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1 ;;; password-cache.el --- Read passwords, possibly using a password cache.
3 ;; Copyright (C) 1999-2000, 2003-2015 Free Software Foundation, Inc.
5 ;; Author: Simon Josefsson <simon@josefsson.org>
6 ;; Created: 2003-12-21
7 ;; Keywords: password cache passphrase key
9 ;; This file is part of GNU Emacs.
11 ;; GNU Emacs is free software: you can redistribute it and/or modify
12 ;; it under the terms of the GNU General Public License as published by
13 ;; the Free Software Foundation, either version 3 of the License, or
14 ;; (at your option) any later version.
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.
21 ;; You should have received a copy of the GNU General Public License
22 ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
24 ;;; Commentary:
26 ;; Greatly influenced by pgg.el written by Daiki Ueno, with timer
27 ;; fixes for XEmacs by Katsumi Yamaoka. In fact, this is mostly just
28 ;; a rip-off.
30 ;; (password-read "Password? " "test")
31 ;; ;; Minibuffer prompt for password.
32 ;; => "foo"
34 ;; (password-cache-add "test" "foo")
35 ;; => nil
37 ;; (password-read "Password? " "test")
38 ;; ;; No minibuffer prompt
39 ;; => "foo"
41 ;; (password-read "Password? " "test")
42 ;; ;; No minibuffer prompt
43 ;; => "foo"
45 ;; ;; Wait `password-cache-expiry' seconds.
47 ;; (password-read "Password? " "test")
48 ;; ;; Minibuffer prompt for password is back.
49 ;; => "foo"
51 ;;; Code:
53 ;; Options are autoloaded since they are used by eg mml-sec.el.
55 ;;;###autoload
56 (defcustom password-cache t
57 "Whether to cache passwords."
58 :group 'password
59 :type 'boolean)
61 ;;;###autoload
62 (defcustom password-cache-expiry 16
63 "How many seconds passwords are cached, or nil to disable expiring.
64 Whether passwords are cached at all is controlled by `password-cache'."
65 :group 'password
66 :type '(choice (const :tag "Never" nil)
67 (integer :tag "Seconds")))
69 (defvar password-data (make-vector 7 0))
71 (defun password-read-from-cache (key)
72 "Obtain passphrase for KEY from time-limited passphrase cache.
73 Custom variables `password-cache' and `password-cache-expiry'
74 regulate cache behavior."
75 (and password-cache
76 key
77 (symbol-value (intern-soft key password-data))))
79 ;;;###autoload
80 (defun password-in-cache-p (key)
81 "Check if KEY is in the cache."
82 (and password-cache
83 key
84 (intern-soft key password-data)))
86 (defun password-read (prompt &optional key)
87 "Read password, for use with KEY, from user, or from cache if wanted.
88 KEY indicate the purpose of the password, so the cache can
89 separate passwords. The cache is not used if KEY is nil. It is
90 typically a string.
91 The variable `password-cache' control whether the cache is used."
92 (or (password-read-from-cache key)
93 (read-passwd prompt)))
95 (defun password-read-and-add (prompt &optional key)
96 "Read password, for use with KEY, from user, or from cache if wanted.
97 Then store the password in the cache. Uses `password-read' and
98 `password-cache-add'. Custom variables `password-cache' and
99 `password-cache-expiry' regulate cache behavior.
101 Warning: the password is cached without checking that it is
102 correct. It is better to check the password before caching. If
103 you must use this function, take care to check passwords and
104 remove incorrect ones from the cache."
105 (declare (obsolete password-read "23.1"))
106 (let ((password (password-read prompt key)))
107 (when (and password key)
108 (password-cache-add key password))
109 password))
111 (defun password-cache-remove (key)
112 "Remove password indexed by KEY from password cache.
113 This is typically run by a timer setup from `password-cache-add',
114 but can be invoked at any time to forcefully remove passwords
115 from the cache. This may be useful when it has been detected
116 that a password is invalid, so that `password-read' query the
117 user again."
118 (let ((sym (intern-soft key password-data)))
119 (when sym
120 (let ((password (symbol-value sym)))
121 (when (stringp password)
122 (if (fboundp 'clear-string)
123 (clear-string password)
124 (fillarray password ?_)))
125 (unintern key password-data)))))
127 (defun password-cache-add (key password)
128 "Add password to cache.
129 The password is removed by a timer after `password-cache-expiry' seconds."
130 (when (and password-cache-expiry (null (intern-soft key password-data)))
131 (run-at-time password-cache-expiry nil
132 #'password-cache-remove
133 key))
134 (set (intern key password-data) password)
135 nil)
137 (defun password-reset ()
138 "Clear the password cache."
139 (interactive)
140 (fillarray password-data 0))
142 (provide 'password-cache)
144 ;;; password-cache.el ends here