DatabaseOracle.php

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<?php
use Wikimedia\Rdbms\Database;
use Wikimedia\Rdbms\Blob;
use Wikimedia\Rdbms\ResultWrapper;
use Wikimedia\Rdbms\DBConnectionError;
use Wikimedia\Rdbms\DBUnexpectedError;
 
class DatabaseOracle extends Database {
    protected $mLastResult = null;
 
    protected $mAffectedRows;
 
    private $ignoreDupValOnIndex = false;
 
    private $sequenceData = null;
 
    private $defaultCharset = 'AL32UTF8';
 
    private $mFieldInfoCache = [];
 
    function __construct( array $p ) {
        global $wgDBprefix;
 
        if ( $p['tablePrefix'] == 'get from global' ) {
            $p['tablePrefix'] = $wgDBprefix;
        }
        $p['tablePrefix'] = strtoupper( $p['tablePrefix'] );
        parent::__construct( $p );
        Hooks::run( 'DatabaseOraclePostInit', [ $this ] );
    }
 
    function __destruct() {
        if ( $this->opened ) {
            Wikimedia\suppressWarnings();
            $this->close();
            Wikimedia\restoreWarnings();
        }
    }
 
    function getType() {
        return 'oracle';
    }
 
    function implicitGroupby() {
        return false;
    }
 
    function implicitOrderby() {
        return false;
    }
 
    function open( $server, $user, $password, $dbName ) {
        global $wgDBOracleDRCP;
        if ( !function_exists( 'oci_connect' ) ) {
            throw new DBConnectionError(
                $this,
                "Oracle functions missing, have you compiled PHP with the --with-oci8 option?\n " .
                    "(Note: if you recently installed PHP, you may need to restart your webserver\n " .
                    "and database)\n" );
        }
 
        $this->close();
        $this->user = $user;
        $this->password = $password;
        // changed internal variables functions
        // mServer now holds the TNS endpoint
        // mDBname is schema name if different from username
        if ( !$server ) {
            // backward compatibillity (server used to be null and TNS was supplied in dbname)
            $this->server = $dbName;
            $this->dbName = $user;
        } else {
            $this->server = $server;
            if ( !$dbName ) {
                $this->dbName = $user;
            } else {
                $this->dbName = $dbName;
            }
        }
 
        if ( !strlen( $user ) ) { # e.g. the class is being loaded
            return null;
        }
 
        if ( $wgDBOracleDRCP ) {
            $this->setFlag( DBO_PERSISTENT );
        }
 
        $session_mode = $this->flags & DBO_SYSDBA ? OCI_SYSDBA : OCI_DEFAULT;
 
        Wikimedia\suppressWarnings();
        if ( $this->flags & DBO_PERSISTENT ) {
            $this->conn = oci_pconnect(
                $this->user,
                $this->password,
                $this->server,
                $this->defaultCharset,
                $session_mode
            );
        } elseif ( $this->flags & DBO_DEFAULT ) {
            $this->conn = oci_new_connect(
                $this->user,
                $this->password,
                $this->server,
                $this->defaultCharset,
                $session_mode
            );
        } else {
            $this->conn = oci_connect(
                $this->user,
                $this->password,
                $this->server,
                $this->defaultCharset,
                $session_mode
            );
        }
        Wikimedia\restoreWarnings();
 
        if ( $this->user != $this->dbName ) {
            // change current schema in session
            $this->selectDB( $this->dbName );
        }
 
        if ( !$this->conn ) {
            throw new DBConnectionError( $this, $this->lastError() );
        }
 
        $this->opened = true;
 
        # removed putenv calls because they interfere with the system globaly
        $this->doQuery( 'ALTER SESSION SET NLS_TIMESTAMP_FORMAT=\'DD-MM-YYYY HH24:MI:SS.FF6\'' );
        $this->doQuery( 'ALTER SESSION SET NLS_TIMESTAMP_TZ_FORMAT=\'DD-MM-YYYY HH24:MI:SS.FF6\'' );
        $this->doQuery( 'ALTER SESSION SET NLS_NUMERIC_CHARACTERS=\'.,\'' );
 
        return $this->conn;
    }
 
    protected function closeConnection() {
        return oci_close( $this->conn );
    }
 
    function execFlags() {
        return $this->trxLevel ? OCI_NO_AUTO_COMMIT : OCI_COMMIT_ON_SUCCESS;
    }
 
    protected function doQuery( $sql ) {
        wfDebug( "SQL: [$sql]\n" );
        if ( !StringUtils::isUtf8( $sql ) ) {
            throw new InvalidArgumentException( "SQL encoding is invalid\n$sql" );
        }
 
        // handle some oracle specifics
        // remove AS column/table/subquery namings
        if ( !$this->getFlag( DBO_DDLMODE ) ) {
            $sql = preg_replace( '/ as /i', ' ', $sql );
        }
 
