includes/Database.php

   1 <?php
   2 /**
   3  * This file deals with MySQL interface functions
   4  * and query specifics/optimisations
   5  * @package MediaWiki
   6  */
   7
   8 /**
   9  * Depends on the CacheManager
  10  */
  11 require_once( 'CacheManager.php' );
  12
  13 /** See Database::makeList() */
  14 define( 'LIST_COMMA', 0 );
  15 define( 'LIST_AND', 1 );
  16 define( 'LIST_SET', 2 );
  17 define( 'LIST_NAMES', 3);
  18 define( 'LIST_OR', 4);
  19
  20 /** Number of times to re-try an operation in case of deadlock */
  21 define( 'DEADLOCK_TRIES', 4 );
  22 /** Minimum time to wait before retry, in microseconds */
  23 define( 'DEADLOCK_DELAY_MIN', 500000 );
  24 /** Maximum time to wait before retry */
  25 define( 'DEADLOCK_DELAY_MAX', 1500000 );
  26
  27 class DBObject {
  28         var $mData;
  29
  30         function DBObject($data) {
  31                 $this->mData = $data;
  32         }
  33
  34         function isLOB() {
  35                 return false;
  36         }
  37
  38         function data() {
  39                 return $this->mData;
  40         }
  41 };
  42
  43 /**
  44  * Database abstraction object
  45  * @package MediaWiki
  46  */
  47 class Database {
  48
  49 #------------------------------------------------------------------------------
  50 # Variables
  51 #------------------------------------------------------------------------------
  52         /**#@+
  53          * @access private
  54          */
  55         var $mLastQuery = '';
  56
  57         var $mServer, $mUser, $mPassword, $mConn = null, $mDBname;
  58         var $mOut, $mOpened = false;
  59
  60         var $mFailFunction;
  61         var $mTablePrefix;
  62         var $mFlags;
  63         var $mTrxLevel = 0;
  64         var $mErrorCount = 0;
  65         var $mLBInfo = array();
  66         /**#@-*/
  67
  68 #------------------------------------------------------------------------------
  69 # Accessors
  70 #------------------------------------------------------------------------------
  71         # These optionally set a variable and return the previous state
  72
  73         /**
  74          * Fail function, takes a Database as a parameter
  75          * Set to false for default, 1 for ignore errors
  76          */
  77         function failFunction( $function = NULL ) {
  78                 return wfSetVar( $this->mFailFunction, $function );
  79         }
  80
  81         /**
  82          * Output page, used for reporting errors
  83          * FALSE means discard output
  84          */
  85         function &setOutputPage( &$out ) {
  86                 $this->mOut =& $out;
  87         }
  88
  89         /**
  90          * Boolean, controls output of large amounts of debug information
  91          */
  92         function debug( $debug = NULL ) {
  93                 return wfSetBit( $this->mFlags, DBO_DEBUG, $debug );
  94         }
  95
  96         /**
  97          * Turns buffering of SQL result sets on (true) or off (false).
  98          * Default is "on" and it should not be changed without good reasons.
  99          */
 100         function bufferResults( $buffer = NULL ) {
 101                 if ( is_null( $buffer ) ) {
 102                         return !(bool)( $this->mFlags & DBO_NOBUFFER );
 103                 } else {
 104                         return !wfSetBit( $this->mFlags, DBO_NOBUFFER, !$buffer );
 105                 }
 106         }
 107
 108         /**
 109          * Turns on (false) or off (true) the automatic generation and sending
 110          * of a "we're sorry, but there has been a database error" page on
 111          * database errors. Default is on (false). When turned off, the
 112          * code should use wfLastErrno() and wfLastError() to handle the
 113          * situation as appropriate.
 114          */
 115         function ignoreErrors( $ignoreErrors = NULL ) {
 116                 return wfSetBit( $this->mFlags, DBO_IGNORE, $ignoreErrors );
 117         }
 118
 119         /**
 120          * The current depth of nested transactions
 121          * @param integer $level
 122          */
 123         function trxLevel( $level = NULL ) {
 124                 return wfSetVar( $this->mTrxLevel, $level );
 125         }
 126
 127         /**
 128          * Number of errors logged, only useful when errors are ignored
 129          */
 130         function errorCount( $count = NULL ) {
 131                 return wfSetVar( $this->mErrorCount, $count );
 132         }
 133
 134         /**
 135          * Properties passed down from the server info array of the load balancer
 136          */
 137         function getLBInfo( $name = NULL ) {
 138                 if ( is_null( $name ) ) {
 139                         return $this->mLBInfo;
 140                 } else {
 141                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 142                                 return $this->mLBInfo[$name];
 143                         } else {
 144                                 return NULL;
 145                         }
 146                 }
 147         }
 148
 149         function setLBInfo( $name, $value = NULL ) {
 150                 if ( is_null( $value ) ) {
 151                         $this->mLBInfo = $name;
 152                 } else {
 153                         $this->mLBInfo[$name] = $value;
 154                 }
 155         }
 156
 157         /**#@+
 158          * Get function
 159          */
 160         function lastQuery() { return $this->mLastQuery; }
 161         function isOpen() { return $this->mOpened; }
 162         /**#@-*/
 163
 164         function setFlag( $flag ) {
 165                 $this->mFlags |= $flag;
 166         }
 167
 168         function clearFlag( $flag ) {
 169                 $this->mFlags &= ~$flag;
 170         }
 171
 172         function getFlag( $flag ) {
 173                 return !!($this->mFlags & $flag);
 174         }
 175
 176 #------------------------------------------------------------------------------
 177 # Other functions
 178 #------------------------------------------------------------------------------
 179
 180         /**#@+
 181          * @param string $server database server host
 182          * @param string $user database user name
 183          * @param string $password database user password
 184          * @param string $dbname database name
 185          */
 186
 187         /**
 188          * @param failFunction
 189          * @param $flags
 190          * @param string $tablePrefix Database table prefixes. By default use the prefix gave in LocalSettings.php
 191          */
 192         function Database( $server = false, $user = false, $password = false, $dbName = false,
 193                 $failFunction = false, $flags = 0, $tablePrefix = 'get from global' ) {
 194
 195                 global $wgOut, $wgDBprefix, $wgCommandLineMode;
 196                 # Can't get a reference if it hasn't been set yet
 197                 if ( !isset( $wgOut ) ) {
 198                         $wgOut = NULL;
 199                 }
 200                 $this->mOut =& $wgOut;
 201
 202                 $this->mFailFunction = $failFunction;
 203                 $this->mFlags = $flags;
 204
 205                 if ( $this->mFlags & DBO_DEFAULT ) {
 206                         if ( $wgCommandLineMode ) {
 207                                 $this->mFlags &= ~DBO_TRX;
 208                         } else {
 209                                 $this->mFlags |= DBO_TRX;
 210                         }
 211                 }
 212
 213                 /*
 214                 // Faster read-only access
 215                 if ( wfReadOnly() ) {
 216                         $this->mFlags |= DBO_PERSISTENT;
 217                         $this->mFlags &= ~DBO_TRX;
 218                 }*/
 219
 220                 /** Get the default table prefix*/
 221                 if ( $tablePrefix == 'get from global' ) {
 222                         $this->mTablePrefix = $wgDBprefix;
 223                 } else {
 224                         $this->mTablePrefix = $tablePrefix;
 225                 }
 226
 227                 if ( $server ) {
 228                         $this->open( $server, $user, $password, $dbName );
 229                 }
 230         }
 231
 232         /**
 233          * @static
 234          * @param failFunction
 235          * @param $flags
 236          */
 237         function newFromParams( $server, $user, $password, $dbName,
 238                 $failFunction = false, $flags = 0 )
 239         {
 240                 return new Database( $server, $user, $password, $dbName, $failFunction, $flags );
 241         }
 242
 243         /**
 244          * Usually aborts on failure
 245          * If the failFunction is set to a non-zero integer, returns success
 246          */
 247         function open( $server, $user, $password, $dbName ) {
 248                 global $wguname;
 249
 250                 # Test for missing mysql.so
 251                 # First try to load it
 252                 if (!@extension_loaded('mysql')) {
 253                         @dl('mysql.so');
 254                 }
 255
 256                 # Otherwise we get a suppressed fatal error, which is very hard to track down
 257                 if ( !function_exists( 'mysql_connect' ) ) {
 258                         die( "MySQL functions missing, have you compiled PHP with the --with-mysql option?\n" );
 259                 }
 260
 261                 $this->close();
 262                 $this->mServer = $server;
 263                 $this->mUser = $user;
 264                 $this->mPassword = $password;
 265                 $this->mDBname = $dbName;
 266
 267                 $success = false;
 268
 269                 if ( $this->mFlags & DBO_PERSISTENT ) {
 270                         @/**/$this->mConn = mysql_pconnect( $server, $user, $password );
 271                 } else {
 272                         # Create a new connection...
