lisp/tar-mode.el

   1 ;;; tar-mode.el --- simple editing of tar files from GNU emacs
   2
   3 ;; Copyright (C) 1990, 1991, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
   4 ;;   2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008 Free Software Foundation, Inc.
   5
   6 ;; Author: Jamie Zawinski <jwz@lucid.com>
   7 ;; Maintainer: FSF
   8 ;; Created: 04 Apr 1990
   9 ;; Keywords: unix
  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 package attempts to make dealing with Unix 'tar' archives easier.
  29 ;; When this code is loaded, visiting a file whose name ends in '.tar' will
  30 ;; cause the contents of that archive file to be displayed in a Dired-like
  31 ;; listing.  It is then possible to use the customary Dired keybindings to
  32 ;; extract sub-files from that archive, either by reading them into their own
  33 ;; editor buffers, or by copying them directly to arbitrary files on disk.
  34 ;; It is also possible to delete sub-files from within the tar file and write
  35 ;; the modified archive back to disk, or to edit sub-files within the archive
  36 ;; and re-insert the modified files into the archive.  See the documentation
  37 ;; string of tar-mode for more info.
  38
  39 ;; This code now understands the extra fields that GNU tar adds to tar files.
  40
  41 ;; This interacts correctly with "uncompress.el" in the Emacs library,
  42 ;; which you get with
  43 ;;
  44 ;;  (autoload 'uncompress-while-visiting "uncompress")
  45 ;;  (setq auto-mode-alist (cons '("\\.Z$" . uncompress-while-visiting)
  46 ;;                         auto-mode-alist))
  47 ;;
  48 ;; Do not attempt to use tar-mode.el with crypt.el, you will lose.
  49
  50 ;;    ***************   TO DO   ***************
  51 ;;
  52 ;; o  chmod should understand "a+x,og-w".
  53 ;;
  54 ;; o  It's not possible to add a NEW file to a tar archive; not that
  55 ;;    important, but still...
  56 ;;
  57 ;; o  The code is less efficient that it could be - in a lot of places, I
  58 ;;    pull a 512-character string out of the buffer and parse it, when I could
  59 ;;    be parsing it in place, not garbaging a string.  Should redo that.
  60 ;;
  61 ;; o  I'd like a command that searches for a string/regexp in every subfile
  62 ;;    of an archive, where <esc> would leave you in a subfile-edit buffer.
  63 ;;    (Like the Meta-R command of the Zmacs mail reader.)
  64 ;;
  65 ;; o  Sometimes (but not always) reverting the tar-file buffer does not
  66 ;;    re-grind the listing, and you are staring at the binary tar data.
  67 ;;    Typing 'g' again immediately after that will always revert and re-grind
  68 ;;    it, though.  I have no idea why this happens.
  69 ;;
  70 ;; o  Tar-mode interacts poorly with crypt.el and zcat.el because the tar
  71 ;;    write-file-hook actually writes the file.  Instead it should remove the
  72 ;;    header (and conspire to put it back afterwards) so that other write-file
  73 ;;    hooks which frob the buffer have a chance to do their dirty work.  There
  74 ;;    might be a problem if the tar write-file-hook does not come *first* on
  75 ;;    the list.
  76 ;;
  77 ;; o  Block files, sparse files, continuation files, and the various header
  78 ;;    types aren't editable.  Actually I don't know that they work at all.
  79
  80 ;; Rationale:
  81
  82 ;; Why does tar-mode edit the file itself instead of using tar?
  83
  84 ;; That means that you can edit tar files which you don't have room for
  85 ;; on your local disk.
  86
  87 ;; I don't know about recent features in gnu tar, but old versions of tar
  88 ;; can't replace a file in the middle of a tar file with a new version.
  89 ;; Tar-mode can.  I don't think tar can do things like chmod the subfiles.
  90 ;; An implementation which involved unpacking and repacking the file into
  91 ;; some scratch directory would be very wasteful, and wouldn't be able to
  92 ;; preserve the file owners.
  93
  94 ;;; Code:
  95
  96 (defgroup tar nil
  97   "Simple editing of tar files."
  98   :prefix "tar-"
  99   :group 'data)
 100
 101 (defcustom tar-anal-blocksize 20
 102   "The blocksize of tar files written by Emacs, or nil, meaning don't care.
 103 The blocksize of a tar file is not really the size of the blocks; rather, it is
 104 the number of blocks written with one system call.  When tarring to a tape,
 105 this is the size of the *tape* blocks, but when writing to a file, it doesn't
 106 matter much.  The only noticeable difference is that if a tar file does not
 107 have a blocksize of 20, tar will tell you that; all this really controls is
 108 how many null padding bytes go on the end of the tar file."
 109   :type '(choice integer (const nil))
 110   :group 'tar)
 111
 112 (defcustom tar-update-datestamp nil
 113   "Non-nil means Tar mode should play fast and loose with sub-file datestamps.
 114 If this is true, then editing and saving a tar file entry back into its
 115 tar file will update its datestamp.  If false, the datestamp is unchanged.
 116 You may or may not want this - it is good in that you can tell when a file
 117 in a tar archive has been changed, but it is bad for the same reason that
 118 editing a file in the tar archive at all is bad - the changed version of
 119 the file never exists on disk."
 120   :type 'boolean
 121   :group 'tar)
 122
 123 (defcustom tar-mode-show-date nil
 124   "Non-nil means Tar mode should show the date/time of each subfile.
 125 This information is useful, but it takes screen space away from file names."
 126   :type 'boolean
 127   :group 'tar)
 128
 129 (defvar tar-parse-info nil)
 130 (defvar tar-header-offset nil)
 131 (defvar tar-superior-buffer nil)
 132 (defvar tar-superior-descriptor nil)
 133 (defvar tar-subfile-mode nil)
 134 (defvar tar-file-name-coding-system nil)
 135
 136 (put 'tar-parse-info 'permanent-local t)
 137 (put 'tar-header-offset 'permanent-local t)
 138 (put 'tar-superior-buffer 'permanent-local t)
 139 (put 'tar-superior-descriptor 'permanent-local t)
 140 (put 'tar-file-name-coding-system 'permanent-local t)
 141 \f
 142 (defmacro tar-setf (form val)
 143   "A mind-numbingly simple implementation of setf."
 144   (let ((mform (macroexpand form (and (boundp 'byte-compile-macro-environment)
 145                                       byte-compile-macro-environment))))
 146     (cond ((symbolp mform) (list 'setq mform val))
 147           ((not (consp mform)) (error "can't setf %s" form))
 148           ((eq (car mform) 'aref)
 149            (list 'aset (nth 1 mform) (nth 2 mform) val))
 150           ((eq (car mform) 'car)
 151            (list 'setcar (nth 1 mform) val))
 152           ((eq (car mform) 'cdr)
 153            (list 'setcdr (nth 1 mform) val))
 154           (t (error "don't know how to setf %s" form)))))
 155 \f
 156 ;;; down to business.
