includes/db/Database.php

   1 <?php
   2 /**
   3  * @defgroup Database Database
   4  *
   5  * @file
   6  * @ingroup Database
   7  * This file deals with MySQL 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 class Database {
  23
  24 #------------------------------------------------------------------------------
  25 # Variables
  26 #------------------------------------------------------------------------------
  27
  28         protected $mLastQuery = '';
  29         protected $mPHPError = false;
  30
  31         protected $mServer, $mUser, $mPassword, $mConn = null, $mDBname;
  32         protected $mOpened = false;
  33
  34         protected $mFailFunction;
  35         protected $mTablePrefix;
  36         protected $mFlags;
  37         protected $mTrxLevel = 0;
  38         protected $mErrorCount = 0;
  39         protected $mLBInfo = array();
  40         protected $mFakeSlaveLag = null, $mFakeMaster = false;
  41
  42 #------------------------------------------------------------------------------
  43 # Accessors
  44 #------------------------------------------------------------------------------
  45         # These optionally set a variable and return the previous state
  46
  47         /**
  48          * Fail function, takes a Database as a parameter
  49          * Set to false for default, 1 for ignore errors
  50          */
  51         function failFunction( $function = NULL ) {
  52                 return wfSetVar( $this->mFailFunction, $function );
  53         }
  54
  55         /**
  56          * Output page, used for reporting errors
  57          * FALSE means discard output
  58          */
  59         function setOutputPage( $out ) {
  60                 wfDeprecated( __METHOD__ );
  61         }
  62
  63         /**
  64          * Boolean, controls output of large amounts of debug information
  65          */
  66         function debug( $debug = NULL ) {
  67                 return wfSetBit( $this->mFlags, DBO_DEBUG, $debug );
  68         }
  69
  70         /**
  71          * Turns buffering of SQL result sets on (true) or off (false).
  72          * Default is "on" and it should not be changed without good reasons.
  73          */
  74         function bufferResults( $buffer = NULL ) {
  75                 if ( is_null( $buffer ) ) {
  76                         return !(bool)( $this->mFlags & DBO_NOBUFFER );
  77                 } else {
  78                         return !wfSetBit( $this->mFlags, DBO_NOBUFFER, !$buffer );
  79                 }
  80         }
  81
  82         /**
  83          * Turns on (false) or off (true) the automatic generation and sending
  84          * of a "we're sorry, but there has been a database error" page on
  85          * database errors. Default is on (false). When turned off, the
  86          * code should use lastErrno() and lastError() to handle the
  87          * situation as appropriate.
  88          */
  89         function ignoreErrors( $ignoreErrors = NULL ) {
  90                 return wfSetBit( $this->mFlags, DBO_IGNORE, $ignoreErrors );
  91         }
  92
  93         /**
  94          * The current depth of nested transactions
  95          * @param $level Integer: , default NULL.
  96          */
  97         function trxLevel( $level = NULL ) {
  98                 return wfSetVar( $this->mTrxLevel, $level );
  99         }
 100
 101         /**
 102          * Number of errors logged, only useful when errors are ignored
 103          */
 104         function errorCount( $count = NULL ) {
 105                 return wfSetVar( $this->mErrorCount, $count );
 106         }
 107
 108         function tablePrefix( $prefix = null ) {
 109                 return wfSetVar( $this->mTablePrefix, $prefix );
 110         }
 111
 112         /**
 113          * Properties passed down from the server info array of the load balancer
 114          */
 115         function getLBInfo( $name = NULL ) {
 116                 if ( is_null( $name ) ) {
 117                         return $this->mLBInfo;
 118                 } else {
 119                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 120                                 return $this->mLBInfo[$name];
 121                         } else {
 122                                 return NULL;
 123                         }
 124                 }
 125         }
 126
 127         function setLBInfo( $name, $value = NULL ) {
 128                 if ( is_null( $value ) ) {
 129                         $this->mLBInfo = $name;
 130                 } else {
 131                         $this->mLBInfo[$name] = $value;
 132                 }
 133         }
 134
 135         /**
 136          * Set lag time in seconds for a fake slave
 137          */
 138         function setFakeSlaveLag( $lag ) {
 139                 $this->mFakeSlaveLag = $lag;
 140         }
 141
 142         /**
 143          * Make this connection a fake master
 144          */
 145         function setFakeMaster( $enabled = true ) {
 146                 $this->mFakeMaster = $enabled;
 147         }
 148
 149         /**
 150          * Returns true if this database supports (and uses) cascading deletes
 151          */
 152         function cascadingDeletes() {
 153                 return false;
 154         }
 155
 156         /**
 157          * Returns true if this database supports (and uses) triggers (e.g. on the page table)
 158          */
 159         function cleanupTriggers() {
 160                 return false;
 161         }
 162
 163         /**
 164          * Returns true if this database is strict about what can be put into an IP field.
 165          * Specifically, it uses a NULL value instead of an empty string.
 166          */
 167         function strictIPs() {
 168                 return false;
 169         }
 170
 171         /**
 172          * Returns true if this database uses timestamps rather than integers
 173         */
 174         function realTimestamps() {
 175                 return false;
 176         }
 177
 178         /**
 179          * Returns true if this database does an implicit sort when doing GROUP BY
 180          */
 181         function implicitGroupby() {
 182                 return true;
 183         }
 184
 185         /**
 186          * Returns true if this database does an implicit order by when the column has an index
 187          * For example: SELECT page_title FROM page LIMIT 1
 188          */
 189         function implicitOrderby() {
 190                 return true;
 191         }
 192
 193         /**
 194          * Returns true if this database can do a native search on IP columns
 195          * e.g. this works as expected: .. WHERE rc_ip = '127.42.12.102/32';
 196          */
 197         function searchableIPs() {
 198                 return false;
 199         }
 200
 201         /**
 202          * Returns true if this database can use functional indexes
 203          */
 204         function functionalIndexes() {
 205                 return false;
 206         }
 207
 208         /**
 209          * Return the last query that went through Database::query()
 210          * @return string
 211          */
 212         function lastQuery() { return $this->mLastQuery; }
 213
 214         /**
 215          * Is a connection to the database open?
 216          * @return bool
 217          */
 218         function isOpen() { return $this->mOpened; }
 219
 220         function setFlag( $flag ) {
 221                 $this->mFlags |= $flag;
 222         }
 223
 224         function clearFlag( $flag ) {
 225                 $this->mFlags &= ~$flag;
 226         }
 227
 228         function getFlag( $flag ) {
 229                 return !!($this->mFlags & $flag);
 230         }
 231
 232         /**
 233          * General read-only accessor
 234          */
 235         function getProperty( $name ) {
 236                 return $this->$name;
 237         }
 238
 239         function getWikiID() {
 240                 if( $this->mTablePrefix ) {
 241                         return "{$this->mDBname}-{$this->mTablePrefix}";
 242                 } else {
 243                         return $this->mDBname;
 244                 }
 245         }
 246
 247 #------------------------------------------------------------------------------
 248 # Other functions
 249 #------------------------------------------------------------------------------
 250
 251         /**@{{
 252          * Constructor.
 253          * @param string $server database server host
 254          * @param string $user database user name
 255          * @param string $password database user password
 256          * @param string $dbname database name
 257          * @param failFunction
 258          * @param $flags
 259          * @param $tablePrefix String: database table prefixes. By default use the prefix gave in LocalSettings.php
 260          */
 261         function __construct( $server = false, $user = false, $password = false, $dbName = false,
 262                 $failFunction = false, $flags = 0, $tablePrefix = 'get from global' ) {
 263
 264                 global $wgOut, $wgDBprefix, $wgCommandLineMode;
 265                 # Can't get a reference if it hasn't been set yet
 266                 if ( !isset( $wgOut ) ) {
 267                         $wgOut = NULL;
 268                 }
 269
 270                 $this->mFailFunction = $failFunction;
 271                 $this->mFlags = $flags;
 272
 273                 if ( $this->mFlags & DBO_DEFAULT ) {
 274                         if ( $wgCommandLineMode ) {
 275                                 $this->mFlags &= ~DBO_TRX;
 276                         } else {
 277                                 $this->mFlags |= DBO_TRX;
 278                         }
 279                 }
 280
 281                 /*
 282                 // Faster read-only access
 283                 if ( wfReadOnly() ) {
 284                         $this->mFlags |= DBO_PERSISTENT;
 285                         $this->mFlags &= ~DBO_TRX;
 286                 }*/
 287
 288                 /** Get the default table prefix*/
 289                 if ( $tablePrefix == 'get from global' ) {
 290                         $this->mTablePrefix = $wgDBprefix;
 291                 } else {
 292                         $this->mTablePrefix = $tablePrefix;
 293                 }
 294
 295                 if ( $server ) {
 296                         $this->open( $server, $user, $password, $dbName );
 297                 }
 298         }
 299
 300         /**
 301          * @static
 302          * @param failFunction
 303          * @param $flags
 304          */
 305         static function newFromParams( $server, $user, $password, $dbName, $failFunction = false, $flags = 0 )
 306         {
 307                 return new Database( $server, $user, $password, $dbName, $failFunction, $flags );
 308         }
 309
 310         /**
 311          * Usually aborts on failure
 312          * If the failFunction is set to a non-zero integer, returns success
 313          */
 314         function open( $server, $user, $password, $dbName ) {
 315                 global $wguname, $wgAllDBsAreLocalhost;
 316                 wfProfileIn( __METHOD__ );
 317
 318                 # Test for missing mysql.so
 319                 # First try to load it
 320                 if (!@extension_loaded('mysql')) {
 321                         @dl('mysql.so');
 322                 }
 323
 324                 # Fail now
 325                 # Otherwise we get a suppressed fatal error, which is very hard to track down
 326                 if ( !function_exists( 'mysql_connect' ) ) {
 327                         throw new DBConnectionError( $this, "MySQL functions missing, have you compiled PHP with the --with-mysql option?\n" );
 328                 }
 329
 330                 # Debugging hack -- fake cluster
 331                 if ( $wgAllDBsAreLocalhost ) {
 332                         $realServer = 'localhost';
 333                 } else {
 334                         $realServer = $server;
 335                 }
 336                 $this->close();
 337                 $this->mServer = $server;
 338                 $this->mUser = $user;
 339                 $this->mPassword = $password;
 340                 $this->mDBname = $dbName;
 341
 342                 $success = false;
 343
 344                 wfProfileIn("dbconnect-$server");
 345
 346                 # Try to connect up to three times
 347                 # The kernel's default SYN retransmission period is far too slow for us,
 348                 # so we use a short timeout plus a manual retry.
 349                 $this->mConn = false;
 350                 $max = 3;
 351                 $this->installErrorHandler();
 352                 for ( $i = 0; $i < $max && !$this->mConn; $i++ ) {
 353                         if ( $i > 1 ) {
 354                                 usleep( 1000 );
 355                         }
 356                         if ( $this->mFlags & DBO_PERSISTENT ) {
 357                                 $this->mConn = mysql_pconnect( $realServer, $user, $password );
 358                         } else {
 359                                 # Create a new connection...
 360                                 $this->mConn = mysql_connect( $realServer, $user, $password, true );
 361                         }
 362                         if ($this->mConn === false) {
 363                                 #$iplus = $i + 1;
 364                                 #wfLogDBError("Connect loop error $iplus of $max ($server): " . mysql_errno() . " - " . mysql_error()."\n");
 365                         }
 366                 }
 367                 $phpError = $this->restoreErrorHandler();
 368
 369                 wfProfileOut("dbconnect-$server");
 370
 371                 if ( $dbName != '' ) {
 372                         if ( $this->mConn !== false ) {
 373                                 $success = @/**/mysql_select_db( $dbName, $this->mConn );
 374                                 if ( !$success ) {
 375                                         $error = "Error selecting database $dbName on server {$this->mServer} " .
 376                                                 "from client host {$wguname['nodename']}\n";
 377                                         wfLogDBError(" Error selecting database $dbName on server {$this->mServer} \n");
 378                                         wfDebug( $error );
 379                                 }
 380                         } else {
 381                                 wfDebug( "DB connection error\n" );
 382                                 wfDebug( "Server: $server, User: $user, Password: " .
