tar-mode.el 42.2 KB
Newer Older
Eric S. Raymond's avatar
Eric S. Raymond committed
1
;;; tar-mode.el --- simple editing of tar files from GNU emacs
Richard M. Stallman's avatar
Richard M. Stallman committed
2

Eric S. Raymond's avatar
Eric S. Raymond committed
3 4
;;; Copyright (C) 1990, 1991 Free Software Foundation, Inc.

Eric S. Raymond's avatar
Eric S. Raymond committed
5
;; Author: Jamie Zawinski <jwz@lucid.com>
Eric S. Raymond's avatar
Eric S. Raymond committed
6
;; Created: 04 Apr 1990
Eric S. Raymond's avatar
Eric S. Raymond committed
7
;; Version: 1.21
Eric S. Raymond's avatar
Eric S. Raymond committed
8
;; Keywords: unix
Richard M. Stallman's avatar
Richard M. Stallman committed
9 10 11 12 13

;;; This file is part of GNU Emacs.
;;;
;;; GNU Emacs is free software; you can redistribute it and/or modify
;;; it under the terms of the GNU General Public License as published by
Eric S. Raymond's avatar
Eric S. Raymond committed
14
;;; the Free Software Foundation; either version 2, or (at your option)
Richard M. Stallman's avatar
Richard M. Stallman committed
15 16 17 18 19 20 21 22 23 24 25
;;; any later version.
;;;
;;; GNU Emacs is distributed in the hope that it will be useful,
;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;;; GNU General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with GNU Emacs; see the file COPYING.  If not, write to
;;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.

Eric S. Raymond's avatar
Eric S. Raymond committed
26 27
;;; Commentary:

Richard M. Stallman's avatar
Richard M. Stallman committed
28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92
;;; This package attempts to make dealing with Unix 'tar' archives easier.
;;; When this code is loaded, visiting a file whose name ends in '.tar' will
;;; cause the contents of that archive file to be displayed in a Dired-like
;;; listing.  It is then possible to use the customary Dired keybindings to
;;; extract sub-files from that archive, either by reading them into their own
;;; editor buffers, or by copying them directly to arbitrary files on disk.
;;; It is also possible to delete sub-files from within the tar file and write
;;; the modified archive back to disk, or to edit sub-files within the archive
;;; and re-insert the modified files into the archive.  See the documentation
;;; string of tar-mode for more info.

;;; To autoload, add this to your .emacs file:
;;;
;;;  (setq auto-mode-alist (cons '("\\.tar$" . tar-mode) auto-mode-alist))
;;;  (autoload 'tar-mode "tar-mode")
;;;
;;; But beware: for certain tar files - those whose very first file has 
;;; a -*- property line - autoloading won't work.  See the function 
;;; "tar-normal-mode" to understand why.

;;; This code now understands the extra fields that GNU tar adds to tar files.

;;; This interacts correctly with "uncompress.el" in the Emacs library,
;;; which you get with 
;;;
;;;  (autoload 'uncompress-while-visiting "uncompress")
;;;  (setq auto-mode-alist (cons '("\\.Z$" . uncompress-while-visiting)
;;;			   auto-mode-alist))
;;;
;;; Do not attempt to use tar-mode.el with crypt.el, you will lose.

;;;    ***************   TO DO   *************** 
;;;
;;; o  chmod should understand "a+x,og-w".
;;;
;;; o  It's not possible to add a NEW file to a tar archive; not that 
;;;    important, but still...
;;;
;;; o  In the directory listing, we don't show creation times because I don't
;;;    know how to print an arbitrary date, and I don't really want to have to
;;;    implement decode-universal-time.
;;;
;;; o  The code is less efficient that it could be - in a lot of places, I
;;;    pull a 512-character string out of the buffer and parse it, when I could
;;;    be parsing it in place, not garbaging a string.  Should redo that.
;;;
;;; o  I'd like a command that searches for a string/regexp in every subfile
;;;    of an archive, where <esc> would leave you in a subfile-edit buffer.
;;;    (Like the Meta-R command of the Zmacs mail reader.)
;;;
;;; o  Sometimes (but not always) reverting the tar-file buffer does not 
;;;    re-grind the listing, and you are staring at the binary tar data.
;;;    Typing 'g' again immediately after that will always revert and re-grind
;;;    it, though.  I have no idea why this happens.
;;;
;;; o  Tar-mode interacts poorly with crypt.el and zcat.el because the tar
;;;    write-file-hook actually writes the file.  Instead it should remove the
;;;    header (and conspire to put it back afterwards) so that other write-file
;;;    hooks which frob the buffer have a chance to do their dirty work.  There
;;;    might be a problem if the tar write-file-hook does not come *first* on
;;;    the list.
;;;
;;; o  Block files, sparse files, continuation files, and the various header 
;;;    types aren't editable.  Actually I don't know that they work at all.

Eric S. Raymond's avatar
Eric S. Raymond committed
93 94
;;; Code:

Richard M. Stallman's avatar
Richard M. Stallman committed
95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110
(defvar tar-anal-blocksize 20
  "*The blocksize of tar files written by Emacs, or nil, meaning don't care.
The blocksize of a tar file is not really the size of the blocks; rather, it is
the number of blocks written with one system call.  When tarring to a tape, 
this is the size of the *tape* blocks, but when writing to a file, it doesn't
matter much.  The only noticeable difference is that if a tar file does not
have a blocksize of 20, tar will tell you that; all this really controls is
how many null padding bytes go on the end of the tar file.")

(defvar tar-update-datestamp nil
  "*Whether tar-mode should play fast and loose with sub-file datestamps;
if this is true, then editing and saving a tar file entry back into its
tar file will update its datestamp.  If false, the datestamp is unchanged.
You may or may not want this - it is good in that you can tell when a file
in a tar archive has been changed, but it is bad for the same reason that
editing a file in the tar archive at all is bad - the changed version of 
Jim Blandy's avatar
Jim Blandy committed
111
the file never exists on disk.")
Richard M. Stallman's avatar
Richard M. Stallman committed
112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918



;;; First, duplicate some Common Lisp functions; I used to just (require 'cl)
;;; but "cl.el" was messing some people up (also it's really big).