 157
 158 (defmacro make-tar-header (name mode uid git size date ck lt ln
 159                            magic uname gname devmaj devmin)
 160   (list 'vector name mode uid git size date ck lt ln
 161         magic uname gname devmaj devmin))
 162
 163 (defmacro tar-header-name (x) (list 'aref x 0))
 164 (defmacro tar-header-mode (x) (list 'aref x 1))
 165 (defmacro tar-header-uid  (x) (list 'aref x 2))
 166 (defmacro tar-header-gid  (x) (list 'aref x 3))
 167 (defmacro tar-header-size (x) (list 'aref x 4))
 168 (defmacro tar-header-date (x) (list 'aref x 5))
 169 (defmacro tar-header-checksum  (x) (list 'aref x 6))
 170 (defmacro tar-header-link-type (x) (list 'aref x 7))
 171 (defmacro tar-header-link-name (x) (list 'aref x 8))
 172 (defmacro tar-header-magic (x) (list 'aref x 9))
 173 (defmacro tar-header-uname (x) (list 'aref x 10))
 174 (defmacro tar-header-gname (x) (list 'aref x 11))
 175 (defmacro tar-header-dmaj (x) (list 'aref x 12))
 176 (defmacro tar-header-dmin (x) (list 'aref x 13))
 177
 178 (defmacro make-tar-desc (data-start tokens)
 179   (list 'cons data-start tokens))
 180
 181 (defmacro tar-desc-data-start (x) (list 'car x))
 182 (defmacro tar-desc-tokens     (x) (list 'cdr x))
 183
 184 (defconst tar-name-offset 0)
 185 (defconst tar-mode-offset (+ tar-name-offset 100))
 186 (defconst tar-uid-offset  (+ tar-mode-offset 8))
 187 (defconst tar-gid-offset  (+ tar-uid-offset 8))
 188 (defconst tar-size-offset (+ tar-gid-offset 8))
 189 (defconst tar-time-offset (+ tar-size-offset 12))
 190 (defconst tar-chk-offset  (+ tar-time-offset 12))
 191 (defconst tar-linkp-offset (+ tar-chk-offset 8))
 192 (defconst tar-link-offset (+ tar-linkp-offset 1))
 193 ;;; GNU-tar specific slots.
 194 (defconst tar-magic-offset (+ tar-link-offset 100))
 195 (defconst tar-uname-offset (+ tar-magic-offset 8))
 196 (defconst tar-gname-offset (+ tar-uname-offset 32))
 197 (defconst tar-dmaj-offset (+ tar-gname-offset 32))
 198 (defconst tar-dmin-offset (+ tar-dmaj-offset 8))
 199 (defconst tar-prefix-offset (+ tar-dmin-offset 8))
 200 (defconst tar-end-offset (+ tar-prefix-offset 155))
 201
 202 (defun tar-header-block-tokenize (string)
 203   "Return a `tar-header' structure.
 204 This is a list of name, mode, uid, gid, size,
 205 write-date, checksum, link-type, and link-name."
 206   (setq string (string-as-unibyte string))
 207   (cond ((< (length string) 512) nil)
 208         (;(some 'plusp string)           ; <-- oops, massive cycle hog!
 209          (or (not (= 0 (aref string 0))) ; This will do.
 210              (not (= 0 (aref string 101))))
 211          (let* ((name-end tar-mode-offset)
 212                 (link-end (1- tar-magic-offset))
 213                 (uname-end (1- tar-gname-offset))
 214                 (gname-end (1- tar-dmaj-offset))
 215                 (link-p (aref string tar-linkp-offset))
 216                 (magic-str (substring string tar-magic-offset (1- tar-uname-offset)))
 217                 (uname-valid-p (or (string= "ustar  " magic-str) (string= "GNUtar " magic-str)
 218                                    (string= "ustar\0000" magic-str)))
 219                 name linkname
 220                 (nulsexp   "[^\000]*\000"))
 221            (when (string-match nulsexp string tar-name-offset)
 222              (setq name-end (min name-end (1- (match-end 0)))))
 223            (when (string-match nulsexp string tar-link-offset)
 224              (setq link-end (min link-end (1- (match-end 0)))))
 225            (when (string-match nulsexp string tar-uname-offset)
 226              (setq uname-end (min uname-end (1- (match-end 0)))))
 227            (when (string-match nulsexp string tar-gname-offset)
 228              (setq gname-end (min gname-end (1- (match-end 0)))))
 229            (setq name (substring string tar-name-offset name-end)
 230                  link-p (if (or (= link-p 0) (= link-p ?0))
 231                             nil
 232                           (- link-p ?0)))
 233            (setq linkname (substring string tar-link-offset link-end))
 234            (when (and uname-valid-p
 235                       (string-match nulsexp string tar-prefix-offset)
 236                       (> (match-end 0) (1+ tar-prefix-offset)))
 237              (setq name (concat (substring string tar-prefix-offset
 238                                            (1- (match-end 0)))
 239                                 "/" name)))
 240            (if default-enable-multibyte-characters
 241                (setq name
 242                      (decode-coding-string name tar-file-name-coding-system)
 243                      linkname
 244                      (decode-coding-string linkname
 245                                            tar-file-name-coding-system)))
 246            (if (and (null link-p) (string-match "/\\'" name)) (setq link-p 5)) ; directory
 247            (make-tar-header
 248              name
 249              (tar-parse-octal-integer string tar-mode-offset tar-uid-offset)
 250              (tar-parse-octal-integer string tar-uid-offset tar-gid-offset)
 251              (tar-parse-octal-integer string tar-gid-offset tar-size-offset)
 252              (tar-parse-octal-integer string tar-size-offset tar-time-offset)
 253              (tar-parse-octal-long-integer string tar-time-offset tar-chk-offset)
 254              (tar-parse-octal-integer string tar-chk-offset tar-linkp-offset)
 255              link-p
 256              linkname
 257              uname-valid-p
 258              (and uname-valid-p (substring string tar-uname-offset uname-end))
 259              (and uname-valid-p (substring string tar-gname-offset gname-end))
 260              (tar-parse-octal-integer string tar-dmaj-offset tar-dmin-offset)
 261              (tar-parse-octal-integer string tar-dmin-offset tar-prefix-offset)
 262              )))
 263         (t 'empty-tar-block)))
 264
 265
 266 (defun tar-parse-octal-integer (string &optional start end)
 267   (if (null start) (setq start 0))
 268   (if (null end) (setq end (length string)))
 269   (if (= (aref string start) 0)
 270       0
 271     (let ((n 0))
 272       (while (< start end)
 273         (setq n (if (< (aref string start) ?0) n
 274                   (+ (* n 8) (- (aref string start) ?0)))
 275               start (1+ start)))
 276       n)))
 277
 278 (defun tar-parse-octal-long-integer (string &optional start end)
 279   (if (null start) (setq start 0))
 280   (if (null end) (setq end (length string)))
 281   (if (= (aref string start) 0)
 282       (list 0 0)
 283     (let ((lo 0)
 284           (hi 0))
 285       (while (< start end)
 286         (if (>= (aref string start) ?0)
 287             (setq lo (+ (* lo 8) (- (aref string start) ?0))
 288                   hi (+ (* hi 8) (ash lo -16))
 289                   lo (logand lo 65535)))
 290         (setq start (1+ start)))
 291       (list hi lo))))
 292
 293 (defun tar-parse-octal-integer-safe (string)
 294   (if (zerop (length string)) (error "empty string"))
 295   (mapc (lambda (c)
 296           (if (or (< c ?0) (> c ?7))
 297               (error "`%c' is not an octal digit" c)))
 298         string)
 299   (tar-parse-octal-integer string))
 300
 301
 302 (defun tar-header-block-checksum (string)
 303   "Compute and return a tar-acceptable checksum for this block."
 304   (setq string (string-as-unibyte string))
 305   (let* ((chk-field-start tar-chk-offset)
 306          (chk-field-end (+ chk-field-start 8))
 307          (sum 0)
 308          (i 0))
 309     ;; Add up all of the characters except the ones in the checksum field.
