program info))
 521               (uncompress-args (jka-compr-info-uncompress-args info))
 522               (base-name (file-name-nondirectory filename))
 523               (local-copy
 524                (jka-compr-run-real-handler 'file-local-copy (list filename)))
 525               (temp-file (jka-compr-make-temp-name t))
 526               (temp-buffer (get-buffer-create " *jka-compr-flc-temp*"))
 527               local-file)
 528
 529           (setq local-file (or local-copy filename))
 530
 531           (unwind-protect
 532
 533               (with-current-buffer temp-buffer
 534
 535                 (and
 536                  uncompress-message
 537                  (message "%s %s..." uncompress-message base-name))
 538
 539                 ;; Here we must read the output of uncompress program
 540                 ;; and write it to TEMP-FILE without any code
 541                 ;; conversion.  An appropriate code conversion (if
 542                 ;; necessary) is done by the later I/O operation
 543                 ;; (e.g. load).
 544                 (let ((coding-system-for-read 'no-conversion)
 545                       (coding-system-for-write 'no-conversion))
 546
 547                   (jka-compr-call-process uncompress-program
 548                                           (concat uncompress-message
 549                                                   " " base-name)
 550                                           local-file
 551                                           t
 552                                           nil
 553                                           uncompress-args)
 554
 555                   (and
 556                    uncompress-message
 557                    (message "%s %s...done" uncompress-message base-name))
 558
 559                   (write-region
 560                    (point-min) (point-max) temp-file nil 'dont)))
 561
 562             (and
 563              local-copy
 564              (file-exists-p local-copy)
 565              (delete-file local-copy))
 566
 567             (kill-buffer temp-buffer))
 568
 569           temp-file)
 570
 571       (jka-compr-run-real-handler 'file-local-copy (list filename)))))
 572
 573
 574 ;; Support for loading compressed files.
 575 (defun jka-compr-load (file &optional noerror nomessage nosuffix)
 576   "Documented as original."
 577
 578   (let* ((local-copy (jka-compr-file-local-copy file))
 579          (load-file (or local-copy file)))
 580
 581     (unwind-protect
 582
 583         (let (inhibit-file-name-operation
 584               inhibit-file-name-handlers)
 585           (or nomessage
 586               (message "Loading %s..." file))
 587
 588           (let ((load-force-doc-strings t))
 589             (load load-file noerror t t))
 590           (or nomessage
 591               (message "Loading %s...done." file))
 592           ;; Fix up the load history to point at the right library.
 593           (let ((l (assoc load-file load-history)))
 594             ;; Remove .gz and .elc?.
 595             (while (file-name-extension file)
 596               (setq file (file-name-sans-extension file)))
 597             (setcar l file)))
 598
 599       (jka-compr-delete-temp-file local-copy))
 600
 601     t))
 602
 603 (defun jka-compr-byte-compiler-base-file-name (file)
 604   (let ((info (jka-compr-get-compression-info file)))
 605     (if (and info (jka-compr-info-strip-extension info))
 606         (save-match-data
 607           (substring file 0 (string-match (jka-compr-info-regexp info) file)))
 608       file)))
 609 \f
 610 (put 'write-region 'jka-compr 'jka-compr-write-region)
 611 (put 'insert-file-contents 'jka-compr 'jka-compr-insert-file-contents)
 612 (put 'file-local-copy 'jka-compr 'jka-compr-file-local-copy)
 613 (put 'load 'jka-compr 'jka-compr-load)
 614 (put 'byte-compiler-base-file-name 'jka-compr
 615      'jka-compr-byte-compiler-base-file-name)
 616
 617 ;;;###autoload
 618 (defvar jka-compr-inhibit nil
 619   "Non-nil means inhibit automatic uncompression temporarily.
 620 Lisp programs can bind this to t to do that.
 621 It is not recommended to set this variable permanently to anything but nil.")
 622
 623 ;;;###autoload
 624 (defun jka-compr-handler (operation &rest args)
 625   (save-match-data
 626     (let ((jka-op (get operation 'jka-compr)))
 627       (if (and jka-op (not jka-compr-inhibit))
 628           (apply jka-op args)
 629         (jka-compr-run-real-handler operation args)))))
 630
 631 ;; If we are given an operation that we don't handle,
 632 ;; call the Emacs primitive for that operation,
 633 ;; and manipulate the inhibit variables
 634 ;; to prevent the primitive from calling our handler again.
 635 (defun jka-compr-run-real-handler (operation args)
 636   (let ((inhibit-file-name-handlers
 637          (cons 'jka-compr-handler
 638                (and (eq inhibit-file-name-operation operation)
 639                     inhibit-file-name-handlers)))
 640         (inhibit-file-name-operation operation))
 641     (apply operation args)))
 642
 643 ;;;###autoload
 644 (defun jka-compr-uninstall ()
 645   "Uninstall jka-compr.
 646 This removes the entries in `file-name-handler-alist' and `auto-mode-alist'
 647 and `inhibit-first-line-modes-suffixes' that were added
 648 by `jka-compr-installed'."
 649   ;; Delete from inhibit-first-line-modes-suffixes
 650   ;; what jka-compr-install added.
 651   (mapc
 652      (function (lambda (x)
 653                  (and (jka-compr-info-strip-extension x)
 654                       (setq inhibit-first-line-modes-suffixes
 655                             (delete (jka-compr-info-regexp x)
 656                                     inhibit-first-line-modes-suffixes)))))
 657      jka-compr-compression-info-list--internal)
 658
 659   (let* ((fnha (cons nil file-name-handler-alist))
 660          (last fnha))
 661
 662     (while (cdr last)
 663       (if (eq (cdr (car (cdr last))) 'jka-compr-handler)
 664           (setcdr last (cdr (cdr last)))
 665         (setq last (cdr last))))
 666
 667     (setq file-name-handler-alist (cdr fnha)))
 668
 669   (let* ((ama (cons nil auto-mode-alist))
 670          (last ama)
 671          entry)
 672
 673     (while (cdr last)
 674       (setq entry (car (cdr last)))
 675       (if (or (member entry jka-compr-mode-alist-additions--internal)
 676               (and (consp (cdr entry))
 677                    (eq (nth 2 entry) 'jka-compr)))
 678           (setcdr last (cdr (cdr last)))
 679         (setq last (cdr last))))
 680
 681     (setq auto-mode-alist (cdr ama)))
 682
 683   (while jka-compr-added-to-file-coding-system-alist
 684     (setq file-coding-system-alist
 685           (delq (car (member (pop jka-compr-added-to-file-coding-system-alist)
 686                              file-coding-system-alist))
 687                 file-coding-system-alist)))
 688
 689   ;; Remove the suffixes that were added by jka-compr.
 690   (dolist (suff jka-compr-load-suffixes--internal)
 691     (setq load-file-rep-suffixes (delete suff load-file-rep-suffixes)))
 692
 693   (setq jka-compr-compression-info-list--internal nil
 694         jka-compr-mode-alist-additions--internal nil
 695         jka-compr-load-suffixes--internal nil))
 696
 697 (provide 'jka-compr)
 698
 699 ;; arch-tag: 3f15b630-e9a7-46c4-a22a-94afdde86ebc
 700 ;;; jka-compr.el ends here