 273                         if( version_compare( PHP_VERSION, '4.2.0', 'ge' ) ) {
 274                                 @/**/$this->mConn = mysql_connect( $server, $user, $password, true );
 275                         } else {
 276                                 # On PHP 4.1 the new_link parameter is not available. We cannot
 277                                 # guarantee that we'll actually get a new connection, and this
 278                                 # may cause some operations to fail possibly.
 279                                 @/**/$this->mConn = mysql_connect( $server, $user, $password );
 280                         }
 281                 }
 282
 283                 if ( $dbName != '' ) {
 284                         if ( $this->mConn !== false ) {
 285                                 $success = @/**/mysql_select_db( $dbName, $this->mConn );
 286                                 if ( !$success ) {
 287                                         $error = "Error selecting database $dbName on server {$this->mServer} " .
 288                                                 "from client host {$wguname['nodename']}\n";
 289                                         wfDebug( $error );
 290                                 }
 291                         } else {
 292                                 wfDebug( "DB connection error\n" );
 293                                 wfDebug( "Server: $server, User: $user, Password: " .
 294                                         substr( $password, 0, 3 ) . "..., error: " . mysql_error() . "\n" );
 295                                 $success = false;
 296                         }
 297                 } else {
 298                         # Delay USE query
 299                         $success = (bool)$this->mConn;
 300                 }
 301
 302                 if ( !$success ) {
 303                         $this->reportConnectionError();
 304                 }
 305
 306                 global $wgDBmysql5;
 307                 if( $wgDBmysql5 ) {
 308                         // Tell the server we're communicating with it in UTF-8.
 309                         // This may engage various charset conversions.
 310                         $this->query( 'SET NAMES utf8' );
 311                 }
 312
 313                 $this->mOpened = $success;
 314                 return $success;
 315         }
 316         /**#@-*/
 317
 318         /**
 319          * Closes a database connection.
 320          * if it is open : commits any open transactions
 321          *
 322          * @return bool operation success. true if already closed.
 323          */
 324         function close()
 325         {
 326                 $this->mOpened = false;
 327                 if ( $this->mConn ) {
 328                         if ( $this->trxLevel() ) {
 329                                 $this->immediateCommit();
 330                         }
 331                         return mysql_close( $this->mConn );
 332                 } else {
 333                         return true;
 334                 }
 335         }
 336
 337         /**
 338          * @access private
 339          * @param string $error fallback error message, used if none is given by MySQL
 340          */
 341         function reportConnectionError( $error = 'Unknown error' ) {
 342                 $myError = $this->lastError();
 343                 if ( $myError ) {
 344                         $error = $myError;
 345                 }
 346
 347                 if ( $this->mFailFunction ) {
 348                         if ( !is_int( $this->mFailFunction ) ) {
 349                                 $ff = $this->mFailFunction;
 350                                 $ff( $this, $error );
 351                         }
 352                 } else {
 353                         wfEmergencyAbort( $this, $error );
 354                 }
 355         }
 356
 357         /**
 358          * Usually aborts on failure
 359          * If errors are explicitly ignored, returns success
 360          */
 361         function query( $sql, $fname = '', $tempIgnore = false ) {
 362                 global $wgProfiling, $wgCommandLineMode;
 363
 364                 if ( wfReadOnly() ) {
 365                         # This is a quick check for the most common kinds of write query used
 366                         # in MediaWiki, to provide extra safety in addition to UI-level checks.
 367                         # It is not intended to prevent every conceivable write query, or even
 368                         # to handle such queries gracefully.
 369                         if ( preg_match( '/^(?:update|insert|replace|delete)/i', $sql ) ) {
 370                                 wfDebug( "Write query from $fname blocked\n" );
 371                                 return false;
 372                         }
 373                 }
 374
 375                 if ( $wgProfiling ) {
 376                         # generalizeSQL will probably cut down the query to reasonable
 377                         # logging size most of the time. The substr is really just a sanity check.
 378
 379                         # Who's been wasting my precious column space? -- TS
 380                         #$profName = 'query: ' . $fname . ' ' . substr( Database::generalizeSQL( $sql ), 0, 255 );
 381                         $profName = 'query: ' . substr( Database::generalizeSQL( $sql ), 0, 255 );
 382
 383                         wfProfileIn( 'Database::query' );
 384                         wfProfileIn( $profName );
 385                 }
 386
 387                 $this->mLastQuery = $sql;
 388
 389                 # Add a comment for easy SHOW PROCESSLIST interpretation
 390                 if ( $fname ) {
 391                         $commentedSql = preg_replace("/\s/", " /* $fname */ ", $sql, 1);
 392                 } else {
 393                         $commentedSql = $sql;
 394                 }
 395
 396                 # If DBO_TRX is set, start a transaction
 397                 if ( ( $this->mFlags & DBO_TRX ) && !$this->trxLevel() && $sql != 'BEGIN' ) {
 398                         $this->begin();
 399                 }
 400
 401                 if ( $this->debug() ) {
 402                         $sqlx = substr( $commentedSql, 0, 500 );
 403                         $sqlx = strtr( $sqlx, "\t\n", '  ' );
 404                         wfDebug( "SQL: $sqlx\n" );
 405                 }
 406
 407                 # Do the query and handle errors
 408                 $ret = $this->doQuery( $commentedSql );
 409
 410                 # Try reconnecting if the connection was lost
 411                 if ( false === $ret && ( $this->lastErrno() == 2013 || $this->lastErrno() == 2006 ) ) {
 412                         # Transaction is gone, like it or not
 413                         $this->mTrxLevel = 0;
 414                         wfDebug( "Connection lost, reconnecting...\n" );
 415                         if ( $this->ping() ) {
 416                                 wfDebug( "Reconnected\n" );
 417                                 $ret = $this->doQuery( $commentedSql );
 418                         } else {
 419                                 wfDebug( "Failed\n" );
 420                         }
 421                 }
 422
 423                 if ( false === $ret ) {
 424                         $this->reportQueryError( $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 425                 }
 426
 427                 if ( $wgProfiling ) {
 428                         wfProfileOut( $profName );
 429                         wfProfileOut( 'Database::query' );
 430                 }
 431                 return $ret;
 432         }
 433
 434         /**
 435          * The DBMS-dependent part of query()
 436          * @param string $sql SQL query.
 437          */
 438         function doQuery( $sql ) {
 439                 if( $this->bufferResults() ) {
 440                         $ret = mysql_query( $sql, $this->mConn );
 441                 } else {
 442                         $ret = mysql_unbuffered_query( $sql, $this->mConn );
 443                 }
 444                 return $ret;
 445         }
 446
 447         /**
 448          * @param $error
 449          * @param $errno
 450          * @param $sql
 451          * @param string $fname
 452          * @param bool $tempIgnore
 453          */
 454         function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 455                 global $wgCommandLineMode, $wgFullyInitialised;
 456                 # Ignore errors during error handling to avoid infinite recursion
 457                 $ignore = $this->ignoreErrors( true );
 458                 ++$this->mErrorCount;
 459
 460                 if( $ignore || $tempIgnore ) {
 461                         wfDebug("SQL ERROR (ignored): $error\n");
 462                 } else {
 463                         $sql1line = str_replace( "\n", "\\n", $sql );
 464                         wfLogDBError("$fname\t{$this->mServer}\t$errno\t$error\t$sql1line\n");
 465                         wfDebug("SQL ERROR: " . $error . "\n");
 466                         if ( $wgCommandLineMode || !$this->mOut || empty( $wgFullyInitialised ) ) {
 467                                 $message = "A database error has occurred\n" .