 310     ;; Add that field as if it were filled with spaces.
 311     (while (< i chk-field-start)
 312       (setq sum (+ sum (aref string i))
 313             i (1+ i)))
 314     (setq i chk-field-end)
 315     (while (< i 512)
 316       (setq sum (+ sum (aref string i))
 317             i (1+ i)))
 318     (+ sum (* 32 8))))
 319
 320 (defun tar-header-block-check-checksum (hblock desired-checksum file-name)
 321   "Beep and print a warning if the checksum doesn't match."
 322   (if (not (= desired-checksum (tar-header-block-checksum hblock)))
 323       (progn (beep) (message "Invalid checksum for file %s!" file-name))))
 324
 325 (defun tar-clip-time-string (time)
 326   (let ((str (current-time-string time)))
 327     (concat " " (substring str 4 16) (substring str 19 24))))
 328
 329 (defun tar-grind-file-mode (mode)
 330   "Construct a `-rw--r--r--' string indicating MODE.
 331 MODE should be an integer which is a file mode value."
 332   (string
 333    (if (zerop (logand 256 mode)) ?- ?r)
 334    (if (zerop (logand 128 mode)) ?- ?w)
 335    (if (zerop (logand 1024 mode)) (if (zerop (logand  64 mode)) ?- ?x) ?s)
 336    (if (zerop (logand  32 mode)) ?- ?r)
 337    (if (zerop (logand  16 mode)) ?- ?w)
 338    (if (zerop (logand 2048 mode)) (if (zerop (logand   8 mode)) ?- ?x) ?s)
 339    (if (zerop (logand   4 mode)) ?- ?r)
 340    (if (zerop (logand   2 mode)) ?- ?w)
 341    (if (zerop (logand   1 mode)) ?- ?x)))
 342
 343 (defun tar-header-block-summarize (tar-hblock &optional mod-p)
 344   "Return a line similar to the output of `tar -vtf'."
 345   (let ((name (tar-header-name tar-hblock))
 346         (mode (tar-header-mode tar-hblock))
 347         (uid (tar-header-uid tar-hblock))
 348         (gid (tar-header-gid tar-hblock))
 349         (uname (tar-header-uname tar-hblock))
 350         (gname (tar-header-gname tar-hblock))
 351         (size (tar-header-size tar-hblock))
 352         (time (tar-header-date tar-hblock))
 353         ;; (ck (tar-header-checksum tar-hblock))
 354         (type (tar-header-link-type tar-hblock))
 355         (link-name (tar-header-link-name tar-hblock)))
 356     (format "%c%c%s%8s/%-8s%7s%s %s%s"
 357             (if mod-p ?* ? )
 358             (cond ((or (eq type nil) (eq type 0)) ?-)
 359                   ((eq type 1) ?h)      ; link
 360                   ((eq type 2) ?l)      ; symlink
 361                   ((eq type 3) ?c)      ; char special
 362                   ((eq type 4) ?b)      ; block special
 363                   ((eq type 5) ?d)      ; directory
 364                   ((eq type 6) ?p)      ; FIFO/pipe
 365                   ((eq type 20) ?*)     ; directory listing
 366                   ((eq type 28) ?L)     ; next has longname
 367                   ((eq type 29) ?M)     ; multivolume continuation
 368                   ((eq type 35) ?S)     ; sparse
 369                   ((eq type 38) ?V)     ; volume header
 370                   ((eq type 55) ?H)     ; extended pax header
 371                   (t ?\s)
 372                   )
 373             (tar-grind-file-mode mode)
 374             (if (= 0 (length uname)) uid uname)
 375             (if (= 0 (length gname)) gid gname)
 376             size
 377             (if tar-mode-show-date (tar-clip-time-string time) "")
 378             (propertize name
 379                         'mouse-face 'highlight
 380                         'help-echo "mouse-2: extract this file into a buffer")
 381             (if (or (eq type 1) (eq type 2))
 382                 (concat (if (= type 1) " ==> " " --> ") link-name)
 383               ""))))
 384
 385 (defun tar-untar-buffer ()
 386   "Extract all archive members in the tar-file into the current directory."
 387   (interactive)
 388   (let ((multibyte enable-multibyte-characters))
 389     (unwind-protect
 390         (save-restriction
 391           (widen)
 392           (set-buffer-multibyte nil)
 393           (dolist (descriptor tar-parse-info)
 394             (let* ((tokens (tar-desc-tokens descriptor))
 395                    (name (tar-header-name tokens))
 396                    (dir (if (eq (tar-header-link-type tokens) 5)
 397                             name
 398                           (file-name-directory name)))
 399                    (start (+ (tar-desc-data-start descriptor)
 400                              (- tar-header-offset (point-min))))
 401                    (end (+ start (tar-header-size tokens))))
 402               (unless (file-directory-p name)
 403                 (message "Extracting %s" name)
 404                 (if (and dir (not (file-exists-p dir)))
 405                     (make-directory dir t))
 406                 (unless (file-directory-p name)
 407                   (write-region start end name))
 408                 (set-file-modes name (tar-header-mode tokens))))))
 409       (if multibyte
 410           (set-buffer-multibyte 'to)))))
 411
 412 (defun tar-summarize-buffer ()
 413   "Parse the contents of the tar file in the current buffer.
 414 Place a dired-like listing on the front;
 415 then narrow to it, so that only that listing
 416 is visible (and the real data of the buffer is hidden)."
 417   (let ((modified (buffer-modified-p)))
 418     (set-buffer-multibyte nil)
 419     (let* ((result '())
 420            (pos (point-min))
 421            (progress-reporter
 422             (make-progress-reporter "Parsing tar file..."
 423                                     (point-min) (max 1 (- (buffer-size) 1024))))
 424            tokens)
 425       (while (and (<= (+ pos 512) (point-max))
 426                   (not (eq 'empty-tar-block
 427                            (setq tokens
 428                                  (tar-header-block-tokenize
 429                                   (buffer-substring pos (+ pos 512)))))))
 430         (setq pos (+ pos 512))
 431         (progress-reporter-update progress-reporter pos)
 432         (if (memq (tar-header-link-type tokens) '(20 55))
 433             ;; Foo.  There's an extra empty block after these.
 434             (setq pos (+ pos 512)))
 435         (let ((size (tar-header-size tokens)))
 436           (if (< size 0)
 437               (error "%s has size %s - corrupted"
 438                      (tar-header-name tokens) size))
 439           ;;
 440           ;; This is just too slow.  Don't really need it anyway....
 441           ;;(tar-header-block-check-checksum
 442           ;;  hblock (tar-header-block-checksum hblock)
 443           ;;  (tar-header-name tokens))
 444
 445           (push (make-tar-desc pos tokens) result)
 446
 447           (and (null (tar-header-link-type tokens))
 448                (> size 0)
 449                (setq pos
 450                      (+ pos 512 (ash (ash (1- size) -9) 9)) ; this works
 451                      ;;(+ pos (+ size (- 512 (rem (1- size) 512)))) ; this doesn't
 452                      ))))
 453       (make-local-variable 'tar-parse-info)
 454       (setq tar-parse-info (nreverse result))
 455       ;; A tar file should end with a block or two of nulls,
 456       ;; but let's not get a fatal error if it doesn't.
