1 ;;; rfc2047.el --- functions for encoding and decoding rfc2047 messages
3 ;; Copyright (C) 1998-2016 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 3 of the License, or
12 ;; (at your option) any later version.
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. If not, see <http://www.gnu.org/licenses/>.
24 ;; RFC 2047 is "MIME (Multipurpose Internet Mail Extensions) Part
25 ;; Three: Message Header Extensions for Non-ASCII Text".
31 (defvar message-posting-charset)
35 ;; Fixme: Avoid this (used for mail-parse-charset) mm dependence on gnus.
37 (require 'rfc2045) ;; rfc2045-encode-string
38 (autoload 'mm-body-7-or-8 "mm-bodies")
40 (defvar rfc2047-header-encoding-alist
41 '(("Newsgroups" . nil)
44 ("\\(Resent-\\)?\\(From\\|Cc\\|To\\|Bcc\\|\\(In-\\)?Reply-To\\|Sender\
45 \\|Mail-Followup-To\\|Mail-Copies-To\\|Approved\\)" . address-mime)
47 "*Header/encoding method alist.
48 The list is traversed sequentially. The keys can either be
53 1) nil, in which case no encoding is done;
54 2) `mime', in which case the header will be encoded according to RFC2047;
55 3) `address-mime', like `mime', but takes account of the rules for address
56 fields (where quoted strings and comments must be treated separately);
57 4) a charset, in which case it will be encoded as that charset;
58 5) `default', in which case the field will be encoded as the rest
61 (defvar rfc2047-charset-encoding-alist
87 "Alist of MIME charsets to RFC2047 encodings.
88 Valid encodings are nil, `Q' and `B'. These indicate binary (no) encoding,
89 quoted-printable and base64 respectively.")
91 (defvar rfc2047-encode-function-alist
92 '((Q . rfc2047-q-encode-string)
93 (B . rfc2047-b-encode-string)
95 "Alist of RFC2047 encodings to encoding functions.")
97 (defvar rfc2047-encode-encoded-words t
98 "Whether encoded words should be encoded again.")
100 (defvar rfc2047-allow-irregular-q-encoded-words t
101 "*Whether to decode irregular Q-encoded words.")
103 (eval-and-compile ;; Necessary to hard code them in `rfc2047-decode-region'.
104 (defconst rfc2047-encoded-word-regexp
105 "=\\?\\([^][\000-\040()<>@,;:*\\\"/?.=]+\\)\\(?:\\*[^?]+\\)?\\?\
106 \\(B\\?[+/0-9A-Za-z]*=*\
109 "Regexp that matches encoded word."
110 ;; The patterns for the B encoding and the Q encoding, i.e. the ones
111 ;; beginning with "B" and "Q" respectively, are restricted into only
112 ;; the characters that those encodings may generally use.
114 (defconst rfc2047-encoded-word-regexp-loose
115 "=\\?\\([^][\000-\040()<>@,;:*\\\"/?.=]+\\)\\(?:\\*[^?]+\\)?\\?\
116 \\(B\\?[+/0-9A-Za-z]*=*\
117 \\|Q\\?\\(?:\\?+[ -<>@-~]\\)?\\(?:[ ->@-~]+\\?+[ -<>@-~]\\)*[ ->@-~]*\\?*\
119 "Regexp that matches encoded word allowing loose Q encoding."
120 ;; The pattern for the Q encoding, i.e. the one beginning with "Q",
122 ;; "Q\\?\\(\\?+[^\n=?]\\)?\\([^\n?]+\\?+[^\n=?]\\)*[^\n?]*\\?*"
123 ;; <--------1-------><----------2,3----------><--4--><-5->
125 ;; 1. After "Q?", allow "?"s that follow a character other than "=".
126 ;; 2. Allow "=" after "Q?"; it isn't regarded as the terminator.
127 ;; 3. In the middle of an encoded word, allow "?"s that follow a
128 ;; character other than "=".
129 ;; 4. Allow any characters other than "?" in the middle of an
131 ;; 5. At the end, allow "?"s.
135 ;;; Functions for encoding RFC2047 messages
138 (defun rfc2047-qp-or-base64 ()
139 "Return the type with which to encode the buffer.
