includes/db/Database.php

   1 <?php
   2 /**
   3  * @defgroup Database Database
   4  *
   5  * @file
   6  * @ingroup Database
   7  * This file deals with database interface functions
   8  * and query specifics/optimisations
   9  */
  10
  11 /** Number of times to re-try an operation in case of deadlock */
  12 define( 'DEADLOCK_TRIES', 4 );
  13 /** Minimum time to wait before retry, in microseconds */
  14 define( 'DEADLOCK_DELAY_MIN', 500000 );
  15 /** Maximum time to wait before retry */
  16 define( 'DEADLOCK_DELAY_MAX', 1500000 );
  17
  18 /**
  19  * Base interface for all DBMS-specific code. At a bare minimum, all of the
  20  * following must be implemented to support MediaWiki
  21  *
  22  * @file
  23  * @ingroup Database
  24  */
  25 interface DatabaseType {
  26         /**
  27          * Get the type of the DBMS, as it appears in $wgDBtype.
  28          *
  29          * @return string
  30          */
  31         public function getType();
  32
  33         /**
  34          * Open a connection to the database. Usually aborts on failure
  35          *
  36          * @param $server String: database server host
  37          * @param $user String: database user name
  38          * @param $password String: database user password
  39          * @param $dbName String: database name
  40          * @return bool
  41          * @throws DBConnectionError
  42          */
  43         public function open( $server, $user, $password, $dbName );
  44
  45         /**
  46          * The DBMS-dependent part of query()
  47          * @todo Fixme: Make this private someday
  48          *
  49          * @param  $sql String: SQL query.
  50          * @return Result object to feed to fetchObject, fetchRow, ...; or false on failure
  51          * @private
  52          */
  53         /*private*/ function doQuery( $sql );
  54
  55         /**
  56          * Fetch the next row from the given result object, in object form.
  57          * Fields can be retrieved with $row->fieldname, with fields acting like
  58          * member variables.
  59          *
  60          * @param $res SQL result object as returned from DatabaseBase::query(), etc.
  61          * @return Row object
  62          * @throws DBUnexpectedError Thrown if the database returns an error
  63          */
  64         public function fetchObject( $res );
  65
  66         /**
  67          * Fetch the next row from the given result object, in associative array
  68          * form.  Fields are retrieved with $row['fieldname'].
  69          *
  70          * @param $res SQL result object as returned from DatabaseBase::query(), etc.
  71          * @return Row object
  72          * @throws DBUnexpectedError Thrown if the database returns an error
  73          */
  74         public function fetchRow( $res );
  75
  76         /**
  77          * Get the number of rows in a result object
  78          *
  79          * @param $res Mixed: A SQL result
  80          * @return int
  81          */
  82         public function numRows( $res );
  83
  84         /**
  85          * Get the number of fields in a result object
  86          * @see http://www.php.net/mysql_num_fields
  87          *
  88          * @param $res Mixed: A SQL result
  89          * @return int
  90          */
  91         public function numFields( $res );
  92
  93         /**
  94          * Get a field name in a result object
  95          * @see http://www.php.net/mysql_field_name
  96          *
  97          * @param $res Mixed: A SQL result
  98          * @param $n Integer
  99          * @return string
 100          */
 101         public function fieldName( $res, $n );
 102
 103         /**
 104          * Get the inserted value of an auto-increment row
 105          *
 106          * The value inserted should be fetched from nextSequenceValue()
 107          *
 108          * Example:
 109          * $id = $dbw->nextSequenceValue('page_page_id_seq');
 110          * $dbw->insert('page',array('page_id' => $id));
 111          * $id = $dbw->insertId();
 112          *
 113          * @return int
 114          */
 115         public function insertId();
 116
 117         /**
 118          * Change the position of the cursor in a result object
 119          * @see http://www.php.net/mysql_data_seek
 120          *
 121          * @param $res Mixed: A SQL result
 122          * @param $row Mixed: Either MySQL row or ResultWrapper
 123          */
 124         public function dataSeek( $res, $row );
 125
 126         /**
 127          * Get the last error number
 128          * @see http://www.php.net/mysql_errno
 129          *
 130          * @return int
 131          */
 132         public function lastErrno();
 133
 134         /**
 135          * Get a description of the last error
 136          * @see http://www.php.net/mysql_error
 137          *
 138          * @return string
 139          */
 140         public function lastError();
 141
 142         /**
 143          * mysql_fetch_field() wrapper
 144          * Returns false if the field doesn't exist
 145          *
 146          * @param $table string: table name
 147          * @param $field string: field name
 148          */
 149         public function fieldInfo( $table, $field );
 150
 151         /**
 152          * Get information about an index into an object
 153          * @param $table string: Table name
 154          * @param $index string: Index name
 155          * @param $fname string: Calling function name
 156          * @return Mixed: Database-specific index description class or false if the index does not exist
 157          */
 158         function indexInfo( $table, $index, $fname = 'Database::indexInfo' );
 159
 160         /**
 161          * Get the number of rows affected by the last write query
 162          * @see http://www.php.net/mysql_affected_rows
 163          *
 164          * @return int
 165          */
 166         public function affectedRows();
 167
 168         /**
 169          * Wrapper for addslashes()
 170          *
 171          * @param $s string: to be slashed.
 172          * @return string: slashed string.
 173          */
 174         public function strencode( $s );
 175
 176         /**
 177          * Returns a wikitext link to the DB's website, e.g.,
 178          *     return "[http://www.mysql.com/ MySQL]";
 179          * Should at least contain plain text, if for some reason
 180          * your database has no website.
 181          *
 182          * @return string: wikitext of a link to the server software's web site
 183          */
 184         public static function getSoftwareLink();
 185
 186         /**
 187          * A string describing the current software version, like from
 188          * mysql_get_server_info().
 189          *
 190          * @return string: Version information from the database server.
 191          */
 192         public function getServerVersion();
 193
 194         /**
 195          * A string describing the current software version, and possibly
 196          * other details in a user-friendly way.  Will be listed on Special:Version, etc.
 197          * Use getServerVersion() to get machine-friendly information.
 198          *
 199          * @return string: Version information from the database server
 200          */
 201         public function getServerInfo();
 202 }
 203
 204 /**
 205  * Database abstraction object
 206  * @ingroup Database
 207  */
 208 abstract class DatabaseBase implements DatabaseType {
 209
 210 # ------------------------------------------------------------------------------
 211 # Variables
 212 # ------------------------------------------------------------------------------
 213
 214         protected $mLastQuery = '';
 215         protected $mDoneWrites = false;
 216         protected $mPHPError = false;
 217
 218         protected $mServer, $mUser, $mPassword, $mConn = null, $mDBname;
 219         protected $mOpened = false;
 220
 221         protected $mTablePrefix;
 222         protected $mFlags;
 223         protected $mTrxLevel = 0;
 224         protected $mErrorCount = 0;
 225         protected $mLBInfo = array();
 226         protected $mFakeSlaveLag = null, $mFakeMaster = false;
 227         protected $mDefaultBigSelects = null;
 228
 229 # ------------------------------------------------------------------------------
 230 # Accessors
 231 # ------------------------------------------------------------------------------
 232         # These optionally set a variable and return the previous state
 233
 234         /**
 235          * A string describing the current software version, and possibly
 236          * other details in a user-friendly way.  Will be listed on Special:Version, etc.
 237          * Use getServerVersion() to get machine-friendly information.
 238          *
 239          * @return string: Version information from the database server
 240          */
 241         public function getServerInfo() {
 242                 return $this->getServerVersion();
 243         }
 244
 245         /**
 246          * Boolean, controls output of large amounts of debug information
 247          */
 248         function debug( $debug = null ) {
 249                 return wfSetBit( $this->mFlags, DBO_DEBUG, $debug );
 250         }
 251
 252         /**
 253          * Turns buffering of SQL result sets on (true) or off (false).
 254          * Default is "on" and it should not be changed without good reasons.
 255          */
 256         function bufferResults( $buffer = null ) {
 257                 if ( is_null( $buffer ) ) {
 258                         return !(bool)( $this->mFlags & DBO_NOBUFFER );
 259                 } else {
 260                         return !wfSetBit( $this->mFlags, DBO_NOBUFFER, !$buffer );
 261                 }
 262         }
 263
 264         /**
 265          * Turns on (false) or off (true) the automatic generation and sending
 266          * of a "we're sorry, but there has been a database error" page on
 267          * database errors. Default is on (false). When turned off, the
 268          * code should use lastErrno() and lastError() to handle the
 269          * situation as appropriate.
 270          */
 271         function ignoreErrors( $ignoreErrors = null ) {
 272                 return wfSetBit( $this->mFlags, DBO_IGNORE, $ignoreErrors );
 273         }
 274
 275         /**
 276          * The current depth of nested transactions
 277          * @param $level Integer: , default NULL.
 278          */
 279         function trxLevel( $level = null ) {
 280                 return wfSetVar( $this->mTrxLevel, $level );
 281         }
 282
 283         /**
 284          * Number of errors logged, only useful when errors are ignored
 285          */
 286         function errorCount( $count = null ) {
 287                 return wfSetVar( $this->mErrorCount, $count );
 288         }
 289
 290         function tablePrefix( $prefix = null ) {
 291                 return wfSetVar( $this->mTablePrefix, $prefix );
 292         }
 293
 294         /**
 295          * Properties passed down from the server info array of the load balancer
 296          */
 297         function getLBInfo( $name = null ) {
 298                 if ( is_null( $name ) ) {
 299                         return $this->mLBInfo;
 300                 } else {
 301                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 302                                 return $this->mLBInfo[$name];
 303                         } else {
 304                                 return null;
 305                         }
 306                 }
 307         }
 308
 309         function setLBInfo( $name, $value = null ) {
 310                 if ( is_null( $value ) ) {
 311                         $this->mLBInfo = $name;
 312                 } else {
 313                         $this->mLBInfo[$name] = $value;
 314                 }
 315         }
 316
 317         /**
 318          * Set lag time in seconds for a fake slave
 319          */
 320         function setFakeSlaveLag( $lag ) {
 321                 $this->mFakeSlaveLag = $lag;
 322         }
 323
 324         /**
 325          * Make this connection a fake master
 326          */
 327         function setFakeMaster( $enabled = true ) {
 328                 $this->mFakeMaster = $enabled;
 329         }
 330
 331         /**
 332          * Returns true if this database supports (and uses) cascading deletes
 333          */
 334         function cascadingDeletes() {
 335                 return false;
 336         }
 337
 338         /**
 339          * Returns true if this database supports (and uses) triggers (e.g. on the page table)
 340          */
 341         function cleanupTriggers() {
 342                 return false;
 343         }
 344
 345         /**
 346          * Returns true if this database is strict about what can be put into an IP field.
 347          * Specifically, it uses a NULL value instead of an empty string.
 348          */
 349         function strictIPs() {
 350                 return false;
 351         }
 352
 353         /**
 354          * Returns true if this database uses timestamps rather than integers
 355         */
 356         function realTimestamps() {
 357                 return false;
 358         }
 359
 360         /**
 361          * Returns true if this database does an implicit sort when doing GROUP BY
 362          */
 363         function implicitGroupby() {
 364                 return true;
 365         }
 366
 367         /**
 368          * Returns true if this database does an implicit order by when the column has an index
 369          * For example: SELECT page_title FROM page LIMIT 1
 370          */
 371         function implicitOrderby() {
 372                 return true;
 373         }
 374
 375         /**
 376          * Returns true if this database requires that SELECT DISTINCT queries require that all
 377            ORDER BY expressions occur in the SELECT list per the SQL92 standard
 378          */
 379         function standardSelectDistinct() {
 380                 return true;
 381         }
 382
 383         /**
 384          * Returns true if this database can do a native search on IP columns
 385          * e.g. this works as expected: .. WHERE rc_ip = '127.42.12.102/32';
 386          */
 387         function searchableIPs() {
 388                 return false;
 389         }
 390
 391         /**
 392          * Returns true if this database can use functional indexes
 393          */
 394         function functionalIndexes() {
 395                 return false;
 396         }
 397
 398         /**
 399          * Return the last query that went through DatabaseBase::query()
 400          * @return String
 401          */
 402         function lastQuery() { return $this->mLastQuery; }
 403
 404
 405         /**
 406          * Returns true if the connection may have been used for write queries.
 407          * Should return true if unsure.
 408          */
 409         function doneWrites() { return $this->mDoneWrites; }
 410
 411         /**
 412          * Is a connection to the database open?
