1 ;;; mm-encode.el --- Functions for encoding MIME things
3 ;; Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004,
4 ;; 2005, 2006, 2007, 2008 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, or (at your option)
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; see the file COPYING. If not, write to the
22 ;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
23 ;; Boston, MA 02110-1301, USA.
29 (eval-when-compile (require 'cl
))
33 (autoload 'mm-body-7-or-8
"mm-bodies")
34 (autoload 'mm-long-lines-p
"mm-bodies"))
36 (defcustom mm-content-transfer-encoding-defaults
37 '(("text/x-patch" 8bit
)
38 ("text/.*" qp-or-base64
)
39 ("message/rfc822" 8bit
)
40 ("application/emacs-lisp" qp-or-base64
)
41 ("application/x-emacs-lisp" qp-or-base64
)
42 ("application/x-patch" qp-or-base64
)
44 "Alist of regexps that match MIME types and their encodings.
45 If the encoding is `qp-or-base64', then either quoted-printable
46 or base64 will be used, depending on what is more efficient.
48 `qp-or-base64' has another effect. It will fold long lines so that
49 MIME parts may not be broken by MTA. So do `quoted-printable' and
52 Note: It affects body encoding only when a part is a raw forwarded
53 message (which will be made by `gnus-summary-mail-forward' with the
54 arg 2 for example) or is neither the text/* type nor the message/*
55 type. Even though in those cases, you can use the `encoding' MML tag
56 to specify encoding of non-ASCII MIME parts."
57 :type
'(repeat (list (regexp :tag
"MIME type")
58 (choice :tag
"encoding"
62 (const quoted-printable
)
66 (defvar mm-use-ultra-safe-encoding nil
67 "If non-nil, use encodings aimed at Procrustean bed survival.
69 This means that textual parts are encoded as quoted-printable if they
70 contain lines longer than 76 characters or starting with \"From \" in
71 the body. Non-7bit encodings (8bit, binary) are generally disallowed.
72 This is to reduce the probability that a broken MTA or MDA changes the
75 This variable should never be set directly, but bound before a call to
76 `mml-generate-mime' or similar functions.")
78 (defun mm-insert-rfc822-headers (charset encoding
)
79 "Insert text/plain headers with CHARSET and ENCODING."
80 (insert "MIME-Version: 1.0\n")
81 (insert "Content-Type: text/plain; charset="
82 (mail-quote-string (downcase (symbol-name charset
))) "\n")
83 (insert "Content-Transfer-Encoding: "
84 (downcase (symbol-name encoding
)) "\n"))
86 (defun mm-insert-multipart-headers ()
87 "Insert multipart/mixed headers."
88 (let ((boundary "=-=-="))
89 (insert "MIME-Version: 1.0\n")
90 (insert "Content-Type: multipart/mixed; boundary=\"" boundary
"\"\n")
93 (defun mm-default-file-encoding (file)
94 "Return a default encoding for FILE."
95 (if (not (string-match "\\.[^.]+$" file
))
96 "application/octet-stream"
97 (mailcap-extension-to-mime (match-string 0 file
))))
99 (defun mm-safer-encoding (encoding &optional type
)
100 "Return an encoding similar to ENCODING but safer than it."
102 ((eq encoding
'7bit
) '7bit
) ;; 7bit is considered safe.
103 ((memq encoding
'(8bit quoted-printable
))
104 ;; According to RFC2046, 5.2.1, RFC822 Subtype, "quoted-printable" is not
105 ;; a valid encoding for message/rfc822:
106 ;; No encoding other than "7bit", "8bit", or "binary" is permitted for the
107 ;; body of a "message/rfc822" entity.
108 (if (string= type
"message/rfc822") '8bit
'quoted-printable
))
109 ;; The remaining encodings are binary and base64 (and perhaps some
110 ;; non-standard ones), which are both turned into base64.
