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  * Database abstraction object
  20  * @ingroup Database
  21  */
  22 abstract class DatabaseBase implements DatabaseType {
  23
  24 #------------------------------------------------------------------------------
  25 # Variables
  26 #------------------------------------------------------------------------------
  27
  28         protected $mLastQuery = '';
  29         protected $mDoneWrites = false;
  30         protected $mPHPError = false;
  31
  32         protected $mServer, $mUser, $mPassword, $mConn = null, $mDBname;
  33         protected $mOpened = false;
  34
  35         protected $mFailFunction;
  36         protected $mTablePrefix;
  37         protected $mFlags;
  38         protected $mTrxLevel = 0;
  39         protected $mErrorCount = 0;
  40         protected $mLBInfo = array();
  41         protected $mFakeSlaveLag = null, $mFakeMaster = false;
  42         protected $mDefaultBigSelects = null;
  43
  44 #------------------------------------------------------------------------------
  45 # Accessors
  46 #------------------------------------------------------------------------------
  47         # These optionally set a variable and return the previous state
  48
  49         /**
  50          * Fail function, takes a Database as a parameter
  51          * Set to false for default, 1 for ignore errors
  52          */
  53         function failFunction( $function = null ) {
  54                 return wfSetVar( $this->mFailFunction, $function );
  55         }
  56
  57         /**
  58          * Boolean, controls output of large amounts of debug information
  59          */
  60         function debug( $debug = null ) {
  61                 return wfSetBit( $this->mFlags, DBO_DEBUG, $debug );
  62         }
  63
  64         /**
  65          * Turns buffering of SQL result sets on (true) or off (false).
  66          * Default is "on" and it should not be changed without good reasons.
  67          */
  68         function bufferResults( $buffer = null ) {
  69                 if ( is_null( $buffer ) ) {
  70                         return !(bool)( $this->mFlags & DBO_NOBUFFER );
  71                 } else {
  72                         return !wfSetBit( $this->mFlags, DBO_NOBUFFER, !$buffer );
  73                 }
  74         }
  75
  76         /**
  77          * Turns on (false) or off (true) the automatic generation and sending
  78          * of a "we're sorry, but there has been a database error" page on
  79          * database errors. Default is on (false). When turned off, the
  80          * code should use lastErrno() and lastError() to handle the
  81          * situation as appropriate.
  82          */
  83         function ignoreErrors( $ignoreErrors = null ) {
  84                 return wfSetBit( $this->mFlags, DBO_IGNORE, $ignoreErrors );
  85         }
  86
  87         /**
  88          * The current depth of nested transactions
  89          * @param $level Integer: , default NULL.
  90          */
  91         function trxLevel( $level = null ) {
  92                 return wfSetVar( $this->mTrxLevel, $level );
  93         }
  94
  95         /**
  96          * Number of errors logged, only useful when errors are ignored
  97          */
  98         function errorCount( $count = null ) {
  99                 return wfSetVar( $this->mErrorCount, $count );
 100         }
 101
 102         function tablePrefix( $prefix = null ) {
 103                 return wfSetVar( $this->mTablePrefix, $prefix );
 104         }
 105
 106         /**
 107          * Properties passed down from the server info array of the load balancer
 108          */
 109         function getLBInfo( $name = null ) {
 110                 if ( is_null( $name ) ) {
 111                         return $this->mLBInfo;
 112                 } else {
 113                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 114                                 return $this->mLBInfo[$name];
 115                         } else {
 116                                 return null;
 117                         }
 118                 }
 119         }
 120
 121         function setLBInfo( $name, $value = null ) {
 122                 if ( is_null( $value ) ) {
 123                         $this->mLBInfo = $name;
 124                 } else {
 125                         $this->mLBInfo[$name] = $value;
 126                 }
 127         }
 128
 129         /**
 130          * Set lag time in seconds for a fake slave
 131          */
 132         function setFakeSlaveLag( $lag ) {
 133                 $this->mFakeSlaveLag = $lag;
 134         }
 135
 136         /**
 137          * Make this connection a fake master
 138          */
 139         function setFakeMaster( $enabled = true ) {
 140                 $this->mFakeMaster = $enabled;
 141         }
 142
 143         /**
 144          * Returns true if this database supports (and uses) cascading deletes
 145          */
 146         function cascadingDeletes() {
 147                 return false;
 148         }
 149
 150         /**
 151          * Returns true if this database supports (and uses) triggers (e.g. on the page table)
 152          */
 153         function cleanupTriggers() {
 154                 return false;
 155         }
 156
 157         /**
 158          * Returns true if this database is strict about what can be put into an IP field.
 159          * Specifically, it uses a NULL value instead of an empty string.
 160          */
 161         function strictIPs() {
 162                 return false;
 163         }
 164
 165         /**
 166          * Returns true if this database uses timestamps rather than integers
 167         */
 168         function realTimestamps() {
 169                 return false;
 170         }
 171
 172         /**
 173          * Returns true if this database does an implicit sort when doing GROUP BY
 174          */
 175         function implicitGroupby() {
 176                 return true;
 177         }
 178
 179         /**
 180          * Returns true if this database does an implicit order by when the column has an index
 181          * For example: SELECT page_title FROM page LIMIT 1
 182          */
 183         function implicitOrderby() {
 184                 return true;
 185         }
 186
 187         /**
 188          * Returns true if this database requires that SELECT DISTINCT queries require that all
 189        ORDER BY expressions occur in the SELECT list per the SQL92 standard
 190          */
 191         function standardSelectDistinct() {
 192                 return true;
 193         }
 194
 195         /**
 196          * Returns true if this database can do a native search on IP columns
 197          * e.g. this works as expected: .. WHERE rc_ip = '127.42.12.102/32';
 198          */
 199         function searchableIPs() {
 200                 return false;
 201         }
 202
 203         /**
 204          * Returns true if this database can use functional indexes
 205          */
 206         function functionalIndexes() {
 207                 return false;
 208         }
 209
 210         /**
 211          * Return the last query that went through DatabaseBase::query()
 212          * @return String
 213          */
 214         function lastQuery() { return $this->mLastQuery; }
 215
 216
 217         /**
 218          * Returns true if the connection may have been used for write queries.
 219          * Should return true if unsure.
 220          */
 221         function doneWrites() { return $this->mDoneWrites; }
 222
 223         /**
 224          * Is a connection to the database open?
 225          * @return Boolean
 226          */
 227         function isOpen() { return $this->mOpened; }
 228
 229         /**
 230          * Set a flag for this connection
 231          *
 232          * @param $flag Integer: DBO_* constants from Defines.php:
 233          *   - DBO_DEBUG: output some debug info (same as debug())
 234          *   - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
 235          *   - DBO_IGNORE: ignore errors (same as ignoreErrors())
 236          *   - DBO_TRX: automatically start transactions
 237          *   - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
 238          *       and removes it in command line mode
 239          *   - DBO_PERSISTENT: use persistant database connection
 240          */
 241         function setFlag( $flag ) {
 242                 $this->mFlags |= $flag;
 243         }
 244
 245         /**
 246          * Clear a flag for this connection
 247          *
 248          * @param $flag: same as setFlag()'s $flag param
 249          */
 250         function clearFlag( $flag ) {
 251                 $this->mFlags &= ~$flag;
 252         }
 253
 254         /**
 255          * Returns a boolean whether the flag $flag is set for this connection
 256          *
 257          * @param $flag: same as setFlag()'s $flag param
 258          * @return Boolean
 259          */
 260         function getFlag( $flag ) {
 261                 return !!($this->mFlags & $flag);
 262         }
 263
 264         /**
 265          * General read-only accessor
 266          */
 267         function getProperty( $name ) {
 268                 return $this->$name;
 269         }
 270
 271         function getWikiID() {
 272                 if( $this->mTablePrefix ) {
 273                         return "{$this->mDBname}-{$this->mTablePrefix}";
 274                 } else {
 275                         return $this->mDBname;
 276                 }
 277         }
 278
 279 #------------------------------------------------------------------------------
 280 # Other functions
 281 #------------------------------------------------------------------------------
 282
 283         /**
 284          * Constructor.
 285          * @param $server String: database server host
 286          * @param $user String: database user name
 287          * @param $password String: database user password
 288          * @param $dbName String: database name
 289          * @param $failFunction
 290          * @param $flags
 291          * @param $tablePrefix String: database table prefixes. By default use the prefix gave in LocalSettings.php
 292          */
 293         function __construct( $server = false, $user = false, $password = false, $dbName = false,
 294                 $failFunction = false, $flags = 0, $tablePrefix = 'get from global' ) {
 295
 296                 global $wgOut, $wgDBprefix, $wgCommandLineMode;
 297                 # Can't get a reference if it hasn't been set yet
 298                 if ( !isset( $wgOut ) ) {
 299                         $wgOut = null;
 300                 }
 301
 302                 $this->mFailFunction = $failFunction;
 303                 $this->mFlags = $flags;
 304
 305                 if ( $this->mFlags & DBO_DEFAULT ) {
 306                         if ( $wgCommandLineMode ) {
 307                                 $this->mFlags &= ~DBO_TRX;
 308                         } else {
 309                                 $this->mFlags |= DBO_TRX;
 310                         }
 311                 }
 312
 313                 /*
 314                 // Faster read-only access
 315                 if ( wfReadOnly() ) {
 316                         $this->mFlags |= DBO_PERSISTENT;
 317                         $this->mFlags &= ~DBO_TRX;
 318                 }*/
 319
 320                 /** Get the default table prefix*/
 321                 if ( $tablePrefix == 'get from global' ) {
 322                         $this->mTablePrefix = $wgDBprefix;
 323                 } else {
 324                         $this->mTablePrefix = $tablePrefix;
 325                 }
 326
 327                 if ( $server ) {
 328                         $this->open( $server, $user, $password, $dbName );
 329                 }
 330         }
 331
 332         /**
 333          * Same as new DatabaseMysql( ... ), kept for backward compatibility
 334          * @param $server String: database server host
 335          * @param $user String: database user name
 336          * @param $password String: database user password
 337          * @param $dbName String: database name
 338          * @param failFunction
 339          * @param $flags
 340          */
 341         static function newFromParams( $server, $user, $password, $dbName, $failFunction = false, $flags = 0 )
 342         {
 343                 wfDeprecated( __METHOD__ );
 344                 return new DatabaseMysql( $server, $user, $password, $dbName, $failFunction, $flags );
 345         }
 346
 347         protected function installErrorHandler() {
 348                 $this->mPHPError = false;
 349                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 350                 set_error_handler( array( $this, 'connectionErrorHandler' ) );
 351         }
 352
 353         protected function restoreErrorHandler() {
 354                 restore_error_handler();
 355                 if ( $this->htmlErrors !== false ) {
 356                         ini_set( 'html_errors', $this->htmlErrors );
 357                 }
 358                 if ( $this->mPHPError ) {
 359                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 360                         $error = preg_replace( '!^.*?:(.*)$!', '$1', $error );
 361                         return $error;
 362                 } else {
 363                         return false;
 364                 }
 365         }
 366
 367         protected function connectionErrorHandler( $errno,  $errstr ) {
 368                 $this->mPHPError = $errstr;
 369         }
 370
 371         /**
 372          * Closes a database connection.
 373          * if it is open : commits any open transactions
 374          *
 375          * @return Bool operation success. true if already closed.
 376          */
 377         function close() {
 378                 # Stub, should probably be overridden
 379                 return true;
 380         }
 381
 382         /**
 383          * @param $error String: fallback error message, used if none is given by DB
 384          */
 385         function reportConnectionError( $error = 'Unknown error' ) {
 386                 $myError = $this->lastError();
 387                 if ( $myError ) {
 388                         $error = $myError;
 389                 }
 390
 391                 if ( $this->mFailFunction ) {
 392                         # Legacy error handling method
 393                         if ( !is_int( $this->mFailFunction ) ) {
 394                                 $ff = $this->mFailFunction;
 395                                 $ff( $this, $error );
 396                         }
 397                 } else {
 398                         # New method
 399                         throw new DBConnectionError( $this, $error );
 400                 }
 401         }
 402
 403         /**
 404          * Determine whether a query writes to the DB.
 405          * Should return true if unsure.
 406          */
 407         function isWriteQuery( $sql ) {
 408                 return !preg_match( '/^(?:SELECT|BEGIN|COMMIT|SET|SHOW|\(SELECT)\b/i', $sql );
 409         }
 410
 411         /**
 412          * Usually aborts on failure.  If errors are explicitly ignored, returns success.