 413          * @return Boolean
 414          */
 415         function isOpen() { return $this->mOpened; }
 416
 417         /**
 418          * Set a flag for this connection
 419          *
 420          * @param $flag Integer: DBO_* constants from Defines.php:
 421          *   - DBO_DEBUG: output some debug info (same as debug())
 422          *   - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
 423          *   - DBO_IGNORE: ignore errors (same as ignoreErrors())
 424          *   - DBO_TRX: automatically start transactions
 425          *   - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
 426          *       and removes it in command line mode
 427          *   - DBO_PERSISTENT: use persistant database connection
 428          */
 429         function setFlag( $flag ) {
 430                 $this->mFlags |= $flag;
 431         }
 432
 433         /**
 434          * Clear a flag for this connection
 435          *
 436          * @param $flag: same as setFlag()'s $flag param
 437          */
 438         function clearFlag( $flag ) {
 439                 $this->mFlags &= ~$flag;
 440         }
 441
 442         /**
 443          * Returns a boolean whether the flag $flag is set for this connection
 444          *
 445          * @param $flag: same as setFlag()'s $flag param
 446          * @return Boolean
 447          */
 448         function getFlag( $flag ) {
 449                 return !!( $this->mFlags & $flag );
 450         }
 451
 452         /**
 453          * General read-only accessor
 454          */
 455         function getProperty( $name ) {
 456                 return $this->$name;
 457         }
 458
 459         function getWikiID() {
 460                 if ( $this->mTablePrefix ) {
 461                         return "{$this->mDBname}-{$this->mTablePrefix}";
 462                 } else {
 463                         return $this->mDBname;
 464                 }
 465         }
 466
 467         /**
 468          * Return a path to the DBMS-specific schema, otherwise default to tables.sql
 469          */
 470         public function getSchema() {
 471                 global $IP;
 472                 if ( file_exists( "$IP/maintenance/" . $this->getType() . "/tables.sql" ) ) {
 473                         return "$IP/maintenance/" . $this->getType() . "/tables.sql";
 474                 } else {
 475                         return "$IP/maintenance/tables.sql";
 476                 }
 477         }
 478
 479 # ------------------------------------------------------------------------------
 480 # Other functions
 481 # ------------------------------------------------------------------------------
 482
 483         /**
 484          * Constructor.
 485          * @param $server String: database server host
 486          * @param $user String: database user name
 487          * @param $password String: database user password
 488          * @param $dbName String: database name
 489          * @param $flags
 490          * @param $tablePrefix String: database table prefixes. By default use the prefix gave in LocalSettings.php
 491          */
 492         function __construct( $server = false, $user = false, $password = false, $dbName = false,
 493                 $flags = 0, $tablePrefix = 'get from global'
 494         ) {
 495                 global $wgOut, $wgDBprefix, $wgCommandLineMode;
 496
 497                 # Can't get a reference if it hasn't been set yet
 498                 if ( !isset( $wgOut ) ) {
 499                         $wgOut = null;
 500                 }
 501                 $this->mFlags = $flags;
 502
 503                 if ( $this->mFlags & DBO_DEFAULT ) {
 504                         if ( $wgCommandLineMode ) {
 505                                 $this->mFlags &= ~DBO_TRX;
 506                         } else {
 507                                 $this->mFlags |= DBO_TRX;
 508                         }
 509                 }
 510
 511                 /*
 512                 // Faster read-only access
 513                 if ( wfReadOnly() ) {
 514                         $this->mFlags |= DBO_PERSISTENT;
 515                         $this->mFlags &= ~DBO_TRX;
 516                 }*/
 517
 518                 /** Get the default table prefix*/
 519                 if ( $tablePrefix == 'get from global' ) {
 520                         $this->mTablePrefix = $wgDBprefix;
 521                 } else {
 522                         $this->mTablePrefix = $tablePrefix;
 523                 }
 524
 525                 if ( $server ) {
 526                         $this->open( $server, $user, $password, $dbName );
 527                 }
 528         }
 529
 530         /**
 531          * Same as new DatabaseMysql( ... ), kept for backward compatibility
 532          * @param $server String: database server host
 533          * @param $user String: database user name
 534          * @param $password String: database user password
 535          * @param $dbName String: database name
 536          * @param $flags
 537          */
 538         static function newFromParams( $server, $user, $password, $dbName, $flags = 0 ) {
 539                 wfDeprecated( __METHOD__ );
 540                 return new DatabaseMysql( $server, $user, $password, $dbName, $flags );
 541         }
 542
 543         protected function installErrorHandler() {
 544                 $this->mPHPError = false;
 545                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 546                 set_error_handler( array( $this, 'connectionErrorHandler' ) );
 547         }
 548
 549         protected function restoreErrorHandler() {
 550                 restore_error_handler();
 551                 if ( $this->htmlErrors !== false ) {
 552                         ini_set( 'html_errors', $this->htmlErrors );
 553                 }
 554                 if ( $this->mPHPError ) {
 555                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 556                         $error = preg_replace( '!^.*?:(.*)$!', '$1', $error );
 557                         return $error;
 558                 } else {
 559                         return false;
 560                 }
 561         }
 562
 563         protected function connectionErrorHandler( $errno,  $errstr ) {
 564                 $this->mPHPError = $errstr;
 565         }
 566
 567         /**
 568          * Closes a database connection.
 569          * if it is open : commits any open transactions
 570          *
 571          * @return Bool operation success. true if already closed.
 572          */
 573         function close() {
 574                 # Stub, should probably be overridden
 575                 return true;
 576         }
 577
 578         /**
 579          * @param $error String: fallback error message, used if none is given by DB
 580          */
 581         function reportConnectionError( $error = 'Unknown error' ) {
 582                 $myError = $this->lastError();
 583                 if ( $myError ) {
 584                         $error = $myError;
 585                 }
 586
 587                 # New method
 588                 throw new DBConnectionError( $this, $error );
 589         }
 590
 591         /**
 592          * Determine whether a query writes to the DB.
 593          * Should return true if unsure.
 594          */
 595         function isWriteQuery( $sql ) {
 596                 return !preg_match( '/^(?:SELECT|BEGIN|COMMIT|SET|SHOW|\(SELECT)\b/i', $sql );
 597         }
 598
 599         /**
 600          * Usually aborts on failure.  If errors are explicitly ignored, returns success.
 601          *
 602          * @param  $sql        String: SQL query
 603          * @param  $fname      String: Name of the calling function, for profiling/SHOW PROCESSLIST
 604          *     comment (you can use __METHOD__ or add some extra info)
 605          * @param  $tempIgnore Boolean:   Whether to avoid throwing an exception on errors...
 606          *     maybe best to catch the exception instead?
 607          * @return true for a successful write query, ResultWrapper object for a successful read query,
 608          *     or false on failure if $tempIgnore set
 609          * @throws DBQueryError Thrown when the database returns an error of any kind
 610          */
 611         public function query( $sql, $fname = '', $tempIgnore = false ) {
 612                 global $wgProfiler;
 613
 614                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 615                 if ( isset( $wgProfiler ) ) {
 616                         # generalizeSQL will probably cut down the query to reasonable
 617                         # logging size most of the time. The substr is really just a sanity check.
 618
 619                         # Who's been wasting my precious column space? -- TS
 620                         # $profName = 'query: ' . $fname . ' ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 621
 622                         if ( $isMaster ) {
 623                                 $queryProf = 'query-m: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 624                                 $totalProf = 'DatabaseBase::query-master';
 625                         } else {
 626                                 $queryProf = 'query: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 627                                 $totalProf = 'DatabaseBase::query';
 628                         }
 629
 630                         wfProfileIn( $totalProf );
 631                         wfProfileIn( $queryProf );
 632                 }
 633
 634                 $this->mLastQuery = $sql;
 635                 if ( !$this->mDoneWrites && $this->isWriteQuery( $sql ) ) {
 636                         // Set a flag indicating that writes have been done
 637                         wfDebug( __METHOD__ . ": Writes done: $sql\n" );
 638                         $this->mDoneWrites = true;
 639                 }
 640
 641                 # Add a comment for easy SHOW PROCESSLIST interpretation
 642                 # if ( $fname ) {
 643                         global $wgUser;
 644                         if ( is_object( $wgUser ) && $wgUser->mDataLoaded ) {
 645                                 $userName = $wgUser->getName();
 646                                 if ( mb_strlen( $userName ) > 15 ) {
 647                                         $userName = mb_substr( $userName, 0, 15 ) . '...';
 648                                 }
 649                                 $userName = str_replace( '/', '', $userName );
 650                         } else {
 651                                 $userName = '';
 652                         }
 653                         $commentedSql = preg_replace( '/\s/', " /* $fname $userName */ ", $sql, 1 );
 654                 # } else {
 655                 #       $commentedSql = $sql;
 656                 # }
 657
 658                 # If DBO_TRX is set, start a transaction
 659                 if ( ( $this->mFlags & DBO_TRX ) && !$this->trxLevel() &&
 660                         $sql != 'BEGIN' && $sql != 'COMMIT' && $sql != 'ROLLBACK' ) {
 661                         // avoid establishing transactions for SHOW and SET statements too -
 662                         // that would delay transaction initializations to once connection
 663                         // is really used by application
 664                         $sqlstart = substr( $sql, 0, 10 ); // very much worth it, benchmark certified(tm)
 665                         if ( strpos( $sqlstart, "SHOW " ) !== 0 and strpos( $sqlstart, "SET " ) !== 0 )
 666                                 $this->begin();
 667                 }
 668
 669                 if ( $this->debug() ) {
 670                         static $cnt = 0;
 671
 672                         $cnt++;
 673                         $sqlx = substr( $commentedSql, 0, 500 );
 674                         $sqlx = strtr( $sqlx, "\t\n", '  ' );
 675
 676                         if ( $isMaster ) {
 677                                 wfDebug( "Query $cnt (master): $sqlx\n" );
 678                         } else {
 679                                 wfDebug( "Query $cnt (slave): $sqlx\n" );
 680                         }
 681                 }
 682
 683                 if ( istainted( $sql ) & TC_MYSQL ) {
 684                         throw new MWException( 'Tainted query found' );
 685                 }
 686
 687                 # Do the query and handle errors
 688                 $ret = $this->doQuery( $commentedSql );
 689
 690                 # Try reconnecting if the connection was lost
 691                 if ( false === $ret && $this->wasErrorReissuable() ) {
 692                         # Transaction is gone, like it or not
 693                         $this->mTrxLevel = 0;
 694                         wfDebug( "Connection lost, reconnecting...\n" );
 695
 696                         if ( $this->ping() ) {
 697                                 wfDebug( "Reconnected\n" );
 698                                 $sqlx = substr( $commentedSql, 0, 500 );
 699                                 $sqlx = strtr( $sqlx, "\t\n", '  ' );
 700                                 global $wgRequestTime;
 701                                 $elapsed = round( microtime( true ) - $wgRequestTime, 3 );
 702                                 wfLogDBError( "Connection lost and reconnected after {$elapsed}s, query: $sqlx\n" );
 703                                 $ret = $this->doQuery( $commentedSql );
 704                         } else {
 705                                 wfDebug( "Failed\n" );
 706                         }
 707                 }
 708
 709                 if ( false === $ret ) {
 710                         $this->reportQueryError( $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 711                 }
 712
 713                 if ( isset( $wgProfiler ) ) {
 714                         wfProfileOut( $queryProf );
 715                         wfProfileOut( $totalProf );
 716                 }
 717
 718                 return $this->resultObject( $ret );
 719         }
 720
 721         /**
 722          * @param $error String
 723          * @param $errno Integer
 724          * @param $sql String
 725          * @param $fname String
 726          * @param $tempIgnore Boolean
 727          */
 728         function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 729                 # Ignore errors during error handling to avoid infinite recursion
 730                 $ignore = $this->ignoreErrors( true );
 731                 ++$this->mErrorCount;
 732
 733                 if ( $ignore || $tempIgnore ) {
 734                         wfDebug( "SQL ERROR (ignored): $error\n" );
 735                         $this->ignoreErrors( $ignore );
 736                 } else {
 737                         $sql1line = str_replace( "\n", "\\n", $sql );
 738                         wfLogDBError( "$fname\t{$this->mServer}\t$errno\t$error\t$sql1line\n" );
 739                         wfDebug( "SQL ERROR: " . $error . "\n" );
 740                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
 741                 }
 742         }
 743
 744
 745         /**
 746          * Intended to be compatible with the PEAR::DB wrapper functions.
 747          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
 748          *
 749          * ? = scalar value, quoted as necessary
 750          * ! = raw SQL bit (a function for instance)
 751          * & = filename; reads the file and inserts as a blob
 752          *     (we don't use this though...)
 753          */
 754         function prepare( $sql, $func = 'DatabaseBase::prepare' ) {
 755                 /* MySQL doesn't support prepared statements (yet), so just
 756                    pack up the query for reference. We'll manually replace
 757                    the bits later. */
 758                 return array( 'query' => $sql, 'func' => $func );
 759         }
 760
 761         function freePrepared( $prepared ) {
 762                 /* No-op by default */
 763         }
 764
 765         /**
 766          * Execute a prepared query with the various arguments
 767          * @param $prepared String: the prepared sql
 768          * @param $args Mixed: Either an array here, or put scalars as varargs
 769          */
 770         function execute( $prepared, $args = null ) {
 771                 if ( !is_array( $args ) ) {
 772                         # Pull the var args
 773                         $args = func_get_args();
 774                         array_shift( $args );
 775                 }
 776
 777                 $sql = $this->fillPrepared( $prepared['query'], $args );
 778
 779                 return $this->query( $sql, $prepared['func'] );
 780         }
 781
 782         /**
 783          * Prepare & execute an SQL statement, quoting and inserting arguments
 784          * in the appropriate places.
 785          * @param $query String
 786          * @param $args ...
 787          */
 788         function safeQuery( $query, $args = null ) {
 789                 $prepared = $this->prepare( $query, 'DatabaseBase::safeQuery' );
 790
 791                 if ( !is_array( $args ) ) {
 792                         # Pull the var args
 793                         $args = func_get_args();
 794                         array_shift( $args );
 795                 }
 796
 797                 $retval = $this->execute( $prepared, $args );
 798                 $this->freePrepared( $prepared );
 799
 800                 return $retval;
 801         }
 802
 803         /**
 804          * For faking prepared SQL statements on DBs that don't support
 805          * it directly.