 383                                         substr( $password, 0, 3 ) . "..., error: " . mysql_error() . "\n" );
 384                                 $success = false;
 385                         }
 386                 } else {
 387                         # Delay USE query
 388                         $success = (bool)$this->mConn;
 389                 }
 390
 391                 if ( $success ) {
 392                         $version = $this->getServerVersion();
 393                         if ( version_compare( $version, '4.1' ) >= 0 ) {
 394                                 // Tell the server we're communicating with it in UTF-8.
 395                                 // This may engage various charset conversions.
 396                                 global $wgDBmysql5;
 397                                 if( $wgDBmysql5 ) {
 398                                         $this->query( 'SET NAMES utf8', __METHOD__ );
 399                                 }
 400                                 // Turn off strict mode
 401                                 $this->query( "SET sql_mode = ''", __METHOD__ );
 402                         }
 403
 404                         // Turn off strict mode if it is on
 405                 } else {
 406                         $this->reportConnectionError( $phpError );
 407                 }
 408
 409                 $this->mOpened = $success;
 410                 wfProfileOut( __METHOD__ );
 411                 return $success;
 412         }
 413         /**@}}*/
 414
 415         protected function installErrorHandler() {
 416                 $this->mPHPError = false;
 417                 set_error_handler( array( $this, 'connectionErrorHandler' ) );
 418         }
 419
 420         protected function restoreErrorHandler() {
 421                 restore_error_handler();
 422                 return $this->mPHPError;
 423         }
 424
 425         protected function connectionErrorHandler( $errno,  $errstr ) {
 426                 $this->mPHPError = $errstr;
 427         }
 428
 429         /**
 430          * Closes a database connection.
 431          * if it is open : commits any open transactions
 432          *
 433          * @return bool operation success. true if already closed.
 434          */
 435         function close()
 436         {
 437                 $this->mOpened = false;
 438                 if ( $this->mConn ) {
 439                         if ( $this->trxLevel() ) {
 440                                 $this->immediateCommit();
 441                         }
 442                         return mysql_close( $this->mConn );
 443                 } else {
 444                         return true;
 445                 }
 446         }
 447
 448         /**
 449          * @param string $error fallback error message, used if none is given by MySQL
 450          */
 451         function reportConnectionError( $error = 'Unknown error' ) {
 452                 $myError = $this->lastError();
 453                 if ( $myError ) {
 454                         $error = $myError;
 455                 }
 456
 457                 if ( $this->mFailFunction ) {
 458                         # Legacy error handling method
 459                         if ( !is_int( $this->mFailFunction ) ) {
 460                                 $ff = $this->mFailFunction;
 461                                 $ff( $this, $error );
 462                         }
 463                 } else {
 464                         # New method
 465                         wfLogDBError( "Connection error: $error\n" );
 466                         throw new DBConnectionError( $this, $error );
 467                 }
 468         }
 469
 470         /**
 471          * Usually aborts on failure.  If errors are explicitly ignored, returns success.
 472          *
 473          * @param  $sql        String: SQL query
 474          * @param  $fname      String: Name of the calling function, for profiling/SHOW PROCESSLIST
 475          *     comment (you can use __METHOD__ or add some extra info)
 476          * @param  $tempIgnore Bool:   Whether to avoid throwing an exception on errors...
 477          *     maybe best to catch the exception instead?
 478          * @return true for a successful write query, ResultWrapper object for a successful read query,
 479          *     or false on failure if $tempIgnore set
 480          * @throws DBQueryError Thrown when the database returns an error of any kind
 481          */
 482         public function query( $sql, $fname = '', $tempIgnore = false ) {
 483                 global $wgProfiler;
 484
 485                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 486                 if ( isset( $wgProfiler ) ) {
 487                         # generalizeSQL will probably cut down the query to reasonable
 488                         # logging size most of the time. The substr is really just a sanity check.
 489
 490                         # Who's been wasting my precious column space? -- TS
 491                         #$profName = 'query: ' . $fname . ' ' . substr( Database::generalizeSQL( $sql ), 0, 255 );
 492
 493                         if ( $isMaster ) {
 494                                 $queryProf = 'query-m: ' . substr( Database::generalizeSQL( $sql ), 0, 255 );
 495                                 $totalProf = 'Database::query-master';
 496                         } else {
 497                                 $queryProf = 'query: ' . substr( Database::generalizeSQL( $sql ), 0, 255 );
 498                                 $totalProf = 'Database::query';
 499                         }
 500                         wfProfileIn( $totalProf );
 501                         wfProfileIn( $queryProf );
 502                 }
 503
 504                 $this->mLastQuery = $sql;
 505
 506                 # Add a comment for easy SHOW PROCESSLIST interpretation
 507                 #if ( $fname ) {
 508                         global $wgUser;
 509                         if ( is_object( $wgUser ) && !($wgUser instanceof StubObject) ) {
 510                                 $userName = $wgUser->getName();
 511                                 if ( mb_strlen( $userName ) > 15 ) {
 512                                         $userName = mb_substr( $userName, 0, 15 ) . '...';
 513                                 }
 514                                 $userName = str_replace( '/', '', $userName );
 515                         } else {
 516                                 $userName = '';
 517                         }
 518                         $commentedSql = preg_replace('/\s/', " /* $fname $userName */ ", $sql, 1);
 519                 #} else {
 520                 #       $commentedSql = $sql;
 521                 #}
 522
 523                 # If DBO_TRX is set, start a transaction
 524                 if ( ( $this->mFlags & DBO_TRX ) && !$this->trxLevel() &&
 525                         $sql != 'BEGIN' && $sql != 'COMMIT' && $sql != 'ROLLBACK') {
 526                         // avoid establishing transactions for SHOW and SET statements too -
 527                         // that would delay transaction initializations to once connection
 528                         // is really used by application
 529                         $sqlstart = substr($sql,0,10); // very much worth it, benchmark certified(tm)
 530                         if (strpos($sqlstart,"SHOW ")!==0 and strpos($sqlstart,"SET ")!==0)
 531                                 $this->begin();
 532                 }
 533
 534                 if ( $this->debug() ) {
 535                         $sqlx = substr( $commentedSql, 0, 500 );
 536                         $sqlx = strtr( $sqlx, "\t\n", '  ' );
 537                         if ( $isMaster ) {
 538                                 wfDebug( "SQL-master: $sqlx\n" );
 539                         } else {
 540                                 wfDebug( "SQL: $sqlx\n" );
 541                         }
 542                 }
 543
 544                 # Do the query and handle errors
 545                 $ret = $this->doQuery( $commentedSql );
 546
 547                 # Try reconnecting if the connection was lost
 548                 if ( false === $ret && ( $this->lastErrno() == 2013 || $this->lastErrno() == 2006 ) ) {
 549                         # Transaction is gone, like it or not
 550                         $this->mTrxLevel = 0;
 551                         wfDebug( "Connection lost, reconnecting...\n" );
 552                         if ( $this->ping() ) {
 553                                 wfDebug( "Reconnected\n" );
 554                                 $sqlx = substr( $commentedSql, 0, 500 );
 555                                 $sqlx = strtr( $sqlx, "\t\n", '  ' );
 556                                 global $wgRequestTime;
 557                                 $elapsed = round( microtime(true) - $wgRequestTime, 3 );
 558                                 wfLogDBError( "Connection lost and reconnected after {$elapsed}s, query: $sqlx\n" );
 559                                 $ret = $this->doQuery( $commentedSql );
 560                         } else {
 561                                 wfDebug( "Failed\n" );
 562                         }
 563                 }
 564
 565                 if ( false === $ret ) {
 566                         $this->reportQueryError( $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 567                 }
 568
 569                 if ( isset( $wgProfiler ) ) {
 570                         wfProfileOut( $queryProf );
 571                         wfProfileOut( $totalProf );
 572                 }
 573                 return $this->resultObject( $ret );
 574         }
 575
 576         /**
 577          * The DBMS-dependent part of query()
 578          * @param  $sql String: SQL query.
 579          * @return Result object to feed to fetchObject, fetchRow, ...; or false on failure
 580          * @access private
 581          */
 582         /*private*/ function doQuery( $sql ) {
 583                 if( $this->bufferResults() ) {
 584                         $ret = mysql_query( $sql, $this->mConn );
 585                 } else {
 586                         $ret = mysql_unbuffered_query( $sql, $this->mConn );
 587                 }
 588                 return $ret;
 589         }
 590
 591         /**
 592          * @param $error
 593          * @param $errno
 594          * @param $sql
 595          * @param string $fname
 596          * @param bool $tempIgnore
 597          */
 598         function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 599                 global $wgCommandLineMode;
 600                 # Ignore errors during error handling to avoid infinite recursion
 601                 $ignore = $this->ignoreErrors( true );
 602                 ++$this->mErrorCount;
 603
 604                 if( $ignore || $tempIgnore ) {
 605                         wfDebug("SQL ERROR (ignored): $error\n");
 606                         $this->ignoreErrors( $ignore );
 607                 } else {
 608                         $sql1line = str_replace( "\n", "\\n", $sql );
 609                         wfLogDBError("$fname\t{$this->mServer}\t$errno\t$error\t$sql1line\n");
 610                         wfDebug("SQL ERROR: " . $error . "\n");
 611                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
 612                 }
 613         }
 614
 615
 616         /**
 617          * Intended to be compatible with the PEAR::DB wrapper functions.
 618          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
 619          *
 620          * ? = scalar value, quoted as necessary
 621          * ! = raw SQL bit (a function for instance)
 622          * & = filename; reads the file and inserts as a blob
 623          *     (we don't use this though...)
 624          */
 625         function prepare( $sql, $func = 'Database::prepare' ) {
 626                 /* MySQL doesn't support prepared statements (yet), so just
 627                    pack up the query for reference. We'll manually replace
 628                    the bits later. */
 629                 return array( 'query' => $sql, 'func' => $func );
 630         }
 631
 632         function freePrepared( $prepared ) {
 633                 /* No-op for MySQL */
 634         }
 635
 636         /**
 637          * Execute a prepared query with the various arguments
 638          * @param string $prepared the prepared sql
 639          * @param mixed $args Either an array here, or put scalars as varargs
 640          */
 641         function execute( $prepared, $args = null ) {
 642                 if( !is_array( $args ) ) {
 643                         # Pull the var args
 644                         $args = func_get_args();
 645                         array_shift( $args );
 646                 }
 647                 $sql = $this->fillPrepared( $prepared['query'], $args );
 648                 return $this->query( $sql, $prepared['func'] );
 649         }
 650
 651         /**
 652          * Prepare & execute an SQL statement, quoting and inserting arguments
 653          * in the appropriate places.
 654          * @param string $query
 655          * @param string $args ...
 656          */
 657         function safeQuery( $query, $args = null ) {
 658                 $prepared = $this->prepare( $query, 'Database::safeQuery' );
 659                 if( !is_array( $args ) ) {
 660                         # Pull the var args
 661                         $args = func_get_args();
 662                         array_shift( $args );
 663                 }
 664                 $retval = $this->execute( $prepared, $args );
 665                 $this->freePrepared( $prepared );
 666                 return $retval;
 667         }
 668
 669         /**
 670          * For faking prepared SQL statements on DBs that don't support
 671          * it directly.
 672          * @param string $preparedSql - a 'preparable' SQL statement
 673          * @param array $args - array of arguments to fill it with
 674          * @return string executable SQL
 675          */
 676         function fillPrepared( $preparedQuery, $args ) {
 677                 reset( $args );
 678                 $this->preparedArgs =& $args;
 679                 return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
 680                         array( &$this, 'fillPreparedArg' ), $preparedQuery );
 681         }
 682
 683         /**
 684          * preg_callback func for fillPrepared()
 685          * The arguments should be in $this->preparedArgs and must not be touched
 686          * while we're doing this.
