lisp/jka-cmpr-hook.el

   1 ;;; jka-cmpr-hook.el --- preloaded code to enable jka-compr.el
   2
   3 ;; Copyright (C) 1993-1995, 1997, 1999-2000, 2002-2011
   4 ;;   Free Software Foundation, Inc.
   5
   6 ;; Author: jka@ece.cmu.edu (Jay K. Adams)
   7 ;; Maintainer: FSF
   8 ;; Keywords: data
   9 ;; Package: emacs
  10
  11 ;; This file is part of GNU Emacs.
  12
  13 ;; GNU Emacs is free software: you can redistribute it and/or modify
  14 ;; it under the terms of the GNU General Public License as published by
  15 ;; the Free Software Foundation, either version 3 of the License, or
  16 ;; (at your option) any later version.
  17
  18 ;; GNU Emacs is distributed in the hope that it will be useful,
  19 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  20 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21 ;; GNU General Public License for more details.
  22
  23 ;; You should have received a copy of the GNU General Public License
  24 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  25
  26 ;;; Commentary:
  27
  28 ;; This file contains the code to enable and disable Auto-Compression mode.
  29 ;; It is preloaded.  The guts of this mode are in jka-compr.el, which
  30 ;; is loaded only when you really try to uncompress something.
  31
  32 ;;; Code:
  33
  34 (defgroup compression nil
  35   "Data compression utilities."
  36   :group 'data)
  37
  38 (defgroup jka-compr nil
  39   "jka-compr customization."
  40   :group 'compression)
  41
  42 (defcustom jka-compr-verbose t
  43   "If non-nil, output messages whenever compressing or uncompressing files."
  44   :version "24.1"
  45   :type 'boolean
  46   :group 'jka-compr)
  47
  48 ;; List of all the elements we actually added to file-coding-system-alist.
  49 (defvar jka-compr-added-to-file-coding-system-alist nil)
  50
  51 (defvar jka-compr-file-name-handler-entry
  52   nil
  53   "`file-name-handler-alist' entry used by jka-compr I/O functions.")
  54
  55 ;; Compiler defvars.  These three variables will be defined later with
  56 ;; `defcustom' when everything used in the :set functions is defined.
  57 (defvar jka-compr-compression-info-list)
  58 (defvar jka-compr-mode-alist-additions)
  59 (defvar jka-compr-load-suffixes)
  60
  61 (defvar jka-compr-compression-info-list--internal nil
  62   "Stored value of `jka-compr-compression-info-list'.
  63 If Auto Compression mode is enabled, this is the value of
  64 `jka-compr-compression-info-list' when `jka-compr-install' was last called.
  65 Otherwise, it is nil.")
  66
  67 (defvar jka-compr-mode-alist-additions--internal nil
  68   "Stored value of `jka-compr-mode-alist-additions'.
  69 If Auto Compression mode is enabled, this is the value of
  70 `jka-compr-mode-alist-additions' when `jka-compr-install' was last called.
  71 Otherwise, it is nil.")
  72
  73 (defvar jka-compr-load-suffixes--internal nil
  74   "Stored value of `jka-compr-load-suffixes'.
  75 If Auto Compression mode is enabled, this is the value of
  76 `jka-compr-load-suffixes' when `jka-compr-install' was last called.
  77 Otherwise, it is nil.")
  78
  79 \f
  80 (defun jka-compr-build-file-regexp ()
  81   (purecopy
  82    (let ((re-anchored '())
  83          (re-free '()))
  84      (dolist (e jka-compr-compression-info-list)
  85        (let ((re (jka-compr-info-regexp e)))
  86          (if (string-match "\\\\'\\'" re)
  87              (push (substring re 0 (match-beginning 0)) re-anchored)
  88            (push re re-free))))
  89      (concat
  90       (if re-free (concat (mapconcat 'identity re-free "\\|") "\\|"))
  91       "\\(?:"
  92       (mapconcat 'identity re-anchored "\\|")
  93       "\\)" file-name-version-regexp "?\\'"))))
  94
  95 ;; Functions for accessing the return value of jka-compr-get-compression-info
  96 (defun jka-compr-info-regexp               (info)  (aref info 0))
  97 (defun jka-compr-info-compress-message     (info)  (aref info 1))
  98 (defun jka-compr-info-compress-program     (info)  (aref info 2))
  99 (defun jka-compr-info-compress-args        (info)  (aref info 3))
 100 (defun jka-compr-info-uncompress-message   (info)  (aref info 4))
 101 (defun jka-compr-info-uncompress-program   (info)  (aref info 5))
 102 (defun jka-compr-info-uncompress-args      (info)  (aref info 6))
 103 (defun jka-compr-info-can-append           (info)  (aref info 7))
 104 (defun jka-compr-info-strip-extension      (info)  (aref info 8))
 105 (defun jka-compr-info-file-magic-bytes     (info)  (aref info 9))
 106
 107
 108 (defun jka-compr-get-compression-info (filename)
 109   "Return information about the compression scheme of FILENAME.
