lisp/tar-mode.el

   1 ;;; tar-mode.el --- simple editing of tar files from GNU emacs
   2
   3 ;; Copyright (C) 1990, 1991, 1993, 1994, 1995 Free Software Foundation, Inc.
   4
   5 ;; Author: Jamie Zawinski <jwz@lucid.com>
   6 ;; Created: 04 Apr 1990
   7 ;; Keywords: unix
   8
   9 ;; This file is part of GNU Emacs.
  10
  11 ;; GNU Emacs is free software; you can redistribute it and/or modify
  12 ;; it under the terms of the GNU General Public License as published by
  13 ;; the Free Software Foundation; either version 2, or (at your option)
  14 ;; any later version.
  15
  16 ;; GNU Emacs is distributed in the hope that it will be useful,
  17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 ;; GNU General Public License for more details.
  20
  21 ;; You should have received a copy of the GNU General Public License
  22 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  23 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  24 ;; Boston, MA 02111-1307, 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  The code is less efficient that it could be - in a lot of places, I
  58 ;;    pull a 512-character string out of the buffer and parse it, when I could
  59 ;;    be parsing it in place, not garbaging a string.  Should redo that.
  60 ;;
  61 ;; o  I'd like a command that searches for a string/regexp in every subfile
  62 ;;    of an archive, where <esc> would leave you in a subfile-edit buffer.
  63 ;;    (Like the Meta-R command of the Zmacs mail reader.)
  64 ;;
  65 ;; o  Sometimes (but not always) reverting the tar-file buffer does not
  66 ;;    re-grind the listing, and you are staring at the binary tar data.
  67 ;;    Typing 'g' again immediately after that will always revert and re-grind
  68 ;;    it, though.  I have no idea why this happens.
  69 ;;
  70 ;; o  Tar-mode interacts poorly with crypt.el and zcat.el because the tar
  71 ;;    write-file-hook actually writes the file.  Instead it should remove the
  72 ;;    header (and conspire to put it back afterwards) so that other write-file
  73 ;;    hooks which frob the buffer have a chance to do their dirty work.  There
  74 ;;    might be a problem if the tar write-file-hook does not come *first* on
  75 ;;    the list.
  76 ;;
  77 ;; o  Block files, sparse files, continuation files, and the various header
  78 ;;    types aren't editable.  Actually I don't know that they work at all.
  79
  80 ;; Rationale:
  81
  82 ;; Why does tar-mode edit the file itself instead of using tar?
  83
  84 ;; That means that you can edit tar files which you don't have room for
  85 ;; on your local disk.
  86
  87 ;; I don't know about recent features in gnu tar, but old versions of tar
  88 ;; can't replace a file in the middle of a tar file with a new version.
  89 ;; Tar-mode can.  I don't think tar can do things like chmod the subfiles.
  90 ;; An implementation which involved unpacking and repacking the file into
  91 ;; some scratch directory would be very wasteful, and wouldn't be able to
  92 ;; preserve the file owners.
  93
  94 ;;; Code:
  95
  96 (defvar tar-anal-blocksize 20
  97   "*The blocksize of tar files written by Emacs, or nil, meaning don't care.
  98 The blocksize of a tar file is not really the size of the blocks; rather, it is
  99 the number of blocks written with one system call.  When tarring to a tape,
 100 this is the size of the *tape* blocks, but when writing to a file, it doesn't
 101 matter much.  The only noticeable difference is that if a tar file does not
 102 have a blocksize of 20, tar will tell you that; all this really controls is
 103 how many null padding bytes go on the end of the tar file.")
 104
 105 (defvar tar-update-datestamp nil
 106   "*Non-nil means tar-mode should play fast and loose with sub-file datestamps.
 107 If this is true, then editing and saving a tar file entry back into its
 108 tar file will update its datestamp.  If false, the datestamp is unchanged.
 109 You may or may not want this - it is good in that you can tell when a file
 110 in a tar archive has been changed, but it is bad for the same reason that
 111 editing a file in the tar archive at all is bad - the changed version of
 112 the file never exists on disk.")
 113
 114 (defvar tar-mode-show-date nil
 115   "*Non-nil means Tar mode should show the date/time of each subfile.
 116 This information is useful, but it takes screen space away from file names.")
 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-long-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) ?0)))
 273               start (1+ start)))
 274       n)))
 275
 276 (defun tar-parse-octal-long-integer (string &optional start end)
 277   (if (null start) (setq start 0))
 278   (if (null end) (setq end (length string)))
 279   (if (= (aref string start) 0)
 280       (list 0 0)
 281     (let ((lo 0)
 282           (hi 0))
 283       (while (< start end)
 284         (if (>= (aref string start) ?0)
 285             (setq lo (+ (* lo 8) (- (aref string start) ?0))
 286                   hi (+ (* hi 8) (ash lo -16))
 287                   lo (logand lo 65535)))
 288         (setq start (1+ start)))
 289       (list hi lo))))
 290
 291 (defun tar-parse-octal-integer-safe (string)
 292   (let ((L (length string)))
 293     (if (= L 0) (error "empty string"))
 294     (tar-dotimes (i L)
 295        (if (or (< (aref string i) ?0)
 296                (> (aref string i) ?7))
 297            (error "'%c' is not an octal digit"))))
 298   (tar-parse-octal-integer string))
 299
 300
 301 (defun tar-header-block-checksum (string)
 302   "Compute and return a tar-acceptable checksum for this block."
 303   (let* ((chk-field-start tar-chk-offset)
 304          (chk-field-end (+ chk-field-start 8))
 305          (sum 0)
 306          (i 0))
 307     ;; Add up all of the characters except the ones in the checksum field.
 308     ;; Add that field as if it were filled with spaces.
 309     (while (< i chk-field-start)
 310       (setq sum (+ sum (aref string i))
 311             i (1+ i)))
 312     (setq i chk-field-end)
 313     (while (< i 512)
 314       (setq sum (+ sum (aref string i))
 315             i (1+ i)))
 316     (+ sum (* 32 8))))
 317
 318 (defun tar-header-block-check-checksum (hblock desired-checksum file-name)
 319   "Beep and print a warning if the checksum doesn't match."