140 This is either `base64' or `quoted-printable'."
142 (let ((limit (min (point-max) (+ 2000 (point-min))))
144 (goto-char (point-min))
145 (skip-chars-forward "\x20-\x7f\r\n\t" limit)
146 (while (< (point) limit)
149 (skip-chars-forward "\x20-\x7f\r\n\t" limit))
150 (if (or (< (* 6 n8bit) (- limit (point-min)))
151 ;; Don't base64, say, a short line with a single
152 ;; non-ASCII char when splitting parts by charset.
157 (defun rfc2047-narrow-to-field ()
158 "Narrow the buffer to the header on the current line."
164 (if (re-search-forward "^[^ \n\t]" nil t)
167 (goto-char (point-min)))
169 (defun rfc2047-field-value ()
170 "Return the value of the field at point."
173 (rfc2047-narrow-to-field)
174 (re-search-forward ":[ \t\n]*" nil t)
175 (buffer-substring-no-properties (point) (point-max)))))
177 (defun rfc2047-quote-special-characters-in-quoted-strings (&optional
179 "Quote special characters with `\\'s in quoted strings.
180 Quoting will not be done in a quoted string if it contains characters
181 matching ENCODABLE-REGEXP or it is within parentheses."
182 (goto-char (point-min))
183 (let ((tspecials (concat "[" ietf-drums-tspecials "]"))
186 (with-syntax-table (standard-syntax-table)
190 (eq (char-before) ?\)))
192 (goto-char (point-max)))
194 (narrow-to-region start (point))
196 (while (search-forward "\"" nil t)
197 (setq beg (match-beginning 0))
198 (unless (eq (char-before beg) ?\\)
204 (setq end (1- (point)))
206 (if (and encodable-regexp
207 (re-search-forward encodable-regexp end t))
210 (narrow-to-region beg end)
211 (while (re-search-forward tspecials nil 'move)
212 (if (eq (char-before) ?\\)
213 (if (looking-at tspecials) ;; Already quoted.
216 (goto-char (match-beginning 0))
222 (goto-char (point-max)))
224 (setq start (point))))))
226 (defvar rfc2047-encoding-type 'address-mime
227 "The type of encoding done by `rfc2047-encode-region'.
228 This should be dynamically bound around calls to
229 `rfc2047-encode-region' to either `mime' or `address-mime'. See
230 `rfc2047-header-encoding-alist', for definitions.")
232 (defun rfc2047-encode-message-header ()
233 "Encode the message header according to `rfc2047-header-encoding-alist'.
234 Should be called narrowed to the head of the message."
237 (goto-char (point-min))
238 (let (alist elem method charsets)
241 (rfc2047-narrow-to-field)
243 alist rfc2047-header-encoding-alist
244 charsets (mm-find-mime-charset-region (point-min) (point-max)))
245 ;; M$ Outlook boycotts decoding of a header if it consists
246 ;; of two or more encoded words and those charsets differ;
247 ;; it seems to decode all words in a header from a charset
248 ;; found first in the header. So, we unify the charsets into
249 ;; a single one used for encoding the whole text in a header.
250 (let ((mm-coding-system-priorities
251 (if (= (length charsets) 1)
252 (cons (mm-charset-to-coding-system (car charsets))
253 mm-coding-system-priorities)
254 mm-coding-system-priorities)))
255 (while (setq elem (pop alist))
256 (when (or (and (stringp (car elem))
257 (looking-at (car elem)))
261 (if (not (rfc2047-encodable-p))
263 (when (eq method 'address-mime)
264 (rfc2047-quote-special-characters-in-quoted-strings))
265 (if (and (eq (mm-body-7-or-8) '8bit)
268 (car message-posting-charset)))
269 ;; 8 bit must be decoded.
270 (mm-encode-coding-region
271 (point-min) (point-max)
272 (mm-charset-to-coding-system
273 (car message-posting-charset))))
274 ;; No encoding necessary, but folding is nice
278 (goto-char (point-min))
279 (skip-chars-forward "^:")
280 (when (looking-at ": ")
284 ;; We found something that may perhaps be encoded.
