<?php

/* vim: set expandtab sw=4 ts=4 sts=4: */
/**
 * function for the main export logic
 *
 * @package PhpMyAdmin
 */

if (! defined('PHPMYADMIN')) {
    exit;
}

/**
 * Sets a session variable upon a possible fatal error during export
 *
 * @return void
 */
function PMA_shutdownDuringExport()
{
    $a = error_get_last();
    if ($a != null
        && /*overload*/mb_strpos($a['message'], "execution time")
    ) {
        //write in partially downloaded file for future reference of user
        print_r($a);
        //set session variable to check if there was error while exporting
        $_SESSION['pma_export_error'] = $a['message'];
    }
}

/**
 * Detect ob_gzhandler
 *
 * @return bool
 */
function PMA_isGzHandlerEnabled()
{
    return in_array('ob_gzhandler', ob_list_handlers());
}

/**
 * Detect whether gzencode is needed; it might not be needed if
 * the server is already compressing by itself
 *
 * @return bool Whether gzencode is needed
 */
function PMA_gzencodeNeeded()
{
    /*
     * We should gzencode only if the function exists
     * but we don't want to compress twice, therefore
     * gzencode only if transparent compression is not enabled
     * and gz compression was not asked via $cfg['OBGzip']
     * but transparent compression does not apply when saving to server
     */
    if (@function_exists('gzencode')
        && ((! @ini_get('zlib.output_compression')
        && ! PMA_isGzHandlerEnabled())
        || $GLOBALS['save_on_server'])
    ) {
        return true;
    } else {
        return false;
    }
}

/**
 * Output handler for all exports, if needed buffering, it stores data into
 * $dump_buffer, otherwise it prints them out.
 *
 * @param string $line the insert statement
 *
 * @return bool Whether output succeeded
 */
function PMA_exportOutputHandler($line)
{
    global $time_start, $dump_buffer, $dump_buffer_len, $save_filename;

    // Kanji encoding convert feature
    if ($GLOBALS['output_kanji_conversion']) {
        $line = PMA_Kanji_strConv(
            $line,
            $GLOBALS['knjenc'],
            isset($GLOBALS['xkana']) ? $GLOBALS['xkana'] : ''
        );
    }

    // If we have to buffer data, we will perform everything at once at the end
    if ($GLOBALS['buffer_needed']) {

        $dump_buffer .= $line;
        if ($GLOBALS['onfly_compression']) {

            $dump_buffer_len += /*overload*/mb_strlen($line);

            if ($dump_buffer_len > $GLOBALS['memory_limit']) {
                if ($GLOBALS['output_charset_conversion']) {
                    $dump_buffer = PMA_convertString(
                        'utf-8',
                        $GLOBALS['charset_of_file'],
                        $dump_buffer
                    );
                }
                if ($GLOBALS['compression'] == 'gzip'
                    && PMA_gzencodeNeeded()
                ) {
                    // as a gzipped file
                    // without the optional parameter level because it bugs
                    $dump_buffer = gzencode($dump_buffer);
                }
                if ($GLOBALS['save_on_server']) {
                    $write_result = @fwrite($GLOBALS['file_handle'], $dump_buffer);
                    // Here, use strlen rather than mb_strlen to get the length
                    // in bytes to compare against the number of bytes written.
                    if ($write_result != strlen($dump_buffer)) {
                        $GLOBALS['message'] = PMA_Message::error(
                            __('Insufficient space to save the file %s.')
                        );
                        $GLOBALS['message']->addParam($save_filename);
                        return false;
                    }
                } else {
                    echo $dump_buffer;
                }
                $dump_buffer = '';
                $dump_buffer_len = 0;
            }
        } else {
            $time_now = time();
            if ($time_start >= $time_now + 30) {
                $time_start = $time_now;
                header('X-pmaPing: Pong');
            } // end if
        }
    } else {
        if ($GLOBALS['asfile']) {
            if ($GLOBALS['output_charset_conversion']) {
                $line = PMA_convertString(
                    'utf-8',
                    $GLOBALS['charset_of_file'],
                    $line
                );
            }
            if ($GLOBALS['save_on_server'] && /*overload*/mb_strlen($line) > 0) {
                $write_result = @fwrite($GLOBALS['file_handle'], $line);
                // Here, use strlen rather than mb_strlen to get the length
                // in bytes to compare against the number of bytes written.
                if (! $write_result
                    || $write_result != strlen($line)
                ) {
                    $GLOBALS['message'] = PMA_Message::error(
                        __('Insufficient space to save the file %s.')
                    );
                    $GLOBALS['message']->addParam($save_filename);
                    return false;
                }
                $time_now = time();
                if ($time_start >= $time_now + 30) {
                    $time_start = $time_now;
                    header('X-pmaPing: Pong');
                } // end if
            } else {
                // We export as file - output normally
                echo $line;
            }
        } else {
            // We export as html - replace special chars
            echo htmlspecialchars($line);
        }
    }
    return true;
} // end of the 'PMA_exportOutputHandler()' function

