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d501f516 ER |
1 | ;;; userlock.el --- handle file access contention between multiple users |
2 | ||
ba318903 | 3 | ;; Copyright (C) 1985-1986, 2001-2014 Free Software Foundation, Inc. |
58142744 | 4 | |
72311017 GM |
5 | ;; Author: Richard King |
6 | ;; (according to authors.el) | |
34dc21db | 7 | ;; Maintainer: emacs-devel@gnu.org |
6251ee24 | 8 | ;; Keywords: internal |
d0b822e3 | 9 | ;; Package: emacs |
e5167999 | 10 | |
a2535589 JA |
11 | ;; This file is part of GNU Emacs. |
12 | ||
eb3fa2cf | 13 | ;; GNU Emacs is free software: you can redistribute it and/or modify |
a2535589 | 14 | ;; it under the terms of the GNU General Public License as published by |
eb3fa2cf GM |
15 | ;; the Free Software Foundation, either version 3 of the License, or |
16 | ;; (at your option) any later version. | |
a2535589 JA |
17 | |
18 | ;; GNU Emacs is distributed in the hope that it will be useful, | |
19 | ;; but WITHOUT ANY WARRANTY; without even the implied warranty of | |
20 | ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
21 | ;; GNU General Public License for more details. | |
22 | ||
23 | ;; You should have received a copy of the GNU General Public License | |
eb3fa2cf | 24 | ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. |
a2535589 | 25 | |
e5167999 | 26 | ;;; Commentary: |
a2535589 | 27 | |
e5167999 | 28 | ;; This file is autoloaded to handle certain conditions |
a2535589 JA |
29 | ;; detected by the file-locking code within Emacs. |
30 | ;; The two entry points are `ask-user-about-lock' and | |
31 | ;; `ask-user-about-supersession-threat'. | |
32 | ||
e5167999 | 33 | ;;; Code: |
a2535589 | 34 | |
54bd972f | 35 | (define-error 'file-locked "File is locked" 'file-error) |
a2535589 | 36 | |
f9f9507e | 37 | ;;;###autoload |
bdca5405 RS |
38 | (defun ask-user-about-lock (file opponent) |
39 | "Ask user what to do when he wants to edit FILE but it is locked by OPPONENT. | |
a2535589 | 40 | This function has a choice of three things to do: |
5f60927d | 41 | do (signal 'file-locked (list FILE OPPONENT)) |
a2535589 JA |
42 | to refrain from editing the file |
43 | return t (grab the lock on the file) | |
44 | return nil (edit the file even though it is locked). | |
bdca5405 RS |
45 | You can redefine this function to choose among those three alternatives |
46 | in any way you like." | |
a2535589 JA |
47 | (discard-input) |
48 | (save-window-excursion | |
bdca5405 RS |
49 | (let (answer short-opponent short-file) |
50 | (setq short-file | |
51 | (if (> (length file) 22) | |
52 | (concat "..." (substring file (- (length file) 22))) | |
53 | file)) | |
54 | (setq short-opponent | |
55 | (if (> (length opponent) 25) | |
56 | (save-match-data | |
57 | (string-match " (pid [0-9]+)" opponent) | |
58 | (concat (substring opponent 0 13) "..." | |
59 | (match-string 0 opponent))) | |
60 | opponent)) | |
a2535589 | 61 | (while (null answer) |
bdca5405 RS |
62 | (message "%s locked by %s: (s, q, p, ?)? " |
63 | short-file short-opponent) | |
a2535589 JA |
64 | (let ((tem (let ((inhibit-quit t) |
65 | (cursor-in-echo-area t)) | |
66 | (prog1 (downcase (read-char)) | |
67 | (setq quit-flag nil))))) | |
68 | (if (= tem help-char) | |
69 | (ask-user-about-lock-help) | |
70 | (setq answer (assoc tem '((?s . t) | |
71 | (?q . yield) | |
72 | (?\C-g . yield) | |
73 | (?p . nil) | |
74 | (?? . help)))) | |
75 | (cond ((null answer) | |
76 | (beep) | |
77 | (message "Please type q, s, or p; or ? for help") | |
78 | (sit-for 3)) | |
79 | ((eq (cdr answer) 'help) | |
80 | (ask-user-about-lock-help) | |
81 | (setq answer nil)) | |
82 | ((eq (cdr answer) 'yield) | |
bdca5405 | 83 | (signal 'file-locked (list file opponent))))))) |
a2535589 JA |
84 | (cdr answer)))) |
85 | ||
86 | (defun ask-user-about-lock-help () | |
87 | (with-output-to-temp-buffer "*Help*" | |
88 | (princ "It has been detected that you want to modify a file that someone else has | |
95d2516a | 89 | already started modifying in Emacs. |
a2535589 | 90 | |
95d2516a | 91 | You can <s>teal the file; the other user becomes the |
a2535589 JA |
92 | intruder if (s)he ever unmodifies the file and then changes it again. |
93 | You can <p>roceed; you edit at your own (and the other user's) risk. | |
0dc07483 | 94 | You can <q>uit; don't modify this file.") |
7fdbcd83 | 95 | (with-current-buffer standard-output |
0dc07483 | 96 | (help-mode)))) |
a2535589 | 97 | |
54bd972f | 98 | (define-error 'file-supersession nil 'file-error) |
a2535589 | 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 | |
145823ec CY |
111 | (let ((prompt |
112 | (format "%s changed on disk; \ | |
113 | really edit the buffer? (y, n, r or C-h) " | |
114 | (file-name-nondirectory fn))) | |
115 | (choices '(?y ?n ?r ?? ?\C-h)) | |
116 | answer) | |
a2535589 | 117 | (while (null answer) |
145823ec CY |
118 | (setq answer (read-char-choice prompt choices)) |
119 | (cond ((memq answer '(?? ?\C-h)) | |
120 | (ask-user-about-supersession-help) | |
121 | (setq answer nil)) | |
122 | ((eq answer ?r) | |
123 | ;; Ask for confirmation if buffer modified | |
124 | (revert-buffer nil (not (buffer-modified-p))) | |
125 | (signal 'file-supersession | |
126 | (list "File reverted" fn))) | |
127 | ((eq answer ?n) | |
128 | (signal 'file-supersession | |
129 | (list "File changed on disk" fn))))) | |
a2535589 | 130 | (message |
145823ec | 131 | "File on disk now will become a backup file if you save these changes.") |
a2535589 JA |
132 | (setq buffer-backed-up nil)))) |
133 | ||
134 | (defun ask-user-about-supersession-help () | |
135 | (with-output-to-temp-buffer "*Help*" | |
136 | (princ "You want to modify a buffer whose disk file has changed | |
137 | since you last read it in or saved it with this buffer. | |
138 | ||
139 | If you say `y' to go ahead and modify this buffer, | |
140 | you risk ruining the work of whoever rewrote the file. | |
11fc9165 RS |
141 | If you say `r' to revert, the contents of the buffer are refreshed |
142 | from the file on disk. | |
a2535589 JA |
143 | If you say `n', the change you started to make will be aborted. |
144 | ||
145 | Usually, you should type `n' and then `M-x revert-buffer', | |
0dc07483 | 146 | to get the latest version of the file, then make the change again.") |
7fdbcd83 | 147 | (with-current-buffer standard-output |
0dc07483 | 148 | (help-mode)))) |
a2535589 | 149 | |
d501f516 | 150 | ;;; userlock.el ends here |