 687          *
 688          * @param array $matches
 689          * @return string
 690          * @private
 691          */
 692         function fillPreparedArg( $matches ) {
 693                 switch( $matches[1] ) {
 694                         case '\\?': return '?';
 695                         case '\\!': return '!';
 696                         case '\\&': return '&';
 697                 }
 698                 list( /* $n */ , $arg ) = each( $this->preparedArgs );
 699                 switch( $matches[1] ) {
 700                         case '?': return $this->addQuotes( $arg );
 701                         case '!': return $arg;
 702                         case '&':
 703                                 # return $this->addQuotes( file_get_contents( $arg ) );
 704                                 throw new DBUnexpectedError( $this, '& mode is not implemented. If it\'s really needed, uncomment the line above.' );
 705                         default:
 706                                 throw new DBUnexpectedError( $this, 'Received invalid match. This should never happen!' );
 707                 }
 708         }
 709
 710         /**#@+
 711          * @param mixed $res A SQL result
 712          */
 713         /**
 714          * Free a result object
 715          */
 716         function freeResult( $res ) {
 717                 if ( $res instanceof ResultWrapper ) {
 718                         $res = $res->result;
 719                 }
 720                 if ( !@/**/mysql_free_result( $res ) ) {
 721                         throw new DBUnexpectedError( $this, "Unable to free MySQL result" );
 722                 }
 723         }
 724
 725         /**
 726          * Fetch the next row from the given result object, in object form.
 727          * Fields can be retrieved with $row->fieldname, with fields acting like
 728          * member variables.
 729          *
 730          * @param $res SQL result object as returned from Database::query(), etc.
 731          * @return MySQL row object
 732          * @throws DBUnexpectedError Thrown if the database returns an error
 733          */
 734         function fetchObject( $res ) {
 735                 if ( $res instanceof ResultWrapper ) {
 736                         $res = $res->result;
 737                 }
 738                 @/**/$row = mysql_fetch_object( $res );
 739                 if( $this->lastErrno() ) {
 740                         throw new DBUnexpectedError( $this, 'Error in fetchObject(): ' . htmlspecialchars( $this->lastError() ) );
 741                 }
 742                 return $row;
 743         }
 744
 745         /**
 746          * Fetch the next row from the given result object, in associative array
 747          * form.  Fields are retrieved with $row['fieldname'].
 748          *
 749          * @param $res SQL result object as returned from Database::query(), etc.
 750          * @return MySQL row object
 751          * @throws DBUnexpectedError Thrown if the database returns an error
 752          */
 753         function fetchRow( $res ) {
 754                 if ( $res instanceof ResultWrapper ) {
 755                         $res = $res->result;
 756                 }
 757                 @/**/$row = mysql_fetch_array( $res );
 758                 if ( $this->lastErrno() ) {
 759                         throw new DBUnexpectedError( $this, 'Error in fetchRow(): ' . htmlspecialchars( $this->lastError() ) );
 760                 }
 761                 return $row;
 762         }
 763
 764         /**
 765          * Get the number of rows in a result object
 766          */
 767         function numRows( $res ) {
 768                 if ( $res instanceof ResultWrapper ) {
 769                         $res = $res->result;
 770                 }
 771                 @/**/$n = mysql_num_rows( $res );
 772                 if( $this->lastErrno() ) {
 773                         throw new DBUnexpectedError( $this, 'Error in numRows(): ' . htmlspecialchars( $this->lastError() ) );
 774                 }
 775                 return $n;
 776         }
 777
 778         /**
 779          * Get the number of fields in a result object
 780          * See documentation for mysql_num_fields()
 781          */
 782         function numFields( $res ) {
 783                 if ( $res instanceof ResultWrapper ) {
 784                         $res = $res->result;
 785                 }
 786                 return mysql_num_fields( $res );
 787         }
 788
 789         /**
 790          * Get a field name in a result object
 791          * See documentation for mysql_field_name():
 792          * http://www.php.net/mysql_field_name
 793          */
 794         function fieldName( $res, $n ) {
 795                 if ( $res instanceof ResultWrapper ) {
 796                         $res = $res->result;
 797                 }
 798                 return mysql_field_name( $res, $n );
 799         }
 800
 801         /**
 802          * Get the inserted value of an auto-increment row
 803          *
 804          * The value inserted should be fetched from nextSequenceValue()
 805          *
 806          * Example:
 807          * $id = $dbw->nextSequenceValue('page_page_id_seq');
 808          * $dbw->insert('page',array('page_id' => $id));
 809          * $id = $dbw->insertId();
 810          */
 811         function insertId() { return mysql_insert_id( $this->mConn ); }
 812
 813         /**
 814          * Change the position of the cursor in a result object
 815          * See mysql_data_seek()
 816          */
 817         function dataSeek( $res, $row ) {
 818                 if ( $res instanceof ResultWrapper ) {
 819                         $res = $res->result;
 820                 }
 821                 return mysql_data_seek( $res, $row );
 822         }
 823
 824         /**
 825          * Get the last error number
 826          * See mysql_errno()
 827          */
 828         function lastErrno() {
 829                 if ( $this->mConn ) {
 830                         return mysql_errno( $this->mConn );
 831                 } else {
 832                         return mysql_errno();
 833                 }
 834         }
 835
 836         /**
 837          * Get a description of the last error
 838          * See mysql_error() for more details
 839          */
 840         function lastError() {
 841                 if ( $this->mConn ) {
 842                         # Even if it's non-zero, it can still be invalid
 843                         wfSuppressWarnings();
 844                         $error = mysql_error( $this->mConn );
 845                         if ( !$error ) {
 846                                 $error = mysql_error();
 847                         }
 848                         wfRestoreWarnings();
 849                 } else {
 850                         $error = mysql_error();
 851                 }
 852                 if( $error ) {
 853                         $error .= ' (' . $this->mServer . ')';
 854                 }
 855                 return $error;
 856         }
 857         /**
 858          * Get the number of rows affected by the last write query
 859          * See mysql_affected_rows() for more details
 860          */
 861         function affectedRows() { return mysql_affected_rows( $this->mConn ); }
 862         /**#@-*/ // end of template : @param $result
 863
 864         /**
 865          * Simple UPDATE wrapper
 866          * Usually aborts on failure
 867          * If errors are explicitly ignored, returns success
 868          *
 869          * This function exists for historical reasons, Database::update() has a more standard
 870          * calling convention and feature set
 871          */
 872         function set( $table, $var, $value, $cond, $fname = 'Database::set' )
 873         {
 874                 $table = $this->tableName( $table );
 875                 $sql = "UPDATE $table SET $var = '" .
 876                   $this->strencode( $value ) . "' WHERE ($cond)";
 877                 return (bool)$this->query( $sql, $fname );
 878         }
 879
 880         /**
 881          * Simple SELECT wrapper, returns a single field, input must be encoded
 882          * Usually aborts on failure
 883          * If errors are explicitly ignored, returns FALSE on failure
 884          */
 885         function selectField( $table, $var, $cond='', $fname = 'Database::selectField', $options = array() ) {
 886                 if ( !is_array( $options ) ) {
 887                         $options = array( $options );
 888                 }
 889                 $options['LIMIT'] = 1;
 890
 891                 $res = $this->select( $table, $var, $cond, $fname, $options );
 892                 if ( $res === false || !$this->numRows( $res ) ) {
 893                         return false;
 894                 }
 895                 $row = $this->fetchRow( $res );
 896                 if ( $row !== false ) {
 897                         $this->freeResult( $res );
 898                         return $row[0];
 899                 } else {
 900                         return false;
 901                 }
 902         }
 903
 904         /**
 905          * Returns an optional USE INDEX clause to go after the table, and a
 906          * string to go at the end of the query
 907          *
 908          * @private
 909          *
 910          * @param array $options an associative array of options to be turned into
 911          *              an SQL query, valid keys are listed in the function.
 912          * @return array
 913          */
 914         function makeSelectOptions( $options ) {
 915                 $preLimitTail = $postLimitTail = '';
 916                 $startOpts = '';
 917
 918                 $noKeyOptions = array();
 919                 foreach ( $options as $key => $option ) {
 920                         if ( is_numeric( $key ) ) {
 921                                 $noKeyOptions[$option] = true;
 922                         }
 923                 }
 924
 925                 if ( isset( $options['GROUP BY'] ) ) $preLimitTail .= " GROUP BY {$options['GROUP BY']}";
 926                 if ( isset( $options['HAVING'] ) ) $preLimitTail .= " HAVING {$options['HAVING']}";
 927                 if ( isset( $options['ORDER BY'] ) ) $preLimitTail .= " ORDER BY {$options['ORDER BY']}";
 928
 929                 //if (isset($options['LIMIT'])) {
 930                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
 931                 //              isset($options['OFFSET']) ? $options['OFFSET']
 932                 //              : false);
 933                 //}
 934
 935                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) $postLimitTail .= ' FOR UPDATE';
 936                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) $postLimitTail .= ' LOCK IN SHARE MODE';
 937                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) $startOpts .= 'DISTINCT';
 938
 939                 # Various MySQL extensions
 940                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) $startOpts .= ' /*! STRAIGHT_JOIN */';
 941                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) $startOpts .= ' HIGH_PRIORITY';
 942                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) $startOpts .= ' SQL_BIG_RESULT';
 943                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) $startOpts .= ' SQL_BUFFER_RESULT';
 944                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) $startOpts .= ' SQL_SMALL_RESULT';
 945                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) $startOpts .= ' SQL_CALC_FOUND_ROWS';
 946                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) $startOpts .= ' SQL_CACHE';
 947                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) $startOpts .= ' SQL_NO_CACHE';
 948
 949                 if ( isset( $options['USE INDEX'] ) && ! is_array( $options['USE INDEX'] ) ) {
 950                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
 951                 } else {
 952                         $useIndex = '';
 953                 }
 954
 955                 return array( $startOpts, $useIndex, $preLimitTail, $postLimitTail );
 956         }
 957
 958         /**
 959          * SELECT wrapper
 960          *
 961          * @param mixed  $table   Array or string, table name(s) (prefix auto-added)
 962          * @param mixed  $vars    Array or string, field name(s) to be retrieved
 963          * @param mixed  $conds   Array or string, condition(s) for WHERE
 964          * @param string $fname   Calling function name (use __METHOD__) for logs/profiling
 965          * @param array  $options Associative array of options (e.g. array('GROUP BY' => 'page_title')),
 966          *                        see Database::makeSelectOptions code for list of supported stuff
 967          * @param array $join_conds Associative array of table join conditions (optional)
 968          *                        (e.g. array( 'page' => array('LEFT JOIN','page_latest=rev_id') )
 969          * @return mixed Database result resource (feed to Database::fetchObject or whatever), or false on failure
 970          */
 971         function select( $table, $vars, $conds='', $fname = 'Database::select', $options = array(), $join_conds = array() )
 972         {
 973                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
 974                 return $this->query( $sql, $fname );
 975         }
 976
 977         /**
 978          * SELECT wrapper
 979          *
 980          * @param mixed  $table   Array or string, table name(s) (prefix auto-added)
 981          * @param mixed  $vars    Array or string, field name(s) to be retrieved
 982          * @param mixed  $conds   Array or string, condition(s) for WHERE
 983          * @param string $fname   Calling function name (use __METHOD__) for logs/profiling
 984          * @param array  $options Associative array of options (e.g. array('GROUP BY' => 'page_title')),
 985          *                        see Database::makeSelectOptions code for list of supported stuff
 986          * @param array $join_conds Associative array of table join conditions (optional)
 987          *                        (e.g. array( 'page' => array('LEFT JOIN','page_latest=rev_id') )
 988          * @return string, the SQL text
 989          */
 990         function selectSQLText( $table, $vars, $conds='', $fname = 'Database::select', $options = array(), $join_conds = array() ) {
 991                 if( is_array( $vars ) ) {
 992                         $vars = implode( ',', $vars );
 993                 }
 994                 if( !is_array( $options ) ) {
 995                         $options = array( $options );
 996                 }
 997                 if( is_array( $table ) ) {
 998                         if ( !empty($join_conds) || ( isset( $options['USE INDEX'] ) && is_array( @$options['USE INDEX'] ) ) )
 999                                 $from = ' FROM ' . $this->tableNamesWithUseIndexOrJOIN( $table, @$options['USE INDEX'], $join_conds );
1000                         else
1001                                 $from = ' FROM ' . implode( ',', array_map( array( &$this, 'tableName' ), $table ) );
1002                 } elseif ($table!='') {
1003                         if ($table{0}==' ') {
1004                                 $from = ' FROM ' . $table;
1005                         } else {
1006                                 $from = ' FROM ' . $this->tableName( $table );
1007                         }
1008                 } else {
1009                         $from = '';
1010                 }
1011
1012                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail ) = $this->makeSelectOptions( $options );
1013
1014                 if( !empty( $conds ) ) {
1015                         if ( is_array( $conds ) ) {
1016                                 $conds = $this->makeList( $conds, LIST_AND );
1017                         }
1018                         $sql = "SELECT $startOpts $vars $from $useIndex WHERE $conds $preLimitTail";
1019                 } else {
1020                         $sql = "SELECT $startOpts $vars $from $useIndex $preLimitTail";
1021                 }
1022
1023                 if (isset($options['LIMIT']))
1024                         $sql = $this->limitResult($sql, $options['LIMIT'],
1025                                 isset($options['OFFSET']) ? $options['OFFSET'] : false);
1026                 $sql = "$sql $postLimitTail";
1027
1028                 if (isset($options['EXPLAIN'])) {
1029                         $sql = 'EXPLAIN ' . $sql;
1030                 }
1031                 return $sql;
1032         }
1033
1034         /**
1035          * Single row SELECT wrapper
1036          * Aborts or returns FALSE on error
1037          *
1038          * $vars: the selected variables
1039          * $conds: a condition map, terms are ANDed together.