285 (re-search-forward "^[^:]+: *" nil t)
287 ((eq method 'address-mime)
288 (rfc2047-encode-region (point) (point-max)))
290 (let ((rfc2047-encoding-type 'mime))
291 (rfc2047-encode-region (point) (point-max))))
292 ((eq method 'default)
293 (if (and (featurep 'mule)
294 (if (boundp 'enable-multibyte-characters)
295 (default-value 'enable-multibyte-characters))
297 (mm-encode-coding-region (point) (point-max)
298 mail-parse-charset)))
299 ;; We get this when CC'ing messages to newsgroups with
300 ;; 8-bit names. The group name mail copy just got
301 ;; unconditionally encoded. Previously, it would ask
302 ;; whether to encode, which was quite confusing for the
303 ;; user. If the new behavior is wrong, tell me. I have
304 ;; left the old code commented out below.
305 ;; -- Per Abrahamsen <abraham@dina.kvl.dk> Date: 2001-10-07.
306 ;; Modified by Dave Love, with the commented-out code changed
307 ;; in accordance with changes elsewhere.
309 (rfc2047-encode-region (point) (point-max)))
311 ;;; (if (or (message-options-get
312 ;;; 'rfc2047-encode-message-header-encode-any)
313 ;;; (message-options-set
314 ;;; 'rfc2047-encode-message-header-encode-any
316 ;;; "Some texts are not encoded. Encode anyway?")))
317 ;;; (rfc2047-encode-region (point-min) (point-max))
318 ;;; (error "Cannot send unencoded text")))
319 ((mm-coding-system-p method)
320 (if (or (and (featurep 'mule)
321 (if (boundp 'enable-multibyte-characters)
322 (default-value 'enable-multibyte-characters)))
323 (featurep 'file-coding))
324 (mm-encode-coding-region (point) (point-max) method)))
327 (goto-char (point-max))))))))
329 ;; Fixme: This, and the require below may not be the Right Thing, but
330 ;; should be safe just before release. -- fx 2001-02-08
332 (defun rfc2047-encodable-p ()
333 "Return non-nil if any characters in current buffer need encoding in headers.
334 The buffer may be narrowed."
335 (require 'message) ; for message-posting-charset
337 (mm-find-mime-charset-region (point-min) (point-max))))
338 (goto-char (point-min))
339 (or (and rfc2047-encode-encoded-words
341 (re-search-forward rfc2047-encoded-word-regexp nil t)
342 (goto-char (point-min))))
344 (not (equal charsets (list (car message-posting-charset))))))))
346 ;; Use this syntax table when parsing into regions that may need
347 ;; encoding. Double quotes are string delimiters, backslash is
348 ;; character quoting, and all other RFC 2822 special characters are
349 ;; treated as punctuation so we can use forward-sexp/forward-word to
350 ;; skip to the end of regions appropriately. Nb. ietf-drums does
351 ;; things differently.
352 (defconst rfc2047-syntax-table
353 ;; (make-char-table 'syntax-table '(2)) only works in Emacs.
354 (let ((table (make-syntax-table)))
355 ;; The following is done to work for setting all elements of the table;
356 ;; it appears to be the cleanest way.
357 ;; Play safe and don't assume the form of the word syntax entry --
359 (if (featurep 'xemacs)
360 (put-char-table t (get-char-table ?a (standard-syntax-table)) table)
361 (set-char-table-range table t (aref (standard-syntax-table) ?a)))
362 (modify-syntax-entry ?\\ "\\" table)
363 (modify-syntax-entry ?\" "\"" table)
364 (modify-syntax-entry ?\( "(" table)
365 (modify-syntax-entry ?\) ")" table)
366 (modify-syntax-entry ?\< "." table)
367 (modify-syntax-entry ?\> "." table)
368 (modify-syntax-entry ?\[ "." table)
369 (modify-syntax-entry ?\] "." table)
370 (modify-syntax-entry ?: "." table)
371 (modify-syntax-entry ?\; "." table)
372 (modify-syntax-entry ?, "." table)
373 (modify-syntax-entry ?@ "." table)
376 (defun rfc2047-encode-region (b e &optional dont-fold)
377 "Encode words in region B to E that need encoding.
