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|
;;; mm-bodies.el --- Functions for decoding MIME things
;; Copyright (C) 1998-2021 Free Software Foundation, Inc.
;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
;; MORIOKA Tomohiko <morioka@jaist.ac.jp>
;; This file is part of GNU Emacs.
;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.
;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>.
;;; Commentary:
;;; Code:
(require 'mm-util)
(require 'rfc2047)
(require 'mm-encode)
(defvar mm-uu-yenc-decode-function)
(defvar mm-uu-decode-function)
(defvar mm-uu-binhex-decode-function)
;; 8bit treatment gets any char except: 0x32 - 0x7f, LF, TAB, BEL,
;; BS, vertical TAB, form feed, and ^_
;;
;; Note that CR is *not* included, as that would allow a non-paired CR
;; in the body contrary to RFC 822 (or later):
;;
;; - CR and LF MUST only occur together as CRLF; they MUST NOT
;; appear independently in the body.
(defvar mm-7bit-chars "\x20-\x7f\n\t\x7\x8\xb\xc\x1f")
(defcustom mm-body-charset-encoding-alist
'((iso-2022-jp . 7bit)
(iso-2022-jp-2 . 7bit)
;; We MUST encode UTF-16 because it can contain \0's which is
;; known to break servers.
;; Note: UTF-16 variants are invalid for text parts [RFC 2781],
;; so this can't happen :-/.
;; PPS: Yes, it can happen if the user specifies UTF-16 in the MML
;; markup. - jh.
(utf-16 . base64)
(utf-16be . base64)
(utf-16le . base64))
"Alist of MIME charsets to encodings.
Valid encodings are `7bit', `8bit', `quoted-printable' and `base64'."
:type '(repeat (cons (symbol :tag "charset")
(choice :tag "encoding"
(const 7bit)
(const 8bit)
(const quoted-printable)
(const base64))))
:group 'mime)
(autoload 'message-options-get "message")
(declare-function message-options-set "message" (symbol value))
(defun mm-encode-body (&optional charset)
"Encode whole buffer's contents.
Buffer's multibyteness will be turned off when encoding takes place.
If there is more than one non-ASCII MULE charset in the body, then the
list of MULE charsets found is returned.
If CHARSET is non-nil, it is used as the MIME charset to encode the body.
If successful, the MIME charset is returned.
If no encoding was done, nil is returned."
(if (not enable-multibyte-characters)
;; In the non-Mule case, we search for non-ASCII chars and
;; return the value of `mail-parse-charset' if any are found.
(or charset
(save-excursion
(goto-char (point-min))
(if (re-search-forward "[^\x0-\x7f]" nil t)
(or mail-parse-charset
(message-options-get 'mm-body-charset-encoding-alist)
(message-options-set
'mm-body-charset-encoding-alist
(read-coding-system "Charset used in the article: ")))
;; The logic in `mml-generate-mime-1' confirms that it's OK
;; to return nil here.
nil)))
(save-excursion
(if charset
(progn
(insert
(prog1
(encode-coding-string (buffer-string)
(mm-charset-to-coding-system charset))
(erase-buffer)
(set-buffer-multibyte nil)))
charset)
(goto-char (point-min))
(let ((charsets (mm-find-mime-charset-region (point-min) (point-max)
mm-hack-charsets)))
(cond
;; No encoding.
((null charsets)
nil)
;; Too many charsets.
((> (length charsets) 1)
charsets)
;; We encode.
(t
(prog1
(setq charset (car charsets))
(insert
(prog1
(encode-coding-string (buffer-string)
(mm-charset-to-coding-system charset))
(erase-buffer)
(set-buffer-multibyte nil)))))
))))))
(defun mm-long-lines-p (length)
"Say whether any of the lines in the buffer is longer than LENGTH."
(save-excursion
(goto-char (point-min))
(end-of-line)
(while (and (not (eobp))
(not (> (current-column) length)))
(forward-line 1)
(end-of-line))
(and (> (current-column) length)
(current-column))))
(defvar message-posting-charset)
(defun mm-body-encoding (charset &optional encoding)
"Do Content-Transfer-Encoding and return the encoding of the current buffer."
(when (stringp encoding)
(setq encoding (intern (downcase encoding))))
(let ((bits (mm-body-7-or-8))
(longp (mm-long-lines-p 1000)))
(require 'message)
(cond
((and (not longp)
(not (and mm-use-ultra-safe-encoding
(or (save-excursion (re-search-forward " $" nil t))
(save-excursion (re-search-forward "^From " nil t)))))
(eq bits '7bit))
bits)
((and (not mm-use-ultra-safe-encoding)
(not longp)
(not (cdr (assq charset mm-body-charset-encoding-alist)))
(or (eq t (cdr message-posting-charset))
(memq charset (cdr message-posting-charset))
(eq charset mail-parse-charset)))
bits)
(t
(let ((encoding (or encoding
(cdr (assq charset mm-body-charset-encoding-alist))
(mm-qp-or-base64))))
(when mm-use-ultra-safe-encoding
(setq encoding (mm-safer-encoding encoding)))
(mm-encode-content-transfer-encoding encoding "text/plain")
encoding)))))
(defun mm-body-7-or-8 ()
"Say whether the body is 7bit or 8bit."