1040          *   Items with numeric keys are taken to be literal conditions
1041          * Takes an array of selected variables, and a condition map, which is ANDed
1042          * e.g: selectRow( "page", array( "page_id" ), array( "page_namespace" =>
1043          * NS_MAIN, "page_title" => "Astronomy" ) )   would return an object where
1044          * $obj- >page_id is the ID of the Astronomy article
1045          *
1046          * @todo migrate documentation to phpdocumentor format
1047          */
1048         function selectRow( $table, $vars, $conds, $fname = 'Database::selectRow', $options = array(), $join_conds = array() ) {
1049                 $options['LIMIT'] = 1;
1050                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1051                 if ( $res === false )
1052                         return false;
1053                 if ( !$this->numRows($res) ) {
1054                         $this->freeResult($res);
1055                         return false;
1056                 }
1057                 $obj = $this->fetchObject( $res );
1058                 $this->freeResult( $res );
1059                 return $obj;
1060
1061         }
1062
1063         /**
1064          * Estimate rows in dataset
1065          * Returns estimated count, based on EXPLAIN output
1066          * Takes same arguments as Database::select()
1067          */
1068
1069         function estimateRowCount( $table, $vars='*', $conds='', $fname = 'Database::estimateRowCount', $options = array() ) {
1070                 $options['EXPLAIN']=true;
1071                 $res = $this->select ($table, $vars, $conds, $fname, $options );
1072                 if ( $res === false )
1073                         return false;
1074                 if (!$this->numRows($res)) {
1075                         $this->freeResult($res);
1076                         return 0;
1077                 }
1078
1079                 $rows=1;
1080
1081                 while( $plan = $this->fetchObject( $res ) ) {
1082                         $rows *= ($plan->rows > 0)?$plan->rows:1; // avoid resetting to zero
1083                 }
1084
1085                 $this->freeResult($res);
1086                 return $rows;
1087         }
1088
1089
1090         /**
1091          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1092          * It's only slightly flawed. Don't use for anything important.
1093          *
1094          * @param string $sql A SQL Query
1095          * @static
1096          */
1097         static function generalizeSQL( $sql ) {
1098                 # This does the same as the regexp below would do, but in such a way
1099                 # as to avoid crashing php on some large strings.
1100                 # $sql = preg_replace ( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql);
1101
1102                 $sql = str_replace ( "\\\\", '', $sql);
1103                 $sql = str_replace ( "\\'", '', $sql);
1104                 $sql = str_replace ( "\\\"", '', $sql);
1105                 $sql = preg_replace ("/'.*'/s", "'X'", $sql);
1106                 $sql = preg_replace ('/".*"/s', "'X'", $sql);
1107
1108                 # All newlines, tabs, etc replaced by single space
1109                 $sql = preg_replace ( '/\s+/', ' ', $sql);
1110
1111                 # All numbers => N
1112                 $sql = preg_replace ('/-?[0-9]+/s', 'N', $sql);
1113
1114                 return $sql;
1115         }
1116
1117         /**
1118          * Determines whether a field exists in a table
1119          * Usually aborts on failure
1120          * If errors are explicitly ignored, returns NULL on failure
1121          */
1122         function fieldExists( $table, $field, $fname = 'Database::fieldExists' ) {
1123                 $table = $this->tableName( $table );
1124                 $res = $this->query( 'DESCRIBE '.$table, $fname );
1125                 if ( !$res ) {
1126                         return NULL;
1127                 }
1128
1129                 $found = false;
1130
1131                 while ( $row = $this->fetchObject( $res ) ) {
1132                         if ( $row->Field == $field ) {
1133                                 $found = true;
1134                                 break;
1135                         }
1136                 }
1137                 return $found;
1138         }
1139
1140         /**
1141          * Determines whether an index exists
1142          * Usually aborts on failure
1143          * If errors are explicitly ignored, returns NULL on failure
1144          */
1145         function indexExists( $table, $index, $fname = 'Database::indexExists' ) {
1146                 $info = $this->indexInfo( $table, $index, $fname );
1147                 if ( is_null( $info ) ) {
1148                         return NULL;
1149                 } else {
1150                         return $info !== false;
1151                 }
1152         }
1153
1154
1155         /**
1156          * Get information about an index into an object
1157          * Returns false if the index does not exist
1158          */
1159         function indexInfo( $table, $index, $fname = 'Database::indexInfo' ) {
1160                 # SHOW INDEX works in MySQL 3.23.58, but SHOW INDEXES does not.
1161                 # SHOW INDEX should work for 3.x and up:
1162                 # http://dev.mysql.com/doc/mysql/en/SHOW_INDEX.html
1163                 $table = $this->tableName( $table );
1164                 $sql = 'SHOW INDEX FROM '.$table;
1165                 $res = $this->query( $sql, $fname );
1166                 if ( !$res ) {
1167                         return NULL;
1168                 }
1169
1170                 $result = array();
1171                 while ( $row = $this->fetchObject( $res ) ) {
1172                         if ( $row->Key_name == $index ) {
1173                                 $result[] = $row;
1174                         }
1175                 }
1176                 $this->freeResult($res);
1177
1178                 return empty($result) ? false : $result;
1179         }
1180
1181         /**
1182          * Query whether a given table exists
1183          */
1184         function tableExists( $table ) {
1185                 $table = $this->tableName( $table );
1186                 $old = $this->ignoreErrors( true );
1187                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1" );
1188                 $this->ignoreErrors( $old );
1189                 if( $res ) {
1190                         $this->freeResult( $res );
1191                         return true;
1192                 } else {
1193                         return false;
1194                 }
1195         }
1196
1197         /**
1198          * mysql_fetch_field() wrapper
1199          * Returns false if the field doesn't exist
1200          *
1201          * @param $table
1202          * @param $field
1203          */
1204         function fieldInfo( $table, $field ) {
1205                 $table = $this->tableName( $table );
1206                 $res = $this->query( "SELECT * FROM $table LIMIT 1" );
1207                 $n = mysql_num_fields( $res->result );
1208                 for( $i = 0; $i < $n; $i++ ) {
1209                         $meta = mysql_fetch_field( $res->result, $i );
1210                         if( $field == $meta->name ) {
1211                                 return new MySQLField($meta);
1212                         }
1213                 }
1214                 return false;
1215         }
1216
1217         /**
1218          * mysql_field_type() wrapper
1219          */
1220         function fieldType( $res, $index ) {
1221                 if ( $res instanceof ResultWrapper ) {
1222                         $res = $res->result;
1223                 }
1224                 return mysql_field_type( $res, $index );
1225         }
1226
1227         /**
1228          * Determines if a given index is unique
1229          */
1230         function indexUnique( $table, $index ) {
1231                 $indexInfo = $this->indexInfo( $table, $index );
1232                 if ( !$indexInfo ) {
1233                         return NULL;
1234                 }
1235                 return !$indexInfo[0]->Non_unique;
1236         }
1237
1238         /**
1239          * INSERT wrapper, inserts an array into a table
1240          *
1241          * $a may be a single associative array, or an array of these with numeric keys, for
1242          * multi-row insert.
1243          *
1244          * Usually aborts on failure
1245          * If errors are explicitly ignored, returns success
1246          */
1247         function insert( $table, $a, $fname = 'Database::insert', $options = array() ) {
1248                 # No rows to insert, easy just return now
1249                 if ( !count( $a ) ) {
1250                         return true;
1251                 }
1252
1253                 $table = $this->tableName( $table );
1254                 if ( !is_array( $options ) ) {
1255                         $options = array( $options );
1256                 }
1257                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1258                         $multi = true;
1259                         $keys = array_keys( $a[0] );
1260                 } else {
1261                         $multi = false;
1262                         $keys = array_keys( $a );
1263                 }
1264
1265                 $sql = 'INSERT ' . implode( ' ', $options ) .
1266                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1267
1268                 if ( $multi ) {
1269                         $first = true;
1270                         foreach ( $a as $row ) {
1271                                 if ( $first ) {
1272                                         $first = false;
1273                                 } else {
1274                                         $sql .= ',';
1275                                 }
1276                                 $sql .= '(' . $this->makeList( $row ) . ')';
1277                         }
1278                 } else {
1279                         $sql .= '(' . $this->makeList( $a ) . ')';
1280                 }
1281                 return (bool)$this->query( $sql, $fname );
1282         }
1283
1284         /**
1285          * Make UPDATE options for the Database::update function
1286          *
1287          * @private
1288          * @param array $options The options passed to Database::update
1289          * @return string
1290          */
1291         function makeUpdateOptions( $options ) {
1292                 if( !is_array( $options ) ) {
1293                         $options = array( $options );
1294                 }
1295                 $opts = array();
1296                 if ( in_array( 'LOW_PRIORITY', $options ) )
1297                         $opts[] = $this->lowPriorityOption();
1298                 if ( in_array( 'IGNORE', $options ) )
1299                         $opts[] = 'IGNORE';
1300                 return implode(' ', $opts);
1301         }
1302
1303         /**
1304          * UPDATE wrapper, takes a condition array and a SET array
1305          *
1306          * @param string $table  The table to UPDATE
1307          * @param array  $values An array of values to SET
1308          * @param array  $conds  An array of conditions (WHERE). Use '*' to update all rows.
1309          * @param string $fname  The Class::Function calling this function
1310          *                       (for the log)
1311          * @param array  $options An array of UPDATE options, can be one or
1312          *                        more of IGNORE, LOW_PRIORITY
1313          * @return bool
1314          */
1315         function update( $table, $values, $conds, $fname = 'Database::update', $options = array() ) {
1316                 $table = $this->tableName( $table );
1317                 $opts = $this->makeUpdateOptions( $options );
1318                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1319                 if ( $conds != '*' ) {
1320                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1321                 }
1322                 return $this->query( $sql, $fname );
1323         }
1324
1325         /**
1326          * Makes an encoded list of strings from an array
1327          * $mode:
1328          *        LIST_COMMA         - comma separated, no field names
1329          *        LIST_AND           - ANDed WHERE clause (without the WHERE)
1330          *        LIST_OR            - ORed WHERE clause (without the WHERE)
1331          *        LIST_SET           - comma separated with field names, like a SET clause
1332          *        LIST_NAMES         - comma separated field names
1333          */
1334         function makeList( $a, $mode = LIST_COMMA ) {
1335                 if ( !is_array( $a ) ) {
1336                         throw new DBUnexpectedError( $this, 'Database::makeList called with incorrect parameters' );
1337                 }
1338
1339                 $first = true;
1340                 $list = '';
1341                 foreach ( $a as $field => $value ) {
1342                         if ( !$first ) {
1343                                 if ( $mode == LIST_AND ) {
1344                                         $list .= ' AND ';
1345                                 } elseif($mode == LIST_OR) {
1346                                         $list .= ' OR ';
1347                                 } else {
1348                                         $list .= ',';
1349                                 }
1350                         } else {
1351                                 $first = false;
1352                         }
1353                         if ( ($mode == LIST_AND || $mode == LIST_OR) && is_numeric( $field ) ) {
1354                                 $list .= "($value)";
1355                         } elseif ( ($mode == LIST_SET) && is_numeric( $field ) ) {
1356                                 $list .= "$value";
1357                         } elseif ( ($mode == LIST_AND || $mode == LIST_OR) && is_array($value) ) {
1358                                 if( count( $value ) == 0 ) {
1359                                         throw new MWException( __METHOD__.': empty input' );
1360                                 } elseif( count( $value ) == 1 ) {
1361                                         // Special-case single values, as IN isn't terribly efficient
1362                                         // Don't necessarily assume the single key is 0; we don't
1363                                         // enforce linear numeric ordering on other arrays here.