 110 The determination as to which compression scheme, if any, to use is
 111 based on the filename itself and `jka-compr-compression-info-list'."
 112   (catch 'compression-info
 113     (let ((case-fold-search nil))
 114       (dolist (x jka-compr-compression-info-list)
 115         (and (string-match (jka-compr-info-regexp x) filename)
 116              (throw 'compression-info x)))
 117       nil)))
 118
 119 (defun jka-compr-install ()
 120   "Install jka-compr.
 121 This adds entries to `file-name-handler-alist' and `auto-mode-alist'
 122 and `inhibit-first-line-modes-suffixes'."
 123
 124   (setq jka-compr-file-name-handler-entry
 125         (cons (jka-compr-build-file-regexp) 'jka-compr-handler))
 126
 127   (push jka-compr-file-name-handler-entry file-name-handler-alist)
 128
 129   (setq jka-compr-compression-info-list--internal
 130         jka-compr-compression-info-list
 131         jka-compr-mode-alist-additions--internal
 132         jka-compr-mode-alist-additions
 133         jka-compr-load-suffixes--internal
 134         jka-compr-load-suffixes)
 135
 136   (dolist (x jka-compr-compression-info-list)
 137     ;; Don't do multibyte encoding on the compressed files.
 138     (let ((elt (cons (jka-compr-info-regexp x)
 139                      '(no-conversion . no-conversion))))
 140       (push elt file-coding-system-alist)
 141       (push elt jka-compr-added-to-file-coding-system-alist))
 142
 143     (and (jka-compr-info-strip-extension x)
 144          ;; Make entries in auto-mode-alist so that modes
 145          ;; are chosen right according to the file names
 146          ;; sans `.gz'.
 147          (push (list (jka-compr-info-regexp x) nil 'jka-compr) auto-mode-alist)
 148          ;; Also add these regexps to
 149          ;; inhibit-first-line-modes-suffixes, so that a
 150          ;; -*- line in the first file of a compressed tar
 151          ;; file doesn't override tar-mode.
 152          (push (jka-compr-info-regexp x)
 153                inhibit-first-line-modes-suffixes)))
 154   (setq auto-mode-alist
 155         (append auto-mode-alist jka-compr-mode-alist-additions))
 156
 157   ;; Make sure that (load "foo") will find /bla/foo.el.gz.
 158   (setq load-file-rep-suffixes
 159         (append load-file-rep-suffixes jka-compr-load-suffixes nil)))
 160
 161 (defun jka-compr-installed-p ()
 162   "Return non-nil if jka-compr is installed.
 163 The return value is the entry in `file-name-handler-alist' for jka-compr."
 164
 165   (let ((fnha file-name-handler-alist)
 166         (installed nil))
 167
 168     (while (and fnha (not installed))
 169      (and (eq (cdr (car fnha)) 'jka-compr-handler)
 170            (setq installed (car fnha)))
 171       (setq fnha (cdr fnha)))
 172
 173     installed))
 174
 175 (defun jka-compr-update ()
 176   "Update Auto Compression mode for changes in option values.
 177 If you change the options `jka-compr-compression-info-list',
 178 `jka-compr-mode-alist-additions' or `jka-compr-load-suffixes'
 179 outside Custom, while Auto Compression mode is already enabled
 180 \(as it is by default), then you have to call this function
 181 afterward to properly update other variables.  Setting these
 182 options through Custom does this automatically."
 183   (when (jka-compr-installed-p)
 184     (jka-compr-uninstall)
 185     (jka-compr-install)))
 186
 187 (defun jka-compr-set (variable value)
 188   "Internal Custom :set function."
 189   (set-default variable value)
 190   (jka-compr-update))
 191
 192 ;; I have this defined so that .Z files are assumed to be in unix
 193 ;; compress format; and .gz files, in gzip format, and .bz2 files in bzip fmt.
