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 the number of rows affected by the last write query
 153          * @see http://www.php.net/mysql_affected_rows
 154          *
 155          * @return int
 156          */
 157         public function affectedRows();
 158
 159         /**
 160          * Wrapper for addslashes()
 161          *
 162          * @param $s string: to be slashed.
 163          * @return string: slashed string.
 164          */
 165         public function strencode( $s );
 166
 167         /**
 168          * Returns a wikitext link to the DB's website, e.g.,
 169          *     return "[http://www.mysql.com/ MySQL]";
 170          * Should at least contain plain text, if for some reason
 171          * your database has no website.
 172          *
 173          * @return string: wikitext of a link to the server software's web site
 174          */
 175         public static function getSoftwareLink();
 176
 177         /**
 178          * A string describing the current software version, like from
 179          * mysql_get_server_info().
 180          *
 181          * @return string: Version information from the database server.
 182          */
 183         public function getServerVersion();
 184
 185         /**
 186          * A string describing the current software version, and possibly
 187          * other details in a user-friendly way.  Will be listed on Special:Version, etc.
 188          * Use getServerVersion() to get machine-friendly information.
 189          *
 190          * @return string: Version information from the database server
 191          */
 192         public function getServerInfo();
 193 }
 194
 195 /**
 196  * Database abstraction object
 197  * @ingroup Database
 198  */
 199 abstract class DatabaseBase implements DatabaseType {
 200
 201 # ------------------------------------------------------------------------------
 202 # Variables
 203 # ------------------------------------------------------------------------------
 204
 205         protected $mLastQuery = '';
 206         protected $mDoneWrites = false;
 207         protected $mPHPError = false;
 208
 209         protected $mServer, $mUser, $mPassword, $mConn = null, $mDBname;
 210         protected $mOpened = false;
 211
 212         protected $mTablePrefix;
 213         protected $mFlags;
 214         protected $mTrxLevel = 0;
 215         protected $mErrorCount = 0;
 216         protected $mLBInfo = array();
 217         protected $mFakeSlaveLag = null, $mFakeMaster = false;
 218         protected $mDefaultBigSelects = null;
 219
 220 # ------------------------------------------------------------------------------
 221 # Accessors
 222 # ------------------------------------------------------------------------------
 223         # These optionally set a variable and return the previous state
 224
 225         /**
 226          * A string describing the current software version, and possibly
 227          * other details in a user-friendly way.  Will be listed on Special:Version, etc.
 228          * Use getServerVersion() to get machine-friendly information.
 229          *
 230          * @return string: Version information from the database server
 231          */
 232         public function getServerInfo() {
 233                 return $this->getServerVersion();
 234         }
 235
 236         /**
 237          * Boolean, controls output of large amounts of debug information
 238          */
 239         function debug( $debug = null ) {
 240                 return wfSetBit( $this->mFlags, DBO_DEBUG, $debug );
 241         }
 242
 243         /**
 244          * Turns buffering of SQL result sets on (true) or off (false).
 245          * Default is "on" and it should not be changed without good reasons.
 246          */
 247         function bufferResults( $buffer = null ) {
 248                 if ( is_null( $buffer ) ) {
 249                         return !(bool)( $this->mFlags & DBO_NOBUFFER );
 250                 } else {
 251                         return !wfSetBit( $this->mFlags, DBO_NOBUFFER, !$buffer );
 252                 }
 253         }
 254
 255         /**
 256          * Turns on (false) or off (true) the automatic generation and sending
 257          * of a "we're sorry, but there has been a database error" page on
 258          * database errors. Default is on (false). When turned off, the
 259          * code should use lastErrno() and lastError() to handle the
 260          * situation as appropriate.
 261          */
 262         function ignoreErrors( $ignoreErrors = null ) {
 263                 return wfSetBit( $this->mFlags, DBO_IGNORE, $ignoreErrors );
 264         }
 265
 266         /**
 267          * The current depth of nested transactions
 268          * @param $level Integer: , default NULL.
 269          */
 270         function trxLevel( $level = null ) {
 271                 return wfSetVar( $this->mTrxLevel, $level );
 272         }
 273
 274         /**
 275          * Number of errors logged, only useful when errors are ignored
 276          */
 277         function errorCount( $count = null ) {
 278                 return wfSetVar( $this->mErrorCount, $count );
 279         }
 280
 281         function tablePrefix( $prefix = null ) {
 282                 return wfSetVar( $this->mTablePrefix, $prefix );
 283         }
 284
 285         /**
 286          * Properties passed down from the server info array of the load balancer
 287          */
 288         function getLBInfo( $name = null ) {
 289                 if ( is_null( $name ) ) {
 290                         return $this->mLBInfo;
 291                 } else {
 292                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 293                                 return $this->mLBInfo[$name];
 294                         } else {
 295                                 return null;
 296                         }
 297                 }
 298         }
 299
 300         function setLBInfo( $name, $value = null ) {
 301                 if ( is_null( $value ) ) {
 302                         $this->mLBInfo = $name;
 303                 } else {
 304                         $this->mLBInfo[$name] = $value;
 305                 }
 306         }
 307
 308         /**
 309          * Set lag time in seconds for a fake slave
 310          */
 311         function setFakeSlaveLag( $lag ) {
 312                 $this->mFakeSlaveLag = $lag;
 313         }
 314
 315         /**
 316          * Make this connection a fake master
 317          */
 318         function setFakeMaster( $enabled = true ) {
 319                 $this->mFakeMaster = $enabled;
 320         }
 321
 322         /**
 323          * Returns true if this database supports (and uses) cascading deletes
 324          */
 325         function cascadingDeletes() {
 326                 return false;
 327         }
 328
 329         /**
 330          * Returns true if this database supports (and uses) triggers (e.g. on the page table)
 331          */
 332         function cleanupTriggers() {
 333                 return false;
 334         }
 335
 336         /**
 337          * Returns true if this database is strict about what can be put into an IP field.
 338          * Specifically, it uses a NULL value instead of an empty string.
 339          */
 340         function strictIPs() {
 341                 return false;
 342         }
 343
 344         /**
 345          * Returns true if this database uses timestamps rather than integers
 346         */
 347         function realTimestamps() {
 348                 return false;
 349         }
 350
 351         /**
 352          * Returns true if this database does an implicit sort when doing GROUP BY
 353          */
 354         function implicitGroupby() {
 355                 return true;
 356         }
 357
 358         /**
 359          * Returns true if this database does an implicit order by when the column has an index
 360          * For example: SELECT page_title FROM page LIMIT 1
 361          */
 362         function implicitOrderby() {
 363                 return true;
 364         }
 365
 366         /**
 367          * Returns true if this database requires that SELECT DISTINCT queries require that all
 368            ORDER BY expressions occur in the SELECT list per the SQL92 standard
 369          */
 370         function standardSelectDistinct() {
 371                 return true;
 372         }
 373
 374         /**
 375          * Returns true if this database can do a native search on IP columns
 376          * e.g. this works as expected: .. WHERE rc_ip = '127.42.12.102/32';
 377          */
 378         function searchableIPs() {
 379                 return false;
 380         }
 381
 382         /**
 383          * Returns true if this database can use functional indexes
 384          */
 385         function functionalIndexes() {
 386                 return false;
 387         }
 388
 389         /**
 390          * Return the last query that went through DatabaseBase::query()
 391          * @return String
 392          */
 393         function lastQuery() { return $this->mLastQuery; }
 394
 395
 396         /**
 397          * Returns true if the connection may have been used for write queries.
 398          * Should return true if unsure.
 399          */
 400         function doneWrites() { return $this->mDoneWrites; }
 401
 402         /**
 403          * Is a connection to the database open?
 404          * @return Boolean
 405          */
 406         function isOpen() { return $this->mOpened; }
 407
 408         /**
 409          * Set a flag for this connection
 410          *
 411          * @param $flag Integer: DBO_* constants from Defines.php:
 412          *   - DBO_DEBUG: output some debug info (same as debug())
 413          *   - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
 414          *   - DBO_IGNORE: ignore errors (same as ignoreErrors())
 415          *   - DBO_TRX: automatically start transactions
 416          *   - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
 417          *       and removes it in command line mode
 418          *   - DBO_PERSISTENT: use persistant database connection
 419          */
 420         function setFlag( $flag ) {
 421                 $this->mFlags |= $flag;
 422         }
 423
 424         /**
 425          * Clear a flag for this connection
 426          *
 427          * @param $flag: same as setFlag()'s $flag param
 428          */
 429         function clearFlag( $flag ) {
 430                 $this->mFlags &= ~$flag;
 431         }
 432
 433         /**
 434          * Returns a boolean whether the flag $flag is set for this connection
 435          *
 436          * @param $flag: same as setFlag()'s $flag param
 437          * @return Boolean
 438          */
 439         function getFlag( $flag ) {
 440                 return !!( $this->mFlags & $flag );
 441         }
 442
 443         /**
 444          * General read-only accessor
 445          */
 446         function getProperty( $name ) {
 447                 return $this->$name;
 448         }
 449
 450         function getWikiID() {
 451                 if ( $this->mTablePrefix ) {
 452                         return "{$this->mDBname}-{$this->mTablePrefix}";
 453                 } else {
 454                         return $this->mDBname;
 455                 }
 456         }
 457
 458         /**
 459          * Return a path to the DBMS-specific schema, otherwise default to tables.sql
 460          */
 461         public function getSchema() {
 462                 global $IP;
 463                 if ( file_exists( "$IP/maintenance/" . $this->getType() . "/tables.sql" ) ) {
 464                         return "$IP/maintenance/" . $this->getType() . "/tables.sql";
 465                 } else {
 466                         return "$IP/maintenance/tables.sql";
 467                 }
 468         }
 469
 470 # ------------------------------------------------------------------------------
 471 # Other functions
 472 # ------------------------------------------------------------------------------
 473
 474         /**
 475          * Constructor.
 476          * @param $server String: database server host
 477          * @param $user String: database user name
 478          * @param $password String: database user password
 479          * @param $dbName String: database name
 480          * @param $flags
 481          * @param $tablePrefix String: database table prefixes. By default use the prefix gave in LocalSettings.php
 482          */
 483         function __construct( $server = false, $user = false, $password = false, $dbName = false,
 484                 $flags = 0, $tablePrefix = 'get from global'
 485         ) {
 486                 global $wgOut, $wgDBprefix, $wgCommandLineMode;
 487
 488                 # Can't get a reference if it hasn't been set yet
 489                 if ( !isset( $wgOut ) ) {
 490                         $wgOut = null;
 491                 }
 492                 $this->mFlags = $flags;
 493
 494                 if ( $this->mFlags & DBO_DEFAULT ) {
 495                         if ( $wgCommandLineMode ) {
 496                                 $this->mFlags &= ~DBO_TRX;
 497                         } else {
 498                                 $this->mFlags |= DBO_TRX;
 499                         }
 500                 }
 501
 502                 /*
 503                 // Faster read-only access
 504                 if ( wfReadOnly() ) {
 505                         $this->mFlags |= DBO_PERSISTENT;
 506                         $this->mFlags &= ~DBO_TRX;
 507                 }*/
 508
 509                 /** Get the default table prefix*/
 510                 if ( $tablePrefix == 'get from global' ) {
 511                         $this->mTablePrefix = $wgDBprefix;
 512                 } else {
 513                         $this->mTablePrefix = $tablePrefix;
 514                 }
 515
 516                 if ( $server ) {
 517                         $this->open( $server, $user, $password, $dbName );
 518                 }
 519         }
 520
 521         /**
 522          * Same as new DatabaseMysql( ... ), kept for backward compatibility
 523          * @param $server String: database server host
 524          * @param $user String: database user name
 525          * @param $password String: database user password
 526          * @param $dbName String: database name
 527          * @param $flags
 528          */
 529         static function newFromParams( $server, $user, $password, $dbName, $flags = 0 ) {
 530                 wfDeprecated( __METHOD__ );
 531                 return new DatabaseMysql( $server, $user, $password, $dbName, $flags );
 532         }
 533
 534         protected function installErrorHandler() {
 535                 $this->mPHPError = false;
 536                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 537                 set_error_handler( array( $this, 'connectionErrorHandler' ) );
 538         }
 539
 540         protected function restoreErrorHandler() {
 541                 restore_error_handler();
 542                 if ( $this->htmlErrors !== false ) {
 543                         ini_set( 'html_errors', $this->htmlErrors );
 544                 }
 545                 if ( $this->mPHPError ) {
 546                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 547                         $error = preg_replace( '!^.*?:(.*)$!', '$1', $error );
 548                         return $error;
 549                 } else {
 550                         return false;
 551                 }
 552         }
 553
 554         protected function connectionErrorHandler( $errno,  $errstr ) {
 555                 $this->mPHPError = $errstr;
 556         }
 557
 558         /**
 559          * Closes a database connection.
 560          * if it is open : commits any open transactions
 561          *
 562          * @return Bool operation success. true if already closed.
