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          * If the failFunction is set to a non-zero integer, returns success
  36          *
  37          * @param $server String: database server host
  38          * @param $user String: database user name
  39          * @param $password String: database user password
  40          * @param $dbName String: database name
  41          * @return bool
  42          * @throws DBConnectionError
  43          */
  44         public function open( $server, $user, $password, $dbName );
  45
  46         /**
  47          * The DBMS-dependent part of query()
  48          * @todo @fixme Make this private someday
  49          *
  50          * @param  $sql String: SQL query.
  51          * @return Result object to feed to fetchObject, fetchRow, ...; or false on failure
  52          * @private
  53          */
  54         /*private*/ function doQuery( $sql );
  55
  56         /**
  57          * Fetch the next row from the given result object, in object form.
  58          * Fields can be retrieved with $row->fieldname, with fields acting like
  59          * member variables.
  60          *
  61          * @param $res SQL result object as returned from DatabaseBase::query(), etc.
  62          * @return Row object
  63          * @throws DBUnexpectedError Thrown if the database returns an error
  64          */
  65         public function fetchObject( $res );
  66
  67         /**
  68          * Fetch the next row from the given result object, in associative array
  69          * form.  Fields are retrieved with $row['fieldname'].
  70          *
  71          * @param $res SQL result object as returned from DatabaseBase::query(), etc.
  72          * @return Row object
  73          * @throws DBUnexpectedError Thrown if the database returns an error
  74          */
  75         public function fetchRow( $res );
  76
  77         /**
  78          * Get the number of rows in a result object
  79          *
  80          * @param $res Mixed: A SQL result
  81          * @return int
  82          */
  83         public function numRows( $res );
  84
  85         /**
  86          * Get the number of fields in a result object
  87          * @see http://www.php.net/mysql_num_fields
  88          *
  89          * @param $res Mixed: A SQL result
  90          * @return int
  91          */
  92         public function numFields( $res );
  93
  94         /**
  95          * Get a field name in a result object
  96          * @see http://www.php.net/mysql_field_name
  97          *
  98          * @param $res Mixed: A SQL result
  99          * @param $n Integer
 100          * @return string
 101          */
 102         public function fieldName( $res, $n );
 103
 104         /**
 105          * Get the inserted value of an auto-increment row
 106          *
 107          * The value inserted should be fetched from nextSequenceValue()
 108          *
 109          * Example:
 110          * $id = $dbw->nextSequenceValue('page_page_id_seq');
 111          * $dbw->insert('page',array('page_id' => $id));
 112          * $id = $dbw->insertId();
 113          *
 114          * @return int
 115          */
 116         public function insertId();
 117
 118         /**
 119          * Change the position of the cursor in a result object
 120          * @see http://www.php.net/mysql_data_seek
 121          *
 122          * @param $res Mixed: A SQL result
 123          * @param $row Mixed: Either MySQL row or ResultWrapper
 124          */
 125         public function dataSeek( $res, $row );
 126
 127         /**
 128          * Get the last error number
 129          * @see http://www.php.net/mysql_errno
 130          *
 131          * @return int
 132          */
 133         public function lastErrno();
 134
 135         /**
 136          * Get a description of the last error
 137          * @see http://www.php.net/mysql_error
 138          *
 139          * @return string
 140          */
 141         public function lastError();
 142
 143         /**
 144          * mysql_fetch_field() wrapper
 145          * Returns false if the field doesn't exist
 146          *
 147          * @param $table string: table name
 148          * @param $field string: field name
 149          */
 150         public function fieldInfo( $table, $field );
 151
 152         /**
 153          * Get the number of rows affected by the last write query
 154          * @see http://www.php.net/mysql_affected_rows
 155          *
 156          * @return int
 157          */
 158         public function affectedRows();
 159
 160         /**
 161          * Wrapper for addslashes()
 162          *
 163          * @param $s string: to be slashed.
 164          * @return string: slashed string.
 165          */
 166         public function strencode( $s );
 167
 168         /**
 169          * Returns a wikitext link to the DB's website, e.g.,
 170          *         return "[http://www.mysql.com/ MySQL]";
 171          * Should at least contain plain text, if for some reason
 172          * your database has no website.
 173          *
 174          * @return string: wikitext of a link to the server software's web site
 175          */
 176         public static function getSoftwareLink();
 177
 178         /**
 179          * A string describing the current software version, like from
 180          * mysql_get_server_info().
 181          *
 182          * @return string: Version information from the database server.
 183          */
 184         public function getServerVersion();
 185
 186         /**
 187          * A string describing the current software version, and possibly
 188          * other details in a user-friendly way.  Will be listed on Special:Version, etc.
 189          * Use getServerVersion() to get machine-friendly information.
 190          *
 191          * @return string: Version information from the database server
 192          */
 193         public function getServerInfo();
 194 }
 195
 196 /**
 197  * Database abstraction object
 198  * @ingroup Database
 199  */
 200 abstract class DatabaseBase implements DatabaseType {
 201
 202 # ------------------------------------------------------------------------------
 203 # Variables
 204 # ------------------------------------------------------------------------------
 205
 206         protected $mLastQuery = '';
 207         protected $mDoneWrites = false;
 208         protected $mPHPError = false;
 209
 210         protected $mServer, $mUser, $mPassword, $mConn = null, $mDBname;
 211         protected $mOpened = false;
 212
 213         protected $mFailFunction;
 214         protected $mTablePrefix;
 215         protected $mFlags;
 216         protected $mTrxLevel = 0;
 217         protected $mErrorCount = 0;
 218         protected $mLBInfo = array();
 219         protected $mFakeSlaveLag = null, $mFakeMaster = false;
 220         protected $mDefaultBigSelects = null;
 221
 222 # ------------------------------------------------------------------------------
 223 # Accessors
 224 # ------------------------------------------------------------------------------
 225         # These optionally set a variable and return the previous state
 226
 227         /**
 228          * A string describing the current software version, and possibly
 229          * other details in a user-friendly way.  Will be listed on Special:Version, etc.
 230          * Use getServerVersion() to get machine-friendly information.
 231          *
 232          * @return string: Version information from the database server
 233          */
 234         public function getServerInfo() {
 235                 return $this->getServerVersion();
 236         }
 237
 238         /**
 239          * Fail function, takes a Database as a parameter
 240          * Set to false for default, 1 for ignore errors
 241          */
 242         function failFunction( $function = null ) {
 243                 return wfSetVar( $this->mFailFunction, $function );
 244         }
 245
 246         /**
 247          * Boolean, controls output of large amounts of debug information
 248          */
 249         function debug( $debug = null ) {
 250                 return wfSetBit( $this->mFlags, DBO_DEBUG, $debug );
 251         }
 252
 253         /**
 254          * Turns buffering of SQL result sets on (true) or off (false).
 255          * Default is "on" and it should not be changed without good reasons.
 256          */
 257         function bufferResults( $buffer = null ) {
 258                 if ( is_null( $buffer ) ) {
 259                         return !(bool)( $this->mFlags & DBO_NOBUFFER );
 260                 } else {
 261                         return !wfSetBit( $this->mFlags, DBO_NOBUFFER, !$buffer );
 262                 }
 263         }
 264
 265         /**
 266          * Turns on (false) or off (true) the automatic generation and sending
 267          * of a "we're sorry, but there has been a database error" page on
 268          * database errors. Default is on (false). When turned off, the
 269          * code should use lastErrno() and lastError() to handle the
 270          * situation as appropriate.
 271          */
 272         function ignoreErrors( $ignoreErrors = null ) {
 273                 return wfSetBit( $this->mFlags, DBO_IGNORE, $ignoreErrors );
 274         }
 275
 276         /**
 277          * The current depth of nested transactions
 278          * @param $level Integer: , default NULL.
 279          */
 280         function trxLevel( $level = null ) {
 281                 return wfSetVar( $this->mTrxLevel, $level );
 282         }
 283
 284         /**
 285          * Number of errors logged, only useful when errors are ignored
 286          */
 287         function errorCount( $count = null ) {
 288                 return wfSetVar( $this->mErrorCount, $count );
 289         }
 290
 291         function tablePrefix( $prefix = null ) {
 292                 return wfSetVar( $this->mTablePrefix, $prefix );
 293         }
 294
 295         /**
 296          * Properties passed down from the server info array of the load balancer
 297          */
 298         function getLBInfo( $name = null ) {
 299                 if ( is_null( $name ) ) {
 300                         return $this->mLBInfo;
 301                 } else {
 302                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 303                                 return $this->mLBInfo[$name];
 304                         } else {
 305                                 return null;
 306                         }
 307                 }
 308         }
 309
 310         function setLBInfo( $name, $value = null ) {
 311                 if ( is_null( $value ) ) {
 312                         $this->mLBInfo = $name;
 313                 } else {
 314                         $this->mLBInfo[$name] = $value;
 315                 }
 316         }
 317
 318         /**
 319          * Set lag time in seconds for a fake slave
 320          */
 321         function setFakeSlaveLag( $lag ) {
 322                 $this->mFakeSlaveLag = $lag;
 323         }
 324
 325         /**
 326          * Make this connection a fake master
 327          */
 328         function setFakeMaster( $enabled = true ) {
 329                 $this->mFakeMaster = $enabled;
 330         }
 331
 332         /**
 333          * Returns true if this database supports (and uses) cascading deletes
 334          */
 335         function cascadingDeletes() {
 336                 return false;
 337         }
 338
 339         /**
 340          * Returns true if this database supports (and uses) triggers (e.g. on the page table)
 341          */
 342         function cleanupTriggers() {
 343                 return false;
 344         }
 345
 346         /**
 347          * Returns true if this database is strict about what can be put into an IP field.
 348          * Specifically, it uses a NULL value instead of an empty string.
 349          */
 350         function strictIPs() {
 351                 return false;
 352         }
 353
 354         /**
 355          * Returns true if this database uses timestamps rather than integers
 356         */
 357         function realTimestamps() {
 358                 return false;
 359         }
 360
 361         /**
 362          * Returns true if this database does an implicit sort when doing GROUP BY
 363          */
 364         function implicitGroupby() {
 365                 return true;
 366         }
 367
 368         /**
 369          * Returns true if this database does an implicit order by when the column has an index
 370          * For example: SELECT page_title FROM page LIMIT 1
 371          */
 372         function implicitOrderby() {
 373                 return true;
 374         }
 375
 376         /**
 377          * Returns true if this database requires that SELECT DISTINCT queries require that all
 378            ORDER BY expressions occur in the SELECT list per the SQL92 standard
 379          */
 380         function standardSelectDistinct() {
 381                 return true;
 382         }
 383
 384         /**
 385          * Returns true if this database can do a native search on IP columns
 386          * e.g. this works as expected: .. WHERE rc_ip = '127.42.12.102/32';
 387          */
 388         function searchableIPs() {
 389                 return false;
 390         }
 391
 392         /**
 393          * Returns true if this database can use functional indexes
 394          */
 395         function functionalIndexes() {
 396                 return false;
 397         }
 398
 399         /**
 400          * Return the last query that went through DatabaseBase::query()
 401          * @return String
 402          */
 403         function lastQuery() { return $this->mLastQuery; }
 404
 405
 406         /**
 407          * Returns true if the connection may have been used for write queries.
 408          * Should return true if unsure.
 409          */
 410         function doneWrites() { return $this->mDoneWrites; }
 411
 412         /**
 413          * Is a connection to the database open?
 414          * @return Boolean
 415          */
 416         function isOpen() { return $this->mOpened; }
 417
 418         /**
 419          * Set a flag for this connection
 420          *
 421          * @param $flag Integer: DBO_* constants from Defines.php:
 422          *       - DBO_DEBUG: output some debug info (same as debug())
 423          *       - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
 424          *       - DBO_IGNORE: ignore errors (same as ignoreErrors())
 425          *       - DBO_TRX: automatically start transactions
 426          *       - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
 427          *               and removes it in command line mode
 428          *       - DBO_PERSISTENT: use persistant database connection
 429          */
 430         function setFlag( $flag ) {
 431                 $this->mFlags |= $flag;
 432         }
 433
 434         /**
 435          * Clear a flag for this connection
 436          *
 437          * @param $flag: same as setFlag()'s $flag param
 438          */
 439         function clearFlag( $flag ) {
 440                 $this->mFlags &= ~$flag;
 441         }
 442
 443         /**
 444          * Returns a boolean whether the flag $flag is set for this connection
 445          *
 446          * @param $flag: same as setFlag()'s $flag param
 447          * @return Boolean
 448          */
 449         function getFlag( $flag ) {
 450                 return !!( $this->mFlags & $flag );
 451         }
 452
 453         /**
 454          * General read-only accessor
 455          */
 456         function getProperty( $name ) {
 457                 return $this->$name;
 458         }
 459
 460         function getWikiID() {
 461                 if ( $this->mTablePrefix ) {
 462                         return "{$this->mDBname}-{$this->mTablePrefix}";
 463                 } else {
 464                         return $this->mDBname;
 465                 }
 466         }
 467
 468         /**
 469          * Return a path to the DBMS-specific schema, otherwise default to tables.sql
 470          */
 471         public function getSchema() {
 472                 global $IP;
 473                 if ( file_exists( "$IP/maintenance/" . $this->getType() . "/tables.sql" ) ) {
 474                         return "$IP/maintenance/" . $this->getType() . "/tables.sql";
 475                 } else {
 476                         return "$IP/maintenance/tables.sql";
 477                 }
 478         }
 479
 480 # ------------------------------------------------------------------------------
 481 # Other functions
 482 # ------------------------------------------------------------------------------
 483
 484         /**
 485          * Constructor.
