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 ;;; First, duplicate some Common Lisp functions; I used to just (require 'cl)
 143 ;;; but "cl.el" was messing some people up (also it's really big).
 144
 145 (defmacro tar-setf (form val)
 146   "A mind-numbingly simple implementation of setf."
 147   (let ((mform (macroexpand form (and (boundp 'byte-compile-macro-environment)
 148                                       byte-compile-macro-environment))))
 149     (cond ((symbolp mform) (list 'setq mform val))
 150           ((not (consp mform)) (error "can't setf %s" form))
 151           ((eq (car mform) 'aref)
 152            (list 'aset (nth 1 mform) (nth 2 mform) val))
 153           ((eq (car mform) 'car)
 154            (list 'setcar (nth 1 mform) val))
 155           ((eq (car mform) 'cdr)
 156            (list 'setcdr (nth 1 mform) val))
 157           (t (error "don't know how to setf %s" form)))))
 158
 159 (defmacro tar-dolist (control &rest body)
 160   "syntax: (dolist (var-name list-expr &optional return-value) &body body)"
 161   (let ((var (car control))
 162         (init (car (cdr control)))
 163         (val (car (cdr (cdr control)))))
 164     (list 'let (list (list '_dolist_iterator_ init))
 165           (list 'while '_dolist_iterator_
 166             (cons 'let
 167               (cons (list (list var '(car _dolist_iterator_)))
 168                     (append body
 169                             (list (list 'setq '_dolist_iterator_
 170                                         (list 'cdr '_dolist_iterator_)))))))
 171           val)))
 172
 173 (defmacro tar-dotimes (control &rest body)
 174   "syntax: (dolist (var-name count-expr &optional return-value) &body body)"
 175   (let ((var (car control))
 176         (n (car (cdr control)))
 177         (val (car (cdr (cdr control)))))
 178     (list 'let (list (list '_dotimes_end_ n)
 179                      (list var 0))
 180           (cons 'while
 181                 (cons (list '< var '_dotimes_end_)
 182                       (append body
 183                               (list (list 'setq var (list '1+ var))))))
 184           val)))
 185
 186 \f
 187 ;;; down to business.
 188
 189 (defmacro make-tar-header (name mode uid git size date ck lt ln
 190                            magic uname gname devmaj devmin)
 191   (list 'vector name mode uid git size date ck lt ln
 192         magic uname gname devmaj devmin))
 193
 194 (defmacro tar-header-name (x) (list 'aref x 0))
 195 (defmacro tar-header-mode (x) (list 'aref x 1))
 196 (defmacro tar-header-uid  (x) (list 'aref x 2))
 197 (defmacro tar-header-gid  (x) (list 'aref x 3))
 198 (defmacro tar-header-size (x) (list 'aref x 4))
 199 (defmacro tar-header-date (x) (list 'aref x 5))
 200 (defmacro tar-header-checksum  (x) (list 'aref x 6))
 201 (defmacro tar-header-link-type (x) (list 'aref x 7))
 202 (defmacro tar-header-link-name (x) (list 'aref x 8))
 203 (defmacro tar-header-magic (x) (list 'aref x 9))
 204 (defmacro tar-header-uname (x) (list 'aref x 10))
 205 (defmacro tar-header-gname (x) (list 'aref x 11))
 206 (defmacro tar-header-dmaj (x) (list 'aref x 12))
 207 (defmacro tar-header-dmin (x) (list 'aref x 13))
 208
 209 (defmacro make-tar-desc (data-start tokens)
 210   (list 'cons data-start tokens))
 211
 212 (defmacro tar-desc-data-start (x) (list 'car x))
 213 (defmacro tar-desc-tokens     (x) (list 'cdr x))
 214
 215 (defconst tar-name-offset 0)
 216 (defconst tar-mode-offset (+ tar-name-offset 100))
 217 (defconst tar-uid-offset  (+ tar-mode-offset 8))
 218 (defconst tar-gid-offset  (+ tar-uid-offset 8))
 219 (defconst tar-size-offset (+ tar-gid-offset 8))
 220 (defconst tar-time-offset (+ tar-size-offset 12))
 221 (defconst tar-chk-offset  (+ tar-time-offset 12))
 222 (defconst tar-linkp-offset (+ tar-chk-offset 8))
 223 (defconst tar-link-offset (+ tar-linkp-offset 1))
 224 ;;; GNU-tar specific slots.
 225 (defconst tar-magic-offset (+ tar-link-offset 100))
 226 (defconst tar-uname-offset (+ tar-magic-offset 8))
 227 (defconst tar-gname-offset (+ tar-uname-offset 32))
 228 (defconst tar-dmaj-offset (+ tar-gname-offset 32))
 229 (defconst tar-dmin-offset (+ tar-dmaj-offset 8))
 230 (defconst tar-end-offset (+ tar-dmin-offset 8))
 231
 232 (defun tar-header-block-tokenize (string)
 233   "Return a `tar-header' structure.
 234 This is a list of name, mode, uid, gid, size,
 235 write-date, checksum, link-type, and link-name."
 236   (cond ((< (length string) 512) nil)
 237         (;(some 'plusp string)           ; <-- oops, massive cycle hog!
 238          (or (not (= 0 (aref string 0))) ; This will do.
