lisp/tar-mode.el

   1 ;;; tar-mode.el --- simple editing of tar files from GNU emacs
   2
   3 ;;; Copyright (C) 1990, 1991, 1993, 1994 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 ;;; Rationale:
  85
  86 ;;; Why does tar-mode edit the file itself instead of using tar?
  87
  88 ;;; That means that you can edit tar files which you don't have room for
  89 ;;; on your local disk.
  90
  91 ;;; I don't know about recent features in gnu tar, but old versions of tar
  92 ;;; can't replace a file in the middle of a tar file with a new version.
  93 ;;; Tar-mode can.  I don't think tar can do things like chmod the subfiles.
  94 ;;; An implementation which involved unpacking and repacking the file into
  95 ;;; some scratch directory would be very wasteful, and wouldn't be able to
  96 ;;; preserve the file owners.
  97
  98 ;;; Code:
  99
 100 (defvar tar-anal-blocksize 20
 101   "*The blocksize of tar files written by Emacs, or nil, meaning don't care.
 102 The blocksize of a tar file is not really the size of the blocks; rather, it is
 103 the number of blocks written with one system call.  When tarring to a tape,
 104 this is the size of the *tape* blocks, but when writing to a file, it doesn't
 105 matter much.  The only noticeable difference is that if a tar file does not
 106 have a blocksize of 20, tar will tell you that; all this really controls is
 107 how many null padding bytes go on the end of the tar file.")
 108
 109 (defvar tar-update-datestamp nil
 110   "*Whether tar-mode should play fast and loose with sub-file datestamps;
 111 if this is true, then editing and saving a tar file entry back into its
 112 tar file will update its datestamp.  If false, the datestamp is unchanged.
 113 You may or may not want this - it is good in that you can tell when a file
 114 in a tar archive has been changed, but it is bad for the same reason that
 115 editing a file in the tar archive at all is bad - the changed version of
 116 the file never exists on disk.")
 117
 118 (defvar tar-parse-info nil)
 119 (defvar tar-header-offset nil)
 120 (defvar tar-superior-buffer nil)
 121 (defvar tar-superior-descriptor nil)
 122 (defvar tar-subfile-mode nil)
 123
 124 (put 'tar-parse-info 'permanent-local t)
 125 (put 'tar-header-offset 'permanent-local t)
 126 (put 'tar-superior-buffer 'permanent-local t)
 127 (put 'tar-superior-descriptor 'permanent-local t)
 128 \f
 129 ;;; First, duplicate some Common Lisp functions; I used to just (require 'cl)
 130 ;;; but "cl.el" was messing some people up (also it's really big).
 131
 132 (defmacro tar-setf (form val)
 133   "A mind-numbingly simple implementation of setf."
 134   (let ((mform (macroexpand form (and (boundp 'byte-compile-macro-environment)
 135                                       byte-compile-macro-environment))))
 136     (cond ((symbolp mform) (list 'setq mform val))
 137           ((not (consp mform)) (error "can't setf %s" form))
 138           ((eq (car mform) 'aref)
 139            (list 'aset (nth 1 mform) (nth 2 mform) val))
 140           ((eq (car mform) 'car)
 141            (list 'setcar (nth 1 mform) val))
 142           ((eq (car mform) 'cdr)
 143            (list 'setcdr (nth 1 mform) val))
 144           (t (error "don't know how to setf %s" form)))))
 145
 146 (defmacro tar-dolist (control &rest body)
 147   "syntax: (dolist (var-name list-expr &optional return-value) &body body)"
 148   (let ((var (car control))
 149         (init (car (cdr control)))
 150         (val (car (cdr (cdr control)))))
 151     (list 'let (list (list '_dolist_iterator_ init))
 152           (list 'while '_dolist_iterator_
 153             (cons 'let
 154               (cons (list (list var '(car _dolist_iterator_)))
 155                     (append body
 156                             (list (list 'setq '_dolist_iterator_
 157                                         (list 'cdr '_dolist_iterator_)))))))
 158           val)))
 159
 160 (defmacro tar-dotimes (control &rest body)
 161   "syntax: (dolist (var-name count-expr &optional return-value) &body body)"
 162   (let ((var (car control))
 163         (n (car (cdr control)))
 164         (val (car (cdr (cdr control)))))
 165     (list 'let (list (list '_dotimes_end_ n)
 166                      (list var 0))
 167           (cons 'while
 168                 (cons (list '< var '_dotimes_end_)
 169                       (append body
 170                               (list (list 'setq var (list '1+ var))))))
 171           val)))
 172
 173 \f
 174 ;;; down to business.
 175
 176 (defmacro make-tar-header (name mode uid git size date ck lt ln
 177                            magic uname gname devmaj devmin)
 178   (list 'vector name mode uid git size date ck lt ln
 179         magic uname gname devmaj devmin))
 180
 181 (defmacro tar-header-name (x) (list 'aref x 0))
 182 (defmacro tar-header-mode (x) (list 'aref x 1))
 183 (defmacro tar-header-uid  (x) (list 'aref x 2))
 184 (defmacro tar-header-gid  (x) (list 'aref x 3))
 185 (defmacro tar-header-size (x) (list 'aref x 4))
 186 (defmacro tar-header-date (x) (list 'aref x 5))
 187 (defmacro tar-header-checksum  (x) (list 'aref x 6))
 188 (defmacro tar-header-link-type (x) (list 'aref x 7))
 189 (defmacro tar-header-link-name (x) (list 'aref x 8))
 190 (defmacro tar-header-magic (x) (list 'aref x 9))
 191 (defmacro tar-header-uname (x) (list 'aref x 10))
 192 (defmacro tar-header-gname (x) (list 'aref x 11))
 193 (defmacro tar-header-dmaj (x) (list 'aref x 12))
 194 (defmacro tar-header-dmin (x) (list 'aref x 13))
 195
 196 (defmacro make-tar-desc (data-start tokens)
 197   (list 'cons data-start tokens))
 198
 199 (defmacro tar-desc-data-start (x) (list 'car x))
 200 (defmacro tar-desc-tokens     (x) (list 'cdr x))
 201
 202 (defconst tar-name-offset 0)
 203 (defconst tar-mode-offset (+ tar-name-offset 100))
 204 (defconst tar-uid-offset  (+ tar-mode-offset 8))
 205 (defconst tar-gid-offset  (+ tar-uid-offset 8))
 206 (defconst tar-size-offset (+ tar-gid-offset 8))
 207 (defconst tar-time-offset (+ tar-size-offset 12))
 208 (defconst tar-chk-offset  (+ tar-time-offset 12))
 209 (defconst tar-linkp-offset (+ tar-chk-offset 8))
 210 (defconst tar-link-offset (+ tar-linkp-offset 1))
 211 ;;; GNU-tar specific slots.
