lisp/tar-mode.el

   1 ;;; tar-mode.el --- simple editing of tar files from GNU emacs
   2
   3 ;;; Copyright (C) 1990, 1991, 1993 Free Software Foundation, Inc.
   4
   5 ;; Author: Jamie Zawinski <jwz@lucid.com>
   6 ;; Created: 04 Apr 1990
   7 ;; Version: 1.21bis (some cleanup by ESR)
   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
  24 ;;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
  25
  26 ;;; Commentary:
  27
  28 ;;; This package attempts to make dealing with Unix 'tar' archives easier.
  29 ;;; When this code is loaded, visiting a file whose name ends in '.tar' will
  30 ;;; cause the contents of that archive file to be displayed in a Dired-like
  31 ;;; listing.  It is then possible to use the customary Dired keybindings to
  32 ;;; extract sub-files from that archive, either by reading them into their own
  33 ;;; editor buffers, or by copying them directly to arbitrary files on disk.
  34 ;;; It is also possible to delete sub-files from within the tar file and write
  35 ;;; the modified archive back to disk, or to edit sub-files within the archive
  36 ;;; and re-insert the modified files into the archive.  See the documentation
  37 ;;; string of tar-mode for more info.
  38
  39 ;;; This code now understands the extra fields that GNU tar adds to tar files.
  40
  41 ;;; This interacts correctly with "uncompress.el" in the Emacs library,
  42 ;;; which you get with
  43 ;;;
  44 ;;;  (autoload 'uncompress-while-visiting "uncompress")
  45 ;;;  (setq auto-mode-alist (cons '("\\.Z$" . uncompress-while-visiting)
  46 ;;;                        auto-mode-alist))
  47 ;;;
  48 ;;; Do not attempt to use tar-mode.el with crypt.el, you will lose.
  49
  50 ;;;    ***************   TO DO   ***************
  51 ;;;
  52 ;;; o  chmod should understand "a+x,og-w".
  53 ;;;
  54 ;;; o  It's not possible to add a NEW file to a tar archive; not that
  55 ;;;    important, but still...
  56 ;;;
  57 ;;; o  In the directory listing, we don't show creation times because I don't
  58 ;;;    know how to print an arbitrary date, and I don't really want to have to
  59 ;;;    implement decode-universal-time.
  60 ;;;
  61 ;;; o  The code is less efficient that it could be - in a lot of places, I
  62 ;;;    pull a 512-character string out of the buffer and parse it, when I could
  63 ;;;    be parsing it in place, not garbaging a string.  Should redo that.
  64 ;;;
  65 ;;; o  I'd like a command that searches for a string/regexp in every subfile
  66 ;;;    of an archive, where <esc> would leave you in a subfile-edit buffer.
  67 ;;;    (Like the Meta-R command of the Zmacs mail reader.)
  68 ;;;
  69 ;;; o  Sometimes (but not always) reverting the tar-file buffer does not
  70 ;;;    re-grind the listing, and you are staring at the binary tar data.
  71 ;;;    Typing 'g' again immediately after that will always revert and re-grind
  72 ;;;    it, though.  I have no idea why this happens.
  73 ;;;
  74 ;;; o  Tar-mode interacts poorly with crypt.el and zcat.el because the tar
  75 ;;;    write-file-hook actually writes the file.  Instead it should remove the
  76 ;;;    header (and conspire to put it back afterwards) so that other write-file
  77 ;;;    hooks which frob the buffer have a chance to do their dirty work.  There
  78 ;;;    might be a problem if the tar write-file-hook does not come *first* on
  79 ;;;    the list.
  80 ;;;
  81 ;;; o  Block files, sparse files, continuation files, and the various header
  82 ;;;    types aren't editable.  Actually I don't know that they work at all.
  83
  84 ;;; Code:
  85
  86 (defvar tar-anal-blocksize 20
  87   "*The blocksize of tar files written by Emacs, or nil, meaning don't care.
  88 The blocksize of a tar file is not really the size of the blocks; rather, it is
  89 the number of blocks written with one system call.  When tarring to a tape,
  90 this is the size of the *tape* blocks, but when writing to a file, it doesn't
  91 matter much.  The only noticeable difference is that if a tar file does not
  92 have a blocksize of 20, tar will tell you that; all this really controls is
  93 how many null padding bytes go on the end of the tar file.")
  94
  95 (defvar tar-update-datestamp nil
  96   "*Whether tar-mode should play fast and loose with sub-file datestamps;
  97 if this is true, then editing and saving a tar file entry back into its
  98 tar file will update its datestamp.  If false, the datestamp is unchanged.
  99 You may or may not want this - it is good in that you can tell when a file
 100 in a tar archive has been changed, but it is bad for the same reason that
 101 editing a file in the tar archive at all is bad - the changed version of
 102 the file never exists on disk.")
 103
 104 (defvar tar-parse-info nil)
 105 (defvar tar-header-offset nil)
 106 (defvar tar-superior-buffer nil)
 107 (defvar tar-superior-descriptor nil)
 108 (defvar tar-subfile-mode nil)
 109
 110 (put 'tar-parse-info 'permanent-local t)
 111 (put 'tar-header-offset 'permanent-local t)
 112 (put 'tar-superior-buffer 'permanent-local t)
 113 (put 'tar-superior-descriptor 'permanent-local t)
 114 \f
 115 ;;; First, duplicate some Common Lisp functions; I used to just (require 'cl)
 116 ;;; but "cl.el" was messing some people up (also it's really big).
 117
 118 (defmacro tar-setf (form val)
 119   "A mind-numbingly simple implementation of setf."
 120   (let ((mform (macroexpand form (and (boundp 'byte-compile-macro-environment)
 121                                       byte-compile-macro-environment))))
 122     (cond ((symbolp mform) (list 'setq mform val))
 123           ((not (consp mform)) (error "can't setf %s" form))
 124           ((eq (car mform) 'aref)
 125            (list 'aset (nth 1 mform) (nth 2 mform) val))
 126           ((eq (car mform) 'car)
 127            (list 'setcar (nth 1 mform) val))
 128           ((eq (car mform) 'cdr)
 129            (list 'setcdr (nth 1 mform) val))
 130           (t (error "don't know how to setf %s" form)))))
 131
 132 (defmacro tar-dolist (control &rest body)
 133   "syntax: (dolist (var-name list-expr &optional return-value) &body body)"
 134   (let ((var (car control))
 135         (init (car (cdr control)))
 136         (val (car (cdr (cdr control)))))
 137     (list 'let (list (list '_dolist_iterator_ init))
 138           (list 'while '_dolist_iterator_
 139             (cons 'let
 140               (cons (list (list var '(car _dolist_iterator_)))
 141                     (append body
 142                             (list (list 'setq '_dolist_iterator_
 143                                         (list 'cdr '_dolist_iterator_)))))))
 144           val)))
 145
 146 (defmacro tar-dotimes (control &rest body)
 147   "syntax: (dolist (var-name count-expr &optional return-value) &body body)"
 148   (let ((var (car control))
 149         (n (car (cdr control)))
 150         (val (car (cdr (cdr control)))))
 151     (list 'let (list (list '_dotimes_end_ n)
 152                      (list var 0))
 153           (cons 'while
 154                 (cons (list '< var '_dotimes_end_)
 155                       (append body
 156                               (list (list 'setq var (list '1+ var))))))
 157           val)))
 158
 159 \f
 160 ;;; down to business.