 468                                   "Query: $sql\n" .
 469                                   "Function: $fname\n" .
 470                                   "Error: $errno $error\n";
 471                                 if ( !$wgCommandLineMode ) {
 472                                         $message = nl2br( $message );
 473                                 }
 474                                 wfDebugDieBacktrace( $message );
 475                         } else {
 476                                 // this calls wfAbruptExit()
 477                                 $this->mOut->databaseError( $fname, $sql, $error, $errno );
 478                         }
 479                 }
 480                 $this->ignoreErrors( $ignore );
 481         }
 482
 483
 484         /**
 485          * Intended to be compatible with the PEAR::DB wrapper functions.
 486          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
 487          *
 488          * ? = scalar value, quoted as necessary
 489          * ! = raw SQL bit (a function for instance)
 490          * & = filename; reads the file and inserts as a blob
 491          *     (we don't use this though...)
 492          */
 493         function prepare( $sql, $func = 'Database::prepare' ) {
 494                 /* MySQL doesn't support prepared statements (yet), so just
 495                    pack up the query for reference. We'll manually replace
 496                    the bits later. */
 497                 return array( 'query' => $sql, 'func' => $func );
 498         }
 499
 500         function freePrepared( $prepared ) {
 501                 /* No-op for MySQL */
 502         }
 503
 504         /**
 505          * Execute a prepared query with the various arguments
 506          * @param string $prepared the prepared sql
 507          * @param mixed $args Either an array here, or put scalars as varargs
 508          */
 509         function execute( $prepared, $args = null ) {
 510                 if( !is_array( $args ) ) {
 511                         # Pull the var args
 512                         $args = func_get_args();
 513                         array_shift( $args );
 514                 }
 515                 $sql = $this->fillPrepared( $prepared['query'], $args );
 516                 return $this->query( $sql, $prepared['func'] );
 517         }
 518
 519         /**
 520          * Prepare & execute an SQL statement, quoting and inserting arguments
 521          * in the appropriate places.
 522          * @param string $query
 523          * @param string $args ...
 524          */
 525         function safeQuery( $query, $args = null ) {
 526                 $prepared = $this->prepare( $query, 'Database::safeQuery' );
 527                 if( !is_array( $args ) ) {
 528                         # Pull the var args
 529                         $args = func_get_args();
 530                         array_shift( $args );
 531                 }
 532                 $retval = $this->execute( $prepared, $args );
 533                 $this->freePrepared( $prepared );
 534                 return $retval;
 535         }
 536
 537         /**
 538          * For faking prepared SQL statements on DBs that don't support
 539          * it directly.
 540          * @param string $preparedSql - a 'preparable' SQL statement
 541          * @param array $args - array of arguments to fill it with
 542          * @return string executable SQL
 543          */
 544         function fillPrepared( $preparedQuery, $args ) {
 545                 $n = 0;
 546                 reset( $args );
 547                 $this->preparedArgs =& $args;
 548                 return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
 549                         array( &$this, 'fillPreparedArg' ), $preparedQuery );
 550         }
 551
 552         /**
 553          * preg_callback func for fillPrepared()
 554          * The arguments should be in $this->preparedArgs and must not be touched
 555          * while we're doing this.
 556          *
 557          * @param array $matches
 558          * @return string
 559          * @access private
 560          */
 561         function fillPreparedArg( $matches ) {
 562                 switch( $matches[1] ) {
 563                         case '\\?': return '?';
 564                         case '\\!': return '!';
 565                         case '\\&': return '&';
 566                 }
 567                 list( $n, $arg ) = each( $this->preparedArgs );
 568                 switch( $matches[1] ) {
 569                         case '?': return $this->addQuotes( $arg );
 570                         case '!': return $arg;
 571                         case '&':
 572                                 # return $this->addQuotes( file_get_contents( $arg ) );
 573                                 wfDebugDieBacktrace( '& mode is not implemented. If it\'s really needed, uncomment the line above.' );
 574                         default:
 575                                 wfDebugDieBacktrace( 'Received invalid match. This should never happen!' );
 576                 }
 577         }
 578
 579         /**#@+
 580          * @param mixed $res A SQL result
 581          */
 582         /**
 583          * Free a result object
 584          */
 585         function freeResult( $res ) {
 586                 if ( !@/**/mysql_free_result( $res ) ) {
 587                         wfDebugDieBacktrace( "Unable to free MySQL result\n" );
 588                 }
 589         }
 590
 591         /**
 592          * Fetch the next row from the given result object, in object form
 593          */
 594         function fetchObject( $res ) {
 595                 @/**/$row = mysql_fetch_object( $res );
 596                 if( mysql_errno() ) {
 597                         wfDebugDieBacktrace( 'Error in fetchObject(): ' . htmlspecialchars( mysql_error() ) );
 598                 }
 599                 return $row;
 600         }
 601
 602         /**
 603          * Fetch the next row from the given result object
 604          * Returns an array
 605          */
 606         function fetchRow( $res ) {
 607                 @/**/$row = mysql_fetch_array( $res );
 608                 if (mysql_errno() ) {
 609                         wfDebugDieBacktrace( 'Error in fetchRow(): ' . htmlspecialchars( mysql_error() ) );
 610                 }
 611                 return $row;
 612         }
 613
 614         /**
 615          * Get the number of rows in a result object
 616          */
 617         function numRows( $res ) {
 618                 @/**/$n = mysql_num_rows( $res );
 619                 if( mysql_errno() ) {
 620                         wfDebugDieBacktrace( 'Error in numRows(): ' . htmlspecialchars( mysql_error() ) );
 621                 }
 622                 return $n;
 623         }
 624
 625         /**
 626          * Get the number of fields in a result object
 627          * See documentation for mysql_num_fields()
 628          */
 629         function numFields( $res ) { return mysql_num_fields( $res ); }
 630
 631         /**
 632          * Get a field name in a result object
 633          * See documentation for mysql_field_name()
 634          */
 635         function fieldName( $res, $n ) { return mysql_field_name( $res, $n ); }
 636
 637         /**
 638          * Get the inserted value of an auto-increment row
 639          *
 640          * The value inserted should be fetched from nextSequenceValue()
 641          *
 642          * Example:
 643          * $id = $dbw->nextSequenceValue('page_page_id_seq');
 644          * $dbw->insert('page',array('page_id' => $id));
 645          * $id = $dbw->insertId();
 646          */
 647         function insertId() { return mysql_insert_id( $this->mConn ); }
 648
 649         /**
 650          * Change the position of the cursor in a result object
 651          * See mysql_data_seek()
 652          */
 653         function dataSeek( $res, $row ) { return mysql_data_seek( $res, $row ); }
 654
 655         /**
 656          * Get the last error number
 657          * See mysql_errno()
 658          */
 659         function lastErrno() {
 660                 if ( $this->mConn ) {
 661                         return mysql_errno( $this->mConn );
 662                 } else {
 663                         return mysql_errno();
 664                 }
 665         }
 666
 667         /**
 668          * Get a description of the last error
 669          * See mysql_error() for more details
 670          */
 671         function lastError() {
 672                 if ( $this->mConn ) {
 673                         # Even if it's non-zero, it can still be invalid
 674                         wfSuppressWarnings();
 675                         $error = mysql_error( $this->mConn );
 676                         if ( !$error ) {
 677                                 $error = mysql_error();
 678                         }
 679                         wfRestoreWarnings();
 680                 } else {
 681                         $error = mysql_error();
 682                 }
 683                 if( $error ) {
 684                         $error .= ' (' . $this->mServer . ')';
 685                 }
 686                 return $error;
 687         }
 688         /**
 689          * Get the number of rows affected by the last write query
 690          * See mysql_affected_rows() for more details
 691          */
 692         function affectedRows() { return mysql_affected_rows( $this->mConn ); }
 693         /**#@-*/ // end of template : @param $result
 694
 695         /**
 696          * Simple UPDATE wrapper
 697          * Usually aborts on failure
 698          * If errors are explicitly ignored, returns success
 699          *
 700          * This function exists for historical reasons, Database::update() has a more standard
 701          * calling convention and feature set
 702          */
 703         function set( $table, $var, $value, $cond, $fname = 'Database::set' )
 704         {
 705                 $table = $this->tableName( $table );
 706                 $sql = "UPDATE $table SET $var = '" .
