Synch to No Gnus 200406292138.
[elisp/gnus.git-] / lisp / rfc2047.el
index 059d350..3b76718 100644 (file)
@@ -1,5 +1,7 @@
 ;;; rfc2047.el --- functions for encoding and decoding rfc2047 messages
-;; Copyright (C) 1998, 1999, 2000, 2002, 2003 Free Software Foundation, Inc.
+
+;; Copyright (C) 1998, 1999, 2000, 2002, 2003, 2004
+;;        Free Software Foundation, Inc.
 
 ;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
 ;;     MORIOKA Tomohiko <morioka@jaist.ac.jp>
@@ -87,12 +89,15 @@ The values can be:
 Valid encodings are nil, `Q' and `B'.  These indicate binary (no) encoding,
 quoted-printable and base64 respectively.")
 
-(defvar rfc2047-encoding-function-alist
-  '((Q . rfc2047-q-encode-region)
-    (B . rfc2047-b-encode-region)
-    (nil . ignore))
+(defvar rfc2047-encode-function-alist
+  '((Q . rfc2047-q-encode-string)
+    (B . rfc2047-b-encode-string)
+    (nil . identity))
   "Alist of RFC2047 encodings to encoding functions.")
 
+(defvar rfc2047-encode-encoded-words t
+  "Whether encoded words should be encoded again.")
+
 ;;;
 ;;; Functions for encoding RFC2047 messages
 ;;;
@@ -164,14 +169,15 @@ Should be called narrowed to the head of the message."
                       (mm-charset-to-coding-system
                        (car message-posting-charset))))
                ;; No encoding necessary, but folding is nice
-               (rfc2047-fold-region
-                (save-excursion
-                  (goto-char (point-min))
-                  (skip-chars-forward "^:")
-                  (when (looking-at ": ")
-                    (forward-char 2))
-                  (point))
-                (point-max)))
+               (when nil
+                 (rfc2047-fold-region
+                  (save-excursion
+                    (goto-char (point-min))
+                    (skip-chars-forward "^:")
+                    (when (looking-at ": ")
+                      (forward-char 2))
+                    (point))
+                  (point-max))))
            ;; We found something that may perhaps be encoded.
            (setq method nil
                  alist rfc2047-header-encoding-alist)
@@ -181,7 +187,6 @@ Should be called narrowed to the head of the message."
                        (eq (car elem) t))
                (setq alist nil
                      method (cdr elem))))
-           (goto-char (point-min))
            (re-search-forward "^[^:]+: *" nil t)
            (cond
             ((eq method 'address-mime)
@@ -235,8 +240,13 @@ The buffer may be narrowed."
   (require 'message)                   ; for message-posting-charset
   (let ((charsets
         (mm-find-mime-charset-region (point-min) (point-max))))
-    (and charsets
-        (not (equal charsets (list (car message-posting-charset)))))))
+    (goto-char (point-min))
+    (or (and rfc2047-encode-encoded-words
+            (prog1
+                (search-forward "=?" nil t)
+              (goto-char (point-min))))
+       (and charsets
+            (not (equal charsets (list (car message-posting-charset))))))))
 
 ;; Use this syntax table when parsing into regions that may need
 ;; encoding.  Double quotes are string delimiters, backslash is
@@ -260,8 +270,8 @@ The buffer may be narrowed."
                              table))))
     (modify-syntax-entry ?\\ "\\" table)
     (modify-syntax-entry ?\" "\"" table)
-    (modify-syntax-entry ?\( "." table)
-    (modify-syntax-entry ?\) "." table)
+    (modify-syntax-entry ?\( "(" table)
+    (modify-syntax-entry ?\) ")" table)
     (modify-syntax-entry ?\< "." table)
     (modify-syntax-entry ?\> "." table)
     (modify-syntax-entry ?\[ "." table)
@@ -278,41 +288,45 @@ By default, the region is treated as containing RFC2822 addresses.
 Dynamically bind `rfc2047-encoding-type' to change that."
   (save-restriction
     (narrow-to-region b e)
-    (if (eq 'mime rfc2047-encoding-type)
-       ;; Simple case.  Treat as single word after any initial ASCII
-       ;; part and before any tailing ASCII part.  The leading ASCII
-       ;; is relevant for instance in Subject headers with `Re:' for
-       ;; interoperability with non-MIME clients, and we might as
-       ;; well avoid the tail too.
