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                         wfDie( "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;
 363
 364                 if ( $wgProfiling ) {
 365                         # generalizeSQL will probably cut down the query to reasonable
 366                         # logging size most of the time. The substr is really just a sanity check.
 367
 368                         # Who's been wasting my precious column space? -- TS
 369                         #$profName = 'query: ' . $fname . ' ' . substr( Database::generalizeSQL( $sql ), 0, 255 );
 370
 371                         if ( is_null( $this->getLBInfo( 'master' ) ) ) {
 372                                 $queryProf = 'query: ' . substr( Database::generalizeSQL( $sql ), 0, 255 );
 373                                 $totalProf = 'Database::query';
 374                         } else {
 375                                 $queryProf = 'query-m: ' . substr( Database::generalizeSQL( $sql ), 0, 255 );
 376                                 $totalProf = 'Database::query-master';
 377                         }
 378                         wfProfileIn( $totalProf );
 379                         wfProfileIn( $queryProf );
 380                 }
 381
 382                 $this->mLastQuery = $sql;
 383
 384                 # Add a comment for easy SHOW PROCESSLIST interpretation
 385                 if ( $fname ) {
 386                         $commentedSql = preg_replace("/\s/", " /* $fname */ ", $sql, 1);
 387                 } else {
 388                         $commentedSql = $sql;
 389                 }
 390
 391                 # If DBO_TRX is set, start a transaction
 392                 if ( ( $this->mFlags & DBO_TRX ) && !$this->trxLevel() && $sql != 'BEGIN' ) {
 393                         $this->begin();
 394                 }
 395
 396                 if ( $this->debug() ) {
 397                         $sqlx = substr( $commentedSql, 0, 500 );
 398                         $sqlx = strtr( $sqlx, "\t\n", '  ' );
 399                         wfDebug( "SQL: $sqlx\n" );
 400                 }
 401
 402                 # Do the query and handle errors
 403                 $ret = $this->doQuery( $commentedSql );
 404
 405                 # Try reconnecting if the connection was lost
 406                 if ( false === $ret && ( $this->lastErrno() == 2013 || $this->lastErrno() == 2006 ) ) {
 407                         # Transaction is gone, like it or not
 408                         $this->mTrxLevel = 0;
 409                         wfDebug( "Connection lost, reconnecting...\n" );
 410                         if ( $this->ping() ) {
 411                                 wfDebug( "Reconnected\n" );
 412                                 $ret = $this->doQuery( $commentedSql );
 413                         } else {
 414                                 wfDebug( "Failed\n" );
 415                         }
 416                 }
 417
 418                 if ( false === $ret ) {
 419                         $this->reportQueryError( $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 420                 }
 421
 422                 if ( $wgProfiling ) {
 423                         wfProfileOut( $queryProf );
 424                         wfProfileOut( $totalProf );
 425                 }
 426                 return $ret;
 427         }
 428
 429         /**
 430          * The DBMS-dependent part of query()
 431          * @param string $sql SQL query.
 432          */
 433         function doQuery( $sql ) {
 434                 if( $this->bufferResults() ) {
 435                         $ret = mysql_query( $sql, $this->mConn );
 436                 } else {
 437                         $ret = mysql_unbuffered_query( $sql, $this->mConn );
 438                 }
 439                 return $ret;
 440         }
 441
 442         /**
 443          * @param $error
 444          * @param $errno
 445          * @param $sql
 446          * @param string $fname
 447          * @param bool $tempIgnore
 448          */
 449         function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 450                 global $wgCommandLineMode, $wgFullyInitialised, $wgColorErrors;
 451                 # Ignore errors during error handling to avoid infinite recursion
 452                 $ignore = $this->ignoreErrors( true );
 453                 ++$this->mErrorCount;
 454
 455                 if( $ignore || $tempIgnore ) {
 456                         wfDebug("SQL ERROR (ignored): $error\n");
 457                 } else {
 458                         $sql1line = str_replace( "\n", "\\n", $sql );
 459                         wfLogDBError("$fname\t{$this->mServer}\t$errno\t$error\t$sql1line\n");
 460                         wfDebug("SQL ERROR: " . $error . "\n");
 461                         if ( $wgCommandLineMode || !$this->mOut || empty( $wgFullyInitialised ) ) {
 462                                 $message = "A database error has occurred\n" .