/**
 * Returns HTML containing the footer for a displayed export
 *
 * @param string $back_button the link for going Back
 *
 * @return string $html the HTML output
 */
function PMA_getHtmlForDisplayedExportFooter($back_button)
{
    /**
     * Close the html tags and add the footers for on-screen export
     */
    $html = '</textarea>'
        . '    </form>'
        // bottom back button
        . $back_button
        . '</div>'
        . '<script type="text/javascript">' . "\n"
        . '//<![CDATA[' . "\n"
        . 'var $body = $("body");' . "\n"
        . '$("#textSQLDUMP")' . "\n"
        . '.width($body.width() - 50)' . "\n"
        . '.height($body.height() - 100);' . "\n"
        . '//]]>' . "\n"
        . '</script>' . "\n";
    return $html;
}

/**
 * Computes the memory limit for export
 *
 * @return int $memory_limit the memory limit
 */
function PMA_getMemoryLimitForExport()
{
    $memory_limit = trim(@ini_get('memory_limit'));
    $memory_limit_num = (int)substr($memory_limit, 0, -1);
    $lowerLastChar = strtolower(substr($memory_limit, -1));
    // 2 MB as default
    if (empty($memory_limit) || '-1' == $memory_limit) {
        $memory_limit = 2 * 1024 * 1024;
    } elseif ($lowerLastChar == 'm') {
        $memory_limit = $memory_limit_num * 1024 * 1024;
    } elseif ($lowerLastChar == 'k') {
        $memory_limit = $memory_limit_num * 1024;
    } elseif ($lowerLastChar == 'g') {
        $memory_limit = $memory_limit_num * 1024 * 1024 * 1024;
    } else {
        $memory_limit = (int)$memory_limit;
    }

    // Some of memory is needed for other things and as threshold.
    // During export I had allocated (see memory_get_usage function)
    // approx 1.2MB so this comes from that.
    if ($memory_limit > 1500000) {
        $memory_limit -= 1500000;
    }

    // Some memory is needed for compression, assume 1/3
    $memory_limit /= 8;
    return $memory_limit;
}

/**
 * Return the filename and MIME type for export file
 *
 * @param string $export_type       type of export
 * @param string $remember_template whether to remember template
 * @param object $export_plugin     the export plugin
 * @param string $compression       compression asked
 * @param string $filename_template the filename template
 *
 * @return array the filename template and mime type
 */
function PMA_getExportFilenameAndMimetype(
    $export_type, $remember_template, $export_plugin, $compression,
    $filename_template
) {
    if ($export_type == 'server') {
        if (! empty($remember_template)) {
            $GLOBALS['PMA_Config']->setUserValue(
                'pma_server_filename_template',
                'Export/file_template_server',
                $filename_template
            );
        }
    } elseif ($export_type == 'database') {
        if (! empty($remember_template)) {
            $GLOBALS['PMA_Config']->setUserValue(
                'pma_db_filename_template',
                'Export/file_template_database',
                $filename_template
            );
        }
    } else {
        if (! empty($remember_template)) {
            $GLOBALS['PMA_Config']->setUserValue(
                'pma_table_filename_template',
                'Export/file_template_table',
                $filename_template
            );
        }
    }
    $filename = PMA_Util::expandUserString($filename_template);
    // remove dots in filename (coming from either the template or already
    // part of the filename) to avoid a remote code execution vulnerability
    $filename = PMA_sanitizeFilename($filename, $replaceDots = true);