 486          * @param $server String: database server host
 487          * @param $user String: database user name
 488          * @param $password String: database user password
 489          * @param $dbName String: database name
 490          * @param $failFunction
 491          * @param $flags
 492          * @param $tablePrefix String: database table prefixes. By default use the prefix gave in LocalSettings.php
 493          */
 494         function __construct( $server = false, $user = false, $password = false, $dbName = false,
 495                 $failFunction = false, $flags = 0, $tablePrefix = 'get from global'
 496         ) {
 497                 global $wgOut, $wgDBprefix, $wgCommandLineMode;
 498
 499                 # Can't get a reference if it hasn't been set yet
 500                 if ( !isset( $wgOut ) ) {
 501                         $wgOut = null;
 502                 }
 503
 504                 $this->mFailFunction = $failFunction;
 505                 $this->mFlags = $flags;
 506
 507                 if ( $this->mFlags & DBO_DEFAULT ) {
 508                         if ( $wgCommandLineMode ) {
 509                                 $this->mFlags &= ~DBO_TRX;
 510                         } else {
 511                                 $this->mFlags |= DBO_TRX;
 512                         }
 513                 }
 514
 515                 /*
 516                 // Faster read-only access
 517                 if ( wfReadOnly() ) {
 518                         $this->mFlags |= DBO_PERSISTENT;
 519                         $this->mFlags &= ~DBO_TRX;
 520                 }*/
 521
 522                 /** Get the default table prefix*/
 523                 if ( $tablePrefix == 'get from global' ) {
 524                         $this->mTablePrefix = $wgDBprefix;
 525                 } else {
 526                         $this->mTablePrefix = $tablePrefix;
 527                 }
 528
 529                 if ( $server ) {
 530                         $this->open( $server, $user, $password, $dbName );
 531                 }
 532         }
 533
 534         /**
 535          * Same as new DatabaseMysql( ... ), kept for backward compatibility
 536          * @param $server String: database server host
 537          * @param $user String: database user name
 538          * @param $password String: database user password
 539          * @param $dbName String: database name
 540          * @param failFunction
 541          * @param $flags
 542          */
 543         static function newFromParams( $server, $user, $password, $dbName, $failFunction = false, $flags = 0 ) {
 544                 wfDeprecated( __METHOD__ );
 545                 return new DatabaseMysql( $server, $user, $password, $dbName, $failFunction, $flags );
 546         }
 547
 548         protected function installErrorHandler() {
 549                 $this->mPHPError = false;
 550                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 551                 set_error_handler( array( $this, 'connectionErrorHandler' ) );
 552         }
 553
 554         protected function restoreErrorHandler() {
 555                 restore_error_handler();
 556                 if ( $this->htmlErrors !== false ) {
 557                         ini_set( 'html_errors', $this->htmlErrors );
 558                 }
 559                 if ( $this->mPHPError ) {
 560                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 561                         $error = preg_replace( '!^.*?:(.*)$!', '$1', $error );
 562                         return $error;
 563                 } else {
 564                         return false;
 565                 }
 566         }
 567
 568         protected function connectionErrorHandler( $errno,      $errstr ) {
 569                 $this->mPHPError = $errstr;
 570         }
 571
 572         /**
 573          * Closes a database connection.
 574          * if it is open : commits any open transactions
 575          *
 576          * @return Bool operation success. true if already closed.
 577          */
 578         function close() {
 579                 # Stub, should probably be overridden
 580                 return true;
 581         }
 582
 583         /**
 584          * @param $error String: fallback error message, used if none is given by DB
 585          */
 586         function reportConnectionError( $error = 'Unknown error' ) {
 587                 $myError = $this->lastError();
 588                 if ( $myError ) {
 589                         $error = $myError;
 590                 }
 591
 592                 if ( $this->mFailFunction ) {
 593                         # Legacy error handling method
 594                         if ( !is_int( $this->mFailFunction ) ) {
 595                                 $ff = $this->mFailFunction;
 596                                 $ff( $this, $error );
 597                         }
 598                 } else {
 599                         # New method
 600                         throw new DBConnectionError( $this, $error );
 601                 }
 602         }
 603
 604         /**
 605          * Determine whether a query writes to the DB.
 606          * Should return true if unsure.
 607          */
 608         function isWriteQuery( $sql ) {
 609                 return !preg_match( '/^(?:SELECT|BEGIN|COMMIT|SET|SHOW|\(SELECT)\b/i', $sql );
 610         }
 611
 612         /**
 613          * Usually aborts on failure.  If errors are explicitly ignored, returns success.
 614          *
 615          * @param  $sql            String: SQL query
 616          * @param  $fname          String: Name of the calling function, for profiling/SHOW PROCESSLIST
 617          *         comment (you can use __METHOD__ or add some extra info)
 618          * @param  $tempIgnore Boolean:   Whether to avoid throwing an exception on errors...
 619          *         maybe best to catch the exception instead?
 620          * @return true for a successful write query, ResultWrapper object for a successful read query,
 621          *         or false on failure if $tempIgnore set
 622          * @throws DBQueryError Thrown when the database returns an error of any kind
 623          */
 624         public function query( $sql, $fname = '', $tempIgnore = false ) {
 625                 global $wgProfiler;
 626
 627                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 628                 if ( isset( $wgProfiler ) ) {
 629                         # generalizeSQL will probably cut down the query to reasonable
 630                         # logging size most of the time. The substr is really just a sanity check.
 631
 632                         # Who's been wasting my precious column space? -- TS
 633                         # $profName = 'query: ' . $fname . ' ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 634
 635                         if ( $isMaster ) {
 636                                 $queryProf = 'query-m: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 637                                 $totalProf = 'DatabaseBase::query-master';
 638                         } else {
 639                                 $queryProf = 'query: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 640                                 $totalProf = 'DatabaseBase::query';
 641                         }
 642
 643                         wfProfileIn( $totalProf );
 644                         wfProfileIn( $queryProf );
 645                 }
 646
 647                 $this->mLastQuery = $sql;
 648                 if ( !$this->mDoneWrites && $this->isWriteQuery( $sql ) ) {
 649                         // Set a flag indicating that writes have been done
 650                         wfDebug( __METHOD__ . ": Writes done: $sql\n" );
 651                         $this->mDoneWrites = true;
 652                 }
 653
 654                 # Add a comment for easy SHOW PROCESSLIST interpretation
 655                 # if ( $fname ) {
 656                         global $wgUser;
 657                         if ( is_object( $wgUser ) && !( $wgUser instanceof StubObject ) ) {
 658                                 $userName = $wgUser->getName();
 659                                 if ( mb_strlen( $userName ) > 15 ) {
 660                                         $userName = mb_substr( $userName, 0, 15 ) . '...';
 661                                 }
 662                                 $userName = str_replace( '/', '', $userName );
 663                         } else {
 664                                 $userName = '';
 665                         }
 666                         $commentedSql = preg_replace( '/\s/', " /* $fname $userName */ ", $sql, 1 );
 667                 # } else {
 668                 #       $commentedSql = $sql;
 669                 # }
 670
 671                 # If DBO_TRX is set, start a transaction
 672                 if ( ( $this->mFlags & DBO_TRX ) && !$this->trxLevel() &&
 673                         $sql != 'BEGIN' && $sql != 'COMMIT' && $sql != 'ROLLBACK' ) {
 674                         // avoid establishing transactions for SHOW and SET statements too -
 675                         // that would delay transaction initializations to once connection
 676                         // is really used by application
 677                         $sqlstart = substr( $sql, 0, 10 ); // very much worth it, benchmark certified(tm)
 678                         if ( strpos( $sqlstart, "SHOW " ) !== 0 and strpos( $sqlstart, "SET " ) !== 0 )
 679                                 $this->begin();
 680                 }
 681
 682                 if ( $this->debug() ) {
 683                         static $cnt = 0;
 684
 685                         $cnt++;
 686                         $sqlx = substr( $commentedSql, 0, 500 );
 687                         $sqlx = strtr( $sqlx, "\t\n", '  ' );
 688
 689                         if ( $isMaster ) {
 690                                 wfDebug( "Query $cnt (master): $sqlx\n" );
 691                         } else {
 692                                 wfDebug( "Query $cnt (slave): $sqlx\n" );
 693                         }
 694                 }
 695
 696                 if ( istainted( $sql ) & TC_MYSQL ) {
 697                         throw new MWException( 'Tainted query found' );
 698                 }
 699
 700                 # Do the query and handle errors
 701                 $ret = $this->doQuery( $commentedSql );
 702
 703                 # Try reconnecting if the connection was lost
 704                 if ( false === $ret && $this->wasErrorReissuable() ) {
 705                         # Transaction is gone, like it or not
 706                         $this->mTrxLevel = 0;
 707                         wfDebug( "Connection lost, reconnecting...\n" );
 708
 709                         if ( $this->ping() ) {
 710                                 wfDebug( "Reconnected\n" );
 711                                 $sqlx = substr( $commentedSql, 0, 500 );
 712                                 $sqlx = strtr( $sqlx, "\t\n", '  ' );
 713                                 global $wgRequestTime;
 714                                 $elapsed = round( microtime( true ) - $wgRequestTime, 3 );
 715                                 wfLogDBError( "Connection lost and reconnected after {$elapsed}s, query: $sqlx\n" );
 716                                 $ret = $this->doQuery( $commentedSql );
 717                         } else {
 718                                 wfDebug( "Failed\n" );
 719                         }
 720                 }
 721
 722                 if ( false === $ret ) {
 723                         $this->reportQueryError( $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 724                 }
 725
 726                 if ( isset( $wgProfiler ) ) {
 727                         wfProfileOut( $queryProf );
 728                         wfProfileOut( $totalProf );
 729                 }
 730
 731                 return $this->resultObject( $ret );
 732         }
 733
 734         /**
 735          * @param $error String
 736          * @param $errno Integer
 737          * @param $sql String
 738          * @param $fname String
 739          * @param $tempIgnore Boolean
 740          */
 741         function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 742                 # Ignore errors during error handling to avoid infinite recursion
 743                 $ignore = $this->ignoreErrors( true );
 744                 ++$this->mErrorCount;
 745
 746                 if ( $ignore || $tempIgnore ) {
 747                         wfDebug( "SQL ERROR (ignored): $error\n" );
 748                         $this->ignoreErrors( $ignore );
 749                 } else {
 750                         $sql1line = str_replace( "\n", "\\n", $sql );
 751                         wfLogDBError( "$fname\t{$this->mServer}\t$errno\t$error\t$sql1line\n" );
 752                         wfDebug( "SQL ERROR: " . $error . "\n" );
 753                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
 754                 }
 755         }
 756
 757
 758         /**
 759          * Intended to be compatible with the PEAR::DB wrapper functions.
 760          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
 761          *
 762          * ? = scalar value, quoted as necessary
 763          * ! = raw SQL bit (a function for instance)
 764          * & = filename; reads the file and inserts as a blob
 765          *         (we don't use this though...)
 766          */
 767         function prepare( $sql, $func = 'DatabaseBase::prepare' ) {
 768                 /* MySQL doesn't support prepared statements (yet), so just
 769                    pack up the query for reference. We'll manually replace
 770                    the bits later. */
 771                 return array( 'query' => $sql, 'func' => $func );
 772         }
 773
 774         function freePrepared( $prepared ) {
 775                 /* No-op by default */
 776         }
 777
 778         /**
 779          * Execute a prepared query with the various arguments
 780          * @param $prepared String: the prepared sql
 781          * @param $args Mixed: Either an array here, or put scalars as varargs
 782          */
 783         function execute( $prepared, $args = null ) {
 784                 if ( !is_array( $args ) ) {
 785                         # Pull the var args
 786                         $args = func_get_args();
 787                         array_shift( $args );
 788                 }
 789
 790                 $sql = $this->fillPrepared( $prepared['query'], $args );
 791
 792                 return $this->query( $sql, $prepared['func'] );
 793         }
 794
 795         /**
 796          * Prepare & execute an SQL statement, quoting and inserting arguments
 797          * in the appropriate places.
 798          * @param $query String
 799          * @param $args ...
 800          */
 801         function safeQuery( $query, $args = null ) {
 802                 $prepared = $this->prepare( $query, 'DatabaseBase::safeQuery' );
 803
 804                 if ( !is_array( $args ) ) {
 805                         # Pull the var args
 806                         $args = func_get_args();
 807                         array_shift( $args );
 808                 }
 809
 810                 $retval = $this->execute( $prepared, $args );
 811                 $this->freePrepared( $prepared );
 812
 813                 return $retval;
 814         }
 815
 816         /**
 817          * For faking prepared SQL statements on DBs that don't support
 818          * it directly.
 819          * @param $preparedQuery String: a 'preparable' SQL statement
 820          * @param $args Array of arguments to fill it with
 821          * @return string executable SQL
 822          */
 823         function fillPrepared( $preparedQuery, $args ) {
 824                 reset( $args );
 825                 $this->preparedArgs =& $args;
 826
 827                 return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
 828                         array( &$this, 'fillPreparedArg' ), $preparedQuery );
 829         }
 830
 831         /**
 832          * preg_callback func for fillPrepared()
 833          * The arguments should be in $this->preparedArgs and must not be touched
 834          * while we're doing this.
