workbench/devs/diskimage/plugins/dmg/base64.c

   1 /* Copyright 2007-2012 Fredrik Wikstrom. All rights reserved.
   2 **
   3 ** Redistribution and use in source and binary forms, with or without
   4 ** modification, are permitted provided that the following conditions
   5 ** are met:
   6 **
   7 ** 1. Redistributions of source code must retain the above copyright
   8 **    notice, this list of conditions and the following disclaimer.
   9 **
  10 ** 2. Redistributions in binary form must reproduce the above copyright
  11 **    notice, this list of conditions and the following disclaimer in the
  12 **    documentation and/or other materials provided with the distribution.
  13 **
  14 ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS `AS IS'
  15 ** AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16 ** IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17 ** ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  18 ** LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  19 ** CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  20 ** SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  21 ** INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  22 ** CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  23 ** ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  24 ** POSSIBILITY OF SUCH DAMAGE.
  25 */
  26
  27 #include <string.h>
  28 #include "base64.h"
  29
  30 static BOOL inline is_base64 (const TEXT c) {
  31         if ((c >= 'A' && c <= 'Z') ||
  32                 (c >= 'a' && c <= 'z') ||
  33                 (c >= '0' && c <= '9') ||
  34                 c == '+' || c == '/' || c == '=')
  35                 return TRUE;
  36         else
  37                 return FALSE;
  38 }
  39
  40 void cleanup_base64 (STRPTR src) {
  41         STRPTR dst = src;
  42         while (*src) {
  43                 if (is_base64(*src)) {
  44                         *dst++ = *src++;
  45                 } else {
  46                         src++;
  47                 }
  48         }
  49         *dst = 0;
  50 }
  51
  52 static inline UBYTE decode_base64_char (const TEXT c) {
  53         if (c >= 'A' && c <= 'Z') return c - 'A';
  54         if (c >= 'a' && c <= 'z') return c - 'a' + 26;
  55         if (c >= '0' && c <= '9') return c - '0' + 52;
  56         if (c == '+') return 62;
  57         if (c == '/') return 63;
  58         return 0;
  59 }
  60
  61 ULONG decode_base64(CONST_STRPTR src, STRPTR dst) {
  62         ULONG cnt, dlen;
  63         UBYTE c0, c1, c2, c3;
  64         cnt = strlen(src) >> 2;
  65         dlen = cnt * 3;
  66         while (cnt--) {
  67                 c0 = decode_base64_char(*src++);
  68                 c1 = decode_base64_char(*src++);
  69                 c2 = decode_base64_char(*src++);
  70                 c3 = decode_base64_char(*src++);
  71                 *dst++ = (c0 << 2)|(c1 >> 4);
  72                 *dst++ = (c1 << 4)|(c2 >> 2);
  73                 *dst++ = (c2 << 6)|c3;
  74         }
  75         while (*--src == '=' && dlen) dlen--;
  76         return dlen;
  77 }