    // Grab basic dump extension and mime type
    // Check if the user already added extension;
    // get the substring where the extension would be if it was included
    $extension_start_pos = /*overload*/mb_strlen($filename) - /*overload*/mb_strlen(
        $export_plugin->getProperties()->getExtension()
    ) - 1;
    $user_extension = /*overload*/mb_substr(
        $filename, $extension_start_pos, /*overload*/mb_strlen($filename)
    );
    $required_extension = "." . $export_plugin->getProperties()->getExtension();
    if (/*overload*/mb_strtolower($user_extension) != $required_extension) {
        $filename  .= $required_extension;
    }
    $mime_type  = $export_plugin->getProperties()->getMimeType();

    // If dump is going to be compressed, set correct mime_type and add
    // compression to extension
    if ($compression == 'gzip') {
        $filename  .= '.gz';
        $mime_type = 'application/x-gzip';
    } elseif ($compression == 'zip') {
        $filename  .= '.zip';
        $mime_type = 'application/zip';
    }
    return array($filename, $mime_type);
}

/**
 * Open the export file
 *
 * @param string  $filename     the export filename
 * @param boolean $quick_export whether it's a quick export or not
 *
 * @return array the full save filename, possible message and the file handle
 */
function PMA_openExportFile($filename, $quick_export)
{
    $file_handle = null;
    $message = '';

    $save_filename = PMA_Util::userDir($GLOBALS['cfg']['SaveDir'])
        . preg_replace('@[/\\\\]@', '_', $filename);

    if (file_exists($save_filename)
        && ((! $quick_export && empty($_REQUEST['onserverover']))
        || ($quick_export
        && $_REQUEST['quick_export_onserverover'] != 'saveitover'))
    ) {
        $message = PMA_Message::error(
            __(
                'File %s already exists on server, '
                . 'change filename or check overwrite option.'
            )
        );
        $message->addParam($save_filename);
    } elseif (is_file($save_filename) && ! is_writable($save_filename)) {
        $message = PMA_Message::error(
            __(
                'The web server does not have permission '
                . 'to save the file %s.'
            )
        );
        $message->addParam($save_filename);
    } elseif (! $file_handle = @fopen($save_filename, 'w')) {
        $message = PMA_Message::error(
            __(
                'The web server does not have permission '
                . 'to save the file %s.'
            )
        );
        $message->addParam($save_filename);
    }
    return array($save_filename, $message, $file_handle);
}

/**
 * Close the export file
 *
 * @param resource $file_handle   the export file handle
 * @param string   $dump_buffer   the current dump buffer
 * @param string   $save_filename the export filename
 *
 * @return object $message a message object (or empty string)
 */
function PMA_closeExportFile($file_handle, $dump_buffer, $save_filename)
{
    $write_result = @fwrite($file_handle, $dump_buffer);
    fclose($file_handle);
    // Here, use strlen rather than mb_strlen to get the length
    // in bytes to compare against the number of bytes written.
    if (/*overload*/mb_strlen($dump_buffer) > 0
        && (! $write_result || $write_result != strlen($dump_buffer))
    ) {
        $message = new PMA_Message(
            __('Insufficient space to save the file %s.'),
            PMA_Message::ERROR,
            array($save_filename)
        );
    } else {
        $message = new PMA_Message(
            __('Dump has been saved to file %s.'),
            PMA_Message::SUCCESS,
            array($save_filename)
        );
    }
    return $message;
}

