<?php

/**

 * CodeIgniter

 *

 * An open source application development framework for PHP

 *

 * This content is released under the MIT License (MIT)

 *

 * Copyright (c) 2014 - 2017, British Columbia Institute of Technology

 *

 * 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.

 *

 * @package	CodeIgniter

 * @author	EllisLab Dev Team

 * @copyright	Copyright (c) 2008 - 2014, EllisLab, Inc. (https://ellislab.com/)

 * @copyright	Copyright (c) 2014 - 2017, British Columbia Institute of Technology (http://bcit.ca/)

 * @license	http://opensource.org/licenses/MIT	MIT License

 * @link	https://codeigniter.com

 * @since	Version 1.0.0

 * @filesource

 */

defined('BASEPATH') OR exit('No direct script access allowed');



/**

 * Database Driver Class

 *

 * This is the platform-independent base DB implementation class.

 * This class will not be called directly. Rather, the adapter

 * class for the specific database will extend and instantiate it.

 *

 * @package		CodeIgniter

 * @subpackage	Drivers

 * @category	Database

 * @author		EllisLab Dev Team

 * @link		https://codeigniter.com/user_guide/database/

 */

abstract class CI_DB_driver {



	/**

	 * Data Source Name / Connect string

	 *

	 * @var	string

	 */

	public $dsn;



	/**

	 * Username

	 *

	 * @var	string

	 */

	public $username;



	/**

	 * Password

	 *

	 * @var	string

	 */

	public $password;



	/**

	 * Hostname

	 *

	 * @var	string

	 */

	public $hostname;



	/**

	 * Database name

	 *

	 * @var	string

	 */

	public $database;



	/**

	 * Database driver

	 *

	 * @var	string

	 */

	public $dbdriver		= 'mysqli';



	/**

	 * Sub-driver

	 *

	 * @used-by	CI_DB_pdo_driver

	 * @var	string

	 */

	public $subdriver;



	/**

	 * Table prefix

	 *

	 * @var	string

	 */

	public $dbprefix		= '';



	/**

	 * Character set

	 *

	 * @var	string

	 */

	public $char_set		= 'utf8';



	/**

	 * Collation

	 *

	 * @var	string

	 */

	public $dbcollat		= 'utf8_general_ci';



	/**

	 * Encryption flag/data

	 *

	 * @var	mixed

	 */

	public $encrypt			= FALSE;



	/**

	 * Swap Prefix

	 *

	 * @var	string

	 */

	public $swap_pre		= '';



	/**

	 * Database port

	 *

	 * @var	int

	 */

	public $port			= '';



	/**

	 * Persistent connection flag

	 *

	 * @var	bool

	 */

	public $pconnect		= FALSE;



	/**

	 * Connection ID

	 *

	 * @var	object|resource

	 */

	public $conn_id			= FALSE;



	/**

	 * Result ID

	 *

	 * @var	object|resource

	 */

	public $result_id		= FALSE;



	/**

	 * Debug flag

	 *

	 * Whether to display error messages.

	 *

	 * @var	bool

	 */

	public $db_debug		= FALSE;



	/**

	 * Benchmark time

	 *

	 * @var	int

	 */

	public $benchmark		= 0;



	/**

	 * Executed queries count

	 *

	 * @var	int

	 */

	public $query_count		= 0;



	/**

	 * Bind marker

	 *

	 * Character used to identify values in a prepared statement.

	 *

	 * @var	string

	 */

	public $bind_marker		= '?';



	/**

	 * Save queries flag

	 *

	 * Whether to keep an in-memory history of queries for debugging purposes.

	 *

	 * @var	bool

	 */

	public $save_queries		= TRUE;



	/**

	 * Queries list

	 *

	 * @see	CI_DB_driver::$save_queries

	 * @var	string[]

	 */

	public $queries			= array();



	/**

	 * Query times

	 *

	 * A list of times that queries took to execute.

	 *

	 * @var	array

	 */

	public $query_times		= array();



	/**

	 * Data cache

	 *

	 * An internal generic value cache.

	 *

	 * @var	array

	 */

	public $data_cache		= array();



	/**

	 * Transaction enabled flag

	 *

	 * @var	bool

	 */

	public $trans_enabled		= TRUE;



	/**

	 * Strict transaction mode flag

	 *

	 * @var	bool

	 */

	public $trans_strict		= TRUE;



	/**

	 * Transaction depth level

	 *

	 * @var	int

	 */

	protected $_trans_depth		= 0;



	/**

	 * Transaction status flag

	 *

	 * Used with transactions to determine if a rollback should occur.

	 *

	 * @var	bool

	 */

	protected $_trans_status	= TRUE;



	/**

	 * Transaction failure flag

	 *

	 * Used with transactions to determine if a transaction has failed.

	 *

	 * @var	bool

	 */

	protected $_trans_failure	= FALSE;



	/**

	 * Cache On flag

	 *

	 * @var	bool

	 */

	public $cache_on		= FALSE;



	/**

	 * Cache directory path

	 *

	 * @var	bool

	 */

	public $cachedir		= '';



	/**

	 * Cache auto-delete flag

	 *

	 * @var	bool

	 */

	public $cache_autodel		= FALSE;



	/**

	 * DB Cache object

	 *

	 * @see	CI_DB_cache

	 * @var	object

	 */

	public $CACHE;



	/**

	 * Protect identifiers flag

	 *

	 * @var	bool

	 */

	protected $_protect_identifiers		= TRUE;



	/**

	 * List of reserved identifiers

	 *

	 * Identifiers that must NOT be escaped.

