<?php
	/**
	 * Copyright 2000, 2001, 2002 Philipp von Klitzing
	 * Copyright 2003, 2004, 2005, 2006, 2007, 2008, 2009 Wim van Ravesteijn
	 *
	 * This file is part of AEGEE-Europe Statutory Event Applications.
	 *
	 * AEGEE-Europe Statutory Event Applications is free software: you can
	 * redistribute it and/or modify it under the terms of the GNU General
	 * Public License as published by the Free Software Foundation, either
	 * version 3 of the License, or (at your option) any later version.
	 *
	 * AEGEE-Europe Statutory Event Applications is distributed in the hope
	 * that it will be useful, but WITHOUT ANY WARRANTY; without even the
	 * implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
	 * PURPOSE.  See the GNU General Public License for more details.
	 *
	 * You should have received a copy of the GNU General Public License
	 * along with AEGEE-Europe Statutory Event Applications.  If not, see
	 * <http://www.gnu.org/licenses/>.
	 */
	class Tar {
		private $outdata;

		public function Tar() {
			$this->outdata = "";
		}

		public function add($data, $filename, $timestamp) {
			$filesize = strlen($data);
			$block_len = 512*ceil($filesize/512)-$filesize;
			$this->outdata .= $this->build_header($data, $filename, $timestamp);
			$this->outdata .= $data;
			$this->outdata .= pack("a".$block_len, "");
		}

		public function close() {
			return $this->outdata;
		}

		private function build_header($data, $filename, $timestamp="") {
			if( strlen($timestamp)<1 ) $timestamp = time();
			if( strlen($filename)>99 ) die('Error');
			$header = pack("a100a8a8a8a12A12a8a1a100a255",
				$filename,
				sprintf("%6s ", decoct(33188)),
				sprintf("%6s ", decoct(1000)),
				sprintf("%6s ", decoct(1000)),
				sprintf("%11s ",decoct(strlen($data))),
				sprintf("%11s", decoct($timestamp)),
				sprintf("%8s", " "),
				"0",
				"",
				""
			);
			$checksum = 0;
			for( $i=0; $i<512; $i++ ) {
				$checksum += ord(substr($header,$i,1));
			}
			$checksum_data = pack(
				"a8", sprintf("%6s ", decoct($checksum))
			);
			for( $i=0, $j=148; $i<7; $i++, $j++ )
				$header[$j] = $checksum_data[$i];
			return $header;
		}
	}
?>