        // Oracle has issues with UNION clause if the statement includes LOB fields
        // So we do a UNION ALL and then filter the results array with array_unique
        $union_unique = ( preg_match( '/\/\* UNION_UNIQUE \*\/ /', $sql ) != 0 );
        // EXPLAIN syntax in Oracle is EXPLAIN PLAN FOR and it return nothing
        // you have to select data from plan table after explain
        $explain_id = MWTimestamp::getLocalInstance()->format( 'dmYHis' );
 
        $sql = preg_replace(
            '/^EXPLAIN /',
            'EXPLAIN PLAN SET STATEMENT_ID = \'' . $explain_id . '\' FOR',
            $sql,
            1,
            $explain_count
        );
 
        Wikimedia\suppressWarnings();
 
        $this->mLastResult = $stmt = oci_parse( $this->conn, $sql );
        if ( $stmt === false ) {
            $e = oci_error( $this->conn );
            $this->reportQueryError( $e['message'], $e['code'], $sql, __METHOD__ );
 
            return false;
        }
 
        if ( !oci_execute( $stmt, $this->execFlags() ) ) {
            $e = oci_error( $stmt );
            if ( !$this->ignoreDupValOnIndex || $e['code'] != '1' ) {
                $this->reportQueryError( $e['message'], $e['code'], $sql, __METHOD__ );
 
                return false;
            }
        }
 
        Wikimedia\restoreWarnings();
 
        if ( $explain_count > 0 ) {
            return $this->doQuery( 'SELECT id, cardinality "ROWS" FROM plan_table ' .
                'WHERE statement_id = \'' . $explain_id . '\'' );
        } elseif ( oci_statement_type( $stmt ) == 'SELECT' ) {
            return new ORAResult( $this, $stmt, $union_unique );
        } else {
            $this->mAffectedRows = oci_num_rows( $stmt );
 
            return true;
        }
    }
 
    function queryIgnore( $sql, $fname = '' ) {
        return $this->query( $sql, $fname, true );
    }
 
    function freeResult( $res ) {
        if ( $res instanceof ResultWrapper ) {
            $res = $res->result;
        }
 
        $res->free();
    }
 
    function fetchObject( $res ) {
        if ( $res instanceof ResultWrapper ) {
            $res = $res->result;
        }
 
        return $res->fetchObject();
    }
 
    function fetchRow( $res ) {
        if ( $res instanceof ResultWrapper ) {
            $res = $res->result;
        }
 
        return $res->fetchRow();
    }
 
    function numRows( $res ) {
        if ( $res instanceof ResultWrapper ) {
            $res = $res->result;
        }
 
        return $res->numRows();
    }
 
    function numFields( $res ) {
        if ( $res instanceof ResultWrapper ) {
            $res = $res->result;
        }
 
        return $res->numFields();
    }
 
    function fieldName( $stmt, $n ) {
        return oci_field_name( $stmt, $n );
    }
 
    function insertId() {
        $res = $this->query( "SELECT lastval_pkg.getLastval FROM dual" );
        $row = $this->fetchRow( $res );
        return is_null( $row[0] ) ? null : (int)$row[0];
    }
 
    function dataSeek( $res, $row ) {
        if ( $res instanceof ORAResult ) {
            $res->seek( $row );
        } else {
            $res->result->seek( $row );
        }
    }
 
    function lastError() {
        if ( $this->conn === false ) {
            $e = oci_error();
        } else {
            $e = oci_error( $this->conn );
        }
 
        return $e['message'];
    }
 
    function lastErrno() {
        if ( $this->conn === false ) {
            $e = oci_error();
        } else {
            $e = oci_error( $this->conn );
        }
 
        return $e['code'];
    }
 
    protected function fetchAffectedRowCount() {
        return $this->mAffectedRows;
    }
 
    function indexInfo( $table, $index, $fname = __METHOD__ ) {
        return false;
    }
 
    function indexUnique( $table, $index, $fname = __METHOD__ ) {
        return false;
    }
 
    function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
        if ( !count( $a ) ) {
            return true;
        }
 
        if ( !is_array( $options ) ) {
            $options = [ $options ];
        }
 
        if ( in_array( 'IGNORE', $options ) ) {
            $this->ignoreDupValOnIndex = true;
        }
 
        if ( !is_array( reset( $a ) ) ) {
            $a = [ $a ];
        }
 
        foreach ( $a as &$row ) {
            $this->insertOneRow( $table, $row, $fname );
        }
        $retVal = true;
 
        if ( in_array( 'IGNORE', $options ) ) {
            $this->ignoreDupValOnIndex = false;
        }
 
        return $retVal;
    }
 
    private function fieldBindStatement( $table, $col, &$val, $includeCol = false ) {
        $col_info = $this->fieldInfoMulti( $table, $col );
        $col_type = $col_info != false ? $col_info->type() : 'CONSTANT';
 