 457       (if (eq tokens 'empty-tar-block)
 458           (progress-reporter-done progress-reporter)
 459         (message "Warning: premature EOF parsing tar file")))
 460     ;; Obey the user's preference for the use of uni/multibytes.
 461     (if default-enable-multibyte-characters
 462         (set-buffer-multibyte 'to))
 463     (goto-char (point-min))
 464     (let ((inhibit-read-only t)
 465           ;; Collect summary lines and insert them all at once since tar files
 466           ;; can be pretty big.
 467           (total-summaries
 468            (mapconcat
 469             (lambda (tar-desc)
 470               (tar-header-block-summarize (tar-desc-tokens tar-desc)))
 471             tar-parse-info
 472             "\n")))
 473       (insert total-summaries "\n"))
 474     (narrow-to-region (point-min) (point))
 475     (set (make-local-variable 'tar-header-offset) (position-bytes (point)))
 476     (goto-char (point-min))
 477     (restore-buffer-modified-p modified)))
 478 \f
 479 (defvar tar-mode-map
 480   (let ((map (make-keymap)))
 481     (suppress-keymap map)
 482     (define-key map " " 'tar-next-line)
 483     (define-key map "C" 'tar-copy)
 484     (define-key map "d" 'tar-flag-deleted)
 485     (define-key map "\^D" 'tar-flag-deleted)
 486     (define-key map "e" 'tar-extract)
 487     (define-key map "f" 'tar-extract)
 488     (define-key map "\C-m" 'tar-extract)
 489     (define-key map [mouse-2] 'tar-mouse-extract)
 490     (define-key map "g" 'revert-buffer)
 491     (define-key map "h" 'describe-mode)
 492     (define-key map "n" 'tar-next-line)
 493     (define-key map "\^N" 'tar-next-line)
 494     (define-key map [down] 'tar-next-line)
 495     (define-key map "o" 'tar-extract-other-window)
 496     (define-key map "p" 'tar-previous-line)
 497     (define-key map "q" 'quit-window)
 498     (define-key map "\^P" 'tar-previous-line)
 499     (define-key map [up] 'tar-previous-line)
 500     (define-key map "R" 'tar-rename-entry)
 501     (define-key map "u" 'tar-unflag)
 502     (define-key map "v" 'tar-view)
 503     (define-key map "x" 'tar-expunge)
 504     (define-key map "\177" 'tar-unflag-backwards)
 505     (define-key map "E" 'tar-extract-other-window)
 506     (define-key map "M" 'tar-chmod-entry)
 507     (define-key map "G" 'tar-chgrp-entry)
 508     (define-key map "O" 'tar-chown-entry)
 509     ;; Let mouse-1 follow the link.
 510     (define-key map [follow-link] 'mouse-face)
 511
 512     ;; Make menu bar items.
 513
 514     ;; Get rid of the Edit menu bar item to save space.
 515     (define-key map [menu-bar edit] 'undefined)
 516
 517     (define-key map [menu-bar immediate]
 518       (cons "Immediate" (make-sparse-keymap "Immediate")))
 519
 520     (define-key map [menu-bar immediate view]
 521       '("View This File" . tar-view))
 522     (define-key map [menu-bar immediate display]
 523       '("Display in Other Window" . tar-display-other-window))
 524     (define-key map [menu-bar immediate find-file-other-window]
 525       '("Find in Other Window" . tar-extract-other-window))
 526     (define-key map [menu-bar immediate find-file]
 527       '("Find This File" . tar-extract))
 528
 529     (define-key map [menu-bar mark]
 530       (cons "Mark" (make-sparse-keymap "Mark")))
 531
 532     (define-key map [menu-bar mark unmark-all]
 533       '("Unmark All" . tar-clear-modification-flags))
 534     (define-key map [menu-bar mark deletion]
 535       '("Flag" . tar-flag-deleted))
 536     (define-key map [menu-bar mark unmark]
 537       '("Unflag" . tar-unflag))
 538
 539     (define-key map [menu-bar operate]
 540       (cons "Operate" (make-sparse-keymap "Operate")))
 541
 542     (define-key map [menu-bar operate chown]
 543       '("Change Owner..." . tar-chown-entry))
 544     (define-key map [menu-bar operate chgrp]
 545       '("Change Group..." . tar-chgrp-entry))
 546     (define-key map [menu-bar operate chmod]
 547       '("Change Mode..." . tar-chmod-entry))
 548     (define-key map [menu-bar operate rename]
 549       '("Rename to..." . tar-rename-entry))
 550     (define-key map [menu-bar operate copy]
 551       '("Copy to..." . tar-copy))
 552     (define-key map [menu-bar operate expunge]
 553       '("Expunge Marked Files" . tar-expunge))
 554     \f
 555     map)
 556   "Local keymap for Tar mode listings.")
 557
 558 \f
 559 ;; tar mode is suitable only for specially formatted data.
 560 (put 'tar-mode 'mode-class 'special)
 561 (put 'tar-subfile-mode 'mode-class 'special)
 562
 563 ;;;###autoload
 564 (define-derived-mode tar-mode nil "Tar"
 565   "Major mode for viewing a tar file as a dired-like listing of its contents.
 566 You can move around using the usual cursor motion commands.
 567 Letters no longer insert themselves.
 568 Type `e' to pull a file out of the tar file and into its own buffer;
 569 or click mouse-2 on the file's line in the Tar mode buffer.
 570 Type `c' to copy an entry from the tar file into another file on disk.
 571
 572 If you edit a sub-file of this archive (as with the `e' command) and
 573 save it with \\[save-buffer], the contents of that buffer will be
 574 saved back into the tar-file buffer; in this way you can edit a file
 575 inside of a tar archive without extracting it and re-archiving it.
 576
 577 See also: variables `tar-update-datestamp' and `tar-anal-blocksize'.
 578 \\{tar-mode-map}"
 579   ;; this is not interactive because you shouldn't be turning this
 580   ;; mode on and off.  You can corrupt things that way.
 581   ;; rms: with permanent locals, it should now be possible to make this work
 582   ;; interactively in some reasonable fashion.
 583   (make-local-variable 'tar-header-offset)
 584   (make-local-variable 'tar-parse-info)
 585   (set (make-local-variable 'require-final-newline) nil) ; binary data, dude...
 586   (set (make-local-variable 'revert-buffer-function) 'tar-mode-revert)
 587   (set (make-local-variable 'local-enable-local-variables) nil)
 588   (set (make-local-variable 'next-line-add-newlines) nil)
 589   (set (make-local-variable 'tar-file-name-coding-system)
 590        (or file-name-coding-system
 591            default-file-name-coding-system
 592            locale-coding-system))
 593   ;; Prevent loss of data when saving the file.
 594   (set (make-local-variable 'file-precious-flag) t)
 595   (auto-save-mode 0)
 596   (set (make-local-variable 'write-contents-functions) '(tar-mode-write-file))
 597   (buffer-disable-undo)
 598   (widen)
 599   (if (and (boundp 'tar-header-offset) tar-header-offset)
 600       (narrow-to-region (point-min) tar-header-offset)
 601     (tar-summarize-buffer)
 602     (tar-next-line 0)))
 603
 604
 605 (defun tar-subfile-mode (p)
 606   "Minor mode for editing an element of a tar-file.
 607 This mode arranges for \"saving\" this buffer to write the data
 608 into the tar-file buffer that it came from.  The changes will actually
 609 appear on disk when you save the tar-file's buffer."