(if (save-excursion
(goto-char (point-min))
(skip-chars-forward mm-7bit-chars)
(eobp))
'7bit
'8bit))
;;;
;;; Functions for decoding
;;;
(defun mm-decode-content-transfer-encoding (encoding &optional type)
"Decodes buffer encoded with ENCODING, returning success status.
If TYPE is `text/plain' CRLF->LF translation may occur."
(prog1
(condition-case error
(cond
((eq encoding 'quoted-printable)
(quoted-printable-decode-region (point-min) (point-max))
t)
((eq encoding 'base64)
(base64-decode-region
(point-min)
;; Some mailers insert whitespace
;; junk at the end which
;; base64-decode-region dislikes.
;; Also remove possible junk which could
;; have been added by mailing list software.
(save-excursion
(goto-char (point-min))
(while (re-search-forward "^[\t ]*\r?\n" nil t)
(delete-region (match-beginning 0) (match-end 0)))
(goto-char (point-max))
(when (re-search-backward "^[\t ]*[A-Za-z0-9+/]+=*[\t ]*$"
nil t)
(forward-line))
(point))))
((memq encoding '(nil 7bit 8bit binary))
;; Do nothing.
t)
((memq encoding '(x-uuencode x-uue))
(require 'mm-uu)
(funcall mm-uu-decode-function (point-min) (point-max))
t)
((eq encoding 'x-binhex)
(require 'mm-uu)
(funcall mm-uu-binhex-decode-function (point-min) (point-max))
t)
((eq encoding 'x-yenc)
(require 'mm-uu)
(funcall mm-uu-yenc-decode-function (point-min) (point-max))
)
((functionp encoding)
(funcall encoding (point-min) (point-max))
t)
(t
(message "Unknown encoding %s; defaulting to 8bit" encoding)))
(error
(message "Error while decoding: %s" error)
nil))
(when (and
type
(memq encoding '(base64 x-uuencode x-uue x-binhex x-yenc))
(string-match "\\`text/" type))
(goto-char (point-min))
(while (search-forward "\r\n" nil t)
(replace-match "\n" t t)))))
(defun mm-decode-body (charset &optional encoding type)
"Decode the current article that has been encoded with ENCODING to CHARSET.
ENCODING is a MIME content transfer encoding.
CHARSET is the MIME charset with which to decode the data after transfer
decoding. If it is nil, default to `mail-parse-charset'."
(when (stringp charset)
(setq charset (intern (downcase charset))))
(when (or (not charset)
(eq 'gnus-all mail-parse-ignored-charsets)
(memq 'gnus-all mail-parse-ignored-charsets)
(memq charset mail-parse-ignored-charsets))
(setq charset mail-parse-charset))
(save-excursion
(when encoding
(mm-decode-content-transfer-encoding encoding type))
(when (not (eq charset 'gnus-decoded))
(let ((coding-system (mm-charset-to-coding-system
;; Allow overwrite using
;; `mm-charset-override-alist'.
charset nil t)))
(if (and (not coding-system)
(listp mail-parse-ignored-charsets)
(memq 'gnus-unknown mail-parse-ignored-charsets))
(setq coding-system
(mm-charset-to-coding-system mail-parse-charset)))
(when (and charset coding-system
enable-multibyte-characters
(or (not (eq coding-system 'ascii))
(setq coding-system mail-parse-charset)))
(decode-coding-region (point-min) (point-max) coding-system))
(setq buffer-file-coding-system last-coding-system-used)))))
(defun mm-decode-string (string charset)
"Decode STRING with CHARSET."
(when (stringp charset)
(setq charset (intern (downcase charset))))
(when (or (not charset)
(eq 'gnus-all mail-parse-ignored-charsets)
(memq 'gnus-all mail-parse-ignored-charsets)
(memq charset mail-parse-ignored-charsets))
(setq charset mail-parse-charset))
(or
(let ((coding-system (mm-charset-to-coding-system
charset
;; Allow overwrite using
;; `mm-charset-override-alist'.
nil t)))
(if (and (not coding-system)
(listp mail-parse-ignored-charsets)
(memq 'gnus-unknown mail-parse-ignored-charsets))
(setq coding-system
(mm-charset-to-coding-system mail-parse-charset)))
(when (and charset coding-system
enable-multibyte-characters
(or (not (eq coding-system 'ascii))
(setq coding-system mail-parse-charset)))
(decode-coding-string string coding-system)))
string))
(provide 'mm-bodies)
;;; mm-bodies.el ends here
|