378 By default, the region is treated as containing RFC2822 addresses.
379 Dynamically bind `rfc2047-encoding-type' to change that."
381 (narrow-to-region b e)
382 (let ((encodable-regexp (if rfc2047-encode-encoded-words
383 "[^\000-\177]+\\|=\\?"
385 start ; start of current token
387 ;; Whether there's an encoded word before the current token,
388 ;; either immediately or separated by space.
390 (orig-text (buffer-substring-no-properties b e)))
391 (if (eq 'mime rfc2047-encoding-type)
392 ;; Simple case. Continuous words in which all those contain
393 ;; non-ASCII characters are encoded collectively. Encoding
394 ;; ASCII words, including `Re:' used in Subject headers, is
395 ;; avoided for interoperability with non-MIME clients and
396 ;; for making it easy to find keywords.
398 (goto-char (point-min))
399 (while (progn (skip-chars-forward " \t\n")
402 (while (and (looking-at "[ \t\n]*\\([^ \t\n]+\\)")
404 (setq end (match-end 0))
405 (re-search-forward encodable-regexp end t)))
407 (if (> (point) start)
408 (rfc2047-encode start (point))
410 ;; `address-mime' case -- take care of quoted words, comments.
411 (rfc2047-quote-special-characters-in-quoted-strings encodable-regexp)
412 (with-syntax-table rfc2047-syntax-table
413 (goto-char (point-min))
414 (condition-case err ; in case of unbalanced quotes
415 ;; Look for rfc2822-style: sequences of atoms, quoted
416 ;; strings, specials, whitespace. (Specials mustn't be
420 (skip-chars-forward " \t\n")
423 ((not (char-after))) ; eob
425 ((eq ?\" (setq csyntax (char-syntax (char-after))))
429 ;; Does it need encoding?
431 (if (re-search-forward encodable-regexp end 'move)
432 ;; It needs encoding. Strip the quotes first,
433 ;; since encoded words can't occur in quotes.
440 ;; There was a preceding quoted word. We need
441 ;; to include any separating whitespace in this
442 ;; word to avoid it getting lost.
443 (skip-chars-backward " \t")
444 ;; A space is needed between the encoded words.
448 ;; Adjust the end position for the deleted quotes.
449 (rfc2047-encode start (- end 2))
450 (setq last-encoded t)) ; record that it was encoded
451 (setq last-encoded nil)))
453 ;; Skip other delimiters, but record that they've
454 ;; potentially separated quoted words.
456 (setq last-encoded nil))
458 (error "Unbalanced parentheses"))
460 ;; Look for the end of parentheses.
462 ;; Encode text as an unstructured field.
463 (let ((rfc2047-encoding-type 'mime))
464 (rfc2047-encode-region (1+ start) (1- (point))))
465 (skip-chars-forward ")"))
466 (t ; normal token/whitespace sequence
468 ;; Skip one ASCII word, or encode continuous words
469 ;; in which all those contain non-ASCII characters.
471 (while (not (or end (eobp)))
472 (when (looking-at "[\000-\177]+")
476 (while (and (or (re-search-forward
477 "[ \t\n]\\|\\Sw" end 'move)
479 (eq ?\\ (char-syntax (char-before))))
480 ;; Skip backslash-quoted characters.
483 (setq end (match-beginning 0))
484 (if rfc2047-encode-encoded-words
487 (when (search-forward "=?" end 'move)
488 (goto-char (match-beginning 0))
491 ;; Where the value nil of `end' means there may be
492 ;; text to have to be encoded following the point.
493 ;; Otherwise, the point reached to the end of ASCII
494 ;; words separated by whitespace or a special char.