 610   (interactive "P")
 611   (or (and (boundp 'tar-superior-buffer) tar-superior-buffer)
 612       (error "This buffer is not an element of a tar file"))
 613   ;; Don't do this, because it is redundant and wastes mode line space.
 614   ;;  (or (assq 'tar-subfile-mode minor-mode-alist)
 615   ;;      (setq minor-mode-alist (append minor-mode-alist
 616   ;;                                 (list '(tar-subfile-mode " TarFile")))))
 617   (make-local-variable 'tar-subfile-mode)
 618   (setq tar-subfile-mode
 619         (if (null p)
 620             (not tar-subfile-mode)
 621             (> (prefix-numeric-value p) 0)))
 622   (cond (tar-subfile-mode
 623          (add-hook 'write-file-functions 'tar-subfile-save-buffer nil t)
 624          ;; turn off auto-save.
 625          (auto-save-mode -1)
 626          (setq buffer-auto-save-file-name nil)
 627          (run-hooks 'tar-subfile-mode-hook))
 628         (t
 629          (remove-hook 'write-file-functions 'tar-subfile-save-buffer t))))
 630
 631
 632 ;; Revert the buffer and recompute the dired-like listing.
 633 (defun tar-mode-revert (&optional no-auto-save no-confirm)
 634   (let ((revert-buffer-function nil)
 635         (old-offset tar-header-offset)
 636         success)
 637     (setq tar-header-offset nil)
 638     (unwind-protect
 639         (and (revert-buffer t no-confirm)
 640              (progn (widen)
 641                     (setq success t)
 642                     (tar-mode)))
 643       ;; If the revert was canceled,
 644       ;; put back the old value of tar-header-offset.
 645       (or success
 646           (setq tar-header-offset old-offset)))))
 647
 648
 649 (defun tar-next-line (arg)
 650   "Move cursor vertically down ARG lines and to the start of the filename."
 651   (interactive "p")
 652   (forward-line arg)
 653   (if (eobp) nil (forward-char (if tar-mode-show-date 54 36))))
 654
 655 (defun tar-previous-line (arg)
 656   "Move cursor vertically up ARG lines and to the start of the filename."
 657   (interactive "p")
 658   (tar-next-line (- arg)))
 659
 660 (defun tar-current-descriptor (&optional noerror)
 661   "Return the tar-descriptor of the current line, or signals an error."
 662   ;; I wish lines had plists, like in ZMACS...
 663   (or (nth (count-lines (point-min)
 664                         (save-excursion (beginning-of-line) (point)))
 665            tar-parse-info)
 666       (if noerror
 667           nil
 668           (error "This line does not describe a tar-file entry"))))
 669
 670 (defun tar-get-descriptor ()
 671   (let* ((descriptor (tar-current-descriptor))
 672          (tokens (tar-desc-tokens descriptor))
 673          (size (tar-header-size tokens))
 674          (link-p (tar-header-link-type tokens)))
 675     (if link-p
 676         (error "This is %s, not a real file"
 677                (cond ((eq link-p 5) "a directory")
 678                      ((eq link-p 20) "a tar directory header")
 679                      ((eq link-p 28) "a next has longname")
 680                      ((eq link-p 29) "a multivolume-continuation")
 681                      ((eq link-p 35) "a sparse entry")
 682                      ((eq link-p 38) "a volume header")
 683                      ((eq link-p 55) "an extended pax header")
 684                      (t "a link"))))
 685     (if (zerop size) (message "This is a zero-length file"))
 686     descriptor))
 687
 688 (defun tar-mouse-extract (event)
 689   "Extract a file whose tar directory line you click on."
 690   (interactive "e")
 691   (with-current-buffer (window-buffer (posn-window (event-end event)))
 692     (save-excursion
 693       (goto-char (posn-point (event-end event)))
 694       ;; Just make sure this doesn't get an error.
 695       (tar-get-descriptor)))
 696   (select-window (posn-window (event-end event)))
 697   (goto-char (posn-point (event-end event)))
 698   (tar-extract))
 699
 700 (defun tar-file-name-handler (op &rest args)
 701   "Helper function for `tar-extract'."
 702   (or (eq op 'file-exists-p)
 703       (let ((file-name-handler-alist nil))
 704         (apply op args))))
 705
 706 (defun tar-extract (&optional other-window-p)
 707   "In Tar mode, extract this entry of the tar file into its own buffer."
 708   (interactive)
 709   (let* ((view-p (eq other-window-p 'view))
 710          (descriptor (tar-get-descriptor))
 711          (tokens (tar-desc-tokens descriptor))
 712          (name (tar-header-name tokens))
 713          (size (tar-header-size tokens))
 714          (start (+ (tar-desc-data-start descriptor)
 715                    (- tar-header-offset (point-min))))
 716          (end (+ start size)))
 717     (let* ((tar-buffer (current-buffer))
 718            (tarname (buffer-name))
 719            (bufname (concat (file-name-nondirectory name)
 720                             " ("
 721                              tarname
 722                              ")"))
 723            (read-only-p (or buffer-read-only view-p))
 724            (new-buffer-file-name (expand-file-name
 725                                   ;; `:' is not allowed on Windows
 726                                   (concat tarname "!" name)))
 727            (buffer (get-file-buffer new-buffer-file-name))
 728            (just-created nil)
 729            (pos (point))
 730            undo-list)
 731       (unless buffer
 732         (setq buffer (generate-new-buffer bufname))
 733         (with-current-buffer buffer
 734           (setq undo-list buffer-undo-list
 735                 buffer-undo-list t))
 736         (setq bufname (buffer-name buffer))
 737         (setq just-created t)
 738         (unwind-protect
 739             (let (coding)
 740               (narrow-to-region start end)
 741               (goto-char start)
 742               (setq coding (or coding-system-for-read
 743                                (and set-auto-coding-function
 744                                     (funcall set-auto-coding-function
 745                                              name (- end start)))
 746                                ;; The following binding causes
 747                                ;; find-buffer-file-type-coding-system
 748                                ;; (defined on dos-w32.el) to act as if
 749                                ;; the file being extracted existed, so
 750                                ;; that the file's contents' encoding and
 751                                ;; EOL format are auto-detected.
 752                                (let ((file-name-handler-alist
 753                                       '(("" . tar-file-name-handler))))
 754                                  (car (find-operation-coding-system
 755                                        'insert-file-contents
 756                                        (cons name (current-buffer)) t)))))
 757               (if (or (not coding)
 758                       (eq (coding-system-type coding) 'undecided))
 759                   (setq coding (detect-coding-region start end t)))
 760               (if (and default-enable-multibyte-characters
 761                        (coding-system-get coding :for-unibyte))
 762                   (with-current-buffer buffer
 763                     (set-buffer-multibyte nil)))
 764               (widen)
 765               (decode-coding-region start end coding buffer)
 766               (with-current-buffer buffer
 767                 (goto-char (point-min))
 768                 (setq buffer-file-name new-buffer-file-name)
 769                 (setq buffer-file-truename
 770                       (abbreviate-file-name buffer-file-name))
 771                 ;; Force buffer-file-coding-system to what
 772                 ;; decode-coding-region actually used.
 773                 (set-buffer-file-coding-system last-coding-system-used t)
 774                 ;; Set the default-directory to the dir of the
 775                 ;; superior buffer.
 776                 (setq default-directory
 777                       (with-current-buffer tar-buffer
 778                         default-directory))
 779                 (normal-mode)  ; pick a mode.
