database.inc

<?php


/**
 * @file
 * Database interface code for SQLite embedded database engine.
 */

/**
 * @addtogroup database
 * @{
 */
include_once DRUPAL_ROOT . '/includes/database/prefetch.inc';

/**
 * Specific SQLite implementation of DatabaseConnection.
 */
class DatabaseConnection_sqlite extends DatabaseConnection {
    
    /**
     * Whether this database connection supports savepoints.
     *
     * Version of sqlite lower then 3.6.8 can't use savepoints.
     * See http://www.sqlite.org/releaselog/3_6_8.html
     *
     * @var boolean
     */
    protected $savepointSupport = FALSE;
    
    /**
     * Whether or not the active transaction (if any) will be rolled back.
     *
     * @var boolean
     */
    protected $willRollback;
    
    /**
     * All databases attached to the current database. This is used to allow
     * prefixes to be safely handled without locking the table
     *
     * @var array
     */
    protected $attachedDatabases = array();
    
    /**
     * Whether or not a table has been dropped this request: the destructor will
     * only try to get rid of unnecessary databases if there is potential of them
     * being empty.
     *
     * This variable is set to public because DatabaseSchema_sqlite needs to
     * access it. However, it should not be manually set.
     *
     * @var boolean
     */
    var $tableDropped = FALSE;
    public function __construct(array $connection_options = array()) {
        // We don't need a specific PDOStatement class here, we simulate it below.
        $this->statementClass = NULL;
        // This driver defaults to transaction support, except if explicitly passed FALSE.
        $this->transactionSupport = $this->transactionalDDLSupport = !isset($connection_options['transactions']) || $connection_options['transactions'] !== FALSE;
        $this->connectionOptions = $connection_options;
        // Allow PDO options to be overridden.
        $connection_options += array(
            'pdo' => array(),
        );
        $connection_options['pdo'] += array(
            // Convert numeric values to strings when fetching.
PDO::ATTR_STRINGIFY_FETCHES => TRUE,
        );
        parent::__construct('sqlite:' . $connection_options['database'], '', '', $connection_options['pdo']);
        // Attach one database for each registered prefix.
        $prefixes = $this->prefixes;
        foreach ($prefixes as $table => &$prefix) {
            // Empty prefix means query the main database -- no need to attach anything.
            if (!empty($prefix)) {
                // Only attach the database once.
                if (!isset($this->attachedDatabases[$prefix])) {
                    $this->attachedDatabases[$prefix] = $prefix;
                    $this->query('ATTACH DATABASE :database AS :prefix', array(
                        ':database' => $connection_options['database'] . '-' . $prefix,
                        ':prefix' => $prefix,
                    ));
                }
                // Add a ., so queries become prefix.table, which is proper syntax for
                // querying an attached database.
                $prefix .= '.';
            }
        }
        // Regenerate the prefixes replacement table.
        $this->setPrefix($prefixes);
        // Detect support for SAVEPOINT.
        $version = $this->query('SELECT sqlite_version()')
            ->fetchField();
        $this->savepointSupport = version_compare($version, '3.6.8') >= 0;
        // Create functions needed by SQLite.
        $this->sqliteCreateFunction('if', array(
            $this,
            'sqlFunctionIf',
        ));
        $this->sqliteCreateFunction('greatest', array(
            $this,
            'sqlFunctionGreatest',
        ));
        $this->sqliteCreateFunction('pow', 'pow', 2);
        $this->sqliteCreateFunction('length', 'strlen', 1);
        $this->sqliteCreateFunction('md5', 'md5', 1);
        $this->sqliteCreateFunction('concat', array(
            $this,
            'sqlFunctionConcat',
        ));
        $this->sqliteCreateFunction('substring', array(
            $this,
            'sqlFunctionSubstring',
        ), 3);
        $this->sqliteCreateFunction('substring_index', array(
            $this,
            'sqlFunctionSubstringIndex',
        ), 3);
        $this->sqliteCreateFunction('rand', array(
            $this,
            'sqlFunctionRand',
        ));
        // Enable the Write-Ahead Logging (WAL) option for SQLite if supported.
        // @see https://www.drupal.org/node/2348137
        // @see https://sqlite.org/wal.html
        if (version_compare($version, '3.7') >= 0) {
            $connection_options += array(
                'init_commands' => array(),
            );
            $connection_options['init_commands'] += array(
                'wal' => "PRAGMA journal_mode=WAL",
            );
        }
        // Execute sqlite init_commands.
        if (isset($connection_options['init_commands'])) {
            $this->connection
                ->exec(implode('; ', $connection_options['init_commands']));
        }
    }
    
