emacs-lock.el 3.9 KB
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;;; emacs-lock.el --- prevents you from exiting Emacs if a buffer is locked
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;; Copyright (C) 1994, 1997, 2001-2011 Free Software Foundation, Inc
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;; Author: Tom Wurgler <twurgler@goodyear.com>
;; Created: 12/8/94
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;; Keywords: extensions, processes
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;; This file is part of GNU Emacs.

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;; GNU Emacs is free software: you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.
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;; GNU Emacs is distributed in the hope that it will be useful,
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;; 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.
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;; You should have received a copy of the GNU General Public License
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;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
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;;; Commentary:
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;; This code sets a buffer-local variable to t if toggle-emacs-lock is run,
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;; then if the user attempts to exit Emacs, the locked buffer name will be
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;; displayed and the exit aborted.  This is just a way of protecting
;; yourself from yourself.  For example, if you have a shell running a big
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;; program and exiting Emacs would abort that program, you may want to lock
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;; that buffer, then if you forget about it after a while, you won't
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;; accidentally exit Emacs.  To unlock the buffer, just goto the buffer and
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;; run toggle-emacs-lock again.

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;;; Code:

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(defvar emacs-lock-from-exiting nil
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  "Whether Emacs is locked to prevent exiting.  See `check-emacs-lock'.")
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(make-variable-buffer-local 'emacs-lock-from-exiting)

(defvar emacs-lock-buffer-locked nil
  "Whether a shell or telnet buffer was locked when its process was killed.")
(make-variable-buffer-local 'emacs-lock-buffer-locked)
(put 'emacs-lock-buffer-locked 'permanent-local t)
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(defun check-emacs-lock ()
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  "Check if variable `emacs-lock-from-exiting' is t for any buffer.
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If any locked buffer is found, signal error and display the buffer's name."
  (save-excursion
    (dolist (buffer (buffer-list))
      (set-buffer buffer)
      (when emacs-lock-from-exiting
	(error "Emacs is locked from exit due to buffer: %s" (buffer-name))))))
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(defun toggle-emacs-lock ()
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  "Toggle `emacs-lock-from-exiting' for the current buffer.
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See `check-emacs-lock'."
  (interactive)
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  (setq emacs-lock-from-exiting (not emacs-lock-from-exiting))
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  (if emacs-lock-from-exiting
      (message "Buffer is now locked")
    (message "Buffer is now unlocked")))

(defun emacs-lock-check-buffer-lock ()
  "Check if variable `emacs-lock-from-exiting' is t for a buffer.
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If the buffer is locked, signal error and display its name."
  (when emacs-lock-from-exiting
    (error "Buffer `%s' is locked, can't delete it" (buffer-name))))
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; These next defuns make it so if you exit a shell that is locked,  the lock
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; is shut off for that shell so you can exit Emacs.  Same for telnet.
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; Also, if a shell or a telnet buffer was locked and the process killed,
; turn the lock back on again if the process is restarted.

(defun emacs-lock-shell-sentinel ()
  (set-process-sentinel
   (get-buffer-process (buffer-name)) (function emacs-lock-clear-sentinel)))

(defun emacs-lock-clear-sentinel (proc str)
  (if emacs-lock-from-exiting
      (progn
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	(setq emacs-lock-from-exiting nil)
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	(setq emacs-lock-buffer-locked t)
	(message "Buffer is now unlocked"))
    (setq emacs-lock-buffer-locked nil)))

(defun emacs-lock-was-buffer-locked ()
  (if emacs-lock-buffer-locked
      (setq emacs-lock-from-exiting t)))
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(unless noninteractive
  (add-hook 'kill-emacs-hook 'check-emacs-lock))
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(add-hook 'kill-buffer-hook 'emacs-lock-check-buffer-lock)
(add-hook 'shell-mode-hook 'emacs-lock-was-buffer-locked)
(add-hook 'shell-mode-hook 'emacs-lock-shell-sentinel)
(add-hook 'telnet-mode-hook 'emacs-lock-was-buffer-locked)
(add-hook 'telnet-mode-hook 'emacs-lock-shell-sentinel)

(provide 'emacs-lock)
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;;; emacs-lock.el ends here