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 Free Software Foundation, Inc.
   4
   5 ;; Author: Jamie Zawinski <jwz@lucid.com>
   6 ;; Maintainer: FSF
   7 ;; Created: 04 Apr 1990
   8 ;; Keywords: unix
   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 2, or (at your option)
  15 ;; 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; see the file COPYING.  If not, write to the
  24 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  25 ;; Boston, MA 02111-1307, USA.
  26
  27 ;;; Commentary:
  28
  29 ;; This package attempts to make dealing with Unix 'tar' archives easier.
  30 ;; When this code is loaded, visiting a file whose name ends in '.tar' will
  31 ;; cause the contents of that archive file to be displayed in a Dired-like
  32 ;; listing.  It is then possible to use the customary Dired keybindings to
  33 ;; extract sub-files from that archive, either by reading them into their own
  34 ;; editor buffers, or by copying them directly to arbitrary files on disk.
  35 ;; It is also possible to delete sub-files from within the tar file and write
  36 ;; the modified archive back to disk, or to edit sub-files within the archive
  37 ;; and re-insert the modified files into the archive.  See the documentation
  38 ;; string of tar-mode for more info.
  39
  40 ;; This code now understands the extra fields that GNU tar adds to tar files.
  41
  42 ;; This interacts correctly with "uncompress.el" in the Emacs library,
  43 ;; which you get with
  44 ;;
  45 ;;  (autoload 'uncompress-while-visiting "uncompress")
  46 ;;  (setq auto-mode-alist (cons '("\\.Z$" . uncompress-while-visiting)
  47 ;;                         auto-mode-alist))
  48 ;;
  49 ;; Do not attempt to use tar-mode.el with crypt.el, you will lose.
  50
  51 ;;    ***************   TO DO   ***************
  52 ;;
  53 ;; o  chmod should understand "a+x,og-w".
  54 ;;
  55 ;; o  It's not possible to add a NEW file to a tar archive; not that
  56 ;;    important, but still...
  57 ;;
  58 ;; o  The code is less efficient that it could be - in a lot of places, I
  59 ;;    pull a 512-character string out of the buffer and parse it, when I could
  60 ;;    be parsing it in place, not garbaging a string.  Should redo that.
  61 ;;
  62 ;; o  I'd like a command that searches for a string/regexp in every subfile
  63 ;;    of an archive, where <esc> would leave you in a subfile-edit buffer.
  64 ;;    (Like the Meta-R command of the Zmacs mail reader.)
  65 ;;
  66 ;; o  Sometimes (but not always) reverting the tar-file buffer does not
  67 ;;    re-grind the listing, and you are staring at the binary tar data.
  68 ;;    Typing 'g' again immediately after that will always revert and re-grind
  69 ;;    it, though.  I have no idea why this happens.
  70 ;;
  71 ;; o  Tar-mode interacts poorly with crypt.el and zcat.el because the tar
  72 ;;    write-file-hook actually writes the file.  Instead it should remove the
  73 ;;    header (and conspire to put it back afterwards) so that other write-file
  74 ;;    hooks which frob the buffer have a chance to do their dirty work.  There
  75 ;;    might be a problem if the tar write-file-hook does not come *first* on
  76 ;;    the list.
  77 ;;
  78 ;; o  Block files, sparse files, continuation files, and the various header
  79 ;;    types aren't editable.  Actually I don't know that they work at all.
  80
  81 ;; Rationale:
  82
  83 ;; Why does tar-mode edit the file itself instead of using tar?
  84
  85 ;; That means that you can edit tar files which you don't have room for
  86 ;; on your local disk.
  87
  88 ;; I don't know about recent features in gnu tar, but old versions of tar
  89 ;; can't replace a file in the middle of a tar file with a new version.
  90 ;; Tar-mode can.  I don't think tar can do things like chmod the subfiles.
  91 ;; An implementation which involved unpacking and repacking the file into
  92 ;; some scratch directory would be very wasteful, and wouldn't be able to
  93 ;; preserve the file owners.
  94
  95 ;;; Code:
  96
  97 (defgroup tar nil
  98   "Simple editing of tar files."
  99   :prefix "tar-"
 100   :group 'data)
 101
 102 (defcustom tar-anal-blocksize 20
 103   "*The blocksize of tar files written by Emacs, or nil, meaning don't care.
 104 The blocksize of a tar file is not really the size of the blocks; rather, it is
 105 the number of blocks written with one system call.  When tarring to a tape,
 106 this is the size of the *tape* blocks, but when writing to a file, it doesn't
 107 matter much.  The only noticeable difference is that if a tar file does not
 108 have a blocksize of 20, tar will tell you that; all this really controls is
 109 how many null padding bytes go on the end of the tar file."
 110   :type '(choice integer (const nil))
 111   :group 'tar)
 112
 113 (defcustom tar-update-datestamp nil
 114   "*Non-nil means Tar mode should play fast and loose with sub-file datestamps.
 115 If this is true, then editing and saving a tar file entry back into its
 116 tar file will update its datestamp.  If false, the datestamp is unchanged.
 117 You may or may not want this - it is good in that you can tell when a file
 118 in a tar archive has been changed, but it is bad for the same reason that
 119 editing a file in the tar archive at all is bad - the changed version of
 120 the file never exists on disk."
 121   :type 'boolean
 122   :group 'tar)
 123
 124 (defcustom tar-mode-show-date nil
 125   "*Non-nil means Tar mode should show the date/time of each subfile.
 126 This information is useful, but it takes screen space away from file names."
 127   :type 'boolean
 128   :group 'tar)
 129
 130 (defvar tar-parse-info nil)
 131 ;; Be sure that this variable holds byte position, not char position.
 132 (defvar tar-header-offset nil)
 133 (defvar tar-superior-buffer nil)
 134 (defvar tar-superior-descriptor nil)
 135 (defvar tar-subfile-mode nil)
 136
 137 (put 'tar-parse-info 'permanent-local t)
 138 (put 'tar-header-offset 'permanent-local t)
 139 (put 'tar-superior-buffer 'permanent-local t)
 140 (put 'tar-superior-descriptor '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-end-offset (+ tar-dmin-offset 8))
 200
 201 (defun tar-header-block-tokenize (string)
 202   "Return a `tar-header' structure.
 203 This is a list of name, mode, uid, gid, size,
 204 write-date, checksum, link-type, and link-name."
 205   (cond ((< (length string) 512) nil)
 206         (;(some 'plusp string)           ; <-- oops, massive cycle hog!
 207          (or (not (= 0 (aref string 0))) ; This will do.