 212 (defconst tar-magic-offset (+ tar-link-offset 100))
 213 (defconst tar-uname-offset (+ tar-magic-offset 8))
 214 (defconst tar-gname-offset (+ tar-uname-offset 32))
 215 (defconst tar-dmaj-offset (+ tar-gname-offset 32))
 216 (defconst tar-dmin-offset (+ tar-dmaj-offset 8))
 217 (defconst tar-end-offset (+ tar-dmin-offset 8))
 218
 219 (defun tar-header-block-tokenize (string)
 220   "Return a `tar-header' structure.
 221 This is a list of name, mode, uid, gid, size,
 222 write-date, checksum, link-type, and link-name."
 223   (cond ((< (length string) 512) nil)
 224         (;(some 'plusp string)           ; <-- oops, massive cycle hog!
 225          (or (not (= 0 (aref string 0))) ; This will do.
 226              (not (= 0 (aref string 101))))
 227          (let* ((name-end (1- tar-mode-offset))
 228                 (link-end (1- tar-magic-offset))
 229                 (uname-end (1- tar-gname-offset))
 230                 (gname-end (1- tar-dmaj-offset))
 231                 (link-p (aref string tar-linkp-offset))
 232                 (magic-str (substring string tar-magic-offset (1- tar-uname-offset)))
 233                 (uname-valid-p (or (string= "ustar  " magic-str) (string= "GNUtar " magic-str)))
 234                 name
 235                 (nulsexp   "[^\000]*\000"))
 236            (and (string-match nulsexp string tar-name-offset) (setq name-end (min name-end (1- (match-end 0)))))
 237            (and (string-match nulsexp string tar-link-offset) (setq link-end (min link-end (1- (match-end 0)))))
 238            (and (string-match nulsexp string tar-uname-offset) (setq uname-end (min uname-end (1- (match-end 0)))))
 239            (and (string-match nulsexp string tar-gname-offset) (setq gname-end (min gname-end (1- (match-end 0)))))
 240            (setq name (substring string tar-name-offset name-end)
 241                  link-p (if (or (= link-p 0) (= link-p ?0))
 242                             nil
 243                           (- link-p ?0)))
 244            (if (and (null link-p) (string-match "/$" name)) (setq link-p 5)) ; directory
 245            (make-tar-header
 246              name
 247              (tar-parse-octal-integer string tar-mode-offset (1- tar-uid-offset))
 248              (tar-parse-octal-integer string tar-uid-offset (1- tar-gid-offset))
 249              (tar-parse-octal-integer string tar-gid-offset (1- tar-size-offset))
 250              (tar-parse-octal-integer string tar-size-offset (1- tar-time-offset))
 251              (tar-parse-octal-integer string tar-time-offset (1- tar-chk-offset))
 252              (tar-parse-octal-integer string tar-chk-offset (1- tar-linkp-offset))
 253              link-p
 254              (substring string tar-link-offset link-end)
 255              uname-valid-p
 256              (and uname-valid-p (substring string tar-uname-offset uname-end))
 257              (and uname-valid-p (substring string tar-gname-offset gname-end))
 258              (tar-parse-octal-integer string tar-dmaj-offset (1- tar-dmin-offset))
 259              (tar-parse-octal-integer string tar-dmin-offset (1- tar-end-offset))
 260              )))
 261         (t 'empty-tar-block)))
 262
 263
 264 (defun tar-parse-octal-integer (string &optional start end)
 265   (if (null start) (setq start 0))
 266   (if (null end) (setq end (length string)))
 267   (if (= (aref string start) 0)
 268       0
 269     (let ((n 0))
 270       (while (< start end)
 271         (setq n (if (< (aref string start) ?0) n
 272                   (+ (* n 8) (- (aref string start) 48)))
 273               start (1+ start)))
 274       n)))
 275
 276 (defun tar-parse-octal-integer-safe (string)
 277   (let ((L (length string)))
 278     (if (= L 0) (error "empty string"))
 279     (tar-dotimes (i L)
 280        (if (or (< (aref string i) ?0)
 281                (> (aref string i) ?7))
 282            (error "'%c' is not an octal digit"))))
 283   (tar-parse-octal-integer string))
 284
 285
 286 (defun tar-header-block-checksum (string)
 287   "Compute and return a tar-acceptable checksum for this block."
 288   (let* ((chk-field-start tar-chk-offset)
 289          (chk-field-end (+ chk-field-start 8))
 290          (sum 0)
 291          (i 0))
 292     ;; Add up all of the characters except the ones in the checksum field.
 293     ;; Add that field as if it were filled with spaces.
 294     (while (< i chk-field-start)
 295       (setq sum (+ sum (aref string i))
 296             i (1+ i)))
 297     (setq i chk-field-end)
 298     (while (< i 512)
 299       (setq sum (+ sum (aref string i))
 300             i (1+ i)))
 301     (+ sum (* 32 8))))
 302
 303 (defun tar-header-block-check-checksum (hblock desired-checksum file-name)
 304   "Beep and print a warning if the checksum doesn't match."
 305   (if (not (= desired-checksum (tar-header-block-checksum hblock)))
 306       (progn (beep) (message "Invalid checksum for file %s!" file-name))))
 307
 308 (defun tar-header-block-recompute-checksum (hblock)
 309   "Modifies the given string to have a valid checksum field."
 310   (let* ((chk (tar-header-block-checksum hblock))
 311          (chk-string (format "%6o" chk))
 312          (l (length chk-string)))
 313     (aset hblock 154 0)
 314     (aset hblock 155 32)
 315     (tar-dotimes (i l) (aset hblock (- 153 i) (aref chk-string (- l i 1)))))
 316   hblock)
 317
 318
 319 (defun tar-grind-file-mode (mode string start)
 320   "Write a \"-rw--r--r-\" representing MODE into STRING beginning at START."
