New maintenance script to clean up rows with invalid DB keys
authorThis, that and the other <at.light@live.com.au>
Fri, 10 Mar 2017 13:27:27 +0000 (00:27 +1100)
committerThis, that and the other <at.light@live.com.au>
Fri, 10 Mar 2017 13:27:27 +0000 (00:27 +1100)
The TitleValue constructor, used by the link cache among other things,
throws an exception for DB keys which do not satisfy a simple sanity test
(starting or ending with _, or containing a space, tab, CR or LF
character). This has broken certain special pages on a number of WMF sites;
see T99736, T146778 and T155091.

The new cleanupInvalidDbKeys.php script allows these bogus entries to be
removed from the DB, making sure these exceptions won't be thrown in the
future. It cleans the title columns of the page, archive, redirect,
logging, category, protected_titles, recentchanges, watchlist, pagelinks,
templatelinks, and categorylinks tables.

The script doesn't support batching; most wikis should have fewer than 500
broken entries in each table. If need be, the script can be run several
times.

To make the LIKE queries work properly I had to fix the broken escaping
behaviour of Database::buildLike() -- previously it had a habit of double-
escaping things. Now an ESCAPE clause is added to change the escape
character from the problematic default backslash, and tests are added to
cover the changes.

Bug: T155091
Change-Id: I908e795e884e35be91852c0eaf056d6acfda31d8

autoload.php
includes/libs/rdbms/database/Database.php
includes/libs/rdbms/database/DatabaseMssql.php
includes/libs/rdbms/database/DatabaseMysqlBase.php
includes/libs/rdbms/database/DatabaseSqlite.php
maintenance/cleanupInvalidDbKeys.php [new file with mode: 0644]
tests/phpunit/includes/db/DatabaseSQLTest.php

index 0f79323..c333285 100644 (file)
@@ -252,6 +252,7 @@ $wgAutoloadLocalClasses = [
        'CleanupAncientTables' => __DIR__ . '/maintenance/cleanupAncientTables.php',
        'CleanupBlocks' => __DIR__ . '/maintenance/cleanupBlocks.php',
        'CleanupEmptyCategories' => __DIR__ . '/maintenance/cleanupEmptyCategories.php',
+       'CleanupInvalidDbKeys' => __DIR__ . '/maintenance/cleanupInvalidDbKeys.php',
        'CleanupPreferences' => __DIR__ . '/maintenance/cleanupPreferences.php',
        'CleanupRemovedModules' => __DIR__ . '/maintenance/cleanupRemovedModules.php',
        'CleanupSpam' => __DIR__ . '/maintenance/cleanupSpam.php',
index e807bc8..13295cd 100644 (file)
@@ -2002,8 +2002,10 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
         * @param string $s
         * @return string
         */
-       protected function escapeLikeInternal( $s ) {
-               return addcslashes( $s, '\%_' );
+       protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
+               return str_replace( [ $escapeChar, '%', '_' ],
+                       [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_" ],
+                       $s );
        }
 
        public function buildLike() {
@@ -2015,15 +2017,21 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 
                $s = '';
 
+               // We use ` instead of \ as the default LIKE escape character, since addQuotes()
+               // may escape backslashes, creating problems of double escaping. The `
+               // character has good cross-DBMS compatibility, avoiding special operators
+               // in MS SQL like ^ and %
+               $escapeChar = '`';
+
                foreach ( $params as $value ) {
                        if ( $value instanceof LikeMatch ) {
                                $s .= $value->toString();
                        } else {
-                               $s .= $this->escapeLikeInternal( $value );
+                               $s .= $this->escapeLikeInternal( $value, $escapeChar );
                        }
                }
 