 413          *
 414          * @param  $sql        String: SQL query
 415          * @param  $fname      String: Name of the calling function, for profiling/SHOW PROCESSLIST
 416          *     comment (you can use __METHOD__ or add some extra info)
 417          * @param  $tempIgnore Boolean:   Whether to avoid throwing an exception on errors...
 418          *     maybe best to catch the exception instead?
 419          * @return true for a successful write query, ResultWrapper object for a successful read query,
 420          *     or false on failure if $tempIgnore set
 421          * @throws DBQueryError Thrown when the database returns an error of any kind
 422          */
 423         public function query( $sql, $fname = '', $tempIgnore = false ) {
 424                 global $wgProfiler;
 425
 426                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 427                 if ( isset( $wgProfiler ) ) {
 428                         # generalizeSQL will probably cut down the query to reasonable
 429                         # logging size most of the time. The substr is really just a sanity check.
 430
 431                         # Who's been wasting my precious column space? -- TS
 432                         #$profName = 'query: ' . $fname . ' ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 433
 434                         if ( $isMaster ) {
 435                                 $queryProf = 'query-m: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 436                                 $totalProf = 'DatabaseBase::query-master';
 437                         } else {
 438                                 $queryProf = 'query: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 439                                 $totalProf = 'DatabaseBase::query';
 440                         }
 441                         wfProfileIn( $totalProf );
 442                         wfProfileIn( $queryProf );
 443                 }
 444
 445                 $this->mLastQuery = $sql;
 446                 if ( !$this->mDoneWrites && $this->isWriteQuery( $sql ) ) {
 447                         // Set a flag indicating that writes have been done
 448                         wfDebug( __METHOD__.": Writes done: $sql\n" );
 449                         $this->mDoneWrites = true;
 450                 }
 451
 452                 # Add a comment for easy SHOW PROCESSLIST interpretation
 453                 #if ( $fname ) {
 454                         global $wgUser;
 455                         if ( is_object( $wgUser ) && !($wgUser instanceof StubObject) ) {
 456                                 $userName = $wgUser->getName();
 457                                 if ( mb_strlen( $userName ) > 15 ) {
 458                                         $userName = mb_substr( $userName, 0, 15 ) . '...';
 459                                 }
 460                                 $userName = str_replace( '/', '', $userName );
 461                         } else {
 462                                 $userName = '';
 463                         }
 464                         $commentedSql = preg_replace('/\s/', " /* $fname $userName */ ", $sql, 1);
 465                 #} else {
 466                 #       $commentedSql = $sql;
 467                 #}
 468
 469                 # If DBO_TRX is set, start a transaction
 470                 if ( ( $this->mFlags & DBO_TRX ) && !$this->trxLevel() &&
 471                         $sql != 'BEGIN' && $sql != 'COMMIT' && $sql != 'ROLLBACK') {
 472                         // avoid establishing transactions for SHOW and SET statements too -
 473                         // that would delay transaction initializations to once connection
 474                         // is really used by application
 475                         $sqlstart = substr($sql,0,10); // very much worth it, benchmark certified(tm)
 476                         if (strpos($sqlstart,"SHOW ")!==0 and strpos($sqlstart,"SET ")!==0)
 477                                 $this->begin();
 478                 }
 479
 480                 if ( $this->debug() ) {
 481                         static $cnt = 0;
 482                         $cnt++;
 483                         $sqlx = substr( $commentedSql, 0, 500 );
 484                         $sqlx = strtr( $sqlx, "\t\n", '  ' );
 485                         if ( $isMaster ) {
 486                                 wfDebug( "Query $cnt (master): $sqlx\n" );
 487                         } else {
 488                                 wfDebug( "Query $cnt (slave): $sqlx\n" );
 489                         }
 490                 }
 491
 492                 if ( istainted( $sql ) & TC_MYSQL ) {
 493                         throw new MWException( 'Tainted query found' );
 494                 }
 495
 496                 # Do the query and handle errors
 497                 $ret = $this->doQuery( $commentedSql );
 498
 499                 # Try reconnecting if the connection was lost
 500                 if ( false === $ret && $this->wasErrorReissuable() ) {
 501                         # Transaction is gone, like it or not
 502                         $this->mTrxLevel = 0;
 503                         wfDebug( "Connection lost, reconnecting...\n" );
 504                         if ( $this->ping() ) {
 505                                 wfDebug( "Reconnected\n" );
 506                                 $sqlx = substr( $commentedSql, 0, 500 );
 507                                 $sqlx = strtr( $sqlx, "\t\n", '  ' );
 508                                 global $wgRequestTime;
 509                                 $elapsed = round( microtime(true) - $wgRequestTime, 3 );
 510                                 wfLogDBError( "Connection lost and reconnected after {$elapsed}s, query: $sqlx\n" );
 511                                 $ret = $this->doQuery( $commentedSql );
 512                         } else {
 513                                 wfDebug( "Failed\n" );
 514                         }
 515                 }
 516
 517                 if ( false === $ret ) {
 518                         $this->reportQueryError( $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 519                 }
 520
 521                 if ( isset( $wgProfiler ) ) {
 522                         wfProfileOut( $queryProf );
 523                         wfProfileOut( $totalProf );
 524                 }
 525                 return $this->resultObject( $ret );
 526         }
 527
 528         /**
 529          * @param $error String
 530          * @param $errno Integer
 531          * @param $sql String
 532          * @param $fname String
 533          * @param $tempIgnore Boolean
 534          */
 535         function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 536                 # Ignore errors during error handling to avoid infinite recursion
 537                 $ignore = $this->ignoreErrors( true );
 538                 ++$this->mErrorCount;
 539
 540                 if( $ignore || $tempIgnore ) {
 541                         wfDebug("SQL ERROR (ignored): $error\n");
 542                         $this->ignoreErrors( $ignore );
 543                 } else {
 544                         $sql1line = str_replace( "\n", "\\n", $sql );
 545                         wfLogDBError("$fname\t{$this->mServer}\t$errno\t$error\t$sql1line\n");
 546                         wfDebug("SQL ERROR: " . $error . "\n");
 547                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
 548                 }
 549         }
 550
 551
 552         /**
 553          * Intended to be compatible with the PEAR::DB wrapper functions.
 554          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
 555          *
 556          * ? = scalar value, quoted as necessary
 557          * ! = raw SQL bit (a function for instance)
 558          * & = filename; reads the file and inserts as a blob
 559          *     (we don't use this though...)
 560          */
 561         function prepare( $sql, $func = 'DatabaseBase::prepare' ) {
 562                 /* MySQL doesn't support prepared statements (yet), so just
 563                    pack up the query for reference. We'll manually replace
 564                    the bits later. */
 565                 return array( 'query' => $sql, 'func' => $func );
 566         }
 567
 568         function freePrepared( $prepared ) {
 569                 /* No-op by default */
 570         }
 571
 572         /**
 573          * Execute a prepared query with the various arguments
 574          * @param $prepared String: the prepared sql
 575          * @param $args Mixed: Either an array here, or put scalars as varargs
 576          */
 577         function execute( $prepared, $args = null ) {
 578                 if( !is_array( $args ) ) {
 579                         # Pull the var args
 580                         $args = func_get_args();
 581                         array_shift( $args );
 582                 }
 583                 $sql = $this->fillPrepared( $prepared['query'], $args );
 584                 return $this->query( $sql, $prepared['func'] );
 585         }
 586
 587         /**
 588          * Prepare & execute an SQL statement, quoting and inserting arguments
 589          * in the appropriate places.
 590          * @param $query String
 591          * @param $args ...
 592          */
 593         function safeQuery( $query, $args = null ) {
 594                 $prepared = $this->prepare( $query, 'DatabaseBase::safeQuery' );
 595                 if( !is_array( $args ) ) {
 596                         # Pull the var args
 597                         $args = func_get_args();
 598                         array_shift( $args );
 599                 }
 600                 $retval = $this->execute( $prepared, $args );
 601                 $this->freePrepared( $prepared );
 602                 return $retval;
 603         }
 604
 605         /**
 606          * For faking prepared SQL statements on DBs that don't support
 607          * it directly.
 608          * @param $preparedQuery String: a 'preparable' SQL statement
 609          * @param $args Array of arguments to fill it with
 610          * @return string executable SQL
 611          */
 612         function fillPrepared( $preparedQuery, $args ) {
 613                 reset( $args );
 614                 $this->preparedArgs =& $args;
 615                 return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
 616                         array( &$this, 'fillPreparedArg' ), $preparedQuery );
 617         }
 618
 619         /**
 620          * preg_callback func for fillPrepared()
 621          * The arguments should be in $this->preparedArgs and must not be touched
 622          * while we're doing this.
 623          *
 624          * @param $matches Array
 625          * @return String
 626          * @private
 627          */
 628         function fillPreparedArg( $matches ) {
 629                 switch( $matches[1] ) {
 630                         case '\\?': return '?';
 631                         case '\\!': return '!';
 632                         case '\\&': return '&';
 633                 }
 634                 list( /* $n */ , $arg ) = each( $this->preparedArgs );
 635                 switch( $matches[1] ) {
 636                         case '?': return $this->addQuotes( $arg );
 637                         case '!': return $arg;
 638                         case '&':
 639                                 # return $this->addQuotes( file_get_contents( $arg ) );
 640                                 throw new DBUnexpectedError( $this, '& mode is not implemented. If it\'s really needed, uncomment the line above.' );
 641                         default:
 642                                 throw new DBUnexpectedError( $this, 'Received invalid match. This should never happen!' );
 643                 }
 644         }
 645
 646         /**
 647          * Free a result object
 648          * @param $res Mixed: A SQL result
 649          */
 650         function freeResult( $res ) {
 651                 # Stub.  Might not really need to be overridden, since results should
 652                 # be freed by PHP when the variable goes out of scope anyway.
 653         }
 654
 655         /**
 656          * Simple UPDATE wrapper
 657          * Usually aborts on failure
 658          * If errors are explicitly ignored, returns success
 659          *
 660          * This function exists for historical reasons, DatabaseBase::update() has a more standard
 661          * calling convention and feature set
 662          */
 663         function set( $table, $var, $value, $cond, $fname = 'DatabaseBase::set' ) {
 664                 $table = $this->tableName( $table );
 665                 $sql = "UPDATE $table SET $var = '" .
 666                   $this->strencode( $value ) . "' WHERE ($cond)";
 667                 return (bool)$this->query( $sql, $fname );
 668         }
 669
 670         /**
 671          * Simple SELECT wrapper, returns a single field, input must be encoded
 672          * Usually aborts on failure
 673          * If errors are explicitly ignored, returns FALSE on failure
 674          */
 675         function selectField( $table, $var, $cond='', $fname = 'DatabaseBase::selectField', $options = array() ) {
 676                 if ( !is_array( $options ) ) {
 677                         $options = array( $options );
 678                 }
 679                 $options['LIMIT'] = 1;
 680
 681                 $res = $this->select( $table, $var, $cond, $fname, $options );
 682                 if ( $res === false || !$this->numRows( $res ) ) {
 683                         return false;
 684                 }
 685                 $row = $this->fetchRow( $res );
 686                 if ( $row !== false ) {
 687                         return reset( $row );
 688                 } else {
 689                         return false;
 690                 }
 691         }
 692
 693         /**
 694          * Returns an optional USE INDEX clause to go after the table, and a
 695          * string to go at the end of the query
 696          *
 697          * @private
 698          *
 699          * @param $options Array: associative array of options to be turned into
 700          *              an SQL query, valid keys are listed in the function.
