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 = $this->restoreErrorHandler();
 368                 if ( !$this->mConn ) {
 369                         $error = $this->lastError();
 370                         if ( !$error ) {
 371                                 $error = $phpError;
 372                         }
 373                         wfLogDBError( "Error connecting to {$this->mServer}: $error\n" );
 374                 }
 375
 376                 wfProfileOut("dbconnect-$server");
 377
 378                 if ( $dbName != '' ) {
 379                         if ( $this->mConn !== false ) {
 380                                 $success = @/**/mysql_select_db( $dbName, $this->mConn );
 381                                 if ( !$success ) {
 382                                         $error = "Error selecting database $dbName on server {$this->mServer} " .
 383                                                 "from client host {$wguname['nodename']}\n";
 384                                         wfLogDBError(" Error selecting database $dbName on server {$this->mServer} \n");
 385                                         wfDebug( $error );
 386                                 }
 387                         } else {
 388                                 wfDebug( "DB connection error\n" );
 389                                 wfDebug( "Server: $server, User: $user, Password: " .
 390                                         substr( $password, 0, 3 ) . "..., error: " . mysql_error() . "\n" );
 391                                 $success = false;
 392                         }
 393                 } else {
 394                         # Delay USE query
 395                         $success = (bool)$this->mConn;
 396                 }
 397
 398                 if ( $success ) {
 399                         $version = $this->getServerVersion();
 400                         if ( version_compare( $version, '4.1' ) >= 0 ) {
 401                                 // Tell the server we're communicating with it in UTF-8.
 402                                 // This may engage various charset conversions.
 403                                 global $wgDBmysql5;
 404                                 if( $wgDBmysql5 ) {
 405                                         $this->query( 'SET NAMES utf8', __METHOD__ );
 406                                 }
 407                                 // Turn off strict mode
 408                                 $this->query( "SET sql_mode = ''", __METHOD__ );
 409                         }
 410
 411                         // Turn off strict mode if it is on
 412                 } else {
 413                         $this->reportConnectionError( $phpError );
 414                 }
 415
 416                 $this->mOpened = $success;
 417                 wfProfileOut( __METHOD__ );
 418                 return $success;
 419         }
 420         /**@}}*/
 421
 422         protected function installErrorHandler() {
 423                 $this->mPHPError = false;
 424                 set_error_handler( array( $this, 'connectionErrorHandler' ) );
 425         }
 426
 427         protected function restoreErrorHandler() {
 428                 restore_error_handler();
 429                 return $this->mPHPError;
 430         }
 431
 432         protected function connectionErrorHandler( $errno,  $errstr ) {
 433                 $this->mPHPError = $errstr;
 434         }
 435
 436         /**
 437          * Closes a database connection.
 438          * if it is open : commits any open transactions
 439          *
 440          * @return bool operation success. true if already closed.
 441          */
 442         function close()
 443         {
 444                 $this->mOpened = false;
 445                 if ( $this->mConn ) {
 446                         if ( $this->trxLevel() ) {
 447                                 $this->immediateCommit();
 448                         }
 449                         return mysql_close( $this->mConn );
 450                 } else {
 451                         return true;
 452                 }
 453         }
 454
 455         /**
 456          * @param string $error fallback error message, used if none is given by MySQL
 457          */
 458         function reportConnectionError( $error = 'Unknown error' ) {
 459                 $myError = $this->lastError();
 460                 if ( $myError ) {
 461                         $error = $myError;
 462                 }
 463
 464                 if ( $this->mFailFunction ) {
 465                         # Legacy error handling method
 466                         if ( !is_int( $this->mFailFunction ) ) {
 467                                 $ff = $this->mFailFunction;
 468                                 $ff( $this, $error );
 469                         }
 470                 } else {
 471                         # New method
 472                         throw new DBConnectionError( $this, $error );
 473                 }
 474         }
 475
 476         /**
 477          * Usually aborts on failure.  If errors are explicitly ignored, returns success.
 478          *
 479          * @param  $sql        String: SQL query
 480          * @param  $fname      String: Name of the calling function, for profiling/SHOW PROCESSLIST
 481          *     comment (you can use __METHOD__ or add some extra info)
 482          * @param  $tempIgnore Bool:   Whether to avoid throwing an exception on errors...
 483          *     maybe best to catch the exception instead?
 484          * @return true for a successful write query, ResultWrapper object for a successful read query,
 485          *     or false on failure if $tempIgnore set
 486          * @throws DBQueryError Thrown when the database returns an error of any kind
 487          */
 488         public function query( $sql, $fname = '', $tempIgnore = false ) {
 489                 global $wgProfiler;
 490
 491                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 492                 if ( isset( $wgProfiler ) ) {
 493                         # generalizeSQL will probably cut down the query to reasonable
 494                         # logging size most of the time. The substr is really just a sanity check.
 495
 496                         # Who's been wasting my precious column space? -- TS
 497                         #$profName = 'query: ' . $fname . ' ' . substr( Database::generalizeSQL( $sql ), 0, 255 );
 498
 499                         if ( $isMaster ) {
 500                                 $queryProf = 'query-m: ' . substr( Database::generalizeSQL( $sql ), 0, 255 );
 501                                 $totalProf = 'Database::query-master';
 502                         } else {
 503                                 $queryProf = 'query: ' . substr( Database::generalizeSQL( $sql ), 0, 255 );
 504                                 $totalProf = 'Database::query';
 505                         }
 506                         wfProfileIn( $totalProf );
 507                         wfProfileIn( $queryProf );
 508                 }
 509
 510                 $this->mLastQuery = $sql;
 511
 512                 # Add a comment for easy SHOW PROCESSLIST interpretation
 513                 #if ( $fname ) {
 514                         global $wgUser;
 515                         if ( is_object( $wgUser ) && !($wgUser instanceof StubObject) ) {
 516                                 $userName = $wgUser->getName();
 517                                 if ( mb_strlen( $userName ) > 15 ) {
 518                                         $userName = mb_substr( $userName, 0, 15 ) . '...';
 519                                 }
 520                                 $userName = str_replace( '/', '', $userName );
 521                         } else {
 522                                 $userName = '';
 523                         }
 524                         $commentedSql = preg_replace('/\s/', " /* $fname $userName */ ", $sql, 1);
 525                 #} else {
 526                 #       $commentedSql = $sql;
 527                 #}
 528
 529                 # If DBO_TRX is set, start a transaction
 530                 if ( ( $this->mFlags & DBO_TRX ) && !$this->trxLevel() &&
 531                         $sql != 'BEGIN' && $sql != 'COMMIT' && $sql != 'ROLLBACK') {
 532                         // avoid establishing transactions for SHOW and SET statements too -
 533                         // that would delay transaction initializations to once connection
 534                         // is really used by application
 535                         $sqlstart = substr($sql,0,10); // very much worth it, benchmark certified(tm)
 536                         if (strpos($sqlstart,"SHOW ")!==0 and strpos($sqlstart,"SET ")!==0)
 537                                 $this->begin();
 538                 }
 539
 540                 if ( $this->debug() ) {
 541                         $sqlx = substr( $commentedSql, 0, 500 );
 542                         $sqlx = strtr( $sqlx, "\t\n", '  ' );
 543                         if ( $isMaster ) {
 544                                 wfDebug( "SQL-master: $sqlx\n" );
 545                         } else {
 546                                 wfDebug( "SQL: $sqlx\n" );
 547                         }
 548                 }
 549
 550                 # Do the query and handle errors
 551                 $ret = $this->doQuery( $commentedSql );
 552
 553                 # Try reconnecting if the connection was lost
 554                 if ( false === $ret && ( $this->lastErrno() == 2013 || $this->lastErrno() == 2006 ) ) {
 555                         # Transaction is gone, like it or not
 556                         $this->mTrxLevel = 0;
 557                         wfDebug( "Connection lost, reconnecting...\n" );
 558                         if ( $this->ping() ) {
 559                                 wfDebug( "Reconnected\n" );
 560                                 $sqlx = substr( $commentedSql, 0, 500 );
 561                                 $sqlx = strtr( $sqlx, "\t\n", '  ' );
 562                                 global $wgRequestTime;
 563                                 $elapsed = round( microtime(true) - $wgRequestTime, 3 );
 564                                 wfLogDBError( "Connection lost and reconnected after {$elapsed}s, query: $sqlx\n" );
 565                                 $ret = $this->doQuery( $commentedSql );
 566                         } else {
 567                                 wfDebug( "Failed\n" );
 568                         }
 569                 }
 570
 571                 if ( false === $ret ) {
 572                         $this->reportQueryError( $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 573                 }
 574
 575                 if ( isset( $wgProfiler ) ) {
 576                         wfProfileOut( $queryProf );
 577                         wfProfileOut( $totalProf );
 578                 }
 579                 return $this->resultObject( $ret );
 580         }
 581
 582         /**
 583          * The DBMS-dependent part of query()
 584          * @param  $sql String: SQL query.
 585          * @return Result object to feed to fetchObject, fetchRow, ...; or false on failure
 586          * @access private
 587          */
 588         /*private*/ function doQuery( $sql ) {
 589                 if( $this->bufferResults() ) {
 590                         $ret = mysql_query( $sql, $this->mConn );
 591                 } else {
 592                         $ret = mysql_unbuffered_query( $sql, $this->mConn );
 593                 }
 594                 return $ret;
 595         }
 596
 597         /**
 598          * @param $error
 599          * @param $errno
 600          * @param $sql
 601          * @param string $fname
 602          * @param bool $tempIgnore
 603          */
 604         function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 605                 global $wgCommandLineMode;
 606                 # Ignore errors during error handling to avoid infinite recursion
 607                 $ignore = $this->ignoreErrors( true );
 608                 ++$this->mErrorCount;
 609
 610                 if( $ignore || $tempIgnore ) {
 611                         wfDebug("SQL ERROR (ignored): $error\n");
 612                         $this->ignoreErrors( $ignore );
 613                 } else {
 614                         $sql1line = str_replace( "\n", "\\n", $sql );
 615                         wfLogDBError("$fname\t{$this->mServer}\t$errno\t$error\t$sql1line\n");
 616                         wfDebug("SQL ERROR: " . $error . "\n");
 617                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
 618                 }
 619         }
 620
 621
 622         /**
 623          * Intended to be compatible with the PEAR::DB wrapper functions.
 624          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
 625          *
 626          * ? = scalar value, quoted as necessary
 627          * ! = raw SQL bit (a function for instance)
 628          * & = filename; reads the file and inserts as a blob
 629          *     (we don't use this though...)