-               return " LIKE {$this->addQuotes( $s )} ";
+               return ' LIKE ' . $this->addQuotes( $s ) . ' ESCAPE ' . $this->addQuotes( $escapeChar ) . ' ';
        }
 
        public function anyChar() {
index 75ddc9d..5f740b9 100644 (file)
@@ -1109,27 +1109,11 @@ class DatabaseMssql extends Database {
         * @param string $s
         * @return string
         */
-       protected function escapeLikeInternal( $s ) {
-               return addcslashes( $s, '\%_[]^' );
-       }
-
-       /**
-        * MS SQL requires specifying the escape character used in a LIKE query
-        * or using Square brackets to surround characters that are to be escaped
-        * https://msdn.microsoft.com/en-us/library/ms179859.aspx
-        * Here we take the Specify-Escape-Character approach since it's less
-        * invasive, renders a query that is closer to other DB's and better at
-        * handling square bracket escaping
-        *
-        * @return string Fully built LIKE statement
-        */
-       public function buildLike() {
-               $params = func_get_args();
-               if ( count( $params ) > 0 && is_array( $params[0] ) ) {
-                       $params = $params[0];
-               }
-
-               return parent::buildLike( $params ) . " ESCAPE '\' ";
+       protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
+               return str_replace( [ $escapeChar, '%', '_', '[', ']', '^' ],
+                       [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_",
+                               "{$escapeChar}[", "{$escapeChar}]", "{$escapeChar}^" ],
+                       $s );
        }
 
        /**
index e900027..988a5d6 100644 (file)
@@ -528,9 +528,11 @@ abstract class DatabaseMysqlBase extends Database {
                        return true; // already known to exist and won't show in SHOW TABLES anyway
                }
 
-               $encLike = $this->buildLike( $table );
+               // We can't use buildLike() here, because it specifies an escape character
+               // other than the backslash, which is the only one supported by SHOW TABLES
+               $encLike = $this->escapeLikeInternal( $table, '\\' );
 
-               return $this->query( "SHOW TABLES $encLike", $fname )->numRows() > 0;
+               return $this->query( "SHOW TABLES LIKE '$encLike'", $fname )->numRows() > 0;
        }
 
        /**
index 090ce8e..e2b07ac 100644 (file)
@@ -804,18 +804,6 @@ class DatabaseSqlite extends Database {
                }
        }
 