 806          * @param $preparedQuery String: a 'preparable' SQL statement
 807          * @param $args Array of arguments to fill it with
 808          * @return string executable SQL
 809          */
 810         function fillPrepared( $preparedQuery, $args ) {
 811                 reset( $args );
 812                 $this->preparedArgs =& $args;
 813
 814                 return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
 815                         array( &$this, 'fillPreparedArg' ), $preparedQuery );
 816         }
 817
 818         /**
 819          * preg_callback func for fillPrepared()
 820          * The arguments should be in $this->preparedArgs and must not be touched
 821          * while we're doing this.
 822          *
 823          * @param $matches Array
 824          * @return String
 825          * @private
 826          */
 827         function fillPreparedArg( $matches ) {
 828                 switch( $matches[1] ) {
 829                         case '\\?': return '?';
 830                         case '\\!': return '!';
 831                         case '\\&': return '&';
 832                 }
 833
 834                 list( /* $n */ , $arg ) = each( $this->preparedArgs );
 835
 836                 switch( $matches[1] ) {
 837                         case '?': return $this->addQuotes( $arg );
 838                         case '!': return $arg;
 839                         case '&':
 840                                 # return $this->addQuotes( file_get_contents( $arg ) );
 841                                 throw new DBUnexpectedError( $this, '& mode is not implemented. If it\'s really needed, uncomment the line above.' );
 842                         default:
 843                                 throw new DBUnexpectedError( $this, 'Received invalid match. This should never happen!' );
 844                 }
 845         }
 846
 847         /**
 848          * Free a result object
 849          * @param $res Mixed: A SQL result
 850          */
 851         function freeResult( $res ) {
 852                 # Stub.  Might not really need to be overridden, since results should
 853                 # be freed by PHP when the variable goes out of scope anyway.
 854         }
 855
 856         /**
 857          * Simple UPDATE wrapper
 858          * Usually aborts on failure
 859          * If errors are explicitly ignored, returns success
 860          *
 861          * This function exists for historical reasons, DatabaseBase::update() has a more standard
 862          * calling convention and feature set
 863          */
 864         function set( $table, $var, $value, $cond, $fname = 'DatabaseBase::set' ) {
 865                 $table = $this->tableName( $table );
 866                 $sql = "UPDATE $table SET $var = '" .
 867                   $this->strencode( $value ) . "' WHERE ($cond)";
 868
 869                 return (bool)$this->query( $sql, $fname );
 870         }
 871
 872         /**
 873          * Simple SELECT wrapper, returns a single field, input must be encoded
 874          * Usually aborts on failure
 875          * If errors are explicitly ignored, returns FALSE on failure
 876          */
 877         function selectField( $table, $var, $cond = '', $fname = 'DatabaseBase::selectField', $options = array() ) {
 878                 if ( !is_array( $options ) ) {
 879                         $options = array( $options );
 880                 }
 881
 882                 $options['LIMIT'] = 1;
 883
 884                 $res = $this->select( $table, $var, $cond, $fname, $options );
 885
 886                 if ( $res === false || !$this->numRows( $res ) ) {
 887                         return false;
 888                 }
 889
 890                 $row = $this->fetchRow( $res );
 891
 892                 if ( $row !== false ) {
 893                         return reset( $row );
 894                 } else {
 895                         return false;
 896                 }
 897         }
 898
 899         /**
 900          * Returns an optional USE INDEX clause to go after the table, and a
 901          * string to go at the end of the query
 902          *
 903          * @private
 904          *
 905          * @param $options Array: associative array of options to be turned into
 906          *              an SQL query, valid keys are listed in the function.
 907          * @return Array
 908          */
 909         function makeSelectOptions( $options ) {
 910                 $preLimitTail = $postLimitTail = '';
 911                 $startOpts = '';
 912
 913                 $noKeyOptions = array();
 914
 915                 foreach ( $options as $key => $option ) {
 916                         if ( is_numeric( $key ) ) {
 917                                 $noKeyOptions[$option] = true;
 918                         }
 919                 }
 920
 921                 if ( isset( $options['GROUP BY'] ) ) {
 922                         $preLimitTail .= " GROUP BY {$options['GROUP BY']}";
 923                 }
 924
 925                 if ( isset( $options['HAVING'] ) ) {
 926                         $preLimitTail .= " HAVING {$options['HAVING']}";
 927                 }
 928
 929                 if ( isset( $options['ORDER BY'] ) ) {
 930                         $preLimitTail .= " ORDER BY {$options['ORDER BY']}";
 931                 }
 932
 933                 // if (isset($options['LIMIT'])) {
 934                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
 935                 //              isset($options['OFFSET']) ? $options['OFFSET']
 936                 //              : false);
 937                 // }
 938
 939                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
 940                         $postLimitTail .= ' FOR UPDATE';
 941                 }
 942
 943                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
 944                         $postLimitTail .= ' LOCK IN SHARE MODE';
 945                 }
 946
 947                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
 948                         $startOpts .= 'DISTINCT';
 949                 }
 950
 951                 # Various MySQL extensions
 952                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
 953                         $startOpts .= ' /*! STRAIGHT_JOIN */';
 954                 }
 955
 956                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
 957                         $startOpts .= ' HIGH_PRIORITY';
 958                 }
 959
 960                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
 961                         $startOpts .= ' SQL_BIG_RESULT';
 962                 }
 963
 964                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
 965                         $startOpts .= ' SQL_BUFFER_RESULT';
 966                 }
 967
 968                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
 969                         $startOpts .= ' SQL_SMALL_RESULT';
 970                 }
 971
 972                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
 973                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
 974                 }
 975
 976                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
 977                         $startOpts .= ' SQL_CACHE';
 978                 }
 979
 980                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
 981                         $startOpts .= ' SQL_NO_CACHE';
 982                 }
 983
 984                 if ( isset( $options['USE INDEX'] ) && ! is_array( $options['USE INDEX'] ) ) {
 985                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
 986                 } else {
 987                         $useIndex = '';
 988                 }
 989
 990                 return array( $startOpts, $useIndex, $preLimitTail, $postLimitTail );
 991         }
 992
 993         /**
 994          * SELECT wrapper
 995          *
 996          * @param $table   Mixed:  Array or string, table name(s) (prefix auto-added)
 997          * @param $vars    Mixed:  Array or string, field name(s) to be retrieved
 998          * @param $conds   Mixed:  Array or string, condition(s) for WHERE
 999          * @param $fname   String: Calling function name (use __METHOD__) for logs/profiling
1000          * @param $options Array:  Associative array of options (e.g. array('GROUP BY' => 'page_title')),
1001          *                         see DatabaseBase::makeSelectOptions code for list of supported stuff
1002          * @param $join_conds Array: Associative array of table join conditions (optional)
1003          *                           (e.g. array( 'page' => array('LEFT JOIN','page_latest=rev_id') )
1004          * @return mixed Database result resource (feed to DatabaseBase::fetchObject or whatever), or false on failure
1005          */
1006         function select( $table, $vars, $conds = '', $fname = 'DatabaseBase::select', $options = array(), $join_conds = array() ) {
1007                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1008
1009                 return $this->query( $sql, $fname );
1010         }
1011
1012         /**
1013          * SELECT wrapper
1014          *
1015          * @param $table   Mixed:  Array or string, table name(s) (prefix auto-added)
1016          * @param $vars    Mixed:  Array or string, field name(s) to be retrieved
1017          * @param $conds   Mixed:  Array or string, condition(s) for WHERE
1018          * @param $fname   String: Calling function name (use __METHOD__) for logs/profiling
1019          * @param $options Array:  Associative array of options (e.g. array('GROUP BY' => 'page_title')),
1020          *                         see DatabaseBase::makeSelectOptions code for list of supported stuff
1021          * @param $join_conds Array: Associative array of table join conditions (optional)
1022          *                           (e.g. array( 'page' => array('LEFT JOIN','page_latest=rev_id') )
1023          * @return string, the SQL text
1024          */
1025         function selectSQLText( $table, $vars, $conds = '', $fname = 'DatabaseBase::select', $options = array(), $join_conds = array() ) {
1026                 if ( is_array( $vars ) ) {
1027                         $vars = implode( ',', $vars );
1028                 }
1029
1030                 if ( !is_array( $options ) ) {
1031                         $options = array( $options );
1032                 }
1033
1034                 if ( is_array( $table ) ) {
1035                         if ( !empty( $join_conds ) || ( isset( $options['USE INDEX'] ) && is_array( @$options['USE INDEX'] ) ) ) {
1036                                 $from = ' FROM ' . $this->tableNamesWithUseIndexOrJOIN( $table, @$options['USE INDEX'], $join_conds );
1037                         } else {
1038                                 $from = ' FROM ' . implode( ',', array_map( array( &$this, 'tableName' ), $table ) );
1039                         }
1040                 } elseif ( $table != '' ) {
1041                         if ( $table { 0 } == ' ' ) {
1042                                 $from = ' FROM ' . $table;
1043                         } else {
1044                                 $from = ' FROM ' . $this->tableName( $table );
1045                         }
1046                 } else {
1047                         $from = '';
1048                 }
1049
1050                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail ) = $this->makeSelectOptions( $options );
1051
1052                 if ( !empty( $conds ) ) {
1053                         if ( is_array( $conds ) ) {
1054                                 $conds = $this->makeList( $conds, LIST_AND );
1055                         }
1056                         $sql = "SELECT $startOpts $vars $from $useIndex WHERE $conds $preLimitTail";
1057                 } else {
1058                         $sql = "SELECT $startOpts $vars $from $useIndex $preLimitTail";
1059                 }
1060
1061                 if ( isset( $options['LIMIT'] ) )
1062                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1063                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1064                 $sql = "$sql $postLimitTail";
1065
1066                 if ( isset( $options['EXPLAIN'] ) ) {
1067                         $sql = 'EXPLAIN ' . $sql;
1068                 }
1069
1070                 return $sql;
1071         }
1072
1073         /**
1074          * Single row SELECT wrapper
1075          * Aborts or returns FALSE on error
1076          *
1077          * @param $table String: table name
1078          * @param $vars String: the selected variables
1079          * @param $conds Array: a condition map, terms are ANDed together.
1080          *   Items with numeric keys are taken to be literal conditions
1081          * Takes an array of selected variables, and a condition map, which is ANDed
1082          * e.g: selectRow( "page", array( "page_id" ), array( "page_namespace" =>
1083          * NS_MAIN, "page_title" => "Astronomy" ) )   would return an object where
1084          * $obj- >page_id is the ID of the Astronomy article
1085          * @param $fname String: Calling function name
1086          * @param $options Array
1087          * @param $join_conds Array
1088          *
1089          * @todo migrate documentation to phpdocumentor format
1090          */
1091         function selectRow( $table, $vars, $conds, $fname = 'DatabaseBase::selectRow', $options = array(), $join_conds = array() ) {
1092                 $options['LIMIT'] = 1;
1093                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1094
1095                 if ( $res === false ) {
1096                         return false;
1097                 }
1098
1099                 if ( !$this->numRows( $res ) ) {
1100                         return false;
1101                 }
1102
1103                 $obj = $this->fetchObject( $res );
1104
1105                 return $obj;
1106         }
1107
1108         /**
1109          * Estimate rows in dataset
1110          * Returns estimated count - not necessarily an accurate estimate across different databases,
1111          * so use sparingly
1112          * Takes same arguments as DatabaseBase::select()
1113          *
1114          * @param $table String: table name
1115          * @param $vars Array: unused
1116          * @param $conds Array: filters on the table
1117          * @param $fname String: function name for profiling
1118          * @param $options Array: options for select
1119          * @return Integer: row count
1120          */
1121         public function estimateRowCount( $table, $vars = '*', $conds = '', $fname = 'DatabaseBase::estimateRowCount', $options = array() ) {
1122                 $rows = 0;
1123                 $res = $this->select ( $table, 'COUNT(*) AS rowcount', $conds, $fname, $options );
1124
1125                 if ( $res ) {
1126                         $row = $this->fetchRow( $res );
1127                         $rows = ( isset( $row['rowcount'] ) ) ? $row['rowcount'] : 0;
1128                 }
1129
1130                 return $rows;
1131         }
1132
1133         /**
1134          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1135          * It's only slightly flawed. Don't use for anything important.
1136          *
1137          * @param $sql String: A SQL Query
1138          */
1139         static function generalizeSQL( $sql ) {
1140                 # This does the same as the regexp below would do, but in such a way
1141                 # as to avoid crashing php on some large strings.