 239              (not (= 0 (aref string 101))))
 240          (let* ((name-end (1- tar-mode-offset))
 241                 (link-end (1- tar-magic-offset))
 242                 (uname-end (1- tar-gname-offset))
 243                 (gname-end (1- tar-dmaj-offset))
 244                 (link-p (aref string tar-linkp-offset))
 245                 (magic-str (substring string tar-magic-offset (1- tar-uname-offset)))
 246                 (uname-valid-p (or (string= "ustar  " magic-str) (string= "GNUtar " magic-str)))
 247                 name linkname
 248                 (nulsexp   "[^\000]*\000"))
 249            (when (string-match nulsexp string tar-name-offset)
 250              (setq name-end (min name-end (1- (match-end 0)))))
 251            (when (string-match nulsexp string tar-link-offset)
 252              (setq link-end (min link-end (1- (match-end 0)))))
 253            (when (string-match nulsexp string tar-uname-offset)
 254              (setq uname-end (min uname-end (1- (match-end 0)))))
 255            (when (string-match nulsexp string tar-gname-offset)
 256              (setq gname-end (min gname-end (1- (match-end 0)))))
 257            (setq name (substring string tar-name-offset name-end)
 258                  link-p (if (or (= link-p 0) (= link-p ?0))
 259                             nil
 260                           (- link-p ?0)))
 261            (setq linkname (substring string tar-link-offset link-end))
 262            (if default-enable-multibyte-characters
 263                (setq name
 264                      (decode-coding-string name (or file-name-coding-system
 265                                                     'undecided))
 266                      linkname
 267                      (decode-coding-string linkname (or file-name-coding-system
 268                                                         'undecided))))
 269            (if (and (null link-p) (string-match "/$" name)) (setq link-p 5)) ; directory
 270            (make-tar-header
 271              name
 272              (tar-parse-octal-integer string tar-mode-offset tar-uid-offset)
 273              (tar-parse-octal-integer string tar-uid-offset tar-gid-offset)
 274              (tar-parse-octal-integer string tar-gid-offset tar-size-offset)
 275              (tar-parse-octal-integer string tar-size-offset tar-time-offset)
 276              (tar-parse-octal-long-integer string tar-time-offset tar-chk-offset)
 277              (tar-parse-octal-integer string tar-chk-offset tar-linkp-offset)
 278              link-p
 279              linkname
 280              uname-valid-p
 281              (and uname-valid-p (substring string tar-uname-offset uname-end))
 282              (and uname-valid-p (substring string tar-gname-offset gname-end))
 283              (tar-parse-octal-integer string tar-dmaj-offset tar-dmin-offset)
 284              (tar-parse-octal-integer string tar-dmin-offset tar-end-offset)
 285              )))
 286         (t 'empty-tar-block)))
 287
 288
 289 (defun tar-parse-octal-integer (string &optional start end)
 290   (if (null start) (setq start 0))
 291   (if (null end) (setq end (length string)))
 292   (if (= (aref string start) 0)
 293       0
 294     (let ((n 0))
 295       (while (< start end)
 296         (setq n (if (< (aref string start) ?0) n
 297                   (+ (* n 8) (- (aref string start) ?0)))
 298               start (1+ start)))
 299       n)))
 300
 301 (defun tar-parse-octal-long-integer (string &optional start end)
 302   (if (null start) (setq start 0))
 303   (if (null end) (setq end (length string)))
 304   (if (= (aref string start) 0)
 305       (list 0 0)
 306     (let ((lo 0)
 307           (hi 0))
 308       (while (< start end)
 309         (if (>= (aref string start) ?0)
 310             (setq lo (+ (* lo 8) (- (aref string start) ?0))
 311                   hi (+ (* hi 8) (ash lo -16))
 312                   lo (logand lo 65535)))
 313         (setq start (1+ start)))
 314       (list hi lo))))
 315
 316 (defun tar-parse-octal-integer-safe (string)
 317   (let ((L (length string)))
 318     (if (= L 0) (error "empty string"))
 319     (tar-dotimes (i L)
 320        (if (or (< (aref string i) ?0)
 321                (> (aref string i) ?7))
 322            (error "`%c' is not an octal digit"))))
 323   (tar-parse-octal-integer string))
 324
 325
 326 (defun tar-header-block-checksum (string)
 327   "Compute and return a tar-acceptable checksum for this block."
 328   (let* ((chk-field-start tar-chk-offset)
 329          (chk-field-end (+ chk-field-start 8))
 330          (sum 0)
 331          (i 0))
 332     ;; Add up all of the characters except the ones in the checksum field.
 333     ;; Add that field as if it were filled with spaces.
 334     (while (< i chk-field-start)
 335       (setq sum (+ sum (aref string i))
 336             i (1+ i)))
 337     (setq i chk-field-end)
 338     (while (< i 512)
 339       (setq sum (+ sum (aref string i))
 340             i (1+ i)))
 341     (+ sum (* 32 8))))
 342
 343 (defun tar-header-block-check-checksum (hblock desired-checksum file-name)
 344   "Beep and print a warning if the checksum doesn't match."
 345   (if (not (= desired-checksum (tar-header-block-checksum hblock)))
 346       (progn (beep) (message "Invalid checksum for file %s!" file-name))))
 347
 348 (defun tar-header-block-recompute-checksum (hblock)
 349   "Modifies the given string to have a valid checksum field."
 350   (let* ((chk (tar-header-block-checksum hblock))
 351          (chk-string (format "%6o" chk))
 352          (l (length chk-string)))
 353     (aset hblock 154 0)
 354     (aset hblock 155 32)
 355     (tar-dotimes (i l) (aset hblock (- 153 i) (aref chk-string (- l i 1)))))
 356   hblock)
 357
 358 (defun tar-clip-time-string (time)
 359   (let ((str (current-time-string time)))
 360     (concat (substring str 4 16) (substring str 19 24))))
 361
 362 (defun tar-grind-file-mode (mode string start)
 363   "Store `-rw--r--r--' indicating MODE into STRING beginning at START.
 364 MODE should be an integer which is a file mode value."
 365   (aset string start       (if (zerop (logand 256 mode)) ?- ?r))
 366   (aset string (+ start 1) (if (zerop (logand 128 mode)) ?- ?w))
 367   (aset string (+ start 2) (if (zerop (logand  64 mode)) ?- ?x))
 368   (aset string (+ start 3) (if (zerop (logand  32 mode)) ?- ?r))
 369   (aset string (+ start 4) (if (zerop (logand  16 mode)) ?- ?w))
 370   (aset string (+ start 5) (if (zerop (logand   8 mode)) ?- ?x))
 371   (aset string (+ start 6) (if (zerop (logand   4 mode)) ?- ?r))
 372   (aset string (+ start 7) (if (zerop (logand   2 mode)) ?- ?w))
 373   (aset string (+ start 8) (if (zerop (logand   1 mode)) ?- ?x))
 374   (if (zerop (logand 1024 mode)) nil (aset string (+ start 2) ?s))
 375   (if (zerop (logand 2048 mode)) nil (aset string (+ start 5) ?s))
 376   string)
 377
 378 (defun tar-header-block-summarize (tar-hblock &optional mod-p)
 379   "Returns a line similar to the output of `tar -vtf'."
 380   (let ((name (tar-header-name tar-hblock))
 381         (mode (tar-header-mode tar-hblock))
 382         (uid (tar-header-uid tar-hblock))
 383         (gid (tar-header-gid tar-hblock))
 384         (uname (tar-header-uname tar-hblock))
 385         (gname (tar-header-gname tar-hblock))
 386         (size (tar-header-size tar-hblock))
 387         (time (tar-header-date tar-hblock))
 388         (ck (tar-header-checksum tar-hblock))
 389         (link-p (tar-header-link-type tar-hblock))
 390         (link-name (tar-header-link-name tar-hblock))
 391         )
 392     (let* ((left 11)
 393            (namew 8)
 394            (groupw 8)
 395            (sizew 8)
 396            (datew (if tar-mode-show-date 18 0))
 397            (slash (1- (+ left namew)))
 398            (lastdigit (+ slash groupw sizew))
 399            (datestart (+ lastdigit 2))
 400            (namestart (+ datestart datew))
 401            (multibyte (or (multibyte-string-p name)
 402                           (multibyte-string-p link-name)))
 403            ;; If multibyte, we can't use optimized method of aset,
 404            ;; instead we must use concat.
