Fix save with adjustment.

superfluous checks to vlf-verify-size when saving.  Fix vlf-revert not
to ask unnecessary.

.gitignore

@@ -0,0 +1,2 @@
+*.elc
+*~

README.org

@@ -1,22 +1,121 @@
-* View Large Files Improved
+* View Large Files
 
-An Emacs mode that allows viewing files in chunks.  This is a fork
-that builds on the bare bones GNU ELPA vlf.el.  It adds the following
-improvements:
+Emacs minor mode that allows viewing, editing and searching large
+files in batches.  Batch size can be adjusted on the fly and bounds
+the memory that is to be used for operations on the file.
+
+This is development version of the GNU ELPA [[http://elpa.gnu.org/packages/vlf][vlf.el]] package.  Here's
+what it does in a nutshell:
 
 - regular expression search on whole file (in constant memory
   determined by current batch size)
 - chunk editing (if size has changed, saving is done in constant
   memory determined by current batch size)
+- occur like indexing
 - options to jump to beginning, end or arbitrary file chunk
 - ability to jump/insert given number of batches at once
 - newly added content is acknowledged if file has changed size
   meanwhile
-- vlfi is added as an option when opening large files
+- automatic scrolling of batches
+- as VLF is minor mode, font locking and functionality of the
+  respective major mode is also present
+- VLF is added as an option when opening large files
 
-* Known issues
+GNU Emacs 23 and 24 are supported.
 
-- When chunk starts with only part of multi-byte character, encoding
-  for this chunk is clobbered visibly, don't edit/save in such case.
-  Workaround is to move back to the first non-clobbered chunk and
-  enlarge batch size until this chunk comes into range.
+* Overview and tips
+
+M-x vlf PATH-TO-FILE
+
+** Unicode
+
+Emacs' Unicode support is leveraged so you'll not see bare bytes but
+characters decoded as if file is normally opened.  This holds for
+editing, search and indexing.
+
+** 32-bit GNU Emacs
+
+Regular Emacs integers are used, so if you use 32-bit Emacs without
+bignum support and have really huge file (with size beyond the maximum
+integer value), VLF will probably not quite work.
+
+** Memory control
+
+*vlf-batch-size* bounds the memory used for all operations.
+
+* Detail usage
+
+** Applicability
+
+You can control when vlf-mode is invoked or offered as choice with the
+*vlf-application* customization option.  By default it will offer VLF
+when opening large files.  There are also options to never use it (you
+can still call *vlf* command explicitly); to use it without asking for
+large files or to invoke it on all files.  Here's example setup such
+that vlf-mode automatically launches for large files:
+
+#+BEGIN_EXAMPLE
+(custom-set-variables
+ '(vlf-application 'dont-ask))
+#+END_EXAMPLE
+
+** Keymap
+
+All VLF operations are grouped under the *C-c C-v* prefix by default.
+Here's example how to add another prefix (*C-x v*):
+
+#+BEGIN_EXAMPLE
+(eval-after-load "vlf"
+  '(define-key vlf-prefix-map "\C-xv" vlf-mode-map))
+#+END_EXAMPLE
+
+** Control batch size
+
+*C-c C-v +* and *C-c C-v -* control current batch size by factors
+of 2.
+
+You can also set by hand local variable *vlf-batch-size* and then
+refresh with *C-c C-v g*.
+
+** Move around
+
+*C-c C-v n* and *C-c C-v p* move batch by batch.  With positive
+prefix argument they move prefix number of batches.  With negative -
+append prefix number of batches.
+
+*C-c C-v SPC* displays batch starting from current point.
+
+*C-c C-v [* and *C-c C-v ]* take you to the beginning and end of file
+respectively.
+
+*C-c C-v j* jumps to given chunk.  To see where you are in file and
+how many chunks there are (using the current batch size), look at the
+parenthesized part of the buffer name, batch size is also indicated at
+the end.
+
+** Search whole file
+
+*C-c C-v s* and *C-c C-v r* search forward and backward respectively
+over the whole file.  This is done batch by batch so if you have
+really huge file - you'd better set somewhat bigger batch size
+beforehand.