 630          */
 631         function prepare( $sql, $func = 'Database::prepare' ) {
 632                 /* MySQL doesn't support prepared statements (yet), so just
 633                    pack up the query for reference. We'll manually replace
 634                    the bits later. */
 635                 return array( 'query' => $sql, 'func' => $func );
 636         }
 637
 638         function freePrepared( $prepared ) {
 639                 /* No-op for MySQL */
 640         }
 641
 642         /**
 643          * Execute a prepared query with the various arguments
 644          * @param string $prepared the prepared sql
 645          * @param mixed $args Either an array here, or put scalars as varargs
 646          */
 647         function execute( $prepared, $args = null ) {
 648                 if( !is_array( $args ) ) {
 649                         # Pull the var args
 650                         $args = func_get_args();
 651                         array_shift( $args );
 652                 }
 653                 $sql = $this->fillPrepared( $prepared['query'], $args );
 654                 return $this->query( $sql, $prepared['func'] );
 655         }
 656
 657         /**
 658          * Prepare & execute an SQL statement, quoting and inserting arguments
 659          * in the appropriate places.
 660          * @param string $query
 661          * @param string $args ...
 662          */
 663         function safeQuery( $query, $args = null ) {
 664                 $prepared = $this->prepare( $query, 'Database::safeQuery' );
 665                 if( !is_array( $args ) ) {
 666                         # Pull the var args
 667                         $args = func_get_args();
 668                         array_shift( $args );
 669                 }
 670                 $retval = $this->execute( $prepared, $args );
 671                 $this->freePrepared( $prepared );
 672                 return $retval;
 673         }
 674
 675         /**
 676          * For faking prepared SQL statements on DBs that don't support
 677          * it directly.
 678          * @param string $preparedSql - a 'preparable' SQL statement
 679          * @param array $args - array of arguments to fill it with
 680          * @return string executable SQL
 681          */
 682         function fillPrepared( $preparedQuery, $args ) {
 683                 reset( $args );
 684                 $this->preparedArgs =& $args;
 685                 return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
 686                         array( &$this, 'fillPreparedArg' ), $preparedQuery );
 687         }
 688
 689         /**
 690          * preg_callback func for fillPrepared()
 691          * The arguments should be in $this->preparedArgs and must not be touched
 692          * while we're doing this.
 693          *
 694          * @param array $matches
 695          * @return string
 696          * @private
 697          */
 698         function fillPreparedArg( $matches ) {
 699                 switch( $matches[1] ) {
 700                         case '\\?': return '?';
 701                         case '\\!': return '!';
 702                         case '\\&': return '&';
 703                 }
 704                 list( /* $n */ , $arg ) = each( $this->preparedArgs );
 705                 switch( $matches[1] ) {
 706                         case '?': return $this->addQuotes( $arg );
 707                         case '!': return $arg;
 708                         case '&':
 709                                 # return $this->addQuotes( file_get_contents( $arg ) );
 710                                 throw new DBUnexpectedError( $this, '& mode is not implemented. If it\'s really needed, uncomment the line above.' );
 711                         default:
 712                                 throw new DBUnexpectedError( $this, 'Received invalid match. This should never happen!' );
 713                 }
 714         }
 715
 716         /**#@+
 717          * @param mixed $res A SQL result
 718          */
 719         /**
 720          * Free a result object
 721          */
 722         function freeResult( $res ) {
 723                 if ( $res instanceof ResultWrapper ) {
 724                         $res = $res->result;
 725                 }
 726                 if ( !@/**/mysql_free_result( $res ) ) {
 727                         throw new DBUnexpectedError( $this, "Unable to free MySQL result" );
 728                 }
 729         }
 730
 731         /**
 732          * Fetch the next row from the given result object, in object form.
 733          * Fields can be retrieved with $row->fieldname, with fields acting like
 734          * member variables.
 735          *
 736          * @param $res SQL result object as returned from Database::query(), etc.
 737          * @return MySQL row object
 738          * @throws DBUnexpectedError Thrown if the database returns an error
 739          */
 740         function fetchObject( $res ) {
 741                 if ( $res instanceof ResultWrapper ) {
 742                         $res = $res->result;
 743                 }
 744                 @/**/$row = mysql_fetch_object( $res );
 745                 if( $this->lastErrno() ) {
 746                         throw new DBUnexpectedError( $this, 'Error in fetchObject(): ' . htmlspecialchars( $this->lastError() ) );
 747                 }
 748                 return $row;
 749         }
 750
 751         /**
 752          * Fetch the next row from the given result object, in associative array
 753          * form.  Fields are retrieved with $row['fieldname'].
 754          *
 755          * @param $res SQL result object as returned from Database::query(), etc.
 756          * @return MySQL row object
 757          * @throws DBUnexpectedError Thrown if the database returns an error
 758          */
 759         function fetchRow( $res ) {
 760                 if ( $res instanceof ResultWrapper ) {
 761                         $res = $res->result;
 762                 }
 763                 @/**/$row = mysql_fetch_array( $res );
 764                 if ( $this->lastErrno() ) {
 765                         throw new DBUnexpectedError( $this, 'Error in fetchRow(): ' . htmlspecialchars( $this->lastError() ) );
 766                 }
 767                 return $row;
 768         }
 769
 770         /**
 771          * Get the number of rows in a result object
 772          */
 773         function numRows( $res ) {
 774                 if ( $res instanceof ResultWrapper ) {
 775                         $res = $res->result;
 776                 }
 777                 @/**/$n = mysql_num_rows( $res );
 778                 if( $this->lastErrno() ) {
 779                         throw new DBUnexpectedError( $this, 'Error in numRows(): ' . htmlspecialchars( $this->lastError() ) );
 780                 }
 781                 return $n;
 782         }
 783
 784         /**
 785          * Get the number of fields in a result object
 786          * See documentation for mysql_num_fields()
 787          */
 788         function numFields( $res ) {
 789                 if ( $res instanceof ResultWrapper ) {
 790                         $res = $res->result;
 791                 }
 792                 return mysql_num_fields( $res );
 793         }
 794
 795         /**
 796          * Get a field name in a result object
 797          * See documentation for mysql_field_name():
 798          * http://www.php.net/mysql_field_name
 799          */
 800         function fieldName( $res, $n ) {
 801                 if ( $res instanceof ResultWrapper ) {
 802                         $res = $res->result;
 803                 }
 804                 return mysql_field_name( $res, $n );
 805         }
 806
 807         /**
 808          * Get the inserted value of an auto-increment row
 809          *
 810          * The value inserted should be fetched from nextSequenceValue()
 811          *
 812          * Example:
 813          * $id = $dbw->nextSequenceValue('page_page_id_seq');
 814          * $dbw->insert('page',array('page_id' => $id));
 815          * $id = $dbw->insertId();
 816          */
 817         function insertId() { return mysql_insert_id( $this->mConn ); }
 818
 819         /**
 820          * Change the position of the cursor in a result object
 821          * See mysql_data_seek()
 822          */
 823         function dataSeek( $res, $row ) {
 824                 if ( $res instanceof ResultWrapper ) {
 825                         $res = $res->result;
 826                 }
 827                 return mysql_data_seek( $res, $row );
 828         }
 829
 830         /**
 831          * Get the last error number
 832          * See mysql_errno()
 833          */
 834         function lastErrno() {
 835                 if ( $this->mConn ) {
 836                         return mysql_errno( $this->mConn );
 837                 } else {
 838                         return mysql_errno();
 839                 }
 840         }
 841
 842         /**
 843          * Get a description of the last error
 844          * See mysql_error() for more details
 845          */
 846         function lastError() {
 847                 if ( $this->mConn ) {
 848                         # Even if it's non-zero, it can still be invalid
 849                         wfSuppressWarnings();
 850                         $error = mysql_error( $this->mConn );
 851                         if ( !$error ) {
 852                                 $error = mysql_error();
 853                         }
 854                         wfRestoreWarnings();
 855                 } else {
 856                         $error = mysql_error();
 857                 }
 858                 if( $error ) {
 859                         $error .= ' (' . $this->mServer . ')';
 860                 }
 861                 return $error;
 862         }
 863         /**
 864          * Get the number of rows affected by the last write query
 865          * See mysql_affected_rows() for more details
 866          */
 867         function affectedRows() { return mysql_affected_rows( $this->mConn ); }
 868         /**#@-*/ // end of template : @param $result
 869
 870         /**
 871          * Simple UPDATE wrapper
 872          * Usually aborts on failure
 873          * If errors are explicitly ignored, returns success
 874          *
 875          * This function exists for historical reasons, Database::update() has a more standard
 876          * calling convention and feature set
 877          */
 878         function set( $table, $var, $value, $cond, $fname = 'Database::set' )
 879         {
 880                 $table = $this->tableName( $table );
 881                 $sql = "UPDATE $table SET $var = '" .
 882                   $this->strencode( $value ) . "' WHERE ($cond)";
 883                 return (bool)$this->query( $sql, $fname );
 884         }
 885
 886         /**
 887          * Simple SELECT wrapper, returns a single field, input must be encoded
 888          * Usually aborts on failure
 889          * If errors are explicitly ignored, returns FALSE on failure
 890          */
 891         function selectField( $table, $var, $cond='', $fname = 'Database::selectField', $options = array() ) {
 892                 if ( !is_array( $options ) ) {
 893                         $options = array( $options );
 894                 }
 895                 $options['LIMIT'] = 1;
 896
 897                 $res = $this->select( $table, $var, $cond, $fname, $options );
 898                 if ( $res === false || !$this->numRows( $res ) ) {
 899                         return false;
 900                 }
 901                 $row = $this->fetchRow( $res );
 902                 if ( $row !== false ) {
 903                         $this->freeResult( $res );
 904                         return $row[0];
 905                 } else {
 906                         return false;
 907                 }
 908         }
 909
 910         /**
 911          * Returns an optional USE INDEX clause to go after the table, and a
 912          * string to go at the end of the query
 913          *
 914          * @private
 915          *
 916          * @param array $options an associative array of options to be turned into
 917          *              an SQL query, valid keys are listed in the function.