 208              (not (= 0 (aref string 101))))
 209          (let* ((name-end (1- tar-mode-offset))
 210                 (link-end (1- tar-magic-offset))
 211                 (uname-end (1- tar-gname-offset))
 212                 (gname-end (1- tar-dmaj-offset))
 213                 (link-p (aref string tar-linkp-offset))
 214                 (magic-str (substring string tar-magic-offset (1- tar-uname-offset)))
 215                 (uname-valid-p (or (string= "ustar  " magic-str) (string= "GNUtar " magic-str)))
 216                 name linkname
 217                 (nulsexp   "[^\000]*\000"))
 218            (when (string-match nulsexp string tar-name-offset)
 219              (setq name-end (min name-end (1- (match-end 0)))))
 220            (when (string-match nulsexp string tar-link-offset)
 221              (setq link-end (min link-end (1- (match-end 0)))))
 222            (when (string-match nulsexp string tar-uname-offset)
 223              (setq uname-end (min uname-end (1- (match-end 0)))))
 224            (when (string-match nulsexp string tar-gname-offset)
 225              (setq gname-end (min gname-end (1- (match-end 0)))))
 226            (setq name (substring string tar-name-offset name-end)
 227                  link-p (if (or (= link-p 0) (= link-p ?0))
 228                             nil
 229                           (- link-p ?0)))
 230            (setq linkname (substring string tar-link-offset link-end))
 231            (if default-enable-multibyte-characters
 232                (setq name
 233                      (decode-coding-string name (or file-name-coding-system
 234                                                     'undecided))
 235                      linkname
 236                      (decode-coding-string linkname (or file-name-coding-system
 237                                                         'undecided))))
 238            (if (and (null link-p) (string-match "/$" name)) (setq link-p 5)) ; directory
 239            (make-tar-header
 240              name
 241              (tar-parse-octal-integer string tar-mode-offset tar-uid-offset)
 242              (tar-parse-octal-integer string tar-uid-offset tar-gid-offset)
 243              (tar-parse-octal-integer string tar-gid-offset tar-size-offset)
 244              (tar-parse-octal-integer string tar-size-offset tar-time-offset)
 245              (tar-parse-octal-long-integer string tar-time-offset tar-chk-offset)
 246              (tar-parse-octal-integer string tar-chk-offset tar-linkp-offset)
 247              link-p
 248              linkname
 249              uname-valid-p
 250              (and uname-valid-p (substring string tar-uname-offset uname-end))
 251              (and uname-valid-p (substring string tar-gname-offset gname-end))
 252              (tar-parse-octal-integer string tar-dmaj-offset tar-dmin-offset)
 253              (tar-parse-octal-integer string tar-dmin-offset tar-end-offset)
 254              )))
 255         (t 'empty-tar-block)))
 256
 257
 258 (defun tar-parse-octal-integer (string &optional start end)
 259   (if (null start) (setq start 0))
 260   (if (null end) (setq end (length string)))
 261   (if (= (aref string start) 0)
 262       0
 263     (let ((n 0))
 264       (while (< start end)
 265         (setq n (if (< (aref string start) ?0) n
 266                   (+ (* n 8) (- (aref string start) ?0)))
 267               start (1+ start)))
 268       n)))
 269
 270 (defun tar-parse-octal-long-integer (string &optional start end)
 271   (if (null start) (setq start 0))
 272   (if (null end) (setq end (length string)))
 273   (if (= (aref string start) 0)
 274       (list 0 0)
 275     (let ((lo 0)
 276           (hi 0))
 277       (while (< start end)
 278         (if (>= (aref string start) ?0)
 279             (setq lo (+ (* lo 8) (- (aref string start) ?0))
 280                   hi (+ (* hi 8) (ash lo -16))
 281                   lo (logand lo 65535)))
 282         (setq start (1+ start)))
 283       (list hi lo))))
 284
 285 (defun tar-parse-octal-integer-safe (string)
 286   (let ((L (length string)))
 287     (if (= L 0) (error "empty string"))
 288     (dotimes (i L)
 289        (if (or (< (aref string i) ?0)
 290                (> (aref string i) ?7))
 291            (error "`%c' is not an octal digit"))))
 292   (tar-parse-octal-integer string))
 293
 294
 295 (defun tar-header-block-checksum (string)
 296   "Compute and return a tar-acceptable checksum for this block."
 297   (let* ((chk-field-start tar-chk-offset)
 298          (chk-field-end (+ chk-field-start 8))
 299          (sum 0)
 300          (i 0))
 301     ;; Add up all of the characters except the ones in the checksum field.
 302     ;; Add that field as if it were filled with spaces.
 303     (while (< i chk-field-start)
 304       (setq sum (+ sum (aref string i))
 305             i (1+ i)))
 306     (setq i chk-field-end)
 307     (while (< i 512)
 308       (setq sum (+ sum (aref string i))
 309             i (1+ i)))
 310     (+ sum (* 32 8))))
 311
 312 (defun tar-header-block-check-checksum (hblock desired-checksum file-name)
 313   "Beep and print a warning if the checksum doesn't match."
 314   (if (not (= desired-checksum (tar-header-block-checksum hblock)))
 315       (progn (beep) (message "Invalid checksum for file %s!" file-name))))
 316
 317 (defun tar-clip-time-string (time)
 318   (let ((str (current-time-string time)))
 319     (concat " " (substring str 4 16) (substring str 19 24))))
 320
 321 (defun tar-grind-file-mode (mode)
 322   "Construct a `-rw--r--r--' string indicating MODE.
 323 MODE should be an integer which is a file mode value."
 324   (string
 325    (if (zerop (logand 256 mode)) ?- ?r)
 326    (if (zerop (logand 128 mode)) ?- ?w)
 327    (if (zerop (logand 1024 mode)) (if (zerop (logand  64 mode)) ?- ?x) ?s)
 328    (if (zerop (logand  32 mode)) ?- ?r)
 329    (if (zerop (logand  16 mode)) ?- ?w)
 330    (if (zerop (logand 2048 mode)) (if (zerop (logand   8 mode)) ?- ?x) ?s)
 331    (if (zerop (logand   4 mode)) ?- ?r)
 332    (if (zerop (logand   2 mode)) ?- ?w)
 333    (if (zerop (logand   1 mode)) ?- ?x)))
 334
 335 (defun tar-header-block-summarize (tar-hblock &optional mod-p)
 336   "Return a line similar to the output of `tar -vtf'."
 337   (let ((name (tar-header-name tar-hblock))
 338         (mode (tar-header-mode tar-hblock))
 339         (uid (tar-header-uid tar-hblock))
 340         (gid (tar-header-gid tar-hblock))
 341         (uname (tar-header-uname tar-hblock))
 342         (gname (tar-header-gname tar-hblock))
 343         (size (tar-header-size tar-hblock))
 344         (time (tar-header-date tar-hblock))
 345         (ck (tar-header-checksum tar-hblock))
 346         (type (tar-header-link-type tar-hblock))
 347         (link-name (tar-header-link-name tar-hblock)))
 348     (format "%c%c%s%8s/%-8s%7s%s %s%s"
 349             (if mod-p ?* ? )
 350             (cond ((or (eq type nil) (eq type 0)) ?-)
 351                   ((eq type 1) ?l)      ; link
 352                   ((eq type 2) ?s)      ; symlink
 353                   ((eq type 3) ?c)      ; char special
 354                   ((eq type 4) ?b)      ; block special
 355                   ((eq type 5) ?d)      ; directory
 356                   ((eq type 6) ?p)      ; FIFO/pipe
 357                   ((eq type 20) ?*)     ; directory listing
 358                   ((eq type 29) ?M)     ; multivolume continuation
 359                   ((eq type 35) ?S)     ; sparse
 360                   ((eq type 38) ?V)     ; volume header
 361                   (t ?\ )
 362                   )
 363             (tar-grind-file-mode mode)
 364             (if (= 0 (length uname)) uid uname)
 365             (if (= 0 (length gname)) gid gname)
 366             size
 367             (if tar-mode-show-date (tar-clip-time-string time) "")
 368             (propertize name 'mouse-face 'highlight)
 369             (if (or (eq type 1) (eq type 2))
 370                 (concat (if (= type 1) " ==> " " --> ") link-name)
 371               ""))))
 372
 373 (defun tar-summarize-buffer ()
 374   "Parse the contents of the tar file in the current buffer.
