;;; utf-7.el --- utf-7 coding system ;; Copyright (C) 2003 Free Software Foundation, Inc. ;; Author: Dave Love ;; Keywords: i18n, mail ;; This file is free software; you can redistribute it and/or modify ;; it under the terms of the GNU General Public License as published by ;; the Free Software Foundation; either version 2, or (at your option) ;; any later version. ;; This file is distributed in the hope that it will be useful, ;; but WITHOUT ANY WARRANTY; without even the implied warranty of ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ;; GNU General Public License for more details. ;; You should have received a copy of the GNU General Public License ;; along with GNU Emacs; see the file COPYING. If not, write to ;; the Free Software Foundation, Inc., 59 Temple Place - Suite 330, ;; Boston, MA 02111-1307, USA. ;;; Commentary: ;; Defines a coding system for UTF-7, defined in RFC 2152. Non-ASCII ;; segments are encoded as base64-encoded big endian UTF-16. Also ;; defines a variation required for IMAP (RFC 2060). ;; The encoding and decoding was originally taken from Jon K Hellan's ;; implementation in Gnus, but has been substantially re-done. ;; This probably needs more attention. In particular, it's not ;; completely consistent with iconv's behaviour. It's arguable ;; whether the IMAP version should be a coding system since it's ;; apparently only used for IMAP mailbox names, so it's commented out. ;;; Code: (make-coding-system 'utf-7 0 ?U "UTF-7 encoding of Unicode (RFC 2152)" nil `((safe-chars . ,(coding-system-get 'utf-16be 'safe-chars)) (mime-charset . utf-7) (pre-write-conversion . utf-7-pre-write-conversion) (post-read-conversion . utf-7-post-read-conversion))) ;; (make-coding-system ;; 'utf-7-imap 0 ?u ;; "UTF-7 encoding of Unicode, IMAP version (RFC 2060)" ;; nil ;; `((safe-chars . ,(coding-system-get 'utf-16be 'safe-chars)) ;; (pre-write-conversion . utf-7-imap-pre-write-conversion) ;; (post-read-conversion . utf-7-imap-post-read-conversion))) (defun utf-7-decode (len imap) "Decode LEN bytes of UTF-7 at point. IMAP non-nil means use the IMAP version." (save-excursion (save-restriction (narrow-to-region (point) (+ (point) len)) (let ((not-esc (if imap "^&" "^+")) (skip-chars (if imap "A-Za-z0-9+," "A-Za-z0-9+/"))) (while (not (eobp)) (skip-chars-forward not-esc) (unless (eobp) (forward-char) (let ((p (point)) (run-length (skip-chars-forward skip-chars))) (if (eq ?- (char-after)) (delete-char 1)) (unless (= run-length 0) ; encoded lone esc-char (let ((pl (mod (- run-length) 4))) (insert-char ?= pl) (if imap (subst-char-in-region p (point) ?, ?/)) (base64-decode-region p (point))) (decode-coding-region p (point) 'utf-16be) (save-excursion (goto-char p) (delete-backward-char 1))))))) (- (point-max) (point-min))))) (defun utf-7-post-read-conversion (len) (utf-7-decode len nil)) ;; (defun utf-7-imap-post-read-conversion (len) ;; (utf-7-decode len t)) (defun utf-7-encode (from to imap) "Encode bytes between FROM and TO to UTF-7. ESC and SKIP-CHARS are adjusted for the normal and IMAP versions." (let* ((old-buf (current-buffer)) (esc (if imap ?& ?+)) ;; These are characters which can be encoded asis. (skip-chars (if imap "\t\n\r\x20-\x25\x27-\x7e" ; rfc2060 ;; This includes the rfc2152 optional set. ;; Perhaps it shouldn't (like iconv). "\t\n\r -*,-[]-}")) (not-skip-chars (format "^%s%c" skip-chars esc))) (set-buffer (generate-new-buffer " *temp*")) (if (stringp from) (insert from) (insert-buffer-substring old-buf from to)) (goto-char (point-min)) (while (not (eobp)) (skip-chars-forward skip-chars) (if (eq ?+ (char-after)) (progn (forward-char) (insert ?-)) (unless (eobp) (insert esc) (let ((p (point))) (skip-chars-forward not-skip-chars) (save-restriction ;; encode-coding-region doesn't preserve point (narrow-to-region p (point)) (encode-coding-region p (point-max) 'utf-16be) (base64-encode-region p (point-max)) (if imap (subst-char-in-region p (point-max) ?/ ?,)) (goto-char p) ;; As I read the RFC, this isn't correct, but it's ;; consistent with iconv, at least regarding `='. (skip-chars-forward "^= \t\n") (delete-region (point) (point-max)))) (unless (eobp) (insert ?-))))) nil)) (defun utf-7-pre-write-conversion (from to) (utf-7-encode from to nil)) ;; (defun utf-7-imap-pre-write-conversion (from to) ;; (utf-7-encode from to t)) (provide 'utf-7) ;;; arch-tag: 975ee403-90a4-4286-97d2-4ed1323f4ef9 ;;; utf-7.el ends here