File: base64.c

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/*
 * This is a minimal base64 encoder. It is derived from b64.c
 * version 08/04/01 -- Create Version 0.00.00B by Bob Trower,
 * with the following changes by Max Vozeler <xam@debian.org>
 * 
 * - Stripped code not required for encoding
 * - Use LF line endings instead of CRLF
 * - Use fixed LINESIZE of 60 to follow uuencode -m
 *
 * Copyright (c) 2001 Bob Trower, Trantor Standard Systems Inc.
 * 
 * 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.
 *
 */

#include <stdio.h>

#define LINESIZE 60

static const char cb64[]=
  "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

/*
** encodeblock
**
** encode 3 8-bit binary bytes as 4 '6-bit' characters
*/

void encodeblock( unsigned char in[3], unsigned char out[4], int len )
{
    out[0] = cb64[ in[0] >> 2 ];
    out[1] = cb64[ ((in[0] & 0x03) << 4) | ((in[1] & 0xf0) >> 4) ];
    out[2] = (unsigned char) (len > 1 ? cb64[ ((in[1] & 0x0f) << 2) | ((in[2] & 0xc0) >> 6) ] : '=');
    out[3] = (unsigned char) (len > 2 ? cb64[ in[2] & 0x3f ] : '=');
}

/*
** encode
**
** base64 encode a stream adding padding and line breaks as per spec.
*/

void encode(FILE *infile, FILE *outfile)
{
    unsigned char in[3], out[4];
    int i, len, blocksout = 0;

    while( !feof( infile ) ) {
        len = 0;
        for( i = 0; i < 3; i++ ) {
            in[i] = (unsigned char) getc( infile );
            if( !feof( infile ) ) {
                len++;
            }
            else {
                in[i] = 0;
            }
        }
        if( len ) {
            encodeblock( in, out, len );
            for( i = 0; i < 4; i++ ) {
                putc( out[i], outfile );
            }
            blocksout++;
        }
        if( blocksout >= (LINESIZE/4) || feof( infile ) ) {
            if( blocksout ) {
                fprintf( outfile, "\n" );
            }
            blocksout = 0;
        }
    }
}

int main(int argc, char **argv)
{
    encode(stdin, stdout);
    if (ferror(stdin) || ferror(stdout))
        return 1;
    return 0;
}