 707                   $this->strencode( $value ) . "' WHERE ($cond)";
 708                 return (bool)$this->query( $sql, DB_MASTER, $fname );
 709         }
 710
 711         /**
 712          * Simple SELECT wrapper, returns a single field, input must be encoded
 713          * Usually aborts on failure
 714          * If errors are explicitly ignored, returns FALSE on failure
 715          */
 716         function selectField( $table, $var, $cond='', $fname = 'Database::selectField', $options = array() ) {
 717                 if ( !is_array( $options ) ) {
 718                         $options = array( $options );
 719                 }
 720                 $options['LIMIT'] = 1;
 721
 722                 $res = $this->select( $table, $var, $cond, $fname, $options );
 723                 if ( $res === false || !$this->numRows( $res ) ) {
 724                         return false;
 725                 }
 726                 $row = $this->fetchRow( $res );
 727                 if ( $row !== false ) {
 728                         $this->freeResult( $res );
 729                         return $row[0];
 730                 } else {
 731                         return false;
 732                 }
 733         }
 734
 735         /**
 736          * Returns an optional USE INDEX clause to go after the table, and a
 737          * string to go at the end of the query
 738          *
 739          * @access private
 740          *
 741          * @param array $options an associative array of options to be turned into
 742          *              an SQL query, valid keys are listed in the function.
 743          * @return array
 744          */
 745         function makeSelectOptions( $options ) {
 746                 $tailOpts = '';
 747
 748                 if ( isset( $options['GROUP BY'] ) ) {
 749                         $tailOpts .= " GROUP BY {$options['GROUP BY']}";
 750                 }
 751                 if ( isset( $options['ORDER BY'] ) ) {
 752                         $tailOpts .= " ORDER BY {$options['ORDER BY']}";
 753                 }
 754                 if (isset($options['LIMIT'])) {
 755                         $tailOpts .= $this->limitResult('', $options['LIMIT'],
 756                                 isset($options['OFFSET']) ? $options['OFFSET'] : false);
 757                 }
 758                 if ( is_numeric( array_search( 'FOR UPDATE', $options ) ) ) {
 759                         $tailOpts .= ' FOR UPDATE';
 760                 }
 761
 762                 if ( is_numeric( array_search( 'LOCK IN SHARE MODE', $options ) ) ) {
 763                         $tailOpts .= ' LOCK IN SHARE MODE';
 764                 }
 765
 766                 if ( isset( $options['USE INDEX'] ) && ! is_array( $options['USE INDEX'] ) ) {
 767                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
 768                 } else {
 769                         $useIndex = '';
 770                 }
 771                 return array( $useIndex, $tailOpts );
 772         }
 773
 774         /**
 775          * SELECT wrapper
 776          */
 777         function select( $table, $vars, $conds='', $fname = 'Database::select', $options = array() )
 778         {
 779                 if( is_array( $vars ) ) {
 780                         $vars = implode( ',', $vars );
 781                 }
 782                 if( !is_array( $options ) ) {
 783                         $options = array( $options );
 784                 }
 785                 if( is_array( $table ) ) {
 786                         if ( @is_array( $options['USE INDEX'] ) )
 787                                 $from = ' FROM ' . $this->tableNamesWithUseIndex( $table, $options['USE INDEX'] );
 788                         else
 789                                 $from = ' FROM ' . implode( ',', array_map( array( &$this, 'tableName' ), $table ) );
 790                 } elseif ($table!='') {
 791                         $from = ' FROM ' . $this->tableName( $table );
 792                 } else {
 793                         $from = '';
 794                 }
 795
 796                 list( $useIndex, $tailOpts ) = $this->makeSelectOptions( $options );
 797
 798                 if( !empty( $conds ) ) {
 799                         if ( is_array( $conds ) ) {
 800                                 $conds = $this->makeList( $conds, LIST_AND );
 801                         }
 802                         $sql = "SELECT $vars $from $useIndex WHERE $conds $tailOpts";
 803                 } else {
 804                         $sql = "SELECT $vars $from $useIndex $tailOpts";
 805                 }
 806
 807                 return $this->query( $sql, $fname );
 808         }
 809
 810         /**
 811          * Single row SELECT wrapper
 812          * Aborts or returns FALSE on error
 813          *
 814          * $vars: the selected variables
 815          * $conds: a condition map, terms are ANDed together.
 816          *   Items with numeric keys are taken to be literal conditions
 817          * Takes an array of selected variables, and a condition map, which is ANDed
 818          * e.g: selectRow( "page", array( "page_id" ), array( "page_namespace" =>
 819          * NS_MAIN, "page_title" => "Astronomy" ) )   would return an object where
 820          * $obj- >page_id is the ID of the Astronomy article
 821          *
 822          * @todo migrate documentation to phpdocumentor format
 823          */
 824         function selectRow( $table, $vars, $conds, $fname = 'Database::selectRow', $options = array() ) {
 825                 $options['LIMIT'] = 1;
 826                 $res = $this->select( $table, $vars, $conds, $fname, $options );
 827                 if ( $res === false )
 828                         return false;
 829                 if ( !$this->numRows($res) ) {
 830                         $this->freeResult($res);
 831                         return false;
 832                 }
 833                 $obj = $this->fetchObject( $res );
 834                 $this->freeResult( $res );
 835                 return $obj;
 836
 837         }
 838
 839         /**
 840          * Removes most variables from an SQL query and replaces them with X or N for numbers.
 841          * It's only slightly flawed. Don't use for anything important.
 842          *
 843          * @param string $sql A SQL Query
 844          * @static
 845          */
 846         function generalizeSQL( $sql ) {
 847                 # This does the same as the regexp below would do, but in such a way
 848                 # as to avoid crashing php on some large strings.
 849                 # $sql = preg_replace ( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql);
 850
 851                 $sql = str_replace ( "\\\\", '', $sql);
 852                 $sql = str_replace ( "\\'", '', $sql);
 853                 $sql = str_replace ( "\\\"", '', $sql);
 854                 $sql = preg_replace ("/'.*'/s", "'X'", $sql);
 855                 $sql = preg_replace ('/".*"/s', "'X'", $sql);
 856
 857                 # All newlines, tabs, etc replaced by single space
 858                 $sql = preg_replace ( "/\s+/", ' ', $sql);
 859
 860                 # All numbers => N
 861                 $sql = preg_replace ('/-?[0-9]+/s', 'N', $sql);
 862
 863                 return $sql;
 864         }
 865
 866         /**
 867          * Determines whether a field exists in a table
 868          * Usually aborts on failure
 869          * If errors are explicitly ignored, returns NULL on failure
 870          */
 871         function fieldExists( $table, $field, $fname = 'Database::fieldExists' ) {
 872                 $table = $this->tableName( $table );
 873                 $res = $this->query( 'DESCRIBE '.$table, DB_SLAVE, $fname );
 874                 if ( !$res ) {
 875                         return NULL;
 876                 }
 877
 878                 $found = false;
 879
 880                 while ( $row = $this->fetchObject( $res ) ) {
 881                         if ( $row->Field == $field ) {
 882                                 $found = true;
 883                                 break;
 884                         }
 885                 }
 886                 return $found;
 887         }
 888
 889         /**
 890          * Determines whether an index exists
 891          * Usually aborts on failure
 892          * If errors are explicitly ignored, returns NULL on failure
 893          */
 894         function indexExists( $table, $index, $fname = 'Database::indexExists' ) {
 895                 $info = $this->indexInfo( $table, $index, $fname );
 896                 if ( is_null( $info ) ) {
 897                         return NULL;
 898                 } else {
 899                         return $info !== false;
 900                 }
 901         }
 902
 903
 904         /**
 905          * Get information about an index into an object
 906          * Returns false if the index does not exist
 907          */
 908         function indexInfo( $table, $index, $fname = 'Database::indexInfo' ) {
 909                 # SHOW INDEX works in MySQL 3.23.58, but SHOW INDEXES does not.