	 *

	 * @var	string[]

	 */

	protected $_reserved_identifiers	= array('*');



	/**

	 * Identifier escape character

	 *

	 * @var	string

	 */

	protected $_escape_char = '"';



	/**

	 * ESCAPE statement string

	 *

	 * @var	string

	 */

	protected $_like_escape_str = " ESCAPE '%s' ";



	/**

	 * ESCAPE character

	 *

	 * @var	string

	 */

	protected $_like_escape_chr = '!';



	/**

	 * ORDER BY random keyword

	 *

	 * @var	array

	 */

	protected $_random_keyword = array('RAND()', 'RAND(%d)');



	/**

	 * COUNT string

	 *

	 * @used-by	CI_DB_driver::count_all()

	 * @used-by	CI_DB_query_builder::count_all_results()

	 *

	 * @var	string

	 */

	protected $_count_string = 'SELECT COUNT(*) AS ';



	// --------------------------------------------------------------------



	/**

	 * Class constructor

	 *

	 * @param	array	$params

	 * @return	void

	 */

	public function __construct($params)

	{

		if (is_array($params))

		{

			foreach ($params as $key => $val)

			{

				$this->$key = $val;

			}

		}



		log_message('info', 'Database Driver Class Initialized');

	}



	// --------------------------------------------------------------------



	/**

	 * Initialize Database Settings

	 *

	 * @return	bool

	 */

	public function initialize()

	{

		/* If an established connection is available, then there's

		 * no need to connect and select the database.

		 *

		 * Depending on the database driver, conn_id can be either

		 * boolean TRUE, a resource or an object.

		 */

		if ($this->conn_id)

		{

			return TRUE;

		}



		// ----------------------------------------------------------------



		// Connect to the database and set the connection ID

		$this->conn_id = $this->db_connect($this->pconnect);



		// No connection resource? Check if there is a failover else throw an error

		if ( ! $this->conn_id)

		{

			// Check if there is a failover set

			if ( ! empty($this->failover) && is_array($this->failover))

			{

				// Go over all the failovers

				foreach ($this->failover as $failover)

				{

					// Replace the current settings with those of the failover

					foreach ($failover as $key => $val)

					{

						$this->$key = $val;

					}



					// Try to connect

					$this->conn_id = $this->db_connect($this->pconnect);



					// If a connection is made break the foreach loop

					if ($this->conn_id)

					{

						break;

					}

				}

			}



			// We still don't have a connection?

			if ( ! $this->conn_id)

			{

				log_message('error', 'Unable to connect to the database');



				if ($this->db_debug)

				{

					$this->display_error('db_unable_to_connect');

				}



				return FALSE;

			}

		}



		// Now we set the character set and that's all

		return $this->db_set_charset($this->char_set);

	}



	// --------------------------------------------------------------------



	/**

	 * DB connect

	 *

	 * This is just a dummy method that all drivers will override.

	 *

	 * @return	mixed

	 */

	public function db_connect()

	{

		return TRUE;

	}



	// --------------------------------------------------------------------



	/**

	 * Persistent database connection

	 *

	 * @return	mixed

	 */

	public function db_pconnect()

	{

		return $this->db_connect(TRUE);

	}



	// --------------------------------------------------------------------



	/**

	 * Reconnect

	 *

	 * Keep / reestablish the db connection if no queries have been

	 * sent for a length of time exceeding the server's idle timeout.

	 *

	 * This is just a dummy method to allow drivers without such

	 * functionality to not declare it, while others will override it.

	 *

	 * @return	void

	 */

	public function reconnect()

	{

	}



	// --------------------------------------------------------------------



	/**

	 * Select database

	 *

	 * This is just a dummy method to allow drivers without such

	 * functionality to not declare it, while others will override it.

	 *

	 * @return	bool

	 */

	public function db_select()

	{

		return TRUE;

	}



	// --------------------------------------------------------------------



	/**

	 * Last error

	 *

	 * @return	array

	 */

	public function error()

	{

		return array('code' => NULL, 'message' => NULL);

	}



	// --------------------------------------------------------------------



	/**

	 * Set client character set

	 *

	 * @param	string

	 * @return	bool

	 */

	public function db_set_charset($charset)

	{

		if (method_exists($this, '_db_set_charset') && ! $this->_db_set_charset($charset))

		{

			log_message('error', 'Unable to set database connection charset: '.$charset);



			if ($this->db_debug)

			{

				$this->display_error('db_unable_to_set_charset', $charset);

			}



			return FALSE;

		}



		return TRUE;

	}



	// --------------------------------------------------------------------



	/**

	 * The name of the platform in use (mysql, mssql, etc...)

	 *

	 * @return	string

	 */

	public function platform()

	{

		return $this->dbdriver;

	}



	// --------------------------------------------------------------------



	/**

	 * Database version number

	 *

	 * Returns a string containing the version of the database being used.

	 * Most drivers will override this method.

	 *

	 * @return	string

	 */

	public function version()

	{

		if (isset($this->data_cache['version']))

		{

			return $this->data_cache['version'];

		}



		if (FALSE === ($sql = $this->_version()))

		{

			return ($this->db_debug) ? $this->display_error('db_unsupported_function') : FALSE;

		}



		$query = $this->query($sql)->row();

		return $this->data_cache['version'] = $query->ver;

	}



	// --------------------------------------------------------------------



	/**

	 * Version number query string

	 *

	 * @return	string

	 */

	protected function _version()

	{

		return 'SELECT VERSION() AS ver';

	}



	// --------------------------------------------------------------------



	/**

	 * Execute the query

	 *

	 * Accepts an SQL string as input and returns a result object upon

	 * successful execution of a "read" type query. Returns boolean TRUE

	 * upon successful execution of a "write" type query. Returns boolean

	 * FALSE upon failure, and if the $db_debug variable is set to TRUE

	 * will raise an error.