1142                 # $sql = preg_replace ( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql);
1143
1144                 $sql = str_replace ( "\\\\", '', $sql );
1145                 $sql = str_replace ( "\\'", '', $sql );
1146                 $sql = str_replace ( "\\\"", '', $sql );
1147                 $sql = preg_replace ( "/'.*'/s", "'X'", $sql );
1148                 $sql = preg_replace ( '/".*"/s', "'X'", $sql );
1149
1150                 # All newlines, tabs, etc replaced by single space
1151                 $sql = preg_replace ( '/\s+/', ' ', $sql );
1152
1153                 # All numbers => N
1154                 $sql = preg_replace ( '/-?[0-9]+/s', 'N', $sql );
1155
1156                 return $sql;
1157         }
1158
1159         /**
1160          * Determines whether a field exists in a table
1161          *
1162          * @param $table String: table name
1163          * @param $field String: filed to check on that table
1164          * @param $fname String: calling function name (optional)
1165          * @return Boolean: whether $table has filed $field
1166          */
1167         function fieldExists( $table, $field, $fname = 'DatabaseBase::fieldExists' ) {
1168                 $info = $this->fieldInfo( $table, $field );
1169
1170                 return (bool)$info;
1171         }
1172
1173         /**
1174          * Determines whether an index exists
1175          * Usually aborts on failure
1176          * If errors are explicitly ignored, returns NULL on failure
1177          */
1178         function indexExists( $table, $index, $fname = 'DatabaseBase::indexExists' ) {
1179                 $info = $this->indexInfo( $table, $index, $fname );
1180                 if ( is_null( $info ) ) {
1181                         return null;
1182                 } else {
1183                         return $info !== false;
1184                 }
1185         }
1186
1187         /**
1188          * Query whether a given table exists
1189          */
1190         function tableExists( $table ) {
1191                 $table = $this->tableName( $table );
1192                 $old = $this->ignoreErrors( true );
1193                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", __METHOD__ );
1194                 $this->ignoreErrors( $old );
1195
1196                 return (bool)$res;
1197         }
1198
1199         /**
1200          * mysql_field_type() wrapper
1201          */
1202         function fieldType( $res, $index ) {
1203                 if ( $res instanceof ResultWrapper ) {
1204                         $res = $res->result;
1205                 }
1206
1207                 return mysql_field_type( $res, $index );
1208         }
1209
1210         /**
1211          * Determines if a given index is unique
1212          */
1213         function indexUnique( $table, $index ) {
1214                 $indexInfo = $this->indexInfo( $table, $index );
1215
1216                 if ( !$indexInfo ) {
1217                         return null;
1218                 }
1219
1220                 return !$indexInfo[0]->Non_unique;
1221         }
1222
1223         /**
1224          * INSERT wrapper, inserts an array into a table
1225          *
1226          * $a may be a single associative array, or an array of these with numeric keys, for
1227          * multi-row insert.
1228          *
1229          * Usually aborts on failure
1230          * If errors are explicitly ignored, returns success
1231          *
1232          * @param $table   String: table name (prefix auto-added)
1233          * @param $a       Array: Array of rows to insert
1234          * @param $fname   String: Calling function name (use __METHOD__) for logs/profiling
1235          * @param $options Mixed: Associative array of options
1236          *
1237          * @return bool
1238          */
1239         function insert( $table, $a, $fname = 'DatabaseBase::insert', $options = array() ) {
1240                 # No rows to insert, easy just return now
1241                 if ( !count( $a ) ) {
1242                         return true;
1243                 }
1244
1245                 $table = $this->tableName( $table );
1246
1247                 if ( !is_array( $options ) ) {
1248                         $options = array( $options );
1249                 }
1250
1251                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1252                         $multi = true;
1253                         $keys = array_keys( $a[0] );
1254                 } else {
1255                         $multi = false;
1256                         $keys = array_keys( $a );
1257                 }
1258
1259                 $sql = 'INSERT ' . implode( ' ', $options ) .
1260                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1261
1262                 if ( $multi ) {
1263                         $first = true;
1264                         foreach ( $a as $row ) {
1265                                 if ( $first ) {
1266                                         $first = false;
1267                                 } else {
1268                                         $sql .= ',';
1269                                 }
1270                                 $sql .= '(' . $this->makeList( $row ) . ')';
1271                         }
1272                 } else {
1273                         $sql .= '(' . $this->makeList( $a ) . ')';
1274                 }
1275
1276                 return (bool)$this->query( $sql, $fname );
1277         }
1278
1279         /**
1280          * Make UPDATE options for the DatabaseBase::update function
1281          *
1282          * @private
1283          * @param $options Array: The options passed to DatabaseBase::update
1284          * @return string
1285          */
1286         function makeUpdateOptions( $options ) {
1287                 if ( !is_array( $options ) ) {
1288                         $options = array( $options );
1289                 }
1290
1291                 $opts = array();
1292
1293                 if ( in_array( 'LOW_PRIORITY', $options ) ) {
1294                         $opts[] = $this->lowPriorityOption();
1295                 }
1296
1297                 if ( in_array( 'IGNORE', $options ) ) {
1298                         $opts[] = 'IGNORE';
1299                 }
1300
1301                 return implode( ' ', $opts );
1302         }
1303
1304         /**
1305          * UPDATE wrapper, takes a condition array and a SET array
1306          *
1307          * @param $table  String: The table to UPDATE
1308          * @param $values Array:  An array of values to SET
1309          * @param $conds  Array:  An array of conditions (WHERE). Use '*' to update all rows.
1310          * @param $fname  String: The Class::Function calling this function
1311          *                        (for the log)
1312          * @param $options Array: An array of UPDATE options, can be one or
1313          *                        more of IGNORE, LOW_PRIORITY
1314          * @return Boolean
1315          */
1316         function update( $table, $values, $conds, $fname = 'DatabaseBase::update', $options = array() ) {
1317                 $table = $this->tableName( $table );
1318                 $opts = $this->makeUpdateOptions( $options );
1319                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1320
1321                 if ( $conds != '*' ) {
1322                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1323                 }
1324
1325                 return $this->query( $sql, $fname );
1326         }
1327
1328         /**
1329          * Makes an encoded list of strings from an array
1330          * $mode:
1331          *        LIST_COMMA         - comma separated, no field names
1332          *        LIST_AND           - ANDed WHERE clause (without the WHERE)
1333          *        LIST_OR            - ORed WHERE clause (without the WHERE)
1334          *        LIST_SET           - comma separated with field names, like a SET clause
1335          *        LIST_NAMES         - comma separated field names
1336          */
1337         function makeList( $a, $mode = LIST_COMMA ) {
1338                 if ( !is_array( $a ) ) {
1339                         throw new DBUnexpectedError( $this, 'DatabaseBase::makeList called with incorrect parameters' );
1340                 }
1341
1342                 $first = true;
1343                 $list = '';
1344
1345                 foreach ( $a as $field => $value ) {
1346                         if ( !$first ) {
1347                                 if ( $mode == LIST_AND ) {
1348                                         $list .= ' AND ';
1349                                 } elseif ( $mode == LIST_OR ) {
1350                                         $list .= ' OR ';
1351                                 } else {
1352                                         $list .= ',';
1353                                 }
1354                         } else {
1355                                 $first = false;
1356                         }
1357
1358                         if ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_numeric( $field ) ) {
1359                                 $list .= "($value)";
1360                         } elseif ( ( $mode == LIST_SET ) && is_numeric( $field ) ) {
1361                                 $list .= "$value";
1362                         } elseif ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_array( $value ) ) {
1363                                 if ( count( $value ) == 0 ) {
1364                                         throw new MWException( __METHOD__ . ': empty input' );
1365                                 } elseif ( count( $value ) == 1 ) {
1366                                         // Special-case single values, as IN isn't terribly efficient
1367                                         // Don't necessarily assume the single key is 0; we don't
1368                                         // enforce linear numeric ordering on other arrays here.
1369                                         $value = array_values( $value );
1370                                         $list .= $field . " = " . $this->addQuotes( $value[0] );
1371                                 } else {
1372                                         $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1373                                 }
1374                         } elseif ( $value === null ) {
1375                                 if ( $mode == LIST_AND || $mode == LIST_OR ) {
1376                                         $list .= "$field IS ";
1377                                 } elseif ( $mode == LIST_SET ) {
1378                                         $list .= "$field = ";
1379                                 }
1380                                 $list .= 'NULL';
1381                         } else {
1382                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
1383                                         $list .= "$field = ";
1384                                 }
1385                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
1386                         }
1387                 }
1388
1389                 return $list;
1390         }
1391
1392         /**
1393          * Build a partial where clause from a 2-d array such as used for LinkBatch.
1394          * The keys on each level may be either integers or strings.
1395          *
1396          * @param $data Array: organized as 2-d array(baseKeyVal => array(subKeyVal => <ignored>, ...), ...)
1397          * @param $baseKey String: field name to match the base-level keys to (eg 'pl_namespace')
1398          * @param $subKey String: field name to match the sub-level keys to (eg 'pl_title')
1399          * @return Mixed: string SQL fragment, or false if no items in array.
1400          */
1401         function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1402                 $conds = array();
1403
1404                 foreach ( $data as $base => $sub ) {
1405                         if ( count( $sub ) ) {
1406                                 $conds[] = $this->makeList(
1407                                         array( $baseKey => $base, $subKey => array_keys( $sub ) ),
1408                                         LIST_AND );
1409                         }
1410                 }
1411
1412                 if ( $conds ) {
1413                         return $this->makeList( $conds, LIST_OR );
1414                 } else {
1415                         // Nothing to search for...
1416                         return false;
1417                 }
1418         }
1419
1420         /**
1421          * Bitwise operations
1422          */
1423
1424         function bitNot( $field ) {
1425                 return "(~$field)";
1426         }
1427
1428         function bitAnd( $fieldLeft, $fieldRight ) {
1429                 return "($fieldLeft & $fieldRight)";
1430         }
1431
1432         function bitOr( $fieldLeft, $fieldRight ) {
1433                 return "($fieldLeft | $fieldRight)";
1434         }
1435
1436         /**
1437          * Change the current database
1438          *
1439          * @todo Explain what exactly will fail if this is not overridden.
1440          * @return bool Success or failure
1441          */
1442         function selectDB( $db ) {
1443                 # Stub.  Shouldn't cause serious problems if it's not overridden, but
1444                 # if your database engine supports a concept similar to MySQL's
1445                 # databases you may as well.
1446                 return true;
1447         }
1448
1449         /**
1450          * Get the current DB name
1451          */
1452         function getDBname() {
1453                 return $this->mDBname;
1454         }
1455
1456         /**
1457          * Get the server hostname or IP address
1458          */
1459         function getServer() {
1460                 return $this->mServer;
1461         }
1462
1463         /**
1464          * Format a table name ready for use in constructing an SQL query
1465          *
1466          * This does two important things: it quotes the table names to clean them up,
1467          * and it adds a table prefix if only given a table name with no quotes.
1468          *
1469          * All functions of this object which require a table name call this function
1470          * themselves. Pass the canonical name to such functions. This is only needed
1471          * when calling query() directly.
1472          *
1473          * @param $name String: database table name
1474          * @return String: full database name
1475          */
1476         function tableName( $name ) {
1477                 global $wgSharedDB, $wgSharedPrefix, $wgSharedTables;
1478                 # Skip the entire process when we have a string quoted on both ends.
1479                 # Note that we check the end so that we will still quote any use of
1480                 # use of `database`.table. But won't break things if someone wants
1481                 # to query a database table with a dot in the name.
1482                 if ( $name[0] == '`' && substr( $name, -1, 1 ) == '`' ) {
1483                         return $name;
1484                 }
1485
1486                 # Lets test for any bits of text that should never show up in a table
1487                 # name. Basically anything like JOIN or ON which are actually part of
1488                 # SQL queries, but may end up inside of the table value to combine
1489                 # sql. Such as how the API is doing.
1490                 # Note that we use a whitespace test rather than a \b test to avoid
1491                 # any remote case where a word like on may be inside of a table name
1492                 # surrounded by symbols which may be considered word breaks.
1493                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1494                         return $name;
1495                 }
1496
1497                 # Split database and table into proper variables.
1498                 # We reverse the explode so that database.table and table both output
1499                 # the correct table.
1500                 $dbDetails = array_reverse( explode( '.', $name, 2 ) );
1501                 if ( isset( $dbDetails[1] ) ) {
1502                         @list( $table, $database ) = $dbDetails;
1503                 } else {
1504                         @list( $table ) = $dbDetails;
1505                 }
1506                 $prefix = $this->mTablePrefix; # Default prefix
1507
1508                 # A database name has been specified in input. Quote the table name
1509                 # because we don't want any prefixes added.
1510                 if ( isset( $database ) ) {
1511                         $table = ( $table[0] == '`' ? $table : "`{$table}`" );
1512                 }
1513
1514                 # Note that we use the long format because php will complain in in_array if
1515                 # the input is not an array, and will complain in is_array if it is not set.
1516                 if ( !isset( $database ) # Don't use shared database if pre selected.
1517                  && isset( $wgSharedDB ) # We have a shared database
1518                  && $table[0] != '`' # Paranoia check to prevent shared tables listing '`table`'
1519                  && isset( $wgSharedTables )
1520                  && is_array( $wgSharedTables )
1521                  && in_array( $table, $wgSharedTables ) ) { # A shared table is selected
1522                         $database = $wgSharedDB;
1523                         $prefix   = isset( $wgSharedPrefix ) ? $wgSharedPrefix : $prefix;
1524                 }
1525
1526                 # Quote the $database and $table and apply the prefix if not quoted.
1527                 if ( isset( $database ) ) {
1528                         $database = ( $database[0] == '`' ? $database : "`{$database}`" );
1529                 }
1530                 $table = ( $table[0] == '`' ? $table : "`{$prefix}{$table}`" );
1531
1532                 # Merge our database and table into our final table name.