-       /**
-        * @return string
-        */
-       function buildLike() {
-               $params = func_get_args();
-               if ( count( $params ) > 0 && is_array( $params[0] ) ) {
-                       $params = $params[0];
-               }
-
-               return parent::buildLike( $params ) . "ESCAPE '\' ";
-       }
-
        /**
         * @param string $field Field or column to cast
         * @return string
diff --git a/maintenance/cleanupInvalidDbKeys.php b/maintenance/cleanupInvalidDbKeys.php
new file mode 100644 (file)
index 0000000..423686e
--- /dev/null
@@ -0,0 +1,310 @@
+<?php
+/**
+ * Cleans up invalid titles in various tables.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ * @ingroup Maintenance
+ */
+
+require_once __DIR__ . '/Maintenance.php';
+
+/**
+ * Maintenance script that cleans up invalid titles in various tables.
+ *
+ * @since 1.29
+ * @ingroup Maintenance
+ */
+class CleanupInvalidDbKeys extends Maintenance {
+       /** @var array List of tables to clean up, and the field prefix for that table */
+       protected static $tables = [
+               // Data tables
+               [ 'page', 'page' ],
+               [ 'redirect', 'rd', 'idField' => 'rd_from' ],
+               [ 'archive', 'ar' ],
+               [ 'logging', 'log' ],
+               [ 'protected_titles', 'pt', 'idField' => 0 ],
+               [ 'category', 'cat', 'nsField' => 14 ],
+               [ 'recentchanges', 'rc' ],
+               [ 'watchlist', 'wl' ],
+               // The querycache tables' qc(c)_title and qcc_titletwo may contain titles,
+               // but also usernames or other things like that, so we leave them alone
+
+               // Links tables
+               [ 'pagelinks', 'pl', 'idField' => 'pl_from' ],
+               [ 'templatelinks', 'tl', 'idField' => 'tl_from' ],
+               [ 'categorylinks', 'cl', 'idField' => 'cl_from', 'nsField' => 14, 'titleField' => 'cl_to' ],
+       ];
+
+       public function __construct() {
+               parent::__construct();
+               $this->addDescription( <<<'TEXT'
+This script cleans up the title fields in various tables to remove entries that
+will be rejected by the constructor of TitleValue.  This constructor throws an
+exception when invalid data is encountered, which will not normally occur on
+regular page views, but can happen on query special pages.
+
+The script targets titles matching the regular expression /^_|[ \r\n\t]|_$/.
+Because any foreign key relationships involving these titles will already be
+broken, the titles are corrected to a valid version or the rows are deleted
+entirely, depending on the table.
+
+Key progress output is printed to STDERR, while a full log of all entries that
+are deleted is sent to STDOUT. You are strongly advised to capture STDOUT into
+a file.
+TEXT
+               );
+               $this->addOption( 'fix', 'Actually clean up invalid titles. If this parameter is ' .
+                       'not specified, the script will report invalid titles but not clean them up.',
+                       false, false );
+               $this->addOption( 'table', 'The table(s) to process. This option can be specified ' .
+                       'more than once (e.g. -t category -t watchlist). If not specified, all available ' .
+                       'tables will be processed. Available tables are: ' .
+                       implode( ', ', array_column( static::$tables, 0 ) ), false, true, 't', true );
+
+               $this->setBatchSize( 500 );
+       }
+
+       public function execute() {
+               $tablesToProcess = $this->getOption( 'table' );
+               foreach ( static::$tables as $tableParams ) {
+                       if ( !$tablesToProcess || in_array( $tableParams[0], $tablesToProcess ) ) {
+                               $this->cleanupTable( $tableParams );
+                       }
+               }
+
+               $this->output( 'Done! Cleaned up invalid DB keys on ' . wfWikiID() . "!\n" );
+       }
+
+       /**
+        * Prints text to STDOUT, and STDERR if STDOUT was redirected to a file.
+        * Used for progress reporting.
+        *
+        * @param string $str Text to write to both places
+        * @param string|null $channel Ignored
+        */
+       protected function output( $str, $channel = null ) {
+               // Make it easier to find progress lines in the STDOUT log
+               if ( trim( $str ) ) {
+                       fwrite( STDOUT, '*** ' );
+               }
+               fwrite( STDERR, $str );
+       }
+
+       /**
+        * Prints text to STDOUT. Used for logging output.
+        *
+        * @param string $str Text to write
+        */
+       protected function writeToReport( $str ) {
+               fwrite( STDOUT, $str );
+       }
+
+       /**
+        * Identifies, and optionally cleans up, invalid titles.
+        *
+        * @param array $tableParams A child array of self::$tables
+        */
+       protected function cleanupTable( $tableParams ) {
+               $table = $tableParams[0];
+               $prefix = $tableParams[1];
+               $idField = isset( $tableParams['idField'] ) ?
+                       $tableParams['idField'] :
+                       "{$prefix}_id";
+               $nsField = isset( $tableParams['nsField'] ) ?
+                       $tableParams['nsField'] :
+                       "{$prefix}_namespace";
+               $titleField = isset( $tableParams['titleField'] ) ?
+                       $tableParams['titleField'] :
+                       "{$prefix}_title";
+
+               $this->output( "Looking for invalid $titleField entries in $table...\n" );
+
