;;; tar-mode.el --- simple editing of tar files from GNU Emacs -*- lexical-binding:t -*-
;; Copyright (C) 1990-1991, 1993-2024 Free Software Foundation, Inc.
;; Author: Jamie Zawinski <jwz@lucid.com>
;; Maintainer: emacs-devel@gnu.org
;; Created: 04 Apr 1990
;; Keywords: unix
;; 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
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) 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. If not, see <https://www.gnu.org/licenses/>.
;;; Commentary:
;; 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.
;; This code now understands the extra fields that GNU tar adds to tar files.
;; 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 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.
;; Rationale:
;; Why does tar-mode edit the file itself instead of using tar?
;; That means that you can edit tar files which you don't have room for
;; on your local disk.
;; I don't know about recent features in gnu tar, but old versions of tar
;; can't replace a file in the middle of a tar file with a new version.
;; Tar-mode can. I don't think tar can do things like chmod the subfiles.
;; An implementation which involved unpacking and repacking the file into
;; some scratch directory would be very wasteful, and wouldn't be able to
;; preserve the file owners.
;;; Bugs:
;; - Rename on ././@LongLink files
;; - Revert confirmation displays the raw data temporarily.
;;; Code:
(eval-when-compile (require 'cl-lib))
(require 'arc-mode)
(defgroup tar nil
"Simple editing of tar files."
:prefix "tar-"
:group 'data)
(defcustom 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."
:type '(choice integer (const nil)))
(defcustom tar-update-datestamp nil
"Non-nil means 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
the file never exists on disk."
:type 'boolean)
(defcustom tar-mode-show-date nil
"Non-nil means Tar mode should show the date/time of each subfile.
This information is useful, but it takes screen space away from file names."
:type 'boolean)
(defcustom tar-copy-preserve-time nil
"Non-nil means that Tar mode preserves the timestamp when copying files."
:type 'boolean
:version "27.1")
(defvar tar-parse-info nil)
(defvar tar-superior-buffer nil
"Buffer containing the tar archive from which a member was extracted.")
(defvar tar-superior-descriptor nil
"Tar descriptor for a member extracted from an archive.")
(defvar tar-file-name-coding-system nil)
(put 'tar-superior-buffer 'permanent-local t)
(put 'tar-superior-descriptor 'permanent-local t)
;; The Tar data is made up of bytes and better manipulated as bytes
;; and can be very large, so insert/delete can be costly. The summary we
;; want to display may contain non-ascii chars, of course, so we'd like it
;; to be multibyte. We used to keep both in the same buffer and switch
;; from/to uni/multibyte. But this had several downsides:
;; - set-buffer-multibyte has an O(N^2) worst case that tends to be triggered
;; here, so it gets atrociously slow on large Tar files.
;; - need to widen/narrow the buffer to show/hide the raw data, and need to
;; maintain a tar-header-offset that keeps track of the boundary between
;; the two.
;; - can't use markers because they're not preserved by set-buffer-multibyte.
;; So instead, we now keep the two pieces of data in separate buffers, and
;; use the new buffer-swap-text primitive when we need to change which data
;; is associated with "the" buffer.
(defvar-local tar-data-buffer nil
"Buffer that holds the actual raw tar bytes.")
(defvar-local tar-data-swapped nil
"If non-nil, `tar-data-buffer' indeed holds raw tar bytes.")
(defun tar-data-swapped-p ()
"Return non-nil if the tar-data is in `tar-data-buffer'."
(and (buffer-live-p tar-data-buffer)
;; Sanity check to try and make sure tar-data-swapped tracks the swap
;; state correctly: the raw data is expected to be always larger than
;; the summary.
(progn
(cl-assert (or (= (buffer-size tar-data-buffer) (buffer-size))
(eq tar-data-swapped
(> (buffer-size tar-data-buffer) (buffer-size)))))
tar-data-swapped)))
(defun tar-swap-data ()
"Swap buffer contents between current buffer and `tar-data-buffer'.
Preserve the modified states of the buffers and set `tar-data-swapped'."
(let ((data-buffer-modified-p (buffer-modified-p tar-data-buffer))
(current-buffer-modified-p (buffer-modified-p)))
(buffer-swap-text tar-data-buffer)
(setq tar-data-swapped (not tar-data-swapped))
(restore-buffer-modified-p data-buffer-modified-p)
(with-current-buffer tar-data-buffer
(restore-buffer-modified-p current-buffer-modified-p))))
;;; down to business.
(cl-defstruct (tar-header
(:constructor nil)
(:type vector)
:named
(:constructor
make-tar-header (data-start name mode uid gid size date checksum
link-type link-name magic uname gname dmaj dmin)))
data-start name mode uid gid size date checksum link-type link-name
magic uname gname dmaj dmin
;; Start of the header can be nil (meaning it's 512 bytes before data-start)
;; or a marker (in case the header uses LongLink thingies).
header-start)
(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-prefix-offset (+ tar-dmin-offset 8))
(defconst tar-end-offset (+ tar-prefix-offset 155))
(defun tar-roundup-512 (s)
"Round S up to the next multiple of 512."
(ash (ash (+ s 511) -9) 9))
(defun tar-header-block-tokenize (pos coding &optional disable-slash)
"Return a `tar-header' structure.
This is a list of name, mode, uid, gid, size,
write-date, checksum, link-type, and link-name.
CODING is our best guess for decoding non-ASCII file names.
DISABLE-SLASH, if non-nil, means don't decide an entry is a directory
based on the trailing slash, only based on the \"link-type\" field
of the file header. This is used for \"old GNU\" Tar format."
