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c113de23 GM |
1 | ;;; mm-encode.el --- Functions for encoding MIME things |
2 | ;; Copyright (C) 1998, 1999, 2000 Free Software Foundation, Inc. | |
3 | ||
4 | ;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org> | |
5 | ;; MORIOKA Tomohiko <morioka@jaist.ac.jp> | |
6 | ;; This file is part of GNU Emacs. | |
7 | ||
8 | ;; GNU Emacs is free software; you can redistribute it and/or modify | |
9 | ;; it under the terms of the GNU General Public License as published by | |
10 | ;; the Free Software Foundation; either version 2, or (at your option) | |
11 | ;; any later version. | |
12 | ||
13 | ;; GNU Emacs is distributed in the hope that it will be useful, | |
14 | ;; but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | ;; GNU General Public License for more details. | |
17 | ||
18 | ;; You should have received a copy of the GNU General Public License | |
19 | ;; along with GNU Emacs; see the file COPYING. If not, write to the | |
20 | ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330, | |
21 | ;; Boston, MA 02111-1307, USA. | |
22 | ||
23 | ;;; Commentary: | |
24 | ||
25 | ;;; Code: | |
26 | ||
b28ce55a | 27 | (eval-when-compile (require 'cl)) |
c113de23 GM |
28 | (require 'mail-parse) |
29 | (require 'mailcap) | |
30 | ||
31 | (defvar mm-content-transfer-encoding-defaults | |
32 | '(("text/x-patch" 8bit) | |
33 | ("text/.*" qp-or-base64) | |
34 | ("message/rfc822" 8bit) | |
35 | ("application/emacs-lisp" 8bit) | |
36 | ("application/x-patch" 8bit) | |
37 | (".*" qp-or-base64)) | |
38 | "Alist of regexps that match MIME types and their encodings. | |
39 | If the encoding is `qp-or-base64', then either quoted-printable | |
40 | or base64 will be used, depending on what is more efficient.") | |
41 | ||
42 | (defvar mm-use-ultra-safe-encoding nil | |
43 | "If non-nil, use encodings aimed at Procrustean bed survival. | |
44 | ||
45 | This means that textual parts are encoded as quoted-printable if they | |
46 | contain lines longer than 76 characters or starting with \"From \" in | |
47 | the body. Non-7bit encodings (8bit, binary) are generally disallowed. | |
48 | This is to reduce the probability that a broken MTA or MDA changes the | |
49 | message. | |
50 | ||
51 | This variable should never be set directly, but bound before a call to | |
52 | `mml-generate-mime' or similar functions.") | |
53 | ||
54 | (defun mm-insert-rfc822-headers (charset encoding) | |
55 | "Insert text/plain headers with CHARSET and ENCODING." | |
56 | (insert "MIME-Version: 1.0\n") | |
57 | (insert "Content-Type: text/plain; charset=" | |
58 | (mail-quote-string (downcase (symbol-name charset))) "\n") | |
59 | (insert "Content-Transfer-Encoding: " | |
60 | (downcase (symbol-name encoding)) "\n")) | |
61 | ||
62 | (defun mm-insert-multipart-headers () | |
63 | "Insert multipart/mixed headers." | |
64 | (let ((boundary "=-=-=")) | |
65 | (insert "MIME-Version: 1.0\n") | |
66 | (insert "Content-Type: multipart/mixed; boundary=\"" boundary "\"\n") | |
67 | boundary)) | |
68 | ||
69 | (defun mm-default-file-encoding (file) | |
70 | "Return a default encoding for FILE." | |
71 | (if (not (string-match "\\.[^.]+$" file)) | |
72 | "application/octet-stream" | |
73 | (mailcap-extension-to-mime (match-string 0 file)))) | |
74 | ||
75 | (defun mm-safer-encoding (encoding) | |
76 | "Return a safer but similar encoding." | |
77 | (cond | |