 375 Place a dired-like listing on the front;
 376 then narrow to it, so that only that listing
 377 is visible (and the real data of the buffer is hidden)."
 378   (set-buffer-multibyte nil)
 379   (message "Parsing tar file...")
 380   (let* ((result '())
 381          (pos 1)
 382          (bs (max 1 (- (buffer-size) 1024))) ; always 2+ empty blocks at end.
 383          (bs100 (max 1 (/ bs 100)))
 384          tokens)
 385     (while (and (<= (+ pos 512) (point-max))
 386                 (not (eq 'empty-tar-block
 387                          (setq tokens
 388                                (tar-header-block-tokenize
 389                                 (buffer-substring pos (+ pos 512)))))))
 390       (setq pos (+ pos 512))
 391       (message "Parsing tar file...%d%%"
 392                ;(/ (* pos 100) bs)   ; this gets round-off lossage
 393                (/ pos bs100)         ; this doesn't
 394                )
 395       (if (eq (tar-header-link-type tokens) 20)
 396           ;; Foo.  There's an extra empty block after these.
 397           (setq pos (+ pos 512)))
 398       (let ((size (tar-header-size tokens)))
 399         (if (< size 0)
 400             (error "%s has size %s - corrupted"
 401                    (tar-header-name tokens) size))
 402         ;
 403         ; This is just too slow.  Don't really need it anyway....
 404         ;(tar-header-block-check-checksum
 405         ;  hblock (tar-header-block-checksum hblock)
 406         ;  (tar-header-name tokens))
 407
 408         (setq result (cons (make-tar-desc pos tokens) result))
 409
 410         (and (null (tar-header-link-type tokens))
 411              (> size 0)
 412              (setq pos
 413                    (+ pos 512 (ash (ash (1- size) -9) 9))        ; this works
 414                    ;(+ pos (+ size (- 512 (rem (1- size) 512)))) ; this doesn't
 415                    ))))
 416     (make-local-variable 'tar-parse-info)
 417     (setq tar-parse-info (nreverse result))
 418     ;; A tar file should end with a block or two of nulls,
 419     ;; but let's not get a fatal error if it doesn't.
 420     (if (eq tokens 'empty-tar-block)
 421         (message "Parsing tar file...done")
 422       (message "Warning: premature EOF parsing tar file")))
 423   (save-excursion
 424     (goto-char (point-min))
 425     (let ((buffer-read-only nil)
 426           (summaries nil))
 427       ;; Collect summary lines and insert them all at once since tar files
 428       ;; can be pretty big.
 429       (dolist (tar-desc (reverse tar-parse-info))
 430         (setq summaries
 431               (cons (tar-header-block-summarize (tar-desc-tokens tar-desc))
 432                     (cons "\n"
 433                           summaries))))
 434       (let ((total-summaries (apply 'concat summaries)))
 435         (if (multibyte-string-p total-summaries)
 436             (set-buffer-multibyte t))
 437         (insert total-summaries))
 438       (make-local-variable 'tar-header-offset)
 439       (setq tar-header-offset (point))
 440       (narrow-to-region 1 tar-header-offset)
 441       (if enable-multibyte-characters
 442           (setq tar-header-offset (position-bytes tar-header-offset)))
 443       (set-buffer-modified-p nil))))
 444 \f
 445 (defvar tar-mode-map nil "*Local keymap for Tar mode listings.")
 446
 447 (if tar-mode-map
 448     nil
 449   (setq tar-mode-map (make-keymap))
 450   (suppress-keymap tar-mode-map)
 451   (define-key tar-mode-map " " 'tar-next-line)
 452   (define-key tar-mode-map "C" 'tar-copy)
 453   (define-key tar-mode-map "d" 'tar-flag-deleted)
 454   (define-key tar-mode-map "\^D" 'tar-flag-deleted)
 455   (define-key tar-mode-map "e" 'tar-extract)
 456   (define-key tar-mode-map "f" 'tar-extract)
 457   (define-key tar-mode-map "\C-m" 'tar-extract)
 458   (define-key tar-mode-map [mouse-2] 'tar-mouse-extract)
 459   (define-key tar-mode-map "g" 'revert-buffer)
 460   (define-key tar-mode-map "h" 'describe-mode)
 461   (define-key tar-mode-map "n" 'tar-next-line)
 462   (define-key tar-mode-map "\^N" 'tar-next-line)
 463   (define-key tar-mode-map [down] 'tar-next-line)
 464   (define-key tar-mode-map "o" 'tar-extract-other-window)
 465   (define-key tar-mode-map "p" 'tar-previous-line)
 466   (define-key tar-mode-map "q" 'quit-window)
 467   (define-key tar-mode-map "\^P" 'tar-previous-line)
 468   (define-key tar-mode-map [up] 'tar-previous-line)
 469   (define-key tar-mode-map "R" 'tar-rename-entry)
 470   (define-key tar-mode-map "u" 'tar-unflag)
 471   (define-key tar-mode-map "v" 'tar-view)
 472   (define-key tar-mode-map "x" 'tar-expunge)
 473   (define-key tar-mode-map "\177" 'tar-unflag-backwards)
 474   (define-key tar-mode-map "E" 'tar-extract-other-window)
 475   (define-key tar-mode-map "M" 'tar-chmod-entry)
 476   (define-key tar-mode-map "G" 'tar-chgrp-entry)
 477   (define-key tar-mode-map "O" 'tar-chown-entry)
 478   )
 479 \f
 480 ;; Make menu bar items.
 481
 482 ;; Get rid of the Edit menu bar item to save space.