(if (> (+ pos 512) (point-max)) (error "Malformed Tar header"))
(cl-assert (zerop (mod (- pos (point-min)) 512)))
(cl-assert (not enable-multibyte-characters))
(let ((string (buffer-substring pos (setq pos (+ pos 512)))))
(when ;(some 'plusp string) ; <-- oops, massive cycle hog!
(or (not (= 0 (aref string 0))) ; This will do.
(not (= 0 (aref string 101))))
(let* ((name-end 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
;; The magic string is actually 6bytes
;; of magic string plus 2bytes of version
;; which we here ignore.
(- tar-uname-offset 2)))
;; The magic string is "ustar\0" for POSIX format, and
;; "ustar " for GNU Tar's format.
(uname-valid-p (car (member magic-str '("ustar " "ustar\0"))))
name linkname
(nulsexp "[^\000]*\000"))
(when (string-match nulsexp string tar-name-offset)
(setq name-end (min name-end (1- (match-end 0)))))
(when (string-match nulsexp string tar-link-offset)
(setq link-end (min link-end (1- (match-end 0)))))
(when (string-match nulsexp string tar-uname-offset)
(setq uname-end (min uname-end (1- (match-end 0)))))
(when (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)))
(setq linkname (substring string tar-link-offset link-end))
(when (and (equal uname-valid-p "ustar\0")
(string-match nulsexp string tar-prefix-offset)
(> (match-end 0) (1+ tar-prefix-offset)))
(setq name (concat (substring string tar-prefix-offset
(1- (match-end 0)))
"/" name)))
(setq name
(decode-coding-string name coding)
linkname
(decode-coding-string linkname coding))
(if (and (null link-p) (null disable-slash) (string-match "/\\'" name))
(setq link-p 5)) ; directory
(if (and (equal name "././@LongLink")
;; Supposedly @LongLink is only used for GNUTAR
;; format (i.e. "ustar ") but some POSIX Tar files
;; (with "ustar\0") have been seen using it as well.
(member magic-str '("ustar " "ustar\0")))
;; This is a GNU Tar long-file-name header.
(let* ((size (tar-parse-octal-integer
string tar-size-offset tar-time-offset))
;; The long name is in the next 512-byte block.
;; We've already moved POS there, when we computed
;; STRING above.
(name (decode-coding-string
;; -1 so as to strip the terminating 0 byte.
(buffer-substring pos (+ pos size -1)) coding))
;; Tokenize the header of the _real_ file entry,
;; which is further 512 bytes into the archive.
(descriptor (tar-header-block-tokenize
(+ pos (tar-roundup-512 size)) coding
;; Don't intuit directories from
;; the trailing slash, because the
;; truncated name might by chance end
;; in a slash.
'ignore-trailing-slash)))
;; Fix the descriptor of the real file entry by using
;; the information from the long name entry.
(cond
((eq link-p (- ?L ?0)) ;GNUTYPE_LONGNAME.
(setf (tar-header-name descriptor) name))
((eq link-p (- ?K ?0)) ;GNUTYPE_LONGLINK.
(setf (tar-header-link-name descriptor) name))
(t
(message "Unrecognized GNU Tar @LongLink format")))
;; Fix the "link-type" attribute, based on the long name.
(if (and (null (tar-header-link-type descriptor))
(string-match "/\\'" name))
(setf (tar-header-link-type descriptor) 5)) ; directory
(setf (tar-header-header-start descriptor)
(copy-marker (- pos 512) t))
descriptor)
(make-tar-header
(copy-marker pos nil)
name
(tar-parse-octal-integer string tar-mode-offset tar-uid-offset)
(tar-parse-octal-integer string tar-uid-offset tar-gid-offset)
(tar-parse-octal-integer string tar-gid-offset tar-size-offset)
(tar-parse-octal-integer string tar-size-offset tar-time-offset)
(tar-parse-octal-integer string tar-time-offset tar-chk-offset)
(tar-parse-octal-integer string tar-chk-offset tar-linkp-offset)
link-p
linkname
uname-valid-p
(when uname-valid-p
(decode-coding-string
(substring string tar-uname-offset uname-end) coding))
(when uname-valid-p
(decode-coding-string
(substring string tar-gname-offset gname-end) coding))
(tar-parse-octal-integer string tar-dmaj-offset tar-dmin-offset)
(tar-parse-octal-integer string tar-dmin-offset tar-prefix-offset)
))))))
;; Pseudo-field.
(defun tar-header-data-end (descriptor)
(let* ((data-start (tar-header-data-start descriptor))
(link-type (tar-header-link-type descriptor))
(size (tar-header-size descriptor)))
(+ data-start
;; Ignore size for files of type 1-6
(if (and (not (memq link-type '(1 2 3 4 5 6))) (> size 0))
(tar-roundup-512 size)
0))))
(defun tar-parse-octal-integer (string &optional start end)
(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) ?0)))
start (1+ start)))
n)))
(define-obsolete-function-alias 'tar-parse-octal-long-integer
#'tar-parse-octal-integer "27.1")
(defun tar-parse-octal-integer-safe (string)
(if (zerop (length string)) (error "Empty string"))
(mapc (lambda (c)
(if (or (< c ?0) (> c ?7))
(error "`%c' is not an octal digit" c)))
string)
(tar-parse-octal-integer string))
(defun tar-new-regular-file-header (filename &optional size time)
"Return a Tar header for a regular file.
The header will lack a proper checksum; use `tar-header-block-checksum'
to compute one, or request `tar-header-serialize' to do that.