 405            (string (make-string (if multibyte
 406                                     namestart
 407                                   (+ namestart
 408                                      (length name)
 409                                      (if link-p (+ 5 (length link-name)) 0)))
 410                                 32))
 411            (type (tar-header-link-type tar-hblock)))
 412       (aset string 0 (if mod-p ?* ? ))
 413       (aset string 1
 414             (cond ((or (eq type nil) (eq type 0)) ?-)
 415                   ((eq type 1) ?l)  ; link
 416                   ((eq type 2) ?s)  ; symlink
 417                   ((eq type 3) ?c)  ; char special
 418                   ((eq type 4) ?b)  ; block special
 419                   ((eq type 5) ?d)  ; directory
 420                   ((eq type 6) ?p)  ; FIFO/pipe
 421                   ((eq type 20) ?*) ; directory listing
 422                   ((eq type 29) ?M) ; multivolume continuation
 423                   ((eq type 35) ?S) ; sparse
 424                   ((eq type 38) ?V) ; volume header
 425                   ))
 426       (tar-grind-file-mode mode string 2)
 427       (setq uid (if (= 0 (length uname)) (int-to-string uid) uname))
 428       (setq gid (if (= 0 (length gname)) (int-to-string gid) gname))
 429       (setq size (int-to-string size))
 430       (setq time (tar-clip-time-string time))
 431       (tar-dotimes (i (min (1- namew) (length uid))) (aset string (- slash i) (aref uid (- (length uid) i 1))))
 432       (aset string (1+ slash) ?/)
 433       (tar-dotimes (i (min (1- groupw) (length gid))) (aset string (+ (+ slash 2) i) (aref gid i)))
 434       (tar-dotimes (i (min sizew (length size))) (aset string (- lastdigit i) (aref size (- (length size) i 1))))
 435       (if tar-mode-show-date
 436           (tar-dotimes (i (length time)) (aset string (+ datestart i) (aref time i))))
 437       (if multibyte
 438           (setq string (concat string name))
 439         (tar-dotimes (i (length name)) (aset string (+ namestart i) (aref name i))))
 440       (if (or (eq link-p 1) (eq link-p 2))
 441           (if multibyte
 442               (setq string (concat string
 443                                    (if (= link-p 1) " ==> " " --> ")
 444                                    link-name))
 445             (tar-dotimes (i 3) (aset string (+ namestart 1 (length name) i) (aref (if (= link-p 1) "==>" "-->") i)))
 446             (tar-dotimes (i (length link-name)) (aset string (+ namestart 5 (length name) i) (aref link-name i)))))
 447       (put-text-property namestart (length string)
 448                          'mouse-face 'highlight string)
 449       string)))
 450
 451
 452 (defun tar-summarize-buffer ()
 453   "Parse the contents of the tar file in the current buffer.
 454 Place a dired-like listing on the front;
 455 then narrow to it, so that only that listing
 456 is visible (and the real data of the buffer is hidden)."
 457   (set-buffer-multibyte nil)
 458   (message "Parsing tar file...")
 459   (let* ((result '())
 460          (pos 1)
 461          (bs (max 1 (- (buffer-size) 1024))) ; always 2+ empty blocks at end.
 462          (bs100 (max 1 (/ bs 100)))
 463          tokens)
 464     (while (and (<= (+ pos 512) (point-max))
 465                 (not (eq 'empty-tar-block
 466                          (setq tokens
 467                                (tar-header-block-tokenize
 468                                 (buffer-substring pos (+ pos 512)))))))
 469       (setq pos (+ pos 512))
 470       (message "Parsing tar file...%d%%"
 471                ;(/ (* pos 100) bs)   ; this gets round-off lossage
 472                (/ pos bs100)         ; this doesn't
 473                )
 474       (if (eq (tar-header-link-type tokens) 20)
 475           ;; Foo.  There's an extra empty block after these.
 476           (setq pos (+ pos 512)))
 477       (let ((size (tar-header-size tokens)))
 478         (if (< size 0)
 479             (error "%s has size %s - corrupted"
 480                    (tar-header-name tokens) size))
 481         ;
 482         ; This is just too slow.  Don't really need it anyway....
 483         ;(tar-header-block-check-checksum
 484         ;  hblock (tar-header-block-checksum hblock)
 485         ;  (tar-header-name tokens))
 486
 487         (setq result (cons (make-tar-desc pos tokens) result))
 488
 489         (and (null (tar-header-link-type tokens))
 490              (> size 0)
 491              (setq pos
 492                    (+ pos 512 (ash (ash (1- size) -9) 9))        ; this works
 493                    ;(+ pos (+ size (- 512 (rem (1- size) 512)))) ; this doesn't
 494                    ))))
 495     (make-local-variable 'tar-parse-info)
 496     (setq tar-parse-info (nreverse result))
 497     ;; A tar file should end with a block or two of nulls,
 498     ;; but let's not get a fatal error if it doesn't.
 499     (if (eq tokens 'empty-tar-block)
 500         (message "Parsing tar file...done")
 501       (message "Warning: premature EOF parsing tar file")))
 502   (save-excursion
 503     (goto-char (point-min))
 504     (let ((buffer-read-only nil)
 505           (summaries nil))
 506       ;; Collect summary lines and insert them all at once since tar files
 507       ;; can be pretty big.
 508       (tar-dolist (tar-desc (reverse tar-parse-info))
 509         (setq summaries
 510               (cons (tar-header-block-summarize (tar-desc-tokens tar-desc))
 511                     (cons "\n"
 512                           summaries))))
 513       (let ((total-summaries (apply 'concat summaries)))
 514         (if (multibyte-string-p total-summaries)
 515             (set-buffer-multibyte t))
 516         (insert total-summaries))
 517       (make-local-variable 'tar-header-offset)
 518       (setq tar-header-offset (point))
 519       (narrow-to-region 1 tar-header-offset)
 520       (if enable-multibyte-characters
 521           (setq tar-header-offset (position-bytes tar-header-offset)))
 522       (set-buffer-modified-p nil))))
 523 \f
 524 (defvar tar-mode-map nil "*Local keymap for Tar mode listings.")
 525
 526 (if tar-mode-map
 527     nil
 528   (setq tar-mode-map (make-keymap))
 529   (suppress-keymap tar-mode-map)
 530   (define-key tar-mode-map " " 'tar-next-line)
 531   (define-key tar-mode-map "C" 'tar-copy)
 532   (define-key tar-mode-map "d" 'tar-flag-deleted)
 533   (define-key tar-mode-map "\^D" 'tar-flag-deleted)
 534   (define-key tar-mode-map "e" 'tar-extract)
 535   (define-key tar-mode-map "f" 'tar-extract)
 536   (define-key tar-mode-map "\C-m" 'tar-extract)
 537   (define-key tar-mode-map [mouse-2] 'tar-mouse-extract)
 538   (define-key tar-mode-map "g" 'revert-buffer)
 539   (define-key tar-mode-map "h" 'describe-mode)
 540   (define-key tar-mode-map "n" 'tar-next-line)
 541   (define-key tar-mode-map "\^N" 'tar-next-line)
 542   (define-key tar-mode-map [down] 'tar-next-line)
 543   (define-key tar-mode-map "o" 'tar-extract-other-window)
 544   (define-key tar-mode-map "p" 'tar-previous-line)
 545   (define-key tar-mode-map "q" 'quit-window)
 546   (define-key tar-mode-map "\^P" 'tar-previous-line)
 547   (define-key tar-mode-map [up] 'tar-previous-line)
 548   (define-key tar-mode-map "R" 'tar-rename-entry)
 549   (define-key tar-mode-map "u" 'tar-unflag)
 550   (define-key tar-mode-map "v" 'tar-view)
 551   (define-key tar-mode-map "x" 'tar-expunge)
 552   (define-key tar-mode-map "\177" 'tar-unflag-backwards)
 553   (define-key tar-mode-map "E" 'tar-extract-other-window)
 554   (define-key tar-mode-map "M" 'tar-chmod-entry)
 555   (define-key tar-mode-map "G" 'tar-chgrp-entry)
 556   (define-key tar-mode-map "O" 'tar-chown-entry)
 557   )
 558 \f
 559 ;; Make menu bar items.