1533                 $tableName = ( isset( $database ) ? "{$database}.{$table}" : "{$table}" );
1534
1535                 return $tableName;
1536         }
1537
1538         /**
1539          * Fetch a number of table names into an array
1540          * This is handy when you need to construct SQL for joins
1541          *
1542          * Example:
1543          * extract($dbr->tableNames('user','watchlist'));
1544          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1545          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1546          */
1547         public function tableNames() {
1548                 $inArray = func_get_args();
1549                 $retVal = array();
1550
1551                 foreach ( $inArray as $name ) {
1552                         $retVal[$name] = $this->tableName( $name );
1553                 }
1554
1555                 return $retVal;
1556         }
1557
1558         /**
1559          * Fetch a number of table names into an zero-indexed numerical array
1560          * This is handy when you need to construct SQL for joins
1561          *
1562          * Example:
1563          * list( $user, $watchlist ) = $dbr->tableNamesN('user','watchlist');
1564          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1565          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1566          */
1567         public function tableNamesN() {
1568                 $inArray = func_get_args();
1569                 $retVal = array();
1570
1571                 foreach ( $inArray as $name ) {
1572                         $retVal[] = $this->tableName( $name );
1573                 }
1574
1575                 return $retVal;
1576         }
1577
1578         /**
1579          * @private
1580          */
1581         function tableNamesWithUseIndexOrJOIN( $tables, $use_index = array(), $join_conds = array() ) {
1582                 $ret = array();
1583                 $retJOIN = array();
1584                 $use_index_safe = is_array( $use_index ) ? $use_index : array();
1585                 $join_conds_safe = is_array( $join_conds ) ? $join_conds : array();
1586
1587                 foreach ( $tables as $table ) {
1588                         // Is there a JOIN and INDEX clause for this table?
1589                         if ( isset( $join_conds_safe[$table] ) && isset( $use_index_safe[$table] ) ) {
1590                                 $tableClause = $join_conds_safe[$table][0] . ' ' . $this->tableName( $table );
1591                                 $tableClause .= ' ' . $this->useIndexClause( implode( ',', (array)$use_index_safe[$table] ) );
1592                                 $on = $this->makeList( (array)$join_conds_safe[$table][1], LIST_AND );
1593
1594                                 if ( $on != '' ) {
1595                                         $tableClause .= ' ON (' . $on . ')';
1596                                 }
1597
1598                                 $retJOIN[] = $tableClause;
1599                         // Is there an INDEX clause?
1600                         } else if ( isset( $use_index_safe[$table] ) ) {
1601                                 $tableClause = $this->tableName( $table );
1602                                 $tableClause .= ' ' . $this->useIndexClause( implode( ',', (array)$use_index_safe[$table] ) );
1603                                 $ret[] = $tableClause;
1604                         // Is there a JOIN clause?
1605                         } else if ( isset( $join_conds_safe[$table] ) ) {
1606                                 $tableClause = $join_conds_safe[$table][0] . ' ' . $this->tableName( $table );
1607                                 $on = $this->makeList( (array)$join_conds_safe[$table][1], LIST_AND );
1608
1609                                 if ( $on != '' ) {
1610                                         $tableClause .= ' ON (' . $on . ')';
1611                                 }
1612
1613                                 $retJOIN[] = $tableClause;
1614                         } else {
1615                                 $tableClause = $this->tableName( $table );
1616                                 $ret[] = $tableClause;
1617                         }
1618                 }
1619
1620                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
1621                 $straightJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
1622                 $otherJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
1623
1624                 // Compile our final table clause
1625                 return implode( ' ', array( $straightJoins, $otherJoins ) );
1626         }
1627
1628         /**
1629          * Get the name of an index in a given table
1630          */
1631         function indexName( $index ) {
1632                 // Backwards-compatibility hack
1633                 $renamed = array(
1634                         'ar_usertext_timestamp' => 'usertext_timestamp',
1635                         'un_user_id'            => 'user_id',
1636                         'un_user_ip'            => 'user_ip',
1637                 );
1638
1639                 if ( isset( $renamed[$index] ) ) {
1640                         return $renamed[$index];
1641                 } else {
1642                         return $index;
1643                 }
1644         }
1645
1646         /**
1647          * If it's a string, adds quotes and backslashes
1648          * Otherwise returns as-is
1649          */
1650         function addQuotes( $s ) {
1651                 if ( $s === null ) {
1652                         return 'NULL';
1653                 } else {
1654                         # This will also quote numeric values. This should be harmless,
1655                         # and protects against weird problems that occur when they really
1656                         # _are_ strings such as article titles and string->number->string
1657                         # conversion is not 1:1.
1658                         return "'" . $this->strencode( $s ) . "'";
1659                 }
1660         }
1661
1662         /**
1663          * Escape string for safe LIKE usage.
1664          * WARNING: you should almost never use this function directly,
1665          * instead use buildLike() that escapes everything automatically
1666          * Deprecated in 1.17, warnings in 1.17, removed in ???
1667          */
1668         public function escapeLike( $s ) {
1669                 wfDeprecated( __METHOD__ );
1670                 return $this->escapeLikeInternal( $s );
1671         }
1672
1673         protected function escapeLikeInternal( $s ) {
1674                 $s = str_replace( '\\', '\\\\', $s );
1675                 $s = $this->strencode( $s );
1676                 $s = str_replace( array( '%', '_' ), array( '\%', '\_' ), $s );
1677
1678                 return $s;
1679         }
1680
1681         /**
1682          * LIKE statement wrapper, receives a variable-length argument list with parts of pattern to match
1683          * containing either string literals that will be escaped or tokens returned by anyChar() or anyString().
1684          * Alternatively, the function could be provided with an array of aforementioned parameters.
1685          *
1686          * Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns a LIKE clause that searches
1687          * for subpages of 'My page title'.
1688          * Alternatively: $pattern = array( 'My_page_title/', $dbr->anyString() ); $query .= $dbr->buildLike( $pattern );
1689          *
1690          * @since 1.16
1691          * @return String: fully built LIKE statement
1692          */
1693         function buildLike() {
1694                 $params = func_get_args();
1695
1696                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
1697                         $params = $params[0];
1698                 }
1699
1700                 $s = '';
1701
1702                 foreach ( $params as $value ) {
1703                         if ( $value instanceof LikeMatch ) {
1704                                 $s .= $value->toString();
1705                         } else {
1706                                 $s .= $this->escapeLikeInternal( $value );
1707                         }
1708                 }
1709
1710                 return " LIKE '" . $s . "' ";
1711         }
1712
1713         /**
1714          * Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
1715          */
1716         function anyChar() {
1717                 return new LikeMatch( '_' );
1718         }
1719
1720         /**
1721          * Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
1722          */
1723         function anyString() {
1724                 return new LikeMatch( '%' );
1725         }
1726
1727         /**
1728          * Returns an appropriately quoted sequence value for inserting a new row.
1729          * MySQL has autoincrement fields, so this is just NULL. But the PostgreSQL
1730          * subclass will return an integer, and save the value for insertId()
1731          */
1732         function nextSequenceValue( $seqName ) {
1733                 return null;
1734         }
1735
1736         /**
1737          * USE INDEX clause.  Unlikely to be useful for anything but MySQL.  This
1738          * is only needed because a) MySQL must be as efficient as possible due to
1739          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
1740          * which index to pick.  Anyway, other databases might have different
1741          * indexes on a given table.  So don't bother overriding this unless you're
1742          * MySQL.
1743          */
1744         function useIndexClause( $index ) {
1745                 return '';
1746         }
1747
1748         /**
1749          * REPLACE query wrapper
1750          * PostgreSQL simulates this with a DELETE followed by INSERT
1751          * $row is the row to insert, an associative array
1752          * $uniqueIndexes is an array of indexes. Each element may be either a
1753          * field name or an array of field names
1754          *
1755          * It may be more efficient to leave off unique indexes which are unlikely to collide.
1756          * However if you do this, you run the risk of encountering errors which wouldn't have
1757          * occurred in MySQL
1758          *
1759          * @param $table String: The table to replace the row(s) in.
1760          * @param $uniqueIndexes Array: An associative array of indexes
1761          * @param $rows Array: Array of rows to replace
1762          * @param $fname String: Calling function name (use __METHOD__) for logs/profiling
1763          */
1764         function replace( $table, $uniqueIndexes, $rows, $fname = 'DatabaseBase::replace' ) {
1765                 $table = $this->tableName( $table );
1766
1767                 # Single row case
1768                 if ( !is_array( reset( $rows ) ) ) {
1769                         $rows = array( $rows );
1770                 }
1771
1772                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
1773                 $first = true;
1774
1775                 foreach ( $rows as $row ) {
1776                         if ( $first ) {
1777                                 $first = false;
1778                         } else {
1779                                 $sql .= ',';
1780                         }
1781
1782                         $sql .= '(' . $this->makeList( $row ) . ')';
1783                 }
1784
1785                 return $this->query( $sql, $fname );
1786         }
1787
1788         /**
1789          * DELETE where the condition is a join
1790          * MySQL does this with a multi-table DELETE syntax, PostgreSQL does it with sub-selects
1791          *
1792          * For safety, an empty $conds will not delete everything. If you want to delete all rows where the
1793          * join condition matches, set $conds='*'
1794          *
1795          * DO NOT put the join condition in $conds
1796          *
1797          * @param $delTable String: The table to delete from.
1798          * @param $joinTable String: The other table.
1799          * @param $delVar String: The variable to join on, in the first table.
1800          * @param $joinVar String: The variable to join on, in the second table.
1801          * @param $conds Array: Condition array of field names mapped to variables, ANDed together in the WHERE clause
1802          * @param $fname String: Calling function name (use __METHOD__) for logs/profiling
1803          */
1804         function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds, $fname = 'DatabaseBase::deleteJoin' ) {
1805                 if ( !$conds ) {
1806                         throw new DBUnexpectedError( $this, 'DatabaseBase::deleteJoin() called with empty $conds' );
1807                 }
1808
1809                 $delTable = $this->tableName( $delTable );
1810                 $joinTable = $this->tableName( $joinTable );
1811                 $sql = "DELETE $delTable FROM $delTable, $joinTable WHERE $delVar=$joinVar ";
1812
1813                 if ( $conds != '*' ) {
1814                         $sql .= ' AND ' . $this->makeList( $conds, LIST_AND );
1815                 }
1816
1817                 return $this->query( $sql, $fname );
1818         }
1819
1820         /**
1821          * Returns the size of a text field, or -1 for "unlimited"
1822          */
1823         function textFieldSize( $table, $field ) {
1824                 $table = $this->tableName( $table );
1825                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
1826                 $res = $this->query( $sql, 'DatabaseBase::textFieldSize' );
1827                 $row = $this->fetchObject( $res );
1828
1829                 $m = array();
1830
1831                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
1832                         $size = $m[1];
1833                 } else {
1834                         $size = -1;
1835                 }
1836
1837                 return $size;
1838         }
1839
1840         /**
1841          * A string to insert into queries to show that they're low-priority, like
1842          * MySQL's LOW_PRIORITY.  If no such feature exists, return an empty
1843          * string and nothing bad should happen.
1844          *
1845          * @return string Returns the text of the low priority option if it is supported, or a blank string otherwise
1846          */
1847         function lowPriorityOption() {
1848                 return '';
1849         }
1850
1851         /**
1852          * DELETE query wrapper
1853          *
1854          * Use $conds == "*" to delete all rows
1855          */
1856         function delete( $table, $conds, $fname = 'DatabaseBase::delete' ) {
1857                 if ( !$conds ) {
1858                         throw new DBUnexpectedError( $this, 'DatabaseBase::delete() called with no conditions' );
1859                 }
1860
1861                 $table = $this->tableName( $table );
1862                 $sql = "DELETE FROM $table";
1863
1864                 if ( $conds != '*' ) {
1865                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1866                 }
1867
1868                 return $this->query( $sql, $fname );
1869         }
1870
1871         /**
1872          * INSERT SELECT wrapper
1873          * $varMap must be an associative array of the form array( 'dest1' => 'source1', ...)
1874          * Source items may be literals rather than field names, but strings should be quoted with DatabaseBase::addQuotes()
1875          * $conds may be "*" to copy the whole table
1876          * srcTable may be an array of tables.
1877          */
1878         function insertSelect( $destTable, $srcTable, $varMap, $conds, $fname = 'DatabaseBase::insertSelect',
1879                 $insertOptions = array(), $selectOptions = array() )
1880         {
1881                 $destTable = $this->tableName( $destTable );
1882
1883                 if ( is_array( $insertOptions ) ) {
1884                         $insertOptions = implode( ' ', $insertOptions );
1885                 }
1886
1887                 if ( !is_array( $selectOptions ) ) {
1888                         $selectOptions = array( $selectOptions );
1889                 }
1890
1891                 list( $startOpts, $useIndex, $tailOpts ) = $this->makeSelectOptions( $selectOptions );
1892
1893                 if ( is_array( $srcTable ) ) {
1894                         $srcTable =  implode( ',', array_map( array( &$this, 'tableName' ), $srcTable ) );
1895                 } else {
1896                         $srcTable = $this->tableName( $srcTable );
1897                 }
1898
1899                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
1900                         " SELECT $startOpts " . implode( ',', $varMap ) .
