1;;; mm-bodies.el --- Functions for decoding MIME things
2
3;; Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004,
4;;   2005, 2006, 2007 Free Software Foundation, Inc.
5
6;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
7;;	MORIOKA Tomohiko <morioka@jaist.ac.jp>
8;; This file is part of GNU Emacs.
9
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 2, or (at your option)
13;; any later version.
14
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.
19
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.
24
25;;; Commentary:
26
27;;; Code:
28
29(eval-and-compile
30  (or (fboundp  'base64-decode-region)
31      (require 'base64)))
32
33(eval-when-compile
34  (defvar mm-uu-decode-function)
35  (defvar mm-uu-binhex-decode-function))
36
37(require 'mm-util)
38(require 'rfc2047)
39(require 'mm-encode)
40
41;; 8bit treatment gets any char except: 0x32 - 0x7f, LF, TAB, BEL,
42;; BS, vertical TAB, form feed, and ^_
43;;
44;; Note that CR is *not* included, as that would allow a non-paired CR
45;; in the body contrary to RFC 2822:
46;;
47;;   - CR and LF MUST only occur together as CRLF; they MUST NOT
48;;     appear independently in the body.
49
50(defvar mm-7bit-chars "\x20-\x7f\n\t\x7\x8\xb\xc\x1f")
51
52(defcustom mm-body-charset-encoding-alist
53  '((iso-2022-jp . 7bit)
54    (iso-2022-jp-2 . 7bit)
55    ;; We MUST encode UTF-16 because it can contain \0's which is
56    ;; known to break servers.
57    ;; Note: UTF-16 variants are invalid for text parts [RFC 2781],
58    ;; so this can't happen :-/.
59    ;; PPS: Yes, it can happen if the user specifies UTF-16 in the MML
60    ;; markup. - jh.
61    (utf-16 . base64)
62    (utf-16be . base64)
63    (utf-16le . base64))
64  "Alist of MIME charsets to encodings.
65Valid encodings are `7bit', `8bit', `quoted-printable' and `base64'."
66  :type '(repeat (cons (symbol :tag "charset")
67		       (choice :tag "encoding"
68			       (const 7bit)
69			       (const 8bit)
70			       (const quoted-printable)
71			       (const base64))))
72  :group 'mime)
73
74(defun mm-encode-body (&optional charset)
75  "Encode a body.
76Should be called narrowed to the body that is to be encoded.
77If there is more than one non-ASCII MULE charset in the body, then the
78list of MULE charsets found is returned.
79If CHARSET is non-nil, it is used as the MIME charset to encode the body.
80If successful, the MIME charset is returned.
81If no encoding was done, nil is returned."
82  (if (not (mm-multibyte-p))
83      ;; In the non-Mule case, we search for non-ASCII chars and
84      ;; return the value of `mail-parse-charset' if any are found.
85      (or charset
86	  (save-excursion
87	    (goto-char (point-min))
88	    (if (re-search-forward "[^\x0-\x7f]" nil t)
89		(or mail-parse-charset
90		    (message-options-get 'mm-encody-body-charset)
91		    (message-options-set
92		     'mm-encody-body-charset
93		     (mm-read-coding-system "Charset used in the article: ")))
94	      ;; The logic in `mml-generate-mime-1' confirms that it's OK
95	      ;; to return nil here.
96	      nil)))
97    (save-excursion
98      (if charset
99	  (progn
100	    (mm-encode-coding-region (point-min) (point-max)
101				     (mm-charset-to-coding-system charset))
102	    charset)
103	(goto-char (point-min))
104	(let ((charsets (mm-find-mime-charset-region (point-min) (point-max)
105						     mm-hack-charsets)))
106	  (cond
107	   ;; No encoding.
108	   ((null charsets)
109	    nil)
110	   ;; Too many charsets.
111	   ((> (length charsets) 1)
112	    charsets)
113	   ;; We encode.