 321   (aset string start       (if (zerop (logand 256 mode)) ?- ?r))
 322   (aset string (+ start 1) (if (zerop (logand 128 mode)) ?- ?w))
 323   (aset string (+ start 2) (if (zerop (logand  64 mode)) ?- ?x))
 324   (aset string (+ start 3) (if (zerop (logand  32 mode)) ?- ?r))
 325   (aset string (+ start 4) (if (zerop (logand  16 mode)) ?- ?w))
 326   (aset string (+ start 5) (if (zerop (logand   8 mode)) ?- ?x))
 327   (aset string (+ start 6) (if (zerop (logand   4 mode)) ?- ?r))
 328   (aset string (+ start 7) (if (zerop (logand   2 mode)) ?- ?w))
 329   (aset string (+ start 8) (if (zerop (logand   1 mode)) ?- ?x))
 330   (if (zerop (logand 1024 mode)) nil (aset string (+ start 2) ?s))
 331   (if (zerop (logand 2048 mode)) nil (aset string (+ start 5) ?s))
 332   string)
 333
 334 (defun tar-header-block-summarize (tar-hblock &optional mod-p)
 335   "Returns a line similar to the output of `tar -vtf'."
 336   (let ((name (tar-header-name tar-hblock))
 337         (mode (tar-header-mode tar-hblock))
 338         (uid (tar-header-uid tar-hblock))
 339         (gid (tar-header-gid tar-hblock))
 340         (uname (tar-header-uname tar-hblock))
 341         (gname (tar-header-gname tar-hblock))
 342         (size (tar-header-size tar-hblock))
 343         (time (tar-header-date tar-hblock))
 344         (ck (tar-header-checksum tar-hblock))
 345         (link-p (tar-header-link-type tar-hblock))
 346         (link-name (tar-header-link-name tar-hblock))
 347         )
 348     (let* ((left 11)
 349            (namew 8)
 350            (groupw 8)
 351            (sizew 8)
 352            (datew 2)
 353            (slash (1- (+ left namew)))
 354            (lastdigit (+ slash groupw sizew))
 355            (namestart (+ lastdigit datew))
 356            (string (make-string (+ namestart (length name) (if link-p (+ 5 (length link-name)) 0)) 32))
 357            (type (tar-header-link-type tar-hblock)))
 358       (aset string 0 (if mod-p ?* ? ))
 359       (aset string 1
 360             (cond ((or (eq type nil) (eq type 0)) ?-)
 361                   ((eq type 1) ?l)  ; link
 362                   ((eq type 2) ?s)  ; symlink
 363                   ((eq type 3) ?c)  ; char special
 364                   ((eq type 4) ?b)  ; block special
 365                   ((eq type 5) ?d)  ; directory
 366                   ((eq type 6) ?p)  ; FIFO/pipe
 367                   ((eq type 20) ?*) ; directory listing
 368                   ((eq type 29) ?M) ; multivolume continuation
 369                   ((eq type 35) ?S) ; sparse
 370                   ((eq type 38) ?V) ; volume header
 371                   ))
 372       (tar-grind-file-mode mode string 2)
 373       (setq uid (if (= 0 (length uname)) (int-to-string uid) uname))
 374       (setq gid (if (= 0 (length gname)) (int-to-string gid) gname))
 375       (setq size (int-to-string size))
 376       (tar-dotimes (i (min (1- namew) (length uid))) (aset string (- slash i) (aref uid (- (length uid) i 1))))
 377       (aset string (1+ slash) ?/)
 378       (tar-dotimes (i (min (1- groupw) (length gid))) (aset string (+ (+ slash 2) i) (aref gid i)))
 379       (tar-dotimes (i (min sizew (length size))) (aset string (- lastdigit i) (aref size (- (length size) i 1))))
 380       ;; ## bloody hell, how do I print an arbitrary date??
 381       (tar-dotimes (i (length name)) (aset string (+ namestart i) (aref name i)))
 382       (if (or (eq link-p 1) (eq link-p 2))
 383           (progn
 384             (tar-dotimes (i 3) (aset string (+ namestart 1 (length name) i) (aref (if (= link-p 1) "==>" "-->") i)))
 385             (tar-dotimes (i (length link-name)) (aset string (+ namestart 5 (length name) i) (aref link-name i)))))
 386       (put-text-property namestart (length string)
 387                          'mouse-face 'highlight string)
 388       string)))
 389
 390
 391 (defun tar-summarize-buffer ()
 392   "Parse the contents of the tar file in the current buffer.
 393 Place a dired-like listing on the front;
 394 then narrow to it, so that only that listing
 395 is visible (and the real data of the buffer is hidden)."
 396   (message "parsing tar file...")
 397   (let* ((result '())
 398          (pos 1)
 399          (bs (max 1 (- (buffer-size) 1024))) ; always 2+ empty blocks at end.
 400          (bs100 (max 1 (/ bs 100)))
 401          tokens)
 402     (while (and (<= (+ pos 512) (point-max))
 403                 (not (eq 'empty-tar-block
 404                          (setq tokens
 405                                (tar-header-block-tokenize
 406                                 (buffer-substring pos (+ pos 512)))))))
 407       (setq pos (+ pos 512))
 408       (message "Parsing tar file...%d%%"
 409                ;(/ (* pos 100) bs)   ; this gets round-off lossage
 410                (/ pos bs100)         ; this doesn't
 411                )
 412       (if (eq (tar-header-link-type tokens) 20)
 413           ;; Foo.  There's an extra empty block after these.
 414           (setq pos (+ pos 512)))
 415       (let ((size (tar-header-size tokens)))
 416         (if (< size 0)
 417             (error "%s has size %s - corrupted"
 418                    (tar-header-name tokens) size))
 419         ;
 420         ; This is just too slow.  Don't really need it anyway....
 421         ;(tar-header-block-check-checksum
 422         ;  hblock (tar-header-block-checksum hblock)
 423         ;  (tar-header-name tokens))
 424
 425         (setq result (cons (make-tar-desc pos tokens) result))
 426
 427         (and (null (tar-header-link-type tokens))
 428              (> size 0)
 429              (setq pos
 430                    (+ pos 512 (ash (ash (1- size) -9) 9))        ; this works
 431                    ;(+ pos (+ size (- 512 (rem (1- size) 512)))) ; this doesn't
 432                    ))))
 433     (make-local-variable 'tar-parse-info)
 434     (setq tar-parse-info (nreverse result))
 435     ;; A tar file should end with a block or two of nulls,
 436     ;; but let's not get a fatal error if it doesn't.
 437     (if (eq tokens 'empty-tar-block)
 438         (message "Parsing tar file...done.")
 439       (message "Warning: premature EOF parsing tar file")))
 440   (save-excursion
 441     (goto-char (point-min))
 442     (let ((buffer-read-only nil))
 443       (tar-dolist (tar-desc tar-parse-info)
 444         (insert-string
 445           (tar-header-block-summarize (tar-desc-tokens tar-desc)))
 446         (insert-string "\n"))
 447       (make-local-variable 'tar-header-offset)
 448       (setq tar-header-offset (point))
 449       (narrow-to-region 1 tar-header-offset)
 450       (set-buffer-modified-p nil))))
 451 \f
 452 (defvar tar-mode-map nil "*Local keymap for Tar mode listings.")