+
+** Occur over whole file
+
+*C-c C-v o* builds index for given regular expression just like
+*M-x occur*.  It does this batch by batch over the whole file.  Note
+that even if you prematurely stop it with *C-g*, it will still show
+index of what's found so far.
+
+** Jump to line
+
+*C-c C-v l* jumps to given line in file.  This is done by searching
+from the beginning, so again the bigger current batch size, the
+quicker.  With negative argument, lines are counted from the end of
+file.
+
+** Edit and save
+
+If editing doesn't change size of the chunk, only this chunk is saved.
+Otherwise the remaining part of the file is adjusted batch by batch,
+so again you'd better have bigger current batch size.

vlfi.el

@@ -1,563 +0,0 @@
-;;; vlfi.el --- View Large Files Improved  -*- lexical-binding: t -*-
-
-;; Copyright (C) 2006, 2012, 2013  Free Software Foundation, Inc.
-
-;; Version: 0.6
-;; Keywords: large files, utilities
-;; Authors: 2006 Mathias Dahl <mathias.dahl@gmail.com>
-;;          2012 Sam Steingold <sds@gnu.org>
-;;          2013 Andrey Kotlarski <m00naticus@gmail.com>
-
-;; This file 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 2, or (at your option)
-;; any later version.
-
-;; This file 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, Inc., 59 Temple Place - Suite 330,
-;; Boston, MA 02111-1307, USA.
-
-;;; Commentary:
-
-;; This package provides the M-x vlfi command, which visits part of a
-;; large file in a read-only buffer without visiting the entire file.
-;; The buffer uses VLFI mode, which defines several commands for
-;; moving around, searching and editing selected chunk of file.
-
-;; This package is an improved fork of the vlf.el package.
-
-;;; Code:
-
-(defgroup vlfi nil
-  "View Large Files in Emacs."
-  :prefix "vlfi-"
-  :group 'files)
-
-(defcustom vlfi-batch-size 1024
-  "Defines how large each batch of file data is (in bytes)."
-  :type 'integer
-  :group 'vlfi)
-
-;;; Keep track of file position.
-(defvar vlfi-start-pos 0
-  "Absolute position of the visible chunk start.")
-(defvar vlfi-end-pos vlfi-batch-size
-  "Absolute position of the visible chunk end.")
-(defvar vlfi-file-size 0 "Total size of presented file.")
-
-(defvar vlfi-mode-map
-  (let ((map (make-sparse-keymap)))
-    (define-key map [M-next] 'vlfi-next-batch)
-    (define-key map [M-prior] 'vlfi-prev-batch)
-    (define-key map "+" 'vlfi-change-batch-size)
-    (define-key map "-"
-      (lambda () "Decrease vlfi batch size by factor of 2."
-        (interactive)
-        (vlfi-change-batch-size t)))
-    (define-key map "s" 'vlfi-re-search-forward)
-    (define-key map "r" 'vlfi-re-search-backward)
-    (define-key map "[" 'vlfi-beginning-of-file)
-    (define-key map "]" 'vlfi-end-of-file)
-    (define-key map "e" 'vlfi-edit-mode)
-    (define-key map "j" 'vlfi-jump-to-chunk)
-    map)
-  "Keymap for `vlfi-mode'.")
-
-(define-derived-mode vlfi-mode special-mode "VLFI"
-  "Mode to browse large files in."
-  (setq buffer-read-only t)
-  (set-buffer-modified-p nil)
-  (buffer-disable-undo)
-  (add-hook 'write-contents-functions 'vlfi-write)
-  (setq revert-buffer-function 'vlfi-revert)
-  (make-local-variable 'vlfi-batch-size)
-  (put 'vlfi-batch-size 'permanent-local t)
-  (make-local-variable 'vlfi-start-pos)
-  (put 'vlfi-start-pos 'permanent-local t)
-  (make-local-variable 'vlfi-end-pos)
-  (put 'vlfi-end-pos 'permanent-local t)
-  (make-local-variable 'vlfi-file-size)
-  (put 'vlfi-file-size 'permanent-local t))
-
-;;;###autoload
-(defun vlfi (file &optional from-end)
-  "View Large FILE.  With FROM-END prefix, view from the back.
