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d501f516 ER |
1 | ;;; userlock.el --- handle file access contention between multiple users |
2 | ||
c90f2757 | 3 | ;; Copyright (C) 1985, 1986, 2001, 2002, 2003, 2004, |
114f9c96 | 4 | ;; 2005, 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc. |
58142744 | 5 | |
6251ee24 | 6 | ;; Maintainer: FSF |
6251ee24 | 7 | ;; Keywords: internal |
e5167999 | 8 | |
a2535589 JA |
9 | ;; This file is part of GNU Emacs. |
10 | ||
eb3fa2cf | 11 | ;; GNU Emacs is free software: you can redistribute it and/or modify |
a2535589 | 12 | ;; it under the terms of the GNU General Public License as published by |
eb3fa2cf GM |
13 | ;; the Free Software Foundation, either version 3 of the License, or |
14 | ;; (at your option) any later version. | |
a2535589 JA |
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 | |
eb3fa2cf | 22 | ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. |
a2535589 | 23 | |
e5167999 | 24 | ;;; Commentary: |
a2535589 | 25 | |
e5167999 | 26 | ;; This file is autoloaded to handle certain conditions |
a2535589 JA |
27 | ;; detected by the file-locking code within Emacs. |
28 | ;; The two entry points are `ask-user-about-lock' and | |
29 | ;; `ask-user-about-supersession-threat'. | |
30 | ||
e5167999 | 31 | ;;; Code: |
a2535589 JA |
32 | |
33 | (put 'file-locked 'error-conditions '(file-locked file-error error)) | |
bdca5405 | 34 | (put 'file-locked 'error-message "File is locked") |
a2535589 | 35 | |
f9f9507e | 36 | ;;;###autoload |
bdca5405 RS |
37 | (defun ask-user-about-lock (file opponent) |
38 | "Ask user what to do when he wants to edit FILE but it is locked by OPPONENT. | |
a2535589 | 39 | This function has a choice of three things to do: |
5f60927d | 40 | do (signal 'file-locked (list FILE OPPONENT)) |
a2535589 JA |
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). | |
bdca5405 RS |
44 | You can redefine this function to choose among those three alternatives |
45 | in any way you like." | |
a2535589 JA |
46 | (discard-input) |
47 | (save-window-excursion | |
bdca5405 RS |
48 | (let (answer short-opponent short-file) |
49 | (setq short-file | |
50 | (if (> (length file) 22) | |
51 | (concat "..." (substring file (- (length file) 22))) | |
52 | file)) | |
53 | (setq short-opponent | |
54 | (if (> (length opponent) 25) | |
55 | (save-match-data | |
56 | (string-match " (pid [0-9]+)" opponent) | |
57 | (concat (substring opponent 0 13) "..." | |
58 | (match-string 0 opponent))) | |
59 | opponent)) | |
a2535589 | 60 | (while (null answer) |
bdca5405 RS |
61 | (message "%s locked by %s: (s, q, p, ?)? " |
62 | short-file short-opponent) | |
a2535589 JA |
63 | (let ((tem (let ((inhibit-quit t) |
64 | (cursor-in-echo-area t)) | |
65 | (prog1 (downcase (read-char)) | |
66 | (setq quit-flag nil))))) | |
67 | (if (= tem help-char) | |
68 | (ask-user-about-lock-help) | |
69 | (setq answer (assoc tem '((?s . t) | |
70 | (?q . yield) | |
71 | (?\C-g . yield) | |
72 | (?p . nil) | |
73 | (?? . help)))) | |
74 | (cond ((null answer) | |
75 | (beep) | |
76 | (message "Please type q, s, or p; or ? for help") | |
77 | (sit-for 3)) | |
78 | ((eq (cdr answer) 'help) | |
79 | (ask-user-about-lock-help) | |
80 | (setq answer nil)) | |
81 | ((eq (cdr answer) 'yield) | |
bdca5405 | 82 | (signal 'file-locked (list file opponent))))))) |
a2535589 JA |
83 | (cdr answer)))) |
84 | ||
85 | (defun ask-user-about-lock-help () | |
86 | (with-output-to-temp-buffer "*Help*" | |
87 | (princ "It has been detected that you want to modify a file that someone else has | |