	 *

	 * @param	string	$sql

	 * @param	array	$binds = FALSE		An array of binding data

	 * @param	bool	$return_object = NULL

	 * @return	mixed

	 */

	public function query($sql, $binds = FALSE, $return_object = NULL)

	{

		if ($sql === '')

		{

			log_message('error', 'Invalid query: '.$sql);

			return ($this->db_debug) ? $this->display_error('db_invalid_query') : FALSE;

		}

		elseif ( ! is_bool($return_object))

		{

			$return_object = ! $this->is_write_type($sql);

		}



		// Verify table prefix and replace if necessary

		if ($this->dbprefix !== '' && $this->swap_pre !== '' && $this->dbprefix !== $this->swap_pre)

		{

			$sql = preg_replace('/(\W)'.$this->swap_pre.'(\S+?)/', '\\1'.$this->dbprefix.'\\2', $sql);

		}



		// Compile binds if needed

		if ($binds !== FALSE)

		{

			$sql = $this->compile_binds($sql, $binds);

		}



		// Is query caching enabled? If the query is a "read type"

		// we will load the caching class and return the previously

		// cached query if it exists

		if ($this->cache_on === TRUE && $return_object === TRUE && $this->_cache_init())

		{

			$this->load_rdriver();

			if (FALSE !== ($cache = $this->CACHE->read($sql)))

			{

				return $cache;

			}

		}



		// Save the query for debugging

		if ($this->save_queries === TRUE)

		{

			$this->queries[] = $sql;

		}



		// Start the Query Timer

		$time_start = microtime(TRUE);



		// Run the Query

		if (FALSE === ($this->result_id = $this->simple_query($sql)))

		{

			if ($this->save_queries === TRUE)

			{

				$this->query_times[] = 0;

			}



			// This will trigger a rollback if transactions are being used

			if ($this->_trans_depth !== 0)

			{

				$this->_trans_status = FALSE;

			}



			// Grab the error now, as we might run some additional queries before displaying the error

			$error = $this->error();



			// Log errors

			log_message('error', 'Query error: '.$error['message'].' - Invalid query: '.$sql);



			if ($this->db_debug)

			{

				// We call this function in order to roll-back queries

				// if transactions are enabled. If we don't call this here

				// the error message will trigger an exit, causing the

				// transactions to remain in limbo.

				while ($this->_trans_depth !== 0)

				{

					$trans_depth = $this->_trans_depth;

					$this->trans_complete();

					if ($trans_depth === $this->_trans_depth)

					{

						log_message('error', 'Database: Failure during an automated transaction commit/rollback!');

						break;

					}

				}



				// Display errors

				return $this->display_error(array('Error Number: '.$error['code'], $error['message'], $sql));

			}



			return FALSE;

		}



		// Stop and aggregate the query time results

		$time_end = microtime(TRUE);

		$this->benchmark += $time_end - $time_start;



		if ($this->save_queries === TRUE)

		{

			$this->query_times[] = $time_end - $time_start;

		}



		// Increment the query counter

		$this->query_count++;



		// Will we have a result object instantiated? If not - we'll simply return TRUE

		if ($return_object !== TRUE)

		{

			// If caching is enabled we'll auto-cleanup any existing files related to this particular URI

			if ($this->cache_on === TRUE && $this->cache_autodel === TRUE && $this->_cache_init())

			{

				$this->CACHE->delete();

			}



			return TRUE;

		}



		// Load and instantiate the result driver

		$driver		= $this->load_rdriver();

		$RES		= new $driver($this);



		// Is query caching enabled? If so, we'll serialize the

		// result object and save it to a cache file.

		if ($this->cache_on === TRUE && $this->_cache_init())

		{

			// We'll create a new instance of the result object

			// only without the platform specific driver since

			// we can't use it with cached data (the query result

			// resource ID won't be any good once we've cached the

			// result object, so we'll have to compile the data

			// and save it)

			$CR = new CI_DB_result($this);

			$CR->result_object	= $RES->result_object();

			$CR->result_array	= $RES->result_array();

			$CR->num_rows		= $RES->num_rows();



			// Reset these since cached objects can not utilize resource IDs.

			$CR->conn_id		= NULL;

			$CR->result_id		= NULL;



			$this->CACHE->write($sql, $CR);

		}



		return $RES;

	}



	// --------------------------------------------------------------------



	/**

	 * Load the result drivers

	 *

	 * @return	string	the name of the result class

	 */

	public function load_rdriver()

	{

		$driver = 'CI_DB_'.$this->dbdriver.'_result';



		if ( ! class_exists($driver, FALSE))

		{

			require_once(BASEPATH.'database/DB_result.php');

			require_once(BASEPATH.'database/drivers/'.$this->dbdriver.'/'.$this->dbdriver.'_result.php');

		}



		return $driver;

	}



	// --------------------------------------------------------------------



	/**

	 * Simple Query

	 * This is a simplified version of the query() function. Internally

	 * we only use it when running transaction commands since they do

	 * not require all the features of the main query() function.

	 *

	 * @param	string	the sql query

	 * @return	mixed

	 */

	public function simple_query($sql)

	{

		if ( ! $this->conn_id)

		{

			if ( ! $this->initialize())

			{

				return FALSE;

			}

		}



		return $this->_execute($sql);

	}



	// --------------------------------------------------------------------



	/**

	 * Disable Transactions

	 * This permits transactions to be disabled at run-time.

	 *

	 * @return	void

	 */

	public function trans_off()

	{

		$this->trans_enabled = FALSE;

	}



	// --------------------------------------------------------------------



	/**

	 * Enable/disable Transaction Strict Mode

	 *

	 * When strict mode is enabled, if you are running multiple groups of

	 * transactions, if one group fails all subsequent groups will be

	 * rolled back.