-Batches of the file data from FILE will be displayed in a read-only
-buffer.  You can customize number of bytes displayed by customizing
-`vlfi-batch-size'."
-  (interactive "fFile to open: \nP")
-  (with-current-buffer (generate-new-buffer "*vlfi*")
-    (setq buffer-file-name file
-          vlfi-file-size (nth 7 (file-attributes file)))
-    (vlfi-insert-file from-end)
-    (vlfi-mode)
-    (switch-to-buffer (current-buffer))))
-
-;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
-;;; integration with other packages
-
-;;;###autoload
-(defun dired-vlfi (from-end)
-  "In Dired, visit the file on this line in VLFI mode.
-With FROM-END prefix, view from the back."
-  (interactive "P")
-  (vlfi (dired-get-file-for-visit) from-end))
-
-;;;###autoload
-(eval-after-load "dired"
-  '(define-key dired-mode-map "V" 'dired-vlfi))
-
-;;;###autoload
-(defun vlfi-if-file-too-large (size op-type &optional filename)
-  "If file SIZE larger than `large-file-warning-threshold', \
-allow user to view file with `vlfi', open it normally or abort.
-OP-TYPE specifies the file operation being performed over FILENAME."
-  (and large-file-warning-threshold size
-       (> size large-file-warning-threshold)
-       (let ((char nil))
-         (while (not (memq (setq char
-                                 (read-event
-                                  (propertize
-                                   (format
-                                    "File %s is large (%s): \
-%s normally (o), %s with vlfi (v) or abort (a)"
-                                    (if filename
-                                        (file-name-nondirectory filename)
-                                      "")
-                                    (file-size-human-readable size)
-                                    op-type op-type)
-                                   'face 'minibuffer-prompt)))
-                           '(?o ?O ?v ?V ?a ?A))))
-         (cond ((memq char '(?o ?O)))
-               ((memq char '(?v ?V))
-                (vlfi filename nil)
-                (error ""))
-               ((memq char '(?a ?A))
-                (error "Aborted"))))))
-
-;; hijack `abort-if-file-too-large'
-;;;###autoload
-(fset 'abort-if-file-too-large 'vlfi-if-file-too-large)
-
-;; non recent Emacs
-(unless (fboundp 'file-size-human-readable)
-  (defun file-size-human-readable (file-size)
-    "Print FILE-SIZE in MB."
-    (format "%.1fMB" (/ file-size 1024.0))))
-
-;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
-;;; utilities
-
-(defun vlfi-change-batch-size (decrease)
-  "Change the buffer-local value of `vlfi-batch-size'.
-Normally, the value is doubled;
-with the prefix argument DECREASE it is halved."
-  (interactive "P")
-  (or (assq 'vlfi-batch-size (buffer-local-variables))
-      (error "%s is not local in this buffer" 'vlfi-batch-size))
-  (setq vlfi-batch-size (if decrease
-                            (/ vlfi-batch-size 2)
-                          (* vlfi-batch-size 2)))
-  (vlfi-move-to-batch vlfi-start-pos))
-
-(defun vlfi-format-buffer-name ()
-  "Return format for vlfi buffer name."
-  (format "%s(%s)[%d/%d](%d)"
-          (file-name-nondirectory buffer-file-name)
-          (file-size-human-readable vlfi-file-size)
-          (/ vlfi-end-pos vlfi-batch-size)
-          (/ vlfi-file-size vlfi-batch-size)
-          vlfi-batch-size))
-
-(defun vlfi-update-buffer-name ()
-  "Update the current buffer name."
-  (rename-buffer (vlfi-format-buffer-name) t))
-
-(defun vlfi-insert-file (&optional from-end)
-  "Insert first chunk of current file contents in current buffer.
-With FROM-END prefix, start from the back."
