(mm-insert-multipart-headers): Avoid redundant

[gnus] / lisp / mm-encode.el

diff --git a/lisp/mm-encode.el b/lisp/mm-encode.el
index 587abf8..0b80981 100644 (file)
--- a/lisp/mm-encode.el
+++ b/lisp/mm-encode.el
@@ -1,5 +1,5 @@
-;;; mm-encode.el --- Functions for encoding MIME things
-;; Copyright (C) 1998,99 Free Software Foundation, Inc.
+;;; mm-encode.el --- Functions for encoding MIME things 
+;; Copyright (C) 1998, 1999, 2000 Free Software Foundation, Inc.
 
 ;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
 ;;     MORIOKA Tomohiko <morioka@jaist.ac.jp>
@@ -28,12 +28,27 @@
 (require 'mailcap)
 
 (defvar mm-content-transfer-encoding-defaults
-  '(("text/.*" quoted-printable)
+  '(("text/x-patch" 8bit)
+    ("text/.*" qp-or-base64)
     ("message/rfc822" 8bit)
     ("application/emacs-lisp" 8bit)
     ("application/x-patch" 8bit)
-    (".*" base64))
-  "Alist of regexps that match MIME types and their encodings.")
+    (".*" qp-or-base64))
+  "Alist of regexps that match MIME types and their encodings.
+If the encoding is `qp-or-base64', then either quoted-printable
+or base64 will be used, depending on what is more efficient.")
+
+(defvar mm-use-ultra-safe-encoding nil
+  "If non-nil, use encodings aimed at Procrustean bed survival.
+
+This means that textual parts are encoded as quoted-printable if they
+contain lines longer than 76 characters or starting with \"From \" in
+the body.  Non-7bit encodings (8bit, binary) are generally disallowed.
+This is to reduce the probability that a broken MTA or MDA changes the
+message.
+
+This variable should never be set directly, but bound before a call to
+`mml-generate-mime' or similar functions.")
 
 (defun mm-insert-rfc822-headers (charset encoding)
   "Insert text/plain headers with CHARSET and ENCODING."
@@ -47,8 +62,7 @@
   "Insert multipart/mixed headers."
   (let ((boundary "=-=-="))
     (insert "MIME-Version: 1.0\n")
-    (insert (format "Content-Type: multipart/mixed; boundary=\"%s\"\n"
-                   boundary))
+    (insert "Content-Type: multipart/mixed; boundary=\"" boundary "\"\n")
     boundary))
 
 (defun mm-default-file-encoding (file)
@@ -57,10 +71,18 @@
       "application/octet-stream"
     (mailcap-extension-to-mime (match-string 0 file))))
 
+(defun mm-safer-encoding (encoding)
+  "Return a safer but similar encoding."
+  (cond
+   ((memq encoding '(7bit 8bit quoted-printable)) 'quoted-printable)
+   ;; The remaing encodings are binary and base64 (and perhaps some
+   ;; non-standard ones), which are both turned into base64.
+   (t 'base64)))
+
 (defun mm-encode-content-transfer-encoding (encoding &optional type)
   (cond
    ((eq encoding 'quoted-printable)
-    (quoted-printable-encode-region (point-min) (point-max)))
+    (quoted-printable-encode-region (point-min) (point-max) t))
    ((eq encoding 'base64)
     (when (equal type "text/plain")
       (goto-char (point-min))
@@ -72,8 +94,10 @@
        (message "Error while decoding: %s" error)
        nil)))
    ((memq encoding '(7bit 8bit binary))
+    ;; Do nothing.
     )
    ((null encoding)
+    ;; Do nothing.
     )
    ((functionp encoding)
     (ignore-errors (funcall encoding (point-min) (point-max))))
@@ -87,7 +111,12 @@ The encoding used is returned."
         (encoding
          (or (and (listp type)
                   (cadr (assq 'encoding type)))
-             (mm-content-transfer-encoding mime-type))))
+             (mm-content-transfer-encoding mime-type)))
+        (bits (mm-body-7-or-8)))
+    ;; We force buffers that are 7bit to be unencoded, no matter
+    ;; what the preferred encoding is.
+    (when (eq bits '7bit)
+      (setq encoding bits))
     (mm-encode-content-transfer-encoding encoding mime-type)
     encoding))
 
@@ -105,14 +134,35 @@ The encoding used is returned."
   (insert "\n"))
 
 (defun mm-content-transfer-encoding (type)
-  "Return a CTE suitable for TYPE."
+  "Return a CTE suitable for TYPE to encode the current buffer."
   (let ((rules mm-content-transfer-encoding-defaults))
     (catch 'found
       (while rules
        (when (string-match (caar rules) type)
-         (throw 'found (cadar rules)))
+         (throw 'found
+                (let ((encoding 
+                       (if (eq (cadr (car rules)) 'qp-or-base64)
+                           (mm-qp-or-base64)
+                         (cadr (car rules)))))
+                  (if mm-use-ultra-safe-encoding
+                      (mm-safer-encoding encoding)
+                    encoding))))
        (pop rules)))))
 
+(defun mm-qp-or-base64 ()
+  (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 (< (* 6 n8bit) (- limit (point-min)))
+         'quoted-printable
+       'base64))))
+
 (provide 'mm-encode)
 
 ;;; mm-encode.el ends here