1 ;;; mel-b.el: Base64 encoder/decoder for GNU Emacs
3 ;; Copyright (C) 1992,1995,1996,1997,1998 Free Software Foundation, Inc.
5 ;; Author: ENAMI Tsugutomo <enami@sys.ptg.sony.co.jp>
6 ;; MORIOKA Tomohiko <morioka@jaist.ac.jp>
8 ;; Keywords: MIME, Base64
10 ;; This file is part of MEL (MIME Encoding Library).
12 ;; This program is free software; you can redistribute it and/or
13 ;; modify it under the terms of the GNU General Public License as
14 ;; published by the Free Software Foundation; either version 2, or (at
15 ;; your option) any later version.
17 ;; This program is distributed in the hope that it will be useful, but
18 ;; WITHOUT ANY WARRANTY; without even the implied warranty of
19 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
20 ;; General Public License for more details.
22 ;; You should have received a copy of the GNU General Public License
23 ;; along with GNU Emacs; see the file COPYING. If not, write to the
24 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
25 ;; Boston, MA 02111-1307, USA.
35 (defvar base64-external-encoder '("mmencode")
36 "*list of base64 encoder program name and its arguments.")
38 (defvar base64-external-decoder '("mmencode" "-u")
39 "*list of base64 decoder program name and its arguments.")
41 (defvar base64-external-decoder-option-to-specify-file '("-o")
42 "*list of options of base64 decoder program to specify file.")
44 (defvar base64-internal-encoding-limit 1000
45 "*limit size to use internal base64 encoder.
46 If size of input to encode is larger than this limit,
47 external encoder is called.")
49 (defvar base64-internal-decoding-limit 1000
50 "*limit size to use internal base64 decoder.
51 If size of input to decode is larger than this limit,
52 external decoder is called.")
55 ;;; @ internal base64 decoder/encoder
56 ;;; based on base64 decoder by Enami Tsugutomo
58 ;;; @@ convert from/to base64 char
61 (defun base64-num-to-char (n)
64 ((< n 52) (+ ?a (- n 26)))
65 ((< n 62) (+ ?0 (- n 52)))
68 (t (error "not a base64 integer %d" n))))
70 (defun base64-char-to-num (c)
71 (cond ((and (<= ?A c) (<= c ?Z)) (- c ?A))
72 ((and (<= ?a c) (<= c ?z)) (+ (- c ?a) 26))
73 ((and (<= ?0 c) (<= c ?9)) (+ (- c ?0) 52))
77 (t (error "not a base64 character %c" c))))
80 ;;; @@ encode/decode one base64 unit
83 (defun base64-encode-1 (pack)
88 (char-to-string (base64-num-to-char (ash a -2)))
92 (base64-num-to-char (logior (ash (logand a 3) 4) (ash b -4))))
96 (base64-num-to-char (logior (ash (logand b 15) 2) (ash c -6))))
97 (char-to-string (base64-num-to-char (logand c 63)))
99 (concat (char-to-string
100 (base64-num-to-char (ash (logand b 15) 2))) "=")
102 (concat (char-to-string
103 (base64-num-to-char (ash (logand a 3) 4))) "==")
106 (defun base64-decode-unit (a b &optional c d)
109 (char-to-string (logior (ash (base64-char-to-num a) 2)
110 (ash (setq b (base64-char-to-num b)) -4)))
111 (if (and c (setq c (base64-char-to-num c)))
112 (concat (char-to-string
113 (logior (ash (logand b 15) 4) (ash c -2)))
114 (if (and d (setq d (base64-char-to-num d)))
115 (char-to-string (logior (ash (logand c 3) 6) d))
117 (error (message (nth 1 err))
121 ;;; @@ base64 encoder/decoder for string
124 (defun base64-encode-string (string)
125 "Encode STRING to base64, and return the result."
126 (let ((len (length string))
133 (function base64-encode-1)
134 (pack-sequence (substring string b e) 3)
141 (let* ((es (mapconcat
142 (function base64-encode-1)
143 (pack-sequence (substring string b) 3)
145 (m (mod (length es) 4))
147 (concat dest es (cond ((= m 3) "=")
152 (defun base64-internal-decode-string (string)
153 "Decode STRING which is encoded in base64, and return the result."