 918          * @return array
 919          */
 920         function makeSelectOptions( $options ) {
 921                 $preLimitTail = $postLimitTail = '';
 922                 $startOpts = '';
 923
 924                 $noKeyOptions = array();
 925                 foreach ( $options as $key => $option ) {
 926                         if ( is_numeric( $key ) ) {
 927                                 $noKeyOptions[$option] = true;
 928                         }
 929                 }
 930
 931                 if ( isset( $options['GROUP BY'] ) ) $preLimitTail .= " GROUP BY {$options['GROUP BY']}";
 932                 if ( isset( $options['HAVING'] ) ) $preLimitTail .= " HAVING {$options['HAVING']}";
 933                 if ( isset( $options['ORDER BY'] ) ) $preLimitTail .= " ORDER BY {$options['ORDER BY']}";
 934
 935                 //if (isset($options['LIMIT'])) {
 936                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
 937                 //              isset($options['OFFSET']) ? $options['OFFSET']
 938                 //              : false);
 939                 //}
 940
 941                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) $postLimitTail .= ' FOR UPDATE';
 942                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) $postLimitTail .= ' LOCK IN SHARE MODE';
 943                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) $startOpts .= 'DISTINCT';
 944
 945                 # Various MySQL extensions
 946                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) $startOpts .= ' /*! STRAIGHT_JOIN */';
 947                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) $startOpts .= ' HIGH_PRIORITY';
 948                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) $startOpts .= ' SQL_BIG_RESULT';
 949                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) $startOpts .= ' SQL_BUFFER_RESULT';
 950                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) $startOpts .= ' SQL_SMALL_RESULT';
 951                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) $startOpts .= ' SQL_CALC_FOUND_ROWS';
 952                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) $startOpts .= ' SQL_CACHE';
 953                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) $startOpts .= ' SQL_NO_CACHE';
 954
 955                 if ( isset( $options['USE INDEX'] ) && ! is_array( $options['USE INDEX'] ) ) {
 956                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
 957                 } else {
 958                         $useIndex = '';
 959                 }
 960
 961                 return array( $startOpts, $useIndex, $preLimitTail, $postLimitTail );
 962         }
 963
 964         /**
 965          * SELECT wrapper
 966          *
 967          * @param mixed  $table   Array or string, table name(s) (prefix auto-added)
 968          * @param mixed  $vars    Array or string, field name(s) to be retrieved
 969          * @param mixed  $conds   Array or string, condition(s) for WHERE
 970          * @param string $fname   Calling function name (use __METHOD__) for logs/profiling
 971          * @param array  $options Associative array of options (e.g. array('GROUP BY' => 'page_title')),
 972          *                        see Database::makeSelectOptions code for list of supported stuff
 973          * @param array $join_conds Associative array of table join conditions (optional)
 974          *                        (e.g. array( 'page' => array('LEFT JOIN','page_latest=rev_id') )
 975          * @return mixed Database result resource (feed to Database::fetchObject or whatever), or false on failure
 976          */
 977         function select( $table, $vars, $conds='', $fname = 'Database::select', $options = array(), $join_conds = array() )
 978         {
 979                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
 980                 return $this->query( $sql, $fname );
 981         }
 982
 983         /**
 984          * SELECT wrapper
 985          *
 986          * @param mixed  $table   Array or string, table name(s) (prefix auto-added)
 987          * @param mixed  $vars    Array or string, field name(s) to be retrieved
 988          * @param mixed  $conds   Array or string, condition(s) for WHERE
 989          * @param string $fname   Calling function name (use __METHOD__) for logs/profiling
 990          * @param array  $options Associative array of options (e.g. array('GROUP BY' => 'page_title')),
 991          *                        see Database::makeSelectOptions code for list of supported stuff
 992          * @param array $join_conds Associative array of table join conditions (optional)
 993          *                        (e.g. array( 'page' => array('LEFT JOIN','page_latest=rev_id') )
 994          * @return string, the SQL text
 995          */
 996         function selectSQLText( $table, $vars, $conds='', $fname = 'Database::select', $options = array(), $join_conds = array() ) {
 997                 if( is_array( $vars ) ) {
 998                         $vars = implode( ',', $vars );
 999                 }
1000                 if( !is_array( $options ) ) {
1001                         $options = array( $options );
1002                 }
1003                 if( is_array( $table ) ) {
1004                         if ( !empty($join_conds) || ( isset( $options['USE INDEX'] ) && is_array( @$options['USE INDEX'] ) ) )
1005                                 $from = ' FROM ' . $this->tableNamesWithUseIndexOrJOIN( $table, @$options['USE INDEX'], $join_conds );
1006                         else
1007                                 $from = ' FROM ' . implode( ',', array_map( array( &$this, 'tableName' ), $table ) );
1008                 } elseif ($table!='') {
1009                         if ($table{0}==' ') {
1010                                 $from = ' FROM ' . $table;
1011                         } else {
1012                                 $from = ' FROM ' . $this->tableName( $table );
1013                         }
1014                 } else {
1015                         $from = '';
1016                 }
1017
1018                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail ) = $this->makeSelectOptions( $options );
1019
1020                 if( !empty( $conds ) ) {
1021                         if ( is_array( $conds ) ) {
1022                                 $conds = $this->makeList( $conds, LIST_AND );
1023                         }
1024                         $sql = "SELECT $startOpts $vars $from $useIndex WHERE $conds $preLimitTail";
1025                 } else {
1026                         $sql = "SELECT $startOpts $vars $from $useIndex $preLimitTail";
1027                 }
1028
1029                 if (isset($options['LIMIT']))
1030                         $sql = $this->limitResult($sql, $options['LIMIT'],
1031                                 isset($options['OFFSET']) ? $options['OFFSET'] : false);
1032                 $sql = "$sql $postLimitTail";
1033
1034                 if (isset($options['EXPLAIN'])) {
1035                         $sql = 'EXPLAIN ' . $sql;
1036                 }
1037                 return $sql;
1038         }
1039
1040         /**
1041          * Single row SELECT wrapper
1042          * Aborts or returns FALSE on error
1043          *
1044          * $vars: the selected variables
1045          * $conds: a condition map, terms are ANDed together.
1046          *   Items with numeric keys are taken to be literal conditions
1047          * Takes an array of selected variables, and a condition map, which is ANDed
1048          * e.g: selectRow( "page", array( "page_id" ), array( "page_namespace" =>
1049          * NS_MAIN, "page_title" => "Astronomy" ) )   would return an object where
1050          * $obj- >page_id is the ID of the Astronomy article
1051          *
1052          * @todo migrate documentation to phpdocumentor format
1053          */
1054         function selectRow( $table, $vars, $conds, $fname = 'Database::selectRow', $options = array(), $join_conds = array() ) {
1055                 $options['LIMIT'] = 1;
1056                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1057                 if ( $res === false )
1058                         return false;
1059                 if ( !$this->numRows($res) ) {
1060                         $this->freeResult($res);
1061                         return false;
1062                 }
1063                 $obj = $this->fetchObject( $res );
1064                 $this->freeResult( $res );
1065                 return $obj;
1066
1067         }
1068
1069         /**
1070          * Estimate rows in dataset
1071          * Returns estimated count, based on EXPLAIN output
1072          * Takes same arguments as Database::select()
1073          */
1074
1075         function estimateRowCount( $table, $vars='*', $conds='', $fname = 'Database::estimateRowCount', $options = array() ) {
1076                 $options['EXPLAIN']=true;
1077                 $res = $this->select ($table, $vars, $conds, $fname, $options );
1078                 if ( $res === false )
1079                         return false;
1080                 if (!$this->numRows($res)) {
1081                         $this->freeResult($res);
1082                         return 0;
1083                 }
1084
1085                 $rows=1;
1086
1087                 while( $plan = $this->fetchObject( $res ) ) {
1088                         $rows *= ($plan->rows > 0)?$plan->rows:1; // avoid resetting to zero
1089                 }
1090
1091                 $this->freeResult($res);
1092                 return $rows;
1093         }
1094
1095
1096         /**
1097          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1098          * It's only slightly flawed. Don't use for anything important.
1099          *
1100          * @param string $sql A SQL Query
1101          * @static
1102          */
1103         static function generalizeSQL( $sql ) {
1104                 # This does the same as the regexp below would do, but in such a way
1105                 # as to avoid crashing php on some large strings.
1106                 # $sql = preg_replace ( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql);
1107
1108                 $sql = str_replace ( "\\\\", '', $sql);
1109                 $sql = str_replace ( "\\'", '', $sql);
1110                 $sql = str_replace ( "\\\"", '', $sql);
1111                 $sql = preg_replace ("/'.*'/s", "'X'", $sql);
1112                 $sql = preg_replace ('/".*"/s', "'X'", $sql);
1113
1114                 # All newlines, tabs, etc replaced by single space
1115                 $sql = preg_replace ( '/\s+/', ' ', $sql);
1116
1117                 # All numbers => N
1118                 $sql = preg_replace ('/-?[0-9]+/s', 'N', $sql);
1119
1120                 return $sql;
1121         }
1122
1123         /**
1124          * Determines whether a field exists in a table
1125          * Usually aborts on failure
1126          * If errors are explicitly ignored, returns NULL on failure
1127          */
1128         function fieldExists( $table, $field, $fname = 'Database::fieldExists' ) {
1129                 $table = $this->tableName( $table );
1130                 $res = $this->query( 'DESCRIBE '.$table, $fname );
1131                 if ( !$res ) {
1132                         return NULL;
1133                 }
1134
1135                 $found = false;
1136
1137                 while ( $row = $this->fetchObject( $res ) ) {
1138                         if ( $row->Field == $field ) {
1139                                 $found = true;
1140                                 break;
1141                         }
1142                 }
1143                 return $found;
1144         }
1145
1146         /**
1147          * Determines whether an index exists
1148          * Usually aborts on failure
1149          * If errors are explicitly ignored, returns NULL on failure
1150          */
1151         function indexExists( $table, $index, $fname = 'Database::indexExists' ) {
1152                 $info = $this->indexInfo( $table, $index, $fname );
1153                 if ( is_null( $info ) ) {
1154                         return NULL;
1155                 } else {
1156                         return $info !== false;
1157                 }
1158         }
1159
1160
1161         /**
1162          * Get information about an index into an object
1163          * Returns false if the index does not exist
1164          */
1165         function indexInfo( $table, $index, $fname = 'Database::indexInfo' ) {
1166                 # SHOW INDEX works in MySQL 3.23.58, but SHOW INDEXES does not.
