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1 | ;;; utf-7.el --- utf-7 coding system |
2 | ||
95df8112 | 3 | ;; Copyright (C) 2003-2011 Free Software Foundation, Inc. |
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4 | |
5 | ;; Author: Dave Love <fx@gnu.org> | |
6 | ;; Keywords: i18n, mail | |
7 | ||
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8 | ;; This file is part of GNU Emacs. |
9 | ||
10 | ;; GNU Emacs is free software: you can redistribute it and/or modify | |
347003be | 11 | ;; it under the terms of the GNU General Public License as published by |
eb3fa2cf GM |
12 | ;; the Free Software Foundation, either version 3 of the License, or |
13 | ;; (at your option) any later version. | |
347003be | 14 | |
eb3fa2cf | 15 | ;; GNU Emacs is distributed in the hope that it will be useful, |
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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 | |
eb3fa2cf | 21 | ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. |
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22 | |
23 | ;;; Commentary: | |
24 | ||
25 | ;; Defines a coding system for UTF-7, defined in RFC 2152. Non-ASCII | |
26 | ;; segments are encoded as base64-encoded big endian UTF-16. Also | |
27 | ;; defines a variation required for IMAP (RFC 2060). | |
28 | ||
29 | ;; The encoding and decoding was originally taken from Jon K Hellan's | |
30 | ;; implementation in Gnus, but has been substantially re-done. | |
31 | ||
32 | ;; This probably needs more attention. In particular, it's not | |
fffa137c | 33 | ;; completely consistent with iconv's behavior. It's arguable |
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34 | ;; whether the IMAP version should be a coding system since it's |
35 | ;; apparently only used for IMAP mailbox names, so it's commented out. | |
36 | ||
37 | ;;; Code: | |
38 | ||
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39 | (defun utf-7-decode (len imap) |
40 | "Decode LEN bytes of UTF-7 at point. | |
41 | IMAP non-nil means use the IMAP version." | |
42 | (save-excursion | |
43 | (save-restriction | |
44 | (narrow-to-region (point) (+ (point) len)) | |
45 | (let ((not-esc (if imap "^&" "^+")) | |
46 | (skip-chars (if imap "A-Za-z0-9+," "A-Za-z0-9+/"))) | |
47 | (while (not (eobp)) | |
48 | (skip-chars-forward not-esc) | |
49 | (unless (eobp) | |
50 | (forward-char) | |
51 | (let ((p (point)) | |
52 | (run-length (skip-chars-forward skip-chars))) | |
53 | (if (eq ?- (char-after)) | |
54 | (delete-char 1)) | |
55 | (unless (= run-length 0) ; encoded lone esc-char | |
56 | (let ((pl (mod (- run-length) 4))) | |
57 | (insert-char ?= pl) | |
58 | (if imap | |
59 | (subst-char-in-region p (point) ?, ?/)) | |
60 | (base64-decode-region p (point))) | |
9ef9b28e | 61 | (decode-coding-region p (point) 'utf-16be) |
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62 | (save-excursion |
63 | (goto-char p) | |
d355a0b7 | 64 | (delete-char -1))))))) |
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65 | (- (point-max) (point-min))))) |
66 | ||
a74333a1 | 67 | ;;;###autoload |
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68 | (defun utf-7-post-read-conversion (len) |
69 | (utf-7-decode len nil)) | |
70 | ||
7d06be9c KH |
71 | ;;;###autoload |
72 | (defun utf-7-imap-post-read-conversion (len) | |
73 | (utf-7-decode len t)) | |
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74 | |
75 | (defun utf-7-encode (from to imap) | |
76 | "Encode bytes between FROM and TO to UTF-7. | |
77 | ESC and SKIP-CHARS are adjusted for the normal and IMAP versions." | |
78 | (let* ((old-buf (current-buffer)) | |
79 | (esc (if imap ?& ?+)) | |
80 | ;; These are characters which can be encoded asis. | |
81 | (skip-chars (if imap | |
82 | "\t\n\r\x20-\x25\x27-\x7e" ; rfc2060 | |
83 | ;; This includes the rfc2152 optional set. | |
84 | ;; Perhaps it shouldn't (like iconv). | |
85 | "\t\n\r -*,-[]-}")) | |
86 | (not-skip-chars (format "^%s%c" skip-chars esc))) | |
87 | (set-buffer (generate-new-buffer " *temp*")) | |
88 | (if (stringp from) | |
89 | (insert from) | |
90 | (insert-buffer-substring old-buf from to)) | |
91 | (goto-char (point-min)) | |
92 | (while (not (eobp)) | |
93 | (skip-chars-forward skip-chars) | |
e9255637 | 94 | (if (eq esc (char-after)) |
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95 | (progn (forward-char) |
96 | (insert ?-)) | |
97 | (unless (eobp) | |
98 | (insert esc) | |
99 | (let ((p (point))) | |
100 | (skip-chars-forward not-skip-chars) | |
101 | (save-restriction | |
102 | ;; encode-coding-region doesn't preserve point | |
103 | (narrow-to-region p (point)) | |
9ef9b28e | 104 | (encode-coding-region p (point-max) 'utf-16be) |
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105 | (base64-encode-region p (point-max)) |
106 | (if imap | |
107 | (subst-char-in-region p (point-max) ?/ ?,)) | |
108 | (goto-char p) | |
109 | ;; As I read the RFC, this isn't correct, but it's | |
110 | ;; consistent with iconv, at least regarding `='. | |
111 | (skip-chars-forward "^= \t\n") | |
112 | (delete-region (point) (point-max)))) | |
13dbab28 SM |
113 | ;; RFC2060 stipulates that all names MUST end in US-ASCII (i.e. |
114 | ;; a name that ends with a Unicode octet MUST end with a "-"). | |
115 | (if (or imap (not (eobp))) | |
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116 | (insert ?-))))) |
117 | nil)) | |
118 | ||
a74333a1 | 119 | ;;;###autoload |
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120 | (defun utf-7-pre-write-conversion (from to) |
121 | (utf-7-encode from to nil)) | |
122 | ||
7d06be9c KH |
123 | ;;;###autoload |
124 | (defun utf-7-imap-pre-write-conversion (from to) | |
125 | (utf-7-encode from to t)) | |
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126 | |
127 | (provide 'utf-7) | |
ab5796a9 | 128 | |
347003be | 129 | ;;; utf-7.el ends here |