(defmacro tar-setf (form val)
  "A mind-numbingly simple implementation of setf."
  (let ((mform (macroexpand form (and (boundp 'byte-compile-macro-environment)
				      byte-compile-macro-environment))))
    (cond ((symbolp mform) (list 'setq mform val))
	  ((not (consp mform)) (error "can't setf %s" form))
	  ((eq (car mform) 'aref)
	   (list 'aset (nth 1 mform) (nth 2 mform) val))
	  ((eq (car mform) 'car)
	   (list 'setcar (nth 1 mform) val))
	  ((eq (car mform) 'cdr)
	   (list 'setcdr (nth 1 mform) val))
	  (t (error "don't know how to setf %s" form)))))

(defmacro tar-dolist (control &rest body)
  "syntax: (dolist (var-name list-expr &optional return-value) &body body)"
  (let ((var (car control))
	(init (car (cdr control)))
	(val (car (cdr (cdr control)))))
    (list 'let (list (list '_dolist_iterator_ init))
	  (list 'while '_dolist_iterator_
	    (cons 'let
	      (cons (list (list var '(car _dolist_iterator_)))
		    (append body
			    (list (list 'setq '_dolist_iterator_
					(list 'cdr '_dolist_iterator_)))))))
	  val)))

(defmacro tar-dotimes (control &rest body)
  "syntax: (dolist (var-name count-expr &optional return-value) &body body)"
  (let ((var (car control))
	(n (car (cdr control)))
	(val (car (cdr (cdr control)))))
    (list 'let (list (list '_dotimes_end_ n)
		     (list var 0))
	  (cons 'while
		(cons (list '< var '_dotimes_end_)
		      (append body
			      (list (list 'setq var (list '1+ var))))))
	  val)))


;;; down to business.

(defmacro make-tar-header (name mode uid git size date ck lt ln
			   magic uname gname devmaj devmin)
  (list 'vector name mode uid git size date ck lt ln
	magic uname gname devmaj devmin))

(defmacro tar-header-name (x) (list 'aref x 0))
(defmacro tar-header-mode (x) (list 'aref x 1))
(defmacro tar-header-uid  (x) (list 'aref x 2))
(defmacro tar-header-gid  (x) (list 'aref x 3))
(defmacro tar-header-size (x) (list 'aref x 4))
(defmacro tar-header-date (x) (list 'aref x 5))
(defmacro tar-header-checksum  (x) (list 'aref x 6))
(defmacro tar-header-link-type (x) (list 'aref x 7))
(defmacro tar-header-link-name (x) (list 'aref x 8))
(defmacro tar-header-magic (x) (list 'aref x 9))
(defmacro tar-header-uname (x) (list 'aref x 10))
(defmacro tar-header-gname (x) (list 'aref x 11))
(defmacro tar-header-dmaj (x) (list 'aref x 12))
(defmacro tar-header-dmin (x) (list 'aref x 13))

(defmacro make-tar-desc (data-start tokens)
  (list 'cons data-start tokens))

(defmacro tar-desc-data-start (x) (list 'car x))
(defmacro tar-desc-tokens     (x) (list 'cdr x))

(defconst tar-name-offset 0)
(defconst tar-mode-offset (+ tar-name-offset 100))
(defconst tar-uid-offset  (+ tar-mode-offset 8))
(defconst tar-gid-offset  (+ tar-uid-offset 8))
(defconst tar-size-offset (+ tar-gid-offset 8))
(defconst tar-time-offset (+ tar-size-offset 12))
(defconst tar-chk-offset  (+ tar-time-offset 12))
(defconst tar-linkp-offset (+ tar-chk-offset 8))
(defconst tar-link-offset (+ tar-linkp-offset 1))
;;; GNU-tar specific slots.
(defconst tar-magic-offset (+ tar-link-offset 100))
(defconst tar-uname-offset (+ tar-magic-offset 8))
(defconst tar-gname-offset (+ tar-uname-offset 32))
(defconst tar-dmaj-offset (+ tar-gname-offset 32))
(defconst tar-dmin-offset (+ tar-dmaj-offset 8))
(defconst tar-end-offset (+ tar-dmin-offset 8))

(defun tokenize-tar-header-block (string)
  "Returns a 'tar-header' structure (a list of name, mode, uid, gid, size, 
write-date, checksum, link-type, and link-name)."
  (cond ((< (length string) 512) nil)
	(;(some 'plusp string)		 ; <-- oops, massive cycle hog!
	 (or (not (= 0 (aref string 0))) ; This will do.
	     (not (= 0 (aref string 101))))
	 (let* ((name-end (1- tar-mode-offset))
		(link-end (1- tar-magic-offset))
		(uname-end (1- tar-gname-offset))
		(gname-end (1- tar-dmaj-offset))
		(link-p (aref string tar-linkp-offset))
		(magic-str (substring string tar-magic-offset (1- tar-uname-offset)))
		(uname-valid-p (or (string= "ustar  " magic-str) (string= "GNUtar " magic-str)))
		name
		(nulsexp   "[^\000]*\000"))
	   (and (string-match nulsexp string tar-name-offset) (setq name-end (min name-end (1- (match-end 0)))))
	   (and (string-match nulsexp string tar-link-offset) (setq link-end (min link-end (1- (match-end 0)))))
	   (and (string-match nulsexp string tar-uname-offset) (setq uname-end (min uname-end (1- (match-end 0)))))
	   (and (string-match nulsexp string tar-gname-offset) (setq gname-end (min gname-end (1- (match-end 0)))))
	   (setq name (substring string tar-name-offset name-end)
		 link-p (if (or (= link-p 0) (= link-p ?0))
			    nil
			  (- link-p ?0)))
	   (if (and (null link-p) (string-match "/$" name)) (setq link-p 5)) ; directory
	   (make-tar-header
	     name
	     (tar-parse-octal-integer string tar-mode-offset (1- tar-uid-offset))
	     (tar-parse-octal-integer string tar-uid-offset (1- tar-gid-offset))
	     (tar-parse-octal-integer string tar-gid-offset (1- tar-size-offset))
	     (tar-parse-octal-integer string tar-size-offset (1- tar-time-offset))
	     (tar-parse-octal-integer string tar-time-offset (1- tar-chk-offset))
	     (tar-parse-octal-integer string tar-chk-offset (1- tar-linkp-offset))
	     link-p
	     (substring string tar-link-offset link-end)
	     uname-valid-p
	     (and uname-valid-p (substring string tar-uname-offset uname-end))
	     (and uname-valid-p (substring string tar-gname-offset gname-end))
	     (tar-parse-octal-integer string tar-dmaj-offset (1- tar-dmin-offset))
	     (tar-parse-octal-integer string tar-dmin-offset (1- tar-end-offset))
	     )))
	(t 'empty-tar-block)))