 560
 561 ;; Get rid of the Edit menu bar item to save space.
 562 (define-key tar-mode-map [menu-bar edit] 'undefined)
 563
 564 (define-key tar-mode-map [menu-bar immediate]
 565   (cons "Immediate" (make-sparse-keymap "Immediate")))
 566
 567 (define-key tar-mode-map [menu-bar immediate view]
 568   '("View This File" . tar-view))
 569 (define-key tar-mode-map [menu-bar immediate display]
 570   '("Display in Other Window" . tar-display-other-window))
 571 (define-key tar-mode-map [menu-bar immediate find-file-other-window]
 572   '("Find in Other Window" . tar-extract-other-window))
 573 (define-key tar-mode-map [menu-bar immediate find-file]
 574   '("Find This File" . tar-extract))
 575
 576 (define-key tar-mode-map [menu-bar mark]
 577   (cons "Mark" (make-sparse-keymap "Mark")))
 578
 579 (define-key tar-mode-map [menu-bar mark unmark-all]
 580   '("Unmark All" . tar-clear-modification-flags))
 581 (define-key tar-mode-map [menu-bar mark deletion]
 582   '("Flag" . tar-flag-deleted))
 583 (define-key tar-mode-map [menu-bar mark unmark]
 584   '("Unflag" . tar-unflag))
 585
 586 (define-key tar-mode-map [menu-bar operate]
 587   (cons "Operate" (make-sparse-keymap "Operate")))
 588
 589 (define-key tar-mode-map [menu-bar operate chown]
 590   '("Change Owner..." . tar-chown-entry))
 591 (define-key tar-mode-map [menu-bar operate chgrp]
 592   '("Change Group..." . tar-chgrp-entry))
 593 (define-key tar-mode-map [menu-bar operate chmod]
 594   '("Change Mode..." . tar-chmod-entry))
 595 (define-key tar-mode-map [menu-bar operate rename]
 596   '("Rename to..." . tar-rename-entry))
 597 (define-key tar-mode-map [menu-bar operate copy]
 598   '("Copy to..." . tar-copy))
 599 (define-key tar-mode-map [menu-bar operate expunge]
 600   '("Expunge Marked Files" . tar-expunge))
 601 \f
 602 ;; tar mode is suitable only for specially formatted data.
 603 (put 'tar-mode 'mode-class 'special)
 604 (put 'tar-subfile-mode 'mode-class 'special)
 605
 606 ;;;###autoload
 607 (defun tar-mode ()
 608   "Major mode for viewing a tar file as a dired-like listing of its contents.
 609 You can move around using the usual cursor motion commands.
 610 Letters no longer insert themselves.
 611 Type `e' to pull a file out of the tar file and into its own buffer;
 612 or click mouse-2 on the file's line in the Tar mode buffer.
 613 Type `c' to copy an entry from the tar file into another file on disk.
 614
 615 If you edit a sub-file of this archive (as with the `e' command) and
 616 save it with Control-x Control-s, the contents of that buffer will be
 617 saved back into the tar-file buffer; in this way you can edit a file
 618 inside of a tar archive without extracting it and re-archiving it.
 619
 620 See also: variables `tar-update-datestamp' and `tar-anal-blocksize'.
 621 \\{tar-mode-map}"
 622   ;; this is not interactive because you shouldn't be turning this
 623   ;; mode on and off.  You can corrupt things that way.
 624   ;; rms: with permanent locals, it should now be possible to make this work
 625   ;; interactively in some reasonable fashion.
 626   (kill-all-local-variables)
 627   (make-local-variable 'tar-header-offset)
 628   (make-local-variable 'tar-parse-info)
 629   (make-local-variable 'require-final-newline)
 630   (setq require-final-newline nil) ; binary data, dude...
 631   (make-local-variable 'revert-buffer-function)
 632   (setq revert-buffer-function 'tar-mode-revert)
 633   (make-local-variable 'local-enable-local-variables)
 634   (setq local-enable-local-variables nil)
 635   (make-local-variable 'next-line-add-newlines)
 636   (setq next-line-add-newlines nil)
 637   ;; Prevent loss of data when saving the file.
 638   (make-local-variable 'file-precious-flag)
 639   (setq file-precious-flag t)
 640   (setq major-mode 'tar-mode)
 641   (setq mode-name "Tar")
 642   (use-local-map tar-mode-map)
 643   (auto-save-mode 0)
 644   (make-local-variable 'write-contents-hooks)
 645   (setq write-contents-hooks '(tar-mode-write-file))
 646   (widen)
 647   (if (and (boundp 'tar-header-offset) tar-header-offset)
 648       (narrow-to-region 1 (byte-to-position tar-header-offset))
 649       (tar-summarize-buffer)
 650       (tar-next-line 0))
 651   (run-hooks 'tar-mode-hook)
 652   )
 653
 654
 655 (defun tar-subfile-mode (p)
 656   "Minor mode for editing an element of a tar-file.
 657 This mode arranges for \"saving\" this buffer to write the data
 658 into the tar-file buffer that it came from.  The changes will actually
 659 appear on disk when you save the tar-file's buffer."
 660   (interactive "P")
 661   (or (and (boundp 'tar-superior-buffer) tar-superior-buffer)
 662       (error "This buffer is not an element of a tar file"))
 663 ;;; Don't do this, because it is redundant and wastes mode line space.
 664 ;;;  (or (assq 'tar-subfile-mode minor-mode-alist)
 665 ;;;      (setq minor-mode-alist (append minor-mode-alist
 666 ;;;                                  (list '(tar-subfile-mode " TarFile")))))
 667   (make-local-variable 'tar-subfile-mode)
 668   (setq tar-subfile-mode
 669         (if (null p)
 670             (not tar-subfile-mode)
 671             (> (prefix-numeric-value p) 0)))
 672   (cond (tar-subfile-mode
 673          (make-local-variable 'local-write-file-hooks)
 674          (setq local-write-file-hooks '(tar-subfile-save-buffer))
 675          ;; turn off auto-save.
 676          (auto-save-mode -1)
 677          (setq buffer-auto-save-file-name nil)
 678          (run-hooks 'tar-subfile-mode-hook))
 679         (t
 680          (kill-local-variable 'local-write-file-hooks))))
 681
 682
 683 ;; Revert the buffer and recompute the dired-like listing.
 684 (defun tar-mode-revert (&optional no-auto-save no-confirm)
 685   (let ((revert-buffer-function nil)
 686         (old-offset tar-header-offset)
 687         success)
 688     (setq tar-header-offset nil)
 689     (unwind-protect
 690         (and (revert-buffer t no-confirm)
 691              (progn (widen)
 692                     (setq success t)
 693                     (tar-mode)))
 694       ;; If the revert was canceled,
 695       ;; put back the old value of tar-header-offset.
