DatabaseError.php

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<?php
class DBError extends MWException {
    public $db;

    function __construct( DatabaseBase $db = null, $error ) {
        $this->db = $db;
        parent::__construct( $error );
    }
}

class DBExpectedError extends DBError {
    function getText() {
        global $wgShowDBErrorBacktrace;

        $s = $this->getTextContent() . "\n";

        if ( $wgShowDBErrorBacktrace ) {
            $s .= "Backtrace:\n" . $this->getTraceAsString() . "\n";
        }

        return $s;
    }

    function getHTML() {
        global $wgShowDBErrorBacktrace;

        $s = $this->getHTMLContent();

        if ( $wgShowDBErrorBacktrace ) {
            $s .= '<p>Backtrace:</p><pre>' . htmlspecialchars( $this->getTraceAsString() ) . '</pre>';
        }

        return $s;
    }

    protected function getTextContent() {
        return $this->getMessage();
    }

    protected function getHTMLContent() {
        return '<p>' . nl2br( htmlspecialchars( $this->getTextContent() ) ) . '</p>';
    }
}

class DBConnectionError extends DBExpectedError {
    public $error;

    function __construct( DatabaseBase $db = null, $error = 'unknown error' ) {
        $msg = 'DB connection error';

        if ( trim( $error ) != '' ) {
            $msg .= ": $error";
        } elseif ( $db ) {
            $error = $this->db->getServer();
        }

        parent::__construct( $db, $msg );
        $this->error = $error;
    }

    function useOutputPage() {
        // Not likely to work
        return false;
    }

    function msg( $key, $fallback /*[, params...] */ ) {
        $args = array_slice( func_get_args(), 2 );

        if ( $this->useMessageCache() ) {
            return wfMessage( $key, $args )->useDatabase( false )->text();
        } else {
            return wfMsgReplaceArgs( $fallback, $args );
        }
    }

    function isLoggable() {
        // Don't send to the exception log, already in dberror log
        return false;
    }

    function getHTML() {
        global $wgShowDBErrorBacktrace, $wgShowHostnames, $wgShowSQLErrors;

        $sorry = htmlspecialchars( $this->msg(
            'dberr-problems',
            'Sorry! This site is experiencing technical difficulties.'
        ) );
        $again = htmlspecialchars( $this->msg(
            'dberr-again',
            'Try waiting a few minutes and reloading.'
        ) );

        if ( $wgShowHostnames || $wgShowSQLErrors ) {
            $info = str_replace(
                '$1', Html::element( 'span', array( 'dir' => 'ltr' ), $this->error ),
                htmlspecialchars( $this->msg( 'dberr-info', '(Cannot contact the database server: $1)' ) )
            );
        } else {
            $info = htmlspecialchars( $this->msg(
                'dberr-info-hidden',
                '(Cannot contact the database server)'
            ) );
        }

        # No database access
        MessageCache::singleton()->disable();

        $html = "<h1>$sorry</h1><p>$again</p><p><small>$info</small></p>";

        if ( $wgShowDBErrorBacktrace ) {
            $html .= '<p>Backtrace:</p><pre>' . htmlspecialchars( $this->getTraceAsString() ) . '</pre>';
        }

        $html .= '<hr />';
        $html .= $this->searchForm();

        return $html;
    }

    protected function getTextContent() {
        global $wgShowHostnames, $wgShowSQLErrors;

        if ( $wgShowHostnames || $wgShowSQLErrors ) {
            return $this->getMessage();
        } else {
            return 'DB connection error';
        }
    }

    public function reportHTML() {
        global $wgUseFileCache;

        // Check whether we can serve a file-cached copy of the page with the error underneath
        if ( $wgUseFileCache ) {
            try {
                $cache = $this->fileCachedPage();
                // Cached version on file system?
                if ( $cache !== null ) {
                    // Hack: extend the body for error messages
                    $cache = str_replace( array( '</html>', '</body>' ), '', $cache );
                    // Add cache notice...
                    $cache .= '<div style="border:1px solid #ffd0d0;padding:1em;">' .
                        htmlspecialchars( $this->msg( 'dberr-cachederror',
                            'This is a cached copy of the requested page, and may not be up to date.' ) ) .
                        '</div>';

                    // Output cached page with notices on bottom and re-close body
                    echo "{$cache}<hr />{$this->getHTML()}</body></html>";

                    return;
                }
            } catch ( MWException $e ) {
                // Do nothing, just use the default page
            }
        }

        // We can't, cough and die in the usual fashion
        parent::reportHTML();
    }

    function searchForm() {
        global $wgSitename, $wgCanonicalServer, $wgRequest;

        $usegoogle = htmlspecialchars( $this->msg(
            'dberr-usegoogle',
            'You can try searching via Google in the meantime.'
        ) );
        $outofdate = htmlspecialchars( $this->msg(
            'dberr-outofdate',
            'Note that their indexes of our content may be out of date.'
        ) );
        $googlesearch = htmlspecialchars( $this->msg( 'searchbutton', 'Search' ) );