 563          */
 564         function close() {
 565                 # Stub, should probably be overridden
 566                 return true;
 567         }
 568
 569         /**
 570          * @param $error String: fallback error message, used if none is given by DB
 571          */
 572         function reportConnectionError( $error = 'Unknown error' ) {
 573                 $myError = $this->lastError();
 574                 if ( $myError ) {
 575                         $error = $myError;
 576                 }
 577
 578                 # New method
 579                 throw new DBConnectionError( $this, $error );
 580         }
 581
 582         /**
 583          * Determine whether a query writes to the DB.
 584          * Should return true if unsure.
 585          */
 586         function isWriteQuery( $sql ) {
 587                 return !preg_match( '/^(?:SELECT|BEGIN|COMMIT|SET|SHOW|\(SELECT)\b/i', $sql );
 588         }
 589
 590         /**
 591          * Usually aborts on failure.  If errors are explicitly ignored, returns success.
 592          *
 593          * @param  $sql        String: SQL query
 594          * @param  $fname      String: Name of the calling function, for profiling/SHOW PROCESSLIST
 595          *     comment (you can use __METHOD__ or add some extra info)
 596          * @param  $tempIgnore Boolean:   Whether to avoid throwing an exception on errors...
 597          *     maybe best to catch the exception instead?
 598          * @return true for a successful write query, ResultWrapper object for a successful read query,
 599          *     or false on failure if $tempIgnore set
 600          * @throws DBQueryError Thrown when the database returns an error of any kind
 601          */
 602         public function query( $sql, $fname = '', $tempIgnore = false ) {
 603                 global $wgProfiler;
 604
 605                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 606                 if ( isset( $wgProfiler ) ) {
 607                         # generalizeSQL will probably cut down the query to reasonable
 608                         # logging size most of the time. The substr is really just a sanity check.
 609
 610                         # Who's been wasting my precious column space? -- TS
 611                         # $profName = 'query: ' . $fname . ' ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 612
 613                         if ( $isMaster ) {
 614                                 $queryProf = 'query-m: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 615                                 $totalProf = 'DatabaseBase::query-master';
 616                         } else {
 617                                 $queryProf = 'query: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 618                                 $totalProf = 'DatabaseBase::query';
 619                         }
 620
 621                         wfProfileIn( $totalProf );
 622                         wfProfileIn( $queryProf );
 623                 }
 624
 625                 $this->mLastQuery = $sql;
 626                 if ( !$this->mDoneWrites && $this->isWriteQuery( $sql ) ) {
 627                         // Set a flag indicating that writes have been done
 628                         wfDebug( __METHOD__ . ": Writes done: $sql\n" );
 629                         $this->mDoneWrites = true;
 630                 }
 631
 632                 # Add a comment for easy SHOW PROCESSLIST interpretation
 633                 # if ( $fname ) {
 634                         global $wgUser;
 635                         if ( is_object( $wgUser ) && $wgUser->mDataLoaded ) {
 636                                 $userName = $wgUser->getName();
 637                                 if ( mb_strlen( $userName ) > 15 ) {
 638                                         $userName = mb_substr( $userName, 0, 15 ) . '...';
 639                                 }
 640                                 $userName = str_replace( '/', '', $userName );
 641                         } else {
 642                                 $userName = '';
 643                         }
 644                         $commentedSql = preg_replace( '/\s/', " /* $fname $userName */ ", $sql, 1 );
 645                 # } else {
 646                 #       $commentedSql = $sql;
 647                 # }
 648
 649                 # If DBO_TRX is set, start a transaction
 650                 if ( ( $this->mFlags & DBO_TRX ) && !$this->trxLevel() &&
 651                         $sql != 'BEGIN' && $sql != 'COMMIT' && $sql != 'ROLLBACK' ) {
 652                         // avoid establishing transactions for SHOW and SET statements too -
 653                         // that would delay transaction initializations to once connection
 654                         // is really used by application
 655                         $sqlstart = substr( $sql, 0, 10 ); // very much worth it, benchmark certified(tm)
 656                         if ( strpos( $sqlstart, "SHOW " ) !== 0 and strpos( $sqlstart, "SET " ) !== 0 )
 657                                 $this->begin();
 658                 }
 659
 660                 if ( $this->debug() ) {
 661                         static $cnt = 0;
 662
 663                         $cnt++;
 664                         $sqlx = substr( $commentedSql, 0, 500 );
 665                         $sqlx = strtr( $sqlx, "\t\n", '  ' );
 666
 667                         if ( $isMaster ) {
 668                                 wfDebug( "Query $cnt (master): $sqlx\n" );
 669                         } else {
 670                                 wfDebug( "Query $cnt (slave): $sqlx\n" );
 671                         }
 672                 }
 673
 674                 if ( istainted( $sql ) & TC_MYSQL ) {
 675                         throw new MWException( 'Tainted query found' );
 676                 }
 677
 678                 # Do the query and handle errors
 679                 $ret = $this->doQuery( $commentedSql );
 680
 681                 # Try reconnecting if the connection was lost
 682                 if ( false === $ret && $this->wasErrorReissuable() ) {
 683                         # Transaction is gone, like it or not
 684                         $this->mTrxLevel = 0;
 685                         wfDebug( "Connection lost, reconnecting...\n" );
 686
 687                         if ( $this->ping() ) {
 688                                 wfDebug( "Reconnected\n" );
 689                                 $sqlx = substr( $commentedSql, 0, 500 );
 690                                 $sqlx = strtr( $sqlx, "\t\n", '  ' );
 691                                 global $wgRequestTime;
 692                                 $elapsed = round( microtime( true ) - $wgRequestTime, 3 );
 693                                 wfLogDBError( "Connection lost and reconnected after {$elapsed}s, query: $sqlx\n" );
 694                                 $ret = $this->doQuery( $commentedSql );
 695                         } else {
 696                                 wfDebug( "Failed\n" );
 697                         }
 698                 }
 699
 700                 if ( false === $ret ) {
 701                         $this->reportQueryError( $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 702                 }
 703
 704                 if ( isset( $wgProfiler ) ) {
 705                         wfProfileOut( $queryProf );
 706                         wfProfileOut( $totalProf );
 707                 }
 708
 709                 return $this->resultObject( $ret );
 710         }
 711
 712         /**
 713          * @param $error String
 714          * @param $errno Integer
 715          * @param $sql String
 716          * @param $fname String
 717          * @param $tempIgnore Boolean
 718          */
 719         function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 720                 # Ignore errors during error handling to avoid infinite recursion
 721                 $ignore = $this->ignoreErrors( true );
 722                 ++$this->mErrorCount;
 723
 724                 if ( $ignore || $tempIgnore ) {
 725                         wfDebug( "SQL ERROR (ignored): $error\n" );
 726                         $this->ignoreErrors( $ignore );
 727                 } else {
 728                         $sql1line = str_replace( "\n", "\\n", $sql );
 729                         wfLogDBError( "$fname\t{$this->mServer}\t$errno\t$error\t$sql1line\n" );
 730                         wfDebug( "SQL ERROR: " . $error . "\n" );
 731                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
 732                 }
 733         }
 734
 735
 736         /**
 737          * Intended to be compatible with the PEAR::DB wrapper functions.
 738          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
 739          *
 740          * ? = scalar value, quoted as necessary
 741          * ! = raw SQL bit (a function for instance)
 742          * & = filename; reads the file and inserts as a blob
 743          *     (we don't use this though...)
 744          */
 745         function prepare( $sql, $func = 'DatabaseBase::prepare' ) {
 746                 /* MySQL doesn't support prepared statements (yet), so just
 747                    pack up the query for reference. We'll manually replace
 748                    the bits later. */
 749                 return array( 'query' => $sql, 'func' => $func );
 750         }
 751
 752         function freePrepared( $prepared ) {
 753                 /* No-op by default */
 754         }
 755
 756         /**
 757          * Execute a prepared query with the various arguments
 758          * @param $prepared String: the prepared sql
 759          * @param $args Mixed: Either an array here, or put scalars as varargs
 760          */
 761         function execute( $prepared, $args = null ) {
 762                 if ( !is_array( $args ) ) {
 763                         # Pull the var args
 764                         $args = func_get_args();
 765                         array_shift( $args );
 766                 }
 767
 768                 $sql = $this->fillPrepared( $prepared['query'], $args );
 769
 770                 return $this->query( $sql, $prepared['func'] );
 771         }
 772
 773         /**
 774          * Prepare & execute an SQL statement, quoting and inserting arguments
 775          * in the appropriate places.
 776          * @param $query String
 777          * @param $args ...
 778          */
 779         function safeQuery( $query, $args = null ) {
 780                 $prepared = $this->prepare( $query, 'DatabaseBase::safeQuery' );
 781
 782                 if ( !is_array( $args ) ) {
 783                         # Pull the var args
 784                         $args = func_get_args();
 785                         array_shift( $args );
 786                 }
 787
 788                 $retval = $this->execute( $prepared, $args );
 789                 $this->freePrepared( $prepared );
 790
 791                 return $retval;
 792         }
 793
 794         /**
 795          * For faking prepared SQL statements on DBs that don't support
 796          * it directly.
 797          * @param $preparedQuery String: a 'preparable' SQL statement
 798          * @param $args Array of arguments to fill it with
 799          * @return string executable SQL
 800          */
 801         function fillPrepared( $preparedQuery, $args ) {
 802                 reset( $args );
 803                 $this->preparedArgs =& $args;
 804
 805                 return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
 806                         array( &$this, 'fillPreparedArg' ), $preparedQuery );
 807         }
 808
 809         /**
 810          * preg_callback func for fillPrepared()
 811          * The arguments should be in $this->preparedArgs and must not be touched
 812          * while we're doing this.
 813          *
 814          * @param $matches Array
 815          * @return String
 816          * @private
 817          */
 818         function fillPreparedArg( $matches ) {
 819                 switch( $matches[1] ) {
 820                         case '\\?': return '?';
 821                         case '\\!': return '!';
 822                         case '\\&': return '&';
 823                 }
 824
 825                 list( /* $n */ , $arg ) = each( $this->preparedArgs );
 826
 827                 switch( $matches[1] ) {
 828                         case '?': return $this->addQuotes( $arg );
 829                         case '!': return $arg;
 830                         case '&':
 831                                 # return $this->addQuotes( file_get_contents( $arg ) );
 832                                 throw new DBUnexpectedError( $this, '& mode is not implemented. If it\'s really needed, uncomment the line above.' );
 833                         default:
 834                                 throw new DBUnexpectedError( $this, 'Received invalid match. This should never happen!' );
 835                 }
 836         }
 837
 838         /**
 839          * Free a result object
 840          * @param $res Mixed: A SQL result
 841          */
 842         function freeResult( $res ) {
 843                 # Stub.  Might not really need to be overridden, since results should
 844                 # be freed by PHP when the variable goes out of scope anyway.
 845         }
 846
 847         /**
 848          * Simple UPDATE wrapper
 849          * Usually aborts on failure
 850          * If errors are explicitly ignored, returns success
 851          *
 852          * This function exists for historical reasons, DatabaseBase::update() has a more standard
 853          * calling convention and feature set
 854          */
 855         function set( $table, $var, $value, $cond, $fname = 'DatabaseBase::set' ) {
 856                 $table = $this->tableName( $table );
 857                 $sql = "UPDATE $table SET $var = '" .
 858                   $this->strencode( $value ) . "' WHERE ($cond)";
 859
 860                 return (bool)$this->query( $sql, $fname );
 861         }
 862
 863         /**
 864          * Simple SELECT wrapper, returns a single field, input must be encoded
 865          * Usually aborts on failure
 866          * If errors are explicitly ignored, returns FALSE on failure
 867          */
 868         function selectField( $table, $var, $cond = '', $fname = 'DatabaseBase::selectField', $options = array() ) {
 869                 if ( !is_array( $options ) ) {
 870                         $options = array( $options );
 871                 }
 872
 873                 $options['LIMIT'] = 1;
 874
 875                 $res = $this->select( $table, $var, $cond, $fname, $options );
 876
 877                 if ( $res === false || !$this->numRows( $res ) ) {
 878                         return false;
 879                 }
 880
 881                 $row = $this->fetchRow( $res );
 882
 883                 if ( $row !== false ) {
 884                         return reset( $row );
 885                 } else {
 886                         return false;
 887                 }
 888         }
 889
 890         /**
 891          * Returns an optional USE INDEX clause to go after the table, and a
 892          * string to go at the end of the query
 893          *
 894          * @private
 895          *
 896          * @param $options Array: associative array of options to be turned into
 897          *              an SQL query, valid keys are listed in the function.