 320   (if (not (= desired-checksum (tar-header-block-checksum hblock)))
 321       (progn (beep) (message "Invalid checksum for file %s!" file-name))))
 322
 323 (defun tar-header-block-recompute-checksum (hblock)
 324   "Modifies the given string to have a valid checksum field."
 325   (let* ((chk (tar-header-block-checksum hblock))
 326          (chk-string (format "%6o" chk))
 327          (l (length chk-string)))
 328     (aset hblock 154 0)
 329     (aset hblock 155 32)
 330     (tar-dotimes (i l) (aset hblock (- 153 i) (aref chk-string (- l i 1)))))
 331   hblock)
 332
 333 (defun tar-clip-time-string (time)
 334   (let ((str (current-time-string time)))
 335     (concat (substring str 4 16) (substring str 19 24))))
 336
 337 (defun tar-grind-file-mode (mode string start)
 338   "Store `-rw--r--r--' indicating MODE into STRING beginning at START.
 339 MODE should be an integer which is a file mode value."
 340   (aset string start       (if (zerop (logand 256 mode)) ?- ?r))
 341   (aset string (+ start 1) (if (zerop (logand 128 mode)) ?- ?w))
 342   (aset string (+ start 2) (if (zerop (logand  64 mode)) ?- ?x))
 343   (aset string (+ start 3) (if (zerop (logand  32 mode)) ?- ?r))
 344   (aset string (+ start 4) (if (zerop (logand  16 mode)) ?- ?w))
 345   (aset string (+ start 5) (if (zerop (logand   8 mode)) ?- ?x))
 346   (aset string (+ start 6) (if (zerop (logand   4 mode)) ?- ?r))
 347   (aset string (+ start 7) (if (zerop (logand   2 mode)) ?- ?w))
 348   (aset string (+ start 8) (if (zerop (logand   1 mode)) ?- ?x))
 349   (if (zerop (logand 1024 mode)) nil (aset string (+ start 2) ?s))
 350   (if (zerop (logand 2048 mode)) nil (aset string (+ start 5) ?s))
 351   string)
 352
 353 (defun tar-header-block-summarize (tar-hblock &optional mod-p)
 354   "Returns a line similar to the output of `tar -vtf'."
 355   (let ((name (tar-header-name tar-hblock))
 356         (mode (tar-header-mode tar-hblock))
 357         (uid (tar-header-uid tar-hblock))
 358         (gid (tar-header-gid tar-hblock))
 359         (uname (tar-header-uname tar-hblock))
 360         (gname (tar-header-gname tar-hblock))
 361         (size (tar-header-size tar-hblock))
 362         (time (tar-header-date tar-hblock))
 363         (ck (tar-header-checksum tar-hblock))
 364         (link-p (tar-header-link-type tar-hblock))
 365         (link-name (tar-header-link-name tar-hblock))
 366         )
 367     (let* ((left 11)
 368            (namew 8)
 369            (groupw 8)
 370            (sizew 8)
 371            (datew (if tar-mode-show-date 18 0))
 372            (slash (1- (+ left namew)))
 373            (lastdigit (+ slash groupw sizew))
 374            (datestart (+ lastdigit 2))
 375            (namestart (+ datestart datew))
 376            (string (make-string (+ namestart (length name) (if link-p (+ 5 (length link-name)) 0)) 32))
 377            (type (tar-header-link-type tar-hblock)))
 378       (aset string 0 (if mod-p ?* ? ))
 379       (aset string 1
 380             (cond ((or (eq type nil) (eq type 0)) ?-)
 381                   ((eq type 1) ?l)  ; link
 382                   ((eq type 2) ?s)  ; symlink
 383                   ((eq type 3) ?c)  ; char special
 384                   ((eq type 4) ?b)  ; block special
 385                   ((eq type 5) ?d)  ; directory
 386                   ((eq type 6) ?p)  ; FIFO/pipe
 387                   ((eq type 20) ?*) ; directory listing
 388                   ((eq type 29) ?M) ; multivolume continuation
 389                   ((eq type 35) ?S) ; sparse
 390                   ((eq type 38) ?V) ; volume header
 391                   ))
 392       (tar-grind-file-mode mode string 2)
 393       (setq uid (if (= 0 (length uname)) (int-to-string uid) uname))
 394       (setq gid (if (= 0 (length gname)) (int-to-string gid) gname))
 395       (setq size (int-to-string size))
 396       (setq time (tar-clip-time-string time))
 397       (tar-dotimes (i (min (1- namew) (length uid))) (aset string (- slash i) (aref uid (- (length uid) i 1))))
 398       (aset string (1+ slash) ?/)
 399       (tar-dotimes (i (min (1- groupw) (length gid))) (aset string (+ (+ slash 2) i) (aref gid i)))
 400       (tar-dotimes (i (min sizew (length size))) (aset string (- lastdigit i) (aref size (- (length size) i 1))))
 401       (if tar-mode-show-date
 402           (tar-dotimes (i (length time)) (aset string (+ datestart i) (aref time i))))
 403       (tar-dotimes (i (length name)) (aset string (+ namestart i) (aref name i)))
 404       (if (or (eq link-p 1) (eq link-p 2))
 405           (progn
 406             (tar-dotimes (i 3) (aset string (+ namestart 1 (length name) i) (aref (if (= link-p 1) "==>" "-->") i)))
 407             (tar-dotimes (i (length link-name)) (aset string (+ namestart 5 (length name) i) (aref link-name i)))))
 408       (put-text-property namestart (length string)
 409                          'mouse-face 'highlight string)
 410       string)))
 411
 412
 413 (defun tar-summarize-buffer ()
 414   "Parse the contents of the tar file in the current buffer.
 415 Place a dired-like listing on the front;
 416 then narrow to it, so that only that listing
 417 is visible (and the real data of the buffer is hidden)."