 483 (define-key tar-mode-map [menu-bar edit] 'undefined)
 484
 485 (define-key tar-mode-map [menu-bar immediate]
 486   (cons "Immediate" (make-sparse-keymap "Immediate")))
 487
 488 (define-key tar-mode-map [menu-bar immediate view]
 489   '("View This File" . tar-view))
 490 (define-key tar-mode-map [menu-bar immediate display]
 491   '("Display in Other Window" . tar-display-other-window))
 492 (define-key tar-mode-map [menu-bar immediate find-file-other-window]
 493   '("Find in Other Window" . tar-extract-other-window))
 494 (define-key tar-mode-map [menu-bar immediate find-file]
 495   '("Find This File" . tar-extract))
 496
 497 (define-key tar-mode-map [menu-bar mark]
 498   (cons "Mark" (make-sparse-keymap "Mark")))
 499
 500 (define-key tar-mode-map [menu-bar mark unmark-all]
 501   '("Unmark All" . tar-clear-modification-flags))
 502 (define-key tar-mode-map [menu-bar mark deletion]
 503   '("Flag" . tar-flag-deleted))
 504 (define-key tar-mode-map [menu-bar mark unmark]
 505   '("Unflag" . tar-unflag))
 506
 507 (define-key tar-mode-map [menu-bar operate]
 508   (cons "Operate" (make-sparse-keymap "Operate")))
 509
 510 (define-key tar-mode-map [menu-bar operate chown]
 511   '("Change Owner..." . tar-chown-entry))
 512 (define-key tar-mode-map [menu-bar operate chgrp]
 513   '("Change Group..." . tar-chgrp-entry))
 514 (define-key tar-mode-map [menu-bar operate chmod]
 515   '("Change Mode..." . tar-chmod-entry))
 516 (define-key tar-mode-map [menu-bar operate rename]
 517   '("Rename to..." . tar-rename-entry))
 518 (define-key tar-mode-map [menu-bar operate copy]
 519   '("Copy to..." . tar-copy))
 520 (define-key tar-mode-map [menu-bar operate expunge]
 521   '("Expunge Marked Files" . tar-expunge))
 522 \f
 523 ;; tar mode is suitable only for specially formatted data.
 524 (put 'tar-mode 'mode-class 'special)
 525 (put 'tar-subfile-mode 'mode-class 'special)
 526
 527 ;;;###autoload
 528 (defun tar-mode ()
 529   "Major mode for viewing a tar file as a dired-like listing of its contents.
 530 You can move around using the usual cursor motion commands.
 531 Letters no longer insert themselves.
 532 Type `e' to pull a file out of the tar file and into its own buffer;
 533 or click mouse-2 on the file's line in the Tar mode buffer.
 534 Type `c' to copy an entry from the tar file into another file on disk.
 535
 536 If you edit a sub-file of this archive (as with the `e' command) and
 537 save it with Control-x Control-s, the contents of that buffer will be
 538 saved back into the tar-file buffer; in this way you can edit a file
 539 inside of a tar archive without extracting it and re-archiving it.
 540
 541 See also: variables `tar-update-datestamp' and `tar-anal-blocksize'.
 542 \\{tar-mode-map}"
 543   ;; this is not interactive because you shouldn't be turning this
 544   ;; mode on and off.  You can corrupt things that way.
 545   ;; rms: with permanent locals, it should now be possible to make this work
 546   ;; interactively in some reasonable fashion.
 547   (kill-all-local-variables)
 548   (make-local-variable 'tar-header-offset)
 549   (make-local-variable 'tar-parse-info)
 550   (make-local-variable 'require-final-newline)
 551   (setq require-final-newline nil) ; binary data, dude...
 552   (make-local-variable 'revert-buffer-function)
 553   (setq revert-buffer-function 'tar-mode-revert)
 554   (make-local-variable 'local-enable-local-variables)
 555   (setq local-enable-local-variables nil)
 556   (make-local-variable 'next-line-add-newlines)
 557   (setq next-line-add-newlines nil)
 558   ;; Prevent loss of data when saving the file.
 559   (make-local-variable 'file-precious-flag)
 560   (setq file-precious-flag t)
 561   (setq major-mode 'tar-mode)
 562   (setq mode-name "Tar")
 563   (use-local-map tar-mode-map)
 564   (auto-save-mode 0)
 565   (make-local-variable 'write-contents-hooks)
 566   (setq write-contents-hooks '(tar-mode-write-file))
 567   (widen)
 568   (if (and (boundp 'tar-header-offset) tar-header-offset)
 569       (narrow-to-region 1 (byte-to-position tar-header-offset))
 570       (tar-summarize-buffer)
 571       (tar-next-line 0))
 572   (run-hooks 'tar-mode-hook)
 573   )
 574
 575
 576 (defun tar-subfile-mode (p)
 577   "Minor mode for editing an element of a tar-file.
 578 This mode arranges for \"saving\" this buffer to write the data
 579 into the tar-file buffer that it came from.  The changes will actually
 580 appear on disk when you save the tar-file's buffer."
 581   (interactive "P")
 582   (or (and (boundp 'tar-superior-buffer) tar-superior-buffer)
 583       (error "This buffer is not an element of a tar file"))
 584 ;;; Don't do this, because it is redundant and wastes mode line space.
 585 ;;;  (or (assq 'tar-subfile-mode minor-mode-alist)
 586 ;;;      (setq minor-mode-alist (append minor-mode-alist
 587 ;;;                                  (list '(tar-subfile-mode " TarFile")))))
 588   (make-local-variable 'tar-subfile-mode)
 589   (setq tar-subfile-mode
 590         (if (null p)
 591             (not tar-subfile-mode)
 592             (> (prefix-numeric-value p) 0)))
 593   (cond (tar-subfile-mode
 594          (make-local-variable 'local-write-file-hooks)
 595          (setq local-write-file-hooks '(tar-subfile-save-buffer))
 596          ;; turn off auto-save.
 597          (auto-save-mode -1)
 598          (setq buffer-auto-save-file-name nil)
 599          (run-hooks 'tar-subfile-mode-hook))
 600         (t
 601          (kill-local-variable 'local-write-file-hooks))))
 602
 603
 604 ;; Revert the buffer and recompute the dired-like listing.
 605 (defun tar-mode-revert (&optional no-auto-save no-confirm)
 606   (let ((revert-buffer-function nil)
 607         (old-offset tar-header-offset)
 608         success)
 609     (setq tar-header-offset nil)
 610     (unwind-protect
 611         (and (revert-buffer t no-confirm)
 612              (progn (widen)
 613                     (setq success t)
 614                     (tar-mode)))
 615       ;; If the revert was canceled,
 616       ;; put back the old value of tar-header-offset.
 617       (or success
 618           (setq tar-header-offset old-offset)))))
 619
 620
 621 (defun tar-next-line (p)
 622   (interactive "p")
 623   (forward-line p)
 624   (if (eobp) nil (forward-char (if tar-mode-show-date 54 36))))
 625
 626 (defun tar-previous-line (p)
 627   (interactive "p")
 628   (tar-next-line (- p)))
 629
 630 (defun tar-current-descriptor (&optional noerror)
 631   "Return the tar-descriptor of the current line, or signals an error."
 632   ;; I wish lines had plists, like in ZMACS...