-  (if from-end
-      (setq vlfi-start-pos (max 0 (- vlfi-file-size vlfi-batch-size))
-            vlfi-end-pos vlfi-file-size)
-    (setq vlfi-start-pos 0
-          vlfi-end-pos (min vlfi-batch-size vlfi-file-size)))
-  (vlfi-move-to-chunk vlfi-start-pos vlfi-end-pos))
-
-(defun vlfi-beginning-of-file ()
-  "Jump to beginning of file content."
-  (interactive)
-  (vlfi-insert-file))
-
-(defun vlfi-end-of-file ()
-  "Jump to end of file content."
-  (interactive)
-  (vlfi-insert-file t))
-
-(defun vlfi-revert (&rest args)
-  "Revert current chunk.  Ignore ARGS."
-  (ignore args)
-  (vlfi-move-to-chunk vlfi-start-pos vlfi-end-pos))
-
-(defun vlfi-jump-to-chunk (n)
-  "Go to to chunk N."
-  (interactive "nGoto to chunk: ")
-  (vlfi-move-to-batch (* (1- n) vlfi-batch-size)))
-
-;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
-;;; batch movement
-
-(defun vlfi-next-batch (append)
-  "Display the next batch of file data.
-When prefix argument is supplied and positive
- jump over APPEND number of batches.
-When prefix argument is negative
- append next APPEND number of batches to the existing buffer."
-  (interactive "p")
-  (let ((end (+ vlfi-end-pos (* vlfi-batch-size
-                                (abs append)))))
-    (when (< vlfi-file-size end)        ; re-check file size
-      (setq vlfi-file-size (nth 7 (file-attributes buffer-file-name)))
-      (cond ((= vlfi-end-pos vlfi-file-size)
-             (error "Already at EOF"))
-            ((< vlfi-file-size end)
-             (setq end vlfi-file-size))))
-    (let ((inhibit-read-only t)
-          (do-append (< append 0))
-          (pos (point)))
-      (if do-append
-          (goto-char (point-max))
-        (setq vlfi-start-pos (- end vlfi-batch-size))
-        (erase-buffer))
-      (insert-file-contents buffer-file-name nil (if do-append
-                                                     vlfi-end-pos
-                                                   vlfi-start-pos)
-                            end)
-      (goto-char pos))
-    (setq vlfi-end-pos end))
-  (set-visited-file-modtime)
-  (set-buffer-modified-p nil)
-  (vlfi-update-buffer-name))
-
-(defun vlfi-prev-batch (prepend)
-  "Display the previous batch of file data.
-When prefix argument is supplied and positive
- jump over PREPEND number of batches.
-When prefix argument is negative
- append previous PREPEND number of batches to the existing buffer."
-  (interactive "p")
-  (if (zerop vlfi-start-pos)
-      (error "Already at BOF"))
-  (let ((inhibit-read-only t)
-        (start (max 0 (- vlfi-start-pos (* vlfi-batch-size
-                                           (abs prepend)))))
-        (do-prepend (< prepend 0))
-        (pos (- (point-max) (point))))
-    (if do-prepend
-        (goto-char (point-min))
-      (setq vlfi-end-pos (+ start vlfi-batch-size))
-      (erase-buffer))
-    (insert-file-contents buffer-file-name nil start
-                          (if do-prepend
-                              vlfi-start-pos
-                            vlfi-end-pos))
-    (goto-char (- (point-max) pos))
-    (setq vlfi-start-pos start))
-  (set-visited-file-modtime)
-  (set-buffer-modified-p nil)
-  (vlfi-update-buffer-name))
-
-(defun vlfi-move-to-batch (start)
-  "Move to batch determined by START.
-Adjust according to file start/end and show `vlfi-batch-size' bytes."