 910                 # SHOW INDEX should work for 3.x and up:
 911                 # http://dev.mysql.com/doc/mysql/en/SHOW_INDEX.html
 912                 $table = $this->tableName( $table );
 913                 $sql = 'SHOW INDEX FROM '.$table;
 914                 $res = $this->query( $sql, $fname );
 915                 if ( !$res ) {
 916                         return NULL;
 917                 }
 918
 919                 while ( $row = $this->fetchObject( $res ) ) {
 920                         if ( $row->Key_name == $index ) {
 921                                 return $row;
 922                         }
 923                 }
 924                 return false;
 925         }
 926
 927         /**
 928          * Query whether a given table exists
 929          */
 930         function tableExists( $table ) {
 931                 $table = $this->tableName( $table );
 932                 $old = $this->ignoreErrors( true );
 933                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1" );
 934                 $this->ignoreErrors( $old );
 935                 if( $res ) {
 936                         $this->freeResult( $res );
 937                         return true;
 938                 } else {
 939                         return false;
 940                 }
 941         }
 942
 943         /**
 944          * mysql_fetch_field() wrapper
 945          * Returns false if the field doesn't exist
 946          *
 947          * @param $table
 948          * @param $field
 949          */
 950         function fieldInfo( $table, $field ) {
 951                 $table = $this->tableName( $table );
 952                 $res = $this->query( "SELECT * FROM $table LIMIT 1" );
 953                 $n = mysql_num_fields( $res );
 954                 for( $i = 0; $i < $n; $i++ ) {
 955                         $meta = mysql_fetch_field( $res, $i );
 956                         if( $field == $meta->name ) {
 957                                 return $meta;
 958                         }
 959                 }
 960                 return false;
 961         }
 962
 963         /**
 964          * mysql_field_type() wrapper
 965          */
 966         function fieldType( $res, $index ) {
 967                 return mysql_field_type( $res, $index );
 968         }
 969
 970         /**
 971          * Determines if a given index is unique
 972          */
 973         function indexUnique( $table, $index ) {
 974                 $indexInfo = $this->indexInfo( $table, $index );
 975                 if ( !$indexInfo ) {
 976                         return NULL;
 977                 }
 978                 return !$indexInfo->Non_unique;
 979         }
 980
 981         /**
 982          * INSERT wrapper, inserts an array into a table
 983          *
 984          * $a may be a single associative array, or an array of these with numeric keys, for
 985          * multi-row insert.
 986          *
 987          * Usually aborts on failure
 988          * If errors are explicitly ignored, returns success
 989          */
 990         function insert( $table, $a, $fname = 'Database::insert', $options = array() ) {
 991                 # No rows to insert, easy just return now
 992                 if ( !count( $a ) ) {
 993                         return true;
 994                 }
 995
 996                 $table = $this->tableName( $table );
 997                 if ( !is_array( $options ) ) {
 998                         $options = array( $options );
 999                 }
1000                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1001                         $multi = true;
1002                         $keys = array_keys( $a[0] );
1003                 } else {
1004                         $multi = false;
1005                         $keys = array_keys( $a );
1006                 }
1007
1008                 $sql = 'INSERT ' . implode( ' ', $options ) .
1009                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1010
1011                 if ( $multi ) {
1012                         $first = true;
1013                         foreach ( $a as $row ) {
1014                                 if ( $first ) {
1015                                         $first = false;
1016                                 } else {
1017                                         $sql .= ',';
1018                                 }
1019                                 $sql .= '(' . $this->makeList( $row ) . ')';
1020                         }
1021                 } else {
1022                         $sql .= '(' . $this->makeList( $a ) . ')';
1023                 }
1024                 return (bool)$this->query( $sql, $fname );
1025         }
1026
1027         /**
1028          * Make UPDATE options for the Database::update function
1029          *
1030          * @access private
1031          * @param array $options The options passed to Database::update
1032          * @return string
1033          */
1034         function makeUpdateOptions( $options ) {
1035                 if( !is_array( $options ) ) {
1036                         $options = array( $options );
1037                 }
1038                 $opts = array();
1039                 if ( in_array( 'LOW_PRIORITY', $options ) )
1040                         $opts[] = $this->lowPriorityOption();
1041                 if ( in_array( 'IGNORE', $options ) )
1042                         $opts[] = 'IGNORE';
1043                 return implode(' ', $opts);
1044         }
1045
1046         /**
1047          * UPDATE wrapper, takes a condition array and a SET array
1048          *
1049          * @param string $table  The table to UPDATE
1050          * @param array  $values An array of values to SET
1051          * @param array  $conds  An array of conditions (WHERE)
1052          * @param string $fname  The Class::Function calling this function
1053          *                       (for the log)
1054          * @param array  $options An array of UPDATE options, can be one or
1055          *                        more of IGNORE, LOW_PRIORITY
1056          */
1057         function update( $table, $values, $conds, $fname = 'Database::update', $options = array() ) {
1058                 $table = $this->tableName( $table );
1059                 $opts = $this->makeUpdateOptions( $options );
1060                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1061                 if ( $conds != '*' ) {
1062                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1063                 }
1064                 $this->query( $sql, $fname );
1065         }
1066
1067         /**
1068          * Makes a wfStrencoded list from an array
1069          * $mode: LIST_COMMA         - comma separated, no field names
1070          *        LIST_AND           - ANDed WHERE clause (without the WHERE)
1071          *        LIST_SET           - comma separated with field names, like a SET clause
1072          *        LIST_NAMES         - comma separated field names
1073          */
1074         function makeList( $a, $mode = LIST_COMMA ) {
1075                 if ( !is_array( $a ) ) {
1076                         wfDebugDieBacktrace( 'Database::makeList called with incorrect parameters' );
1077                 }
1078
1079                 $first = true;
1080                 $list = '';
1081                 foreach ( $a as $field => $value ) {
1082                         if ( !$first ) {
1083                                 if ( $mode == LIST_AND ) {
1084                                         $list .= ' AND ';
1085                                 } elseif($mode == LIST_OR) {
1086                                         $list .= ' OR ';
1087                                 } else {
1088                                         $list .= ',';
1089                                 }
1090                         } else {
1091                                 $first = false;
1092                         }
1093                         if ( ($mode == LIST_AND || $mode == LIST_OR) && is_numeric( $field ) ) {
1094                                 $list .= "($value)";
1095                         } elseif ( $mode == LIST_AND && is_array ($value) ) {
1096                                 $list .= $field." IN (".$this->makeList($value).") ";
1097                         } else {
1098                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
1099                                         $list .= "$field = ";
1100                                 }
1101                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
1102                         }
1103                 }
1104                 return $list;
1105         }
1106
1107         /**
1108          * Change the current database
1109          */
1110         function selectDB( $db ) {
1111                 $this->mDBname = $db;
1112                 return mysql_select_db( $db, $this->mConn );
1113         }
1114
1115         /**
1116          * Starts a timer which will kill the DB thread after $timeout seconds
1117          */
1118         function startTimer( $timeout ) {
1119                 global $IP;
1120                 if( function_exists( 'mysql_thread_id' ) ) {
1121                         # This will kill the query if it's still running after $timeout seconds.
1122                         $tid = mysql_thread_id( $this->mConn );
1123                         exec( "php $IP/includes/killthread.php $timeout $tid &>/dev/null &" );
1124                 }
1125         }
1126
1127         /**
1128          * Stop a timer started by startTimer()
1129          * Currently unimplemented.
1130          *
1131          */
1132         function stopTimer() { }
1133
1134         /**
1135          * Format a table name ready for use in constructing an SQL query
1136          *
1137          * This does two important things: it quotes table names which as necessary,
1138          * and it adds a table prefix if there is one.
1139          *
1140          * All functions of this object which require a table name call this function
1141          * themselves. Pass the canonical name to such functions. This is only needed
1142          * when calling query() directly.