Other `tar-mode' facilities may also require the data-start header
field to be set to a valid value.
If SIZE is not given or nil, it defaults to 0.
If TIME is not given or nil, assume now."
(make-tar-header
nil
filename
#o644 0 0 (or size 0)
(or time (current-time))
nil ; checksum
nil nil
nil nil nil nil nil))
(defun tar--pad-to (pos)
(make-string (+ pos (- (point)) (point-min)) 0))
(defun tar--put-at (pos val &optional fmt mask)
(when val
(insert (tar--pad-to pos)
(if fmt
(format fmt (if mask (logand mask val) val))
val))))
(defun tar-header-serialize (header &optional update-checksum)
"Return the serialization of a Tar HEADER as a string.
This function calls `tar-header-block-check-checksum' to ensure the
checksum is correct.
If UPDATE-CHECKSUM is non-nil, update HEADER with the newly-computed
checksum before doing the check."
(with-temp-buffer
(set-buffer-multibyte nil)
(let ((encoded-name
(encode-coding-string (tar-header-name header)
tar-file-name-coding-system)))
(unless (< (length encoded-name) 99)
;; FIXME: Implement it.
(error "Long file name support is not implemented"))
(insert encoded-name))
(tar--put-at tar-mode-offset (tar-header-mode header) "%6o\0 " #o777777)
(tar--put-at tar-uid-offset (tar-header-uid header) "%6o\0 " #o777777)
(tar--put-at tar-gid-offset (tar-header-gid header) "%6o\0 " #o777777)
(tar--put-at tar-size-offset (tar-header-size header) "%11o ")
(insert (tar--pad-to tar-time-offset)
(tar-octal-time (tar-header-date header))
" ")
;; Omit tar-header-checksum (tar-chk-offset) for now.
(tar--put-at tar-linkp-offset (tar-header-link-type header))
(tar--put-at tar-link-offset (tar-header-link-name header))
(when (tar-header-magic header)
(tar--put-at tar-magic-offset (tar-header-magic header))
(tar--put-at tar-uname-offset (tar-header-uname header))
(tar--put-at tar-gname-offset (tar-header-gname header))
(tar--put-at tar-dmaj-offset (tar-header-dmaj header) "%7o\0" #o7777777)
(tar--put-at tar-dmin-offset (tar-header-dmin header) "%7o\0" #o7777777))
(tar--put-at 512 "")
(let ((ck (tar-header-block-checksum (buffer-string))))
(goto-char (+ (point-min) tar-chk-offset))
(delete-char 8)
(insert (format "%6o\0 " ck))
(when update-checksum
(setf (tar-header-checksum header) ck))
(tar-header-block-check-checksum (buffer-string)
(tar-header-checksum header)
(tar-header-name header)))
;; .
(buffer-string)))
(defun tar-header-block-checksum (string)
"Compute and return a tar-acceptable checksum for this block."
(cl-assert (not (multibyte-string-p string)))
(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 tar-header-block-check-checksum (hblock desired-checksum file-name)
"Beep and print a warning if the checksum doesn't match."
(if (not (= desired-checksum (tar-header-block-checksum hblock)))
(progn (beep) (message "Invalid checksum for file %s!" file-name))))
(defun tar-clip-time-string (time)
(declare (obsolete format-time-string "27.1"))
(let ((system-time-locale "C"))
(format-time-string " %b %e %H:%M %Y" time)))
(defun tar-grind-file-mode (mode)
"Construct a `rw-r--r--' string indicating MODE.
MODE should be an integer which is a file mode value.
For instance, if mode is #o700, then it produces `rwx------'."
(declare (obsolete file-modes-number-to-symbolic "28.1"))
(substring (file-modes-number-to-symbolic mode) 1))
(defun tar-header-block-summarize (tar-hblock &optional mod-p)
"Return 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))
(type (tar-header-link-type tar-hblock))
(link-name (tar-header-link-name tar-hblock)))
(format "%c%s %7s/%-7s %7s%s %s%s"
(if mod-p ?* ? )
(file-modes-number-to-symbolic
mode
(cond ((or (eq type nil) (eq type 0)) ?-)
((eq type 1) ?h) ; link
((eq type 2) ?l) ; 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 28) ?L) ; next has longname
((eq type 29) ?M) ; multivolume continuation
((eq type 35) ?S) ; sparse
((eq type 38) ?V) ; volume header
((eq type 55) ?H) ; pax global extended header
((eq type 72) ?X) ; pax extended header
(t ?\s)
))
(if (= 0 (length uname)) uid uname)
(if (= 0 (length gname)) gid gname)
size
(if tar-mode-show-date
(format-time-string " %Y-%m-%d %H:%M" time)
"")
(propertize name
'mouse-face 'highlight
'help-echo "mouse-2: extract this file into a buffer")
(if (or (eq type 1) (eq type 2))
(concat (if (= type 1) " ==> " " --> ") link-name)
""))))
(defun tar-untar-buffer ()
"Extract all archive members in the tar-file into the current directory."
(interactive)
;; FIXME: make it work even if we're not in tar-mode.
(let ((data-buf (if (tar-data-swapped-p) tar-data-buffer
(current-buffer)))
(reporter (make-progress-reporter "Extracting")))
(with-current-buffer data-buf
(cl-assert (not enable-multibyte-characters)))
(dolist (descriptor tar-parse-info)
(let* ((orig (tar-header-name descriptor))
;; Note that default-directory may have different values
;; in the tar-mode and data buffers, so we stick to the
;; absolute file name from now on.
