includes/db/Database.php

   1 <?php
   2 /**
   3  * @defgroup Database Database
   4  *
   5  * @file
   6  * @ingroup Database
   7  * This file deals with database interface functions
   8  * and query specifics/optimisations
   9  */
  10
  11 /** Number of times to re-try an operation in case of deadlock */
  12 define( 'DEADLOCK_TRIES', 4 );
  13 /** Minimum time to wait before retry, in microseconds */
  14 define( 'DEADLOCK_DELAY_MIN', 500000 );
  15 /** Maximum time to wait before retry */
  16 define( 'DEADLOCK_DELAY_MAX', 1500000 );
  17
  18 /**
  19  * Base interface for all DBMS-specific code. At a bare minimum, all of the
  20  * following must be implemented to support MediaWiki
  21  *
  22  * @file
  23  * @ingroup Database
  24  */
  25 interface DatabaseType {
  26         /**
  27          * Get the type of the DBMS, as it appears in $wgDBtype.
  28          *
  29          * @return string
  30          */
  31         public function getType();
  32
  33         /**
  34          * Open a connection to the database. Usually aborts on failure
  35          *
  36          * @param $server String: database server host
  37          * @param $user String: database user name
  38          * @param $password String: database user password
  39          * @param $dbName String: database name
  40          * @return bool
  41          * @throws DBConnectionError
  42          */
  43         public function open( $server, $user, $password, $dbName );
  44
  45         /**
  46          * The DBMS-dependent part of query()
  47          * @todo Fixme: Make this private someday
  48          *
  49          * @param  $sql String: SQL query.
  50          * @return Result object to feed to fetchObject, fetchRow, ...; or false on failure
  51          * @private
  52          */
  53         /*private*/ function doQuery( $sql );
  54
  55         /**
  56          * Fetch the next row from the given result object, in object form.
  57          * Fields can be retrieved with $row->fieldname, with fields acting like
  58          * member variables.
  59          *
  60          * @param $res SQL result object as returned from DatabaseBase::query(), etc.
  61          * @return Row object
  62          * @throws DBUnexpectedError Thrown if the database returns an error
  63          */
  64         public function fetchObject( $res );
  65
  66         /**
  67          * Fetch the next row from the given result object, in associative array
  68          * form.  Fields are retrieved with $row['fieldname'].
  69          *
  70          * @param $res SQL result object as returned from DatabaseBase::query(), etc.
  71          * @return Row object
  72          * @throws DBUnexpectedError Thrown if the database returns an error
  73          */
  74         public function fetchRow( $res );
  75
  76         /**
  77          * Get the number of rows in a result object
  78          *
  79          * @param $res Mixed: A SQL result
  80          * @return int
  81          */
  82         public function numRows( $res );
  83
  84         /**
  85          * Get the number of fields in a result object
  86          * @see http://www.php.net/mysql_num_fields
  87          *
  88          * @param $res Mixed: A SQL result
  89          * @return int
  90          */
  91         public function numFields( $res );
  92
  93         /**
  94          * Get a field name in a result object
  95          * @see http://www.php.net/mysql_field_name
  96          *
  97          * @param $res Mixed: A SQL result
  98          * @param $n Integer
  99          * @return string
 100          */
 101         public function fieldName( $res, $n );
 102
 103         /**
 104          * Get the inserted value of an auto-increment row
 105          *
 106          * The value inserted should be fetched from nextSequenceValue()
 107          *
 108          * Example:
 109          * $id = $dbw->nextSequenceValue('page_page_id_seq');
 110          * $dbw->insert('page',array('page_id' => $id));
 111          * $id = $dbw->insertId();
 112          *
 113          * @return int
 114          */
 115         public function insertId();
 116
 117         /**
 118          * Change the position of the cursor in a result object
 119          * @see http://www.php.net/mysql_data_seek
 120          *
 121          * @param $res Mixed: A SQL result
 122          * @param $row Mixed: Either MySQL row or ResultWrapper
 123          */
 124         public function dataSeek( $res, $row );
 125
 126         /**
 127          * Get the last error number
 128          * @see http://www.php.net/mysql_errno
 129          *
 130          * @return int
 131          */
 132         public function lastErrno();
 133
 134         /**
 135          * Get a description of the last error
 136          * @see http://www.php.net/mysql_error
 137          *
 138          * @return string
 139          */
 140         public function lastError();
 141
 142         /**
 143          * mysql_fetch_field() wrapper
 144          * Returns false if the field doesn't exist
 145          *
 146          * @param $table string: table name
 147          * @param $field string: field name
 148          */
 149         public function fieldInfo( $table, $field );
 150
 151         /**
 152          * Get information about an index into an object
 153          * @param $table string: Table name
 154          * @param $index string: Index name
 155          * @param $fname string: Calling function name
 156          * @return Mixed: Database-specific index description class or false if the index does not exist
 157          */
 158         function indexInfo( $table, $index, $fname = 'Database::indexInfo' );
 159
 160         /**
 161          * Get the number of rows affected by the last write query
 162          * @see http://www.php.net/mysql_affected_rows
 163          *
 164          * @return int
 165          */
 166         public function affectedRows();
 167
 168         /**
 169          * Wrapper for addslashes()
 170          *
 171          * @param $s string: to be slashed.
 172          * @return string: slashed string.
 173          */
 174         public function strencode( $s );
 175
 176         /**
 177          * Returns a wikitext link to the DB's website, e.g.,
 178          *     return "[http://www.mysql.com/ MySQL]";
 179          * Should at least contain plain text, if for some reason
 180          * your database has no website.
 181          *
 182          * @return string: wikitext of a link to the server software's web site
 183          */
 184         public static function getSoftwareLink();
 185
 186         /**
 187          * A string describing the current software version, like from
 188          * mysql_get_server_info().
 189          *
 190          * @return string: Version information from the database server.
 191          */
 192         public function getServerVersion();
 193
 194         /**
 195          * A string describing the current software version, and possibly
 196          * other details in a user-friendly way.  Will be listed on Special:Version, etc.
 197          * Use getServerVersion() to get machine-friendly information.
 198          *
 199          * @return string: Version information from the database server
 200          */
 201         public function getServerInfo();
 202 }
 203
 204 /**
 205  * Database abstraction object
 206  * @ingroup Database
 207  */
 208 abstract class DatabaseBase implements DatabaseType {
 209
 210 # ------------------------------------------------------------------------------
 211 # Variables
 212 # ------------------------------------------------------------------------------
 213
 214         protected $mLastQuery = '';
 215         protected $mDoneWrites = false;
 216         protected $mPHPError = false;
 217
 218         protected $mServer, $mUser, $mPassword, $mConn = null, $mDBname;
 219         protected $mOpened = false;
 220
 221         protected $mTablePrefix;
 222         protected $mFlags;
 223         protected $mTrxLevel = 0;
 224         protected $mErrorCount = 0;
 225         protected $mLBInfo = array();
 226         protected $mFakeSlaveLag = null, $mFakeMaster = false;
 227         protected $mDefaultBigSelects = null;
 228
 229 # ------------------------------------------------------------------------------
 230 # Accessors
 231 # ------------------------------------------------------------------------------
 232         # These optionally set a variable and return the previous state
 233
 234         /**
 235          * A string describing the current software version, and possibly
 236          * other details in a user-friendly way.  Will be listed on Special:Version, etc.
 237          * Use getServerVersion() to get machine-friendly information.
 238          *
 239          * @return string: Version information from the database server
 240          */
 241         public function getServerInfo() {
 242                 return $this->getServerVersion();
 243         }
 244
 245         /**
 246          * Boolean, controls output of large amounts of debug information
 247          */
 248         function debug( $debug = null ) {
 249                 return wfSetBit( $this->mFlags, DBO_DEBUG, $debug );
 250         }
 251
 252         /**
 253          * Turns buffering of SQL result sets on (true) or off (false).
 254          * Default is "on" and it should not be changed without good reasons.
 255          */
 256         function bufferResults( $buffer = null ) {
 257                 if ( is_null( $buffer ) ) {
 258                         return !(bool)( $this->mFlags & DBO_NOBUFFER );
 259                 } else {
 260                         return !wfSetBit( $this->mFlags, DBO_NOBUFFER, !$buffer );
 261                 }
 262         }
 263
 264         /**
 265          * Turns on (false) or off (true) the automatic generation and sending
 266          * of a "we're sorry, but there has been a database error" page on
 267          * database errors. Default is on (false). When turned off, the
 268          * code should use lastErrno() and lastError() to handle the
 269          * situation as appropriate.
 270          */
 271         function ignoreErrors( $ignoreErrors = null ) {
 272                 return wfSetBit( $this->mFlags, DBO_IGNORE, $ignoreErrors );
 273         }
 274
 275         /**
 276          * The current depth of nested transactions
 277          * @param $level Integer: , default NULL.
 278          */
 279         function trxLevel( $level = null ) {
 280                 return wfSetVar( $this->mTrxLevel, $level );
 281         }
 282
 283         /**
 284          * Number of errors logged, only useful when errors are ignored
 285          */
 286         function errorCount( $count = null ) {
 287                 return wfSetVar( $this->mErrorCount, $count );
 288         }
 289
 290         function tablePrefix( $prefix = null ) {
 291                 return wfSetVar( $this->mTablePrefix, $prefix );
 292         }
 293
 294         /**
 295          * Properties passed down from the server info array of the load balancer
 296          */
 297         function getLBInfo( $name = null ) {
 298                 if ( is_null( $name ) ) {
 299                         return $this->mLBInfo;
 300                 } else {
 301                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 302                                 return $this->mLBInfo[$name];
 303                         } else {
 304                                 return null;
 305                         }
 306                 }
 307         }
 308
 309         function setLBInfo( $name, $value = null ) {
 310                 if ( is_null( $value ) ) {
 311                         $this->mLBInfo = $name;
 312                 } else {
 313                         $this->mLBInfo[$name] = $value;
 314                 }
 315         }
 316
 317         /**
 318          * Set lag time in seconds for a fake slave
 319          */
 320         function setFakeSlaveLag( $lag ) {
 321                 $this->mFakeSlaveLag = $lag;
 322         }
 323
 324         /**
 325          * Make this connection a fake master
 326          */
 327         function setFakeMaster( $enabled = true ) {
 328                 $this->mFakeMaster = $enabled;
 329         }
 330
 331         /**
 332          * Returns true if this database supports (and uses) cascading deletes
 333          */
 334         function cascadingDeletes() {
 335                 return false;
 336         }
 337
 338         /**
 339          * Returns true if this database supports (and uses) triggers (e.g. on the page table)
 340          */
 341         function cleanupTriggers() {
 342                 return false;
 343         }
 344
 345         /**
 346          * Returns true if this database is strict about what can be put into an IP field.
 347          * Specifically, it uses a NULL value instead of an empty string.
 348          */
 349         function strictIPs() {
 350                 return false;
 351         }
 352
 353         /**
 354          * Returns true if this database uses timestamps rather than integers
 355         */
 356         function realTimestamps() {
 357                 return false;
 358         }
 359
 360         /**
 361          * Returns true if this database does an implicit sort when doing GROUP BY
 362          */
 363         function implicitGroupby() {
 364                 return true;
 365         }
 366
 367         /**
 368          * Returns true if this database does an implicit order by when the column has an index
 369          * For example: SELECT page_title FROM page LIMIT 1
 370          */
 371         function implicitOrderby() {
 372                 return true;
 373         }
 374
 375         /**
 376          * Returns true if this database requires that SELECT DISTINCT queries require that all
 377            ORDER BY expressions occur in the SELECT list per the SQL92 standard
 378          */
 379         function standardSelectDistinct() {
 380                 return true;
 381         }
 382
 383         /**
 384          * Returns true if this database can do a native search on IP columns
 385          * e.g. this works as expected: .. WHERE rc_ip = '127.42.12.102/32';
 386          */
 387         function searchableIPs() {
 388                 return false;
 389         }
 390
 391         /**
 392          * Returns true if this database can use functional indexes
 393          */
 394         function functionalIndexes() {
 395                 return false;
 396         }
 397
 398         /**
 399          * Return the last query that went through DatabaseBase::query()
 400          * @return String
 401          */
 402         function lastQuery() { return $this->mLastQuery; }
 403
 404
 405         /**
 406          * Returns true if the connection may have been used for write queries.
 407          * Should return true if unsure.
 408          */
 409         function doneWrites() { return $this->mDoneWrites; }
 410
 411         /**
 412          * Is a connection to the database open?