 161
 162 (defmacro make-tar-header (name mode uid git size date ck lt ln
 163                            magic uname gname devmaj devmin)
 164   (list 'vector name mode uid git size date ck lt ln
 165         magic uname gname devmaj devmin))
 166
 167 (defmacro tar-header-name (x) (list 'aref x 0))
 168 (defmacro tar-header-mode (x) (list 'aref x 1))
 169 (defmacro tar-header-uid  (x) (list 'aref x 2))
 170 (defmacro tar-header-gid  (x) (list 'aref x 3))
 171 (defmacro tar-header-size (x) (list 'aref x 4))
 172 (defmacro tar-header-date (x) (list 'aref x 5))
 173 (defmacro tar-header-checksum  (x) (list 'aref x 6))
 174 (defmacro tar-header-link-type (x) (list 'aref x 7))
 175 (defmacro tar-header-link-name (x) (list 'aref x 8))
 176 (defmacro tar-header-magic (x) (list 'aref x 9))
 177 (defmacro tar-header-uname (x) (list 'aref x 10))
 178 (defmacro tar-header-gname (x) (list 'aref x 11))
 179 (defmacro tar-header-dmaj (x) (list 'aref x 12))
 180 (defmacro tar-header-dmin (x) (list 'aref x 13))
 181
 182 (defmacro make-tar-desc (data-start tokens)
 183   (list 'cons data-start tokens))
 184
 185 (defmacro tar-desc-data-start (x) (list 'car x))
 186 (defmacro tar-desc-tokens     (x) (list 'cdr x))
 187
 188 (defconst tar-name-offset 0)
 189 (defconst tar-mode-offset (+ tar-name-offset 100))
 190 (defconst tar-uid-offset  (+ tar-mode-offset 8))
 191 (defconst tar-gid-offset  (+ tar-uid-offset 8))
 192 (defconst tar-size-offset (+ tar-gid-offset 8))
 193 (defconst tar-time-offset (+ tar-size-offset 12))
 194 (defconst tar-chk-offset  (+ tar-time-offset 12))
 195 (defconst tar-linkp-offset (+ tar-chk-offset 8))
 196 (defconst tar-link-offset (+ tar-linkp-offset 1))
 197 ;;; GNU-tar specific slots.
 198 (defconst tar-magic-offset (+ tar-link-offset 100))
 199 (defconst tar-uname-offset (+ tar-magic-offset 8))
 200 (defconst tar-gname-offset (+ tar-uname-offset 32))
 201 (defconst tar-dmaj-offset (+ tar-gname-offset 32))
 202 (defconst tar-dmin-offset (+ tar-dmaj-offset 8))
 203 (defconst tar-end-offset (+ tar-dmin-offset 8))
 204
 205 (defun tokenize-tar-header-block (string)
 206   "Return a `tar-header' structure.
 207 This is a list of name, mode, uid, gid, size,
 208 write-date, checksum, link-type, and link-name."
 209   (cond ((< (length string) 512) nil)
 210         (;(some 'plusp string)           ; <-- oops, massive cycle hog!
 211          (or (not (= 0 (aref string 0))) ; This will do.
 212              (not (= 0 (aref string 101))))
 213          (let* ((name-end (1- tar-mode-offset))
 214                 (link-end (1- tar-magic-offset))
 215                 (uname-end (1- tar-gname-offset))
 216                 (gname-end (1- tar-dmaj-offset))
 217                 (link-p (aref string tar-linkp-offset))
 218                 (magic-str (substring string tar-magic-offset (1- tar-uname-offset)))
 219                 (uname-valid-p (or (string= "ustar  " magic-str) (string= "GNUtar " magic-str)))
 220                 name
 221                 (nulsexp   "[^\000]*\000"))
 222            (and (string-match nulsexp string tar-name-offset) (setq name-end (min name-end (1- (match-end 0)))))
 223            (and (string-match nulsexp string tar-link-offset) (setq link-end (min link-end (1- (match-end 0)))))
 224            (and (string-match nulsexp string tar-uname-offset) (setq uname-end (min uname-end (1- (match-end 0)))))
 225            (and (string-match nulsexp string tar-gname-offset) (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            (if (and (null link-p) (string-match "/$" name)) (setq link-p 5)) ; directory
 231            (make-tar-header
 232              name
 233              (tar-parse-octal-integer string tar-mode-offset (1- tar-uid-offset))
 234              (tar-parse-octal-integer string tar-uid-offset (1- tar-gid-offset))
 235              (tar-parse-octal-integer string tar-gid-offset (1- tar-size-offset))
 236              (tar-parse-octal-integer string tar-size-offset (1- tar-time-offset))
 237              (tar-parse-octal-integer string tar-time-offset (1- tar-chk-offset))
 238              (tar-parse-octal-integer string tar-chk-offset (1- tar-linkp-offset))
 239              link-p
 240              (substring string tar-link-offset link-end)
 241              uname-valid-p
 242              (and uname-valid-p (substring string tar-uname-offset uname-end))
 243              (and uname-valid-p (substring string tar-gname-offset gname-end))
 244              (tar-parse-octal-integer string tar-dmaj-offset (1- tar-dmin-offset))
 245              (tar-parse-octal-integer string tar-dmin-offset (1- tar-end-offset))
 246              )))
 247         (t 'empty-tar-block)))
 248
 249
 250 (defun tar-parse-octal-integer (string &optional start end)
 251   (if (null start) (setq start 0))
 252   (if (null end) (setq end (length string)))
 253   (if (= (aref string start) 0)
 254       0
 255     (let ((n 0))
 256       (while (< start end)
 257         (setq n (if (< (aref string start) ?0) n
 258                   (+ (* n 8) (- (aref string start) 48)))
 259               start (1+ start)))
 260       n)))
 261
 262 (defun tar-parse-octal-integer-safe (string)
 263   (let ((L (length string)))
 264     (if (= L 0) (error "empty string"))
 265     (tar-dotimes (i L)
 266        (if (or (< (aref string i) ?0)
 267                (> (aref string i) ?7))
 268            (error "'%c' is not an octal digit"))))
 269   (tar-parse-octal-integer string))
 270
 271
 272 (defun checksum-tar-header-block (string)
 273   "Compute and return a tar-acceptable checksum for this block."
