<?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".
*/