    /**
     * Destructor for the SQLite connection.
     *
     * We prune empty databases on destruct, but only if tables have been
     * dropped. This is especially needed when running the test suite, which
     * creates and destroy databases several times in a row.
     */
    public function __destruct() {
        if ($this->tableDropped && !empty($this->attachedDatabases)) {
            foreach ($this->attachedDatabases as $prefix) {
                // Check if the database is now empty, ignore the internal SQLite tables.
                try {
                    $count = $this->query('SELECT COUNT(*) FROM ' . $prefix . '.sqlite_master WHERE type = :type AND name NOT LIKE :pattern', array(
                        ':type' => 'table',
                        ':pattern' => 'sqlite_%',
                    ))
                        ->fetchField();
                    // We can prune the database file if it doesn't have any tables.
                    if ($count == 0 && $this->connectionOptions['database'] != ':memory:') {
                        // Detaching the database fails at this point, but no other queries
                        // are executed after the connection is destructed so we can simply
                        // remove the database file.
                        unlink($this->connectionOptions['database'] . '-' . $prefix);
                    }
                } catch (Exception $e) {
                    // Ignore the exception and continue. There is nothing we can do here
                    // to report the error or fail safe.
                }
            }
        }
    }
    
    /**
     * Gets all the attached databases.
     *
     * @return array
     *   An array of attached database names.
     *
     * @see DatabaseConnection_sqlite::__construct().
     */
    public function getAttachedDatabases() {
        return $this->attachedDatabases;
    }
    
    /**
     * SQLite compatibility implementation for the IF() SQL function.
     */
    public function sqlFunctionIf($condition, $expr1, $expr2 = NULL) {
        return $condition ? $expr1 : $expr2;
    }
    
    /**
     * SQLite compatibility implementation for the GREATEST() SQL function.
     */
    public function sqlFunctionGreatest() {
        $args = func_get_args();
        foreach ($args as $k => $v) {
            if (!isset($v)) {
                unset($args);
            }
        }
        if (count($args)) {
            return max($args);
        }
        else {
            return NULL;
        }
    }
    
    /**
     * SQLite compatibility implementation for the CONCAT() SQL function.
     */
    public function sqlFunctionConcat() {
        $args = func_get_args();
        return implode('', $args);
    }
    
    /**
     * SQLite compatibility implementation for the SUBSTRING() SQL function.
     */
    public function sqlFunctionSubstring($string, $from, $length) {
        return substr($string, $from - 1, $length);
    }
    
    /**
     * SQLite compatibility implementation for the SUBSTRING_INDEX() SQL function.
     */
    public function sqlFunctionSubstringIndex($string, $delimiter, $count) {
        // If string is empty, simply return an empty string.
        if (empty($string)) {
            return '';
        }
        $end = 0;
        for ($i = 0; $i < $count; $i++) {
            $end = strpos($string, $delimiter, $end + 1);
            if ($end === FALSE) {
                $end = strlen($string);
            }
        }
        return substr($string, 0, $end);
    }
    
    /**
     * SQLite compatibility implementation for the RAND() SQL function.
     */
    public function sqlFunctionRand($seed = NULL) {
        if (isset($seed)) {
            mt_srand($seed);
        }
        return mt_rand() / mt_getrandmax();
    }
    
    /**
     * SQLite-specific implementation of DatabaseConnection::prepare().
     *
     * We don't use prepared statements at all at this stage. We just create
     * a DatabaseStatement_sqlite object, that will create a PDOStatement
     * using the semi-private PDOPrepare() method below.
     */
    public function prepare($query, $options = array()) {
        return new DatabaseStatement_sqlite($this, $query, $options);
    }
    
