code.delx.au - gnu-emacs/blob - lisp/gnus/mm-bodies.el

   1 ;;; mm-bodies.el --- Functions for decoding MIME things
   2
   3 ;; Copyright (C) 1998, 1999, 2000, 2001, 2003, 2004
   4 ;;        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., 59 Temple Place - Suite 330,
  23 ;; Boston, MA 02111-1307, 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     (utf-16 . base64)
  60     (utf-16be . base64)
  61     (utf-16le . base64))
  62   "Alist of MIME charsets to encodings.
  63 Valid encodings are `7bit', `8bit', `quoted-printable' and `base64'."
  64   :type '(repeat (cons (symbol :tag "charset")
  65                        (choice :tag "encoding"
  66                                (const 7bit)
  67                                (const 8bit)
  68                                (const quoted-printable)
  69                                (const base64))))
  70   :group 'mime)
  71
  72 (defun mm-encode-body (&optional charset)
  73   "Encode a body.
  74 Should be called narrowed to the body that is to be encoded.
  75 If there is more than one non-ASCII MULE charset in the body, then the
  76 list of MULE charsets found is returned.
  77 If CHARSET is non-nil, it is used as the MIME charset to encode the body.
  78 If successful, the MIME charset is returned.
  79 If no encoding was done, nil is returned."
  80   (if (not (mm-multibyte-p))
  81       ;; In the non-Mule case, we search for non-ASCII chars and
  82       ;; return the value of `mail-parse-charset' if any are found.
  83       (or charset
  84           (save-excursion
  85             (goto-char (point-min))
  86             (if (re-search-forward "[^\x0-\x7f]" nil t)
  87                 (or mail-parse-charset
  88                     (message-options-get 'mm-encody-body-charset)
  89                     (message-options-set
  90                      'mm-encody-body-charset
  91                      (mm-read-coding-system "Charset used in the article: ")))
  92               ;; The logic in `mml-generate-mime-1' confirms that it's OK
  93               ;; to return nil here.
  94               nil)))
  95     (save-excursion
  96       (if charset
  97           (progn
  98             (mm-encode-coding-region (point-min) (point-max) charset)
  99             charset)
 100         (goto-char (point-min))
 101         (let ((charsets (mm-find-mime-charset-region (point-min) (point-max))))
 102           (cond
 103            ;; No encoding.
 104            ((null charsets)
 105             nil)
 106            ;; Too many charsets.
 107            ((> (length charsets) 1)
 108             charsets)
 109            ;; We encode.
 110            (t
 111             (prog1
 112                 (setq charset (car charsets))
 113               (mm-encode-coding-region (point-min) (point-max)
 114                                        (mm-charset-to-coding-system charset))))
 115            ))))))
 116
 117 (defun mm-long-lines-p (length)
 118   "Say whether any of the lines in the buffer is longer than LENGTH."
 119   (save-excursion
 120     (goto-char (point-min))
 121     (end-of-line)
 122     (while (and (not (eobp))
 123                 (not (> (current-column) length)))
 124       (forward-line 1)
 125       (end-of-line))
 126     (and (> (current-column) length)
 127          (current-column))))
 128
 129 (defvar message-posting-charset)
 130
 131 (defun mm-body-encoding (charset &optional encoding)
 132   "Do Content-Transfer-Encoding and return the encoding of the current buffer."
 133   (when (stringp encoding)
 134     (setq encoding (intern (downcase encoding))))
 135   (let ((bits (mm-body-7-or-8))
 136         (longp (mm-long-lines-p 1000)))
 137     (require 'message)
 138     (cond
 139      ((and (not longp)
 140            (not (and mm-use-ultra-safe-encoding
 141                      (save-excursion (re-search-forward "^From " nil t))))
 142            (eq bits '7bit))
 143       bits)
 144      ((and (not mm-use-ultra-safe-encoding)
 145            (not longp)
 146            (not (cdr (assq charset mm-body-charset-encoding-alist)))
 147            (or (eq t (cdr message-posting-charset))
 148                (memq charset (cdr message-posting-charset))
 149                (eq charset mail-parse-charset)))
 150       bits)
 151      (t
 152       (let ((encoding (or encoding
 153                           (cdr (assq charset mm-body-charset-encoding-alist))
 154                           (mm-qp-or-base64))))
 155         (when mm-use-ultra-safe-encoding
 156           (setq encoding (mm-safer-encoding encoding)))
 157         (mm-encode-content-transfer-encoding encoding "text/plain")
 158         encoding)))))
 159
 160 (defun mm-body-7-or-8 ()
 161   "Say whether the body is 7bit or 8bit."
 162   (if (save-excursion
 163         (goto-char (point-min))
 164         (skip-chars-forward mm-7bit-chars)
 165         (eobp))
 166       '7bit
 167     '8bit))
 168
 169 ;;;
 170 ;;; Functions for decoding
 171 ;;;
 172
 173 (eval-when-compile (defvar mm-uu-yenc-decode-function))
 174
 175 (defun mm-decode-content-transfer-encoding (encoding &optional type)
 176   "Decodes buffer encoded with ENCODING, returning success status.