	 *

	 * If strict mode is disabled, each group is treated autonomously,

	 * meaning a failure of one group will not affect any others

	 *

	 * @param	bool	$mode = TRUE

	 * @return	void

	 */

	public function trans_strict($mode = TRUE)

	{

		$this->trans_strict = is_bool($mode) ? $mode : TRUE;

	}



	// --------------------------------------------------------------------



	/**

	 * Start Transaction

	 *

	 * @param	bool	$test_mode = FALSE

	 * @return	bool

	 */

	public function trans_start($test_mode = FALSE)

	{

		if ( ! $this->trans_enabled)

		{

			return FALSE;

		}



		return $this->trans_begin($test_mode);

	}



	// --------------------------------------------------------------------



	/**

	 * Complete Transaction

	 *

	 * @return	bool

	 */

	public function trans_complete()

	{

		if ( ! $this->trans_enabled)

		{

			return FALSE;

		}



		// The query() function will set this flag to FALSE in the event that a query failed

		if ($this->_trans_status === FALSE OR $this->_trans_failure === TRUE)

		{

			$this->trans_rollback();



			// If we are NOT running in strict mode, we will reset

			// the _trans_status flag so that subsequent groups of

			// transactions will be permitted.

			if ($this->trans_strict === FALSE)

			{

				$this->_trans_status = TRUE;

			}



			log_message('debug', 'DB Transaction Failure');

			return FALSE;

		}



		return $this->trans_commit();

	}



	// --------------------------------------------------------------------



	/**

	 * Lets you retrieve the transaction flag to determine if it has failed

	 *

	 * @return	bool

	 */

	public function trans_status()

	{

		return $this->_trans_status;

	}



	// --------------------------------------------------------------------



	/**

	 * Begin Transaction

	 *

	 * @param	bool	$test_mode

	 * @return	bool

	 */

	public function trans_begin($test_mode = FALSE)

	{

		if ( ! $this->trans_enabled)

		{

			return FALSE;

		}

		// When transactions are nested we only begin/commit/rollback the outermost ones

		elseif ($this->_trans_depth > 0)

		{

			$this->_trans_depth++;

			return TRUE;

		}



		// Reset the transaction failure flag.

		// If the $test_mode flag is set to TRUE transactions will be rolled back

		// even if the queries produce a successful result.

		$this->_trans_failure = ($test_mode === TRUE);



		if ($this->_trans_begin())

		{

			$this->_trans_depth++;

			return TRUE;

		}



		return FALSE;

	}



	// --------------------------------------------------------------------



	/**

	 * Commit Transaction

	 *

	 * @return	bool

	 */

	public function trans_commit()

	{

		if ( ! $this->trans_enabled OR $this->_trans_depth === 0)

		{

			return FALSE;

		}

		// When transactions are nested we only begin/commit/rollback the outermost ones

		elseif ($this->_trans_depth > 1 OR $this->_trans_commit())

		{

			$this->_trans_depth--;

			return TRUE;

		}



		return FALSE;

	}



	// --------------------------------------------------------------------



	/**

	 * Rollback Transaction

	 *

	 * @return	bool

	 */

	public function trans_rollback()

	{

		if ( ! $this->trans_enabled OR $this->_trans_depth === 0)

		{

			return FALSE;

		}

		// When transactions are nested we only begin/commit/rollback the outermost ones

		elseif ($this->_trans_depth > 1 OR $this->_trans_rollback())

		{

			$this->_trans_depth--;

			return TRUE;

		}



		return FALSE;

	}



	// --------------------------------------------------------------------



	/**

	 * Compile Bindings

	 *

	 * @param	string	the sql statement

	 * @param	array	an array of bind data

	 * @return	string

	 */

	public function compile_binds($sql, $binds)

	{

		if (empty($this->bind_marker) OR strpos($sql, $this->bind_marker) === FALSE)

		{

			return $sql;

		}

		elseif ( ! is_array($binds))

		{

			$binds = array($binds);

			$bind_count = 1;

		}

		else

		{

			// Make sure we're using numeric keys

			$binds = array_values($binds);

			$bind_count = count($binds);

		}



		// We'll need the marker length later

		$ml = strlen($this->bind_marker);



		// Make sure not to replace a chunk inside a string that happens to match the bind marker

		if ($c = preg_match_all("/'[^']*'|\"[^\"]*\"/i", $sql, $matches))

		{

			$c = preg_match_all('/'.preg_quote($this->bind_marker, '/').'/i',

				str_replace($matches[0],

					str_replace($this->bind_marker, str_repeat(' ', $ml), $matches[0]),

					$sql, $c),

				$matches, PREG_OFFSET_CAPTURE);



			// Bind values' count must match the count of markers in the query

			if ($bind_count !== $c)

			{

				return $sql;

			}

		}

		elseif (($c = preg_match_all('/'.preg_quote($this->bind_marker, '/').'/i', $sql, $matches, PREG_OFFSET_CAPTURE)) !== $bind_count)

		{

			return $sql;

		}



		do

		{

			$c--;

			$escaped_value = $this->escape($binds[$c]);

			if (is_array($escaped_value))

			{

				$escaped_value = '('.implode(',', $escaped_value).')';

			}

			$sql = substr_replace($sql, $escaped_value, $matches[0][$c][1], $ml);

		}

		while ($c !== 0);



		return $sql;

	}



	// --------------------------------------------------------------------



	/**

	 * Determines if a query is a "write" type.

	 *

	 * @param	string	An SQL query string

	 * @return	bool

	 */

	public function is_write_type($sql)

	{

		return (bool) preg_match('/^\s*"?(SET|INSERT|UPDATE|DELETE|REPLACE|CREATE|DROP|TRUNCATE|LOAD|COPY|ALTER|RENAME|GRANT|REVOKE|LOCK|UNLOCK|REINDEX)\s/i', $sql);

	}



	// --------------------------------------------------------------------



	/**

	 * Calculate the aggregate query elapsed time

	 *

	 * @param	int	The number of decimal places

	 * @return	string

	 */

	public function elapsed_time($decimals = 6)

	{

		return number_format($this->benchmark, $decimals);

	}



	// --------------------------------------------------------------------



	/**

	 * Returns the total number of queries

	 *

	 * @return	int

	 */

	public function total_queries()

	{

		return $this->query_count;

	}



	// --------------------------------------------------------------------



	/**

	 * Returns the last query that was executed

	 *

	 * @return	string

	 */

	public function last_query()

	{

		return end($this->queries);