 633   (or (nth (count-lines (point-min)
 634                         (save-excursion (beginning-of-line) (point)))
 635            tar-parse-info)
 636       (if noerror
 637           nil
 638           (error "This line does not describe a tar-file entry"))))
 639
 640 (defun tar-get-descriptor ()
 641   (let* ((descriptor (tar-current-descriptor))
 642          (tokens (tar-desc-tokens descriptor))
 643          (size (tar-header-size tokens))
 644          (link-p (tar-header-link-type tokens)))
 645     (if link-p
 646         (error "This is a %s, not a real file"
 647                (cond ((eq link-p 5) "directory")
 648                      ((eq link-p 20) "tar directory header")
 649                      ((eq link-p 29) "multivolume-continuation")
 650                      ((eq link-p 35) "sparse entry")
 651                      ((eq link-p 38) "volume header")
 652                      (t "link"))))
 653     (if (zerop size) (error "This is a zero-length file"))
 654     descriptor))
 655
 656 (defun tar-mouse-extract (event)
 657   "Extract a file whose tar directory line you click on."
 658   (interactive "e")
 659   (save-excursion
 660     (set-buffer (window-buffer (posn-window (event-end event))))
 661     (save-excursion
 662       (goto-char (posn-point (event-end event)))
 663       ;; Just make sure this doesn't get an error.
 664       (tar-get-descriptor)))
 665   (select-window (posn-window (event-end event)))
 666   (goto-char (posn-point (event-end event)))
 667   (tar-extract))
 668
 669 (defun tar-extract (&optional other-window-p)
 670   "In Tar mode, extract this entry of the tar file into its own buffer."
 671   (interactive)
 672   (let* ((view-p (eq other-window-p 'view))
 673          (descriptor (tar-get-descriptor))
 674          (tokens (tar-desc-tokens descriptor))
 675          (name (tar-header-name tokens))
 676          (size (tar-header-size tokens))
 677          (start (+ (tar-desc-data-start descriptor) tar-header-offset -1))
 678          (end (+ start size)))
 679     (let* ((tar-buffer (current-buffer))
 680            (tar-buffer-multibyte enable-multibyte-characters)
 681            (tarname (buffer-name))
 682            (bufname (concat (file-name-nondirectory name)
 683                             " ("
 684                             tarname
 685                             ")"))
 686            (read-only-p (or buffer-read-only view-p))
 687            (buffer (get-buffer bufname))
 688            (just-created nil)
 689            (new-buffer-file-name (expand-file-name
 690                                   ;; `:' is not allowed on Windows
 691                                   (concat tarname "!" name))))
 692       (if (and buffer
 693                ;; Check that the buffer is visiting the same file
 694                (equal (buffer-file-name buffer) new-buffer-file-name))
 695           nil
 696         (setq buffer (generate-new-buffer bufname))
 697         (setq bufname (buffer-name buffer))
 698         (setq just-created t)
 699         (unwind-protect
 700             (progn
 701               (widen)
 702               (set-buffer-multibyte nil)
 703               (save-excursion
 704                 (set-buffer buffer)
 705                 (if enable-multibyte-characters
 706                     (progn
 707                       ;; We must avoid unibyte->multibyte conversion.
 708                       (set-buffer-multibyte nil)
 709                       (insert-buffer-substring tar-buffer start end)
 710                       (set-buffer-multibyte t))
 711                   (insert-buffer-substring tar-buffer start end))
 712                 (goto-char (point-min))
 713                 (setq buffer-file-name new-buffer-file-name)
 714                 (setq buffer-file-truename
 715                       (abbreviate-file-name buffer-file-name))
 716                 ;; We need to mimic the parts of insert-file-contents
 717                 ;; which determine the coding-system and decode the text.
 718                 (let ((coding
 719                        (and set-auto-coding-function
 720                             (save-excursion
 721                               (funcall set-auto-coding-function
 722                                        name (- (point-max) (point))))))
 723                       (multibyte enable-multibyte-characters)
 724                       (detected (detect-coding-region
 725                                  1 (min 16384 (point-max)) t)))
 726                   (if coding
 727                       (or (numberp (coding-system-eol-type coding))
 728                           (setq coding (coding-system-change-eol-conversion
 729                                         coding
 730                                         (coding-system-eol-type detected))))
 731                     (setq coding
 732                           (or (find-new-buffer-file-coding-system detected)
 733                               (let ((file-coding
 734                                      (find-operation-coding-system
 735                                       'insert-file-contents buffer-file-name)))
 736                                 (if (consp file-coding)
 737                                     (setq file-coding (car file-coding))
 738                                   file-coding)))))
 739                   (if (or (eq coding 'no-conversion)
 740                           (eq (coding-system-type coding) 5))
 741                       (setq multibyte (set-buffer-multibyte nil)))
 742                   (or multibyte
 743                       (setq coding
 744                             (coding-system-change-text-conversion
 745                              coding 'raw-text)))
 746                   (decode-coding-region 1 (point-max) coding)
 747                   (set-buffer-file-coding-system coding))
 748                 ;; Set the default-directory to the dir of the
 749                 ;; superior buffer.
 750                 (setq default-directory
 751                       (save-excursion
 752                         (set-buffer tar-buffer)
 753                         default-directory))
 754                 (normal-mode)  ; pick a mode.
 755                 (rename-buffer bufname)
 756                 (make-local-variable 'tar-superior-buffer)
 757                 (make-local-variable 'tar-superior-descriptor)
 758                 (setq tar-superior-buffer tar-buffer)
 759                 (setq tar-superior-descriptor descriptor)
 760                 (setq buffer-read-only read-only-p)
 761                 (set-buffer-modified-p nil)
 762                 (tar-subfile-mode 1))
 763               (set-buffer tar-buffer))
 764           (narrow-to-region 1 tar-header-offset)
 765           (set-buffer-multibyte tar-buffer-multibyte)))
 766       (if view-p
 767           (view-buffer buffer (and just-created 'kill-buffer))
 768         (if (eq other-window-p 'display)
 769             (display-buffer buffer)
 770           (if other-window-p
 771               (switch-to-buffer-other-window buffer)
 772             (switch-to-buffer buffer)))))))
 773
 774
 775 (defun tar-extract-other-window ()
 776   "*In Tar mode, find this entry of the tar file in another window."
 777   (interactive)
 778   (tar-extract t))
 779
 780 (defun tar-display-other-window ()
 781   "*In Tar mode, display this entry of the tar file in another window."
 782   (interactive)
 783   (tar-extract 'display))
 784
 785 (defun tar-view ()
 786   "*In Tar mode, view the tar file entry on this line."
 787   (interactive)
 788   (tar-extract 'view))
 789
 790
 791 (defun tar-read-file-name (&optional prompt)
 792   "Read a file name with this line's entry as the default."
 793   (or prompt (setq prompt "Copy to: "))
 794   (let* ((default-file (expand-file-name
 795                         (tar-header-name (tar-desc-tokens
 796                                           (tar-current-descriptor)))))
 797          (target (expand-file-name
 798                   (read-file-name prompt
 799                                   (file-name-directory default-file)
 800                                   default-file nil))))
 801     (if (or (string= "" (file-name-nondirectory target))
 802             (file-directory-p target))
 803         (setq target (concat (if (string-match "/$" target)
 804                                  (substring target 0 (1- (match-end 0)))
 805                                  target)
 806                              "/"
 807                              (file-name-nondirectory default-file))))
 808     target))
 809
 810
 811 (defun tar-copy (&optional to-file)
 812   "*In Tar mode, extract this entry of the tar file into a file on disk.