 780                 (rename-buffer bufname)
 781                 (make-local-variable 'tar-superior-buffer)
 782                 (make-local-variable 'tar-superior-descriptor)
 783                 (setq tar-superior-buffer tar-buffer)
 784                 (setq tar-superior-descriptor descriptor)
 785                 (setq buffer-read-only read-only-p)
 786                 (set-buffer-modified-p nil)
 787                 (setq buffer-undo-list undo-list)
 788                 (tar-subfile-mode 1))
 789               (set-buffer tar-buffer))
 790           (narrow-to-region (point-min) tar-header-offset)
 791           (goto-char pos)))
 792       (if view-p
 793           (view-buffer
 794            buffer (and just-created 'kill-buffer-if-not-modified))
 795         (if (eq other-window-p 'display)
 796             (display-buffer buffer)
 797           (if other-window-p
 798               (switch-to-buffer-other-window buffer)
 799             (switch-to-buffer buffer)))))))
 800
 801
 802 (defun tar-extract-other-window ()
 803   "In Tar mode, find this entry of the tar file in another window."
 804   (interactive)
 805   (tar-extract t))
 806
 807 (defun tar-display-other-window ()
 808   "In Tar mode, display this entry of the tar file in another window."
 809   (interactive)
 810   (tar-extract 'display))
 811
 812 (defun tar-view ()
 813   "In Tar mode, view the tar file entry on this line."
 814   (interactive)
 815   (tar-extract 'view))
 816
 817
 818 (defun tar-read-file-name (&optional prompt)
 819   "Read a file name with this line's entry as the default."
 820   (or prompt (setq prompt "Copy to: "))
 821   (let* ((default-file (expand-file-name
 822                         (tar-header-name (tar-desc-tokens
 823                                           (tar-current-descriptor)))))
 824          (target (expand-file-name
 825                   (read-file-name prompt
 826                                   (file-name-directory default-file)
 827                                   default-file nil))))
 828     (if (or (string= "" (file-name-nondirectory target))
 829             (file-directory-p target))
 830         (setq target (concat (if (string-match "/$" target)
 831                                  (substring target 0 (1- (match-end 0)))
 832                                  target)
 833                              "/"
 834                              (file-name-nondirectory default-file))))
 835     target))
 836
 837
 838 (defun tar-copy (&optional to-file)
 839   "In Tar mode, extract this entry of the tar file into a file on disk.
 840 If TO-FILE is not supplied, it is prompted for, defaulting to the name of
 841 the current tar-entry."
 842   (interactive (list (tar-read-file-name)))
 843   (let* ((descriptor (tar-get-descriptor))
 844          (tokens (tar-desc-tokens descriptor))
 845          (name (tar-header-name tokens))
 846          (size (tar-header-size tokens))
 847          (start (+ (tar-desc-data-start descriptor)
 848                    (- tar-header-offset (point-min))))
 849          (end (+ start size))
 850          (inhibit-file-name-handlers inhibit-file-name-handlers)
 851          (inhibit-file-name-operation inhibit-file-name-operation))
 852     (save-restriction
 853       (widen)
 854       ;; Inhibit compressing a subfile again if *both* name and
 855       ;; to-file are handled by jka-compr
 856       (if (and (eq (find-file-name-handler name 'write-region) 'jka-compr-handler)
 857                (eq (find-file-name-handler to-file 'write-region) 'jka-compr-handler))
 858           (setq inhibit-file-name-handlers
 859                 (cons 'jka-compr-handler
 860                       (and (eq inhibit-file-name-operation 'write-region)
 861                            inhibit-file-name-handlers))
 862                 inhibit-file-name-operation 'write-region))
 863       (let ((coding-system-for-write 'no-conversion))
 864         (write-region start end to-file nil nil nil t)))
 865     (message "Copied tar entry %s to %s" name to-file)))
 866
 867 (defun tar-flag-deleted (p &optional unflag)
 868   "In Tar mode, mark this sub-file to be deleted from the tar file.
 869 With a prefix argument, mark that many files."
 870   (interactive "p")
 871   (beginning-of-line)
 872   (dotimes (i (abs p))
 873     (if (tar-current-descriptor unflag) ; barf if we're not on an entry-line.
 874         (progn
 875           (delete-char 1)
 876           (insert (if unflag " " "D"))))
 877     (forward-line (if (< p 0) -1 1)))
 878   (if (eobp) nil (forward-char 36)))
 879
 880 (defun tar-unflag (p)
 881   "In Tar mode, un-mark this sub-file if it is marked to be deleted.
 882 With a prefix argument, un-mark that many files forward."
 883   (interactive "p")
 884   (tar-flag-deleted p t))
 885
 886 (defun tar-unflag-backwards (p)
 887   "In Tar mode, un-mark this sub-file if it is marked to be deleted.
 888 With a prefix argument, un-mark that many files backward."
 889   (interactive "p")
 890   (tar-flag-deleted (- p) t))
 891
 892
 893 (defun tar-expunge-internal ()
 894   "Expunge the tar-entry specified by the current line."
 895   (let* ((descriptor (tar-current-descriptor))
 896          (tokens (tar-desc-tokens descriptor))
 897          ;; (line (tar-desc-data-start descriptor))
 898          (name (tar-header-name tokens))
 899          (size (tar-header-size tokens))
 900          (link-p (tar-header-link-type tokens))
 901          (start (tar-desc-data-start descriptor))
 902          (following-descs (cdr (memq descriptor tar-parse-info))))
 903     (if link-p (setq size 0)) ; size lies for hard-links.
 904     ;;
 905     ;; delete the current line...
 906     (beginning-of-line)
 907     (let ((line-start (point)))
 908       (end-of-line) (forward-char)
 909       ;; decrement the header-pointer to be in sync...
 910       (setq tar-header-offset (- tar-header-offset (- (point) line-start)))
 911       (delete-region line-start (point)))
 912     ;;
 913     ;; delete the data pointer...
 914     (setq tar-parse-info (delq descriptor tar-parse-info))
 915     ;;
 916     ;; delete the data from inside the file...
 917     (widen)
 918     (let* ((data-start (+ start (- tar-header-offset (point-min)) -512))
 919            (data-end (+ data-start 512 (ash (ash (+ size 511) -9) 9))))
 920       (delete-region data-start data-end)
 921       ;;
 922       ;; and finally, decrement the start-pointers of all following
 923       ;; entries in the archive.  This is a pig when deleting a bunch
 924       ;; of files at once - we could optimize this to only do the
 925       ;; iteration over the files that remain, or only iterate up to
 926       ;; the next file to be deleted.
 927       (let ((data-length (- data-end data-start)))
 928         (dolist (desc following-descs)
 929           (tar-setf (tar-desc-data-start desc)
 930                     (- (tar-desc-data-start desc) data-length))))
 931       ))
 932   (narrow-to-region (point-min) tar-header-offset))
 933
 934
 935 (defun tar-expunge (&optional noconfirm)
 936   "In Tar mode, delete all the archived files flagged for deletion.
 937 This does not modify the disk image; you must save the tar file itself
 938 for this to be permanent."
 939   (interactive)
 940   (if (or noconfirm
 941           (y-or-n-p "Expunge files marked for deletion? "))
 942       (let ((n 0))
 943         (save-excursion
 944           (goto-char (point-min))
 945           (while (not (eobp))
 946             (if (looking-at "D")
 947                 (progn (tar-expunge-internal)
 948                        (setq n (1+ n)))
 949                 (forward-line 1)))
 950           ;; after doing the deletions, add any padding that may be necessary.