(name (expand-file-name orig))
(dir (if (eq (tar-header-link-type descriptor) 5)
name
(file-name-directory name)))
(link-desc (tar--describe-as-link descriptor))
(start (tar-header-data-start descriptor))
(end (+ start (tar-header-size descriptor))))
(unless (file-directory-p name)
(progress-reporter-update reporter name)
(if (and dir (not (file-exists-p dir)))
(make-directory dir t))
(unless (file-directory-p name)
(with-current-buffer data-buf
(let ((coding-system-for-write 'no-conversion)
(write-region-inhibit-fsync t))
(when link-desc
(lwarn '(tar link) :warning
"Extracted `%s', %s, as a normal file"
name link-desc))
(write-region start end name nil :nomessage)))
(set-file-modes name (tar-header-mode descriptor))))))
(progress-reporter-done reporter)))
(defun tar-summarize-buffer ()
"Parse the contents of the tar file in the current buffer."
(cl-assert (tar-data-swapped-p))
(let* ((modified (buffer-modified-p))
(result '())
(pos (point-min))
(coding tar-file-name-coding-system)
(progress-reporter
(with-current-buffer tar-data-buffer
(make-progress-reporter "Parsing tar file..."
(point-min) (point-max))))
descriptor)
(with-current-buffer tar-data-buffer
(while (and (< pos (point-max))
(setq descriptor (tar-header-block-tokenize pos coding)))
(let ((size (tar-header-size descriptor)))
(if (< size 0)
(error "%s has size %s - corrupted"
(tar-header-name descriptor) size)))
;;
;; This is just too slow. Don't really need it anyway....
;;(tar-header-block-check-checksum
;; hblock (tar-header-block-checksum hblock)
;; (tar-header-name descriptor))
(push descriptor result)
(setq pos (tar-header-data-end descriptor))
(progress-reporter-update progress-reporter pos)))
(setq-local tar-parse-info (nreverse result))
;; A tar file should end with a block or two of nulls,
;; but let's not get a fatal error if it doesn't.
(if (null descriptor)
(progress-reporter-done progress-reporter)
(message "Warning: premature EOF parsing tar file"))
(goto-char (point-min))
(let ((create-lockfiles nil) ; avoid changing dir mtime by lock_file
(inhibit-read-only t)
(total-summaries
(mapconcat #'tar-header-block-summarize tar-parse-info "\n")))
(insert total-summaries "\n")
(goto-char (point-min))
(restore-buffer-modified-p modified))))
(defvar-keymap tar-mode-map
:doc "Local keymap for Tar mode listings."
:full t :suppress t
"SPC" #'tar-next-line
"C" #'tar-copy
"d" #'tar-flag-deleted
"C-d" #'tar-flag-deleted
"e" #'tar-extract
"f" #'tar-extract
"RET" #'tar-extract
"g" #'revert-buffer
"n" #'tar-next-line
"C-n" #'tar-next-line
"<down>" #'tar-next-line
"o" #'tar-extract-other-window
"p" #'tar-previous-line
"C-p" #'tar-previous-line
"<up>" #'tar-previous-line
"I" #'tar-new-entry
"R" #'tar-rename-entry
"u" #'tar-unflag
"v" #'tar-view
"w" #'woman-tar-extract-file
"x" #'tar-expunge
"DEL" #'tar-unflag-backwards
"E" #'tar-extract-other-window
"M" #'tar-chmod-entry
"G" #'tar-chgrp-entry
"O" #'tar-chown-entry
;; Let mouse-1 follow the link.
"<follow-link>" 'mouse-face
"<mouse-2>" #'tar-mouse-extract
;; Get rid of the Edit menu bar item to save space.
"<menu-bar> <edit>" #'undefined)
(easy-menu-define tar-mode-immediate-menu tar-mode-map
"Immediate menu for Tar mode."
'("Immediate"
["Find This File" tar-extract]
["Find in Other Window" tar-extract-other-window]
["Display in Other Window" tar-display-other-window]
["View This File" tar-view]
["Read Man Page (WoMan)" woman-tar-extract-file]))
(easy-menu-define tar-mode-mark-menu tar-mode-map
"Mark menu for Tar mode."
'("Mark"
["Unflag" tar-unflag]
["Flag" tar-flag-deleted]
["Unmark All" tar-clear-modification-flags]))
(easy-menu-define tar-mode-operate-menu tar-mode-map
"Operate menu for Tar mode."
'("Operate"
["Expunge Marked Files" tar-expunge]
["Copy to..." tar-copy]
["Rename to..." tar-rename-entry]
["Change Mode..." tar-chmod-entry]
["Change Group..." tar-chgrp-entry]
["Change Owner..." 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-change-major-mode-hook ()
;; Bring the actual Tar data back into the main buffer.
(when (tar-data-swapped-p) (tar-swap-data))
;; Throw away the summary.
(when (buffer-live-p tar-data-buffer) (kill-buffer tar-data-buffer)))
(defun tar-mode-kill-buffer-hook ()
(if (buffer-live-p tar-data-buffer) (kill-buffer tar-data-buffer)))
;;;###autoload
(define-derived-mode tar-mode special-mode "Tar"
"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.\\<tar-mode-map>
Type \\[tar-extract] to pull a file out of the tar file and into its own buffer;
or click mouse-2 on the file's line in the Tar mode buffer.