 453
 454 (if tar-mode-map
 455     nil
 456   (setq tar-mode-map (make-keymap))
 457   (suppress-keymap tar-mode-map)
 458   (define-key tar-mode-map " " 'tar-next-line)
 459   (define-key tar-mode-map "c" 'tar-copy)
 460   (define-key tar-mode-map "d" 'tar-flag-deleted)
 461   (define-key tar-mode-map "\^D" 'tar-flag-deleted)
 462   (define-key tar-mode-map "e" 'tar-extract)
 463   (define-key tar-mode-map "f" 'tar-extract)
 464   (define-key tar-mode-map "\C-m" 'tar-extract)
 465   (define-key tar-mode-map [mouse-2] 'tar-mouse-extract)
 466   (define-key tar-mode-map "g" 'revert-buffer)
 467   (define-key tar-mode-map "h" 'describe-mode)
 468   (define-key tar-mode-map "n" 'tar-next-line)
 469   (define-key tar-mode-map "\^N" 'tar-next-line)
 470   (define-key tar-mode-map "o" 'tar-extract-other-window)
 471   (define-key tar-mode-map "p" 'tar-previous-line)
 472   (define-key tar-mode-map "\^P" 'tar-previous-line)
 473   (define-key tar-mode-map "r" 'tar-rename-entry)
 474   (define-key tar-mode-map "u" 'tar-unflag)
 475   (define-key tar-mode-map "v" 'tar-view)
 476   (define-key tar-mode-map "x" 'tar-expunge)
 477   (define-key tar-mode-map "\177" 'tar-unflag-backwards)
 478   (define-key tar-mode-map "E" 'tar-extract-other-window)
 479   (define-key tar-mode-map "M" 'tar-chmod-entry)
 480   (define-key tar-mode-map "G" 'tar-chgrp-entry)
 481   (define-key tar-mode-map "O" 'tar-chown-entry)
 482   )
 483 \f
 484 ;; Make menu bar items.
 485
 486 ;; Get rid of the Edit menu bar item to save space.
 487 (define-key tar-mode-map [menu-bar edit] 'undefined)
 488
 489 (define-key tar-mode-map [menu-bar immediate]
 490   (cons "Immediate" (make-sparse-keymap "Immediate")))
 491
 492 (define-key tar-mode-map [menu-bar immediate view]
 493   '("View This File" . tar-view))
 494 (define-key tar-mode-map [menu-bar immediate display]
 495   '("Display in Other Window" . tar-display-file))
 496 (define-key tar-mode-map [menu-bar immediate find-file-other-window]
 497   '("Find in Other Window" . tar-extract-other-window))
 498 (define-key tar-mode-map [menu-bar immediate find-file]
 499   '("Find This File" . tar-extract))
 500
 501 (define-key tar-mode-map [menu-bar mark]
 502   (cons "Mark" (make-sparse-keymap "Mark")))
 503
 504 (define-key tar-mode-map [menu-bar mark unmark-all]
 505   '("Unmark All" . tar-clear-modification-flags))
 506 (define-key tar-mode-map [menu-bar mark deletion]
 507   '("Flag" . tar-flag-deleted))
 508 (define-key tar-mode-map [menu-bar mark unmark]
 509   '("Unflag" . tar-unflag))
 510
 511 (define-key tar-mode-map [menu-bar operate]
 512   (cons "Operate" (make-sparse-keymap "Operate")))
 513
 514 (define-key tar-mode-map [menu-bar operate chown]
 515   '("Change Owner..." . tar-chown-entry))
 516 (define-key tar-mode-map [menu-bar operate chgrp]
 517   '("Change Group..." . tar-chgrp-entry))
 518 (define-key tar-mode-map [menu-bar operate chmod]
 519   '("Change Mode..." . tar-chmod-entry))
 520 (define-key tar-mode-map [menu-bar operate rename]
 521   '("Rename to..." . tar-rename-entry))
 522 (define-key tar-mode-map [menu-bar operate copy]
 523   '("Copy to..." . tar-copy))
 524 (define-key tar-mode-map [menu-bar operate expunge]
 525   '("Expunge marked files" . tar-expunge))
 526 \f
 527 ;; tar mode is suitable only for specially formatted data.
 528 (put 'tar-mode 'mode-class 'special)
 529 (put 'tar-subfile-mode 'mode-class 'special)
 530
 531 ;;;###autoload
 532 (defun tar-mode ()
 533   "Major mode for viewing a tar file as a dired-like listing of its contents.
 534 You can move around using the usual cursor motion commands.
 535 Letters no longer insert themselves.
 536 Type `e' to pull a file out of the tar file and into its own buffer;
 537 or click mouse-2 on the file's line in the Tar mode buffer.
 538 Type `c' to copy an entry from the tar file into another file on disk.
 539
 540 If you edit a sub-file of this archive (as with the `e' command) and
 541 save it with Control-x Control-s, the contents of that buffer will be
 542 saved back into the tar-file buffer; in this way you can edit a file
 543 inside of a tar archive without extracting it and re-archiving it.
 544
 545 See also: variables `tar-update-datestamp' and `tar-anal-blocksize'.
 546 \\{tar-mode-map}"
 547   ;; this is not interactive because you shouldn't be turning this
 548   ;; mode on and off.  You can corrupt things that way.
 549   ;; rms: with permanent locals, it should now be possible to make this work
 550   ;; interactively in some reasonable fashion.
 551   (kill-all-local-variables)
 552   (make-local-variable 'tar-header-offset)
 553   (make-local-variable 'tar-parse-info)
 554   (make-local-variable 'require-final-newline)
 555   (setq require-final-newline nil) ; binary data, dude...
 556   (make-local-variable 'revert-buffer-function)
 557   (setq revert-buffer-function 'tar-mode-revert)
 558   (make-local-variable 'enable-local-variables)
 559   (setq enable-local-variables nil)
 560   (setq major-mode 'tar-mode)
 561   (setq mode-name "Tar")
 562   (use-local-map tar-mode-map)
 563   (auto-save-mode 0)
 564   (widen)
 565   (if (and (boundp 'tar-header-offset) tar-header-offset)
 566       (narrow-to-region 1 tar-header-offset)
 567       (tar-summarize-buffer))
 568   (run-hooks 'tar-mode-hook)
 569   )
 570
 571
 572 ;; This should be converted to use a minor mode keymap.
 573
 574 (defun tar-subfile-mode (p)
 575   "Minor mode for editing an element of a tar-file.