 701          * @return Array
 702          */
 703         function makeSelectOptions( $options ) {
 704                 $preLimitTail = $postLimitTail = '';
 705                 $startOpts = '';
 706
 707                 $noKeyOptions = array();
 708                 foreach ( $options as $key => $option ) {
 709                         if ( is_numeric( $key ) ) {
 710                                 $noKeyOptions[$option] = true;
 711                         }
 712                 }
 713
 714                 if ( isset( $options['GROUP BY'] ) ) $preLimitTail .= " GROUP BY {$options['GROUP BY']}";
 715                 if ( isset( $options['HAVING'] ) ) $preLimitTail .= " HAVING {$options['HAVING']}";
 716                 if ( isset( $options['ORDER BY'] ) ) $preLimitTail .= " ORDER BY {$options['ORDER BY']}";
 717
 718                 //if (isset($options['LIMIT'])) {
 719                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
 720                 //              isset($options['OFFSET']) ? $options['OFFSET']
 721                 //              : false);
 722                 //}
 723
 724                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) $postLimitTail .= ' FOR UPDATE';
 725                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) $postLimitTail .= ' LOCK IN SHARE MODE';
 726                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) $startOpts .= 'DISTINCT';
 727
 728                 # Various MySQL extensions
 729                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) $startOpts .= ' /*! STRAIGHT_JOIN */';
 730                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) $startOpts .= ' HIGH_PRIORITY';
 731                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) $startOpts .= ' SQL_BIG_RESULT';
 732                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) $startOpts .= ' SQL_BUFFER_RESULT';
 733                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) $startOpts .= ' SQL_SMALL_RESULT';
 734                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) $startOpts .= ' SQL_CALC_FOUND_ROWS';
 735                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) $startOpts .= ' SQL_CACHE';
 736                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) $startOpts .= ' SQL_NO_CACHE';
 737
 738                 if ( isset( $options['USE INDEX'] ) && ! is_array( $options['USE INDEX'] ) ) {
 739                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
 740                 } else {
 741                         $useIndex = '';
 742                 }
 743
 744                 return array( $startOpts, $useIndex, $preLimitTail, $postLimitTail );
 745         }
 746
 747         /**
 748          * SELECT wrapper
 749          *
 750          * @param $table   Mixed:  Array or string, table name(s) (prefix auto-added)
 751          * @param $vars    Mixed:  Array or string, field name(s) to be retrieved
 752          * @param $conds   Mixed:  Array or string, condition(s) for WHERE
 753          * @param $fname   String: Calling function name (use __METHOD__) for logs/profiling
 754          * @param $options Array:  Associative array of options (e.g. array('GROUP BY' => 'page_title')),
 755          *                         see DatabaseBase::makeSelectOptions code for list of supported stuff
 756          * @param $join_conds Array: Associative array of table join conditions (optional)
 757          *                           (e.g. array( 'page' => array('LEFT JOIN','page_latest=rev_id') )
 758          * @return mixed Database result resource (feed to DatabaseBase::fetchObject or whatever), or false on failure
 759          */
 760         function select( $table, $vars, $conds='', $fname = 'DatabaseBase::select', $options = array(), $join_conds = array() ) {
 761                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
 762                 return $this->query( $sql, $fname );
 763         }
 764
 765         /**
 766          * SELECT wrapper
 767          *
 768          * @param $table   Mixed:  Array or string, table name(s) (prefix auto-added)
 769          * @param $vars    Mixed:  Array or string, field name(s) to be retrieved
 770          * @param $conds   Mixed:  Array or string, condition(s) for WHERE
 771          * @param $fname   String: Calling function name (use __METHOD__) for logs/profiling
 772          * @param $options Array:  Associative array of options (e.g. array('GROUP BY' => 'page_title')),
 773          *                         see DatabaseBase::makeSelectOptions code for list of supported stuff
 774          * @param $join_conds Array: Associative array of table join conditions (optional)
 775          *                           (e.g. array( 'page' => array('LEFT JOIN','page_latest=rev_id') )
 776          * @return string, the SQL text
 777          */
 778         function selectSQLText( $table, $vars, $conds='', $fname = 'DatabaseBase::select', $options = array(), $join_conds = array() ) {
 779                 if( is_array( $vars ) ) {
 780                         $vars = implode( ',', $vars );
 781                 }
 782                 if( !is_array( $options ) ) {
 783                         $options = array( $options );
 784                 }
 785                 if( is_array( $table ) ) {
 786                         if ( !empty($join_conds) || ( isset( $options['USE INDEX'] ) && is_array( @$options['USE INDEX'] ) ) )
 787                                 $from = ' FROM ' . $this->tableNamesWithUseIndexOrJOIN( $table, @$options['USE INDEX'], $join_conds );
 788                         else
 789                                 $from = ' FROM ' . implode( ',', array_map( array( &$this, 'tableName' ), $table ) );
 790                 } elseif ($table!='') {
 791                         if ($table{0}==' ') {
 792                                 $from = ' FROM ' . $table;
 793                         } else {
 794                                 $from = ' FROM ' . $this->tableName( $table );
 795                         }
 796                 } else {
 797                         $from = '';
 798                 }
 799
 800                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail ) = $this->makeSelectOptions( $options );
 801
 802                 if( !empty( $conds ) ) {
 803                         if ( is_array( $conds ) ) {
 804                                 $conds = $this->makeList( $conds, LIST_AND );
 805                         }
 806                         $sql = "SELECT $startOpts $vars $from $useIndex WHERE $conds $preLimitTail";
 807                 } else {
 808                         $sql = "SELECT $startOpts $vars $from $useIndex $preLimitTail";
 809                 }
 810
 811                 if (isset($options['LIMIT']))
 812                         $sql = $this->limitResult($sql, $options['LIMIT'],
 813                                 isset($options['OFFSET']) ? $options['OFFSET'] : false);
 814                 $sql = "$sql $postLimitTail";
 815
 816                 if (isset($options['EXPLAIN'])) {
 817                         $sql = 'EXPLAIN ' . $sql;
 818                 }
 819                 return $sql;
 820         }
 821
 822         /**
 823          * Single row SELECT wrapper
 824          * Aborts or returns FALSE on error
 825          *
 826          * @param $table String: table name
 827          * @param $vars String: the selected variables
 828          * @param $conds Array: a condition map, terms are ANDed together.
 829          *   Items with numeric keys are taken to be literal conditions
 830          * Takes an array of selected variables, and a condition map, which is ANDed
 831          * e.g: selectRow( "page", array( "page_id" ), array( "page_namespace" =>
 832          * NS_MAIN, "page_title" => "Astronomy" ) )   would return an object where
 833          * $obj- >page_id is the ID of the Astronomy article
 834          * @param $fname String: Calling function name
 835          * @param $options Array
 836          * @param $join_conds Array
 837          *
 838          * @todo migrate documentation to phpdocumentor format
 839          */
 840         function selectRow( $table, $vars, $conds, $fname = 'DatabaseBase::selectRow', $options = array(), $join_conds = array() ) {
 841                 $options['LIMIT'] = 1;
 842                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
 843                 if ( $res === false )
 844                         return false;
 845                 if ( !$this->numRows($res) ) {
 846                         return false;
 847                 }
 848                 $obj = $this->fetchObject( $res );
 849                 return $obj;
 850         }
 851
 852         /**
 853          * Estimate rows in dataset
 854          * Returns estimated count - not necessarily an accurate estimate across different databases,
 855          * so use sparingly
 856          * Takes same arguments as DatabaseBase::select()
 857          *
 858          * @param $table String: table name
 859          * @param $vars Array: unused
 860          * @param $conds Array: filters on the table
 861          * @param $fname String: function name for profiling
 862          * @param $options Array: options for select
 863          * @return Integer: row count
 864          */
 865         public function estimateRowCount( $table, $vars='*', $conds='', $fname = 'DatabaseBase::estimateRowCount', $options = array() ) {
 866                 $rows = 0;
 867                 $res = $this->select ( $table, 'COUNT(*) AS rowcount', $conds, $fname, $options );
 868                 if ( $res ) {
 869                         $row = $this->fetchRow( $res );
 870                         $rows = ( isset( $row['rowcount'] ) ) ? $row['rowcount'] : 0;
 871                 }
 872                 return $rows;
 873         }
 874
 875         /**
 876          * Removes most variables from an SQL query and replaces them with X or N for numbers.
 877          * It's only slightly flawed. Don't use for anything important.
 878          *
 879          * @param $sql String: A SQL Query
 880          */
 881         static function generalizeSQL( $sql ) {
 882                 # This does the same as the regexp below would do, but in such a way
 883                 # as to avoid crashing php on some large strings.
 884                 # $sql = preg_replace ( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql);
 885
 886                 $sql = str_replace ( "\\\\", '', $sql);
 887                 $sql = str_replace ( "\\'", '', $sql);
 888                 $sql = str_replace ( "\\\"", '', $sql);
 889                 $sql = preg_replace ("/'.*'/s", "'X'", $sql);
 890                 $sql = preg_replace ('/".*"/s', "'X'", $sql);
 891
 892                 # All newlines, tabs, etc replaced by single space
 893                 $sql = preg_replace ( '/\s+/', ' ', $sql);
 894
 895                 # All numbers => N
 896                 $sql = preg_replace ('/-?[0-9]+/s', 'N', $sql);
 897
 898                 return $sql;
 899         }
 900
 901         /**
 902          * Determines whether a field exists in a table
 903          *
 904          * @param $table String: table name
 905          * @param $field String: filed to check on that table
 906          * @param $fname String: calling function name (optional)
 907          * @return Boolean: whether $table has filed $field
 908          */
 909         function fieldExists( $table, $field, $fname = 'DatabaseBase::fieldExists' ) {
 910                 $info = $this->fieldInfo( $table, $field );
 911                 return (bool)$info;
 912         }
 913
 914         /**
 915          * Determines whether an index exists
 916          * Usually aborts on failure
 917          * If errors are explicitly ignored, returns NULL on failure
 918          */
 919         function indexExists( $table, $index, $fname = 'DatabaseBase::indexExists' ) {
 920                 $info = $this->indexInfo( $table, $index, $fname );
 921                 if ( is_null( $info ) ) {
 922                         return null;
 923                 } else {
 924                         return $info !== false;
 925                 }
 926         }
 927
 928
 929         /**
 930          * Get information about an index into an object
 931          * Returns false if the index does not exist
 932          */
 933         function indexInfo( $table, $index, $fname = 'DatabaseBase::indexInfo' ) {
 934                 # SHOW INDEX works in MySQL 3.23.58, but SHOW INDEXES does not.
 935                 # SHOW INDEX should work for 3.x and up:
 936                 # http://dev.mysql.com/doc/mysql/en/SHOW_INDEX.html
 937                 $table = $this->tableName( $table );
 938                 $index = $this->indexName( $index );
 939                 $sql = 'SHOW INDEX FROM '.$table;
 940                 $res = $this->query( $sql, $fname );
 941                 if ( !$res ) {
 942                         return null;
 943                 }
 944
 945                 $result = array();
 946                 while ( $row = $this->fetchObject( $res ) ) {
 947                         if ( $row->Key_name == $index ) {
 948                                 $result[] = $row;
 949                         }
 950                 }
 951
 952                 return empty($result) ? false : $result;
 953         }
 954
 955         /**
 956          * Query whether a given table exists
 957          */
 958         function tableExists( $table ) {
 959                 $table = $this->tableName( $table );
 960                 $old = $this->ignoreErrors( true );
 961                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1" );
 962                 $this->ignoreErrors( $old );
 963                 return (bool)$res;
 964         }
 965
 966         /**
 967          * mysql_field_type() wrapper
 968          */
 969         function fieldType( $res, $index ) {
 970                 if ( $res instanceof ResultWrapper ) {
 971                         $res = $res->result;
 972                 }
 973                 return mysql_field_type( $res, $index );
 974         }
 975
 976         /**
 977          * Determines if a given index is unique
 978          */
 979         function indexUnique( $table, $index ) {
 980                 $indexInfo = $this->indexInfo( $table, $index );
 981                 if ( !$indexInfo ) {
 982                         return null;
 983                 }
 984                 return !$indexInfo[0]->Non_unique;
 985         }
 986
 987         /**
 988          * INSERT wrapper, inserts an array into a table
 989          *
 990          * $a may be a single associative array, or an array of these with numeric keys, for
 991          * multi-row insert.
 992          *
 993          * Usually aborts on failure
 994          * If errors are explicitly ignored, returns success
 995          *
 996          * @param $table   String: table name (prefix auto-added)
 997          * @param $a       Array: Array of rows to insert
 998          * @param $fname   String: Calling function name (use __METHOD__) for logs/profiling
 999          * @param $options Mixed: Associative array of options
1000          *
1001          * @return bool
1002          */
1003         function insert( $table, $a, $fname = 'DatabaseBase::insert', $options = array() ) {
1004                 # No rows to insert, easy just return now
1005                 if ( !count( $a ) ) {
1006                         return true;
1007                 }
1008
1009                 $table = $this->tableName( $table );
1010                 if ( !is_array( $options ) ) {
1011                         $options = array( $options );
1012                 }
1013                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1014                         $multi = true;
1015                         $keys = array_keys( $a[0] );
1016                 } else {
1017                         $multi = false;
1018                         $keys = array_keys( $a );
1019                 }
1020
1021                 $sql = 'INSERT ' . implode( ' ', $options ) .