 696       (or success
 697           (setq tar-header-offset old-offset)))))
 698
 699
 700 (defun tar-next-line (p)
 701   (interactive "p")
 702   (forward-line p)
 703   (if (eobp) nil (forward-char (if tar-mode-show-date 54 36))))
 704
 705 (defun tar-previous-line (p)
 706   (interactive "p")
 707   (tar-next-line (- p)))
 708
 709 (defun tar-current-descriptor (&optional noerror)
 710   "Return the tar-descriptor of the current line, or signals an error."
 711   ;; I wish lines had plists, like in ZMACS...
 712   (or (nth (count-lines (point-min)
 713                         (save-excursion (beginning-of-line) (point)))
 714            tar-parse-info)
 715       (if noerror
 716           nil
 717           (error "This line does not describe a tar-file entry"))))
 718
 719 (defun tar-get-descriptor ()
 720   (let* ((descriptor (tar-current-descriptor))
 721          (tokens (tar-desc-tokens descriptor))
 722          (size (tar-header-size tokens))
 723          (link-p (tar-header-link-type tokens)))
 724     (if link-p
 725         (error "This is a %s, not a real file"
 726                (cond ((eq link-p 5) "directory")
 727                      ((eq link-p 20) "tar directory header")
 728                      ((eq link-p 29) "multivolume-continuation")
 729                      ((eq link-p 35) "sparse entry")
 730                      ((eq link-p 38) "volume header")
 731                      (t "link"))))
 732     (if (zerop size) (error "This is a zero-length file"))
 733     descriptor))
 734
 735 (defun tar-mouse-extract (event)
 736   "Extract a file whose tar directory line you click on."
 737   (interactive "e")
 738   (save-excursion
 739     (set-buffer (window-buffer (posn-window (event-end event))))
 740     (save-excursion
 741       (goto-char (posn-point (event-end event)))
 742       ;; Just make sure this doesn't get an error.
 743       (tar-get-descriptor)))
 744   (select-window (posn-window (event-end event)))
 745   (goto-char (posn-point (event-end event)))
 746   (tar-extract))
 747
 748 (defun tar-extract (&optional other-window-p)
 749   "In Tar mode, extract this entry of the tar file into its own buffer."
 750   (interactive)
 751   (let* ((view-p (eq other-window-p 'view))
 752          (descriptor (tar-get-descriptor))
 753          (tokens (tar-desc-tokens descriptor))
 754          (name (tar-header-name tokens))
 755          (size (tar-header-size tokens))
 756          (start (+ (tar-desc-data-start descriptor) tar-header-offset -1))
 757          (end (+ start size)))
 758     (let* ((tar-buffer (current-buffer))
 759            (tar-buffer-multibyte enable-multibyte-characters)
 760            (tarname (if (buffer-file-name)
 761                         (file-name-nondirectory (buffer-file-name))
 762                       (buffer-name)))
 763            (bufname (concat (file-name-nondirectory name)
 764                             " ("
 765                             tarname
 766                             ")"))
 767            (read-only-p (or buffer-read-only view-p))
 768            (buffer (get-buffer bufname))
 769            (just-created nil))
 770       (if buffer
 771           nil
 772         (setq buffer (get-buffer-create bufname))
 773         (setq just-created t)
 774         (unwind-protect
 775             (progn
 776               (widen)
 777               (set-buffer-multibyte nil)
 778               (save-excursion
 779                 (set-buffer buffer)
 780                 (if enable-multibyte-characters
 781                     (progn
 782                       ;; We must avoid unibyte->multibyte conversion.
 783                       (set-buffer-multibyte nil)
 784                       (insert-buffer-substring tar-buffer start end)
 785                       (set-buffer-multibyte t))
 786                   (insert-buffer-substring tar-buffer start end))
 787                 (goto-char 0)
 788                 (setq buffer-file-name
 789                       ;; `:' is not allowed on Windows
 790                       (expand-file-name (concat tarname "!" name)))
 791                 (setq buffer-file-truename
 792                       (abbreviate-file-name buffer-file-name))
 793                 ;; We need to mimic the parts of insert-file-contents
 794                 ;; which determine the coding-system and decode the text.
 795                 (let ((coding
 796                        (and set-auto-coding-function
 797                             (save-excursion
 798                               (funcall set-auto-coding-function
 799                                        name (point-max)))))
 800                       (multibyte enable-multibyte-characters)
 801                       (detected (detect-coding-region
 802                                  1 (min 16384 (point-max)) t)))
 803                   (if coding
 804                       (or (numberp (coding-system-eol-type coding))
 805                           (setq coding (coding-system-change-eol-conversion
 806                                         coding
 807                                         (coding-system-eol-type detected))))
 808                     (setq coding
 809                           (or (find-new-buffer-file-coding-system detected)
 810                               (let ((file-coding
 811                                      (find-operation-coding-system
 812                                       'insert-file-contents buffer-file-name)))
 813                                 (if (consp file-coding)
 814                                     (setq file-coding (car file-coding))
 815                                   file-coding)))))
 816                   (if (or (eq coding 'no-conversion)
 817                           (eq (coding-system-type coding) 5))
 818                       (setq multibyte (set-buffer-multibyte nil)))
 819                   (or multibyte
 820                       (setq coding
 821                             (coding-system-change-text-conversion
 822                              coding 'raw-text)))
 823                   (decode-coding-region 1 (point-max) coding)
 824                   (set-buffer-file-coding-system coding))
 825                 ;; Set the default-directory to the dir of the
 826                 ;; superior buffer.
 827                 (setq default-directory
 828                       (save-excursion
 829                         (set-buffer tar-buffer)
 830                         default-directory))
 831                 (normal-mode)  ; pick a mode.
 832                 (rename-buffer bufname)
 833                 (make-local-variable 'tar-superior-buffer)
 834                 (make-local-variable 'tar-superior-descriptor)
 835                 (setq tar-superior-buffer tar-buffer)
 836                 (setq tar-superior-descriptor descriptor)
 837                 (setq buffer-read-only read-only-p)
 838                 (set-buffer-modified-p nil)
 839                 (tar-subfile-mode 1))
 840               (set-buffer tar-buffer))
 841           (narrow-to-region 1 tar-header-offset)
 842           (set-buffer-multibyte tar-buffer-multibyte)))
 843       (if view-p
 844           (view-buffer buffer (and just-created 'kill-buffer))
 845         (if (eq other-window-p 'display)
 846             (display-buffer buffer)
 847           (if other-window-p
 848               (switch-to-buffer-other-window buffer)
 849             (switch-to-buffer buffer)))))))
 850
 851
 852 (defun tar-extract-other-window ()
 853   "*In Tar mode, find this entry of the tar file in another window."
 854   (interactive)
 855   (tar-extract t))
 856
 857 (defun tar-display-other-window ()
 858   "*In Tar mode, display this entry of the tar file in another window."
 859   (interactive)
 860   (tar-extract 'display))
 861
 862 (defun tar-view ()
 863   "*In Tar mode, view the tar file entry on this line."
 864   (interactive)
 865   (tar-extract 'view))
 866
 867
 868 (defun tar-read-file-name (&optional prompt)
 869   "Read a file name with this line's entry as the default."