-       (progn
-         (goto-char (point-min))
-         ;; Does it need encoding?
-         (skip-chars-forward "\000-\177")
-         (unless (eobp)
-           (skip-chars-backward "^ \n") ; beginning of space-delimited word
-           (rfc2047-encode (point) (progn
-                                     (goto-char e)
-                                     (skip-chars-backward "\000-\177")
-                                     (skip-chars-forward "^ \n")
-                                     ;; end of space-delimited word
-                                     (point)))))
-      ;; `address-mime' case -- take care of quoted words, comments.
-      (with-syntax-table rfc2047-syntax-table
-       (let ((start)                   ; start of current token
-             end                       ; end of current token
-             ;; Whether there's an encoded word before the current
-             ;; token, either immediately or separated by space.
-             last-encoded)
+    (let ((encodable-regexp (if rfc2047-encode-encoded-words
+                               "[^\000-\177]+\\|=\\?"
+                             "[^\000-\177]+"))
+         start                         ; start of current token
+         end begin
+         ;; Whether there's an encoded word before the current token,
+         ;; either immediately or separated by space.
+         last-encoded
+         (orig-text (buffer-substring-no-properties b e)))
+      (if (eq 'mime rfc2047-encoding-type)
+         ;; Simple case.  Continuous words in which all those contain
+         ;; non-ASCII characters are encoded collectively.  Encoding
+         ;; ASCII words, including `Re:' used in Subject headers, is
+         ;; avoided for interoperability with non-MIME clients and
+         ;; for making it easy to find keywords.
+         (progn
+           (goto-char (point-min))
+           (while (progn (skip-chars-forward " \t\n")
+                         (not (eobp)))
+             (setq start (point))
+             (while (and (looking-at "[ \t\n]*\\([^ \t\n]+\\)")
+                         (progn
+                           (setq end (match-end 0))
+                           (re-search-forward encodable-regexp end t)))
+               (goto-char end))
+             (if (> (point) start)
+                 (rfc2047-encode start (point))
+               (goto-char end))))
+       ;; `address-mime' case -- take care of quoted words, comments.
+       (with-syntax-table rfc2047-syntax-table
          (goto-char (point-min))
          (condition-case nil           ; in case of unbalanced quotes
              ;; Look for rfc2822-style: sequences of atoms, quoted
              ;; strings, specials, whitespace.  (Specials mustn't be
              ;; encoded.)
              (while (not (eobp))
-               (setq start (point))
                ;; Skip whitespace.
-               (unless (= 0 (skip-chars-forward " \t\n"))
-                 (setq start (point)))
+               (skip-chars-forward " \t\n")
+               (setq start (point))
                (cond
                 ((not (char-after)))   ; eob
                 ;; else token start
@@ -322,139 +336,209 @@ Dynamically bind `rfc2047-encoding-type' to change that."
                  (setq end (point))
                  ;; Does it need encoding?
                  (goto-char start)
-                 (skip-chars-forward "\000-\177" end)
-                 (if (= end (point))
-                     (setq last-encoded  nil)
-                   ;; It needs encoding.  Strip the quotes first,
-                   ;; since encoded words can't occur in quotes.
-                   (goto-char end)
-                   (delete-backward-char 1)
-                   (goto-char start)
-                   (delete-char 1)
-                   (when last-encoded
-                     ;; There was a preceding quoted word.  We need
-                     ;; to include any separating whitespace in this
-                     ;; word to avoid it getting lost.
-                     (skip-chars-backward " \t")
-                     ;; A space is needed between the encoded words.
-                     (insert ? )
-                     (setq start (point)
-                           end (1+ end)))
-                   ;; Adjust the end position for the deleted quotes.
-                   (rfc2047-encode start (- end 2))
-                   (setq last-encoded t))) ; record that it was encoded
+                 (if (re-search-forward encodable-regexp end 'move)
+                     ;; It needs encoding.  Strip the quotes first,
+                     ;; since encoded words can't occur in quotes.
