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
58 (defun base64-char-to-num (c)
59 (cond ((and (<= ?A c) (<= c ?Z)) (- c ?A))
60 ((and (<= ?a c) (<= c ?z)) (+ (- c ?a) 26))
61 ((and (<= ?0 c) (<= c ?9)) (+ (- c ?0) 52))
65 (t (error "not a base64 character %c" c))))
67 (defun base64-internal-decode-string (string)
68 (let* ((len (length string))
70 (dest (make-string len 0))
74 (let ((c (aref string i)))
76 (unless (memq c '(?\x0d ?\x0a))
77 (let ((v1 (base64-char-to-num c))
78 (v2 (base64-char-to-num (aref string (prog1 i
80 (v3 (base64-char-to-num (aref string (prog1 i
82 (aset dest j (logior (lsh v1 2)(lsh v2 -4)))
85 (let ((v4 (base64-char-to-num (aref string i))))
87 (aset dest j (logior (lsh (logand v2 15) 4)(lsh v3 -2)))
90 (aset dest (prog1 j (setq j (1+ j)))
91 (logior (logand (lsh (logand v3 15) 6) 255)
100 (defun base64-internal-decode-region (beg end)
102 (let ((str (buffer-substring beg end)))
103 (delete-region beg end)
105 (insert (base64-internal-decode-string str)))))
108 ;;; @ internal base64 encoder
109 ;;; based on base64 decoder by Enami Tsugutomo
111 (defun base64-num-to-char (n)
112 (cond ((eq n nil) ?=)
114 ((< n 52) (+ ?a (- n 26)))
115 ((< n 62) (+ ?0 (- n 52)))
118 (t (error "not a base64 integer %d" n))))
120 (defun base64-encode-1 (pack)
125 (char-to-string (base64-num-to-char (ash a -2)))
129 (base64-num-to-char (logior (ash (logand a 3) 4) (ash b -4))))
133 (base64-num-to-char (logior (ash (logand b 15) 2) (ash c -6))))
134 (char-to-string (base64-num-to-char (logand c 63)))
136 (concat (char-to-string
137 (base64-num-to-char (ash (logand b 15) 2))) "=")
139 (concat (char-to-string
140 (base64-num-to-char (ash (logand a 3) 4))) "==")
143 (defun base64-encode-string (string)
144 "Encode STRING to base64, and return the result."
145 (let ((len (length string))
152 (function base64-encode-1)
153 (pack-sequence (substring string b e) 3)
160 (let* ((es (mapconcat
161 (function base64-encode-1)
162 (pack-sequence (substring string b) 3)
164 (m (mod (length es) 4))
166 (concat dest es (cond ((= m 3) "=")
171 (defun base64-internal-encode-region (beg end)
174 (narrow-to-region beg end)
175 (let ((str (buffer-substring beg end)))
176 (delete-region beg end)
177 (insert (base64-encode-string str))
185 ;;; @ base64 encoder/decoder for region
188 (defun base64-external-encode-region (beg end)
191 (narrow-to-region beg end)
193 (apply (function call-process-region)
194 beg end (car base64-external-encoder)
195 t t nil (cdr base64-external-encoder)))
197 ;; regularize line break code
198 (goto-char (point-min))
199 (while (re-search-forward "\r$" nil t)
203 (defun base64-external-decode-region (beg end)
206 (apply (function call-process-region)
207 beg end (car base64-external-decoder)
208 t t nil (cdr base64-external-decoder)))
211 (defun base64-external-decode-string (string)
215 (apply (function call-process-region)
216 (point-min) (point-max)
217 (car base64-external-decoder)
218 t t nil (cdr base64-external-decoder)))
222 (defun base64-encode-region (start end)
223 "Encode current region by base64.
224 START and END are buffer positions.
225 This function calls internal base64 encoder if size of region is
226 smaller than `base64-internal-encoding-limit', otherwise it calls
227 external base64 encoder specified by `base64-external-encoder'. In
228 this case, you must install the program (maybe mmencode included in
229 metamail or XEmacs package)."
231 (if (and base64-internal-encoding-limit
232 (> (- end start) base64-internal-encoding-limit))
233 (base64-external-encode-region start end)
234 (base64-internal-encode-region start end)))
236 (defun base64-decode-region (start end)
237 "Decode current region by base64.
238 START and END are buffer positions.
239 This function calls internal base64 decoder if size of region is
240 smaller than `base64-internal-decoding-limit', otherwise it calls
241 external base64 decoder specified by `base64-external-decoder'. In
242 this case, you must install the program (maybe mmencode included in
243 metamail or XEmacs package)."
245 (if (and base64-internal-decoding-limit
246 (> (- end start) base64-internal-decoding-limit))
247 (base64-external-decode-region start end)
248 (base64-internal-decode-region start end)))
250 (defun base64-decode-string (string)
251 "Decode STRING which is encoded in base64, and return the result.
252 This function calls internal base64 decoder if size of STRING is
253 smaller than `base64-internal-decoding-limit', otherwise it calls
254 external base64 decoder specified by `base64-external-decoder'. In
255 this case, you must install the program (maybe mmencode included in
256 metamail or XEmacs package)."
258 (if (and base64-internal-decoding-limit
259 (> (length string) base64-internal-decoding-limit))
260 (base64-external-decode-string string)
261 (base64-internal-decode-string string)))
264 ;;; @ base64 encoder/decoder for file
267 (defun base64-insert-encoded-file (filename)
268 "Encode contents of file FILENAME to base64, and insert the result.
269 It calls external base64 encoder specified by
270 `base64-external-encoder'. So you must install the program (maybe
271 mmencode included in metamail or XEmacs package)."
272 (interactive (list (read-file-name "Insert encoded file: ")))
273 (if (and base64-internal-encoding-limit
274 (> (nth 7 (file-attributes filename))
275 base64-internal-encoding-limit))
276 (apply (function call-process) (car base64-external-encoder)
277 filename t nil (cdr base64-external-encoder))
279 (base64-encode-string
281 (insert-file-contents-as-binary filename)
287 (defun base64-write-decoded-region (start end filename)
288 "Decode and write current region encoded by base64 into FILENAME.
289 START and END are buffer positions."
291 (list (region-beginning) (region-end)
292 (read-file-name "Write decoded region to file: ")))
293 (if (and base64-internal-decoding-limit
294 (> (- end start) base64-internal-decoding-limit))
296 (apply (function call-process-region)
297 start end (car base64-external-decoder)
299 (append (cdr base64-external-decoder)
300 base64-external-decoder-option-to-specify-file
302 (let ((str (buffer-substring start end)))
304 (insert (base64-internal-decode-string str))
305 (write-region-as-binary (point-min) (point-max) filename)))))
310 (defun base64-encoded-length (string)
311 (let ((len (length string)))
313 (if (= (mod len 3) 0) 0 1)
317 (defun pack-sequence (seq size)
318 "Split sequence SEQ into SIZE elements packs,
319 and return list of packs. [mel-b; tl-seq function]"
320 (let ((len (length seq)) (p 0) obj
324 (setq obj (elt seq p))
325 (setq unit (cons obj unit))
329 (setq dest (cons (reverse unit) dest))
336 (setq dest (cons (reverse unit) dest))
347 ;;; mel-b.el ends here.