        $bind = '';
        if ( is_numeric( $col ) ) {
            $bind = $val;
            $val = null;
 
            return $bind;
        } elseif ( $includeCol ) {
            $bind = "$col = ";
        }
 
        if ( $val == '' && $val !== 0 && $col_type != 'BLOB' && $col_type != 'CLOB' ) {
            $val = null;
        }
 
        if ( $val === 'NULL' ) {
            $val = null;
        }
 
        if ( $val === null ) {
            if ( $col_info != false && $col_info->isNullable() == 0 && $col_info->defaultValue() != null ) {
                $bind .= 'DEFAULT';
            } else {
                $bind .= 'NULL';
            }
        } else {
            $bind .= ':' . $col;
        }
 
        return $bind;
    }
 
    private function insertOneRow( $table, $row, $fname ) {
        global $wgContLang;
 
        $table = $this->tableName( $table );
        // "INSERT INTO tables (a, b, c)"
        $sql = "INSERT INTO " . $table . " (" . implode( ',', array_keys( $row ) ) . ')';
        $sql .= " VALUES (";
 
        // for each value, append ":key"
        $first = true;
        foreach ( $row as $col => &$val ) {
            if ( !$first ) {
                $sql .= ', ';
            } else {
                $first = false;
            }
            if ( $this->isQuotedIdentifier( $val ) ) {
                $sql .= $this->removeIdentifierQuotes( $val );
                unset( $row[$col] );
            } else {
                $sql .= $this->fieldBindStatement( $table, $col, $val );
            }
        }
        $sql .= ')';
 
        $this->mLastResult = $stmt = oci_parse( $this->conn, $sql );
        if ( $stmt === false ) {
            $e = oci_error( $this->conn );
            $this->reportQueryError( $e['message'], $e['code'], $sql, __METHOD__ );
 
            return false;
        }
        foreach ( $row as $col => &$val ) {
            $col_info = $this->fieldInfoMulti( $table, $col );
            $col_type = $col_info != false ? $col_info->type() : 'CONSTANT';
 
            if ( $val === null ) {
                // do nothing ... null was inserted in statement creation
            } elseif ( $col_type != 'BLOB' && $col_type != 'CLOB' ) {
                if ( is_object( $val ) ) {
                    $val = $val->fetch();
                }
 
                // backward compatibility
                if ( preg_match( '/^timestamp.*/i', $col_type ) == 1 && strtolower( $val ) == 'infinity' ) {
                    $val = $this->getInfinity();
                }
 
                $val = ( $wgContLang != null ) ? $wgContLang->checkTitleEncoding( $val ) : $val;
                if ( oci_bind_by_name( $stmt, ":$col", $val, -1, SQLT_CHR ) === false ) {
                    $e = oci_error( $stmt );
                    $this->reportQueryError( $e['message'], $e['code'], $sql, __METHOD__ );
 
                    return false;
                }
            } else {
                $lob[$col] = oci_new_descriptor( $this->conn, OCI_D_LOB );
                if ( $lob[$col] === false ) {
                    $e = oci_error( $stmt );
                    throw new DBUnexpectedError( $this, "Cannot create LOB descriptor: " . $e['message'] );
                }
 
                if ( is_object( $val ) ) {
                    $val = $val->fetch();
                }
 
                if ( $col_type == 'BLOB' ) {
                    $lob[$col]->writeTemporary( $val, OCI_TEMP_BLOB );
                    oci_bind_by_name( $stmt, ":$col", $lob[$col], -1, OCI_B_BLOB );
                } else {
                    $lob[$col]->writeTemporary( $val, OCI_TEMP_CLOB );
                    oci_bind_by_name( $stmt, ":$col", $lob[$col], -1, OCI_B_CLOB );
                }
            }
        }
 
        Wikimedia\suppressWarnings();
 
        if ( oci_execute( $stmt, $this->execFlags() ) === false ) {
            $e = oci_error( $stmt );
            if ( !$this->ignoreDupValOnIndex || $e['code'] != '1' ) {
                $this->reportQueryError( $e['message'], $e['code'], $sql, __METHOD__ );
 
                return false;
            } else {
                $this->mAffectedRows = oci_num_rows( $stmt );
            }
        } else {
            $this->mAffectedRows = oci_num_rows( $stmt );
        }
 
        Wikimedia\restoreWarnings();
 
        if ( isset( $lob ) ) {
            foreach ( $lob as $lob_v ) {
                $lob_v->free();
            }
        }
 
        if ( !$this->trxLevel ) {
            oci_commit( $this->conn );
        }
 
        return oci_free_statement( $stmt );
    }
 
    function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds, $fname = __METHOD__,
        $insertOptions = [], $selectOptions = [], $selectJoinConds = []
    ) {
        $destTable = $this->tableName( $destTable );
 
        $sequenceData = $this->getSequenceData( $destTable );
        if ( $sequenceData !== false &&
            !isset( $varMap[$sequenceData['column']] )
        ) {
            $varMap[$sequenceData['column']] = 'GET_SEQUENCE_VALUE(\'' . $sequenceData['sequence'] . '\')';
        }
 
        // count-alias subselect fields to avoid abigious definition errors
        $i = 0;
        foreach ( $varMap as &$val ) {
            $val = $val . ' field' . ( $i++ );
        }
 
        $selectSql = $this->selectSQLText(
            $srcTable,
            array_values( $varMap ),
            $conds,
            $fname,
            $selectOptions,
            $selectJoinConds
        );
 