+                     (progn
+                       (goto-char end)
+                       (delete-backward-char 1)
+                       (goto-char start)
+                       (delete-char 1)
+                       (when last-encoded
+                         ;; There was a preceding quoted word.  We need
+                         ;; to include any separating whitespace in this
+                         ;; word to avoid it getting lost.
+                         (skip-chars-backward " \t")
+                         ;; A space is needed between the encoded words.
+                         (insert ? )
+                         (setq start (point)
+                               end (1+ end)))
+                       ;; Adjust the end position for the deleted quotes.
+                       (rfc2047-encode start (- end 2))
+                       (setq last-encoded t)) ; record that it was encoded
+                   (setq last-encoded  nil)))
                 ((eq ?. (char-syntax (char-after)))
                  ;; Skip other delimiters, but record that they've
                  ;; potentially separated quoted words.
                  (forward-char)
                  (setq last-encoded nil))
+                ((eq ?\) (char-syntax (char-after)))
+                 (error "Unbalanced parentheses"))
+                ((eq ?\( (char-syntax (char-after)))
+                 ;; Look for the end of parentheses.
+                 (forward-list)
+                 ;; Encode text as an unstructured field.
+                 (let ((rfc2047-encoding-type 'mime))
+                   (rfc2047-encode-region (1+ start) (1- (point)))
+                   (forward-char)))
                 (t                 ; normal token/whitespace sequence
                  ;; Find the end.
-                 (forward-word 1)
-                 (skip-chars-backward " \t")
+                 ;; Skip one ASCII word, or encode continuous words
+                 ;; in which all those contain non-ASCII characters.
+                 (setq end nil)
+                 (while (not end)
+                   (when (looking-at "[\000-\177]+")
+                     (setq begin (point)
+                           end (match-end 0))
+                     (if (re-search-forward "[ \t\n]\\|\\Sw" end 'move)
+                         (progn
+                           (setq end (match-beginning 0))
+                           (if rfc2047-encode-encoded-words
+                               (progn
+                                 (goto-char begin)
+                                 (when (search-forward "=?" end 'move)
+                                   (goto-char (match-beginning 0))
+                                   (setq end nil)))
+                             (goto-char end)))
+                       (setq end nil)))
+                   (unless end
+                     (setq end t)
+                     (when (looking-at encodable-regexp)
+                       (goto-char (match-end 0))
+                       (while (and (looking-at "[ \t\n]+\\([^ \t\n]+\\)")
+                                   (setq end (match-end 0))
+                                   (string-match encodable-regexp
+                                                 (match-string 1)))
+                         (goto-char end))
+                       (when (looking-at "[^ \t\n]+")
+                         (setq end (match-end 0))
+                         (if (re-search-forward "\\Sw+" end t)
+                             ;; There are special characters better
+                             ;; to be encoded so that MTAs may parse
+                             ;; them safely.
+                             (cond ((= end (point)))
+                                   ((looking-at encodable-regexp)
+                                    (setq end nil))
+                                   (t
+                                    (goto-char (1- (match-end 0)))
+                                    (unless (= (point) (match-beginning 0))
+                                      (insert " "))))
+                           (goto-char end)
+                           (skip-chars-forward " \t\n")
+                           (if (and (looking-at "[^ \t\n]+")
+                                    (string-match encodable-regexp
+                                                  (match-string 0)))
+                               (setq end nil)
+                             (goto-char end)))))))
+                 (skip-chars-backward " \t\n")
                  (setq end (point))
-                 ;; Deal with encoding and leading space as for
-                 ;; quoted words.
                  (goto-char start)
-                 (skip-chars-forward "\000-\177" end)
-                 (if (= end (point))
-                     (setq last-encoded  nil)
-                   (when last-encoded
-                     (goto-char start)
-                     (skip-chars-backward " \t")
-                     (insert ? )
-                     (setq start (point)
-                           end (1+ end)))
-                   (rfc2047-encode start end)
-                   (setq last-encoded t)))))
+                 (if (re-search-forward encodable-regexp end 'move)
+                     (progn
+                       (rfc2047-encode start end)
+                       (setq last-encoded t))
+                   (setq last-encoded nil)))))
            (error
             (error "Invalid data for rfc2047 encoding: %s"
-                   (buffer-substring b e)))))))
-    (rfc2047-fold-region b (point))))
+                   (mm-replace-in-string orig-text "[ \t\n]+" " ")))))))
+    (rfc2047-fold-region b (point))
+    (goto-char (point-max))))
 
 (defun rfc2047-encode-string (string)
   "Encode words in STRING.