 274   (let* ((chk-field-start tar-chk-offset)
 275          (chk-field-end (+ chk-field-start 8))
 276          (sum 0)
 277          (i 0))
 278     ;; Add up all of the characters except the ones in the checksum field.
 279     ;; Add that field as if it were filled with spaces.
 280     (while (< i chk-field-start)
 281       (setq sum (+ sum (aref string i))
 282             i (1+ i)))
 283     (setq i chk-field-end)
 284     (while (< i 512)
 285       (setq sum (+ sum (aref string i))
 286             i (1+ i)))
 287     (+ sum (* 32 8))))
 288
 289 (defun check-tar-header-block-checksum (hblock desired-checksum file-name)
 290   "Beep and print a warning if the checksum doesn't match."
 291   (if (not (= desired-checksum (checksum-tar-header-block hblock)))
 292       (progn (beep) (message "Invalid checksum for file %s!" file-name))))
 293
 294 (defun recompute-tar-header-block-checksum (hblock)
 295   "Modifies the given string to have a valid checksum field."
 296   (let* ((chk (checksum-tar-header-block hblock))
 297          (chk-string (format "%6o" chk))
 298          (l (length chk-string)))
 299     (aset hblock 154 0)
 300     (aset hblock 155 32)
 301     (tar-dotimes (i l) (aset hblock (- 153 i) (aref chk-string (- l i 1)))))
 302   hblock)
 303
 304
 305 (defun tar-grind-file-mode (mode string start)
 306   "Write a \"-rw--r--r-\" representing MODE into STRING beginning at START."
 307   (aset string start       (if (zerop (logand 256 mode)) ?- ?r))
 308   (aset string (+ start 1) (if (zerop (logand 128 mode)) ?- ?w))
 309   (aset string (+ start 2) (if (zerop (logand  64 mode)) ?- ?x))
 310   (aset string (+ start 3) (if (zerop (logand  32 mode)) ?- ?r))
 311   (aset string (+ start 4) (if (zerop (logand  16 mode)) ?- ?w))
 312   (aset string (+ start 5) (if (zerop (logand   8 mode)) ?- ?x))
 313   (aset string (+ start 6) (if (zerop (logand   4 mode)) ?- ?r))
 314   (aset string (+ start 7) (if (zerop (logand   2 mode)) ?- ?w))
 315   (aset string (+ start 8) (if (zerop (logand   1 mode)) ?- ?x))
 316   (if (zerop (logand 1024 mode)) nil (aset string (+ start 2) ?s))
 317   (if (zerop (logand 2048 mode)) nil (aset string (+ start 5) ?s))
 318   string)
 319
 320 (defun summarize-tar-header-block (tar-hblock &optional mod-p)
 321   "Returns a line similar to the output of `tar -vtf'."
 322   (let ((name (tar-header-name tar-hblock))
 323         (mode (tar-header-mode tar-hblock))
 324         (uid (tar-header-uid tar-hblock))
 325         (gid (tar-header-gid tar-hblock))
 326         (uname (tar-header-uname tar-hblock))
 327         (gname (tar-header-gname tar-hblock))
 328         (size (tar-header-size tar-hblock))
 329         (time (tar-header-date tar-hblock))
 330         (ck (tar-header-checksum tar-hblock))
 331         (link-p (tar-header-link-type tar-hblock))
 332         (link-name (tar-header-link-name tar-hblock))
 333         )
 334     (let* ((left 11)
 335            (namew 8)
 336            (groupw 8)
 337            (sizew 8)
 338            (datew 2)
 339            (slash (1- (+ left namew)))
 340            (lastdigit (+ slash groupw sizew))
 341            (namestart (+ lastdigit datew))
 342            (string (make-string (+ namestart (length name) (if link-p (+ 5 (length link-name)) 0)) 32))
 343            (type (tar-header-link-type tar-hblock)))
 344       (aset string 0 (if mod-p ?* ? ))
 345       (aset string 1
 346             (cond ((or (eq type nil) (eq type 0)) ?-)
 347                   ((eq type 1) ?l)  ; link
 348                   ((eq type 2) ?s)  ; symlink
 349                   ((eq type 3) ?c)  ; char special
 350                   ((eq type 4) ?b)  ; block special
 351                   ((eq type 5) ?d)  ; directory
 352                   ((eq type 6) ?p)  ; FIFO/pipe
 353                   ((eq type 20) ?*) ; directory listing
 354                   ((eq type 29) ?M) ; multivolume continuation
 355                   ((eq type 35) ?S) ; sparse
 356                   ((eq type 38) ?V) ; volume header
 357                   ))
 358       (tar-grind-file-mode mode string 2)
 359       (setq uid (if (= 0 (length uname)) (int-to-string uid) uname))
 360       (setq gid (if (= 0 (length gname)) (int-to-string gid) gname))
 361       (setq size (int-to-string size))
 362       (tar-dotimes (i (min (1- namew) (length uid))) (aset string (- slash i) (aref uid (- (length uid) i 1))))
 363       (aset string (1+ slash) ?/)
 364       (tar-dotimes (i (min (1- groupw) (length gid))) (aset string (+ (+ slash 2) i) (aref gid i)))
 365       (tar-dotimes (i (min sizew (length size))) (aset string (- lastdigit i) (aref size (- (length size) i 1))))
 366       ;; ## bloody hell, how do I print an arbitrary date??
 367       (tar-dotimes (i (length name)) (aset string (+ namestart i) (aref name i)))
 368       (if (or (eq link-p 1) (eq link-p 2))
 369           (progn
 370             (tar-dotimes (i 3) (aset string (+ namestart 1 (length name) i) (aref (if (= link-p 1) "==>" "-->") i)))
 371             (tar-dotimes (i (length link-name)) (aset string (+ namestart 5 (length name) i) (aref link-name i)))))
 372       (put-text-property namestart (length string)
 373                          'mouse-face 'highlight string)
 374       string)))
 375
 376
 377 (defun tar-summarize-buffer ()
 378   "Parse the contents of the tar file in the current buffer.
 379 Place a dired-like listing on the front;
 380 then narrow to it, so that only that listing
 381 is visible (and the real data of the buffer is hidden)."
 382   (message "parsing tar file...")
 383   (let* ((result '())
 384          (pos 1)
 385          (bs (max 1 (- (buffer-size) 1024))) ; always 2+ empty blocks at end.
 386          (bs100 (max 1 (/ bs 100)))
 387         (tokens nil))
 388     (while (not (eq tokens 'empty-tar-block))
 389       (let* ((hblock (buffer-substring pos (+ pos 512))))
 390         (setq tokens (tokenize-tar-header-block hblock))
 391         (setq pos (+ pos 512))
 392         (message "parsing tar file...%s%%"
 393                  ;(/ (* pos 100) bs)   ; this gets round-off lossage
 394                  (/ pos bs100)         ; this doesn't
 395                  )
 396         (if (eq tokens 'empty-tar-block)
 397             nil
 398           (if (null tokens) (error "premature EOF parsing tar file"))
 399           (if (eq (tar-header-link-type tokens) 20)
 400               ;; Foo.  There's an extra empty block after these.