        $sql = "INSERT INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ') ' . $selectSql;
 
        if ( in_array( 'IGNORE', $insertOptions ) ) {
            $this->ignoreDupValOnIndex = true;
        }
 
        $retval = $this->query( $sql, $fname );
 
        if ( in_array( 'IGNORE', $insertOptions ) ) {
            $this->ignoreDupValOnIndex = false;
        }
 
        return $retval;
    }
 
    public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
        $fname = __METHOD__
    ) {
        if ( !count( $rows ) ) {
            return true; // nothing to do
        }
 
        if ( !is_array( reset( $rows ) ) ) {
            $rows = [ $rows ];
        }
 
        $sequenceData = $this->getSequenceData( $table );
        if ( $sequenceData !== false ) {
            // add sequence column to each list of columns, when not set
            foreach ( $rows as &$row ) {
                if ( !isset( $row[$sequenceData['column']] ) ) {
                    $row[$sequenceData['column']] =
                        $this->addIdentifierQuotes( 'GET_SEQUENCE_VALUE(\'' .
                            $sequenceData['sequence'] . '\')' );
                }
            }
        }
 
        return parent::upsert( $table, $rows, $uniqueIndexes, $set, $fname );
    }
 
    function tableName( $name, $format = 'quoted' ) {
        /*
        Replace reserved words with better ones
        Using uppercase because that's the only way Oracle can handle
        quoted tablenames
        */
        switch ( $name ) {
            case 'user':
                $name = 'MWUSER';
                break;
            case 'text':
                $name = 'PAGECONTENT';
                break;
        }
 
        return strtoupper( parent::tableName( $name, $format ) );
    }
 
    function tableNameInternal( $name ) {
        $name = $this->tableName( $name );
 
        return preg_replace( '/.*\.(.*)/', '$1', $name );
    }
 
    private function getSequenceData( $table ) {
        if ( $this->sequenceData == null ) {
            $result = $this->doQuery( "SELECT lower(asq.sequence_name),
                lower(atc.table_name),
                lower(atc.column_name)
            FROM all_sequences asq, all_tab_columns atc
            WHERE decode(
                    atc.table_name,
                    '{$this->tablePrefix}MWUSER',
                    '{$this->tablePrefix}USER',
                    atc.table_name
                ) || '_' ||
                atc.column_name || '_SEQ' = '{$this->tablePrefix}' || asq.sequence_name
                AND asq.sequence_owner = upper('{$this->dbName}')
                AND atc.owner = upper('{$this->dbName}')" );
 
            while ( ( $row = $result->fetchRow() ) !== false ) {
                $this->sequenceData[$row[1]] = [
                    'sequence' => $row[0],
                    'column' => $row[2]
                ];
            }
        }
        $table = strtolower( $this->removeIdentifierQuotes( $this->tableName( $table ) ) );
 
        return ( isset( $this->sequenceData[$table] ) ) ? $this->sequenceData[$table] : false;
    }
 
    function textFieldSize( $table, $field ) {
        $fieldInfoData = $this->fieldInfo( $table, $field );
 
        return $fieldInfoData->maxLength();
    }
 
    function limitResult( $sql, $limit, $offset = false ) {
        if ( $offset === false ) {
            $offset = 0;
        }
 
        return "SELECT * FROM ($sql) WHERE rownum >= (1 + $offset) AND rownum < (1 + $limit + $offset)";
    }
 
    function encodeBlob( $b ) {
        return new Blob( $b );
    }
 
    function decodeBlob( $b ) {
        if ( $b instanceof Blob ) {
            $b = $b->fetch();
        }
 
        return $b;
    }
 
    function unionQueries( $sqls, $all ) {
        $glue = ' UNION ALL ';
 
        return 'SELECT * ' . ( $all ? '' : '/* UNION_UNIQUE */ ' ) .
            'FROM (' . implode( $glue, $sqls ) . ')';
    }
 
    function wasDeadlock() {
        return $this->lastErrno() == 'OCI-00060';
    }
 
    function duplicateTableStructure( $oldName, $newName, $temporary = false,
        $fname = __METHOD__
    ) {
        $temporary = $temporary ? 'TRUE' : 'FALSE';
 
        $newName = strtoupper( $newName );
        $oldName = strtoupper( $oldName );
 
        $tabName = substr( $newName, strlen( $this->tablePrefix ) );
        $oldPrefix = substr( $oldName, 0, strlen( $oldName ) - strlen( $tabName ) );
        $newPrefix = strtoupper( $this->tablePrefix );
 
        return $this->doQuery( "BEGIN DUPLICATE_TABLE( '$tabName', " .
            "'$oldPrefix', '$newPrefix', $temporary ); END;" );
    }
 
    function listTables( $prefix = null, $fname = __METHOD__ ) {
        $listWhere = '';
        if ( !empty( $prefix ) ) {
            $listWhere = ' AND table_name LIKE \'' . strtoupper( $prefix ) . '%\'';
        }
 