111 (t (if (string= type
"message/rfc822") 'binary
'base64
))))
113 (defun mm-encode-content-transfer-encoding (encoding &optional type
)
114 "Encode the current buffer with ENCODING for MIME type TYPE.
115 ENCODING can be: nil (do nothing); one of `quoted-printable', `base64';
116 `7bit', `8bit' or `binary' (all do nothing); a function to do the encoding."
118 ((eq encoding
'quoted-printable
)
119 ;; This used to try to make a multibyte buffer unibyte. That's
120 ;; completely wrong, since you'd get QP-encoded emacs-mule. If
121 ;; this gets run on multibyte text it's an error that needs
122 ;; fixing, and the encoding function will signal an error.
123 ;; Likewise base64 below.
124 (quoted-printable-encode-region (point-min) (point-max) t
))
125 ((eq encoding
'base64
)
126 (when (string-match "\\`text/" type
)
127 (goto-char (point-min))
128 (while (search-forward "\n" nil t
)
129 (replace-match "\r\n" t t
)))
130 (base64-encode-region (point-min) (point-max)))
131 ((memq encoding
'(7bit 8bit binary
))
137 ;; Fixme: Ignoring errors here looks bogus.
138 ((functionp encoding
)
139 (ignore-errors (funcall encoding
(point-min) (point-max))))
141 (error "Unknown encoding %s" encoding
))))
143 (defun mm-encode-buffer (type)
144 "Encode the buffer which contains data of MIME type TYPE.
145 TYPE is a string or a list of the components.
146 The encoding used is returned."
147 (let* ((mime-type (if (stringp type
) type
(car type
)))
149 (or (and (listp type
)
150 (cadr (assq 'encoding type
)))
151 (mm-content-transfer-encoding mime-type
)))
152 (bits (mm-body-7-or-8)))
153 ;; We force buffers that are 7bit to be unencoded, no matter
154 ;; what the preferred encoding is.
155 ;; Only if the buffers don't contain lone lines.
156 (when (and (eq bits
'7bit
) (not (mm-long-lines-p 76)))
157 (setq encoding bits
))
158 (mm-encode-content-transfer-encoding encoding mime-type
)
161 (defun mm-insert-headers (type encoding
&optional file
)
162 "Insert headers for TYPE."
163 (insert "Content-Type: " type
)
165 (insert ";\n\tname=\"" (file-name-nondirectory file
) "\""))
167 (insert (format "Content-Transfer-Encoding: %s\n" encoding
))
168 (insert "Content-Disposition: inline")
170 (insert ";\n\tfilename=\"" (file-name-nondirectory file
) "\""))
174 (defun mm-content-transfer-encoding (type)
175 "Return a CTE suitable for TYPE to encode the current buffer."
176 (let ((rules mm-content-transfer-encoding-defaults
))
179 (when (string-match (caar rules
) type
)
182 (if (eq (cadr (car rules
)) 'qp-or-base64
)
184 (cadr (car rules
)))))
185 (if mm-use-ultra-safe-encoding
186 (mm-safer-encoding encoding type
)
190 (defun mm-qp-or-base64 ()
191 "Return the type with which to encode the buffer.
192 This is either `base64' or `quoted-printable'."
193 (if (equal mm-use-ultra-safe-encoding
'(sign .
"pgp"))
194 ;; perhaps not always accurate?
197 (let ((limit (min (point-max) (+ 2000 (point-min))))
199 (goto-char (point-min))
200 (skip-chars-forward "\x20-\x7f\r\n\t" limit
)
201 (while (< (point) limit
)
204 (skip-chars-forward "\x20-\x7f\r\n\t" limit
))
205 (if (or (< (* 6 n8bit
) (- limit
(point-min)))
206 ;; Don't base64, say, a short line with a single
207 ;; non-ASCII char when splitting parts by charset.
214 ;; arch-tag: 7d01bba4-d469-4851-952b-dc863f84ed66
215 ;;; mm-encode.el ends here