1364                                         $value = array_values( $value );
1365                                         $list .= $field." = ".$this->addQuotes( $value[0] );
1366                                 } else {
1367                                         $list .= $field." IN (".$this->makeList($value).") ";
1368                                 }
1369                         } elseif( is_null($value) ) {
1370                                 if ( $mode == LIST_AND || $mode == LIST_OR ) {
1371                                         $list .= "$field IS ";
1372                                 } elseif ( $mode == LIST_SET ) {
1373                                         $list .= "$field = ";
1374                                 }
1375                                 $list .= 'NULL';
1376                         } else {
1377                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
1378                                         $list .= "$field = ";
1379                                 }
1380                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
1381                         }
1382                 }
1383                 return $list;
1384         }
1385
1386         /**
1387          * Change the current database
1388          */
1389         function selectDB( $db ) {
1390                 $this->mDBname = $db;
1391                 return mysql_select_db( $db, $this->mConn );
1392         }
1393
1394         /**
1395          * Get the current DB name
1396          */
1397         function getDBname() {
1398                 return $this->mDBname;
1399         }
1400
1401         /**
1402          * Get the server hostname or IP address
1403          */
1404         function getServer() {
1405                 return $this->mServer;
1406         }
1407
1408         /**
1409          * Format a table name ready for use in constructing an SQL query
1410          *
1411          * This does two important things: it quotes the table names to clean them up,
1412          * and it adds a table prefix if only given a table name with no quotes.
1413          *
1414          * All functions of this object which require a table name call this function
1415          * themselves. Pass the canonical name to such functions. This is only needed
1416          * when calling query() directly.
1417          *
1418          * @param string $name database table name
1419          * @return string full database name
1420          */
1421         function tableName( $name ) {
1422                 global $wgSharedDB, $wgSharedPrefix, $wgSharedTables;
1423                 # Skip the entire process when we have a string quoted on both ends.
1424                 # Note that we check the end so that we will still quote any use of
1425                 # use of `database`.table. But won't break things if someone wants
1426                 # to query a database table with a dot in the name.
1427                 if ( $name[0] == '`' && substr( $name, -1, 1 ) == '`' ) return $name;
1428
1429                 # Lets test for any bits of text that should never show up in a table
1430                 # name. Basically anything like JOIN or ON which are actually part of
1431                 # SQL queries, but may end up inside of the table value to combine
1432                 # sql. Such as how the API is doing.
1433                 # Note that we use a whitespace test rather than a \b test to avoid
1434                 # any remote case where a word like on may be inside of a table name
1435                 # surrounded by symbols which may be considered word breaks.
1436                 if( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) return $name;
1437
1438                 # Split database and table into proper variables.
1439                 # We reverse the explode so that database.table and table both output
1440                 # the correct table.
1441                 $dbDetails = array_reverse( explode( '.', $name, 2 ) );
1442                 if( isset( $dbDetails[1] ) ) @list( $table, $database ) = $dbDetails;
1443                 else                         @list( $table ) = $dbDetails;
1444                 $prefix = $this->mTablePrefix; # Default prefix
1445
1446                 # A database name has been specified in input. Quote the table name
1447                 # because we don't want any prefixes added.
1448                 if( isset($database) ) $table = ( $table[0] == '`' ? $table : "`{$table}`" );
1449
1450                 # Note that we use the long format because php will complain in in_array if
1451                 # the input is not an array, and will complain in is_array if it is not set.
1452                 if( !isset( $database ) # Don't use shared database if pre selected.
1453                  && isset( $wgSharedDB ) # We have a shared database
1454                  && $table[0] != '`' # Paranoia check to prevent shared tables listing '`table`'
1455                  && isset( $wgSharedTables )
1456                  && is_array( $wgSharedTables )
1457                  && in_array( $table, $wgSharedTables ) ) { # A shared table is selected
1458                         $database = $wgSharedDB;
1459                         $prefix   = isset( $wgSharedPrefix ) ? $wgSharedPrefix : $prefix;
1460                 }
1461
1462                 # Quote the $database and $table and apply the prefix if not quoted.
1463                 if( isset($database) ) $database = ( $database[0] == '`' ? $database : "`{$database}`" );
1464                 $table = ( $table[0] == '`' ? $table : "`{$prefix}{$table}`" );
1465
1466                 # Merge our database and table into our final table name.
1467                 $tableName = ( isset($database) ? "{$database}.{$table}" : "{$table}" );
1468
1469                 # We're finished, return.
1470                 return $tableName;
1471         }
1472
1473         /**
1474          * Fetch a number of table names into an array
1475          * This is handy when you need to construct SQL for joins
1476          *
1477          * Example:
1478          * extract($dbr->tableNames('user','watchlist'));
1479          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1480          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1481          */
1482         public function tableNames() {
1483                 $inArray = func_get_args();
1484                 $retVal = array();
1485                 foreach ( $inArray as $name ) {
1486                         $retVal[$name] = $this->tableName( $name );
1487                 }
1488                 return $retVal;
1489         }
1490
1491         /**
1492          * Fetch a number of table names into an zero-indexed numerical array
1493          * This is handy when you need to construct SQL for joins
1494          *
1495          * Example:
1496          * list( $user, $watchlist ) = $dbr->tableNamesN('user','watchlist');
1497          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1498          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1499          */
1500         public function tableNamesN() {
1501                 $inArray = func_get_args();
1502                 $retVal = array();
1503                 foreach ( $inArray as $name ) {
1504                         $retVal[] = $this->tableName( $name );
1505                 }
1506                 return $retVal;
1507         }
1508
1509         /**
1510          * @private
1511          */
1512         function tableNamesWithUseIndexOrJOIN( $tables, $use_index = array(), $join_conds = array() ) {
1513                 $ret = array();
1514                 $retJOIN = array();
1515                 $use_index_safe = is_array($use_index) ? $use_index : array();
1516                 $join_conds_safe = is_array($join_conds) ? $join_conds : array();
1517                 foreach ( $tables as $table ) {
1518                         // Is there a JOIN and INDEX clause for this table?
1519                         if ( isset($join_conds_safe[$table]) && isset($use_index_safe[$table]) ) {
1520                                 $tableClause = $join_conds_safe[$table][0] . ' ' . $this->tableName( $table );
1521                                 $tableClause .= ' ' . $this->useIndexClause( implode( ',', (array)$use_index_safe[$table] ) );
1522                                 $tableClause .= ' ON (' . $this->makeList((array)$join_conds_safe[$table][1], LIST_AND) . ')';
1523                                 $retJOIN[] = $tableClause;
1524                         // Is there an INDEX clause?
1525                         } else if ( isset($use_index_safe[$table]) ) {
1526                                 $tableClause = $this->tableName( $table );
1527                                 $tableClause .= ' ' . $this->useIndexClause( implode( ',', (array)$use_index_safe[$table] ) );
1528                                 $ret[] = $tableClause;
1529                         // Is there a JOIN clause?
1530                         } else if ( isset($join_conds_safe[$table]) ) {
1531                                 $tableClause = $join_conds_safe[$table][0] . ' ' . $this->tableName( $table );
1532                                 $tableClause .= ' ON (' . $this->makeList((array)$join_conds_safe[$table][1], LIST_AND) . ')';
1533                                 $retJOIN[] = $tableClause;
1534                         } else {
1535                                 $tableClause = $this->tableName( $table );
1536                                 $ret[] = $tableClause;
1537                         }
1538                 }
1539                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
1540                 $straightJoins = !empty($ret) ? implode( ',', $ret ) : "";
1541                 $otherJoins = !empty($retJOIN) ? implode( ' ', $retJOIN ) : "";
1542                 // Compile our final table clause
1543                 return implode(' ',array($straightJoins,$otherJoins) );
1544         }
1545
1546         /**
1547          * Wrapper for addslashes()
1548          * @param string $s String to be slashed.
1549          * @return string slashed string.
1550          */
1551         function strencode( $s ) {
1552                 return mysql_real_escape_string( $s, $this->mConn );
1553         }
1554
1555         /**
1556          * If it's a string, adds quotes and backslashes
1557          * Otherwise returns as-is
1558          */
1559         function addQuotes( $s ) {
1560                 if ( is_null( $s ) ) {
1561                         return 'NULL';
1562                 } else {
1563                         # This will also quote numeric values. This should be harmless,
1564                         # and protects against weird problems that occur when they really
1565                         # _are_ strings such as article titles and string->number->string
1566                         # conversion is not 1:1.
1567                         return "'" . $this->strencode( $s ) . "'";
1568                 }
1569         }
1570
1571         /**
1572          * Escape string for safe LIKE usage
1573          */
1574         function escapeLike( $s ) {
1575                 $s=$this->strencode( $s );
1576                 $s=str_replace(array('%','_'),array('\%','\_'),$s);
1577                 return $s;
1578         }
1579
1580         /**
1581          * Returns an appropriately quoted sequence value for inserting a new row.
1582          * MySQL has autoincrement fields, so this is just NULL. But the PostgreSQL
1583          * subclass will return an integer, and save the value for insertId()
1584          */
1585         function nextSequenceValue( $seqName ) {
1586                 return NULL;
1587         }
1588
1589         /**
1590          * USE INDEX clause
1591          * PostgreSQL doesn't have them and returns ""
1592          */
1593         function useIndexClause( $index ) {
1594                 return "FORCE INDEX ($index)";
1595         }
1596
1597         /**
1598          * REPLACE query wrapper
1599          * PostgreSQL simulates this with a DELETE followed by INSERT
1600          * $row is the row to insert, an associative array
1601          * $uniqueIndexes is an array of indexes. Each element may be either a
1602          * field name or an array of field names
1603          *
1604          * It may be more efficient to leave off unique indexes which are unlikely to collide.
1605          * However if you do this, you run the risk of encountering errors which wouldn't have
1606          * occurred in MySQL
1607          *
1608          * @todo migrate comment to phodocumentor format
1609          */
1610         function replace( $table, $uniqueIndexes, $rows, $fname = 'Database::replace' ) {
1611                 $table = $this->tableName( $table );
1612
1613                 # Single row case
1614                 if ( !is_array( reset( $rows ) ) ) {
1615                         $rows = array( $rows );
1616                 }
1617
1618                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) .') VALUES ';
1619                 $first = true;
1620                 foreach ( $rows as $row ) {
1621                         if ( $first ) {
1622                                 $first = false;
1623                         } else {
1624                                 $sql .= ',';
1625                         }
1626                         $sql .= '(' . $this->makeList( $row ) . ')';
1627                 }
1628                 return $this->query( $sql, $fname );
1629         }
1630
1631         /**
1632          * DELETE where the condition is a join
1633          * MySQL does this with a multi-table DELETE syntax, PostgreSQL does it with sub-selects
1634          *
1635          * For safety, an empty $conds will not delete everything. If you want to delete all rows where the
1636          * join condition matches, set $conds='*'
1637          *
1638          * DO NOT put the join condition in $conds
1639          *
1640          * @param string $delTable The table to delete from.
1641          * @param string $joinTable The other table.
1642          * @param string $delVar The variable to join on, in the first table.
1643          * @param string $joinVar The variable to join on, in the second table.
