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comparison lisp/userlock.el @ 227:0e522484dd2a r20-5b12

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Import from CVS: tag r20-5b12
author cvs
date Mon, 13 Aug 2007 10:12:37 +0200
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226:eea38c7ad7b4 227:0e522484dd2a
1 ;;; userlock.el --- handle file access contention between multiple users
2
3 ;; Copyright (C) 1985, 1986, 1993 Free Software Foundation, inc.
4
5 ;; Maintainer: FSF
6 ;; Keywords: internal
7
8 ;; This file is part of XEmacs.
9
10 ;; XEmacs is free software; you can redistribute it and/or modify it
11 ;; under the terms of the GNU General Public License as published by
12 ;; the Free Software Foundation; either version 2, or (at your option)
13 ;; any later version.
14
15 ;; XEmacs is distributed in the hope that it will be useful, but
16 ;; WITHOUT ANY WARRANTY; without even the implied warranty of
17 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 ;; General Public License for more details.
19
20 ;; You should have received a copy of the GNU General Public License
21 ;; along with XEmacs; see the file COPYING. If not, write to the Free
22 ;; Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
23 ;; 02111-1307, USA.
24
25 ;;; Synched up with: FSF 19.34.
26
27 ;;; Commentary:
28
29 ;; This file is autoloaded to handle certain conditions
30 ;; detected by the file-locking code within XEmacs.
31 ;; The two entry points are `ask-user-about-lock' and
32 ;; `ask-user-about-supersession-threat'.
33
34 ;;; Code:
35
36 (define-error 'file-locked "File is locked" 'file-error) ; XEmacs
37
38 (defun ask-user-about-lock-minibuf (fn opponent)
39 (save-window-excursion
40 (let (answer)
41 (while (null answer)
42 (message "%s is locking %s: action (s, q, p, ?)? " opponent fn)
43 (let ((tem (let ((inhibit-quit t)
44 (cursor-in-echo-area t))
45 (prog1 (downcase (read-char))
46 (setq quit-flag nil)))))
47 (if (= tem help-char)
48 (ask-user-about-lock-help)
49 (setq answer (assoc tem '((?s . t)
50 (?q . yield)
51 (?\C-g . yield)
52 (?p . nil)
53 (?? . help))))
54 (cond ((null answer)
55 (beep)
56 (message "Please type q, s, or p; or ? for help")
57 (sit-for 3))
58 ((eq (cdr answer) 'help)
59 (ask-user-about-lock-help)
60 (setq answer nil))
61 ((eq (cdr answer) 'yield)
62 (signal 'file-locked (list "File is locked" fn opponent)))))))
63 (cdr answer))))
64
65 (defun ask-user-about-lock-help ()
66 (with-output-to-temp-buffer "*Help*"
67 (princ "It has been detected that you want to modify a file that someone else has
68 already started modifying in EMACS.
69
70 You can <s>teal the file; The other user becomes the
71 intruder if (s)he ever unmodifies the file and then changes it again.
72 You can <p>roceed; you edit at your own (and the other user's) risk.
73 You can <q>uit; don't modify this file.")
74 (save-excursion
75 (set-buffer standard-output)
76 (help-mode))))
77
78 (define-error 'file-supersession "File changed on disk" 'file-error) ; XEmacs
79
80 (defun ask-user-about-supersession-threat-minibuf (fn)
81 (save-window-excursion
82 (let (answer)
83 (while (null answer)
84 (message "%s changed on disk; really edit the buffer? (y, n, r or C-h) "
85 (file-name-nondirectory fn))
86 (let ((tem (downcase (let ((cursor-in-echo-area t))
87 (read-char)))))
88 (setq answer
89 (if (= tem help-char)
90 'help
91 (cdr (assoc tem '((?n . yield)
92 (?\C-g . yield)
93 (?y . proceed)
94 (?r . revert)
95 (?? . help))))))
96 (cond ((null answer)
97 (beep)
98 (message "Please type y, n or r; or ? for help")
99 (sit-for 3))
100 ((eq answer 'help)
101 (ask-user-about-supersession-help)
102 (setq answer nil))
103 ((eq answer 'revert)
104 (revert-buffer nil (not (buffer-modified-p)))
105 ; ask confirmation iff buffer modified
106 (signal 'file-supersession
107 (list "File reverted" fn)))
108 ((eq answer 'yield)
109 (signal 'file-supersession
110 (list "File changed on disk" fn))))))
111 (message
112 "File on disk now will become a backup file if you save these changes.")
113 (setq buffer-backed-up nil))))
114
115 (defun ask-user-about-supersession-help ()
116 (with-output-to-temp-buffer "*Help*"
117 (princ "You want to modify a buffer whose disk file has changed
118 since you last read it in or saved it with this buffer.
