SGI Freeware 1999 August/SGI Freeware 1999 August.iso/dist/fw_xemacs.idb/usr/freeware/lib/xemacs-20.4/lisp/mel/mel-b.el.z/mel-b.el

Text File | 1998-05-21 | 8.3 KB | 310 lines

;;; mel-b.el: Base64 encoder/decoder for GNU Emacs

;; Copyright (C) 1992,1995,1996,1997 Free Software Foundation, Inc.

;; Author: ENAMI Tsugutomo <[e-mail]>
;;         MORIOKA Tomohiko <[e-mail]>
;; Maintainer: MORIOKA Tomohiko <[e-mail]>
;; Created: 1995/6/24
;; Version: $Id: mel-b.el,v 6.3 1997/04/30 17:17:42 morioka Exp $
;; Keywords: MIME, Base64

;; This file is part of MEL (MIME Encoding Library).

;; This program 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 program 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.

;;; Code:

(require 'emu)


;;; @ variables
;;;

(defvar base64-external-encoder '("mmencode")
  "*list of base64 encoder program name and its arguments.")

(defvar base64-external-decoder '("mmencode" "-u")
  "*list of base64 decoder program name and its arguments.")

(defvar base64-internal-encoding-limit 1000
  "*limit size to use internal base64 encoder.
If size of input to encode is larger than this limit,
external encoder is called.")

(defvar base64-internal-decoding-limit 1000
  "*limit size to use internal base64 decoder.
If size of input to decode is larger than this limit,
external decoder is called.")


;;; @ internal base64 decoder/encoder
;;;    based on base64 decoder by Enami Tsugutomo

;;; @@ convert from/to base64 char
;;;

(defun base64-num-to-char (n)
  (cond ((eq n nil) ?=)
    ((< n 26) (+ ?A n))
    ((< n 52) (+ ?a (- n 26)))
    ((< n 62) (+ ?0 (- n 52)))
    ((= n 62) ?+)
    ((= n 63) ?/)
    (t (error "not a base64 integer %d" n))))

(defun base64-char-to-num (c)
  (cond ((and (<= ?A c) (<= c ?Z)) (- c ?A))
    ((and (<= ?a c) (<= c ?z)) (+ (- c ?a) 26))
    ((and (<= ?0 c) (<= c ?9)) (+ (- c ?0) 52))
    ((= c ?+) 62)
    ((= c ?/) 63)
    ((= c ?=) nil)
    (t (error "not a base64 character %c" c))))


;;; @@ encode/decode one base64 unit
;;;

(defun base64-encode-1 (pack)
  (let ((a (car pack))
    (b (nth 1 pack))
    (c (nth 2 pack)))
    (concat
     (char-to-string (base64-num-to-char (ash a -2)))
     (if b
     (concat
      (char-to-string
       (base64-num-to-char (logior (ash (logand a 3) 4) (ash b -4))))
      (if c
          (concat
           (char-to-string
        (base64-num-to-char (logior (ash (logand b 15) 2) (ash c -6))))
           (char-to-string (base64-num-to-char (logand c 63)))
           )
        (concat (char-to-string
             (base64-num-to-char (ash (logand b 15) 2))) "=")
        ))
       (concat (char-to-string
        (base64-num-to-char (ash (logand a 3) 4))) "==")
       ))))

(defun base64-decode-1 (pack)
  (let ((a (base64-char-to-num (car pack)))
    (b (base64-char-to-num (nth 1 pack)))
    (c (nth 2 pack))
    (d (nth 3 pack)))
    (concat (char-to-string (logior (ash a 2) (ash b -4)))
        (if (and c (setq c (base64-char-to-num c)))
        (concat (char-to-string
             (logior (ash (logand b 15) 4) (ash c -2)))
            (if (and d (setq d (base64-char-to-num d)))
                (char-to-string (logior (ash (logand c 3) 6) d))
              ))))))


;;; @@ base64 encoder/decoder for string
;;;

(defun base64-encode-string (string)
  "Encode STRING to base64, and return the result."
  (let ((len (length string))
    (b 0)(e 57)
    dest)
    (while (< e len)
      (setq dest
        (concat dest
            (mapconcat
             (function base64-encode-1)
             (pack-sequence (substring string b e) 3)
             "")
            "\n"))
      (setq b e
        e (+ e 57)
        )
      )
    (let* ((es (mapconcat
        (function base64-encode-1)
        (pack-sequence (substring string b) 3)
        ""))
       (m (mod (length es) 4))
       )
      (concat dest es (cond ((= m 3) "=")
                ((= m 2) "==")
                ))
      )))