-  (setq vlfi-start-pos (max 0 start)
-        vlfi-end-pos (+ vlfi-start-pos vlfi-batch-size))
-  (if (< vlfi-file-size vlfi-end-pos)   ; re-check file size
-      (setq vlfi-file-size
-            (nth 7 (file-attributes buffer-file-name))
-            vlfi-end-pos (min vlfi-end-pos vlfi-file-size)
-            vlfi-start-pos (max 0 (- vlfi-end-pos vlfi-batch-size))))
-  (let ((inhibit-read-only t)
-        (pos (point)))
-    (erase-buffer)
-    (insert-file-contents buffer-file-name nil
-                          vlfi-start-pos vlfi-end-pos)
-    (goto-char pos))
-  (set-visited-file-modtime)
-  (set-buffer-modified-p nil)
-  (vlfi-update-buffer-name))
-
-(defun vlfi-move-to-chunk (start end)
-  "Move to chunk determined by START END."
-  (if (< vlfi-file-size end)            ; re-check file size
-      (setq vlfi-file-size (nth 7
-                                (file-attributes buffer-file-name))))
-  (setq vlfi-start-pos (max 0 start)
-        vlfi-end-pos (min end vlfi-file-size))
-  (let ((inhibit-read-only t)
-        (pos (point)))
-    (erase-buffer)
-    (insert-file-contents buffer-file-name nil
-                          vlfi-start-pos vlfi-end-pos)
-    (goto-char pos))
-  (set-visited-file-modtime)
-  (set-buffer-modified-p nil)
-  (vlfi-update-buffer-name))
-
-;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
-;;; search
-
-(defun vlfi-re-search (regexp count backward)
-  "Search for REGEXP COUNT number of times forward or BACKWARD."
-  (let* ((match-start-pos (+ vlfi-start-pos (point)))
-         (match-end-pos match-start-pos)
-         (to-find count)
-         (search-reporter (make-progress-reporter
-                           (concat "Searching for " regexp)
-                           (if backward
-                               (- vlfi-file-size vlfi-end-pos)
-                             vlfi-start-pos)
-                           vlfi-file-size))
-         (batch-step (/ vlfi-batch-size 8))) ; amount of chunk overlap
-    (unwind-protect
-        (catch 'end-of-file
-          (if backward
-              (while (not (zerop to-find))
-                (cond ((re-search-backward regexp nil t)
-                       (setq to-find (1- to-find)
-                             match-start-pos (+ vlfi-start-pos
-                                                (match-beginning 0))
-                             match-end-pos (+ vlfi-start-pos
-                                              (match-end 0))))
-                      ((zerop vlfi-start-pos)
-                       (throw 'end-of-file nil))
-                      (t (let ((batch-move (- vlfi-start-pos
-                                              (- vlfi-batch-size
-                                                 batch-step))))
-                           (vlfi-move-to-batch
-                            (if (< match-start-pos batch-move)
-                                (- match-start-pos vlfi-batch-size)
-                              batch-move)))
-                         (goto-char (if (< match-start-pos
-                                           vlfi-end-pos)
-                                        (- match-start-pos
-                                           vlfi-start-pos)
-                                      (point-max)))
-                         (progress-reporter-update search-reporter
-                                                   vlfi-start-pos))))
-            (while (not (zerop to-find))
-              (cond ((re-search-forward regexp nil t)
-                     (setq to-find (1- to-find)
-                           match-start-pos (+ vlfi-start-pos
-                                              (match-beginning 0))
-                           match-end-pos (+ vlfi-start-pos
-                                            (match-end 0))))
-                    ((= vlfi-end-pos vlfi-file-size)
-                     (throw 'end-of-file nil))
-                    (t (let ((batch-move (- vlfi-end-pos batch-step)))
-                         (vlfi-move-to-batch
-                          (if (< batch-move match-end-pos)
-                              match-end-pos
-                            batch-move)))
-                       (goto-char (if (< vlfi-start-pos match-end-pos)
-                                      (- match-end-pos vlfi-start-pos)
-                                    (point-min)))
-                       (progress-reporter-update search-reporter
-                                                 vlfi-end-pos)))))
-          (progress-reporter-done search-reporter))
-      (if backward
-          (vlfi-goto-match match-end-pos match-start-pos
-                           count to-find)
-        (vlfi-goto-match match-start-pos match-end-pos
-                         count to-find)))))
-
-(defun vlfi-goto-match (match-pos-start match-pos-end count to-find)
-  "Move to chunk surrounding MATCH-POS-START and MATCH-POS-END.
