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/* ----------------------------------------------------------------------- *
*
* Copyright 2005-2008 H. Peter Anvin - All Rights Reserved
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom
* the Software is furnished to do so, subject to the following
* conditions:
*
* The above copyright notice and this permission notice shall
* be included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*
* ----------------------------------------------------------------------- */
/*
* unbase64.c
*
* Convert a string in base64 format to a byte array.
*/
#include <string.h>
#include <base64.h>
static const unsigned char _base64chars[] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
size_t unbase64(unsigned char *buffer, size_t bufsiz, const char *txt)
{
unsigned int bits = 0;
int nbits = 0;
char base64tbl[256];
int i;
char v;
size_t nbytes = 0;
memset(base64tbl, -1, sizeof base64tbl);
for (i = 0; _base64chars[i]; i++) {
base64tbl[_base64chars[i]] = i;
}
/* Also support filesystem safe alternate base64 encoding */
base64tbl['.'] = 62;
base64tbl['-'] = 62;
base64tbl['_'] = 63;
while (*txt) {
if ((v = base64tbl[(unsigned char)*txt]) >= 0) {
bits <<= 6;
bits += v;
nbits += 6;
if (nbits >= 8) {
if (nbytes < bufsiz)
*buffer++ = (bits >> (nbits - 8));
nbytes++;
nbits -= 8;
}
}
txt++;
}
return nbytes;
}
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