1 ;;; mm-encode.el --- Functions for encoding MIME things
3 ;; Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004,
4 ;; 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
6 ;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
7 ;; MORIOKA Tomohiko <morioka@jaist.ac.jp>
8 ;; This file is part of GNU Emacs.
10 ;; GNU Emacs is free software: you can redistribute it and/or modify
11 ;; it under the terms of the GNU General Public License as published by
12 ;; the Free Software Foundation, either version 3 of the License, or
13 ;; (at your option) any later version.
15 ;; GNU Emacs is distributed in the hope that it will be useful,
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.
20 ;; You should have received a copy of the GNU General Public License
21 ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
27 (eval-when-compile (require 'cl))
30 (autoload 'mm-body-7-or-8 "mm-bodies")
31 (autoload 'mm-long-lines-p "mm-bodies")
33 (defcustom mm-content-transfer-encoding-defaults
34 '(("text/x-patch" 8bit)
35 ("text/.*" qp-or-base64)
36 ("message/rfc822" 8bit)
37 ("application/emacs-lisp" qp-or-base64)
38 ("application/x-emacs-lisp" qp-or-base64)
39 ("application/x-patch" qp-or-base64)
41 "Alist of regexps that match MIME types and their encodings.
42 If the encoding is `qp-or-base64', then either quoted-printable
43 or base64 will be used, depending on what is more efficient.
45 `qp-or-base64' has another effect. It will fold long lines so that
46 MIME parts may not be broken by MTA. So do `quoted-printable' and
49 Note: It affects body encoding only when a part is a raw forwarded
50 message (which will be made by `gnus-summary-mail-forward' with the
51 arg 2 for example) or is neither the text/* type nor the message/*
52 type. Even though in those cases, you can use the `encoding' MML tag
53 to specify encoding of non-ASCII MIME parts."
54 :type '(repeat (list (regexp :tag "MIME type")
55 (choice :tag "encoding"
59 (const quoted-printable)
63 (defcustom mm-sign-option nil
64 "Option how to create signed parts.
65 nil, use the default keys without asking;
66 `guided', let you select signing keys from the menu."
68 :type '(choice (item guided)
69 (item :tag "default" nil))
70 :group 'mime-security)
72 (defcustom mm-encrypt-option nil
73 "Option how to create encrypted parts.
74 nil, use the default keys without asking;
75 `guided', let you select recipients' keys from the menu."
77 :type '(choice (item guided)
78 (item :tag "default" nil))
79 :group 'mime-security)
81 (defvar mm-use-ultra-safe-encoding nil
82 "If non-nil, use encodings aimed at Procrustean bed survival.
84 This means that textual parts are encoded as quoted-printable if they
85 contain lines longer than 76 characters or starting with \"From \" in
86 the body. Non-7bit encodings (8bit, binary) are generally disallowed.
87 This is to reduce the probability that a broken MTA or MDA changes the
90 This variable should never be set directly, but bound before a call to
91 `mml-generate-mime' or similar functions.")
93 (defun mm-insert-rfc822-headers (charset encoding)
94 "Insert text/plain headers with CHARSET and ENCODING."
95 (insert "MIME-Version: 1.0\n")
96 (insert "Content-Type: text/plain; charset="
97 (mail-quote-string (downcase (symbol-name charset))) "\n")
98 (insert "Content-Transfer-Encoding: "
99 (downcase (symbol-name encoding)) "\n"))
101 (defun mm-insert-multipart-headers ()
102 "Insert multipart/mixed headers."
103 (let ((boundary "=-=-="))
104 (insert "MIME-Version: 1.0\n")
105 (insert "Content-Type: multipart/mixed; boundary=\"" boundary "\"\n")
108 (defun mm-default-file-encoding (file)
109 "Return a default encoding for FILE."
110 (if (not (string-match "\\.[^.]+$" file))
111 "application/octet-stream"
112 (mailcap-extension-to-mime (match-string 0 file))))
114 (defun mm-safer-encoding (encoding &optional type)
115 "Return an encoding similar to ENCODING but safer than it."
117 ((eq encoding '7bit) '7bit) ;; 7bit is considered safe.