 401               (setq pos (+ pos 512)))
 402           (let ((size (tar-header-size tokens)))
 403             (if (< size 0)
 404                 (error "%s has size %s - corrupted"
 405                        (tar-header-name tokens) size))
 406             ;
 407             ; This is just too slow.  Don't really need it anyway....
 408             ;(check-tar-header-block-checksum
 409             ;  hblock (checksum-tar-header-block hblock)
 410             ;  (tar-header-name tokens))
 411
 412             (setq result (cons (make-tar-desc pos tokens) result))
 413
 414             (if (and (null (tar-header-link-type tokens))
 415                      (> size 0))
 416                 (setq pos
 417                   (+ pos 512 (ash (ash (1- size) -9) 9))        ; this works
 418                   ;(+ pos (+ size (- 512 (rem (1- size) 512)))) ; this doesn't
 419                   ))
 420             ))))
 421     (make-local-variable 'tar-parse-info)
 422     (setq tar-parse-info (nreverse result)))
 423   (save-excursion
 424     (goto-char (point-min))
 425     (let ((buffer-read-only nil))
 426       (tar-dolist (tar-desc tar-parse-info)
 427         (insert-string
 428           (summarize-tar-header-block (tar-desc-tokens tar-desc)))
 429         (insert-string "\n"))
 430       (make-local-variable 'tar-header-offset)
 431       (setq tar-header-offset (point))
 432       (narrow-to-region 1 tar-header-offset)
 433       (set-buffer-modified-p nil)))
 434   (message "parsing tar file...done."))
 435 \f
 436 (defvar tar-mode-map nil "*Local keymap for Tar mode listings.")
 437
 438 (if tar-mode-map
 439     nil
 440   (setq tar-mode-map (make-keymap))
 441   (suppress-keymap tar-mode-map)
 442   (define-key tar-mode-map " " 'tar-next-line)
 443   (define-key tar-mode-map "c" 'tar-copy)
 444   (define-key tar-mode-map "d" 'tar-flag-deleted)
 445   (define-key tar-mode-map "\^D" 'tar-flag-deleted)
 446   (define-key tar-mode-map "e" 'tar-extract)
 447   (define-key tar-mode-map "f" 'tar-extract)
 448   (define-key tar-mode-map [mouse-2] 'tar-mouse-extract)
 449   (define-key tar-mode-map "g" 'revert-buffer)
 450   (define-key tar-mode-map "h" 'describe-mode)
 451   (define-key tar-mode-map "n" 'tar-next-line)
 452   (define-key tar-mode-map "\^N" 'tar-next-line)
 453   (define-key tar-mode-map "o" 'tar-extract-other-window)
 454   (define-key tar-mode-map "p" 'tar-previous-line)
 455   (define-key tar-mode-map "\^P" 'tar-previous-line)
 456   (define-key tar-mode-map "r" 'tar-rename-entry)
 457   (define-key tar-mode-map "u" 'tar-unflag)
 458   (define-key tar-mode-map "v" 'tar-view)
 459   (define-key tar-mode-map "x" 'tar-expunge)
 460   (define-key tar-mode-map "\177" 'tar-unflag-backwards)
 461   (define-key tar-mode-map "E" 'tar-extract-other-window)
 462   (define-key tar-mode-map "M" 'tar-chmod-entry)
 463   (define-key tar-mode-map "G" 'tar-chgrp-entry)
 464   (define-key tar-mode-map "O" 'tar-chown-entry)
 465   )
 466 \f
 467 ;; Make menu bar items.
 468
 469 ;; Get rid of the Edit menu bar item to save space.
 470 (define-key tar-mode-map [menu-bar edit] 'undefined)
 471
 472 (define-key tar-mode-map [menu-bar immediate]
 473   (cons "Immediate" (make-sparse-keymap "Immediate")))
 474
 475 (define-key tar-mode-map [menu-bar immediate view]
 476   '("View This File" . tar-view))
 477 (define-key tar-mode-map [menu-bar immediate display]
 478   '("Display in Other Window" . tar-display-file))
 479 (define-key tar-mode-map [menu-bar immediate find-file-other-window]
 480   '("Find in Other Window" . tar-extract-other-window))
 481 (define-key tar-mode-map [menu-bar immediate find-file]
 482   '("Find This File" . tar-extract))
 483
 484 (define-key tar-mode-map [menu-bar mark]
 485   (cons "Mark" (make-sparse-keymap "Mark")))
 486
 487 (define-key tar-mode-map [menu-bar mark unmark-all]
 488   '("Unmark All" . tar-clear-modification-flags))
 489 (define-key tar-mode-map [menu-bar mark deletion]
 490   '("Flag" . tar-flag-deleted))
 491 (define-key tar-mode-map [menu-bar mark unmark]
 492   '("Unflag" . tar-unflag))
 493
 494 (define-key tar-mode-map [menu-bar operate]
 495   (cons "Operate" (make-sparse-keymap "Operate")))
 496
 497 (define-key tar-mode-map [menu-bar operate chown]
 498   '("Change Owner..." . tar-chown-entry))
 499 (define-key tar-mode-map [menu-bar operate chgrp]
 500   '("Change Group..." . tar-chgrp-entry))
 501 (define-key tar-mode-map [menu-bar operate chmod]
 502   '("Change Mode..." . tar-chmod-entry))
 503 (define-key tar-mode-map [menu-bar operate rename]
 504   '("Rename to..." . tar-rename-entry))
 505 (define-key tar-mode-map [menu-bar operate copy]
 506   '("Copy to..." . tar-copy))
 507 (define-key tar-mode-map [menu-bar operate expunge]
 508   '("Expunge marked files" . tar-expunge))
 509 \f
 510 ;; tar mode is suitable only for specially formatted data.
 511 (put 'tar-mode 'mode-class 'special)
 512 (put 'tar-subfile-mode 'mode-class 'special)
 513
 514 ;;;###autoload
 515 (defun tar-mode ()
 516   "Major mode for viewing a tar file as a dired-like listing of its contents.
 517 You can move around using the usual cursor motion commands.
 518 Letters no longer insert themselves.
 519 Type `e' to pull a file out of the tar file and into its own buffer;
 520 or click mouse-2 on the file's line in the Tar mode buffer.
 521 Type `c' to copy an entry from the tar file into another file on disk.
 522
 523 If you edit a sub-file of this archive (as with the `e' command) and
 524 save it with Control-x Control-s, the contents of that buffer will be
 525 saved back into the tar-file buffer; in this way you can edit a file
 526 inside of a tar archive without extracting it and re-archiving it.
 527
 528 See also: variables `tar-update-datestamp' and `tar-anal-blocksize'.
 529 \\{tar-mode-map}"
 530   ;; this is not interactive because you shouldn't be turning this
 531   ;; mode on and off.  You can corrupt things that way.