 898          * @return Array
 899          */
 900         function makeSelectOptions( $options ) {
 901                 $preLimitTail = $postLimitTail = '';
 902                 $startOpts = '';
 903
 904                 $noKeyOptions = array();
 905
 906                 foreach ( $options as $key => $option ) {
 907                         if ( is_numeric( $key ) ) {
 908                                 $noKeyOptions[$option] = true;
 909                         }
 910                 }
 911
 912                 if ( isset( $options['GROUP BY'] ) ) {
 913                         $preLimitTail .= " GROUP BY {$options['GROUP BY']}";
 914                 }
 915
 916                 if ( isset( $options['HAVING'] ) ) {
 917                         $preLimitTail .= " HAVING {$options['HAVING']}";
 918                 }
 919
 920                 if ( isset( $options['ORDER BY'] ) ) {
 921                         $preLimitTail .= " ORDER BY {$options['ORDER BY']}";
 922                 }
 923
 924                 // if (isset($options['LIMIT'])) {
 925                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
 926                 //              isset($options['OFFSET']) ? $options['OFFSET']
 927                 //              : false);
 928                 // }
 929
 930                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
 931                         $postLimitTail .= ' FOR UPDATE';
 932                 }
 933
 934                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
 935                         $postLimitTail .= ' LOCK IN SHARE MODE';
 936                 }
 937
 938                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
 939                         $startOpts .= 'DISTINCT';
 940                 }
 941
 942                 # Various MySQL extensions
 943                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
 944                         $startOpts .= ' /*! STRAIGHT_JOIN */';
 945                 }
 946
 947                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
 948                         $startOpts .= ' HIGH_PRIORITY';
 949                 }
 950
 951                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
 952                         $startOpts .= ' SQL_BIG_RESULT';
 953                 }
 954
 955                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
 956                         $startOpts .= ' SQL_BUFFER_RESULT';
 957                 }
 958
 959                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
 960                         $startOpts .= ' SQL_SMALL_RESULT';
 961                 }
 962
 963                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
 964                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
 965                 }
 966
 967                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
 968                         $startOpts .= ' SQL_CACHE';
 969                 }
 970
 971                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
 972                         $startOpts .= ' SQL_NO_CACHE';
 973                 }
 974
 975                 if ( isset( $options['USE INDEX'] ) && ! is_array( $options['USE INDEX'] ) ) {
 976                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
 977                 } else {
 978                         $useIndex = '';
 979                 }
 980
 981                 return array( $startOpts, $useIndex, $preLimitTail, $postLimitTail );
 982         }
 983
 984         /**
 985          * SELECT wrapper
 986          *
 987          * @param $table   Mixed:  Array or string, table name(s) (prefix auto-added)
 988          * @param $vars    Mixed:  Array or string, field name(s) to be retrieved
 989          * @param $conds   Mixed:  Array or string, condition(s) for WHERE
 990          * @param $fname   String: Calling function name (use __METHOD__) for logs/profiling
 991          * @param $options Array:  Associative array of options (e.g. array('GROUP BY' => 'page_title')),
 992          *                         see DatabaseBase::makeSelectOptions code for list of supported stuff
 993          * @param $join_conds Array: Associative array of table join conditions (optional)
 994          *                           (e.g. array( 'page' => array('LEFT JOIN','page_latest=rev_id') )
 995          * @return mixed Database result resource (feed to DatabaseBase::fetchObject or whatever), or false on failure
 996          */
 997         function select( $table, $vars, $conds = '', $fname = 'DatabaseBase::select', $options = array(), $join_conds = array() ) {
 998                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
 999
1000                 return $this->query( $sql, $fname );
1001         }
1002
1003         /**
1004          * SELECT wrapper
1005          *
1006          * @param $table   Mixed:  Array or string, table name(s) (prefix auto-added)
1007          * @param $vars    Mixed:  Array or string, field name(s) to be retrieved
1008          * @param $conds   Mixed:  Array or string, condition(s) for WHERE
1009          * @param $fname   String: Calling function name (use __METHOD__) for logs/profiling
1010          * @param $options Array:  Associative array of options (e.g. array('GROUP BY' => 'page_title')),
1011          *                         see DatabaseBase::makeSelectOptions code for list of supported stuff
1012          * @param $join_conds Array: Associative array of table join conditions (optional)
1013          *                           (e.g. array( 'page' => array('LEFT JOIN','page_latest=rev_id') )
1014          * @return string, the SQL text
1015          */
1016         function selectSQLText( $table, $vars, $conds = '', $fname = 'DatabaseBase::select', $options = array(), $join_conds = array() ) {
1017                 if ( is_array( $vars ) ) {
1018                         $vars = implode( ',', $vars );
1019                 }
1020
1021                 if ( !is_array( $options ) ) {
1022                         $options = array( $options );
1023                 }
1024
1025                 if ( is_array( $table ) ) {
1026                         if ( !empty( $join_conds ) || ( isset( $options['USE INDEX'] ) && is_array( @$options['USE INDEX'] ) ) ) {
1027                                 $from = ' FROM ' . $this->tableNamesWithUseIndexOrJOIN( $table, @$options['USE INDEX'], $join_conds );
1028                         } else {
1029                                 $from = ' FROM ' . implode( ',', array_map( array( &$this, 'tableName' ), $table ) );
1030                         }
1031                 } elseif ( $table != '' ) {
1032                         if ( $table { 0 } == ' ' ) {
1033                                 $from = ' FROM ' . $table;
1034                         } else {
1035                                 $from = ' FROM ' . $this->tableName( $table );
1036                         }
1037                 } else {
1038                         $from = '';
1039                 }
1040
1041                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail ) = $this->makeSelectOptions( $options );
1042
1043                 if ( !empty( $conds ) ) {
1044                         if ( is_array( $conds ) ) {
1045                                 $conds = $this->makeList( $conds, LIST_AND );
1046                         }
1047                         $sql = "SELECT $startOpts $vars $from $useIndex WHERE $conds $preLimitTail";
1048                 } else {
1049                         $sql = "SELECT $startOpts $vars $from $useIndex $preLimitTail";
1050                 }
1051
1052                 if ( isset( $options['LIMIT'] ) )
1053                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1054                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1055                 $sql = "$sql $postLimitTail";
1056
1057                 if ( isset( $options['EXPLAIN'] ) ) {
1058                         $sql = 'EXPLAIN ' . $sql;
1059                 }
1060
1061                 return $sql;
1062         }
1063
1064         /**
1065          * Single row SELECT wrapper
1066          * Aborts or returns FALSE on error
1067          *
1068          * @param $table String: table name
1069          * @param $vars String: the selected variables
1070          * @param $conds Array: a condition map, terms are ANDed together.
1071          *   Items with numeric keys are taken to be literal conditions
1072          * Takes an array of selected variables, and a condition map, which is ANDed
1073          * e.g: selectRow( "page", array( "page_id" ), array( "page_namespace" =>
1074          * NS_MAIN, "page_title" => "Astronomy" ) )   would return an object where
1075          * $obj- >page_id is the ID of the Astronomy article
1076          * @param $fname String: Calling function name
1077          * @param $options Array
1078          * @param $join_conds Array
1079          *
1080          * @todo migrate documentation to phpdocumentor format
1081          */
1082         function selectRow( $table, $vars, $conds, $fname = 'DatabaseBase::selectRow', $options = array(), $join_conds = array() ) {
1083                 $options['LIMIT'] = 1;
1084                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1085
1086                 if ( $res === false ) {
1087                         return false;
1088                 }
1089
1090                 if ( !$this->numRows( $res ) ) {
1091                         return false;
1092                 }
1093
1094                 $obj = $this->fetchObject( $res );
1095
1096                 return $obj;
1097         }
1098
1099         /**
1100          * Estimate rows in dataset
1101          * Returns estimated count - not necessarily an accurate estimate across different databases,
1102          * so use sparingly
1103          * Takes same arguments as DatabaseBase::select()
1104          *
1105          * @param $table String: table name
1106          * @param $vars Array: unused
1107          * @param $conds Array: filters on the table
1108          * @param $fname String: function name for profiling
1109          * @param $options Array: options for select
1110          * @return Integer: row count
1111          */
1112         public function estimateRowCount( $table, $vars = '*', $conds = '', $fname = 'DatabaseBase::estimateRowCount', $options = array() ) {
1113                 $rows = 0;
1114                 $res = $this->select ( $table, 'COUNT(*) AS rowcount', $conds, $fname, $options );
1115
1116                 if ( $res ) {
1117                         $row = $this->fetchRow( $res );
1118                         $rows = ( isset( $row['rowcount'] ) ) ? $row['rowcount'] : 0;
1119                 }
1120
1121                 return $rows;
1122         }
1123
1124         /**
1125          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1126          * It's only slightly flawed. Don't use for anything important.
1127          *
1128          * @param $sql String: A SQL Query
1129          */
1130         static function generalizeSQL( $sql ) {
1131                 # This does the same as the regexp below would do, but in such a way
1132                 # as to avoid crashing php on some large strings.
1133                 # $sql = preg_replace ( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql);
1134
1135                 $sql = str_replace ( "\\\\", '', $sql );
1136                 $sql = str_replace ( "\\'", '', $sql );
1137                 $sql = str_replace ( "\\\"", '', $sql );
1138                 $sql = preg_replace ( "/'.*'/s", "'X'", $sql );
1139                 $sql = preg_replace ( '/".*"/s', "'X'", $sql );
1140
1141                 # All newlines, tabs, etc replaced by single space
1142                 $sql = preg_replace ( '/\s+/', ' ', $sql );
1143
1144                 # All numbers => N
1145                 $sql = preg_replace ( '/-?[0-9]+/s', 'N', $sql );
1146
1147                 return $sql;
1148         }
1149
1150         /**
1151          * Determines whether a field exists in a table
1152          *
1153          * @param $table String: table name
1154          * @param $field String: filed to check on that table
1155          * @param $fname String: calling function name (optional)
1156          * @return Boolean: whether $table has filed $field
1157          */
1158         function fieldExists( $table, $field, $fname = 'DatabaseBase::fieldExists' ) {
1159                 $info = $this->fieldInfo( $table, $field );
1160
1161                 return (bool)$info;
1162         }
1163
1164         /**
1165          * Determines whether an index exists
1166          * Usually aborts on failure
1167          * If errors are explicitly ignored, returns NULL on failure
1168          */
1169         function indexExists( $table, $index, $fname = 'DatabaseBase::indexExists' ) {
1170                 $info = $this->indexInfo( $table, $index, $fname );
1171                 if ( is_null( $info ) ) {
1172                         return null;
1173                 } else {
1174                         return $info !== false;
1175                 }
1176         }
1177
1178
1179         /**
1180          * Get information about an index into an object
1181          * Returns false if the index does not exist
1182          */
1183         function indexInfo( $table, $index, $fname = 'DatabaseBase::indexInfo' ) {
1184                 # SHOW INDEX works in MySQL 3.23.58, but SHOW INDEXES does not.
1185                 # SHOW INDEX should work for 3.x and up:
1186                 # http://dev.mysql.com/doc/mysql/en/SHOW_INDEX.html
1187                 $table = $this->tableName( $table );
1188                 $index = $this->indexName( $index );
1189                 $sql = 'SHOW INDEX FROM ' . $table;
1190                 $res = $this->query( $sql, $fname );
1191
1192                 if ( !$res ) {
1193                         return null;
1194                 }
1195
1196                 $result = array();
1197
1198                 foreach ( $res as $row ) {
1199                         if ( $row->Key_name == $index ) {
1200                                 $result[] = $row;
1201                         }
1202                 }
1203
1204                 return empty( $result ) ? false : $result;
1205         }
1206
1207         /**
1208          * Query whether a given table exists
1209          */
1210         function tableExists( $table ) {
1211                 $table = $this->tableName( $table );
1212                 $old = $this->ignoreErrors( true );
1213                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", __METHOD__ );
1214                 $this->ignoreErrors( $old );
1215
1216                 return (bool)$res;
1217         }
1218
1219         /**
1220          * mysql_field_type() wrapper
1221          */
1222         function fieldType( $res, $index ) {
1223                 if ( $res instanceof ResultWrapper ) {
1224                         $res = $res->result;
1225                 }
1226
1227                 return mysql_field_type( $res, $index );
1228         }
1229
1230         /**
1231          * Determines if a given index is unique
1232          */
1233         function indexUnique( $table, $index ) {
1234                 $indexInfo = $this->indexInfo( $table, $index );
1235
1236                 if ( !$indexInfo ) {
1237                         return null;
1238                 }
1239
1240                 return !$indexInfo[0]->Non_unique;
1241         }
1242
1243         /**
1244          * INSERT wrapper, inserts an array into a table
1245          *
1246          * $a may be a single associative array, or an array of these with numeric keys, for
1247          * multi-row insert.
