lisp/gnus/mm-bodies.el

   1 ;;; mm-bodies.el --- Functions for decoding MIME things
   2
   3 ;; Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004,
   4 ;;   2005, 2006 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.
  65 Valid 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.
  76 Should be called narrowed to the body that is to be encoded.
  77 If there is more than one non-ASCII MULE charset in the body, then the
  78 list of MULE charsets found is returned.
  79 If CHARSET is non-nil, it is used as the MIME charset to encode the body.
  80 If successful, the MIME charset is returned.
  81 If 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.
 182 If 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.
 241 ENCODING is a MIME content transfer encoding.
 242 CHARSET is the MIME charset with which to decode the data after transfer
 243 decoding.  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