 870   (or prompt (setq prompt "Copy to: "))
 871   (let* ((default-file (expand-file-name
 872                         (tar-header-name (tar-desc-tokens
 873                                           (tar-current-descriptor)))))
 874          (target (expand-file-name
 875                   (read-file-name prompt
 876                                   (file-name-directory default-file)
 877                                   default-file nil))))
 878     (if (or (string= "" (file-name-nondirectory target))
 879             (file-directory-p target))
 880         (setq target (concat (if (string-match "/$" target)
 881                                  (substring target 0 (1- (match-end 0)))
 882                                  target)
 883                              "/"
 884                              (file-name-nondirectory default-file))))
 885     target))
 886
 887
 888 (defun tar-copy (&optional to-file)
 889   "*In Tar mode, extract this entry of the tar file into a file on disk.
 890 If TO-FILE is not supplied, it is prompted for, defaulting to the name of
 891 the current tar-entry."
 892   (interactive (list (tar-read-file-name)))
 893   (let* ((descriptor (tar-get-descriptor))
 894          (tokens (tar-desc-tokens descriptor))
 895          (name (tar-header-name tokens))
 896          (size (tar-header-size tokens))
 897          (start (+ (tar-desc-data-start descriptor) tar-header-offset -1))
 898          (end (+ start size))
 899          (multibyte enable-multibyte-characters)
 900          (inhibit-file-name-handlers inhibit-file-name-handlers)
 901          (inhibit-file-name-operation inhibit-file-name-operation))
 902     (save-restriction
 903       (widen)
 904       ;; Inhibit compressing a subfile again if *both* name and
 905       ;; to-file are handled by jka-compr
 906       (if (and (eq (find-file-name-handler name 'write-region) 'jka-compr-handler)
 907                (eq (find-file-name-handler to-file 'write-region) 'jka-compr-handler))
 908           (setq inhibit-file-name-handlers
 909                 (cons 'jka-compr-handler
 910                       (and (eq inhibit-file-name-operation 'write-region)
 911                            inhibit-file-name-handlers))
 912                 inhibit-file-name-operation 'write-region))
 913       (unwind-protect
 914           (let ((coding-system-for-write 'no-conversion))
 915             (set-buffer-multibyte nil)
 916             (write-region start end to-file))
 917         (set-buffer-multibyte multibyte)))
 918     (message "Copied tar entry %s to %s" name to-file)))
 919
 920 (defun tar-flag-deleted (p &optional unflag)
 921   "*In Tar mode, mark this sub-file to be deleted from the tar file.
 922 With a prefix argument, mark that many files."
 923   (interactive "p")
 924   (beginning-of-line)
 925   (tar-dotimes (i (if (< p 0) (- p) p))
 926     (if (tar-current-descriptor unflag) ; barf if we're not on an entry-line.
 927         (progn
 928           (delete-char 1)
 929           (insert (if unflag " " "D"))))
 930     (forward-line (if (< p 0) -1 1)))
 931   (if (eobp) nil (forward-char 36)))
 932
 933 (defun tar-unflag (p)
 934   "*In Tar mode, un-mark this sub-file if it is marked to be deleted.
 935 With a prefix argument, un-mark that many files forward."
 936   (interactive "p")
 937   (tar-flag-deleted p t))
 938
 939 (defun tar-unflag-backwards (p)
 940   "*In Tar mode, un-mark this sub-file if it is marked to be deleted.
 941 With a prefix argument, un-mark that many files backward."
 942   (interactive "p")
 943   (tar-flag-deleted (- p) t))
 944
 945
 946 ;; When this function is called, it is sure that the buffer is unibyte.
 947 (defun tar-expunge-internal ()
 948   "Expunge the tar-entry specified by the current line."
 949   (let* ((descriptor (tar-current-descriptor))
 950          (tokens (tar-desc-tokens descriptor))
 951          (line (tar-desc-data-start descriptor))
 952          (name (tar-header-name tokens))
 953          (size (tar-header-size tokens))
 954          (link-p (tar-header-link-type tokens))
 955          (start (tar-desc-data-start descriptor))
 956          (following-descs (cdr (memq descriptor tar-parse-info))))
 957     (if link-p (setq size 0)) ; size lies for hard-links.
 958     ;;
 959     ;; delete the current line...
 960     (beginning-of-line)
 961     (let ((line-start (point)))
 962       (end-of-line) (forward-char)
 963       (let ((line-len (- (point) line-start)))
 964         (delete-region line-start (point))
 965         ;;
 966         ;; decrement the header-pointer to be in sync...
 967         (setq tar-header-offset (- tar-header-offset line-len))))
 968     ;;
 969     ;; delete the data pointer...
 970     (setq tar-parse-info (delq descriptor tar-parse-info))
 971     ;;
 972     ;; delete the data from inside the file...
 973     (widen)
 974     (let* ((data-start (+ start tar-header-offset -513))
 975            (data-end (+ data-start 512 (ash (ash (+ size 511) -9) 9))))
 976       (delete-region data-start data-end)
 977       ;;
 978       ;; and finally, decrement the start-pointers of all following
 979       ;; entries in the archive.  This is a pig when deleting a bunch
 980       ;; of files at once - we could optimize this to only do the
 981       ;; iteration over the files that remain, or only iterate up to
 982       ;; the next file to be deleted.
 983       (let ((data-length (- data-end data-start)))
 984         (tar-dolist (desc following-descs)
 985           (tar-setf (tar-desc-data-start desc)
 986                     (- (tar-desc-data-start desc) data-length))))
 987       ))
 988   (narrow-to-region 1 tar-header-offset))
 989
 990
 991 (defun tar-expunge (&optional noconfirm)
 992   "*In Tar mode, delete all the archived files flagged for deletion.
 993 This does not modify the disk image; you must save the tar file itself
 994 for this to be permanent."
 995   (interactive)
 996   (if (or noconfirm
 997           (y-or-n-p "Expunge files marked for deletion? "))
 998       (let ((n 0)
 999             (multibyte enable-multibyte-characters))
1000         (set-buffer-multibyte nil)
1001         (save-excursion
1002           (goto-char 0)
1003           (while (not (eobp))
1004             (if (looking-at "D")
1005                 (progn (tar-expunge-internal)
1006                        (setq n (1+ n)))
1007                 (forward-line 1)))
1008           ;; after doing the deletions, add any padding that may be necessary.
1009           (tar-pad-to-blocksize)
1010           (narrow-to-region 1 tar-header-offset))
1011         (set-buffer-multibyte multibyte)
1012         (if (zerop n)
1013             (message "Nothing to expunge.")
1014             (message "%s files expunged.  Be sure to save this buffer." n)))))
1015
1016
1017 (defun tar-clear-modification-flags ()
1018   "Remove the stars at the beginning of each line."
1019   (interactive)
1020   (save-excursion
1021     (goto-char 1)
1022     (while (< (position-bytes (point)) tar-header-offset)
1023       (if (not (eq (following-char) ?\ ))
1024           (progn (delete-char 1) (insert " ")))
1025       (forward-line 1))))
1026
1027
1028 (defun tar-chown-entry (new-uid)
1029   "*Change the user-id associated with this entry in the tar file.
1030 If this tar file was written by GNU tar, then you will be able to edit
1031 the user id as a string; otherwise, you must edit it as a number.