	}



	// --------------------------------------------------------------------



	/**

	 * "Smart" Escape String

	 *

	 * Escapes data based on type

	 * Sets boolean and null types

	 *

	 * @param	string

	 * @return	mixed

	 */

	public function escape($str)

	{

		if (is_array($str))

		{

			$str = array_map(array(&$this, 'escape'), $str);

			return $str;

		}

		elseif (is_string($str) OR (is_object($str) && method_exists($str, '__toString')))

		{

			return "'".$this->escape_str($str)."'";

		}

		elseif (is_bool($str))

		{

			return ($str === FALSE) ? 0 : 1;

		}

		elseif ($str === NULL)

		{

			return 'NULL';

		}



		return $str;

	}



	// --------------------------------------------------------------------



	/**

	 * Escape String

	 *

	 * @param	string|string[]	$str	Input string

	 * @param	bool	$like	Whether or not the string will be used in a LIKE condition

	 * @return	string

	 */

	public function escape_str($str, $like = FALSE)

	{

		if (is_array($str))

		{

			foreach ($str as $key => $val)

			{

				$str[$key] = $this->escape_str($val, $like);

			}



			return $str;

		}



		$str = $this->_escape_str($str);



		// escape LIKE condition wildcards

		if ($like === TRUE)

		{

			return str_replace(

				array($this->_like_escape_chr, '%', '_'),

				array($this->_like_escape_chr.$this->_like_escape_chr, $this->_like_escape_chr.'%', $this->_like_escape_chr.'_'),

				$str

			);

		}



		return $str;

	}



	// --------------------------------------------------------------------



	/**

	 * Escape LIKE String

	 *

	 * Calls the individual driver for platform

	 * specific escaping for LIKE conditions

	 *

	 * @param	string|string[]

	 * @return	mixed

	 */

	public function escape_like_str($str)

	{

		return $this->escape_str($str, TRUE);

	}



	// --------------------------------------------------------------------



	/**

	 * Platform-dependant string escape

	 *

	 * @param	string

	 * @return	string

	 */

	protected function _escape_str($str)

	{

		return str_replace("'", "''", remove_invisible_characters($str));

	}



	// --------------------------------------------------------------------



	/**

	 * Primary

	 *

	 * Retrieves the primary key. It assumes that the row in the first

	 * position is the primary key

	 *

	 * @param	string	$table	Table name

	 * @return	string

	 */

	public function primary($table)

	{

		$fields = $this->list_fields($table);

		return is_array($fields) ? current($fields) : FALSE;

	}



	// --------------------------------------------------------------------



	/**

	 * "Count All" query

	 *

	 * Generates a platform-specific query string that counts all records in

	 * the specified database

	 *

	 * @param	string

	 * @return	int

	 */

	public function count_all($table = '')

	{

		if ($table === '')

		{

			return 0;

		}



		$query = $this->query($this->_count_string.$this->escape_identifiers('numrows').' FROM '.$this->protect_identifiers($table, TRUE, NULL, FALSE));

		if ($query->num_rows() === 0)

		{

			return 0;

		}



		$query = $query->row();

		$this->_reset_select();

		return (int) $query->numrows;

	}



	// --------------------------------------------------------------------



	/**

	 * Returns an array of table names

	 *

	 * @param	string	$constrain_by_prefix = FALSE

	 * @return	array

	 */

	public function list_tables($constrain_by_prefix = FALSE)

	{

		// Is there a cached result?

		if (isset($this->data_cache['table_names']))

		{

			return $this->data_cache['table_names'];

		}



		if (FALSE === ($sql = $this->_list_tables($constrain_by_prefix)))

		{

			return ($this->db_debug) ? $this->display_error('db_unsupported_function') : FALSE;

		}



		$this->data_cache['table_names'] = array();

		$query = $this->query($sql);



		foreach ($query->result_array() as $row)

		{

			// Do we know from which column to get the table name?

			if ( ! isset($key))

			{

				if (isset($row['table_name']))

				{

					$key = 'table_name';

				}

				elseif (isset($row['TABLE_NAME']))

				{

					$key = 'TABLE_NAME';

				}

				else

				{

					/* We have no other choice but to just get the first element's key.

					 * Due to array_shift() accepting its argument by reference, if

					 * E_STRICT is on, this would trigger a warning. So we'll have to

					 * assign it first.

					 */

					$key = array_keys($row);

					$key = array_shift($key);

				}

			}



			$this->data_cache['table_names'][] = $row[$key];

		}



		return $this->data_cache['table_names'];

	}



	// --------------------------------------------------------------------



	/**

	 * Determine if a particular table exists

	 *

	 * @param	string	$table_name

	 * @return	bool

	 */

	public function table_exists($table_name)

	{

		return in_array($this->protect_identifiers($table_name, TRUE, FALSE, FALSE), $this->list_tables());

	}



	// --------------------------------------------------------------------



	/**

	 * Fetch Field Names

	 *

	 * @param	string	$table	Table name

	 * @return	array

	 */

	public function list_fields($table)

	{

		// Is there a cached result?

		if (isset($this->data_cache['field_names'][$table]))

		{

			return $this->data_cache['field_names'][$table];

		}



		if (FALSE === ($sql = $this->_list_columns($table)))

		{

			return ($this->db_debug) ? $this->display_error('db_unsupported_function') : FALSE;

		}



		$query = $this->query($sql);

		$this->data_cache['field_names'][$table] = array();



		foreach ($query->result_array() as $row)

		{

			// Do we know from where to get the column's name?

			if ( ! isset($key))

			{

				if (isset($row['column_name']))

				{

					$key = 'column_name';

				}

				elseif (isset($row['COLUMN_NAME']))

				{

					$key = 'COLUMN_NAME';

				}

				else

				{

					// We have no other choice but to just get the first element's key.