-According to COUNT and left TO-FIND, show if search has been
-successful.  Return nil if nothing found."
-  (let ((success (zerop to-find)))
-    (or success
-        (vlfi-move-to-batch (- match-pos-start
-                               (/ vlfi-batch-size 2))))
-    (let* ((match-end (- match-pos-end vlfi-start-pos))
-           (overlay (make-overlay (- match-pos-start vlfi-start-pos)
-                                  match-end)))
-      (overlay-put overlay 'face 'region)
-      (or success (goto-char match-end))
-      (prog1 (cond (success t)
-                   ((< to-find count)
-                    (message "Moved to the %d match which is last"
-                             (- count to-find))
-                    t)
-                   (t (message "Not found")
-                      nil))
-        (sit-for 0.1)
-        (delete-overlay overlay)))))
-
-(defun vlfi-re-search-forward (regexp count)
-  "Search forward for REGEXP prefix COUNT number of times.
-Search is performed chunk by chunk in `vlfi-batch-size' memory."
-  (interactive (list (read-regexp "Search whole file"
-                                  (if regexp-history
-                                      (car regexp-history))
-                                  'regexp-history)
-                     (or current-prefix-arg 1)))
-  (vlfi-re-search regexp count nil))
-
-(defun vlfi-re-search-backward (regexp count)
-  "Search backward for REGEXP prefix COUNT number of times.
-Search is performed chunk by chunk in `vlfi-batch-size' memory."
-  (interactive (list (read-regexp "Search whole file backward"
-                                  (if regexp-history
-                                      (car regexp-history))
-                                  'regexp-history)
-                     (or current-prefix-arg 1)))
-  (vlfi-re-search regexp count t))
-
-;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
-;;; editing
-
-(defvar vlfi-edit-mode-map
-  (let ((map (make-sparse-keymap)))
-    (set-keymap-parent map text-mode-map)
-    (define-key map "\C-c\C-c" 'vlfi-write)
-    (define-key map "\C-c\C-q" 'vlfi-discard-edit)
-    map)
-  "Keymap for command `vlfi-edit-mode'.")
-
-(define-derived-mode vlfi-edit-mode vlfi-mode "VLFI[edit]"
-  "Major mode for editing large file chunks."
-  (setq buffer-read-only nil)
-  (buffer-enable-undo)
-  (message (substitute-command-keys
-            "Editing: Type \\[vlfi-write] to write chunk \
-or \\[vlfi-discard-edit] to discard changes.")))
-
-(defun vlfi-discard-edit ()
-  "Discard edit and refresh chunk from file."
-  (interactive)
-  (vlfi-move-to-chunk vlfi-start-pos vlfi-end-pos)
-  (vlfi-mode)
-  (message "Switched to VLFI mode."))
-
-;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
-;;; saving
-
-(defun vlfi-write ()
-  "Write current chunk to file.  Always return true to disable save.
-If changing size of chunk shift remaining file content."
-  (interactive)
-  (when (and (derived-mode-p 'vlfi-mode)
-             (buffer-modified-p)
-             (or (verify-visited-file-modtime)
-                 (y-or-n-p "File has changed since visited or saved.  \
-Save anyway? ")))
-    (let ((size-change (- vlfi-end-pos vlfi-start-pos
-                          (length (encode-coding-region
-                                   (point-min) (point-max)
-                                   buffer-file-coding-system t))))
-          (pos (point)))
-      (cond ((zerop size-change)
-             (write-region nil nil buffer-file-name vlfi-start-pos t))
-            ((< 0 size-change)
-             (vlfi-file-shift-back size-change))
-            (t (vlfi-file-shift-forward (- size-change))))
-      (goto-char pos))
-    (vlfi-move-to-chunk vlfi-start-pos vlfi-end-pos)
-    (vlfi-mode)
-    t))
-
-(defun vlfi-file-shift-back (size-change)
-  "Shift file contents SIZE-CHANGE bytes back."