 413          * @return Boolean
 414          */
 415         function isOpen() { return $this->mOpened; }
 416
 417         /**
 418          * Set a flag for this connection
 419          *
 420          * @param $flag Integer: DBO_* constants from Defines.php:
 421          *   - DBO_DEBUG: output some debug info (same as debug())
 422          *   - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
 423          *   - DBO_IGNORE: ignore errors (same as ignoreErrors())
 424          *   - DBO_TRX: automatically start transactions
 425          *   - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
 426          *       and removes it in command line mode
 427          *   - DBO_PERSISTENT: use persistant database connection
 428          */
 429         function setFlag( $flag ) {
 430                 $this->mFlags |= $flag;
 431         }
 432
 433         /**
 434          * Clear a flag for this connection
 435          *
 436          * @param $flag: same as setFlag()'s $flag param
 437          */
 438         function clearFlag( $flag ) {
 439                 $this->mFlags &= ~$flag;
 440         }
 441
 442         /**
 443          * Returns a boolean whether the flag $flag is set for this connection
 444          *
 445          * @param $flag: same as setFlag()'s $flag param
 446          * @return Boolean
 447          */
 448         function getFlag( $flag ) {
 449                 return !!( $this->mFlags & $flag );
 450         }
 451
 452         /**
 453          * General read-only accessor
 454          */
 455         function getProperty( $name ) {
 456                 return $this->$name;
 457         }
 458
 459         function getWikiID() {
 460                 if ( $this->mTablePrefix ) {
 461                         return "{$this->mDBname}-{$this->mTablePrefix}";
 462                 } else {
 463                         return $this->mDBname;
 464                 }
 465         }
 466
 467         /**
 468          * Return a path to the DBMS-specific schema, otherwise default to tables.sql
 469          */
 470         public function getSchema() {
 471                 global $IP;
 472                 if ( file_exists( "$IP/maintenance/" . $this->getType() . "/tables.sql" ) ) {
 473                         return "$IP/maintenance/" . $this->getType() . "/tables.sql";
 474                 } else {
 475                         return "$IP/maintenance/tables.sql";
 476                 }
 477         }
 478
 479 # ------------------------------------------------------------------------------
 480 # Other functions
 481 # ------------------------------------------------------------------------------
 482
 483         /**
 484          * Constructor.
 485          * @param $server String: database server host
 486          * @param $user String: database user name
 487          * @param $password String: database user password
 488          * @param $dbName String: database name
 489          * @param $flags
 490          * @param $tablePrefix String: database table prefixes. By default use the prefix gave in LocalSettings.php
 491          */
 492         function __construct( $server = false, $user = false, $password = false, $dbName = false,
 493                 $flags = 0, $tablePrefix = 'get from global'
 494         ) {
 495                 global $wgOut, $wgDBprefix, $wgCommandLineMode;
 496
 497                 # Can't get a reference if it hasn't been set yet
 498                 if ( !isset( $wgOut ) ) {
 499                         $wgOut = null;
 500                 }
 501                 $this->mFlags = $flags;
 502
 503                 if ( $this->mFlags & DBO_DEFAULT ) {
 504                         if ( $wgCommandLineMode ) {
 505                                 $this->mFlags &= ~DBO_TRX;
 506                         } else {
 507                                 $this->mFlags |= DBO_TRX;
 508                         }
 509                 }
 510
 511                 /*
 512                 // Faster read-only access
 513                 if ( wfReadOnly() ) {
 514                         $this->mFlags |= DBO_PERSISTENT;
 515                         $this->mFlags &= ~DBO_TRX;
 516                 }*/
 517
 518                 /** Get the default table prefix*/
 519                 if ( $tablePrefix == 'get from global' ) {
 520                         $this->mTablePrefix = $wgDBprefix;
 521                 } else {
 522                         $this->mTablePrefix = $tablePrefix;
 523                 }
 524
 525                 if ( $server ) {
 526                         $this->open( $server, $user, $password, $dbName );
 527                 }
 528         }
 529
 530         /**
 531          * Same as new DatabaseMysql( ... ), kept for backward compatibility
 532          * @param $server String: database server host
 533          * @param $user String: database user name
 534          * @param $password String: database user password
 535          * @param $dbName String: database name
 536          * @param $flags
 537          */
 538         static function newFromParams( $server, $user, $password, $dbName, $flags = 0 ) {
 539                 wfDeprecated( __METHOD__ );
 540                 return new DatabaseMysql( $server, $user, $password, $dbName, $flags );
 541         }
 542
 543         protected function installErrorHandler() {
 544                 $this->mPHPError = false;
 545                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 546                 set_error_handler( array( $this, 'connectionErrorHandler' ) );
 547         }
 548
 549         protected function restoreErrorHandler() {
 550                 restore_error_handler();
 551                 if ( $this->htmlErrors !== false ) {
 552                         ini_set( 'html_errors', $this->htmlErrors );
 553                 }
 554                 if ( $this->mPHPError ) {
 555                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 556                         $error = preg_replace( '!^.*?:(.*)$!', '$1', $error );
 557                         return $error;
 558                 } else {
 559                         return false;
 560                 }
 561         }
 562
 563         protected function connectionErrorHandler( $errno,  $errstr ) {
 564                 $this->mPHPError = $errstr;
 565         }
 566
 567         /**
 568          * Closes a database connection.
 569          * if it is open : commits any open transactions
 570          *
 571          * @return Bool operation success. true if already closed.
 572          */
 573         function close() {
 574                 # Stub, should probably be overridden
 575                 return true;
 576         }
 577
 578         /**
 579          * @param $error String: fallback error message, used if none is given by DB
 580          */
 581         function reportConnectionError( $error = 'Unknown error' ) {
 582                 $myError = $this->lastError();
 583                 if ( $myError ) {
 584                         $error = $myError;
 585                 }
 586
 587                 # New method
 588                 throw new DBConnectionError( $this, $error );
 589         }
 590
 591         /**
 592          * Determine whether a query writes to the DB.
 593          * Should return true if unsure.
 594          */
 595         function isWriteQuery( $sql ) {
 596                 return !preg_match( '/^(?:SELECT|BEGIN|COMMIT|SET|SHOW|\(SELECT)\b/i', $sql );
 597         }
 598
 599         /**
 600          * Database specific translations like MySQL's UNIX_TIMESTAMP() to
 601          * something the DB can use.
 602          */
 603         function translateSQLFunctions( $vars ) {
 604                 return $vars;
 605         }
 606
 607         /**
 608          * Usually aborts on failure.  If errors are explicitly ignored, returns success.
 609          *
 610          * @param  $sql        String: SQL query
 611          * @param  $fname      String: Name of the calling function, for profiling/SHOW PROCESSLIST
 612          *     comment (you can use __METHOD__ or add some extra info)
 613          * @param  $tempIgnore Boolean:   Whether to avoid throwing an exception on errors...
 614          *     maybe best to catch the exception instead?
 615          * @return true for a successful write query, ResultWrapper object for a successful read query,
 616          *     or false on failure if $tempIgnore set
 617          * @throws DBQueryError Thrown when the database returns an error of any kind
 618          */
 619         public function query( $sql, $fname = '', $tempIgnore = false ) {
 620                 global $wgProfiler;
 621
 622                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 623                 if ( isset( $wgProfiler ) ) {
 624                         # generalizeSQL will probably cut down the query to reasonable
 625                         # logging size most of the time. The substr is really just a sanity check.
 626
 627                         # Who's been wasting my precious column space? -- TS
 628                         # $profName = 'query: ' . $fname . ' ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 629
 630                         if ( $isMaster ) {
 631                                 $queryProf = 'query-m: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 632                                 $totalProf = 'DatabaseBase::query-master';
 633                         } else {
 634                                 $queryProf = 'query: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 635                                 $totalProf = 'DatabaseBase::query';
 636                         }
 637
 638                         wfProfileIn( $totalProf );
 639                         wfProfileIn( $queryProf );
 640                 }
 641
 642                 $this->mLastQuery = $sql;
 643                 if ( !$this->mDoneWrites && $this->isWriteQuery( $sql ) ) {
 644                         // Set a flag indicating that writes have been done
 645                         wfDebug( __METHOD__ . ": Writes done: $sql\n" );
 646                         $this->mDoneWrites = true;
 647                 }
 648
 649                 # Add a comment for easy SHOW PROCESSLIST interpretation
 650                 # if ( $fname ) {
 651                         global $wgUser;
 652                         if ( is_object( $wgUser ) && $wgUser->mDataLoaded ) {
 653                                 $userName = $wgUser->getName();
 654                                 if ( mb_strlen( $userName ) > 15 ) {
 655                                         $userName = mb_substr( $userName, 0, 15 ) . '...';
 656                                 }
 657                                 $userName = str_replace( '/', '', $userName );
 658                         } else {
 659                                 $userName = '';
 660                         }
 661                         $commentedSql = $this->translateSQLFunctions( preg_replace( '/\s/', " /* $fname $userName */ ", $sql, 1 ) );
 662                 # } else {
 663                 #       $commentedSql = $sql;
 664                 # }
 665
 666                 # If DBO_TRX is set, start a transaction
 667                 if ( ( $this->mFlags & DBO_TRX ) && !$this->trxLevel() &&
 668                         $sql != 'BEGIN' && $sql != 'COMMIT' && $sql != 'ROLLBACK' ) {
 669                         // avoid establishing transactions for SHOW and SET statements too -
 670                         // that would delay transaction initializations to once connection
 671                         // is really used by application
 672                         $sqlstart = substr( $sql, 0, 10 ); // very much worth it, benchmark certified(tm)
 673                         if ( strpos( $sqlstart, "SHOW " ) !== 0 and strpos( $sqlstart, "SET " ) !== 0 )
 674                                 $this->begin();
 675                 }
 676
 677                 if ( $this->debug() ) {
 678                         static $cnt = 0;
 679
 680                         $cnt++;
 681                         $sqlx = substr( $commentedSql, 0, 500 );
 682                         $sqlx = strtr( $sqlx, "\t\n", '  ' );
 683
 684                         if ( $isMaster ) {
 685                                 wfDebug( "Query $cnt (master): $sqlx\n" );
 686                         } else {
 687                                 wfDebug( "Query $cnt (slave): $sqlx\n" );
 688                         }
 689                 }
 690
 691                 if ( istainted( $sql ) & TC_MYSQL ) {
 692                         throw new MWException( 'Tainted query found' );
 693                 }
 694
 695                 # Do the query and handle errors
 696                 $ret = $this->doQuery( $commentedSql );
 697
 698                 # Try reconnecting if the connection was lost
 699                 if ( false === $ret && $this->wasErrorReissuable() ) {
 700                         # Transaction is gone, like it or not
 701                         $this->mTrxLevel = 0;
 702                         wfDebug( "Connection lost, reconnecting...\n" );
 703
 704                         if ( $this->ping() ) {
 705                                 wfDebug( "Reconnected\n" );
 706                                 $sqlx = substr( $commentedSql, 0, 500 );
 707                                 $sqlx = strtr( $sqlx, "\t\n", '  ' );
 708                                 global $wgRequestTime;
 709                                 $elapsed = round( microtime( true ) - $wgRequestTime, 3 );
 710                                 wfLogDBError( "Connection lost and reconnected after {$elapsed}s, query: $sqlx\n" );
 711                                 $ret = $this->doQuery( $commentedSql );
 712                         } else {
 713                                 wfDebug( "Failed\n" );
 714                         }
 715                 }
 716
 717                 if ( false === $ret ) {
 718                         $this->reportQueryError( $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 719                 }
 720
 721                 if ( isset( $wgProfiler ) ) {
 722                         wfProfileOut( $queryProf );
 723                         wfProfileOut( $totalProf );
 724                 }
 725
 726                 return $this->resultObject( $ret );
 727         }
 728
 729         /**
 730          * @param $error String
 731          * @param $errno Integer
 732          * @param $sql String
 733          * @param $fname String
 734          * @param $tempIgnore Boolean
 735          */
 736         function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 737                 # Ignore errors during error handling to avoid infinite recursion
 738                 $ignore = $this->ignoreErrors( true );
 739                 ++$this->mErrorCount;
 740
 741                 if ( $ignore || $tempIgnore ) {
 742                         wfDebug( "SQL ERROR (ignored): $error\n" );
 743                         $this->ignoreErrors( $ignore );
 744                 } else {
 745                         $sql1line = str_replace( "\n", "\\n", $sql );
 746                         wfLogDBError( "$fname\t{$this->mServer}\t$errno\t$error\t$sql1line\n" );
 747                         wfDebug( "SQL ERROR: " . $error . "\n" );
 748                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
 749                 }
 750         }
 751
 752
 753         /**
 754          * Intended to be compatible with the PEAR::DB wrapper functions.
 755          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
 756          *
 757          * ? = scalar value, quoted as necessary
 758          * ! = raw SQL bit (a function for instance)
 759          * & = filename; reads the file and inserts as a blob
 760          *     (we don't use this though...)
 761          */
 762         function prepare( $sql, $func = 'DatabaseBase::prepare' ) {
 763                 /* MySQL doesn't support prepared statements (yet), so just
 764                    pack up the query for reference. We'll manually replace
 765                    the bits later. */
 766                 return array( 'query' => $sql, 'func' => $func );
 767         }
 768
 769         function freePrepared( $prepared ) {
 770                 /* No-op by default */
 771         }
 772
 773         /**
 774          * Execute a prepared query with the various arguments
 775          * @param $prepared String: the prepared sql
 776          * @param $args Mixed: Either an array here, or put scalars as varargs
 777          */
 778         function execute( $prepared, $args = null ) {
 779                 if ( !is_array( $args ) ) {
 780                         # Pull the var args
 781                         $args = func_get_args();
 782                         array_shift( $args );
 783                 }
 784
 785                 $sql = $this->fillPrepared( $prepared['query'], $args );
 786
 787                 return $this->query( $sql, $prepared['func'] );
 788         }
 789
 790         /**
 791          * Prepare & execute an SQL statement, quoting and inserting arguments
 792          * in the appropriate places.
 793          * @param $query String
 794          * @param $args ...
