all messages for Emacs-related lists mirrored at yhetil.org
 help / color / mirror / code / Atom feed
blob a0c55fd1e13433ca7c9e8070cac20cc91e75fbd0 5422 bytes (raw)
name: lisp/userlock.el 	 # note: path name is non-authoritative(*)

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
 
;;; userlock.el --- handle file access contention between multiple users

;; Copyright (C) 1985-1986, 2001-2016 Free Software Foundation, Inc.

;; Author: Richard King
;; (according to authors.el)
;; Maintainer: emacs-devel@gnu.org
;; Keywords: internal
;; Package: emacs

;; This file is part of GNU Emacs.

;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.

;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.

;;; Commentary:

;; This file is autoloaded to handle certain conditions
;; detected by the file-locking code within Emacs.
;; The two entry points are `ask-user-about-lock' and
;; `ask-user-about-supersession-threat'.

;;; Code:

(define-error 'file-locked "File is locked" 'file-error)

;;;###autoload
(defun ask-user-about-lock (file opponent)
  "Ask user what to do when he wants to edit FILE but it is locked by OPPONENT.
This function has a choice of three things to do:
  do (signal \\='file-locked (list FILE OPPONENT))
    to refrain from editing the file
  return t (grab the lock on the file)
  return nil (edit the file even though it is locked).
You can redefine this function to choose among those three alternatives
in any way you like."
  (discard-input)
  (save-window-excursion
    (let (answer short-opponent short-file)
      (setq short-file
	    (if (> (length file) 22)
		(concat "..." (substring file (- (length file) 22)))
	      file))
      (setq short-opponent
	    (if (> (length opponent) 25)
		(save-match-data
		  (string-match " (pid [0-9]+)" opponent)
		  (concat (substring opponent 0 13) "..."
			  (match-string 0 opponent)))
	      opponent))
      (while (null answer)
	(message "%s locked by %s: (s, q, p, ?)? "
		 short-file short-opponent)
	(let ((tem (let ((inhibit-quit t)
			 (cursor-in-echo-area t))
		     (prog1 (downcase (read-char))
		            (setq quit-flag nil)))))
	  (if (= tem help-char)
	      (ask-user-about-lock-help)
	    (setq answer (assoc tem '((?s . t)
				      (?q . yield)
				      (?\C-g . yield)
				      (?p . nil)
				      (?? . help))))
	    (cond ((null answer)
		   (beep)
		   (message "Please type q, s, or p; or ? for help")
		   (sit-for 3))
		  ((eq (cdr answer) 'help)
		   (ask-user-about-lock-help)
		   (setq answer nil))
		  ((eq (cdr answer) 'yield)
		   (signal 'file-locked (list file opponent)))))))
      (cdr answer))))

(defun ask-user-about-lock-help ()
  (with-output-to-temp-buffer "*Help*"
    (princ "It has been detected that you want to modify a file that someone else has
already started modifying in Emacs.

You can <s>teal the file; the other user becomes the
  intruder if (s)he ever unmodifies the file and then changes it again.
You can <p>roceed; you edit at your own (and the other user's) risk.
You can <q>uit; don't modify this file.")
    (with-current-buffer standard-output
      (help-mode))))

(define-error 'file-supersession nil 'file-error)

;;;###autoload
(defun ask-user-about-supersession-threat (fn)
  "Ask a user who is about to modify an obsolete buffer what to do.
This function has two choices: it can return, in which case the modification
of the buffer will proceed, or it can (signal \\='file-supersession (file)),
in which case the proposed buffer modification will not be made.

You can rewrite this to use any criterion you like to choose which one to do.
The buffer in question is current when this function is called."
  (discard-input)
  (save-window-excursion
    (let ((prompt
	   (format "%s changed on disk; \
really edit the buffer? (y, n, r or C-h) "
		   (file-name-nondirectory fn)))
	  (choices '(?y ?n ?r ?? ?\C-h))
	  answer)
      (while (null answer)
	(setq answer (read-char-choice prompt choices))
	(cond ((memq answer '(?? ?\C-h))
	       (ask-user-about-supersession-help)
	       (setq answer nil))
	      ((eq answer ?r)
	       ;; Ask for confirmation if buffer modified
	       (revert-buffer nil (not (buffer-modified-p)))
	       (signal 'file-supersession
		       (list "File reverted" fn)))
	      ((eq answer ?n)
	       (signal 'file-supersession
		       (list "File changed on disk" fn)))))
      (message
       "File on disk now will become a backup file if you save these changes.")
      (setq buffer-backed-up nil))))

(defun ask-user-about-supersession-help ()
  (with-output-to-temp-buffer "*Help*"
    (princ "You want to modify a buffer whose disk file has changed
since you last read it in or saved it with this buffer.

If you say `y' to go ahead and modify this buffer,
you risk ruining the work of whoever rewrote the file.
If you say `r' to revert, the contents of the buffer are refreshed
from the file on disk.
If you say `n', the change you started to make will be aborted.

Usually, you should type `n' and then `\\[revert-buffer]',
to get the latest version of the file, then make the change again.")
    (with-current-buffer standard-output
      (help-mode))))

;;; userlock.el ends here

debug log:

solving a0c55fd ...
found a0c55fd in https://git.savannah.gnu.org/cgit/emacs.git

(*) Git path names are given by the tree(s) the blob belongs to.
    Blobs themselves have no identifier aside from the hash of its contents.^

Code repositories for project(s) associated with this external index

	https://git.savannah.gnu.org/cgit/emacs.git
	https://git.savannah.gnu.org/cgit/emacs/org-mode.git

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.