1167                 # SHOW INDEX should work for 3.x and up:
1168                 # http://dev.mysql.com/doc/mysql/en/SHOW_INDEX.html
1169                 $table = $this->tableName( $table );
1170                 $sql = 'SHOW INDEX FROM '.$table;
1171                 $res = $this->query( $sql, $fname );
1172                 if ( !$res ) {
1173                         return NULL;
1174                 }
1175
1176                 $result = array();
1177                 while ( $row = $this->fetchObject( $res ) ) {
1178                         if ( $row->Key_name == $index ) {
1179                                 $result[] = $row;
1180                         }
1181                 }
1182                 $this->freeResult($res);
1183
1184                 return empty($result) ? false : $result;
1185         }
1186
1187         /**
1188          * Query whether a given table exists
1189          */
1190         function tableExists( $table ) {
1191                 $table = $this->tableName( $table );
1192                 $old = $this->ignoreErrors( true );
1193                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1" );
1194                 $this->ignoreErrors( $old );
1195                 if( $res ) {
1196                         $this->freeResult( $res );
1197                         return true;
1198                 } else {
1199                         return false;
1200                 }
1201         }
1202
1203         /**
1204          * mysql_fetch_field() wrapper
1205          * Returns false if the field doesn't exist
1206          *
1207          * @param $table
1208          * @param $field
1209          */
1210         function fieldInfo( $table, $field ) {
1211                 $table = $this->tableName( $table );
1212                 $res = $this->query( "SELECT * FROM $table LIMIT 1" );
1213                 $n = mysql_num_fields( $res->result );
1214                 for( $i = 0; $i < $n; $i++ ) {
1215                         $meta = mysql_fetch_field( $res->result, $i );
1216                         if( $field == $meta->name ) {
1217                                 return new MySQLField($meta);
1218                         }
1219                 }
1220                 return false;
1221         }
1222
1223         /**
1224          * mysql_field_type() wrapper
1225          */
1226         function fieldType( $res, $index ) {
1227                 if ( $res instanceof ResultWrapper ) {
1228                         $res = $res->result;
1229                 }
1230                 return mysql_field_type( $res, $index );
1231         }
1232
1233         /**
1234          * Determines if a given index is unique
1235          */
1236         function indexUnique( $table, $index ) {
1237                 $indexInfo = $this->indexInfo( $table, $index );
1238                 if ( !$indexInfo ) {
1239                         return NULL;
1240                 }
1241                 return !$indexInfo[0]->Non_unique;
1242         }
1243
1244         /**
1245          * INSERT wrapper, inserts an array into a table
1246          *
1247          * $a may be a single associative array, or an array of these with numeric keys, for
1248          * multi-row insert.
1249          *
1250          * Usually aborts on failure
1251          * If errors are explicitly ignored, returns success
1252          */
1253         function insert( $table, $a, $fname = 'Database::insert', $options = array() ) {
1254                 # No rows to insert, easy just return now
1255                 if ( !count( $a ) ) {
1256                         return true;
1257                 }
1258
1259                 $table = $this->tableName( $table );
1260                 if ( !is_array( $options ) ) {
1261                         $options = array( $options );
1262                 }
1263                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1264                         $multi = true;
1265                         $keys = array_keys( $a[0] );
1266                 } else {
1267                         $multi = false;
1268                         $keys = array_keys( $a );
1269                 }
1270
1271                 $sql = 'INSERT ' . implode( ' ', $options ) .
1272                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1273
1274                 if ( $multi ) {
1275                         $first = true;
1276                         foreach ( $a as $row ) {
1277                                 if ( $first ) {
1278                                         $first = false;
1279                                 } else {
1280                                         $sql .= ',';
1281                                 }
1282                                 $sql .= '(' . $this->makeList( $row ) . ')';
1283                         }
1284                 } else {
1285                         $sql .= '(' . $this->makeList( $a ) . ')';
1286                 }
1287                 return (bool)$this->query( $sql, $fname );
1288         }
1289
1290         /**
1291          * Make UPDATE options for the Database::update function
1292          *
1293          * @private
1294          * @param array $options The options passed to Database::update
1295          * @return string
1296          */
1297         function makeUpdateOptions( $options ) {
1298                 if( !is_array( $options ) ) {
1299                         $options = array( $options );
1300                 }
1301                 $opts = array();
1302                 if ( in_array( 'LOW_PRIORITY', $options ) )
1303                         $opts[] = $this->lowPriorityOption();
1304                 if ( in_array( 'IGNORE', $options ) )
1305                         $opts[] = 'IGNORE';
1306                 return implode(' ', $opts);
1307         }
1308
1309         /**
1310          * UPDATE wrapper, takes a condition array and a SET array
1311          *
1312          * @param string $table  The table to UPDATE
1313          * @param array  $values An array of values to SET
1314          * @param array  $conds  An array of conditions (WHERE). Use '*' to update all rows.
1315          * @param string $fname  The Class::Function calling this function
1316          *                       (for the log)
1317          * @param array  $options An array of UPDATE options, can be one or
1318          *                        more of IGNORE, LOW_PRIORITY
1319          * @return bool
1320          */
1321         function update( $table, $values, $conds, $fname = 'Database::update', $options = array() ) {
1322                 $table = $this->tableName( $table );
1323                 $opts = $this->makeUpdateOptions( $options );
1324                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1325                 if ( $conds != '*' ) {
1326                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1327                 }
1328                 return $this->query( $sql, $fname );
1329         }
1330
1331         /**
1332          * Makes an encoded list of strings from an array
1333          * $mode:
1334          *        LIST_COMMA         - comma separated, no field names
1335          *        LIST_AND           - ANDed WHERE clause (without the WHERE)
1336          *        LIST_OR            - ORed WHERE clause (without the WHERE)
1337          *        LIST_SET           - comma separated with field names, like a SET clause
1338          *        LIST_NAMES         - comma separated field names
1339          */
1340         function makeList( $a, $mode = LIST_COMMA ) {
1341                 if ( !is_array( $a ) ) {
1342                         throw new DBUnexpectedError( $this, 'Database::makeList called with incorrect parameters' );
1343                 }
1344
1345                 $first = true;
1346                 $list = '';
1347                 foreach ( $a as $field => $value ) {
1348                         if ( !$first ) {
1349                                 if ( $mode == LIST_AND ) {
1350                                         $list .= ' AND ';
1351                                 } elseif($mode == LIST_OR) {
1352                                         $list .= ' OR ';
1353                                 } else {
1354                                         $list .= ',';
1355                                 }
1356                         } else {
1357                                 $first = false;
1358                         }
1359                         if ( ($mode == LIST_AND || $mode == LIST_OR) && is_numeric( $field ) ) {
1360                                 $list .= "($value)";
1361                         } elseif ( ($mode == LIST_SET) && is_numeric( $field ) ) {
1362                                 $list .= "$value";
1363                         } elseif ( ($mode == LIST_AND || $mode == LIST_OR) && is_array($value) ) {
1364                                 if( count( $value ) == 0 ) {
1365                                         throw new MWException( __METHOD__.': empty input' );
1366                                 } elseif( count( $value ) == 1 ) {
1367                                         // Special-case single values, as IN isn't terribly efficient
1368                                         // Don't necessarily assume the single key is 0; we don't
1369                                         // enforce linear numeric ordering on other arrays here.
1370                                         $value = array_values( $value );
1371                                         $list .= $field." = ".$this->addQuotes( $value[0] );
1372                                 } else {
1373                                         $list .= $field." IN (".$this->makeList($value).") ";
1374                                 }
1375                         } elseif( is_null($value) ) {
1376                                 if ( $mode == LIST_AND || $mode == LIST_OR ) {
1377                                         $list .= "$field IS ";
1378                                 } elseif ( $mode == LIST_SET ) {
1379                                         $list .= "$field = ";
1380                                 }
1381                                 $list .= 'NULL';
1382                         } else {
1383                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
1384                                         $list .= "$field = ";
1385                                 }
1386                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
1387                         }
1388                 }
1389                 return $list;
1390         }
1391
1392         /**
1393          * Change the current database
1394          */
1395         function selectDB( $db ) {
1396                 $this->mDBname = $db;
1397                 return mysql_select_db( $db, $this->mConn );
1398         }
1399
1400         /**
1401          * Get the current DB name
1402          */
1403         function getDBname() {
1404                 return $this->mDBname;
1405         }
1406
1407         /**
1408          * Get the server hostname or IP address
1409          */
1410         function getServer() {
1411                 return $this->mServer;
1412         }
1413
1414         /**
1415          * Format a table name ready for use in constructing an SQL query
1416          *
1417          * This does two important things: it quotes the table names to clean them up,
1418          * and it adds a table prefix if only given a table name with no quotes.
1419          *
1420          * All functions of this object which require a table name call this function
1421          * themselves. Pass the canonical name to such functions. This is only needed
1422          * when calling query() directly.
1423          *
1424          * @param string $name database table name
1425          * @return string full database name
1426          */
1427         function tableName( $name ) {
1428                 global $wgSharedDB, $wgSharedPrefix, $wgSharedTables;
1429                 # Skip the entire process when we have a string quoted on both ends.
1430                 # Note that we check the end so that we will still quote any use of
1431                 # use of `database`.table. But won't break things if someone wants
1432                 # to query a database table with a dot in the name.
1433                 if ( $name[0] == '`' && substr( $name, -1, 1 ) == '`' ) return $name;
1434
1435                 # Lets test for any bits of text that should never show up in a table
1436                 # name. Basically anything like JOIN or ON which are actually part of
1437                 # SQL queries, but may end up inside of the table value to combine
1438                 # sql. Such as how the API is doing.
1439                 # Note that we use a whitespace test rather than a \b test to avoid
1440                 # any remote case where a word like on may be inside of a table name
1441                 # surrounded by symbols which may be considered word breaks.
1442                 if( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) return $name;
1443
1444                 # Split database and table into proper variables.
1445                 # We reverse the explode so that database.table and table both output
1446                 # the correct table.
1447                 $dbDetails = array_reverse( explode( '.', $name, 2 ) );
1448                 if( isset( $dbDetails[1] ) ) @list( $table, $database ) = $dbDetails;
1449                 else                         @list( $table ) = $dbDetails;
1450                 $prefix = $this->mTablePrefix; # Default prefix
1451
1452                 # A database name has been specified in input. Quote the table name
1453                 # because we don't want any prefixes added.
1454                 if( isset($database) ) $table = ( $table[0] == '`' ? $table : "`{$table}`" );
1455
1456                 # Note that we use the long format because php will complain in in_array if
1457                 # the input is not an array, and will complain in is_array if it is not set.
1458                 if( !isset( $database ) # Don't use shared database if pre selected.
1459                  && isset( $wgSharedDB ) # We have a shared database
1460                  && $table[0] != '`' # Paranoia check to prevent shared tables listing '`table`'
1461                  && isset( $wgSharedTables )
1462                  && is_array( $wgSharedTables )
1463                  && in_array( $table, $wgSharedTables ) ) { # A shared table is selected
1464                         $database = $wgSharedDB;
1465                         $prefix   = isset( $wgSharedPrefix ) ? $wgSharedPrefix : $prefix;
1466                 }
1467
1468                 # Quote the $database and $table and apply the prefix if not quoted.
1469                 if( isset($database) ) $database = ( $database[0] == '`' ? $database : "`{$database}`" );
1470                 $table = ( $table[0] == '`' ? $table : "`{$prefix}{$table}`" );
1471
1472                 # Merge our database and table into our final table name.
1473                 $tableName = ( isset($database) ? "{$database}.{$table}" : "{$table}" );
1474
1475                 # We're finished, return.