					$key = key($row);

				}

			}



			$this->data_cache['field_names'][$table][] = $row[$key];

		}



		return $this->data_cache['field_names'][$table];

	}



	// --------------------------------------------------------------------



	/**

	 * Determine if a particular field exists

	 *

	 * @param	string

	 * @param	string

	 * @return	bool

	 */

	public function field_exists($field_name, $table_name)

	{

		return in_array($field_name, $this->list_fields($table_name));

	}



	// --------------------------------------------------------------------



	/**

	 * Returns an object with field data

	 *

	 * @param	string	$table	the table name

	 * @return	array

	 */

	public function field_data($table)

	{

		$query = $this->query($this->_field_data($this->protect_identifiers($table, TRUE, NULL, FALSE)));

		return ($query) ? $query->field_data() : FALSE;

	}



	// --------------------------------------------------------------------



	/**

	 * Escape the SQL Identifiers

	 *

	 * This function escapes column and table names

	 *

	 * @param	mixed

	 * @return	mixed

	 */

	public function escape_identifiers($item)

	{

		if ($this->_escape_char === '' OR empty($item) OR in_array($item, $this->_reserved_identifiers))

		{

			return $item;

		}

		elseif (is_array($item))

		{

			foreach ($item as $key => $value)

			{

				$item[$key] = $this->escape_identifiers($value);

			}



			return $item;

		}

		// Avoid breaking functions and literal values inside queries

		elseif (ctype_digit($item) OR $item[0] === "'" OR ($this->_escape_char !== '"' && $item[0] === '"') OR strpos($item, '(') !== FALSE)

		{

			return $item;

		}



		static $preg_ec = array();



		if (empty($preg_ec))

		{

			if (is_array($this->_escape_char))

			{

				$preg_ec = array(

					preg_quote($this->_escape_char[0], '/'),

					preg_quote($this->_escape_char[1], '/'),

					$this->_escape_char[0],

					$this->_escape_char[1]

				);

			}

			else

			{

				$preg_ec[0] = $preg_ec[1] = preg_quote($this->_escape_char, '/');

				$preg_ec[2] = $preg_ec[3] = $this->_escape_char;

			}

		}



		foreach ($this->_reserved_identifiers as $id)

		{

			if (strpos($item, '.'.$id) !== FALSE)

			{

				return preg_replace('/'.$preg_ec[0].'?([^'.$preg_ec[1].'\.]+)'.$preg_ec[1].'?\./i', $preg_ec[2].'$1'.$preg_ec[3].'.', $item);

			}

		}



		return preg_replace('/'.$preg_ec[0].'?([^'.$preg_ec[1].'\.]+)'.$preg_ec[1].'?(\.)?/i', $preg_ec[2].'$1'.$preg_ec[3].'$2', $item);

	}



	// --------------------------------------------------------------------



	/**

	 * Generate an insert string

	 *

	 * @param	string	the table upon which the query will be performed

	 * @param	array	an associative array data of key/values

	 * @return	string

	 */

	public function insert_string($table, $data)

	{

		$fields = $values = array();



		foreach ($data as $key => $val)

		{

			$fields[] = $this->escape_identifiers($key);

			$values[] = $this->escape($val);

		}



		return $this->_insert($this->protect_identifiers($table, TRUE, NULL, FALSE), $fields, $values);

	}



	// --------------------------------------------------------------------



	/**

	 * Insert statement

	 *

	 * Generates a platform-specific insert string from the supplied data

	 *

	 * @param	string	the table name

	 * @param	array	the insert keys

	 * @param	array	the insert values

	 * @return	string

	 */

	protected function _insert($table, $keys, $values)

	{

		return 'INSERT INTO '.$table.' ('.implode(', ', $keys).') VALUES ('.implode(', ', $values).')';

	}



	// --------------------------------------------------------------------



	/**

	 * Generate an update string

	 *

	 * @param	string	the table upon which the query will be performed

	 * @param	array	an associative array data of key/values

	 * @param	mixed	the "where" statement

	 * @return	string

	 */

	public function update_string($table, $data, $where)

	{

		if (empty($where))

		{

			return FALSE;

		}



		$this->where($where);



		$fields = array();

		foreach ($data as $key => $val)

		{

			$fields[$this->protect_identifiers($key)] = $this->escape($val);

		}



		$sql = $this->_update($this->protect_identifiers($table, TRUE, NULL, FALSE), $fields);

		$this->_reset_write();

		return $sql;

	}



	// --------------------------------------------------------------------



	/**

	 * Update statement

	 *

	 * Generates a platform-specific update string from the supplied data

	 *

	 * @param	string	the table name

	 * @param	array	the update data

	 * @return	string

	 */

	protected function _update($table, $values)

	{

		foreach ($values as $key => $val)

		{

			$valstr[] = $key.' = '.$val;

		}



		return 'UPDATE '.$table.' SET '.implode(', ', $valstr)

			.$this->_compile_wh('qb_where')

			.$this->_compile_order_by()

			.($this->qb_limit ? ' LIMIT '.$this->qb_limit : '');

	}



	// --------------------------------------------------------------------



	/**

	 * Tests whether the string has an SQL operator

	 *

	 * @param	string

	 * @return	bool

	 */

	protected function _has_operator($str)

	{

		return (bool) preg_match('/(<|>|!|=|\sIS NULL|\sIS NOT NULL|\sEXISTS|\sBETWEEN|\sLIKE|\sIN\s*\(|\s)/i', trim($str));

	}



	// --------------------------------------------------------------------



	/**

	 * Returns the SQL string operator

	 *

	 * @param	string

	 * @return	string

	 */

	protected function _get_operator($str)

	{

		static $_operators;



		if (empty($_operators))

		{

			$_les = ($this->_like_escape_str !== '')

				? '\s+'.preg_quote(trim(sprintf($this->_like_escape_str, $this->_like_escape_chr)), '/')

				: '';