1248          *
1249          * Usually aborts on failure
1250          * If errors are explicitly ignored, returns success
1251          *
1252          * @param $table   String: table name (prefix auto-added)
1253          * @param $a       Array: Array of rows to insert
1254          * @param $fname   String: Calling function name (use __METHOD__) for logs/profiling
1255          * @param $options Mixed: Associative array of options
1256          *
1257          * @return bool
1258          */
1259         function insert( $table, $a, $fname = 'DatabaseBase::insert', $options = array() ) {
1260                 # No rows to insert, easy just return now
1261                 if ( !count( $a ) ) {
1262                         return true;
1263                 }
1264
1265                 $table = $this->tableName( $table );
1266
1267                 if ( !is_array( $options ) ) {
1268                         $options = array( $options );
1269                 }
1270
1271                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1272                         $multi = true;
1273                         $keys = array_keys( $a[0] );
1274                 } else {
1275                         $multi = false;
1276                         $keys = array_keys( $a );
1277                 }
1278
1279                 $sql = 'INSERT ' . implode( ' ', $options ) .
1280                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1281
1282                 if ( $multi ) {
1283                         $first = true;
1284                         foreach ( $a as $row ) {
1285                                 if ( $first ) {
1286                                         $first = false;
1287                                 } else {
1288                                         $sql .= ',';
1289                                 }
1290                                 $sql .= '(' . $this->makeList( $row ) . ')';
1291                         }
1292                 } else {
1293                         $sql .= '(' . $this->makeList( $a ) . ')';
1294                 }
1295
1296                 return (bool)$this->query( $sql, $fname );
1297         }
1298
1299         /**
1300          * Make UPDATE options for the DatabaseBase::update function
1301          *
1302          * @private
1303          * @param $options Array: The options passed to DatabaseBase::update
1304          * @return string
1305          */
1306         function makeUpdateOptions( $options ) {
1307                 if ( !is_array( $options ) ) {
1308                         $options = array( $options );
1309                 }
1310
1311                 $opts = array();
1312
1313                 if ( in_array( 'LOW_PRIORITY', $options ) ) {
1314                         $opts[] = $this->lowPriorityOption();
1315                 }
1316
1317                 if ( in_array( 'IGNORE', $options ) ) {
1318                         $opts[] = 'IGNORE';
1319                 }
1320
1321                 return implode( ' ', $opts );
1322         }
1323
1324         /**
1325          * UPDATE wrapper, takes a condition array and a SET array
1326          *
1327          * @param $table  String: The table to UPDATE
1328          * @param $values Array:  An array of values to SET
1329          * @param $conds  Array:  An array of conditions (WHERE). Use '*' to update all rows.
1330          * @param $fname  String: The Class::Function calling this function
1331          *                        (for the log)
1332          * @param $options Array: An array of UPDATE options, can be one or
1333          *                        more of IGNORE, LOW_PRIORITY
1334          * @return Boolean
1335          */
1336         function update( $table, $values, $conds, $fname = 'DatabaseBase::update', $options = array() ) {
1337                 $table = $this->tableName( $table );
1338                 $opts = $this->makeUpdateOptions( $options );
1339                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1340
1341                 if ( $conds != '*' ) {
1342                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1343                 }
1344
1345                 return $this->query( $sql, $fname );
1346         }
1347
1348         /**
1349          * Makes an encoded list of strings from an array
1350          * $mode:
1351          *        LIST_COMMA         - comma separated, no field names
1352          *        LIST_AND           - ANDed WHERE clause (without the WHERE)
1353          *        LIST_OR            - ORed WHERE clause (without the WHERE)
1354          *        LIST_SET           - comma separated with field names, like a SET clause
1355          *        LIST_NAMES         - comma separated field names
1356          */
1357         function makeList( $a, $mode = LIST_COMMA ) {
1358                 if ( !is_array( $a ) ) {
1359                         throw new DBUnexpectedError( $this, 'DatabaseBase::makeList called with incorrect parameters' );
1360                 }
1361
1362                 $first = true;
1363                 $list = '';
1364
1365                 foreach ( $a as $field => $value ) {
1366                         if ( !$first ) {
1367                                 if ( $mode == LIST_AND ) {
1368                                         $list .= ' AND ';
1369                                 } elseif ( $mode == LIST_OR ) {
1370                                         $list .= ' OR ';
1371                                 } else {
1372                                         $list .= ',';
1373                                 }
1374                         } else {
1375                                 $first = false;
1376                         }
1377
1378                         if ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_numeric( $field ) ) {
1379                                 $list .= "($value)";
1380                         } elseif ( ( $mode == LIST_SET ) && is_numeric( $field ) ) {
1381                                 $list .= "$value";
1382                         } elseif ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_array( $value ) ) {
1383                                 if ( count( $value ) == 0 ) {
1384                                         throw new MWException( __METHOD__ . ': empty input' );
1385                                 } elseif ( count( $value ) == 1 ) {
1386                                         // Special-case single values, as IN isn't terribly efficient
1387                                         // Don't necessarily assume the single key is 0; we don't
1388                                         // enforce linear numeric ordering on other arrays here.
1389                                         $value = array_values( $value );
1390                                         $list .= $field . " = " . $this->addQuotes( $value[0] );
1391                                 } else {
1392                                         $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1393                                 }
1394                         } elseif ( $value === null ) {
1395                                 if ( $mode == LIST_AND || $mode == LIST_OR ) {
1396                                         $list .= "$field IS ";
1397                                 } elseif ( $mode == LIST_SET ) {
1398                                         $list .= "$field = ";
1399                                 }
1400                                 $list .= 'NULL';
1401                         } else {
1402                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
1403                                         $list .= "$field = ";
1404                                 }
1405                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
1406                         }
1407                 }
1408
1409                 return $list;
1410         }
1411
1412         /**
1413          * Build a partial where clause from a 2-d array such as used for LinkBatch.
1414          * The keys on each level may be either integers or strings.
1415          *
1416          * @param $data Array: organized as 2-d array(baseKeyVal => array(subKeyVal => <ignored>, ...), ...)
1417          * @param $baseKey String: field name to match the base-level keys to (eg 'pl_namespace')
1418          * @param $subKey String: field name to match the sub-level keys to (eg 'pl_title')
1419          * @return Mixed: string SQL fragment, or false if no items in array.
1420          */
1421         function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1422                 $conds = array();
1423
1424                 foreach ( $data as $base => $sub ) {
1425                         if ( count( $sub ) ) {
1426                                 $conds[] = $this->makeList(
1427                                         array( $baseKey => $base, $subKey => array_keys( $sub ) ),
1428                                         LIST_AND );
1429                         }
1430                 }
1431
1432                 if ( $conds ) {
1433                         return $this->makeList( $conds, LIST_OR );
1434                 } else {
1435                         // Nothing to search for...
1436                         return false;
1437                 }
1438         }
1439
1440         /**
1441          * Bitwise operations
1442          */
1443
1444         function bitNot( $field ) {
1445                 return "(~$field)";
1446         }
1447
1448         function bitAnd( $fieldLeft, $fieldRight ) {
1449                 return "($fieldLeft & $fieldRight)";
1450         }
1451
1452         function bitOr( $fieldLeft, $fieldRight ) {
1453                 return "($fieldLeft | $fieldRight)";
1454         }
1455
1456         /**
1457          * Change the current database
1458          *
1459          * @todo Explain what exactly will fail if this is not overridden.
1460          * @return bool Success or failure
1461          */
1462         function selectDB( $db ) {
1463                 # Stub.  Shouldn't cause serious problems if it's not overridden, but
1464                 # if your database engine supports a concept similar to MySQL's
1465                 # databases you may as well.
1466                 return true;
1467         }
1468
1469         /**
1470          * Get the current DB name
1471          */
1472         function getDBname() {
1473                 return $this->mDBname;
1474         }
1475
1476         /**
1477          * Get the server hostname or IP address
1478          */
1479         function getServer() {
1480                 return $this->mServer;
1481         }
1482
1483         /**
1484          * Format a table name ready for use in constructing an SQL query
1485          *
1486          * This does two important things: it quotes the table names to clean them up,
1487          * and it adds a table prefix if only given a table name with no quotes.
1488          *
1489          * All functions of this object which require a table name call this function
1490          * themselves. Pass the canonical name to such functions. This is only needed
1491          * when calling query() directly.
1492          *
1493          * @param $name String: database table name
1494          * @return String: full database name
1495          */
1496         function tableName( $name ) {
1497                 global $wgSharedDB, $wgSharedPrefix, $wgSharedTables;
1498                 # Skip the entire process when we have a string quoted on both ends.
1499                 # Note that we check the end so that we will still quote any use of
1500                 # use of `database`.table. But won't break things if someone wants
1501                 # to query a database table with a dot in the name.
1502                 if ( $name[0] == '`' && substr( $name, -1, 1 ) == '`' ) {
1503                         return $name;
1504                 }
1505
1506                 # Lets test for any bits of text that should never show up in a table
1507                 # name. Basically anything like JOIN or ON which are actually part of
1508                 # SQL queries, but may end up inside of the table value to combine
1509                 # sql. Such as how the API is doing.
1510                 # Note that we use a whitespace test rather than a \b test to avoid
1511                 # any remote case where a word like on may be inside of a table name
1512                 # surrounded by symbols which may be considered word breaks.
1513                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1514                         return $name;
1515                 }
1516
1517                 # Split database and table into proper variables.
1518                 # We reverse the explode so that database.table and table both output
1519                 # the correct table.
1520                 $dbDetails = array_reverse( explode( '.', $name, 2 ) );
1521                 if ( isset( $dbDetails[1] ) ) {
1522                         @list( $table, $database ) = $dbDetails;
1523                 } else {
1524                         @list( $table ) = $dbDetails;
1525                 }
1526                 $prefix = $this->mTablePrefix; # Default prefix
1527
1528                 # A database name has been specified in input. Quote the table name
1529                 # because we don't want any prefixes added.
1530                 if ( isset( $database ) ) {
1531                         $table = ( $table[0] == '`' ? $table : "`{$table}`" );
1532                 }
1533
1534                 # Note that we use the long format because php will complain in in_array if
1535                 # the input is not an array, and will complain in is_array if it is not set.
1536                 if ( !isset( $database ) # Don't use shared database if pre selected.
1537                  && isset( $wgSharedDB ) # We have a shared database
1538                  && $table[0] != '`' # Paranoia check to prevent shared tables listing '`table`'
1539                  && isset( $wgSharedTables )
1540                  && is_array( $wgSharedTables )
1541                  && in_array( $table, $wgSharedTables ) ) { # A shared table is selected
1542                         $database = $wgSharedDB;
1543                         $prefix   = isset( $wgSharedPrefix ) ? $wgSharedPrefix : $prefix;
1544                 }
1545
1546                 # Quote the $database and $table and apply the prefix if not quoted.
1547                 if ( isset( $database ) ) {
1548                         $database = ( $database[0] == '`' ? $database : "`{$database}`" );
1549                 }
1550                 $table = ( $table[0] == '`' ? $table : "`{$prefix}{$table}`" );
1551
1552                 # Merge our database and table into our final table name.
1553                 $tableName = ( isset( $database ) ? "{$database}.{$table}" : "{$table}" );
1554
1555                 return $tableName;
1556         }
1557
1558         /**
1559          * Fetch a number of table names into an array
1560          * This is handy when you need to construct SQL for joins
1561          *
1562          * Example:
1563          * extract($dbr->tableNames('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 tableNames() {
1568                 $inArray = func_get_args();
1569                 $retVal = array();
1570
1571                 foreach ( $inArray as $name ) {
1572                         $retVal[$name] = $this->tableName( $name );
1573                 }
1574
1575                 return $retVal;
1576         }
1577
1578         /**
1579          * Fetch a number of table names into an zero-indexed numerical array
1580          * This is handy when you need to construct SQL for joins
1581          *
1582          * Example:
1583          * list( $user, $watchlist ) = $dbr->tableNamesN('user','watchlist');
1584          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1585          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1586          */
1587         public function tableNamesN() {
1588                 $inArray = func_get_args();
1589                 $retVal = array();
1590
1591                 foreach ( $inArray as $name ) {
1592                         $retVal[] = $this->tableName( $name );
1593                 }
1594
1595                 return $retVal;
1596         }
1597
1598         /**
1599          * @private
1600          */
1601         function tableNamesWithUseIndexOrJOIN( $tables, $use_index = array(), $join_conds = array() ) {
1602                 $ret = array();
1603                 $retJOIN = array();
1604                 $use_index_safe = is_array( $use_index ) ? $use_index : array();
1605                 $join_conds_safe = is_array( $join_conds ) ? $join_conds : array();
1606
1607                 foreach ( $tables as $table ) {
1608                         // Is there a JOIN and INDEX clause for this table?
1609                         if ( isset( $join_conds_safe[$table] ) && isset( $use_index_safe[$table] ) ) {
1610                                 $tableClause = $join_conds_safe[$table][0] . ' ' . $this->tableName( $table );
1611                                 $tableClause .= ' ' . $this->useIndexClause( implode( ',', (array)$use_index_safe[$table] ) );
1612                                 $on = $this->makeList( (array)$join_conds_safe[$table][1], LIST_AND );
1613
1614                                 if ( $on != '' ) {
1615                                         $tableClause .= ' ON (' . $on . ')';
1616                                 }
1617
1618                                 $retJOIN[] = $tableClause;
1619                         // Is there an INDEX clause?