1022                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1023
1024                 if ( $multi ) {
1025                         $first = true;
1026                         foreach ( $a as $row ) {
1027                                 if ( $first ) {
1028                                         $first = false;
1029                                 } else {
1030                                         $sql .= ',';
1031                                 }
1032                                 $sql .= '(' . $this->makeList( $row ) . ')';
1033                         }
1034                 } else {
1035                         $sql .= '(' . $this->makeList( $a ) . ')';
1036                 }
1037
1038                 return (bool)$this->query( $sql, $fname );
1039         }
1040
1041         /**
1042          * Make UPDATE options for the DatabaseBase::update function
1043          *
1044          * @private
1045          * @param $options Array: The options passed to DatabaseBase::update
1046          * @return string
1047          */
1048         function makeUpdateOptions( $options ) {
1049                 if( !is_array( $options ) ) {
1050                         $options = array( $options );
1051                 }
1052                 $opts = array();
1053                 if ( in_array( 'LOW_PRIORITY', $options ) ) {
1054                         $opts[] = $this->lowPriorityOption();
1055                 }
1056                 if ( in_array( 'IGNORE', $options ) ) {
1057                         $opts[] = 'IGNORE';
1058                 }
1059                 return implode(' ', $opts);
1060         }
1061
1062         /**
1063          * UPDATE wrapper, takes a condition array and a SET array
1064          *
1065          * @param $table  String: The table to UPDATE
1066          * @param $values Array:  An array of values to SET
1067          * @param $conds  Array:  An array of conditions (WHERE). Use '*' to update all rows.
1068          * @param $fname  String: The Class::Function calling this function
1069          *                        (for the log)
1070          * @param $options Array: An array of UPDATE options, can be one or
1071          *                        more of IGNORE, LOW_PRIORITY
1072          * @return Boolean
1073          */
1074         function update( $table, $values, $conds, $fname = 'DatabaseBase::update', $options = array() ) {
1075                 $table = $this->tableName( $table );
1076                 $opts = $this->makeUpdateOptions( $options );
1077                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1078                 if ( $conds != '*' ) {
1079                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1080                 }
1081                 return $this->query( $sql, $fname );
1082         }
1083
1084         /**
1085          * Makes an encoded list of strings from an array
1086          * $mode:
1087          *        LIST_COMMA         - comma separated, no field names
1088          *        LIST_AND           - ANDed WHERE clause (without the WHERE)
1089          *        LIST_OR            - ORed WHERE clause (without the WHERE)
1090          *        LIST_SET           - comma separated with field names, like a SET clause
1091          *        LIST_NAMES         - comma separated field names
1092          */
1093         function makeList( $a, $mode = LIST_COMMA ) {
1094                 if ( !is_array( $a ) ) {
1095                         throw new DBUnexpectedError( $this, 'DatabaseBase::makeList called with incorrect parameters' );
1096                 }
1097
1098                 $first = true;
1099                 $list = '';
1100                 foreach ( $a as $field => $value ) {
1101                         if ( !$first ) {
1102                                 if ( $mode == LIST_AND ) {
1103                                         $list .= ' AND ';
1104                                 } elseif($mode == LIST_OR) {
1105                                         $list .= ' OR ';
1106                                 } else {
1107                                         $list .= ',';
1108                                 }
1109                         } else {
1110                                 $first = false;
1111                         }
1112                         if ( ($mode == LIST_AND || $mode == LIST_OR) && is_numeric( $field ) ) {
1113                                 $list .= "($value)";
1114                         } elseif ( ($mode == LIST_SET) && is_numeric( $field ) ) {
1115                                 $list .= "$value";
1116                         } elseif ( ($mode == LIST_AND || $mode == LIST_OR) && is_array($value) ) {
1117                                 if( count( $value ) == 0 ) {
1118                                         throw new MWException( __METHOD__.': empty input' );
1119                                 } elseif( count( $value ) == 1 ) {
1120                                         // Special-case single values, as IN isn't terribly efficient
1121                                         // Don't necessarily assume the single key is 0; we don't
1122                                         // enforce linear numeric ordering on other arrays here.
1123                                         $value = array_values( $value );
1124                                         $list .= $field." = ".$this->addQuotes( $value[0] );
1125                                 } else {
1126                                         $list .= $field." IN (".$this->makeList($value).") ";
1127                                 }
1128                         } elseif( $value === null ) {
1129                                 if ( $mode == LIST_AND || $mode == LIST_OR ) {
1130                                         $list .= "$field IS ";
1131                                 } elseif ( $mode == LIST_SET ) {
1132                                         $list .= "$field = ";
1133                                 }
1134                                 $list .= 'NULL';
1135                         } else {
1136                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
1137                                         $list .= "$field = ";
1138                                 }
1139                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
1140                         }
1141                 }
1142                 return $list;
1143         }
1144
1145         /**
1146          * Build a partial where clause from a 2-d array such as used for LinkBatch.
1147          * The keys on each level may be either integers or strings.
1148          *
1149          * @param $data Array: organized as 2-d array(baseKeyVal => array(subKeyVal => <ignored>, ...), ...)
1150          * @param $baseKey String: field name to match the base-level keys to (eg 'pl_namespace')
1151          * @param $subKey String: field name to match the sub-level keys to (eg 'pl_title')
1152          * @return Mixed: string SQL fragment, or false if no items in array.
1153          */
1154         function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1155                 $conds = array();
1156                 foreach ( $data as $base => $sub ) {
1157                         if ( count( $sub ) ) {
1158                                 $conds[] = $this->makeList(
1159                                         array( $baseKey => $base, $subKey => array_keys( $sub ) ),
1160                                         LIST_AND);
1161                         }
1162                 }
1163
1164                 if ( $conds ) {
1165                         return $this->makeList( $conds, LIST_OR );
1166                 } else {
1167                         // Nothing to search for...
1168                         return false;
1169                 }
1170         }
1171
1172         /**
1173          * Bitwise operations
1174          */
1175
1176         function bitNot($field) {
1177                 return "(~$field)";
1178         }
1179
1180         function bitAnd($fieldLeft, $fieldRight) {
1181                 return "($fieldLeft & $fieldRight)";
1182         }
1183
1184         function bitOr($fieldLeft, $fieldRight) {
1185                 return "($fieldLeft | $fieldRight)";
1186         }
1187
1188         /**
1189          * Change the current database
1190          *
1191          * @return bool Success or failure
1192          */
1193         function selectDB( $db ) {
1194                 # Stub.  Shouldn't cause serious problems if it's not overridden, but
1195                 # if your database engine supports a concept similar to MySQL's
1196                 # databases you may as well.  TODO: explain what exactly will fail if
1197                 # this is not overridden.
1198                 return true;
1199         }
1200
1201         /**
1202          * Get the current DB name
1203          */
1204         function getDBname() {
1205                 return $this->mDBname;
1206         }
1207
1208         /**
1209          * Get the server hostname or IP address
1210          */
1211         function getServer() {
1212                 return $this->mServer;
1213         }
1214
1215         /**
1216          * Format a table name ready for use in constructing an SQL query
1217          *
1218          * This does two important things: it quotes the table names to clean them up,
1219          * and it adds a table prefix if only given a table name with no quotes.
1220          *
1221          * All functions of this object which require a table name call this function
1222          * themselves. Pass the canonical name to such functions. This is only needed
1223          * when calling query() directly.
1224          *
1225          * @param $name String: database table name
1226          * @return String: full database name
1227          */
1228         function tableName( $name ) {
1229                 global $wgSharedDB, $wgSharedPrefix, $wgSharedTables;
1230                 # Skip the entire process when we have a string quoted on both ends.
1231                 # Note that we check the end so that we will still quote any use of
1232                 # use of `database`.table. But won't break things if someone wants
1233                 # to query a database table with a dot in the name.
1234                 if ( $name[0] == '`' && substr( $name, -1, 1 ) == '`' ) {
1235                         return $name;
1236                 }
1237
1238                 # Lets test for any bits of text that should never show up in a table
1239                 # name. Basically anything like JOIN or ON which are actually part of
1240                 # SQL queries, but may end up inside of the table value to combine
1241                 # sql. Such as how the API is doing.
1242                 # Note that we use a whitespace test rather than a \b test to avoid
1243                 # any remote case where a word like on may be inside of a table name
1244                 # surrounded by symbols which may be considered word breaks.
1245                 if( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1246                         return $name;
1247                 }
1248
1249                 # Split database and table into proper variables.
1250                 # We reverse the explode so that database.table and table both output
1251                 # the correct table.
1252                 $dbDetails = array_reverse( explode( '.', $name, 2 ) );
1253                 if( isset( $dbDetails[1] ) ) {
1254                         @list( $table, $database ) = $dbDetails;
1255                 } else {
1256                         @list( $table ) = $dbDetails;
1257                 }
1258                 $prefix = $this->mTablePrefix; # Default prefix
1259
1260                 # A database name has been specified in input. Quote the table name
1261                 # because we don't want any prefixes added.
1262                 if( isset($database) ) {
1263                         $table = ( $table[0] == '`' ? $table : "`{$table}`" );
1264                 }
1265
1266                 # Note that we use the long format because php will complain in in_array if
1267                 # the input is not an array, and will complain in is_array if it is not set.
1268                 if( !isset( $database ) # Don't use shared database if pre selected.
1269                  && isset( $wgSharedDB ) # We have a shared database
1270                  && $table[0] != '`' # Paranoia check to prevent shared tables listing '`table`'
1271                  && isset( $wgSharedTables )
1272                  && is_array( $wgSharedTables )
1273                  && in_array( $table, $wgSharedTables ) ) { # A shared table is selected
1274                         $database = $wgSharedDB;
1275                         $prefix   = isset( $wgSharedPrefix ) ? $wgSharedPrefix : $prefix;
1276                 }
1277
1278                 # Quote the $database and $table and apply the prefix if not quoted.
1279                 if( isset($database) ) {
1280                         $database = ( $database[0] == '`' ? $database : "`{$database}`" );
1281                 }
1282                 $table = ( $table[0] == '`' ? $table : "`{$prefix}{$table}`" );
1283
1284                 # Merge our database and table into our final table name.
1285                 $tableName = ( isset($database) ? "{$database}.{$table}" : "{$table}" );
1286
1287                 # We're finished, return.
1288                 return $tableName;
1289         }
1290
1291         /**
1292          * Fetch a number of table names into an array
1293          * This is handy when you need to construct SQL for joins
1294          *
1295          * Example:
1296          * extract($dbr->tableNames('user','watchlist'));
1297          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1298          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1299          */
1300         public function tableNames() {
1301                 $inArray = func_get_args();
1302                 $retVal = array();
1303                 foreach ( $inArray as $name ) {
1304                         $retVal[$name] = $this->tableName( $name );
1305                 }
1306                 return $retVal;
1307         }
1308
1309         /**
1310          * Fetch a number of table names into an zero-indexed numerical array
1311          * This is handy when you need to construct SQL for joins
1312          *
1313          * Example:
1314          * list( $user, $watchlist ) = $dbr->tableNamesN('user','watchlist');
1315          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1316          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1317          */
1318         public function tableNamesN() {
1319                 $inArray = func_get_args();
1320                 $retVal = array();
1321                 foreach ( $inArray as $name ) {
1322                         $retVal[] = $this->tableName( $name );
1323                 }
1324                 return $retVal;
1325         }
1326
1327         /**
1328          * @private
1329          */
1330         function tableNamesWithUseIndexOrJOIN( $tables, $use_index = array(), $join_conds = array() ) {
1331                 $ret = array();
1332                 $retJOIN = array();
1333                 $use_index_safe = is_array($use_index) ? $use_index : array();
1334                 $join_conds_safe = is_array($join_conds) ? $join_conds : array();
1335                 foreach ( $tables as $table ) {
1336                         // Is there a JOIN and INDEX clause for this table?
1337                         if ( isset($join_conds_safe[$table]) && isset($use_index_safe[$table]) ) {
1338                                 $tableClause = $join_conds_safe[$table][0] . ' ' . $this->tableName( $table );
1339                                 $tableClause .= ' ' . $this->useIndexClause( implode( ',', (array)$use_index_safe[$table] ) );
1340                                 $on = $this->makeList((array)$join_conds_safe[$table][1], LIST_AND);
1341                                 if ( $on != '' ) {
1342                                         $tableClause .= ' ON (' . $on . ')';
1343                                 }
1344                                 $retJOIN[] = $tableClause;
1345                         // Is there an INDEX clause?
1346                         } else if ( isset($use_index_safe[$table]) ) {
1347                                 $tableClause = $this->tableName( $table );
1348                                 $tableClause .= ' ' . $this->useIndexClause( implode( ',', (array)$use_index_safe[$table] ) );
1349                                 $ret[] = $tableClause;
1350                         // Is there a JOIN clause?