 835          *
 836          * @param $matches Array
 837          * @return String
 838          * @private
 839          */
 840         function fillPreparedArg( $matches ) {
 841                 switch( $matches[1] ) {
 842                         case '\\?': return '?';
 843                         case '\\!': return '!';
 844                         case '\\&': return '&';
 845                 }
 846
 847                 list( /* $n */ , $arg ) = each( $this->preparedArgs );
 848
 849                 switch( $matches[1] ) {
 850                         case '?': return $this->addQuotes( $arg );
 851                         case '!': return $arg;
 852                         case '&':
 853                                 # return $this->addQuotes( file_get_contents( $arg ) );
 854                                 throw new DBUnexpectedError( $this, '& mode is not implemented. If it\'s really needed, uncomment the line above.' );
 855                         default:
 856                                 throw new DBUnexpectedError( $this, 'Received invalid match. This should never happen!' );
 857                 }
 858         }
 859
 860         /**
 861          * Free a result object
 862          * @param $res Mixed: A SQL result
 863          */
 864         function freeResult( $res ) {
 865                 # Stub.  Might not really need to be overridden, since results should
 866                 # be freed by PHP when the variable goes out of scope anyway.
 867         }
 868
 869         /**
 870          * Simple UPDATE wrapper
 871          * Usually aborts on failure
 872          * If errors are explicitly ignored, returns success
 873          *
 874          * This function exists for historical reasons, DatabaseBase::update() has a more standard
 875          * calling convention and feature set
 876          */
 877         function set( $table, $var, $value, $cond, $fname = 'DatabaseBase::set' ) {
 878                 $table = $this->tableName( $table );
 879                 $sql = "UPDATE $table SET $var = '" .
 880                   $this->strencode( $value ) . "' WHERE ($cond)";
 881
 882                 return (bool)$this->query( $sql, $fname );
 883         }
 884
 885         /**
 886          * Simple SELECT wrapper, returns a single field, input must be encoded
 887          * Usually aborts on failure
 888          * If errors are explicitly ignored, returns FALSE on failure
 889          */
 890         function selectField( $table, $var, $cond = '', $fname = 'DatabaseBase::selectField', $options = array() ) {
 891                 if ( !is_array( $options ) ) {
 892                         $options = array( $options );
 893                 }
 894
 895                 $options['LIMIT'] = 1;
 896
 897                 $res = $this->select( $table, $var, $cond, $fname, $options );
 898
 899                 if ( $res === false || !$this->numRows( $res ) ) {
 900                         return false;
 901                 }
 902
 903                 $row = $this->fetchRow( $res );
 904
 905                 if ( $row !== false ) {
 906                         return reset( $row );
 907                 } else {
 908                         return false;
 909                 }
 910         }
 911
 912         /**
 913          * Returns an optional USE INDEX clause to go after the table, and a
 914          * string to go at the end of the query
 915          *
 916          * @private
 917          *
 918          * @param $options Array: associative array of options to be turned into
 919          *                              an SQL query, valid keys are listed in the function.
 920          * @return Array
 921          */
 922         function makeSelectOptions( $options ) {
 923                 $preLimitTail = $postLimitTail = '';
 924                 $startOpts = '';
 925
 926                 $noKeyOptions = array();
 927
 928                 foreach ( $options as $key => $option ) {
 929                         if ( is_numeric( $key ) ) {
 930                                 $noKeyOptions[$option] = true;
 931                         }
 932                 }
 933
 934                 if ( isset( $options['GROUP BY'] ) ) {
 935                         $preLimitTail .= " GROUP BY {$options['GROUP BY']}";
 936                 }
 937
 938                 if ( isset( $options['HAVING'] ) ) {
 939                         $preLimitTail .= " HAVING {$options['HAVING']}";
 940                 }
 941
 942                 if ( isset( $options['ORDER BY'] ) ) {
 943                         $preLimitTail .= " ORDER BY {$options['ORDER BY']}";
 944                 }
 945
 946                 // if (isset($options['LIMIT'])) {
 947                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
 948                 //              isset($options['OFFSET']) ? $options['OFFSET']
 949                 //              : false);
 950                 // }
 951
 952                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
 953                         $postLimitTail .= ' FOR UPDATE';
 954                 }
 955
 956                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
 957                         $postLimitTail .= ' LOCK IN SHARE MODE';
 958                 }
 959
 960                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
 961                         $startOpts .= 'DISTINCT';
 962                 }
 963
 964                 # Various MySQL extensions
 965                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
 966                         $startOpts .= ' /*! STRAIGHT_JOIN */';
 967                 }
 968
 969                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
 970                         $startOpts .= ' HIGH_PRIORITY';
 971                 }
 972
 973                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
 974                         $startOpts .= ' SQL_BIG_RESULT';
 975                 }
 976
 977                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
 978                         $startOpts .= ' SQL_BUFFER_RESULT';
 979                 }
 980
 981                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
 982                         $startOpts .= ' SQL_SMALL_RESULT';
 983                 }
 984
 985                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
 986                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
 987                 }
 988
 989                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
 990                         $startOpts .= ' SQL_CACHE';
 991                 }
 992
 993                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
 994                         $startOpts .= ' SQL_NO_CACHE';
 995                 }
 996
 997                 if ( isset( $options['USE INDEX'] ) && ! is_array( $options['USE INDEX'] ) ) {
 998                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
 999                 } else {
1000                         $useIndex = '';
1001                 }
1002
1003                 return array( $startOpts, $useIndex, $preLimitTail, $postLimitTail );
1004         }
1005
1006         /**
1007          * SELECT wrapper
1008          *
1009          * @param $table   Mixed:  Array or string, table name(s) (prefix auto-added)
1010          * @param $vars    Mixed:  Array or string, field name(s) to be retrieved
1011          * @param $conds   Mixed:  Array or string, condition(s) for WHERE
1012          * @param $fname   String: Calling function name (use __METHOD__) for logs/profiling
1013          * @param $options Array:  Associative array of options (e.g. array('GROUP BY' => 'page_title')),
1014          *                                                 see DatabaseBase::makeSelectOptions code for list of supported stuff
1015          * @param $join_conds Array: Associative array of table join conditions (optional)
1016          *                                                       (e.g. array( 'page' => array('LEFT JOIN','page_latest=rev_id') )
1017          * @return mixed Database result resource (feed to DatabaseBase::fetchObject or whatever), or false on failure
1018          */
1019         function select( $table, $vars, $conds = '', $fname = 'DatabaseBase::select', $options = array(), $join_conds = array() ) {
1020                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1021
1022                 return $this->query( $sql, $fname );
1023         }
1024
1025         /**
1026          * SELECT wrapper
1027          *
1028          * @param $table   Mixed:  Array or string, table name(s) (prefix auto-added)
1029          * @param $vars    Mixed:  Array or string, field name(s) to be retrieved
1030          * @param $conds   Mixed:  Array or string, condition(s) for WHERE
1031          * @param $fname   String: Calling function name (use __METHOD__) for logs/profiling
1032          * @param $options Array:  Associative array of options (e.g. array('GROUP BY' => 'page_title')),
1033          *                                                 see DatabaseBase::makeSelectOptions code for list of supported stuff
1034          * @param $join_conds Array: Associative array of table join conditions (optional)
1035          *                                                       (e.g. array( 'page' => array('LEFT JOIN','page_latest=rev_id') )
1036          * @return string, the SQL text
1037          */
1038         function selectSQLText( $table, $vars, $conds = '', $fname = 'DatabaseBase::select', $options = array(), $join_conds = array() ) {
1039                 if ( is_array( $vars ) ) {
1040                         $vars = implode( ',', $vars );
1041                 }
1042
1043                 if ( !is_array( $options ) ) {
1044                         $options = array( $options );
1045                 }
1046
1047                 if ( is_array( $table ) ) {
1048                         if ( !empty( $join_conds ) || ( isset( $options['USE INDEX'] ) && is_array( @$options['USE INDEX'] ) ) ) {
1049                                 $from = ' FROM ' . $this->tableNamesWithUseIndexOrJOIN( $table, @$options['USE INDEX'], $join_conds );
1050                         } else {
1051                                 $from = ' FROM ' . implode( ',', array_map( array( &$this, 'tableName' ), $table ) );
1052                         }
1053                 } elseif ( $table != '' ) {
1054                         if ( $table { 0 } == ' ' ) {
1055                                 $from = ' FROM ' . $table;
1056                         } else {
1057                                 $from = ' FROM ' . $this->tableName( $table );
1058                         }
1059                 } else {
1060                         $from = '';
1061                 }
1062
1063                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail ) = $this->makeSelectOptions( $options );
1064
1065                 if ( !empty( $conds ) ) {
1066                         if ( is_array( $conds ) ) {
1067                                 $conds = $this->makeList( $conds, LIST_AND );
1068                         }
1069                         $sql = "SELECT $startOpts $vars $from $useIndex WHERE $conds $preLimitTail";
1070                 } else {
1071                         $sql = "SELECT $startOpts $vars $from $useIndex $preLimitTail";
1072                 }
1073
1074                 if ( isset( $options['LIMIT'] ) )
1075                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1076                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1077                 $sql = "$sql $postLimitTail";
1078
1079                 if ( isset( $options['EXPLAIN'] ) ) {
1080                         $sql = 'EXPLAIN ' . $sql;
1081                 }
1082
1083                 return $sql;
1084         }
1085
1086         /**
1087          * Single row SELECT wrapper
1088          * Aborts or returns FALSE on error
1089          *
1090          * @param $table String: table name
1091          * @param $vars String: the selected variables
1092          * @param $conds Array: a condition map, terms are ANDed together.
1093          *       Items with numeric keys are taken to be literal conditions
1094          * Takes an array of selected variables, and a condition map, which is ANDed
1095          * e.g: selectRow( "page", array( "page_id" ), array( "page_namespace" =>
1096          * NS_MAIN, "page_title" => "Astronomy" ) )       would return an object where
1097          * $obj- >page_id is the ID of the Astronomy article
1098          * @param $fname String: Calling function name
1099          * @param $options Array
1100          * @param $join_conds Array
1101          *
1102          * @todo migrate documentation to phpdocumentor format
1103          */
1104         function selectRow( $table, $vars, $conds, $fname = 'DatabaseBase::selectRow', $options = array(), $join_conds = array() ) {
1105                 $options['LIMIT'] = 1;
1106                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1107
1108                 if ( $res === false ) {
1109                         return false;
1110                 }
1111
1112                 if ( !$this->numRows( $res ) ) {
1113                         return false;
1114                 }
1115
1116                 $obj = $this->fetchObject( $res );
1117
1118                 return $obj;
1119         }
1120
1121         /**
1122          * Estimate rows in dataset
1123          * Returns estimated count - not necessarily an accurate estimate across different databases,
1124          * so use sparingly
1125          * Takes same arguments as DatabaseBase::select()
1126          *
1127          * @param $table String: table name
1128          * @param $vars Array: unused
1129          * @param $conds Array: filters on the table
1130          * @param $fname String: function name for profiling
1131          * @param $options Array: options for select
1132          * @return Integer: row count
1133          */
1134         public function estimateRowCount( $table, $vars = '*', $conds = '', $fname = 'DatabaseBase::estimateRowCount', $options = array() ) {
1135                 $rows = 0;
1136                 $res = $this->select ( $table, 'COUNT(*) AS rowcount', $conds, $fname, $options );
1137
1138                 if ( $res ) {
1139                         $row = $this->fetchRow( $res );
1140                         $rows = ( isset( $row['rowcount'] ) ) ? $row['rowcount'] : 0;
1141                 }
1142
1143                 return $rows;
1144         }
1145
1146         /**
1147          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1148          * It's only slightly flawed. Don't use for anything important.
1149          *
1150          * @param $sql String: A SQL Query
1151          */
1152         static function generalizeSQL( $sql ) {
1153                 # This does the same as the regexp below would do, but in such a way
1154                 # as to avoid crashing php on some large strings.
1155                 # $sql = preg_replace ( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql);
1156
1157                 $sql = str_replace ( "\\\\", '', $sql );
1158                 $sql = str_replace ( "\\'", '', $sql );
1159                 $sql = str_replace ( "\\\"", '', $sql );
1160                 $sql = preg_replace ( "/'.*'/s", "'X'", $sql );
1161                 $sql = preg_replace ( '/".*"/s', "'X'", $sql );
1162
1163                 # All newlines, tabs, etc replaced by single space
1164                 $sql = preg_replace ( '/\s+/', ' ', $sql );
1165
1166                 # All numbers => N
1167                 $sql = preg_replace ( '/-?[0-9]+/s', 'N', $sql );
1168
1169                 return $sql;
1170         }
1171
1172         /**
1173          * Determines whether a field exists in a table
1174          *
1175          * @param $table String: table name
1176          * @param $field String: filed to check on that table
1177          * @param $fname String: calling function name (optional)
1178          * @return Boolean: whether $table has filed $field
1179          */
1180         function fieldExists( $table, $field, $fname = 'DatabaseBase::fieldExists' ) {
1181                 $info = $this->fieldInfo( $table, $field );
1182
1183                 return (bool)$info;
1184         }
1185
1186         /**
1187          * Determines whether an index exists
1188          * Usually aborts on failure
1189          * If errors are explicitly ignored, returns NULL on failure
1190          */
1191         function indexExists( $table, $index, $fname = 'DatabaseBase::indexExists' ) {
1192                 $info = $this->indexInfo( $table, $index, $fname );
1193                 if ( is_null( $info ) ) {
1194                         return null;
1195                 } else {
1196                         return $info !== false;
1197                 }
1198         }
1199
1200
1201         /**
1202          * Get information about an index into an object
1203          * Returns false if the index does not exist
1204          */
1205         function indexInfo( $table, $index, $fname = 'DatabaseBase::indexInfo' ) {
1206                 # SHOW INDEX works in MySQL 3.23.58, but SHOW INDEXES does not.