Type \\[tar-copy] 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 \\[tar-extract] command) and
save it with \\[save-buffer], 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}"
(and buffer-file-name
(file-writable-p buffer-file-name)
(setq buffer-read-only nil)) ; undo what `special-mode' did
(make-local-variable 'tar-parse-info)
(setq-local require-final-newline nil) ; binary data, dude...
(setq-local local-enable-local-variables nil)
(setq-local next-line-add-newlines nil)
(setq-local tar-file-name-coding-system
(or file-name-coding-system
default-file-name-coding-system
locale-coding-system))
;; Prevent loss of data when saving the file.
(setq-local file-precious-flag t)
(buffer-disable-undo)
(widen)
;; Now move the Tar data into an auxiliary buffer, so we can use the main
;; buffer for the summary.
(cl-assert (not (tar-data-swapped-p)))
(setq-local revert-buffer-function #'tar-mode-revert)
;; We started using write-contents-functions, but this hook is not
;; used during auto-save, so we now use
;; write-region-annotate-functions which hooks at a lower-level.
(add-hook 'write-region-annotate-functions #'tar-write-region-annotate nil t)
(add-hook 'kill-buffer-hook #'tar-mode-kill-buffer-hook nil t)
(add-hook 'change-major-mode-hook #'tar-change-major-mode-hook nil t)
;; Tar data is made of bytes, not chars.
(set-buffer-multibyte nil) ;Hopefully a no-op.
(setq-local tar-data-buffer (generate-new-buffer
(format " *tar-data %s*"
(file-name-nondirectory
(or buffer-file-name (buffer-name))))))
(condition-case err
(progn
(tar-swap-data)
(tar-summarize-buffer)
(tar-next-line 0))
(error
;; If summarizing caused an error, then maybe the buffer doesn't contain
;; tar data. Rather than show a mysterious empty buffer, let's
;; revert to fundamental-mode.
(fundamental-mode)
(signal (car err) (cdr err)))))
(autoload 'woman-tar-extract-file "woman"
"In tar mode, run the WoMan man-page browser on this file." t)
(define-minor-mode tar-subfile-mode
"Minor mode for editing an element of a tar-file.
This mode arranges for \"saving\" this buffer to write the data
into the tar-file buffer that it came from. The changes will
actually appear on disk when you save the tar-file's buffer."
;; Don't do this, because it is redundant and wastes mode line space.
;; :lighter " TarFile"
:lighter nil
(or (and (boundp 'tar-superior-buffer) tar-superior-buffer)
(error "This buffer is not an element of a tar file"))
(cond (tar-subfile-mode
(add-hook 'write-file-functions #'tar-subfile-save-buffer nil t)
;; turn off auto-save.
(auto-save-mode -1)
(setq buffer-auto-save-file-name nil))
(t
(remove-hook 'write-file-functions #'tar-subfile-save-buffer t))))
;; Revert the buffer and recompute the dired-like listing.
(defun tar-mode-revert (&optional no-auto-save no-confirm)
(unwind-protect
(let ((revert-buffer-function nil))
(if (tar-data-swapped-p) (tar-swap-data))
;; FIXME: If we ask for confirmation, the user will be temporarily
;; looking at the raw data.
(revert-buffer no-auto-save no-confirm 'preserve-modes)
;; Recompute the summary.
(if (buffer-live-p tar-data-buffer) (kill-buffer tar-data-buffer))
(tar-mode))
(unless (tar-data-swapped-p) (tar-swap-data))))
(defun tar-next-line (arg)
"Move cursor vertically down ARG lines and to the start of the filename."
(interactive "p")
(forward-line arg)
(goto-char (or (next-single-property-change (point) 'mouse-face) (point))))
(defun tar-previous-line (arg)
"Move cursor vertically up ARG lines and to the start of the filename."
(interactive "p")
(tar-next-line (- arg)))
(defun tar-current-position ()
"Return the `tar-parse-info' index for the current line."
(count-lines (point-min) (line-beginning-position)))
(defun tar-current-descriptor (&optional noerror)
"Return the tar-descriptor of the current line, or signals an error."
;; I wish lines had plists, like in ZMACS...
(or (nth (tar-current-position)
tar-parse-info)
(if noerror
nil
(error "This line does not describe a tar-file entry"))))
(defun tar--describe-as-link (descriptor)
(let ((link-p (tar-header-link-type descriptor)))
(if link-p
(cond ((eq link-p 5) "a directory")
((eq link-p 20) "a tar directory header")
((eq link-p 28) "a next has longname")
((eq link-p 29) "a multivolume-continuation")
((eq link-p 35) "a sparse entry")
((eq link-p 38) "a volume header")
((eq link-p 55) "a pax global extended header")
((eq link-p 72) "a pax extended header")
(t "a link")))))
(defun tar--check-descriptor (descriptor)
(let ((link-desc (tar--describe-as-link descriptor)))
(when link-desc
(error "This is %s, not a real file" link-desc))))
(defun tar-get-descriptor ()
(let* ((descriptor (tar-current-descriptor))
(size (tar-header-size descriptor)))
(tar--check-descriptor descriptor)
(if (zerop size) (message "This is a zero-length file"))
descriptor))
(defun tar-get-file-descriptor (file)
;; Used by package.el.
(let ((desc ()))
(dolist (hdr tar-parse-info)
(when (equal file (tar-header-name hdr))
(setq desc hdr)))
(tar--check-descriptor desc)
desc))
(defun tar-mouse-extract (event)
"Extract a file whose tar directory line you click on."
(interactive "e")
(with-current-buffer (window-buffer (posn-window (event-end event)))
(save-excursion
(goto-char (posn-point (event-end event)))
;; Just make sure this doesn't get an error.