 By default, the string is treated as containing addresses (see
 `rfc2047-encoding-type')."
-  (with-temp-buffer
+  (mm-with-multibyte-buffer
     (insert string)
     (rfc2047-encode-region (point-min) (point-max))
     (buffer-string)))
 
+(defun rfc2047-encode-1 (column string cs encoder start space &optional eword)
+  "Subroutine used by `rfc2047-encode'."
+  (cond ((string-equal string "")
+        (or eword ""))
+       ((>= column 76)
+        (when (and eword
+                   (string-match "\n[ \t]+\\'" eword))
+          ;; Reomove a superfluous empty line.
+          (setq eword (substring eword 0 (match-beginning 0))))
+        (rfc2047-encode-1 (length space) string cs encoder start " "
+                          (concat eword "\n" space)))
+       (t
+        (let ((index 0)
+              (limit (1- (length string)))
+              (prev "")
+              next)
+          (while (and prev
+                      (<= index limit))
+            (setq next (concat start
+                               (funcall encoder
+                                        (if cs
+                                            (mm-encode-coding-string
+                                             (substring string 0 (1+ index))
+                                             cs)
+                                          (substring string 0 (1+ index))))
+                               "?="))
+            (if (<= (+ column (length next)) 76)
+                (setq prev next
+                      index (1+ index))
+              (setq next prev
+                    prev nil)))
+          (setq eword (concat eword next))
+          (if (> index limit)
+              eword
+            (when (string-match "\n[ \t]+\\'" eword)
+              ;; Reomove a superfluous empty line.
+              (setq eword (substring eword 0 (match-beginning 0))))
+            (rfc2047-encode-1 (length space) (substring string index)
+                              cs encoder start " "
+                              (concat eword "\n" space)))))))
+
 (defun rfc2047-encode (b e)
   "Encode the word(s) in the region B to E.
-By default, the region is treated as containing addresses (see
-`rfc2047-encoding-type')."
-  (let* ((mime-charset (mm-find-mime-charset-region b e))
-        (cs (if (> (length mime-charset) 1)
-                ;; Fixme: Instead of this, try to break region into
-                ;; parts that can be encoded separately.
-                (error "Can't rfc2047-encode `%s'"
-                       (buffer-substring b e))
-              (setq mime-charset (car mime-charset))
-              (mm-charset-to-coding-system mime-charset)))
-        ;; Fixme: Better, calculate the number of non-ASCII
-        ;; characters, at least for 8-bit charsets.
-        (encoding (or (cdr (assq mime-charset
+Point moves to the end of the region."
+  (let ((mime-charset (or (mm-find-mime-charset-region b e) (list 'us-ascii)))
+       cs encoding space eword)
+    (cond ((> (length mime-charset) 1)
+          (error "Can't rfc2047-encode `%s'"
+                 (buffer-substring-no-properties b e)))
+         ((= (length mime-charset) 1)
+          (setq mime-charset (car mime-charset)
+                cs (mm-charset-to-coding-system mime-charset))
+          (unless (and (mm-multibyte-p)
+                       (mm-coding-system-p cs))
+            (setq cs nil))
+          (save-restriction
+            (narrow-to-region b e)
+            (setq encoding
+                  (or (cdr (assq mime-charset
                                  rfc2047-charset-encoding-alist))
                       ;; For the charsets that don't have a preferred
                       ;; encoding, choose the one that's shorter.
-                      (save-restriction
-                        (narrow-to-region b e)
-                        (if (eq (rfc2047-qp-or-base64) 'base64)
-                            'B
-                          'Q))))
-        (start (concat
-                "=?" (downcase (symbol-name mime-charset)) "?"
-                (upcase (symbol-name encoding)) "?"))
-        (factor (case mime-charset
-                  ((iso-8859-5 iso-8859-7 iso-8859-8 koi8-r) 1)
-                  ((big5 gb2312 euc-kr) 2)
-                  (utf-8 4)
-                  (t 8)))
-        (pre (- b (save-restriction
-                    (widen)
-                    (point-at-bol))))
-        ;; encoded-words must not be longer than 75 characters,
-        ;; including charset, encoding etc.  This leaves us with
-        ;; 75 - (length start) - 2 - 2 characters.  The last 2 is for
-        ;; possible base64 padding.  In the worst case (iso-2022-*)
-        ;; each character expands to 8 bytes which is expanded by a
-        ;; factor of 4/3 by base64 encoding.