1351                         } else if ( isset($join_conds_safe[$table]) ) {
1352                                 $tableClause = $join_conds_safe[$table][0] . ' ' . $this->tableName( $table );
1353                                 $on = $this->makeList((array)$join_conds_safe[$table][1], LIST_AND);
1354                                 if ( $on != '' ) {
1355                                         $tableClause .= ' ON (' . $on . ')';
1356                                 }
1357                                 $retJOIN[] = $tableClause;
1358                         } else {
1359                                 $tableClause = $this->tableName( $table );
1360                                 $ret[] = $tableClause;
1361                         }
1362                 }
1363                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
1364                 $straightJoins = !empty($ret) ? implode( ',', $ret ) : "";
1365                 $otherJoins = !empty($retJOIN) ? implode( ' ', $retJOIN ) : "";
1366                 // Compile our final table clause
1367                 return implode(' ',array($straightJoins,$otherJoins) );
1368         }
1369
1370         /**
1371          * Get the name of an index in a given table
1372          */
1373         function indexName( $index ) {
1374                 // Backwards-compatibility hack
1375                 $renamed = array(
1376                         'ar_usertext_timestamp' => 'usertext_timestamp',
1377                         'un_user_id'            => 'user_id',
1378                         'un_user_ip'            => 'user_ip',
1379                 );
1380                 if( isset( $renamed[$index] ) ) {
1381                         return $renamed[$index];
1382                 } else {
1383                         return $index;
1384                 }
1385         }
1386
1387         /**
1388          * If it's a string, adds quotes and backslashes
1389          * Otherwise returns as-is
1390          */
1391         function addQuotes( $s ) {
1392                 if ( $s === null ) {
1393                         return 'NULL';
1394                 } else {
1395                         # This will also quote numeric values. This should be harmless,
1396                         # and protects against weird problems that occur when they really
1397                         # _are_ strings such as article titles and string->number->string
1398                         # conversion is not 1:1.
1399                         return "'" . $this->strencode( $s ) . "'";
1400                 }
1401         }
1402
1403         /**
1404          * Escape string for safe LIKE usage.
1405          * WARNING: you should almost never use this function directly,
1406          * instead use buildLike() that escapes everything automatically
1407          * Deprecated in 1.17, warnings in 1.17, removed in ???
1408          */
1409         public function escapeLike( $s ) {
1410                 wfDeprecated( __METHOD__ );
1411                 return $this->escapeLikeInternal( $s );
1412         }
1413
1414         protected function escapeLikeInternal( $s ) {
1415                 $s = str_replace( '\\', '\\\\', $s );
1416                 $s = $this->strencode( $s );
1417                 $s = str_replace( array( '%', '_' ), array( '\%', '\_' ), $s );
1418                 return $s;
1419         }
1420
1421         /**
1422          * LIKE statement wrapper, receives a variable-length argument list with parts of pattern to match
1423          * containing either string literals that will be escaped or tokens returned by anyChar() or anyString().
1424          * Alternatively, the function could be provided with an array of aforementioned parameters.
1425          *
1426          * Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns a LIKE clause that searches
1427          * for subpages of 'My page title'.
1428          * Alternatively: $pattern = array( 'My_page_title/', $dbr->anyString() ); $query .= $dbr->buildLike( $pattern );
1429          *
1430          * @since 1.16
1431          * @return String: fully built LIKE statement
1432          */
1433         function buildLike() {
1434                 $params = func_get_args();
1435                 if (count($params) > 0 && is_array($params[0])) {
1436                         $params = $params[0];
1437                 }
1438
1439                 $s = '';
1440                 foreach( $params as $value) {
1441                         if( $value instanceof LikeMatch ) {
1442                                 $s .= $value->toString();
1443                         } else {
1444                                 $s .= $this->escapeLikeInternal( $value );
1445                         }
1446                 }
1447                 return " LIKE '" . $s . "' ";
1448         }
1449
1450         /**
1451          * Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
1452          */
1453         function anyChar() {
1454                 return new LikeMatch( '_' );
1455         }
1456
1457         /**
1458          * Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
1459          */
1460         function anyString() {
1461                 return new LikeMatch( '%' );
1462         }
1463
1464         /**
1465          * Returns an appropriately quoted sequence value for inserting a new row.
1466          * MySQL has autoincrement fields, so this is just NULL. But the PostgreSQL
1467          * subclass will return an integer, and save the value for insertId()
1468          */
1469         function nextSequenceValue( $seqName ) {
1470                 return null;
1471         }
1472
1473         /**
1474          * USE INDEX clause.  Unlikely to be useful for anything but MySQL.  This
1475          * is only needed because a) MySQL must be as efficient as possible due to
1476          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
1477          * which index to pick.  Anyway, other databases might have different
1478          * indexes on a given table.  So don't bother overriding this unless you're
1479          * MySQL.
1480          */
1481         function useIndexClause( $index ) {
1482                 return '';
1483         }
1484
1485         /**
1486          * REPLACE query wrapper
1487          * PostgreSQL simulates this with a DELETE followed by INSERT
1488          * $row is the row to insert, an associative array
1489          * $uniqueIndexes is an array of indexes. Each element may be either a
1490          * field name or an array of field names
1491          *
1492          * It may be more efficient to leave off unique indexes which are unlikely to collide.
1493          * However if you do this, you run the risk of encountering errors which wouldn't have
1494          * occurred in MySQL
1495          *
1496          * @param $table String: The table to replace the row(s) in.
1497          * @param $uniqueIndexes Array: An associative array of indexes
1498          * @param $rows Array: Array of rows to replace
1499          * @param $fname String: Calling function name (use __METHOD__) for logs/profiling
1500          */
1501         function replace( $table, $uniqueIndexes, $rows, $fname = 'DatabaseBase::replace' ) {
1502                 $table = $this->tableName( $table );
1503
1504                 # Single row case
1505                 if ( !is_array( reset( $rows ) ) ) {
1506                         $rows = array( $rows );
1507                 }
1508
1509                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) .') VALUES ';
1510                 $first = true;
1511                 foreach ( $rows as $row ) {
1512                         if ( $first ) {
1513                                 $first = false;
1514                         } else {
1515                                 $sql .= ',';
1516                         }
1517                         $sql .= '(' . $this->makeList( $row ) . ')';
1518                 }
1519                 return $this->query( $sql, $fname );
1520         }
1521
1522         /**
1523          * DELETE where the condition is a join
1524          * MySQL does this with a multi-table DELETE syntax, PostgreSQL does it with sub-selects
1525          *
1526          * For safety, an empty $conds will not delete everything. If you want to delete all rows where the
1527          * join condition matches, set $conds='*'
1528          *
1529          * DO NOT put the join condition in $conds
1530          *
1531          * @param $delTable String: The table to delete from.
1532          * @param $joinTable String: The other table.
1533          * @param $delVar String: The variable to join on, in the first table.
1534          * @param $joinVar String: The variable to join on, in the second table.
1535          * @param $conds Array: Condition array of field names mapped to variables, ANDed together in the WHERE clause
1536          * @param $fname String: Calling function name (use __METHOD__) for logs/profiling
1537          */
1538         function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds, $fname = 'DatabaseBase::deleteJoin' ) {
1539                 if ( !$conds ) {
1540                         throw new DBUnexpectedError( $this, 'DatabaseBase::deleteJoin() called with empty $conds' );
1541                 }
1542
1543                 $delTable = $this->tableName( $delTable );
1544                 $joinTable = $this->tableName( $joinTable );
1545                 $sql = "DELETE $delTable FROM $delTable, $joinTable WHERE $delVar=$joinVar ";
1546                 if ( $conds != '*' ) {
1547                         $sql .= ' AND ' . $this->makeList( $conds, LIST_AND );
1548                 }
1549
1550                 return $this->query( $sql, $fname );
1551         }
1552
1553         /**
1554          * Returns the size of a text field, or -1 for "unlimited"
1555          */
1556         function textFieldSize( $table, $field ) {
1557                 $table = $this->tableName( $table );
1558                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
1559                 $res = $this->query( $sql, 'DatabaseBase::textFieldSize' );
1560                 $row = $this->fetchObject( $res );
1561
1562                 $m = array();
1563                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
1564                         $size = $m[1];
1565                 } else {
1566                         $size = -1;
1567                 }
1568                 return $size;
1569         }
1570
1571         /**
1572          * A string to insert into queries to show that they're low-priority, like
1573          * MySQL's LOW_PRIORITY.  If no such feature exists, return an empty
1574          * string and nothing bad should happen.
1575          *
1576          * @return string Returns the text of the low priority option if it is supported, or a blank string otherwise
1577          */
1578         function lowPriorityOption() {
1579                 return '';
1580         }
1581
1582         /**
1583          * DELETE query wrapper
1584          *
1585          * Use $conds == "*" to delete all rows
1586          */
1587         function delete( $table, $conds, $fname = 'DatabaseBase::delete' ) {
1588                 if ( !$conds ) {
1589                         throw new DBUnexpectedError( $this, 'DatabaseBase::delete() called with no conditions' );
1590                 }
1591                 $table = $this->tableName( $table );
1592                 $sql = "DELETE FROM $table";
1593                 if ( $conds != '*' ) {
1594                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1595                 }
1596                 return $this->query( $sql, $fname );
1597         }
1598
1599         /**
1600          * INSERT SELECT wrapper
1601          * $varMap must be an associative array of the form array( 'dest1' => 'source1', ...)
1602          * Source items may be literals rather than field names, but strings should be quoted with DatabaseBase::addQuotes()
1603          * $conds may be "*" to copy the whole table
1604          * srcTable may be an array of tables.
1605          */
1606         function insertSelect( $destTable, $srcTable, $varMap, $conds, $fname = 'DatabaseBase::insertSelect',
1607                 $insertOptions = array(), $selectOptions = array() )
1608         {
1609                 $destTable = $this->tableName( $destTable );
1610                 if ( is_array( $insertOptions ) ) {
1611                         $insertOptions = implode( ' ', $insertOptions );
1612                 }
1613                 if( !is_array( $selectOptions ) ) {
1614                         $selectOptions = array( $selectOptions );
1615                 }
1616                 list( $startOpts, $useIndex, $tailOpts ) = $this->makeSelectOptions( $selectOptions );
1617                 if( is_array( $srcTable ) ) {
1618                         $srcTable =  implode( ',', array_map( array( &$this, 'tableName' ), $srcTable ) );
1619                 } else {
1620                         $srcTable = $this->tableName( $srcTable );
1621                 }
1622                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
1623                         " SELECT $startOpts " . implode( ',', $varMap ) .
1624                         " FROM $srcTable $useIndex ";
1625                 if ( $conds != '*' ) {
1626                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1627                 }
1628                 $sql .= " $tailOpts";
1629                 return $this->query( $sql, $fname );
1630         }
1631
1632         /**
1633          * Construct a LIMIT query with optional offset.  This is used for query
1634          * pages.  The SQL should be adjusted so that only the first $limit rows
1635          * are returned.  If $offset is provided as well, then the first $offset
1636          * rows should be discarded, and the next $limit rows should be returned.
1637          * If the result of the query is not ordered, then the rows to be returned
1638          * are theoretically arbitrary.
1639          *
1640          * $sql is expected to be a SELECT, if that makes a difference.  For
1641          * UPDATE, limitResultForUpdate should be used.
1642          *
1643          * The version provided by default works in MySQL and SQLite.  It will very
1644          * likely need to be overridden for most other DBMSes.
1645          *
1646          * @param $sql String: SQL query we will append the limit too
1647          * @param $limit Integer: the SQL limit
1648          * @param $offset Integer the SQL offset (default false)
1649          */
1650         function limitResult( $sql, $limit, $offset=false ) {
1651                 if( !is_numeric( $limit ) ) {
1652                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
1653                 }
1654                 return "$sql LIMIT "
1655                                 . ( (is_numeric($offset) && $offset != 0) ? "{$offset}," : "" )
1656                                 . "{$limit} ";
1657         }
1658         function limitResultForUpdate( $sql, $num ) {
1659                 return $this->limitResult( $sql, $num, 0 );
1660         }
1661
1662         /**
1663          * Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
1664          * within the UNION construct.
1665          * @return Boolean
1666          */
1667         function unionSupportsOrderAndLimit() {
1668                 return true; // True for almost every DB supported
1669         }
1670
1671         /**
1672          * Construct a UNION query
1673          * This is used for providing overload point for other DB abstractions
1674          * not compatible with the MySQL syntax.
