1 ;;; mm-encode.el --- Functions for encoding MIME things
3 ;; Copyright (C) 1998-2011 Free Software Foundation, Inc.
5 ;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
6 ;; MORIOKA Tomohiko <morioka@jaist.ac.jp>
7 ;; This file is part of GNU Emacs.
9 ;; GNU Emacs is free software: you can redistribute it and/or modify
10 ;; it under the terms of the GNU General Public License as published by
11 ;; the Free Software Foundation, either version 3 of the License, or
12 ;; (at your option) any later version.
14 ;; GNU Emacs is distributed in the hope that it will be useful,
15 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
16 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 ;; GNU General Public License for more details.
19 ;; You should have received a copy of the GNU General Public License
20 ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
26 (eval-when-compile (require 'cl
))
28 (autoload 'mailcap-extension-to-mime
"mailcap")
29 (autoload 'mm-body-7-or-8
"mm-bodies")
30 (autoload 'mm-long-lines-p
"mm-bodies")
32 (defcustom mm-content-transfer-encoding-defaults
33 '(("text/x-patch" 8bit
)
34 ("text/.*" qp-or-base64
)
35 ("message/rfc822" 8bit
)
36 ("application/emacs-lisp" qp-or-base64
)
37 ("application/x-emacs-lisp" qp-or-base64
)
38 ("application/x-patch" qp-or-base64
)
40 "Alist of regexps that match MIME types and their encodings.
41 If the encoding is `qp-or-base64', then either quoted-printable
42 or base64 will be used, depending on what is more efficient.
44 This list is only consulted when encoding MIME parts in the
45 bodies -- not for the regular non-MIME-ish messages."
46 :type
'(repeat (list (regexp :tag
"MIME type")
47 (choice :tag
"encoding"
51 (const quoted-printable
)
55 (defcustom mm-sign-option nil
56 "Option how to create signed parts.
57 nil, use the default keys without asking;
58 `guided', let you select signing keys from the menu."
59 :version
"23.2" ;; No Gnus 0.12
60 :type
'(choice (item guided
)
61 (item :tag
"default" nil
))
62 :group
'mime-security
)
64 (defcustom mm-encrypt-option nil
65 "Option how to create encrypted parts.
66 nil, use the default keys without asking;
67 `guided', let you select recipients' keys from the menu."
68 :version
"23.2" ;; No Gnus 0.12
69 :type
'(choice (item guided
)
70 (item :tag
"default" nil
))
71 :group
'mime-security
)
73 (defvar mm-use-ultra-safe-encoding nil
74 "If non-nil, use encodings aimed at Procrustean bed survival.
76 This means that textual parts are encoded as quoted-printable if they
77 contain lines longer than 76 characters or starting with \"From \" in
78 the body. Non-7bit encodings (8bit, binary) are generally disallowed.
79 This is to reduce the probability that a broken MTA or MDA changes the
82 This variable should never be set directly, but bound before a call to
83 `mml-generate-mime' or similar functions.")
85 (defun mm-insert-rfc822-headers (charset encoding
)
86 "Insert text/plain headers with CHARSET and ENCODING."
87 (insert "MIME-Version: 1.0\n")
88 (insert "Content-Type: text/plain; charset="
89 (mail-quote-string (downcase (symbol-name charset
))) "\n")
90 (insert "Content-Transfer-Encoding: "
91 (downcase (symbol-name encoding
)) "\n"))
93 (defun mm-insert-multipart-headers ()
94 "Insert multipart/mixed headers."
95 (let ((boundary "=-=-="))
96 (insert "MIME-Version: 1.0\n")
97 (insert "Content-Type: multipart/mixed; boundary=\"" boundary
"\"\n")
100 (defun mm-default-file-encoding (file)
101 "Return a default encoding for FILE."
102 (if (not (string-match "\\.[^.]+$" file
))
103 "application/octet-stream"
104 (mailcap-extension-to-mime (match-string 0 file
))))
106 (defun mm-safer-encoding (encoding &optional type
)
107 "Return an encoding similar to ENCODING but safer than it."
109 ((eq encoding
'7bit
) '7bit
) ;; 7bit is considered safe.