1143          *
1144          * @param string $name database table name
1145          */
1146         function tableName( $name ) {
1147                 global $wgSharedDB;
1148                 # Skip quoted literals
1149                 if ( $name{0} != '`' ) {
1150                         if ( $this->mTablePrefix !== '' &&  strpos( '.', $name ) === false ) {
1151                                 $name = "{$this->mTablePrefix}$name";
1152                         }
1153                         if ( isset( $wgSharedDB ) && "{$this->mTablePrefix}user" == $name ) {
1154                                 $name = "`$wgSharedDB`.`$name`";
1155                         } else {
1156                                 # Standard quoting
1157                                 $name = "`$name`";
1158                         }
1159                 }
1160                 return $name;
1161         }
1162
1163         /**
1164          * Fetch a number of table names into an array
1165          * This is handy when you need to construct SQL for joins
1166          *
1167          * Example:
1168          * extract($dbr->tableNames('user','watchlist'));
1169          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1170          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1171          */
1172         function tableNames() {
1173                 $inArray = func_get_args();
1174                 $retVal = array();
1175                 foreach ( $inArray as $name ) {
1176                         $retVal[$name] = $this->tableName( $name );
1177                 }
1178                 return $retVal;
1179         }
1180
1181         /**
1182          * @access private
1183          */
1184         function tableNamesWithUseIndex( $tables, $use_index ) {
1185                 $ret = array();
1186
1187                 foreach ( $tables as $table )
1188                         if ( @$use_index[$table] !== null )
1189                                 $ret[] = $this->tableName( $table ) . ' ' . $this->useIndexClause( implode( ',', (array)$use_index[$table] ) );
1190                         else
1191                                 $ret[] = $this->tableName( $table );
1192
1193                 return implode( ',', $ret );
1194         }
1195
1196         /**
1197          * Wrapper for addslashes()
1198          * @param string $s String to be slashed.
1199          * @return string slashed string.
1200          */
1201         function strencode( $s ) {
1202                 return addslashes( $s );
1203         }
1204
1205         /**
1206          * If it's a string, adds quotes and backslashes
1207          * Otherwise returns as-is
1208          */
1209         function addQuotes( $s ) {
1210                 if ( is_null( $s ) ) {
1211                         return 'NULL';
1212                 } else {
1213                         # This will also quote numeric values. This should be harmless,
1214                         # and protects against weird problems that occur when they really
1215                         # _are_ strings such as article titles and string->number->string
1216                         # conversion is not 1:1.
1217                         return "'" . $this->strencode( $s ) . "'";
1218                 }
1219         }
1220
1221         /**
1222          * Escape string for safe LIKE usage
1223          */
1224         function escapeLike( $s ) {
1225                 $s=$this->strencode( $s );
1226                 $s=str_replace(array('%','_'),array('\%','\_'),$s);
1227                 return $s;
1228         }
1229
1230         /**
1231          * Returns an appropriately quoted sequence value for inserting a new row.
1232          * MySQL has autoincrement fields, so this is just NULL. But the PostgreSQL
1233          * subclass will return an integer, and save the value for insertId()
1234          */
1235         function nextSequenceValue( $seqName ) {
1236                 return NULL;
1237         }
1238
1239         /**
1240          * USE INDEX clause
1241          * PostgreSQL doesn't have them and returns ""
1242          */
1243         function useIndexClause( $index ) {
1244                 return "FORCE INDEX ($index)";
1245         }
1246
1247         /**
1248          * REPLACE query wrapper
1249          * PostgreSQL simulates this with a DELETE followed by INSERT
1250          * $row is the row to insert, an associative array
1251          * $uniqueIndexes is an array of indexes. Each element may be either a
1252          * field name or an array of field names
1253          *
1254          * It may be more efficient to leave off unique indexes which are unlikely to collide.
1255          * However if you do this, you run the risk of encountering errors which wouldn't have
1256          * occurred in MySQL
1257          *
1258          * @todo migrate comment to phodocumentor format
1259          */
1260         function replace( $table, $uniqueIndexes, $rows, $fname = 'Database::replace' ) {
1261                 $table = $this->tableName( $table );
1262
1263                 # Single row case
1264                 if ( !is_array( reset( $rows ) ) ) {
1265                         $rows = array( $rows );
1266                 }
1267
1268                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) .') VALUES ';
1269                 $first = true;
1270                 foreach ( $rows as $row ) {
1271                         if ( $first ) {
1272                                 $first = false;
1273                         } else {
1274                                 $sql .= ',';
1275                         }
1276                         $sql .= '(' . $this->makeList( $row ) . ')';
1277                 }
1278                 return $this->query( $sql, $fname );
1279         }
1280
1281         /**
1282          * DELETE where the condition is a join
1283          * MySQL does this with a multi-table DELETE syntax, PostgreSQL does it with sub-selects
1284          *
1285          * For safety, an empty $conds will not delete everything. If you want to delete all rows where the
1286          * join condition matches, set $conds='*'
1287          *
1288          * DO NOT put the join condition in $conds
1289          *
1290          * @param string $delTable The table to delete from.
1291          * @param string $joinTable The other table.
1292          * @param string $delVar The variable to join on, in the first table.
1293          * @param string $joinVar The variable to join on, in the second table.
1294          * @param array $conds Condition array of field names mapped to variables, ANDed together in the WHERE clause
1295          */
1296         function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds, $fname = 'Database::deleteJoin' ) {
1297                 if ( !$conds ) {
1298                         wfDebugDieBacktrace( 'Database::deleteJoin() called with empty $conds' );
1299                 }
1300
1301                 $delTable = $this->tableName( $delTable );
1302                 $joinTable = $this->tableName( $joinTable );
1303                 $sql = "DELETE $delTable FROM $delTable, $joinTable WHERE $delVar=$joinVar ";
1304                 if ( $conds != '*' ) {
1305                         $sql .= ' AND ' . $this->makeList( $conds, LIST_AND );
1306                 }
1307
1308                 return $this->query( $sql, $fname );
1309         }
1310
1311         /**
1312          * Returns the size of a text field, or -1 for "unlimited"
1313          */
1314         function textFieldSize( $table, $field ) {
1315                 $table = $this->tableName( $table );
1316                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
1317                 $res = $this->query( $sql, 'Database::textFieldSize' );
1318                 $row = $this->fetchObject( $res );
1319                 $this->freeResult( $res );
1320
1321                 if ( preg_match( "/\((.*)\)/", $row->Type, $m ) ) {
1322                         $size = $m[1];
1323                 } else {
1324                         $size = -1;
1325                 }
1326                 return $size;
1327         }
1328
1329         /**
1330          * @return string Returns the text of the low priority option if it is supported, or a blank string otherwise
1331          */
1332         function lowPriorityOption() {
1333                 return 'LOW_PRIORITY';
1334         }
1335
1336         /**
1337          * DELETE query wrapper
1338          *
1339          * Use $conds == "*" to delete all rows
1340          */
1341         function delete( $table, $conds, $fname = 'Database::delete' ) {
1342                 if ( !$conds ) {
1343                         wfDebugDieBacktrace( 'Database::delete() called with no conditions' );
1344                 }
1345                 $table = $this->tableName( $table );
1346                 $sql = "DELETE FROM $table";
1347                 if ( $conds != '*' ) {
1348                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1349                 }
1350                 return $this->query( $sql, $fname );
1351         }
1352
1353         /**
1354          * INSERT SELECT wrapper
1355          * $varMap must be an associative array of the form array( 'dest1' => 'source1', ...)
1356          * Source items may be literals rather than field names, but strings should be quoted with Database::addQuotes()
1357          * $conds may be "*" to copy the whole table
1358          * srcTable may be an array of tables.
1359          */
1360         function insertSelect( $destTable, $srcTable, $varMap, $conds, $fname = 'Database::insertSelect' ) {
1361                 $destTable = $this->tableName( $destTable );
1362                 if( is_array( $srcTable ) ) {
1363                         $srcTable =  implode( ',', array_map( array( &$this, 'tableName' ), $srcTable ) );
1364                 } else {
1365                         $srcTable = $this->tableName( $srcTable );
1366                 }
1367                 $sql = "INSERT INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
1368                         ' SELECT ' . implode( ',', $varMap ) .