1675          * @param $sqls Array: SQL statements to combine
1676          * @param $all Boolean: use UNION ALL
1677          * @return String: SQL fragment
1678          */
1679         function unionQueries($sqls, $all) {
1680                 $glue = $all ? ') UNION ALL (' : ') UNION (';
1681                 return '('.implode( $glue, $sqls ) . ')';
1682         }
1683
1684         /**
1685          * Returns an SQL expression for a simple conditional.  This doesn't need
1686          * to be overridden unless CASE isn't supported in your DBMS.
1687          *
1688          * @param $cond String: SQL expression which will result in a boolean value
1689          * @param $trueVal String: SQL expression to return if true
1690          * @param $falseVal String: SQL expression to return if false
1691          * @return String: SQL fragment
1692          */
1693         function conditional( $cond, $trueVal, $falseVal ) {
1694                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
1695         }
1696
1697         /**
1698          * Returns a comand for str_replace function in SQL query.
1699          * Uses REPLACE() in MySQL
1700          *
1701          * @param $orig String: column to modify
1702          * @param $old String: column to seek
1703          * @param $new String: column to replace with
1704          */
1705         function strreplace( $orig, $old, $new ) {
1706                 return "REPLACE({$orig}, {$old}, {$new})";
1707         }
1708
1709         /**
1710          * Determines if the last failure was due to a deadlock
1711          * STUB
1712          */
1713         function wasDeadlock() {
1714                 return false;
1715         }
1716
1717         /**
1718          * Determines if the last query error was something that should be dealt
1719          * with by pinging the connection and reissuing the query.
1720          * STUB
1721          */
1722         function wasErrorReissuable() {
1723                 return false;
1724         }
1725
1726         /**
1727          * Determines if the last failure was due to the database being read-only.
1728          * STUB
1729          */
1730         function wasReadOnlyError() {
1731                 return false;
1732         }
1733
1734         /**
1735          * Perform a deadlock-prone transaction.
1736          *
1737          * This function invokes a callback function to perform a set of write
1738          * queries. If a deadlock occurs during the processing, the transaction
1739          * will be rolled back and the callback function will be called again.
1740          *
1741          * Usage:
1742          *   $dbw->deadlockLoop( callback, ... );
1743          *
1744          * Extra arguments are passed through to the specified callback function.
1745          *
1746          * Returns whatever the callback function returned on its successful,
1747          * iteration, or false on error, for example if the retry limit was
1748          * reached.
1749          */
1750         function deadlockLoop() {
1751                 $myFname = 'DatabaseBase::deadlockLoop';
1752
1753                 $this->begin();
1754                 $args = func_get_args();
1755                 $function = array_shift( $args );
1756                 $oldIgnore = $this->ignoreErrors( true );
1757                 $tries = DEADLOCK_TRIES;
1758                 if ( is_array( $function ) ) {
1759                         $fname = $function[0];
1760                 } else {
1761                         $fname = $function;
1762                 }
1763                 do {
1764                         $retVal = call_user_func_array( $function, $args );
1765                         $error = $this->lastError();
1766                         $errno = $this->lastErrno();
1767                         $sql = $this->lastQuery();
1768
1769                         if ( $errno ) {
1770                                 if ( $this->wasDeadlock() ) {
1771                                         # Retry
1772                                         usleep( mt_rand( DEADLOCK_DELAY_MIN, DEADLOCK_DELAY_MAX ) );
1773                                 } else {
1774                                         $this->reportQueryError( $error, $errno, $sql, $fname );
1775                                 }
1776                         }
1777                 } while( $this->wasDeadlock() && --$tries > 0 );
1778                 $this->ignoreErrors( $oldIgnore );
1779                 if ( $tries <= 0 ) {
1780                         $this->rollback( $myFname );
1781                         $this->reportQueryError( $error, $errno, $sql, $fname );
1782                         return false;
1783                 } else {
1784                         $this->commit( $myFname );
1785                         return $retVal;
1786                 }
1787         }
1788
1789         /**
1790          * Do a SELECT MASTER_POS_WAIT()
1791          *
1792          * @param $pos MySQLMasterPos object
1793          * @param $timeout Integer: the maximum number of seconds to wait for synchronisation
1794          */
1795         function masterPosWait( MySQLMasterPos $pos, $timeout ) {
1796                 $fname = 'DatabaseBase::masterPosWait';
1797                 wfProfileIn( $fname );
1798
1799                 # Commit any open transactions
1800                 if ( $this->mTrxLevel ) {
1801                         $this->commit();
1802                 }
1803
1804                 if ( !is_null( $this->mFakeSlaveLag ) ) {
1805                         $wait = intval( ( $pos->pos - microtime(true) + $this->mFakeSlaveLag ) * 1e6 );
1806                         if ( $wait > $timeout * 1e6 ) {
1807                                 wfDebug( "Fake slave timed out waiting for $pos ($wait us)\n" );
1808                                 wfProfileOut( $fname );
1809                                 return -1;
1810                         } elseif ( $wait > 0 ) {
1811                                 wfDebug( "Fake slave waiting $wait us\n" );
1812                                 usleep( $wait );
1813                                 wfProfileOut( $fname );
1814                                 return 1;
1815                         } else {
1816                                 wfDebug( "Fake slave up to date ($wait us)\n" );
1817                                 wfProfileOut( $fname );
1818                                 return 0;
1819                         }
1820                 }
1821
1822                 # Call doQuery() directly, to avoid opening a transaction if DBO_TRX is set
1823                 $encFile = $this->addQuotes( $pos->file );
1824                 $encPos = intval( $pos->pos );
1825                 $sql = "SELECT MASTER_POS_WAIT($encFile, $encPos, $timeout)";
1826                 $res = $this->doQuery( $sql );
1827                 if ( $res && $row = $this->fetchRow( $res ) ) {
1828                         wfProfileOut( $fname );
1829                         return $row[0];
1830                 } else {
1831                         wfProfileOut( $fname );
1832                         return false;
1833                 }
1834         }
1835
1836         /**
1837          * Get the position of the master from SHOW SLAVE STATUS
1838          */
1839         function getSlavePos() {
1840                 if ( !is_null( $this->mFakeSlaveLag ) ) {
1841                         $pos = new MySQLMasterPos( 'fake', microtime(true) - $this->mFakeSlaveLag );
1842                         wfDebug( __METHOD__.": fake slave pos = $pos\n" );
1843                         return $pos;
1844                 }
1845                 $res = $this->query( 'SHOW SLAVE STATUS', 'DatabaseBase::getSlavePos' );
1846                 $row = $this->fetchObject( $res );
1847                 if ( $row ) {
1848                         $pos = isset($row->Exec_master_log_pos) ? $row->Exec_master_log_pos : $row->Exec_Master_Log_Pos;
1849                         return new MySQLMasterPos( $row->Relay_Master_Log_File, $pos );
1850                 } else {
1851                         return false;
1852                 }
1853         }
1854
1855         /**
1856          * Get the position of the master from SHOW MASTER STATUS
1857          */
1858         function getMasterPos() {
1859                 if ( $this->mFakeMaster ) {
1860                         return new MySQLMasterPos( 'fake', microtime( true ) );
1861                 }
1862                 $res = $this->query( 'SHOW MASTER STATUS', 'DatabaseBase::getMasterPos' );
1863                 $row = $this->fetchObject( $res );
1864                 if ( $row ) {
1865                         return new MySQLMasterPos( $row->File, $row->Position );
1866                 } else {
1867                         return false;
1868                 }
1869         }
1870
1871         /**
1872          * Begin a transaction, committing any previously open transaction
1873          */
1874         function begin( $fname = 'DatabaseBase::begin' ) {
1875                 $this->query( 'BEGIN', $fname );
1876                 $this->mTrxLevel = 1;
1877         }
1878
1879         /**
1880          * End a transaction
1881          */
1882         function commit( $fname = 'DatabaseBase::commit' ) {
1883                 if( $this->mTrxLevel ) {
1884                         $this->query( 'COMMIT', $fname );
1885                         $this->mTrxLevel = 0;
1886                 }
1887         }
1888
1889         /**
1890          * Rollback a transaction.
1891          * No-op on non-transactional databases.
1892          */
1893         function rollback( $fname = 'DatabaseBase::rollback' ) {
1894                 if( $this->mTrxLevel ) {
1895                         $this->query( 'ROLLBACK', $fname, true );
1896                         $this->mTrxLevel = 0;
1897                 }
1898         }
1899
1900         /**
1901          * Begin a transaction, committing any previously open transaction
1902          * @deprecated use begin()
1903          */
1904         function immediateBegin( $fname = 'DatabaseBase::immediateBegin' ) {
1905                 wfDeprecated( __METHOD__ );
1906                 $this->begin();
1907         }
1908
1909         /**
1910          * Commit transaction, if one is open
1911          * @deprecated use commit()
1912          */
1913         function immediateCommit( $fname = 'DatabaseBase::immediateCommit' ) {
1914                 wfDeprecated( __METHOD__ );
1915                 $this->commit();
1916         }
1917
1918         /**
1919          * Creates a new table with structure copied from existing table
1920          * Note that unlike most database abstraction functions, this function does not
1921          * automatically append database prefix, because it works at a lower
1922          * abstraction level.
1923          *
1924          * @param $oldName String: name of table whose structure should be copied
1925          * @param $newName String: name of table to be created
1926          * @param $temporary Boolean: whether the new table should be temporary
1927          * @param $fname String: calling function name
1928          * @return Boolean: true if operation was successful
1929          */
1930         function duplicateTableStructure( $oldName, $newName, $temporary = false, $fname = 'DatabaseBase::duplicateTableStructure' ) {
1931                 throw new MWException( 'DatabaseBase::duplicateTableStructure is not implemented in descendant class' );
1932         }
1933
1934         /**
1935          * Return MW-style timestamp used for MySQL schema
1936          */
1937         function timestamp( $ts=0 ) {
1938                 return wfTimestamp(TS_MW,$ts);
1939         }
1940
1941         /**
1942          * Local database timestamp format or null
1943          */
1944         function timestampOrNull( $ts = null ) {
1945                 if( is_null( $ts ) ) {
1946                         return null;
1947                 } else {
1948                         return $this->timestamp( $ts );
1949                 }
1950         }
1951
1952         /**
1953          * @todo document
1954          */
1955         function resultObject( $result ) {
1956                 if( empty( $result ) ) {
1957                         return false;
1958                 } elseif ( $result instanceof ResultWrapper ) {
1959                         return $result;
1960                 } elseif ( $result === true ) {
1961                         // Successful write query
1962                         return $result;
1963                 } else {
1964                         return new ResultWrapper( $this, $result );
1965                 }
1966         }
1967
1968         /**
1969          * Return aggregated value alias
1970          */
1971         function aggregateValue ($valuedata,$valuename='value') {
1972                 return $valuename;
1973         }
1974
1975         /**
1976          * Ping the server and try to reconnect if it there is no connection
1977          *
1978          * @return bool Success or failure
1979          */
1980         function ping() {
1981                 # Stub.  Not essential to override.
1982                 return true;
1983         }
1984
1985         /**
1986          * Get slave lag.
1987          * Currently supported only by MySQL
1988          * @return Database replication lag in seconds
1989          */
1990         function getLag() {
1991                 return $this->mFakeSlaveLag;
1992         }
1993
1994         /**
1995          * Get status information from SHOW STATUS in an associative array
1996          */
1997         function getStatus($which="%") {
1998                 $res = $this->query( "SHOW STATUS LIKE '{$which}'" );
1999                 $status = array();
2000                 while ( $row = $this->fetchObject( $res ) ) {
2001                         $status[$row->Variable_name] = $row->Value;
2002                 }
2003                 return $status;
2004         }
2005
2006         /**
2007          * Return the maximum number of items allowed in a list, or 0 for unlimited.
2008          */
2009         function maxListLen() {
2010                 return 0;
2011         }
2012
2013         function encodeBlob($b) {
2014                 return $b;
2015         }
2016
2017         function decodeBlob($b) {
2018                 return $b;
2019         }
2020
2021         /**
2022          * Override database's default connection timeout.  May be useful for very
2023          * long batch queries such as full-wiki dumps, where a single query reads
2024          * out over hours or days.  May or may not be necessary for non-MySQL
2025          * databases.  For most purposes, leaving it as a no-op should be fine.
2026          *
2027          * @param $timeout Integer in seconds
2028          */
2029         public function setTimeout( $timeout ) {}
2030
2031         /**
2032          * Read and execute SQL commands from a file.