 576 This mode redefines C-x C-s to save the current buffer back into its
 577 associated tar-file buffer.  You must save that buffer to actually
 578 save your changes to disk."
 579   (interactive "P")
 580   (or (and (boundp 'tar-superior-buffer) tar-superior-buffer)
 581       (error "This buffer is not an element of a tar file"))
 582 ;;; Don't do this, because it is redundant and wastes mode line space.
 583 ;;;  (or (assq 'tar-subfile-mode minor-mode-alist)
 584 ;;;      (setq minor-mode-alist (append minor-mode-alist
 585 ;;;                                  (list '(tar-subfile-mode " TarFile")))))
 586   (make-local-variable 'tar-subfile-mode)
 587   (setq tar-subfile-mode
 588         (if (null p)
 589             (not tar-subfile-mode)
 590             (> (prefix-numeric-value p) 0)))
 591   (cond (tar-subfile-mode
 592          (make-local-variable 'local-write-file-hooks)
 593          (setq local-write-file-hooks '(tar-subfile-save-buffer))
 594          ;; turn off auto-save.
 595          (auto-save-mode nil)
 596          (setq buffer-auto-save-file-name nil)
 597          (run-hooks 'tar-subfile-mode-hook))
 598         (t
 599          (kill-local-variable 'local-write-file-hooks))))
 600
 601
 602 ;; Revert the buffer and recompute the dired-like listing.
 603 (defun tar-mode-revert (&optional no-autosave no-confirm)
 604   (setq tar-header-offset nil)
 605   (let ((revert-buffer-function nil))
 606     (revert-buffer t no-confirm)
 607     (widen))
 608   (tar-mode))
 609
 610
 611 (defun tar-next-line (p)
 612   (interactive "p")
 613   (forward-line p)
 614   (if (eobp) nil (forward-char 36)))
 615
 616 (defun tar-previous-line (p)
 617   (interactive "p")
 618   (tar-next-line (- p)))
 619
 620 (defun tar-current-descriptor (&optional noerror)
 621   "Return the tar-descriptor of the current line, or signals an error."
 622   ;; I wish lines had plists, like in ZMACS...
 623   (or (nth (count-lines (point-min)
 624                         (save-excursion (beginning-of-line) (point)))
 625            tar-parse-info)
 626       (if noerror
 627           nil
 628           (error "This line does not describe a tar-file entry"))))
 629
 630 (defun tar-get-descriptor ()
 631   (let* ((descriptor (tar-current-descriptor))
 632          (tokens (tar-desc-tokens descriptor))
 633          (size (tar-header-size tokens))
 634          (link-p (tar-header-link-type tokens)))
 635     (if link-p
 636         (error "This is a %s, not a real file"
 637                (cond ((eq link-p 5) "directory")
 638                      ((eq link-p 20) "tar directory header")
 639                      ((eq link-p 29) "multivolume-continuation")
 640                      ((eq link-p 35) "sparse entry")
 641                      ((eq link-p 38) "volume header")
 642                      (t "link"))))
 643     (if (zerop size) (error "This is a zero-length file"))
 644     descriptor))
 645
 646 (defun tar-mouse-extract (event)
 647   "Extract a file whose tar directory line you click on."
 648   (interactive "e")
 649   (save-excursion
 650     (set-buffer (window-buffer (posn-window (event-end event))))
 651     (save-excursion
 652       (goto-char (posn-point (event-end event)))
 653       ;; Just make sure this doesn't get an error.
 654       (tar-get-descriptor)))
 655   (select-window (posn-window (event-end event)))
 656   (goto-char (posn-point (event-end event)))
 657   (tar-extract))
 658
 659 (defun tar-extract (&optional other-window-p)
 660   "In Tar mode, extract this entry of the tar file into its own buffer."
 661   (interactive)
 662   (let* ((view-p (eq other-window-p 'view))
 663          (descriptor (tar-get-descriptor))
 664          (tokens (tar-desc-tokens descriptor))
 665          (name (tar-header-name tokens))
 666          (size (tar-header-size tokens))
 667          (start (+ (tar-desc-data-start descriptor) tar-header-offset -1))
 668          (end (+ start size)))
 669     (let* ((tar-buffer (current-buffer))
 670            (tarname (file-name-nondirectory (buffer-file-name)))
 671            (bufname (concat (file-name-nondirectory name)
 672                             " ("
 673                             tarname
 674                             ")"))
 675            (read-only-p (or buffer-read-only view-p))
 676            (buffer (get-buffer bufname))
 677            (just-created nil))
 678       (if buffer
 679           nil
 680         (setq buffer (get-buffer-create bufname))
 681         (setq just-created t)
 682         (unwind-protect
 683             (progn
 684               (widen)
 685               (save-excursion
 686                 (set-buffer buffer)
 687                 (insert-buffer-substring tar-buffer start end)
 688                 (goto-char 0)
 689                 (setq buffer-file-name
 690                       (expand-file-name (concat tarname ":" name)))
 691                 (setq buffer-file-truename
 692                       (abbreviate-file-name buffer-file-name))
 693                 ;; Set the default-directory to the dir of the
 694                 ;; superior buffer.
 695                 (setq default-directory
 696                       (save-excursion
 697                         (set-buffer tar-buffer)
 698                         default-directory))
 699                 (normal-mode)  ; pick a mode.
 700                 (rename-buffer bufname)
 701                 (make-local-variable 'tar-superior-buffer)
 702                 (make-local-variable 'tar-superior-descriptor)
 703                 (setq tar-superior-buffer tar-buffer)
 704                 (setq tar-superior-descriptor descriptor)
 705                 (tar-subfile-mode 1)
 706                 (setq buffer-read-only read-only-p)
 707                 (set-buffer-modified-p nil))
 708               (set-buffer tar-buffer))
 709           (narrow-to-region 1 tar-header-offset)))
 710       (if view-p
 711           (progn
 712             (view-buffer buffer)
 713             (and just-created
 714                  (setq view-exit-action 'kill-buffer)))
 715         (if (eq other-window-p 'display)
 716             (display-buffer buffer)
 717           (if other-window-p
 718               (switch-to-buffer-other-window buffer)
 719             (switch-to-buffer buffer)))))))
 720
 721
 722 (defun tar-extract-other-window ()
 723   "*In Tar mode, find this entry of the tar file in another window."
 724   (interactive)
 725   (tar-extract t))
 726
 727 (defun tar-display-other-window ()
 728   "*In Tar mode, display this entry of the tar file in another window."
 729   (interactive)
 730   (tar-extract 'display))
 731
 732 (defun tar-view ()
 733   "*In Tar mode, view the tar file entry on this line."