/**
 * Compress the export buffer
 *
 * @param string $dump_buffer the current dump buffer
 * @param string $compression the compression mode
 * @param string $filename    the filename
 *
 * @return object $message a message object (or empty string)
 */
function PMA_compressExport($dump_buffer, $compression, $filename)
{
    if ($compression == 'zip' && @function_exists('gzcompress')) {
        $zipfile = new ZipFile();
        $zipfile->addFile(
            $dump_buffer,
            substr($filename, 0, -4)
        );
        $dump_buffer = $zipfile->file();
    } elseif ($compression == 'gzip' && PMA_gzencodeNeeded()) {
        // without the optional parameter level because it bugs
        $dump_buffer = gzencode($dump_buffer);
    }
    return $dump_buffer;
}

/**
 * Returns HTML containing the header for a displayed export
 *
 * @param string $export_type the export type
 * @param string $db          the database name
 * @param string $table       the table name
 *
 * @return array the generated HTML and back button
 */
function PMA_getHtmlForDisplayedExportHeader($export_type, $db, $table)
{
    $html = '<div style="text-align: ' . $GLOBALS['cell_align_left'] . '">';

    /**
     * Displays a back button with all the $_REQUEST data in the URL
     * (store in a variable to also display after the textarea)
     */
    $back_button = '<p>[ <a href="';
    if ($export_type == 'server') {
        $back_button .= 'server_export.php' . PMA_URL_getCommon();
    } elseif ($export_type == 'database') {
        $back_button .= 'db_export.php' . PMA_URL_getCommon(array('db' => $db));
    } else {
        $back_button .= 'tbl_export.php' . PMA_URL_getCommon(
            array(
                'db' => $db, 'table' => $table
            )
        );
    }

    // Convert the multiple select elements from an array to a string
    if ($export_type == 'server' && isset($_REQUEST['db_select'])) {
        $_REQUEST['db_select'] = implode(",", $_REQUEST['db_select']);
    } elseif ($export_type == 'database'
        && isset($_REQUEST['table_select'])
    ) {
        $_REQUEST['table_select'] = implode(",", $_REQUEST['table_select']);
    }

    foreach ($_REQUEST as $name => $value) {
        if (!is_array($value)) {
            $back_button .= '&amp;' . urlencode($name) . '=' . urlencode($value);
        }
    }
    $back_button .= '&amp;repopulate=1">' . __('Back') . '</a> ]</p>';

    $html .= $back_button
        . '<form name="nofunction">'
        . '<textarea name="sqldump" cols="50" rows="30" '
        . 'id="textSQLDUMP" wrap="OFF">';

    return array($html, $back_button);
}

/**
 * Export at the server level
 *
 * @param string $db_select       the selected databases to export
 * @param string $whatStrucOrData structure or data or both
 * @param object $export_plugin   the selected export plugin
 * @param string $crlf            end of line character(s)
 * @param string $err_url         the URL in case of error
 * @param string $export_type     the export type
 * @param bool   $do_relation     whether to export relation info
 * @param bool   $do_comments     whether to add comments
 * @param bool   $do_mime         whether to add MIME info
 * @param bool   $do_dates        whether to add dates
 * @param array  $aliases         Alias information for db/table/column
 *
 * @return void
 */
function PMA_exportServer(
    $db_select, $whatStrucOrData, $export_plugin, $crlf, $err_url,
    $export_type, $do_relation, $do_comments, $do_mime, $do_dates,
    $aliases
) {
    if (! empty($db_select)) {
        $tmp_select = implode($db_select, '|');
        $tmp_select = '|' . $tmp_select . '|';
    }
    // Walk over databases
    foreach ($GLOBALS['pma']->databases as $current_db) {
        if (isset($tmp_select)
            && /*overload*/mb_strpos(' ' . $tmp_select, '|' . $current_db . '|')
        ) {
            $tables = $GLOBALS['dbi']->getTables($current_db);
            PMA_exportDatabase(
                $current_db, $tables, $whatStrucOrData, $export_plugin, $crlf,
                $err_url, $export_type, $do_relation, $do_comments, $do_mime,
                $do_dates, $aliases
            );
        }
    } // end foreach database
}