+               // Do all the select queries on the replicas, as they are slow (they use
+               // unanchored LIKEs). Naturally this could cause problems if rows are
+               // modified after selecting and before deleting/updating, but working on
+               // the hypothesis that invalid rows will be old and in all likelihood
+               // unreferenced, we should be fine to do it like this.
+               $dbr = $this->getDB( DB_REPLICA, 'vslow' );
+
+               // Find all TitleValue-invalid titles.
+               $percent = $dbr->anyString(); // DBMS-agnostic equivalent of '%' LIKE wildcard
+               $res = $dbr->select(
+                       $table,
+                       [
+                               'id' => $idField,
+                               'ns' => $nsField,
+                               'title' => $titleField,
+                       ],
+                       // The REGEXP operator is not cross-DBMS, so we have to use lots of LIKEs
+                       [ $dbr->makeList( [
+                               $titleField . $dbr->buildLike( $percent, ' ', $percent ),
+                               $titleField . $dbr->buildLike( $percent, '\r', $percent ),
+                               $titleField . $dbr->buildLike( $percent, '\n', $percent ),
+                               $titleField . $dbr->buildLike( $percent, '\t', $percent ),
+                               $titleField . $dbr->buildLike( '_', $percent ),
+                               $titleField . $dbr->buildLike( $percent, '_' ),
+                       ], LIST_OR ) ],
+                       __METHOD__,
+                       [ 'LIMIT' => $this->mBatchSize ]
+               );
+
+               $this->output( "Number of invalid rows: " . $res->numRows() . "\n" );
+               if ( !$res->numRows() ) {
+                       $this->output( "\n" );
+                       return;
+               }
+
+               // Write a table of titles to the report file. Also keep a list of the found
+               // IDs, as we might need it later for DB updates
+               $this->writeToReport( sprintf( "%10s |  ns | dbkey\n", $idField ) );
+               $ids = [];
+               foreach ( $res as $row ) {
+                       $this->writeToReport( sprintf( "%10d | %3d | %s\n", $row->id, $row->ns, $row->title ) );
+                       $ids[] = $row->id;
+               }
+
+               // If we're doing a dry run, output the new titles we would use for the UPDATE
+               // queries (if relevant), and finish
+               if ( !$this->hasOption( 'fix' ) ) {
+                       if ( $table === 'logging' || $table === 'archive' ) {
+                               $this->writeToReport( "The following updates would be run with the --fix flag:\n" );
+                               foreach ( $res as $row ) {
+                                       $newTitle = self::makeValidTitle( $row->title );
+                                       $this->writeToReport(
+                                               "$idField={$row->id}: update '{$row->title}' to '$newTitle'\n" );
+                               }
+                       }
+
+                       if ( $table !== 'page' && $table !== 'redirect' ) {
+                               $this->output( "Run with --fix to clean up these rows\n" );
+                       }
+                       $this->output( "\n" );
+                       return;
+               }
+
+               // Fix the bad data, using different logic for the various tables
+               $dbw = $this->getDB( DB_MASTER );
+               switch ( $table ) {
+                       case 'page':
+                       case 'redirect':
+                               // This shouldn't happen on production wikis, and we already have a script
+                               // to handle 'page' rows anyway, so just notify the user and let them decide
+                               // what to do next.
+                               $this->output( <<<TEXT
+IMPORTANT: This script does not fix invalid entries in the $table table.
+Consider repairing these rows, and rows in related tables, by hand.
+You may like to run, or borrow logic from, the cleanupTitles.php script.
+
+TEXT
+                               );
+                               break;
+
+                       case 'archive':
+                       case 'logging':
+                               // Rename the title to a corrected equivalent. Any foreign key relationships
+                               // to the page_title field are already broken, so this will just make sure
+                               // users can still access the log entries/deleted revisions from the interface
+                               // using a valid page title.
+                               $this->output(
+                                       "Updating these rows, setting $titleField to the closest valid DB key...\n" );
+                               $affectedRowCount = 0;
+                               foreach ( $res as $row ) {
+                                       $newTitle = self::makeValidTitle( $row->title );
+                                       $this->writeToReport(
+                                               "$idField={$row->id}: updating '{$row->title}' to '$newTitle'\n" );
+
+                                       $dbw->update( $table,
+                                               [ $titleField => $newTitle ],
+                                               [ $idField => $row->id ],
+                                               __METHOD__ );
+                                       $affectedRowCount += $dbw->affectedRows();
+                               }