 795          */
 796         function safeQuery( $query, $args = null ) {
 797                 $prepared = $this->prepare( $query, 'DatabaseBase::safeQuery' );
 798
 799                 if ( !is_array( $args ) ) {
 800                         # Pull the var args
 801                         $args = func_get_args();
 802                         array_shift( $args );
 803                 }
 804
 805                 $retval = $this->execute( $prepared, $args );
 806                 $this->freePrepared( $prepared );
 807
 808                 return $retval;
 809         }
 810
 811         /**
 812          * For faking prepared SQL statements on DBs that don't support
 813          * it directly.
 814          * @param $preparedQuery String: a 'preparable' SQL statement
 815          * @param $args Array of arguments to fill it with
 816          * @return string executable SQL
 817          */
 818         function fillPrepared( $preparedQuery, $args ) {
 819                 reset( $args );
 820                 $this->preparedArgs =& $args;
 821
 822                 return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
 823                         array( &$this, 'fillPreparedArg' ), $preparedQuery );
 824         }
 825
 826         /**
 827          * preg_callback func for fillPrepared()
 828          * The arguments should be in $this->preparedArgs and must not be touched
 829          * while we're doing this.
 830          *
 831          * @param $matches Array
 832          * @return String
 833          * @private
 834          */
 835         function fillPreparedArg( $matches ) {
 836                 switch( $matches[1] ) {
 837                         case '\\?': return '?';
 838                         case '\\!': return '!';
 839                         case '\\&': return '&';
 840                 }
 841
 842                 list( /* $n */ , $arg ) = each( $this->preparedArgs );
 843
 844                 switch( $matches[1] ) {
 845                         case '?': return $this->addQuotes( $arg );
 846                         case '!': return $arg;
 847                         case '&':
 848                                 # return $this->addQuotes( file_get_contents( $arg ) );
 849                                 throw new DBUnexpectedError( $this, '& mode is not implemented. If it\'s really needed, uncomment the line above.' );
 850                         default:
 851                                 throw new DBUnexpectedError( $this, 'Received invalid match. This should never happen!' );
 852                 }
 853         }
 854
 855         /**
 856          * Free a result object
 857          * @param $res Mixed: A SQL result
 858          */
 859         function freeResult( $res ) {
 860                 # Stub.  Might not really need to be overridden, since results should
 861                 # be freed by PHP when the variable goes out of scope anyway.
 862         }
 863
 864         /**
 865          * Simple UPDATE wrapper
 866          * Usually aborts on failure
 867          * If errors are explicitly ignored, returns success
 868          *
 869          * This function exists for historical reasons, DatabaseBase::update() has a more standard
 870          * calling convention and feature set
 871          */
 872         function set( $table, $var, $value, $cond, $fname = 'DatabaseBase::set' ) {
 873                 $table = $this->tableName( $table );
 874                 $sql = "UPDATE $table SET $var = '" .
 875                   $this->strencode( $value ) . "' WHERE ($cond)";
 876
 877                 return (bool)$this->query( $sql, $fname );
 878         }
 879
 880         /**
 881          * Simple SELECT wrapper, returns a single field, input must be encoded
 882          * Usually aborts on failure
 883          * If errors are explicitly ignored, returns FALSE on failure
 884          */
 885         function selectField( $table, $var, $cond = '', $fname = 'DatabaseBase::selectField', $options = array() ) {
 886                 if ( !is_array( $options ) ) {
 887                         $options = array( $options );
 888                 }
 889
 890                 $options['LIMIT'] = 1;
 891
 892                 $res = $this->select( $table, $var, $cond, $fname, $options );
 893
 894                 if ( $res === false || !$this->numRows( $res ) ) {
 895                         return false;
 896                 }
 897
 898                 $row = $this->fetchRow( $res );
 899
 900                 if ( $row !== false ) {
 901                         return reset( $row );
 902                 } else {
 903                         return false;
 904                 }
 905         }
 906
 907         /**
 908          * Returns an optional USE INDEX clause to go after the table, and a
 909          * string to go at the end of the query
 910          *
 911          * @private
 912          *
 913          * @param $options Array: associative array of options to be turned into
 914          *              an SQL query, valid keys are listed in the function.
 915          * @return Array
 916          */
 917         function makeSelectOptions( $options ) {
 918                 $preLimitTail = $postLimitTail = '';
 919                 $startOpts = '';
 920
 921                 $noKeyOptions = array();
 922
 923                 foreach ( $options as $key => $option ) {
 924                         if ( is_numeric( $key ) ) {
 925                                 $noKeyOptions[$option] = true;
 926                         }
 927                 }
 928
 929                 if ( isset( $options['GROUP BY'] ) ) {
 930                         $preLimitTail .= " GROUP BY {$options['GROUP BY']}";
 931                 }
 932
 933                 if ( isset( $options['HAVING'] ) ) {
 934                         $preLimitTail .= " HAVING {$options['HAVING']}";
 935                 }
 936
 937                 if ( isset( $options['ORDER BY'] ) ) {
 938                         $preLimitTail .= " ORDER BY {$options['ORDER BY']}";
 939                 }
 940
 941                 // if (isset($options['LIMIT'])) {
 942                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
 943                 //              isset($options['OFFSET']) ? $options['OFFSET']
 944                 //              : false);
 945                 // }
 946
 947                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
 948                         $postLimitTail .= ' FOR UPDATE';
 949                 }
 950
 951                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
 952                         $postLimitTail .= ' LOCK IN SHARE MODE';
 953                 }
 954
 955                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
 956                         $startOpts .= 'DISTINCT';
 957                 }
 958
 959                 # Various MySQL extensions
 960                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
 961                         $startOpts .= ' /*! STRAIGHT_JOIN */';
 962                 }
 963
 964                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
 965                         $startOpts .= ' HIGH_PRIORITY';
 966                 }
 967
 968                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
 969                         $startOpts .= ' SQL_BIG_RESULT';
 970                 }
 971
 972                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
 973                         $startOpts .= ' SQL_BUFFER_RESULT';
 974                 }
 975
 976                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
 977                         $startOpts .= ' SQL_SMALL_RESULT';
 978                 }
 979
 980                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
 981                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
 982                 }
 983
 984                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
 985                         $startOpts .= ' SQL_CACHE';
 986                 }
 987
 988                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
 989                         $startOpts .= ' SQL_NO_CACHE';
 990                 }
 991
 992                 if ( isset( $options['USE INDEX'] ) && ! is_array( $options['USE INDEX'] ) ) {
 993                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
 994                 } else {
 995                         $useIndex = '';
 996                 }
 997
 998                 return array( $startOpts, $useIndex, $preLimitTail, $postLimitTail );
 999         }
1000
1001         /**
1002          * SELECT wrapper
1003          *
1004          * @param $table   Mixed:  Array or string, table name(s) (prefix auto-added)
1005          * @param $vars    Mixed:  Array or string, field name(s) to be retrieved
1006          * @param $conds   Mixed:  Array or string, condition(s) for WHERE
1007          * @param $fname   String: Calling function name (use __METHOD__) for logs/profiling
1008          * @param $options Array:  Associative array of options (e.g. array('GROUP BY' => 'page_title')),
1009          *                         see DatabaseBase::makeSelectOptions code for list of supported stuff
1010          * @param $join_conds Array: Associative array of table join conditions (optional)
1011          *                           (e.g. array( 'page' => array('LEFT JOIN','page_latest=rev_id') )
1012          * @return mixed Database result resource (feed to DatabaseBase::fetchObject or whatever), or false on failure
1013          */
1014         function select( $table, $vars, $conds = '', $fname = 'DatabaseBase::select', $options = array(), $join_conds = array() ) {
1015                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1016
1017                 return $this->query( $sql, $fname );
1018         }
1019
1020         /**
1021          * SELECT wrapper
1022          *
1023          * @param $table   Mixed:  Array or string, table name(s) (prefix auto-added)
1024          * @param $vars    Mixed:  Array or string, field name(s) to be retrieved
1025          * @param $conds   Mixed:  Array or string, condition(s) for WHERE
1026          * @param $fname   String: Calling function name (use __METHOD__) for logs/profiling
1027          * @param $options Array:  Associative array of options (e.g. array('GROUP BY' => 'page_title')),
1028          *                         see DatabaseBase::makeSelectOptions code for list of supported stuff
1029          * @param $join_conds Array: Associative array of table join conditions (optional)
1030          *                           (e.g. array( 'page' => array('LEFT JOIN','page_latest=rev_id') )
1031          * @return string, the SQL text
1032          */
1033         function selectSQLText( $table, $vars, $conds = '', $fname = 'DatabaseBase::select', $options = array(), $join_conds = array() ) {
1034                 if ( is_array( $vars ) ) {
1035                         $vars = implode( ',', $vars );
1036                 }
1037
1038                 if ( !is_array( $options ) ) {
1039                         $options = array( $options );
1040                 }
1041
1042                 if ( is_array( $table ) ) {
1043                         if ( !empty( $join_conds ) || ( isset( $options['USE INDEX'] ) && is_array( @$options['USE INDEX'] ) ) ) {
1044                                 $from = ' FROM ' . $this->tableNamesWithUseIndexOrJOIN( $table, @$options['USE INDEX'], $join_conds );
1045                         } else {
1046                                 $from = ' FROM ' . implode( ',', array_map( array( &$this, 'tableName' ), $table ) );
1047                         }
1048                 } elseif ( $table != '' ) {
1049                         if ( $table { 0 } == ' ' ) {
1050                                 $from = ' FROM ' . $table;
1051                         } else {
1052                                 $from = ' FROM ' . $this->tableName( $table );
1053                         }
1054                 } else {
1055                         $from = '';
1056                 }
1057
1058                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail ) = $this->makeSelectOptions( $options );
1059
1060                 if ( !empty( $conds ) ) {
1061                         if ( is_array( $conds ) ) {
1062                                 $conds = $this->makeList( $conds, LIST_AND );
1063                         }
1064                         $sql = "SELECT $startOpts $vars $from $useIndex WHERE $conds $preLimitTail";
1065                 } else {
1066                         $sql = "SELECT $startOpts $vars $from $useIndex $preLimitTail";
1067                 }
1068
1069                 if ( isset( $options['LIMIT'] ) )
1070                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1071                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1072                 $sql = "$sql $postLimitTail";
1073
1074                 if ( isset( $options['EXPLAIN'] ) ) {
1075                         $sql = 'EXPLAIN ' . $sql;
1076                 }
1077
1078                 return $sql;
1079         }
1080
1081         /**
1082          * Single row SELECT wrapper
1083          * Aborts or returns FALSE on error
1084          *
1085          * @param $table String: table name
1086          * @param $vars String: the selected variables
1087          * @param $conds Array: a condition map, terms are ANDed together.
1088          *   Items with numeric keys are taken to be literal conditions
1089          * Takes an array of selected variables, and a condition map, which is ANDed
1090          * e.g: selectRow( "page", array( "page_id" ), array( "page_namespace" =>
1091          * NS_MAIN, "page_title" => "Astronomy" ) )   would return an object where
1092          * $obj- >page_id is the ID of the Astronomy article
1093          * @param $fname String: Calling function name
1094          * @param $options Array
1095          * @param $join_conds Array
1096          *
1097          * @todo migrate documentation to phpdocumentor format
1098          */
1099         function selectRow( $table, $vars, $conds, $fname = 'DatabaseBase::selectRow', $options = array(), $join_conds = array() ) {
1100                 $options['LIMIT'] = 1;
1101                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1102
1103                 if ( $res === false ) {
1104                         return false;
1105                 }
1106
1107                 if ( !$this->numRows( $res ) ) {
1108                         return false;
1109                 }
1110
1111                 $obj = $this->fetchObject( $res );
1112
1113                 return $obj;
1114         }
1115
1116         /**
1117          * Estimate rows in dataset
1118          * Returns estimated count - not necessarily an accurate estimate across different databases,
1119          * so use sparingly
1120          * Takes same arguments as DatabaseBase::select()
1121          *
1122          * @param $table String: table name
1123          * @param $vars Array: unused
1124          * @param $conds Array: filters on the table
1125          * @param $fname String: function name for profiling
1126          * @param $options Array: options for select
1127          * @return Integer: row count
1128          */
1129         public function estimateRowCount( $table, $vars = '*', $conds = '', $fname = 'DatabaseBase::estimateRowCount', $options = array() ) {
1130                 $rows = 0;
1131                 $res = $this->select ( $table, 'COUNT(*) AS rowcount', $conds, $fname, $options );
1132
1133                 if ( $res ) {
1134                         $row = $this->fetchRow( $res );
1135                         $rows = ( isset( $row['rowcount'] ) ) ? $row['rowcount'] : 0;
1136                 }
1137
1138                 return $rows;
1139         }
1140
1141         /**
1142          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1143          * It's only slightly flawed. Don't use for anything important.
1144          *
1145          * @param $sql String: A SQL Query
1146          */
1147         static function generalizeSQL( $sql ) {
1148                 # This does the same as the regexp below would do, but in such a way
1149                 # as to avoid crashing php on some large strings.