1476                 return $tableName;
1477         }
1478
1479         /**
1480          * Fetch a number of table names into an array
1481          * This is handy when you need to construct SQL for joins
1482          *
1483          * Example:
1484          * extract($dbr->tableNames('user','watchlist'));
1485          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1486          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1487          */
1488         public function tableNames() {
1489                 $inArray = func_get_args();
1490                 $retVal = array();
1491                 foreach ( $inArray as $name ) {
1492                         $retVal[$name] = $this->tableName( $name );
1493                 }
1494                 return $retVal;
1495         }
1496
1497         /**
1498          * Fetch a number of table names into an zero-indexed numerical array
1499          * This is handy when you need to construct SQL for joins
1500          *
1501          * Example:
1502          * list( $user, $watchlist ) = $dbr->tableNamesN('user','watchlist');
1503          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1504          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1505          */
1506         public function tableNamesN() {
1507                 $inArray = func_get_args();
1508                 $retVal = array();
1509                 foreach ( $inArray as $name ) {
1510                         $retVal[] = $this->tableName( $name );
1511                 }
1512                 return $retVal;
1513         }
1514
1515         /**
1516          * @private
1517          */
1518         function tableNamesWithUseIndexOrJOIN( $tables, $use_index = array(), $join_conds = array() ) {
1519                 $ret = array();
1520                 $retJOIN = array();
1521                 $use_index_safe = is_array($use_index) ? $use_index : array();
1522                 $join_conds_safe = is_array($join_conds) ? $join_conds : array();
1523                 foreach ( $tables as $table ) {
1524                         // Is there a JOIN and INDEX clause for this table?
1525                         if ( isset($join_conds_safe[$table]) && isset($use_index_safe[$table]) ) {
1526                                 $tableClause = $join_conds_safe[$table][0] . ' ' . $this->tableName( $table );
1527                                 $tableClause .= ' ' . $this->useIndexClause( implode( ',', (array)$use_index_safe[$table] ) );
1528                                 $tableClause .= ' ON (' . $this->makeList((array)$join_conds_safe[$table][1], LIST_AND) . ')';
1529                                 $retJOIN[] = $tableClause;
1530                         // Is there an INDEX clause?
1531                         } else if ( isset($use_index_safe[$table]) ) {
1532                                 $tableClause = $this->tableName( $table );
1533                                 $tableClause .= ' ' . $this->useIndexClause( implode( ',', (array)$use_index_safe[$table] ) );
1534                                 $ret[] = $tableClause;
1535                         // Is there a JOIN clause?
1536                         } else if ( isset($join_conds_safe[$table]) ) {
1537                                 $tableClause = $join_conds_safe[$table][0] . ' ' . $this->tableName( $table );
1538                                 $tableClause .= ' ON (' . $this->makeList((array)$join_conds_safe[$table][1], LIST_AND) . ')';
1539                                 $retJOIN[] = $tableClause;
1540                         } else {
1541                                 $tableClause = $this->tableName( $table );
1542                                 $ret[] = $tableClause;
1543                         }
1544                 }
1545                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
1546                 $straightJoins = !empty($ret) ? implode( ',', $ret ) : "";
1547                 $otherJoins = !empty($retJOIN) ? implode( ' ', $retJOIN ) : "";
1548                 // Compile our final table clause
1549                 return implode(' ',array($straightJoins,$otherJoins) );
1550         }
1551
1552         /**
1553          * Wrapper for addslashes()
1554          * @param string $s String to be slashed.
1555          * @return string slashed string.
1556          */
1557         function strencode( $s ) {
1558                 return mysql_real_escape_string( $s, $this->mConn );
1559         }
1560
1561         /**
1562          * If it's a string, adds quotes and backslashes
1563          * Otherwise returns as-is
1564          */
1565         function addQuotes( $s ) {
1566                 if ( is_null( $s ) ) {
1567                         return 'NULL';
1568                 } else {
1569                         # This will also quote numeric values. This should be harmless,
1570                         # and protects against weird problems that occur when they really
1571                         # _are_ strings such as article titles and string->number->string
1572                         # conversion is not 1:1.
1573                         return "'" . $this->strencode( $s ) . "'";
1574                 }
1575         }
1576
1577         /**
1578          * Escape string for safe LIKE usage
1579          */
1580         function escapeLike( $s ) {
1581                 $s=$this->strencode( $s );
1582                 $s=str_replace(array('%','_'),array('\%','\_'),$s);
1583                 return $s;
1584         }
1585
1586         /**
1587          * Returns an appropriately quoted sequence value for inserting a new row.
1588          * MySQL has autoincrement fields, so this is just NULL. But the PostgreSQL
1589          * subclass will return an integer, and save the value for insertId()
1590          */
1591         function nextSequenceValue( $seqName ) {
1592                 return NULL;
1593         }
1594
1595         /**
1596          * USE INDEX clause
1597          * PostgreSQL doesn't have them and returns ""
1598          */
1599         function useIndexClause( $index ) {
1600                 return "FORCE INDEX ($index)";
1601         }
1602
1603         /**
1604          * REPLACE query wrapper
1605          * PostgreSQL simulates this with a DELETE followed by INSERT
1606          * $row is the row to insert, an associative array
1607          * $uniqueIndexes is an array of indexes. Each element may be either a
1608          * field name or an array of field names
1609          *
1610          * It may be more efficient to leave off unique indexes which are unlikely to collide.
1611          * However if you do this, you run the risk of encountering errors which wouldn't have
1612          * occurred in MySQL
1613          *
1614          * @todo migrate comment to phodocumentor format
1615          */
1616         function replace( $table, $uniqueIndexes, $rows, $fname = 'Database::replace' ) {
1617                 $table = $this->tableName( $table );
1618
1619                 # Single row case
1620                 if ( !is_array( reset( $rows ) ) ) {
1621                         $rows = array( $rows );
1622                 }
1623
1624                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) .') VALUES ';
1625                 $first = true;
1626                 foreach ( $rows as $row ) {
1627                         if ( $first ) {
1628                                 $first = false;
1629                         } else {
1630                                 $sql .= ',';
1631                         }
1632                         $sql .= '(' . $this->makeList( $row ) . ')';
1633                 }
1634                 return $this->query( $sql, $fname );
1635         }
1636
1637         /**
1638          * DELETE where the condition is a join
1639          * MySQL does this with a multi-table DELETE syntax, PostgreSQL does it with sub-selects
1640          *
1641          * For safety, an empty $conds will not delete everything. If you want to delete all rows where the
1642          * join condition matches, set $conds='*'
1643          *
1644          * DO NOT put the join condition in $conds
1645          *
1646          * @param string $delTable The table to delete from.
1647          * @param string $joinTable The other table.
1648          * @param string $delVar The variable to join on, in the first table.
1649          * @param string $joinVar The variable to join on, in the second table.
1650          * @param array $conds Condition array of field names mapped to variables, ANDed together in the WHERE clause
1651          */
1652         function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds, $fname = 'Database::deleteJoin' ) {
1653                 if ( !$conds ) {
1654                         throw new DBUnexpectedError( $this, 'Database::deleteJoin() called with empty $conds' );
1655                 }
1656
1657                 $delTable = $this->tableName( $delTable );
1658                 $joinTable = $this->tableName( $joinTable );
1659                 $sql = "DELETE $delTable FROM $delTable, $joinTable WHERE $delVar=$joinVar ";
1660                 if ( $conds != '*' ) {
1661                         $sql .= ' AND ' . $this->makeList( $conds, LIST_AND );
1662                 }
1663
1664                 return $this->query( $sql, $fname );
1665         }
1666
1667         /**
1668          * Returns the size of a text field, or -1 for "unlimited"
1669          */
1670         function textFieldSize( $table, $field ) {
1671                 $table = $this->tableName( $table );
1672                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
1673                 $res = $this->query( $sql, 'Database::textFieldSize' );
1674                 $row = $this->fetchObject( $res );
1675                 $this->freeResult( $res );
1676
1677                 $m = array();
1678                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
1679                         $size = $m[1];
1680                 } else {
1681                         $size = -1;
1682                 }
1683                 return $size;
1684         }
1685
1686         /**
1687          * @return string Returns the text of the low priority option if it is supported, or a blank string otherwise
1688          */
1689         function lowPriorityOption() {
1690                 return 'LOW_PRIORITY';
1691         }
1692
1693         /**
1694          * DELETE query wrapper
1695          *
1696          * Use $conds == "*" to delete all rows
1697          */
1698         function delete( $table, $conds, $fname = 'Database::delete' ) {
1699                 if ( !$conds ) {
1700                         throw new DBUnexpectedError( $this, 'Database::delete() called with no conditions' );
1701                 }
1702                 $table = $this->tableName( $table );
1703                 $sql = "DELETE FROM $table";
1704                 if ( $conds != '*' ) {
1705                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1706                 }
1707                 return $this->query( $sql, $fname );
1708         }
1709
1710         /**
1711          * INSERT SELECT wrapper
1712          * $varMap must be an associative array of the form array( 'dest1' => 'source1', ...)
1713          * Source items may be literals rather than field names, but strings should be quoted with Database::addQuotes()
1714          * $conds may be "*" to copy the whole table
1715          * srcTable may be an array of tables.
1716          */
1717         function insertSelect( $destTable, $srcTable, $varMap, $conds, $fname = 'Database::insertSelect',
1718                 $insertOptions = array(), $selectOptions = array() )
1719         {
1720                 $destTable = $this->tableName( $destTable );
1721                 if ( is_array( $insertOptions ) ) {
1722                         $insertOptions = implode( ' ', $insertOptions );
1723                 }
1724                 if( !is_array( $selectOptions ) ) {
1725                         $selectOptions = array( $selectOptions );
1726                 }
1727                 list( $startOpts, $useIndex, $tailOpts ) = $this->makeSelectOptions( $selectOptions );
1728                 if( is_array( $srcTable ) ) {
1729                         $srcTable =  implode( ',', array_map( array( &$this, 'tableName' ), $srcTable ) );
1730                 } else {
1731                         $srcTable = $this->tableName( $srcTable );
1732                 }
1733                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
1734                         " SELECT $startOpts " . implode( ',', $varMap ) .
1735                         " FROM $srcTable $useIndex ";
1736                 if ( $conds != '*' ) {
1737                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1738                 }
1739                 $sql .= " $tailOpts";
1740                 return $this->query( $sql, $fname );
1741         }
1742
1743         /**
1744          * Construct a LIMIT query with optional offset
1745          * This is used for query pages
1746          * $sql string SQL query we will append the limit too
1747          * $limit integer the SQL limit
1748          * $offset integer the SQL offset (default false)
1749          */
1750         function limitResult($sql, $limit, $offset=false) {
1751                 if( !is_numeric($limit) ) {
1752                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
1753                 }
1754                 return "$sql LIMIT "
1755                                 . ( (is_numeric($offset) && $offset != 0) ? "{$offset}," : "" )
1756                                 . "{$limit} ";
1757         }
1758         function limitResultForUpdate($sql, $num) {
1759                 return $this->limitResult($sql, $num, 0);
1760         }
1761
1762         /**
1763          * Returns an SQL expression for a simple conditional.