1369                         " FROM $srcTable";
1370                 if ( $conds != '*' ) {
1371                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1372                 }
1373                 return $this->query( $sql, $fname );
1374         }
1375
1376         /**
1377          * Construct a LIMIT query with optional offset
1378          * This is used for query pages
1379          * $sql string SQL query we will append the limit too
1380          * $limit integer the SQL limit
1381          * $offset integer the SQL offset (default false)
1382          */
1383         function limitResult($sql, $limit, $offset=false) {
1384                 return " $sql LIMIT ".((is_numeric($offset) && $offset != 0)?"{$offset},":"")."{$limit} ";
1385         }
1386         function limitResultForUpdate($sql, $num) {
1387                 return $this->limitResult($sql, $num, 0);
1388         }
1389
1390         /**
1391          * Returns an SQL expression for a simple conditional.
1392          * Uses IF on MySQL.
1393          *
1394          * @param string $cond SQL expression which will result in a boolean value
1395          * @param string $trueVal SQL expression to return if true
1396          * @param string $falseVal SQL expression to return if false
1397          * @return string SQL fragment
1398          */
1399         function conditional( $cond, $trueVal, $falseVal ) {
1400                 return " IF($cond, $trueVal, $falseVal) ";
1401         }
1402
1403         /**
1404          * Determines if the last failure was due to a deadlock
1405          */
1406         function wasDeadlock() {
1407                 return $this->lastErrno() == 1213;
1408         }
1409
1410         /**
1411          * Perform a deadlock-prone transaction.
1412          *
1413          * This function invokes a callback function to perform a set of write
1414          * queries. If a deadlock occurs during the processing, the transaction
1415          * will be rolled back and the callback function will be called again.
1416          *
1417          * Usage:
1418          *   $dbw->deadlockLoop( callback, ... );
1419          *
1420          * Extra arguments are passed through to the specified callback function.
1421          *
1422          * Returns whatever the callback function returned on its successful,
1423          * iteration, or false on error, for example if the retry limit was
1424          * reached.
1425          */
1426         function deadlockLoop() {
1427                 $myFname = 'Database::deadlockLoop';
1428
1429                 $this->begin();
1430                 $args = func_get_args();
1431                 $function = array_shift( $args );
1432                 $oldIgnore = $this->ignoreErrors( true );
1433                 $tries = DEADLOCK_TRIES;
1434                 if ( is_array( $function ) ) {
1435                         $fname = $function[0];
1436                 } else {
1437                         $fname = $function;
1438                 }
1439                 do {
1440                         $retVal = call_user_func_array( $function, $args );
1441                         $error = $this->lastError();
1442                         $errno = $this->lastErrno();
1443                         $sql = $this->lastQuery();
1444
1445                         if ( $errno ) {
1446                                 if ( $this->wasDeadlock() ) {
1447                                         # Retry
1448                                         usleep( mt_rand( DEADLOCK_DELAY_MIN, DEADLOCK_DELAY_MAX ) );
1449                                 } else {
1450                                         $this->reportQueryError( $error, $errno, $sql, $fname );
1451                                 }
1452                         }
1453                 } while( $this->wasDeadlock() && --$tries > 0 );
1454                 $this->ignoreErrors( $oldIgnore );
1455                 if ( $tries <= 0 ) {
1456                         $this->query( 'ROLLBACK', $myFname );
1457                         $this->reportQueryError( $error, $errno, $sql, $fname );
1458                         return false;
1459                 } else {
1460                         $this->query( 'COMMIT', $myFname );
1461                         return $retVal;
1462                 }
1463         }
1464
1465         /**
1466          * Do a SELECT MASTER_POS_WAIT()
1467          *
1468          * @param string $file the binlog file
1469          * @param string $pos the binlog position
1470          * @param integer $timeout the maximum number of seconds to wait for synchronisation
1471          */
1472         function masterPosWait( $file, $pos, $timeout ) {
1473                 $fname = 'Database::masterPosWait';
1474                 wfProfileIn( $fname );
1475
1476
1477                 # Commit any open transactions
1478                 $this->immediateCommit();
1479
1480                 # Call doQuery() directly, to avoid opening a transaction if DBO_TRX is set
1481                 $encFile = $this->strencode( $file );
1482                 $sql = "SELECT MASTER_POS_WAIT('$encFile', $pos, $timeout)";
1483                 $res = $this->doQuery( $sql );
1484                 if ( $res && $row = $this->fetchRow( $res ) ) {
1485                         $this->freeResult( $res );
1486                         wfProfileOut( $fname );
1487                         return $row[0];
1488                 } else {
1489                         wfProfileOut( $fname );
1490                         return false;
1491                 }
1492         }
1493
1494         /**
1495          * Get the position of the master from SHOW SLAVE STATUS
1496          */
1497         function getSlavePos() {
1498                 $res = $this->query( 'SHOW SLAVE STATUS', 'Database::getSlavePos' );
1499                 $row = $this->fetchObject( $res );
1500                 if ( $row ) {
1501                         return array( $row->Master_Log_File, $row->Read_Master_Log_Pos );
1502                 } else {
1503                         return array( false, false );
1504                 }
1505         }
1506
1507         /**
1508          * Get the position of the master from SHOW MASTER STATUS
1509          */
1510         function getMasterPos() {
1511                 $res = $this->query( 'SHOW MASTER STATUS', 'Database::getMasterPos' );
1512                 $row = $this->fetchObject( $res );
1513                 if ( $row ) {
1514                         return array( $row->File, $row->Position );
1515                 } else {
1516                         return array( false, false );
1517                 }
1518         }
1519
1520         /**
1521          * Begin a transaction, or if a transaction has already started, continue it
1522          */
1523         function begin( $fname = 'Database::begin' ) {
1524                 if ( !$this->mTrxLevel ) {
1525                         $this->immediateBegin( $fname );
1526                 } else {
1527                         $this->mTrxLevel++;
1528                 }
1529         }
1530
1531         /**
1532          * End a transaction, or decrement the nest level if transactions are nested
1533          */
1534         function commit( $fname = 'Database::commit' ) {
1535                 if ( $this->mTrxLevel ) {
1536                         $this->mTrxLevel--;
1537                 }
1538                 if ( !$this->mTrxLevel ) {
1539                         $this->immediateCommit( $fname );
1540                 }
1541         }
1542
1543         /**
1544          * Rollback a transaction
1545          */
1546         function rollback( $fname = 'Database::rollback' ) {
1547                 $this->query( 'ROLLBACK', $fname );
1548                 $this->mTrxLevel = 0;
1549         }
1550
1551         /**
1552          * Begin a transaction, committing any previously open transaction
1553          */
1554         function immediateBegin( $fname = 'Database::immediateBegin' ) {
1555                 $this->query( 'BEGIN', $fname );
1556                 $this->mTrxLevel = 1;
1557         }
1558
1559         /**
1560          * Commit transaction, if one is open
1561          */
1562         function immediateCommit( $fname = 'Database::immediateCommit' ) {
1563                 $this->query( 'COMMIT', $fname );
1564                 $this->mTrxLevel = 0;
1565         }
1566
1567         /**
1568          * Return MW-style timestamp used for MySQL schema
1569          */
1570         function timestamp( $ts=0 ) {
1571                 return wfTimestamp(TS_MW,$ts);
1572         }
1573
1574         /**
1575          * Local database timestamp format or null
1576          */
1577         function timestampOrNull( $ts = null ) {
1578                 if( is_null( $ts ) ) {
1579                         return null;
1580                 } else {
1581                         return $this->timestamp( $ts );
1582                 }
1583         }
1584
1585         /**
1586          * @todo document
1587          */
1588         function resultObject( $result ) {
1589                 if( empty( $result ) ) {
1590                         return NULL;
1591                 } else {
1592                         return new ResultWrapper( $this, $result );
1593                 }
1594         }
1595
1596         /**
1597          * Return aggregated value alias
1598          */
1599         function aggregateValue ($valuedata,$valuename='value') {
1600                 return $valuename;
1601         }
1602
1603         /**
1604          * @return string wikitext of a link to the server software's web site
1605          */
1606         function getSoftwareLink() {
1607                 return "[http://www.mysql.com/ MySQL]";
1608         }
1609
1610         /**
1611          * @return string Version information from the database
1612          */
1613         function getServerVersion() {
1614                 return mysql_get_server_info();
1615         }
1616
1617         /**
1618          * Ping the server and try to reconnect if it there is no connection
1619          */
1620         function ping() {
1621                 if( function_exists( 'mysql_ping' ) ) {
1622                         return mysql_ping( $this->mConn );
1623                 } else {
1624                         wfDebug( "Tried to call mysql_ping but this is ancient PHP version. Faking it!\n" );
1625                         return true;
1626                 }
1627         }
1628
1629         /**
1630          * Get slave lag.