 532   ;; rms: with permanent locals, it should now be possible to make this work
 533   ;; interactively in some reasonable fashion.
 534   (kill-all-local-variables)
 535   (make-local-variable 'tar-header-offset)
 536   (make-local-variable 'tar-parse-info)
 537   (make-local-variable 'require-final-newline)
 538   (setq require-final-newline nil) ; binary data, dude...
 539   (make-local-variable 'revert-buffer-function)
 540   (setq revert-buffer-function 'tar-mode-revert)
 541   (make-local-variable 'enable-local-variables)
 542   (setq enable-local-variables nil)
 543   (setq major-mode 'tar-mode)
 544   (setq mode-name "Tar")
 545   (use-local-map tar-mode-map)
 546   (auto-save-mode 0)
 547   (widen)
 548   (if (and (boundp 'tar-header-offset) tar-header-offset)
 549       (narrow-to-region 1 tar-header-offset)
 550       (tar-summarize-buffer))
 551   (run-hooks 'tar-mode-hook)
 552   )
 553
 554
 555 ;; This should be converted to use a minor mode keymap.
 556
 557 (defun tar-subfile-mode (p)
 558   "Minor mode for editing an element of a tar-file.
 559 This mode redefines C-x C-s to save the current buffer back into its
 560 associated tar-file buffer.  You must save that buffer to actually
 561 save your changes to disk."
 562   (interactive "P")
 563   (or (and (boundp 'tar-superior-buffer) tar-superior-buffer)
 564       (error "This buffer is not an element of a tar file"))
 565   (or (assq 'tar-subfile-mode minor-mode-alist)
 566       (setq minor-mode-alist (append minor-mode-alist
 567                                      (list '(tar-subfile-mode
 568                                              " TarFile")))))
 569   (make-local-variable 'tar-subfile-mode)
 570   (setq tar-subfile-mode
 571         (if (null p)
 572             (not tar-subfile-mode)
 573             (> (prefix-numeric-value p) 0)))
 574   (cond (tar-subfile-mode
 575          (make-local-variable 'local-write-file-hooks)
 576          (setq local-write-file-hooks '(tar-subfile-save-buffer))
 577          ;; turn off auto-save.
 578          (auto-save-mode nil)
 579          (setq buffer-auto-save-file-name nil)
 580          (run-hooks 'tar-subfile-mode-hook))
 581         (t
 582          (kill-local-variable 'local-write-file-hooks))))
 583
 584
 585 ;; Revert the buffer and recompute the dired-like listing.
 586 (defun tar-mode-revert (&optional no-autosave no-confirm)
 587   (setq tar-header-offset nil)
 588   (let ((revert-buffer-function nil))
 589     (revert-buffer t no-confirm)
 590     (widen))
 591   (tar-mode))
 592
 593
 594 (defun tar-next-line (p)
 595   (interactive "p")
 596   (forward-line p)
 597   (if (eobp) nil (forward-char 36)))
 598
 599 (defun tar-previous-line (p)
 600   (interactive "p")
 601   (tar-next-line (- p)))
 602
 603 (defun tar-current-descriptor (&optional noerror)
 604   "Return the tar-descriptor of the current line, or signals an error."
 605   ;; I wish lines had plists, like in ZMACS...
 606   (or (nth (count-lines (point-min)
 607                         (save-excursion (beginning-of-line) (point)))
 608            tar-parse-info)
 609       (if noerror
 610           nil
 611           (error "This line does not describe a tar-file entry"))))
 612
 613 (defun tar-get-descriptor ()
 614   (let* ((descriptor (tar-current-descriptor))
 615          (tokens (tar-desc-tokens descriptor))
 616          (size (tar-header-size tokens))
 617          (link-p (tar-header-link-type tokens)))
 618     (if link-p
 619         (error "This is a %s, not a real file"
 620                (cond ((eq link-p 5) "directory")
 621                      ((eq link-p 20) "tar directory header")
 622                      ((eq link-p 29) "multivolume-continuation")
 623                      ((eq link-p 35) "sparse entry")
 624                      ((eq link-p 38) "volume header")
 625                      (t "link"))))
 626     (if (zerop size) (error "This is a zero-length file"))
 627     descriptor))
 628
 629 (defun tar-mouse-extract (event)
 630   "Extract a file whose tar directory line you click on."
 631   (interactive "e")
 632   (save-excursion
 633     (set-buffer (window-buffer (posn-window (event-end event))))
 634     (save-excursion
 635       (goto-char (posn-point (event-end event)))
 636       ;; Just make sure this doesn't get an error.
 637       (tar-get-descriptor)))
 638   (select-window (posn-window (event-end event)))
 639   (goto-char (posn-point (event-end event)))
 640   (tar-extract))
 641
 642 (defun tar-extract (&optional other-window-p)
 643   "In Tar mode, extract this entry of the tar file into its own buffer."
 644   (interactive)
 645   (let* ((view-p (eq other-window-p 'view))
 646          (descriptor (tar-get-descriptor))
 647          (tokens (tar-desc-tokens descriptor))
 648          (name (tar-header-name tokens))
 649          (size (tar-header-size tokens))
 650          (start (+ (tar-desc-data-start descriptor) tar-header-offset -1))
 651          (end (+ start size)))
 652     (let* ((tar-buffer (current-buffer))
 653            (bufname (concat (file-name-nondirectory name)
 654                             " (" name " in "
 655                             (file-name-nondirectory (buffer-file-name))
 656                             ")"))
 657            (read-only-p (or buffer-read-only view-p))
 658            (buffer (get-buffer bufname))
 659            (just-created nil))
 660       (if buffer
 661           nil
 662         (setq buffer (get-buffer-create bufname))
 663         (setq just-created t)
 664         (unwind-protect
 665             (progn
 666               (widen)
 667               (save-excursion
 668                 (set-buffer buffer)
 669                 (insert-buffer-substring tar-buffer start end)
 670                 (goto-char 0)
 671                 (set-visited-file-name name) ; give it a name to decide mode.
 672                 (normal-mode)  ; pick a mode.
 673                 (set-visited-file-name nil)  ; nuke the name - not meaningful.
 674                 (rename-buffer bufname)
 675
 676                 (make-local-variable 'tar-superior-buffer)
 677                 (make-local-variable 'tar-superior-descriptor)
 678                 (setq tar-superior-buffer tar-buffer)
 679                 (setq tar-superior-descriptor descriptor)
 680                 (tar-subfile-mode 1)
 681
 682                 (setq buffer-read-only read-only-p)
 683                 (set-buffer-modified-p nil))
 684               (set-buffer tar-buffer))
 685           (narrow-to-region 1 tar-header-offset)))
 686       (if view-p
 687           (progn
 688             (view-buffer buffer)
 689             (and just-created
 690                  (setq view-exit-action 'kill-buffer)))
 691         (if (eq other-window-p 'display)
 692             (display-buffer buffer)
 693           (if other-window-p
 694               (switch-to-buffer-other-window buffer)
 695             (switch-to-buffer buffer)))))))
 696
 697
 698 (defun tar-extract-other-window ()
 699   "*In Tar mode, find this entry of the tar file in another window."