1032 You can force editing as a number by calling this with a prefix arg.
1033 This does not modify the disk image; you must save the tar file itself
1034 for this to be permanent."
1035   (interactive (list
1036                  (let ((tokens (tar-desc-tokens (tar-current-descriptor))))
1037                    (if (or current-prefix-arg
1038                            (not (tar-header-magic tokens)))
1039                        (let (n)
1040                          (while (not (numberp (setq n (read-minibuffer
1041                                                         "New UID number: "
1042                                                         (format "%s" (tar-header-uid tokens)))))))
1043                          n)
1044                        (read-string "New UID string: " (tar-header-uname tokens))))))
1045   (cond ((stringp new-uid)
1046          (tar-setf (tar-header-uname (tar-desc-tokens (tar-current-descriptor)))
1047                    new-uid)
1048          (tar-alter-one-field tar-uname-offset (concat new-uid "\000")))
1049         (t
1050          (tar-setf (tar-header-uid (tar-desc-tokens (tar-current-descriptor)))
1051                    new-uid)
1052          (tar-alter-one-field tar-uid-offset
1053            (concat (substring (format "%6o" new-uid) 0 6) "\000 ")))))
1054
1055
1056 (defun tar-chgrp-entry (new-gid)
1057   "*Change the group-id associated with this entry in the tar file.
1058 If this tar file was written by GNU tar, then you will be able to edit
1059 the group id as a string; otherwise, you must edit it as a number.
1060 You can force editing as a number by calling this with a prefix arg.
1061 This does not modify the disk image; you must save the tar file itself
1062 for this to be permanent."
1063   (interactive (list
1064                  (let ((tokens (tar-desc-tokens (tar-current-descriptor))))
1065                    (if (or current-prefix-arg
1066                            (not (tar-header-magic tokens)))
1067                        (let (n)
1068                          (while (not (numberp (setq n (read-minibuffer
1069                                                         "New GID number: "
1070                                                         (format "%s" (tar-header-gid tokens)))))))
1071                          n)
1072                        (read-string "New GID string: " (tar-header-gname tokens))))))
1073   (cond ((stringp new-gid)
1074          (tar-setf (tar-header-gname (tar-desc-tokens (tar-current-descriptor)))
1075                    new-gid)
1076          (tar-alter-one-field tar-gname-offset
1077            (concat new-gid "\000")))
1078         (t
1079          (tar-setf (tar-header-gid (tar-desc-tokens (tar-current-descriptor)))
1080                    new-gid)
1081          (tar-alter-one-field tar-gid-offset
1082            (concat (substring (format "%6o" new-gid) 0 6) "\000 ")))))
1083
1084 (defun tar-rename-entry (new-name)
1085   "*Change the name associated with this entry in the tar file.
1086 This does not modify the disk image; you must save the tar file itself
1087 for this to be permanent."
1088   (interactive
1089     (list (read-string "New name: "
1090             (tar-header-name (tar-desc-tokens (tar-current-descriptor))))))
1091   (if (string= "" new-name) (error "zero length name"))
1092   (if (> (length new-name) 98) (error "name too long"))
1093   (tar-setf (tar-header-name (tar-desc-tokens (tar-current-descriptor)))
1094             new-name)
1095   (tar-alter-one-field 0
1096     (substring (concat new-name (make-string 99 0)) 0 99)))
1097
1098
1099 (defun tar-chmod-entry (new-mode)
1100   "*Change the protection bits associated with this entry in the tar file.
1101 This does not modify the disk image; you must save the tar file itself
1102 for this to be permanent."
1103   (interactive (list (tar-parse-octal-integer-safe
1104                        (read-string "New protection (octal): "))))
1105   (tar-setf (tar-header-mode (tar-desc-tokens (tar-current-descriptor)))
1106             new-mode)
1107   (tar-alter-one-field tar-mode-offset
1108     (concat (substring (format "%6o" new-mode) 0 6) "\000 ")))
1109
1110
1111 (defun tar-alter-one-field (data-position new-data-string)
1112   (let* ((descriptor (tar-current-descriptor))
1113          (tokens (tar-desc-tokens descriptor))
1114          (multibyte enable-multibyte-characters))
1115     (unwind-protect
1116         (save-excursion
1117           ;;
1118           ;; update the header-line.
1119           (beginning-of-line)
1120           (let ((p (point)))
1121             (forward-line 1)
1122             (delete-region p (point))
1123             (insert (tar-header-block-summarize tokens) "\n")
1124             (setq tar-header-offset (position-bytes (point-max))))
1125
1126           (widen)
1127           (set-buffer-multibyte nil)
1128           (let* ((start (+ (tar-desc-data-start descriptor) tar-header-offset -513)))
1129             ;;
1130             ;; delete the old field and insert a new one.
1131             (goto-char (+ start data-position))
1132             (delete-region (point) (+ (point) (length new-data-string))) ; <--
1133             (insert new-data-string) ; <--
1134             ;;
1135             ;; compute a new checksum and insert it.
1136             (let ((chk (tar-header-block-checksum
1137                         (buffer-substring start (+ start 512)))))
1138               (goto-char (+ start tar-chk-offset))
1139               (delete-region (point) (+ (point) 8))
1140               (insert (format "%6o" chk))
1141               (insert 0)
1142               (insert ? )
1143               (tar-setf (tar-header-checksum tokens) chk)
1144               ;;
1145               ;; ok, make sure we didn't botch it.
1146               (tar-header-block-check-checksum
1147                 (buffer-substring start (+ start 512))
1148                 chk (tar-header-name tokens))
1149               )))
1150       (narrow-to-region 1 tar-header-offset)
1151       (set-buffer-multibyte multibyte)
1152       (tar-next-line 0))))
1153
1154
1155 (defun tar-octal-time (timeval)
1156   ;; Format a timestamp as 11 octal digits.  Ghod, I hope this works...
1157   (let ((hibits (car timeval)) (lobits (car (cdr timeval))))
1158     (insert (format "%05o%01o%05o"
1159                     (lsh hibits -2)
1160                     (logior (lsh (logand 3 hibits) 1) (> (logand lobits 32768) 0))
1161                     (logand 32767 lobits)
1162                     ))))
1163
1164 (defun tar-subfile-save-buffer ()
1165   "In tar subfile mode, save this buffer into its parent tar-file buffer.
1166 This doesn't write anything to disk; you must save the parent tar-file buffer
1167 to make your changes permanent."
1168   (interactive)
1169   (if (not (and (boundp 'tar-superior-buffer) tar-superior-buffer))
1170     (error "This buffer has no superior tar file buffer"))
1171   (if (not (and (boundp 'tar-superior-descriptor) tar-superior-descriptor))
1172     (error "This buffer doesn't have an index into its superior tar file!"))
1173   (save-excursion
1174   (let ((subfile (current-buffer))
1175         (subfile-multibyte enable-multibyte-characters)
1176         (coding buffer-file-coding-system)
1177         (descriptor tar-superior-descriptor)
1178         subfile-size)
1179     ;; We must make the current buffer unibyte temporarily to avoid
1180     ;; multibyte->unibyte conversion in `insert-buffer'.
