1 ;;; mm-encode.el --- Functions for encoding MIME things
2 ;; Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003
3 ;; 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 2, or (at your option)
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; see the file COPYING. If not, write to the
21 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
22 ;; Boston, MA 02111-1307, USA.
28 (eval-when-compile (require 'cl))
30 (require 'gnus-mailcap)
32 (autoload 'mm-body-7-or-8 "mm-bodies")
33 (autoload 'mm-long-lines-p "mm-bodies"))
35 (defcustom mm-content-transfer-encoding-defaults
36 '(("text/x-patch" 8bit)
37 ("text/.*" qp-or-base64)
38 ("message/rfc822" 8bit)
39 ("application/emacs-lisp" 8bit)
40 ("application/x-emacs-lisp" 8bit)
41 ("application/x-patch" 8bit)
43 "Alist of regexps that match MIME types and their encodings.
44 If the encoding is `qp-or-base64', then either quoted-printable
45 or base64 will be used, depending on what is more efficient."
46 :type '(repeat (list (regexp :tag "MIME type")
47 (choice :tag "encoding"
51 (const quoted-printable)
55 (defvar mm-use-ultra-safe-encoding nil
56 "If non-nil, use encodings aimed at Procrustean bed survival.
58 This means that textual parts are encoded as quoted-printable if they
59 contain lines longer than 76 characters or starting with \"From \" in
60 the body. Non-7bit encodings (8bit, binary) are generally disallowed.
61 This is to reduce the probability that a broken MTA or MDA changes the
64 This variable should never be set directly, but bound before a call to
65 `mml-generate-mime' or similar functions.")
67 (defun mm-insert-rfc822-headers (charset encoding)
68 "Insert text/plain headers with CHARSET and ENCODING."
69 (insert "MIME-Version: 1.0\n")
70 (insert "Content-Type: text/plain; charset="
71 (mail-quote-string (downcase (symbol-name charset))) "\n")
72 (insert "Content-Transfer-Encoding: "
73 (downcase (symbol-name encoding)) "\n"))
75 (defun mm-insert-multipart-headers ()
76 "Insert multipart/mixed headers."
77 (let ((boundary "=-=-="))
78 (insert "MIME-Version: 1.0\n")
79 (insert "Content-Type: multipart/mixed; boundary=\"" boundary "\"\n")
82 (defun mm-default-file-encoding (file)
83 "Return a default encoding for FILE."
84 (if (not (string-match "\\.[^.]+$" file))
85 "application/octet-stream"
86 (mailcap-extension-to-mime (match-string 0 file))))
88 (defun mm-safer-encoding (encoding)
89 "Return an encoding similar to ENCODING but safer than it."
91 ((memq encoding '(7bit 8bit quoted-printable)) 'quoted-printable)
92 ;; The remaining encodings are binary and base64 (and perhaps some
93 ;; non-standard ones), which are both turned into base64.
96 (defun mm-encode-content-transfer-encoding (encoding &optional type)
97 "Encode the current buffer with ENCODING for MIME type TYPE.
98 ENCODING can be: nil (do nothing); one of `quoted-printable', `base64';
99 `7bit', `8bit' or `binary' (all do nothing); a function to do the encoding."
101 ((eq encoding 'quoted-printable)
102 ;; This used to try to make a multibyte buffer unibyte. That's
103 ;; completely wrong, since you'd get QP-encoded emacs-mule. If
104 ;; this gets run on multibyte text it's an error that needs
105 ;; fixing, and the encoding function will signal an error.
106 ;; Likewise base64 below.
107 (quoted-printable-encode-region (point-min) (point-max) t))
108 ((eq encoding 'base64)
109 (when (equal type "text/plain")
110 (goto-char (point-min))
111 (while (search-forward "\n" nil t)
112 (replace-match "\r\n" t t)))
113 (base64-encode-region (point-min) (point-max)))
114 ((memq encoding '(7bit 8bit binary))
120 ;; Fixme: Ignoring errors here looks bogus.
121 ((functionp encoding)
122 (ignore-errors (funcall encoding (point-min) (point-max))))
124 (error "Unknown encoding %s" encoding))))
126 (defun mm-encode-buffer (type)
127 "Encode the buffer which contains data of MIME type TYPE.
128 TYPE is a string or a list of the components.
129 The encoding used is returned."
130 (let* ((mime-type (if (stringp type) type (car type)))
132 (or (and (listp type)
133 (cadr (assq 'encoding type)))
134 (mm-content-transfer-encoding mime-type)))
135 (bits (mm-body-7-or-8)))
136 ;; We force buffers that are 7bit to be unencoded, no matter
137 ;; what the preferred encoding is.
138 ;; Only if the buffers don't contain lone lines.
139 (when (and (eq bits '7bit) (not (mm-long-lines-p 76)))
140 (setq encoding bits))
141 (mm-encode-content-transfer-encoding encoding mime-type)
144 (defun mm-insert-headers (type encoding &optional file)
145 "Insert headers for TYPE."
146 (insert "Content-Type: " type)
148 (insert ";\n\tname=\"" (file-name-nondirectory file) "\""))
150 (insert (format "Content-Transfer-Encoding: %s\n" encoding))
151 (insert "Content-Disposition: inline")
153 (insert ";\n\tfilename=\"" (file-name-nondirectory file) "\""))
157 (defun mm-content-transfer-encoding (type)
158 "Return a CTE suitable for TYPE to encode the current buffer."
159 (let ((rules mm-content-transfer-encoding-defaults))
162 (when (string-match (caar rules) type)
165 (if (eq (cadr (car rules)) 'qp-or-base64)
167 (cadr (car rules)))))
168 (if mm-use-ultra-safe-encoding
169 (mm-safer-encoding encoding)
173 (defun mm-qp-or-base64 ()
174 "Return the type with which to encode the buffer.
175 This is either `base64' or `quoted-printable'."
176 (if (equal mm-use-ultra-safe-encoding '(sign . "pgp"))
177 ;; perhaps not always accurate?
180 (let ((limit (min (point-max) (+ 2000 (point-min))))
182 (goto-char (point-min))
183 (skip-chars-forward "\x20-\x7f\r\n\t" limit)
184 (while (< (point) limit)
187 (skip-chars-forward "\x20-\x7f\r\n\t" limit))
188 (if (or (< (* 6 n8bit) (- limit (point-min)))
189 ;; Don't base64, say, a short line with a single
190 ;; non-ASCII char when splitting parts by charset.
197 ;;; mm-encode.el ends here