 418   (message "Parsing tar file...")
 419   (let* ((result '())
 420          (pos 1)
 421          (bs (max 1 (- (buffer-size) 1024))) ; always 2+ empty blocks at end.
 422          (bs100 (max 1 (/ bs 100)))
 423          tokens)
 424     (while (and (<= (+ pos 512) (point-max))
 425                 (not (eq 'empty-tar-block
 426                          (setq tokens
 427                                (tar-header-block-tokenize
 428                                 (buffer-substring pos (+ pos 512)))))))
 429       (setq pos (+ pos 512))
 430       (message "Parsing tar file...%d%%"
 431                ;(/ (* pos 100) bs)   ; this gets round-off lossage
 432                (/ pos bs100)         ; this doesn't
 433                )
 434       (if (eq (tar-header-link-type tokens) 20)
 435           ;; Foo.  There's an extra empty block after these.
 436           (setq pos (+ pos 512)))
 437       (let ((size (tar-header-size tokens)))
 438         (if (< size 0)
 439             (error "%s has size %s - corrupted"
 440                    (tar-header-name tokens) size))
 441         ;
 442         ; This is just too slow.  Don't really need it anyway....
 443         ;(tar-header-block-check-checksum
 444         ;  hblock (tar-header-block-checksum hblock)
 445         ;  (tar-header-name tokens))
 446
 447         (setq result (cons (make-tar-desc pos tokens) result))
 448
 449         (and (null (tar-header-link-type tokens))
 450              (> size 0)
 451              (setq pos
 452                    (+ pos 512 (ash (ash (1- size) -9) 9))        ; this works
 453                    ;(+ pos (+ size (- 512 (rem (1- size) 512)))) ; this doesn't
 454                    ))))
 455     (make-local-variable 'tar-parse-info)
 456     (setq tar-parse-info (nreverse result))
 457     ;; A tar file should end with a block or two of nulls,
 458     ;; but let's not get a fatal error if it doesn't.
 459     (if (eq tokens 'empty-tar-block)
 460         (message "Parsing tar file...done.")
 461       (message "Warning: premature EOF parsing tar file")))
 462   (save-excursion
 463     (goto-char (point-min))
 464     (let ((buffer-read-only nil))
 465       (tar-dolist (tar-desc tar-parse-info)
 466         (insert-string
 467           (tar-header-block-summarize (tar-desc-tokens tar-desc)))
 468         (insert-string "\n"))
 469       (make-local-variable 'tar-header-offset)
 470       (setq tar-header-offset (point))
 471       (narrow-to-region 1 tar-header-offset)
 472       (set-buffer-modified-p nil))))
 473 \f
 474 (defvar tar-mode-map nil "*Local keymap for Tar mode listings.")
 475
 476 (if tar-mode-map
 477     nil
 478   (setq tar-mode-map (make-keymap))
 479   (suppress-keymap tar-mode-map)
 480   (define-key tar-mode-map " " 'tar-next-line)
 481   (define-key tar-mode-map "c" 'tar-copy)
 482   (define-key tar-mode-map "d" 'tar-flag-deleted)
 483   (define-key tar-mode-map "\^D" 'tar-flag-deleted)
 484   (define-key tar-mode-map "e" 'tar-extract)
 485   (define-key tar-mode-map "f" 'tar-extract)
 486   (define-key tar-mode-map "\C-m" 'tar-extract)
 487   (define-key tar-mode-map [mouse-2] 'tar-mouse-extract)
 488   (define-key tar-mode-map "g" 'revert-buffer)
 489   (define-key tar-mode-map "h" 'describe-mode)
 490   (define-key tar-mode-map "n" 'tar-next-line)
 491   (define-key tar-mode-map "\^N" 'tar-next-line)
 492   (define-key tar-mode-map "o" 'tar-extract-other-window)
 493   (define-key tar-mode-map "p" 'tar-previous-line)
 494   (define-key tar-mode-map "\^P" 'tar-previous-line)
 495   (define-key tar-mode-map "r" 'tar-rename-entry)
 496   (define-key tar-mode-map "u" 'tar-unflag)
 497   (define-key tar-mode-map "v" 'tar-view)
 498   (define-key tar-mode-map "x" 'tar-expunge)
 499   (define-key tar-mode-map "\177" 'tar-unflag-backwards)
 500   (define-key tar-mode-map "E" 'tar-extract-other-window)
 501   (define-key tar-mode-map "M" 'tar-chmod-entry)
 502   (define-key tar-mode-map "G" 'tar-chgrp-entry)
 503   (define-key tar-mode-map "O" 'tar-chown-entry)
 504   )
 505 \f
 506 ;; Make menu bar items.
 507
 508 ;; Get rid of the Edit menu bar item to save space.
 509 (define-key tar-mode-map [menu-bar edit] 'undefined)
 510
 511 (define-key tar-mode-map [menu-bar immediate]
 512   (cons "Immediate" (make-sparse-keymap "Immediate")))
 513
 514 (define-key tar-mode-map [menu-bar immediate view]
 515   '("View This File" . tar-view))
 516 (define-key tar-mode-map [menu-bar immediate display]
 517   '("Display in Other Window" . tar-display-other-file))
 518 (define-key tar-mode-map [menu-bar immediate find-file-other-window]
 519   '("Find in Other Window" . tar-extract-other-window))
 520 (define-key tar-mode-map [menu-bar immediate find-file]
 521   '("Find This File" . tar-extract))
 522
 523 (define-key tar-mode-map [menu-bar mark]
 524   (cons "Mark" (make-sparse-keymap "Mark")))
 525
 526 (define-key tar-mode-map [menu-bar mark unmark-all]
 527   '("Unmark All" . tar-clear-modification-flags))
 528 (define-key tar-mode-map [menu-bar mark deletion]
 529   '("Flag" . tar-flag-deleted))
 530 (define-key tar-mode-map [menu-bar mark unmark]
 531   '("Unflag" . tar-unflag))
 532
 533 (define-key tar-mode-map [menu-bar operate]
 534   (cons "Operate" (make-sparse-keymap "Operate")))
 535
 536 (define-key tar-mode-map [menu-bar operate chown]
 537   '("Change Owner..." . tar-chown-entry))
 538 (define-key tar-mode-map [menu-bar operate chgrp]
 539   '("Change Group..." . tar-chgrp-entry))
 540 (define-key tar-mode-map [menu-bar operate chmod]
 541   '("Change Mode..." . tar-chmod-entry))
 542 (define-key tar-mode-map [menu-bar operate rename]
 543   '("Rename to..." . tar-rename-entry))
 544 (define-key tar-mode-map [menu-bar operate copy]
 545   '("Copy to..." . tar-copy))
 546 (define-key tar-mode-map [menu-bar operate expunge]
 547   '("Expunge Marked Files" . tar-expunge))
 548 \f
 549 ;; tar mode is suitable only for specially formatted data.