1620                         } else if ( isset( $use_index_safe[$table] ) ) {
1621                                 $tableClause = $this->tableName( $table );
1622                                 $tableClause .= ' ' . $this->useIndexClause( implode( ',', (array)$use_index_safe[$table] ) );
1623                                 $ret[] = $tableClause;
1624                         // Is there a JOIN clause?
1625                         } else if ( isset( $join_conds_safe[$table] ) ) {
1626                                 $tableClause = $join_conds_safe[$table][0] . ' ' . $this->tableName( $table );
1627                                 $on = $this->makeList( (array)$join_conds_safe[$table][1], LIST_AND );
1628
1629                                 if ( $on != '' ) {
1630                                         $tableClause .= ' ON (' . $on . ')';
1631                                 }
1632
1633                                 $retJOIN[] = $tableClause;
1634                         } else {
1635                                 $tableClause = $this->tableName( $table );
1636                                 $ret[] = $tableClause;
1637                         }
1638                 }
1639
1640                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
1641                 $straightJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
1642                 $otherJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
1643
1644                 // Compile our final table clause
1645                 return implode( ' ', array( $straightJoins, $otherJoins ) );
1646         }
1647
1648         /**
1649          * Get the name of an index in a given table
1650          */
1651         function indexName( $index ) {
1652                 // Backwards-compatibility hack
1653                 $renamed = array(
1654                         'ar_usertext_timestamp' => 'usertext_timestamp',
1655                         'un_user_id'            => 'user_id',
1656                         'un_user_ip'            => 'user_ip',
1657                 );
1658
1659                 if ( isset( $renamed[$index] ) ) {
1660                         return $renamed[$index];
1661                 } else {
1662                         return $index;
1663                 }
1664         }
1665
1666         /**
1667          * If it's a string, adds quotes and backslashes
1668          * Otherwise returns as-is
1669          */
1670         function addQuotes( $s ) {
1671                 if ( $s === null ) {
1672                         return 'NULL';
1673                 } else {
1674                         # This will also quote numeric values. This should be harmless,
1675                         # and protects against weird problems that occur when they really
1676                         # _are_ strings such as article titles and string->number->string
1677                         # conversion is not 1:1.
1678                         return "'" . $this->strencode( $s ) . "'";
1679                 }
1680         }
1681
1682         /**
1683          * Escape string for safe LIKE usage.
1684          * WARNING: you should almost never use this function directly,
1685          * instead use buildLike() that escapes everything automatically
1686          * Deprecated in 1.17, warnings in 1.17, removed in ???
1687          */
1688         public function escapeLike( $s ) {
1689                 wfDeprecated( __METHOD__ );
1690                 return $this->escapeLikeInternal( $s );
1691         }
1692
1693         protected function escapeLikeInternal( $s ) {
1694                 $s = str_replace( '\\', '\\\\', $s );
1695                 $s = $this->strencode( $s );
1696                 $s = str_replace( array( '%', '_' ), array( '\%', '\_' ), $s );
1697
1698                 return $s;
1699         }
1700
1701         /**
1702          * LIKE statement wrapper, receives a variable-length argument list with parts of pattern to match
1703          * containing either string literals that will be escaped or tokens returned by anyChar() or anyString().
1704          * Alternatively, the function could be provided with an array of aforementioned parameters.
1705          *
1706          * Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns a LIKE clause that searches
1707          * for subpages of 'My page title'.
1708          * Alternatively: $pattern = array( 'My_page_title/', $dbr->anyString() ); $query .= $dbr->buildLike( $pattern );
1709          *
1710          * @since 1.16
1711          * @return String: fully built LIKE statement
1712          */
1713         function buildLike() {
1714                 $params = func_get_args();
1715
1716                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
1717                         $params = $params[0];
1718                 }
1719
1720                 $s = '';
1721
1722                 foreach ( $params as $value ) {
1723                         if ( $value instanceof LikeMatch ) {
1724                                 $s .= $value->toString();
1725                         } else {
1726                                 $s .= $this->escapeLikeInternal( $value );
1727                         }
1728                 }
1729
1730                 return " LIKE '" . $s . "' ";
1731         }
1732
1733         /**
1734          * Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
1735          */
1736         function anyChar() {
1737                 return new LikeMatch( '_' );
1738         }
1739
1740         /**
1741          * Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
1742          */
1743         function anyString() {
1744                 return new LikeMatch( '%' );
1745         }
1746
1747         /**
1748          * Returns an appropriately quoted sequence value for inserting a new row.
1749          * MySQL has autoincrement fields, so this is just NULL. But the PostgreSQL
1750          * subclass will return an integer, and save the value for insertId()
1751          */
1752         function nextSequenceValue( $seqName ) {
1753                 return null;
1754         }
1755
1756         /**
1757          * USE INDEX clause.  Unlikely to be useful for anything but MySQL.  This
1758          * is only needed because a) MySQL must be as efficient as possible due to
1759          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
1760          * which index to pick.  Anyway, other databases might have different
1761          * indexes on a given table.  So don't bother overriding this unless you're
1762          * MySQL.
1763          */
1764         function useIndexClause( $index ) {
1765                 return '';
1766         }
1767
1768         /**
1769          * REPLACE query wrapper
1770          * PostgreSQL simulates this with a DELETE followed by INSERT
1771          * $row is the row to insert, an associative array
1772          * $uniqueIndexes is an array of indexes. Each element may be either a
1773          * field name or an array of field names
1774          *
1775          * It may be more efficient to leave off unique indexes which are unlikely to collide.
1776          * However if you do this, you run the risk of encountering errors which wouldn't have
1777          * occurred in MySQL
1778          *
1779          * @param $table String: The table to replace the row(s) in.
1780          * @param $uniqueIndexes Array: An associative array of indexes
1781          * @param $rows Array: Array of rows to replace
1782          * @param $fname String: Calling function name (use __METHOD__) for logs/profiling
1783          */
1784         function replace( $table, $uniqueIndexes, $rows, $fname = 'DatabaseBase::replace' ) {
1785                 $table = $this->tableName( $table );
1786
1787                 # Single row case
1788                 if ( !is_array( reset( $rows ) ) ) {
1789                         $rows = array( $rows );
1790                 }
1791
1792                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
1793                 $first = true;
1794
1795                 foreach ( $rows as $row ) {
1796                         if ( $first ) {
1797                                 $first = false;
1798                         } else {
1799                                 $sql .= ',';
1800                         }
1801
1802                         $sql .= '(' . $this->makeList( $row ) . ')';
1803                 }
1804
1805                 return $this->query( $sql, $fname );
1806         }
1807
1808         /**
1809          * DELETE where the condition is a join
1810          * MySQL does this with a multi-table DELETE syntax, PostgreSQL does it with sub-selects
1811          *
1812          * For safety, an empty $conds will not delete everything. If you want to delete all rows where the
1813          * join condition matches, set $conds='*'
1814          *
1815          * DO NOT put the join condition in $conds
1816          *
1817          * @param $delTable String: The table to delete from.
1818          * @param $joinTable String: The other table.
1819          * @param $delVar String: The variable to join on, in the first table.
1820          * @param $joinVar String: The variable to join on, in the second table.
1821          * @param $conds Array: Condition array of field names mapped to variables, ANDed together in the WHERE clause
1822          * @param $fname String: Calling function name (use __METHOD__) for logs/profiling
1823          */
1824         function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds, $fname = 'DatabaseBase::deleteJoin' ) {
1825                 if ( !$conds ) {
1826                         throw new DBUnexpectedError( $this, 'DatabaseBase::deleteJoin() called with empty $conds' );
1827                 }
1828
1829                 $delTable = $this->tableName( $delTable );
1830                 $joinTable = $this->tableName( $joinTable );
1831                 $sql = "DELETE $delTable FROM $delTable, $joinTable WHERE $delVar=$joinVar ";
1832
1833                 if ( $conds != '*' ) {
1834                         $sql .= ' AND ' . $this->makeList( $conds, LIST_AND );
1835                 }
1836
1837                 return $this->query( $sql, $fname );
1838         }
1839
1840         /**
1841          * Returns the size of a text field, or -1 for "unlimited"
1842          */
1843         function textFieldSize( $table, $field ) {
1844                 $table = $this->tableName( $table );
1845                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
1846                 $res = $this->query( $sql, 'DatabaseBase::textFieldSize' );
1847                 $row = $this->fetchObject( $res );
1848
1849                 $m = array();
1850
1851                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
1852                         $size = $m[1];
1853                 } else {
1854                         $size = -1;
1855                 }
1856
1857                 return $size;
1858         }
1859
1860         /**
1861          * A string to insert into queries to show that they're low-priority, like
1862          * MySQL's LOW_PRIORITY.  If no such feature exists, return an empty
1863          * string and nothing bad should happen.
1864          *
1865          * @return string Returns the text of the low priority option if it is supported, or a blank string otherwise
1866          */
1867         function lowPriorityOption() {
1868                 return '';
1869         }
1870
1871         /**
1872          * DELETE query wrapper
1873          *
1874          * Use $conds == "*" to delete all rows
1875          */
1876         function delete( $table, $conds, $fname = 'DatabaseBase::delete' ) {
1877                 if ( !$conds ) {
1878                         throw new DBUnexpectedError( $this, 'DatabaseBase::delete() called with no conditions' );
1879                 }
1880
1881                 $table = $this->tableName( $table );
1882                 $sql = "DELETE FROM $table";
1883
1884                 if ( $conds != '*' ) {
1885                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1886                 }
1887
1888                 return $this->query( $sql, $fname );
1889         }
1890
1891         /**
1892          * INSERT SELECT wrapper
1893          * $varMap must be an associative array of the form array( 'dest1' => 'source1', ...)
1894          * Source items may be literals rather than field names, but strings should be quoted with DatabaseBase::addQuotes()
1895          * $conds may be "*" to copy the whole table
1896          * srcTable may be an array of tables.
1897          */
1898         function insertSelect( $destTable, $srcTable, $varMap, $conds, $fname = 'DatabaseBase::insertSelect',
1899                 $insertOptions = array(), $selectOptions = array() )
1900         {
1901                 $destTable = $this->tableName( $destTable );
1902
1903                 if ( is_array( $insertOptions ) ) {
1904                         $insertOptions = implode( ' ', $insertOptions );
1905                 }
1906
1907                 if ( !is_array( $selectOptions ) ) {
1908                         $selectOptions = array( $selectOptions );
1909                 }
1910
1911                 list( $startOpts, $useIndex, $tailOpts ) = $this->makeSelectOptions( $selectOptions );
1912
1913                 if ( is_array( $srcTable ) ) {
1914                         $srcTable =  implode( ',', array_map( array( &$this, 'tableName' ), $srcTable ) );
1915                 } else {
1916                         $srcTable = $this->tableName( $srcTable );
1917                 }
1918
1919                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
1920                         " SELECT $startOpts " . implode( ',', $varMap ) .
1921                         " FROM $srcTable $useIndex ";
1922
1923                 if ( $conds != '*' ) {
1924                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1925                 }
1926
1927                 $sql .= " $tailOpts";
1928
1929                 return $this->query( $sql, $fname );
1930         }
1931
1932         /**
1933          * Construct a LIMIT query with optional offset.  This is used for query
1934          * pages.  The SQL should be adjusted so that only the first $limit rows
1935          * are returned.  If $offset is provided as well, then the first $offset
1936          * rows should be discarded, and the next $limit rows should be returned.
1937          * If the result of the query is not ordered, then the rows to be returned
1938          * are theoretically arbitrary.
1939          *
1940          * $sql is expected to be a SELECT, if that makes a difference.  For
1941          * UPDATE, limitResultForUpdate should be used.
1942          *
1943          * The version provided by default works in MySQL and SQLite.  It will very
1944          * likely need to be overridden for most other DBMSes.
1945          *
1946          * @param $sql String: SQL query we will append the limit too
1947          * @param $limit Integer: the SQL limit
1948          * @param $offset Integer the SQL offset (default false)
1949          */
1950         function limitResult( $sql, $limit, $offset = false ) {
1951                 if ( !is_numeric( $limit ) ) {
1952                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
1953                 }
1954
1955                 return "$sql LIMIT "
1956                                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
1957                                 . "{$limit} ";
1958         }
1959
1960         function limitResultForUpdate( $sql, $num ) {
1961                 return $this->limitResult( $sql, $num, 0 );
1962         }
1963
1964         /**
1965          * Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
1966          * within the UNION construct.
1967          * @return Boolean
1968          */
1969         function unionSupportsOrderAndLimit() {
1970                 return true; // True for almost every DB supported
1971         }
1972
1973         /**
1974          * Construct a UNION query
1975          * This is used for providing overload point for other DB abstractions
1976          * not compatible with the MySQL syntax.