/**
 * Export at the database level
 *
 * @param string $db              the database to export
 * @param array  $tables          the tables to export
 * @param string $whatStrucOrData structure or data or both
 * @param object $export_plugin   the selected export plugin
 * @param string $crlf            end of line character(s)
 * @param string $err_url         the URL in case of error
 * @param string $export_type     the export type
 * @param bool   $do_relation     whether to export relation info
 * @param bool   $do_comments     whether to add comments
 * @param bool   $do_mime         whether to add MIME info
 * @param bool   $do_dates        whether to add dates
 * @param array  $aliases         Alias information for db/table/column
 *
 * @return void
 */
function PMA_exportDatabase(
    $db, $tables, $whatStrucOrData, $export_plugin, $crlf, $err_url,
    $export_type, $do_relation, $do_comments, $do_mime, $do_dates,
    $aliases
) {
    $db_alias = !empty($aliases[$db]['alias'])
        ? $aliases[$db]['alias'] : '';
    if (! $export_plugin->exportDBHeader($db, $db_alias)) {
        return;
    }
    if (! $export_plugin->exportDBCreate($db, $db_alias)) {
        return;
    }

    if (method_exists($export_plugin, 'exportRoutines')
        && /*overload*/mb_strpos(
            $GLOBALS['sql_structure_or_data'],
            'structure'
        ) !== false
        && isset($GLOBALS['sql_procedure_function'])
    ) {
        $export_plugin->exportRoutines($db, $aliases);
    }

    $views = array();

    foreach ($tables as $table) {
        // if this is a view, collect it for later;
        // views must be exported after the tables
        $is_view = PMA_Table::isView($db, $table);
        if ($is_view) {
            $views[] = $table;
        }
        if ($whatStrucOrData == 'structure'
            || $whatStrucOrData == 'structure_and_data'
        ) {
            // for a view, export a stand-in definition of the table
            // to resolve view dependencies

            if ($is_view) {

                if (isset($GLOBALS['sql_create_view'])) {
                    if (! $export_plugin->exportStructure(
                        $db, $table, $crlf, $err_url, 'stand_in',
                        $export_type, $do_relation, $do_comments,
                        $do_mime, $do_dates, $aliases
                    )) {
                        break 1;
                    }
                }

            } else if (isset($GLOBALS['sql_create_table'])) {

                $table_size = $GLOBALS['maxsize'];
                // Checking if the maximum table size constrain has been set
                // And if that constrain is a valid number or not
                if ($table_size !== '' && is_numeric($table_size)) {
                    // This obtains the current table's size
                    $query = 'SELECT data_length + index_length
                          from information_schema.TABLES
                          WHERE table_schema = "' . $db . '"
                          AND table_name = "' . $table . '"';

                    $size = $GLOBALS['dbi']->fetchValue($query);
                    //Converting the size to MB
                    $size = ($size / 1024) / 1024;
                    if ($size > $table_size) {
                        continue;
                    }
                }

                if (! $export_plugin->exportStructure(
                    $db, $table, $crlf, $err_url, 'create_table',
                    $export_type, $do_relation, $do_comments,
                    $do_mime, $do_dates, $aliases
                )) {
                    break 1;
                }