1181     (set-buffer-multibyte nil)
1182     (setq subfile-size (buffer-size))
1183     (set-buffer tar-superior-buffer)
1184     (let* ((tokens (tar-desc-tokens descriptor))
1185            (start (tar-desc-data-start descriptor))
1186            (name (tar-header-name tokens))
1187            (size (tar-header-size tokens))
1188            (size-pad (ash (ash (+ size 511) -9) 9))
1189            (head (memq descriptor tar-parse-info))
1190            (following-descs (cdr head))
1191            (tar-buffer-multibyte enable-multibyte-characters))
1192       (if (not head)
1193         (error "Can't find this tar file entry in its parent tar file!"))
1194       (unwind-protect
1195        (save-excursion
1196         (widen)
1197         (set-buffer-multibyte nil)
1198         ;; delete the old data...
1199         (let* ((data-start (+ start tar-header-offset -1))
1200                (data-end (+ data-start (ash (ash (+ size 511) -9) 9))))
1201           (delete-region data-start data-end)
1202           ;; insert the new data...
1203           (goto-char data-start)
1204           (insert-buffer subfile)
1205           (setq subfile-size
1206                 (encode-coding-region
1207                  data-start (+ data-start subfile-size) coding))
1208           ;;
1209           ;; pad the new data out to a multiple of 512...
1210           (let ((subfile-size-pad (ash (ash (+ subfile-size 511) -9) 9)))
1211             (goto-char (+ data-start subfile-size))
1212             (insert (make-string (- subfile-size-pad subfile-size) 0))
1213             ;;
1214             ;; update the data pointer of this and all following files...
1215             (tar-setf (tar-header-size tokens) subfile-size)
1216             (let ((difference (- subfile-size-pad size-pad)))
1217               (tar-dolist (desc following-descs)
1218                 (tar-setf (tar-desc-data-start desc)
1219                           (+ (tar-desc-data-start desc) difference))))
1220             ;;
1221             ;; Update the size field in the header block.
1222             (let ((header-start (- data-start 512)))
1223               (goto-char (+ header-start tar-size-offset))
1224               (delete-region (point) (+ (point) 12))
1225               (insert (format "%11o" subfile-size))
1226               (insert ? )
1227               ;;
1228               ;; Maybe update the datestamp.
1229               (if (not tar-update-datestamp)
1230                   nil
1231                 (goto-char (+ header-start tar-time-offset))
1232                 (delete-region (point) (+ (point) 12))
1233                 (insert (tar-octal-time (current-time)))
1234                 (insert ? ))
1235               ;;
1236               ;; compute a new checksum and insert it.
1237               (let ((chk (tar-header-block-checksum
1238                           (buffer-substring header-start data-start))))
1239                 (goto-char (+ header-start tar-chk-offset))
1240                 (delete-region (point) (+ (point) 8))
1241                 (insert (format "%6o" chk))
1242                 (insert 0)
1243                 (insert ? )
1244                 (tar-setf (tar-header-checksum tokens) chk)))
1245             ;;
1246             ;; alter the descriptor-line...
1247             ;;
1248             (let ((position (- (length tar-parse-info) (length head))))
1249               (goto-char 1)
1250               (next-line position)
1251               (beginning-of-line)
1252               (let ((p (point))
1253                     after
1254                     (m (set-marker (make-marker) tar-header-offset)))
1255                 (forward-line 1)
1256                 (setq after (point))
1257                 ;; Insert the new text after the old, before deleting,
1258                 ;; to preserve the window start.
1259                 (let ((line (tar-header-block-summarize tokens t)))
1260                   (if (multibyte-string-p line)
1261                       (insert-before-markers (string-as-unibyte line) "\n")
1262                     (insert-before-markers line "\n")))
1263                 (delete-region p after)
1264                 (setq tar-header-offset (marker-position m)))
1265               )))
1266         ;; after doing the insertion, add any final padding that may be necessary.
1267         (tar-pad-to-blocksize))
1268        (narrow-to-region 1 tar-header-offset)
1269        (set-buffer-multibyte tar-buffer-multibyte)))
1270     (set-buffer-modified-p t)   ; mark the tar file as modified
1271     (tar-next-line 0)
1272     (set-buffer subfile)
1273     ;; Restore the buffer multibyteness.
1274     (set-buffer-multibyte subfile-multibyte)
1275     (set-buffer-modified-p nil) ; mark the tar subfile as unmodified
1276     (message "Saved into tar-buffer `%s'.  Be sure to save that buffer!"
1277              (buffer-name tar-superior-buffer))
1278     ;; Prevent basic-save-buffer from changing our coding-system.
1279     (setq last-coding-system-used buffer-file-coding-system)
1280     ;; Prevent ordinary saving from happening.
1281     t)))
1282
1283
1284 ;; When this function is called, it is sure that the buffer is unibyte.
1285 (defun tar-pad-to-blocksize ()
1286   "If we are being anal about tar file blocksizes, fix up the current buffer.
1287 Leaves the region wide."
1288   (if (null tar-anal-blocksize)
1289       nil
1290     (widen)
1291     (let* ((last-desc (nth (1- (length tar-parse-info)) tar-parse-info))
1292            (start (tar-desc-data-start last-desc))
1293            (tokens (tar-desc-tokens last-desc))
1294            (link-p (tar-header-link-type tokens))
1295            (size (if link-p 0 (tar-header-size tokens)))
1296            (data-end (+ start size))
1297            (bbytes (ash tar-anal-blocksize 9))
1298            (pad-to (+ bbytes (* bbytes (/ (1- data-end) bbytes))))
1299            (inhibit-read-only t) ; ##
1300            )
1301       ;; If the padding after the last data is too long, delete some;
1302       ;; else insert some until we are padded out to the right number of blocks.
1303       ;;
1304       (goto-char (+ (or tar-header-offset 0) data-end))
1305       (if (> (1+ (buffer-size)) (+ (or tar-header-offset 0) pad-to))
1306           (delete-region (+ (or tar-header-offset 0) pad-to) (1+ (buffer-size)))
1307           (insert (make-string (- (+ (or tar-header-offset 0) pad-to)
1308                                   (1+ (buffer-size)))
1309                                0)))
1310       )))
1311
1312
1313 ;; Used in write-file-hook to write tar-files out correctly.
1314 (defun tar-mode-write-file ()
1315   (unwind-protect
1316       (save-excursion
1317         (widen)
1318         ;; Doing this here confuses things - the region gets left too wide!
1319         ;; I suppose this is run in a context where changing the buffer is bad.
1320         ;; (tar-pad-to-blocksize)
1321         ;; tar-header-offset turns out to be null for files fetched with W3,
1322         ;; at least.
1323         (let ((coding-system-for-write 'no-conversion))
1324           (write-region (or (byte-to-position tar-header-offset)
1325                             (point-min))
1326                         (point-max)
1327                         buffer-file-name nil t))
1328         (tar-clear-modification-flags)
1329         (set-buffer-modified-p nil))
1330     (narrow-to-region 1 (byte-to-position tar-header-offset)))
1331   ;; Return t because we've written the file.
1332   t)
1333 \f
1334 (provide 'tar-mode)
1335
1336 ;;; tar-mode.el ends here