 813 If TO-FILE is not supplied, it is prompted for, defaulting to the name of
 814 the current tar-entry."
 815   (interactive (list (tar-read-file-name)))
 816   (let* ((descriptor (tar-get-descriptor))
 817          (tokens (tar-desc-tokens descriptor))
 818          (name (tar-header-name tokens))
 819          (size (tar-header-size tokens))
 820          (start (+ (tar-desc-data-start descriptor) tar-header-offset -1))
 821          (end (+ start size))
 822          (multibyte enable-multibyte-characters)
 823          (inhibit-file-name-handlers inhibit-file-name-handlers)
 824          (inhibit-file-name-operation inhibit-file-name-operation))
 825     (save-restriction
 826       (widen)
 827       ;; Inhibit compressing a subfile again if *both* name and
 828       ;; to-file are handled by jka-compr
 829       (if (and (eq (find-file-name-handler name 'write-region) 'jka-compr-handler)
 830                (eq (find-file-name-handler to-file 'write-region) 'jka-compr-handler))
 831           (setq inhibit-file-name-handlers
 832                 (cons 'jka-compr-handler
 833                       (and (eq inhibit-file-name-operation 'write-region)
 834                            inhibit-file-name-handlers))
 835                 inhibit-file-name-operation 'write-region))
 836       (unwind-protect
 837           (let ((coding-system-for-write 'no-conversion))
 838             (set-buffer-multibyte nil)
 839             (write-region start end to-file nil nil nil t))
 840         (set-buffer-multibyte multibyte)))
 841     (message "Copied tar entry %s to %s" name to-file)))
 842
 843 (defun tar-flag-deleted (p &optional unflag)
 844   "*In Tar mode, mark this sub-file to be deleted from the tar file.
 845 With a prefix argument, mark that many files."
 846   (interactive "p")
 847   (beginning-of-line)
 848   (dotimes (i (if (< p 0) (- p) p))
 849     (if (tar-current-descriptor unflag) ; barf if we're not on an entry-line.
 850         (progn
 851           (delete-char 1)
 852           (insert (if unflag " " "D"))))
 853     (forward-line (if (< p 0) -1 1)))
 854   (if (eobp) nil (forward-char 36)))
 855
 856 (defun tar-unflag (p)
 857   "*In Tar mode, un-mark this sub-file if it is marked to be deleted.
 858 With a prefix argument, un-mark that many files forward."
 859   (interactive "p")
 860   (tar-flag-deleted p t))
 861
 862 (defun tar-unflag-backwards (p)
 863   "*In Tar mode, un-mark this sub-file if it is marked to be deleted.
 864 With a prefix argument, un-mark that many files backward."
 865   (interactive "p")
 866   (tar-flag-deleted (- p) t))
 867
 868
 869 ;; When this function is called, it is sure that the buffer is unibyte.
 870 (defun tar-expunge-internal ()
 871   "Expunge the tar-entry specified by the current line."
 872   (let* ((descriptor (tar-current-descriptor))
 873          (tokens (tar-desc-tokens descriptor))
 874          (line (tar-desc-data-start descriptor))
 875          (name (tar-header-name tokens))
 876          (size (tar-header-size tokens))
 877          (link-p (tar-header-link-type tokens))
 878          (start (tar-desc-data-start descriptor))
 879          (following-descs (cdr (memq descriptor tar-parse-info))))
 880     (if link-p (setq size 0)) ; size lies for hard-links.
 881     ;;
 882     ;; delete the current line...
 883     (beginning-of-line)
 884     (let ((line-start (point)))
 885       (end-of-line) (forward-char)
 886       (let ((line-len (- (point) line-start)))
 887         (delete-region line-start (point))
 888         ;;
 889         ;; decrement the header-pointer to be in sync...
 890         (setq tar-header-offset (- tar-header-offset line-len))))
 891     ;;
 892     ;; delete the data pointer...
 893     (setq tar-parse-info (delq descriptor tar-parse-info))
 894     ;;
 895     ;; delete the data from inside the file...
 896     (widen)
 897     (let* ((data-start (+ start tar-header-offset -513))
 898            (data-end (+ data-start 512 (ash (ash (+ size 511) -9) 9))))
 899       (delete-region data-start data-end)
 900       ;;
 901       ;; and finally, decrement the start-pointers of all following
 902       ;; entries in the archive.  This is a pig when deleting a bunch
 903       ;; of files at once - we could optimize this to only do the
 904       ;; iteration over the files that remain, or only iterate up to
 905       ;; the next file to be deleted.
 906       (let ((data-length (- data-end data-start)))
 907         (dolist (desc following-descs)
 908           (tar-setf (tar-desc-data-start desc)
 909                     (- (tar-desc-data-start desc) data-length))))
 910       ))
 911   (narrow-to-region 1 tar-header-offset))
 912
 913
 914 (defun tar-expunge (&optional noconfirm)
 915   "*In Tar mode, delete all the archived files flagged for deletion.
 916 This does not modify the disk image; you must save the tar file itself
 917 for this to be permanent."
 918   (interactive)
 919   (if (or noconfirm
 920           (y-or-n-p "Expunge files marked for deletion? "))
 921       (let ((n 0)
 922             (multibyte enable-multibyte-characters))
 923         (set-buffer-multibyte nil)
 924         (save-excursion
 925           (goto-char (point-min))
 926           (while (not (eobp))
 927             (if (looking-at "D")
 928                 (progn (tar-expunge-internal)
 929                        (setq n (1+ n)))
 930                 (forward-line 1)))
 931           ;; after doing the deletions, add any padding that may be necessary.
 932           (tar-pad-to-blocksize)
 933           (narrow-to-region 1 tar-header-offset))
 934         (set-buffer-multibyte multibyte)
 935         (if (zerop n)
 936             (message "Nothing to expunge.")
 937             (message "%s files expunged.  Be sure to save this buffer." n)))))
 938
 939
 940 (defun tar-clear-modification-flags ()
 941   "Remove the stars at the beginning of each line."
 942   (interactive)
 943   (save-excursion
 944     (goto-char (point-min))
 945     (while (< (position-bytes (point)) tar-header-offset)
 946       (if (not (eq (following-char) ?\ ))
 947           (progn (delete-char 1) (insert " ")))
 948       (forward-line 1))))
 949
 950
 951 (defun tar-chown-entry (new-uid)
 952   "*Change the user-id associated with this entry in the tar file.
 953 If this tar file was written by GNU tar, then you will be able to edit
 954 the user id as a string; otherwise, you must edit it as a number.
 955 You can force editing as a number by calling this with a prefix arg.
 956 This does not modify the disk image; you must save the tar file itself
 957 for this to be permanent."