1207                 # SHOW INDEX should work for 3.x and up:
1208                 # http://dev.mysql.com/doc/mysql/en/SHOW_INDEX.html
1209                 $table = $this->tableName( $table );
1210                 $index = $this->indexName( $index );
1211                 $sql = 'SHOW INDEX FROM ' . $table;
1212                 $res = $this->query( $sql, $fname );
1213
1214                 if ( !$res ) {
1215                         return null;
1216                 }
1217
1218                 $result = array();
1219
1220                 while ( $row = $this->fetchObject( $res ) ) {
1221                         if ( $row->Key_name == $index ) {
1222                                 $result[] = $row;
1223                         }
1224                 }
1225
1226                 return empty( $result ) ? false : $result;
1227         }
1228
1229         /**
1230          * Query whether a given table exists
1231          */
1232         function tableExists( $table ) {
1233                 $table = $this->tableName( $table );
1234                 $old = $this->ignoreErrors( true );
1235                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", __METHOD__ );
1236                 $this->ignoreErrors( $old );
1237
1238                 return (bool)$res;
1239         }
1240
1241         /**
1242          * mysql_field_type() wrapper
1243          */
1244         function fieldType( $res, $index ) {
1245                 if ( $res instanceof ResultWrapper ) {
1246                         $res = $res->result;
1247                 }
1248
1249                 return mysql_field_type( $res, $index );
1250         }
1251
1252         /**
1253          * Determines if a given index is unique
1254          */
1255         function indexUnique( $table, $index ) {
1256                 $indexInfo = $this->indexInfo( $table, $index );
1257
1258                 if ( !$indexInfo ) {
1259                         return null;
1260                 }
1261
1262                 return !$indexInfo[0]->Non_unique;
1263         }
1264
1265         /**
1266          * INSERT wrapper, inserts an array into a table
1267          *
1268          * $a may be a single associative array, or an array of these with numeric keys, for
1269          * multi-row insert.
1270          *
1271          * Usually aborts on failure
1272          * If errors are explicitly ignored, returns success
1273          *
1274          * @param $table   String: table name (prefix auto-added)
1275          * @param $a       Array: Array of rows to insert
1276          * @param $fname   String: Calling function name (use __METHOD__) for logs/profiling
1277          * @param $options Mixed: Associative array of options
1278          *
1279          * @return bool
1280          */
1281         function insert( $table, $a, $fname = 'DatabaseBase::insert', $options = array() ) {
1282                 # No rows to insert, easy just return now
1283                 if ( !count( $a ) ) {
1284                         return true;
1285                 }
1286
1287                 $table = $this->tableName( $table );
1288
1289                 if ( !is_array( $options ) ) {
1290                         $options = array( $options );
1291                 }
1292
1293                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1294                         $multi = true;
1295                         $keys = array_keys( $a[0] );
1296                 } else {
1297                         $multi = false;
1298                         $keys = array_keys( $a );
1299                 }
1300
1301                 $sql = 'INSERT ' . implode( ' ', $options ) .
1302                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1303
1304                 if ( $multi ) {
1305                         $first = true;
1306                         foreach ( $a as $row ) {
1307                                 if ( $first ) {
1308                                         $first = false;
1309                                 } else {
1310                                         $sql .= ',';
1311                                 }
1312                                 $sql .= '(' . $this->makeList( $row ) . ')';
1313                         }
1314                 } else {
1315                         $sql .= '(' . $this->makeList( $a ) . ')';
1316                 }
1317
1318                 return (bool)$this->query( $sql, $fname );
1319         }
1320
1321         /**
1322          * Make UPDATE options for the DatabaseBase::update function
1323          *
1324          * @private
1325          * @param $options Array: The options passed to DatabaseBase::update
1326          * @return string
1327          */
1328         function makeUpdateOptions( $options ) {
1329                 if ( !is_array( $options ) ) {
1330                         $options = array( $options );
1331                 }
1332
1333                 $opts = array();
1334
1335                 if ( in_array( 'LOW_PRIORITY', $options ) ) {
1336                         $opts[] = $this->lowPriorityOption();
1337                 }
1338
1339                 if ( in_array( 'IGNORE', $options ) ) {
1340                         $opts[] = 'IGNORE';
1341                 }
1342
1343                 return implode( ' ', $opts );
1344         }
1345
1346         /**
1347          * UPDATE wrapper, takes a condition array and a SET array
1348          *
1349          * @param $table  String: The table to UPDATE
1350          * @param $values Array:  An array of values to SET
1351          * @param $conds  Array:  An array of conditions (WHERE). Use '*' to update all rows.
1352          * @param $fname  String: The Class::Function calling this function
1353          *                                                (for the log)
1354          * @param $options Array: An array of UPDATE options, can be one or
1355          *                                                more of IGNORE, LOW_PRIORITY
1356          * @return Boolean
1357          */
1358         function update( $table, $values, $conds, $fname = 'DatabaseBase::update', $options = array() ) {
1359                 $table = $this->tableName( $table );
1360                 $opts = $this->makeUpdateOptions( $options );
1361                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1362
1363                 if ( $conds != '*' ) {
1364                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1365                 }
1366
1367                 return $this->query( $sql, $fname );
1368         }
1369
1370         /**
1371          * Makes an encoded list of strings from an array
1372          * $mode:
1373          *                LIST_COMMA             - comma separated, no field names
1374          *                LIST_AND                       - ANDed WHERE clause (without the WHERE)
1375          *                LIST_OR                        - ORed WHERE clause (without the WHERE)
1376          *                LIST_SET                       - comma separated with field names, like a SET clause
1377          *                LIST_NAMES             - comma separated field names
1378          */
1379         function makeList( $a, $mode = LIST_COMMA ) {
1380                 if ( !is_array( $a ) ) {
1381                         throw new DBUnexpectedError( $this, 'DatabaseBase::makeList called with incorrect parameters' );
1382                 }
1383
1384                 $first = true;
1385                 $list = '';
1386
1387                 foreach ( $a as $field => $value ) {
1388                         if ( !$first ) {
1389                                 if ( $mode == LIST_AND ) {
1390                                         $list .= ' AND ';
1391                                 } elseif ( $mode == LIST_OR ) {
1392                                         $list .= ' OR ';
1393                                 } else {
1394                                         $list .= ',';
1395                                 }
1396                         } else {
1397                                 $first = false;
1398                         }
1399
1400                         if ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_numeric( $field ) ) {
1401                                 $list .= "($value)";
1402                         } elseif ( ( $mode == LIST_SET ) && is_numeric( $field ) ) {
1403                                 $list .= "$value";
1404                         } elseif ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_array( $value ) ) {
1405                                 if ( count( $value ) == 0 ) {
1406                                         throw new MWException( __METHOD__ . ': empty input' );
1407                                 } elseif ( count( $value ) == 1 ) {
1408                                         // Special-case single values, as IN isn't terribly efficient
1409                                         // Don't necessarily assume the single key is 0; we don't
1410                                         // enforce linear numeric ordering on other arrays here.
1411                                         $value = array_values( $value );
1412                                         $list .= $field . " = " . $this->addQuotes( $value[0] );
1413                                 } else {
1414                                         $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1415                                 }
1416                         } elseif ( $value === null ) {
1417                                 if ( $mode == LIST_AND || $mode == LIST_OR ) {
1418                                         $list .= "$field IS ";
1419                                 } elseif ( $mode == LIST_SET ) {
1420                                         $list .= "$field = ";
1421                                 }
1422                                 $list .= 'NULL';
1423                         } else {
1424                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
1425                                         $list .= "$field = ";
1426                                 }
1427                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
1428                         }
1429                 }
1430
1431                 return $list;
1432         }
1433
1434         /**
1435          * Build a partial where clause from a 2-d array such as used for LinkBatch.
1436          * The keys on each level may be either integers or strings.
1437          *
1438          * @param $data Array: organized as 2-d array(baseKeyVal => array(subKeyVal => <ignored>, ...), ...)
1439          * @param $baseKey String: field name to match the base-level keys to (eg 'pl_namespace')
1440          * @param $subKey String: field name to match the sub-level keys to (eg 'pl_title')
1441          * @return Mixed: string SQL fragment, or false if no items in array.
1442          */
1443         function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1444                 $conds = array();
1445
1446                 foreach ( $data as $base => $sub ) {
1447                         if ( count( $sub ) ) {
1448                                 $conds[] = $this->makeList(
1449                                         array( $baseKey => $base, $subKey => array_keys( $sub ) ),
1450                                         LIST_AND );
1451                         }
1452                 }
1453
1454                 if ( $conds ) {
1455                         return $this->makeList( $conds, LIST_OR );
1456                 } else {
1457                         // Nothing to search for...
1458                         return false;
1459                 }
1460         }
1461
1462         /**
1463          * Bitwise operations
1464          */
1465
1466         function bitNot( $field ) {
1467                 return "(~$field)";
1468         }
1469
1470         function bitAnd( $fieldLeft, $fieldRight ) {
1471                 return "($fieldLeft & $fieldRight)";
1472         }
1473
1474         function bitOr( $fieldLeft, $fieldRight ) {
1475                 return "($fieldLeft | $fieldRight)";
1476         }
1477
1478         /**
1479          * Change the current database
1480          *
1481          * @todo Explain what exactly will fail if this is not overridden.
1482          * @return bool Success or failure
1483          */
1484         function selectDB( $db ) {
1485                 # Stub.  Shouldn't cause serious problems if it's not overridden, but
1486                 # if your database engine supports a concept similar to MySQL's
1487                 # databases you may as well.
1488                 return true;
1489         }
1490
1491         /**
1492          * Get the current DB name
1493          */
1494         function getDBname() {
1495                 return $this->mDBname;
1496         }
1497
1498         /**
1499          * Get the server hostname or IP address
1500          */
1501         function getServer() {
1502                 return $this->mServer;
1503         }
1504
1505         /**
1506          * Format a table name ready for use in constructing an SQL query
1507          *
1508          * This does two important things: it quotes the table names to clean them up,
1509          * and it adds a table prefix if only given a table name with no quotes.
1510          *
1511          * All functions of this object which require a table name call this function
1512          * themselves. Pass the canonical name to such functions. This is only needed
1513          * when calling query() directly.
1514          *
1515          * @param $name String: database table name
1516          * @return String: full database name
1517          */
1518         function tableName( $name ) {
1519                 global $wgSharedDB, $wgSharedPrefix, $wgSharedTables;
1520                 # Skip the entire process when we have a string quoted on both ends.
1521                 # Note that we check the end so that we will still quote any use of
1522                 # use of `database`.table. But won't break things if someone wants
1523                 # to query a database table with a dot in the name.
1524                 if ( $name[0] == '`' && substr( $name, -1, 1 ) == '`' ) {
1525                         return $name;
1526                 }
1527
1528                 # Lets test for any bits of text that should never show up in a table
1529                 # name. Basically anything like JOIN or ON which are actually part of
1530                 # SQL queries, but may end up inside of the table value to combine
1531                 # sql. Such as how the API is doing.
1532                 # Note that we use a whitespace test rather than a \b test to avoid
1533                 # any remote case where a word like on may be inside of a table name
1534                 # surrounded by symbols which may be considered word breaks.
1535                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1536                         return $name;
1537                 }
1538
1539                 # Split database and table into proper variables.
1540                 # We reverse the explode so that database.table and table both output
1541                 # the correct table.
1542                 $dbDetails = array_reverse( explode( '.', $name, 2 ) );
1543                 if ( isset( $dbDetails[1] ) ) {
1544                         @list( $table, $database ) = $dbDetails;
1545                 } else {
1546                         @list( $table ) = $dbDetails;
1547                 }
1548                 $prefix = $this->mTablePrefix; # Default prefix
1549
1550                 # A database name has been specified in input. Quote the table name
1551                 # because we don't want any prefixes added.
1552                 if ( isset( $database ) ) {
1553                         $table = ( $table[0] == '`' ? $table : "`{$table}`" );
1554                 }
1555
1556                 # Note that we use the long format because php will complain in in_array if
1557                 # the input is not an array, and will complain in is_array if it is not set.
1558                 if ( !isset( $database ) # Don't use shared database if pre selected.
1559                  && isset( $wgSharedDB ) # We have a shared database
1560                  && $table[0] != '`' # Paranoia check to prevent shared tables listing '`table`'
1561                  && isset( $wgSharedTables )
1562                  && is_array( $wgSharedTables )
1563                  && in_array( $table, $wgSharedTables ) ) { # A shared table is selected
1564                         $database = $wgSharedDB;
1565                         $prefix   = isset( $wgSharedPrefix ) ? $wgSharedPrefix : $prefix;
1566                 }
1567
1568                 # Quote the $database and $table and apply the prefix if not quoted.
1569                 if ( isset( $database ) ) {
1570                         $database = ( $database[0] == '`' ? $database : "`{$database}`" );
1571                 }
1572                 $table = ( $table[0] == '`' ? $table : "`{$prefix}{$table}`" );
1573
1574                 # Merge our database and table into our final table name.