(tar-get-descriptor)))
(select-window (posn-window (event-end event)))
(goto-char (posn-point (event-end event)))
(tar-extract))
(defun tar-file-name-handler (op &rest args)
"Helper function for `tar-extract'."
(or (eq op 'file-exists-p)
(let ((file-name-handler-alist nil))
(apply op args))))
(defun tar--extract (descriptor)
"Extract this entry of the tar file into its own buffer."
(let* ((name (tar-header-name descriptor))
(size (tar-header-size descriptor))
(start (tar-header-data-start descriptor))
(end (+ start size))
(tarname (buffer-name))
(bufname (concat (file-name-nondirectory name)
" ("
tarname
")"))
(buffer (generate-new-buffer bufname)))
(with-current-buffer tar-data-buffer
(let (coding)
(narrow-to-region start end)
(goto-char start)
(setq coding (or coding-system-for-read
(and set-auto-coding-function
(funcall set-auto-coding-function
name (- end start)))
;; The following binding causes
;; find-buffer-file-type-coding-system
;; (defined on dos-w32.el) to act as if
;; the file being extracted existed, so
;; that the file's contents' encoding and
;; EOL format are auto-detected.
(let ((file-name-handler-alist
'(("" . tar-file-name-handler))))
(car (find-operation-coding-system
'insert-file-contents
(cons name (current-buffer)) t)))))
(if (or (not coding)
(eq (coding-system-type coding) 'undecided))
(setq coding (detect-coding-region start end t)))
(if (coding-system-get coding :for-unibyte)
(with-current-buffer buffer
(set-buffer-multibyte nil)))
(widen)
(with-current-buffer buffer
(setq buffer-undo-list t))
(decode-coding-region start end coding buffer)
(with-current-buffer buffer
(setq buffer-undo-list nil))))
buffer))
(defun tar-goto-file (file)
"Go to FILE in the current buffer.
FILE should be a relative file name. If FILE can't be found,
return nil. Otherwise point is returned."
(let ((start (point))
found)
(goto-char (point-min))
(while (and (not found)
(not (eobp)))
(forward-line 1)
(when-let ((descriptor (ignore-errors (tar-get-descriptor))))
(when (equal (tar-header-name descriptor) file)
(setq found t))))
(if (not found)
(progn
(goto-char start)
nil)
(point))))
(defun tar-next-file-displayer (file regexp n)
"Return a closure to display the next file after FILE that matches REGEXP."
(let ((short (replace-regexp-in-string "\\`.*!" "" file))
next)
;; The tar buffer chops off leading "./", so do the same
;; here.
(setq short (replace-regexp-in-string "\\`\\./" "" file))
(tar-goto-file short)
(while (and (not next)
;; Stop if we reach the end/start of the buffer.
(if (> n 0)
(not (eobp))
(not (save-excursion
(beginning-of-line)
(bobp)))))
(tar-next-line n)
(when-let ((descriptor (ignore-errors (tar-get-descriptor))))
(let ((candidate (tar-header-name descriptor))
(buffer (current-buffer)))
(when (and candidate
(string-match-p regexp candidate))
(setq next (lambda ()
(kill-buffer (current-buffer))
(switch-to-buffer buffer)
(tar-extract)))))))
(unless next
;; If we didn't find a next/prev file, then restore
;; point.
(tar-goto-file short))
next))
(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-get-descriptor))
(name (tar-header-name descriptor))
(tar-buffer (current-buffer))
(tarname (buffer-name))
(read-only-p (or buffer-read-only view-p))
(new-buffer-file-name (expand-file-name
;; `:' is not allowed on Windows
(concat tarname "!"
(if (string-search "/" name)
name
;; Make sure `name' contains a /
;; so set-auto-mode doesn't try
;; to look at `tarname' for hints.
(concat "./" name)))))
(buffer (get-file-buffer new-buffer-file-name))
(just-created nil))
(unless buffer
(setq buffer (tar--extract descriptor))
(setq just-created t)
(with-current-buffer buffer
(goto-char (point-min))
(setq buffer-file-name new-buffer-file-name)
(setq buffer-file-truename
(abbreviate-file-name buffer-file-name))
(archive-try-jka-compr) ;Pretty ugly hack :-(
;; Force buffer-file-coding-system to what
;; decode-coding-region actually used.
(set-buffer-file-coding-system last-coding-system-used t)
;; Set the default-directory to the dir of the
;; superior buffer.
(setq default-directory
(with-current-buffer tar-buffer
default-directory))
(set-buffer-modified-p nil)
(normal-mode) ; pick a mode.
(setq-local tar-superior-buffer tar-buffer)
(setq-local tar-superior-descriptor descriptor)
(setq buffer-read-only read-only-p)
(tar-subfile-mode 1)))
(cond
(view-p
(view-buffer buffer (and just-created 'kill-buffer-if-not-modified)))
((eq other-window-p 'display) (display-buffer buffer))
(other-window-p (switch-to-buffer-other-window buffer))
(t (switch-to-buffer buffer)))))
(defun tar-extract-other-window ()
"In Tar mode, find this entry of the tar file in another window."
(interactive)
(tar-extract t))
(defun tar-display-other-window ()
"In Tar mode, display this entry of the tar file in another window."
(interactive)
(tar-extract 'display))
(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)
"Read a file name with this line's entry as the default."
(or prompt (setq prompt "Copy to: "))
(let* ((default-file (expand-file-name
(tar-header-name (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.