 700   (interactive)
 701   (tar-extract t))
 702
 703 (defun tar-display-other-window ()
 704   "*In Tar mode, display this entry of the tar file in another window."
 705   (interactive)
 706   (tar-extract 'display))
 707
 708 (defun tar-view ()
 709   "*In Tar mode, view the tar file entry on this line."
 710   (interactive)
 711   (tar-extract 'view))
 712
 713
 714 (defun tar-read-file-name (&optional prompt)
 715   "Read a file name with this line's entry as the default."
 716   (or prompt (setq prompt "Copy to: "))
 717   (let* ((default-file (expand-file-name
 718                         (tar-header-name (tar-desc-tokens
 719                                           (tar-current-descriptor)))))
 720          (target (expand-file-name
 721                   (read-file-name prompt
 722                                   (file-name-directory default-file)
 723                                   default-file nil))))
 724     (if (or (string= "" (file-name-nondirectory target))
 725             (file-directory-p target))
 726         (setq target (concat (if (string-match "/$" target)
 727                                  (substring target 0 (1- (match-end 0)))
 728                                  target)
 729                              "/"
 730                              (file-name-nondirectory default-file))))
 731     target))
 732
 733
 734 (defun tar-copy (&optional to-file)
 735   "*In Tar mode, extract this entry of the tar file into a file on disk.
 736 If TO-FILE is not supplied, it is prompted for, defaulting to the name of
 737 the current tar-entry."
 738   (interactive (list (tar-read-file-name)))
 739   (let* ((descriptor (tar-get-descriptor))
 740          (tokens (tar-desc-tokens descriptor))
 741          (name (tar-header-name tokens))
 742          (size (tar-header-size tokens))
 743          (start (+ (tar-desc-data-start descriptor) tar-header-offset -1))
 744          (end (+ start size)))
 745     (let* ((tar-buffer (current-buffer))
 746            buffer)
 747       (unwind-protect
 748           (progn
 749             (setq buffer (generate-new-buffer "*tar-copy-tmp*"))
 750             (widen)
 751             (save-excursion
 752               (set-buffer buffer)
 753               (insert-buffer-substring tar-buffer start end)
 754               (set-buffer-modified-p nil) ; in case we abort
 755               (write-file to-file)
 756               (message "Copied tar entry %s to %s" name to-file)
 757               (set-buffer tar-buffer)))
 758         (narrow-to-region 1 tar-header-offset)
 759         (if buffer (kill-buffer buffer)))
 760       )))
 761
 762
 763 (defun tar-flag-deleted (p &optional unflag)
 764   "*In Tar mode, mark this sub-file to be deleted from the tar file.
 765 With a prefix argument, mark that many files."
 766   (interactive "p")
 767   (beginning-of-line)
 768   (tar-dotimes (i (if (< p 0) (- p) p))
 769     (if (tar-current-descriptor unflag) ; barf if we're not on an entry-line.
 770         (progn
 771           (delete-char 1)
 772           (insert (if unflag " " "D"))))
 773     (forward-line (if (< p 0) -1 1)))
 774   (if (eobp) nil (forward-char 36)))
 775
 776 (defun tar-unflag (p)
 777   "*In Tar mode, un-mark this sub-file if it is marked to be deleted.
 778 With a prefix argument, un-mark that many files forward."
 779   (interactive "p")
 780   (tar-flag-deleted p t))
 781
 782 (defun tar-unflag-backwards (p)
 783   "*In Tar mode, un-mark this sub-file if it is marked to be deleted.
 784 With a prefix argument, un-mark that many files backward."
 785   (interactive "p")
 786   (tar-flag-deleted (- p) t))
 787
 788
 789 (defun tar-expunge-internal ()
 790   "Expunge the tar-entry specified by the current line."
 791   (let* ((descriptor (tar-current-descriptor))
 792          (tokens (tar-desc-tokens descriptor))
 793          (line (tar-desc-data-start descriptor))
 794          (name (tar-header-name tokens))
 795          (size (tar-header-size tokens))
 796          (link-p (tar-header-link-type tokens))
 797          (start (tar-desc-data-start descriptor))
 798          (following-descs (cdr (memq descriptor tar-parse-info))))
 799     (if link-p (setq size 0)) ; size lies for hard-links.
 800     ;;
 801     ;; delete the current line...
 802     (beginning-of-line)
 803     (let ((line-start (point)))
 804       (end-of-line) (forward-char)
 805       (let ((line-len (- (point) line-start)))
 806         (delete-region line-start (point))
 807         ;;
 808         ;; decrement the header-pointer to be in synch...
 809         (setq tar-header-offset (- tar-header-offset line-len))))
 810     ;;
 811     ;; delete the data pointer...
 812     (setq tar-parse-info (delq descriptor tar-parse-info))
 813     ;;
 814     ;; delete the data from inside the file...
 815     (widen)
 816     (let* ((data-start (+ start tar-header-offset -513))
 817            (data-end (+ data-start 512 (ash (ash (+ size 511) -9) 9))))
 818       (delete-region data-start data-end)
 819       ;;
 820       ;; and finally, decrement the start-pointers of all following
 821       ;; entries in the archive.  This is a pig when deleting a bunch
 822       ;; of files at once - we could optimize this to only do the
 823       ;; iteration over the files that remain, or only iterate up to
 824       ;; the next file to be deleted.
 825       (let ((data-length (- data-end data-start)))
 826         (tar-dolist (desc following-descs)
 827           (tar-setf (tar-desc-data-start desc)
 828                     (- (tar-desc-data-start desc) data-length))))
 829       ))
 830   (narrow-to-region 1 tar-header-offset))
 831
 832
 833 (defun tar-expunge (&optional noconfirm)
 834   "*In Tar mode, delete all the archived files flagged for deletion.
 835 This does not modify the disk image; you must save the tar file itself
 836 for this to be permanent."
 837   (interactive)
 838   (if (or noconfirm
 839           (y-or-n-p "expunge files marked for deletion? "))
 840       (let ((n 0))
 841         (save-excursion
 842           (goto-char 0)
 843           (while (not (eobp))
 844             (if (looking-at "D")
 845                 (progn (tar-expunge-internal)
 846                        (setq n (1+ n)))
 847                 (forward-line 1)))
 848           ;; after doing the deletions, add any padding that may be necessary.
 849           (tar-pad-to-blocksize)
 850           (narrow-to-region 1 tar-header-offset)
 851           )
 852         (if (zerop n)
 853             (message "nothing to expunge.")
 854             (message "%s expunged.  Be sure to save this buffer." n)))))
 855
 856
 857 (defun tar-clear-modification-flags ()
 858   "Remove the stars at the beginning of each line."