1644          * @param array $conds Condition array of field names mapped to variables, ANDed together in the WHERE clause
1645          */
1646         function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds, $fname = 'Database::deleteJoin' ) {
1647                 if ( !$conds ) {
1648                         throw new DBUnexpectedError( $this, 'Database::deleteJoin() called with empty $conds' );
1649                 }
1650
1651                 $delTable = $this->tableName( $delTable );
1652                 $joinTable = $this->tableName( $joinTable );
1653                 $sql = "DELETE $delTable FROM $delTable, $joinTable WHERE $delVar=$joinVar ";
1654                 if ( $conds != '*' ) {
1655                         $sql .= ' AND ' . $this->makeList( $conds, LIST_AND );
1656                 }
1657
1658                 return $this->query( $sql, $fname );
1659         }
1660
1661         /**
1662          * Returns the size of a text field, or -1 for "unlimited"
1663          */
1664         function textFieldSize( $table, $field ) {
1665                 $table = $this->tableName( $table );
1666                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
1667                 $res = $this->query( $sql, 'Database::textFieldSize' );
1668                 $row = $this->fetchObject( $res );
1669                 $this->freeResult( $res );
1670
1671                 $m = array();
1672                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
1673                         $size = $m[1];
1674                 } else {
1675                         $size = -1;
1676                 }
1677                 return $size;
1678         }
1679
1680         /**
1681          * @return string Returns the text of the low priority option if it is supported, or a blank string otherwise
1682          */
1683         function lowPriorityOption() {
1684                 return 'LOW_PRIORITY';
1685         }
1686
1687         /**
1688          * DELETE query wrapper
1689          *
1690          * Use $conds == "*" to delete all rows
1691          */
1692         function delete( $table, $conds, $fname = 'Database::delete' ) {
1693                 if ( !$conds ) {
1694                         throw new DBUnexpectedError( $this, 'Database::delete() called with no conditions' );
1695                 }
1696                 $table = $this->tableName( $table );
1697                 $sql = "DELETE FROM $table";
1698                 if ( $conds != '*' ) {
1699                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1700                 }
1701                 return $this->query( $sql, $fname );
1702         }
1703
1704         /**
1705          * INSERT SELECT wrapper
1706          * $varMap must be an associative array of the form array( 'dest1' => 'source1', ...)
1707          * Source items may be literals rather than field names, but strings should be quoted with Database::addQuotes()
1708          * $conds may be "*" to copy the whole table
1709          * srcTable may be an array of tables.
1710          */
1711         function insertSelect( $destTable, $srcTable, $varMap, $conds, $fname = 'Database::insertSelect',
1712                 $insertOptions = array(), $selectOptions = array() )
1713         {
1714                 $destTable = $this->tableName( $destTable );
1715                 if ( is_array( $insertOptions ) ) {
1716                         $insertOptions = implode( ' ', $insertOptions );
1717                 }
1718                 if( !is_array( $selectOptions ) ) {
1719                         $selectOptions = array( $selectOptions );
1720                 }
1721                 list( $startOpts, $useIndex, $tailOpts ) = $this->makeSelectOptions( $selectOptions );
1722                 if( is_array( $srcTable ) ) {
1723                         $srcTable =  implode( ',', array_map( array( &$this, 'tableName' ), $srcTable ) );
1724                 } else {
1725                         $srcTable = $this->tableName( $srcTable );
1726                 }
1727                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
1728                         " SELECT $startOpts " . implode( ',', $varMap ) .
1729                         " FROM $srcTable $useIndex ";
1730                 if ( $conds != '*' ) {
1731                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1732                 }
1733                 $sql .= " $tailOpts";
1734                 return $this->query( $sql, $fname );
1735         }
1736
1737         /**
1738          * Construct a LIMIT query with optional offset
1739          * This is used for query pages
1740          * $sql string SQL query we will append the limit too
1741          * $limit integer the SQL limit
1742          * $offset integer the SQL offset (default false)
1743          */
1744         function limitResult($sql, $limit, $offset=false) {
1745                 if( !is_numeric($limit) ) {
1746                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
1747                 }
1748                 return "$sql LIMIT "
1749                                 . ( (is_numeric($offset) && $offset != 0) ? "{$offset}," : "" )
1750                                 . "{$limit} ";
1751         }
1752         function limitResultForUpdate($sql, $num) {
1753                 return $this->limitResult($sql, $num, 0);
1754         }
1755
1756         /**
1757          * Returns an SQL expression for a simple conditional.
1758          * Uses IF on MySQL.
1759          *
1760          * @param string $cond SQL expression which will result in a boolean value
1761          * @param string $trueVal SQL expression to return if true
1762          * @param string $falseVal SQL expression to return if false
1763          * @return string SQL fragment
1764          */
1765         function conditional( $cond, $trueVal, $falseVal ) {
1766                 return " IF($cond, $trueVal, $falseVal) ";
1767         }
1768
1769         /**
1770          * Returns a comand for str_replace function in SQL query.
1771          * Uses REPLACE() in MySQL
1772          *
1773          * @param string $orig String or column to modify
1774          * @param string $old String or column to seek
1775          * @param string $new String or column to replace with
1776          */
1777         function strreplace( $orig, $old, $new ) {
1778                 return "REPLACE({$orig}, {$old}, {$new})";
1779         }
1780
1781         /**
1782          * Determines if the last failure was due to a deadlock
1783          */
1784         function wasDeadlock() {
1785                 return $this->lastErrno() == 1213;
1786         }
1787
1788         /**
1789          * Perform a deadlock-prone transaction.
1790          *
1791          * This function invokes a callback function to perform a set of write
1792          * queries. If a deadlock occurs during the processing, the transaction
1793          * will be rolled back and the callback function will be called again.
1794          *
1795          * Usage:
1796          *   $dbw->deadlockLoop( callback, ... );
1797          *
1798          * Extra arguments are passed through to the specified callback function.
1799          *
1800          * Returns whatever the callback function returned on its successful,
1801          * iteration, or false on error, for example if the retry limit was
1802          * reached.
1803          */
1804         function deadlockLoop() {
1805                 $myFname = 'Database::deadlockLoop';
1806
1807                 $this->begin();
1808                 $args = func_get_args();
1809                 $function = array_shift( $args );
1810                 $oldIgnore = $this->ignoreErrors( true );
1811                 $tries = DEADLOCK_TRIES;
1812                 if ( is_array( $function ) ) {
1813                         $fname = $function[0];
1814                 } else {
1815                         $fname = $function;
1816                 }
1817                 do {
1818                         $retVal = call_user_func_array( $function, $args );
1819                         $error = $this->lastError();
1820                         $errno = $this->lastErrno();
1821                         $sql = $this->lastQuery();
1822
1823                         if ( $errno ) {
1824                                 if ( $this->wasDeadlock() ) {
1825                                         # Retry
1826                                         usleep( mt_rand( DEADLOCK_DELAY_MIN, DEADLOCK_DELAY_MAX ) );
1827                                 } else {
1828                                         $this->reportQueryError( $error, $errno, $sql, $fname );
1829                                 }
1830                         }
1831                 } while( $this->wasDeadlock() && --$tries > 0 );
1832                 $this->ignoreErrors( $oldIgnore );
1833                 if ( $tries <= 0 ) {
1834                         $this->query( 'ROLLBACK', $myFname );
1835                         $this->reportQueryError( $error, $errno, $sql, $fname );
1836                         return false;
1837                 } else {
1838                         $this->query( 'COMMIT', $myFname );
1839                         return $retVal;
1840                 }
1841         }
1842
1843         /**
1844          * Do a SELECT MASTER_POS_WAIT()
1845          *
1846          * @param string $file the binlog file
1847          * @param string $pos the binlog position
1848          * @param integer $timeout the maximum number of seconds to wait for synchronisation
1849          */
1850         function masterPosWait( MySQLMasterPos $pos, $timeout ) {
1851                 $fname = 'Database::masterPosWait';
1852                 wfProfileIn( $fname );
1853
1854                 # Commit any open transactions
1855                 if ( $this->mTrxLevel ) {
1856                         $this->immediateCommit();
1857                 }
1858
1859                 if ( !is_null( $this->mFakeSlaveLag ) ) {
1860                         $wait = intval( ( $pos->pos - microtime(true) + $this->mFakeSlaveLag ) * 1e6 );
1861                         if ( $wait > $timeout * 1e6 ) {
1862                                 wfDebug( "Fake slave timed out waiting for $pos ($wait us)\n" );
1863                                 wfProfileOut( $fname );
1864                                 return -1;
1865                         } elseif ( $wait > 0 ) {
1866                                 wfDebug( "Fake slave waiting $wait us\n" );
1867                                 usleep( $wait );
1868                                 wfProfileOut( $fname );
1869                                 return 1;
1870                         } else {
1871                                 wfDebug( "Fake slave up to date ($wait us)\n" );
1872                                 wfProfileOut( $fname );
1873                                 return 0;
1874                         }
1875                 }
1876
1877                 # Call doQuery() directly, to avoid opening a transaction if DBO_TRX is set
1878                 $encFile = $this->addQuotes( $pos->file );
1879                 $encPos = intval( $pos->pos );
1880                 $sql = "SELECT MASTER_POS_WAIT($encFile, $encPos, $timeout)";
1881                 $res = $this->doQuery( $sql );
1882                 if ( $res && $row = $this->fetchRow( $res ) ) {
1883                         $this->freeResult( $res );
1884                         wfProfileOut( $fname );
1885                         return $row[0];
1886                 } else {
1887                         wfProfileOut( $fname );
1888                         return false;
1889                 }
1890         }
1891
1892         /**
1893          * Get the position of the master from SHOW SLAVE STATUS
1894          */
1895         function getSlavePos() {
1896                 if ( !is_null( $this->mFakeSlaveLag ) ) {
1897                         $pos = new MySQLMasterPos( 'fake', microtime(true) - $this->mFakeSlaveLag );
1898                         wfDebug( __METHOD__.": fake slave pos = $pos\n" );
1899                         return $pos;
1900                 }
1901                 $res = $this->query( 'SHOW SLAVE STATUS', 'Database::getSlavePos' );
1902                 $row = $this->fetchObject( $res );
1903                 if ( $row ) {
1904                         return new MySQLMasterPos( $row->Master_Log_File, $row->Read_Master_Log_Pos );
1905                 } else {
1906                         return false;
1907                 }
1908         }
1909
1910         /**
1911          * Get the position of the master from SHOW MASTER STATUS
1912          */
1913         function getMasterPos() {
1914                 if ( $this->mFakeMaster ) {
1915                         return new MySQLMasterPos( 'fake', microtime( true ) );
1916                 }
1917                 $res = $this->query( 'SHOW MASTER STATUS', 'Database::getMasterPos' );
1918                 $row = $this->fetchObject( $res );
1919                 if ( $row ) {
1920                         return new MySQLMasterPos( $row->File, $row->Position );
1921                 } else {
1922                         return false;
1923                 }
1924         }
1925
1926         /**
1927          * Begin a transaction, committing any previously open transaction
1928          */
1929         function begin( $fname = 'Database::begin' ) {
1930                 $this->query( 'BEGIN', $fname );
1931                 $this->mTrxLevel = 1;
1932         }
1933
1934         /**
1935          * End a transaction
1936          */
1937         function commit( $fname = 'Database::commit' ) {
1938                 $this->query( 'COMMIT', $fname );
1939                 $this->mTrxLevel = 0;
1940         }
1941
1942         /**
1943          * Rollback a transaction.
1944          * No-op on non-transactional databases.
