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23f87bed | 1 | ;;; mm-encode.el --- Functions for encoding MIME things |
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2 | |
3 | ;; Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, | |
e3fe4da0 | 4 | ;; 2005, 2006, 2007, 2008 Free Software Foundation, Inc. |
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5 | |
6 | ;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org> | |
7 | ;; MORIOKA Tomohiko <morioka@jaist.ac.jp> | |
8 | ;; This file is part of GNU Emacs. | |
9 | ||
5e809f55 | 10 | ;; GNU Emacs is free software: you can redistribute it and/or modify |
c113de23 | 11 | ;; it under the terms of the GNU General Public License as published by |
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12 | ;; the Free Software Foundation, either version 3 of the License, or |
13 | ;; (at your option) any later version. | |
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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 | |
5e809f55 | 17 | ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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18 | ;; GNU General Public License for more details. |
19 | ||
20 | ;; You should have received a copy of the GNU General Public License | |
5e809f55 | 21 | ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. |
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22 | |
23 | ;;; Commentary: | |
24 | ||
25 | ;;; Code: | |
26 | ||
b28ce55a | 27 | (eval-when-compile (require 'cl)) |
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28 | (require 'mail-parse) |
29 | (require 'mailcap) | |
4515227f | 30 | (eval-and-compile |
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31 | (autoload 'mm-body-7-or-8 "mm-bodies") |
32 | (autoload 'mm-long-lines-p "mm-bodies")) | |
c113de23 | 33 | |
23f87bed | 34 | (defcustom mm-content-transfer-encoding-defaults |
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35 | '(("text/x-patch" 8bit) |
36 | ("text/.*" qp-or-base64) | |
37 | ("message/rfc822" 8bit) | |
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38 | ("application/emacs-lisp" qp-or-base64) |
39 | ("application/x-emacs-lisp" qp-or-base64) | |
40 | ("application/x-patch" qp-or-base64) | |
5be28abc | 41 | (".*" base64)) |
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42 | "Alist of regexps that match MIME types and their encodings. |
43 | If the encoding is `qp-or-base64', then either quoted-printable | |
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44 | or base64 will be used, depending on what is more efficient. |
45 | ||
46 | `qp-or-base64' has another effect. It will fold long lines so that | |
47 | MIME parts may not be broken by MTA. So do `quoted-printable' and | |
48 | `base64'. | |
49 | ||
50 | Note: It affects body encoding only when a part is a raw forwarded | |
51 | message (which will be made by `gnus-summary-mail-forward' with the | |
52 | arg 2 for example) or is neither the text/* type nor the message/* | |
53 | type. Even though in those cases, you can use the `encoding' MML tag | |
54 | to specify encoding of non-ASCII MIME parts." | |
55 | :type '(repeat (list (regexp :tag "MIME type") | |
56 | (choice :tag "encoding" | |
57 | (const 7bit) | |
58 | (const 8bit) | |
59 | (const qp-or-base64) | |
60 | (const quoted-printable) | |
61 | (const base64)))) | |
62 | :group 'mime) | |
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63 | |
64 | (defvar mm-use-ultra-safe-encoding nil | |
65 | "If non-nil, use encodings aimed at Procrustean bed survival. | |
66 | ||
67 | This means that textual parts are encoded as quoted-printable if they | |
68 | contain lines longer than 76 characters or starting with \"From \" in | |
69 | the body. Non-7bit encodings (8bit, binary) are generally disallowed. | |
70 | This is to reduce the probability that a broken MTA or MDA changes the | |
71 | message. | |
72 | ||
73 | This variable should never be set directly, but bound before a call to | |
74 | `mml-generate-mime' or similar functions.") | |
75 | ||
76 | (defun mm-insert-rfc822-headers (charset encoding) | |
77 | "Insert text/plain headers with CHARSET and ENCODING." | |
78 | (insert "MIME-Version: 1.0\n") | |
79 | (insert "Content-Type: text/plain; charset=" | |
80 | (mail-quote-string (downcase (symbol-name charset))) "\n") | |
81 | (insert "Content-Transfer-Encoding: " | |
82 | (downcase (symbol-name encoding)) "\n")) | |
83 | ||
84 | (defun mm-insert-multipart-headers () | |
85 | "Insert multipart/mixed headers." | |
86 | (let ((boundary "=-=-=")) | |
87 | (insert "MIME-Version: 1.0\n") | |
88 | (insert "Content-Type: multipart/mixed; boundary=\"" boundary "\"\n") | |
89 | boundary)) | |
90 | ||
91 | (defun mm-default-file-encoding (file) | |
92 | "Return a default encoding for FILE." | |
93 | (if (not (string-match "\\.[^.]+$" file)) | |
94 | "application/octet-stream" | |
95 | (mailcap-extension-to-mime (match-string 0 file)))) | |
96 | ||
58a67d68 | 97 | (defun mm-safer-encoding (encoding &optional type) |
23f87bed | 98 | "Return an encoding similar to ENCODING but safer than it." |
c113de23 | 99 | (cond |
23f87bed | 100 | ((eq encoding '7bit) '7bit) ;; 7bit is considered safe. |
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101 | ((memq encoding '(8bit quoted-printable)) |
102 | ;; According to RFC2046, 5.2.1, RFC822 Subtype, "quoted-printable" is not | |
103 | ;; a valid encoding for message/rfc822: | |
104 | ;; No encoding other than "7bit", "8bit", or "binary" is permitted for the | |
105 | ;; body of a "message/rfc822" entity. | |