496 (when (looking-at encodable-regexp)
497 (goto-char (setq begin (match-end 0)))
498 (while (and (looking-at "[ \t\n]+\\([^ \t\n]+\\)")
499 (setq end (match-end 0))
501 (while (re-search-forward
502 encodable-regexp end t))
505 (or (not (re-search-forward "\\Sw" end t))
507 (goto-char (match-beginning 0))
510 (when (looking-at "[^ \t\n]+")
511 (setq end (match-end 0))
512 (if (re-search-forward "\\Sw+" end t)
513 ;; There are special characters better
514 ;; to be encoded so that MTAs may parse
516 (cond ((= end (point)))
517 ((looking-at (concat "\\sw*\\("
522 (goto-char (1- (match-end 0)))
523 (unless (= (point) (match-beginning 0))
524 ;; Separate encodable text and
528 (skip-chars-forward " \t\n")
529 (if (and (looking-at "[^ \t\n]+")
530 (string-match encodable-regexp
533 (goto-char end)))))))
534 (skip-chars-backward " \t\n")
537 (if (re-search-forward encodable-regexp end 'move)
539 (unless (memq (char-before start) '(nil ?\t ? ))
542 (skip-chars-backward "^ \t\n")
543 (and (looking-at "\\Sw+")
544 (= (match-end 0) start)))
545 ;; Also encode bogus delimiters.
547 ;; Separate encodable text and delimiter.
550 (setq start (1+ start)
552 (rfc2047-encode start end)
553 (setq last-encoded t))
554 (setq last-encoded nil)))))
556 (if (or debug-on-quit debug-on-error)
557 (signal (car err) (cdr err))
558 (error "Invalid data for rfc2047 encoding: %s"
559 (mm-replace-in-string orig-text "[ \t\n]+" " "))))))))
561 (rfc2047-fold-region b (point)))
562 (goto-char (point-max))))
564 (defun rfc2047-encode-string (string &optional dont-fold)
565 "Encode words in STRING.
566 By default, the string is treated as containing addresses (see
567 `rfc2047-encoding-type')."
568 (mm-with-multibyte-buffer
570 (rfc2047-encode-region (point-min) (point-max) dont-fold)
574 ;; 2. Syntax of encoded-words
576 ;; While there is no limit to the length of a multiple-line header
577 ;; field, each line of a header field that contains one or more
578 ;; 'encoded-word's is limited to 76 characters.
580 ;; In `rfc2047-encode-parameter' it is bound to nil, so don't defconst it.
581 (defvar rfc2047-encode-max-chars 76
582 "Maximum characters of each header line that contain encoded-words.
583 According to RFC 2047, it is 76. If it is nil, encoded-words
584 will not be folded. Too small value may cause an error. You
585 should not change this value.")
587 (defun rfc2047-encode-1 (column string cs encoder start crest tail
589 "Subroutine used by `rfc2047-encode'."
590 (cond ((string-equal string "")
592 ((not rfc2047-encode-max-chars)
594 (funcall encoder (if cs
595 (mm-encode-coding-string string cs)
598 ((>= column rfc2047-encode-max-chars)
600 (cond ((string-match "\n[ \t]+\\'" eword)
601 ;; Remove a superfluous empty line.
602 (setq eword (substring eword 0 (match-beginning 0))))
603 ((string-match "(+\\'" eword)
604 ;; Break the line before the open parenthesis.
605 (setq crest (concat crest (match-string 0 eword))
606 eword (substring eword 0 (match-beginning 0))))))
607 (rfc2047-encode-1 (length crest) string cs encoder start " " tail
608 (concat eword "\n" crest)))
611 (limit (1- (length string)))
616 (setq next (concat start
619 (mm-encode-coding-string
620 (substring string 0 (1+ index))
622 (substring string 0 (1+ index))))
624 len (+ column (length next)))
625 (if (> len rfc2047-encode-max-chars)
628 (if (or (< index limit)
629 (<= (+ len (or (string-match "\n" tail)
631 rfc2047-encode-max-chars))
634 (if (string-match "\\`)+" tail)
635 ;; Break the line after the close parenthesis.
636 (setq tail (concat (substring tail 0 (match-end 0))
638 (substring tail (match-end 0)))
644 (concat eword next tail)
647 (string-match "(+\\'" eword))
648 (setq crest (concat crest (match-string 0 eword))
649 eword (substring eword 0 (match-beginning 0)))
650 (setq eword (concat eword next)))
652 eword (concat eword next)))
653 (when (string-match "\n[ \t]+\\'" eword)
654 ;; Remove a superfluous empty line.
655 (setq eword (substring eword 0 (match-beginning 0))))
656 (rfc2047-encode-1 (length crest) (substring string index)
657 cs encoder start " " tail
658 (concat eword "\n" crest)))))))
660 (defun rfc2047-encode (b e)
661 "Encode the word(s) in the region B to E.