114	   (t
115	    (prog1
116		(setq charset (car charsets))
117	      (mm-encode-coding-region (point-min) (point-max)
118				       (mm-charset-to-coding-system charset))))
119	   ))))))
120
121(defun mm-long-lines-p (length)
122  "Say whether any of the lines in the buffer is longer than LENGTH."
123  (save-excursion
124    (goto-char (point-min))
125    (end-of-line)
126    (while (and (not (eobp))
127		(not (> (current-column) length)))
128      (forward-line 1)
129      (end-of-line))
130    (and (> (current-column) length)
131	 (current-column))))
132
133(defvar message-posting-charset)
134
135(defun mm-body-encoding (charset &optional encoding)
136  "Do Content-Transfer-Encoding and return the encoding of the current buffer."
137  (when (stringp encoding)
138    (setq encoding (intern (downcase encoding))))
139  (let ((bits (mm-body-7-or-8))
140	(longp (mm-long-lines-p 1000)))
141    (require 'message)
142    (cond
143     ((and (not longp)
144	   (not (and mm-use-ultra-safe-encoding
145		     (or (save-excursion (re-search-forward " $" nil t))
146			 (save-excursion (re-search-forward "^From " nil t)))))
147	   (eq bits '7bit))
148      bits)
149     ((and (not mm-use-ultra-safe-encoding)
150	   (not longp)
151	   (not (cdr (assq charset mm-body-charset-encoding-alist)))
152	   (or (eq t (cdr message-posting-charset))
153	       (memq charset (cdr message-posting-charset))
154	       (eq charset mail-parse-charset)))
155      bits)
156     (t
157      (let ((encoding (or encoding
158			  (cdr (assq charset mm-body-charset-encoding-alist))
159			  (mm-qp-or-base64))))
160	(when mm-use-ultra-safe-encoding
161	  (setq encoding (mm-safer-encoding encoding)))
162	(mm-encode-content-transfer-encoding encoding "text/plain")
163	encoding)))))
164
165(defun mm-body-7-or-8 ()
166  "Say whether the body is 7bit or 8bit."
167  (if (save-excursion
168	(goto-char (point-min))
169	(skip-chars-forward mm-7bit-chars)
170	(eobp))
171      '7bit
172    '8bit))
173
174;;;
175;;; Functions for decoding
176;;;
177
178(eval-when-compile (defvar mm-uu-yenc-decode-function))
179
180(defun mm-decode-content-transfer-encoding (encoding &optional type)
181  "Decodes buffer encoded with ENCODING, returning success status.
182If TYPE is `text/plain' CRLF->LF translation may occur."
183  (prog1
184      (condition-case error
185	  (cond
186	   ((eq encoding 'quoted-printable)
187	    (quoted-printable-decode-region (point-min) (point-max))
188	    t)
189	   ((eq encoding 'base64)
190	    (base64-decode-region
191	     (point-min)
192	     ;; Some mailers insert whitespace
193	     ;; junk at the end which
194	     ;; base64-decode-region dislikes.
195	     ;; Also remove possible junk which could
196	     ;; have been added by mailing list software.
197	     (save-excursion
198	       (goto-char (point-min))
199	       (while (re-search-forward "^[\t ]*\r?\n" nil t)
200		 (delete-region (match-beginning 0) (match-end 0)))
201	       (goto-char (point-max))
202	       (when (re-search-backward "^[A-Za-z0-9+/]+=*[\t ]*$" nil t)
203		 (forward-line))
204	       (point))))
205	   ((memq encoding '(7bit 8bit binary))
206	    ;; Do nothing.
207	    t)
208	   ((null encoding)
209	    ;; Do nothing.