154 (let ((len (length string))
158 (let ((a (aref string i)))
161 (let ((b (aref string i)))
168 (setq dest (concat dest (base64-decode-unit a b) ))
171 (let ((c (aref string i)))
175 (setq dest (concat dest (base64-decode-unit a b)))
178 (setq dest (concat dest (base64-decode-unit a b c)))
181 (let ((d (aref string i)))
186 (base64-decode-unit a b c)
187 (base64-decode-unit a b c d))))
191 (defalias 'base64-decode-string 'base64-internal-decode-string)
194 ;;; @ base64 encoder/decoder for region
197 (defun base64-internal-encode-region (beg end)
200 (narrow-to-region beg end)
201 (let ((str (buffer-substring beg end)))
202 (delete-region beg end)
203 (insert (base64-encode-string str))
210 (defun base64-internal-decode-region (beg end)
212 (let ((str (buffer-substring beg end)))
213 (delete-region beg end)
215 (insert (base64-internal-decode-string str)))))
217 (defun base64-external-encode-region (beg end)
220 (narrow-to-region beg end)
221 (as-binary-process (apply (function call-process-region)
222 beg end (car base64-external-encoder)
223 t t nil (cdr base64-external-encoder))
226 ;; regularize line break code
227 (goto-char (point-min))
228 (while (re-search-forward "\r$" nil t)
233 (defun base64-external-decode-region (beg end)
235 (as-binary-process (apply (function call-process-region)
236 beg end (car base64-external-decoder)
237 t t nil (cdr base64-external-decoder))
240 (defun base64-encode-region (start end)
241 "Encode current region by base64.
242 START and END are buffer positions.
243 This function calls internal base64 encoder if size of region is
244 smaller than `base64-internal-encoding-limit', otherwise it calls
245 external base64 encoder specified by `base64-external-encoder'. In
246 this case, you must install the program (maybe mmencode included in
247 metamail or XEmacs package)."
249 (if (and base64-internal-encoding-limit
250 (> (- end start) base64-internal-encoding-limit))
251 (base64-external-encode-region start end)
252 (base64-internal-encode-region start end)
255 (defun base64-decode-region (start end)
256 "Decode current region by base64.
257 START and END are buffer positions.
258 This function calls internal base64 decoder if size of region is
259 smaller than `base64-internal-decoding-limit', otherwise it calls
260 external base64 decoder specified by `base64-external-decoder'. In
261 this case, you must install the program (maybe mmencode included in
262 metamail or XEmacs package)."
264 (if (and base64-internal-decoding-limit
265 (> (- end start) base64-internal-decoding-limit))
266 (base64-external-decode-region start end)
267 (base64-internal-decode-region start end)
271 ;;; @ base64 encoder/decoder for file
274 (defun base64-insert-encoded-file (filename)
275 "Encode contents of file FILENAME to base64, and insert the result.
276 It calls external base64 encoder specified by
277 `base64-external-encoder'. So you must install the program (maybe
278 mmencode included in metamail or XEmacs package)."
279 (interactive (list (read-file-name "Insert encoded file: ")))
280 (apply (function call-process) (car base64-external-encoder)
281 filename t nil (cdr base64-external-encoder))
284 (defun base64-write-decoded-region (start end filename)
285 "Decode and write current region encoded by base64 into FILENAME.
286 START and END are buffer positions."
288 (list (region-beginning) (region-end)
289 (read-file-name "Write decoded region to file: ")))
291 (apply (function call-process-region)
292 start end (car base64-external-decoder)
294 (append (cdr base64-external-decoder)
295 base64-external-decoder-option-to-specify-file
303 (defun base64-encoded-length (string)
304 (let ((len (length string)))
306 (if (= (mod len 3) 0) 0 1)
310 (defun pack-sequence (seq size)
311 "Split sequence SEQ into SIZE elements packs,
312 and return list of packs. [mel-b; tl-seq function]"
313 (let ((len (length seq)) (p 0) obj
317 (setq obj (elt seq p))
318 (setq unit (cons obj unit))
322 (setq dest (cons (reverse unit) dest))
329 (setq dest (cons (reverse unit) dest))
340 ;;; mel-b.el ends here.