1764          * Uses IF on MySQL.
1765          *
1766          * @param string $cond SQL expression which will result in a boolean value
1767          * @param string $trueVal SQL expression to return if true
1768          * @param string $falseVal SQL expression to return if false
1769          * @return string SQL fragment
1770          */
1771         function conditional( $cond, $trueVal, $falseVal ) {
1772                 return " IF($cond, $trueVal, $falseVal) ";
1773         }
1774
1775         /**
1776          * Returns a comand for str_replace function in SQL query.
1777          * Uses REPLACE() in MySQL
1778          *
1779          * @param string $orig String or column to modify
1780          * @param string $old String or column to seek
1781          * @param string $new String or column to replace with
1782          */
1783         function strreplace( $orig, $old, $new ) {
1784                 return "REPLACE({$orig}, {$old}, {$new})";
1785         }
1786
1787         /**
1788          * Determines if the last failure was due to a deadlock
1789          */
1790         function wasDeadlock() {
1791                 return $this->lastErrno() == 1213;
1792         }
1793
1794         /**
1795          * Perform a deadlock-prone transaction.
1796          *
1797          * This function invokes a callback function to perform a set of write
1798          * queries. If a deadlock occurs during the processing, the transaction
1799          * will be rolled back and the callback function will be called again.
1800          *
1801          * Usage:
1802          *   $dbw->deadlockLoop( callback, ... );
1803          *
1804          * Extra arguments are passed through to the specified callback function.
1805          *
1806          * Returns whatever the callback function returned on its successful,
1807          * iteration, or false on error, for example if the retry limit was
1808          * reached.
1809          */
1810         function deadlockLoop() {
1811                 $myFname = 'Database::deadlockLoop';
1812
1813                 $this->begin();
1814                 $args = func_get_args();
1815                 $function = array_shift( $args );
1816                 $oldIgnore = $this->ignoreErrors( true );
1817                 $tries = DEADLOCK_TRIES;
1818                 if ( is_array( $function ) ) {
1819                         $fname = $function[0];
1820                 } else {
1821                         $fname = $function;
1822                 }
1823                 do {
1824                         $retVal = call_user_func_array( $function, $args );
1825                         $error = $this->lastError();
1826                         $errno = $this->lastErrno();
1827                         $sql = $this->lastQuery();
1828
1829                         if ( $errno ) {
1830                                 if ( $this->wasDeadlock() ) {
1831                                         # Retry
1832                                         usleep( mt_rand( DEADLOCK_DELAY_MIN, DEADLOCK_DELAY_MAX ) );
1833                                 } else {
1834                                         $this->reportQueryError( $error, $errno, $sql, $fname );
1835                                 }
1836                         }
1837                 } while( $this->wasDeadlock() && --$tries > 0 );
1838                 $this->ignoreErrors( $oldIgnore );
1839                 if ( $tries <= 0 ) {
1840                         $this->query( 'ROLLBACK', $myFname );
1841                         $this->reportQueryError( $error, $errno, $sql, $fname );
1842                         return false;
1843                 } else {
1844                         $this->query( 'COMMIT', $myFname );
1845                         return $retVal;
1846                 }
1847         }
1848
1849         /**
1850          * Do a SELECT MASTER_POS_WAIT()
1851          *
1852          * @param string $file the binlog file
1853          * @param string $pos the binlog position
1854          * @param integer $timeout the maximum number of seconds to wait for synchronisation
1855          */
1856         function masterPosWait( MySQLMasterPos $pos, $timeout ) {
1857                 $fname = 'Database::masterPosWait';
1858                 wfProfileIn( $fname );
1859
1860                 # Commit any open transactions
1861                 if ( $this->mTrxLevel ) {
1862                         $this->immediateCommit();
1863                 }
1864
1865                 if ( !is_null( $this->mFakeSlaveLag ) ) {
1866                         $wait = intval( ( $pos->pos - microtime(true) + $this->mFakeSlaveLag ) * 1e6 );
1867                         if ( $wait > $timeout * 1e6 ) {
1868                                 wfDebug( "Fake slave timed out waiting for $pos ($wait us)\n" );
1869                                 wfProfileOut( $fname );
1870                                 return -1;
1871                         } elseif ( $wait > 0 ) {
1872                                 wfDebug( "Fake slave waiting $wait us\n" );
1873                                 usleep( $wait );
1874                                 wfProfileOut( $fname );
1875                                 return 1;
1876                         } else {
1877                                 wfDebug( "Fake slave up to date ($wait us)\n" );
1878                                 wfProfileOut( $fname );
1879                                 return 0;
1880                         }
1881                 }
1882
1883                 # Call doQuery() directly, to avoid opening a transaction if DBO_TRX is set
1884                 $encFile = $this->addQuotes( $pos->file );
1885                 $encPos = intval( $pos->pos );
1886                 $sql = "SELECT MASTER_POS_WAIT($encFile, $encPos, $timeout)";
1887                 $res = $this->doQuery( $sql );
1888                 if ( $res && $row = $this->fetchRow( $res ) ) {
1889                         $this->freeResult( $res );
1890                         wfProfileOut( $fname );
1891                         return $row[0];
1892                 } else {
1893                         wfProfileOut( $fname );
1894                         return false;
1895                 }
1896         }
1897
1898         /**
1899          * Get the position of the master from SHOW SLAVE STATUS
1900          */
1901         function getSlavePos() {
1902                 if ( !is_null( $this->mFakeSlaveLag ) ) {
1903                         $pos = new MySQLMasterPos( 'fake', microtime(true) - $this->mFakeSlaveLag );
1904                         wfDebug( __METHOD__.": fake slave pos = $pos\n" );
1905                         return $pos;
1906                 }
1907                 $res = $this->query( 'SHOW SLAVE STATUS', 'Database::getSlavePos' );
1908                 $row = $this->fetchObject( $res );
1909                 if ( $row ) {
1910                         return new MySQLMasterPos( $row->Master_Log_File, $row->Read_Master_Log_Pos );
1911                 } else {
1912                         return false;
1913                 }
1914         }
1915
1916         /**
1917          * Get the position of the master from SHOW MASTER STATUS
1918          */
1919         function getMasterPos() {
1920                 if ( $this->mFakeMaster ) {
1921                         return new MySQLMasterPos( 'fake', microtime( true ) );
1922                 }
1923                 $res = $this->query( 'SHOW MASTER STATUS', 'Database::getMasterPos' );
1924                 $row = $this->fetchObject( $res );
1925                 if ( $row ) {
1926                         return new MySQLMasterPos( $row->File, $row->Position );
1927                 } else {
1928                         return false;
1929                 }
1930         }
1931
1932         /**
1933          * Begin a transaction, committing any previously open transaction
1934          */
1935         function begin( $fname = 'Database::begin' ) {
1936                 $this->query( 'BEGIN', $fname );
1937                 $this->mTrxLevel = 1;
1938         }
1939
1940         /**
1941          * End a transaction
1942          */
1943         function commit( $fname = 'Database::commit' ) {
1944                 $this->query( 'COMMIT', $fname );
1945                 $this->mTrxLevel = 0;
1946         }
1947
1948         /**
1949          * Rollback a transaction.
1950          * No-op on non-transactional databases.
1951          */
1952         function rollback( $fname = 'Database::rollback' ) {
1953                 $this->query( 'ROLLBACK', $fname, true );
1954                 $this->mTrxLevel = 0;
1955         }
1956
1957         /**
1958          * Begin a transaction, committing any previously open transaction
1959          * @deprecated use begin()
1960          */
1961         function immediateBegin( $fname = 'Database::immediateBegin' ) {
1962                 $this->begin();
1963         }
1964
1965         /**
1966          * Commit transaction, if one is open
1967          * @deprecated use commit()
1968          */
1969         function immediateCommit( $fname = 'Database::immediateCommit' ) {
1970                 $this->commit();
1971         }
1972
1973         /**
1974          * Return MW-style timestamp used for MySQL schema
1975          */
1976         function timestamp( $ts=0 ) {
1977                 return wfTimestamp(TS_MW,$ts);
1978         }
1979
1980         /**
1981          * Local database timestamp format or null
1982          */
1983         function timestampOrNull( $ts = null ) {
1984                 if( is_null( $ts ) ) {
1985                         return null;
1986                 } else {
1987                         return $this->timestamp( $ts );
1988                 }
1989         }
1990
1991         /**
1992          * @todo document
1993          */
1994         function resultObject( $result ) {
1995                 if( empty( $result ) ) {
1996                         return false;
1997                 } elseif ( $result instanceof ResultWrapper ) {
1998                         return $result;
1999                 } elseif ( $result === true ) {
2000                         // Successful write query
2001                         return $result;
2002                 } else {
2003                         return new ResultWrapper( $this, $result );
2004                 }
2005         }
2006
2007         /**
2008          * Return aggregated value alias
2009          */
2010         function aggregateValue ($valuedata,$valuename='value') {
2011                 return $valuename;
2012         }
2013
2014         /**
2015          * @return string wikitext of a link to the server software's web site
2016          */
2017         function getSoftwareLink() {
2018                 return "[http://www.mysql.com/ MySQL]";
2019         }
2020
2021         /**
2022          * @return string Version information from the database
2023          */
2024         function getServerVersion() {
2025                 return mysql_get_server_info( $this->mConn );
2026         }
2027
2028         /**
2029          * Ping the server and try to reconnect if it there is no connection
2030          */
2031         function ping() {
2032                 if( !function_exists( 'mysql_ping' ) ) {
2033                         wfDebug( "Tried to call mysql_ping but this is ancient PHP version. Faking it!\n" );
2034                         return true;
2035                 }
2036                 $ping = mysql_ping( $this->mConn );
2037                 if ( $ping ) {
2038                         return true;
2039                 }
2040
2041                 // Need to reconnect manually in MySQL client 5.0.13+
2042                 if ( version_compare( mysql_get_client_info(), '5.0.13', '>=' ) ) {
2043                         mysql_close( $this->mConn );
2044                         $this->mOpened = false;
2045                         $this->mConn = false;
2046                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
2047                         return true;
2048                 }
2049                 return false;
2050         }
2051
2052         /**
2053          * Get slave lag.