1150                 # $sql = preg_replace ( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql);
1151
1152                 $sql = str_replace ( "\\\\", '', $sql );
1153                 $sql = str_replace ( "\\'", '', $sql );
1154                 $sql = str_replace ( "\\\"", '', $sql );
1155                 $sql = preg_replace ( "/'.*'/s", "'X'", $sql );
1156                 $sql = preg_replace ( '/".*"/s', "'X'", $sql );
1157
1158                 # All newlines, tabs, etc replaced by single space
1159                 $sql = preg_replace ( '/\s+/', ' ', $sql );
1160
1161                 # All numbers => N
1162                 $sql = preg_replace ( '/-?[0-9]+/s', 'N', $sql );
1163
1164                 return $sql;
1165         }
1166
1167         /**
1168          * Determines whether a field exists in a table
1169          *
1170          * @param $table String: table name
1171          * @param $field String: filed to check on that table
1172          * @param $fname String: calling function name (optional)
1173          * @return Boolean: whether $table has filed $field
1174          */
1175         function fieldExists( $table, $field, $fname = 'DatabaseBase::fieldExists' ) {
1176                 $info = $this->fieldInfo( $table, $field );
1177
1178                 return (bool)$info;
1179         }
1180
1181         /**
1182          * Determines whether an index exists
1183          * Usually aborts on failure
1184          * If errors are explicitly ignored, returns NULL on failure
1185          */
1186         function indexExists( $table, $index, $fname = 'DatabaseBase::indexExists' ) {
1187                 $info = $this->indexInfo( $table, $index, $fname );
1188                 if ( is_null( $info ) ) {
1189                         return null;
1190                 } else {
1191                         return $info !== false;
1192                 }
1193         }
1194
1195         /**
1196          * Query whether a given table exists
1197          */
1198         function tableExists( $table ) {
1199                 $table = $this->tableName( $table );
1200                 $old = $this->ignoreErrors( true );
1201                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", __METHOD__ );
1202                 $this->ignoreErrors( $old );
1203
1204                 return (bool)$res;
1205         }
1206
1207         /**
1208          * mysql_field_type() wrapper
1209          */
1210         function fieldType( $res, $index ) {
1211                 if ( $res instanceof ResultWrapper ) {
1212                         $res = $res->result;
1213                 }
1214
1215                 return mysql_field_type( $res, $index );
1216         }
1217
1218         /**
1219          * Determines if a given index is unique
1220          */
1221         function indexUnique( $table, $index ) {
1222                 $indexInfo = $this->indexInfo( $table, $index );
1223
1224                 if ( !$indexInfo ) {
1225                         return null;
1226                 }
1227
1228                 return !$indexInfo[0]->Non_unique;
1229         }
1230
1231         /**
1232          * INSERT wrapper, inserts an array into a table
1233          *
1234          * $a may be a single associative array, or an array of these with numeric keys, for
1235          * multi-row insert.
1236          *
1237          * Usually aborts on failure
1238          * If errors are explicitly ignored, returns success
1239          *
1240          * @param $table   String: table name (prefix auto-added)
1241          * @param $a       Array: Array of rows to insert
1242          * @param $fname   String: Calling function name (use __METHOD__) for logs/profiling
1243          * @param $options Mixed: Associative array of options
1244          *
1245          * @return bool
1246          */
1247         function insert( $table, $a, $fname = 'DatabaseBase::insert', $options = array() ) {
1248                 # No rows to insert, easy just return now
1249                 if ( !count( $a ) ) {
1250                         return true;
1251                 }
1252
1253                 $table = $this->tableName( $table );
1254
1255                 if ( !is_array( $options ) ) {
1256                         $options = array( $options );
1257                 }
1258
1259                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1260                         $multi = true;
1261                         $keys = array_keys( $a[0] );
1262                 } else {
1263                         $multi = false;
1264                         $keys = array_keys( $a );
1265                 }
1266
1267                 $sql = 'INSERT ' . implode( ' ', $options ) .
1268                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1269
1270                 if ( $multi ) {
1271                         $first = true;
1272                         foreach ( $a as $row ) {
1273                                 if ( $first ) {
1274                                         $first = false;
1275                                 } else {
1276                                         $sql .= ',';
1277                                 }
1278                                 $sql .= '(' . $this->makeList( $row ) . ')';
1279                         }
1280                 } else {
1281                         $sql .= '(' . $this->makeList( $a ) . ')';
1282                 }
1283
1284                 return (bool)$this->query( $sql, $fname );
1285         }
1286
1287         /**
1288          * Make UPDATE options for the DatabaseBase::update function
1289          *
1290          * @private
1291          * @param $options Array: The options passed to DatabaseBase::update
1292          * @return string
1293          */
1294         function makeUpdateOptions( $options ) {
1295                 if ( !is_array( $options ) ) {
1296                         $options = array( $options );
1297                 }
1298
1299                 $opts = array();
1300
1301                 if ( in_array( 'LOW_PRIORITY', $options ) ) {
1302                         $opts[] = $this->lowPriorityOption();
1303                 }
1304
1305                 if ( in_array( 'IGNORE', $options ) ) {
1306                         $opts[] = 'IGNORE';
1307                 }
1308
1309                 return implode( ' ', $opts );
1310         }
1311
1312         /**
1313          * UPDATE wrapper, takes a condition array and a SET array
1314          *
1315          * @param $table  String: The table to UPDATE
1316          * @param $values Array:  An array of values to SET
1317          * @param $conds  Array:  An array of conditions (WHERE). Use '*' to update all rows.
1318          * @param $fname  String: The Class::Function calling this function
1319          *                        (for the log)
1320          * @param $options Array: An array of UPDATE options, can be one or
1321          *                        more of IGNORE, LOW_PRIORITY
1322          * @return Boolean
1323          */
1324         function update( $table, $values, $conds, $fname = 'DatabaseBase::update', $options = array() ) {
1325                 $table = $this->tableName( $table );
1326                 $opts = $this->makeUpdateOptions( $options );
1327                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1328
1329                 if ( $conds != '*' ) {
1330                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1331                 }
1332
1333                 return $this->query( $sql, $fname );
1334         }
1335
1336         /**
1337          * Makes an encoded list of strings from an array
1338          * $mode:
1339          *        LIST_COMMA         - comma separated, no field names
1340          *        LIST_AND           - ANDed WHERE clause (without the WHERE)
1341          *        LIST_OR            - ORed WHERE clause (without the WHERE)
1342          *        LIST_SET           - comma separated with field names, like a SET clause
1343          *        LIST_NAMES         - comma separated field names
1344          */
1345         function makeList( $a, $mode = LIST_COMMA ) {
1346                 if ( !is_array( $a ) ) {
1347                         throw new DBUnexpectedError( $this, 'DatabaseBase::makeList called with incorrect parameters' );
1348                 }
1349
1350                 $first = true;
1351                 $list = '';
1352
1353                 foreach ( $a as $field => $value ) {
1354                         if ( !$first ) {
1355                                 if ( $mode == LIST_AND ) {
1356                                         $list .= ' AND ';
1357                                 } elseif ( $mode == LIST_OR ) {
1358                                         $list .= ' OR ';
1359                                 } else {
1360                                         $list .= ',';
1361                                 }
1362                         } else {
1363                                 $first = false;
1364                         }
1365
1366                         if ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_numeric( $field ) ) {
1367                                 $list .= "($value)";
1368                         } elseif ( ( $mode == LIST_SET ) && is_numeric( $field ) ) {
1369                                 $list .= "$value";
1370                         } elseif ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_array( $value ) ) {
1371                                 if ( count( $value ) == 0 ) {
1372                                         throw new MWException( __METHOD__ . ': empty input' );
1373                                 } elseif ( count( $value ) == 1 ) {
1374                                         // Special-case single values, as IN isn't terribly efficient
1375                                         // Don't necessarily assume the single key is 0; we don't
1376                                         // enforce linear numeric ordering on other arrays here.
1377                                         $value = array_values( $value );
1378                                         $list .= $field . " = " . $this->addQuotes( $value[0] );
1379                                 } else {
1380                                         $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1381                                 }
1382                         } elseif ( $value === null ) {
1383                                 if ( $mode == LIST_AND || $mode == LIST_OR ) {
1384                                         $list .= "$field IS ";
1385                                 } elseif ( $mode == LIST_SET ) {
1386                                         $list .= "$field = ";
1387                                 }
1388                                 $list .= 'NULL';
1389                         } else {
1390                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
1391                                         $list .= "$field = ";
1392                                 }
1393                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
1394                         }
1395                 }
1396
1397                 return $list;
1398         }
1399
1400         /**
1401          * Build a partial where clause from a 2-d array such as used for LinkBatch.
1402          * The keys on each level may be either integers or strings.
1403          *
1404          * @param $data Array: organized as 2-d array(baseKeyVal => array(subKeyVal => <ignored>, ...), ...)
1405          * @param $baseKey String: field name to match the base-level keys to (eg 'pl_namespace')
1406          * @param $subKey String: field name to match the sub-level keys to (eg 'pl_title')
1407          * @return Mixed: string SQL fragment, or false if no items in array.
1408          */
1409         function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1410                 $conds = array();
1411
1412                 foreach ( $data as $base => $sub ) {
1413                         if ( count( $sub ) ) {
1414                                 $conds[] = $this->makeList(
1415                                         array( $baseKey => $base, $subKey => array_keys( $sub ) ),
1416                                         LIST_AND );
1417                         }
1418                 }
1419
1420                 if ( $conds ) {
1421                         return $this->makeList( $conds, LIST_OR );
1422                 } else {
1423                         // Nothing to search for...
1424                         return false;
1425                 }
1426         }
1427
1428         /**
1429          * Bitwise operations
1430          */
1431
1432         function bitNot( $field ) {
1433                 return "(~$field)";
1434         }
1435
1436         function bitAnd( $fieldLeft, $fieldRight ) {
1437                 return "($fieldLeft & $fieldRight)";
1438         }
1439
1440         function bitOr( $fieldLeft, $fieldRight ) {
1441                 return "($fieldLeft | $fieldRight)";
1442         }
1443
1444         /**
1445          * Change the current database
1446          *
1447          * @todo Explain what exactly will fail if this is not overridden.
1448          * @return bool Success or failure
1449          */
1450         function selectDB( $db ) {
1451                 # Stub.  Shouldn't cause serious problems if it's not overridden, but
1452                 # if your database engine supports a concept similar to MySQL's
1453                 # databases you may as well.
1454                 return true;
1455         }
1456
1457         /**
1458          * Get the current DB name
1459          */
1460         function getDBname() {
1461                 return $this->mDBname;
1462         }
1463
1464         /**
1465          * Get the server hostname or IP address
1466          */
1467         function getServer() {
1468                 return $this->mServer;
1469         }
1470
1471         /**
1472          * Format a table name ready for use in constructing an SQL query
1473          *
1474          * This does two important things: it quotes the table names to clean them up,
1475          * and it adds a table prefix if only given a table name with no quotes.
1476          *
1477          * All functions of this object which require a table name call this function
1478          * themselves. Pass the canonical name to such functions. This is only needed
1479          * when calling query() directly.
1480          *
1481          * @param $name String: database table name
1482          * @return String: full database name
1483          */
1484         function tableName( $name ) {
1485                 global $wgSharedDB, $wgSharedPrefix, $wgSharedTables;
1486                 # Skip the entire process when we have a string quoted on both ends.
1487                 # Note that we check the end so that we will still quote any use of
1488                 # use of `database`.table. But won't break things if someone wants
1489                 # to query a database table with a dot in the name.
1490                 if ( $name[0] == '`' && substr( $name, -1, 1 ) == '`' ) {
1491                         return $name;
1492                 }
1493
1494                 # Lets test for any bits of text that should never show up in a table
1495                 # name. Basically anything like JOIN or ON which are actually part of
1496                 # SQL queries, but may end up inside of the table value to combine
1497                 # sql. Such as how the API is doing.
1498                 # Note that we use a whitespace test rather than a \b test to avoid
1499                 # any remote case where a word like on may be inside of a table name
1500                 # surrounded by symbols which may be considered word breaks.
1501                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1502                         return $name;
1503                 }
1504
1505                 # Split database and table into proper variables.
1506                 # We reverse the explode so that database.table and table both output
1507                 # the correct table.
1508                 $dbDetails = array_reverse( explode( '.', $name, 2 ) );
1509                 if ( isset( $dbDetails[1] ) ) {
1510                         @list( $table, $database ) = $dbDetails;
1511                 } else {
1512                         @list( $table ) = $dbDetails;
1513                 }
1514                 $prefix = $this->mTablePrefix; # Default prefix
1515
1516                 # A database name has been specified in input. Quote the table name
1517                 # because we don't want any prefixes added.
1518                 if ( isset( $database ) ) {
1519                         $table = ( $table[0] == '`' ? $table : "`{$table}`" );
1520                 }
1521
1522                 # Note that we use the long format because php will complain in in_array if
1523                 # the input is not an array, and will complain in is_array if it is not set.
1524                 if ( !isset( $database ) # Don't use shared database if pre selected.
1525                  && isset( $wgSharedDB ) # We have a shared database
1526                  && $table[0] != '`' # Paranoia check to prevent shared tables listing '`table`'
1527                  && isset( $wgSharedTables )
1528                  && is_array( $wgSharedTables )
1529                  && in_array( $table, $wgSharedTables ) ) { # A shared table is selected
1530                         $database = $wgSharedDB;
1531                         $prefix   = isset( $wgSharedPrefix ) ? $wgSharedPrefix : $prefix;
1532                 }
1533
1534                 # Quote the $database and $table and apply the prefix if not quoted.