 550 (put 'tar-mode 'mode-class 'special)
 551 (put 'tar-subfile-mode 'mode-class 'special)
 552
 553 ;;;###autoload
 554 (defun tar-mode ()
 555   "Major mode for viewing a tar file as a dired-like listing of its contents.
 556 You can move around using the usual cursor motion commands.
 557 Letters no longer insert themselves.
 558 Type `e' to pull a file out of the tar file and into its own buffer;
 559 or click mouse-2 on the file's line in the Tar mode buffer.
 560 Type `c' to copy an entry from the tar file into another file on disk.
 561
 562 If you edit a sub-file of this archive (as with the `e' command) and
 563 save it with Control-x Control-s, the contents of that buffer will be
 564 saved back into the tar-file buffer; in this way you can edit a file
 565 inside of a tar archive without extracting it and re-archiving it.
 566
 567 See also: variables `tar-update-datestamp' and `tar-anal-blocksize'.
 568 \\{tar-mode-map}"
 569   ;; this is not interactive because you shouldn't be turning this
 570   ;; mode on and off.  You can corrupt things that way.
 571   ;; rms: with permanent locals, it should now be possible to make this work
 572   ;; interactively in some reasonable fashion.
 573   (kill-all-local-variables)
 574   (make-local-variable 'tar-header-offset)
 575   (make-local-variable 'tar-parse-info)
 576   (make-local-variable 'require-final-newline)
 577   (setq require-final-newline nil) ; binary data, dude...
 578   (make-local-variable 'revert-buffer-function)
 579   (setq revert-buffer-function 'tar-mode-revert)
 580   (make-local-variable 'enable-local-variables)
 581   (setq enable-local-variables nil)
 582   (make-local-variable 'next-line-add-newlines)
 583   (setq next-line-add-newlines nil)
 584   (setq major-mode 'tar-mode)
 585   (setq mode-name "Tar")
 586   (use-local-map tar-mode-map)
 587   (auto-save-mode 0)
 588   (make-local-variable 'write-contents-hooks)
 589   (setq write-contents-hooks '(tar-mode-write-file))
 590   (widen)
 591   (if (and (boundp 'tar-header-offset) tar-header-offset)
 592       (narrow-to-region 1 tar-header-offset)
 593       (tar-summarize-buffer))
 594   (run-hooks 'tar-mode-hook)
 595   )
 596
 597
 598 (defun tar-subfile-mode (p)
 599   "Minor mode for editing an element of a tar-file.
 600 This mode redefines the save-buffer command to save the current buffer back
 601 into its associated tar-file buffer.  You must save that buffer to actually
 602 save your changes to disk."
 603   (interactive "P")
 604   (or (and (boundp 'tar-superior-buffer) tar-superior-buffer)
 605       (error "This buffer is not an element of a tar file"))
 606 ;;; Don't do this, because it is redundant and wastes mode line space.
 607 ;;;  (or (assq 'tar-subfile-mode minor-mode-alist)
 608 ;;;      (setq minor-mode-alist (append minor-mode-alist
 609 ;;;                                  (list '(tar-subfile-mode " TarFile")))))
 610   (make-local-variable 'tar-subfile-mode)
 611   (setq tar-subfile-mode
 612         (if (null p)
 613             (not tar-subfile-mode)
 614             (> (prefix-numeric-value p) 0)))
 615   (cond (tar-subfile-mode
 616          (make-local-variable 'local-write-file-hooks)
 617          (setq local-write-file-hooks '(tar-subfile-save-buffer))
 618          ;; turn off auto-save.
 619          (auto-save-mode nil)
 620          (setq buffer-auto-save-file-name nil)
 621          (run-hooks 'tar-subfile-mode-hook))
 622         (t
 623          (kill-local-variable 'local-write-file-hooks))))
 624
 625
 626 ;; Revert the buffer and recompute the dired-like listing.
 627 (defun tar-mode-revert (&optional no-autosave no-confirm)
 628   (setq tar-header-offset nil)
 629   (let ((revert-buffer-function nil))
 630     (revert-buffer t no-confirm)
 631     (widen))
 632   (tar-mode))
 633
 634
 635 (defun tar-next-line (p)
 636   (interactive "p")
 637   (forward-line p)
 638   (if (eobp) nil (forward-char (if tar-mode-show-date 54 36))))
 639
 640 (defun tar-previous-line (p)
 641   (interactive "p")
 642   (tar-next-line (- p)))
 643
 644 (defun tar-current-descriptor (&optional noerror)
 645   "Return the tar-descriptor of the current line, or signals an error."
 646   ;; I wish lines had plists, like in ZMACS...