119
120 If you say `y' to go ahead and modify this buffer,
121 you risk ruining the work of whoever rewrote the file.
122 If you say `r' to revert, the contents of the buffer are refreshed
123 from the file on disk.
124 If you say `n', the change you started to make will be aborted.
125
126 Usually, you should type `n' and then `M-x revert-buffer',
127 to get the latest version of the file, then make the change again.")
128 (save-excursion
129 (set-buffer standard-output)
130 (help-mode))))
131
132 ;;; dialog-box versions [XEmacs]
133
134 (defun ask-user-about-lock-dbox (fn opponent)
135 (let ((echo-keystrokes 0)
136 (dbox
137 (cons
138 (format "%s is locking %s\n
139 It has been detected that you want to modify a file that
140 someone else has already started modifying in XEmacs."
141 opponent fn)
142 '(["Steal Lock\n\nThe other user will\nbecome the intruder" steal t]
143 ["Proceed\n\nEdit file at your own\n\(and the other user's) risk"
144 proceed t]
145 nil
146 ["Abort\n\nDon't modify the buffer\n" yield t]))))
147 (popup-dialog-box dbox)
148 (catch 'aual-done
149 (while t
150 (let ((event (next-command-event)))
151 (cond ((and (misc-user-event-p event) (eq (event-object event) 'proceed))
152 (throw 'aual-done nil))
153 ((and (misc-user-event-p event) (eq (event-object event) 'steal))
154 (throw 'aual-done t))
155 ((and (misc-user-event-p event) (eq (event-object event) 'yield))
156 (signal 'file-locked (list "File is locked" fn opponent)))
157 ((button-release-event-p event) ;; don't beep twice
158 nil)
159 (t
160 (beep)
161 (message "please answer the dialog box"))))))))
162
163 (defun ask-user-about-supersession-threat-dbox (fn)
164 (let ((echo-keystrokes 0)
165 (dbox
166 (cons
167 (format "File %s has changed on disk
168 since its buffer was last read in or saved.
169
170 Do you really want to edit the buffer? " fn)
171 '(["Yes\n\nEdit the buffer anyway,\nignoring the disk file"
172 proceed t]
173 ["No\n\nDon't modify the buffer\n" yield t]
174 nil
175 ["No\n\nDon't modify the buffer\nbut revert it" revert t]
176 ))))
177 (popup-dialog-box dbox)
178 (catch 'auast-done
179 (while t
180 (let ((event (next-command-event)))
181 (cond ((and (misc-user-event-p event) (eq (event-object event) 'proceed))
182 (throw 'auast-done nil))
183 ((and (misc-user-event-p event) (eq (event-object event) 'yield))
184 (signal 'file-supersession (list fn)))
185 ((and (misc-user-event-p event) (eq (event-object event) 'revert))
186 (or (equal fn (buffer-file-name))
187 (error
188 "ask-user-about-supersession-threat called bogusly"))
189 (revert-buffer nil t)
190 (signal 'file-supersession
191 (list fn "(reverted)")))
192 ((button-release-event-p event) ;; don't beep twice
193 nil)
194 (t
195 (beep)
196 (message "please answer the dialog box"))))))))
197
198
199 ;;; top-level
200
201 ;;;###autoload
202 (defun ask-user-about-lock (fn opponent)
203 "Ask user what to do when he wants to edit FILE but it is locked by USER.
204 This function has a choice of three things to do:
205 do (signal 'file-locked (list FILE USER))
206 to refrain from editing the file
207 return t (grab the lock on the file)
208 return nil (edit the file even though it is locked).
209 You can rewrite it to use any criterion you like to choose which one to do."
210 (discard-input)
211 (if (and (fboundp 'popup-dialog-box)
212 (or (button-press-event-p last-command-event)
213 (button-release-event-p last-command-event)
214 (misc-user-event-p last-command-event)))
215 (ask-user-about-lock-dbox fn opponent)
216 (ask-user-about-lock-minibuf fn opponent)))
217
218 ;;;###autoload
219 (defun ask-user-about-supersession-threat (fn)
220 "Ask a user who is about to modify an obsolete buffer what to do.
221 This function has two choices: it can return, in which case the modification
222 of the buffer will proceed, or it can (signal 'file-supersession (file)),
223 in which case the proposed buffer modification will not be made.
224
225 You can rewrite this to use any criterion you like to choose which one to do.
226 The buffer in question is current when this function is called."
227 (discard-input)
228 (if (and (fboundp 'popup-dialog-box)
229 (or (button-press-event-p last-command-event)
230 (button-release-event-p last-command-event)
231 (misc-user-event-p last-command-event)))
232 (ask-user-about-supersession-threat-dbox fn)
233 (ask-user-about-supersession-threat-minibuf fn)))
234
235 ;;; userlock.el ends here