210	    t)
211	   ((memq encoding '(x-uuencode x-uue))
212	    (require 'mm-uu)
213	    (funcall mm-uu-decode-function (point-min) (point-max))
214	    t)
215	   ((eq encoding 'x-binhex)
216	    (require 'mm-uu)
217	    (funcall mm-uu-binhex-decode-function (point-min) (point-max))
218	    t)
219	   ((eq encoding 'x-yenc)
220	    (require 'mm-uu)
221	    (funcall mm-uu-yenc-decode-function (point-min) (point-max))
222	    )
223	   ((functionp encoding)
224	    (funcall encoding (point-min) (point-max))
225	    t)
226	   (t
227	    (message "Unknown encoding %s; defaulting to 8bit" encoding)))
228	(error
229	 (message "Error while decoding: %s" error)
230	 nil))
231    (when (and
232	   type
233	   (memq encoding '(base64 x-uuencode x-uue x-binhex x-yenc))
234	   (string-match "\\`text/" type))
235      (goto-char (point-min))
236      (while (search-forward "\r\n" nil t)
237	(replace-match "\n" t t)))))
238
239(defun mm-decode-body (charset &optional encoding type)
240  "Decode the current article that has been encoded with ENCODING to CHARSET.
241ENCODING is a MIME content transfer encoding.
242CHARSET is the MIME charset with which to decode the data after transfer
243decoding.  If it is nil, default to `mail-parse-charset'."
244  (when (stringp charset)
245    (setq charset (intern (downcase charset))))
246  (when (or (not charset)
247	    (eq 'gnus-all mail-parse-ignored-charsets)
248	    (memq 'gnus-all mail-parse-ignored-charsets)
249	    (memq charset mail-parse-ignored-charsets))
250    (setq charset mail-parse-charset))
251  (save-excursion
252    (when encoding
253      (mm-decode-content-transfer-encoding encoding type))
254    (when (and (featurep 'mule) ;; Fixme: Wrong test for unibyte session.
255	       (not (eq charset 'gnus-decoded)))
256      (let ((coding-system (mm-charset-to-coding-system
257			    ;; Allow overwrite using
258			    ;; `mm-charset-override-alist'.
259			    charset nil t)))
260	(if (and (not coding-system)
261		 (listp mail-parse-ignored-charsets)
262		 (memq 'gnus-unknown mail-parse-ignored-charsets))
263	    (setq coding-system
264		  (mm-charset-to-coding-system mail-parse-charset)))
265	(when (and charset coding-system
266		   ;; buffer-file-coding-system
267		   ;;Article buffer is nil coding system
268		   ;;in XEmacs
269		   (mm-multibyte-p)
270		   (or (not (eq coding-system 'ascii))
271		       (setq coding-system mail-parse-charset)))
272	  (mm-decode-coding-region (point-min) (point-max)
273				   coding-system))
274	(setq buffer-file-coding-system
275	      (if (boundp 'last-coding-system-used)
276		  (symbol-value 'last-coding-system-used)
277		coding-system))))))
278
279(defun mm-decode-string (string charset)
280  "Decode STRING with CHARSET."
281  (when (stringp charset)
282    (setq charset (intern (downcase charset))))
283  (when (or (not charset)
284	    (eq 'gnus-all mail-parse-ignored-charsets)
285	    (memq 'gnus-all mail-parse-ignored-charsets)
286	    (memq charset mail-parse-ignored-charsets))
287    (setq charset mail-parse-charset))
288  (or
289   (when (featurep 'mule)
290     (let ((coding-system (mm-charset-to-coding-system
291			   charset
292			   ;; Allow overwrite using
293			   ;; `mm-charset-override-alist'.
294			   nil t)))
295       (if (and (not coding-system)
296		(listp mail-parse-ignored-charsets)
297		(memq 'gnus-unknown mail-parse-ignored-charsets))
298	   (setq coding-system
299		 (mm-charset-to-coding-system mail-parse-charset)))
300       (when (and charset coding-system
301		  (mm-multibyte-p)
302		  (or (not (eq coding-system 'ascii))
303		      (setq coding-system mail-parse-charset)))
304	 (mm-decode-coding-string string coding-system))))
305   string))
306
307(provide 'mm-bodies)
308
309;;; arch-tag: 41104bb6-4443-4ca9-8d5c-ff87ecf27d8d
310;;; mm-bodies.el ends here
311