110 ((memq encoding
'(8bit quoted-printable
))
111 ;; According to RFC2046, 5.2.1, RFC822 Subtype, "quoted-printable" is not
112 ;; a valid encoding for message/rfc822:
113 ;; No encoding other than "7bit", "8bit", or "binary" is permitted for the
114 ;; body of a "message/rfc822" entity.
115 (if (string= type
"message/rfc822") '8bit
'quoted-printable
))
116 ;; The remaining encodings are binary and base64 (and perhaps some
117 ;; non-standard ones), which are both turned into base64.
118 (t (if (string= type
"message/rfc822") 'binary
'base64
))))
120 (defun mm-encode-content-transfer-encoding (encoding &optional type
)
121 "Encode the current buffer with ENCODING for MIME type TYPE.
122 ENCODING can be: nil (do nothing); one of `quoted-printable', `base64';
123 `7bit', `8bit' or `binary' (all do nothing); a function to do the encoding."
125 ((eq encoding
'quoted-printable
)
126 ;; This used to try to make a multibyte buffer unibyte. That's
127 ;; completely wrong, since you'd get QP-encoded emacs-mule. If
128 ;; this gets run on multibyte text it's an error that needs
129 ;; fixing, and the encoding function will signal an error.
130 ;; Likewise base64 below.
131 (quoted-printable-encode-region (point-min) (point-max) t
))
132 ((eq encoding
'base64
)
133 (when (string-match "\\`text/" type
)
134 (goto-char (point-min))
135 (while (search-forward "\n" nil t
)
136 (replace-match "\r\n" t t
)))
137 (base64-encode-region (point-min) (point-max)))
138 ((memq encoding
'(7bit 8bit binary
))
144 ;; Fixme: Ignoring errors here looks bogus.
145 ((functionp encoding
)
146 (ignore-errors (funcall encoding
(point-min) (point-max))))
148 (error "Unknown encoding %s" encoding
))))
150 (defun mm-encode-buffer (type &optional encoding
)
151 "Encode the buffer which contains data of MIME type TYPE by ENCODING.
152 TYPE is a string or a list of the components.
153 The optional ENCODING overrides the encoding determined according to
154 TYPE and `mm-content-transfer-encoding-defaults'.
155 The encoding used is returned."
156 (let ((mime-type (if (stringp type
) type
(car type
))))
157 (mm-encode-content-transfer-encoding
159 (setq encoding
(or (and (listp type
)
160 (cadr (assq 'encoding type
)))
161 (mm-content-transfer-encoding mime-type
))))
165 (defun mm-insert-headers (type encoding
&optional file
)
166 "Insert headers for TYPE."
167 (insert "Content-Type: " type
)
169 (insert ";\n\tname=\"" (file-name-nondirectory file
) "\""))
171 (insert (format "Content-Transfer-Encoding: %s\n" encoding
))
172 (insert "Content-Disposition: inline")
174 (insert ";\n\tfilename=\"" (file-name-nondirectory file
) "\""))
178 (defun mm-content-transfer-encoding (type)
179 "Return a CTE suitable for TYPE to encode the current buffer."
180 (let ((rules mm-content-transfer-encoding-defaults
))
183 (when (string-match (caar rules
) type
)
186 (if (eq (cadr (car rules
)) 'qp-or-base64
)
188 (cadr (car rules
)))))
189 (if mm-use-ultra-safe-encoding
190 (mm-safer-encoding encoding type
)
194 (defun mm-qp-or-base64 ()
195 "Return the type with which to encode the buffer.
196 This is either `base64' or `quoted-printable'."
197 (if (equal mm-use-ultra-safe-encoding
'(sign .
"pgp"))
198 ;; perhaps not always accurate?
201 (let ((limit (min (point-max) (+ 2000 (point-min))))
203 (goto-char (point-min))
204 (skip-chars-forward "\x20-\x7f\r\n\t" limit
)
205 (while (< (point) limit
)
208 (skip-chars-forward "\x20-\x7f\r\n\t" limit
))
209 (if (or (< (* 6 n8bit
) (- limit
(point-min)))
210 ;; Don't base64, say, a short line with a single
211 ;; non-ASCII char when splitting parts by charset.
218 ;;; mm-encode.el ends here