 177 If TYPE is `text/plain' CRLF->LF translation may occur."
 178   (prog1
 179       (condition-case error
 180           (cond
 181            ((eq encoding 'quoted-printable)
 182             (quoted-printable-decode-region (point-min) (point-max))
 183             t)
 184            ((eq encoding 'base64)
 185             (base64-decode-region
 186              (point-min)
 187              ;; Some mailers insert whitespace
 188              ;; junk at the end which
 189              ;; base64-decode-region dislikes.
 190              ;; Also remove possible junk which could
 191              ;; have been added by mailing list software.
 192              (save-excursion
 193                (goto-char (point-min))
 194                (while (re-search-forward "^[\t ]*\r?\n" nil t)
 195                  (delete-region (match-beginning 0) (match-end 0)))
 196                (goto-char (point-max))
 197                (when (re-search-backward "^[A-Za-z0-9+/]+=*[\t ]*$" nil t)
 198                  (forward-line))
 199                (point))))
 200            ((memq encoding '(7bit 8bit binary))
 201             ;; Do nothing.
 202             t)
 203            ((null encoding)
 204             ;; Do nothing.
 205             t)
 206            ((memq encoding '(x-uuencode x-uue))
 207             (require 'mm-uu)
 208             (funcall mm-uu-decode-function (point-min) (point-max))
 209             t)
 210            ((eq encoding 'x-binhex)
 211             (require 'mm-uu)
 212             (funcall mm-uu-binhex-decode-function (point-min) (point-max))
 213             t)
 214            ((eq encoding 'x-yenc)
 215             (require 'mm-uu)
 216             (funcall mm-uu-yenc-decode-function (point-min) (point-max))
 217             )
 218            ((functionp encoding)
 219             (funcall encoding (point-min) (point-max))
 220             t)
 221            (t
 222             (message "Unknown encoding %s; defaulting to 8bit" encoding)))
 223         (error
 224          (message "Error while decoding: %s" error)
 225          nil))
 226     (when (and
 227            (memq encoding '(base64 x-uuencode x-uue x-binhex x-yenc))
 228            (equal type "text/plain"))
 229       (goto-char (point-min))
 230       (while (search-forward "\r\n" nil t)
 231         (replace-match "\n" t t)))))
 232
 233 (defun mm-decode-body (charset &optional encoding type)
 234   "Decode the current article that has been encoded with ENCODING to CHARSET.
 235 ENCODING is a MIME content transfer encoding.
 236 CHARSET is the MIME charset with which to decode the data after transfer
 237 decoding.  If it is nil, default to `mail-parse-charset'."
 238   (when (stringp charset)
 239     (setq charset (intern (downcase charset))))
 240   (when (or (not charset)
 241             (eq 'gnus-all mail-parse-ignored-charsets)
 242             (memq 'gnus-all mail-parse-ignored-charsets)
 243             (memq charset mail-parse-ignored-charsets))
 244     (setq charset mail-parse-charset))
 245   (save-excursion
 246     (when encoding
 247       (mm-decode-content-transfer-encoding encoding type))
 248     (when (featurep 'mule)  ; Fixme: Wrong test for unibyte session.
 249       (let ((coding-system (mm-charset-to-coding-system charset)))
 250         (if (and (not coding-system)
 251                  (listp mail-parse-ignored-charsets)
 252                  (memq 'gnus-unknown mail-parse-ignored-charsets))
 253             (setq coding-system
 254                   (mm-charset-to-coding-system mail-parse-charset)))
 255         (when (and charset coding-system
 256                    ;; buffer-file-coding-system
 257                    ;;Article buffer is nil coding system
 258                    ;;in XEmacs
 259                    (mm-multibyte-p)
 260                    (or (not (eq coding-system 'ascii))
 261                        (setq coding-system mail-parse-charset))
 262                    (not (eq coding-system 'gnus-decoded)))
 263           (mm-decode-coding-region (point-min) (point-max)
 264                                    coding-system))
 265         (setq buffer-file-coding-system
 266               (if (boundp 'last-coding-system-used)
 267                   (symbol-value 'last-coding-system-used)
 268                 coding-system))))))
 269
 270 (defun mm-decode-string (string charset)
 271   "Decode STRING with CHARSET."
 272   (when (stringp charset)
 273     (setq charset (intern (downcase charset))))
 274   (when (or (not charset)
 275             (eq 'gnus-all mail-parse-ignored-charsets)
 276             (memq 'gnus-all mail-parse-ignored-charsets)
 277             (memq charset mail-parse-ignored-charsets))
 278     (setq charset mail-parse-charset))
 279   (or
 280    (when (featurep 'mule)
 281      (let ((coding-system (mm-charset-to-coding-system charset)))
 282        (if (and (not coding-system)
 283                 (listp mail-parse-ignored-charsets)
 284                 (memq 'gnus-unknown mail-parse-ignored-charsets))
 285            (setq coding-system
 286                  (mm-charset-to-coding-system mail-parse-charset)))
 287        (when (and charset coding-system
 288                   (mm-multibyte-p)
 289                   (or (not (eq coding-system 'ascii))
 290                       (setq coding-system mail-parse-charset)))
 291          (mm-decode-coding-string string coding-system))))
 292    string))
 293
 294 (provide 'mm-bodies)
 295
 296 ;;; arch-tag: 41104bb6-4443-4ca9-8d5c-ff87ecf27d8d
 297 ;;; mm-bodies.el ends here