1901                         " FROM $srcTable $useIndex ";
1902
1903                 if ( $conds != '*' ) {
1904                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1905                 }
1906
1907                 $sql .= " $tailOpts";
1908
1909                 return $this->query( $sql, $fname );
1910         }
1911
1912         /**
1913          * Construct a LIMIT query with optional offset.  This is used for query
1914          * pages.  The SQL should be adjusted so that only the first $limit rows
1915          * are returned.  If $offset is provided as well, then the first $offset
1916          * rows should be discarded, and the next $limit rows should be returned.
1917          * If the result of the query is not ordered, then the rows to be returned
1918          * are theoretically arbitrary.
1919          *
1920          * $sql is expected to be a SELECT, if that makes a difference.  For
1921          * UPDATE, limitResultForUpdate should be used.
1922          *
1923          * The version provided by default works in MySQL and SQLite.  It will very
1924          * likely need to be overridden for most other DBMSes.
1925          *
1926          * @param $sql String: SQL query we will append the limit too
1927          * @param $limit Integer: the SQL limit
1928          * @param $offset Integer the SQL offset (default false)
1929          */
1930         function limitResult( $sql, $limit, $offset = false ) {
1931                 if ( !is_numeric( $limit ) ) {
1932                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
1933                 }
1934
1935                 return "$sql LIMIT "
1936                                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
1937                                 . "{$limit} ";
1938         }
1939
1940         function limitResultForUpdate( $sql, $num ) {
1941                 return $this->limitResult( $sql, $num, 0 );
1942         }
1943
1944         /**
1945          * Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
1946          * within the UNION construct.
1947          * @return Boolean
1948          */
1949         function unionSupportsOrderAndLimit() {
1950                 return true; // True for almost every DB supported
1951         }
1952
1953         /**
1954          * Construct a UNION query
1955          * This is used for providing overload point for other DB abstractions
1956          * not compatible with the MySQL syntax.
1957          * @param $sqls Array: SQL statements to combine
1958          * @param $all Boolean: use UNION ALL
1959          * @return String: SQL fragment
1960          */
1961         function unionQueries( $sqls, $all ) {
1962                 $glue = $all ? ') UNION ALL (' : ') UNION (';
1963                 return '(' . implode( $glue, $sqls ) . ')';
1964         }
1965
1966         /**
1967          * Returns an SQL expression for a simple conditional.  This doesn't need
1968          * to be overridden unless CASE isn't supported in your DBMS.
1969          *
1970          * @param $cond String: SQL expression which will result in a boolean value
1971          * @param $trueVal String: SQL expression to return if true
1972          * @param $falseVal String: SQL expression to return if false
1973          * @return String: SQL fragment
1974          */
1975         function conditional( $cond, $trueVal, $falseVal ) {
1976                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
1977         }
1978
1979         /**
1980          * Returns a comand for str_replace function in SQL query.
1981          * Uses REPLACE() in MySQL
1982          *
1983          * @param $orig String: column to modify
1984          * @param $old String: column to seek
1985          * @param $new String: column to replace with
1986          */
1987         function strreplace( $orig, $old, $new ) {
1988                 return "REPLACE({$orig}, {$old}, {$new})";
1989         }
1990
1991         /**
1992          * Convert a field to an unix timestamp
1993          *
1994          * @param $field String: field name
1995          * @return String: SQL statement
1996          */
1997         public function unixTimestamp( $field ) {
1998                 return "EXTRACT(epoch FROM $field)";
1999         }
2000
2001         /**
2002          * Determines if the last failure was due to a deadlock
2003          * STUB
2004          */
2005         function wasDeadlock() {
2006                 return false;
2007         }
2008
2009         /**
2010          * Determines if the last query error was something that should be dealt
2011          * with by pinging the connection and reissuing the query.
2012          * STUB
2013          */
2014         function wasErrorReissuable() {
2015                 return false;
2016         }
2017
2018         /**
2019          * Determines if the last failure was due to the database being read-only.
2020          * STUB
2021          */
2022         function wasReadOnlyError() {
2023                 return false;
2024         }
2025
2026         /**
2027          * Perform a deadlock-prone transaction.
2028          *
2029          * This function invokes a callback function to perform a set of write
2030          * queries. If a deadlock occurs during the processing, the transaction
2031          * will be rolled back and the callback function will be called again.
2032          *
2033          * Usage:
2034          *   $dbw->deadlockLoop( callback, ... );
2035          *
2036          * Extra arguments are passed through to the specified callback function.
2037          *
2038          * Returns whatever the callback function returned on its successful,
2039          * iteration, or false on error, for example if the retry limit was
2040          * reached.
2041          */
2042         function deadlockLoop() {
2043                 $myFname = 'DatabaseBase::deadlockLoop';
2044
2045                 $this->begin();
2046                 $args = func_get_args();
2047                 $function = array_shift( $args );
2048                 $oldIgnore = $this->ignoreErrors( true );
2049                 $tries = DEADLOCK_TRIES;
2050
2051                 if ( is_array( $function ) ) {
2052                         $fname = $function[0];
2053                 } else {
2054                         $fname = $function;
2055                 }
2056
2057                 do {
2058                         $retVal = call_user_func_array( $function, $args );
2059                         $error = $this->lastError();
2060                         $errno = $this->lastErrno();
2061                         $sql = $this->lastQuery();
2062
2063                         if ( $errno ) {
2064                                 if ( $this->wasDeadlock() ) {
2065                                         # Retry
2066                                         usleep( mt_rand( DEADLOCK_DELAY_MIN, DEADLOCK_DELAY_MAX ) );
2067                                 } else {
2068                                         $this->reportQueryError( $error, $errno, $sql, $fname );
2069                                 }
2070                         }
2071                 } while ( $this->wasDeadlock() && --$tries > 0 );
2072
2073                 $this->ignoreErrors( $oldIgnore );
2074
2075                 if ( $tries <= 0 ) {
2076                         $this->rollback( $myFname );
2077                         $this->reportQueryError( $error, $errno, $sql, $fname );
2078                         return false;
2079                 } else {
2080                         $this->commit( $myFname );
2081                         return $retVal;
2082                 }
2083         }
2084
2085         /**
2086          * Do a SELECT MASTER_POS_WAIT()
2087          *
2088          * @param $pos MySQLMasterPos object
2089          * @param $timeout Integer: the maximum number of seconds to wait for synchronisation
2090          */
2091         function masterPosWait( MySQLMasterPos $pos, $timeout ) {
2092                 $fname = 'DatabaseBase::masterPosWait';
2093                 wfProfileIn( $fname );
2094
2095                 # Commit any open transactions
2096                 if ( $this->mTrxLevel ) {
2097                         $this->commit();
2098                 }
2099
2100                 if ( !is_null( $this->mFakeSlaveLag ) ) {
2101                         $wait = intval( ( $pos->pos - microtime( true ) + $this->mFakeSlaveLag ) * 1e6 );
2102
2103                         if ( $wait > $timeout * 1e6 ) {
2104                                 wfDebug( "Fake slave timed out waiting for $pos ($wait us)\n" );
2105                                 wfProfileOut( $fname );
2106                                 return -1;
2107                         } elseif ( $wait > 0 ) {
2108                                 wfDebug( "Fake slave waiting $wait us\n" );
2109                                 usleep( $wait );
2110                                 wfProfileOut( $fname );
2111                                 return 1;
2112                         } else {
2113                                 wfDebug( "Fake slave up to date ($wait us)\n" );
2114                                 wfProfileOut( $fname );
2115                                 return 0;
2116                         }
2117                 }
2118
2119                 # Call doQuery() directly, to avoid opening a transaction if DBO_TRX is set
2120                 $encFile = $this->addQuotes( $pos->file );
2121                 $encPos = intval( $pos->pos );
2122                 $sql = "SELECT MASTER_POS_WAIT($encFile, $encPos, $timeout)";
2123                 $res = $this->doQuery( $sql );
2124
2125                 if ( $res && $row = $this->fetchRow( $res ) ) {
2126                         wfProfileOut( $fname );
2127                         return $row[0];
2128                 } else {
2129                         wfProfileOut( $fname );
2130                         return false;
2131                 }
2132         }
2133
2134         /**
2135          * Get the position of the master from SHOW SLAVE STATUS
2136          */
2137         function getSlavePos() {
2138                 if ( !is_null( $this->mFakeSlaveLag ) ) {
2139                         $pos = new MySQLMasterPos( 'fake', microtime( true ) - $this->mFakeSlaveLag );
2140                         wfDebug( __METHOD__ . ": fake slave pos = $pos\n" );
2141                         return $pos;
2142                 }
2143
2144                 $res = $this->query( 'SHOW SLAVE STATUS', 'DatabaseBase::getSlavePos' );
2145                 $row = $this->fetchObject( $res );
2146
2147                 if ( $row ) {
2148                         $pos = isset( $row->Exec_master_log_pos ) ? $row->Exec_master_log_pos : $row->Exec_Master_Log_Pos;
2149                         return new MySQLMasterPos( $row->Relay_Master_Log_File, $pos );
2150                 } else {
2151                         return false;
2152                 }
2153         }
2154
2155         /**
2156          * Get the position of the master from SHOW MASTER STATUS
2157          */
2158         function getMasterPos() {
2159                 if ( $this->mFakeMaster ) {
2160                         return new MySQLMasterPos( 'fake', microtime( true ) );
2161                 }
2162
2163                 $res = $this->query( 'SHOW MASTER STATUS', 'DatabaseBase::getMasterPos' );
2164                 $row = $this->fetchObject( $res );
2165
2166                 if ( $row ) {
2167                         return new MySQLMasterPos( $row->File, $row->Position );
2168                 } else {
2169                         return false;
2170                 }
2171         }
2172
2173         /**
2174          * Begin a transaction, committing any previously open transaction
2175          */
2176         function begin( $fname = 'DatabaseBase::begin' ) {
2177                 $this->query( 'BEGIN', $fname );
2178                 $this->mTrxLevel = 1;
2179         }
2180
2181         /**
2182          * End a transaction
2183          */
2184         function commit( $fname = 'DatabaseBase::commit' ) {
2185                 if ( $this->mTrxLevel ) {
2186                         $this->query( 'COMMIT', $fname );
2187                         $this->mTrxLevel = 0;
2188                 }
2189         }
2190
2191         /**
2192          * Rollback a transaction.
2193          * No-op on non-transactional databases.
2194          */
2195         function rollback( $fname = 'DatabaseBase::rollback' ) {
2196                 if ( $this->mTrxLevel ) {
2197                         $this->query( 'ROLLBACK', $fname, true );
2198                         $this->mTrxLevel = 0;
2199                 }
2200         }
2201
2202         /**
2203          * Begin a transaction, committing any previously open transaction
2204          * @deprecated use begin()
2205          */
2206         function immediateBegin( $fname = 'DatabaseBase::immediateBegin' ) {
2207                 wfDeprecated( __METHOD__ );
2208                 $this->begin();
2209         }
2210
2211         /**
2212          * Commit transaction, if one is open
2213          * @deprecated use commit()
2214          */
2215         function immediateCommit( $fname = 'DatabaseBase::immediateCommit' ) {
2216                 wfDeprecated( __METHOD__ );
2217                 $this->commit();
2218         }
2219
2220         /**
2221          * Creates a new table with structure copied from existing table
2222          * Note that unlike most database abstraction functions, this function does not
2223          * automatically append database prefix, because it works at a lower
2224          * abstraction level.
2225          *
2226          * @param $oldName String: name of table whose structure should be copied
2227          * @param $newName String: name of table to be created
2228          * @param $temporary Boolean: whether the new table should be temporary
2229          * @param $fname String: calling function name
2230          * @return Boolean: true if operation was successful
2231          */
2232         function duplicateTableStructure( $oldName, $newName, $temporary = false, $fname = 'DatabaseBase::duplicateTableStructure' ) {
2233                 throw new MWException( 'DatabaseBase::duplicateTableStructure is not implemented in descendant class' );
2234         }
2235
2236         /**
2237          * Return MW-style timestamp used for MySQL schema
2238          */
2239         function timestamp( $ts = 0 ) {
2240                 return wfTimestamp( TS_MW, $ts );
2241         }
2242
2243         /**
2244          * Local database timestamp format or null
2245          */
2246         function timestampOrNull( $ts = null ) {
2247                 if ( is_null( $ts ) ) {
2248                         return null;
2249                 } else {
2250                         return $this->timestamp( $ts );
2251                 }
2252         }
2253
2254         /**
2255          * @todo document
2256          */
2257         function resultObject( $result ) {
2258                 if ( empty( $result ) ) {
2259                         return false;
2260                 } elseif ( $result instanceof ResultWrapper ) {
2261                         return $result;
2262                 } elseif ( $result === true ) {
2263                         // Successful write query
2264                         return $result;
2265                 } else {
2266                         return new ResultWrapper( $this, $result );
2267                 }
2268         }
2269
2270         /**
2271          * Return aggregated value alias
2272          */
2273         function aggregateValue ( $valuedata, $valuename = 'value' ) {
2274                 return $valuename;
2275         }
2276
2277         /**
2278          * Ping the server and try to reconnect if it there is no connection
2279          *
2280          * @return bool Success or failure
2281          */
2282         function ping() {
2283                 # Stub.  Not essential to override.
2284                 return true;
2285         }
2286
2287         /**
2288          * Get slave lag.