If `tar-copy-preserve-time' is non-nil, the original
timestamp (if present in the tar file) will be used on the
extracted file."
(interactive (list (tar-read-file-name)))
(let* ((descriptor (tar-get-descriptor))
(name (tar-header-name descriptor))
(size (tar-header-size descriptor))
(date (tar-header-date descriptor))
(start (tar-header-data-start descriptor))
(end (+ start size))
(inhibit-file-name-handlers inhibit-file-name-handlers)
(inhibit-file-name-operation inhibit-file-name-operation))
(with-current-buffer
(if (tar-data-swapped-p) tar-data-buffer (current-buffer))
;; Inhibit compressing a subfile again if *both* name and
;; to-file are handled by jka-compr
(if (and (eq (find-file-name-handler name 'write-region)
'jka-compr-handler)
(eq (find-file-name-handler to-file 'write-region)
'jka-compr-handler))
(setq inhibit-file-name-handlers
(cons 'jka-compr-handler
(and (eq inhibit-file-name-operation 'write-region)
inhibit-file-name-handlers))
inhibit-file-name-operation 'write-region))
(let ((coding-system-for-write 'no-conversion))
(write-region start end to-file nil nil nil t))
(when (and tar-copy-preserve-time
date)
(set-file-times to-file date 'nofollow)))
(message "Copied tar entry %s to %s" name to-file)))
(defun tar-new-entry (filename &optional index)
"Insert a new empty regular file before point."
(interactive "*sFile name: ")
(let* ((index (or index (tar-current-position)))
(d-list (and (not (zerop index))
(nthcdr (+ -1 index) tar-parse-info)))
(pos (if d-list
(tar-header-data-end (car d-list))
(point-min)))
(new-descriptor
(tar-new-regular-file-header filename)))
;; Update the data buffer; fill the missing descriptor fields.
(with-current-buffer tar-data-buffer
(goto-char pos)
(insert (tar-header-serialize new-descriptor t))
(setf (tar-header-data-start new-descriptor)
(copy-marker (point) nil)))
;; Update tar-parse-info.
(if d-list
(setcdr d-list (cons new-descriptor (cdr d-list)))
(setq tar-parse-info (cons new-descriptor tar-parse-info)))
;; Update the listing buffer.
(save-excursion
(goto-char (point-min))
(forward-line index)
(let ((inhibit-read-only t))
(insert (tar-header-block-summarize new-descriptor) ?\n)))
;; .
index))
(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)
(dotimes (_ (abs 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)))
;;
;; delete the current line...
(delete-region (line-beginning-position) (line-beginning-position 2))
;;
;; delete the data pointer...
(setq tar-parse-info (delq descriptor tar-parse-info))
;;
;; delete the data from inside the file...
(with-current-buffer tar-data-buffer
(delete-region (or (tar-header-header-start descriptor)
(- (tar-header-data-start descriptor) 512))
(tar-header-data-end descriptor)))))
(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 (point-min))
(while (not (eobp))
(if (= (following-char) ?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))
(if (zerop n)
(message "Nothing to expunge.")
(message "%s files expunged. Be sure to save this buffer." n)))))
(defun tar-clear-modification-flags ()
"Remove the stars at the beginning of each line."
(interactive)
(save-excursion
(goto-char (point-min))
(while (not (eobp))
(if (not (eq (following-char) ?\s))
(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 ((descriptor (tar-current-descriptor)))
(if (or current-prefix-arg
(not (tar-header-magic descriptor)))
(read-number
"New UID number: "
(format "%s" (tar-header-uid descriptor)))
(read-string "New UID string: " (tar-header-uname descriptor))))))
(cond ((stringp new-uid)
(setf (tar-header-uname (tar-current-descriptor)) new-uid)
(tar-alter-one-field tar-uname-offset
(concat (encode-coding-string
new-uid tar-file-name-coding-system)
"\000")))
(t
(setf (tar-header-uid (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 ((descriptor (tar-current-descriptor)))
(if (or current-prefix-arg
(not (tar-header-magic descriptor)))
(read-number
"New GID number: "
(format "%s" (tar-header-gid descriptor)))
(read-string "New GID string: " (tar-header-gname descriptor))))))
(cond ((stringp new-gid)
(setf (tar-header-gname (tar-current-descriptor)) new-gid)
(tar-alter-one-field tar-gname-offset
(concat (encode-coding-string
new-gid tar-file-name-coding-system)
"\000")))
(t
(setf (tar-header-gid (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-current-descriptor)))))
(if (string= "" new-name) (error "Zero length name"))
(let ((encoded-new-name (encode-coding-string new-name
tar-file-name-coding-system))
(descriptor (tar-current-descriptor))
(prefix nil))
(when (tar-header-header-start descriptor)
;; FIXME: Make it work for ././@LongLink.
(error "Rename with @LongLink format is not implemented"))
(when (and (> (length encoded-new-name) 98)
(string-match "/" encoded-new-name
(- (length encoded-new-name) 99))
(< (match-beginning 0) 155))
(unless (equal (tar-header-magic descriptor) "ustar\0")
(tar-alter-one-field tar-magic-offset (concat "ustar\0" "00")))
(setq prefix (substring encoded-new-name 0 (match-beginning 0)))
(setq encoded-new-name (substring encoded-new-name (match-end 0))))
(if (> (length encoded-new-name) 98) (error "Name too long"))
(setf (tar-header-name descriptor) new-name)
(tar-alter-one-field 0
(substring (concat encoded-new-name (make-string 99 0)) 0 99))
(if prefix
(tar-alter-one-field tar-prefix-offset
(substring (concat prefix (make-string 155 0)) 0 155)))))
(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): "))))
(setf (tar-header-mode (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 &optional descriptor)
(unless descriptor (setq descriptor (tar-current-descriptor)))
;;
;; update the header-line.