 859   (save-excursion
 860     (goto-char 0)
 861     (while (< (point) tar-header-offset)
 862       (if (looking-at "*")
 863           (progn (delete-char 1) (insert " ")))
 864       (forward-line 1))))
 865
 866
 867 (defun tar-chown-entry (new-uid)
 868   "*Change the user-id associated with this entry in the tar file.
 869 If this tar file was written by GNU tar, then you will be able to edit
 870 the user id as a string; otherwise, you must edit it as a number.
 871 You can force editing as a number by calling this with a prefix arg.
 872 This does not modify the disk image; you must save the tar file itself
 873 for this to be permanent."
 874   (interactive (list
 875                  (let ((tokens (tar-desc-tokens (tar-current-descriptor))))
 876                    (if (or current-prefix-arg
 877                            (not (tar-header-magic tokens)))
 878                        (let (n)
 879                          (while (not (numberp (setq n (read-minibuffer
 880                                                         "New UID number: "
 881                                                         (format "%s" (tar-header-uid tokens)))))))
 882                          n)
 883                        (read-string "New UID string: " (tar-header-uname tokens))))))
 884   (cond ((stringp new-uid)
 885          (tar-setf (tar-header-uname (tar-desc-tokens (tar-current-descriptor)))
 886                    new-uid)
 887          (tar-alter-one-field tar-uname-offset (concat new-uid "\000")))
 888         (t
 889          (tar-setf (tar-header-uid (tar-desc-tokens (tar-current-descriptor)))
 890                    new-uid)
 891          (tar-alter-one-field tar-uid-offset
 892            (concat (substring (format "%6o" new-uid) 0 6) "\000 ")))))
 893
 894
 895 (defun tar-chgrp-entry (new-gid)
 896   "*Change the group-id associated with this entry in the tar file.
 897 If this tar file was written by GNU tar, then you will be able to edit
 898 the group id as a string; otherwise, you must edit it as a number.
 899 You can force editing as a number by calling this with a prefix arg.
 900 This does not modify the disk image; you must save the tar file itself
 901 for this to be permanent."
 902   (interactive (list
 903                  (let ((tokens (tar-desc-tokens (tar-current-descriptor))))
 904                    (if (or current-prefix-arg
 905                            (not (tar-header-magic tokens)))
 906                        (let (n)
 907                          (while (not (numberp (setq n (read-minibuffer
 908                                                         "New GID number: "
 909                                                         (format "%s" (tar-header-gid tokens)))))))
 910                          n)
 911                        (read-string "New GID string: " (tar-header-gname tokens))))))
 912   (cond ((stringp new-gid)
 913          (tar-setf (tar-header-gname (tar-desc-tokens (tar-current-descriptor)))
 914                    new-gid)
 915          (tar-alter-one-field tar-gname-offset
 916            (concat new-gid "\000")))
 917         (t
 918          (tar-setf (tar-header-gid (tar-desc-tokens (tar-current-descriptor)))
 919                    new-gid)
 920          (tar-alter-one-field tar-gid-offset
 921            (concat (substring (format "%6o" new-gid) 0 6) "\000 ")))))
 922
 923 (defun tar-rename-entry (new-name)
 924   "*Change the name associated with this entry in the tar file.
 925 This does not modify the disk image; you must save the tar file itself
 926 for this to be permanent."
 927   (interactive
 928     (list (read-string "New name: "
 929             (tar-header-name (tar-desc-tokens (tar-current-descriptor))))))
 930   (if (string= "" new-name) (error "zero length name"))
 931   (if (> (length new-name) 98) (error "name too long"))
 932   (tar-setf (tar-header-name (tar-desc-tokens (tar-current-descriptor)))
 933             new-name)
 934   (tar-alter-one-field 0
 935     (substring (concat new-name (make-string 99 0)) 0 99)))
 936
 937
 938 (defun tar-chmod-entry (new-mode)
 939   "*Change the protection bits associated with this entry in the tar file.
 940 This does not modify the disk image; you must save the tar file itself
 941 for this to be permanent."
 942   (interactive (list (tar-parse-octal-integer-safe
 943                        (read-string "New protection (octal): "))))
 944   (tar-setf (tar-header-mode (tar-desc-tokens (tar-current-descriptor)))
 945             new-mode)
 946   (tar-alter-one-field tar-mode-offset
 947     (concat (substring (format "%6o" new-mode) 0 6) "\000 ")))
 948
 949
 950 (defun tar-alter-one-field (data-position new-data-string)
 951   (let* ((descriptor (tar-current-descriptor))
 952          (tokens (tar-desc-tokens descriptor)))
 953     (unwind-protect
 954         (save-excursion
 955           ;;
 956           ;; update the header-line.
 957           (beginning-of-line)
 958           (let ((p (point)))
 959             (forward-line 1)
 960             (delete-region p (point))
 961             (insert (summarize-tar-header-block tokens) "\n")
 962             (setq tar-header-offset (point-max)))
 963
 964           (widen)
 965           (let* ((start (+ (tar-desc-data-start descriptor) tar-header-offset -513)))
 966             ;;
 967             ;; delete the old field and insert a new one.
 968             (goto-char (+ start data-position))
 969             (delete-region (point) (+ (point) (length new-data-string))) ; <--
 970             (insert new-data-string) ; <--
 971             ;;
 972             ;; compute a new checksum and insert it.
 973             (let ((chk (checksum-tar-header-block
 974                         (buffer-substring start (+ start 512)))))
 975               (goto-char (+ start tar-chk-offset))
 976               (delete-region (point) (+ (point) 8))
 977               (insert (format "%6o" chk))
 978               (insert 0)
 979               (insert ? )
 980               (tar-setf (tar-header-checksum tokens) chk)
 981               ;;
 982               ;; ok, make sure we didn't botch it.
 983               (check-tar-header-block-checksum
 984                 (buffer-substring start (+ start 512))
 985                 chk (tar-header-name tokens))
 986               )))
 987       (narrow-to-region 1 tar-header-offset))))
 988
 989
 990 (defun tar-octal-time (timeval)
 991   ;; Format a timestamp as 11 octal digits.  Ghod, I hope this works...
 992   (let ((hibits (car timeval)) (lobits (car (cdr timeval))))
 993     (insert (format "%05o%01o%05o"
 994                     (lsh hibits -2)
 995                     (logior (lsh (logand 3 hibits) 1) (> (logand lobits 32768) 0))
 996                     (logand 32767 lobits)
 997                     ))))
 998
 999 (defun tar-subfile-save-buffer ()
1000   "In tar subfile mode, save this buffer into its parent tar-file buffer.
1001 This doesn't write anything to disk; you must save the parent tar-file buffer
1002 to make your changes permanent."