106 | (if (string= type "message/rfc822") '8bit 'quoted-printable)) | |
8f688cb0 | 107 | ;; The remaining encodings are binary and base64 (and perhaps some |
c113de23 | 108 | ;; non-standard ones), which are both turned into base64. |
58a67d68 | 109 | (t (if (string= type "message/rfc822") 'binary 'base64)))) |
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110 | |
111 | (defun mm-encode-content-transfer-encoding (encoding &optional type) | |
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112 | "Encode the current buffer with ENCODING for MIME type TYPE. |
113 | ENCODING can be: nil (do nothing); one of `quoted-printable', `base64'; | |
114 | `7bit', `8bit' or `binary' (all do nothing); a function to do the encoding." | |
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115 | (cond |
116 | ((eq encoding 'quoted-printable) | |
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117 | ;; This used to try to make a multibyte buffer unibyte. That's |
118 | ;; completely wrong, since you'd get QP-encoded emacs-mule. If | |
119 | ;; this gets run on multibyte text it's an error that needs | |
120 | ;; fixing, and the encoding function will signal an error. | |
121 | ;; Likewise base64 below. | |
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122 | (quoted-printable-encode-region (point-min) (point-max) t)) |
123 | ((eq encoding 'base64) | |
4a2358e9 | 124 | (when (string-match "\\`text/" type) |
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125 | (goto-char (point-min)) |
126 | (while (search-forward "\n" nil t) | |
127 | (replace-match "\r\n" t t))) | |
23f87bed | 128 | (base64-encode-region (point-min) (point-max))) |
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129 | ((memq encoding '(7bit 8bit binary)) |
130 | ;; Do nothing. | |
131 | ) | |
132 | ((null encoding) | |
133 | ;; Do nothing. | |
134 | ) | |
23f87bed | 135 | ;; Fixme: Ignoring errors here looks bogus. |
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136 | ((functionp encoding) |
137 | (ignore-errors (funcall encoding (point-min) (point-max)))) | |
138 | (t | |
23f87bed | 139 | (error "Unknown encoding %s" encoding)))) |
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140 | |
141 | (defun mm-encode-buffer (type) | |
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142 | "Encode the buffer which contains data of MIME type TYPE. |
143 | TYPE is a string or a list of the components. | |
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144 | The encoding used is returned." |
145 | (let* ((mime-type (if (stringp type) type (car type))) | |
146 | (encoding | |
147 | (or (and (listp type) | |
148 | (cadr (assq 'encoding type))) | |
149 | (mm-content-transfer-encoding mime-type))) | |
150 | (bits (mm-body-7-or-8))) | |
151 | ;; We force buffers that are 7bit to be unencoded, no matter | |
152 | ;; what the preferred encoding is. | |
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153 | ;; Only if the buffers don't contain lone lines. |
154 | (when (and (eq bits '7bit) (not (mm-long-lines-p 76))) | |
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155 | (setq encoding bits)) |
156 | (mm-encode-content-transfer-encoding encoding mime-type) | |
157 | encoding)) | |
158 | ||
159 | (defun mm-insert-headers (type encoding &optional file) | |
160 | "Insert headers for TYPE." | |
161 | (insert "Content-Type: " type) | |
162 | (when file | |
163 | (insert ";\n\tname=\"" (file-name-nondirectory file) "\"")) | |
164 | (insert "\n") | |
165 | (insert (format "Content-Transfer-Encoding: %s\n" encoding)) | |
166 | (insert "Content-Disposition: inline") | |
167 | (when file | |
168 | (insert ";\n\tfilename=\"" (file-name-nondirectory file) "\"")) | |
169 | (insert "\n") | |
170 | (insert "\n")) | |
171 | ||
172 | (defun mm-content-transfer-encoding (type) | |
173 | "Return a CTE suitable for TYPE to encode the current buffer." | |
174 | (let ((rules mm-content-transfer-encoding-defaults)) | |
175 | (catch 'found | |
176 | (while rules | |
177 | (when (string-match (caar rules) type) | |
178 | (throw 'found | |
a1506d29 | 179 | (let ((encoding |
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180 | (if (eq (cadr (car rules)) 'qp-or-base64) |
181 | (mm-qp-or-base64) | |
182 | (cadr (car rules))))) | |
183 | (if mm-use-ultra-safe-encoding | |
58a67d68 | 184 | (mm-safer-encoding encoding type) |
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185 | encoding)))) |
186 | (pop rules))))) | |
187 | ||
188 | (defun mm-qp-or-base64 () | |
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189 | "Return the type with which to encode the buffer. |
190 | This is either `base64' or `quoted-printable'." | |
191 | (if (equal mm-use-ultra-safe-encoding '(sign . "pgp")) | |
192 | ;; perhaps not always accurate? | |
193 | 'quoted-printable | |
194 | (save-excursion | |
195 | (let ((limit (min (point-max) (+ 2000 (point-min)))) | |
196 | (n8bit 0)) | |
197 | (goto-char (point-min)) | |
198 | (skip-chars-forward "\x20-\x7f\r\n\t" limit) | |
199 | (while (< (point) limit) | |
200 | (incf n8bit) | |
201 | (forward-char 1) | |
202 | (skip-chars-forward "\x20-\x7f\r\n\t" limit)) | |
203 | (if (or (< (* 6 n8bit) (- limit (point-min))) | |
204 | ;; Don't base64, say, a short line with a single | |
205 | ;; non-ASCII char when splitting parts by charset. | |
206 | (= n8bit 1)) | |
207 | 'quoted-printable | |
208 | 'base64))))) | |
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209 | |
210 | (provide 'mm-encode) | |
211 | ||
cbee283d | 212 | ;; arch-tag: 7d01bba4-d469-4851-952b-dc863f84ed66 |
c113de23 | 213 | ;;; mm-encode.el ends here |