2289          * Currently supported only by MySQL
2290          * @return Database replication lag in seconds
2291          */
2292         function getLag() {
2293                 return intval( $this->mFakeSlaveLag );
2294         }
2295
2296         /**
2297          * Get status information from SHOW STATUS in an associative array
2298          */
2299         function getStatus( $which = "%" ) {
2300                 $res = $this->query( "SHOW STATUS LIKE '{$which}'" );
2301                 $status = array();
2302
2303                 foreach ( $res as $row ) {
2304                         $status[$row->Variable_name] = $row->Value;
2305                 }
2306
2307                 return $status;
2308         }
2309
2310         /**
2311          * Return the maximum number of items allowed in a list, or 0 for unlimited.
2312          */
2313         function maxListLen() {
2314                 return 0;
2315         }
2316
2317         function encodeBlob( $b ) {
2318                 return $b;
2319         }
2320
2321         function decodeBlob( $b ) {
2322                 return $b;
2323         }
2324
2325         /**
2326          * Override database's default connection timeout.  May be useful for very
2327          * long batch queries such as full-wiki dumps, where a single query reads
2328          * out over hours or days.  May or may not be necessary for non-MySQL
2329          * databases.  For most purposes, leaving it as a no-op should be fine.
2330          *
2331          * @param $timeout Integer in seconds
2332          */
2333         public function setTimeout( $timeout ) {}
2334
2335         /**
2336          * Read and execute SQL commands from a file.
2337          * Returns true on success, error string or exception on failure (depending on object's error ignore settings)
2338          * @param $filename String: File name to open
2339          * @param $lineCallback Callback: Optional function called before reading each line
2340          * @param $resultCallback Callback: Optional function called for each MySQL result
2341          * @param $fname String: Calling function name or false if name should be generated dynamically
2342          *              using $filename
2343          */
2344         function sourceFile( $filename, $lineCallback = false, $resultCallback = false, $fname = false ) {
2345                 $fp = fopen( $filename, 'r' );
2346
2347                 if ( false === $fp ) {
2348                         if ( !defined( "MEDIAWIKI_INSTALL" ) )
2349                                 throw new MWException( "Could not open \"{$filename}\".\n" );
2350                         else
2351                                 return "Could not open \"{$filename}\".\n";
2352                 }
2353
2354                 if ( !$fname ) {
2355                         $fname = __METHOD__ . "( $filename )";
2356                 }
2357
2358                 try {
2359                         $error = $this->sourceStream( $fp, $lineCallback, $resultCallback, $fname );
2360                 }
2361                 catch ( MWException $e ) {
2362                         if ( defined( "MEDIAWIKI_INSTALL" ) ) {
2363                                 $error = $e->getMessage();
2364                         } else {
2365                                 fclose( $fp );
2366                                 throw $e;
2367                         }
2368                 }
2369
2370                 fclose( $fp );
2371
2372                 return $error;
2373         }
2374
2375         /**
2376          * Get the full path of a patch file. Originally based on archive()
2377          * from updaters.inc. Keep in mind this always returns a patch, as
2378          * it fails back to MySQL if no DB-specific patch can be found
2379          *
2380          * @param $patch String The name of the patch, like patch-something.sql
2381          * @return String Full path to patch file
2382          */
2383         public function patchPath( $patch ) {
2384                 global $IP;
2385
2386                 $dbType = $this->getType();
2387                 if ( file_exists( "$IP/maintenance/$dbType/archives/$patch" ) ) {
2388                         return "$IP/maintenance/$dbType/archives/$patch";
2389                 } else {
2390                         return "$IP/maintenance/archives/$patch";
2391                 }
2392         }
2393
2394         /**
2395          * Read and execute commands from an open file handle
2396          * Returns true on success, error string or exception on failure (depending on object's error ignore settings)
2397          * @param $fp String: File handle
2398          * @param $lineCallback Callback: Optional function called before reading each line
2399          * @param $resultCallback Callback: Optional function called for each MySQL result
2400          * @param $fname String: Calling function name
2401          */
2402         function sourceStream( $fp, $lineCallback = false, $resultCallback = false, $fname = 'DatabaseBase::sourceStream' ) {
2403                 $cmd = "";
2404                 $done = false;
2405                 $dollarquote = false;
2406
2407                 while ( ! feof( $fp ) ) {
2408                         if ( $lineCallback ) {
2409                                 call_user_func( $lineCallback );
2410                         }
2411
2412                         $line = trim( fgets( $fp, 1024 ) );
2413                         $sl = strlen( $line ) - 1;
2414
2415                         if ( $sl < 0 ) {
2416                                 continue;
2417                         }
2418
2419                         if ( '-' == $line { 0 } && '-' == $line { 1 } ) {
2420                                 continue;
2421                         }
2422
2423                         # # Allow dollar quoting for function declarations
2424                         if ( substr( $line, 0, 4 ) == '$mw$' ) {
2425                                 if ( $dollarquote ) {
2426                                         $dollarquote = false;
2427                                         $done = true;
2428                                 }
2429                                 else {
2430                                         $dollarquote = true;
2431                                 }
2432                         }
2433                         else if ( !$dollarquote ) {
2434                                 if ( ';' == $line { $sl } && ( $sl < 2 || ';' != $line { $sl - 1 } ) ) {
2435                                         $done = true;
2436                                         $line = substr( $line, 0, $sl );
2437                                 }
2438                         }
2439
2440                         if ( $cmd != '' ) {
2441                                 $cmd .= ' ';
2442                         }
2443
2444                         $cmd .= "$line\n";
2445
2446                         if ( $done ) {
2447                                 $cmd = str_replace( ';;', ";", $cmd );
2448                                 $cmd = $this->replaceVars( $cmd );
2449                                 $res = $this->query( $cmd, $fname );
2450
2451                                 if ( $resultCallback ) {
2452                                         call_user_func( $resultCallback, $res, $this );
2453                                 }
2454
2455                                 if ( false === $res ) {
2456                                         $err = $this->lastError();
2457                                         return "Query \"{$cmd}\" failed with error code \"$err\".\n";
2458                                 }
2459
2460                                 $cmd = '';
2461                                 $done = false;
2462                         }
2463                 }
2464
2465                 return true;
2466         }
2467
2468         /**
2469          * Replace variables in sourced SQL
2470          */
2471         protected function replaceVars( $ins ) {
2472                 $varnames = array(
2473                         'wgDBserver', 'wgDBname', 'wgDBintlname', 'wgDBuser',
2474                         'wgDBpassword', 'wgDBsqluser', 'wgDBsqlpassword',
2475                         'wgDBadminuser', 'wgDBadminpassword', 'wgDBTableOptions',
2476                 );
2477
2478                 // Ordinary variables
2479                 foreach ( $varnames as $var ) {
2480                         if ( isset( $GLOBALS[$var] ) ) {
2481                                 $val = addslashes( $GLOBALS[$var] ); // FIXME: safety check?
2482                                 $ins = str_replace( '{$' . $var . '}', $val, $ins );
2483                                 $ins = str_replace( '/*$' . $var . '*/`', '`' . $val, $ins );
2484                                 $ins = str_replace( '/*$' . $var . '*/', $val, $ins );
2485                         }
2486                 }
2487
2488                 // Table prefixes
2489                 $ins = preg_replace_callback( '!/\*(?:\$wgDBprefix|_)\*/([a-zA-Z_0-9]*)!',
2490                         array( $this, 'tableNameCallback' ), $ins );
2491
2492                 // Index names
2493                 $ins = preg_replace_callback( '!/\*i\*/([a-zA-Z_0-9]*)!',
2494                         array( $this, 'indexNameCallback' ), $ins );
2495
2496                 return $ins;
2497         }
2498
2499         /**
2500          * Table name callback
2501          * @private
2502          */
2503         protected function tableNameCallback( $matches ) {
2504                 return $this->tableName( $matches[1] );
2505         }
2506
2507         /**
2508          * Index name callback
2509          */
2510         protected function indexNameCallback( $matches ) {
2511                 return $this->indexName( $matches[1] );
2512         }
2513
2514         /**
2515          * Build a concatenation list to feed into a SQL query
2516          * @param $stringList Array: list of raw SQL expressions; caller is responsible for any quoting
2517          * @return String
2518          */
2519         function buildConcat( $stringList ) {
2520                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
2521         }
2522
2523         /**
2524          * Acquire a named lock
2525          *
2526          * Abstracted from Filestore::lock() so child classes can implement for
2527          * their own needs.
2528          *
2529          * @param $lockName String: name of lock to aquire
2530          * @param $method String: name of method calling us
2531          * @param $timeout Integer: timeout
2532          * @return Boolean
2533          */
2534         public function lock( $lockName, $method, $timeout = 5 ) {
2535                 return true;
2536         }
2537
2538         /**
2539          * Release a lock.
2540          *
2541          * @param $lockName String: Name of lock to release
2542          * @param $method String: Name of method calling us
2543          *
2544          * @return Returns 1 if the lock was released, 0 if the lock was not established
2545          * by this thread (in which case the lock is not released), and NULL if the named
2546          * lock did not exist
2547          */
2548         public function unlock( $lockName, $method ) {
2549                 return true;
2550         }
2551
2552         /**
2553          * Lock specific tables
2554          *
2555          * @param $read Array of tables to lock for read access
2556          * @param $write Array of tables to lock for write access
2557          * @param $method String name of caller
2558          * @param $lowPriority bool Whether to indicate writes to be LOW PRIORITY
2559          */
2560         public function lockTables( $read, $write, $method, $lowPriority = true ) {
2561                 return true;
2562         }
2563
2564         /**
2565          * Unlock specific tables
2566          *
2567          * @param $method String the caller
2568          */
2569         public function unlockTables( $method ) {
2570                 return true;
2571         }
2572
2573         /**
2574          * Get search engine class. All subclasses of this need to implement this
2575          * if they wish to use searching.
2576          *
2577          * @return String
2578          */
2579         public function getSearchEngine() {
2580                 return 'SearchEngineDummy';
2581         }
2582
2583         /**
2584          * Allow or deny "big selects" for this session only. This is done by setting
2585          * the sql_big_selects session variable.
2586          *
2587          * This is a MySQL-specific feature.
2588          *
2589          * @param $value Mixed: true for allow, false for deny, or "default" to restore the initial value
2590          */
2591         public function setBigSelects( $value = true ) {
2592                 // no-op
2593         }
2594 }
2595
2596 /******************************************************************************
2597  * Utility classes
2598  *****************************************************************************/
2599
2600 /**
2601  * Utility class.
2602  * @ingroup Database
2603  */
2604 class DBObject {
2605         public $mData;
2606
2607         function __construct( $data ) {
2608                 $this->mData = $data;
2609         }
2610
2611         function isLOB() {
2612                 return false;
2613         }
2614
2615         function data() {
2616                 return $this->mData;
2617         }
2618 }
2619
2620 /**
2621  * Utility class
2622  * @ingroup Database
2623  *
2624  * This allows us to distinguish a blob from a normal string and an array of strings
2625  */
2626 class Blob {
2627         private $mData;
2628
2629         function __construct( $data ) {
2630                 $this->mData = $data;
2631         }
2632
2633         function fetch() {
2634                 return $this->mData;
2635         }
2636 }
2637
2638 /**
2639  * Base for all database-specific classes representing information about database fields
2640  * @ingroup Database
2641  */
2642 interface Field {
2643         /**
2644          * Field name
2645          * @return string
2646          */
2647         function name();
2648
2649         /**
2650          * Name of table this field belongs to
2651          * @return string
2652          */
2653         function tableName();
2654
2655         /**
2656          * Database type
2657          * @return string
2658          */
2659         function type();
2660
2661         /**
2662          * Whether this field can store NULL values
2663          * @return bool
2664          */
2665         function isNullable();
2666 }
2667
2668 /******************************************************************************
2669  * Error classes
2670  *****************************************************************************/
2671
2672 /**
2673  * Database error base class
2674  * @ingroup Database
2675  */
2676 class DBError extends MWException {
2677         public $db;
2678
2679         /**
2680          * Construct a database error
2681          * @param $db Database object which threw the error
2682          * @param $error A simple error message to be used for debugging
2683          */
2684         function __construct( DatabaseBase &$db, $error ) {
2685                 $this->db =& $db;
2686                 parent::__construct( $error );
2687         }
2688
2689         function getText() {
2690                 global $wgShowDBErrorBacktrace;
2691
2692                 $s = $this->getMessage() . "\n";
2693
2694                 if ( $wgShowDBErrorBacktrace ) {
2695                         $s .= "Backtrace:\n" . $this->getTraceAsString() . "\n";
2696                 }
2697
2698                 return $s;
2699         }
2700 }
2701
2702 /**
2703  * @ingroup Database
2704  */
2705 class DBConnectionError extends DBError {
2706         public $error;
2707
2708         function __construct( DatabaseBase &$db, $error = 'unknown error' ) {
2709                 $msg = 'DB connection error';
2710
2711                 if ( trim( $error ) != '' ) {
2712                         $msg .= ": $error";
2713                 }
2714
2715                 $this->error = $error;
2716
2717                 parent::__construct( $db, $msg );
2718         }
2719
2720         function useOutputPage() {
2721                 // Not likely to work
2722                 return false;
2723         }
2724
2725         function useMessageCache() {
2726                 // Not likely to work
2727                 return false;
2728         }
2729
2730         function getLogMessage() {
2731                 # Don't send to the exception log
2732                 return false;
2733         }
2734
2735         function getPageTitle() {
2736                 global $wgSitename, $wgLang;
2737
2738                 $header = "$wgSitename has a problem";
2739
2740                 if ( $wgLang instanceof Language ) {
2741                         $header = htmlspecialchars( $wgLang->getMessage( 'dberr-header' ) );
2742                 }
2743
2744                 return $header;
2745         }
2746
2747         function getHTML() {
2748                 global $wgLang, $wgMessageCache, $wgUseFileCache, $wgShowDBErrorBacktrace;
2749
2750                 $sorry = 'Sorry! This site is experiencing technical difficulties.';
2751                 $again = 'Try waiting a few minutes and reloading.';
2752                 $info  = '(Can\'t contact the database server: $1)';
2753
2754                 if ( $wgLang instanceof Language ) {
2755                         $sorry = htmlspecialchars( $wgLang->getMessage( 'dberr-problems' ) );
2756                         $again = htmlspecialchars( $wgLang->getMessage( 'dberr-again' ) );
2757                         $info  = htmlspecialchars( $wgLang->getMessage( 'dberr-info' ) );
2758                 }
2759
2760                 # No database access
2761                 if ( is_object( $wgMessageCache ) ) {
2762                         $wgMessageCache->disable();
2763                 }
2764
2765                 if ( trim( $this->error ) == '' ) {
2766                         $this->error = $this->db->getProperty( 'mServer' );
2767                 }
2768
2769                 $noconnect = "<p><strong>$sorry</strong><br />$again</p><p><small>$info</small></p>";
2770                 $text = str_replace( '$1', $this->error, $noconnect );
2771
2772                 if ( $wgShowDBErrorBacktrace ) {
2773                         $text .= '<p>Backtrace:</p><p>' . nl2br( htmlspecialchars( $this->getTraceAsString() ) );
2774                 }
2775
2776                 $extra = $this->searchForm();
2777
2778                 if ( $wgUseFileCache ) {
2779                         try {
2780                                 $cache = $this->fileCachedPage();
2781                                 # Cached version on file system?
