lisp/emacs-lock.el

   1 ;;; emacs-lock.el --- prevents you from exiting Emacs if a buffer is locked
   2
   3 ;; Copyright (C) 1994, 1997, 2001-2011 Free Software Foundation, Inc
   4
   5 ;; Author: Tom Wurgler <twurgler@goodyear.com>
   6 ;; Created: 12/8/94
   7 ;; Keywords: extensions, processes
   8
   9 ;; This file is part of GNU Emacs.
  10
  11 ;; GNU Emacs is free software: you can redistribute it and/or modify
  12 ;; it under the terms of the GNU General Public License as published by
  13 ;; the Free Software Foundation, either version 3 of the License, or
  14 ;; (at your option) any later version.
  15
  16 ;; GNU Emacs is distributed in the hope that it will be useful,
  17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 ;; GNU General Public License for more details.
  20
  21 ;; You should have received a copy of the GNU General Public License
  22 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  23
  24 ;;; Commentary:
  25
  26 ;; This code sets a buffer-local variable to t if toggle-emacs-lock is run,
  27 ;; then if the user attempts to exit Emacs, the locked buffer name will be
  28 ;; displayed and the exit aborted.  This is just a way of protecting
  29 ;; yourself from yourself.  For example, if you have a shell running a big
  30 ;; program and exiting Emacs would abort that program, you may want to lock
  31 ;; that buffer, then if you forget about it after a while, you won't
  32 ;; accidentally exit Emacs.  To unlock the buffer, just goto the buffer and
  33 ;; run toggle-emacs-lock again.
  34
  35 ;;; Code:
  36
  37 (defvar emacs-lock-from-exiting nil
  38   "Whether Emacs is locked to prevent exiting.  See `check-emacs-lock'.")
  39 (make-variable-buffer-local 'emacs-lock-from-exiting)
  40
  41 (defvar emacs-lock-buffer-locked nil
  42   "Whether a shell or telnet buffer was locked when its process was killed.")
  43 (make-variable-buffer-local 'emacs-lock-buffer-locked)
  44 (put 'emacs-lock-buffer-locked 'permanent-local t)
  45
  46 (defun check-emacs-lock ()
  47   "Check if variable `emacs-lock-from-exiting' is t for any buffer.
  48 If any locked buffer is found, signal error and display the buffer's name."
  49   (save-excursion
  50     (dolist (buffer (buffer-list))
  51       (set-buffer buffer)
  52       (when emacs-lock-from-exiting
  53         (error "Emacs is locked from exit due to buffer: %s" (buffer-name))))))
  54
  55 (defun toggle-emacs-lock ()
  56   "Toggle `emacs-lock-from-exiting' for the current buffer.
  57 See `check-emacs-lock'."
  58   (interactive)
  59   (setq emacs-lock-from-exiting (not emacs-lock-from-exiting))
  60   (if emacs-lock-from-exiting
  61       (message "Buffer is now locked")
  62     (message "Buffer is now unlocked")))
  63
  64 (defun emacs-lock-check-buffer-lock ()
  65   "Check if variable `emacs-lock-from-exiting' is t for a buffer.
  66 If the buffer is locked, signal error and display its name."
  67   (when emacs-lock-from-exiting
  68     (error "Buffer `%s' is locked, can't delete it" (buffer-name))))
  69
  70 ; These next defuns make it so if you exit a shell that is locked,  the lock
  71 ; is shut off for that shell so you can exit Emacs.  Same for telnet.
  72 ; Also, if a shell or a telnet buffer was locked and the process killed,
  73 ; turn the lock back on again if the process is restarted.
  74
  75 (defun emacs-lock-shell-sentinel ()
  76   (set-process-sentinel
  77    (get-buffer-process (buffer-name)) (function emacs-lock-clear-sentinel)))
  78
  79 (defun emacs-lock-clear-sentinel (_proc _str)
  80   (if emacs-lock-from-exiting
  81       (progn
  82         (setq emacs-lock-from-exiting nil)
  83         (setq emacs-lock-buffer-locked t)
  84         (message "Buffer is now unlocked"))
  85     (setq emacs-lock-buffer-locked nil)))
  86
  87 (defun emacs-lock-was-buffer-locked ()
  88   (if emacs-lock-buffer-locked
  89       (setq emacs-lock-from-exiting t)))
  90
  91 (unless noninteractive
  92   (add-hook 'kill-emacs-hook 'check-emacs-lock))
  93 (add-hook 'kill-buffer-hook 'emacs-lock-check-buffer-lock)
  94 (add-hook 'shell-mode-hook 'emacs-lock-was-buffer-locked)
  95 (add-hook 'shell-mode-hook 'emacs-lock-shell-sentinel)
  96 (add-hook 'telnet-mode-hook 'emacs-lock-was-buffer-locked)
  97 (add-hook 'telnet-mode-hook 'emacs-lock-shell-sentinel)
  98
  99 (provide 'emacs-lock)
 100
 101 ;;; emacs-lock.el ends here