2054          * At the moment, this will only work if the DB user has the PROCESS privilege
2055          */
2056         function getLag() {
2057                 if ( !is_null( $this->mFakeSlaveLag ) ) {
2058                         wfDebug( "getLag: fake slave lagged {$this->mFakeSlaveLag} seconds\n" );
2059                         return $this->mFakeSlaveLag;
2060                 }
2061                 $res = $this->query( 'SHOW PROCESSLIST' );
2062                 # Find slave SQL thread
2063                 while ( $row = $this->fetchObject( $res ) ) {
2064                         /* This should work for most situations - when default db
2065                          * for thread is not specified, it had no events executed,
2066                          * and therefore it doesn't know yet how lagged it is.
2067                          *
2068                          * Relay log I/O thread does not select databases.
2069                          */
2070                         if ( $row->User == 'system user' &&
2071                                 $row->State != 'Waiting for master to send event' &&
2072                                 $row->State != 'Connecting to master' &&
2073                                 $row->State != 'Queueing master event to the relay log' &&
2074                                 $row->State != 'Waiting for master update' &&
2075                                 $row->State != 'Requesting binlog dump'
2076                                 ) {
2077                                 # This is it, return the time (except -ve)
2078                                 if ( $row->Time > 0x7fffffff ) {
2079                                         return false;
2080                                 } else {
2081                                         return $row->Time;
2082                                 }
2083                         }
2084                 }
2085                 return false;
2086         }
2087
2088         /**
2089          * Get status information from SHOW STATUS in an associative array
2090          */
2091         function getStatus($which="%") {
2092                 $res = $this->query( "SHOW STATUS LIKE '{$which}'" );
2093                 $status = array();
2094                 while ( $row = $this->fetchObject( $res ) ) {
2095                         $status[$row->Variable_name] = $row->Value;
2096                 }
2097                 return $status;
2098         }
2099
2100         /**
2101          * Return the maximum number of items allowed in a list, or 0 for unlimited.
2102          */
2103         function maxListLen() {
2104                 return 0;
2105         }
2106
2107         function encodeBlob($b) {
2108                 return $b;
2109         }
2110
2111         function decodeBlob($b) {
2112                 return $b;
2113         }
2114
2115         /**
2116          * Override database's default connection timeout.
2117          * May be useful for very long batch queries such as
2118          * full-wiki dumps, where a single query reads out
2119          * over hours or days.
2120          * @param int $timeout in seconds
2121          */
2122         public function setTimeout( $timeout ) {
2123                 $this->query( "SET net_read_timeout=$timeout" );
2124                 $this->query( "SET net_write_timeout=$timeout" );
2125         }
2126
2127         /**
2128          * Read and execute SQL commands from a file.
2129          * Returns true on success, error string or exception on failure (depending on object's error ignore settings)
2130          * @param string $filename File name to open
2131          * @param callback $lineCallback Optional function called before reading each line
2132          * @param callback $resultCallback Optional function called for each MySQL result
2133          */
2134         function sourceFile( $filename, $lineCallback = false, $resultCallback = false ) {
2135                 $fp = fopen( $filename, 'r' );
2136                 if ( false === $fp ) {
2137                         throw new MWException( "Could not open \"{$filename}\".\n" );
2138                 }
2139                 $error = $this->sourceStream( $fp, $lineCallback, $resultCallback );
2140                 fclose( $fp );
2141                 return $error;
2142         }
2143
2144         /**
2145          * Read and execute commands from an open file handle
2146          * Returns true on success, error string or exception on failure (depending on object's error ignore settings)
2147          * @param string $fp File handle
2148          * @param callback $lineCallback Optional function called before reading each line
2149          * @param callback $resultCallback Optional function called for each MySQL result
2150          */
2151         function sourceStream( $fp, $lineCallback = false, $resultCallback = false ) {
2152                 $cmd = "";
2153                 $done = false;
2154                 $dollarquote = false;
2155
2156                 while ( ! feof( $fp ) ) {
2157                         if ( $lineCallback ) {
2158                                 call_user_func( $lineCallback );
2159                         }
2160                         $line = trim( fgets( $fp, 1024 ) );
2161                         $sl = strlen( $line ) - 1;
2162
2163                         if ( $sl < 0 ) { continue; }
2164                         if ( '-' == $line{0} && '-' == $line{1} ) { continue; }
2165
2166                         ## Allow dollar quoting for function declarations
2167                         if (substr($line,0,4) == '$mw$') {
2168                                 if ($dollarquote) {
2169                                         $dollarquote = false;
2170                                         $done = true;
2171                                 }
2172                                 else {
2173                                         $dollarquote = true;
2174                                 }
2175                         }
2176                         else if (!$dollarquote) {
2177                                 if ( ';' == $line{$sl} && ($sl < 2 || ';' != $line{$sl - 1})) {
2178                                         $done = true;
2179                                         $line = substr( $line, 0, $sl );
2180                                 }
2181                         }
2182
2183                         if ( '' != $cmd ) { $cmd .= ' '; }
2184                         $cmd .= "$line\n";
2185
2186                         if ( $done ) {
2187                                 $cmd = str_replace(';;', ";", $cmd);
2188                                 $cmd = $this->replaceVars( $cmd );
2189                                 $res = $this->query( $cmd, __METHOD__ );
2190                                 if ( $resultCallback ) {
2191                                         call_user_func( $resultCallback, $res, $this );
2192                                 }
2193
2194                                 if ( false === $res ) {
2195                                         $err = $this->lastError();
2196                                         return "Query \"{$cmd}\" failed with error code \"$err\".\n";
2197                                 }
2198
2199                                 $cmd = '';
2200                                 $done = false;
2201                         }
2202                 }
2203                 return true;
2204         }
2205
2206
2207         /**
2208          * Replace variables in sourced SQL
2209          */
2210         protected function replaceVars( $ins ) {
2211                 $varnames = array(
2212                         'wgDBserver', 'wgDBname', 'wgDBintlname', 'wgDBuser',
2213                         'wgDBpassword', 'wgDBsqluser', 'wgDBsqlpassword',
2214                         'wgDBadminuser', 'wgDBadminpassword', 'wgDBTableOptions',
2215                 );
2216
2217                 // Ordinary variables
2218                 foreach ( $varnames as $var ) {
2219                         if( isset( $GLOBALS[$var] ) ) {
2220                                 $val = addslashes( $GLOBALS[$var] ); // FIXME: safety check?
2221                                 $ins = str_replace( '{$' . $var . '}', $val, $ins );
2222                                 $ins = str_replace( '/*$' . $var . '*/`', '`' . $val, $ins );
2223                                 $ins = str_replace( '/*$' . $var . '*/', $val, $ins );
2224                         }
2225                 }
2226
2227                 // Table prefixes
2228                 $ins = preg_replace_callback( '/\/\*(?:\$wgDBprefix|_)\*\/([a-zA-Z_0-9]*)/',
2229                         array( &$this, 'tableNameCallback' ), $ins );
2230                 return $ins;
2231         }
2232
2233         /**
2234          * Table name callback
2235          * @private
2236          */
2237         protected function tableNameCallback( $matches ) {
2238                 return $this->tableName( $matches[1] );
2239         }
2240
2241         /*
2242          * Build a concatenation list to feed into a SQL query
2243         */
2244         function buildConcat( $stringList ) {
2245                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
2246         }
2247
2248         /**
2249          * Acquire a lock
2250          *
2251          * Abstracted from Filestore::lock() so child classes can implement for
2252          * their own needs.
2253          *
2254          * @param string $lockName Name of lock to aquire
2255          * @param string $method Name of method calling us
2256          * @return bool
2257          */
2258         public function lock( $lockName, $method ) {
2259                 $lockName = $this->addQuotes( $lockName );
2260                 $result = $this->query( "SELECT GET_LOCK($lockName, 5) AS lockstatus", $method );
2261                 $row = $this->fetchObject( $result );
2262                 $this->freeResult( $result );
2263
2264                 if( $row->lockstatus == 1 ) {
2265                         return true;
2266                 } else {
2267                         wfDebug( __METHOD__." failed to acquire lock\n" );
2268                         return false;
2269                 }
2270         }
2271         /**
2272          * Release a lock.
2273          *
2274          * @todo fixme - Figure out a way to return a bool
2275          * based on successful lock release.
2276          *
2277          * @param string $lockName Name of lock to release
2278          * @param string $method Name of method calling us
2279          */
2280         public function unlock( $lockName, $method ) {
2281                 $lockName = $this->addQuotes( $lockName );
2282                 $result = $this->query( "SELECT RELEASE_LOCK($lockName)", $method );
2283                 $this->freeResult( $result );
2284         }
2285
2286         /**
2287          * Get search engine class. All subclasses of this
2288          * need to implement this if they wish to use searching.
2289          *
2290          * @return string
2291          */
2292         public function getSearchEngine() {
2293                 return "SearchMySQL";
2294         }
2295 }
2296
2297 /**
2298  * Database abstraction object for mySQL
2299  * Inherit all methods and properties of Database::Database()
2300  *
2301  * @ingroup Database
2302  * @see Database
2303  */
2304 class DatabaseMysql extends Database {
2305         # Inherit all
2306 }
2307
2308 /******************************************************************************
2309  * Utility classes
2310  *****************************************************************************/
2311
2312 /**
2313  * Utility class.
2314  * @ingroup Database
2315  */
2316 class DBObject {
2317         public $mData;
2318
2319         function DBObject($data) {
2320                 $this->mData = $data;
2321         }
2322
2323         function isLOB() {
2324                 return false;
2325         }
2326
2327         function data() {
2328                 return $this->mData;
2329         }
2330 }
2331
2332 /**
2333  * Utility class
2334  * @ingroup Database
2335  *
2336  * This allows us to distinguish a blob from a normal string and an array of strings
2337  */
2338 class Blob {
2339         private $mData;
2340         function __construct($data) {
2341                 $this->mData = $data;
2342         }
2343         function fetch() {
2344                 return $this->mData;
2345         }
2346 }
2347
2348 /**
2349  * Utility class.