            }

        }
        // if this is a view or a merge table, don't export data
        if (($whatStrucOrData == 'data'
            || $whatStrucOrData == 'structure_and_data')
            && ! ($is_view || PMA_Table::isMerge($db, $table))
        ) {
            $local_query  = 'SELECT * FROM ' . PMA_Util::backquote($db)
                . '.' . PMA_Util::backquote($table);
            if (! $export_plugin->exportData(
                $db, $table, $crlf, $err_url, $local_query, $aliases
            )) {
                break 1;
            }
        }
        // now export the triggers (needs to be done after the data because
        // triggers can modify already imported tables)
        if (isset($GLOBALS['sql_create_trigger']) && ($whatStrucOrData == 'structure'
            || $whatStrucOrData == 'structure_and_data')
        ) {
            if (! $export_plugin->exportStructure(
                $db, $table, $crlf, $err_url, 'triggers',
                $export_type, $do_relation, $do_comments,
                $do_mime, $do_dates, $aliases
            )) {
                break 1;
            }
        }
    }

    if (isset($GLOBALS['sql_create_view'])) {

        foreach ($views as $view) {
            // no data export for a view
            if ($whatStrucOrData == 'structure'
                || $whatStrucOrData == 'structure_and_data'
            ) {
                if (! $export_plugin->exportStructure(
                    $db, $view, $crlf, $err_url, 'create_view',
                    $export_type, $do_relation, $do_comments,
                    $do_mime, $do_dates, $aliases
                )) {
                    break 1;
                }
            }
        }

    }

    if (! $export_plugin->exportDBFooter($db, $db_alias)) {
        return;
    }
}

/**
 * Export at the table level
 *
 * @param string $db              the database to export
 * @param string $table           the table to export
 * @param string $whatStrucOrData structure or data or both
 * @param object $export_plugin   the selected export plugin
 * @param string $crlf            end of line character(s)
 * @param string $err_url         the URL in case of error
 * @param string $export_type     the export type
 * @param bool   $do_relation     whether to export relation info
 * @param bool   $do_comments     whether to add comments
 * @param bool   $do_mime         whether to add MIME info
 * @param bool   $do_dates        whether to add dates
 * @param string $allrows         whether "dump all rows" was ticked
 * @param string $limit_to        upper limit
 * @param string $limit_from      starting limit
 * @param string $sql_query       query for which exporting is requested
 * @param array  $aliases         Alias information for db/table/column
 *
 * @return void
 */
function PMA_exportTable(
    $db, $table, $whatStrucOrData, $export_plugin, $crlf, $err_url,
    $export_type, $do_relation, $do_comments, $do_mime, $do_dates,
    $allrows, $limit_to, $limit_from, $sql_query, $aliases
) {
    $db_alias = !empty($aliases[$db]['alias'])
        ? $aliases[$db]['alias'] : '';
    if (! $export_plugin->exportDBHeader($db, $db_alias)) {
        return;
    }
    if (isset($allrows)
        && $allrows == '0'
        && $limit_to > 0
        && $limit_from >= 0
    ) {
        $add_query  = ' LIMIT '
                    . (($limit_from > 0) ? $limit_from . ', ' : '')
                    . $limit_to;
    } else {
        $add_query  = '';
    }

    $is_view = PMA_Table::isView($db, $table);
    if ($whatStrucOrData == 'structure'
        || $whatStrucOrData == 'structure_and_data'
    ) {

        if ($is_view) {

            if (isset($GLOBALS['sql_create_view'])) {
                if (! $export_plugin->exportStructure(
                    $db, $table, $crlf, $err_url, 'create_view',
                    $export_type, $do_relation, $do_comments,
                    $do_mime, $do_dates, $aliases
                )) {
                    return;
                }
            }

        } else if (isset($GLOBALS['sql_create_table'])) {

            if (! $export_plugin->exportStructure(
                $db, $table, $crlf, $err_url, 'create_table',
                $export_type, $do_relation, $do_comments,
                $do_mime, $do_dates, $aliases
            )) {
                return;
            }