 734   (interactive)
 735   (tar-extract 'view))
 736
 737
 738 (defun tar-read-file-name (&optional prompt)
 739   "Read a file name with this line's entry as the default."
 740   (or prompt (setq prompt "Copy to: "))
 741   (let* ((default-file (expand-file-name
 742                         (tar-header-name (tar-desc-tokens
 743                                           (tar-current-descriptor)))))
 744          (target (expand-file-name
 745                   (read-file-name prompt
 746                                   (file-name-directory default-file)
 747                                   default-file nil))))
 748     (if (or (string= "" (file-name-nondirectory target))
 749             (file-directory-p target))
 750         (setq target (concat (if (string-match "/$" target)
 751                                  (substring target 0 (1- (match-end 0)))
 752                                  target)
 753                              "/"
 754                              (file-name-nondirectory default-file))))
 755     target))
 756
 757
 758 (defun tar-copy (&optional to-file)
 759   "*In Tar mode, extract this entry of the tar file into a file on disk.
 760 If TO-FILE is not supplied, it is prompted for, defaulting to the name of
 761 the current tar-entry."
 762   (interactive (list (tar-read-file-name)))
 763   (let* ((descriptor (tar-get-descriptor))
 764          (tokens (tar-desc-tokens descriptor))
 765          (name (tar-header-name tokens))
 766          (size (tar-header-size tokens))
 767          (start (+ (tar-desc-data-start descriptor) tar-header-offset -1))
 768          (end (+ start size)))
 769     (save-restriction
 770       (widen)
 771       (write-region start end to-file))
 772     (message "Copied tar entry %s to %s" name to-file)))
 773
 774 (defun tar-flag-deleted (p &optional unflag)
 775   "*In Tar mode, mark this sub-file to be deleted from the tar file.
 776 With a prefix argument, mark that many files."
 777   (interactive "p")
 778   (beginning-of-line)
 779   (tar-dotimes (i (if (< p 0) (- p) p))
 780     (if (tar-current-descriptor unflag) ; barf if we're not on an entry-line.
 781         (progn
 782           (delete-char 1)
 783           (insert (if unflag " " "D"))))
 784     (forward-line (if (< p 0) -1 1)))
 785   (if (eobp) nil (forward-char 36)))
 786
 787 (defun tar-unflag (p)
 788   "*In Tar mode, un-mark this sub-file if it is marked to be deleted.
 789 With a prefix argument, un-mark that many files forward."
 790   (interactive "p")
 791   (tar-flag-deleted p t))
 792
 793 (defun tar-unflag-backwards (p)
 794   "*In Tar mode, un-mark this sub-file if it is marked to be deleted.
 795 With a prefix argument, un-mark that many files backward."
 796   (interactive "p")
 797   (tar-flag-deleted (- p) t))
 798
 799
 800 (defun tar-expunge-internal ()
 801   "Expunge the tar-entry specified by the current line."
 802   (let* ((descriptor (tar-current-descriptor))
 803          (tokens (tar-desc-tokens descriptor))
 804          (line (tar-desc-data-start descriptor))
 805          (name (tar-header-name tokens))
 806          (size (tar-header-size tokens))
 807          (link-p (tar-header-link-type tokens))
 808          (start (tar-desc-data-start descriptor))
 809          (following-descs (cdr (memq descriptor tar-parse-info))))
 810     (if link-p (setq size 0)) ; size lies for hard-links.
 811     ;;
 812     ;; delete the current line...
 813     (beginning-of-line)
 814     (let ((line-start (point)))
 815       (end-of-line) (forward-char)
 816       (let ((line-len (- (point) line-start)))
 817         (delete-region line-start (point))
 818         ;;
 819         ;; decrement the header-pointer to be in synch...
 820         (setq tar-header-offset (- tar-header-offset line-len))))
 821     ;;
 822     ;; delete the data pointer...
 823     (setq tar-parse-info (delq descriptor tar-parse-info))
 824     ;;
 825     ;; delete the data from inside the file...
 826     (widen)
 827     (let* ((data-start (+ start tar-header-offset -513))
 828            (data-end (+ data-start 512 (ash (ash (+ size 511) -9) 9))))
 829       (delete-region data-start data-end)
 830       ;;
 831       ;; and finally, decrement the start-pointers of all following
 832       ;; entries in the archive.  This is a pig when deleting a bunch
 833       ;; of files at once - we could optimize this to only do the
 834       ;; iteration over the files that remain, or only iterate up to
 835       ;; the next file to be deleted.
 836       (let ((data-length (- data-end data-start)))
 837         (tar-dolist (desc following-descs)
 838           (tar-setf (tar-desc-data-start desc)
 839                     (- (tar-desc-data-start desc) data-length))))
 840       ))
 841   (narrow-to-region 1 tar-header-offset))
 842
 843
 844 (defun tar-expunge (&optional noconfirm)
 845   "*In Tar mode, delete all the archived files flagged for deletion.
 846 This does not modify the disk image; you must save the tar file itself
 847 for this to be permanent."
 848   (interactive)
 849   (if (or noconfirm
 850           (y-or-n-p "expunge files marked for deletion? "))
 851       (let ((n 0))
 852         (save-excursion
 853           (goto-char 0)
 854           (while (not (eobp))
 855             (if (looking-at "D")
 856                 (progn (tar-expunge-internal)
 857                        (setq n (1+ n)))
 858                 (forward-line 1)))
 859           ;; after doing the deletions, add any padding that may be necessary.
 860           (tar-pad-to-blocksize)
 861           (narrow-to-region 1 tar-header-offset)
 862           )
 863         (if (zerop n)
 864             (message "nothing to expunge.")
 865             (message "%s expunged.  Be sure to save this buffer." n)))))
 866
 867
 868 (defun tar-clear-modification-flags ()
 869   "Remove the stars at the beginning of each line."
 870   (save-excursion
 871     (goto-char 0)
 872     (while (< (point) tar-header-offset)
 873       (if (looking-at "*")
 874           (progn (delete-char 1) (insert " ")))
 875       (forward-line 1))))
 876
 877
 878 (defun tar-chown-entry (new-uid)
 879   "*Change the user-id associated with this entry in the tar file.
 880 If this tar file was written by GNU tar, then you will be able to edit
 881 the user id as a string; otherwise, you must edit it as a number.
 882 You can force editing as a number by calling this with a prefix arg.
 883 This does not modify the disk image; you must save the tar file itself
 884 for this to be permanent."
