1;;; emacs-lock.el --- prevents you from exiting Emacs if a buffer is locked
2
3;; Copyright (C) 1994, 1997, 2001, 2002, 2003, 2004,
4;;   2005, 2006, 2007 Free Software Foundation, Inc
5
6;; Author: Tom Wurgler <twurgler@goodyear.com>
7;; Created: 12/8/94
8;; Keywords: extensions, processes
9
10;; This file is part of GNU Emacs.
11
12;; GNU Emacs is free software; you can redistribute it and/or modify
13;; it under the terms of the GNU General Public License as published by
14;; the Free Software Foundation; either version 2, or (at your option)
15;; any later version.
16
17;; GNU Emacs is distributed in the hope that it will be useful,
18;; but WITHOUT ANY WARRANTY; without even the implied warranty of
19;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
20;; GNU General Public License for more details.
21
22;; You should have received a copy of the GNU General Public License
23;; along with GNU Emacs; see the file COPYING.  If not, write to the
24;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
25;; Boston, MA 02110-1301, USA.
26
27;;; Commentary:
28
29;; This code sets a buffer-local variable to t if toggle-emacs-lock is run,
30;; then if the user attempts to exit Emacs, the locked buffer name will be
31;; displayed and the exit aborted.  This is just a way of protecting
32;; yourself from yourself.  For example, if you have a shell running a big
33;; program and exiting Emacs would abort that program, you may want to lock
34;; that buffer, then if you forget about it after a while, you won't
35;; accidentally exit Emacs.  To unlock the buffer, just goto the buffer and
36;; run toggle-emacs-lock again.
37
38;;; Code:
39
40(defvar emacs-lock-from-exiting nil
41  "Whether Emacs is locked to prevent exiting.  See `check-emacs-lock'.")
42(make-variable-buffer-local 'emacs-lock-from-exiting)
43
44(defvar emacs-lock-buffer-locked nil
45  "Whether a shell or telnet buffer was locked when its process was killed.")
46(make-variable-buffer-local 'emacs-lock-buffer-locked)
47(put 'emacs-lock-buffer-locked 'permanent-local t)
48
49(defun check-emacs-lock ()
50  "Check if variable `emacs-lock-from-exiting' is t for any buffer.
51If any locked buffer is found, signal error and display the buffer's name."
52  (save-excursion
53    (dolist (buffer (buffer-list))
54      (set-buffer buffer)
55      (when emacs-lock-from-exiting
56	(error "Emacs is locked from exit due to buffer: %s" (buffer-name))))))
57
58(defun toggle-emacs-lock ()
59  "Toggle `emacs-lock-from-exiting' for the current buffer.
60See `check-emacs-lock'."
61  (interactive)
62  (setq emacs-lock-from-exiting (not emacs-lock-from-exiting))
63  (if emacs-lock-from-exiting
64      (message "Buffer is now locked")
65    (message "Buffer is now unlocked")))
66
67(defun emacs-lock-check-buffer-lock ()
68  "Check if variable `emacs-lock-from-exiting' is t for a buffer.
69If the buffer is locked, signal error and display its name."
70  (when emacs-lock-from-exiting
71    (error "Buffer `%s' is locked, can't delete it" (buffer-name))))
72
73; These next defuns make it so if you exit a shell that is locked,  the lock
74; is shut off for that shell so you can exit Emacs.  Same for telnet.
75; Also, if a shell or a telnet buffer was locked and the process killed,
76; turn the lock back on again if the process is restarted.
77
78(defun emacs-lock-shell-sentinel ()
79  (set-process-sentinel
80   (get-buffer-process (buffer-name)) (function emacs-lock-clear-sentinel)))
81
82(defun emacs-lock-clear-sentinel (proc str)
83  (if emacs-lock-from-exiting
84      (progn
85	(setq emacs-lock-from-exiting nil)
86	(setq emacs-lock-buffer-locked t)
87	(message "Buffer is now unlocked"))
88    (setq emacs-lock-buffer-locked nil)))
89
90(defun emacs-lock-was-buffer-locked ()
91  (if emacs-lock-buffer-locked
92      (setq emacs-lock-from-exiting t)))
93
94(add-hook 'kill-emacs-hook 'check-emacs-lock)
95(add-hook 'kill-buffer-hook 'emacs-lock-check-buffer-lock)
96(add-hook 'shell-mode-hook 'emacs-lock-was-buffer-locked)
97(add-hook 'shell-mode-hook 'emacs-lock-shell-sentinel)
98(add-hook 'telnet-mode-hook 'emacs-lock-was-buffer-locked)
99(add-hook 'telnet-mode-hook 'emacs-lock-shell-sentinel)
100
101(provide 'emacs-lock)
102
103;;; arch-tag: 58e6cb43-7cf0-401a-bcb6-4902a0b8bdc1
104;;; emacs-lock.el ends here
105