Commit | Line | Data |
---|---|---|
d501f516 ER |
1 | ;;; userlock.el --- handle file access contention between multiple users |
2 | ||
58142744 ER |
3 | ;; Copyright (C) 1985, 1986 Free Software Foundation, inc. |
4 | ||
6251ee24 | 5 | ;; Maintainer: FSF |
6251ee24 | 6 | ;; Keywords: internal |
e5167999 | 7 | |
a2535589 JA |
8 | ;; This file is part of GNU Emacs. |
9 | ||
10 | ;; GNU Emacs is free software; you can redistribute it and/or modify | |
11 | ;; it under the terms of the GNU General Public License as published by | |
e5167999 | 12 | ;; the Free Software Foundation; either version 2, or (at your option) |
a2535589 JA |
13 | ;; any later version. |
14 | ||
15 | ;; GNU Emacs is distributed in the hope that it will be useful, | |
16 | ;; but WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
18 | ;; GNU General Public License for more details. | |
19 | ||
20 | ;; You should have received a copy of the GNU General Public License | |
b578f267 EN |
21 | ;; along with GNU Emacs; see the file COPYING. If not, write to the |
22 | ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330, | |
23 | ;; Boston, MA 02111-1307, USA. | |
a2535589 | 24 | |
e5167999 | 25 | ;;; Commentary: |
a2535589 | 26 | |
e5167999 | 27 | ;; This file is autoloaded to handle certain conditions |
a2535589 JA |
28 | ;; detected by the file-locking code within Emacs. |
29 | ;; The two entry points are `ask-user-about-lock' and | |
30 | ;; `ask-user-about-supersession-threat'. | |
31 | ||
e5167999 | 32 | ;;; Code: |
a2535589 JA |
33 | |
34 | (put 'file-locked 'error-conditions '(file-locked file-error error)) | |
35 | ||
f9f9507e | 36 | ;;;###autoload |
a2535589 JA |
37 | (defun ask-user-about-lock (fn opponent) |
38 | "Ask user what to do when he wants to edit FILE but it is locked by USER. | |
39 | This function has a choice of three things to do: | |
40 | do (signal 'buffer-file-locked (list FILE USER)) | |
41 | to refrain from editing the file | |
42 | return t (grab the lock on the file) | |
43 | return nil (edit the file even though it is locked). | |
44 | You can rewrite it to use any criterion you like to choose which one to do." | |
45 | (discard-input) | |
46 | (save-window-excursion | |
47 | (let (answer) | |
48 | (while (null answer) | |
49 | (message "%s is locking %s: action (s, q, p, ?)? " opponent fn) | |
50 | (let ((tem (let ((inhibit-quit t) | |
51 | (cursor-in-echo-area t)) | |
52 | (prog1 (downcase (read-char)) | |
53 | (setq quit-flag nil))))) | |
54 | (if (= tem help-char) | |
55 | (ask-user-about-lock-help) | |
56 | (setq answer (assoc tem '((?s . t) | |
57 | (?q . yield) | |
58 | (?\C-g . yield) | |
59 | (?p . nil) | |
60 | (?? . help)))) | |
61 | (cond ((null answer) | |
62 | (beep) | |
63 | (message "Please type q, s, or p; or ? for help") | |
64 | (sit-for 3)) | |
65 | ((eq (cdr answer) 'help) | |
66 | (ask-user-about-lock-help) | |
67 | (setq answer nil)) | |
68 | ((eq (cdr answer) 'yield) | |
69 | (signal 'file-locked (list "File is locked" fn opponent))))))) | |
70 | (cdr answer)))) | |
71 | ||
72 | (defun ask-user-about-lock-help () | |
73 | (with-output-to-temp-buffer "*Help*" | |
74 | (princ "It has been detected that you want to modify a file that someone else has | |
75 | already started modifying in EMACS. | |
76 | ||
77 | You can <s>teal the file; The other user becomes the | |
78 | intruder if (s)he ever unmodifies the file and then changes it again. | |
79 | You can <p>roceed; you edit at your own (and the other user's) risk. | |
0dc07483 KH |
80 | You can <q>uit; don't modify this file.") |
81 | (save-excursion | |
82 | (set-buffer standard-output) | |
83 | (help-mode)))) | |
a2535589 JA |
84 | |
85 | (put | |
86 | 'file-supersession 'error-conditions '(file-supersession file-error error)) | |
87 | ||
f9f9507e | 88 | ;;;###autoload |
a2535589 JA |
89 | (defun ask-user-about-supersession-threat (fn) |
90 | "Ask a user who is about to modify an obsolete buffer what to do. | |
91 | This function has two choices: it can return, in which case the modification | |
92 | of the buffer will proceed, or it can (signal 'file-supersession (file)), | |
93 | in which case the proposed buffer modification will not be made. | |
94 | ||
95 | You can rewrite this to use any criterion you like to choose which one to do. | |
96 | The buffer in question is current when this function is called." | |
97 | (discard-input) | |
98 | (save-window-excursion | |
99 | (let (answer) | |
100 | (while (null answer) | |
11fc9165 | 101 | (message "%s changed on disk; really edit the buffer? (y, n, r or C-h) " |
a217e08a | 102 | (file-name-nondirectory fn)) |
a2535589 JA |
103 | (let ((tem (downcase (let ((cursor-in-echo-area t)) |
104 | (read-char))))) | |
105 | (setq answer | |
106 | (if (= tem help-char) | |
107 | 'help | |
108 | (cdr (assoc tem '((?n . yield) | |
109 | (?\C-g . yield) | |
110 | (?y . proceed) | |
11fc9165 | 111 | (?r . revert) |
a2535589 JA |
112 | (?? . help)))))) |
113 | (cond ((null answer) | |
114 | (beep) | |
11fc9165 | 115 | (message "Please type y, n or r; or ? for help") |
a2535589 JA |
116 | (sit-for 3)) |
117 | ((eq answer 'help) | |
118 | (ask-user-about-supersession-help) | |
119 | (setq answer nil)) | |
11fc9165 RS |
120 | ((eq answer 'revert) |
121 | (revert-buffer nil (not (buffer-modified-p))) | |
122 | ; ask confirmation iff buffer modified | |
123 | (signal 'file-supersession | |
124 | (list "File reverted" fn))) | |
a2535589 JA |
125 | ((eq answer 'yield) |
126 | (signal 'file-supersession | |
127 | (list "File changed on disk" fn)))))) | |
128 | (message | |
129 | "File on disk now will become a backup file if you save these changes.") | |
130 | (setq buffer-backed-up nil)))) | |
131 | ||
132 | (defun ask-user-about-supersession-help () | |
133 | (with-output-to-temp-buffer "*Help*" | |
134 | (princ "You want to modify a buffer whose disk file has changed | |
135 | since you last read it in or saved it with this buffer. | |
136 | ||
137 | If you say `y' to go ahead and modify this buffer, | |
138 | you risk ruining the work of whoever rewrote the file. | |
11fc9165 RS |
139 | If you say `r' to revert, the contents of the buffer are refreshed |
140 | from the file on disk. | |
a2535589 JA |
141 | If you say `n', the change you started to make will be aborted. |
142 | ||
143 | Usually, you should type `n' and then `M-x revert-buffer', | |
0dc07483 KH |
144 | to get the latest version of the file, then make the change again.") |
145 | (save-excursion | |
146 | (set-buffer standard-output) | |
147 | (help-mode)))) | |
a2535589 | 148 | |
d501f516 | 149 | ;;; userlock.el ends here |