        $search = htmlspecialchars( $wgRequest->getVal( 'search' ) );

        $server = htmlspecialchars( $wgCanonicalServer );
        $sitename = htmlspecialchars( $wgSitename );

        $trygoogle = <<<EOT
<div style="margin: 1.5em">$usegoogle<br />
<small>$outofdate</small>
</div>
<form method="get" action="//www.google.com/search" id="googlesearch">
    <input type="hidden" name="domains" value="$server" />
    <input type="hidden" name="num" value="50" />
    <input type="hidden" name="ie" value="UTF-8" />
    <input type="hidden" name="oe" value="UTF-8" />

    <input type="text" name="q" size="31" maxlength="255" value="$search" />
    <input type="submit" name="btnG" value="$googlesearch" />
    <p>
        <label><input type="radio" name="sitesearch" value="$server" checked="checked" />$sitename</label>
        <label><input type="radio" name="sitesearch" value="" />WWW</label>
    </p>
</form>
EOT;

        return $trygoogle;
    }

    private function fileCachedPage() {
        $context = RequestContext::getMain();

        if ( $context->getOutput()->isDisabled() ) {
            // Done already?
            return '';
        }

        if ( $context->getTitle() ) {
            // Use the main context's title if we managed to set it
            $t = $context->getTitle()->getPrefixedDBkey();
        } else {
            // Fallback to the raw title URL param. We can't use the Title
            // class is it may hit the interwiki table and give a DB error.
            // We may get a cache miss due to not sanitizing the title though.
            $t = str_replace( ' ', '_', $context->getRequest()->getVal( 'title' ) );
            if ( $t == '' ) { // fallback to main page
                $t = Title::newFromText(
                    $this->msg( 'mainpage', 'Main Page' ) )->getPrefixedDBkey();
            }
        }

        $cache = new HTMLFileCache( $t, 'view' );
        if ( $cache->isCached() ) {
            return $cache->fetchText();
        } else {
            return '';
        }
    }
}

class DBQueryError extends DBExpectedError {
    public $error, $errno, $sql, $fname;

    function __construct( DatabaseBase $db, $error, $errno, $sql, $fname ) {
        $message = "A database error has occurred. Did you forget to run " .
            "maintenance/update.php after upgrading?  See: " .
            "https://www.mediawiki.org/wiki/Manual:Upgrading#Run_the_update_script\n" .
            "Query: $sql\n" .
            "Function: $fname\n" .
            "Error: $errno $error\n";
        parent::__construct( $db, $message );

        $this->error = $error;
        $this->errno = $errno;
        $this->sql = $sql;
        $this->fname = $fname;
    }

    function getPageTitle() {
        return $this->msg( 'databaseerror', 'Database error' );
    }

    protected function getHTMLContent() {
        $key = 'databaseerror-text';
        $s = Html::element( 'p', array(), $this->msg( $key, $this->getFallbackMessage( $key ) ) );

        $details = $this->getTechnicalDetails();
        if ( $details ) {
            $s .= '<ul>';
            foreach ( $details as $key => $detail ) {
                $s .= str_replace(
                    '$1', call_user_func_array( 'Html::element', $detail ),
                    Html::element( 'li', array(),
                        $this->msg( $key, $this->getFallbackMessage( $key ) )
                    )
                );
            }
            $s .= '</ul>';
        }

        return $s;
    }

    protected function getTextContent() {
        $key = 'databaseerror-textcl';
        $s = $this->msg( $key, $this->getFallbackMessage( $key ) ) . "\n";

        foreach ( $this->getTechnicalDetails() as $key => $detail ) {
            $s .= $this->msg( $key, $this->getFallbackMessage( $key ), $detail[2] ) . "\n";
        }

        return $s;
    }

    protected function getTechnicalDetails() {
        global $wgShowHostnames, $wgShowSQLErrors;

        $attribs = array( 'dir' => 'ltr' );
        $details = array();

        if ( $wgShowSQLErrors ) {
            $details['databaseerror-query'] = array(
                'div', array( 'class' => 'mw-code' ) + $attribs, $this->sql );
        }

        if ( $wgShowHostnames || $wgShowSQLErrors ) {
            $errorMessage = $this->errno . ' ' . $this->error;
            $details['databaseerror-function'] = array( 'code', $attribs, $this->fname );
            $details['databaseerror-error'] = array( 'samp', $attribs, $errorMessage );
        }

        return $details;
    }

    private function getFallbackMessage( $key ) {
        $messages = array(
            'databaseerror-text' => 'A database query error has occurred.
This may indicate a bug in the software.',
            'databaseerror-textcl' => 'A database query error has occurred.',
            'databaseerror-query' => 'Query: $1',
            'databaseerror-function' => 'Function: $1',
            'databaseerror-error' => 'Error: $1',
        );

        return $messages[$key];
    }
}

class DBUnexpectedError extends DBError {
}