        $owner = strtoupper( $this->dbName );
        $result = $this->doQuery( "SELECT table_name FROM all_tables " .
            "WHERE owner='$owner' AND table_name NOT LIKE '%!_IDX\$_' ESCAPE '!' $listWhere" );
 
        // dirty code ... i know
        $endArray = [];
        $endArray[] = strtoupper( $prefix . 'MWUSER' );
        $endArray[] = strtoupper( $prefix . 'PAGE' );
        $endArray[] = strtoupper( $prefix . 'IMAGE' );
        $fixedOrderTabs = $endArray;
        while ( ( $row = $result->fetchRow() ) !== false ) {
            if ( !in_array( $row['table_name'], $fixedOrderTabs ) ) {
                $endArray[] = $row['table_name'];
            }
        }
 
        return $endArray;
    }
 
    public function dropTable( $tableName, $fName = __METHOD__ ) {
        $tableName = $this->tableName( $tableName );
        if ( !$this->tableExists( $tableName ) ) {
            return false;
        }
 
        return $this->doQuery( "DROP TABLE $tableName CASCADE CONSTRAINTS PURGE" );
    }
 
    function timestamp( $ts = 0 ) {
        return wfTimestamp( TS_ORACLE, $ts );
    }
 
    public function aggregateValue( $valuedata, $valuename = 'value' ) {
        return $valuedata;
    }
 
    public function getSoftwareLink() {
        return '[{{int:version-db-oracle-url}} Oracle]';
    }
 
    function getServerVersion() {
        // better version number, fallback on driver
        $rset = $this->doQuery(
            'SELECT version FROM product_component_version ' .
                'WHERE UPPER(product) LIKE \'ORACLE DATABASE%\''
        );
        $row = $rset->fetchRow();
        if ( !$row ) {
            return oci_server_version( $this->conn );
        }
 
        return $row['version'];
    }
 
    function indexExists( $table, $index, $fname = __METHOD__ ) {
        $table = $this->tableName( $table );
        $table = strtoupper( $this->removeIdentifierQuotes( $table ) );
        $index = strtoupper( $index );
        $owner = strtoupper( $this->dbName );
        $sql = "SELECT 1 FROM all_indexes WHERE owner='$owner' AND index_name='{$table}_{$index}'";
        $res = $this->doQuery( $sql );
        if ( $res ) {
            $count = $res->numRows();
            $res->free();
        } else {
            $count = 0;
        }
 
        return $count != 0;
    }
 
    function tableExists( $table, $fname = __METHOD__ ) {
        $table = $this->tableName( $table );
        $table = $this->addQuotes( strtoupper( $this->removeIdentifierQuotes( $table ) ) );
        $owner = $this->addQuotes( strtoupper( $this->dbName ) );
        $sql = "SELECT 1 FROM all_tables WHERE owner=$owner AND table_name=$table";
        $res = $this->doQuery( $sql );
        if ( $res && $res->numRows() > 0 ) {
            $exists = true;
        } else {
            $exists = false;
        }
 
        $res->free();
 
        return $exists;
    }
 
    private function fieldInfoMulti( $table, $field ) {
        $field = strtoupper( $field );
        if ( is_array( $table ) ) {
            $table = array_map( [ $this, 'tableNameInternal' ], $table );
            $tableWhere = 'IN (';
            foreach ( $table as &$singleTable ) {
                $singleTable = $this->removeIdentifierQuotes( $singleTable );
                if ( isset( $this->mFieldInfoCache["$singleTable.$field"] ) ) {
                    return $this->mFieldInfoCache["$singleTable.$field"];
                }
                $tableWhere .= '\'' . $singleTable . '\',';
            }
            $tableWhere = rtrim( $tableWhere, ',' ) . ')';
        } else {
            $table = $this->removeIdentifierQuotes( $this->tableNameInternal( $table ) );
            if ( isset( $this->mFieldInfoCache["$table.$field"] ) ) {
                return $this->mFieldInfoCache["$table.$field"];
            }
            $tableWhere = '= \'' . $table . '\'';
        }
 
        $fieldInfoStmt = oci_parse(
            $this->conn,
            'SELECT * FROM wiki_field_info_full WHERE table_name ' .
                $tableWhere . ' and column_name = \'' . $field . '\''
        );
        if ( oci_execute( $fieldInfoStmt, $this->execFlags() ) === false ) {
            $e = oci_error( $fieldInfoStmt );
            $this->reportQueryError( $e['message'], $e['code'], 'fieldInfo QUERY', __METHOD__ );
 
            return false;
        }
        $res = new ORAResult( $this, $fieldInfoStmt );
        if ( $res->numRows() == 0 ) {
            if ( is_array( $table ) ) {
                foreach ( $table as &$singleTable ) {
                    $this->mFieldInfoCache["$singleTable.$field"] = false;
                }
            } else {
                $this->mFieldInfoCache["$table.$field"] = false;
            }
            $fieldInfoTemp = null;
        } else {
            $fieldInfoTemp = new ORAField( $res->fetchRow() );
            $table = $fieldInfoTemp->tableName();
            $this->mFieldInfoCache["$table.$field"] = $fieldInfoTemp;
        }
        $res->free();
 