1575                 $tableName = ( isset( $database ) ? "{$database}.{$table}" : "{$table}" );
1576
1577                 return $tableName;
1578         }
1579
1580         /**
1581          * Fetch a number of table names into an array
1582          * This is handy when you need to construct SQL for joins
1583          *
1584          * Example:
1585          * extract($dbr->tableNames('user','watchlist'));
1586          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1587          *                 WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1588          */
1589         public function tableNames() {
1590                 $inArray = func_get_args();
1591                 $retVal = array();
1592
1593                 foreach ( $inArray as $name ) {
1594                         $retVal[$name] = $this->tableName( $name );
1595                 }
1596
1597                 return $retVal;
1598         }
1599
1600         /**
1601          * Fetch a number of table names into an zero-indexed numerical array
1602          * This is handy when you need to construct SQL for joins
1603          *
1604          * Example:
1605          * list( $user, $watchlist ) = $dbr->tableNamesN('user','watchlist');
1606          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1607          *                 WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1608          */
1609         public function tableNamesN() {
1610                 $inArray = func_get_args();
1611                 $retVal = array();
1612
1613                 foreach ( $inArray as $name ) {
1614                         $retVal[] = $this->tableName( $name );
1615                 }
1616
1617                 return $retVal;
1618         }
1619
1620         /**
1621          * @private
1622          */
1623         function tableNamesWithUseIndexOrJOIN( $tables, $use_index = array(), $join_conds = array() ) {
1624                 $ret = array();
1625                 $retJOIN = array();
1626                 $use_index_safe = is_array( $use_index ) ? $use_index : array();
1627                 $join_conds_safe = is_array( $join_conds ) ? $join_conds : array();
1628
1629                 foreach ( $tables as $table ) {
1630                         // Is there a JOIN and INDEX clause for this table?
1631                         if ( isset( $join_conds_safe[$table] ) && isset( $use_index_safe[$table] ) ) {
1632                                 $tableClause = $join_conds_safe[$table][0] . ' ' . $this->tableName( $table );
1633                                 $tableClause .= ' ' . $this->useIndexClause( implode( ',', (array)$use_index_safe[$table] ) );
1634                                 $on = $this->makeList( (array)$join_conds_safe[$table][1], LIST_AND );
1635
1636                                 if ( $on != '' ) {
1637                                         $tableClause .= ' ON (' . $on . ')';
1638                                 }
1639
1640                                 $retJOIN[] = $tableClause;
1641                         // Is there an INDEX clause?
1642                         } else if ( isset( $use_index_safe[$table] ) ) {
1643                                 $tableClause = $this->tableName( $table );
1644                                 $tableClause .= ' ' . $this->useIndexClause( implode( ',', (array)$use_index_safe[$table] ) );
1645                                 $ret[] = $tableClause;
1646                         // Is there a JOIN clause?
1647                         } else if ( isset( $join_conds_safe[$table] ) ) {
1648                                 $tableClause = $join_conds_safe[$table][0] . ' ' . $this->tableName( $table );
1649                                 $on = $this->makeList( (array)$join_conds_safe[$table][1], LIST_AND );
1650
1651                                 if ( $on != '' ) {
1652                                         $tableClause .= ' ON (' . $on . ')';
1653                                 }
1654
1655                                 $retJOIN[] = $tableClause;
1656                         } else {
1657                                 $tableClause = $this->tableName( $table );
1658                                 $ret[] = $tableClause;
1659                         }
1660                 }
1661
1662                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
1663                 $straightJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
1664                 $otherJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
1665
1666                 // Compile our final table clause
1667                 return implode( ' ', array( $straightJoins, $otherJoins ) );
1668         }
1669
1670         /**
1671          * Get the name of an index in a given table
1672          */
1673         function indexName( $index ) {
1674                 // Backwards-compatibility hack
1675                 $renamed = array(
1676                         'ar_usertext_timestamp' => 'usertext_timestamp',
1677                         'un_user_id'            => 'user_id',
1678                         'un_user_ip'            => 'user_ip',
1679                 );
1680
1681                 if ( isset( $renamed[$index] ) ) {
1682                         return $renamed[$index];
1683                 } else {
1684                         return $index;
1685                 }
1686         }
1687
1688         /**
1689          * If it's a string, adds quotes and backslashes
1690          * Otherwise returns as-is
1691          */
1692         function addQuotes( $s ) {
1693                 if ( $s === null ) {
1694                         return 'NULL';
1695                 } else {
1696                         # This will also quote numeric values. This should be harmless,
1697                         # and protects against weird problems that occur when they really
1698                         # _are_ strings such as article titles and string->number->string
1699                         # conversion is not 1:1.
1700                         return "'" . $this->strencode( $s ) . "'";
1701                 }
1702         }
1703
1704         /**
1705          * Escape string for safe LIKE usage.
1706          * WARNING: you should almost never use this function directly,
1707          * instead use buildLike() that escapes everything automatically
1708          * Deprecated in 1.17, warnings in 1.17, removed in ???
1709          */
1710         public function escapeLike( $s ) {
1711                 wfDeprecated( __METHOD__ );
1712                 return $this->escapeLikeInternal( $s );
1713         }
1714
1715         protected function escapeLikeInternal( $s ) {
1716                 $s = str_replace( '\\', '\\\\', $s );
1717                 $s = $this->strencode( $s );
1718                 $s = str_replace( array( '%', '_' ), array( '\%', '\_' ), $s );
1719
1720                 return $s;
1721         }
1722
1723         /**
1724          * LIKE statement wrapper, receives a variable-length argument list with parts of pattern to match
1725          * containing either string literals that will be escaped or tokens returned by anyChar() or anyString().
1726          * Alternatively, the function could be provided with an array of aforementioned parameters.
1727          *
1728          * Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns a LIKE clause that searches
1729          * for subpages of 'My page title'.
1730          * Alternatively: $pattern = array( 'My_page_title/', $dbr->anyString() ); $query .= $dbr->buildLike( $pattern );
1731          *
1732          * @since 1.16
1733          * @return String: fully built LIKE statement
1734          */
1735         function buildLike() {
1736                 $params = func_get_args();
1737
1738                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
1739                         $params = $params[0];
1740                 }
1741
1742                 $s = '';
1743
1744                 foreach ( $params as $value ) {
1745                         if ( $value instanceof LikeMatch ) {
1746                                 $s .= $value->toString();
1747                         } else {
1748                                 $s .= $this->escapeLikeInternal( $value );
1749                         }
1750                 }
1751
1752                 return " LIKE '" . $s . "' ";
1753         }
1754
1755         /**
1756          * Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
1757          */
1758         function anyChar() {
1759                 return new LikeMatch( '_' );
1760         }
1761
1762         /**
1763          * Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
1764          */
1765         function anyString() {
1766                 return new LikeMatch( '%' );
1767         }
1768
1769         /**
1770          * Returns an appropriately quoted sequence value for inserting a new row.
1771          * MySQL has autoincrement fields, so this is just NULL. But the PostgreSQL
1772          * subclass will return an integer, and save the value for insertId()
1773          */
1774         function nextSequenceValue( $seqName ) {
1775                 return null;
1776         }
1777
1778         /**
1779          * USE INDEX clause.  Unlikely to be useful for anything but MySQL.      This
1780          * is only needed because a) MySQL must be as efficient as possible due to
1781          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
1782          * which index to pick.  Anyway, other databases might have different
1783          * indexes on a given table.  So don't bother overriding this unless you're
1784          * MySQL.
1785          */
1786         function useIndexClause( $index ) {
1787                 return '';
1788         }
1789
1790         /**
1791          * REPLACE query wrapper
1792          * PostgreSQL simulates this with a DELETE followed by INSERT
1793          * $row is the row to insert, an associative array
1794          * $uniqueIndexes is an array of indexes. Each element may be either a
1795          * field name or an array of field names
1796          *
1797          * It may be more efficient to leave off unique indexes which are unlikely to collide.
1798          * However if you do this, you run the risk of encountering errors which wouldn't have
1799          * occurred in MySQL
1800          *
1801          * @param $table String: The table to replace the row(s) in.
1802          * @param $uniqueIndexes Array: An associative array of indexes
1803          * @param $rows Array: Array of rows to replace
1804          * @param $fname String: Calling function name (use __METHOD__) for logs/profiling
1805          */
1806         function replace( $table, $uniqueIndexes, $rows, $fname = 'DatabaseBase::replace' ) {
1807                 $table = $this->tableName( $table );
1808
1809                 # Single row case
1810                 if ( !is_array( reset( $rows ) ) ) {
1811                         $rows = array( $rows );
1812                 }
1813
1814                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
1815                 $first = true;
1816
1817                 foreach ( $rows as $row ) {
1818                         if ( $first ) {
1819                                 $first = false;
1820                         } else {
1821                                 $sql .= ',';
1822                         }
1823
1824                         $sql .= '(' . $this->makeList( $row ) . ')';
1825                 }
1826
1827                 return $this->query( $sql, $fname );
1828         }
1829
1830         /**
1831          * DELETE where the condition is a join
1832          * MySQL does this with a multi-table DELETE syntax, PostgreSQL does it with sub-selects
1833          *
1834          * For safety, an empty $conds will not delete everything. If you want to delete all rows where the
1835          * join condition matches, set $conds='*'
1836          *
1837          * DO NOT put the join condition in $conds
1838          *
1839          * @param $delTable String: The table to delete from.
1840          * @param $joinTable String: The other table.
1841          * @param $delVar String: The variable to join on, in the first table.
1842          * @param $joinVar String: The variable to join on, in the second table.
1843          * @param $conds Array: Condition array of field names mapped to variables, ANDed together in the WHERE clause
1844          * @param $fname String: Calling function name (use __METHOD__) for logs/profiling
1845          */
1846         function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds, $fname = 'DatabaseBase::deleteJoin' ) {
1847                 if ( !$conds ) {
1848                         throw new DBUnexpectedError( $this, 'DatabaseBase::deleteJoin() called with empty $conds' );
1849                 }
1850
1851                 $delTable = $this->tableName( $delTable );
1852                 $joinTable = $this->tableName( $joinTable );
1853                 $sql = "DELETE $delTable FROM $delTable, $joinTable WHERE $delVar=$joinVar ";
1854
1855                 if ( $conds != '*' ) {
1856                         $sql .= ' AND ' . $this->makeList( $conds, LIST_AND );
1857                 }
1858
1859                 return $this->query( $sql, $fname );
1860         }
1861
1862         /**
1863          * Returns the size of a text field, or -1 for "unlimited"
1864          */
1865         function textFieldSize( $table, $field ) {
1866                 $table = $this->tableName( $table );
1867                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
1868                 $res = $this->query( $sql, 'DatabaseBase::textFieldSize' );
1869                 $row = $this->fetchObject( $res );
1870
1871                 $m = array();
1872
1873                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
1874                         $size = $m[1];
1875                 } else {
1876                         $size = -1;
1877                 }
1878
1879                 return $size;
1880         }
1881
1882         /**
1883          * A string to insert into queries to show that they're low-priority, like
1884          * MySQL's LOW_PRIORITY.  If no such feature exists, return an empty
1885          * string and nothing bad should happen.
1886          *
1887          * @return string Returns the text of the low priority option if it is supported, or a blank string otherwise
1888          */
1889         function lowPriorityOption() {
1890                 return '';
1891         }
1892
1893         /**
1894          * DELETE query wrapper
1895          *
1896          * Use $conds == "*" to delete all rows
1897          */
1898         function delete( $table, $conds, $fname = 'DatabaseBase::delete' ) {
1899                 if ( !$conds ) {
1900                         throw new DBUnexpectedError( $this, 'DatabaseBase::delete() called with no conditions' );
1901                 }
1902
1903                 $table = $this->tableName( $table );
1904                 $sql = "DELETE FROM $table";
1905
1906                 if ( $conds != '*' ) {
1907                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1908                 }
1909
1910                 return $this->query( $sql, $fname );
1911         }
1912
1913         /**
1914          * INSERT SELECT wrapper
1915          * $varMap must be an associative array of the form array( 'dest1' => 'source1', ...)
1916          * Source items may be literals rather than field names, but strings should be quoted with DatabaseBase::addQuotes()
1917          * $conds may be "*" to copy the whole table
1918          * srcTable may be an array of tables.
1919          */
1920         function insertSelect( $destTable, $srcTable, $varMap, $conds, $fname = 'DatabaseBase::insertSelect',
1921                 $insertOptions = array(), $selectOptions = array() )
1922         {
1923                 $destTable = $this->tableName( $destTable );
1924
1925                 if ( is_array( $insertOptions ) ) {
1926                         $insertOptions = implode( ' ', $insertOptions );
1927                 }
1928
1929                 if ( !is_array( $selectOptions ) ) {
1930                         $selectOptions = array( $selectOptions );
1931                 }
1932
1933                 list( $startOpts, $useIndex, $tailOpts ) = $this->makeSelectOptions( $selectOptions );
1934
1935                 if ( is_array( $srcTable ) ) {
1936                         $srcTable =      implode( ',', array_map( array( &$this, 'tableName' ), $srcTable ) );
1937                 } else {
1938                         $srcTable = $this->tableName( $srcTable );
1939                 }
1940
1941                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
1942                         " SELECT $startOpts " . implode( ',', $varMap ) .
