Package: emacs;
Reported by: Ivan Shmakov <ivan <at> siamics.net>
Date: Thu, 4 Dec 2014 21:19:02 UTC
Severity: wishlist
Tags: patch
Fixed in version 25.1
Done: Ivan Shmakov <ivan <at> siamics.net>
Bug is archived. No further changes may be made.
Message #17 received at 19274 <at> debbugs.gnu.org (full text, mbox):
From: Ivan Shmakov <ivan <at> siamics.net> To: 19274 <at> debbugs.gnu.org Subject: Re: bug#19274: tar-mode.el: allow for adding new archive members Date: Sat, 06 Dec 2014 19:17:16 +0000
[Message part 1 (text/plain, inline)]
>>>>> Stefan Monnier <monnier <at> iro.umontreal.ca> writes: Please consider the revised patch MIMEd. * tar-mode.el: Allow for adding new archive members. (tar-new-regular-file-header, tar--pad-to, tar--put-at) (tar-header-serialize): New functions. (tar-current-position): Split from tar-current-descriptor. (tar-current-descriptor): Use it. (tar-new-entry): New command. (tar-mode-map): Bind it. […] >> BTW, I wonder if it makes sense to split the make-tar-header form >> (with all the nil’s there) off tar-new-entry into a new >> (tar-new-regular-file-header filename &optional size time) function? (Done.) >> I guess that’d ease the creation of Tar archives from Emacs Lisp >> code; (and I already imagine some uses to that.) > BTW, if you're interested in hacking on tar-mode, I keep dreaming of > plugging it into file-name-handler-alist so you can just visit > /foo/bar.tar.gz/somefile, use dired on it, ... I’m not all that familiar with file-name-handler-alist, but I guess I could check it out. (Although at this point I’m simply interested in creating Tar archives from the contents of Emacs buffers, – without having them saved into files, that is.) Curiously, what would be the sensible behavior for Emacs when the copy of the Tar archive kept in the *tar-data* buffer happens to differ to the on-disk state of the respective file? -- FSF associate member #7257 np. Вселенская большая любовь — Гражданская Оборона
[Message part 2 (text/diff, inline)]
--- a/etc/NEWS 2014-11-27 11:36:08 +0000
+++ b/etc/NEWS 2014-12-06 19:03:35 +0000
@@ -340,6 +340,9 @@
`tildify-ignored-environments-alist' variables (as well as a few
helper functions) obsolete.
+** tar-mode: new `tar-new-entry' command, allowing for new members to
+be added to the archive.
+
** Obsolete packages
---
--- a/lisp/tar-mode.el 2014-08-28 19:18:24 +0000
+++ b/lisp/tar-mode.el 2014-12-06 19:04:02 +0000
@@ -50,9 +50,6 @@
;;
;; 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 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.
@@ -369,6 +366,83 @@ write-date, checksum, link-type, and link-name."
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)
+ (when val
+ (insert (tar--pad-to pos) 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.
+
+When 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))
+ (insert (tar--pad-to tar-mode-offset)
+ (format "%6o\0 " (logand #o777777 (tar-header-mode header)))
+ (format "%6o\0 " (logand #o777777 (tar-header-uid header)))
+ (format "%6o\0 " (logand #o777777 (tar-header-gid header))))
+ (insert (tar--pad-to tar-size-offset)
+ (format "%11o " (tar-header-size header)))
+ (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))
+ (let ((dmaj (tar-header-dmaj header))
+ (dmin (tar-header-dmin header)))
+ (tar--put-at tar-dmaj-offset
+ (and dmaj (format "%7o\0" (logand #o7777777 dmaj))))
+ (tar--put-at tar-dmin-offset
+ (and dmin (format "%7o\0" (logand #o7777777 dmin))))))
+ (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."
@@ -547,6 +621,7 @@ MODE should be an integer which is a file mode value."
(define-key map "p" 'tar-previous-line)
(define-key map "\^P" 'tar-previous-line)
(define-key map [up] 'tar-previous-line)
+ (define-key map "I" 'tar-new-entry)
(define-key map "R" 'tar-rename-entry)
(define-key map "u" 'tar-unflag)
(define-key map "v" 'tar-view)
@@ -731,10 +806,14 @@ tar-file's buffer."
(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 (count-lines (point-min) (line-beginning-position))
+ (or (nth (tar-current-position)
tar-parse-info)
(if noerror
nil
@@ -948,6 +1027,37 @@ the current tar-entry."
(write-region start end to-file nil nil nil t)))
(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* ((buffer (current-buffer))
+ (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."
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