-  (let ((coding-system buffer-file-coding-system))
-    (write-region nil nil buffer-file-name vlfi-start-pos t)
-    (setq buffer-file-coding-system nil)
-    (let ((read-start-pos vlfi-end-pos)
-          (reporter (make-progress-reporter "Adjusting file content"
-                                            vlfi-end-pos
-                                            vlfi-file-size)))
-      (while (vlfi-shift-batch read-start-pos (- read-start-pos
-                                                 size-change))
-        (setq read-start-pos (+ read-start-pos vlfi-batch-size))
-        (progress-reporter-update reporter read-start-pos))
-      ;; pad end with space
-      (erase-buffer)
-      (insert-char 32 size-change)
-      (write-region nil nil buffer-file-name (- vlfi-file-size
-                                                size-change) t)
-      (progress-reporter-done reporter))
-    (setq buffer-file-coding-system coding-system)))
-
-(defun vlfi-shift-batch (read-pos write-pos)
-  "Read `vlfi-batch-size' bytes from READ-POS and write them \
-back at WRITE-POS.  Return nil if EOF is reached, t otherwise."
-  (erase-buffer)
-  (setq vlfi-file-size (nth 7 (file-attributes buffer-file-name)))
-  (let ((read-end (+ read-pos vlfi-batch-size)))
-    (insert-file-contents-literally buffer-file-name nil
-                                    read-pos
-                                    (min vlfi-file-size read-end))
-    (write-region nil nil buffer-file-name write-pos t)
-    (< read-end vlfi-file-size)))
-
-(defun vlfi-file-shift-forward (size-change)
-  "Shift file contents SIZE-CHANGE bytes forward.
-Done by saving content up front and then writing previous batch."
-  (let ((vlfi-buffer (current-buffer))
-        (temp-buffer (generate-new-buffer (concat " "
-                                                  (buffer-name))))
-        (coding-system buffer-file-coding-system))
-    (let ((file buffer-file-name))
-      (set-buffer temp-buffer)
-      (setq buffer-file-name file))
-    (set-buffer vlfi-buffer)
-    (let ((read-buffer temp-buffer)
-          (write-buffer vlfi-buffer)
-          (size (+ vlfi-batch-size size-change))
-          (read-pos vlfi-end-pos)
-          (write-pos vlfi-start-pos)
-          swap-buffer
-          (reporter (make-progress-reporter "Adjusting file content"
-                                            vlfi-start-pos
-                                            vlfi-file-size)))
-      (while (vlfi-shift-batches size read-buffer read-pos
-                                 write-buffer write-pos)
-        (setq swap-buffer read-buffer
-              read-buffer write-buffer
-              write-buffer swap-buffer
-              write-pos (+ read-pos size-change)
-              read-pos (+ read-pos size))
-        (progress-reporter-update reporter write-pos))
-      (progress-reporter-done reporter))
-    (kill-buffer temp-buffer)
-    (set-buffer vlfi-buffer)
-    (setq buffer-file-coding-system coding-system)))
-
-(defun vlfi-shift-batches (size read-buffer read-pos
-                                write-buffer write-pos)
-  "Read SIZE bytes in READ-BUFFER starting from READ-POS.
-Then write contents of WRITE-BUFFER to buffer file at WRITE-POS.
-Return nil if EOF is reached, t otherwise."
-  (let* ((file-size (nth 7 (file-attributes buffer-file-name)))
-         (read-more (< read-pos file-size)))
-    (when read-more
-      ;; read
-      (set-buffer read-buffer)
-      (erase-buffer)
-      (setq buffer-file-coding-system nil)
-      (insert-file-contents-literally buffer-file-name nil read-pos
-                                      (min file-size (+ read-pos
-                                                        size))))
-    ;; write
-    (set-buffer write-buffer)
-    (write-region nil nil buffer-file-name write-pos t)
-    read-more))
-
-(provide 'vlfi)
-
-;;; vlfi.el ends here