 951           (tar-pad-to-blocksize)
 952           (narrow-to-region (point-min) tar-header-offset))
 953         (if (zerop n)
 954             (message "Nothing to expunge.")
 955             (message "%s files expunged.  Be sure to save this buffer." n)))))
 956
 957
 958 (defun tar-clear-modification-flags ()
 959   "Remove the stars at the beginning of each line."
 960   (interactive)
 961   (save-excursion
 962     (goto-char (point-min))
 963     (while (< (point) tar-header-offset)
 964       (if (not (eq (following-char) ?\s))
 965           (progn (delete-char 1) (insert " ")))
 966       (forward-line 1))))
 967
 968
 969 (defun tar-chown-entry (new-uid)
 970   "Change the user-id associated with this entry in the tar file.
 971 If this tar file was written by GNU tar, then you will be able to edit
 972 the user id as a string; otherwise, you must edit it as a number.
 973 You can force editing as a number by calling this with a prefix arg.
 974 This does not modify the disk image; you must save the tar file itself
 975 for this to be permanent."
 976   (interactive (list
 977                  (let ((tokens (tar-desc-tokens (tar-current-descriptor))))
 978                    (if (or current-prefix-arg
 979                            (not (tar-header-magic tokens)))
 980                        (let (n)
 981                          (while (not (numberp (setq n (read-minibuffer
 982                                                         "New UID number: "
 983                                                         (format "%s" (tar-header-uid tokens)))))))
 984                          n)
 985                        (read-string "New UID string: " (tar-header-uname tokens))))))
 986   (cond ((stringp new-uid)
 987          (tar-setf (tar-header-uname (tar-desc-tokens (tar-current-descriptor)))
 988                    new-uid)
 989          (tar-alter-one-field tar-uname-offset (concat new-uid "\000")))
 990         (t
 991          (tar-setf (tar-header-uid (tar-desc-tokens (tar-current-descriptor)))
 992                    new-uid)
 993          (tar-alter-one-field tar-uid-offset
 994            (concat (substring (format "%6o" new-uid) 0 6) "\000 ")))))
 995
 996
 997 (defun tar-chgrp-entry (new-gid)
 998   "Change the group-id associated with this entry in the tar file.
 999 If this tar file was written by GNU tar, then you will be able to edit
1000 the group id as a string; otherwise, you must edit it as a number.
1001 You can force editing as a number by calling this with a prefix arg.
1002 This does not modify the disk image; you must save the tar file itself
1003 for this to be permanent."
1004   (interactive (list
1005                  (let ((tokens (tar-desc-tokens (tar-current-descriptor))))
1006                    (if (or current-prefix-arg
1007                            (not (tar-header-magic tokens)))
1008                        (let (n)
1009                          (while (not (numberp (setq n (read-minibuffer
1010                                                         "New GID number: "
1011                                                         (format "%s" (tar-header-gid tokens)))))))
1012                          n)
1013                        (read-string "New GID string: " (tar-header-gname tokens))))))
1014   (cond ((stringp new-gid)
1015          (tar-setf (tar-header-gname (tar-desc-tokens (tar-current-descriptor)))
1016                    new-gid)
1017          (tar-alter-one-field tar-gname-offset
1018            (concat new-gid "\000")))
1019         (t
1020          (tar-setf (tar-header-gid (tar-desc-tokens (tar-current-descriptor)))
1021                    new-gid)
1022          (tar-alter-one-field tar-gid-offset
1023            (concat (substring (format "%6o" new-gid) 0 6) "\000 ")))))
1024
1025 (defun tar-rename-entry (new-name)
1026   "Change the name associated with this entry in the tar file.
1027 This does not modify the disk image; you must save the tar file itself
1028 for this to be permanent."
1029   (interactive
1030     (list (read-string "New name: "
1031             (tar-header-name (tar-desc-tokens (tar-current-descriptor))))))
1032   (if (string= "" new-name) (error "zero length name"))
1033   (let ((encoded-new-name (encode-coding-string new-name
1034                                                 tar-file-name-coding-system)))
1035     (if (> (length encoded-new-name) 98) (error "name too long"))
1036     (tar-setf (tar-header-name (tar-desc-tokens (tar-current-descriptor)))
1037               new-name)
1038     (tar-alter-one-field 0
1039      (substring (concat encoded-new-name (make-string 99 0)) 0 99))))
1040
1041
1042 (defun tar-chmod-entry (new-mode)
1043   "Change the protection bits associated with this entry in the tar file.
1044 This does not modify the disk image; you must save the tar file itself
1045 for this to be permanent."
1046   (interactive (list (tar-parse-octal-integer-safe
1047                        (read-string "New protection (octal): "))))
1048   (tar-setf (tar-header-mode (tar-desc-tokens (tar-current-descriptor)))
1049             new-mode)
1050   (tar-alter-one-field tar-mode-offset
1051     (concat (substring (format "%6o" new-mode) 0 6) "\000 ")))
1052
1053
1054 (defun tar-alter-one-field (data-position new-data-string)
1055   (let* ((descriptor (tar-current-descriptor))
1056          (tokens (tar-desc-tokens descriptor)))
1057     (unwind-protect
1058         (save-excursion
1059           ;;
1060           ;; update the header-line.
1061           (beginning-of-line)
1062           (let ((p (point)))
1063             (forward-line 1)
1064             (delete-region p (point))
1065             (insert (tar-header-block-summarize tokens) "\n")
1066             (setq tar-header-offset (point-max)))
1067
1068           (widen)
1069           (let* ((start (+ (tar-desc-data-start descriptor)
1070                            (- tar-header-offset (point-min))
1071                            -512)))
1072             ;;
1073             ;; delete the old field and insert a new one.
1074             (goto-char (+ start data-position))
1075             (delete-region (point) (+ (point) (length new-data-string))) ; <--
1076
1077             ;; As new-data-string is unibyte, just inserting it will
1078             ;; make eight-bit chars to the corresponding multibyte
1079             ;; chars.  This avoid that conversion, i.e., eight-bit
1080             ;; chars are converted to multibyte form of eight-bit
1081             ;; chars.
1082             (insert (string-to-multibyte new-data-string))
1083             ;;
1084             ;; compute a new checksum and insert it.
1085             (let ((chk (tar-header-block-checksum
1086                         (buffer-substring start (+ start 512)))))
1087               (goto-char (+ start tar-chk-offset))
1088               (delete-region (point) (+ (point) 8))
1089               (insert (format "%6o" chk))
1090               (insert 0)
1091               (insert ? )
1092               (tar-setf (tar-header-checksum tokens) chk)
1093               ;;
1094               ;; ok, make sure we didn't botch it.
1095               (tar-header-block-check-checksum
1096                 (buffer-substring start (+ start 512))
1097                 chk (tar-header-name tokens))
1098               )))
1099       (narrow-to-region (point-min) tar-header-offset)
1100       (tar-next-line 0))))
1101
1102
1103 (defun tar-octal-time (timeval)
1104   ;; Format a timestamp as 11 octal digits.  Ghod, I hope this works...
1105   (let ((hibits (car timeval)) (lobits (car (cdr timeval))))
1106     (format "%05o%01o%05o"
1107             (lsh hibits -2)
1108             (logior (lsh (logand 3 hibits) 1)
1109                     (if (> (logand lobits 32768) 0) 1 0))
1110             (logand 32767 lobits)
1111             )))
1112
1113 (defun tar-subfile-save-buffer ()
1114   "In tar subfile mode, save this buffer into its parent tar-file buffer.