 194
 195 ;; FIXME? It seems ugly that one has to add "\\(~\\|\\.~[0-9]+~\\)?" to
 196 ;; all the regexps here, in order to match backup files etc.
 197 ;; It's trivial to modify jka-compr-get-compression-info to match
 198 ;; regexps against file-name-sans-versions, but this regexp is also
 199 ;; used to build a file-name-handler-alist entry.
 200 ;; find-file-name-handler does not use file-name-sans-versions.
 201 ;; Perhaps it should,
 202 ;; http://lists.gnu.org/archive/html/emacs-devel/2008-02/msg00812.html,
 203 ;; but it's used all over the place and there are probably other ramifications.
 204 ;; One could modify jka-compr-build-file-regexp to add the backup regexp,
 205 ;; but jka-compr-compression-info-list is a defcustom to which
 206 ;; anything could be added, so it's easiest to leave things as they are.
 207 (defcustom jka-compr-compression-info-list
 208   ;;[regexp
 209   ;; compr-message  compr-prog  compr-args
 210   ;; uncomp-message uncomp-prog uncomp-args
 211   ;; can-append strip-extension-flag file-magic-bytes]
 212   (mapcar 'purecopy
 213   '(["\\.Z\\'"
 214      "compressing"    "compress"     ("-c")
 215      ;; gzip is more common than uncompress. It can only read, not write.
 216      "uncompressing"  "gzip"   ("-c" "-q" "-d")
 217      nil t "\037\235"]
 218      ;; Formerly, these had an additional arg "-c", but that fails with
 219      ;; "Version 0.1pl2, 29-Aug-97." (RedHat 5.1 GNU/Linux) and
 220      ;; "Version 0.9.0b, 9-Sept-98".
 221     ["\\.bz2\\'"
 222      "bzip2ing"        "bzip2"         nil
 223      "bunzip2ing"      "bzip2"         ("-d")
 224      nil t "BZh"]
 225     ["\\.tbz2?\\'"
 226      "bzip2ing"        "bzip2"         nil
 227      "bunzip2ing"      "bzip2"         ("-d")
 228      nil nil "BZh"]
 229     ["\\.\\(?:tgz\\|svgz\\|sifz\\)\\'"
 230      "compressing"        "gzip"         ("-c" "-q")
 231      "uncompressing"      "gzip"         ("-c" "-q" "-d")
 232      t nil "\037\213"]
 233     ["\\.g?z\\'"
 234      "compressing"        "gzip"         ("-c" "-q")
 235      "uncompressing"      "gzip"         ("-c" "-q" "-d")
 236      t t "\037\213"]
 237     ["\\.xz\\'"
 238      "XZ compressing"     "xz"           ("-c" "-q")
 239      "XZ uncompressing"   "xz"           ("-c" "-q" "-d")
 240      t t "\3757zXZ\0"]
 241     ;; dzip is gzip with random access.  Its compression program can't
 242     ;; read/write stdin/out, so .dz files can only be viewed without
 243     ;; saving, having their contents decompressed with gzip.
 244     ["\\.dz\\'"
 245      nil              nil            nil
 246      "uncompressing"      "gzip"         ("-c" "-q" "-d")
 247      nil t "\037\213"]))
 248
 249   "List of vectors that describe available compression techniques.
 250 Each element, which describes a compression technique, is a vector of
 251 the form [REGEXP COMPRESS-MSG COMPRESS-PROGRAM COMPRESS-ARGS
 252 UNCOMPRESS-MSG UNCOMPRESS-PROGRAM UNCOMPRESS-ARGS
 253 APPEND-FLAG STRIP-EXTENSION-FLAG FILE-MAGIC-CHARS], where:
 254
 255    regexp                is a regexp that matches filenames that are
 256                          compressed with this format
 257
 258    compress-msg          is the message to issue to the user when doing this
 259                          type of compression (nil means no message)
 260
 261    compress-program      is a program that performs this compression
 262                          (nil means visit file in read-only mode)
 263
 264    compress-args         is a list of args to pass to the compress program
 265
 266    uncompress-msg        is the message to issue to the user when doing this
 267                          type of uncompression (nil means no message)
 268
 269    uncompress-program    is a program that performs this compression
 270
 271    uncompress-args       is a list of args to pass to the uncompress program
 272
 273    append-flag           is non-nil if this compression technique can be
 274                          appended
 275
 276    strip-extension-flag  non-nil means strip the regexp from file names
 277                          before attempting to set the mode.