1977          * @param $sqls Array: SQL statements to combine
1978          * @param $all Boolean: use UNION ALL
1979          * @return String: SQL fragment
1980          */
1981         function unionQueries( $sqls, $all ) {
1982                 $glue = $all ? ') UNION ALL (' : ') UNION (';
1983                 return '(' . implode( $glue, $sqls ) . ')';
1984         }
1985
1986         /**
1987          * Returns an SQL expression for a simple conditional.  This doesn't need
1988          * to be overridden unless CASE isn't supported in your DBMS.
1989          *
1990          * @param $cond String: SQL expression which will result in a boolean value
1991          * @param $trueVal String: SQL expression to return if true
1992          * @param $falseVal String: SQL expression to return if false
1993          * @return String: SQL fragment
1994          */
1995         function conditional( $cond, $trueVal, $falseVal ) {
1996                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
1997         }
1998
1999         /**
2000          * Returns a comand for str_replace function in SQL query.
2001          * Uses REPLACE() in MySQL
2002          *
2003          * @param $orig String: column to modify
2004          * @param $old String: column to seek
2005          * @param $new String: column to replace with
2006          */
2007         function strreplace( $orig, $old, $new ) {
2008                 return "REPLACE({$orig}, {$old}, {$new})";
2009         }
2010
2011         /**
2012          * Determines if the last failure was due to a deadlock
2013          * STUB
2014          */
2015         function wasDeadlock() {
2016                 return false;
2017         }
2018
2019         /**
2020          * Determines if the last query error was something that should be dealt
2021          * with by pinging the connection and reissuing the query.
2022          * STUB
2023          */
2024         function wasErrorReissuable() {
2025                 return false;
2026         }
2027
2028         /**
2029          * Determines if the last failure was due to the database being read-only.
2030          * STUB
2031          */
2032         function wasReadOnlyError() {
2033                 return false;
2034         }
2035
2036         /**
2037          * Perform a deadlock-prone transaction.
2038          *
2039          * This function invokes a callback function to perform a set of write
2040          * queries. If a deadlock occurs during the processing, the transaction
2041          * will be rolled back and the callback function will be called again.
2042          *
2043          * Usage:
2044          *   $dbw->deadlockLoop( callback, ... );
2045          *
2046          * Extra arguments are passed through to the specified callback function.
2047          *
2048          * Returns whatever the callback function returned on its successful,
2049          * iteration, or false on error, for example if the retry limit was
2050          * reached.
2051          */
2052         function deadlockLoop() {
2053                 $myFname = 'DatabaseBase::deadlockLoop';
2054
2055                 $this->begin();
2056                 $args = func_get_args();
2057                 $function = array_shift( $args );
2058                 $oldIgnore = $this->ignoreErrors( true );
2059                 $tries = DEADLOCK_TRIES;
2060
2061                 if ( is_array( $function ) ) {
2062                         $fname = $function[0];
2063                 } else {
2064                         $fname = $function;
2065                 }
2066
2067                 do {
2068                         $retVal = call_user_func_array( $function, $args );
2069                         $error = $this->lastError();
2070                         $errno = $this->lastErrno();
2071                         $sql = $this->lastQuery();
2072
2073                         if ( $errno ) {
2074                                 if ( $this->wasDeadlock() ) {
2075                                         # Retry
2076                                         usleep( mt_rand( DEADLOCK_DELAY_MIN, DEADLOCK_DELAY_MAX ) );
2077                                 } else {
2078                                         $this->reportQueryError( $error, $errno, $sql, $fname );
2079                                 }
2080                         }
2081                 } while ( $this->wasDeadlock() && --$tries > 0 );
2082
2083                 $this->ignoreErrors( $oldIgnore );
2084
2085                 if ( $tries <= 0 ) {
2086                         $this->rollback( $myFname );
2087                         $this->reportQueryError( $error, $errno, $sql, $fname );
2088                         return false;
2089                 } else {
2090                         $this->commit( $myFname );
2091                         return $retVal;
2092                 }
2093         }
2094
2095         /**
2096          * Do a SELECT MASTER_POS_WAIT()
2097          *
2098          * @param $pos MySQLMasterPos object
2099          * @param $timeout Integer: the maximum number of seconds to wait for synchronisation
2100          */
2101         function masterPosWait( MySQLMasterPos $pos, $timeout ) {
2102                 $fname = 'DatabaseBase::masterPosWait';
2103                 wfProfileIn( $fname );
2104
2105                 # Commit any open transactions
2106                 if ( $this->mTrxLevel ) {
2107                         $this->commit();
2108                 }
2109
2110                 if ( !is_null( $this->mFakeSlaveLag ) ) {
2111                         $wait = intval( ( $pos->pos - microtime( true ) + $this->mFakeSlaveLag ) * 1e6 );
2112
2113                         if ( $wait > $timeout * 1e6 ) {
2114                                 wfDebug( "Fake slave timed out waiting for $pos ($wait us)\n" );
2115                                 wfProfileOut( $fname );
2116                                 return -1;
2117                         } elseif ( $wait > 0 ) {
2118                                 wfDebug( "Fake slave waiting $wait us\n" );
2119                                 usleep( $wait );
2120                                 wfProfileOut( $fname );
2121                                 return 1;
2122                         } else {
2123                                 wfDebug( "Fake slave up to date ($wait us)\n" );
2124                                 wfProfileOut( $fname );
2125                                 return 0;
2126                         }
2127                 }
2128
2129                 # Call doQuery() directly, to avoid opening a transaction if DBO_TRX is set
2130                 $encFile = $this->addQuotes( $pos->file );
2131                 $encPos = intval( $pos->pos );
2132                 $sql = "SELECT MASTER_POS_WAIT($encFile, $encPos, $timeout)";
2133                 $res = $this->doQuery( $sql );
2134
2135                 if ( $res && $row = $this->fetchRow( $res ) ) {
2136                         wfProfileOut( $fname );
2137                         return $row[0];
2138                 } else {
2139                         wfProfileOut( $fname );
2140                         return false;
2141                 }
2142         }
2143
2144         /**
2145          * Get the position of the master from SHOW SLAVE STATUS
2146          */
2147         function getSlavePos() {
2148                 if ( !is_null( $this->mFakeSlaveLag ) ) {
2149                         $pos = new MySQLMasterPos( 'fake', microtime( true ) - $this->mFakeSlaveLag );
2150                         wfDebug( __METHOD__ . ": fake slave pos = $pos\n" );
2151                         return $pos;
2152                 }
2153
2154                 $res = $this->query( 'SHOW SLAVE STATUS', 'DatabaseBase::getSlavePos' );
2155                 $row = $this->fetchObject( $res );
2156
2157                 if ( $row ) {
2158                         $pos = isset( $row->Exec_master_log_pos ) ? $row->Exec_master_log_pos : $row->Exec_Master_Log_Pos;
2159                         return new MySQLMasterPos( $row->Relay_Master_Log_File, $pos );
2160                 } else {
2161                         return false;
2162                 }
2163         }
2164
2165         /**
2166          * Get the position of the master from SHOW MASTER STATUS
2167          */
2168         function getMasterPos() {
2169                 if ( $this->mFakeMaster ) {
2170                         return new MySQLMasterPos( 'fake', microtime( true ) );
2171                 }
2172
2173                 $res = $this->query( 'SHOW MASTER STATUS', 'DatabaseBase::getMasterPos' );
2174                 $row = $this->fetchObject( $res );
2175
2176                 if ( $row ) {
2177                         return new MySQLMasterPos( $row->File, $row->Position );
2178                 } else {
2179                         return false;
2180                 }
2181         }
2182
2183         /**
2184          * Begin a transaction, committing any previously open transaction
2185          */
2186         function begin( $fname = 'DatabaseBase::begin' ) {
2187                 $this->query( 'BEGIN', $fname );
2188                 $this->mTrxLevel = 1;
2189         }
2190
2191         /**
2192          * End a transaction
2193          */
2194         function commit( $fname = 'DatabaseBase::commit' ) {
2195                 if ( $this->mTrxLevel ) {
2196                         $this->query( 'COMMIT', $fname );
2197                         $this->mTrxLevel = 0;
2198                 }
2199         }
2200
2201         /**
2202          * Rollback a transaction.
2203          * No-op on non-transactional databases.
2204          */
2205         function rollback( $fname = 'DatabaseBase::rollback' ) {
2206                 if ( $this->mTrxLevel ) {
2207                         $this->query( 'ROLLBACK', $fname, true );
2208                         $this->mTrxLevel = 0;
2209                 }
2210         }
2211
2212         /**
2213          * Begin a transaction, committing any previously open transaction
2214          * @deprecated use begin()
2215          */
2216         function immediateBegin( $fname = 'DatabaseBase::immediateBegin' ) {
2217                 wfDeprecated( __METHOD__ );
2218                 $this->begin();
2219         }
2220
2221         /**
2222          * Commit transaction, if one is open
2223          * @deprecated use commit()
2224          */
2225         function immediateCommit( $fname = 'DatabaseBase::immediateCommit' ) {
2226                 wfDeprecated( __METHOD__ );
2227                 $this->commit();
2228         }
2229
2230         /**
2231          * Creates a new table with structure copied from existing table
2232          * Note that unlike most database abstraction functions, this function does not
2233          * automatically append database prefix, because it works at a lower
2234          * abstraction level.
2235          *
2236          * @param $oldName String: name of table whose structure should be copied
2237          * @param $newName String: name of table to be created
2238          * @param $temporary Boolean: whether the new table should be temporary
2239          * @param $fname String: calling function name
2240          * @return Boolean: true if operation was successful
2241          */
2242         function duplicateTableStructure( $oldName, $newName, $temporary = false, $fname = 'DatabaseBase::duplicateTableStructure' ) {
2243                 throw new MWException( 'DatabaseBase::duplicateTableStructure is not implemented in descendant class' );
2244         }
2245
2246         /**
2247          * Return MW-style timestamp used for MySQL schema
2248          */
2249         function timestamp( $ts = 0 ) {
2250                 return wfTimestamp( TS_MW, $ts );
2251         }
2252
2253         /**
2254          * Local database timestamp format or null
2255          */
2256         function timestampOrNull( $ts = null ) {
2257                 if ( is_null( $ts ) ) {
2258                         return null;
2259                 } else {
2260                         return $this->timestamp( $ts );
2261                 }
2262         }
2263
2264         /**
2265          * @todo document
2266          */
2267         function resultObject( $result ) {
2268                 if ( empty( $result ) ) {
2269                         return false;
2270                 } elseif ( $result instanceof ResultWrapper ) {
2271                         return $result;
2272                 } elseif ( $result === true ) {
2273                         // Successful write query
2274                         return $result;
2275                 } else {
2276                         return new ResultWrapper( $this, $result );
2277                 }
2278         }
2279
2280         /**
2281          * Return aggregated value alias
2282          */
2283         function aggregateValue ( $valuedata, $valuename = 'value' ) {
2284                 return $valuename;
2285         }
2286
2287         /**
2288          * Ping the server and try to reconnect if it there is no connection
2289          *
2290          * @return bool Success or failure
2291          */
2292         function ping() {
2293                 # Stub.  Not essential to override.
2294                 return true;
2295         }
2296
2297         /**
2298          * Get slave lag.
2299          * Currently supported only by MySQL
2300          * @return Database replication lag in seconds
2301          */
2302         function getLag() {
2303                 return intval( $this->mFakeSlaveLag );
2304         }
2305
2306         /**
2307          * Get status information from SHOW STATUS in an associative array
2308          */
2309         function getStatus( $which = "%" ) {
2310                 $res = $this->query( "SHOW STATUS LIKE '{$which}'" );
2311                 $status = array();
2312
2313                 foreach ( $res as $row ) {
2314                         $status[$row->Variable_name] = $row->Value;
2315                 }
2316
2317                 return $status;
2318         }
2319
2320         /**
2321          * Return the maximum number of items allowed in a list, or 0 for unlimited.
2322          */
2323         function maxListLen() {
2324                 return 0;
2325         }
2326
2327         function encodeBlob( $b ) {
2328                 return $b;
2329         }
2330
2331         function decodeBlob( $b ) {
2332                 return $b;
2333         }
2334
2335         /**
2336          * Override database's default connection timeout.  May be useful for very
2337          * long batch queries such as full-wiki dumps, where a single query reads
2338          * out over hours or days.  May or may not be necessary for non-MySQL
2339          * databases.  For most purposes, leaving it as a no-op should be fine.
2340          *
2341          * @param $timeout Integer in seconds
2342          */
2343         public function setTimeout( $timeout ) {}
2344
2345         /**
2346          * Read and execute SQL commands from a file.