(defun tar-parse-octal-integer (string &optional start end)
  "deletes all your files, and then reboots."
  (if (null start) (setq start 0))
  (if (null end) (setq end (length string)))
  (if (= (aref string start) 0)
      0
    (let ((n 0))
      (while (< start end)
	(setq n (if (< (aref string start) ?0) n
		  (+ (* n 8) (- (aref string start) 48)))
	      start (1+ start)))
      n)))

(defun tar-parse-octal-integer-safe (string)
  (let ((L (length string)))
    (if (= L 0) (error "empty string"))
    (tar-dotimes (i L)
       (if (or (< (aref string i) ?0)
	       (> (aref string i) ?7))
	   (error "'%c' is not an octal digit."))))
  (tar-parse-octal-integer string))


(defun checksum-tar-header-block (string)
  "Computes and returns a tar-acceptable checksum for this block."
  (let* ((chk-field-start tar-chk-offset)
	 (chk-field-end (+ chk-field-start 8))
	 (sum 0)
	 (i 0))
    ;; Add up all of the characters except the ones in the checksum field.
    ;; Add that field as if it were filled with spaces.
    (while (< i chk-field-start)
      (setq sum (+ sum (aref string i))
	    i (1+ i)))
    (setq i chk-field-end)
    (while (< i 512)
      (setq sum (+ sum (aref string i))
	    i (1+ i)))
    (+ sum (* 32 8))))

(defun check-tar-header-block-checksum (hblock desired-checksum file-name)
  "Beep and print a warning if the checksum doesn't match."
  (if (not (= desired-checksum (checksum-tar-header-block hblock)))
      (progn (beep) (message "Invalid checksum for file %s!" file-name))))

(defun recompute-tar-header-block-checksum (hblock)
  "Modifies the given string to have a valid checksum field."
  (let* ((chk (checksum-tar-header-block hblock))
	 (chk-string (format "%6o" chk))
	 (l (length chk-string)))
    (aset hblock 154 0)
    (aset hblock 155 32)
    (tar-dotimes (i l) (aset hblock (- 153 i) (aref chk-string (- l i 1)))))
  hblock)


(defun tar-grind-file-mode (mode string start)
  "Write a \"-rw--r--r-\" representing MODE into STRING beginning at START."
  (aset string start       (if (zerop (logand 256 mode)) ?- ?r))
  (aset string (+ start 1) (if (zerop (logand 128 mode)) ?- ?w))
  (aset string (+ start 2) (if (zerop (logand  64 mode)) ?- ?x)) 
  (aset string (+ start 3) (if (zerop (logand  32 mode)) ?- ?r))
  (aset string (+ start 4) (if (zerop (logand  16 mode)) ?- ?w))
  (aset string (+ start 5) (if (zerop (logand   8 mode)) ?- ?x))
  (aset string (+ start 6) (if (zerop (logand   4 mode)) ?- ?r))
  (aset string (+ start 7) (if (zerop (logand   2 mode)) ?- ?w))
  (aset string (+ start 8) (if (zerop (logand   1 mode)) ?- ?x))
  (if (zerop (logand 1024 mode)) nil (aset string (+ start 2) ?s))
  (if (zerop (logand 2048 mode)) nil (aset string (+ start 5) ?s))
  string)

(defun summarize-tar-header-block (tar-hblock &optional mod-p)
  "Returns a line similar to the output of 'tar -vtf'."
  (let ((name (tar-header-name tar-hblock))
	(mode (tar-header-mode tar-hblock))
	(uid (tar-header-uid tar-hblock))
	(gid (tar-header-gid tar-hblock))
	(uname (tar-header-uname tar-hblock))
	(gname (tar-header-gname tar-hblock))
	(size (tar-header-size tar-hblock))
	(time (tar-header-date tar-hblock))
	(ck (tar-header-checksum tar-hblock))
	(link-p (tar-header-link-type tar-hblock))
	(link-name (tar-header-link-name tar-hblock))
	)
    (let* ((left 11)
	   (namew 8)
	   (groupw 8)
	   (sizew 8)
	   (datew 2)
	   (slash (1- (+ left namew)))
	   (lastdigit (+ slash groupw sizew))
	   (namestart (+ lastdigit datew))
	   (string (make-string (+ namestart (length name) (if link-p (+ 5 (length link-name)) 0)) 32))
	   (type (tar-header-link-type tar-hblock)))
      (aset string 0 (if mod-p ?* ? ))
      (aset string 1
	    (cond ((or (eq type nil) (eq type 0)) ?-)
		  ((eq type 1) ?l)  ; link
		  ((eq type 2) ?s)  ; symlink
		  ((eq type 3) ?c)  ; char special
		  ((eq type 4) ?b)  ; block special
		  ((eq type 5) ?d)  ; directory
		  ((eq type 6) ?p)  ; FIFO/pipe
		  ((eq type 20) ?*) ; directory listing
		  ((eq type 29) ?M) ; multivolume continuation
		  ((eq type 35) ?S) ; sparse
		  ((eq type 38) ?V) ; volume header
		  ))
      (tar-grind-file-mode mode string 2)
      (setq uid (if (= 0 (length uname)) (int-to-string uid) uname))
      (setq gid (if (= 0 (length gname)) (int-to-string gid) gname))
      (setq size (int-to-string size))
      (tar-dotimes (i (min (1- namew) (length uid))) (aset string (- slash i) (aref uid (- (length uid) i 1))))
      (aset string (1+ slash) ?/)
      (tar-dotimes (i (min (1- groupw) (length gid))) (aset string (+ (+ slash 2) i) (aref gid i)))
      (tar-dotimes (i (min sizew (length size))) (aset string (- lastdigit i) (aref size (- (length size) i 1))))
      ;; ## bloody hell, how do I print an arbitrary date??
      (tar-dotimes (i (length name)) (aset string (+ namestart i) (aref name i)))
      (if (or (eq link-p 1) (eq link-p 2))
	  (progn
	    (tar-dotimes (i 3) (aset string (+ namestart 1 (length name) i) (aref (if (= link-p 1) "==>" "-->") i)))
	    (tar-dotimes (i (length link-name)) (aset string (+ namestart 5 (length name) i) (aref link-name i)))))
      string)))


