;; View a file with "live" updates as the file grows on disk.
;; Copyright (C) 1991 Dave Gillespie
;; This file is part of GNU Emacs.
;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY. No author or distributor
;; accepts responsibility to anyone for the consequences of using it
;; or for whether it serves any particular purpose or works at all,
;; unless he says so in writing. Refer to the GNU Emacs General Public
;; License for full details.
;; Everyone is granted permission to copy, modify and redistribute
;; GNU Emacs, but only under the conditions described in the
;; GNU Emacs General Public License. A copy of this license is
;; supposed to have been given to you along with GNU Emacs so you
;; can know your rights and responsibilities. It should be in a
;; file named COPYING. Among other things, the copyright notice
;; and this notice must be preserved on all copies.
;; Usage:
;; (autoload 'live-find-file "live" "View a file with \"tail -f\"" t)
;; M-x live-find-file RET filename RET
(defvar live-file-notify t
"*Non-nil to display a message in the echo area if data comes in on a
live file buffer which is not currently displayed.
If Non-nil and not \"t\", actually display the buffer if new data comes in.")
(defvar live-file-mask (concat "^\000\001\002\003\004\005\006\007\010\011"
"\013\015\016\017\020\021\022\023\024\025"
"\026\027\030\031\032\033\034\035\036\037\177")
"*A string of characters to retain in a live file buffer;
all others are discarded. If it begins with \"^\", it is a list of
characters which *should* be discarded.
Default is to discard all control characters except new-line and form-feed.")
(defun live-find-file (filename)
"Read in and display a file with \"live\" updates as the file grows on disk.
This is accomplished using the Unix \"tail -f\" command.
The buffer will remain live until you kill it with \\[kill-buffer].
The buffer is made read-only, and should probably be left that way.
Inside the buffer, hit n to change notification mode, r to re-read, q to kill."
(interactive "fLive find file: ")
(setq filename (expand-file-name filename))
(if (file-directory-p filename)
(error "%s is a directory." filename))
(let ((buf (create-file-buffer filename))
size)
(switch-to-buffer buf)
(fundamental-mode)
(setq major-mode 'live-find-file)
(setq mode-name "Live-Find-File")
(use-local-map (make-sparse-keymap)) ; should set up a real major mode!
(local-set-key "q" "\C-xk\r")
(local-set-key "n" 'Live-file-notify)
(local-set-key "r" 'Live-file-reread)
(local-set-key " " 'scroll-up)
(local-set-key "\177" 'scroll-down)
(local-set-key "?" 'Live-file-help)
(local-set-key "h" 'Live-file-help)
(erase-buffer)
(insert-file-contents filename t)
(setq size (buffer-size))
(live-file-clean-region (point-min) (point-max))
(set-buffer-modified-p nil)
(setq buffer-read-only t)
(goto-char (point-max))
(setq default-directory (file-name-directory filename))
(let* ((process-connection-type nil)
(proc (start-process
"tail" (current-buffer) "tail"
(format "+%dcf" (1+ size))
filename)))
(process-kill-without-query proc)
(set-process-filter proc 'live-file-filter)))
)
(defun Live-file-help ()
(interactive)
(message "Live mode: n=change notification method, q=quit, r=reread")
)
(defun Live-file-notify (flag)
"Control whether to notify on input from live files not visible in a window.
This applies to files created by \\[live-find-file].
Cycles among three options: Notify in echo area, notify by creating a new
window, or don't notify.
Notification mode applies if input arrives for a live file that is not
currently visible. If input arrives for a live file that is visible but
that has been scrolled so that the end is not visible, new input always
notifies in the echo area."
(interactive "P")
(setq live-file-notify
(cond ((null flag)
(or (not live-file-notify)
(and (eq live-file-notify t)
'show)))
((not (integerp flag)) 'show)
((> flag 0) t)))
(message (cond ((eq live-file-notify t) "Notifying in echo area.")
(live-file-notify "Notifying in a new window.")
(t "Not notifying.")))
)
(defun Live-file-reread ()
"Re-read the contents of the current live file from disk.
Live-find-file only checks for new text being appended at the end. This
command re-reads the whole of the file to see if any of it has changed."
(interactive)
(let ((name (buffer-file-name)))
(or name
(error "Buffer is not visiting a file."))
(or (file-readable-p name)
(error "File %s no longer exists." name))
(message "Re-reading %s..." name)
(kill-buffer (current-buffer))
(live-find-file name)
(message "Re-reading %s...done" name))
)
(defun live-file-filter (proc str)
(let* ((oldbuf (current-buffer))
(buf (process-buffer proc))
(win (get-buffer-window buf))
(changed nil))
(unwind-protect
(progn
(set-buffer buf)
(clear-visited-file-modtime)
(let ((pt (point-max))
(opt (and (< (point) (point-max)) (point)))
(mod (buffer-modified-p)))
(goto-char pt)
(let ((buffer-read-only nil))
(insert str)
(live-file-clean-region pt (point-max)))
(setq changed (/= pt (point-max)))
(and changed
(or (not win)
(not (pos-visible-in-window-p pt win)))
(or win (eq live-file-notify t))
(= (minibuffer-depth) 0)
(message "From %s: %s"
(file-name-nondirectory
(buffer-file-name buf))
str))
(or mod
(set-buffer-modified-p nil))
(or opt (setq opt (point-max)))
(goto-char opt)
(and win (set-window-point win opt))))
(set-buffer oldbuf))
(and changed
live-file-notify
(not (eq live-file-notify t))
(not (get-buffer-window buf))
(set-window-point (display-buffer buf t)
(save-excursion (set-buffer buf)
(goto-char (point-max))
(point)))))
)
(defun live-file-clean-region (start end)
(and live-file-mask
(save-excursion
(goto-char end)
(while (progn
(skip-chars-backward live-file-mask start)
(> (point) start))
(delete-backward-char 1))))
)