-        (length (floor (- 75 (length start) 4) (* factor (/ 4.0 3.0))))
-        ;; Limit line length to 76 characters.
-        (length1 (max 1 (floor (- 76 (length start) 4 pre)
-                               (* factor (/ 4.0 3.0)))))
-        (first t))
-    (if mime-charset
-       (save-restriction
-         (narrow-to-region b e)
-         (when (eq encoding 'B)
-           ;; break into lines before encoding
-           (goto-char (point-min))
-           (while (not (eobp))
-             (if first
-                 (progn
-                   (goto-char (min (point-max) (+ length1 (point))))
-                   (setq first nil))
-               (goto-char (min (point-max) (+ length (point)))))
-             (unless (eobp)
-               (insert ?\n)))
-           (setq first t))
-         (if (and (mm-multibyte-p)
-                  (mm-coding-system-p cs))
-             (mm-encode-coding-region (point-min) (point-max) cs))
-         (funcall (cdr (assq encoding rfc2047-encoding-function-alist))
-                  (point-min) (point-max))
-         (goto-char (point-min))
-         (while (not (eobp))
-           (unless first
-             (insert ? ))
-           (setq first nil)
-           (insert start)
-           (end-of-line)
-           (insert "?=")
-           (forward-line 1))))))
+                      (if (eq (rfc2047-qp-or-base64) 'base64)
+                          'B
+                        'Q)))
+            (widen)
+            (goto-char b)
+            (setq b (point-marker)
+                  e (set-marker (make-marker) e))
+            (rfc2047-fold-region (point-at-bol) b)
+            (unless (= 0 (skip-chars-backward " \t"))
+              (setq space (buffer-substring-no-properties (point) b)))
+            (setq eword (rfc2047-encode-1
+                         (- b (point-at-bol))
+                         (mm-replace-in-string
+                          (buffer-substring-no-properties b e)
+                          "\n\\([ \t]?\\)" "\\1")
+                         cs
+                         (or (cdr (assq encoding
+                                        rfc2047-encode-function-alist))
+                             'identity)
+                         (concat "=?" (downcase (symbol-name mime-charset))
+                                 "?" (upcase (symbol-name encoding)) "?")
+                         (or space " ")))
+            (delete-region (if (eq (aref eword 0) ?\n)
+                               (point)
+                             (goto-char b))
+                           e)
+            (insert eword)
+            (set-marker b nil)
+            (set-marker e nil)
+            (unless (or (eolp)
+                        (looking-at "[ \t\n)]"))
+              (insert " "))))
+         (t
+          (goto-char e)))))
 
 (defun rfc2047-fold-field ()
   "Fold the current header field."
@@ -480,6 +564,7 @@ By default, the region is treated as containing addresses (see
          (goto-char (or break qword-break))
          (setq break nil
                qword-break nil)
+         (skip-chars-backward " \t")
          (if (looking-at "[ \t]")
              (insert ?\n)
            (insert "\n "))
@@ -501,10 +586,8 @@ By default, the region is treated as containing addresses (see
          (forward-char 1))
         ((memq (char-after) '(?  ?\t))
          (skip-chars-forward " \t")
-         (if first
-             ;; Don't break just after the header name.
-             (setq first nil)
-           (setq break (1- (point)))))
+         (unless first ;; Don't break just after the header name.
+           (setq break (point))))
         ((not break)
          (if (not (looking-at "=\\?[^=]"))
              (if (eq (char-after) ?=)
@@ -515,15 +598,16 @@ By default, the region is treated as containing addresses (see
              (setq qword-break (point)))
            (skip-chars-forward "^ \t\n\r")))
         (t
-         (skip-chars-forward "^ \t\n\r"))))
+         (skip-chars-forward "^ \t\n\r")))
+       (setq first nil))
       (when (and (or break qword-break)
                 (> (- (point) bol) 76))
        (goto-char (or break qword-break))
        (setq break nil
              qword-break nil)
-       (if (looking-at "[ \t]")
-           (insert ?\n)
-         (insert "\n "))
+         (if (looking-at "[ \t]")
+             (insert ?\n)
+           (insert "\n "))
        (setq bol (1- (point)))
        ;; Don't break before the first non-LWSP characters.