+                               wfWaitForSlaves();
+                               $this->output( "Updated $affectedRowCount rows on $table.\n" );
+
+                               break;
+
+                       case 'recentchanges':
+                       case 'watchlist':
+                       case 'category':
+                               // Since these broken titles can't exist, there's really nothing to watch,
+                               // nothing can be categorised in them, and they can't have been changed
+                               // recently, so we can just remove these rows.
+                               $this->output( "Deleting invalid $table rows...\n" );
+                               $dbw->delete( $table, [ $idField => $ids ], __METHOD__ );
+                               wfWaitForSlaves();
+                               $this->output( 'Deleted ' . $dbw->affectedRows() . " rows from $table.\n" );
+                               break;
+
+                       case 'protected_titles':
+                               // Since these broken titles can't exist, there's really nothing to protect,
+                               // so we can just remove these rows. Made more complicated by this table
+                               // not having an ID field
+                               $this->output( "Deleting invalid $table rows...\n" );
+                               $affectedRowCount = 0;
+                               foreach ( $res as $row ) {
+                                       $dbw->delete( $table,
+                                               [ $nsField => $row->ns, $titleField => $row->title ],
+                                               __METHOD__ );
+                                       $affectedRowCount += $dbw->affectedRows();
+                               }
+                               wfWaitForSlaves();
+                               $this->output( "Deleted $affectedRowCount rows from $table.\n" );
+                               break;
+
+                       case 'pagelinks':
+                       case 'templatelinks':
+                       case 'categorylinks':
+                               // Update links tables for each page where these bogus links are supposedly
+                               // located. If the invalid rows don't go away after these jobs go through,
+                               // they're probably being added by a buggy hook.
+                               $this->output( "Queueing link update jobs for the pages in $idField...\n" );
+                               foreach ( $res as $row ) {
+                                       $wp = WikiPage::newFromID( $row->id );
+                                       if ( $wp ) {
+                                               RefreshLinks::fixLinksFromArticle( $row->id );
+                                       } else {
+                                               // This link entry points to a nonexistent page, so just get rid of it
+                                               $dbw->delete( $table,
+                                                       [ $idField => $row->id, $nsField => $row->ns, $titleField => $row->title ],
+                                                       __METHOD__ );
+                                       }
+                               }
+                               wfWaitForSlaves();
+                               $this->output( "Link update jobs have been added to the job queue.\n" );
+                               break;
+               }
+
+               $this->output( "\n" );
+               return;
+       }
+
+       /**
+        * Fix possible validation issues in the given title (DB key).
+        *
+        * @param string $invalidTitle
+        * @return string
+        */
+       protected static function makeValidTitle( $invalidTitle ) {
+               return strtr( trim( $invalidTitle, '_' ),
+                       [ ' ' => '_', "\r" => '', "\n" => '', "\t" => '_' ] );
+       }
+}
+
+$maintClass = 'CleanupInvalidDbKeys';
+require_once RUN_MAINTENANCE_IF_MAIN;
index 57754bc..b6088ff 100644 (file)
@@ -660,19 +660,31 @@ class DatabaseSQLTest extends MediaWikiTestCase {
                return [
                        [
                                'text',
-                               "LIKE 'text'"
+                               "LIKE 'text' ESCAPE '`'"
                        ],
                        [
                                [ 'text', new LikeMatch( '%' ) ],
-                               "LIKE 'text%'"
+                               "LIKE 'text%' ESCAPE '`'"
                        ],
                        [
                                [ 'text', new LikeMatch( '%' ), 'text2' ],
-                               "LIKE 'text%text2'"
+                               "LIKE 'text%text2' ESCAPE '`'"
                        ],
                        [
                                [ 'text', new LikeMatch( '_' ) ],
-                               "LIKE 'text_'"
+                               "LIKE 'text_' ESCAPE '`'"
+                       ],
+                       [
+                               'more_text',
+                               "LIKE 'more`_text' ESCAPE '`'"
+                       ],
+                       [
+                               [ 'C:\\Windows\\', new LikeMatch( '%' ) ],
+                               "LIKE 'C:\\Windows\\%' ESCAPE '`'"
+                       ],
+                       [
+                               [ 'accent`_test`', new LikeMatch( '%' ) ],
+                               "LIKE 'accent```_test``%' ESCAPE '`'"
                        ],
                ];
        }