1945          */
1946         function rollback( $fname = 'Database::rollback' ) {
1947                 $this->query( 'ROLLBACK', $fname, true );
1948                 $this->mTrxLevel = 0;
1949         }
1950
1951         /**
1952          * Begin a transaction, committing any previously open transaction
1953          * @deprecated use begin()
1954          */
1955         function immediateBegin( $fname = 'Database::immediateBegin' ) {
1956                 $this->begin();
1957         }
1958
1959         /**
1960          * Commit transaction, if one is open
1961          * @deprecated use commit()
1962          */
1963         function immediateCommit( $fname = 'Database::immediateCommit' ) {
1964                 $this->commit();
1965         }
1966
1967         /**
1968          * Return MW-style timestamp used for MySQL schema
1969          */
1970         function timestamp( $ts=0 ) {
1971                 return wfTimestamp(TS_MW,$ts);
1972         }
1973
1974         /**
1975          * Local database timestamp format or null
1976          */
1977         function timestampOrNull( $ts = null ) {
1978                 if( is_null( $ts ) ) {
1979                         return null;
1980                 } else {
1981                         return $this->timestamp( $ts );
1982                 }
1983         }
1984
1985         /**
1986          * @todo document
1987          */
1988         function resultObject( $result ) {
1989                 if( empty( $result ) ) {
1990                         return false;
1991                 } elseif ( $result instanceof ResultWrapper ) {
1992                         return $result;
1993                 } elseif ( $result === true ) {
1994                         // Successful write query
1995                         return $result;
1996                 } else {
1997                         return new ResultWrapper( $this, $result );
1998                 }
1999         }
2000
2001         /**
2002          * Return aggregated value alias
2003          */
2004         function aggregateValue ($valuedata,$valuename='value') {
2005                 return $valuename;
2006         }
2007
2008         /**
2009          * @return string wikitext of a link to the server software's web site
2010          */
2011         function getSoftwareLink() {
2012                 return "[http://www.mysql.com/ MySQL]";
2013         }
2014
2015         /**
2016          * @return string Version information from the database
2017          */
2018         function getServerVersion() {
2019                 return mysql_get_server_info( $this->mConn );
2020         }
2021
2022         /**
2023          * Ping the server and try to reconnect if it there is no connection
2024          */
2025         function ping() {
2026                 if( !function_exists( 'mysql_ping' ) ) {
2027                         wfDebug( "Tried to call mysql_ping but this is ancient PHP version. Faking it!\n" );
2028                         return true;
2029                 }
2030                 $ping = mysql_ping( $this->mConn );
2031                 if ( $ping ) {
2032                         return true;
2033                 }
2034
2035                 // Need to reconnect manually in MySQL client 5.0.13+
2036                 if ( version_compare( mysql_get_client_info(), '5.0.13', '>=' ) ) {
2037                         mysql_close( $this->mConn );
2038                         $this->mOpened = false;
2039                         $this->mConn = false;
2040                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
2041                         return true;
2042                 }
2043                 return false;
2044         }
2045
2046         /**
2047          * Get slave lag.
2048          * At the moment, this will only work if the DB user has the PROCESS privilege
2049          */
2050         function getLag() {
2051                 if ( !is_null( $this->mFakeSlaveLag ) ) {
2052                         wfDebug( "getLag: fake slave lagged {$this->mFakeSlaveLag} seconds\n" );
2053                         return $this->mFakeSlaveLag;
2054                 }
2055                 $res = $this->query( 'SHOW PROCESSLIST' );
2056                 # Find slave SQL thread
2057                 while ( $row = $this->fetchObject( $res ) ) {
2058                         /* This should work for most situations - when default db
2059                          * for thread is not specified, it had no events executed,
2060                          * and therefore it doesn't know yet how lagged it is.
2061                          *
2062                          * Relay log I/O thread does not select databases.
2063                          */
2064                         if ( $row->User == 'system user' &&
2065                                 $row->State != 'Waiting for master to send event' &&
2066                                 $row->State != 'Connecting to master' &&
2067                                 $row->State != 'Queueing master event to the relay log' &&
2068                                 $row->State != 'Waiting for master update' &&
2069                                 $row->State != 'Requesting binlog dump'
2070                                 ) {
2071                                 # This is it, return the time (except -ve)
2072                                 if ( $row->Time > 0x7fffffff ) {
2073                                         return false;
2074                                 } else {
2075                                         return $row->Time;
2076                                 }
2077                         }
2078                 }
2079                 return false;
2080         }
2081
2082         /**
2083          * Get status information from SHOW STATUS in an associative array
2084          */
2085         function getStatus($which="%") {
2086                 $res = $this->query( "SHOW STATUS LIKE '{$which}'" );
2087                 $status = array();
2088                 while ( $row = $this->fetchObject( $res ) ) {
2089                         $status[$row->Variable_name] = $row->Value;
2090                 }
2091                 return $status;
2092         }
2093
2094         /**
2095          * Return the maximum number of items allowed in a list, or 0 for unlimited.
2096          */
2097         function maxListLen() {
2098                 return 0;
2099         }
2100
2101         function encodeBlob($b) {
2102                 return $b;
2103         }
2104
2105         function decodeBlob($b) {
2106                 return $b;
2107         }
2108
2109         /**
2110          * Override database's default connection timeout.
2111          * May be useful for very long batch queries such as
2112          * full-wiki dumps, where a single query reads out
2113          * over hours or days.
2114          * @param int $timeout in seconds
2115          */
2116         public function setTimeout( $timeout ) {
2117                 $this->query( "SET net_read_timeout=$timeout" );
2118                 $this->query( "SET net_write_timeout=$timeout" );
2119         }
2120
2121         /**
2122          * Read and execute SQL commands from a file.
2123          * Returns true on success, error string or exception on failure (depending on object's error ignore settings)
2124          * @param string $filename File name to open
2125          * @param callback $lineCallback Optional function called before reading each line
2126          * @param callback $resultCallback Optional function called for each MySQL result
2127          */
2128         function sourceFile( $filename, $lineCallback = false, $resultCallback = false ) {
2129                 $fp = fopen( $filename, 'r' );
2130                 if ( false === $fp ) {
2131                         throw new MWException( "Could not open \"{$filename}\".\n" );
2132                 }
2133                 $error = $this->sourceStream( $fp, $lineCallback, $resultCallback );
2134                 fclose( $fp );
2135                 return $error;
2136         }
2137
2138         /**
2139          * Read and execute commands from an open file handle
2140          * Returns true on success, error string or exception on failure (depending on object's error ignore settings)
2141          * @param string $fp File handle
2142          * @param callback $lineCallback Optional function called before reading each line
2143          * @param callback $resultCallback Optional function called for each MySQL result
2144          */
2145         function sourceStream( $fp, $lineCallback = false, $resultCallback = false ) {
2146                 $cmd = "";
2147                 $done = false;
2148                 $dollarquote = false;
2149
2150                 while ( ! feof( $fp ) ) {
2151                         if ( $lineCallback ) {
2152                                 call_user_func( $lineCallback );
2153                         }
2154                         $line = trim( fgets( $fp, 1024 ) );
2155                         $sl = strlen( $line ) - 1;
2156
2157                         if ( $sl < 0 ) { continue; }
2158                         if ( '-' == $line{0} && '-' == $line{1} ) { continue; }
2159
2160                         ## Allow dollar quoting for function declarations
2161                         if (substr($line,0,4) == '$mw$') {
2162                                 if ($dollarquote) {
2163                                         $dollarquote = false;
2164                                         $done = true;
2165                                 }
2166                                 else {
2167                                         $dollarquote = true;
2168                                 }
2169                         }
2170                         else if (!$dollarquote) {
2171                                 if ( ';' == $line{$sl} && ($sl < 2 || ';' != $line{$sl - 1})) {
2172                                         $done = true;
2173                                         $line = substr( $line, 0, $sl );
2174                                 }
2175                         }
2176
2177                         if ( '' != $cmd ) { $cmd .= ' '; }
2178                         $cmd .= "$line\n";
2179
2180                         if ( $done ) {
2181                                 $cmd = str_replace(';;', ";", $cmd);
2182                                 $cmd = $this->replaceVars( $cmd );
2183                                 $res = $this->query( $cmd, __METHOD__ );
2184                                 if ( $resultCallback ) {
2185                                         call_user_func( $resultCallback, $res, $this );
2186                                 }
2187
2188                                 if ( false === $res ) {
2189                                         $err = $this->lastError();
2190                                         return "Query \"{$cmd}\" failed with error code \"$err\".\n";
2191                                 }
2192
2193                                 $cmd = '';
2194                                 $done = false;
2195                         }
2196                 }
2197                 return true;
2198         }
2199
2200
2201         /**
2202          * Replace variables in sourced SQL
2203          */
2204         protected function replaceVars( $ins ) {
2205                 $varnames = array(
2206                         'wgDBserver', 'wgDBname', 'wgDBintlname', 'wgDBuser',
2207                         'wgDBpassword', 'wgDBsqluser', 'wgDBsqlpassword',
2208                         'wgDBadminuser', 'wgDBadminpassword', 'wgDBTableOptions',
2209                 );
2210
2211                 // Ordinary variables
2212                 foreach ( $varnames as $var ) {
2213                         if( isset( $GLOBALS[$var] ) ) {
2214                                 $val = addslashes( $GLOBALS[$var] ); // FIXME: safety check?
2215                                 $ins = str_replace( '{$' . $var . '}', $val, $ins );
2216                                 $ins = str_replace( '/*$' . $var . '*/`', '`' . $val, $ins );
2217                                 $ins = str_replace( '/*$' . $var . '*/', $val, $ins );
2218                         }
2219                 }
2220
2221                 // Table prefixes
2222                 $ins = preg_replace_callback( '/\/\*(?:\$wgDBprefix|_)\*\/([a-zA-Z_0-9]*)/',
2223                         array( &$this, 'tableNameCallback' ), $ins );
2224                 return $ins;
2225         }
2226
2227         /**
2228          * Table name callback
2229          * @private
2230          */
2231         protected function tableNameCallback( $matches ) {
2232                 return $this->tableName( $matches[1] );
2233         }
2234
2235         /*
2236          * Build a concatenation list to feed into a SQL query
2237         */
2238         function buildConcat( $stringList ) {
2239                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
2240         }
2241
2242         /**
2243          * Acquire a lock
2244          *
2245          * Abstracted from Filestore::lock() so child classes can implement for
2246          * their own needs.
2247          *
2248          * @param string $lockName Name of lock to aquire
2249          * @param string $method Name of method calling us
2250          * @return bool
2251          */
2252         public function lock( $lockName, $method ) {
2253                 $lockName = $this->addQuotes( $lockName );
2254                 $result = $this->query( "SELECT GET_LOCK($lockName, 5) AS lockstatus", $method );
2255                 $row = $this->fetchObject( $result );
2256                 $this->freeResult( $result );
2257
2258                 if( $row->lockstatus == 1 ) {
2259                         return true;
2260                 } else {
2261                         wfDebug( __METHOD__." failed to acquire lock\n" );
2262                         return false;
2263                 }
2264         }
2265         /**
2266          * Release a lock.
2267          *
2268          * @todo fixme - Figure out a way to return a bool
2269          * based on successful lock release.
2270          *
2271          * @param string $lockName Name of lock to release
2272          * @param string $method Name of method calling us
2273          */
2274         public function unlock( $lockName, $method ) {
2275                 $lockName = $this->addQuotes( $lockName );
2276                 $result = $this->query( "SELECT RELEASE_LOCK($lockName)", $method );
2277                 $this->freeResult( $result );
2278         }
2279
2280         /**
2281          * Get search engine class. All subclasses of this
2282          * need to implement this if they wish to use searching.
2283          *
2284          * @return string
2285          */
2286         public function getSearchEngine() {
2287                 return "SearchMySQL";
2288         }
2289 }
2290
2291 /**
2292  * Database abstraction object for mySQL
2293  * Inherit all methods and properties of Database::Database()
2294  *
2295  * @ingroup Database
2296  * @see Database
2297  */
2298 class DatabaseMysql extends Database {
2299         # Inherit all
2300 }
2301
2302 /******************************************************************************
2303  * Utility classes
2304  *****************************************************************************/
2305
2306 /**
2307  * Utility class.
2308  * @ingroup Database
2309  */
2310 class DBObject {
2311         public $mData;
2312
2313         function DBObject($data) {
2314                 $this->mData = $data;
2315         }
2316
2317         function isLOB() {
2318                 return false;
2319         }
2320
2321         function data() {
2322                 return $this->mData;
2323         }
2324 }
2325
2326 /**
2327  * Utility class
2328  * @ingroup Database
2329  *
2330  * This allows us to distinguish a blob from a normal string and an array of strings
2331  */
2332 class Blob {
2333         private $mData;
2334         function __construct($data) {
2335                 $this->mData = $data;
2336         }
2337         function fetch() {
2338                 return $this->mData;
2339         }
2340 }
2341
2342 /**
2343  * Utility class.