(defun base64-decode-string (string)
  "Decode STRING which is encoded in base64, and return the result."
  (mapconcat (function base64-decode-1)
         (pack-sequence string 4)
         ""))


;;; @ base64 encoder/decoder for region
;;;

(defun base64-internal-encode-region (beg end)
  (save-excursion
    (save-restriction
      (narrow-to-region beg end)
      (let ((str (buffer-substring beg end)))
    (delete-region beg end)
    (insert (base64-encode-string str))
    )
      (or (bolp)
      (insert "\n")
      )
      )))

(defun base64-internal-decode-region (beg end)
  (save-excursion
    (save-restriction
      (narrow-to-region beg end)
      (goto-char (point-min))
      (while (looking-at ".*\n")
    (condition-case err
        (replace-match
         (base64-decode-string
          (buffer-substring (match-beginning 0) (1- (match-end 0))))
         t t)
      (error
       (prog1
           (message (nth 1 err))
         (replace-match "")))))
      (if (looking-at ".*$")
      (condition-case err
          (replace-match
           (base64-decode-string
        (buffer-substring (match-beginning 0) (match-end 0)))
           t t)
        (error
         (prog1
         (message (nth 1 err))
           (replace-match "")))
        ))
      )))

(defun base64-external-encode-region (beg end)
  (save-excursion
    (save-restriction
      (narrow-to-region beg end)
      (as-binary-process (apply (function call-process-region)
                beg end (car base64-external-encoder)
                t t nil (cdr base64-external-encoder))
             )
      ;; for OS/2
      ;;   regularize line break code
      (goto-char (point-min))
      (while (re-search-forward "\r$" nil t)
    (replace-match "")
    )
      )))

(defun base64-external-decode-region (beg end)
  (save-excursion
    (as-binary-process (apply (function call-process-region)
                  beg end (car base64-external-decoder)
                  t t nil (cdr base64-external-decoder))
               )))

(defun base64-encode-region (start end)
  "Encode current region by base64.
START and END are buffer positions.
This function calls internal base64 encoder if size of region is
smaller than `base64-internal-encoding-limit', otherwise it calls
external base64 encoder specified by `base64-external-encoder'.  In
this case, you must install the program (maybe mmencode included in
metamail or XEmacs package)."
  (interactive "r")
  (if (and base64-internal-encoding-limit
       (> (- end start) base64-internal-encoding-limit))
      (base64-external-encode-region start end)
    (base64-internal-encode-region start end)
    ))

(defun base64-decode-region (start end)
  "Decode current region by base64.
START and END are buffer positions.
This function calls internal base64 decoder if size of region is
smaller than `base64-internal-decoding-limit', otherwise it calls
external base64 decoder specified by `base64-external-decoder'.  In
this case, you must install the program (maybe mmencode included in
metamail or XEmacs package)."
  (interactive "r")
  (if (and base64-internal-decoding-limit
       (> (- end start) base64-internal-decoding-limit))
      (base64-external-decode-region start end)
    (base64-internal-decode-region start end)
    ))


;;; @ base64 encoder/decoder for file
;;;

(defun base64-insert-encoded-file (filename)
  "Encode contents of file FILENAME to base64, and insert the result.
It calls external base64 encoder specified by
`base64-external-encoder'.  So you must install the program (maybe
mmencode included in metamail or XEmacs package)."
  (interactive (list (read-file-name "Insert encoded file: ")))
  (apply (function call-process) (car base64-external-encoder)
     filename t nil (cdr base64-external-encoder))
  )


;;; @ etc
;;;

(defun base64-encoded-length (string)
  (let ((len (length string)))
    (* (+ (/ len 3)
      (if (= (mod len 3) 0) 0 1)
      ) 4)
    ))

(defun pack-sequence (seq size)
  "Split sequence SEQ into SIZE elements packs,
and return list of packs. [mel-b; tl-seq function]"
  (let ((len (length seq)) (p 0) obj
    unit (i 0)
    dest)
    (while (< p len)
      (setq obj (elt seq p))
      (setq unit (cons obj unit))
      (setq i (1+ i))
      (if (= i size)
      (progn
        (setq dest (cons (reverse unit) dest))
        (setq unit nil)
        (setq i 0)
        ))
      (setq p (1+ p))
      )
    (if unit
    (setq dest (cons (reverse unit) dest))
      )
    (reverse dest)
    ))


;;; @ end
;;;

(provide 'mel-b)

;;; mel-b.el ends here.