1943                         " FROM $srcTable $useIndex ";
1944
1945                 if ( $conds != '*' ) {
1946                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1947                 }
1948
1949                 $sql .= " $tailOpts";
1950
1951                 return $this->query( $sql, $fname );
1952         }
1953
1954         /**
1955          * Construct a LIMIT query with optional offset.  This is used for query
1956          * pages.  The SQL should be adjusted so that only the first $limit rows
1957          * are returned.  If $offset is provided as well, then the first $offset
1958          * rows should be discarded, and the next $limit rows should be returned.
1959          * If the result of the query is not ordered, then the rows to be returned
1960          * are theoretically arbitrary.
1961          *
1962          * $sql is expected to be a SELECT, if that makes a difference.  For
1963          * UPDATE, limitResultForUpdate should be used.
1964          *
1965          * The version provided by default works in MySQL and SQLite.  It will very
1966          * likely need to be overridden for most other DBMSes.
1967          *
1968          * @param $sql String: SQL query we will append the limit too
1969          * @param $limit Integer: the SQL limit
1970          * @param $offset Integer the SQL offset (default false)
1971          */
1972         function limitResult( $sql, $limit, $offset = false ) {
1973                 if ( !is_numeric( $limit ) ) {
1974                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
1975                 }
1976
1977                 return "$sql LIMIT "
1978                                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
1979                                 . "{$limit} ";
1980         }
1981
1982         function limitResultForUpdate( $sql, $num ) {
1983                 return $this->limitResult( $sql, $num, 0 );
1984         }
1985
1986         /**
1987          * Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
1988          * within the UNION construct.
1989          * @return Boolean
1990          */
1991         function unionSupportsOrderAndLimit() {
1992                 return true; // True for almost every DB supported
1993         }
1994
1995         /**
1996          * Construct a UNION query
1997          * This is used for providing overload point for other DB abstractions
1998          * not compatible with the MySQL syntax.
1999          * @param $sqls Array: SQL statements to combine
2000          * @param $all Boolean: use UNION ALL
2001          * @return String: SQL fragment
2002          */
2003         function unionQueries( $sqls, $all ) {
2004                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2005                 return '(' . implode( $glue, $sqls ) . ')';
2006         }
2007
2008         /**
2009          * Returns an SQL expression for a simple conditional.  This doesn't need
2010          * to be overridden unless CASE isn't supported in your DBMS.
2011          *
2012          * @param $cond String: SQL expression which will result in a boolean value
2013          * @param $trueVal String: SQL expression to return if true
2014          * @param $falseVal String: SQL expression to return if false
2015          * @return String: SQL fragment
2016          */
2017         function conditional( $cond, $trueVal, $falseVal ) {
2018                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2019         }
2020
2021         /**
2022          * Returns a comand for str_replace function in SQL query.
2023          * Uses REPLACE() in MySQL
2024          *
2025          * @param $orig String: column to modify
2026          * @param $old String: column to seek
2027          * @param $new String: column to replace with
2028          */
2029         function strreplace( $orig, $old, $new ) {
2030                 return "REPLACE({$orig}, {$old}, {$new})";
2031         }
2032
2033         /**
2034          * Determines if the last failure was due to a deadlock
2035          * STUB
2036          */
2037         function wasDeadlock() {
2038                 return false;
2039         }
2040
2041         /**
2042          * Determines if the last query error was something that should be dealt
2043          * with by pinging the connection and reissuing the query.
2044          * STUB
2045          */
2046         function wasErrorReissuable() {
2047                 return false;
2048         }
2049
2050         /**
2051          * Determines if the last failure was due to the database being read-only.
2052          * STUB
2053          */
2054         function wasReadOnlyError() {
2055                 return false;
2056         }
2057
2058         /**
2059          * Perform a deadlock-prone transaction.
2060          *
2061          * This function invokes a callback function to perform a set of write
2062          * queries. If a deadlock occurs during the processing, the transaction
2063          * will be rolled back and the callback function will be called again.
2064          *
2065          * Usage:
2066          *       $dbw->deadlockLoop( callback, ... );
2067          *
2068          * Extra arguments are passed through to the specified callback function.
2069          *
2070          * Returns whatever the callback function returned on its successful,
2071          * iteration, or false on error, for example if the retry limit was
2072          * reached.
2073          */
2074         function deadlockLoop() {
2075                 $myFname = 'DatabaseBase::deadlockLoop';
2076
2077                 $this->begin();
2078                 $args = func_get_args();
2079                 $function = array_shift( $args );
2080                 $oldIgnore = $this->ignoreErrors( true );
2081                 $tries = DEADLOCK_TRIES;
2082
2083                 if ( is_array( $function ) ) {
2084                         $fname = $function[0];
2085                 } else {
2086                         $fname = $function;
2087                 }
2088
2089                 do {
2090                         $retVal = call_user_func_array( $function, $args );
2091                         $error = $this->lastError();
2092                         $errno = $this->lastErrno();
2093                         $sql = $this->lastQuery();
2094
2095                         if ( $errno ) {
2096                                 if ( $this->wasDeadlock() ) {
2097                                         # Retry
2098                                         usleep( mt_rand( DEADLOCK_DELAY_MIN, DEADLOCK_DELAY_MAX ) );
2099                                 } else {
2100                                         $this->reportQueryError( $error, $errno, $sql, $fname );
2101                                 }
2102                         }
2103                 } while ( $this->wasDeadlock() && --$tries > 0 );
2104
2105                 $this->ignoreErrors( $oldIgnore );
2106
2107                 if ( $tries <= 0 ) {
2108                         $this->rollback( $myFname );
2109                         $this->reportQueryError( $error, $errno, $sql, $fname );
2110                         return false;
2111                 } else {
2112                         $this->commit( $myFname );
2113                         return $retVal;
2114                 }
2115         }
2116
2117         /**
2118          * Do a SELECT MASTER_POS_WAIT()
2119          *
2120          * @param $pos MySQLMasterPos object
2121          * @param $timeout Integer: the maximum number of seconds to wait for synchronisation
2122          */
2123         function masterPosWait( MySQLMasterPos $pos, $timeout ) {
2124                 $fname = 'DatabaseBase::masterPosWait';
2125                 wfProfileIn( $fname );
2126
2127                 # Commit any open transactions
2128                 if ( $this->mTrxLevel ) {
2129                         $this->commit();
2130                 }
2131
2132                 if ( !is_null( $this->mFakeSlaveLag ) ) {
2133                         $wait = intval( ( $pos->pos - microtime( true ) + $this->mFakeSlaveLag ) * 1e6 );
2134
2135                         if ( $wait > $timeout * 1e6 ) {
2136                                 wfDebug( "Fake slave timed out waiting for $pos ($wait us)\n" );
2137                                 wfProfileOut( $fname );
2138                                 return -1;
2139                         } elseif ( $wait > 0 ) {
2140                                 wfDebug( "Fake slave waiting $wait us\n" );
2141                                 usleep( $wait );
2142                                 wfProfileOut( $fname );
2143                                 return 1;
2144                         } else {
2145                                 wfDebug( "Fake slave up to date ($wait us)\n" );
2146                                 wfProfileOut( $fname );
2147                                 return 0;
2148                         }
2149                 }
2150
2151                 # Call doQuery() directly, to avoid opening a transaction if DBO_TRX is set
2152                 $encFile = $this->addQuotes( $pos->file );
2153                 $encPos = intval( $pos->pos );
2154                 $sql = "SELECT MASTER_POS_WAIT($encFile, $encPos, $timeout)";
2155                 $res = $this->doQuery( $sql );
2156
2157                 if ( $res && $row = $this->fetchRow( $res ) ) {
2158                         wfProfileOut( $fname );
2159                         return $row[0];
2160                 } else {
2161                         wfProfileOut( $fname );
2162                         return false;
2163                 }
2164         }
2165
2166         /**
2167          * Get the position of the master from SHOW SLAVE STATUS
2168          */
2169         function getSlavePos() {
2170                 if ( !is_null( $this->mFakeSlaveLag ) ) {
2171                         $pos = new MySQLMasterPos( 'fake', microtime( true ) - $this->mFakeSlaveLag );
2172                         wfDebug( __METHOD__ . ": fake slave pos = $pos\n" );
2173                         return $pos;
2174                 }
2175
2176                 $res = $this->query( 'SHOW SLAVE STATUS', 'DatabaseBase::getSlavePos' );
2177                 $row = $this->fetchObject( $res );
2178
2179                 if ( $row ) {
2180                         $pos = isset( $row->Exec_master_log_pos ) ? $row->Exec_master_log_pos : $row->Exec_Master_Log_Pos;
2181                         return new MySQLMasterPos( $row->Relay_Master_Log_File, $pos );
2182                 } else {
2183                         return false;
2184                 }
2185         }
2186
2187         /**
2188          * Get the position of the master from SHOW MASTER STATUS
2189          */
2190         function getMasterPos() {
2191                 if ( $this->mFakeMaster ) {
2192                         return new MySQLMasterPos( 'fake', microtime( true ) );
2193                 }
2194
2195                 $res = $this->query( 'SHOW MASTER STATUS', 'DatabaseBase::getMasterPos' );
2196                 $row = $this->fetchObject( $res );
2197
2198                 if ( $row ) {
2199                         return new MySQLMasterPos( $row->File, $row->Position );
2200                 } else {
2201                         return false;
2202                 }
2203         }
2204
2205         /**
2206          * Begin a transaction, committing any previously open transaction
2207          */
2208         function begin( $fname = 'DatabaseBase::begin' ) {
2209                 $this->query( 'BEGIN', $fname );
2210                 $this->mTrxLevel = 1;
2211         }
2212
2213         /**
2214          * End a transaction
2215          */
2216         function commit( $fname = 'DatabaseBase::commit' ) {
2217                 if ( $this->mTrxLevel ) {
2218                         $this->query( 'COMMIT', $fname );
2219                         $this->mTrxLevel = 0;
2220                 }
2221         }
2222
2223         /**
2224          * Rollback a transaction.
2225          * No-op on non-transactional databases.
2226          */
2227         function rollback( $fname = 'DatabaseBase::rollback' ) {
2228                 if ( $this->mTrxLevel ) {
2229                         $this->query( 'ROLLBACK', $fname, true );
2230                         $this->mTrxLevel = 0;
2231                 }
2232         }
2233
2234         /**
2235          * Begin a transaction, committing any previously open transaction
2236          * @deprecated use begin()
2237          */
2238         function immediateBegin( $fname = 'DatabaseBase::immediateBegin' ) {
2239                 wfDeprecated( __METHOD__ );
2240                 $this->begin();
2241         }
2242
2243         /**
2244          * Commit transaction, if one is open
2245          * @deprecated use commit()
2246          */
2247         function immediateCommit( $fname = 'DatabaseBase::immediateCommit' ) {
2248                 wfDeprecated( __METHOD__ );
2249                 $this->commit();
2250         }
2251
2252         /**
2253          * Creates a new table with structure copied from existing table
2254          * Note that unlike most database abstraction functions, this function does not
2255          * automatically append database prefix, because it works at a lower
2256          * abstraction level.
2257          *
2258          * @param $oldName String: name of table whose structure should be copied
2259          * @param $newName String: name of table to be created
2260          * @param $temporary Boolean: whether the new table should be temporary
2261          * @param $fname String: calling function name
2262          * @return Boolean: true if operation was successful
2263          */
2264         function duplicateTableStructure( $oldName, $newName, $temporary = false, $fname = 'DatabaseBase::duplicateTableStructure' ) {
2265                 throw new MWException( 'DatabaseBase::duplicateTableStructure is not implemented in descendant class' );
2266         }
2267
2268         /**
2269          * Return MW-style timestamp used for MySQL schema
2270          */
2271         function timestamp( $ts = 0 ) {
2272                 return wfTimestamp( TS_MW, $ts );
2273         }
2274
2275         /**
2276          * Local database timestamp format or null
2277          */
2278         function timestampOrNull( $ts = null ) {
2279                 if ( is_null( $ts ) ) {
2280                         return null;
2281                 } else {
2282                         return $this->timestamp( $ts );
2283                 }
2284         }
2285
2286         /**
2287          * @todo document
2288          */
2289         function resultObject( $result ) {
2290                 if ( empty( $result ) ) {
2291                         return false;
2292                 } elseif ( $result instanceof ResultWrapper ) {
2293                         return $result;
2294                 } elseif ( $result === true ) {
2295                         // Successful write query
2296                         return $result;
2297                 } else {
2298                         return new ResultWrapper( $this, $result );
2299                 }
2300         }
2301
2302         /**
2303          * Return aggregated value alias
2304          */
2305         function aggregateValue ( $valuedata, $valuename = 'value' ) {
2306                 return $valuename;
2307         }
2308
2309         /**
2310          * Ping the server and try to reconnect if it there is no connection
2311          *
2312          * @return bool Success or failure
2313          */
2314         function ping() {
2315                 # Stub.  Not essential to override.
2316                 return true;
2317         }
2318
2319         /**
2320          * Get slave lag.
2321          * Currently supported only by MySQL
2322          * @return Database replication lag in seconds
2323          */
2324         function getLag() {
2325                 return intval( $this->mFakeSlaveLag );
2326         }
2327
2328         /**
2329          * Get status information from SHOW STATUS in an associative array
2330          */
2331         function getStatus( $which = "%" ) {
2332                 $res = $this->query( "SHOW STATUS LIKE '{$which}'" );
2333                 $status = array();
2334
2335                 while ( $row = $this->fetchObject( $res ) ) {
2336                         $status[$row->Variable_name] = $row->Value;
2337                 }
2338
2339                 return $status;
2340         }
2341
2342         /**
2343          * Return the maximum number of items allowed in a list, or 0 for unlimited.