95d2516a | 88 | already started modifying in Emacs. |
a2535589 | 89 | |
95d2516a | 90 | You can <s>teal the file; the other user becomes the |
a2535589 JA |
91 | intruder if (s)he ever unmodifies the file and then changes it again. |
92 | You can <p>roceed; you edit at your own (and the other user's) risk. | |
0dc07483 | 93 | You can <q>uit; don't modify this file.") |
7fdbcd83 | 94 | (with-current-buffer standard-output |
0dc07483 | 95 | (help-mode)))) |
a2535589 JA |
96 | |
97 | (put | |
98 | 'file-supersession 'error-conditions '(file-supersession file-error error)) | |
99 | ||
f9f9507e | 100 | ;;;###autoload |
a2535589 JA |
101 | (defun ask-user-about-supersession-threat (fn) |
102 | "Ask a user who is about to modify an obsolete buffer what to do. | |
103 | This function has two choices: it can return, in which case the modification | |
104 | of the buffer will proceed, or it can (signal 'file-supersession (file)), | |
105 | in which case the proposed buffer modification will not be made. | |
106 | ||
107 | You can rewrite this to use any criterion you like to choose which one to do. | |
108 | The buffer in question is current when this function is called." | |
109 | (discard-input) | |
110 | (save-window-excursion | |
111 | (let (answer) | |
112 | (while (null answer) | |
11fc9165 | 113 | (message "%s changed on disk; really edit the buffer? (y, n, r or C-h) " |
a217e08a | 114 | (file-name-nondirectory fn)) |
a2535589 | 115 | (let ((tem (downcase (let ((cursor-in-echo-area t)) |
91568070 | 116 | (read-char-exclusive))))) |
a2535589 JA |
117 | (setq answer |
118 | (if (= tem help-char) | |
119 | 'help | |
120 | (cdr (assoc tem '((?n . yield) | |
121 | (?\C-g . yield) | |
122 | (?y . proceed) | |
11fc9165 | 123 | (?r . revert) |
a2535589 JA |
124 | (?? . help)))))) |
125 | (cond ((null answer) | |
126 | (beep) | |
11fc9165 | 127 | (message "Please type y, n or r; or ? for help") |
a2535589 JA |
128 | (sit-for 3)) |
129 | ((eq answer 'help) | |
130 | (ask-user-about-supersession-help) | |
131 | (setq answer nil)) | |
11fc9165 RS |
132 | ((eq answer 'revert) |
133 | (revert-buffer nil (not (buffer-modified-p))) | |
4837b516 | 134 | ; ask confirmation if buffer modified |
11fc9165 RS |
135 | (signal 'file-supersession |
136 | (list "File reverted" fn))) | |
a2535589 JA |
137 | ((eq answer 'yield) |
138 | (signal 'file-supersession | |
139 | (list "File changed on disk" fn)))))) | |
140 | (message | |
141 | "File on disk now will become a backup file if you save these changes.") | |
142 | (setq buffer-backed-up nil)))) | |
143 | ||
144 | (defun ask-user-about-supersession-help () | |
145 | (with-output-to-temp-buffer "*Help*" | |
146 | (princ "You want to modify a buffer whose disk file has changed | |
147 | since you last read it in or saved it with this buffer. | |
148 | ||
149 | If you say `y' to go ahead and modify this buffer, | |
150 | you risk ruining the work of whoever rewrote the file. | |
11fc9165 RS |
151 | If you say `r' to revert, the contents of the buffer are refreshed |
152 | from the file on disk. | |
a2535589 JA |
153 | If you say `n', the change you started to make will be aborted. |
154 | ||
155 | Usually, you should type `n' and then `M-x revert-buffer', | |
0dc07483 | 156 | to get the latest version of the file, then make the change again.") |
7fdbcd83 | 157 | (with-current-buffer standard-output |
0dc07483 | 158 | (help-mode)))) |
a2535589 | 159 | |
cbee283d | 160 | ;; arch-tag: a61c5b60-e1c8-44fd-894a-c617f4dfc639 |
d501f516 | 161 | ;;; userlock.el ends here |