(defun tar-summarize-buffer ()
  "Parse the contents of the tar file in the current buffer, and place a
dired-like listing on the front; then narrow to it, so that only that listing
is visible (and the real data of the buffer is hidden)."
  (message "parsing tar file...")
  (let* ((result '())
	 (pos 1)
	 (bs (max 1 (- (buffer-size) 1024))) ; always 2+ empty blocks at end.
	 (bs100 (max 1 (/ bs 100)))
	(tokens nil))
    (while (not (eq tokens 'empty-tar-block))
      (let* ((hblock (buffer-substring pos (+ pos 512))))
	(setq tokens (tokenize-tar-header-block hblock))
	(setq pos (+ pos 512))
	(message "parsing tar file...%s%%"
		 ;(/ (* pos 100) bs)   ; this gets round-off lossage
		 (/ pos bs100)         ; this doesn't
		 )
	(if (eq tokens 'empty-tar-block)
	    nil
	  (if (null tokens) (error "premature EOF parsing tar file."))
	  (if (eq (tar-header-link-type tokens) 20)
	      ;; Foo.  There's an extra empty block after these.
	      (setq pos (+ pos 512)))
	  (let ((size (tar-header-size tokens)))
	    (if (< size 0)
		(error "%s has size %s - corrupted."
		       (tar-header-name tokens) size))
	    ;
	    ; This is just too slow.  Don't really need it anyway....
	    ;(check-tar-header-block-checksum
	    ;  hblock (checksum-tar-header-block hblock)
	    ;  (tar-header-name tokens))
	    
	    (setq result (cons (make-tar-desc pos tokens) result))
	    
	    (if (and (null (tar-header-link-type tokens))
		     (> size 0))
		(setq pos
		  (+ pos 512 (ash (ash (1- size) -9) 9))        ; this works
		  ;(+ pos (+ size (- 512 (rem (1- size) 512)))) ; this doesn't
		  ))
	    ))))
    (make-local-variable 'tar-parse-info)
    (setq tar-parse-info (nreverse result)))
  (save-excursion
    (goto-char (point-min))
    (let ((buffer-read-only nil))
      (tar-dolist (tar-desc tar-parse-info)
	(insert-string
	  (summarize-tar-header-block (tar-desc-tokens tar-desc)))
	(insert-string "\n"))
      (make-local-variable 'tar-header-offset)
      (setq tar-header-offset (point))
      (narrow-to-region 1 tar-header-offset)
      (set-buffer-modified-p nil)))
  (message "parsing tar file...done."))


(defvar tar-mode-map nil "*Local keymap for tar-mode listings.")

(if tar-mode-map
    nil
  (setq tar-mode-map (make-keymap))
  (suppress-keymap tar-mode-map)
  (define-key tar-mode-map " " 'tar-next-line)
  (define-key tar-mode-map "c" 'tar-copy)
  (define-key tar-mode-map "d" 'tar-flag-deleted)
  (define-key tar-mode-map "\^D" 'tar-flag-deleted)
  (define-key tar-mode-map "e" 'tar-extract)
  (define-key tar-mode-map "f" 'tar-extract)
  (define-key tar-mode-map "g" 'revert-buffer)
  (define-key tar-mode-map "h" 'describe-mode)
  (define-key tar-mode-map "n" 'tar-next-line)
  (define-key tar-mode-map "\^N" 'tar-next-line)
  (define-key tar-mode-map "o" 'tar-extract-other-window)
  (define-key tar-mode-map "\^C" 'tar-copy)
  (define-key tar-mode-map "p" 'tar-previous-line)
  (define-key tar-mode-map "\^P" 'tar-previous-line)
  (define-key tar-mode-map "r" 'tar-rename-entry)
  (define-key tar-mode-map "u" 'tar-unflag)
  (define-key tar-mode-map "v" 'tar-view)
  (define-key tar-mode-map "x" 'tar-expunge)
  (define-key tar-mode-map "\177" 'tar-unflag-backwards)
  (define-key tar-mode-map "E" 'tar-extract-other-window)
  (define-key tar-mode-map "M" 'tar-chmod-entry)
  (define-key tar-mode-map "G" 'tar-chgrp-entry)
  (define-key tar-mode-map "O" 'tar-chown-entry)
  )

;; tar mode is suitable only for specially formatted data.
(put 'tar-mode 'mode-class 'special)
(put 'tar-subfile-mode 'mode-class 'special)

(defun tar-mode ()
  "Major mode for viewing a tar file as a dired-like listing of its contents.
You can move around using the usual cursor motion commands. 
Letters no longer insert themselves.
Type 'e' to pull a file out of the tar file and into its own buffer.
Type 'c' to copy an entry from the tar file into another file on disk.

If you edit a sub-file of this archive (as with the 'e' command) and 
save it with Control-X Control-S, the contents of that buffer will be 
saved back into the tar-file buffer; in this way you can edit a file 
inside of a tar archive without extracting it and re-archiving it.