 958   (interactive (list
 959                  (let ((tokens (tar-desc-tokens (tar-current-descriptor))))
 960                    (if (or current-prefix-arg
 961                            (not (tar-header-magic tokens)))
 962                        (let (n)
 963                          (while (not (numberp (setq n (read-minibuffer
 964                                                         "New UID number: "
 965                                                         (format "%s" (tar-header-uid tokens)))))))
 966                          n)
 967                        (read-string "New UID string: " (tar-header-uname tokens))))))
 968   (cond ((stringp new-uid)
 969          (tar-setf (tar-header-uname (tar-desc-tokens (tar-current-descriptor)))
 970                    new-uid)
 971          (tar-alter-one-field tar-uname-offset (concat new-uid "\000")))
 972         (t
 973          (tar-setf (tar-header-uid (tar-desc-tokens (tar-current-descriptor)))
 974                    new-uid)
 975          (tar-alter-one-field tar-uid-offset
 976            (concat (substring (format "%6o" new-uid) 0 6) "\000 ")))))
 977
 978
 979 (defun tar-chgrp-entry (new-gid)
 980   "*Change the group-id associated with this entry in the tar file.
 981 If this tar file was written by GNU tar, then you will be able to edit
 982 the group id as a string; otherwise, you must edit it as a number.
 983 You can force editing as a number by calling this with a prefix arg.
 984 This does not modify the disk image; you must save the tar file itself
 985 for this to be permanent."
 986   (interactive (list
 987                  (let ((tokens (tar-desc-tokens (tar-current-descriptor))))
 988                    (if (or current-prefix-arg
 989                            (not (tar-header-magic tokens)))
 990                        (let (n)
 991                          (while (not (numberp (setq n (read-minibuffer
 992                                                         "New GID number: "
 993                                                         (format "%s" (tar-header-gid tokens)))))))
 994                          n)
 995                        (read-string "New GID string: " (tar-header-gname tokens))))))
 996   (cond ((stringp new-gid)
 997          (tar-setf (tar-header-gname (tar-desc-tokens (tar-current-descriptor)))
 998                    new-gid)
 999          (tar-alter-one-field tar-gname-offset
1000            (concat new-gid "\000")))
1001         (t
1002          (tar-setf (tar-header-gid (tar-desc-tokens (tar-current-descriptor)))
1003                    new-gid)
1004          (tar-alter-one-field tar-gid-offset
1005            (concat (substring (format "%6o" new-gid) 0 6) "\000 ")))))
1006
1007 (defun tar-rename-entry (new-name)
1008   "*Change the name associated with this entry in the tar file.
1009 This does not modify the disk image; you must save the tar file itself
1010 for this to be permanent."
1011   (interactive
1012     (list (read-string "New name: "
1013             (tar-header-name (tar-desc-tokens (tar-current-descriptor))))))
1014   (if (string= "" new-name) (error "zero length name"))
1015   (if (> (length new-name) 98) (error "name too long"))
1016   (tar-setf (tar-header-name (tar-desc-tokens (tar-current-descriptor)))
1017             new-name)
1018   (tar-alter-one-field 0
1019     (substring (concat new-name (make-string 99 0)) 0 99)))
1020
1021
1022 (defun tar-chmod-entry (new-mode)
1023   "*Change the protection bits associated with this entry in the tar file.
1024 This does not modify the disk image; you must save the tar file itself
1025 for this to be permanent."
1026   (interactive (list (tar-parse-octal-integer-safe
1027                        (read-string "New protection (octal): "))))
1028   (tar-setf (tar-header-mode (tar-desc-tokens (tar-current-descriptor)))
1029             new-mode)
1030   (tar-alter-one-field tar-mode-offset
1031     (concat (substring (format "%6o" new-mode) 0 6) "\000 ")))
1032
1033
1034 (defun tar-alter-one-field (data-position new-data-string)
1035   (let* ((descriptor (tar-current-descriptor))
1036          (tokens (tar-desc-tokens descriptor))
1037          (multibyte enable-multibyte-characters))
1038     (unwind-protect
1039         (save-excursion
1040           ;;
1041           ;; update the header-line.
1042           (beginning-of-line)
1043           (let ((p (point)))
1044             (forward-line 1)
1045             (delete-region p (point))
1046             (insert (tar-header-block-summarize tokens) "\n")
1047             (setq tar-header-offset (position-bytes (point-max))))
1048
1049           (widen)
1050           (set-buffer-multibyte nil)
1051           (let* ((start (+ (tar-desc-data-start descriptor) tar-header-offset -513)))
1052             ;;
1053             ;; delete the old field and insert a new one.
1054             (goto-char (+ start data-position))
1055             (delete-region (point) (+ (point) (length new-data-string))) ; <--
1056             (insert new-data-string) ; <--
1057             ;;
1058             ;; compute a new checksum and insert it.
1059             (let ((chk (tar-header-block-checksum
1060                         (buffer-substring start (+ start 512)))))
1061               (goto-char (+ start tar-chk-offset))
1062               (delete-region (point) (+ (point) 8))
1063               (insert (format "%6o" chk))
1064               (insert 0)
1065               (insert ? )
1066               (tar-setf (tar-header-checksum tokens) chk)
1067               ;;
1068               ;; ok, make sure we didn't botch it.
1069               (tar-header-block-check-checksum
1070                 (buffer-substring start (+ start 512))
1071                 chk (tar-header-name tokens))
1072               )))
1073       (narrow-to-region 1 tar-header-offset)
1074       (set-buffer-multibyte multibyte)
1075       (tar-next-line 0))))
1076
1077
1078 (defun tar-octal-time (timeval)
1079   ;; Format a timestamp as 11 octal digits.  Ghod, I hope this works...
1080   (let ((hibits (car timeval)) (lobits (car (cdr timeval))))
1081     (insert (format "%05o%01o%05o"
1082                     (lsh hibits -2)
1083                     (logior (lsh (logand 3 hibits) 1) (> (logand lobits 32768) 0))
1084                     (logand 32767 lobits)
1085                     ))))
1086
1087 (defun tar-subfile-save-buffer ()
1088   "In tar subfile mode, save this buffer into its parent tar-file buffer.
1089 This doesn't write anything to disk; you must save the parent tar-file buffer
1090 to make your changes permanent."
1091   (interactive)
1092   (if (not (and (boundp 'tar-superior-buffer) tar-superior-buffer))
1093     (error "This buffer has no superior tar file buffer"))
1094   (if (not (and (boundp 'tar-superior-descriptor) tar-superior-descriptor))
1095     (error "This buffer doesn't have an index into its superior tar file!"))
1096   (save-excursion
1097   (let ((subfile (current-buffer))
1098         (subfile-multibyte enable-multibyte-characters)
1099         (coding buffer-file-coding-system)
1100         (descriptor tar-superior-descriptor)
1101         subfile-size)
1102     ;; We must make the current buffer unibyte temporarily to avoid
1103     ;; multibyte->unibyte conversion in `insert-buffer'.