 647   (or (nth (count-lines (point-min)
 648                         (save-excursion (beginning-of-line) (point)))
 649            tar-parse-info)
 650       (if noerror
 651           nil
 652           (error "This line does not describe a tar-file entry"))))
 653
 654 (defun tar-get-descriptor ()
 655   (let* ((descriptor (tar-current-descriptor))
 656          (tokens (tar-desc-tokens descriptor))
 657          (size (tar-header-size tokens))
 658          (link-p (tar-header-link-type tokens)))
 659     (if link-p
 660         (error "This is a %s, not a real file"
 661                (cond ((eq link-p 5) "directory")
 662                      ((eq link-p 20) "tar directory header")
 663                      ((eq link-p 29) "multivolume-continuation")
 664                      ((eq link-p 35) "sparse entry")
 665                      ((eq link-p 38) "volume header")
 666                      (t "link"))))
 667     (if (zerop size) (error "This is a zero-length file"))
 668     descriptor))
 669
 670 (defun tar-mouse-extract (event)
 671   "Extract a file whose tar directory line you click on."
 672   (interactive "e")
 673   (save-excursion
 674     (set-buffer (window-buffer (posn-window (event-end event))))
 675     (save-excursion
 676       (goto-char (posn-point (event-end event)))
 677       ;; Just make sure this doesn't get an error.
 678       (tar-get-descriptor)))
 679   (select-window (posn-window (event-end event)))
 680   (goto-char (posn-point (event-end event)))
 681   (tar-extract))
 682
 683 (defun tar-extract (&optional other-window-p)
 684   "In Tar mode, extract this entry of the tar file into its own buffer."
 685   (interactive)
 686   (let* ((view-p (eq other-window-p 'view))
 687          (descriptor (tar-get-descriptor))
 688          (tokens (tar-desc-tokens descriptor))
 689          (name (tar-header-name tokens))
 690          (size (tar-header-size tokens))
 691          (start (+ (tar-desc-data-start descriptor) tar-header-offset -1))
 692          (end (+ start size)))
 693     (let* ((tar-buffer (current-buffer))
 694            (tarname (file-name-nondirectory (buffer-file-name)))
 695            (bufname (concat (file-name-nondirectory name)
 696                             " ("
 697                             tarname
 698                             ")"))
 699            (read-only-p (or buffer-read-only view-p))
 700            (buffer (get-buffer bufname))
 701            (just-created nil))
 702       (if buffer
 703           nil
 704         (setq buffer (get-buffer-create bufname))
 705         (setq just-created t)
 706         (unwind-protect
 707             (progn
 708               (widen)
 709               (save-excursion
 710                 (set-buffer buffer)
 711                 (insert-buffer-substring tar-buffer start end)
 712                 (goto-char 0)
 713                 (setq buffer-file-name
 714                       (expand-file-name (concat tarname ":" name)))
 715                 (setq buffer-file-truename
 716                       (abbreviate-file-name buffer-file-name))
 717                 ;; Set the default-directory to the dir of the
 718                 ;; superior buffer.
 719                 (setq default-directory
 720                       (save-excursion
 721                         (set-buffer tar-buffer)
 722                         default-directory))
 723                 (normal-mode)  ; pick a mode.
 724                 (rename-buffer bufname)
 725                 (make-local-variable 'tar-superior-buffer)
 726                 (make-local-variable 'tar-superior-descriptor)
 727                 (setq tar-superior-buffer tar-buffer)
 728                 (setq tar-superior-descriptor descriptor)
 729                 (tar-subfile-mode 1)
 730                 (setq buffer-read-only read-only-p)
 731                 (set-buffer-modified-p nil))
 732               (set-buffer tar-buffer))
 733           (narrow-to-region 1 tar-header-offset)))
 734       (if view-p
 735           (progn
 736             (view-buffer buffer)
 737             (and just-created
 738                  ;; This will be created by view.el
 739                  (setq view-exit-action 'kill-buffer)))
 740         (if (eq other-window-p 'display)
 741             (display-buffer buffer)
 742           (if other-window-p
 743               (switch-to-buffer-other-window buffer)
 744             (switch-to-buffer buffer)))))))
 745
 746
 747 (defun tar-extract-other-window ()
 748   "*In Tar mode, find this entry of the tar file in another window."
 749   (interactive)
 750   (tar-extract t))
 751
 752 (defun tar-display-other-window ()
 753   "*In Tar mode, display this entry of the tar file in another window."
 754   (interactive)
 755   (tar-extract 'display))
 756
 757 (defun tar-view ()
 758   "*In Tar mode, view the tar file entry on this line."
 759   (interactive)
 760   (tar-extract 'view))
 761
 762
 763 (defun tar-read-file-name (&optional prompt)
 764   "Read a file name with this line's entry as the default."
 765   (or prompt (setq prompt "Copy to: "))
 766   (let* ((default-file (expand-file-name
 767                         (tar-header-name (tar-desc-tokens
 768                                           (tar-current-descriptor)))))
 769          (target (expand-file-name
 770                   (read-file-name prompt
 771                                   (file-name-directory default-file)
 772                                   default-file nil))))
 773     (if (or (string= "" (file-name-nondirectory target))
 774             (file-directory-p target))
 775         (setq target (concat (if (string-match "/$" target)
 776                                  (substring target 0 (1- (match-end 0)))
 777                                  target)
 778                              "/"
 779                              (file-name-nondirectory default-file))))
 780     target))
 781
 782
 783 (defun tar-copy (&optional to-file)
 784   "*In Tar mode, extract this entry of the tar file into a file on disk.
 785 If TO-FILE is not supplied, it is prompted for, defaulting to the name of
 786 the current tar-entry."
 787   (interactive (list (tar-read-file-name)))
 788   (let* ((descriptor (tar-get-descriptor))
 789          (tokens (tar-desc-tokens descriptor))
 790          (name (tar-header-name tokens))
 791          (size (tar-header-size tokens))
 792          (start (+ (tar-desc-data-start descriptor) tar-header-offset -1))
 793          (end (+ start size))
 794          (inhibit-file-name-handlers inhibit-file-name-handlers)
 795          (inhibit-file-name-operation inhibit-file-name-operation))
 796     (save-restriction
 797       (widen)
 798       ;; Inhibit compressing a subfile again if *both* name and
 799       ;; to-file are handled by jka-compr
 800       (if (and (eq (find-file-name-handler name 'write-region) 'jka-compr-handler)
 801                (eq (find-file-name-handler to-file 'write-region) 'jka-compr-handler))
 802           (setq inhibit-file-name-handlers
 803                 (cons 'jka-compr-handler
 804                       (and (eq inhibit-file-name-operation 'write-region)
 805                            inhibit-file-name-handlers))
 806                 inhibit-file-name-operation 'write-region))
 807       (write-region start end to-file))
 808     (message "Copied tar entry %s to %s" name to-file)))
 809
 810 (defun tar-flag-deleted (p &optional unflag)
 811   "*In Tar mode, mark this sub-file to be deleted from the tar file.
