1 ;;; yenc.el --- elisp native yenc decoder
3 ;; Copyright (C) 2002-2017 Free Software Foundation, Inc.
5 ;; Author: Jesper Harder <harder@ifa.au.dk>
8 ;; This file is part of GNU Emacs.
10 ;; GNU Emacs is free software: you can redistribute it and/or modify
11 ;; it under the terms of the GNU General Public License as published by
12 ;; the Free Software Foundation, either version 3 of the License, or
13 ;; (at your option) any later version.
15 ;; GNU Emacs is distributed in the hope that it will be useful,
16 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
17 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 ;; GNU General Public License for more details.
20 ;; You should have received a copy of the GNU General Public License
21 ;; along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>.
25 ;; Functions for decoding yenc encoded messages.
29 ;; * Does not handle multipart messages.
30 ;; * No support for external decoders.
31 ;; * Doesn't check the crc32 checksum (if present).
35 (eval-when-compile (require 'cl
))
37 (defconst yenc-begin-line
40 (defconst yenc-decoding-vector
41 [214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230
42 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247
43 248 249 250 251 252 253 254 255 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
44 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38
45 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61
46 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84
47 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105
48 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122
49 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139
50 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156
51 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173
52 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190
53 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207
54 208 209 210 211 212 213])
56 (defun yenc-first-part-p ()
57 "Say whether the buffer contains the first part of a yEnc file."
59 (goto-char (point-min))
60 (re-search-forward "^=ybegin part=1 " nil t
)))
62 (defun yenc-last-part-p ()
63 "Say whether the buffer contains the last part of a yEnc file."
65 (goto-char (point-min))
66 (let (total-size end-size
)
67 (when (re-search-forward "^=ybegin.*size=\\([0-9]+\\)" nil t
)
68 (setq total-size
(match-string 1)))
69 (when (re-search-forward "^=ypart.*end=\\([0-9]+\\)" nil t
)
70 (setq end-size
(match-string 1)))
73 (string= total-size end-size
)))))
76 (defun yenc-decode-region (start end
)
77 "Yenc decode region between START and END using an internal decoder."
83 (when (re-search-forward yenc-begin-line end t
)
84 (let ((first (match-end 0))
85 (header-alist (yenc-parse-line (match-string 0)))
86 bytes last footer-alist char
)
87 (when (re-search-forward "^=ypart.*$" end t
)
88 (setq first
(match-end 0)))
89 (when (re-search-forward "^=yend.*$" end t
)
90 (setq last
(match-beginning 0))
91 (setq footer-alist
(yenc-parse-line (match-string 0)))
92 (setq work-buffer
(generate-new-buffer " *yenc-work*"))
93 (with-current-buffer work-buffer
94 (set-buffer-multibyte nil
))
96 (setq char
(char-after first
))
97 (cond ((or (eq char ?
\r)
100 (setq char
(char-after (incf first
)))
101 (with-current-buffer work-buffer
102 (insert-char (mod (- char
106) 256) 1)))
104 (with-current-buffer work-buffer
105 ;;(insert-char (mod (- char 42) 256) 1)
106 (insert-char (aref yenc-decoding-vector char
) 1))))
108 (setq bytes
(buffer-size work-buffer
))
109 (unless (and (= (cdr (assq 'size header-alist
)) bytes
)
110 (= (cdr (assq 'size footer-alist
)) bytes
))
111 (message "Warning: Size mismatch while decoding."))
113 (delete-region start end
)
114 (insert-buffer-substring work-buffer
))))
115 (and work-buffer
(kill-buffer work-buffer
))))))
118 (defun yenc-extract-filename ()
119 "Extract file name from an yenc header."
121 (when (re-search-forward yenc-begin-line nil t
)
122 (cdr (assoc 'name
(yenc-parse-line (match-string 0)))))))
124 (defun yenc-parse-line (str)
125 "Extract file name and size from STR."
127 (when (string-match "^=y.*size=\\([0-9]+\\)" str
)
128 (push (cons 'size
(string-to-number (match-string 1 str
))) result
))
129 (when (string-match "^=y.*name=\\(.*\\)$" str
)
130 (setq name
(match-string 1 str
))
131 ;; Remove trailing white space
132 (when (string-match " +$" name
)
133 (setq name
(substring name
0 (match-beginning 0))))
134 (push (cons 'name name
) result
))
139 ;;; yenc.el ends here