			$_operators = array(

				'\s*(?:<|>|!)?=\s*',             // =, <=, >=, !=

				'\s*<>?\s*',                     // <, <>

				'\s*>\s*',                       // >

				'\s+IS NULL',                    // IS NULL

				'\s+IS NOT NULL',                // IS NOT NULL

				'\s+EXISTS\s*\(.*\)',        // EXISTS(sql)

				'\s+NOT EXISTS\s*\(.*\)',    // NOT EXISTS(sql)

				'\s+BETWEEN\s+',                 // BETWEEN value AND value

				'\s+IN\s*\(.*\)',            // IN(list)

				'\s+NOT IN\s*\(.*\)',        // NOT IN (list)

				'\s+LIKE\s+\S.*('.$_les.')?',    // LIKE 'expr'[ ESCAPE '%s']

				'\s+NOT LIKE\s+\S.*('.$_les.')?' // NOT LIKE 'expr'[ ESCAPE '%s']

			);



		}



		return preg_match('/'.implode('|', $_operators).'/i', $str, $match)

			? $match[0] : FALSE;

	}



	// --------------------------------------------------------------------



	/**

	 * Enables a native PHP function to be run, using a platform agnostic wrapper.

	 *

	 * @param	string	$function	Function name

	 * @return	mixed

	 */

	public function call_function($function)

	{

		$driver = ($this->dbdriver === 'postgre') ? 'pg_' : $this->dbdriver.'_';



		if (FALSE === strpos($driver, $function))

		{

			$function = $driver.$function;

		}



		if ( ! function_exists($function))

		{

			return ($this->db_debug) ? $this->display_error('db_unsupported_function') : FALSE;

		}



		return (func_num_args() > 1)

			? call_user_func_array($function, array_slice(func_get_args(), 1))

			: call_user_func($function);

	}



	// --------------------------------------------------------------------



	/**

	 * Set Cache Directory Path

	 *

	 * @param	string	the path to the cache directory

	 * @return	void

	 */

	public function cache_set_path($path = '')

	{

		$this->cachedir = $path;

	}



	// --------------------------------------------------------------------



	/**

	 * Enable Query Caching

	 *

	 * @return	bool	cache_on value

	 */

	public function cache_on()

	{

		return $this->cache_on = TRUE;

	}



	// --------------------------------------------------------------------



	/**

	 * Disable Query Caching

	 *

	 * @return	bool	cache_on value

	 */

	public function cache_off()

	{

		return $this->cache_on = FALSE;

	}



	// --------------------------------------------------------------------



	/**

	 * Delete the cache files associated with a particular URI

	 *

	 * @param	string	$segment_one = ''

	 * @param	string	$segment_two = ''

	 * @return	bool

	 */

	public function cache_delete($segment_one = '', $segment_two = '')

	{

		return $this->_cache_init()

			? $this->CACHE->delete($segment_one, $segment_two)

			: FALSE;

	}



	// --------------------------------------------------------------------



	/**

	 * Delete All cache files

	 *

	 * @return	bool

	 */

	public function cache_delete_all()

	{

		return $this->_cache_init()

			? $this->CACHE->delete_all()

			: FALSE;

	}



	// --------------------------------------------------------------------



	/**

	 * Initialize the Cache Class

	 *

	 * @return	bool

	 */

	protected function _cache_init()

	{

		if ( ! class_exists('CI_DB_Cache', FALSE))

		{

			require_once(BASEPATH.'database/DB_cache.php');

		}

		elseif (is_object($this->CACHE))

		{

			return TRUE;

		}



		$this->CACHE = new CI_DB_Cache($this); // pass db object to support multiple db connections and returned db objects

		return TRUE;

	}



	// --------------------------------------------------------------------



	/**

	 * Close DB Connection

	 *

	 * @return	void

	 */

	public function close()

	{

		if ($this->conn_id)

		{

			$this->_close();

			$this->conn_id = FALSE;

		}

	}



	// --------------------------------------------------------------------



	/**

	 * Close DB Connection

	 *

	 * This method would be overridden by most of the drivers.

	 *

	 * @return	void

	 */

	protected function _close()

	{

		$this->conn_id = FALSE;

	}



	// --------------------------------------------------------------------



	/**

	 * Display an error message

	 *

	 * @param	string	the error message

	 * @param	string	any "swap" values

	 * @param	bool	whether to localize the message

	 * @return	string	sends the application/views/errors/error_db.php template

	 */

	public function display_error($error = '', $swap = '', $native = FALSE)

	{

		$LANG =& load_class('Lang', 'core');

		$LANG->load('db');



		$heading = $LANG->line('db_error_heading');



		if ($native === TRUE)

		{

			$message = (array) $error;

		}

		else

		{

			$message = is_array($error) ? $error : array(str_replace('%s', $swap, $LANG->line($error)));

		}



		// Find the most likely culprit of the error by going through

		// the backtrace until the source file is no longer in the

		// database folder.

		$trace = debug_backtrace();

		foreach ($trace as $call)

		{

			if (isset($call['file'], $call['class']))

			{

				// We'll need this on Windows, as APPPATH and BASEPATH will always use forward slashes

				if (DIRECTORY_SEPARATOR !== '/')

				{

					$call['file'] = str_replace('\\', '/', $call['file']);

				}



				if (strpos($call['file'], BASEPATH.'database') === FALSE && strpos($call['class'], 'Loader') === FALSE)

				{

					// Found it - use a relative path for safety

					$message[] = 'Filename: '.str_replace(array(APPPATH, BASEPATH), '', $call['file']);

					$message[] = 'Line Number: '.$call['line'];

					break;

				}

			}

		}



		$error =& load_class('Exceptions', 'core');

		echo $error->show_error($heading, $message, 'error_db');

		exit(8); // EXIT_DATABASE

	}



	// --------------------------------------------------------------------



	/**

	 * Protect Identifiers

	 *

	 * This function is used extensively by the Query Builder class, and by

	 * a couple functions in this class.