        return $fieldInfoTemp;
    }
 
    function fieldInfo( $table, $field ) {
        if ( is_array( $table ) ) {
            throw new DBUnexpectedError( $this, 'DatabaseOracle::fieldInfo called with table array!' );
        }
 
        return $this->fieldInfoMulti( $table, $field );
    }
 
    protected function doBegin( $fname = __METHOD__ ) {
        $this->trxLevel = 1;
        $this->doQuery( 'SET CONSTRAINTS ALL DEFERRED' );
    }
 
    protected function doCommit( $fname = __METHOD__ ) {
        if ( $this->trxLevel ) {
            $ret = oci_commit( $this->conn );
            if ( !$ret ) {
                throw new DBUnexpectedError( $this, $this->lastError() );
            }
            $this->trxLevel = 0;
            $this->doQuery( 'SET CONSTRAINTS ALL IMMEDIATE' );
        }
    }
 
    protected function doRollback( $fname = __METHOD__ ) {
        if ( $this->trxLevel ) {
            oci_rollback( $this->conn );
            $this->trxLevel = 0;
            $this->doQuery( 'SET CONSTRAINTS ALL IMMEDIATE' );
        }
    }
 
    function sourceStream(
        $fp,
        callable $lineCallback = null,
        callable $resultCallback = null,
        $fname = __METHOD__, callable $inputCallback = null
    ) {
        $cmd = '';
        $done = false;
        $dollarquote = false;
 
        $replacements = [];
        // Defines must comply with ^define\s*([^\s=]*)\s*=\s?'\{\$([^\}]*)\}';
        while ( !feof( $fp ) ) {
            if ( $lineCallback ) {
                call_user_func( $lineCallback );
            }
            $line = trim( fgets( $fp, 1024 ) );
            $sl = strlen( $line ) - 1;
 
            if ( $sl < 0 ) {
                continue;
            }
            if ( '-' == $line[0] && '-' == $line[1] ) {
                continue;
            }
 
            // Allow dollar quoting for function declarations
            if ( substr( $line, 0, 8 ) == '/*$mw$*/' ) {
                if ( $dollarquote ) {
                    $dollarquote = false;
                    $line = str_replace( '/*$mw$*/', '', $line ); // remove dollarquotes
                    $done = true;
                } else {
                    $dollarquote = true;
                }
            } elseif ( !$dollarquote ) {
                if ( ';' == $line[$sl] && ( $sl < 2 || ';' != $line[$sl - 1] ) ) {
                    $done = true;
                    $line = substr( $line, 0, $sl );
                }
            }
 
            if ( $cmd != '' ) {
                $cmd .= ' ';
            }
            $cmd .= "$line\n";
 
            if ( $done ) {
                $cmd = str_replace( ';;', ";", $cmd );
                if ( strtolower( substr( $cmd, 0, 6 ) ) == 'define' ) {
                    if ( preg_match( '/^define\s*([^\s=]*)\s*=\s*\'\{\$([^\}]*)\}\'/', $cmd, $defines ) ) {
                        $replacements[$defines[2]] = $defines[1];
                    }
                } else {
                    foreach ( $replacements as $mwVar => $scVar ) {
                        $cmd = str_replace( '&' . $scVar . '.', '`{$' . $mwVar . '}`', $cmd );
                    }
 
                    $cmd = $this->replaceVars( $cmd );
                    if ( $inputCallback ) {
                        call_user_func( $inputCallback, $cmd );
                    }
                    $res = $this->doQuery( $cmd );
                    if ( $resultCallback ) {
                        call_user_func( $resultCallback, $res, $this );
                    }
 
                    if ( false === $res ) {
                        $err = $this->lastError();
 
                        return "Query \"{$cmd}\" failed with error code \"$err\".\n";
                    }
                }
 
                $cmd = '';
                $done = false;
            }
        }
 
        return true;
    }
 
    function selectDB( $db ) {
        $this->dbName = $db;
        if ( $db == null || $db == $this->user ) {
            return true;
        }
        $sql = 'ALTER SESSION SET CURRENT_SCHEMA=' . strtoupper( $db );
        $stmt = oci_parse( $this->conn, $sql );
        Wikimedia\suppressWarnings();
        $success = oci_execute( $stmt );
        Wikimedia\restoreWarnings();
        if ( !$success ) {
            $e = oci_error( $stmt );
            if ( $e['code'] != '1435' ) {
                $this->reportQueryError( $e['message'], $e['code'], $sql, __METHOD__ );
            }
 
            return false;
        }
 
        return true;
    }
 
    function strencode( $s ) {
        return str_replace( "'", "''", $s );
    }
 
    function addQuotes( $s ) {
        global $wgContLang;
        if ( isset( $wgContLang->mLoaded ) && $wgContLang->mLoaded ) {
            $s = $wgContLang->checkTitleEncoding( $s );
        }
 
        return "'" . $this->strencode( $s ) . "'";
    }
 
    public function addIdentifierQuotes( $s ) {
        if ( !$this->getFlag( DBO_DDLMODE ) ) {
            $s = '/*Q*/' . $s;
        }
 
        return $s;
    }
 
    public function removeIdentifierQuotes( $s ) {
        return strpos( $s, '/*Q*/' ) === false ? $s : substr( $s, 5 );
    }
 
    public function isQuotedIdentifier( $s ) {
        return strpos( $s, '/*Q*/' ) !== false;
    }
 
    private function wrapFieldForWhere( $table, &$col, &$val ) {
        global $wgContLang;
 