1535                 if ( isset( $database ) ) {
1536                         $database = ( $database[0] == '`' ? $database : "`{$database}`" );
1537                 }
1538                 $table = ( $table[0] == '`' ? $table : "`{$prefix}{$table}`" );
1539
1540                 # Merge our database and table into our final table name.
1541                 $tableName = ( isset( $database ) ? "{$database}.{$table}" : "{$table}" );
1542
1543                 return $tableName;
1544         }
1545
1546         /**
1547          * Fetch a number of table names into an array
1548          * This is handy when you need to construct SQL for joins
1549          *
1550          * Example:
1551          * extract($dbr->tableNames('user','watchlist'));
1552          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1553          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1554          */
1555         public function tableNames() {
1556                 $inArray = func_get_args();
1557                 $retVal = array();
1558
1559                 foreach ( $inArray as $name ) {
1560                         $retVal[$name] = $this->tableName( $name );
1561                 }
1562
1563                 return $retVal;
1564         }
1565
1566         /**
1567          * Fetch a number of table names into an zero-indexed numerical array
1568          * This is handy when you need to construct SQL for joins
1569          *
1570          * Example:
1571          * list( $user, $watchlist ) = $dbr->tableNamesN('user','watchlist');
1572          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1573          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1574          */
1575         public function tableNamesN() {
1576                 $inArray = func_get_args();
1577                 $retVal = array();
1578
1579                 foreach ( $inArray as $name ) {
1580                         $retVal[] = $this->tableName( $name );
1581                 }
1582
1583                 return $retVal;
1584         }
1585
1586         /**
1587          * @private
1588          */
1589         function tableNamesWithUseIndexOrJOIN( $tables, $use_index = array(), $join_conds = array() ) {
1590                 $ret = array();
1591                 $retJOIN = array();
1592                 $use_index_safe = is_array( $use_index ) ? $use_index : array();
1593                 $join_conds_safe = is_array( $join_conds ) ? $join_conds : array();
1594
1595                 foreach ( $tables as $table ) {
1596                         // Is there a JOIN and INDEX clause for this table?
1597                         if ( isset( $join_conds_safe[$table] ) && isset( $use_index_safe[$table] ) ) {
1598                                 $tableClause = $join_conds_safe[$table][0] . ' ' . $this->tableName( $table );
1599                                 $tableClause .= ' ' . $this->useIndexClause( implode( ',', (array)$use_index_safe[$table] ) );
1600                                 $on = $this->makeList( (array)$join_conds_safe[$table][1], LIST_AND );
1601
1602                                 if ( $on != '' ) {
1603                                         $tableClause .= ' ON (' . $on . ')';
1604                                 }
1605
1606                                 $retJOIN[] = $tableClause;
1607                         // Is there an INDEX clause?
1608                         } else if ( isset( $use_index_safe[$table] ) ) {
1609                                 $tableClause = $this->tableName( $table );
1610                                 $tableClause .= ' ' . $this->useIndexClause( implode( ',', (array)$use_index_safe[$table] ) );
1611                                 $ret[] = $tableClause;
1612                         // Is there a JOIN clause?
1613                         } else if ( isset( $join_conds_safe[$table] ) ) {
1614                                 $tableClause = $join_conds_safe[$table][0] . ' ' . $this->tableName( $table );
1615                                 $on = $this->makeList( (array)$join_conds_safe[$table][1], LIST_AND );
1616
1617                                 if ( $on != '' ) {
1618                                         $tableClause .= ' ON (' . $on . ')';
1619                                 }
1620
1621                                 $retJOIN[] = $tableClause;
1622                         } else {
1623                                 $tableClause = $this->tableName( $table );
1624                                 $ret[] = $tableClause;
1625                         }
1626                 }
1627
1628                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
1629                 $straightJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
1630                 $otherJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
1631
1632                 // Compile our final table clause
1633                 return implode( ' ', array( $straightJoins, $otherJoins ) );
1634         }
1635
1636         /**
1637          * Get the name of an index in a given table
1638          */
1639         function indexName( $index ) {
1640                 // Backwards-compatibility hack
1641                 $renamed = array(
1642                         'ar_usertext_timestamp' => 'usertext_timestamp',
1643                         'un_user_id'            => 'user_id',
1644                         'un_user_ip'            => 'user_ip',
1645                 );
1646
1647                 if ( isset( $renamed[$index] ) ) {
1648                         return $renamed[$index];
1649                 } else {
1650                         return $index;
1651                 }
1652         }
1653
1654         /**
1655          * If it's a string, adds quotes and backslashes
1656          * Otherwise returns as-is
1657          */
1658         function addQuotes( $s ) {
1659                 if ( $s === null ) {
1660                         return 'NULL';
1661                 } else {
1662                         # This will also quote numeric values. This should be harmless,
1663                         # and protects against weird problems that occur when they really
1664                         # _are_ strings such as article titles and string->number->string
1665                         # conversion is not 1:1.
1666                         return "'" . $this->strencode( $s ) . "'";
1667                 }
1668         }
1669
1670         /**
1671          * Escape string for safe LIKE usage.
1672          * WARNING: you should almost never use this function directly,
1673          * instead use buildLike() that escapes everything automatically
1674          * Deprecated in 1.17, warnings in 1.17, removed in ???
1675          */
1676         public function escapeLike( $s ) {
1677                 wfDeprecated( __METHOD__ );
1678                 return $this->escapeLikeInternal( $s );
1679         }
1680
1681         protected function escapeLikeInternal( $s ) {
1682                 $s = str_replace( '\\', '\\\\', $s );
1683                 $s = $this->strencode( $s );
1684                 $s = str_replace( array( '%', '_' ), array( '\%', '\_' ), $s );
1685
1686                 return $s;
1687         }
1688
1689         /**
1690          * LIKE statement wrapper, receives a variable-length argument list with parts of pattern to match
1691          * containing either string literals that will be escaped or tokens returned by anyChar() or anyString().
1692          * Alternatively, the function could be provided with an array of aforementioned parameters.
1693          *
1694          * Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns a LIKE clause that searches
1695          * for subpages of 'My page title'.
1696          * Alternatively: $pattern = array( 'My_page_title/', $dbr->anyString() ); $query .= $dbr->buildLike( $pattern );
1697          *
1698          * @since 1.16
1699          * @return String: fully built LIKE statement
1700          */
1701         function buildLike() {
1702                 $params = func_get_args();
1703
1704                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
1705                         $params = $params[0];
1706                 }
1707
1708                 $s = '';
1709
1710                 foreach ( $params as $value ) {
1711                         if ( $value instanceof LikeMatch ) {
1712                                 $s .= $value->toString();
1713                         } else {
1714                                 $s .= $this->escapeLikeInternal( $value );
1715                         }
1716                 }
1717
1718                 return " LIKE '" . $s . "' ";
1719         }
1720
1721         /**
1722          * Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
1723          */
1724         function anyChar() {
1725                 return new LikeMatch( '_' );
1726         }
1727
1728         /**
1729          * Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
1730          */
1731         function anyString() {
1732                 return new LikeMatch( '%' );
1733         }
1734
1735         /**
1736          * Returns an appropriately quoted sequence value for inserting a new row.
1737          * MySQL has autoincrement fields, so this is just NULL. But the PostgreSQL
1738          * subclass will return an integer, and save the value for insertId()
1739          */
1740         function nextSequenceValue( $seqName ) {
1741                 return null;
1742         }
1743
1744         /**
1745          * USE INDEX clause.  Unlikely to be useful for anything but MySQL.  This
1746          * is only needed because a) MySQL must be as efficient as possible due to
1747          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
1748          * which index to pick.  Anyway, other databases might have different
1749          * indexes on a given table.  So don't bother overriding this unless you're
1750          * MySQL.
1751          */
1752         function useIndexClause( $index ) {
1753                 return '';
1754         }
1755
1756         /**
1757          * REPLACE query wrapper
1758          * PostgreSQL simulates this with a DELETE followed by INSERT
1759          * $row is the row to insert, an associative array
1760          * $uniqueIndexes is an array of indexes. Each element may be either a
1761          * field name or an array of field names
1762          *
1763          * It may be more efficient to leave off unique indexes which are unlikely to collide.
1764          * However if you do this, you run the risk of encountering errors which wouldn't have
1765          * occurred in MySQL
1766          *
1767          * @param $table String: The table to replace the row(s) in.
1768          * @param $uniqueIndexes Array: An associative array of indexes
1769          * @param $rows Array: Array of rows to replace
1770          * @param $fname String: Calling function name (use __METHOD__) for logs/profiling
1771          */
1772         function replace( $table, $uniqueIndexes, $rows, $fname = 'DatabaseBase::replace' ) {
1773                 $table = $this->tableName( $table );
1774
1775                 # Single row case
1776                 if ( !is_array( reset( $rows ) ) ) {
1777                         $rows = array( $rows );
1778                 }
1779
1780                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
1781                 $first = true;
1782
1783                 foreach ( $rows as $row ) {
1784                         if ( $first ) {
1785                                 $first = false;
1786                         } else {
1787                                 $sql .= ',';
1788                         }
1789
1790                         $sql .= '(' . $this->makeList( $row ) . ')';
1791                 }
1792
1793                 return $this->query( $sql, $fname );
1794         }
1795
1796         /**
1797          * DELETE where the condition is a join
1798          * MySQL does this with a multi-table DELETE syntax, PostgreSQL does it with sub-selects
1799          *
1800          * For safety, an empty $conds will not delete everything. If you want to delete all rows where the
1801          * join condition matches, set $conds='*'
1802          *
1803          * DO NOT put the join condition in $conds
1804          *
1805          * @param $delTable String: The table to delete from.
1806          * @param $joinTable String: The other table.
1807          * @param $delVar String: The variable to join on, in the first table.
1808          * @param $joinVar String: The variable to join on, in the second table.
1809          * @param $conds Array: Condition array of field names mapped to variables, ANDed together in the WHERE clause
1810          * @param $fname String: Calling function name (use __METHOD__) for logs/profiling
1811          */
1812         function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds, $fname = 'DatabaseBase::deleteJoin' ) {
1813                 if ( !$conds ) {
1814                         throw new DBUnexpectedError( $this, 'DatabaseBase::deleteJoin() called with empty $conds' );
1815                 }
1816
1817                 $delTable = $this->tableName( $delTable );
1818                 $joinTable = $this->tableName( $joinTable );
1819                 $sql = "DELETE $delTable FROM $delTable, $joinTable WHERE $delVar=$joinVar ";
1820
1821                 if ( $conds != '*' ) {
1822                         $sql .= ' AND ' . $this->makeList( $conds, LIST_AND );
1823                 }
1824
1825                 return $this->query( $sql, $fname );
1826         }
1827
1828         /**
1829          * Returns the size of a text field, or -1 for "unlimited"
1830          */
1831         function textFieldSize( $table, $field ) {
1832                 $table = $this->tableName( $table );
1833                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
1834                 $res = $this->query( $sql, 'DatabaseBase::textFieldSize' );
1835                 $row = $this->fetchObject( $res );
1836
1837                 $m = array();
1838
1839                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
1840                         $size = $m[1];
1841                 } else {
1842                         $size = -1;
1843                 }
1844
1845                 return $size;
1846         }
1847
1848         /**
1849          * A string to insert into queries to show that they're low-priority, like
1850          * MySQL's LOW_PRIORITY.  If no such feature exists, return an empty
1851          * string and nothing bad should happen.
1852          *
1853          * @return string Returns the text of the low priority option if it is supported, or a blank string otherwise
1854          */
1855         function lowPriorityOption() {
1856                 return '';
1857         }
1858
1859         /**
1860          * DELETE query wrapper
1861          *
1862          * Use $conds == "*" to delete all rows
1863          */
1864         function delete( $table, $conds, $fname = 'DatabaseBase::delete' ) {
1865                 if ( !$conds ) {
1866                         throw new DBUnexpectedError( $this, 'DatabaseBase::delete() called with no conditions' );
1867                 }
1868
1869                 $table = $this->tableName( $table );
1870                 $sql = "DELETE FROM $table";
1871
1872                 if ( $conds != '*' ) {
1873                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1874                 }
1875
1876                 return $this->query( $sql, $fname );
1877         }
1878
1879         /**
1880          * INSERT SELECT wrapper
1881          * $varMap must be an associative array of the form array( 'dest1' => 'source1', ...)
1882          * Source items may be literals rather than field names, but strings should be quoted with DatabaseBase::addQuotes()
1883          * $conds may be "*" to copy the whole table
1884          * srcTable may be an array of tables.
1885          */
1886         function insertSelect( $destTable, $srcTable, $varMap, $conds, $fname = 'DatabaseBase::insertSelect',
1887                 $insertOptions = array(), $selectOptions = array() )
1888         {
1889                 $destTable = $this->tableName( $destTable );
1890
1891                 if ( is_array( $insertOptions ) ) {
1892                         $insertOptions = implode( ' ', $insertOptions );
1893                 }
1894
1895                 if ( !is_array( $selectOptions ) ) {
1896                         $selectOptions = array( $selectOptions );
1897                 }
1898
1899                 list( $startOpts, $useIndex, $tailOpts ) = $this->makeSelectOptions( $selectOptions );
1900
1901                 if ( is_array( $srcTable ) ) {
1902                         $srcTable =  implode( ',', array_map( array( &$this, 'tableName' ), $srcTable ) );
1903                 } else {
1904                         $srcTable = $this->tableName( $srcTable );
1905                 }
1906
1907                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
1908                         " SELECT $startOpts " . implode( ',', $varMap ) .