1115 This doesn't write anything to disk; you must save the parent tar-file buffer
1116 to make your changes permanent."
1117   (interactive)
1118   (if (not (and (boundp 'tar-superior-buffer) tar-superior-buffer))
1119     (error "This buffer has no superior tar file buffer"))
1120   (if (not (and (boundp 'tar-superior-descriptor) tar-superior-descriptor))
1121     (error "This buffer doesn't have an index into its superior tar file!"))
1122   (save-excursion
1123   (let ((subfile (current-buffer))
1124         (coding buffer-file-coding-system)
1125         (descriptor tar-superior-descriptor)
1126         subfile-size)
1127     (set-buffer tar-superior-buffer)
1128     (let* ((tokens (tar-desc-tokens descriptor))
1129            (start (tar-desc-data-start descriptor))
1130            (name (tar-header-name tokens))
1131            (size (tar-header-size tokens))
1132            (size-pad (ash (ash (+ size 511) -9) 9))
1133            (head (memq descriptor tar-parse-info))
1134            (following-descs (cdr head)))
1135       (if (not head)
1136         (error "Can't find this tar file entry in its parent tar file!"))
1137       (unwind-protect
1138        (save-excursion
1139         ;; delete the old data...
1140         (let* ((data-start (+ start (- tar-header-offset (point-min))))
1141                (data-end (+ data-start (ash (ash (+ size 511) -9) 9))))
1142           (narrow-to-region data-start data-end)
1143           (delete-region (point-min) (point-max))
1144           ;; insert the new data...
1145           (goto-char data-start)
1146           (with-current-buffer subfile
1147             (save-restriction
1148               (widen)
1149               (encode-coding-region 1 (point-max) coding tar-superior-buffer)))
1150           (setq subfile-size (- (point-max) (point-min)))
1151           ;;
1152           ;; pad the new data out to a multiple of 512...
1153           (let ((subfile-size-pad (ash (ash (+ subfile-size 511) -9) 9)))
1154             (goto-char (point-max))
1155             (insert (make-string (- subfile-size-pad subfile-size) 0))
1156             ;;
1157             ;; update the data pointer of this and all following files...
1158             (tar-setf (tar-header-size tokens) subfile-size)
1159             (let ((difference (- subfile-size-pad size-pad)))
1160               (dolist (desc following-descs)
1161                 (tar-setf (tar-desc-data-start desc)
1162                           (+ (tar-desc-data-start desc) difference))))
1163             ;;
1164             ;; Update the size field in the header block.
1165             (widen)
1166             (let ((header-start (- data-start 512)))
1167               (goto-char (+ header-start tar-size-offset))
1168               (delete-region (point) (+ (point) 12))
1169               (insert (format "%11o" subfile-size))
1170               (insert ? )
1171               ;;
1172               ;; Maybe update the datestamp.
1173               (if (not tar-update-datestamp)
1174                   nil
1175                 (goto-char (+ header-start tar-time-offset))
1176                 (delete-region (point) (+ (point) 12))
1177                 (insert (tar-octal-time (current-time)))
1178                 (insert ? ))
1179               ;;
1180               ;; compute a new checksum and insert it.
1181               (let ((chk (tar-header-block-checksum
1182                           (buffer-substring header-start data-start))))
1183                 (goto-char (+ header-start tar-chk-offset))
1184                 (delete-region (point) (+ (point) 8))
1185                 (insert (format "%6o" chk))
1186                 (insert 0)
1187                 (insert ? )
1188                 (tar-setf (tar-header-checksum tokens) chk)))
1189             ;;
1190             ;; alter the descriptor-line...
1191             ;;
1192             (let ((position (- (length tar-parse-info) (length head))))
1193               (goto-char (point-min))
1194               (forward-line position)
1195               (beginning-of-line)
1196               (let ((p (point))
1197                     after
1198                     (m (set-marker (make-marker) tar-header-offset)))
1199                 (forward-line 1)
1200                 (setq after (point))
1201                 ;; Insert the new text after the old, before deleting,
1202                 ;; to preserve the window start.
1203                 (let ((line (tar-header-block-summarize tokens t)))
1204                   (insert-before-markers line "\n"))
1205                 (delete-region p after)
1206                 (setq tar-header-offset (marker-position m)))
1207               )))
1208         ;; after doing the insertion, add any final padding that may be necessary.
1209         (tar-pad-to-blocksize))
1210        (narrow-to-region (point-min) tar-header-offset)))
1211     (set-buffer-modified-p t)   ; mark the tar file as modified
1212     (tar-next-line 0)
1213     (set-buffer subfile)
1214     (set-buffer-modified-p nil) ; mark the tar subfile as unmodified
1215     (message "Saved into tar-buffer `%s'.  Be sure to save that buffer!"
1216              (buffer-name tar-superior-buffer))
1217     ;; Prevent basic-save-buffer from changing our coding-system.
1218     (setq last-coding-system-used buffer-file-coding-system)
1219     ;; Prevent ordinary saving from happening.
1220     t)))
1221
1222
1223 ;; When this function is called, it is sure that the buffer is unibyte.
1224 (defun tar-pad-to-blocksize ()
1225   "If we are being anal about tar file blocksizes, fix up the current buffer.
1226 Leaves the region wide."
1227   (if (null tar-anal-blocksize)
1228       nil
1229     (widen)
1230     (let* ((last-desc (nth (1- (length tar-parse-info)) tar-parse-info))
1231            (start (tar-desc-data-start last-desc))
1232            (tokens (tar-desc-tokens last-desc))
1233            (link-p (tar-header-link-type tokens))
1234            (size (if link-p 0 (tar-header-size tokens)))
1235            (data-end (+ start size))
1236            (bbytes (ash tar-anal-blocksize 9))
1237            (pad-to (+ bbytes (* bbytes (/ (- data-end (point-min)) bbytes))))
1238            (inhibit-read-only t) ; ##
1239            )
1240       ;; If the padding after the last data is too long, delete some;
1241       ;; else insert some until we are padded out to the right number of blocks.
1242       ;;
1243       (let ((goal-end (+ (or tar-header-offset 0) pad-to)))
1244         (if (> (point-max) goal-end)
1245             (delete-region goal-end (point-max))
1246           (goto-char (point-max))
1247           (insert (make-string (- goal-end (point-max)) ?\0)))))))
1248
1249
1250 ;; Used in write-file-hook to write tar-files out correctly.
1251 (defun tar-mode-write-file ()
1252   (unwind-protect
1253       (save-excursion
1254         (widen)
1255         ;; Doing this here confuses things - the region gets left too wide!
1256         ;; I suppose this is run in a context where changing the buffer is bad.
1257         ;; (tar-pad-to-blocksize)
1258         ;; tar-header-offset turns out to be null for files fetched with W3,
1259         ;; at least.
1260         (let ((coding-system-for-write 'no-conversion))
1261           (write-region (or tar-header-offset
1262                             (point-min))
1263                         (point-max)
1264                         buffer-file-name nil t))
1265         (tar-clear-modification-flags)
1266         (set-buffer-modified-p nil))
1267     (narrow-to-region (point-min) tar-header-offset))
1268   ;; Return t because we've written the file.
1269   t)
1270 \f
1271 (provide 'tar-mode)
1272
1273 ;; arch-tag: 8a585a4a-340e-42c2-89e7-d3b1013a4b78
1274 ;;; tar-mode.el ends here