118 ((memq encoding '(8bit quoted-printable))
119 ;; According to RFC2046, 5.2.1, RFC822 Subtype, "quoted-printable" is not
120 ;; a valid encoding for message/rfc822:
121 ;; No encoding other than "7bit", "8bit", or "binary" is permitted for the
122 ;; body of a "message/rfc822" entity.
123 (if (string= type "message/rfc822") '8bit 'quoted-printable))
124 ;; The remaining encodings are binary and base64 (and perhaps some
125 ;; non-standard ones), which are both turned into base64.
126 (t (if (string= type "message/rfc822") 'binary 'base64))))
128 (defun mm-encode-content-transfer-encoding (encoding &optional type)
129 "Encode the current buffer with ENCODING for MIME type TYPE.
130 ENCODING can be: nil (do nothing); one of `quoted-printable', `base64';
131 `7bit', `8bit' or `binary' (all do nothing); a function to do the encoding."
133 ((eq encoding 'quoted-printable)
134 ;; This used to try to make a multibyte buffer unibyte. That's
135 ;; completely wrong, since you'd get QP-encoded emacs-mule. If
136 ;; this gets run on multibyte text it's an error that needs
137 ;; fixing, and the encoding function will signal an error.
138 ;; Likewise base64 below.
139 (quoted-printable-encode-region (point-min) (point-max) t))
140 ((eq encoding 'base64)
141 (when (string-match "\\`text/" type)
142 (goto-char (point-min))
143 (while (search-forward "\n" nil t)
144 (replace-match "\r\n" t t)))
145 (base64-encode-region (point-min) (point-max)))
146 ((memq encoding '(7bit 8bit binary))
152 ;; Fixme: Ignoring errors here looks bogus.
153 ((functionp encoding)
154 (ignore-errors (funcall encoding (point-min) (point-max))))
156 (error "Unknown encoding %s" encoding))))
158 (defun mm-encode-buffer (type &optional encoding)
159 "Encode the buffer which contains data of MIME type TYPE by ENCODING.
160 TYPE is a string or a list of the components.
161 The optional ENCODING overrides the encoding determined according to
162 TYPE and `mm-content-transfer-encoding-defaults'.
163 The encoding used is returned."
164 (let ((mime-type (if (stringp type) type (car type))))
165 (mm-encode-content-transfer-encoding
167 (setq encoding (or (and (listp type)
168 (cadr (assq 'encoding type)))
169 (mm-content-transfer-encoding mime-type))))
173 (defun mm-insert-headers (type encoding &optional file)
174 "Insert headers for TYPE."
175 (insert "Content-Type: " type)
177 (insert ";\n\tname=\"" (file-name-nondirectory file) "\""))
179 (insert (format "Content-Transfer-Encoding: %s\n" encoding))
180 (insert "Content-Disposition: inline")
182 (insert ";\n\tfilename=\"" (file-name-nondirectory file) "\""))
186 (defun mm-content-transfer-encoding (type)
187 "Return a CTE suitable for TYPE to encode the current buffer."
188 (let ((rules mm-content-transfer-encoding-defaults))
191 (when (string-match (caar rules) type)
194 (if (eq (cadr (car rules)) 'qp-or-base64)
196 (cadr (car rules)))))
197 (if mm-use-ultra-safe-encoding
198 (mm-safer-encoding encoding type)
202 (defun mm-qp-or-base64 ()
203 "Return the type with which to encode the buffer.
204 This is either `base64' or `quoted-printable'."
205 (if (equal mm-use-ultra-safe-encoding '(sign . "pgp"))
206 ;; perhaps not always accurate?
209 (let ((limit (min (point-max) (+ 2000 (point-min))))
211 (goto-char (point-min))
212 (skip-chars-forward "\x20-\x7f\r\n\t" limit)
213 (while (< (point) limit)
216 (skip-chars-forward "\x20-\x7f\r\n\t" limit))
217 (if (or (< (* 6 n8bit) (- limit (point-min)))
218 ;; Don't base64, say, a short line with a single
219 ;; non-ASCII char when splitting parts by charset.
226 ;; arch-tag: 7d01bba4-d469-4851-952b-dc863f84ed66
227 ;;; mm-encode.el ends here