See also: variables tar-update-datestamp and tar-anal-blocksize.
\\{tar-mode-map}"
  ;; this is not interactive because you shouldn't be turning this
  ;; mode on and off.  You can corrupt things that way.
  (make-local-variable 'tar-header-offset)
  (make-local-variable 'tar-parse-info)
  (make-local-variable 'require-final-newline)
  (setq require-final-newline nil) ; binary data, dude...
  (make-local-variable 'revert-buffer-function)
  (setq revert-buffer-function 'tar-mode-revert)
  (setq major-mode 'tar-mode)
  (setq mode-name "Tar")
  (use-local-map tar-mode-map)
  (auto-save-mode 0)
  (widen)
  (if (and (boundp 'tar-header-offset) tar-header-offset)
      (narrow-to-region 1 tar-header-offset)
      (tar-summarize-buffer))
  (run-hooks 'tar-mode-hook)
  )


(defun tar-subfile-mode (p)
  "Minor mode for editing an element of a tar-file.
This mode redefines ^X^S to save the current buffer back into its 
associated tar-file buffer.  You must save that buffer to actually
save your changes to disk."
  (interactive "P")
  (or (and (boundp 'superior-tar-buffer) superior-tar-buffer)
      (error "This buffer is not an element of a tar file."))
  (or (assq 'tar-subfile-mode minor-mode-alist)
      (setq minor-mode-alist (append minor-mode-alist
				     (list '(tar-subfile-mode
					     " TarFile")))))
  (make-local-variable 'tar-subfile-mode)
  (setq tar-subfile-mode
	(if (null p)
	    (not tar-subfile-mode)
	    (> (prefix-numeric-value p) 0)))
  (cond (tar-subfile-mode
	 ;; copy the local keymap so that we don't accidentally
	 ;; alter a keymap like 'lisp-mode-map' which is shared
	 ;; by all buffers in that mode.
	 (let ((m (current-local-map)))
	   (if m (use-local-map (copy-keymap m))))
	 (local-set-key "\^X\^S" 'tar-subfile-save-buffer)
	 ;; turn off auto-save.
	 (auto-save-mode nil)
	 (setq buffer-auto-save-file-name nil)
	 (run-hooks 'tar-subfile-mode-hook))
	(t (local-set-key "\^X\^S" 'save-buffer)))
  )


(defun tar-mode-revert (&optional no-autosave no-confirm)
  "Revert this buffer and turn on tar mode again, to re-compute the
directory listing."
  (setq tar-header-offset nil)
  (let ((revert-buffer-function nil))
    (revert-buffer t no-confirm)
    (widen))
  (tar-mode))


(defun tar-next-line (p)
  (interactive "p")
  (forward-line p)
  (if (eobp) nil (forward-char 36)))

(defun tar-previous-line (p)
  (interactive "p")
  (tar-next-line (- p)))

(defun tar-current-descriptor (&optional noerror)
  "Returns the tar-descriptor of the current line, or signals an error."
  ;; I wish lines had plists, like in ZMACS...
  (or (nth (count-lines (point-min)
			(save-excursion (beginning-of-line) (point)))
	   tar-parse-info)
      (if noerror
	  nil
	  (error "This line does not describe a tar-file entry."))))


(defun tar-extract (&optional other-window-p)
  "*In tar-mode, extract this entry of the tar file into its own buffer."
  (interactive)
  (let* ((view-p (eq other-window-p 'view))
	 (descriptor (tar-current-descriptor))
	 (tokens (tar-desc-tokens descriptor))
	 (name (tar-header-name tokens))
	 (size (tar-header-size tokens))
	 (link-p (tar-header-link-type tokens))
	 (start (+ (tar-desc-data-start descriptor) tar-header-offset -1))
	 (end (+ start size)))
    (if link-p
	(error "This is a %s, not a real file."
	       (cond ((eq link-p 5) "directory")
		     ((eq link-p 20) "tar directory header")
		     ((eq link-p 29) "multivolume-continuation")
		     ((eq link-p 35) "sparse entry")
		     ((eq link-p 38) "volume header")
		     (t "link"))))
    (if (zerop size) (error "This is a zero-length file."))
    (let* ((tar-buffer (current-buffer))
	   (bufname (concat (file-name-nondirectory name)
			    " (" name " in "
			    (file-name-nondirectory (buffer-file-name))
			    ")"))
	   (read-only-p (or buffer-read-only view-p))
	   (buffer (get-buffer bufname))
	   (just-created nil))
      (if buffer
	  nil
	(setq buffer (get-buffer-create bufname))
	(setq just-created t)
	(unwind-protect
	    (progn
	      (widen)
	      (save-excursion
		(set-buffer buffer)
		(insert-buffer-substring tar-buffer start end)
		(goto-char 0)
		(set-visited-file-name name) ; give it a name to decide mode.
		(normal-mode)  ; pick a mode.
		(set-visited-file-name nil)  ; nuke the name - not meaningful.
		(rename-buffer bufname)
		
		(make-local-variable 'superior-tar-buffer)
		(make-local-variable 'superior-tar-descriptor)
		(setq superior-tar-buffer tar-buffer)
		(setq superior-tar-descriptor descriptor)
		(tar-subfile-mode 1)
		
		(setq buffer-read-only read-only-p)
		(set-buffer-modified-p nil))
	      (set-buffer tar-buffer))
	  (narrow-to-region 1 tar-header-offset)))
      (if view-p
	  (progn
	    (view-buffer buffer)
	    (and just-created (kill-buffer buffer)))
	  (if other-window-p
	      (switch-to-buffer-other-window buffer)
	      (switch-to-buffer buffer))))))


(defun tar-extract-other-window ()
  "*In tar-mode, extract this entry of the tar file into its own buffer."
  (interactive)
  (tar-extract t))

(defun tar-view ()
  "*In tar-mode, view the tar file entry on this line."
  (interactive)
  (tar-extract 'view))


(defun tar-read-file-name (&optional prompt)
  "Calls read-file-name, with the default being the file of the current
tar-file descriptor."
  (or prompt (setq prompt "Copy to: "))
  (let* ((default-file (expand-file-name
			(tar-header-name (tar-desc-tokens
					  (tar-current-descriptor)))))
	 (target (expand-file-name
		  (read-file-name prompt
				  (file-name-directory default-file)
				  default-file nil))))
    (if (or (string= "" (file-name-nondirectory target))
	    (file-directory-p target))
	(setq target (concat (if (string-match "/$" target)
				 (substring target 0 (1- (match-end 0)))
				 target)
			     "/"
			     (file-name-nondirectory default-file))))
    target))