2344          */
2345         function maxListLen() {
2346                 return 0;
2347         }
2348
2349         function encodeBlob( $b ) {
2350                 return $b;
2351         }
2352
2353         function decodeBlob( $b ) {
2354                 return $b;
2355         }
2356
2357         /**
2358          * Override database's default connection timeout.      May be useful for very
2359          * long batch queries such as full-wiki dumps, where a single query reads
2360          * out over hours or days.      May or may not be necessary for non-MySQL
2361          * databases.  For most purposes, leaving it as a no-op should be fine.
2362          *
2363          * @param $timeout Integer in seconds
2364          */
2365         public function setTimeout( $timeout ) {}
2366
2367         /**
2368          * Read and execute SQL commands from a file.
2369          * Returns true on success, error string or exception on failure (depending on object's error ignore settings)
2370          * @param $filename String: File name to open
2371          * @param $lineCallback Callback: Optional function called before reading each line
2372          * @param $resultCallback Callback: Optional function called for each MySQL result
2373          * @param $fname String: Calling function name or false if name should be generated dynamically
2374          *              using $filename
2375          */
2376         function sourceFile( $filename, $lineCallback = false, $resultCallback = false, $fname = false ) {
2377                 $fp = fopen( $filename, 'r' );
2378
2379                 if ( false === $fp ) {
2380                         if ( !defined( "MEDIAWIKI_INSTALL" ) )
2381                                 throw new MWException( "Could not open \"{$filename}\".\n" );
2382                         else
2383                                 return "Could not open \"{$filename}\".\n";
2384                 }
2385
2386                 if ( !$fname ) {
2387                         $fname = __METHOD__ . "( $filename )";
2388                 }
2389
2390                 try {
2391                         $error = $this->sourceStream( $fp, $lineCallback, $resultCallback, $fname );
2392                 }
2393                 catch ( MWException $e ) {
2394                         if ( defined( "MEDIAWIKI_INSTALL" ) ) {
2395                                 $error = $e->getMessage();
2396                         } else {
2397                                 fclose( $fp );
2398                                 throw $e;
2399                         }
2400                 }
2401
2402                 fclose( $fp );
2403
2404                 return $error;
2405         }
2406
2407         /**
2408          * Get the full path of a patch file. Originally based on archive()
2409          * from updaters.inc. Keep in mind this always returns a patch, as
2410          * it fails back to MySQL if no DB-specific patch can be found
2411          *
2412          * @param $patch String The name of the patch, like patch-something.sql
2413          * @return String Full path to patch file
2414          */
2415         public static function patchPath( $patch ) {
2416                 global $wgDBtype, $IP;
2417
2418                 if ( file_exists( "$IP/maintenance/$wgDBtype/archives/$patch" ) ) {
2419                         return "$IP/maintenance/$wgDBtype/archives/$patch";
2420                 } else {
2421                         return "$IP/maintenance/archives/$patch";
2422                 }
2423         }
2424
2425         /**
2426          * Read and execute commands from an open file handle
2427          * Returns true on success, error string or exception on failure (depending on object's error ignore settings)
2428          * @param $fp String: File handle
2429          * @param $lineCallback Callback: Optional function called before reading each line
2430          * @param $resultCallback Callback: Optional function called for each MySQL result
2431          * @param $fname String: Calling function name
2432          */
2433         function sourceStream( $fp, $lineCallback = false, $resultCallback = false, $fname = 'DatabaseBase::sourceStream' ) {
2434                 $cmd = "";
2435                 $done = false;
2436                 $dollarquote = false;
2437
2438                 while ( ! feof( $fp ) ) {
2439                         if ( $lineCallback ) {
2440                                 call_user_func( $lineCallback );
2441                         }
2442
2443                         $line = trim( fgets( $fp, 1024 ) );
2444                         $sl = strlen( $line ) - 1;
2445
2446                         if ( $sl < 0 ) {
2447                                 continue;
2448                         }
2449
2450                         if ( '-' == $line { 0 } && '-' == $line { 1 } ) {
2451                                 continue;
2452                         }
2453
2454                         # # Allow dollar quoting for function declarations
2455                         if ( substr( $line, 0, 4 ) == '$mw$' ) {
2456                                 if ( $dollarquote ) {
2457                                         $dollarquote = false;
2458                                         $done = true;
2459                                 }
2460                                 else {
2461                                         $dollarquote = true;
2462                                 }
2463                         }
2464                         else if ( !$dollarquote ) {
2465                                 if ( ';' == $line { $sl } && ( $sl < 2 || ';' != $line { $sl - 1 } ) ) {
2466                                         $done = true;
2467                                         $line = substr( $line, 0, $sl );
2468                                 }
2469                         }
2470
2471                         if ( $cmd != '' ) {
2472                                 $cmd .= ' ';
2473                         }
2474
2475                         $cmd .= "$line\n";
2476
2477                         if ( $done ) {
2478                                 $cmd = str_replace( ';;', ";", $cmd );
2479                                 $cmd = $this->replaceVars( $cmd );
2480                                 $res = $this->query( $cmd, $fname );
2481
2482                                 if ( $resultCallback ) {
2483                                         call_user_func( $resultCallback, $res, $this );
2484                                 }
2485
2486                                 if ( false === $res ) {
2487                                         $err = $this->lastError();
2488                                         return "Query \"{$cmd}\" failed with error code \"$err\".\n";
2489                                 }
2490
2491                                 $cmd = '';
2492                                 $done = false;
2493                         }
2494                 }
2495
2496                 return true;
2497         }
2498
2499         /**
2500          * Replace variables in sourced SQL
2501          */
2502         protected function replaceVars( $ins ) {
2503                 $varnames = array(
2504                         'wgDBserver', 'wgDBname', 'wgDBintlname', 'wgDBuser',
2505                         'wgDBpassword', 'wgDBsqluser', 'wgDBsqlpassword',
2506                         'wgDBadminuser', 'wgDBadminpassword', 'wgDBTableOptions',
2507                 );
2508
2509                 // Ordinary variables
2510                 foreach ( $varnames as $var ) {
2511                         if ( isset( $GLOBALS[$var] ) ) {
2512                                 $val = addslashes( $GLOBALS[$var] ); // FIXME: safety check?
2513                                 $ins = str_replace( '{$' . $var . '}', $val, $ins );
2514                                 $ins = str_replace( '/*$' . $var . '*/`', '`' . $val, $ins );
2515                                 $ins = str_replace( '/*$' . $var . '*/', $val, $ins );
2516                         }
2517                 }
2518
2519                 // Table prefixes
2520                 $ins = preg_replace_callback( '!/\*(?:\$wgDBprefix|_)\*/([a-zA-Z_0-9]*)!',
2521                         array( $this, 'tableNameCallback' ), $ins );
2522
2523                 // Index names
2524                 $ins = preg_replace_callback( '!/\*i\*/([a-zA-Z_0-9]*)!',
2525                         array( $this, 'indexNameCallback' ), $ins );
2526
2527                 return $ins;
2528         }
2529
2530         /**
2531          * Table name callback
2532          * @private
2533          */
2534         protected function tableNameCallback( $matches ) {
2535                 return $this->tableName( $matches[1] );
2536         }
2537
2538         /**
2539          * Index name callback
2540          */
2541         protected function indexNameCallback( $matches ) {
2542                 return $this->indexName( $matches[1] );
2543         }
2544
2545         /**
2546          * Build a concatenation list to feed into a SQL query
2547          * @param $stringList Array: list of raw SQL expressions; caller is responsible for any quoting
2548          * @return String
2549          */
2550         function buildConcat( $stringList ) {
2551                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
2552         }
2553
2554         /**
2555          * Acquire a named lock
2556          *
2557          * Abstracted from Filestore::lock() so child classes can implement for
2558          * their own needs.
2559          *
2560          * @param $lockName String: name of lock to aquire
2561          * @param $method String: name of method calling us
2562          * @param $timeout Integer: timeout
2563          * @return Boolean
2564          */
2565         public function lock( $lockName, $method, $timeout = 5 ) {
2566                 return true;
2567         }
2568
2569         /**
2570          * Release a lock.
2571          *
2572          * @param $lockName String: Name of lock to release
2573          * @param $method String: Name of method calling us
2574          *
2575          * @return Returns 1 if the lock was released, 0 if the lock was not established
2576          * by this thread (in which case the lock is not released), and NULL if the named
2577          * lock did not exist
2578          */
2579         public function unlock( $lockName, $method ) {
2580                 return true;
2581         }
2582
2583         /**
2584          * Lock specific tables
2585          *
2586          * @param $read Array of tables to lock for read access
2587          * @param $write Array of tables to lock for write access
2588          * @param $method String name of caller
2589          * @param $lowPriority bool Whether to indicate writes to be LOW PRIORITY
2590          */
2591         public function lockTables( $read, $write, $method, $lowPriority = true ) {
2592                 return true;
2593         }
2594
2595         /**
2596          * Unlock specific tables
2597          *
2598          * @param $method String the caller
2599          */
2600         public function unlockTables( $method ) {
2601                 return true;
2602         }
2603
2604         /**
2605          * Get search engine class. All subclasses of this need to implement this
2606          * if they wish to use searching.
2607          *
2608          * @return String
2609          */
2610         public function getSearchEngine() {
2611                 return 'SearchEngineDummy';
2612         }
2613
2614         /**
2615          * Allow or deny "big selects" for this session only. This is done by setting
2616          * the sql_big_selects session variable.
2617          *
2618          * This is a MySQL-specific feature.
2619          *
2620          * @param $value Mixed: true for allow, false for deny, or "default" to restore the initial value
2621          */
2622         public function setBigSelects( $value = true ) {
2623                 // no-op
2624         }
2625 }
2626
2627 /******************************************************************************
2628  * Utility classes
2629  *****************************************************************************/
2630
2631 /**
2632  * Utility class.
2633  * @ingroup Database
2634  */
2635 class DBObject {
2636         public $mData;
2637
2638         function __construct( $data ) {
2639                 $this->mData = $data;
2640         }
2641
2642         function isLOB() {
2643                 return false;
2644         }
2645
2646         function data() {
2647                 return $this->mData;
2648         }
2649 }
2650
2651 /**
2652  * Utility class
2653  * @ingroup Database
2654  *
2655  * This allows us to distinguish a blob from a normal string and an array of strings
2656  */
2657 class Blob {
2658         private $mData;
2659
2660         function __construct( $data ) {
2661                 $this->mData = $data;
2662         }
2663
2664         function fetch() {
2665                 return $this->mData;
2666         }
2667 }
2668
2669 /**
2670  * Utility class.
2671  * @ingroup Database
2672  */
2673 class MySQLField {
2674         private $name, $tablename, $default, $max_length, $nullable,
2675                 $is_pk, $is_unique, $is_multiple, $is_key, $type;
2676
2677         function __construct ( $info ) {
2678                 $this->name = $info->name;
2679                 $this->tablename = $info->table;
2680                 $this->default = $info->def;
2681                 $this->max_length = $info->max_length;
2682                 $this->nullable = !$info->not_null;
2683                 $this->is_pk = $info->primary_key;
2684                 $this->is_unique = $info->unique_key;
2685                 $this->is_multiple = $info->multiple_key;
2686                 $this->is_key = ( $this->is_pk || $this->is_unique || $this->is_multiple );
2687                 $this->type = $info->type;
2688         }
2689
2690         function name() {
2691                 return $this->name;
2692         }
2693
2694         function tableName() {
2695                 return $this->tableName;
2696         }
2697
2698         function defaultValue() {
2699                 return $this->default;
2700         }
2701
2702         function maxLength() {
2703                 return $this->max_length;
2704         }
2705
2706         function nullable() {
2707                 return $this->nullable;
2708         }
2709
2710         function isKey() {
2711                 return $this->is_key;
2712         }
2713
2714         function isMultipleKey() {
2715                 return $this->is_multiple;
2716         }
2717
2718         function type() {
2719                 return $this->type;
2720         }
2721 }
2722
2723 /******************************************************************************
2724  * Error classes
2725  *****************************************************************************/
2726
2727 /**
2728  * Database error base class
2729  * @ingroup Database
2730  */
2731 class DBError extends MWException {
2732         public $db;
2733
2734         /**
2735          * Construct a database error
2736          * @param $db Database object which threw the error
2737          * @param $error A simple error message to be used for debugging
2738          */
2739         function __construct( DatabaseBase &$db, $error ) {
2740                 $this->db =& $db;
2741                 parent::__construct( $error );
2742         }
2743
2744         function getText() {
2745                 global $wgShowDBErrorBacktrace;
2746
2747                 $s = $this->getMessage() . "\n";
2748
2749                 if ( $wgShowDBErrorBacktrace ) {
2750                         $s .= "Backtrace:\n" . $this->getTraceAsString() . "\n";
2751                 }
2752
2753                 return $s;
2754         }
2755 }
2756
2757 /**
2758  * @ingroup Database
2759  */
2760 class DBConnectionError extends DBError {
2761         public $error;
2762
2763         function __construct( DatabaseBase &$db, $error = 'unknown error' ) {
2764                 $msg = 'DB connection error';
2765
2766                 if ( trim( $error ) != '' ) {
2767                         $msg .= ": $error";
2768                 }
2769
2770                 $this->error = $error;
2771
2772                 parent::__construct( $db, $msg );
2773         }
2774
2775         function useOutputPage() {
2776                 // Not likely to work
2777                 return false;
2778         }
2779
2780         function useMessageCache() {
2781                 // Not likely to work
2782                 return false;
2783         }
2784
2785         function getLogMessage() {
2786                 # Don't send to the exception log
2787                 return false;
2788         }
2789
2790         function getPageTitle() {
2791                 global $wgSitename, $wgLang;
2792
2793                 $header = "$wgSitename has a problem";
2794
2795                 if ( $wgLang instanceof Language ) {
2796                         $header = htmlspecialchars( $wgLang->getMessage( 'dberr-header' ) );
2797                 }
2798
2799                 return $header;
2800         }
2801
2802         function getHTML() {
2803                 global $wgLang, $wgMessageCache, $wgUseFileCache, $wgShowDBErrorBacktrace;
2804
2805                 $sorry = 'Sorry! This site is experiencing technical difficulties.';
2806                 $again = 'Try waiting a few minutes and reloading.';
2807                 $info  = '(Can\'t contact the database server: $1)';
2808
2809                 if ( $wgLang instanceof Language ) {
2810                         $sorry = htmlspecialchars( $wgLang->getMessage( 'dberr-problems' ) );
2811                         $again = htmlspecialchars( $wgLang->getMessage( 'dberr-again' ) );
2812                         $info  = htmlspecialchars( $wgLang->getMessage( 'dberr-info' ) );
2813                 }
2814
2815                 # No database access
2816                 if ( is_object( $wgMessageCache ) ) {
2817                         $wgMessageCache->disable();
2818                 }
2819
2820                 if ( trim( $this->error ) == '' ) {
2821                         $this->error = $this->db->getProperty( 'mServer' );
2822                 }
2823
2824                 $noconnect = "<p><strong>$sorry</strong><br />$again</p><p><small>$info</small></p>";
2825                 $text = str_replace( '$1', $this->error, $noconnect );
2826
2827                 if ( $wgShowDBErrorBacktrace ) {
2828                         $text .= '<p>Backtrace:</p><p>' . nl2br( htmlspecialchars( $this->getTraceAsString() ) );
2829                 }
2830
2831                 $extra = $this->searchForm();
2832
2833                 if ( $wgUseFileCache ) {
2834                         try {
2835                                 $cache = $this->fileCachedPage();
2836                                 # Cached version on file system?