2347          * Returns true on success, error string or exception on failure (depending on object's error ignore settings)
2348          * @param $filename String: File name to open
2349          * @param $lineCallback Callback: Optional function called before reading each line
2350          * @param $resultCallback Callback: Optional function called for each MySQL result
2351          * @param $fname String: Calling function name or false if name should be generated dynamically
2352          *              using $filename
2353          */
2354         function sourceFile( $filename, $lineCallback = false, $resultCallback = false, $fname = false ) {
2355                 $fp = fopen( $filename, 'r' );
2356
2357                 if ( false === $fp ) {
2358                         if ( !defined( "MEDIAWIKI_INSTALL" ) )
2359                                 throw new MWException( "Could not open \"{$filename}\".\n" );
2360                         else
2361                                 return "Could not open \"{$filename}\".\n";
2362                 }
2363
2364                 if ( !$fname ) {
2365                         $fname = __METHOD__ . "( $filename )";
2366                 }
2367
2368                 try {
2369                         $error = $this->sourceStream( $fp, $lineCallback, $resultCallback, $fname );
2370                 }
2371                 catch ( MWException $e ) {
2372                         if ( defined( "MEDIAWIKI_INSTALL" ) ) {
2373                                 $error = $e->getMessage();
2374                         } else {
2375                                 fclose( $fp );
2376                                 throw $e;
2377                         }
2378                 }
2379
2380                 fclose( $fp );
2381
2382                 return $error;
2383         }
2384
2385         /**
2386          * Get the full path of a patch file. Originally based on archive()
2387          * from updaters.inc. Keep in mind this always returns a patch, as
2388          * it fails back to MySQL if no DB-specific patch can be found
2389          *
2390          * @param $patch String The name of the patch, like patch-something.sql
2391          * @return String Full path to patch file
2392          */
2393         public function patchPath( $patch ) {
2394                 global $IP;
2395
2396                 $dbType = $this->getType();
2397                 if ( file_exists( "$IP/maintenance/$dbType/archives/$patch" ) ) {
2398                         return "$IP/maintenance/$dbType/archives/$patch";
2399                 } else {
2400                         return "$IP/maintenance/archives/$patch";
2401                 }
2402         }
2403
2404         /**
2405          * Read and execute commands from an open file handle
2406          * Returns true on success, error string or exception on failure (depending on object's error ignore settings)
2407          * @param $fp String: File handle
2408          * @param $lineCallback Callback: Optional function called before reading each line
2409          * @param $resultCallback Callback: Optional function called for each MySQL result
2410          * @param $fname String: Calling function name
2411          */
2412         function sourceStream( $fp, $lineCallback = false, $resultCallback = false, $fname = 'DatabaseBase::sourceStream' ) {
2413                 $cmd = "";
2414                 $done = false;
2415                 $dollarquote = false;
2416
2417                 while ( ! feof( $fp ) ) {
2418                         if ( $lineCallback ) {
2419                                 call_user_func( $lineCallback );
2420                         }
2421
2422                         $line = trim( fgets( $fp, 1024 ) );
2423                         $sl = strlen( $line ) - 1;
2424
2425                         if ( $sl < 0 ) {
2426                                 continue;
2427                         }
2428
2429                         if ( '-' == $line { 0 } && '-' == $line { 1 } ) {
2430                                 continue;
2431                         }
2432
2433                         # # Allow dollar quoting for function declarations
2434                         if ( substr( $line, 0, 4 ) == '$mw$' ) {
2435                                 if ( $dollarquote ) {
2436                                         $dollarquote = false;
2437                                         $done = true;
2438                                 }
2439                                 else {
2440                                         $dollarquote = true;
2441                                 }
2442                         }
2443                         else if ( !$dollarquote ) {
2444                                 if ( ';' == $line { $sl } && ( $sl < 2 || ';' != $line { $sl - 1 } ) ) {
2445                                         $done = true;
2446                                         $line = substr( $line, 0, $sl );
2447                                 }
2448                         }
2449
2450                         if ( $cmd != '' ) {
2451                                 $cmd .= ' ';
2452                         }
2453
2454                         $cmd .= "$line\n";
2455
2456                         if ( $done ) {
2457                                 $cmd = str_replace( ';;', ";", $cmd );
2458                                 $cmd = $this->replaceVars( $cmd );
2459                                 $res = $this->query( $cmd, $fname );
2460
2461                                 if ( $resultCallback ) {
2462                                         call_user_func( $resultCallback, $res, $this );
2463                                 }
2464
2465                                 if ( false === $res ) {
2466                                         $err = $this->lastError();
2467                                         return "Query \"{$cmd}\" failed with error code \"$err\".\n";
2468                                 }
2469
2470                                 $cmd = '';
2471                                 $done = false;
2472                         }
2473                 }
2474
2475                 return true;
2476         }
2477
2478         /**
2479          * Replace variables in sourced SQL
2480          */
2481         protected function replaceVars( $ins ) {
2482                 $varnames = array(
2483                         'wgDBserver', 'wgDBname', 'wgDBintlname', 'wgDBuser',
2484                         'wgDBpassword', 'wgDBsqluser', 'wgDBsqlpassword',
2485                         'wgDBadminuser', 'wgDBadminpassword', 'wgDBTableOptions',
2486                 );
2487
2488                 // Ordinary variables
2489                 foreach ( $varnames as $var ) {
2490                         if ( isset( $GLOBALS[$var] ) ) {
2491                                 $val = addslashes( $GLOBALS[$var] ); // FIXME: safety check?
2492                                 $ins = str_replace( '{$' . $var . '}', $val, $ins );
2493                                 $ins = str_replace( '/*$' . $var . '*/`', '`' . $val, $ins );
2494                                 $ins = str_replace( '/*$' . $var . '*/', $val, $ins );
2495                         }
2496                 }
2497
2498                 // Table prefixes
2499                 $ins = preg_replace_callback( '!/\*(?:\$wgDBprefix|_)\*/([a-zA-Z_0-9]*)!',
2500                         array( $this, 'tableNameCallback' ), $ins );
2501
2502                 // Index names
2503                 $ins = preg_replace_callback( '!/\*i\*/([a-zA-Z_0-9]*)!',
2504                         array( $this, 'indexNameCallback' ), $ins );
2505
2506                 return $ins;
2507         }
2508
2509         /**
2510          * Table name callback
2511          * @private
2512          */
2513         protected function tableNameCallback( $matches ) {
2514                 return $this->tableName( $matches[1] );
2515         }
2516
2517         /**
2518          * Index name callback
2519          */
2520         protected function indexNameCallback( $matches ) {
2521                 return $this->indexName( $matches[1] );
2522         }
2523
2524         /**
2525          * Build a concatenation list to feed into a SQL query
2526          * @param $stringList Array: list of raw SQL expressions; caller is responsible for any quoting
2527          * @return String
2528          */
2529         function buildConcat( $stringList ) {
2530                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
2531         }
2532
2533         /**
2534          * Acquire a named lock
2535          *
2536          * Abstracted from Filestore::lock() so child classes can implement for
2537          * their own needs.
2538          *
2539          * @param $lockName String: name of lock to aquire
2540          * @param $method String: name of method calling us
2541          * @param $timeout Integer: timeout
2542          * @return Boolean
2543          */
2544         public function lock( $lockName, $method, $timeout = 5 ) {
2545                 return true;
2546         }
2547
2548         /**
2549          * Release a lock.
2550          *
2551          * @param $lockName String: Name of lock to release
2552          * @param $method String: Name of method calling us
2553          *
2554          * @return Returns 1 if the lock was released, 0 if the lock was not established
2555          * by this thread (in which case the lock is not released), and NULL if the named
2556          * lock did not exist
2557          */
2558         public function unlock( $lockName, $method ) {
2559                 return true;
2560         }
2561
2562         /**
2563          * Lock specific tables
2564          *
2565          * @param $read Array of tables to lock for read access
2566          * @param $write Array of tables to lock for write access
2567          * @param $method String name of caller
2568          * @param $lowPriority bool Whether to indicate writes to be LOW PRIORITY
2569          */
2570         public function lockTables( $read, $write, $method, $lowPriority = true ) {
2571                 return true;
2572         }
2573
2574         /**
2575          * Unlock specific tables
2576          *
2577          * @param $method String the caller
2578          */
2579         public function unlockTables( $method ) {
2580                 return true;
2581         }
2582
2583         /**
2584          * Get search engine class. All subclasses of this need to implement this
2585          * if they wish to use searching.
2586          *
2587          * @return String
2588          */
2589         public function getSearchEngine() {
2590                 return 'SearchEngineDummy';
2591         }
2592
2593         /**
2594          * Allow or deny "big selects" for this session only. This is done by setting
2595          * the sql_big_selects session variable.
2596          *
2597          * This is a MySQL-specific feature.
2598          *
2599          * @param $value Mixed: true for allow, false for deny, or "default" to restore the initial value
2600          */
2601         public function setBigSelects( $value = true ) {
2602                 // no-op
2603         }
2604 }
2605
2606 /******************************************************************************
2607  * Utility classes
2608  *****************************************************************************/
2609
2610 /**
2611  * Utility class.
2612  * @ingroup Database
2613  */
2614 class DBObject {
2615         public $mData;
2616
2617         function __construct( $data ) {
2618                 $this->mData = $data;
2619         }
2620
2621         function isLOB() {
2622                 return false;
2623         }
2624
2625         function data() {
2626                 return $this->mData;
2627         }
2628 }
2629
2630 /**
2631  * Utility class
2632  * @ingroup Database
2633  *
2634  * This allows us to distinguish a blob from a normal string and an array of strings
2635  */
2636 class Blob {
2637         private $mData;
2638
2639         function __construct( $data ) {
2640                 $this->mData = $data;
2641         }
2642
2643         function fetch() {
2644                 return $this->mData;
2645         }
2646 }
2647
2648 /**
2649  * Utility class.
2650  * @ingroup Database
2651  */
2652 class MySQLField {
2653         private $name, $tablename, $default, $max_length, $nullable,
2654                 $is_pk, $is_unique, $is_multiple, $is_key, $type;
2655
2656         function __construct ( $info ) {
2657                 $this->name = $info->name;
2658                 $this->tablename = $info->table;
2659                 $this->default = $info->def;
2660                 $this->max_length = $info->max_length;
2661                 $this->nullable = !$info->not_null;
2662                 $this->is_pk = $info->primary_key;
2663                 $this->is_unique = $info->unique_key;
2664                 $this->is_multiple = $info->multiple_key;
2665                 $this->is_key = ( $this->is_pk || $this->is_unique || $this->is_multiple );
2666                 $this->type = $info->type;
2667         }
2668
2669         function name() {
2670                 return $this->name;
2671         }
2672
2673         function tableName() {
2674                 return $this->tableName;
2675         }
2676
2677         function defaultValue() {
2678                 return $this->default;
2679         }
2680
2681         function maxLength() {
2682                 return $this->max_length;
2683         }
2684
2685         function nullable() {
2686                 return $this->nullable;
2687         }
2688
2689         function isKey() {
2690                 return $this->is_key;
2691         }
2692
2693         function isMultipleKey() {
2694                 return $this->is_multiple;
2695         }
2696
2697         function type() {
2698                 return $this->type;
2699         }
2700 }
2701
2702 /******************************************************************************
2703  * Error classes
2704  *****************************************************************************/
2705
2706 /**
2707  * Database error base class
2708  * @ingroup Database
2709  */
2710 class DBError extends MWException {
2711         public $db;
2712
2713         /**
2714          * Construct a database error
2715          * @param $db Database object which threw the error
2716          * @param $error A simple error message to be used for debugging
2717          */
2718         function __construct( DatabaseBase &$db, $error ) {
2719                 $this->db =& $db;
2720                 parent::__construct( $error );
2721         }
2722
2723         function getText() {
2724                 global $wgShowDBErrorBacktrace;
2725
2726                 $s = $this->getMessage() . "\n";
2727
2728                 if ( $wgShowDBErrorBacktrace ) {
2729                         $s .= "Backtrace:\n" . $this->getTraceAsString() . "\n";
2730                 }
2731
2732                 return $s;
2733         }
2734 }
2735
2736 /**
2737  * @ingroup Database
2738  */
2739 class DBConnectionError extends DBError {
2740         public $error;
2741
2742         function __construct( DatabaseBase &$db, $error = 'unknown error' ) {
2743                 $msg = 'DB connection error';
2744
2745                 if ( trim( $error ) != '' ) {
2746                         $msg .= ": $error";
2747                 }
2748
2749                 $this->error = $error;
2750
2751                 parent::__construct( $db, $msg );
2752         }
2753
2754         function useOutputPage() {
2755                 // Not likely to work
2756                 return false;
2757         }
2758
2759         function useMessageCache() {
2760                 // Not likely to work
2761                 return false;
2762         }
2763
2764         function getLogMessage() {
2765                 # Don't send to the exception log
2766                 return false;
2767         }
2768
2769         function getPageTitle() {
2770                 global $wgSitename, $wgLang;
2771
2772                 $header = "$wgSitename has a problem";
2773
2774                 if ( $wgLang instanceof Language ) {
2775                         $header = htmlspecialchars( $wgLang->getMessage( 'dberr-header' ) );
2776                 }
2777
2778                 return $header;
2779         }
2780
2781         function getHTML() {
2782                 global $wgLang, $wgMessageCache, $wgUseFileCache, $wgShowDBErrorBacktrace;
2783
2784                 $sorry = 'Sorry! This site is experiencing technical difficulties.';
2785                 $again = 'Try waiting a few minutes and reloading.';
2786                 $info  = '(Can\'t contact the database server: $1)';
2787
2788                 if ( $wgLang instanceof Language ) {
2789                         $sorry = htmlspecialchars( $wgLang->getMessage( 'dberr-problems' ) );
2790                         $again = htmlspecialchars( $wgLang->getMessage( 'dberr-again' ) );
2791                         $info  = htmlspecialchars( $wgLang->getMessage( 'dberr-info' ) );
2792                 }
2793
2794                 # No database access
2795                 if ( is_object( $wgMessageCache ) ) {
2796                         $wgMessageCache->disable();
2797                 }
2798
2799                 if ( trim( $this->error ) == '' ) {
2800                         $this->error = $this->db->getProperty( 'mServer' );
2801                 }
2802
2803                 $noconnect = "<p><strong>$sorry</strong><br />$again</p><p><small>$info</small></p>";
2804                 $text = str_replace( '$1', $this->error, $noconnect );
2805
2806                 if ( $wgShowDBErrorBacktrace ) {
2807                         $text .= '<p>Backtrace:</p><p>' . nl2br( htmlspecialchars( $this->getTraceAsString() ) );
2808                 }
2809
2810                 $extra = $this->searchForm();
2811
2812                 if ( $wgUseFileCache ) {
2813                         try {
2814                                 $cache = $this->fileCachedPage();
2815                                 # Cached version on file system?