(defun tar-copy (&optional to-file)
  "*In tar-mode, extract this entry of the tar file into a file on disk.
If TO-FILE is not supplied, it is prompted for, defaulting to the name of
the current tar-entry."
  (interactive (list (tar-read-file-name)))
  (let* ((descriptor (tar-current-descriptor))
	 (tokens (tar-desc-tokens descriptor))
	 (name (tar-header-name tokens))
	 (size (tar-header-size tokens))
	 (link-p (tar-header-link-type tokens))
	 (start (+ (tar-desc-data-start descriptor) tar-header-offset -1))
	 (end (+ start size)))
    (if link-p (error "This is a link, not a real file."))
    (if (zerop size) (error "This is a zero-length file."))
    (let* ((tar-buffer (current-buffer))
	   buffer)
      (unwind-protect
	  (progn
	    (setq buffer (generate-new-buffer "*tar-copy-tmp*"))
	    (widen)
	    (save-excursion
	      (set-buffer buffer)
	      (insert-buffer-substring tar-buffer start end)
	      (set-buffer-modified-p nil) ; in case we abort
	      (write-file to-file)
	      (message "Copied tar entry %s to %s" name to-file)
	      (set-buffer tar-buffer)))
	(narrow-to-region 1 tar-header-offset)
	(if buffer (kill-buffer buffer)))
      )))


(defun tar-flag-deleted (p &optional unflag)
  "*In tar mode, mark this sub-file to be deleted from the tar file.
With a prefix argument, mark that many files."
  (interactive "p")
  (beginning-of-line)
  (tar-dotimes (i (if (< p 0) (- p) p))
    (if (tar-current-descriptor unflag) ; barf if we're not on an entry-line.
	(progn
	  (delete-char 1)
	  (insert (if unflag " " "D"))))
    (forward-line (if (< p 0) -1 1)))
  (if (eobp) nil (forward-char 36)))

(defun tar-unflag (p)
  "*In tar mode, un-mark this sub-file if it is marked to be deleted.
With a prefix argument, un-mark that many files forward."
  (interactive "p")
  (tar-flag-deleted p t))

(defun tar-unflag-backwards (p)
  "*In tar mode, un-mark this sub-file if it is marked to be deleted.
With a prefix argument, un-mark that many files backward."
  (interactive "p")
  (tar-flag-deleted (- p) t))


(defun tar-expunge-internal ()
  "Expunge the tar-entry specified by the current line."
  (let* ((descriptor (tar-current-descriptor))
	 (tokens (tar-desc-tokens descriptor))
	 (line (tar-desc-data-start descriptor))
	 (name (tar-header-name tokens))
	 (size (tar-header-size tokens))
	 (link-p (tar-header-link-type tokens))
	 (start (tar-desc-data-start descriptor))
	 (following-descs (cdr (memq descriptor tar-parse-info))))
    (if link-p (setq size 0)) ; size lies for hard-links.
    ;;
    ;; delete the current line...
    (beginning-of-line)
    (let ((line-start (point)))
      (end-of-line) (forward-char)
      (let ((line-len (- (point) line-start)))
	(delete-region line-start (point))
	;;
	;; decrement the header-pointer to be in synch...
	(setq tar-header-offset (- tar-header-offset line-len))))
    ;;
    ;; delete the data pointer...
    (setq tar-parse-info (delq descriptor tar-parse-info))
    ;;
    ;; delete the data from inside the file...
    (widen)
    (let* ((data-start (+ start tar-header-offset -513))
	   (data-end (+ data-start 512 (ash (ash (+ size 511) -9) 9))))
      (delete-region data-start data-end)
      ;;
      ;; and finally, decrement the start-pointers of all following
      ;; entries in the archive.  This is a pig when deleting a bunch
      ;; of files at once - we could optimize this to only do the
      ;; iteration over the files that remain, or only iterate up to
      ;; the next file to be deleted.
      (let ((data-length (- data-end data-start)))
	(tar-dolist (desc following-descs)
	  (tar-setf (tar-desc-data-start desc)
		    (- (tar-desc-data-start desc) data-length))))
      ))
  (narrow-to-region 1 tar-header-offset))


(defun tar-expunge (&optional noconfirm)
  "*In tar-mode, delete all the archived files flagged for deletion.
This does not modify the disk image; you must save the tar file itself
for this to be permanent."
  (interactive)
  (if (or noconfirm
	  (y-or-n-p "expunge files marked for deletion? "))
      (let ((n 0))
	(save-excursion
	  (goto-char 0)
	  (while (not (eobp))
	    (if (looking-at "D")
		(progn (tar-expunge-internal)
		       (setq n (1+ n)))
		(forward-line 1)))
	  ;; after doing the deletions, add any padding that may be necessary.
	  (tar-pad-to-blocksize)
	  (narrow-to-region 1 tar-header-offset)
	  )
	(if (zerop n)
	    (message "nothing to expunge.")
	    (message "%s expunged.  Be sure to save this buffer." n)))))


(defun tar-clear-modification-flags ()
  "remove the stars at the beginning of each line."
  (save-excursion
    (goto-char 0)
    (while (< (point) tar-header-offset)
      (if (looking-at "*")
	  (progn (delete-char 1) (insert " ")))
      (forward-line 1))))


(defun tar-chown-entry (new-uid)
  "*Change the user-id associated with this entry in the tar file.
If this tar file was written by GNU tar, then you will be able to edit
the user id as a string; otherwise, you must edit it as a number.
You can force editing as a number by calling this with a prefix arg.
This does not modify the disk image; you must save the tar file itself
for this to be permanent."
  (interactive (list
		 (let ((tokens (tar-desc-tokens (tar-current-descriptor))))
		   (if (or current-prefix-arg
			   (not (tar-header-magic tokens)))
		       (let (n)
			 (while (not (numberp (setq n (read-minibuffer
							"New UID number: "
							(format "%s" (tar-header-uid tokens)))))))
			 n)
		       (read-string "New UID string: " (tar-header-uname tokens))))))
  (cond ((stringp new-uid)
	 (tar-setf (tar-header-uname (tar-desc-tokens (tar-current-descriptor)))
		   new-uid)
	 (tar-alter-one-field tar-uname-offset (concat new-uid "\000")))
	(t
	 (tar-setf (tar-header-uid (tar-desc-tokens (tar-current-descriptor)))
		   new-uid)
	 (tar-alter-one-field tar-uid-offset
	   (concat (substring (format "%6o" new-uid) 0 6) "\000 ")))))