2344  * @ingroup Database
2345  */
2346 class MySQLField {
2347         private $name, $tablename, $default, $max_length, $nullable,
2348                 $is_pk, $is_unique, $is_multiple, $is_key, $type;
2349         function __construct ($info) {
2350                 $this->name = $info->name;
2351                 $this->tablename = $info->table;
2352                 $this->default = $info->def;
2353                 $this->max_length = $info->max_length;
2354                 $this->nullable = !$info->not_null;
2355                 $this->is_pk = $info->primary_key;
2356                 $this->is_unique = $info->unique_key;
2357                 $this->is_multiple = $info->multiple_key;
2358                 $this->is_key = ($this->is_pk || $this->is_unique || $this->is_multiple);
2359                 $this->type = $info->type;
2360         }
2361
2362         function name() {
2363                 return $this->name;
2364         }
2365
2366         function tableName() {
2367                 return $this->tableName;
2368         }
2369
2370         function defaultValue() {
2371                 return $this->default;
2372         }
2373
2374         function maxLength() {
2375                 return $this->max_length;
2376         }
2377
2378         function nullable() {
2379                 return $this->nullable;
2380         }
2381
2382         function isKey() {
2383                 return $this->is_key;
2384         }
2385
2386         function isMultipleKey() {
2387                 return $this->is_multiple;
2388         }
2389
2390         function type() {
2391                 return $this->type;
2392         }
2393 }
2394
2395 /******************************************************************************
2396  * Error classes
2397  *****************************************************************************/
2398
2399 /**
2400  * Database error base class
2401  * @ingroup Database
2402  */
2403 class DBError extends MWException {
2404         public $db;
2405
2406         /**
2407          * Construct a database error
2408          * @param Database $db The database object which threw the error
2409          * @param string $error A simple error message to be used for debugging
2410          */
2411         function __construct( Database &$db, $error ) {
2412                 $this->db =& $db;
2413                 parent::__construct( $error );
2414         }
2415 }
2416
2417 /**
2418  * @ingroup Database
2419  */
2420 class DBConnectionError extends DBError {
2421         public $error;
2422
2423         function __construct( Database &$db, $error = 'unknown error' ) {
2424                 $msg = 'DB connection error';
2425                 if ( trim( $error ) != '' ) {
2426                         $msg .= ": $error";
2427                 }
2428                 $this->error = $error;
2429                 parent::__construct( $db, $msg );
2430         }
2431
2432         function useOutputPage() {
2433                 // Not likely to work
2434                 return false;
2435         }
2436
2437         function useMessageCache() {
2438                 // Not likely to work
2439                 return false;
2440         }
2441
2442         function getText() {
2443                 return $this->getMessage() . "\n";
2444         }
2445
2446         function getLogMessage() {
2447                 # Don't send to the exception log
2448                 return false;
2449         }
2450
2451         function getPageTitle() {
2452                 global $wgSitename;
2453                 return "$wgSitename has a problem";
2454         }
2455
2456         function getHTML() {
2457                 global $wgTitle, $wgUseFileCache, $title, $wgInputEncoding;
2458                 global $wgSitename, $wgServer, $wgMessageCache;
2459
2460                 # I give up, Brion is right. Getting the message cache to work when there is no DB is tricky.
2461                 # Hard coding strings instead.
2462
2463                 $noconnect = "<p><strong>Sorry! This site is experiencing technical difficulties.</strong></p><p>Try waiting a few minutes and reloading.</p><p><small>(Can't contact the database server: $1)</small></p>";
2464                 $mainpage = 'Main Page';
2465                 $searchdisabled = <<<EOT
2466 <p style="margin: 1.5em 2em 1em">$wgSitename search is disabled for performance reasons. You can search via Google in the meantime.
2467 <span style="font-size: 89%; display: block; margin-left: .2em">Note that their indexes of $wgSitename content may be out of date.</span></p>',
2468 EOT;
2469
2470                 $googlesearch = "
2471 <!-- SiteSearch Google -->
2472 <FORM method=GET action=\"http://www.google.com/search\">
2473 <TABLE bgcolor=\"#FFFFFF\"><tr><td>
2474 <A HREF=\"http://www.google.com/\">
2475 <IMG SRC=\"http://www.google.com/logos/Logo_40wht.gif\"
2476 border=\"0\" ALT=\"Google\"></A>
2477 </td>
2478 <td>
2479 <INPUT TYPE=text name=q size=31 maxlength=255 value=\"$1\">
2480 <INPUT type=submit name=btnG VALUE=\"Google Search\">
2481 <font size=-1>
2482 <input type=hidden name=domains value=\"$wgServer\"><br /><input type=radio name=sitesearch value=\"\"> WWW <input type=radio name=sitesearch value=\"$wgServer\" checked> $wgServer <br />
2483 <input type='hidden' name='ie' value='$2'>
2484 <input type='hidden' name='oe' value='$2'>
2485 </font>
2486 </td></tr></TABLE>
2487 </FORM>
2488 <!-- SiteSearch Google -->";
2489                 $cachederror = "The following is a cached copy of the requested page, and may not be up to date. ";
2490
2491                 # No database access
2492                 if ( is_object( $wgMessageCache ) ) {
2493                         $wgMessageCache->disable();
2494                 }
2495
2496                 if ( trim( $this->error ) == '' ) {
2497                         $this->error = $this->db->getProperty('mServer');
2498                 }
2499
2500                 $text = str_replace( '$1', $this->error, $noconnect );
2501                 $text .= wfGetSiteNotice();
2502
2503                 if($wgUseFileCache) {
2504                         if($wgTitle) {
2505                                 $t =& $wgTitle;
2506                         } else {
2507                                 if($title) {
2508                                         $t = Title::newFromURL( $title );
2509                                 } elseif (@/**/$_REQUEST['search']) {
2510                                         $search = $_REQUEST['search'];
2511                                         return $searchdisabled .
2512                                           str_replace( array( '$1', '$2' ), array( htmlspecialchars( $search ),
2513                                           $wgInputEncoding ), $googlesearch );
2514                                 } else {
2515                                         $t = Title::newFromText( $mainpage );
2516                                 }
2517                         }
2518
2519                         $cache = new HTMLFileCache( $t );
2520                         if( $cache->isFileCached() ) {
2521                                 // @todo, FIXME: $msg is not defined on the next line.
2522                                 $msg = '<p style="color: red"><b>'.$msg."<br />\n" .
2523                                         $cachederror . "</b></p>\n";
2524
2525                                 $tag = '<div id="article">';
2526                                 $text = str_replace(
2527                                         $tag,
2528                                         $tag . $msg,
2529                                         $cache->fetchPageText() );
2530                         }
2531                 }
2532
2533                 return $text;
2534         }
2535 }
2536
2537 /**
2538  * @ingroup Database
2539  */
2540 class DBQueryError extends DBError {
2541         public $error, $errno, $sql, $fname;
2542
2543         function __construct( Database &$db, $error, $errno, $sql, $fname ) {
2544                 $message = "A database error has occurred\n" .
2545                   "Query: $sql\n" .
2546                   "Function: $fname\n" .
2547                   "Error: $errno $error\n";
2548
2549                 parent::__construct( $db, $message );
2550                 $this->error = $error;
2551                 $this->errno = $errno;
2552                 $this->sql = $sql;
2553                 $this->fname = $fname;
2554         }
2555
2556         function getText() {
2557                 if ( $this->useMessageCache() ) {
2558                         return wfMsg( 'dberrortextcl', htmlspecialchars( $this->getSQL() ),
2559                           htmlspecialchars( $this->fname ), $this->errno, htmlspecialchars( $this->error ) ) . "\n";
2560                 } else {
2561                         return $this->getMessage();
2562                 }
2563         }
2564
2565         function getSQL() {
2566                 global $wgShowSQLErrors;
2567                 if( !$wgShowSQLErrors ) {
2568                         return $this->msg( 'sqlhidden', 'SQL hidden' );
2569                 } else {
2570                         return $this->sql;
2571                 }
2572         }
2573
2574         function getLogMessage() {
2575                 # Don't send to the exception log
2576                 return false;
2577         }
2578
2579         function getPageTitle() {
2580                 return $this->msg( 'databaseerror', 'Database error' );
2581         }
2582
2583         function getHTML() {
2584                 if ( $this->useMessageCache() ) {
2585                         return wfMsgNoDB( 'dberrortext', htmlspecialchars( $this->getSQL() ),
2586                           htmlspecialchars( $this->fname ), $this->errno, htmlspecialchars( $this->error ) );
2587                 } else {
2588                         return nl2br( htmlspecialchars( $this->getMessage() ) );
2589                 }
2590         }
2591 }
2592
2593 /**
2594  * @ingroup Database
2595  */
2596 class DBUnexpectedError extends DBError {}
2597
2598
2599 /**
2600  * Result wrapper for grabbing data queried by someone else
2601  * @ingroup Database
2602  */
2603 class ResultWrapper implements Iterator {
2604         var $db, $result, $pos = 0, $currentRow = null;
2605
2606         /**
2607          * Create a new result object from a result resource and a Database object
2608          */
2609         function ResultWrapper( $database, $result ) {
2610                 $this->db = $database;
2611                 if ( $result instanceof ResultWrapper ) {
2612                         $this->result = $result->result;
2613                 } else {
2614                         $this->result = $result;
2615                 }
2616         }
2617
2618         /**
2619          * Get the number of rows in a result object
2620          */
2621         function numRows() {
2622                 return $this->db->numRows( $this->result );
2623         }
2624
2625         /**
2626          * Fetch the next row from the given result object, in object form.
2627          * Fields can be retrieved with $row->fieldname, with fields acting like
2628          * member variables.
2629          *
2630          * @param $res SQL result object as returned from Database::query(), etc.
2631          * @return MySQL row object
2632          * @throws DBUnexpectedError Thrown if the database returns an error
2633          */
2634         function fetchObject() {
2635                 return $this->db->fetchObject( $this->result );
2636         }
2637
2638         /**
2639          * Fetch the next row from the given result object, in associative array
2640          * form.  Fields are retrieved with $row['fieldname'].
2641          *
2642          * @param $res SQL result object as returned from Database::query(), etc.
2643          * @return MySQL row object
2644          * @throws DBUnexpectedError Thrown if the database returns an error
2645          */
2646         function fetchRow() {
2647                 return $this->db->fetchRow( $this->result );
2648         }
2649
2650         /**
2651          * Free a result object
2652          */
2653         function free() {
2654                 $this->db->freeResult( $this->result );
2655                 unset( $this->result );
2656                 unset( $this->db );
2657         }
2658
2659         /**
2660          * Change the position of the cursor in a result object
2661          * See mysql_data_seek()
2662          */
2663         function seek( $row ) {
2664                 $this->db->dataSeek( $this->result, $row );
2665         }
2666
2667         /*********************
2668          * Iterator functions
2669          * Note that using these in combination with the non-iterator functions
2670          * above may cause rows to be skipped or repeated.
2671          */
2672
2673         function rewind() {
2674                 if ($this->numRows()) {
2675                         $this->db->dataSeek($this->result, 0);
2676                 }
2677                 $this->pos = 0;
2678                 $this->currentRow = null;
2679         }
2680
2681         function current() {
2682                 if ( is_null( $this->currentRow ) ) {
2683                         $this->next();
2684                 }
2685                 return $this->currentRow;
2686         }
2687
2688         function key() {
2689                 return $this->pos;
2690         }
2691
2692         function next() {
2693                 $this->pos++;
2694                 $this->currentRow = $this->fetchObject();
2695                 return $this->currentRow;
2696         }
2697
2698         function valid() {
2699                 return $this->current() !== false;
2700         }
2701 }
2702
2703 class MySQLMasterPos {
2704         var $file, $pos;
2705
2706         function __construct( $file, $pos ) {
2707                 $this->file = $file;
2708                 $this->pos = $pos;
2709         }
2710
2711         function __toString() {
2712                 return "{$this->file}/{$this->pos}";
2713         }
2714 }