1104     (set-buffer-multibyte nil)
1105     (setq subfile-size (buffer-size))
1106     (set-buffer tar-superior-buffer)
1107     (let* ((tokens (tar-desc-tokens descriptor))
1108            (start (tar-desc-data-start descriptor))
1109            (name (tar-header-name tokens))
1110            (size (tar-header-size tokens))
1111            (size-pad (ash (ash (+ size 511) -9) 9))
1112            (head (memq descriptor tar-parse-info))
1113            (following-descs (cdr head))
1114            (tar-buffer-multibyte enable-multibyte-characters))
1115       (if (not head)
1116         (error "Can't find this tar file entry in its parent tar file!"))
1117       (unwind-protect
1118        (save-excursion
1119         (widen)
1120         (set-buffer-multibyte nil)
1121         ;; delete the old data...
1122         (let* ((data-start (+ start tar-header-offset -1))
1123                (data-end (+ data-start (ash (ash (+ size 511) -9) 9))))
1124           (delete-region data-start data-end)
1125           ;; insert the new data...
1126           (goto-char data-start)
1127           (insert-buffer subfile)
1128           (setq subfile-size
1129                 (encode-coding-region
1130                  data-start (+ data-start subfile-size) coding))
1131           ;;
1132           ;; pad the new data out to a multiple of 512...
1133           (let ((subfile-size-pad (ash (ash (+ subfile-size 511) -9) 9)))
1134             (goto-char (+ data-start subfile-size))
1135             (insert (make-string (- subfile-size-pad subfile-size) 0))
1136             ;;
1137             ;; update the data pointer of this and all following files...
1138             (tar-setf (tar-header-size tokens) subfile-size)
1139             (let ((difference (- subfile-size-pad size-pad)))
1140               (dolist (desc following-descs)
1141                 (tar-setf (tar-desc-data-start desc)
1142                           (+ (tar-desc-data-start desc) difference))))
1143             ;;
1144             ;; Update the size field in the header block.
1145             (let ((header-start (- data-start 512)))
1146               (goto-char (+ header-start tar-size-offset))
1147               (delete-region (point) (+ (point) 12))
1148               (insert (format "%11o" subfile-size))
1149               (insert ? )
1150               ;;
1151               ;; Maybe update the datestamp.
1152               (if (not tar-update-datestamp)
1153                   nil
1154                 (goto-char (+ header-start tar-time-offset))
1155                 (delete-region (point) (+ (point) 12))
1156                 (insert (tar-octal-time (current-time)))
1157                 (insert ? ))
1158               ;;
1159               ;; compute a new checksum and insert it.
1160               (let ((chk (tar-header-block-checksum
1161                           (buffer-substring header-start data-start))))
1162                 (goto-char (+ header-start tar-chk-offset))
1163                 (delete-region (point) (+ (point) 8))
1164                 (insert (format "%6o" chk))
1165                 (insert 0)
1166                 (insert ? )
1167                 (tar-setf (tar-header-checksum tokens) chk)))
1168             ;;
1169             ;; alter the descriptor-line...
1170             ;;
1171             (let ((position (- (length tar-parse-info) (length head))))
1172               (goto-char (point-min))
1173               (next-line position)
1174               (beginning-of-line)
1175               (let ((p (point))
1176                     after
1177                     (m (set-marker (make-marker) tar-header-offset)))
1178                 (forward-line 1)
1179                 (setq after (point))
1180                 ;; Insert the new text after the old, before deleting,
1181                 ;; to preserve the window start.
1182                 (let ((line (tar-header-block-summarize tokens t)))
1183                   (if (multibyte-string-p line)
1184                       (insert-before-markers (string-as-unibyte line) "\n")
1185                     (insert-before-markers line "\n")))
1186                 (delete-region p after)
1187                 (setq tar-header-offset (marker-position m)))
1188               )))
1189         ;; after doing the insertion, add any final padding that may be necessary.
1190         (tar-pad-to-blocksize))
1191        (narrow-to-region 1 tar-header-offset)
1192        (set-buffer-multibyte tar-buffer-multibyte)))
1193     (set-buffer-modified-p t)   ; mark the tar file as modified
1194     (tar-next-line 0)
1195     (set-buffer subfile)
1196     ;; Restore the buffer multibyteness.
1197     (set-buffer-multibyte subfile-multibyte)
1198     (set-buffer-modified-p nil) ; mark the tar subfile as unmodified
1199     (message "Saved into tar-buffer `%s'.  Be sure to save that buffer!"
1200              (buffer-name tar-superior-buffer))
1201     ;; Prevent basic-save-buffer from changing our coding-system.
1202     (setq last-coding-system-used buffer-file-coding-system)
1203     ;; Prevent ordinary saving from happening.
1204     t)))
1205
1206
1207 ;; When this function is called, it is sure that the buffer is unibyte.
1208 (defun tar-pad-to-blocksize ()
1209   "If we are being anal about tar file blocksizes, fix up the current buffer.
1210 Leaves the region wide."
1211   (if (null tar-anal-blocksize)
1212       nil
1213     (widen)
1214     (let* ((last-desc (nth (1- (length tar-parse-info)) tar-parse-info))
1215            (start (tar-desc-data-start last-desc))
1216            (tokens (tar-desc-tokens last-desc))
1217            (link-p (tar-header-link-type tokens))
1218            (size (if link-p 0 (tar-header-size tokens)))
1219            (data-end (+ start size))
1220            (bbytes (ash tar-anal-blocksize 9))
1221            (pad-to (+ bbytes (* bbytes (/ (1- data-end) bbytes))))
1222            (inhibit-read-only t) ; ##
1223            )
1224       ;; If the padding after the last data is too long, delete some;
1225       ;; else insert some until we are padded out to the right number of blocks.
1226       ;;
1227       (goto-char (+ (or tar-header-offset 0) data-end))
1228       (if (> (1+ (buffer-size)) (+ (or tar-header-offset 0) pad-to))
1229           (delete-region (+ (or tar-header-offset 0) pad-to) (1+ (buffer-size)))
1230           (insert (make-string (- (+ (or tar-header-offset 0) pad-to)
1231                                   (1+ (buffer-size)))
1232                                0)))
1233       )))
1234
1235
1236 ;; Used in write-file-hook to write tar-files out correctly.
1237 (defun tar-mode-write-file ()
1238   (unwind-protect
1239       (save-excursion
1240         (widen)
1241         ;; Doing this here confuses things - the region gets left too wide!
1242         ;; I suppose this is run in a context where changing the buffer is bad.
1243         ;; (tar-pad-to-blocksize)
1244         ;; tar-header-offset turns out to be null for files fetched with W3,
1245         ;; at least.
1246         (let ((coding-system-for-write 'no-conversion))
1247           (write-region (or (byte-to-position tar-header-offset)
1248                             (point-min))
1249                         (point-max)
1250                         buffer-file-name nil t))
1251         (tar-clear-modification-flags)
1252         (set-buffer-modified-p nil))
1253     (narrow-to-region 1 (byte-to-position tar-header-offset)))
1254   ;; Return t because we've written the file.
1255   t)
1256 \f
1257 (provide 'tar-mode)
1258
1259 ;;; tar-mode.el ends here