-;;; mm-encode.el --- Functions for encoding MIME things
-;; Copyright (C) 1998 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>
;;; Code:
+(eval-when-compile (require 'cl))
+(require 'mail-parse)
+(require 'mailcap)
+
+(defvar mm-content-transfer-encoding-defaults
+ '(("text/x-patch" 8bit)
+ ("text/.*" qp-or-base64)
+ ("message/rfc822" 8bit)
+ ("application/emacs-lisp" 8bit)
+ ("application/x-patch" 8bit)
+ (".*" 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."
+ (insert "MIME-Version: 1.0\n")
+ (insert "Content-Type: text/plain; charset="
+ (mail-quote-string (downcase (symbol-name charset))) "\n")
+ (insert "Content-Transfer-Encoding: "
+ (downcase (symbol-name encoding)) "\n"))
+
+(defun mm-insert-multipart-headers ()
+ "Insert multipart/mixed headers."
+ (let ((boundary "=-=-="))
+ (insert "MIME-Version: 1.0\n")
+ (insert "Content-Type: multipart/mixed; boundary=\"" boundary "\"\n")
+ boundary))
+
+(defun mm-default-file-encoding (file)
+ "Return a default encoding for FILE."
+ (if (not (string-match "\\.[^.]+$" file))
+ "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) t))
+ ((eq encoding 'base64)
+ (when (equal type "text/plain")
+ (goto-char (point-min))
+ (while (search-forward "\n" nil t)
+ (replace-match "\r\n" t t)))
+ (condition-case error
+ (base64-encode-region (point-min) (point-max))
+ (error
+ (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))))
+ (t
+ (message "Unknown encoding %s; defaulting to 8bit" encoding))))
+
+(defun mm-encode-buffer (type)
+ "Encode the buffer which contains data of TYPE.
+The encoding used is returned."
+ (let* ((mime-type (if (stringp type) type (car type)))
+ (encoding
+ (or (and (listp type)
+ (cadr (assq 'encoding 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))
+
+(defun mm-insert-headers (type encoding &optional file)
+ "Insert headers for TYPE."
+ (insert "Content-Type: " type)
+ (when file
+ (insert ";\n\tname=\"" (file-name-nondirectory file) "\""))
+ (insert "\n")
+ (insert (format "Content-Transfer-Encoding: %s\n" encoding))
+ (insert "Content-Disposition: inline")
+ (when file
+ (insert ";\n\tfilename=\"" (file-name-nondirectory file) "\""))
+ (insert "\n")
+ (insert "\n"))
+
+(defun mm-content-transfer-encoding (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
+ (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
projects / gnus / blobdiff