2033          * Returns true on success, error string or exception on failure (depending on object's error ignore settings)
2034          * @param $filename String: File name to open
2035          * @param $lineCallback Callback: Optional function called before reading each line
2036          * @param $resultCallback Callback: Optional function called for each MySQL result
2037          */
2038         function sourceFile( $filename, $lineCallback = false, $resultCallback = false ) {
2039                 $fp = fopen( $filename, 'r' );
2040                 if ( false === $fp ) {
2041                         if (!defined("MEDIAWIKI_INSTALL"))
2042                                 throw new MWException( "Could not open \"{$filename}\".\n" );
2043                         else
2044                                 return "Could not open \"{$filename}\".\n";
2045                 }
2046                 try {
2047                         $error = $this->sourceStream( $fp, $lineCallback, $resultCallback );
2048                 }
2049                 catch( MWException $e ) {
2050                         if ( defined("MEDIAWIKI_INSTALL") ) {
2051                                 $error = $e->getMessage();
2052                         } else {
2053                                 fclose( $fp );
2054                                 throw $e;
2055                         }
2056                 }
2057
2058                 fclose( $fp );
2059                 return $error;
2060         }
2061
2062         /**
2063          * Get the full path of a patch file. Originally based on archive()
2064          * from updaters.inc. Keep in mind this always returns a patch, as
2065          * it fails back to MySQL if no DB-specific patch can be found
2066          *
2067          * @param $patch String The name of the patch, like patch-something.sql
2068          * @return String Full path to patch file
2069          */
2070         public static function patchPath( $patch ) {
2071                 global $wgDBtype, $IP;
2072                 if ( file_exists( "$IP/maintenance/$wgDBtype/archives/$patch" ) ) {
2073                         return "$IP/maintenance/$wgDBtype/archives/$patch";
2074                 } else {
2075                         return "$IP/maintenance/archives/$patch";
2076                 }
2077         }
2078
2079         /**
2080          * Read and execute commands from an open file handle
2081          * Returns true on success, error string or exception on failure (depending on object's error ignore settings)
2082          * @param $fp String: File handle
2083          * @param $lineCallback Callback: Optional function called before reading each line
2084          * @param $resultCallback Callback: Optional function called for each MySQL result
2085          */
2086         function sourceStream( $fp, $lineCallback = false, $resultCallback = false ) {
2087                 $cmd = "";
2088                 $done = false;
2089                 $dollarquote = false;
2090
2091                 while ( ! feof( $fp ) ) {
2092                         if ( $lineCallback ) {
2093                                 call_user_func( $lineCallback );
2094                         }
2095                         $line = trim( fgets( $fp, 1024 ) );
2096                         $sl = strlen( $line ) - 1;
2097
2098                         if ( $sl < 0 ) { continue; }
2099                         if ( '-' == $line{0} && '-' == $line{1} ) { continue; }
2100
2101                         ## Allow dollar quoting for function declarations
2102                         if (substr($line,0,4) == '$mw$') {
2103                                 if ($dollarquote) {
2104                                         $dollarquote = false;
2105                                         $done = true;
2106                                 }
2107                                 else {
2108                                         $dollarquote = true;
2109                                 }
2110                         }
2111                         else if (!$dollarquote) {
2112                                 if ( ';' == $line{$sl} && ($sl < 2 || ';' != $line{$sl - 1})) {
2113                                         $done = true;
2114                                         $line = substr( $line, 0, $sl );
2115                                 }
2116                         }
2117
2118                         if ( $cmd != '' ) { $cmd .= ' '; }
2119                         $cmd .= "$line\n";
2120
2121                         if ( $done ) {
2122                                 $cmd = str_replace(';;', ";", $cmd);
2123                                 $cmd = $this->replaceVars( $cmd );
2124                                 $res = $this->query( $cmd, __METHOD__ );
2125                                 if ( $resultCallback ) {
2126                                         call_user_func( $resultCallback, $res, $this );
2127                                 }
2128
2129                                 if ( false === $res ) {
2130                                         $err = $this->lastError();
2131                                         return "Query \"{$cmd}\" failed with error code \"$err\".\n";
2132                                 }
2133
2134                                 $cmd = '';
2135                                 $done = false;
2136                         }
2137                 }
2138                 return true;
2139         }
2140
2141
2142         /**
2143          * Replace variables in sourced SQL
2144          */
2145         protected function replaceVars( $ins ) {
2146                 $varnames = array(
2147                         'wgDBserver', 'wgDBname', 'wgDBintlname', 'wgDBuser',
2148                         'wgDBpassword', 'wgDBsqluser', 'wgDBsqlpassword',
2149                         'wgDBadminuser', 'wgDBadminpassword', 'wgDBTableOptions',
2150                 );
2151
2152                 // Ordinary variables
2153                 foreach ( $varnames as $var ) {
2154                         if( isset( $GLOBALS[$var] ) ) {
2155                                 $val = addslashes( $GLOBALS[$var] ); // FIXME: safety check?
2156                                 $ins = str_replace( '{$' . $var . '}', $val, $ins );
2157                                 $ins = str_replace( '/*$' . $var . '*/`', '`' . $val, $ins );
2158                                 $ins = str_replace( '/*$' . $var . '*/', $val, $ins );
2159                         }
2160                 }
2161
2162                 // Table prefixes
2163                 $ins = preg_replace_callback( '!/\*(?:\$wgDBprefix|_)\*/([a-zA-Z_0-9]*)!',
2164                         array( $this, 'tableNameCallback' ), $ins );
2165
2166                 // Index names
2167                 $ins = preg_replace_callback( '!/\*i\*/([a-zA-Z_0-9]*)!',
2168                         array( $this, 'indexNameCallback' ), $ins );
2169                 return $ins;
2170         }
2171
2172         /**
2173          * Table name callback
2174          * @private
2175          */
2176         protected function tableNameCallback( $matches ) {
2177                 return $this->tableName( $matches[1] );
2178         }
2179
2180         /**
2181          * Index name callback
2182          */
2183         protected function indexNameCallback( $matches ) {
2184                 return $this->indexName( $matches[1] );
2185         }
2186
2187         /**
2188          * Build a concatenation list to feed into a SQL query
2189          * @param $stringList Array: list of raw SQL expressions; caller is responsible for any quoting
2190          * @return String
2191          */
2192         function buildConcat( $stringList ) {
2193                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
2194         }
2195
2196         /**
2197          * Acquire a named lock
2198          *
2199          * Abstracted from Filestore::lock() so child classes can implement for
2200          * their own needs.
2201          *
2202          * @param $lockName String: name of lock to aquire
2203          * @param $method String: name of method calling us
2204          * @param $timeout Integer: timeout
2205          * @return Boolean
2206          */
2207         public function lock( $lockName, $method, $timeout = 5 ) {
2208                 return true;
2209         }
2210
2211         /**
2212          * Release a lock.
2213          *
2214          * @param $lockName String: Name of lock to release
2215          * @param $method String: Name of method calling us
2216          *
2217          * @return Returns 1 if the lock was released, 0 if the lock was not established
2218          * by this thread (in which case the lock is not released), and NULL if the named
2219          * lock did not exist
2220          */
2221         public function unlock( $lockName, $method ) {
2222                 return true;
2223         }
2224
2225         /**
2226          * Lock specific tables
2227          *
2228          * @param $read Array of tables to lock for read access
2229          * @param $write Array of tables to lock for write access
2230          * @param $method String name of caller
2231          * @param $lowPriority bool Whether to indicate writes to be LOW PRIORITY
2232          */
2233         public function lockTables( $read, $write, $method, $lowPriority = true ) {
2234                 return true;
2235         }
2236
2237         /**
2238          * Unlock specific tables
2239          *
2240          * @param $method String the caller
2241          */
2242         public function unlockTables( $method ) {
2243                 return true;
2244         }
2245
2246         /**
2247          * Get search engine class. All subclasses of this need to implement this
2248          * if they wish to use searching.
2249          *
2250          * @return String
2251          */
2252         public function getSearchEngine() {
2253                 return 'SearchEngineDummy';
2254         }
2255
2256         /**
2257          * Allow or deny "big selects" for this session only. This is done by setting
2258          * the sql_big_selects session variable.
2259          *
2260          * This is a MySQL-specific feature.
2261          *
2262          * @param $value Mixed: true for allow, false for deny, or "default" to restore the initial value
2263          */
2264         public function setBigSelects( $value = true ) {
2265                 // no-op
2266         }
2267 }
2268
2269
2270 /******************************************************************************
2271  * Utility classes
2272  *****************************************************************************/
2273
2274 /**
2275  * Utility class.
2276  * @ingroup Database
2277  */
2278 class DBObject {
2279         public $mData;
2280
2281         function __construct($data) {
2282                 $this->mData = $data;
2283         }
2284
2285         function isLOB() {
2286                 return false;
2287         }
2288
2289         function data() {
2290                 return $this->mData;
2291         }
2292 }
2293
2294 /**
2295  * Utility class
2296  * @ingroup Database
2297  *
2298  * This allows us to distinguish a blob from a normal string and an array of strings
2299  */
2300 class Blob {
2301         private $mData;
2302         function __construct($data) {
2303                 $this->mData = $data;
2304         }
2305         function fetch() {
2306                 return $this->mData;
2307         }
2308 }
2309
2310 /**
2311  * Utility class.
2312  * @ingroup Database
2313  */
2314 class MySQLField {
2315         private $name, $tablename, $default, $max_length, $nullable,
2316                 $is_pk, $is_unique, $is_multiple, $is_key, $type;
2317         function __construct ($info) {
2318                 $this->name = $info->name;
2319                 $this->tablename = $info->table;
2320                 $this->default = $info->def;
2321                 $this->max_length = $info->max_length;
2322                 $this->nullable = !$info->not_null;
2323                 $this->is_pk = $info->primary_key;
2324                 $this->is_unique = $info->unique_key;
2325                 $this->is_multiple = $info->multiple_key;
2326                 $this->is_key = ($this->is_pk || $this->is_unique || $this->is_multiple);
2327                 $this->type = $info->type;
2328         }
2329
2330         function name() {
2331                 return $this->name;
2332         }
2333
2334         function tableName() {
2335                 return $this->tableName;
2336         }
2337
2338         function defaultValue() {
2339                 return $this->default;
2340         }
2341
2342         function maxLength() {
2343                 return $this->max_length;
2344         }
2345
2346         function nullable() {
2347                 return $this->nullable;
2348         }
2349
2350         function isKey() {
2351                 return $this->is_key;
2352         }
2353
2354         function isMultipleKey() {
2355                 return $this->is_multiple;
2356         }
2357
2358         function type() {
2359                 return $this->type;
2360         }
2361 }
2362
2363 /******************************************************************************
2364  * Error classes
2365  *****************************************************************************/
2366
2367 /**
2368  * Database error base class
2369  * @ingroup Database
2370  */
2371 class DBError extends MWException {
2372         public $db;
2373
2374         /**
2375          * Construct a database error
2376          * @param $db Database object which threw the error
2377          * @param $error A simple error message to be used for debugging
2378          */
2379         function __construct( DatabaseBase &$db, $error ) {
2380                 $this->db =& $db;
2381                 parent::__construct( $error );
2382         }
2383
2384         function getText() {
2385                 global $wgShowDBErrorBacktrace;
2386                 $s = $this->getMessage() . "\n";
2387                 if ( $wgShowDBErrorBacktrace ) {
2388                         $s .= "Backtrace:\n" . $this->getTraceAsString() . "\n";
2389                 }
2390                 return $s;
2391         }
2392 }
2393
2394 /**
2395  * @ingroup Database
2396  */
2397 class DBConnectionError extends DBError {
2398         public $error;
2399
2400         function __construct( DatabaseBase &$db, $error = 'unknown error' ) {
2401                 $msg = 'DB connection error';
2402                 if ( trim( $error ) != '' ) {
2403                         $msg .= ": $error";
2404                 }
2405                 $this->error = $error;
2406                 parent::__construct( $db, $msg );
2407         }
2408
2409         function useOutputPage() {
2410                 // Not likely to work
2411                 return false;
2412         }
2413
2414         function useMessageCache() {
2415                 // Not likely to work
2416                 return false;
2417         }
2418
2419         function getLogMessage() {
2420                 # Don't send to the exception log
2421                 return false;
2422         }
2423
2424         function getPageTitle() {
2425                 global $wgSitename, $wgLang;
2426                 $header = "$wgSitename has a problem";
2427                 if ( $wgLang instanceof Language ) {
2428                         $header = htmlspecialchars( $wgLang->getMessage( 'dberr-header' ) );
2429                 }
2430
2431                 return $header;
2432         }
2433
2434         function getHTML() {
2435                 global $wgLang, $wgMessageCache, $wgUseFileCache, $wgShowDBErrorBacktrace;
2436
2437                 $sorry = 'Sorry! This site is experiencing technical difficulties.';
2438                 $again = 'Try waiting a few minutes and reloading.';
2439                 $info  = '(Can\'t contact the database server: $1)';
2440
2441                 if ( $wgLang instanceof Language ) {
2442                         $sorry = htmlspecialchars( $wgLang->getMessage( 'dberr-problems' ) );
2443                         $again = htmlspecialchars( $wgLang->getMessage( 'dberr-again' ) );
2444                         $info  = htmlspecialchars( $wgLang->getMessage( 'dberr-info' ) );
2445                 }
2446
2447                 # No database access
2448                 if ( is_object( $wgMessageCache ) ) {
2449                         $wgMessageCache->disable();
2450                 }
2451
2452                 if ( trim( $this->error ) == '' ) {
2453                         $this->error = $this->db->getProperty('mServer');
2454                 }
2455
2456                 $noconnect = "<p><strong>$sorry</strong><br />$again</p><p><small>$info</small></p>";
2457                 $text = str_replace( '$1', $this->error, $noconnect );
2458
2459                 if ( $wgShowDBErrorBacktrace ) {
2460                         $text .= '<p>Backtrace:</p><p>' . nl2br( htmlspecialchars( $this->getTraceAsString() ) );
2461                 }
2462
2463                 $extra = $this->searchForm();
2464
2465                 if( $wgUseFileCache ) {
2466                         try {
2467                                 $cache = $this->fileCachedPage();
2468                                 # Cached version on file system?
