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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)) | |
bdca5405 | 35 | (put 'file-locked 'error-message "File is locked") |
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 | |
89 | already started modifying in EMACS. | |
90 | ||
91 | You can <s>teal the file; The other user becomes the | |
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 KH |
94 | You can <q>uit; don't modify this file.") |
95 | (save-excursion | |
96 | (set-buffer standard-output) | |
97 | (help-mode)))) | |
a2535589 JA |
98 | |
99 | (put | |
100 | 'file-supersession 'error-conditions '(file-supersession file-error error)) | |
101 | ||
f9f9507e | 102 | ;;;###autoload |
a2535589 JA |
103 | (defun ask-user-about-supersession-threat (fn) |
104 | "Ask a user who is about to modify an obsolete buffer what to do. | |
105 | This function has two choices: it can return, in which case the modification | |
106 | of the buffer will proceed, or it can (signal 'file-supersession (file)), | |
107 | in which case the proposed buffer modification will not be made. | |
108 | ||
109 | You can rewrite this to use any criterion you like to choose which one to do. | |
110 | The buffer in question is current when this function is called." | |
111 | (discard-input) | |
112 | (save-window-excursion | |
113 | (let (answer) | |
114 | (while (null answer) | |
11fc9165 | 115 | (message "%s changed on disk; really edit the buffer? (y, n, r or C-h) " |
a217e08a | 116 | (file-name-nondirectory fn)) |
a2535589 JA |
117 | (let ((tem (downcase (let ((cursor-in-echo-area t)) |
118 | (read-char))))) | |
119 | (setq answer | |
120 | (if (= tem help-char) | |
121 | 'help | |
122 | (cdr (assoc tem '((?n . yield) | |
123 | (?\C-g . yield) | |
124 | (?y . proceed) | |
11fc9165 | 125 | (?r . revert) |
a2535589 JA |
126 | (?? . help)))))) |
127 | (cond ((null answer) | |
128 | (beep) | |
11fc9165 | 129 | (message "Please type y, n or r; or ? for help") |
a2535589 JA |
130 | (sit-for 3)) |
131 | ((eq answer 'help) | |
132 | (ask-user-about-supersession-help) | |
133 | (setq answer nil)) | |
11fc9165 RS |
134 | ((eq answer 'revert) |
135 | (revert-buffer nil (not (buffer-modified-p))) | |
136 | ; ask confirmation iff buffer modified | |
137 | (signal 'file-supersession | |
138 | (list "File reverted" fn))) | |
a2535589 JA |
139 | ((eq answer 'yield) |
140 | (signal 'file-supersession | |
141 | (list "File changed on disk" fn)))))) | |
142 | (message | |
143 | "File on disk now will become a backup file if you save these changes.") | |
144 | (setq buffer-backed-up nil)))) | |
145 | ||
146 | (defun ask-user-about-supersession-help () | |
147 | (with-output-to-temp-buffer "*Help*" | |
148 | (princ "You want to modify a buffer whose disk file has changed | |
149 | since you last read it in or saved it with this buffer. | |
150 | ||
151 | If you say `y' to go ahead and modify this buffer, | |
152 | you risk ruining the work of whoever rewrote the file. | |
11fc9165 RS |
153 | If you say `r' to revert, the contents of the buffer are refreshed |
154 | from the file on disk. | |
a2535589 JA |
155 | If you say `n', the change you started to make will be aborted. |
156 | ||
157 | Usually, you should type `n' and then `M-x revert-buffer', | |
0dc07483 KH |
158 | to get the latest version of the file, then make the change again.") |
159 | (save-excursion | |
160 | (set-buffer standard-output) | |
161 | (help-mode)))) | |
a2535589 | 162 | |
d501f516 | 163 | ;;; userlock.el ends here |