2816                                 if ( $cache !== null ) {
2817                                         # Hack: extend the body for error messages
2818                                         $cache = str_replace( array( '</html>', '</body>' ), '', $cache );
2819                                         # Add cache notice...
2820                                         $cachederror = "This is a cached copy of the requested page, and may not be up to date. ";
2821
2822                                         # Localize it if possible...
2823                                         if ( $wgLang instanceof Language ) {
2824                                                 $cachederror = htmlspecialchars( $wgLang->getMessage( 'dberr-cachederror' ) );
2825                                         }
2826
2827                                         $warning = "<div style='color:red;font-size:150%;font-weight:bold;'>$cachederror</div>";
2828
2829                                         # Output cached page with notices on bottom and re-close body
2830                                         return "{$cache}{$warning}<hr />$text<hr />$extra</body></html>";
2831                                 }
2832                         } catch ( MWException $e ) {
2833                                 // Do nothing, just use the default page
2834                         }
2835                 }
2836
2837                 # Headers needed here - output is just the error message
2838                 return $this->htmlHeader() . "$text<hr />$extra" . $this->htmlFooter();
2839         }
2840
2841         function searchForm() {
2842                 global $wgSitename, $wgServer, $wgLang, $wgInputEncoding;
2843
2844                 $usegoogle = "You can try searching via Google in the meantime.";
2845                 $outofdate = "Note that their indexes of our content may be out of date.";
2846                 $googlesearch = "Search";
2847
2848                 if ( $wgLang instanceof Language ) {
2849                         $usegoogle = htmlspecialchars( $wgLang->getMessage( 'dberr-usegoogle' ) );
2850                         $outofdate = htmlspecialchars( $wgLang->getMessage( 'dberr-outofdate' ) );
2851                         $googlesearch  = htmlspecialchars( $wgLang->getMessage( 'searchbutton' ) );
2852                 }
2853
2854                 $search = htmlspecialchars( @$_REQUEST['search'] );
2855
2856                 $trygoogle = <<<EOT
2857 <div style="margin: 1.5em">$usegoogle<br />
2858 <small>$outofdate</small></div>
2859 <!-- SiteSearch Google -->
2860 <form method="get" action="http://www.google.com/search" id="googlesearch">
2861         <input type="hidden" name="domains" value="$wgServer" />
2862         <input type="hidden" name="num" value="50" />
2863         <input type="hidden" name="ie" value="$wgInputEncoding" />
2864         <input type="hidden" name="oe" value="$wgInputEncoding" />
2865
2866         <input type="text" name="q" size="31" maxlength="255" value="$search" />
2867         <input type="submit" name="btnG" value="$googlesearch" />
2868   <div>
2869         <input type="radio" name="sitesearch" id="gwiki" value="$wgServer" checked="checked" /><label for="gwiki">$wgSitename</label>
2870         <input type="radio" name="sitesearch" id="gWWW" value="" /><label for="gWWW">WWW</label>
2871   </div>
2872 </form>
2873 <!-- SiteSearch Google -->
2874 EOT;
2875                 return $trygoogle;
2876         }
2877
2878         function fileCachedPage() {
2879                 global $wgTitle, $title, $wgLang, $wgOut;
2880
2881                 if ( $wgOut->isDisabled() ) {
2882                         return; // Done already?
2883                 }
2884
2885                 $mainpage = 'Main Page';
2886
2887                 if ( $wgLang instanceof Language ) {
2888                         $mainpage    = htmlspecialchars( $wgLang->getMessage( 'mainpage' ) );
2889                 }
2890
2891                 if ( $wgTitle ) {
2892                         $t =& $wgTitle;
2893                 } elseif ( $title ) {
2894                         $t = Title::newFromURL( $title );
2895                 } else {
2896                         $t = Title::newFromText( $mainpage );
2897                 }
2898
2899                 $cache = new HTMLFileCache( $t );
2900                 if ( $cache->isFileCached() ) {
2901                         return $cache->fetchPageText();
2902                 } else {
2903                         return '';
2904                 }
2905         }
2906
2907         function htmlBodyOnly() {
2908                 return true;
2909         }
2910 }
2911
2912 /**
2913  * @ingroup Database
2914  */
2915 class DBQueryError extends DBError {
2916         public $error, $errno, $sql, $fname;
2917
2918         function __construct( DatabaseBase &$db, $error, $errno, $sql, $fname ) {
2919                 $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" .
2920                   "Query: $sql\n" .
2921                   "Function: $fname\n" .
2922                   "Error: $errno $error\n";
2923
2924                 parent::__construct( $db, $message );
2925
2926                 $this->error = $error;
2927                 $this->errno = $errno;
2928                 $this->sql = $sql;
2929                 $this->fname = $fname;
2930         }
2931
2932         function getText() {
2933                 global $wgShowDBErrorBacktrace;
2934
2935                 if ( $this->useMessageCache() ) {
2936                         $s = wfMsg( 'dberrortextcl', htmlspecialchars( $this->getSQL() ),
2937                                 htmlspecialchars( $this->fname ), $this->errno, htmlspecialchars( $this->error ) ) . "\n";
2938
2939                         if ( $wgShowDBErrorBacktrace ) {
2940                                 $s .= "Backtrace:\n" . $this->getTraceAsString() . "\n";
2941                         }
2942
2943                         return $s;
2944                 } else {
2945                         return parent::getText();
2946                 }
2947         }
2948
2949         function getSQL() {
2950                 global $wgShowSQLErrors;
2951
2952                 if ( !$wgShowSQLErrors ) {
2953                         return $this->msg( 'sqlhidden', 'SQL hidden' );
2954                 } else {
2955                         return $this->sql;
2956                 }
2957         }
2958
2959         function getLogMessage() {
2960                 # Don't send to the exception log
2961                 return false;
2962         }
2963
2964         function getPageTitle() {
2965                 return $this->msg( 'databaseerror', 'Database error' );
2966         }
2967
2968         function getHTML() {
2969                 global $wgShowDBErrorBacktrace;
2970
2971                 if ( $this->useMessageCache() ) {
2972                         $s = wfMsgNoDB( 'dberrortext', htmlspecialchars( $this->getSQL() ),
2973                           htmlspecialchars( $this->fname ), $this->errno, htmlspecialchars( $this->error ) );
2974                 } else {
2975                         $s = nl2br( htmlspecialchars( $this->getMessage() ) );
2976                 }
2977
2978                 if ( $wgShowDBErrorBacktrace ) {
2979                         $s .= '<p>Backtrace:</p><p>' . nl2br( htmlspecialchars( $this->getTraceAsString() ) );
2980                 }
2981
2982                 return $s;
2983         }
2984 }
2985
2986 /**
2987  * @ingroup Database
2988  */
2989 class DBUnexpectedError extends DBError {}
2990
2991
2992 /**
2993  * Result wrapper for grabbing data queried by someone else
2994  * @ingroup Database
2995  */
2996 class ResultWrapper implements Iterator {
2997         var $db, $result, $pos = 0, $currentRow = null;
2998
2999         /**
3000          * Create a new result object from a result resource and a Database object
3001          */
3002         function __construct( $database, $result ) {
3003                 $this->db = $database;
3004
3005                 if ( $result instanceof ResultWrapper ) {
3006                         $this->result = $result->result;
3007                 } else {
3008                         $this->result = $result;
3009                 }
3010         }
3011
3012         /**
3013          * Get the number of rows in a result object
3014          */
3015         function numRows() {
3016                 return $this->db->numRows( $this );
3017         }
3018
3019         /**
3020          * Fetch the next row from the given result object, in object form.
3021          * Fields can be retrieved with $row->fieldname, with fields acting like
3022          * member variables.
3023          *
3024          * @return MySQL row object
3025          * @throws DBUnexpectedError Thrown if the database returns an error
3026          */
3027         function fetchObject() {
3028                 return $this->db->fetchObject( $this );
3029         }
3030
3031         /**
3032          * Fetch the next row from the given result object, in associative array
3033          * form.  Fields are retrieved with $row['fieldname'].
3034          *
3035          * @return MySQL row object
3036          * @throws DBUnexpectedError Thrown if the database returns an error
3037          */
3038         function fetchRow() {
3039                 return $this->db->fetchRow( $this );
3040         }
3041
3042         /**
3043          * Free a result object
3044          */
3045         function free() {
3046                 $this->db->freeResult( $this );
3047                 unset( $this->result );
3048                 unset( $this->db );
3049         }
3050
3051         /**
3052          * Change the position of the cursor in a result object
3053          * See mysql_data_seek()
3054          */
3055         function seek( $row ) {
3056                 $this->db->dataSeek( $this, $row );
3057         }
3058
3059         /*********************
3060          * Iterator functions
3061          * Note that using these in combination with the non-iterator functions
3062          * above may cause rows to be skipped or repeated.
3063          */
3064
3065         function rewind() {
3066                 if ( $this->numRows() ) {
3067                         $this->db->dataSeek( $this, 0 );
3068                 }
3069                 $this->pos = 0;
3070                 $this->currentRow = null;
3071         }
3072
3073         function current() {
3074                 if ( is_null( $this->currentRow ) ) {
3075                         $this->next();
3076                 }
3077                 return $this->currentRow;
3078         }
3079
3080         function key() {
3081                 return $this->pos;
3082         }
3083
3084         function next() {
3085                 $this->pos++;
3086                 $this->currentRow = $this->fetchObject();
3087                 return $this->currentRow;
3088         }
3089
3090         function valid() {
3091                 return $this->current() !== false;
3092         }
3093 }
3094
3095 /**
3096  * Overloads the relevant methods of the real ResultsWrapper so it
3097  * doesn't go anywhere near an actual database.
3098  */
3099 class FakeResultWrapper extends ResultWrapper {
3100         var $result     = array();
3101         var $db         = null; // And it's going to stay that way :D
3102         var $pos        = 0;
3103         var $currentRow = null;
3104
3105         function __construct( $array ) {
3106                 $this->result = $array;
3107         }
3108
3109         function numRows() {
3110                 return count( $this->result );
3111         }
3112
3113         function fetchRow() {
3114                 $this->currentRow = $this->result[$this->pos++];
3115                 return $this->currentRow;
3116         }
3117
3118         function seek( $row ) {
3119                 $this->pos = $row;
3120         }
3121
3122         function free() {}
3123
3124         // Callers want to be able to access fields with $this->fieldName
3125         function fetchObject() {
3126                 $this->currentRow = $this->result[$this->pos++];
3127                 return (object)$this->currentRow;
3128         }
3129
3130         function rewind() {
3131                 $this->pos = 0;
3132                 $this->currentRow = null;
3133         }
3134 }
3135
3136 /**
3137  * Used by DatabaseBase::buildLike() to represent characters that have special meaning in SQL LIKE clauses
3138  * and thus need no escaping. Don't instantiate it manually, use DatabaseBase::anyChar() and anyString() instead.
3139  */
3140 class LikeMatch {
3141         private $str;
3142
3143         public function __construct( $s ) {
3144                 $this->str = $s;
3145         }
3146
3147         public function toString() {
3148                 return $this->str;
3149         }
3150 }