lisp/emacs-lock.el

   1 ;;; emacs-lock.el --- prevents you from exiting emacs if a buffer is locked
   2
   3 ;; Copyright (C) 1994, 1997 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 2, or (at your option)
  14 ;; 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; see the file COPYING.  If not, write to the
  23 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  24 ;; Boston, MA 02111-1307, USA.
  25
  26 ;;; Commentary:
  27
  28 ;; This code sets a buffer-local variable to t if toggle-emacs-lock is run,
  29 ;; then if the user attempts to exit emacs, the locked buffer name will be
  30 ;; displayed and the exit aborted.  This is just a way of protecting
  31 ;; yourself from yourself.  For example, if you have a shell running a big
  32 ;; program and exiting emacs would abort that program, you may want to lock
  33 ;; that buffer, then if you forget about it after a while, you won't
  34 ;; accidentally exit emacs.  To unlock the buffer, just goto the buffer and
  35 ;; run toggle-emacs-lock again.
  36
  37 ;;; Code:
  38
  39 (defvar emacs-lock-from-exiting nil
  40   "Whether emacs is locked to prevent exiting.  See `check-emacs-lock'.")
  41 (make-variable-buffer-local 'emacs-lock-from-exiting)
  42
  43 (defvar emacs-lock-buffer-locked nil
  44   "Whether a shell or telnet buffer was locked when its process was killed.")
  45 (make-variable-buffer-local 'emacs-lock-buffer-locked)
  46 (put 'emacs-lock-buffer-locked 'permanent-local t)
  47
  48 (defun check-emacs-lock ()
  49   "Check if variable `emacs-lock-from-exiting' is t for any buffer.
  50 If any t is found, signal error and display the locked buffer name."
  51   (let ((buffers (buffer-list)))
  52     (save-excursion
  53       (while buffers
  54         (set-buffer (car buffers))
  55         (if emacs-lock-from-exiting
  56             (error "Emacs is locked from exit due to buffer: %s" (buffer-name))
  57           (setq buffers (cdr buffers)))))))
  58
  59 (defun toggle-emacs-lock ()
  60   "Toggle `emacs-lock-from-exiting' between t and nil for the current buffer.
  61 See `check-emacs-lock'."
  62   (interactive)
  63   (if emacs-lock-from-exiting
  64       (setq emacs-lock-from-exiting nil)
  65     (setq emacs-lock-from-exiting t))
  66   (if emacs-lock-from-exiting
  67       (message "Buffer is now locked")
  68     (message "Buffer is now unlocked")))
  69
  70 (defun emacs-lock-check-buffer-lock ()
  71   "Check if variable `emacs-lock-from-exiting' is t for a buffer.
  72 If t is found, signal error and display the locked buffer name."
  73   (if emacs-lock-from-exiting
  74       (error "Buffer `%s' is locked, can't delete it" (buffer-name))))
  75
  76 ; These next defuns make it so if you exit a shell that is locked,  the lock
  77 ; is shut off for that shell so you can exit emacs.  Same for telnet.
  78 ; Also, if a shell or a telnet buffer was locked and the process killed,
  79 ; turn the lock back on again if the process is restarted.
  80
  81 (defun emacs-lock-shell-sentinel ()
  82   (set-process-sentinel
  83    (get-buffer-process (buffer-name)) (function emacs-lock-clear-sentinel)))
  84
  85 (defun emacs-lock-clear-sentinel (proc str)
  86   (if emacs-lock-from-exiting
  87       (progn
  88         (setq emacs-lock-from-exiting nil)
  89         (setq emacs-lock-buffer-locked t)
  90         (message "Buffer is now unlocked"))
  91     (setq emacs-lock-buffer-locked nil)))
  92
  93 (defun emacs-lock-was-buffer-locked ()
  94   (if emacs-lock-buffer-locked
  95       (setq emacs-lock-from-exiting t)))
  96
  97 (add-hook 'kill-emacs-hook 'check-emacs-lock)
  98 (add-hook 'kill-buffer-hook 'emacs-lock-check-buffer-lock)
  99 (add-hook 'shell-mode-hook 'emacs-lock-was-buffer-locked)
 100 (add-hook 'shell-mode-hook 'emacs-lock-shell-sentinel)
 101 (add-hook 'telnet-mode-hook 'emacs-lock-was-buffer-locked)
 102 (add-hook 'telnet-mode-hook 'emacs-lock-shell-sentinel)
 103
 104 (provide 'emacs-lock)
 105
 106 ;;; emacs-lock.el ends here