Fix for a base64 decode heap buffer overflow vulnerability.

  while((src[length] != '=') && src[length])

    length++;

  while(src[length+equalsTerm] == '=')

  /* A maximum of two = padding characters is allowed */

  if(src[length] == '=') {

    equalsTerm++;

    if(src[length+equalsTerm] == '=')

      equalsTerm++;

  }

  numQuantums = (length + equalsTerm) / 4;

  /* Don't allocate a buffer if the decoded length is 0 */

  if (numQuantums <= 0)

    return 0;

  rawlen = (numQuantums * 3) - equalsTerm;

  newstr = malloc(rawlen+1);

  /* The buffer must be large enough to make room for the last quantum

  (which may be partially thrown out) and the zero terminator. */

  newstr = malloc(rawlen+4);

  if(!newstr)

    return 0;

  *outptr = newstr;

  /* Decode all but the last quantum (which may not decode to a

  multiple of 3 bytes) */

  for(i = 0; i < numQuantums - 1; i++) {

    decodeQuantum((unsigned char *)newstr, src);

    newstr += 3; src += 4;

  }

  /* This final decode may actually read slightly past the end of the buffer

  if the input string is missing pad bytes.  This will almost always be

  harmless. */

  decodeQuantum(lastQuantum, src);

  for(i = 0; i < 3 - equalsTerm; i++)

    newstr[i] = lastQuantum[i];