662 Point moves to the end of the region."
663 (let ((mime-charset (or (mm-find-mime-charset-region b e) (list 'us-ascii)))
664 cs encoding tail crest eword)
665 ;; Use utf-8 as a last resort if determining charset of text fails.
666 (if (memq nil mime-charset)
667 (setq mime-charset (list 'utf-8)))
668 (cond ((> (length mime-charset) 1)
669 (error "Can't rfc2047-encode `%s'"
670 (buffer-substring-no-properties b e)))
671 ((= (length mime-charset) 1)
672 (setq mime-charset (car mime-charset)
673 cs (mm-charset-to-coding-system mime-charset))
674 (unless (and (mm-multibyte-p)
675 (mm-coding-system-p cs))
678 (narrow-to-region b e)
680 (or (cdr (assq mime-charset
681 rfc2047-charset-encoding-alist))
682 ;; For the charsets that don't have a preferred
683 ;; encoding, choose the one that's shorter.
684 (if (eq (rfc2047-qp-or-base64) 'base64)
689 (skip-chars-forward "^ \t\n")
690 ;; `tail' may contain a close parenthesis.
691 (setq tail (buffer-substring-no-properties e (point)))
693 (setq b (point-marker)
694 e (set-marker (make-marker) e))
695 (rfc2047-fold-region (point-at-bol) b)
697 (skip-chars-backward "^ \t\n")
698 (unless (= 0 (skip-chars-backward " \t"))
699 ;; `crest' may contain whitespace and an open parenthesis.
700 (setq crest (buffer-substring-no-properties (point) b)))
701 (setq eword (rfc2047-encode-1
703 (mm-replace-in-string
704 (buffer-substring-no-properties b e)
705 "\n\\([ \t]?\\)" "\\1")
707 (or (cdr (assq encoding
708 rfc2047-encode-function-alist))
710 (concat "=?" (downcase (symbol-name mime-charset))
711 "?" (upcase (symbol-name encoding)) "?")
714 (delete-region (if (eq (aref eword 0) ?\n)
716 ;; The line was folded before encoding.
721 ;; `eword' contains `crest' and `tail'.
725 (unless (or (/= 0 (length tail))
727 (looking-at "[ \t\n)]"))
732 (defun rfc2047-fold-field ()
733 "Fold the current header field."
736 (rfc2047-narrow-to-field)
737 (rfc2047-fold-region (point-min) (point-max)))))
739 (defun rfc2047-fold-region (b e)
740 "Fold long lines in region B to E."
742 (narrow-to-region b e)
743 (goto-char (point-min))
747 (bol (save-restriction
751 (when (and (or break qword-break)
752 (> (- (point) bol) 76))
753 (goto-char (or break qword-break))
756 (skip-chars-backward " \t")
757 (if (looking-at "[ \t]")
760 (setq bol (1- (point)))
761 ;; Don't break before the first non-LWSP characters.
762 (skip-chars-forward " \t")
766 ((eq (char-after) ?\n)
771 (skip-chars-forward " \t")
772 (unless (or (eobp) (eq (char-after) ?\n))
774 ((eq (char-after) ?\r)
776 ((memq (char-after) '(? ?\t))
777 (skip-chars-forward " \t")
778 (unless first ;; Don't break just after the header name.
779 (setq break (point))))
781 (if (not (looking-at "=\\?[^=]"))
782 (if (eq (char-after) ?=)
784 (skip-chars-forward "^ \t\n\r="))
785 ;; Don't break at the start of the field.
786 (unless (= (point) b)
787 (setq qword-break (point)))
788 (skip-chars-forward "^ \t\n\r")))
790 (skip-chars-forward "^ \t\n\r")))
792 (when (and (or break qword-break)
793 (> (- (point) bol) 76))
794 (goto-char (or break qword-break))
797 (if (or (> 0 (skip-chars-backward " \t"))
798 (looking-at "[ \t]"))
801 (setq bol (1- (point)))
802 ;; Don't break before the first non-LWSP characters.
803 (skip-chars-forward " \t")
805 (forward-char 1))))))
807 (defun rfc2047-unfold-field ()
808 "Fold the current line."
811 (rfc2047-narrow-to-field)