1003   (interactive)
1004   (if (not (and (boundp 'tar-superior-buffer) tar-superior-buffer))
1005     (error "This buffer has no superior tar file buffer"))
1006   (if (not (and (boundp 'tar-superior-descriptor) tar-superior-descriptor))
1007     (error "This buffer doesn't have an index into its superior tar file!"))
1008   (save-excursion
1009   (let ((subfile (current-buffer))
1010         (subfile-size (buffer-size))
1011         (descriptor tar-superior-descriptor))
1012     (set-buffer tar-superior-buffer)
1013     (let* ((tokens (tar-desc-tokens descriptor))
1014            (start (tar-desc-data-start descriptor))
1015            (name (tar-header-name tokens))
1016            (size (tar-header-size tokens))
1017            (size-pad (ash (ash (+ size 511) -9) 9))
1018            (head (memq descriptor tar-parse-info))
1019            (following-descs (cdr head)))
1020       (if (not head)
1021         (error "Can't find this tar file entry in its parent tar file!"))
1022       (unwind-protect
1023        (save-excursion
1024         (widen)
1025         ;; delete the old data...
1026         (let* ((data-start (+ start tar-header-offset -1))
1027                (data-end (+ data-start (ash (ash (+ size 511) -9) 9))))
1028           (delete-region data-start data-end)
1029           ;; insert the new data...
1030           (goto-char data-start)
1031           (insert-buffer subfile)
1032           ;;
1033           ;; pad the new data out to a multiple of 512...
1034           (let ((subfile-size-pad (ash (ash (+ subfile-size 511) -9) 9)))
1035             (goto-char (+ data-start subfile-size))
1036             (insert (make-string (- subfile-size-pad subfile-size) 0))
1037             ;;
1038             ;; update the data pointer of this and all following files...
1039             (tar-setf (tar-header-size tokens) subfile-size)
1040             (let ((difference (- subfile-size-pad size-pad)))
1041               (tar-dolist (desc following-descs)
1042                 (tar-setf (tar-desc-data-start desc)
1043                           (+ (tar-desc-data-start desc) difference))))
1044             ;;
1045             ;; Update the size field in the header block.
1046             (let ((header-start (- data-start 512)))
1047               (goto-char (+ header-start tar-size-offset))
1048               (delete-region (point) (+ (point) 12))
1049               (insert (format "%11o" subfile-size))
1050               (insert ? )
1051               ;;
1052               ;; Maybe update the datestamp.
1053               (if (not tar-update-datestamp)
1054                   nil
1055                 (goto-char (+ header-start tar-time-offset))
1056                 (delete-region (point) (+ (point) 12))
1057                 (insert (tar-octal-time (current-time)))
1058                 (insert ? ))
1059               ;;
1060               ;; compute a new checksum and insert it.
1061               (let ((chk (checksum-tar-header-block
1062                           (buffer-substring header-start data-start))))
1063                 (goto-char (+ header-start tar-chk-offset))
1064                 (delete-region (point) (+ (point) 8))
1065                 (insert (format "%6o" chk))
1066                 (insert 0)
1067                 (insert ? )
1068                 (tar-setf (tar-header-checksum tokens) chk)))
1069             ;;
1070             ;; alter the descriptor-line...
1071             ;;
1072             (let ((position (- (length tar-parse-info) (length head))))
1073               (goto-char 1)
1074               (next-line position)
1075               (beginning-of-line)
1076               (let ((p (point))
1077                     (m (set-marker (make-marker) tar-header-offset)))
1078                 (forward-line 1)
1079                 (delete-region p (point))
1080                 (insert-before-markers (summarize-tar-header-block tokens t) "\n")
1081                 (setq tar-header-offset (marker-position m)))
1082               )))
1083         ;; after doing the insertion, add any final padding that may be necessary.
1084         (tar-pad-to-blocksize))
1085        (narrow-to-region 1 tar-header-offset)))
1086     (set-buffer-modified-p t)   ; mark the tar file as modified
1087     (set-buffer subfile)
1088     (set-buffer-modified-p nil) ; mark the tar subfile as unmodified
1089     (message "saved into tar-buffer \"%s\" - remember to save that buffer!"
1090              (buffer-name tar-superior-buffer))
1091     ;; Prevent ordinary saving from happening.
1092     t)))
1093
1094
1095 (defun tar-pad-to-blocksize ()
1096   "If we are being anal about tar file blocksizes, fix up the current buffer.
1097 Leaves the region wide."
1098   (if (null tar-anal-blocksize)
1099       nil
1100     (widen)
1101     (let* ((last-desc (nth (1- (length tar-parse-info)) tar-parse-info))
1102            (start (tar-desc-data-start last-desc))
1103            (tokens (tar-desc-tokens last-desc))
1104            (link-p (tar-header-link-type tokens))
1105            (size (if link-p 0 (tar-header-size tokens)))
1106            (data-end (+ start size))
1107            (bbytes (ash tar-anal-blocksize 9))
1108            (pad-to (+ bbytes (* bbytes (/ (1- data-end) bbytes))))
1109            (inhibit-read-only t) ; ##
1110            )
1111       ;; If the padding after the last data is too long, delete some;
1112       ;; else insert some until we are padded out to the right number of blocks.
1113       ;;
1114       (goto-char (+ (or tar-header-offset 0) data-end))
1115       (if (> (1+ (buffer-size)) (+ (or tar-header-offset 0) pad-to))
1116           (delete-region (+ (or tar-header-offset 0) pad-to) (1+ (buffer-size)))
1117           (insert (make-string (- (+ (or tar-header-offset 0) pad-to)
1118                                   (1+ (buffer-size)))
1119                                0)))
1120       )))
1121
1122
1123 ;; Used in write-file-hook to write tar-files out correctly.
1124 (defun tar-mode-maybe-write-tar-file ()
1125   ;;
1126   ;; If the current buffer is in Tar mode and has its header-offset set,
1127   ;; only write out the part of the file after the header-offset.
1128   ;;
1129   (if (and (eq major-mode 'tar-mode)
1130            (and (boundp 'tar-header-offset) tar-header-offset))
1131       (unwind-protect
1132         (save-excursion
1133           (tar-clear-modification-flags)
1134           (widen)
1135           ;; Doing this here confuses things - the region gets left too wide!
1136           ;; I suppose this is run in a context where changing the buffer is bad.
1137           ;; (tar-pad-to-blocksize)
1138           (write-region tar-header-offset (1+ (buffer-size)) buffer-file-name nil t)
1139           ;; return T because we've written the file.
1140           t)
1141         (narrow-to-region 1 tar-header-offset)
1142         t)
1143       ;; return NIL because we haven't.
1144       nil))
1145
1146 \f
1147 ;;; Patch it in.
1148
1149 (or (memq 'tar-mode-maybe-write-tar-file write-file-hooks)
1150     (setq write-file-hooks
1151           (cons 'tar-mode-maybe-write-tar-file write-file-hooks)))
1152
1153 (provide 'tar-mode)
1154
1155 ;;; tar-mode.el ends here