2782                                 if ( $cache !== null ) {
2783                                         # Hack: extend the body for error messages
2784                                         $cache = str_replace( array( '</html>', '</body>' ), '', $cache );
2785                                         # Add cache notice...
2786                                         $cachederror = "This is a cached copy of the requested page, and may not be up to date. ";
2787
2788                                         # Localize it if possible...
2789                                         if ( $wgLang instanceof Language ) {
2790                                                 $cachederror = htmlspecialchars( $wgLang->getMessage( 'dberr-cachederror' ) );
2791                                         }
2792
2793                                         $warning = "<div style='color:red;font-size:150%;font-weight:bold;'>$cachederror</div>";
2794
2795                                         # Output cached page with notices on bottom and re-close body
2796                                         return "{$cache}{$warning}<hr />$text<hr />$extra</body></html>";
2797                                 }
2798                         } catch ( MWException $e ) {
2799                                 // Do nothing, just use the default page
2800                         }
2801                 }
2802
2803                 # Headers needed here - output is just the error message
2804                 return $this->htmlHeader() . "$text<hr />$extra" . $this->htmlFooter();
2805         }
2806
2807         function searchForm() {
2808                 global $wgSitename, $wgServer, $wgLang;
2809
2810                 $usegoogle = "You can try searching via Google in the meantime.";
2811                 $outofdate = "Note that their indexes of our content may be out of date.";
2812                 $googlesearch = "Search";
2813
2814                 if ( $wgLang instanceof Language ) {
2815                         $usegoogle = htmlspecialchars( $wgLang->getMessage( 'dberr-usegoogle' ) );
2816                         $outofdate = htmlspecialchars( $wgLang->getMessage( 'dberr-outofdate' ) );
2817                         $googlesearch  = htmlspecialchars( $wgLang->getMessage( 'searchbutton' ) );
2818                 }
2819
2820                 $search = htmlspecialchars( @$_REQUEST['search'] );
2821
2822                 $server = htmlspecialchars( $wgServer );
2823                 $sitename = htmlspecialchars( $wgSitename );
2824
2825                 $trygoogle = <<<EOT
2826 <div style="margin: 1.5em">$usegoogle<br />
2827 <small>$outofdate</small></div>
2828 <!-- SiteSearch Google -->
2829 <form method="get" action="http://www.google.com/search" id="googlesearch">
2830         <input type="hidden" name="domains" value="$server" />
2831         <input type="hidden" name="num" value="50" />
2832         <input type="hidden" name="ie" value="UTF-8" />
2833         <input type="hidden" name="oe" value="UTF-8" />
2834
2835         <input type="text" name="q" size="31" maxlength="255" value="$search" />
2836         <input type="submit" name="btnG" value="$googlesearch" />
2837   <div>
2838         <input type="radio" name="sitesearch" id="gwiki" value="$server" checked="checked" /><label for="gwiki">$sitename</label>
2839         <input type="radio" name="sitesearch" id="gWWW" value="" /><label for="gWWW">WWW</label>
2840   </div>
2841 </form>
2842 <!-- SiteSearch Google -->
2843 EOT;
2844                 return $trygoogle;
2845         }
2846
2847         function fileCachedPage() {
2848                 global $wgTitle, $title, $wgLang, $wgOut;
2849
2850                 if ( $wgOut->isDisabled() ) {
2851                         return; // Done already?
2852                 }
2853
2854                 $mainpage = 'Main Page';
2855
2856                 if ( $wgLang instanceof Language ) {
2857                         $mainpage    = htmlspecialchars( $wgLang->getMessage( 'mainpage' ) );
2858                 }
2859
2860                 if ( $wgTitle ) {
2861                         $t =& $wgTitle;
2862                 } elseif ( $title ) {
2863                         $t = Title::newFromURL( $title );
2864                 } else {
2865                         $t = Title::newFromText( $mainpage );
2866                 }
2867
2868                 $cache = new HTMLFileCache( $t );
2869                 if ( $cache->isFileCached() ) {
2870                         return $cache->fetchPageText();
2871                 } else {
2872                         return '';
2873                 }
2874         }
2875
2876         function htmlBodyOnly() {
2877                 return true;
2878         }
2879 }
2880
2881 /**
2882  * @ingroup Database
2883  */
2884 class DBQueryError extends DBError {
2885         public $error, $errno, $sql, $fname;
2886
2887         function __construct( DatabaseBase &$db, $error, $errno, $sql, $fname ) {
2888                 $message = "A database error has occurred.  Did you forget to run maintenance/update.php after upgrading?  See: http://www.mediawiki.org/wiki/Manual:Upgrading#Run_the_update_script\n" .
2889                   "Query: $sql\n" .
2890                   "Function: $fname\n" .
2891                   "Error: $errno $error\n";
2892
2893                 parent::__construct( $db, $message );
2894
2895                 $this->error = $error;
2896                 $this->errno = $errno;
2897                 $this->sql = $sql;
2898                 $this->fname = $fname;
2899         }
2900
2901         function getText() {
2902                 global $wgShowDBErrorBacktrace;
2903
2904                 if ( $this->useMessageCache() ) {
2905                         $s = wfMsg( 'dberrortextcl', htmlspecialchars( $this->getSQL() ),
2906                                 htmlspecialchars( $this->fname ), $this->errno, htmlspecialchars( $this->error ) ) . "\n";
2907
2908                         if ( $wgShowDBErrorBacktrace ) {
2909                                 $s .= "Backtrace:\n" . $this->getTraceAsString() . "\n";
2910                         }
2911
2912                         return $s;
2913                 } else {
2914                         return parent::getText();
2915                 }
2916         }
2917
2918         function getSQL() {
2919                 global $wgShowSQLErrors;
2920
2921                 if ( !$wgShowSQLErrors ) {
2922                         return $this->msg( 'sqlhidden', 'SQL hidden' );
2923                 } else {
2924                         return $this->sql;
2925                 }
2926         }
2927
2928         function getLogMessage() {
2929                 # Don't send to the exception log
2930                 return false;
2931         }
2932
2933         function getPageTitle() {
2934                 return $this->msg( 'databaseerror', 'Database error' );
2935         }
2936
2937         function getHTML() {
2938                 global $wgShowDBErrorBacktrace;
2939
2940                 if ( $this->useMessageCache() ) {
2941                         $s = wfMsgNoDB( 'dberrortext', htmlspecialchars( $this->getSQL() ),
2942                           htmlspecialchars( $this->fname ), $this->errno, htmlspecialchars( $this->error ) );
2943                 } else {
2944                         $s = nl2br( htmlspecialchars( $this->getMessage() ) );
2945                 }
2946
2947                 if ( $wgShowDBErrorBacktrace ) {
2948                         $s .= '<p>Backtrace:</p><p>' . nl2br( htmlspecialchars( $this->getTraceAsString() ) );
2949                 }
2950
2951                 return $s;
2952         }
2953 }
2954
2955 /**
2956  * @ingroup Database
2957  */
2958 class DBUnexpectedError extends DBError {}
2959
2960
2961 /**
2962  * Result wrapper for grabbing data queried by someone else
2963  * @ingroup Database
2964  */
2965 class ResultWrapper implements Iterator {
2966         var $db, $result, $pos = 0, $currentRow = null;
2967
2968         /**
2969          * Create a new result object from a result resource and a Database object
2970          */
2971         function __construct( $database, $result ) {
2972                 $this->db = $database;
2973
2974                 if ( $result instanceof ResultWrapper ) {
2975                         $this->result = $result->result;
2976                 } else {
2977                         $this->result = $result;
2978                 }
2979         }
2980
2981         /**
2982          * Get the number of rows in a result object
2983          */
2984         function numRows() {
2985                 return $this->db->numRows( $this );
2986         }
2987
2988         /**
2989          * Fetch the next row from the given result object, in object form.
2990          * Fields can be retrieved with $row->fieldname, with fields acting like
2991          * member variables.
2992          *
2993          * @return MySQL row object
2994          * @throws DBUnexpectedError Thrown if the database returns an error
2995          */
2996         function fetchObject() {
2997                 return $this->db->fetchObject( $this );
2998         }
2999
3000         /**
3001          * Fetch the next row from the given result object, in associative array
3002          * form.  Fields are retrieved with $row['fieldname'].
3003          *
3004          * @return MySQL row object
3005          * @throws DBUnexpectedError Thrown if the database returns an error
3006          */
3007         function fetchRow() {
3008                 return $this->db->fetchRow( $this );
3009         }
3010
3011         /**
3012          * Free a result object
3013          */
3014         function free() {
3015                 $this->db->freeResult( $this );
3016                 unset( $this->result );
3017                 unset( $this->db );
3018         }
3019
3020         /**
3021          * Change the position of the cursor in a result object
3022          * See mysql_data_seek()
3023          */
3024         function seek( $row ) {
3025                 $this->db->dataSeek( $this, $row );
3026         }
3027
3028         /*********************
3029          * Iterator functions
3030          * Note that using these in combination with the non-iterator functions
3031          * above may cause rows to be skipped or repeated.
3032          */
3033
3034         function rewind() {
3035                 if ( $this->numRows() ) {
3036                         $this->db->dataSeek( $this, 0 );
3037                 }
3038                 $this->pos = 0;
3039                 $this->currentRow = null;
3040         }
3041
3042         function current() {
3043                 if ( is_null( $this->currentRow ) ) {
3044                         $this->next();
3045                 }
3046                 return $this->currentRow;
3047         }
3048
3049         function key() {
3050                 return $this->pos;
3051         }
3052
3053         function next() {
3054                 $this->pos++;
3055                 $this->currentRow = $this->fetchObject();
3056                 return $this->currentRow;
3057         }
3058
3059         function valid() {
3060                 return $this->current() !== false;
3061         }
3062 }
3063
3064 /**
3065  * Overloads the relevant methods of the real ResultsWrapper so it
3066  * doesn't go anywhere near an actual database.
3067  */
3068 class FakeResultWrapper extends ResultWrapper {
3069         var $result     = array();
3070         var $db         = null; // And it's going to stay that way :D
3071         var $pos        = 0;
3072         var $currentRow = null;
3073
3074         function __construct( $array ) {
3075                 $this->result = $array;
3076         }
3077
3078         function numRows() {
3079                 return count( $this->result );
3080         }
3081
3082         function fetchRow() {
3083                 $this->currentRow = $this->result[$this->pos++];
3084                 return $this->currentRow;
3085         }
3086
3087         function seek( $row ) {
3088                 $this->pos = $row;
3089         }
3090
3091         function free() {}
3092
3093         // Callers want to be able to access fields with $this->fieldName
3094         function fetchObject() {
3095                 $this->currentRow = $this->result[$this->pos++];
3096                 return (object)$this->currentRow;
3097         }
3098
3099         function rewind() {
3100                 $this->pos = 0;
3101                 $this->currentRow = null;
3102         }
3103 }
3104
3105 /**
3106  * Used by DatabaseBase::buildLike() to represent characters that have special meaning in SQL LIKE clauses
3107  * and thus need no escaping. Don't instantiate it manually, use DatabaseBase::anyChar() and anyString() instead.
3108  */
3109 class LikeMatch {
3110         private $str;
3111
3112         public function __construct( $s ) {
3113                 $this->str = $s;
3114         }
3115
3116         public function toString() {
3117                 return $this->str;
3118         }
3119 }