1909                         " FROM $srcTable $useIndex ";
1910
1911                 if ( $conds != '*' ) {
1912                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1913                 }
1914
1915                 $sql .= " $tailOpts";
1916
1917                 return $this->query( $sql, $fname );
1918         }
1919
1920         /**
1921          * Construct a LIMIT query with optional offset.  This is used for query
1922          * pages.  The SQL should be adjusted so that only the first $limit rows
1923          * are returned.  If $offset is provided as well, then the first $offset
1924          * rows should be discarded, and the next $limit rows should be returned.
1925          * If the result of the query is not ordered, then the rows to be returned
1926          * are theoretically arbitrary.
1927          *
1928          * $sql is expected to be a SELECT, if that makes a difference.  For
1929          * UPDATE, limitResultForUpdate should be used.
1930          *
1931          * The version provided by default works in MySQL and SQLite.  It will very
1932          * likely need to be overridden for most other DBMSes.
1933          *
1934          * @param $sql String: SQL query we will append the limit too
1935          * @param $limit Integer: the SQL limit
1936          * @param $offset Integer the SQL offset (default false)
1937          */
1938         function limitResult( $sql, $limit, $offset = false ) {
1939                 if ( !is_numeric( $limit ) ) {
1940                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
1941                 }
1942
1943                 return "$sql LIMIT "
1944                                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
1945                                 . "{$limit} ";
1946         }
1947
1948         function limitResultForUpdate( $sql, $num ) {
1949                 return $this->limitResult( $sql, $num, 0 );
1950         }
1951
1952         /**
1953          * Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
1954          * within the UNION construct.
1955          * @return Boolean
1956          */
1957         function unionSupportsOrderAndLimit() {
1958                 return true; // True for almost every DB supported
1959         }
1960
1961         /**
1962          * Construct a UNION query
1963          * This is used for providing overload point for other DB abstractions
1964          * not compatible with the MySQL syntax.
1965          * @param $sqls Array: SQL statements to combine
1966          * @param $all Boolean: use UNION ALL
1967          * @return String: SQL fragment
1968          */
1969         function unionQueries( $sqls, $all ) {
1970                 $glue = $all ? ') UNION ALL (' : ') UNION (';
1971                 return '(' . implode( $glue, $sqls ) . ')';
1972         }
1973
1974         /**
1975          * Returns an SQL expression for a simple conditional.  This doesn't need
1976          * to be overridden unless CASE isn't supported in your DBMS.
1977          *
1978          * @param $cond String: SQL expression which will result in a boolean value
1979          * @param $trueVal String: SQL expression to return if true
1980          * @param $falseVal String: SQL expression to return if false
1981          * @return String: SQL fragment
1982          */
1983         function conditional( $cond, $trueVal, $falseVal ) {
1984                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
1985         }
1986
1987         /**
1988          * Returns a comand for str_replace function in SQL query.
1989          * Uses REPLACE() in MySQL
1990          *
1991          * @param $orig String: column to modify
1992          * @param $old String: column to seek
1993          * @param $new String: column to replace with
1994          */
1995         function strreplace( $orig, $old, $new ) {
1996                 return "REPLACE({$orig}, {$old}, {$new})";
1997         }
1998
1999         /**
2000          * Convert a field to an unix timestamp
2001          *
2002          * @param $field String: field name
2003          * @return String: SQL statement
2004          */
2005         public function unixTimestamp( $field ) {
2006                 return "EXTRACT(epoch FROM $field)";
2007         }
2008
2009         /**
2010          * Determines if the last failure was due to a deadlock
2011          * STUB
2012          */
2013         function wasDeadlock() {
2014                 return false;
2015         }
2016
2017         /**
2018          * Determines if the last query error was something that should be dealt
2019          * with by pinging the connection and reissuing the query.
2020          * STUB
2021          */
2022         function wasErrorReissuable() {
2023                 return false;
2024         }
2025
2026         /**
2027          * Determines if the last failure was due to the database being read-only.
2028          * STUB
2029          */
2030         function wasReadOnlyError() {
2031                 return false;
2032         }
2033
2034         /**
2035          * Perform a deadlock-prone transaction.
2036          *
2037          * This function invokes a callback function to perform a set of write
2038          * queries. If a deadlock occurs during the processing, the transaction
2039          * will be rolled back and the callback function will be called again.
2040          *
2041          * Usage:
2042          *   $dbw->deadlockLoop( callback, ... );
2043          *
2044          * Extra arguments are passed through to the specified callback function.
2045          *
2046          * Returns whatever the callback function returned on its successful,
2047          * iteration, or false on error, for example if the retry limit was
2048          * reached.
2049          */
2050         function deadlockLoop() {
2051                 $myFname = 'DatabaseBase::deadlockLoop';
2052
2053                 $this->begin();
2054                 $args = func_get_args();
2055                 $function = array_shift( $args );
2056                 $oldIgnore = $this->ignoreErrors( true );
2057                 $tries = DEADLOCK_TRIES;
2058
2059                 if ( is_array( $function ) ) {
2060                         $fname = $function[0];
2061                 } else {
2062                         $fname = $function;
2063                 }
2064
2065                 do {
2066                         $retVal = call_user_func_array( $function, $args );
2067                         $error = $this->lastError();
2068                         $errno = $this->lastErrno();
2069                         $sql = $this->lastQuery();
2070
2071                         if ( $errno ) {
2072                                 if ( $this->wasDeadlock() ) {
2073                                         # Retry
2074                                         usleep( mt_rand( DEADLOCK_DELAY_MIN, DEADLOCK_DELAY_MAX ) );
2075                                 } else {
2076                                         $this->reportQueryError( $error, $errno, $sql, $fname );
2077                                 }
2078                         }
2079                 } while ( $this->wasDeadlock() && --$tries > 0 );
2080
2081                 $this->ignoreErrors( $oldIgnore );
2082
2083                 if ( $tries <= 0 ) {
2084                         $this->rollback( $myFname );
2085                         $this->reportQueryError( $error, $errno, $sql, $fname );
2086                         return false;
2087                 } else {
2088                         $this->commit( $myFname );
2089                         return $retVal;
2090                 }
2091         }
2092
2093         /**
2094          * Do a SELECT MASTER_POS_WAIT()
2095          *
2096          * @param $pos MySQLMasterPos object
2097          * @param $timeout Integer: the maximum number of seconds to wait for synchronisation
2098          */
2099         function masterPosWait( MySQLMasterPos $pos, $timeout ) {
2100                 $fname = 'DatabaseBase::masterPosWait';
2101                 wfProfileIn( $fname );
2102
2103                 # Commit any open transactions
2104                 if ( $this->mTrxLevel ) {
2105                         $this->commit();
2106                 }
2107
2108                 if ( !is_null( $this->mFakeSlaveLag ) ) {
2109                         $wait = intval( ( $pos->pos - microtime( true ) + $this->mFakeSlaveLag ) * 1e6 );
2110
2111                         if ( $wait > $timeout * 1e6 ) {
2112                                 wfDebug( "Fake slave timed out waiting for $pos ($wait us)\n" );
2113                                 wfProfileOut( $fname );
2114                                 return -1;
2115                         } elseif ( $wait > 0 ) {
2116                                 wfDebug( "Fake slave waiting $wait us\n" );
2117                                 usleep( $wait );
2118                                 wfProfileOut( $fname );
2119                                 return 1;
2120                         } else {
2121                                 wfDebug( "Fake slave up to date ($wait us)\n" );
2122                                 wfProfileOut( $fname );
2123                                 return 0;
2124                         }
2125                 }
2126
2127                 # Call doQuery() directly, to avoid opening a transaction if DBO_TRX is set
2128                 $encFile = $this->addQuotes( $pos->file );
2129                 $encPos = intval( $pos->pos );
2130                 $sql = "SELECT MASTER_POS_WAIT($encFile, $encPos, $timeout)";
2131                 $res = $this->doQuery( $sql );
2132
2133                 if ( $res && $row = $this->fetchRow( $res ) ) {
2134                         wfProfileOut( $fname );
2135                         return $row[0];
2136                 } else {
2137                         wfProfileOut( $fname );
2138                         return false;
2139                 }
2140         }
2141
2142         /**
2143          * Get the position of the master from SHOW SLAVE STATUS
2144          */
2145         function getSlavePos() {
2146                 if ( !is_null( $this->mFakeSlaveLag ) ) {
2147                         $pos = new MySQLMasterPos( 'fake', microtime( true ) - $this->mFakeSlaveLag );
2148                         wfDebug( __METHOD__ . ": fake slave pos = $pos\n" );
2149                         return $pos;
2150                 }
2151
2152                 $res = $this->query( 'SHOW SLAVE STATUS', 'DatabaseBase::getSlavePos' );
2153                 $row = $this->fetchObject( $res );
2154
2155                 if ( $row ) {
2156                         $pos = isset( $row->Exec_master_log_pos ) ? $row->Exec_master_log_pos : $row->Exec_Master_Log_Pos;
2157                         return new MySQLMasterPos( $row->Relay_Master_Log_File, $pos );
2158                 } else {
2159                         return false;
2160                 }
2161         }
2162
2163         /**
2164          * Get the position of the master from SHOW MASTER STATUS
2165          */
2166         function getMasterPos() {
2167                 if ( $this->mFakeMaster ) {
2168                         return new MySQLMasterPos( 'fake', microtime( true ) );
2169                 }
2170
2171                 $res = $this->query( 'SHOW MASTER STATUS', 'DatabaseBase::getMasterPos' );
2172                 $row = $this->fetchObject( $res );
2173
2174                 if ( $row ) {
2175                         return new MySQLMasterPos( $row->File, $row->Position );
2176                 } else {
2177                         return false;
2178                 }
2179         }
2180
2181         /**
2182          * Begin a transaction, committing any previously open transaction
2183          */
2184         function begin( $fname = 'DatabaseBase::begin' ) {
2185                 $this->query( 'BEGIN', $fname );
2186                 $this->mTrxLevel = 1;
2187         }
2188
2189         /**
2190          * End a transaction
2191          */
2192         function commit( $fname = 'DatabaseBase::commit' ) {
2193                 if ( $this->mTrxLevel ) {
2194                         $this->query( 'COMMIT', $fname );
2195                         $this->mTrxLevel = 0;
2196                 }
2197         }
2198
2199         /**
2200          * Rollback a transaction.
2201          * No-op on non-transactional databases.
2202          */
2203         function rollback( $fname = 'DatabaseBase::rollback' ) {
2204                 if ( $this->mTrxLevel ) {
2205                         $this->query( 'ROLLBACK', $fname, true );
2206                         $this->mTrxLevel = 0;
2207                 }
2208         }
2209
2210         /**
2211          * Begin a transaction, committing any previously open transaction
2212          * @deprecated use begin()
2213          */
2214         function immediateBegin( $fname = 'DatabaseBase::immediateBegin' ) {
2215                 wfDeprecated( __METHOD__ );
2216                 $this->begin();
2217         }
2218
2219         /**
2220          * Commit transaction, if one is open
2221          * @deprecated use commit()
2222          */
2223         function immediateCommit( $fname = 'DatabaseBase::immediateCommit' ) {
2224                 wfDeprecated( __METHOD__ );
2225                 $this->commit();
2226         }
2227
2228         /**
2229          * Creates a new table with structure copied from existing table
2230          * Note that unlike most database abstraction functions, this function does not
2231          * automatically append database prefix, because it works at a lower
2232          * abstraction level.
2233          *
2234          * @param $oldName String: name of table whose structure should be copied
2235          * @param $newName String: name of table to be created
2236          * @param $temporary Boolean: whether the new table should be temporary
2237          * @param $fname String: calling function name
2238          * @return Boolean: true if operation was successful
2239          */
2240         function duplicateTableStructure( $oldName, $newName, $temporary = false, $fname = 'DatabaseBase::duplicateTableStructure' ) {
2241                 throw new MWException( 'DatabaseBase::duplicateTableStructure is not implemented in descendant class' );
2242         }
2243
2244         /**
2245          * Return MW-style timestamp used for MySQL schema
2246          */
2247         function timestamp( $ts = 0 ) {
2248                 return wfTimestamp( TS_MW, $ts );
2249         }
2250
2251         /**
2252          * Local database timestamp format or null
2253          */
2254         function timestampOrNull( $ts = null ) {
2255                 if ( is_null( $ts ) ) {
2256                         return null;
2257                 } else {
2258                         return $this->timestamp( $ts );
2259                 }
2260         }
2261
2262         /**
2263          * @todo document
2264          */
2265         function resultObject( $result ) {
2266                 if ( empty( $result ) ) {
2267                         return false;
2268                 } elseif ( $result instanceof ResultWrapper ) {
2269                         return $result;
2270                 } elseif ( $result === true ) {
2271                         // Successful write query
2272                         return $result;
2273                 } else {
2274                         return new ResultWrapper( $this, $result );
2275                 }
2276         }
2277
2278         /**
2279          * Return aggregated value alias
2280          */
2281         function aggregateValue ( $valuedata, $valuename = 'value' ) {
2282                 return $valuename;
2283         }
2284
2285         /**
2286          * Ping the server and try to reconnect if it there is no connection
2287          *
2288          * @return bool Success or failure
2289          */
2290         function ping() {
2291                 # Stub.  Not essential to override.