        (skip-chars-forward " \t")
@@ -558,48 +642,27 @@ By default, the region is treated as containing addresses (see
        (setq eol (point-at-eol))
        (forward-line 1)))))
 
-(defun rfc2047-b-encode-region (b e)
-  "Base64-encode the header contained in region B to E."
-  (save-restriction
-    (narrow-to-region (goto-char b) e)
-    (while (not (eobp))
-      (base64-encode-region (point) (progn (end-of-line) (point)) t)
-      (if (and (bolp) (eolp))
-         (delete-backward-char 1))
-      (forward-line))))
-
-(defun rfc2047-q-encode-region (b e)
-  "Quoted-printable-encode the header in region B to E."
-  (save-excursion
-    (save-restriction
-      (narrow-to-region (goto-char b) e)
-      (let ((bol (save-restriction
-                  (widen)
-                  (point-at-bol))))
-       (quoted-printable-encode-region
-        b e nil
-        ;; = (\075), _ (\137), ? (\077) are used in the encoded word.
-        ;; Avoid using 8bit characters.
-        ;; This list excludes `especials' (see the RFC2047 syntax),
-        ;; meaning that some characters in non-structured fields will
-        ;; get encoded when they con't need to be.  The following is
-        ;; what it used to be.
-;;;     ;; Equivalent to "^\000-\007\011\013\015-\037\200-\377=_?"
-;;;     "\010\012\014\040-\074\076\100-\136\140-\177")
-        "-\b\n\f !#-'*+0-9A-Z\\^`-~\d")
-       (subst-char-in-region (point-min) (point-max) ?  ?_)
-       ;; The size of QP encapsulation is about 20, so set limit to
-       ;; 56=76-20.
-       (unless (< (- (point-max) (point-min)) 56)
-         ;; Don't break if it could fit in one line.
-         ;; Let rfc2047-encode-region break it later.
-         (goto-char (1+ (point-min)))
-         (while (and (not (bobp)) (not (eobp)))
-           (goto-char (min (point-max) (+ 56 bol)))
-           (search-backward "=" (- (point) 2) t)
-           (unless (or (bobp) (eobp))
-             (insert ?\n)
-             (setq bol (point)))))))))
+(defun rfc2047-b-encode-string (string)
+  "Base64-encode the header contained in STRING."
+  (base64-encode-string string t))
+
+(defun rfc2047-q-encode-string (string)
+  "Quoted-printable-encode the header in STRING."
+  (mm-with-unibyte-buffer
+    (insert string)
+    (quoted-printable-encode-region
+     (point-min) (point-max) nil
+     ;; = (\075), _ (\137), ? (\077) are used in the encoded word.
+     ;; Avoid using 8bit characters.
+     ;; This list excludes `especials' (see the RFC2047 syntax),
+     ;; meaning that some characters in non-structured fields will
+     ;; get encoded when they con't need to be.  The following is
+     ;; what it used to be.
+     ;;;  ;; Equivalent to "^\000-\007\011\013\015-\037\200-\377=_?"
+     ;;;  "\010\012\014\040-\074\076\100-\136\140-\177")
+     "-\b\n\f !#-'*+0-9A-Z\\^`-~\d")
+    (subst-char-in-region (point-min) (point-max) ?  ?_)
+    (buffer-string)))
 
 ;;;
 ;;; Functions for decoding RFC2047 messages
@@ -750,9 +813,8 @@ If your Emacs implementation can't decode CHARSET, return nil."
             (memq 'gnus-unknown mail-parse-ignored-charsets))
        (setq cs (mm-charset-to-coding-system mail-parse-charset)))
     (when cs
-      (when (and (eq cs 'ascii)
-                mail-parse-charset)
-       (setq cs mail-parse-charset))
+      (when (eq cs 'ascii)
+       (setq cs (or mail-parse-charset 'raw-text)))
       (mm-decode-coding-string
        (cond
        ((char-equal ?B encoding)