2469                                 if( $cache !== null ) {
2470                                         # Hack: extend the body for error messages
2471                                         $cache = str_replace( array('</html>','</body>'), '', $cache );
2472                                         # Add cache notice...
2473                                         $cachederror = "This is a cached copy of the requested page, and may not be up to date. ";
2474                                         # Localize it if possible...
2475                                         if( $wgLang instanceof Language ) {
2476                                                 $cachederror = htmlspecialchars( $wgLang->getMessage( 'dberr-cachederror' ) );
2477                                         }
2478                                         $warning = "<div style='color:red;font-size:150%;font-weight:bold;'>$cachederror</div>";
2479                                         # Output cached page with notices on bottom and re-close body
2480                                         return "{$cache}{$warning}<hr />$text<hr />$extra</body></html>";
2481                                 }
2482                         } catch( MWException $e ) {
2483                                 // Do nothing, just use the default page
2484                         }
2485                 }
2486                 # Headers needed here - output is just the error message
2487                 return $this->htmlHeader()."$text<hr />$extra".$this->htmlFooter();
2488         }
2489
2490         function searchForm() {
2491                 global $wgSitename, $wgServer, $wgLang, $wgInputEncoding;
2492                 $usegoogle = "You can try searching via Google in the meantime.";
2493                 $outofdate = "Note that their indexes of our content may be out of date.";
2494                 $googlesearch = "Search";
2495
2496                 if ( $wgLang instanceof Language ) {
2497                         $usegoogle = htmlspecialchars( $wgLang->getMessage( 'dberr-usegoogle' ) );
2498                         $outofdate = htmlspecialchars( $wgLang->getMessage( 'dberr-outofdate' ) );
2499                         $googlesearch  = htmlspecialchars( $wgLang->getMessage( 'searchbutton' ) );
2500                 }
2501
2502                 $search = htmlspecialchars(@$_REQUEST['search']);
2503
2504                 $trygoogle = <<<EOT
2505 <div style="margin: 1.5em">$usegoogle<br />
2506 <small>$outofdate</small></div>
2507 <!-- SiteSearch Google -->
2508 <form method="get" action="http://www.google.com/search" id="googlesearch">
2509     <input type="hidden" name="domains" value="$wgServer" />
2510     <input type="hidden" name="num" value="50" />
2511     <input type="hidden" name="ie" value="$wgInputEncoding" />
2512     <input type="hidden" name="oe" value="$wgInputEncoding" />
2513
2514     <input type="text" name="q" size="31" maxlength="255" value="$search" />
2515     <input type="submit" name="btnG" value="$googlesearch" />
2516   <div>
2517     <input type="radio" name="sitesearch" id="gwiki" value="$wgServer" checked="checked" /><label for="gwiki">$wgSitename</label>
2518     <input type="radio" name="sitesearch" id="gWWW" value="" /><label for="gWWW">WWW</label>
2519   </div>
2520 </form>
2521 <!-- SiteSearch Google -->
2522 EOT;
2523                 return $trygoogle;
2524         }
2525
2526         function fileCachedPage() {
2527                 global $wgTitle, $title, $wgLang, $wgOut;
2528                 if( $wgOut->isDisabled() ) return; // Done already?
2529                 $mainpage = 'Main Page';
2530                 if ( $wgLang instanceof Language ) {
2531                         $mainpage    = htmlspecialchars( $wgLang->getMessage( 'mainpage' ) );
2532                 }
2533
2534                 if( $wgTitle ) {
2535                         $t =& $wgTitle;
2536                 } elseif( $title ) {
2537                         $t = Title::newFromURL( $title );
2538                 } else {
2539                         $t = Title::newFromText( $mainpage );
2540                 }
2541
2542                 $cache = new HTMLFileCache( $t );
2543                 if( $cache->isFileCached() ) {
2544                         return $cache->fetchPageText();
2545                 } else {
2546                         return '';
2547                 }
2548         }
2549
2550         function htmlBodyOnly() {
2551                 return true;
2552         }
2553
2554 }
2555
2556 /**
2557  * @ingroup Database
2558  */
2559 class DBQueryError extends DBError {
2560         public $error, $errno, $sql, $fname;
2561
2562         function __construct( DatabaseBase &$db, $error, $errno, $sql, $fname ) {
2563                 $message = "A database error has occurred\n" .
2564                   "Query: $sql\n" .
2565                   "Function: $fname\n" .
2566                   "Error: $errno $error\n";
2567
2568                 parent::__construct( $db, $message );
2569                 $this->error = $error;
2570                 $this->errno = $errno;
2571                 $this->sql = $sql;
2572                 $this->fname = $fname;
2573         }
2574
2575         function getText() {
2576                 global $wgShowDBErrorBacktrace;
2577                 if ( $this->useMessageCache() ) {
2578                         $s = wfMsg( 'dberrortextcl', htmlspecialchars( $this->getSQL() ),
2579                                 htmlspecialchars( $this->fname ), $this->errno, htmlspecialchars( $this->error ) ) . "\n";
2580                         if ( $wgShowDBErrorBacktrace ) {
2581                                 $s .= "Backtrace:\n" . $this->getTraceAsString() . "\n";
2582                         }
2583                         return $s;
2584                 } else {
2585                         return parent::getText();
2586                 }
2587         }
2588
2589         function getSQL() {
2590                 global $wgShowSQLErrors;
2591                 if( !$wgShowSQLErrors ) {
2592                         return $this->msg( 'sqlhidden', 'SQL hidden' );
2593                 } else {
2594                         return $this->sql;
2595                 }
2596         }
2597
2598         function getLogMessage() {
2599                 # Don't send to the exception log
2600                 return false;
2601         }
2602
2603         function getPageTitle() {
2604                 return $this->msg( 'databaseerror', 'Database error' );
2605         }
2606
2607         function getHTML() {
2608                 global $wgShowDBErrorBacktrace;
2609                 if ( $this->useMessageCache() ) {
2610                         $s = wfMsgNoDB( 'dberrortext', htmlspecialchars( $this->getSQL() ),
2611                           htmlspecialchars( $this->fname ), $this->errno, htmlspecialchars( $this->error ) );
2612                 } else {
2613                         $s = nl2br( htmlspecialchars( $this->getMessage() ) );
2614                 }
2615                 if ( $wgShowDBErrorBacktrace ) {
2616                         $s .= '<p>Backtrace:</p><p>' . nl2br( htmlspecialchars( $this->getTraceAsString() ) );
2617                 }
2618                 return $s;
2619         }
2620 }
2621
2622 /**
2623  * @ingroup Database
2624  */
2625 class DBUnexpectedError extends DBError {}
2626
2627
2628 /**
2629  * Result wrapper for grabbing data queried by someone else
2630  * @ingroup Database
2631  */
2632 class ResultWrapper implements Iterator {
2633         var $db, $result, $pos = 0, $currentRow = null;
2634
2635         /**
2636          * Create a new result object from a result resource and a Database object
2637          */
2638         function __construct( $database, $result ) {
2639                 $this->db = $database;
2640                 if ( $result instanceof ResultWrapper ) {
2641                         $this->result = $result->result;
2642                 } else {
2643                         $this->result = $result;
2644                 }
2645         }
2646
2647         /**
2648          * Get the number of rows in a result object
2649          */
2650         function numRows() {
2651                 return $this->db->numRows( $this );
2652         }
2653
2654         /**
2655          * Fetch the next row from the given result object, in object form.
2656          * Fields can be retrieved with $row->fieldname, with fields acting like
2657          * member variables.
2658          *
2659          * @return MySQL row object
2660          * @throws DBUnexpectedError Thrown if the database returns an error
2661          */
2662         function fetchObject() {
2663                 return $this->db->fetchObject( $this );
2664         }
2665
2666         /**
2667          * Fetch the next row from the given result object, in associative array
2668          * form.  Fields are retrieved with $row['fieldname'].
2669          *
2670          * @return MySQL row object
2671          * @throws DBUnexpectedError Thrown if the database returns an error
2672          */
2673         function fetchRow() {
2674                 return $this->db->fetchRow( $this );
2675         }
2676
2677         /**
2678          * Free a result object
2679          */
2680         function free() {
2681                 $this->db->freeResult( $this );
2682                 unset( $this->result );
2683                 unset( $this->db );
2684         }
2685
2686         /**
2687          * Change the position of the cursor in a result object
2688          * See mysql_data_seek()
2689          */
2690         function seek( $row ) {
2691                 $this->db->dataSeek( $this, $row );
2692         }
2693
2694         /*********************
2695          * Iterator functions
2696          * Note that using these in combination with the non-iterator functions
2697          * above may cause rows to be skipped or repeated.
2698          */
2699
2700         function rewind() {
2701                 if ($this->numRows()) {
2702                         $this->db->dataSeek($this, 0);
2703                 }
2704                 $this->pos = 0;
2705                 $this->currentRow = null;
2706         }
2707
2708         function current() {
2709                 if ( is_null( $this->currentRow ) ) {
2710                         $this->next();
2711                 }
2712                 return $this->currentRow;
2713         }
2714
2715         function key() {
2716                 return $this->pos;
2717         }
2718
2719         function next() {
2720                 $this->pos++;
2721                 $this->currentRow = $this->fetchObject();
2722                 return $this->currentRow;
2723         }
2724
2725         function valid() {
2726                 return $this->current() !== false;
2727         }
2728 }
2729
2730 /* Overloads the relevant methods of the real ResultsWrapper so it
2731  * doesn't go anywhere near an actual database.
2732  */
2733 class FakeResultWrapper extends ResultWrapper {
2734
2735         var $result     = array();
2736         var $db         = null; // And it's going to stay that way :D
2737         var $pos        = 0;
2738         var $currentRow = null;
2739
2740         function __construct( $array ){
2741                 $this->result = $array;
2742         }
2743
2744         function numRows() {
2745                 return count( $this->result );
2746         }
2747
2748         function fetchRow() {
2749                 $this->currentRow = $this->result[$this->pos++];
2750                 return $this->currentRow;
2751         }
2752
2753         function seek( $row ) {
2754                 $this->pos = $row;
2755         }
2756
2757         function free() {}
2758
2759         // Callers want to be able to access fields with $this->fieldName
2760         function fetchObject(){
2761                 $this->currentRow = $this->result[$this->pos++];
2762                 return (object)$this->currentRow;
2763         }
2764
2765         function rewind() {
2766                 $this->pos = 0;
2767                 $this->currentRow = null;
2768         }
2769 }
2770
2771 /**
2772  * Used by DatabaseBase::buildLike() to represent characters that have special meaning in SQL LIKE clauses
2773  * and thus need no escaping. Don't instantiate it manually, use DatabaseBase::anyChar() and anyString() instead.
2774  */
2775 class LikeMatch {
2776         private $str;
2777
2778         public function __construct( $s ) {
2779                 $this->str = $s;
2780         }
2781
2782         public function toString() {
2783                 return $this->str;
2784         }
2785 }