 885   (interactive (list
 886                  (let ((tokens (tar-desc-tokens (tar-current-descriptor))))
 887                    (if (or current-prefix-arg
 888                            (not (tar-header-magic tokens)))
 889                        (let (n)
 890                          (while (not (numberp (setq n (read-minibuffer
 891                                                         "New UID number: "
 892                                                         (format "%s" (tar-header-uid tokens)))))))
 893                          n)
 894                        (read-string "New UID string: " (tar-header-uname tokens))))))
 895   (cond ((stringp new-uid)
 896          (tar-setf (tar-header-uname (tar-desc-tokens (tar-current-descriptor)))
 897                    new-uid)
 898          (tar-alter-one-field tar-uname-offset (concat new-uid "\000")))
 899         (t
 900          (tar-setf (tar-header-uid (tar-desc-tokens (tar-current-descriptor)))
 901                    new-uid)
 902          (tar-alter-one-field tar-uid-offset
 903            (concat (substring (format "%6o" new-uid) 0 6) "\000 ")))))
 904
 905
 906 (defun tar-chgrp-entry (new-gid)
 907   "*Change the group-id associated with this entry in the tar file.
 908 If this tar file was written by GNU tar, then you will be able to edit
 909 the group id as a string; otherwise, you must edit it as a number.
 910 You can force editing as a number by calling this with a prefix arg.
 911 This does not modify the disk image; you must save the tar file itself
 912 for this to be permanent."
 913   (interactive (list
 914                  (let ((tokens (tar-desc-tokens (tar-current-descriptor))))
 915                    (if (or current-prefix-arg
 916                            (not (tar-header-magic tokens)))
 917                        (let (n)
 918                          (while (not (numberp (setq n (read-minibuffer
 919                                                         "New GID number: "
 920                                                         (format "%s" (tar-header-gid tokens)))))))
 921                          n)
 922                        (read-string "New GID string: " (tar-header-gname tokens))))))
 923   (cond ((stringp new-gid)
 924          (tar-setf (tar-header-gname (tar-desc-tokens (tar-current-descriptor)))
 925                    new-gid)
 926          (tar-alter-one-field tar-gname-offset
 927            (concat new-gid "\000")))
 928         (t
 929          (tar-setf (tar-header-gid (tar-desc-tokens (tar-current-descriptor)))
 930                    new-gid)
 931          (tar-alter-one-field tar-gid-offset
 932            (concat (substring (format "%6o" new-gid) 0 6) "\000 ")))))
 933
 934 (defun tar-rename-entry (new-name)
 935   "*Change the name associated with this entry in the tar file.
 936 This does not modify the disk image; you must save the tar file itself
 937 for this to be permanent."
 938   (interactive
 939     (list (read-string "New name: "
 940             (tar-header-name (tar-desc-tokens (tar-current-descriptor))))))
 941   (if (string= "" new-name) (error "zero length name"))
 942   (if (> (length new-name) 98) (error "name too long"))
 943   (tar-setf (tar-header-name (tar-desc-tokens (tar-current-descriptor)))
 944             new-name)
 945   (tar-alter-one-field 0
 946     (substring (concat new-name (make-string 99 0)) 0 99)))
 947
 948
 949 (defun tar-chmod-entry (new-mode)
 950   "*Change the protection bits associated with this entry in the tar file.
 951 This does not modify the disk image; you must save the tar file itself
 952 for this to be permanent."
 953   (interactive (list (tar-parse-octal-integer-safe
 954                        (read-string "New protection (octal): "))))
 955   (tar-setf (tar-header-mode (tar-desc-tokens (tar-current-descriptor)))
 956             new-mode)
 957   (tar-alter-one-field tar-mode-offset
 958     (concat (substring (format "%6o" new-mode) 0 6) "\000 ")))
 959
 960
 961 (defun tar-alter-one-field (data-position new-data-string)
 962   (let* ((descriptor (tar-current-descriptor))
 963          (tokens (tar-desc-tokens descriptor)))
 964     (unwind-protect
 965         (save-excursion
 966           ;;
 967           ;; update the header-line.
 968           (beginning-of-line)
 969           (let ((p (point)))
 970             (forward-line 1)
 971             (delete-region p (point))
 972             (insert (tar-header-block-summarize tokens) "\n")
 973             (setq tar-header-offset (point-max)))
 974
 975           (widen)
 976           (let* ((start (+ (tar-desc-data-start descriptor) tar-header-offset -513)))
 977             ;;
 978             ;; delete the old field and insert a new one.
 979             (goto-char (+ start data-position))
 980             (delete-region (point) (+ (point) (length new-data-string))) ; <--
 981             (insert new-data-string) ; <--
 982             ;;
 983             ;; compute a new checksum and insert it.
 984             (let ((chk (tar-header-block-checksum
 985                         (buffer-substring start (+ start 512)))))
 986               (goto-char (+ start tar-chk-offset))
 987               (delete-region (point) (+ (point) 8))
 988               (insert (format "%6o" chk))
 989               (insert 0)
 990               (insert ? )
 991               (tar-setf (tar-header-checksum tokens) chk)
 992               ;;
 993               ;; ok, make sure we didn't botch it.
 994               (tar-header-block-check-checksum
 995                 (buffer-substring start (+ start 512))
 996                 chk (tar-header-name tokens))
 997               )))
 998       (narrow-to-region 1 tar-header-offset))))
 999
1000
1001 (defun tar-octal-time (timeval)
1002   ;; Format a timestamp as 11 octal digits.  Ghod, I hope this works...
1003   (let ((hibits (car timeval)) (lobits (car (cdr timeval))))
1004     (insert (format "%05o%01o%05o"
1005                     (lsh hibits -2)
1006                     (logior (lsh (logand 3 hibits) 1) (> (logand lobits 32768) 0))
1007                     (logand 32767 lobits)
1008                     ))))
1009
1010 (defun tar-subfile-save-buffer ()
1011   "In tar subfile mode, save this buffer into its parent tar-file buffer.
1012 This doesn't write anything to disk; you must save the parent tar-file buffer
1013 to make your changes permanent."
1014   (interactive)
1015   (if (not (and (boundp 'tar-superior-buffer) tar-superior-buffer))
1016     (error "This buffer has no superior tar file buffer"))
1017   (if (not (and (boundp 'tar-superior-descriptor) tar-superior-descriptor))
1018     (error "This buffer doesn't have an index into its superior tar file!"))
