protected boolean scanFileData(byte[] fileData) {
		if(fileData == null) {
			return false;
		}
	    this.fileSize = fileData.length;
	    if(this.crc32==null)
	        this.crc32=new CRC32();
	    this.crc32.reset();
	    this.crc32.update(fileData);
	    return true;
	}