(rfc2047-encoded-word-regexp): Support RFC 2231

[gnus] / lisp / rfc2047.el

diff --git a/lisp/rfc2047.el b/lisp/rfc2047.el
index 32842f5..ebd8a4a 100644 (file)
--- a/lisp/rfc2047.el
+++ b/lisp/rfc2047.el
@@ -97,6 +97,25 @@ quoted-printable and base64 respectively.")
 ;;; Functions for encoding RFC2047 messages
 ;;;
 
+(defun rfc2047-qp-or-base64 ()
+  "Return the type with which to encode the buffer.
+This is either `base64' or `quoted-printable'."
+  (save-excursion
+    (let ((limit (min (point-max) (+ 2000 (point-min))))
+         (n8bit 0))
+      (goto-char (point-min))
+      (skip-chars-forward "\x20-\x7f\r\n\t" limit)
+      (while (< (point) limit)
+       (incf n8bit)
+       (forward-char 1)
+       (skip-chars-forward "\x20-\x7f\r\n\t" limit))
+      (if (or (< (* 6 n8bit) (- limit (point-min)))
+             ;; Don't base64, say, a short line with a single
+             ;; non-ASCII char when splitting parts by charset.
+             (= n8bit 1))
+         'quoted-printable
+       'base64))))
+
 (defun rfc2047-narrow-to-field ()
   "Narrow the buffer to the header on the current line."
   (beginning-of-line)
@@ -382,7 +401,7 @@ By default, the region is treated as containing addresses (see
                       ;; encoding, choose the one that's shorter.
                       (save-restriction
                         (narrow-to-region b e)
-                        (if (eq (mm-qp-or-base64) 'base64)
+                        (if (eq (rfc2047-qp-or-base64) 'base64)
                             'B
                           'Q))))
         (start (concat
@@ -588,8 +607,8 @@ By default, the region is treated as containing addresses (see
 
 (eval-and-compile
   (defconst rfc2047-encoded-word-regexp
-    "=\\?\\([^][\000-\040()<>@,\;:\\\"/?.=]+\\)\\?\\(B\\|Q\\)\
-\\?\\([!->@-~ +]*\\)\\?="))
+    "=\\?\\([^][\000-\040()<>@,\;:*\\\"/?.=]+\\)(?:\\*[^?]+\\)?\
+\\?\\(B\\|Q\\)\\?\\([!->@-~ +]*\\)\\?="))
 
 ;; Fixme: This should decode in place, not cons intermediate strings.
 ;; Also check whether it needs to worry about delimiting fields like
@@ -668,7 +687,20 @@ By default, the region is treated as containing addresses (see
               mail-parse-charset
               (not (eq mail-parse-charset 'us-ascii))
               (not (eq mail-parse-charset 'gnus-decoded)))
-         (mm-decode-coding-string string mail-parse-charset)
+         ;; `decode-coding-string' in Emacs offers a third optional
+         ;; arg NOCOPY to avoid consing a new string if the decoding
+         ;; is "trivial".  Unfortunately it currently doesn't
+         ;; consider anything else than a `nil' coding system
+         ;; trivial.
+         ;; `rfc2047-decode-string' is called multiple times for each
+         ;; article during summary buffer generation, and we really
+         ;; want to avoid unnecessary consing.  So we bypass
+         ;; `decode-coding-string' if the string is purely ASCII.
+         (if (and (fboundp 'detect-coding-string)
+                  ;; string is purely ASCII
+                  (eq (detect-coding-string string t) 'undecided))
+             string
+           (mm-decode-coding-string string mail-parse-charset))
        (mm-string-as-multibyte string)))))
 
 (defun rfc2047-parse-and-decode (word)
@@ -681,7 +713,7 @@ decodable."
      (condition-case nil
         (rfc2047-decode
          (match-string 1 word)
-         (upcase (match-string 2 word))
+         (string-to-char (match-string 2 word))
          (match-string 3 word))
        (error word))
      word)))                           ; un-decodable
@@ -691,15 +723,19 @@ decodable."
   ;; Be more liberal to accept buggy base64 strings. If
   ;; base64-decode-string accepts buggy strings, this function could
   ;; be aliased to identity.
-  (case (mod (length string) 4)
-    (0 string)
-    (1 string) ;; Error, don't pad it.
-    (2 (concat string "=="))
-    (3 (concat string "="))))
+  (if (= 0 (mod (length string) 4))
+      string
+    (when (string-match "=+$" string)
+      (setq string (substring string 0 (match-beginning 0))))
+    (case (mod (length string) 4)
+      (0 string)
+      (1 string) ;; Error, don't pad it.
+      (2 (concat string "=="))
+      (3 (concat string "=")))))
 
 (defun rfc2047-decode (charset encoding string)
   "Decode STRING from the given MIME CHARSET in the given ENCODING.
-Valid ENCODINGs are \"B\" and \"Q\".
+Valid ENCODINGs are the characters \"B\" and \"Q\".
 If your Emacs implementation can't decode CHARSET, return nil."
   (if (stringp charset)
       (setq charset (intern (downcase charset))))
@@ -719,13 +755,13 @@ If your Emacs implementation can't decode CHARSET, return nil."
        (setq cs mail-parse-charset))
       (mm-decode-coding-string
        (cond
-       ((equal "B" encoding)
+       ((char-equal ?B encoding)
         (base64-decode-string
          (rfc2047-pad-base64 string)))
-       ((equal "Q" encoding)
+       ((char-equal ?Q encoding)
         (quoted-printable-decode-string
          (mm-subst-char-in-string ?_ ? string t)))
-       (t (error "Invalid encoding: %s" encoding)))
+       (t (error "Invalid encoding: %c" encoding)))
        cs))))
 
 (provide 'rfc2047)