 812 With a prefix argument, mark that many files."
 813   (interactive "p")
 814   (beginning-of-line)
 815   (tar-dotimes (i (if (< p 0) (- p) p))
 816     (if (tar-current-descriptor unflag) ; barf if we're not on an entry-line.
 817         (progn
 818           (delete-char 1)
 819           (insert (if unflag " " "D"))))
 820     (forward-line (if (< p 0) -1 1)))
 821   (if (eobp) nil (forward-char 36)))
 822
 823 (defun tar-unflag (p)
 824   "*In Tar mode, un-mark this sub-file if it is marked to be deleted.
 825 With a prefix argument, un-mark that many files forward."
 826   (interactive "p")
 827   (tar-flag-deleted p t))
 828
 829 (defun tar-unflag-backwards (p)
 830   "*In Tar mode, un-mark this sub-file if it is marked to be deleted.
 831 With a prefix argument, un-mark that many files backward."
 832   (interactive "p")
 833   (tar-flag-deleted (- p) t))
 834
 835
 836 (defun tar-expunge-internal ()
 837   "Expunge the tar-entry specified by the current line."
 838   (let* ((descriptor (tar-current-descriptor))
 839          (tokens (tar-desc-tokens descriptor))
 840          (line (tar-desc-data-start descriptor))
 841          (name (tar-header-name tokens))
 842          (size (tar-header-size tokens))
 843          (link-p (tar-header-link-type tokens))
 844          (start (tar-desc-data-start descriptor))
 845          (following-descs (cdr (memq descriptor tar-parse-info))))
 846     (if link-p (setq size 0)) ; size lies for hard-links.
 847     ;;
 848     ;; delete the current line...
 849     (beginning-of-line)
 850     (let ((line-start (point)))
 851       (end-of-line) (forward-char)
 852       (let ((line-len (- (point) line-start)))
 853         (delete-region line-start (point))
 854         ;;
 855         ;; decrement the header-pointer to be in sync...
 856         (setq tar-header-offset (- tar-header-offset line-len))))
 857     ;;
 858     ;; delete the data pointer...
 859     (setq tar-parse-info (delq descriptor tar-parse-info))
 860     ;;
 861     ;; delete the data from inside the file...
 862     (widen)
 863     (let* ((data-start (+ start tar-header-offset -513))
 864            (data-end (+ data-start 512 (ash (ash (+ size 511) -9) 9))))
 865       (delete-region data-start data-end)
 866       ;;
 867       ;; and finally, decrement the start-pointers of all following
 868       ;; entries in the archive.  This is a pig when deleting a bunch
 869       ;; of files at once - we could optimize this to only do the
 870       ;; iteration over the files that remain, or only iterate up to
 871       ;; the next file to be deleted.
 872       (let ((data-length (- data-end data-start)))
 873         (tar-dolist (desc following-descs)
 874           (tar-setf (tar-desc-data-start desc)
 875                     (- (tar-desc-data-start desc) data-length))))
 876       ))
 877   (narrow-to-region 1 tar-header-offset))
 878
 879
 880 (defun tar-expunge (&optional noconfirm)
 881   "*In Tar mode, delete all the archived files flagged for deletion.
 882 This does not modify the disk image; you must save the tar file itself
 883 for this to be permanent."
 884   (interactive)
 885   (if (or noconfirm
 886           (y-or-n-p "Expunge files marked for deletion? "))
 887       (let ((n 0))
 888         (save-excursion
 889           (goto-char 0)
 890           (while (not (eobp))
 891             (if (looking-at "D")
 892                 (progn (tar-expunge-internal)
 893                        (setq n (1+ n)))
 894                 (forward-line 1)))
 895           ;; after doing the deletions, add any padding that may be necessary.
 896           (tar-pad-to-blocksize)
 897           (narrow-to-region 1 tar-header-offset)
 898           )
 899         (if (zerop n)
 900             (message "Nothing to expunge.")
 901             (message "%s files expunged.  Be sure to save this buffer." n)))))
 902
 903
 904 (defun tar-clear-modification-flags ()
 905   "Remove the stars at the beginning of each line."
 906   (interactive)
 907   (save-excursion
 908     (goto-char 1)
 909     (while (< (point) tar-header-offset)
 910       (if (not (eq (following-char) ?\ ))
 911           (progn (delete-char 1) (insert " ")))
 912       (forward-line 1))))
 913
 914
 915 (defun tar-chown-entry (new-uid)
 916   "*Change the user-id associated with this entry in the tar file.
 917 If this tar file was written by GNU tar, then you will be able to edit
 918 the user id as a string; otherwise, you must edit it as a number.
 919 You can force editing as a number by calling this with a prefix arg.
 920 This does not modify the disk image; you must save the tar file itself
 921 for this to be permanent."
 922   (interactive (list
 923                  (let ((tokens (tar-desc-tokens (tar-current-descriptor))))
 924                    (if (or current-prefix-arg
 925                            (not (tar-header-magic tokens)))
 926                        (let (n)
 927                          (while (not (numberp (setq n (read-minibuffer
 928                                                         "New UID number: "
 929                                                         (format "%s" (tar-header-uid tokens)))))))
 930                          n)
 931                        (read-string "New UID string: " (tar-header-uname tokens))))))
 932   (cond ((stringp new-uid)
 933          (tar-setf (tar-header-uname (tar-desc-tokens (tar-current-descriptor)))
 934                    new-uid)
 935          (tar-alter-one-field tar-uname-offset (concat new-uid "\000")))
 936         (t
 937          (tar-setf (tar-header-uid (tar-desc-tokens (tar-current-descriptor)))
 938                    new-uid)
 939          (tar-alter-one-field tar-uid-offset
 940            (concat (substring (format "%6o" new-uid) 0 6) "\000 ")))))
 941
 942
 943 (defun tar-chgrp-entry (new-gid)
 944   "*Change the group-id associated with this entry in the tar file.
