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#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#define BYTES_PER_BLOCK 3
#define BASE64_PER_BLOCK 4
const char *lookup = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
void dump_base64_block(const unsigned char *data, size_t len, FILE* stream)
{
char out_block[BASE64_PER_BLOCK+1];
memset(out_block, '=', sizeof(out_block));
out_block[4] = '\0';
switch(len) {
case 3:
out_block[3] = lookup[data[2] & 0x3F];
case 2:
out_block[2] = lookup[(data[1] & 0x0F) << 2 | data[2] >> 6];
case 1:
out_block[1] = lookup[(data[0] & 0x03) << 4 | (data[1] & 0xF0) >> 4];
out_block[0] = lookup[data[0] >> 2];
fputs(out_block, stream);
break;
default:
break;
}
}
void dump_base64(FILE* in, FILE* out)
{
size_t nread = 0;
char buffer[BYTES_PER_BLOCK+1];
while (!feof(in)) {
nread = fread(buffer, 1, BYTES_PER_BLOCK, in);
buffer[nread] = '\0';
dump_base64_block(buffer, nread, out);
}
}
int main(void)
{
dump_base64(stdin, stdout);
fputc('\n', stdout);
}
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