	 * It takes a column or table name (optionally with an alias) and inserts

	 * the table prefix onto it. Some logic is necessary in order to deal with

	 * column names that include the path. Consider a query like this:

	 *

	 * SELECT hostname.database.table.column AS c FROM hostname.database.table

	 *

	 * Or a query with aliasing:

	 *

	 * SELECT m.member_id, m.member_name FROM members AS m

	 *

	 * Since the column name can include up to four segments (host, DB, table, column)

	 * or also have an alias prefix, we need to do a bit of work to figure this out and

	 * insert the table prefix (if it exists) in the proper position, and escape only

	 * the correct identifiers.

	 *

	 * @param	string

	 * @param	bool

	 * @param	mixed

	 * @param	bool

	 * @return	string

	 */

	public function protect_identifiers($item, $prefix_single = FALSE, $protect_identifiers = NULL, $field_exists = TRUE)

	{

		if ( ! is_bool($protect_identifiers))

		{

			$protect_identifiers = $this->_protect_identifiers;

		}



		if (is_array($item))

		{

			$escaped_array = array();

			foreach ($item as $k => $v)

			{

				$escaped_array[$this->protect_identifiers($k)] = $this->protect_identifiers($v, $prefix_single, $protect_identifiers, $field_exists);

			}



			return $escaped_array;

		}



		// This is basically a bug fix for queries that use MAX, MIN, etc.

		// If a parenthesis is found we know that we do not need to

		// escape the data or add a prefix. There's probably a more graceful

		// way to deal with this, but I'm not thinking of it -- Rick

		//

		// Added exception for single quotes as well, we don't want to alter

		// literal strings. -- Narf

		if (strcspn($item, "()'") !== strlen($item))

		{

			return $item;

		}



		// Convert tabs or multiple spaces into single spaces

		$item = preg_replace('/\s+/', ' ', trim($item));



		// If the item has an alias declaration we remove it and set it aside.

		// Note: strripos() is used in order to support spaces in table names

		if ($offset = strripos($item, ' AS '))

		{

			$alias = ($protect_identifiers)

				? substr($item, $offset, 4).$this->escape_identifiers(substr($item, $offset + 4))

				: substr($item, $offset);

			$item = substr($item, 0, $offset);

		}

		elseif ($offset = strrpos($item, ' '))

		{

			$alias = ($protect_identifiers)

				? ' '.$this->escape_identifiers(substr($item, $offset + 1))

				: substr($item, $offset);

			$item = substr($item, 0, $offset);

		}

		else

		{

			$alias = '';

		}



		// Break the string apart if it contains periods, then insert the table prefix

		// in the correct location, assuming the period doesn't indicate that we're dealing

		// with an alias. While we're at it, we will escape the components

		if (strpos($item, '.') !== FALSE)

		{

			$parts = explode('.', $item);



			// Does the first segment of the exploded item match

			// one of the aliases previously identified? If so,

			// we have nothing more to do other than escape the item

			//

			// NOTE: The ! empty() condition prevents this method

			//       from breaking when QB isn't enabled.

			if ( ! empty($this->qb_aliased_tables) && in_array($parts[0], $this->qb_aliased_tables))

			{

				if ($protect_identifiers === TRUE)

				{

					foreach ($parts as $key => $val)

					{

						if ( ! in_array($val, $this->_reserved_identifiers))

						{

							$parts[$key] = $this->escape_identifiers($val);

						}

					}



					$item = implode('.', $parts);

				}



				return $item.$alias;

			}



			// Is there a table prefix defined in the config file? If not, no need to do anything

			if ($this->dbprefix !== '')

			{

				// We now add the table prefix based on some logic.

				// Do we have 4 segments (hostname.database.table.column)?

				// If so, we add the table prefix to the column name in the 3rd segment.

				if (isset($parts[3]))

				{

					$i = 2;

				}

				// Do we have 3 segments (database.table.column)?

				// If so, we add the table prefix to the column name in 2nd position

				elseif (isset($parts[2]))

				{

					$i = 1;

				}

				// Do we have 2 segments (table.column)?

				// If so, we add the table prefix to the column name in 1st segment

				else

				{

					$i = 0;

				}



				// This flag is set when the supplied $item does not contain a field name.

				// This can happen when this function is being called from a JOIN.

				if ($field_exists === FALSE)

				{

					$i++;

				}



				// Verify table prefix and replace if necessary

				if ($this->swap_pre !== '' && strpos($parts[$i], $this->swap_pre) === 0)

				{

					$parts[$i] = preg_replace('/^'.$this->swap_pre.'(\S+?)/', $this->dbprefix.'\\1', $parts[$i]);

				}

				// We only add the table prefix if it does not already exist

				elseif (strpos($parts[$i], $this->dbprefix) !== 0)

				{

					$parts[$i] = $this->dbprefix.$parts[$i];

				}



				// Put the parts back together

				$item = implode('.', $parts);

			}



			if ($protect_identifiers === TRUE)

			{

				$item = $this->escape_identifiers($item);

			}



			return $item.$alias;

		}



		// Is there a table prefix? If not, no need to insert it

		if ($this->dbprefix !== '')

		{

			// Verify table prefix and replace if necessary

			if ($this->swap_pre !== '' && strpos($item, $this->swap_pre) === 0)

			{

				$item = preg_replace('/^'.$this->swap_pre.'(\S+?)/', $this->dbprefix.'\\1', $item);

			}

			// Do we prefix an item with no segments?

			elseif ($prefix_single === TRUE && strpos($item, $this->dbprefix) !== 0)

			{

				$item = $this->dbprefix.$item;

			}

		}



		if ($protect_identifiers === TRUE && ! in_array($item, $this->_reserved_identifiers))

		{

			$item = $this->escape_identifiers($item);

		}



		return $item.$alias;

	}



	// --------------------------------------------------------------------



	/**

	 * Dummy method that allows Query Builder class to be disabled

	 * and keep count_all() working.

	 *

	 * @return	void

	 */

	protected function _reset_select()

	{

	}



}