(let ((col (current-column)))
(delete-region (line-beginning-position)
(prog2 (forward-line 1)
(point)
;; Insert the new text after the old, before deleting,
;; to preserve markers such as the window start.
(insert (tar-header-block-summarize descriptor) "\n")))
(forward-line -1) (move-to-column col))
(cl-assert (tar-data-swapped-p))
(with-current-buffer tar-data-buffer
(let* ((start (- (tar-header-data-start descriptor) 512)))
;;
;; delete the old field and insert a new one.
(goto-char (+ start data-position))
(delete-region (point) (+ (point) (length new-data-string))) ; <--
(cl-assert (not (or enable-multibyte-characters
(multibyte-string-p new-data-string))))
(insert new-data-string)
;;
;; compute a new checksum and insert it.
(let ((chk (tar-header-block-checksum
(buffer-substring start (+ start 512)))))
(goto-char (+ start tar-chk-offset))
(delete-region (point) (+ (point) 8))
(insert (format "%6o\0 " chk))
(setf (tar-header-checksum descriptor) chk)
;;
;; ok, make sure we didn't botch it.
(tar-header-block-check-checksum
(buffer-substring start (+ start 512))
chk (tar-header-name descriptor))
))))
(defun tar-octal-time (timeval)
;; Format a timestamp as 11 octal digits.
(format "%011o" (time-convert timeval 'integer)))
(defun tar-subfile-save-buffer ()
"In tar subfile mode, save this buffer 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 'tar-superior-buffer) tar-superior-buffer))
(error "This buffer has no superior tar file buffer"))
(if (not (and (boundp 'tar-superior-descriptor) tar-superior-descriptor))
(error "This buffer doesn't have an index into its superior tar file!"))
(unless (buffer-live-p tar-superior-buffer)
(error "The tar buffer no longer exists; can't save"))
(let ((subfile (current-buffer))
(coding buffer-file-coding-system)
(descriptor tar-superior-descriptor)
subfile-size)
(with-current-buffer tar-superior-buffer
(let* ((start (tar-header-data-start descriptor))
(size (tar-header-size descriptor))
(head (memq descriptor tar-parse-info)))
(if (not head)
(error "Can't find this tar file entry in its parent tar file!"))
(with-current-buffer tar-data-buffer
;; delete the old data...
(let* ((data-start start)
(data-end (+ data-start (tar-roundup-512 size))))
(narrow-to-region data-start data-end)
(delete-region (point-min) (point-max))
;; insert the new data...
(goto-char data-start)
(let ((dest (current-buffer)))
(with-current-buffer subfile
(save-restriction
(widen)
(encode-coding-region (point-min) (point-max) coding dest))))
(setq subfile-size (- (point-max) (point-min)))
;;
;; pad the new data out to a multiple of 512...
(let ((subfile-size-pad (tar-roundup-512 subfile-size)))
(goto-char (point-max))
(insert (make-string (- subfile-size-pad subfile-size) 0))
;;
;; update the data of this files...
(setf (tar-header-size descriptor) subfile-size)
;;
;; Update the size field in the header block.
(widen))))
;;
;; alter the descriptor-line and header
;;
(let ((position (- (length tar-parse-info) (length head))))
(goto-char (point-min))
(forward-line position)
(tar-alter-one-field tar-size-offset (format "%11o " subfile-size))
;;
;; Maybe update the datestamp.
(when tar-update-datestamp
(tar-alter-one-field tar-time-offset
(concat (tar-octal-time nil) " "))))
;; After doing the insertion, add any necessary final padding.
(tar-pad-to-blocksize))
(set-buffer-modified-p t) ; mark the tar file as modified
(tar-next-line 0))
(set-buffer-modified-p nil) ; mark the tar subfile as unmodified
(message "Saved into tar-buffer `%s'. Be sure to save that buffer!"
(buffer-name tar-superior-buffer))
;; Prevent basic-save-buffer from changing our coding-system.
(setq last-coding-system-used buffer-file-coding-system)
;; Prevent ordinary saving from happening.
t))
;; When this function is called, it is sure that the buffer is unibyte.
(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
(let* ((last-desc (nth (1- (length tar-parse-info)) tar-parse-info))
(start (tar-header-data-start last-desc))
(link-p (tar-header-link-type last-desc))
(size (if link-p 0 (tar-header-size last-desc)))
(data-end (+ start size))
(bbytes (ash tar-anal-blocksize 9))
(pad-to (+ bbytes (* bbytes (/ (- data-end (point-min)) bbytes)))))
;; 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.
;;
(with-current-buffer tar-data-buffer
(let ((goal-end (+ (point-min) pad-to)))
(if (> (point-max) goal-end)
(delete-region goal-end (point-max))
(goto-char (point-max))
(insert (make-string (- goal-end (point-max)) ?\0))))))))
;; Used in write-region-annotate-functions to write tar-files out correctly.
(defun tar-write-region-annotate (start _end)
;; When called from write-file (and auto-save), `start' is nil.
;; When called from M-x write-region, we assume the user wants to save
;; (part of) the summary, not the tar data.
(unless (or start (not (tar-data-swapped-p)))
(tar-clear-modification-flags)
(set-buffer tar-data-buffer)
nil))
(provide 'tar-mode)
;;; tar-mode.el ends here