    /**
     * NEVER CALL THIS FUNCTION: YOU MIGHT DEADLOCK YOUR PHP PROCESS.
     *
     * This is a wrapper around the parent PDO::prepare method. However, as
     * the PDO SQLite driver only closes SELECT statements when the PDOStatement
     * destructor is called and SQLite does not allow data change (INSERT,
     * UPDATE etc) on a table which has open SELECT statements, you should never
     * call this function and keep a PDOStatement object alive as that can lead
     * to a deadlock. This really, really should be private, but as
     * DatabaseStatement_sqlite needs to call it, we have no other choice but to
     * expose this function to the world.
     */
    public function PDOPrepare($query, array $options = array()) {
        return $this->connection
            ->prepare($query, $options);
    }
    public function queryRange($query, $from, $count, array $args = array(), array $options = array()) {
        return $this->query($query . ' LIMIT ' . (int) $from . ', ' . (int) $count, $args, $options);
    }
    public function queryTemporary($query, array $args = array(), array $options = array()) {
        // Generate a new temporary table name and protect it from prefixing.
        // SQLite requires that temporary tables to be non-qualified.
        $tablename = $this->generateTemporaryTableName();
        $prefixes = $this->prefixes;
        $prefixes[$tablename] = '';
        $this->setPrefix($prefixes);
        $this->query('CREATE TEMPORARY TABLE ' . $tablename . ' AS ' . $query, $args, $options);
        return $tablename;
    }
    public function driver() {
        return 'sqlite';
    }
    public function databaseType() {
        return 'sqlite';
    }
    public function mapConditionOperator($operator) {
        // We don't want to override any of the defaults.
        static $specials = array(
            'LIKE' => array(
                'postfix' => " ESCAPE '\\'",
            ),
            'NOT LIKE' => array(
                'postfix' => " ESCAPE '\\'",
            ),
        );
        return isset($specials[$operator]) ? $specials[$operator] : NULL;
    }
    public function prepareQuery($query) {
        return $this->prepare($this->prefixTables($query));
    }
    public function nextId($existing_id = 0) {
        $transaction = $this->startTransaction();
        // We can safely use literal queries here instead of the slower query
        // builder because if a given database breaks here then it can simply
        // override nextId. However, this is unlikely as we deal with short strings
        // and integers and no known databases require special handling for those
        // simple cases. If another transaction wants to write the same row, it will
        // wait until this transaction commits.
        $stmt = $this->query('UPDATE {sequences} SET value = GREATEST(value, :existing_id) + 1', array(
            ':existing_id' => $existing_id,
        ));
        if (!$stmt->rowCount()) {
            $this->query('INSERT INTO {sequences} (value) VALUES (:existing_id + 1)', array(
                ':existing_id' => $existing_id,
            ));
        }
        // The transaction gets committed when the transaction object gets destroyed
        // because it gets out of scope.
        return $this->query('SELECT value FROM {sequences}')
            ->fetchField();
    }
    public function rollback($savepoint_name = 'drupal_transaction') {
        if ($this->savepointSupport) {
            return parent::rollBack($savepoint_name);
        }
        if (!$this->inTransaction()) {
            throw new DatabaseTransactionNoActiveException();
        }
        // A previous rollback to an earlier savepoint may mean that the savepoint
        // in question has already been rolled back.
        if (!in_array($savepoint_name, $this->transactionLayers)) {
            return;
        }
        // We need to find the point we're rolling back to, all other savepoints
        // before are no longer needed.
        while ($savepoint = array_pop($this->transactionLayers)) {
            if ($savepoint == $savepoint_name) {
                // Mark whole stack of transactions as needed roll back.
                $this->willRollback = TRUE;
                // If it is the last the transaction in the stack, then it is not a
                // savepoint, it is the transaction itself so we will need to roll back
                // the transaction rather than a savepoint.
                if (empty($this->transactionLayers)) {
                    break;
                }
                return;
            }
        }
        if ($this->supportsTransactions()) {
            $this->connection
                ->rollBack();
        }
    }
    public function pushTransaction($name) {
        if ($this->savepointSupport) {
            return parent::pushTransaction($name);
        }
        if (!$this->supportsTransactions()) {
            return;
        }
        if (isset($this->transactionLayers[$name])) {
            throw new DatabaseTransactionNameNonUniqueException($name . " is already in use.");
        }
        if (!$this->inTransaction()) {
            $this->connection
                ->beginTransaction();
        }
        $this->transactionLayers[$name] = $name;
    }
    public function popTransaction($name) {
        if ($this->savepointSupport) {
            return parent::popTransaction($name);
        }
        if (!$this->supportsTransactions()) {
            return;
        }
        if (!$this->inTransaction()) {
            throw new DatabaseTransactionNoActiveException();
        }
        // Commit everything since SAVEPOINT $name.
        while ($savepoint = array_pop($this->transactionLayers)) {
            if ($savepoint != $name) {
                continue;
            }
            // If there are no more layers left then we should commit or rollback.
            if (empty($this->transactionLayers)) {
                // If there was any rollback() we should roll back whole transaction.
                if ($this->willRollback) {
                    $this->willRollback = FALSE;
                    $this->connection
                        ->rollBack();
                }
                elseif (!$this->connection
                    ->commit()) {
                    throw new DatabaseTransactionCommitFailedException();
                }
            }
            else {
                break;
            }
        }
    }
    public function utf8mb4IsActive() {
        return TRUE;
    }
    public function utf8mb4IsSupported() {
        return TRUE;
    }