78 | ((memq encoding '(7bit 8bit quoted-printable)) 'quoted-printable) | |
79 | ;; The remaing encodings are binary and base64 (and perhaps some | |
80 | ;; non-standard ones), which are both turned into base64. | |
81 | (t 'base64))) | |
82 | ||
83 | (defun mm-encode-content-transfer-encoding (encoding &optional type) | |
84 | (cond | |
85 | ((eq encoding 'quoted-printable) | |
86 | (quoted-printable-encode-region (point-min) (point-max) t)) | |
87 | ((eq encoding 'base64) | |
88 | (when (equal type "text/plain") | |
89 | (goto-char (point-min)) | |
90 | (while (search-forward "\n" nil t) | |
91 | (replace-match "\r\n" t t))) | |
92 | (condition-case error | |
93 | (base64-encode-region (point-min) (point-max)) | |
94 | (error | |
95 | (message "Error while decoding: %s" error) | |
96 | nil))) | |
97 | ((memq encoding '(7bit 8bit binary)) | |
98 | ;; Do nothing. | |
99 | ) | |
100 | ((null encoding) | |
101 | ;; Do nothing. | |
102 | ) | |
103 | ((functionp encoding) | |
104 | (ignore-errors (funcall encoding (point-min) (point-max)))) | |
105 | (t | |
106 | (message "Unknown encoding %s; defaulting to 8bit" encoding)))) | |
107 | ||
108 | (defun mm-encode-buffer (type) | |
109 | "Encode the buffer which contains data of TYPE. | |
110 | The encoding used is returned." | |
111 | (let* ((mime-type (if (stringp type) type (car type))) | |
112 | (encoding | |
113 | (or (and (listp type) | |
114 | (cadr (assq 'encoding type))) | |
115 | (mm-content-transfer-encoding mime-type))) | |
116 | (bits (mm-body-7-or-8))) | |
117 | ;; We force buffers that are 7bit to be unencoded, no matter | |
118 | ;; what the preferred encoding is. | |
119 | (when (eq bits '7bit) | |
120 | (setq encoding bits)) | |
121 | (mm-encode-content-transfer-encoding encoding mime-type) | |
122 | encoding)) | |
123 | ||
124 | (defun mm-insert-headers (type encoding &optional file) | |
125 | "Insert headers for TYPE." | |
126 | (insert "Content-Type: " type) | |
127 | (when file | |
128 | (insert ";\n\tname=\"" (file-name-nondirectory file) "\"")) | |
129 | (insert "\n") | |
130 | (insert (format "Content-Transfer-Encoding: %s\n" encoding)) | |
131 | (insert "Content-Disposition: inline") | |
132 | (when file | |
133 | (insert ";\n\tfilename=\"" (file-name-nondirectory file) "\"")) | |
134 | (insert "\n") | |
135 | (insert "\n")) | |
136 | ||
137 | (defun mm-content-transfer-encoding (type) | |
138 | "Return a CTE suitable for TYPE to encode the current buffer." | |
139 | (let ((rules mm-content-transfer-encoding-defaults)) | |
140 | (catch 'found | |
141 | (while rules | |
142 | (when (string-match (caar rules) type) | |
143 | (throw 'found | |
144 | (let ((encoding | |
145 | (if (eq (cadr (car rules)) 'qp-or-base64) | |
146 | (mm-qp-or-base64) | |
147 | (cadr (car rules))))) | |
148 | (if mm-use-ultra-safe-encoding | |
149 | (mm-safer-encoding encoding) | |
150 | encoding)))) | |
151 | (pop rules))))) | |
152 | ||
153 | (defun mm-qp-or-base64 () | |
154 | (save-excursion | |
155 | (let ((limit (min (point-max) (+ 2000 (point-min)))) | |
156 | (n8bit 0)) | |
157 | (goto-char (point-min)) | |
158 | (skip-chars-forward "\x20-\x7f\r\n\t" limit) | |
159 | (while (< (point) limit) | |
160 | (incf n8bit) | |
161 | (forward-char 1) | |
162 | (skip-chars-forward "\x20-\x7f\r\n\t" limit)) | |
163 | (if (< (* 6 n8bit) (- limit (point-min))) | |
164 | 'quoted-printable | |
165 | 'base64)))) | |
166 | ||
167 | (provide 'mm-encode) | |
168 | ||
169 | ;;; mm-encode.el ends here |