(defun tar-chgrp-entry (new-gid)
  "*Change the group-id associated with this entry in the tar file.
If this tar file was written by GNU tar, then you will be able to edit
the group id as a string; otherwise, you must edit it as a number.
You can force editing as a number by calling this with a prefix arg.
This does not modify the disk image; you must save the tar file itself
for this to be permanent."
  (interactive (list
		 (let ((tokens (tar-desc-tokens (tar-current-descriptor))))
		   (if (or current-prefix-arg
			   (not (tar-header-magic tokens)))
		       (let (n)
			 (while (not (numberp (setq n (read-minibuffer
							"New GID number: "
							(format "%s" (tar-header-gid tokens)))))))
			 n)
		       (read-string "New GID string: " (tar-header-gname tokens))))))
  (cond ((stringp new-gid)
	 (tar-setf (tar-header-gname (tar-desc-tokens (tar-current-descriptor)))
		   new-gid)
	 (tar-alter-one-field tar-gname-offset
	   (concat new-gid "\000")))
	(t
	 (tar-setf (tar-header-gid (tar-desc-tokens (tar-current-descriptor)))
		   new-gid)
	 (tar-alter-one-field tar-gid-offset
	   (concat (substring (format "%6o" new-gid) 0 6) "\000 ")))))

(defun tar-rename-entry (new-name)
  "*Change the name associated with this entry in the tar file.
This does not modify the disk image; you must save the tar file itself
for this to be permanent."
  (interactive
    (list (read-string "New name: "
	    (tar-header-name (tar-desc-tokens (tar-current-descriptor))))))
  (if (string= "" new-name) (error "zero length name."))
  (if (> (length new-name) 98) (error "name too long."))
  (tar-setf (tar-header-name (tar-desc-tokens (tar-current-descriptor)))
	    new-name)
  (tar-alter-one-field 0
    (substring (concat new-name (make-string 99 0)) 0 99)))


(defun tar-chmod-entry (new-mode)
  "*Change the protection bits associated with this entry in the tar file.
This does not modify the disk image; you must save the tar file itself
for this to be permanent."
  (interactive (list (tar-parse-octal-integer-safe
		       (read-string "New protection (octal): "))))
  (tar-setf (tar-header-mode (tar-desc-tokens (tar-current-descriptor)))
	    new-mode)
  (tar-alter-one-field tar-mode-offset
    (concat (substring (format "%6o" new-mode) 0 6) "\000 ")))


(defun tar-alter-one-field (data-position new-data-string)
  (let* ((descriptor (tar-current-descriptor))
	 (tokens (tar-desc-tokens descriptor)))
    (unwind-protect
	(save-excursion
	  ;;
	  ;; update the header-line.
	  (beginning-of-line)
	  (let ((p (point)))
	    (forward-line 1)
	    (delete-region p (point))
	    (insert (summarize-tar-header-block tokens) "\n")
	    (setq tar-header-offset (point-max)))
	  
	  (widen)
	  (let* ((start (+ (tar-desc-data-start descriptor) tar-header-offset -513)))
	    ;;
	    ;; delete the old field and insert a new one.
	    (goto-char (+ start data-position))
	    (delete-region (point) (+ (point) (length new-data-string))) ; <--
	    (insert new-data-string) ; <--
	    ;;
	    ;; compute a new checksum and insert it.
	    (let ((chk (checksum-tar-header-block
			(buffer-substring start (+ start 512)))))
	      (goto-char (+ start tar-chk-offset))
	      (delete-region (point) (+ (point) 8))
	      (insert (format "%6o" chk))
	      (insert 0)
	      (insert ? )
	      (tar-setf (tar-header-checksum tokens) chk)
	      ;;
	      ;; ok, make sure we didn't botch it.
	      (check-tar-header-block-checksum
	        (buffer-substring start (+ start 512))
	        chk (tar-header-name tokens))
	      )))
      (narrow-to-region 1 tar-header-offset))))


Eric S. Raymond's avatar
Eric S. Raymond committed
919 920 921 922 923 924 925 926 927
(defun tar-octal-time (timeval)
  ;; Format a timestamp as 11 octal digits.  Ghod, I hope this works...
  (let ((hibits (car timeval)) (lobits (car (cdr timeval))))
    (insert (format "%05o%01o%05o"
		    (lsh hibits -2)
		    (logior (lsh (logand 3 hibits) 1) (> (logand lobits 32768) 0))
		    (logand 32767 lobits)
		    ))))

