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/* public domain */
/* BASE64 on stdin -> converted data on stdout */
#include <stdio.h>
#include <stdlib.h>
#ifdef _WIN32
#ifndef WIN32
#define WIN32
#endif
#endif
#ifdef WIN32
#include <io.h>
#include <fcntl.h>
#endif
unsigned char alphabet[64] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
int
main(void)
{
static char inalphabet[256], decoder[256];
int i, bits, char_count, errors = 0;
#ifdef WIN32
_setmode( _fileno(stdout), _O_BINARY);
#endif
for (i = (sizeof alphabet) - 1; i >= 0 ; i--) {
inalphabet[alphabet[i]] = 1;
decoder[alphabet[i]] = i;
}
#define BUFLEN 72*500 // must be multiple of 4
int len;
char buf[BUFLEN];
char outbuf[BUFLEN];
while(!feof(stdin)) {
unsigned char c;
int pos=0;
char *out=outbuf;
len=fread(buf, sizeof(c), BUFLEN, stdin);
if(!len) continue;
cont_buffer:
char_count = 0;
bits = 0;
while(pos<len) {
c=buf[pos++];
if (c == '=')
break;
if (! inalphabet[c])
continue;
bits += decoder[c];
char_count++;
if (char_count == 4) {
*out++ = ((bits >> 16));
*out++ = (((bits >> 8) & 0xff));
*out++ = ((bits & 0xff));
bits = 0;
char_count = 0;
} else {
bits <<= 6;
}
}
switch (char_count) {
case 1:
fprintf(stderr, "base64-decode: base64 encoding incomplete: at least 2 bits missing");
errors++;
break;
case 2:
*out++ = ((bits >> 10));
break;
case 3:
*out++ = ((bits >> 16));
*out++ = (((bits >> 8) & 0xff));
break;
case 0:
break;
default:
fprintf(stderr, "base64-decode: base64 encoding incomplete: at least %d bits truncated",
((4 - char_count) * 6));
}
if(pos<len) // did not proceed the whole thing, continue
goto cont_buffer;
fwrite(outbuf, sizeof(char), (out-outbuf), stdout);
}
exit(errors ? 1 : 0);
}
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