1019   (save-excursion
1020   (let ((subfile (current-buffer))
1021         (subfile-size (buffer-size))
1022         (descriptor tar-superior-descriptor))
1023     (set-buffer tar-superior-buffer)
1024     (let* ((tokens (tar-desc-tokens descriptor))
1025            (start (tar-desc-data-start descriptor))
1026            (name (tar-header-name tokens))
1027            (size (tar-header-size tokens))
1028            (size-pad (ash (ash (+ size 511) -9) 9))
1029            (head (memq descriptor tar-parse-info))
1030            (following-descs (cdr head)))
1031       (if (not head)
1032         (error "Can't find this tar file entry in its parent tar file!"))
1033       (unwind-protect
1034        (save-excursion
1035         (widen)
1036         ;; delete the old data...
1037         (let* ((data-start (+ start tar-header-offset -1))
1038                (data-end (+ data-start (ash (ash (+ size 511) -9) 9))))
1039           (delete-region data-start data-end)
1040           ;; insert the new data...
1041           (goto-char data-start)
1042           (insert-buffer subfile)
1043           ;;
1044           ;; pad the new data out to a multiple of 512...
1045           (let ((subfile-size-pad (ash (ash (+ subfile-size 511) -9) 9)))
1046             (goto-char (+ data-start subfile-size))
1047             (insert (make-string (- subfile-size-pad subfile-size) 0))
1048             ;;
1049             ;; update the data pointer of this and all following files...
1050             (tar-setf (tar-header-size tokens) subfile-size)
1051             (let ((difference (- subfile-size-pad size-pad)))
1052               (tar-dolist (desc following-descs)
1053                 (tar-setf (tar-desc-data-start desc)
1054                           (+ (tar-desc-data-start desc) difference))))
1055             ;;
1056             ;; Update the size field in the header block.
1057             (let ((header-start (- data-start 512)))
1058               (goto-char (+ header-start tar-size-offset))
1059               (delete-region (point) (+ (point) 12))
1060               (insert (format "%11o" subfile-size))
1061               (insert ? )
1062               ;;
1063               ;; Maybe update the datestamp.
1064               (if (not tar-update-datestamp)
1065                   nil
1066                 (goto-char (+ header-start tar-time-offset))
1067                 (delete-region (point) (+ (point) 12))
1068                 (insert (tar-octal-time (current-time)))
1069                 (insert ? ))
1070               ;;
1071               ;; compute a new checksum and insert it.
1072               (let ((chk (tar-header-block-checksum
1073                           (buffer-substring header-start data-start))))
1074                 (goto-char (+ header-start tar-chk-offset))
1075                 (delete-region (point) (+ (point) 8))
1076                 (insert (format "%6o" chk))
1077                 (insert 0)
1078                 (insert ? )
1079                 (tar-setf (tar-header-checksum tokens) chk)))
1080             ;;
1081             ;; alter the descriptor-line...
1082             ;;
1083             (let ((position (- (length tar-parse-info) (length head))))
1084               (goto-char 1)
1085               (next-line position)
1086               (beginning-of-line)
1087               (let ((p (point))
1088                     after
1089                     (m (set-marker (make-marker) tar-header-offset)))
1090                 (forward-line 1)
1091                 (setq after (point))
1092                 ;; Insert the new text after the old, before deleting,
1093                 ;; to preserve the window start.
1094                 (insert-before-markers (tar-header-block-summarize tokens t) "\n")
1095                 (delete-region p after)
1096                 (setq tar-header-offset (marker-position m)))
1097               )))
1098         ;; after doing the insertion, add any final padding that may be necessary.
1099         (tar-pad-to-blocksize))
1100        (narrow-to-region 1 tar-header-offset)))
1101     (set-buffer-modified-p t)   ; mark the tar file as modified
1102     (set-buffer subfile)
1103     (set-buffer-modified-p nil) ; mark the tar subfile as unmodified
1104     (message "saved into tar-buffer `%s' -- remember to save that buffer!"
1105              (buffer-name tar-superior-buffer))
1106     ;; Prevent ordinary saving from happening.
1107     t)))
1108
1109
1110 (defun tar-pad-to-blocksize ()
1111   "If we are being anal about tar file blocksizes, fix up the current buffer.
1112 Leaves the region wide."
1113   (if (null tar-anal-blocksize)
1114       nil
1115     (widen)
1116     (let* ((last-desc (nth (1- (length tar-parse-info)) tar-parse-info))
1117            (start (tar-desc-data-start last-desc))
1118            (tokens (tar-desc-tokens last-desc))
1119            (link-p (tar-header-link-type tokens))
1120            (size (if link-p 0 (tar-header-size tokens)))
1121            (data-end (+ start size))
1122            (bbytes (ash tar-anal-blocksize 9))
1123            (pad-to (+ bbytes (* bbytes (/ (1- data-end) bbytes))))
1124            (inhibit-read-only t) ; ##
1125            )
1126       ;; If the padding after the last data is too long, delete some;
1127       ;; else insert some until we are padded out to the right number of blocks.
1128       ;;
1129       (goto-char (+ (or tar-header-offset 0) data-end))
1130       (if (> (1+ (buffer-size)) (+ (or tar-header-offset 0) pad-to))
1131           (delete-region (+ (or tar-header-offset 0) pad-to) (1+ (buffer-size)))
1132           (insert (make-string (- (+ (or tar-header-offset 0) pad-to)
1133                                   (1+ (buffer-size)))
1134                                0)))
1135       )))
1136
1137
1138 ;; Used in write-file-hook to write tar-files out correctly.
1139 (defun tar-mode-maybe-write-tar-file ()
1140   ;;
1141   ;; If the current buffer is in Tar mode and has its header-offset set,
1142   ;; only write out the part of the file after the header-offset.
1143   ;;
1144   (if (and (eq major-mode 'tar-mode)
1145            (and (boundp 'tar-header-offset) tar-header-offset))
1146       (unwind-protect
1147         (save-excursion
1148           (tar-clear-modification-flags)
1149           (widen)
1150           ;; Doing this here confuses things - the region gets left too wide!
1151           ;; I suppose this is run in a context where changing the buffer is bad.
1152           ;; (tar-pad-to-blocksize)
1153           (write-region tar-header-offset (1+ (buffer-size)) buffer-file-name nil t)
1154           ;; return T because we've written the file.
1155           t)
1156         (narrow-to-region 1 tar-header-offset)
1157         t)
1158       ;; return NIL because we haven't.
1159       nil))
1160
1161 \f
1162 ;;; Patch it in.
1163
1164 (or (memq 'tar-mode-maybe-write-tar-file write-file-hooks)
1165     (setq write-file-hooks
1166           (cons 'tar-mode-maybe-write-tar-file write-file-hooks)))
1167
1168 (provide 'tar-mode)
1169
1170 ;;; tar-mode.el ends here