2350  * @ingroup Database
2351  */
2352 class MySQLField {
2353         private $name, $tablename, $default, $max_length, $nullable,
2354                 $is_pk, $is_unique, $is_multiple, $is_key, $type;
2355         function __construct ($info) {
2356                 $this->name = $info->name;
2357                 $this->tablename = $info->table;
2358                 $this->default = $info->def;
2359                 $this->max_length = $info->max_length;
2360                 $this->nullable = !$info->not_null;
2361                 $this->is_pk = $info->primary_key;
2362                 $this->is_unique = $info->unique_key;
2363                 $this->is_multiple = $info->multiple_key;
2364                 $this->is_key = ($this->is_pk || $this->is_unique || $this->is_multiple);
2365                 $this->type = $info->type;
2366         }
2367
2368         function name() {
2369                 return $this->name;
2370         }
2371
2372         function tableName() {
2373                 return $this->tableName;
2374         }
2375
2376         function defaultValue() {
2377                 return $this->default;
2378         }
2379
2380         function maxLength() {
2381                 return $this->max_length;
2382         }
2383
2384         function nullable() {
2385                 return $this->nullable;
2386         }
2387
2388         function isKey() {
2389                 return $this->is_key;
2390         }
2391
2392         function isMultipleKey() {
2393                 return $this->is_multiple;
2394         }
2395
2396         function type() {
2397                 return $this->type;
2398         }
2399 }
2400
2401 /******************************************************************************
2402  * Error classes
2403  *****************************************************************************/
2404
2405 /**
2406  * Database error base class
2407  * @ingroup Database
2408  */
2409 class DBError extends MWException {
2410         public $db;
2411
2412         /**
2413          * Construct a database error
2414          * @param Database $db The database object which threw the error
2415          * @param string $error A simple error message to be used for debugging
2416          */
2417         function __construct( Database &$db, $error ) {
2418                 $this->db =& $db;
2419                 parent::__construct( $error );
2420         }
2421 }
2422
2423 /**
2424  * @ingroup Database
2425  */
2426 class DBConnectionError extends DBError {
2427         public $error;
2428
2429         function __construct( Database &$db, $error = 'unknown error' ) {
2430                 $msg = 'DB connection error';
2431                 if ( trim( $error ) != '' ) {
2432                         $msg .= ": $error";
2433                 }
2434                 $this->error = $error;
2435                 parent::__construct( $db, $msg );
2436         }
2437
2438         function useOutputPage() {
2439                 // Not likely to work
2440                 return false;
2441         }
2442
2443         function useMessageCache() {
2444                 // Not likely to work
2445                 return false;
2446         }
2447
2448         function getText() {
2449                 return $this->getMessage() . "\n";
2450         }
2451
2452         function getLogMessage() {
2453                 # Don't send to the exception log
2454                 return false;
2455         }
2456
2457         function getPageTitle() {
2458                 global $wgSitename;
2459                 return "$wgSitename has a problem";
2460         }
2461
2462         function getHTML() {
2463                 global $wgTitle, $wgUseFileCache, $title, $wgInputEncoding;
2464                 global $wgSitename, $wgServer, $wgMessageCache;
2465
2466                 # I give up, Brion is right. Getting the message cache to work when there is no DB is tricky.
2467                 # Hard coding strings instead.
2468
2469                 $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>";
2470                 $mainpage = 'Main Page';
2471                 $searchdisabled = <<<EOT
2472 <p style="margin: 1.5em 2em 1em">$wgSitename search is disabled for performance reasons. You can search via Google in the meantime.
2473 <span style="font-size: 89%; display: block; margin-left: .2em">Note that their indexes of $wgSitename content may be out of date.</span></p>',
2474 EOT;
2475
2476                 $googlesearch = "
2477 <!-- SiteSearch Google -->
2478 <FORM method=GET action=\"http://www.google.com/search\">
2479 <TABLE bgcolor=\"#FFFFFF\"><tr><td>
2480 <A HREF=\"http://www.google.com/\">
2481 <IMG SRC=\"http://www.google.com/logos/Logo_40wht.gif\"
2482 border=\"0\" ALT=\"Google\"></A>
2483 </td>
2484 <td>
2485 <INPUT TYPE=text name=q size=31 maxlength=255 value=\"$1\">
2486 <INPUT type=submit name=btnG VALUE=\"Google Search\">
2487 <font size=-1>
2488 <input type=hidden name=domains value=\"$wgServer\"><br /><input type=radio name=sitesearch value=\"\"> WWW <input type=radio name=sitesearch value=\"$wgServer\" checked> $wgServer <br />
2489 <input type='hidden' name='ie' value='$2'>
2490 <input type='hidden' name='oe' value='$2'>
2491 </font>
2492 </td></tr></TABLE>
2493 </FORM>
2494 <!-- SiteSearch Google -->";
2495                 $cachederror = "The following is a cached copy of the requested page, and may not be up to date. ";
2496
2497                 # No database access
2498                 if ( is_object( $wgMessageCache ) ) {
2499                         $wgMessageCache->disable();
2500                 }
2501
2502                 if ( trim( $this->error ) == '' ) {
2503                         $this->error = $this->db->getProperty('mServer');
2504                 }
2505
2506                 $text = str_replace( '$1', $this->error, $noconnect );
2507
2508                 if($wgUseFileCache) {
2509                         if($wgTitle) {
2510                                 $t =& $wgTitle;
2511                         } else {
2512                                 if($title) {
2513                                         $t = Title::newFromURL( $title );
2514                                 } elseif (@/**/$_REQUEST['search']) {
2515                                         $search = $_REQUEST['search'];
2516                                         return $searchdisabled .
2517                                           str_replace( array( '$1', '$2' ), array( htmlspecialchars( $search ),
2518                                           $wgInputEncoding ), $googlesearch );
2519                                 } else {
2520                                         $t = Title::newFromText( $mainpage );
2521                                 }
2522                         }
2523
2524                         $cache = new HTMLFileCache( $t );
2525                         if( $cache->isFileCached() ) {
2526                                 // @todo, FIXME: $msg is not defined on the next line.
2527                                 $msg = '<p style="color: red"><b>'.$text."<br />\n" .
2528                                         $cachederror . "</b></p>\n";
2529
2530                                 $tag = '<div id="article">';
2531                                 $text = str_replace(
2532                                         $tag,
2533                                         $tag . $text,
2534                                         $cache->fetchPageText() );
2535                         }
2536                 }
2537
2538                 return $text;
2539         }
2540 }
2541
2542 /**
2543  * @ingroup Database
2544  */
2545 class DBQueryError extends DBError {
2546         public $error, $errno, $sql, $fname;
2547
2548         function __construct( Database &$db, $error, $errno, $sql, $fname ) {
2549                 $message = "A database error has occurred\n" .
2550                   "Query: $sql\n" .
2551                   "Function: $fname\n" .
2552                   "Error: $errno $error\n";
2553
2554                 parent::__construct( $db, $message );
2555                 $this->error = $error;
2556                 $this->errno = $errno;
2557                 $this->sql = $sql;
2558                 $this->fname = $fname;
2559         }
2560
2561         function getText() {
2562                 if ( $this->useMessageCache() ) {
2563                         return wfMsg( 'dberrortextcl', htmlspecialchars( $this->getSQL() ),
2564                           htmlspecialchars( $this->fname ), $this->errno, htmlspecialchars( $this->error ) ) . "\n";
2565                 } else {
2566                         return $this->getMessage();
2567                 }
2568         }
2569
2570         function getSQL() {
2571                 global $wgShowSQLErrors;
2572                 if( !$wgShowSQLErrors ) {
2573                         return $this->msg( 'sqlhidden', 'SQL hidden' );
2574                 } else {
2575                         return $this->sql;
2576                 }
2577         }
2578
2579         function getLogMessage() {
2580                 # Don't send to the exception log
2581                 return false;
2582         }
2583
2584         function getPageTitle() {
2585                 return $this->msg( 'databaseerror', 'Database error' );
2586         }
2587
2588         function getHTML() {
2589                 if ( $this->useMessageCache() ) {
2590                         return wfMsgNoDB( 'dberrortext', htmlspecialchars( $this->getSQL() ),
2591                           htmlspecialchars( $this->fname ), $this->errno, htmlspecialchars( $this->error ) );
2592                 } else {
2593                         return nl2br( htmlspecialchars( $this->getMessage() ) );
2594                 }
2595         }
2596 }
2597
2598 /**
2599  * @ingroup Database
2600  */
2601 class DBUnexpectedError extends DBError {}
2602
2603
2604 /**
2605  * Result wrapper for grabbing data queried by someone else
2606  * @ingroup Database
2607  */
2608 class ResultWrapper implements Iterator {
2609         var $db, $result, $pos = 0, $currentRow = null;
2610
2611         /**
2612          * Create a new result object from a result resource and a Database object
2613          */
2614         function ResultWrapper( $database, $result ) {
2615                 $this->db = $database;
2616                 if ( $result instanceof ResultWrapper ) {
2617                         $this->result = $result->result;
2618                 } else {
2619                         $this->result = $result;
2620                 }
2621         }
2622
2623         /**
2624          * Get the number of rows in a result object
2625          */
2626         function numRows() {
2627                 return $this->db->numRows( $this->result );
2628         }
2629
2630         /**
2631          * Fetch the next row from the given result object, in object form.
2632          * Fields can be retrieved with $row->fieldname, with fields acting like
2633          * member variables.
2634          *
2635          * @param $res SQL result object as returned from Database::query(), etc.
2636          * @return MySQL row object
2637          * @throws DBUnexpectedError Thrown if the database returns an error
2638          */
2639         function fetchObject() {
2640                 return $this->db->fetchObject( $this->result );
2641         }
2642
2643         /**
2644          * Fetch the next row from the given result object, in associative array
2645          * form.  Fields are retrieved with $row['fieldname'].
2646          *
2647          * @param $res SQL result object as returned from Database::query(), etc.
2648          * @return MySQL row object
2649          * @throws DBUnexpectedError Thrown if the database returns an error
2650          */
2651         function fetchRow() {
2652                 return $this->db->fetchRow( $this->result );
2653         }
2654
2655         /**
2656          * Free a result object
2657          */
2658         function free() {
2659                 $this->db->freeResult( $this->result );
2660                 unset( $this->result );
2661                 unset( $this->db );
2662         }
2663
2664         /**
2665          * Change the position of the cursor in a result object
2666          * See mysql_data_seek()
2667          */
2668         function seek( $row ) {
2669                 $this->db->dataSeek( $this->result, $row );
2670         }
2671
2672         /*********************
2673          * Iterator functions
2674          * Note that using these in combination with the non-iterator functions
2675          * above may cause rows to be skipped or repeated.
2676          */
2677
2678         function rewind() {
2679                 if ($this->numRows()) {
2680                         $this->db->dataSeek($this->result, 0);
2681                 }
2682                 $this->pos = 0;
2683                 $this->currentRow = null;
2684         }
2685
2686         function current() {
2687                 if ( is_null( $this->currentRow ) ) {
2688                         $this->next();
2689                 }
2690                 return $this->currentRow;
2691         }
2692
2693         function key() {
2694                 return $this->pos;
2695         }
2696
2697         function next() {
2698                 $this->pos++;
2699                 $this->currentRow = $this->fetchObject();
2700                 return $this->currentRow;
2701         }
2702
2703         function valid() {
2704                 return $this->current() !== false;
2705         }
2706 }
2707
2708 class MySQLMasterPos {
2709         var $file, $pos;
2710
2711         function __construct( $file, $pos ) {
2712                 $this->file = $file;
2713                 $this->pos = $pos;
2714         }
2715
2716         function __toString() {
2717                 return "{$this->file}/{$this->pos}";
2718         }
2719 }