 945 If this tar file was written by GNU tar, then you will be able to edit
 946 the group id as a string; otherwise, you must edit it as a number.
 947 You can force editing as a number by calling this with a prefix arg.
 948 This does not modify the disk image; you must save the tar file itself
 949 for this to be permanent."
 950   (interactive (list
 951                  (let ((tokens (tar-desc-tokens (tar-current-descriptor))))
 952                    (if (or current-prefix-arg
 953                            (not (tar-header-magic tokens)))
 954                        (let (n)
 955                          (while (not (numberp (setq n (read-minibuffer
 956                                                         "New GID number: "
 957                                                         (format "%s" (tar-header-gid tokens)))))))
 958                          n)
 959                        (read-string "New GID string: " (tar-header-gname tokens))))))
 960   (cond ((stringp new-gid)
 961          (tar-setf (tar-header-gname (tar-desc-tokens (tar-current-descriptor)))
 962                    new-gid)
 963          (tar-alter-one-field tar-gname-offset
 964            (concat new-gid "\000")))
 965         (t
 966          (tar-setf (tar-header-gid (tar-desc-tokens (tar-current-descriptor)))
 967                    new-gid)
 968          (tar-alter-one-field tar-gid-offset
 969            (concat (substring (format "%6o" new-gid) 0 6) "\000 ")))))
 970
 971 (defun tar-rename-entry (new-name)
 972   "*Change the name associated with this entry in the tar file.
 973 This does not modify the disk image; you must save the tar file itself
 974 for this to be permanent."
 975   (interactive
 976     (list (read-string "New name: "
 977             (tar-header-name (tar-desc-tokens (tar-current-descriptor))))))
 978   (if (string= "" new-name) (error "zero length name"))
 979   (if (> (length new-name) 98) (error "name too long"))
 980   (tar-setf (tar-header-name (tar-desc-tokens (tar-current-descriptor)))
 981             new-name)
 982   (tar-alter-one-field 0
 983     (substring (concat new-name (make-string 99 0)) 0 99)))
 984
 985
 986 (defun tar-chmod-entry (new-mode)
 987   "*Change the protection bits associated with this entry in the tar file.
 988 This does not modify the disk image; you must save the tar file itself
 989 for this to be permanent."
 990   (interactive (list (tar-parse-octal-integer-safe
 991                        (read-string "New protection (octal): "))))
 992   (tar-setf (tar-header-mode (tar-desc-tokens (tar-current-descriptor)))
 993             new-mode)
 994   (tar-alter-one-field tar-mode-offset
 995     (concat (substring (format "%6o" new-mode) 0 6) "\000 ")))
 996
 997
 998 (defun tar-alter-one-field (data-position new-data-string)
 999   (let* ((descriptor (tar-current-descriptor))
1000          (tokens (tar-desc-tokens descriptor)))
1001     (unwind-protect
1002         (save-excursion
1003           ;;
1004           ;; update the header-line.
1005           (beginning-of-line)
1006           (let ((p (point)))
1007             (forward-line 1)
1008             (delete-region p (point))
1009             (insert (tar-header-block-summarize tokens) "\n")
1010             (setq tar-header-offset (point-max)))
1011
1012           (widen)
1013           (let* ((start (+ (tar-desc-data-start descriptor) tar-header-offset -513)))
1014             ;;
1015             ;; delete the old field and insert a new one.
1016             (goto-char (+ start data-position))
1017             (delete-region (point) (+ (point) (length new-data-string))) ; <--
1018             (insert new-data-string) ; <--
1019             ;;
1020             ;; compute a new checksum and insert it.
1021             (let ((chk (tar-header-block-checksum
1022                         (buffer-substring start (+ start 512)))))
1023               (goto-char (+ start tar-chk-offset))
1024               (delete-region (point) (+ (point) 8))
1025               (insert (format "%6o" chk))
1026               (insert 0)
1027               (insert ? )
1028               (tar-setf (tar-header-checksum tokens) chk)
1029               ;;
1030               ;; ok, make sure we didn't botch it.
1031               (tar-header-block-check-checksum
1032                 (buffer-substring start (+ start 512))
1033                 chk (tar-header-name tokens))
1034               )))
1035       (narrow-to-region 1 tar-header-offset))))
1036
1037
1038 (defun tar-octal-time (timeval)
1039   ;; Format a timestamp as 11 octal digits.  Ghod, I hope this works...
1040   (let ((hibits (car timeval)) (lobits (car (cdr timeval))))
1041     (insert (format "%05o%01o%05o"
1042                     (lsh hibits -2)
1043                     (logior (lsh (logand 3 hibits) 1) (> (logand lobits 32768) 0))
1044                     (logand 32767 lobits)
1045                     ))))
1046
1047 (defun tar-subfile-save-buffer ()
1048   "In tar subfile mode, save this buffer into its parent tar-file buffer.
1049 This doesn't write anything to disk; you must save the parent tar-file buffer
1050 to make your changes permanent."
1051   (interactive)
1052   (if (not (and (boundp 'tar-superior-buffer) tar-superior-buffer))
1053     (error "This buffer has no superior tar file buffer"))
1054   (if (not (and (boundp 'tar-superior-descriptor) tar-superior-descriptor))
1055     (error "This buffer doesn't have an index into its superior tar file!"))