2292                 return true;
2293         }
2294
2295         /**
2296          * Get slave lag.
2297          * Currently supported only by MySQL
2298          * @return Database replication lag in seconds
2299          */
2300         function getLag() {
2301                 return intval( $this->mFakeSlaveLag );
2302         }
2303
2304         /**
2305          * Get status information from SHOW STATUS in an associative array
2306          */
2307         function getStatus( $which = "%" ) {
2308                 $res = $this->query( "SHOW STATUS LIKE '{$which}'" );
2309                 $status = array();
2310
2311                 foreach ( $res as $row ) {
2312                         $status[$row->Variable_name] = $row->Value;
2313                 }
2314
2315                 return $status;
2316         }
2317
2318         /**
2319          * Return the maximum number of items allowed in a list, or 0 for unlimited.
2320          */
2321         function maxListLen() {
2322                 return 0;
2323         }
2324
2325         function encodeBlob( $b ) {
2326                 return $b;
2327         }
2328
2329         function decodeBlob( $b ) {
2330                 return $b;
2331         }
2332
2333         /**
2334          * Override database's default connection timeout.  May be useful for very
2335          * long batch queries such as full-wiki dumps, where a single query reads
2336          * out over hours or days.  May or may not be necessary for non-MySQL
2337          * databases.  For most purposes, leaving it as a no-op should be fine.
2338          *
2339          * @param $timeout Integer in seconds
2340          */
2341         public function setTimeout( $timeout ) {}
2342
2343         /**
2344          * Read and execute SQL commands from a file.
2345          * Returns true on success, error string or exception on failure (depending on object's error ignore settings)
2346          * @param $filename String: File name to open
2347          * @param $lineCallback Callback: Optional function called before reading each line
2348          * @param $resultCallback Callback: Optional function called for each MySQL result
2349          * @param $fname String: Calling function name or false if name should be generated dynamically
2350          *              using $filename
2351          */
2352         function sourceFile( $filename, $lineCallback = false, $resultCallback = false, $fname = false ) {
2353                 $fp = fopen( $filename, 'r' );
2354
2355                 if ( false === $fp ) {
2356                         if ( !defined( "MEDIAWIKI_INSTALL" ) )
2357                                 throw new MWException( "Could not open \"{$filename}\".\n" );
2358                         else
2359                                 return "Could not open \"{$filename}\".\n";
2360                 }
2361
2362                 if ( !$fname ) {
2363                         $fname = __METHOD__ . "( $filename )";
2364                 }
2365
2366                 try {
2367                         $error = $this->sourceStream( $fp, $lineCallback, $resultCallback, $fname );
2368                 }
2369                 catch ( MWException $e ) {
2370                         if ( defined( "MEDIAWIKI_INSTALL" ) ) {
2371                                 $error = $e->getMessage();
2372                         } else {
2373                                 fclose( $fp );
2374                                 throw $e;
2375                         }
2376                 }
2377
2378                 fclose( $fp );
2379
2380                 return $error;
2381         }
2382
2383         /**
2384          * Get the full path of a patch file. Originally based on archive()
2385          * from updaters.inc. Keep in mind this always returns a patch, as
2386          * it fails back to MySQL if no DB-specific patch can be found
2387          *
2388          * @param $patch String The name of the patch, like patch-something.sql
2389          * @return String Full path to patch file
2390          */
2391         public function patchPath( $patch ) {
2392                 global $IP;
2393
2394                 $dbType = $this->getType();
2395                 if ( file_exists( "$IP/maintenance/$dbType/archives/$patch" ) ) {
2396                         return "$IP/maintenance/$dbType/archives/$patch";
2397                 } else {
2398                         return "$IP/maintenance/archives/$patch";
2399                 }
2400         }
2401
2402         /**
2403          * Read and execute commands from an open file handle
2404          * Returns true on success, error string or exception on failure (depending on object's error ignore settings)
2405          * @param $fp String: File handle
2406          * @param $lineCallback Callback: Optional function called before reading each line
2407          * @param $resultCallback Callback: Optional function called for each MySQL result
2408          * @param $fname String: Calling function name
2409          */
2410         function sourceStream( $fp, $lineCallback = false, $resultCallback = false, $fname = 'DatabaseBase::sourceStream' ) {
2411                 $cmd = "";
2412                 $done = false;
2413                 $dollarquote = false;
2414
2415                 while ( ! feof( $fp ) ) {
2416                         if ( $lineCallback ) {
2417                                 call_user_func( $lineCallback );
2418                         }
2419
2420                         $line = trim( fgets( $fp, 1024 ) );
2421                         $sl = strlen( $line ) - 1;
2422
2423                         if ( $sl < 0 ) {
2424                                 continue;
2425                         }
2426
2427                         if ( '-' == $line { 0 } && '-' == $line { 1 } ) {
2428                                 continue;
2429                         }
2430
2431                         # # Allow dollar quoting for function declarations
2432                         if ( substr( $line, 0, 4 ) == '$mw$' ) {
2433                                 if ( $dollarquote ) {
2434                                         $dollarquote = false;
2435                                         $done = true;
2436                                 }
2437                                 else {
2438                                         $dollarquote = true;
2439                                 }
2440                         }
2441                         else if ( !$dollarquote ) {
2442                                 if ( ';' == $line { $sl } && ( $sl < 2 || ';' != $line { $sl - 1 } ) ) {
2443                                         $done = true;
2444                                         $line = substr( $line, 0, $sl );
2445                                 }
2446                         }
2447
2448                         if ( $cmd != '' ) {
2449                                 $cmd .= ' ';
2450                         }
2451
2452                         $cmd .= "$line\n";
2453
2454                         if ( $done ) {
2455                                 $cmd = str_replace( ';;', ";", $cmd );
2456                                 $cmd = $this->replaceVars( $cmd );
2457                                 $res = $this->query( $cmd, $fname );
2458
2459                                 if ( $resultCallback ) {
2460                                         call_user_func( $resultCallback, $res, $this );
2461                                 }
2462
2463                                 if ( false === $res ) {
2464                                         $err = $this->lastError();
2465                                         return "Query \"{$cmd}\" failed with error code \"$err\".\n";
2466                                 }
2467
2468                                 $cmd = '';
2469                                 $done = false;
2470                         }
2471                 }
2472
2473                 return true;
2474         }
2475
2476         /**
2477          * Replace variables in sourced SQL
2478          */
2479         protected function replaceVars( $ins ) {
2480                 $varnames = array(
2481                         'wgDBserver', 'wgDBname', 'wgDBintlname', 'wgDBuser',
2482                         'wgDBpassword', 'wgDBsqluser', 'wgDBsqlpassword',
2483                         'wgDBadminuser', 'wgDBadminpassword', 'wgDBTableOptions',
2484                 );
2485
2486                 // Ordinary variables
2487                 foreach ( $varnames as $var ) {
2488                         if ( isset( $GLOBALS[$var] ) ) {
2489                                 $val = addslashes( $GLOBALS[$var] ); // FIXME: safety check?
2490                                 $ins = str_replace( '{$' . $var . '}', $val, $ins );
2491                                 $ins = str_replace( '/*$' . $var . '*/`', '`' . $val, $ins );
2492                                 $ins = str_replace( '/*$' . $var . '*/', $val, $ins );
2493                         }
2494                 }
2495
2496                 // Table prefixes
2497                 $ins = preg_replace_callback( '!/\*(?:\$wgDBprefix|_)\*/([a-zA-Z_0-9]*)!',
2498                         array( $this, 'tableNameCallback' ), $ins );
2499
2500                 // Index names
2501                 $ins = preg_replace_callback( '!/\*i\*/([a-zA-Z_0-9]*)!',
2502                         array( $this, 'indexNameCallback' ), $ins );
2503
2504                 return $ins;
2505         }
2506
2507         /**
2508          * Table name callback
2509          * @private
2510          */
2511         protected function tableNameCallback( $matches ) {
2512                 return $this->tableName( $matches[1] );
2513         }
2514
2515         /**
2516          * Index name callback
2517          */
2518         protected function indexNameCallback( $matches ) {
2519                 return $this->indexName( $matches[1] );
2520         }
2521
2522         /**
2523          * Build a concatenation list to feed into a SQL query
2524          * @param $stringList Array: list of raw SQL expressions; caller is responsible for any quoting
2525          * @return String
2526          */
2527         function buildConcat( $stringList ) {
2528                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
2529         }
2530
2531         /**
2532          * Acquire a named lock
2533          *
2534          * Abstracted from Filestore::lock() so child classes can implement for
2535          * their own needs.
2536          *
2537          * @param $lockName String: name of lock to aquire
2538          * @param $method String: name of method calling us
2539          * @param $timeout Integer: timeout
2540          * @return Boolean
2541          */
2542         public function lock( $lockName, $method, $timeout = 5 ) {
2543                 return true;
2544         }
2545
2546         /**
2547          * Release a lock.
2548          *
2549          * @param $lockName String: Name of lock to release
2550          * @param $method String: Name of method calling us
2551          *
2552          * @return Returns 1 if the lock was released, 0 if the lock was not established
2553          * by this thread (in which case the lock is not released), and NULL if the named
2554          * lock did not exist
2555          */
2556         public function unlock( $lockName, $method ) {
2557                 return true;
2558         }
2559
2560         /**
2561          * Lock specific tables
2562          *
2563          * @param $read Array of tables to lock for read access
2564          * @param $write Array of tables to lock for write access
2565          * @param $method String name of caller
2566          * @param $lowPriority bool Whether to indicate writes to be LOW PRIORITY
2567          */
2568         public function lockTables( $read, $write, $method, $lowPriority = true ) {
2569                 return true;
2570         }
2571
2572         /**
2573          * Unlock specific tables
2574          *
2575          * @param $method String the caller
2576          */
2577         public function unlockTables( $method ) {
2578                 return true;
2579         }
2580
2581         /**
2582          * Get search engine class. All subclasses of this need to implement this
2583          * if they wish to use searching.
2584          *
2585          * @return String
2586          */
2587         public function getSearchEngine() {
2588                 return 'SearchEngineDummy';
2589         }
2590
2591         /**
2592          * Allow or deny "big selects" for this session only. This is done by setting
2593          * the sql_big_selects session variable.
2594          *
2595          * This is a MySQL-specific feature.
2596          *
2597          * @param $value Mixed: true for allow, false for deny, or "default" to restore the initial value
2598          */
2599         public function setBigSelects( $value = true ) {
2600                 // no-op
2601         }
2602 }
2603
2604 /******************************************************************************
2605  * Utility classes
2606  *****************************************************************************/
2607
2608 /**
2609  * Utility class.
2610  * @ingroup Database
2611  */
2612 class DBObject {
2613         public $mData;
2614
2615         function __construct( $data ) {
2616                 $this->mData = $data;
2617         }
2618
2619         function isLOB() {
2620                 return false;
2621         }
2622
2623         function data() {
2624                 return $this->mData;
2625         }
2626 }
2627
2628 /**
2629  * Utility class
2630  * @ingroup Database
2631  *
2632  * This allows us to distinguish a blob from a normal string and an array of strings
2633  */
2634 class Blob {
2635         private $mData;
2636
2637         function __construct( $data ) {
2638                 $this->mData = $data;
2639         }
2640
2641         function fetch() {
2642                 return $this->mData;
2643         }
2644 }
2645
2646 /**
2647  * Base for all database-specific classes representing information about database fields
2648  * @ingroup Database
2649  */
2650 interface Field {
2651         /**
2652          * Field name
2653          * @return string
2654          */
2655         function name();
2656
2657         /**
2658          * Name of table this field belongs to
2659          * @return string
2660          */
2661         function tableName();
2662
2663         /**
2664          * Database type
2665          * @return string
2666          */
2667         function type();
2668
2669         /**
2670          * Whether this field can store NULL values
2671          * @return bool
2672          */
2673         function isNullable();
2674 }
2675
2676 /******************************************************************************
2677  * Error classes
2678  *****************************************************************************/
2679
2680 /**
2681  * Database error base class
2682  * @ingroup Database
2683  */
2684 class DBError extends MWException {
2685         public $db;
2686
2687         /**
2688          * Construct a database error
2689          * @param $db Database object which threw the error
2690          * @param $error A simple error message to be used for debugging
2691          */
2692         function __construct( DatabaseBase &$db, $error ) {
2693                 $this->db =& $db;
2694                 parent::__construct( $error );
2695         }
2696
2697         function getText() {
2698                 global $wgShowDBErrorBacktrace;
2699
2700                 $s = $this->getMessage() . "\n";
2701
2702                 if ( $wgShowDBErrorBacktrace ) {
2703                         $s .= "Backtrace:\n" . $this->getTraceAsString() . "\n";
2704                 }
2705
2706                 return $s;
2707         }
2708 }
2709
2710 /**
2711  * @ingroup Database
2712  */
2713 class DBConnectionError extends DBError {
2714         public $error;
2715
2716         function __construct( DatabaseBase &$db, $error = 'unknown error' ) {
2717                 $msg = 'DB connection error';
2718
2719                 if ( trim( $error ) != '' ) {
2720                         $msg .= ": $error";
2721                 }
2722
2723                 $this->error = $error;
2724
2725                 parent::__construct( $db, $msg );
2726         }
2727
2728         function useOutputPage() {
2729                 // Not likely to work
2730                 return false;
2731         }
2732
2733         function useMessageCache() {
2734                 // Not likely to work
2735                 return false;
2736         }
2737
2738         function getLogMessage() {
2739                 # Don't send to the exception log
2740                 return false;
2741         }
2742
2743         function getPageTitle() {
2744                 global $wgSitename, $wgLang;
2745
2746                 $header = "$wgSitename has a problem";
2747
2748                 if ( $wgLang instanceof Language ) {
2749                         $header = htmlspecialchars( $wgLang->getMessage( 'dberr-header' ) );
2750                 }
2751
2752                 return $header;
2753         }
2754
2755         function getHTML() {
2756                 global $wgLang, $wgMessageCache, $wgUseFileCache, $wgShowDBErrorBacktrace;
2757
2758                 $sorry = 'Sorry! This site is experiencing technical difficulties.';
2759                 $again = 'Try waiting a few minutes and reloading.';
2760                 $info  = '(Can\'t contact the database server: $1)';
2761
2762                 if ( $wgLang instanceof Language ) {
2763                         $sorry = htmlspecialchars( $wgLang->getMessage( 'dberr-problems' ) );
2764                         $again = htmlspecialchars( $wgLang->getMessage( 'dberr-again' ) );
2765                         $info  = htmlspecialchars( $wgLang->getMessage( 'dberr-info' ) );
2766                 }
2767
2768                 # No database access
2769                 if ( is_object( $wgMessageCache ) ) {
2770                         $wgMessageCache->disable();
2771                 }
2772
2773                 if ( trim( $this->error ) == '' ) {
2774                         $this->error = $this->db->getProperty( 'mServer' );
2775                 }
2776
2777                 $noconnect = "<p><strong>$sorry</strong><br />$again</p><p><small>$info</small></p>";
2778                 $text = str_replace( '$1', $this->error, $noconnect );
2779
2780                 if ( $wgShowDBErrorBacktrace ) {
2781                         $text .= '<p>Backtrace:</p><p>' . nl2br( htmlspecialchars( $this->getTraceAsString() ) );
2782                 }
2783
2784                 $extra = $this->searchForm();
2785
2786                 if ( $wgUseFileCache ) {
2787                         try {
2788                                 $cache = $this->fileCachedPage();
2789                                 # Cached version on file system?