        }

    }
    // If this is an export of a single view, we have to export data;
    // for example, a PDF report
    // if it is a merge table, no data is exported
    if (($whatStrucOrData == 'data'
        || $whatStrucOrData == 'structure_and_data')
        && ! PMA_Table::isMerge($db, $table)
    ) {
        if (! empty($sql_query)) {
            // only preg_replace if needed
            if (! empty($add_query)) {
                // remove trailing semicolon before adding a LIMIT
                $sql_query = preg_replace('%;\s*$%', '', $sql_query);
            }
            $local_query = $sql_query . $add_query;
            $GLOBALS['dbi']->selectDb($db);
        } else {
            $local_query  = 'SELECT * FROM ' . PMA_Util::backquote($db)
                . '.' . PMA_Util::backquote($table) . $add_query;
        }
        if (! $export_plugin->exportData(
            $db, $table, $crlf, $err_url, $local_query, $aliases
        )) {
            return;
        }
    }
    // now export the triggers (needs to be done after the data because
    // triggers can modify already imported tables)
    if (isset($GLOBALS['sql_create_trigger']) && ($whatStrucOrData == 'structure'
        || $whatStrucOrData == 'structure_and_data')
    ) {
        if (! $export_plugin->exportStructure(
            $db, $table, $crlf, $err_url, 'triggers',
            $export_type, $do_relation, $do_comments,
            $do_mime, $do_dates, $aliases
        )) {
            return;
        }
    }
    if (! $export_plugin->exportDBFooter($db, $db_alias)) {
        return;
    }
}

/**
 * Loads correct page after doing export
 *
 * @param string $db          the database name
 * @param string $table       the table name
 * @param string $export_type Export type
 *
 * @return void
 */
function PMA_showExportPage($db, $table, $export_type)
{
    global $cfg;
    if ($export_type == 'server') {
        $active_page = 'server_export.php';
        include_once 'server_export.php';
    } elseif ($export_type == 'database') {
        $active_page = 'db_export.php';
        include_once 'db_export.php';
    } else {
        $active_page = 'tbl_export.php';
        include_once 'tbl_export.php';
    }
    exit();
}

/**
 * Merge two alias arrays, if array1 and array2 have
 * conflicting alias then array2 value is used if it
 * is non empty otherwise array1 value.
 *
 * @param array $aliases1 first array of aliases
 * @param array $aliases2 second array of aliases
 *
 * @return array resultant merged aliases info
 */
function PMA_mergeAliases($aliases1, $aliases2)
{
    // First do a recursive array merge
    // on aliases arrays.
    $aliases = array_merge_recursive($aliases1, $aliases2);
    // Now, resolve conflicts in aliases, if any
    foreach ($aliases as $db_name => $db) {
        // If alias key is an array then
        // it is a merge conflict.
        if (isset($db['alias']) && is_array($db['alias'])) {
            $val1 = $db['alias'][0];
            $val2 = $db['alias'][1];
            // Use aliases2 alias if non empty
            $aliases[$db_name]['alias']
                = empty($val2) ? $val1 : $val2;
        }
        if (!isset($db['tables'])) {
            continue;
        }
        foreach ($db['tables'] as $tbl_name => $tbl) {
            if (isset($tbl['alias']) && is_array($tbl['alias'])) {
                $val1 = $tbl['alias'][0];
                $val2 = $tbl['alias'][1];
                // Use aliases2 alias if non empty
                $aliases[$db_name]['tables'][$tbl_name]['alias']
                    = empty($val2) ? $val1 : $val2;
            }
            if (!isset($tbl['columns'])) {
                continue;
            }
            foreach ($tbl['columns'] as  $col => $col_as) {
                if (isset($col_as) && is_array($col_as)) {
                    $val1 = $col_as[0];
                    $val2 = $col_as[1];
                    // Use aliases2 alias if non empty
                    $aliases[$db_name]['tables'][$tbl_name]['columns'][$col]
                        = empty($val2) ? $val1 : $val2;
                }
            };
        };
    }
    return $aliases;
}
?>