        $col_info = $this->fieldInfoMulti( $table, $col );
        $col_type = $col_info != false ? $col_info->type() : 'CONSTANT';
        if ( $col_type == 'CLOB' ) {
            $col = 'TO_CHAR(' . $col . ')';
            $val = $wgContLang->checkTitleEncoding( $val );
        } elseif ( $col_type == 'VARCHAR2' ) {
            $val = $wgContLang->checkTitleEncoding( $val );
        }
    }
 
    private function wrapConditionsForWhere( $table, $conds, $parentCol = null ) {
        $conds2 = [];
        foreach ( $conds as $col => $val ) {
            if ( is_array( $val ) ) {
                $conds2[$col] = $this->wrapConditionsForWhere( $table, $val, $col );
            } else {
                if ( is_numeric( $col ) && $parentCol != null ) {
                    $this->wrapFieldForWhere( $table, $parentCol, $val );
                } else {
                    $this->wrapFieldForWhere( $table, $col, $val );
                }
                $conds2[$col] = $val;
            }
        }
 
        return $conds2;
    }
 
    function selectRow( $table, $vars, $conds, $fname = __METHOD__,
        $options = [], $join_conds = []
    ) {
        if ( is_array( $conds ) ) {
            $conds = $this->wrapConditionsForWhere( $table, $conds );
        }
 
        return parent::selectRow( $table, $vars, $conds, $fname, $options, $join_conds );
    }
 
    function makeSelectOptions( $options ) {
        $preLimitTail = $postLimitTail = '';
        $startOpts = '';
 
        $noKeyOptions = [];
        foreach ( $options as $key => $option ) {
            if ( is_numeric( $key ) ) {
                $noKeyOptions[$option] = true;
            }
        }
 
        $preLimitTail .= $this->makeGroupByWithHaving( $options );
 
        $preLimitTail .= $this->makeOrderBy( $options );
 
        if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
            $postLimitTail .= ' FOR UPDATE';
        }
 
        if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
            $startOpts .= 'DISTINCT';
        }
 
        if ( isset( $options['USE INDEX'] ) && !is_array( $options['USE INDEX'] ) ) {
            $useIndex = $this->useIndexClause( $options['USE INDEX'] );
        } else {
            $useIndex = '';
        }
 
        if ( isset( $options['IGNORE INDEX'] ) && !is_array( $options['IGNORE INDEX'] ) ) {
            $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
        } else {
            $ignoreIndex = '';
        }
 
        return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
    }
 
    public function delete( $table, $conds, $fname = __METHOD__ ) {
        global $wgActorTableSchemaMigrationStage;
 
        if ( is_array( $conds ) ) {
            $conds = $this->wrapConditionsForWhere( $table, $conds );
        }
        // a hack for deleting pages, users and images (which have non-nullable FKs)
        // all deletions on these tables have transactions so final failure rollbacks these updates
        // @todo: Normalize the schema to match MySQL, no special FKs and such
        $table = $this->tableName( $table );
        if ( $table == $this->tableName( 'user' ) && $wgActorTableSchemaMigrationStage < MIGRATION_NEW ) {
            $this->update( 'archive', [ 'ar_user' => 0 ],
                [ 'ar_user' => $conds['user_id'] ], $fname );
            $this->update( 'ipblocks', [ 'ipb_user' => 0 ],
                [ 'ipb_user' => $conds['user_id'] ], $fname );
            $this->update( 'image', [ 'img_user' => 0 ],
                [ 'img_user' => $conds['user_id'] ], $fname );
            $this->update( 'oldimage', [ 'oi_user' => 0 ],
                [ 'oi_user' => $conds['user_id'] ], $fname );
            $this->update( 'filearchive', [ 'fa_deleted_user' => 0 ],
                [ 'fa_deleted_user' => $conds['user_id'] ], $fname );
            $this->update( 'filearchive', [ 'fa_user' => 0 ],
                [ 'fa_user' => $conds['user_id'] ], $fname );
            $this->update( 'uploadstash', [ 'us_user' => 0 ],
                [ 'us_user' => $conds['user_id'] ], $fname );
            $this->update( 'recentchanges', [ 'rc_user' => 0 ],
                [ 'rc_user' => $conds['user_id'] ], $fname );
            $this->update( 'logging', [ 'log_user' => 0 ],
                [ 'log_user' => $conds['user_id'] ], $fname );
        } elseif ( $table == $this->tableName( 'image' ) ) {
            $this->update( 'oldimage', [ 'oi_name' => 0 ],
                [ 'oi_name' => $conds['img_name'] ], $fname );
        }
 
        return parent::delete( $table, $conds, $fname );
    }
 
    function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
        global $wgContLang;
 