2790                                 if ( $cache !== null ) {
2791                                         # Hack: extend the body for error messages
2792                                         $cache = str_replace( array( '</html>', '</body>' ), '', $cache );
2793                                         # Add cache notice...
2794                                         $cachederror = "This is a cached copy of the requested page, and may not be up to date. ";
2795
2796                                         # Localize it if possible...
2797                                         if ( $wgLang instanceof Language ) {
2798                                                 $cachederror = htmlspecialchars( $wgLang->getMessage( 'dberr-cachederror' ) );
2799                                         }
2800
2801                                         $warning = "<div style='color:red;font-size:150%;font-weight:bold;'>$cachederror</div>";
2802
2803                                         # Output cached page with notices on bottom and re-close body
2804                                         return "{$cache}{$warning}<hr />$text<hr />$extra</body></html>";
2805                                 }
2806                         } catch ( MWException $e ) {
2807                                 // Do nothing, just use the default page
2808                         }
2809                 }
2810
2811                 # Headers needed here - output is just the error message
2812                 return $this->htmlHeader() . "$text<hr />$extra" . $this->htmlFooter();
2813         }
2814
2815         function searchForm() {
2816                 global $wgSitename, $wgServer, $wgLang, $wgInputEncoding;
2817
2818                 $usegoogle = "You can try searching via Google in the meantime.";
2819                 $outofdate = "Note that their indexes of our content may be out of date.";
2820                 $googlesearch = "Search";
2821
2822                 if ( $wgLang instanceof Language ) {
2823                         $usegoogle = htmlspecialchars( $wgLang->getMessage( 'dberr-usegoogle' ) );
2824                         $outofdate = htmlspecialchars( $wgLang->getMessage( 'dberr-outofdate' ) );
2825                         $googlesearch  = htmlspecialchars( $wgLang->getMessage( 'searchbutton' ) );
2826                 }
2827
2828                 $search = htmlspecialchars( @$_REQUEST['search'] );
2829
2830                 $trygoogle = <<<EOT
2831 <div style="margin: 1.5em">$usegoogle<br />
2832 <small>$outofdate</small></div>
2833 <!-- SiteSearch Google -->
2834 <form method="get" action="http://www.google.com/search" id="googlesearch">
2835         <input type="hidden" name="domains" value="$wgServer" />
2836         <input type="hidden" name="num" value="50" />
2837         <input type="hidden" name="ie" value="$wgInputEncoding" />
2838         <input type="hidden" name="oe" value="$wgInputEncoding" />
2839
2840         <input type="text" name="q" size="31" maxlength="255" value="$search" />
2841         <input type="submit" name="btnG" value="$googlesearch" />
2842   <div>
2843         <input type="radio" name="sitesearch" id="gwiki" value="$wgServer" checked="checked" /><label for="gwiki">$wgSitename</label>
2844         <input type="radio" name="sitesearch" id="gWWW" value="" /><label for="gWWW">WWW</label>
2845   </div>
2846 </form>
2847 <!-- SiteSearch Google -->
2848 EOT;
2849                 return $trygoogle;
2850         }
2851
2852         function fileCachedPage() {
2853                 global $wgTitle, $title, $wgLang, $wgOut;
2854
2855                 if ( $wgOut->isDisabled() ) {
2856                         return; // Done already?
2857                 }
2858
2859                 $mainpage = 'Main Page';
2860
2861                 if ( $wgLang instanceof Language ) {
2862                         $mainpage    = htmlspecialchars( $wgLang->getMessage( 'mainpage' ) );
2863                 }
2864
2865                 if ( $wgTitle ) {
2866                         $t =& $wgTitle;
2867                 } elseif ( $title ) {
2868                         $t = Title::newFromURL( $title );
2869                 } else {
2870                         $t = Title::newFromText( $mainpage );
2871                 }
2872
2873                 $cache = new HTMLFileCache( $t );
2874                 if ( $cache->isFileCached() ) {
2875                         return $cache->fetchPageText();
2876                 } else {
2877                         return '';
2878                 }
2879         }
2880
2881         function htmlBodyOnly() {
2882                 return true;
2883         }
2884 }
2885
2886 /**
2887  * @ingroup Database
2888  */
2889 class DBQueryError extends DBError {
2890         public $error, $errno, $sql, $fname;
2891
2892         function __construct( DatabaseBase &$db, $error, $errno, $sql, $fname ) {
2893                 $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" .
2894                   "Query: $sql\n" .
2895                   "Function: $fname\n" .
2896                   "Error: $errno $error\n";
2897
2898                 parent::__construct( $db, $message );
2899
2900                 $this->error = $error;
2901                 $this->errno = $errno;
2902                 $this->sql = $sql;
2903                 $this->fname = $fname;
2904         }
2905
2906         function getText() {
2907                 global $wgShowDBErrorBacktrace;
2908
2909                 if ( $this->useMessageCache() ) {
2910                         $s = wfMsg( 'dberrortextcl', htmlspecialchars( $this->getSQL() ),
2911                                 htmlspecialchars( $this->fname ), $this->errno, htmlspecialchars( $this->error ) ) . "\n";
2912
2913                         if ( $wgShowDBErrorBacktrace ) {
2914                                 $s .= "Backtrace:\n" . $this->getTraceAsString() . "\n";
2915                         }
2916
2917                         return $s;
2918                 } else {
2919                         return parent::getText();
2920                 }
2921         }
2922
2923         function getSQL() {
2924                 global $wgShowSQLErrors;
2925
2926                 if ( !$wgShowSQLErrors ) {
2927                         return $this->msg( 'sqlhidden', 'SQL hidden' );
2928                 } else {
2929                         return $this->sql;
2930                 }
2931         }
2932
2933         function getLogMessage() {
2934                 # Don't send to the exception log
2935                 return false;
2936         }
2937
2938         function getPageTitle() {
2939                 return $this->msg( 'databaseerror', 'Database error' );
2940         }
2941
2942         function getHTML() {
2943                 global $wgShowDBErrorBacktrace;
2944
2945                 if ( $this->useMessageCache() ) {
2946                         $s = wfMsgNoDB( 'dberrortext', htmlspecialchars( $this->getSQL() ),
2947                           htmlspecialchars( $this->fname ), $this->errno, htmlspecialchars( $this->error ) );
2948                 } else {
2949                         $s = nl2br( htmlspecialchars( $this->getMessage() ) );
2950                 }
2951
2952                 if ( $wgShowDBErrorBacktrace ) {
2953                         $s .= '<p>Backtrace:</p><p>' . nl2br( htmlspecialchars( $this->getTraceAsString() ) );
2954                 }
2955
2956                 return $s;
2957         }
2958 }
2959
2960 /**
2961  * @ingroup Database
2962  */
2963 class DBUnexpectedError extends DBError {}
2964
2965
2966 /**
2967  * Result wrapper for grabbing data queried by someone else
2968  * @ingroup Database
2969  */
2970 class ResultWrapper implements Iterator {
2971         var $db, $result, $pos = 0, $currentRow = null;
2972
2973         /**
2974          * Create a new result object from a result resource and a Database object
2975          */
2976         function __construct( $database, $result ) {
2977                 $this->db = $database;
2978
2979                 if ( $result instanceof ResultWrapper ) {
2980                         $this->result = $result->result;
2981                 } else {
2982                         $this->result = $result;
2983                 }
2984         }
2985
2986         /**
2987          * Get the number of rows in a result object
2988          */
2989         function numRows() {
2990                 return $this->db->numRows( $this );
2991         }
2992
2993         /**
2994          * Fetch the next row from the given result object, in object form.
2995          * Fields can be retrieved with $row->fieldname, with fields acting like
2996          * member variables.
2997          *
2998          * @return MySQL row object
2999          * @throws DBUnexpectedError Thrown if the database returns an error
3000          */
3001         function fetchObject() {
3002                 return $this->db->fetchObject( $this );
3003         }
3004
3005         /**
3006          * Fetch the next row from the given result object, in associative array
3007          * form.  Fields are retrieved with $row['fieldname'].
3008          *
3009          * @return MySQL row object
3010          * @throws DBUnexpectedError Thrown if the database returns an error
3011          */
3012         function fetchRow() {
3013                 return $this->db->fetchRow( $this );
3014         }
3015
3016         /**
3017          * Free a result object
3018          */
3019         function free() {
3020                 $this->db->freeResult( $this );
3021                 unset( $this->result );
3022                 unset( $this->db );
3023         }
3024
3025         /**
3026          * Change the position of the cursor in a result object
3027          * See mysql_data_seek()
3028          */
3029         function seek( $row ) {
3030                 $this->db->dataSeek( $this, $row );
3031         }
3032
3033         /*********************
3034          * Iterator functions
3035          * Note that using these in combination with the non-iterator functions
3036          * above may cause rows to be skipped or repeated.
3037          */
3038
3039         function rewind() {
3040                 if ( $this->numRows() ) {
3041                         $this->db->dataSeek( $this, 0 );
3042                 }
3043                 $this->pos = 0;
3044                 $this->currentRow = null;
3045         }
3046
3047         function current() {
3048                 if ( is_null( $this->currentRow ) ) {
3049                         $this->next();
3050                 }
3051                 return $this->currentRow;
3052         }
3053
3054         function key() {
3055                 return $this->pos;
3056         }
3057
3058         function next() {
3059                 $this->pos++;
3060                 $this->currentRow = $this->fetchObject();
3061                 return $this->currentRow;
3062         }
3063
3064         function valid() {
3065                 return $this->current() !== false;
3066         }
3067 }
3068
3069 /**
3070  * Overloads the relevant methods of the real ResultsWrapper so it
3071  * doesn't go anywhere near an actual database.
3072  */
3073 class FakeResultWrapper extends ResultWrapper {
3074         var $result     = array();
3075         var $db         = null; // And it's going to stay that way :D
3076         var $pos        = 0;
3077         var $currentRow = null;
3078
3079         function __construct( $array ) {
3080                 $this->result = $array;
3081         }
3082
3083         function numRows() {
3084                 return count( $this->result );
3085         }
3086
3087         function fetchRow() {
3088                 $this->currentRow = $this->result[$this->pos++];
3089                 return $this->currentRow;
3090         }
3091
3092         function seek( $row ) {
3093                 $this->pos = $row;
3094         }
3095
3096         function free() {}
3097
3098         // Callers want to be able to access fields with $this->fieldName
3099         function fetchObject() {
3100                 $this->currentRow = $this->result[$this->pos++];
3101                 return (object)$this->currentRow;
3102         }
3103
3104         function rewind() {
3105                 $this->pos = 0;
3106                 $this->currentRow = null;
3107         }
3108 }
3109
3110 /**
3111  * Used by DatabaseBase::buildLike() to represent characters that have special meaning in SQL LIKE clauses
3112  * and thus need no escaping. Don't instantiate it manually, use DatabaseBase::anyChar() and anyString() instead.
3113  */
3114 class LikeMatch {
3115         private $str;
3116
3117         public function __construct( $s ) {
3118                 $this->str = $s;
3119         }
3120
3121         public function toString() {
3122                 return $this->str;
3123         }
3124 }