1056   (save-excursion
1057   (let ((subfile (current-buffer))
1058         (subfile-size (buffer-size))
1059         (descriptor tar-superior-descriptor))
1060     (set-buffer tar-superior-buffer)
1061     (let* ((tokens (tar-desc-tokens descriptor))
1062            (start (tar-desc-data-start descriptor))
1063            (name (tar-header-name tokens))
1064            (size (tar-header-size tokens))
1065            (size-pad (ash (ash (+ size 511) -9) 9))
1066            (head (memq descriptor tar-parse-info))
1067            (following-descs (cdr head)))
1068       (if (not head)
1069         (error "Can't find this tar file entry in its parent tar file!"))
1070       (unwind-protect
1071        (save-excursion
1072         (widen)
1073         ;; delete the old data...
1074         (let* ((data-start (+ start tar-header-offset -1))
1075                (data-end (+ data-start (ash (ash (+ size 511) -9) 9))))
1076           (delete-region data-start data-end)
1077           ;; insert the new data...
1078           (goto-char data-start)
1079           (insert-buffer subfile)
1080           ;;
1081           ;; pad the new data out to a multiple of 512...
1082           (let ((subfile-size-pad (ash (ash (+ subfile-size 511) -9) 9)))
1083             (goto-char (+ data-start subfile-size))
1084             (insert (make-string (- subfile-size-pad subfile-size) 0))
1085             ;;
1086             ;; update the data pointer of this and all following files...
1087             (tar-setf (tar-header-size tokens) subfile-size)
1088             (let ((difference (- subfile-size-pad size-pad)))
1089               (tar-dolist (desc following-descs)
1090                 (tar-setf (tar-desc-data-start desc)
1091                           (+ (tar-desc-data-start desc) difference))))
1092             ;;
1093             ;; Update the size field in the header block.
1094             (let ((header-start (- data-start 512)))
1095               (goto-char (+ header-start tar-size-offset))
1096               (delete-region (point) (+ (point) 12))
1097               (insert (format "%11o" subfile-size))
1098               (insert ? )
1099               ;;
1100               ;; Maybe update the datestamp.
1101               (if (not tar-update-datestamp)
1102                   nil
1103                 (goto-char (+ header-start tar-time-offset))
1104                 (delete-region (point) (+ (point) 12))
1105                 (insert (tar-octal-time (current-time)))
1106                 (insert ? ))
1107               ;;
1108               ;; compute a new checksum and insert it.
1109               (let ((chk (tar-header-block-checksum
1110                           (buffer-substring header-start data-start))))
1111                 (goto-char (+ header-start tar-chk-offset))
1112                 (delete-region (point) (+ (point) 8))
1113                 (insert (format "%6o" chk))
1114                 (insert 0)
1115                 (insert ? )
1116                 (tar-setf (tar-header-checksum tokens) chk)))
1117             ;;
1118             ;; alter the descriptor-line...
1119             ;;
1120             (let ((position (- (length tar-parse-info) (length head))))
1121               (goto-char 1)
1122               (next-line position)
1123               (beginning-of-line)
1124               (let ((p (point))
1125                     after
1126                     (m (set-marker (make-marker) tar-header-offset)))
1127                 (forward-line 1)
1128                 (setq after (point))
1129                 ;; Insert the new text after the old, before deleting,
1130                 ;; to preserve the window start.
1131                 (insert-before-markers (tar-header-block-summarize tokens t) "\n")
1132                 (delete-region p after)
1133                 (setq tar-header-offset (marker-position m)))
1134               )))
1135         ;; after doing the insertion, add any final padding that may be necessary.
1136         (tar-pad-to-blocksize))
1137        (narrow-to-region 1 tar-header-offset)))
1138     (set-buffer-modified-p t)   ; mark the tar file as modified
1139     (set-buffer subfile)
1140     (set-buffer-modified-p nil) ; mark the tar subfile as unmodified
1141     (message "Saved into tar-buffer `%s'.  Be sure to save that buffer!"
1142              (buffer-name tar-superior-buffer))
1143     ;; Prevent ordinary saving from happening.
1144     t)))
1145
1146
1147 (defun tar-pad-to-blocksize ()
1148   "If we are being anal about tar file blocksizes, fix up the current buffer.
1149 Leaves the region wide."
1150   (if (null tar-anal-blocksize)
1151       nil
1152     (widen)
1153     (let* ((last-desc (nth (1- (length tar-parse-info)) tar-parse-info))
1154            (start (tar-desc-data-start last-desc))
1155            (tokens (tar-desc-tokens last-desc))
1156            (link-p (tar-header-link-type tokens))
1157            (size (if link-p 0 (tar-header-size tokens)))
1158            (data-end (+ start size))
1159            (bbytes (ash tar-anal-blocksize 9))
1160            (pad-to (+ bbytes (* bbytes (/ (1- data-end) bbytes))))
1161            (inhibit-read-only t) ; ##
1162            )
1163       ;; If the padding after the last data is too long, delete some;
1164       ;; else insert some until we are padded out to the right number of blocks.
1165       ;;
1166       (goto-char (+ (or tar-header-offset 0) data-end))
1167       (if (> (1+ (buffer-size)) (+ (or tar-header-offset 0) pad-to))
1168           (delete-region (+ (or tar-header-offset 0) pad-to) (1+ (buffer-size)))
1169           (insert (make-string (- (+ (or tar-header-offset 0) pad-to)
1170                                   (1+ (buffer-size)))
1171                                0)))
1172       )))
1173
1174
1175 ;; Used in write-file-hook to write tar-files out correctly.
1176 (defun tar-mode-write-file ()
1177   (unwind-protect
1178       (save-excursion
1179         (widen)
1180         ;; Doing this here confuses things - the region gets left too wide!
1181         ;; I suppose this is run in a context where changing the buffer is bad.
1182         ;; (tar-pad-to-blocksize)
1183         (write-region tar-header-offset (point-max) buffer-file-name nil t)
1184         (tar-clear-modification-flags))
1185     (narrow-to-region 1 tar-header-offset))
1186   ;; return T because we've written the file.
1187   t)
1188 \f
1189 (provide 'tar-mode)
1190
1191 ;;; tar-mode.el ends here