1631          * At the moment, this will only work if the DB user has the PROCESS privilege
1632          */
1633         function getLag() {
1634                 $res = $this->query( 'SHOW PROCESSLIST' );
1635                 # Find slave SQL thread. Assumed to be the second one running, which is a bit
1636                 # dubious, but unfortunately there's no easy rigorous way
1637                 $slaveThreads = 0;
1638                 while ( $row = $this->fetchObject( $res ) ) {
1639                         if ( $row->User == 'system user' ) {
1640                                 if ( ++$slaveThreads == 2 ) {
1641                                         # This is it, return the time (except -ve)
1642                                         if ( $row->Time > 1>>31 ) {
1643                                                 return 0;
1644                                         } else {
1645                                                 return $row->Time;
1646                                         }
1647                                 }
1648                         }
1649                 }
1650                 return false;
1651         }
1652
1653         /**
1654          * Get status information from SHOW STATUS in an associative array
1655          */
1656         function getStatus($which="%") {
1657                 $res = $this->query( "SHOW STATUS LIKE '{$which}'" );
1658                 $status = array();
1659                 while ( $row = $this->fetchObject( $res ) ) {
1660                         $status[$row->Variable_name] = $row->Value;
1661                 }
1662                 return $status;
1663         }
1664
1665         /**
1666          * Return the maximum number of items allowed in a list, or 0 for unlimited.
1667          */
1668         function maxListLen() {
1669                 return 0;
1670         }
1671
1672         function encodeBlob($b) {
1673                 return $b;
1674         }
1675 }
1676
1677 /**
1678  * Database abstraction object for mySQL
1679  * Inherit all methods and properties of Database::Database()
1680  *
1681  * @package MediaWiki
1682  * @see Database
1683  */
1684 class DatabaseMysql extends Database {
1685         # Inherit all
1686 }
1687
1688
1689 /**
1690  * Result wrapper for grabbing data queried by someone else
1691  *
1692  * @package MediaWiki
1693  */
1694 class ResultWrapper {
1695         var $db, $result;
1696
1697         /**
1698          * @todo document
1699          */
1700         function ResultWrapper( &$database, $result ) {
1701                 $this->db =& $database;
1702                 $this->result =& $result;
1703         }
1704
1705         /**
1706          * @todo document
1707          */
1708         function numRows() {
1709                 return $this->db->numRows( $this->result );
1710         }
1711
1712         /**
1713          * @todo document
1714          */
1715         function fetchObject() {
1716                 return $this->db->fetchObject( $this->result );
1717         }
1718
1719         /**
1720          * @todo document
1721          */
1722         function &fetchRow() {
1723                 return $this->db->fetchRow( $this->result );
1724         }
1725
1726         /**
1727          * @todo document
1728          */
1729         function free() {
1730                 $this->db->freeResult( $this->result );
1731                 unset( $this->result );
1732                 unset( $this->db );
1733         }
1734
1735         function seek( $row ) {
1736                 $this->db->dataSeek( $this->result, $row );
1737         }
1738 }
1739
1740 #------------------------------------------------------------------------------
1741 # Global functions
1742 #------------------------------------------------------------------------------
1743
1744 /**
1745  * Standard fail function, called by default when a connection cannot be
1746  * established.
1747  * Displays the file cache if possible
1748  */
1749 function wfEmergencyAbort( &$conn, $error ) {
1750         global $wgTitle, $wgUseFileCache, $title, $wgInputEncoding, $wgOutputEncoding;
1751         global $wgSitename, $wgServer, $wgMessageCache, $wgLogo;
1752
1753         # I give up, Brion is right. Getting the message cache to work when there is no DB is tricky.
1754         # Hard coding strings instead.
1755
1756         $noconnect = "<h1><img src='$wgLogo' style='float:left;margin-right:1em' alt=''>$wgSitename has a problem</h1><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>";
1757         $mainpage = 'Main Page';
1758         $searchdisabled = <<<EOT
1759 <p style="margin: 1.5em 2em 1em">$wgSitename search is disabled for performance reasons. You can search via Google in the meantime.
1760 <span style="font-size: 89%; display: block; margin-left: .2em">Note that their indexes of $wgSitename content may be out of date.</span></p>',
1761 EOT;
1762
1763         $googlesearch = "
1764 <!-- SiteSearch Google -->
1765 <FORM method=GET action=\"http://www.google.com/search\">
1766 <TABLE bgcolor=\"#FFFFFF\"><tr><td>
1767 <A HREF=\"http://www.google.com/\">
1768 <IMG SRC=\"http://www.google.com/logos/Logo_40wht.gif\"
1769 border=\"0\" ALT=\"Google\"></A>
1770 </td>
1771 <td>
1772 <INPUT TYPE=text name=q size=31 maxlength=255 value=\"$1\">
1773 <INPUT type=submit name=btnG VALUE=\"Google Search\">
1774 <font size=-1>
1775 <input type=hidden name=domains value=\"$wgServer\"><br /><input type=radio name=sitesearch value=\"\"> WWW <input type=radio name=sitesearch value=\"$wgServer\" checked> $wgServer <br />
1776 <input type='hidden' name='ie' value='$2'>
1777 <input type='hidden' name='oe' value='$2'>
1778 </font>
1779 </td></tr></TABLE>
1780 </FORM>
1781 <!-- SiteSearch Google -->";
1782         $cachederror = "The following is a cached copy of the requested page, and may not be up to date. ";
1783
1784
1785         if( !headers_sent() ) {
1786                 header( 'HTTP/1.0 500 Internal Server Error' );
1787                 header( 'Content-type: text/html; charset='.$wgOutputEncoding );
1788                 /* Don't cache error pages!  They cause no end of trouble... */
1789                 header( 'Cache-control: none' );
1790                 header( 'Pragma: nocache' );
1791         }
1792
1793         # No database access
1794         if ( is_object( $wgMessageCache ) ) {
1795                 $wgMessageCache->disable();
1796         }
1797
1798         if ( trim( $error ) == '' ) {
1799                 $error = $this->mServer;
1800         }
1801
1802         wfLogDBError( "Connection error: $error\n" );
1803
1804         $text = str_replace( '$1', $error, $noconnect );
1805         $text .= wfGetSiteNotice();
1806
1807         if($wgUseFileCache) {
1808                 if($wgTitle) {
1809                         $t =& $wgTitle;
1810                 } else {
1811                         if($title) {
1812                                 $t = Title::newFromURL( $title );
1813                         } elseif (@/**/$_REQUEST['search']) {
1814                                 $search = $_REQUEST['search'];
1815                                 echo $searchdisabled;
1816                                 echo str_replace( array( '$1', '$2' ), array( htmlspecialchars( $search ),
1817                                   $wgInputEncoding ), $googlesearch );
1818                                 wfErrorExit();
1819                         } else {
1820                                 $t = Title::newFromText( $mainpage );
1821                         }
1822                 }
1823
1824                 $cache = new CacheManager( $t );
1825                 if( $cache->isFileCached() ) {
1826                         $msg = '<p style="color: red"><b>'.$msg."<br />\n" .
1827                                 $cachederror . "</b></p>\n";
1828
1829                         $tag = '<div id="article">';
1830                         $text = str_replace(
1831                                 $tag,
1832                                 $tag . $msg,
1833                                 $cache->fetchPageText() );
1834                 }
1835         }
1836
1837         echo $text;
1838         wfErrorExit();
1839 }
1840
1841 ?>