        $table = $this->tableName( $table );
        $opts = $this->makeUpdateOptions( $options );
        $sql = "UPDATE $opts $table SET ";
 
        $first = true;
        foreach ( $values as $col => &$val ) {
            $sqlSet = $this->fieldBindStatement( $table, $col, $val, true );
 
            if ( !$first ) {
                $sqlSet = ', ' . $sqlSet;
            } else {
                $first = false;
            }
            $sql .= $sqlSet;
        }
 
        if ( $conds !== [] && $conds !== '*' ) {
            $conds = $this->wrapConditionsForWhere( $table, $conds );
            $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
        }
 
        $this->mLastResult = $stmt = oci_parse( $this->conn, $sql );
        if ( $stmt === false ) {
            $e = oci_error( $this->conn );
            $this->reportQueryError( $e['message'], $e['code'], $sql, __METHOD__ );
 
            return false;
        }
        foreach ( $values as $col => &$val ) {
            $col_info = $this->fieldInfoMulti( $table, $col );
            $col_type = $col_info != false ? $col_info->type() : 'CONSTANT';
 
            if ( $val === null ) {
                // do nothing ... null was inserted in statement creation
            } elseif ( $col_type != 'BLOB' && $col_type != 'CLOB' ) {
                if ( is_object( $val ) ) {
                    $val = $val->getData();
                }
 
                if ( preg_match( '/^timestamp.*/i', $col_type ) == 1 && strtolower( $val ) == 'infinity' ) {
                    $val = '31-12-2030 12:00:00.000000';
                }
 
                $val = ( $wgContLang != null ) ? $wgContLang->checkTitleEncoding( $val ) : $val;
                if ( oci_bind_by_name( $stmt, ":$col", $val ) === false ) {
                    $e = oci_error( $stmt );
                    $this->reportQueryError( $e['message'], $e['code'], $sql, __METHOD__ );
 
                    return false;
                }
            } else {
                $lob[$col] = oci_new_descriptor( $this->conn, OCI_D_LOB );
                if ( $lob[$col] === false ) {
                    $e = oci_error( $stmt );
                    throw new DBUnexpectedError( $this, "Cannot create LOB descriptor: " . $e['message'] );
                }
 
                if ( is_object( $val ) ) {
                    $val = $val->getData();
                }
 
                if ( $col_type == 'BLOB' ) {
                    $lob[$col]->writeTemporary( $val );
                    oci_bind_by_name( $stmt, ":$col", $lob[$col], -1, SQLT_BLOB );
                } else {
                    $lob[$col]->writeTemporary( $val );
                    oci_bind_by_name( $stmt, ":$col", $lob[$col], -1, OCI_B_CLOB );
                }
            }
        }
 
        Wikimedia\suppressWarnings();
 
        if ( oci_execute( $stmt, $this->execFlags() ) === false ) {
            $e = oci_error( $stmt );
            if ( !$this->ignoreDupValOnIndex || $e['code'] != '1' ) {
                $this->reportQueryError( $e['message'], $e['code'], $sql, __METHOD__ );
 
                return false;
            } else {
                $this->mAffectedRows = oci_num_rows( $stmt );
            }
        } else {
            $this->mAffectedRows = oci_num_rows( $stmt );
        }
 
        Wikimedia\restoreWarnings();
 
        if ( isset( $lob ) ) {
            foreach ( $lob as $lob_v ) {
                $lob_v->free();
            }
        }
 
        if ( !$this->trxLevel ) {
            oci_commit( $this->conn );
        }
 
        return oci_free_statement( $stmt );
    }
 
    function bitNot( $field ) {
        // expecting bit-fields smaller than 4bytes
        return 'BITNOT(' . $field . ')';
    }
 
    function bitAnd( $fieldLeft, $fieldRight ) {
        return 'BITAND(' . $fieldLeft . ', ' . $fieldRight . ')';
    }
 
    function bitOr( $fieldLeft, $fieldRight ) {
        return 'BITOR(' . $fieldLeft . ', ' . $fieldRight . ')';
    }
 
    function getDBname() {
        return $this->dbName;
    }
 
    function getServer() {
        return $this->server;
    }
 
    public function buildGroupConcatField(
        $delim, $table, $field, $conds = '', $join_conds = []
    ) {
        $fld = "LISTAGG($field," . $this->addQuotes( $delim ) . ") WITHIN GROUP (ORDER BY $field)";
 
        return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
    }
 
    public function buildSubstring( $input, $startPosition, $length = null ) {
        $this->assertBuildSubstringParams( $startPosition, $length );
        $params = [ $input, $startPosition ];
        if ( $length !== null ) {
            $params[] = $length;
        }
        return 'SUBSTR(' . implode( ',', $params ) . ')';
    }
 
    public function buildStringCast( $field ) {
        return 'CAST ( ' . $field . ' AS VARCHAR2 )';
    }
 
    public function getInfinity() {
        return '31-12-2030 12:00:00.000000';
    }
}