Richard M. Stallman's avatar
Richard M. Stallman committed
928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985
(defun tar-subfile-save-buffer ()
  "In tar subfile mode, write this buffer back into its parent tar-file buffer.
This doesn't write anything to disk - you must save the parent tar-file buffer
to make your changes permanent."
  (interactive)
  (if (not (and (boundp 'superior-tar-buffer) superior-tar-buffer))
    (error "this buffer has no superior tar file buffer."))
  (if (not (and (boundp 'superior-tar-descriptor) superior-tar-descriptor))
    (error "this buffer doesn't have an index into its superior tar file!"))
  (save-excursion
  (let ((subfile (current-buffer))
	(subfile-size (buffer-size))
	(descriptor superior-tar-descriptor))
    (set-buffer superior-tar-buffer)
    (let* ((tokens (tar-desc-tokens descriptor))
	   (start (tar-desc-data-start descriptor))
	   (name (tar-header-name tokens))
	   (size (tar-header-size tokens))
	   (size-pad (ash (ash (+ size 511) -9) 9))
	   (head (memq descriptor tar-parse-info))
	   (following-descs (cdr head)))
      (if (not head)
	(error "Can't find this tar file entry in its parent tar file!"))
      (unwind-protect
       (save-excursion
	(widen)
	;; delete the old data...
	(let* ((data-start (+ start tar-header-offset -1))
	       (data-end (+ data-start (ash (ash (+ size 511) -9) 9))))
	  (delete-region data-start data-end)
	  ;; insert the new data...
	  (goto-char data-start)
	  (insert-buffer subfile)
	  ;;
	  ;; pad the new data out to a multiple of 512...
	  (let ((subfile-size-pad (ash (ash (+ subfile-size 511) -9) 9)))
	    (goto-char (+ data-start subfile-size))
	    (insert (make-string (- subfile-size-pad subfile-size) 0))
	    ;;
	    ;; update the data pointer of this and all following files...
	    (tar-setf (tar-header-size tokens) subfile-size)
	    (let ((difference (- subfile-size-pad size-pad)))
	      (tar-dolist (desc following-descs)
		(tar-setf (tar-desc-data-start desc)
			  (+ (tar-desc-data-start desc) difference))))
	    ;;
	    ;; Update the size field in the header block.
	    (let ((header-start (- data-start 512)))
	      (goto-char (+ header-start tar-size-offset))
	      (delete-region (point) (+ (point) 12))
	      (insert (format "%11o" subfile-size))
	      (insert ? )
	      ;;
	      ;; Maybe update the datestamp.
	      (if (not tar-update-datestamp)
		  nil
		(goto-char (+ header-start tar-time-offset))
		(delete-region (point) (+ (point) 12))
Eric S. Raymond's avatar
Eric S. Raymond committed
986
		(insert (tar-octal-time (current-time)))
Richard M. Stallman's avatar
Richard M. Stallman committed
987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122
		(insert ? ))
	      ;;
	      ;; compute a new checksum and insert it.
	      (let ((chk (checksum-tar-header-block
			  (buffer-substring header-start data-start))))
		(goto-char (+ header-start tar-chk-offset))
		(delete-region (point) (+ (point) 8))
		(insert (format "%6o" chk))
		(insert 0)
		(insert ? )
		(tar-setf (tar-header-checksum tokens) chk)))
	    ;;
	    ;; alter the descriptor-line...
	    ;;
	    (let ((position (- (length tar-parse-info) (length head))))
	      (goto-char 1)
	      (next-line position)
	      (beginning-of-line)
	      (let ((p (point))
		    (m (set-marker (make-marker) tar-header-offset)))
		(forward-line 1)
		(delete-region p (point))
		(insert-before-markers (summarize-tar-header-block tokens t) "\n")
		(setq tar-header-offset (marker-position m)))
	      )))
	;; after doing the insertion, add any final padding that may be necessary.
	(tar-pad-to-blocksize))
       (narrow-to-region 1 tar-header-offset)))
    (set-buffer-modified-p t)   ; mark the tar file as modified
    (set-buffer subfile)
    (set-buffer-modified-p nil) ; mark the tar subfile as unmodified
    (message "saved into tar-buffer \"%s\" - remember to save that buffer!"
	     (buffer-name superior-tar-buffer))
    )))


(defun tar-pad-to-blocksize ()
  "If we are being anal about tar file blocksizes, fix up the current buffer.
Leaves the region wide."
  (if (null tar-anal-blocksize)
      nil
    (widen)
    (let* ((last-desc (nth (1- (length tar-parse-info)) tar-parse-info))
	   (start (tar-desc-data-start last-desc))
	   (tokens (tar-desc-tokens last-desc))
	   (link-p (tar-header-link-type tokens))
	   (size (if link-p 0 (tar-header-size tokens)))
	   (data-end (+ start size))
	   (bbytes (ash tar-anal-blocksize 9))
	   (pad-to (+ bbytes (* bbytes (/ (1- data-end) bbytes))))
	   (buffer-read-only nil) ; ##
	   )
      ;; If the padding after the last data is too long, delete some;
      ;; else insert some until we are padded out to the right number of blocks.
      ;;
      (goto-char (+ (or tar-header-offset 0) data-end))
      (if (> (1+ (buffer-size)) (+ (or tar-header-offset 0) pad-to))
	  (delete-region (+ (or tar-header-offset 0) pad-to) (1+ (buffer-size)))
	  (insert (make-string (- (+ (or tar-header-offset 0) pad-to)
				  (1+ (buffer-size)))
			       0)))
      )))


(defun maybe-write-tar-file ()
  "Used as a write-file-hook to write tar-files out correctly."
  ;;
  ;; If the current buffer is in tar-mode and has its header-offset set,
  ;; only write out the part of the file after the header-offset.
  ;;
  (if (and (eq major-mode 'tar-mode)
	   (and (boundp 'tar-header-offset) tar-header-offset))
      (unwind-protect
	(save-excursion
	  (tar-clear-modification-flags)
	  (widen)
	  ;; Doing this here confuses things - the region gets left too wide!
	  ;; I suppose this is run in a context where changing the buffer is bad.
	  ;; (tar-pad-to-blocksize)
	  (write-region tar-header-offset (1+ (buffer-size)) buffer-file-name nil t)
	  ;; return T because we've written the file.
	  t)
	(narrow-to-region 1 tar-header-offset)
	t)
      ;; return NIL because we haven't.
      nil))


;;; Patch it in.

(defvar tar-regexp "\\.tar$"
  "The regular expression used to identify tar file names.")

(setq auto-mode-alist
      (cons (cons tar-regexp 'tar-mode) auto-mode-alist))

(or (boundp 'write-file-hooks) (setq write-file-hooks nil))
(or (listp write-file-hooks)
    (setq write-file-hooks (list write-file-hooks)))
(or (memq 'maybe-write-tar-file write-file-hooks)
    (setq write-file-hooks
	  (cons 'maybe-write-tar-file write-file-hooks)))


;;; This is a hack.  For files ending in .tar, we want -*- lines to be
;;; completely ignored - if there is one, it applies to the first file
;;; in the archive, and not the archive itself!  

(defun tar-normal-mode (&optional find-file)
  "Choose the major mode for this buffer automatically.
Also sets up any specified local variables of the file.
Uses the visited file name, the -*- line, and the local variables spec.

This function is called automatically from `find-file'.  In that case,
if `inhibit-local-variables' is non-`nil' we require confirmation before
processing a local variables spec.  If you run `normal-mode' explicitly,
confirmation is never required.

Note that this version of this function has been hacked to interact
correctly with tar files - when visiting a file which matches
'tar-regexp', the -*- line and local-variables are not examined,
as they would apply to a file within the archive rather than the archive
itself."
  (interactive)
  (if (and buffer-file-name
	   (string-match tar-regexp buffer-file-name))
      (tar-mode)
      (tar-real-normal-mode find-file)))


(if (not (fboundp 'tar-real-normal-mode))
    (fset 'tar-real-normal-mode (symbol-function 'normal-mode)))
(fset 'normal-mode 'tar-normal-mode)

(provide 'tar-mode)

Eric S. Raymond's avatar
Eric S. Raymond committed
1123
;;; tar-mode.el ends here