2837                                 if ( $cache !== null ) {
2838                                         # Hack: extend the body for error messages
2839                                         $cache = str_replace( array( '</html>', '</body>' ), '', $cache );
2840                                         # Add cache notice...
2841                                         $cachederror = "This is a cached copy of the requested page, and may not be up to date. ";
2842
2843                                         # Localize it if possible...
2844                                         if ( $wgLang instanceof Language ) {
2845                                                 $cachederror = htmlspecialchars( $wgLang->getMessage( 'dberr-cachederror' ) );
2846                                         }
2847
2848                                         $warning = "<div style='color:red;font-size:150%;font-weight:bold;'>$cachederror</div>";
2849
2850                                         # Output cached page with notices on bottom and re-close body
2851                                         return "{$cache}{$warning}<hr />$text<hr />$extra</body></html>";
2852                                 }
2853                         } catch ( MWException $e ) {
2854                                 // Do nothing, just use the default page
2855                         }
2856                 }
2857
2858                 # Headers needed here - output is just the error message
2859                 return $this->htmlHeader() . "$text<hr />$extra" . $this->htmlFooter();
2860         }
2861
2862         function searchForm() {
2863                 global $wgSitename, $wgServer, $wgLang, $wgInputEncoding;
2864
2865                 $usegoogle = "You can try searching via Google in the meantime.";
2866                 $outofdate = "Note that their indexes of our content may be out of date.";
2867                 $googlesearch = "Search";
2868
2869                 if ( $wgLang instanceof Language ) {
2870                         $usegoogle = htmlspecialchars( $wgLang->getMessage( 'dberr-usegoogle' ) );
2871                         $outofdate = htmlspecialchars( $wgLang->getMessage( 'dberr-outofdate' ) );
2872                         $googlesearch  = htmlspecialchars( $wgLang->getMessage( 'searchbutton' ) );
2873                 }
2874
2875                 $search = htmlspecialchars( @$_REQUEST['search'] );
2876
2877                 $trygoogle = <<<EOT
2878 <div style="margin: 1.5em">$usegoogle<br />
2879 <small>$outofdate</small></div>
2880 <!-- SiteSearch Google -->
2881 <form method="get" action="http://www.google.com/search" id="googlesearch">
2882         <input type="hidden" name="domains" value="$wgServer" />
2883         <input type="hidden" name="num" value="50" />
2884         <input type="hidden" name="ie" value="$wgInputEncoding" />
2885         <input type="hidden" name="oe" value="$wgInputEncoding" />
2886
2887         <input type="text" name="q" size="31" maxlength="255" value="$search" />
2888         <input type="submit" name="btnG" value="$googlesearch" />
2889   <div>
2890         <input type="radio" name="sitesearch" id="gwiki" value="$wgServer" checked="checked" /><label for="gwiki">$wgSitename</label>
2891         <input type="radio" name="sitesearch" id="gWWW" value="" /><label for="gWWW">WWW</label>
2892   </div>
2893 </form>
2894 <!-- SiteSearch Google -->
2895 EOT;
2896                 return $trygoogle;
2897         }
2898
2899         function fileCachedPage() {
2900                 global $wgTitle, $title, $wgLang, $wgOut;
2901
2902                 if ( $wgOut->isDisabled() ) {
2903                         return; // Done already?
2904                 }
2905
2906                 $mainpage = 'Main Page';
2907
2908                 if ( $wgLang instanceof Language ) {
2909                         $mainpage        = htmlspecialchars( $wgLang->getMessage( 'mainpage' ) );
2910                 }
2911
2912                 if ( $wgTitle ) {
2913                         $t =& $wgTitle;
2914                 } elseif ( $title ) {
2915                         $t = Title::newFromURL( $title );
2916                 } else {
2917                         $t = Title::newFromText( $mainpage );
2918                 }
2919
2920                 $cache = new HTMLFileCache( $t );
2921                 if ( $cache->isFileCached() ) {
2922                         return $cache->fetchPageText();
2923                 } else {
2924                         return '';
2925                 }
2926         }
2927
2928         function htmlBodyOnly() {
2929                 return true;
2930         }
2931 }
2932
2933 /**
2934  * @ingroup Database
2935  */
2936 class DBQueryError extends DBError {
2937         public $error, $errno, $sql, $fname;
2938
2939         function __construct( DatabaseBase &$db, $error, $errno, $sql, $fname ) {
2940                 $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" .
2941                   "Query: $sql\n" .
2942                   "Function: $fname\n" .
2943                   "Error: $errno $error\n";
2944
2945                 parent::__construct( $db, $message );
2946
2947                 $this->error = $error;
2948                 $this->errno = $errno;
2949                 $this->sql = $sql;
2950                 $this->fname = $fname;
2951         }
2952
2953         function getText() {
2954                 global $wgShowDBErrorBacktrace;
2955
2956                 if ( $this->useMessageCache() ) {
2957                         $s = wfMsg( 'dberrortextcl', htmlspecialchars( $this->getSQL() ),
2958                                 htmlspecialchars( $this->fname ), $this->errno, htmlspecialchars( $this->error ) ) . "\n";
2959
2960                         if ( $wgShowDBErrorBacktrace ) {
2961                                 $s .= "Backtrace:\n" . $this->getTraceAsString() . "\n";
2962                         }
2963
2964                         return $s;
2965                 } else {
2966                         return parent::getText();
2967                 }
2968         }
2969
2970         function getSQL() {
2971                 global $wgShowSQLErrors;
2972
2973                 if ( !$wgShowSQLErrors ) {
2974                         return $this->msg( 'sqlhidden', 'SQL hidden' );
2975                 } else {
2976                         return $this->sql;
2977                 }
2978         }
2979
2980         function getLogMessage() {
2981                 # Don't send to the exception log
2982                 return false;
2983         }
2984
2985         function getPageTitle() {
2986                 return $this->msg( 'databaseerror', 'Database error' );
2987         }
2988
2989         function getHTML() {
2990                 global $wgShowDBErrorBacktrace;
2991
2992                 if ( $this->useMessageCache() ) {
2993                         $s = wfMsgNoDB( 'dberrortext', htmlspecialchars( $this->getSQL() ),
2994                           htmlspecialchars( $this->fname ), $this->errno, htmlspecialchars( $this->error ) );
2995                 } else {
2996                         $s = nl2br( htmlspecialchars( $this->getMessage() ) );
2997                 }
2998
2999                 if ( $wgShowDBErrorBacktrace ) {
3000                         $s .= '<p>Backtrace:</p><p>' . nl2br( htmlspecialchars( $this->getTraceAsString() ) );
3001                 }
3002
3003                 return $s;
3004         }
3005 }
3006
3007 /**
3008  * @ingroup Database
3009  */
3010 class DBUnexpectedError extends DBError {}
3011
3012
3013 /**
3014  * Result wrapper for grabbing data queried by someone else
3015  * @ingroup Database
3016  */
3017 class ResultWrapper implements Iterator {
3018         var $db, $result, $pos = 0, $currentRow = null;
3019
3020         /**
3021          * Create a new result object from a result resource and a Database object
3022          */
3023         function __construct( $database, $result ) {
3024                 $this->db = $database;
3025
3026                 if ( $result instanceof ResultWrapper ) {
3027                         $this->result = $result->result;
3028                 } else {
3029                         $this->result = $result;
3030                 }
3031         }
3032
3033         /**
3034          * Get the number of rows in a result object
3035          */
3036         function numRows() {
3037                 return $this->db->numRows( $this );
3038         }
3039
3040         /**
3041          * Fetch the next row from the given result object, in object form.
3042          * Fields can be retrieved with $row->fieldname, with fields acting like
3043          * member variables.
3044          *
3045          * @return MySQL row object
3046          * @throws DBUnexpectedError Thrown if the database returns an error
3047          */
3048         function fetchObject() {
3049                 return $this->db->fetchObject( $this );
3050         }
3051
3052         /**
3053          * Fetch the next row from the given result object, in associative array
3054          * form.  Fields are retrieved with $row['fieldname'].
3055          *
3056          * @return MySQL row object
3057          * @throws DBUnexpectedError Thrown if the database returns an error
3058          */
3059         function fetchRow() {
3060                 return $this->db->fetchRow( $this );
3061         }
3062
3063         /**
3064          * Free a result object
3065          */
3066         function free() {
3067                 $this->db->freeResult( $this );
3068                 unset( $this->result );
3069                 unset( $this->db );
3070         }
3071
3072         /**
3073          * Change the position of the cursor in a result object
3074          * See mysql_data_seek()
3075          */
3076         function seek( $row ) {
3077                 $this->db->dataSeek( $this, $row );
3078         }
3079
3080         /*********************
3081          * Iterator functions
3082          * Note that using these in combination with the non-iterator functions
3083          * above may cause rows to be skipped or repeated.
3084          */
3085
3086         function rewind() {
3087                 if ( $this->numRows() ) {
3088                         $this->db->dataSeek( $this, 0 );
3089                 }
3090                 $this->pos = 0;
3091                 $this->currentRow = null;
3092         }
3093
3094         function current() {
3095                 if ( is_null( $this->currentRow ) ) {
3096                         $this->next();
3097                 }
3098                 return $this->currentRow;
3099         }
3100
3101         function key() {
3102                 return $this->pos;
3103         }
3104
3105         function next() {
3106                 $this->pos++;
3107                 $this->currentRow = $this->fetchObject();
3108                 return $this->currentRow;
3109         }
3110
3111         function valid() {
3112                 return $this->current() !== false;
3113         }
3114 }
3115
3116 /**
3117  * Overloads the relevant methods of the real ResultsWrapper so it
3118  * doesn't go anywhere near an actual database.
3119  */
3120 class FakeResultWrapper extends ResultWrapper {
3121         var $result             = array();
3122         var $db                 = null; // And it's going to stay that way :D
3123         var $pos                = 0;
3124         var $currentRow = null;
3125
3126         function __construct( $array ) {
3127                 $this->result = $array;
3128         }
3129
3130         function numRows() {
3131                 return count( $this->result );
3132         }
3133
3134         function fetchRow() {
3135                 $this->currentRow = $this->result[$this->pos++];
3136                 return $this->currentRow;
3137         }
3138
3139         function seek( $row ) {
3140                 $this->pos = $row;
3141         }
3142
3143         function free() {}
3144
3145         // Callers want to be able to access fields with $this->fieldName
3146         function fetchObject() {
3147                 $this->currentRow = $this->result[$this->pos++];
3148                 return (object)$this->currentRow;
3149         }
3150
3151         function rewind() {
3152                 $this->pos = 0;
3153                 $this->currentRow = null;
3154         }
3155 }
3156
3157 /**
3158  * Used by DatabaseBase::buildLike() to represent characters that have special meaning in SQL LIKE clauses
3159  * and thus need no escaping. Don't instantiate it manually, use DatabaseBase::anyChar() and anyString() instead.
3160  */
3161 class LikeMatch {
3162         private $str;
3163
3164         public function __construct( $s ) {
3165                 $this->str = $s;
3166         }
3167
3168         public function toString() {
3169                 return $this->str;
3170         }
3171 }