}

/**
 * Specific SQLite implementation of DatabaseConnection.
 *
 * See DatabaseConnection_sqlite::PDOPrepare() for reasons why we must prefetch
 * the data instead of using PDOStatement.
 *
 * @see DatabaseConnection_sqlite::PDOPrepare()
 */
class DatabaseStatement_sqlite extends DatabaseStatementPrefetch implements Iterator, DatabaseStatementInterface {
    
    /**
     * SQLite specific implementation of getStatement().
     *
     * The PDO SQLite layer doesn't replace numeric placeholders in queries
     * correctly, and this makes numeric expressions (such as COUNT(*) >= :count)
     * fail. We replace numeric placeholders in the query ourselves to work
     * around this bug.
     *
     * See http://bugs.php.net/bug.php?id=45259 for more details.
     */
    protected function getStatement($query, &$args = array()) {
        if (count($args)) {
            // Check if $args is a simple numeric array.
            if (range(0, count($args) - 1) === array_keys($args)) {
                // In that case, we have unnamed placeholders.
                $count = 0;
                $new_args = array();
                foreach ($args as $value) {
                    if (is_float($value) || is_int($value)) {
                        if (is_float($value)) {
                            // Force the conversion to float so as not to loose precision
                            // in the automatic cast.
                            $value = sprintf('%F', $value);
                        }
                        $query = substr_replace($query, $value, strpos($query, '?'), 1);
                    }
                    else {
                        $placeholder = ':db_statement_placeholder_' . $count++;
                        $query = substr_replace($query, $placeholder, strpos($query, '?'), 1);
                        $new_args[$placeholder] = $value;
                    }
                }
                $args = $new_args;
            }
            else {
                // Else, this is using named placeholders.
                foreach ($args as $placeholder => $value) {
                    if (is_float($value) || is_int($value)) {
                        if (is_float($value)) {
                            // Force the conversion to float so as not to loose precision
                            // in the automatic cast.
                            $value = sprintf('%F', $value);
                        }
                        // We will remove this placeholder from the query as PDO throws an
                        // exception if the number of placeholders in the query and the
                        // arguments does not match.
                        unset($args[$placeholder]);
                        // PDO allows placeholders to not be prefixed by a colon. See
                        // http://marc.info/?l=php-internals&m=111234321827149&w=2 for
                        // more.
                        if ($placeholder[0] != ':') {
                            $placeholder = ":{$placeholder}";
                        }
                        // When replacing the placeholders, make sure we search for the
                        // exact placeholder. For example, if searching for
                        // ':db_placeholder_1', do not replace ':db_placeholder_11'.
                        $query = preg_replace('/' . preg_quote($placeholder) . '\\b/', $value, $query);
                    }
                }
            }
        }
        return $this->dbh
            ->PDOPrepare($query);
    }
    public function execute($args = array(), $options = array()) {
        try {
            $return = parent::execute($args, $options);
        } catch (PDOException $e) {
            if (!empty($e->errorInfo[1]) && $e->errorInfo[1] === 17) {
                // The schema has changed. SQLite specifies that we must resend the query.
                $return = parent::execute($args, $options);
            }
            else {
                // Rethrow the exception.
                throw $e;
            }
        }
        // In some weird cases, SQLite will prefix some column names by the name
        // of the table. We post-process the data, by renaming the column names
        // using the same convention as MySQL and PostgreSQL.
        $rename_columns = array();
        foreach ($this->columnNames as $k => $column) {
            // In some SQLite versions, SELECT DISTINCT(field) will return "(field)"
            // instead of "field".
            if (preg_match("/^\\((.*)\\)\$/", $column, $matches)) {
                $rename_columns[$column] = $matches[1];
                $this->columnNames[$k] = $matches[1];
                $column = $matches[1];
            }
            // Remove "table." prefixes.
            if (preg_match("/^.*\\.(.*)\$/", $column, $matches)) {
                $rename_columns[$column] = $matches[1];
                $this->columnNames[$k] = $matches[1];
            }
        }
        if ($rename_columns) {
            // DatabaseStatementPrefetch already extracted the first row,
            // put it back into the result set.
            if (isset($this->currentRow)) {
                $this->data[0] =& $this->currentRow;
            }
            // Then rename all the columns across the result set.
            foreach ($this->data as $k => $row) {
                foreach ($rename_columns as $old_column => $new_column) {
                    $this->data[$k][$new_column] = $this->data[$k][$old_column];
                    unset($this->data[$k][$old_column]);
                }
            }
            // Finally, extract the first row again.
            $this->currentRow = $this->data[0];
            unset($this->data[0]);
        }
        return $return;
    }

}

/**
 * @} End of "addtogroup database".
 */