 278
 279    file-magic-chars      is a string of characters that you would find
 280                          at the beginning of a file compressed in this way.
 281
 282 If you set this outside Custom while Auto Compression mode is
 283 already enabled \(as it is by default), you have to call
 284 `jka-compr-update' after setting it to properly update other
 285 variables.  Setting this through Custom does that automatically."
 286   :type '(repeat (vector regexp
 287                          (choice :tag "Compress Message"
 288                                  (string :format "%v")
 289                                  (const :tag "No Message" nil))
 290                          (choice :tag "Compress Program"
 291                                  (string)
 292                                  (const :tag "None" nil))
 293                          (repeat :tag "Compress Arguments" string)
 294                          (choice :tag "Uncompress Message"
 295                                  (string :format "%v")
 296                                  (const :tag "No Message" nil))
 297                          (choice :tag "Uncompress Program"
 298                                  (string)
 299                                  (const :tag "None" nil))
 300                          (repeat :tag "Uncompress Arguments" string)
 301                          (boolean :tag "Append")
 302                          (boolean :tag "Strip Extension")
 303                          (string :tag "Magic Bytes")))
 304   :set 'jka-compr-set
 305   :group 'jka-compr)
 306
 307 (defcustom jka-compr-mode-alist-additions
 308   (list (cons (purecopy "\\.tgz\\'") 'tar-mode) (cons (purecopy "\\.tbz2?\\'") 'tar-mode))
 309   "List of pairs added to `auto-mode-alist' when installing jka-compr.
 310 Uninstalling jka-compr removes all pairs from `auto-mode-alist' that
 311 installing added.
 312
 313 If you set this outside Custom while Auto Compression mode is
 314 already enabled \(as it is by default), you have to call
 315 `jka-compr-update' after setting it to properly update other
 316 variables.  Setting this through Custom does that automatically."
 317   :type '(repeat (cons string symbol))
 318   :set 'jka-compr-set
 319   :group 'jka-compr)
 320
 321 (defcustom jka-compr-load-suffixes (list (purecopy ".gz"))
 322   "List of compression related suffixes to try when loading files.
 323 Enabling Auto Compression mode appends this list to `load-file-rep-suffixes',
 324 which see.  Disabling Auto Compression mode removes all suffixes
 325 from `load-file-rep-suffixes' that enabling added.
 326
 327 If you set this outside Custom while Auto Compression mode is
 328 already enabled \(as it is by default), you have to call
 329 `jka-compr-update' after setting it to properly update other
 330 variables.  Setting this through Custom does that automatically."
 331   :type '(repeat string)
 332   :set 'jka-compr-set
 333   :group 'jka-compr)
 334
 335 (define-minor-mode auto-compression-mode
 336   "Toggle automatic file compression and uncompression.
 337 With prefix argument ARG, turn auto compression on if positive, else off.
 338 Return the new status of auto compression (non-nil means on)."
 339   :global t :init-value t :group 'jka-compr :version "22.1"
 340   (let* ((installed (jka-compr-installed-p))
 341          (flag auto-compression-mode))
 342     (cond
 343      ((and flag installed) t)           ; already installed
 344      ((and (not flag) (not installed)) nil) ; already not installed
 345      (flag (jka-compr-install))
 346      (t (jka-compr-uninstall)))))
 347
 348 (defmacro with-auto-compression-mode (&rest body)
 349   "Evaluate BODY with automatic file compression and uncompression enabled."
 350   (declare (indent 0))
 351   (let ((already-installed (make-symbol "already-installed")))
 352     `(let ((,already-installed (jka-compr-installed-p)))
 353        (unwind-protect
 354            (progn
 355              (unless ,already-installed
 356                (jka-compr-install))
 357              ,@body)
 358          (unless ,already-installed
 359            (jka-compr-uninstall))))))
 360
 361 ;; This is what we need to know about jka-compr-handler
 362 ;; in order to decide when to call it.
 363
 364 (put 'jka-compr-handler 'safe-magic t)
 365 (put 'jka-compr-handler 'operations '(byte-compiler-base-file-name
 366                                       write-region insert-file-contents
 367                                       file-local-copy load))
 368
 369 ;; Turn on the mode.
 370 (when auto-compression-mode (auto-compression-mode 1))
 371
 372 (provide 'jka-cmpr-hook)
 373
 374 ;;; jka-cmpr-hook.el ends here