<?php

/**
 * This file has a single job - database backup.
 *
 * Simple Machines Forum (SMF)
 *
 * @package SMF
 * @author Simple Machines http://www.simplemachines.org
 * @copyright 2012 Simple Machines
 * @license http://www.simplemachines.org/about/smf/license.php BSD
 *
 * @version 2.1 Alpha 1
 */

if (!defined('SMF'))
	die('Hacking attempt...');

/**
 * Dumps the database.
 * It writes all of the database to standard output.
 * It uses gzip compression if compress is set in the URL/post data.
 * It may possibly time out, and mess up badly if you were relying on it. :P
 * The data dumped depends on whether "struct" and "data" are passed.
 * It requires an administrator and the session hash by post.
 * It is called from ManageMaintenance.php.
 */
function DumpDatabase2()
{
	global $db_name, $scripturl, $context, $modSettings, $crlf, $smcFunc, $db_prefix, $db_show_debug;

	// Administrators only!
	if (!allowedTo('admin_forum'))
		fatal_lang_error('no_dump_database', 'critical');

	// We don't need debug when dumping the database
	$modSettings['disableQueryCheck'] = true;
	$db_show_debug = false;

	// You can't dump nothing!
	if (!isset($_REQUEST['struct']) && !isset($_REQUEST['data']))
		$_REQUEST['data'] = true;

	checkSession('post');

	// We will need this, badly!
	db_extend();

	// Attempt to stop from dying...
	@set_time_limit(600);
	$time_limit = ini_get('max_execution_time');
	$start_time = time();

	// @todo ... fail on not getting the requested memory?
	setMemoryLimit('256M');
	$memory_limit = memoryReturnBytes(ini_get('memory_limit')) / 4;
	$current_used_memory = 0;
	$db_backup = '';
	$output_function = 'un_compressed';

	@ob_end_clean();

	// Start saving the output... (don't do it otherwise for memory reasons.)
	if (isset($_REQUEST['compress']) && function_exists('gzencode'))
	{
		$output_function = 'gzencode';

		// Send faked headers so it will just save the compressed output as a gzip.
		header('Content-Type: application/x-gzip');
		header('Accept-Ranges: bytes');
		header('Content-Encoding: none');

		// Gecko browsers... don't like this. (Mozilla, Firefox, etc.)
		if (!isBrowser('gecko'))
			header('Content-Transfer-Encoding: binary');

		// The file extension will include .gz...
		$extension = '.sql.gz';
	}
	else
	{
		// Get rid of the gzipping alreading being done.
		if (!empty($modSettings['enableCompressedOutput']))
			@ob_end_clean();
		// If we can, clean anything already sent from the output buffer...
		elseif (ob_get_length() != 0)
			ob_clean();

		// Tell the client to save this file, even though it's text.
		header('Content-Type: ' . (isBrowser('ie') || isBrowser('opera') ? 'application/octetstream' : 'application/octet-stream'));
		header('Content-Encoding: none');

		// This time the extension should just be .sql.
		$extension = '.sql';
	}

	// This should turn off the session URL parser.
	$scripturl = '';

	// If this database is flat file and has a handler function pass it to that.
	if (!empty($smcFunc['db_get_backup']))
	{
		$smcFunc['db_get_backup']();
		exit;
	}

	// Send the proper headers to let them download this file.
	header('Content-Disposition: attachment; filename="' . $db_name . '-' . (empty($_REQUEST['struct']) ? 'data' : (empty($_REQUEST['data']) ? 'structure' : 'complete')) . '_' . strftime('%Y-%m-%d') . $extension . '"');
	header('Cache-Control: private');
	header('Connection: close');

	// This makes things simpler when using it so very very often.
	$crlf = "\r\n";

	// SQL Dump Header.
	$db_chunks =
		'-- ==========================================================' . $crlf .
		'--' . $crlf .
		'-- Database dump of tables in `' . $db_name . '`' . $crlf .
		'-- ' . timeformat(time(), false) . $crlf .
		'--' . $crlf .
		'-- ==========================================================' . $crlf .
		$crlf;

	// Get all tables in the database....
	if (preg_match('~^`(.+?)`\.(.+?)$~', $db_prefix, $match) != 0)
	{
		$db = strtr($match[1], array('`' => ''));
		$dbp = str_replace('_', '\_', $match[2]);
	}
	else
	{
		$db = false;
		$dbp = $db_prefix;
	}

	// Dump each table.
	$tables = $smcFunc['db_list_tables'](false, $db_prefix . '%');
	foreach ($tables as $tableName)
	{
		// Are we dumping the structures?
		if (isset($_REQUEST['struct']))
		{
			$db_chunks .=
				$crlf .
				'--' . $crlf .
				'-- Table structure for table `' . $tableName . '`' . $crlf .
				'--' . $crlf .
				$crlf .
				$smcFunc['db_table_sql']($tableName) . ';' . $crlf;
		}
		else
			// This is needed to speedup things later
			$smcFunc['db_table_sql']($tableName);

		// How about the data?
		if (!isset($_REQUEST['data']) || substr($tableName, -10) == 'log_errors')
			continue;

		$first_round = true;
		$close_table = false;

		// Are there any rows in this table?
		while ($get_rows = $smcFunc['db_insert_sql']($tableName, $first_round))
		{
			if (empty($get_rows))
				break;

			// Time is what we need here!
			if (function_exists('apache_reset_timeout'))
				@apache_reset_timeout();
			elseif (!empty($time_limit) && ($start_time + $time_limit - 20 > time()))
			{
				$start_time = time();
				@set_time_limit(150);
			}

			if ($first_round)
			{
				$db_chunks .=
					$crlf .
					'--' . $crlf .
					'-- Dumping data in `' . $tableName . '`' . $crlf .
					'--' . $crlf .
					$crlf;
				$first_round = false;
			}
			$db_chunks .=
				$get_rows;
			$current_used_memory += $smcFunc['strlen']($db_chunks);

			$db_backup .= $db_chunks;
			unset($db_chunks);
			$db_chunks = '';
			if ($current_used_memory > $memory_limit)
			{
				echo $output_function($db_backup);
				$current_used_memory = 0;
				// This is probably redundant
				unset($db_backup);
				$db_backup = '';
			}
			$close_table = true;
		}

		// No rows to get - skip it.
		if ($close_table)
			$db_backup .=
			'-- --------------------------------------------------------' . $crlf;
	}

	$db_backup .=
		$crlf .
		'-- Done' . $crlf;

	echo $output_function($db_backup);

	exit;
}

/**
 * Dummy/helper function, it simply returns the string passed as argument
 * @param $string, a string
 * @return the string passed
 */
function un_compressed($string = '')
{
	return $string;
}