 463                                   "Query: $sql\n" .
 464                                   "Function: $fname\n" .
 465                                   "Error: $errno $error\n";
 466                                 if ( !$wgCommandLineMode ) {
 467                                         $message = nl2br( $message );
 468                                 }
 469                                 if( $wgCommandLineMode && $wgColorErrors && !wfIsWindows() && posix_isatty(1) ) {
 470                                         $color = 31; // bright red!
 471                                         $message = "\x1b[1;{$color}m{$message}\x1b[0m";
 472                                 }
 473                                 wfDebugDieBacktrace( $message );
 474                         } else {
 475                                 // this calls wfAbruptExit()
 476                                 $this->mOut->databaseError( $fname, $sql, $error, $errno );
 477                         }
 478                 }
 479                 $this->ignoreErrors( $ignore );
 480         }
 481
 482
 483         /**
 484          * Intended to be compatible with the PEAR::DB wrapper functions.
 485          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
 486          *
 487          * ? = scalar value, quoted as necessary
 488          * ! = raw SQL bit (a function for instance)
 489          * & = filename; reads the file and inserts as a blob
 490          *     (we don't use this though...)
 491          */
 492         function prepare( $sql, $func = 'Database::prepare' ) {
 493                 /* MySQL doesn't support prepared statements (yet), so just
 494                    pack up the query for reference. We'll manually replace
 495                    the bits later. */
 496                 return array( 'query' => $sql, 'func' => $func );
 497         }
 498
 499         function freePrepared( $prepared ) {
 500                 /* No-op for MySQL */
 501         }
 502
 503         /**
 504          * Execute a prepared query with the various arguments
 505          * @param string $prepared the prepared sql
 506          * @param mixed $args Either an array here, or put scalars as varargs
 507          */
 508         function execute( $prepared, $args = null ) {
 509                 if( !is_array( $args ) ) {
 510                         # Pull the var args
 511                         $args = func_get_args();
 512                         array_shift( $args );
 513                 }
 514                 $sql = $this->fillPrepared( $prepared['query'], $args );
 515                 return $this->query( $sql, $prepared['func'] );
 516         }
 517
 518         /**
 519          * Prepare & execute an SQL statement, quoting and inserting arguments
 520          * in the appropriate places.
 521          * @param string $query
 522          * @param string $args ...
 523          */
 524         function safeQuery( $query, $args = null ) {
 525                 $prepared = $this->prepare( $query, 'Database::safeQuery' );
 526                 if( !is_array( $args ) ) {
 527                         # Pull the var args
 528                         $args = func_get_args();
 529                         array_shift( $args );
 530                 }
 531                 $retval = $this->execute( $prepared, $args );
 532                 $this->freePrepared( $prepared );
 533                 return $retval;
 534         }
 535
 536         /**
 537          * For faking prepared SQL statements on DBs that don't support
 538          * it directly.
 539          * @param string $preparedSql - a 'preparable' SQL statement
 540          * @param array $args - array of arguments to fill it with
 541          * @return string executable SQL
 542          */
 543         function fillPrepared( $preparedQuery, $args ) {
 544                 $n = 0;
 545                 reset( $args );
 546                 $this->preparedArgs =& $args;
 547                 return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
 548                         array( &$this, 'fillPreparedArg' ), $preparedQuery );
 549         }
 550
 551         /**
 552          * preg_callback func for fillPrepared()
 553          * The arguments should be in $this->preparedArgs and must not be touched
 554          * while we're doing this.
 555          *
 556          * @param array $matches
 557          * @return string
 558          * @access private
 559          */
 560         function fillPreparedArg( $matches ) {
 561                 switch( $matches[1] ) {
 562                         case '\\?': return '?';
 563                         case '\\!': return '!';
 564                         case '\\&': return '&';
 565                 }
 566                 list( $n, $arg ) = each( $this->preparedArgs );
 567                 switch( $matches[1] ) {
 568                         case '?': return $this->addQuotes( $arg );
 569                         case '!': return $arg;
 570                         case '&':
 571                                 # return $this->addQuotes( file_get_contents( $arg ) );
 572                                 wfDebugDieBacktrace( '& mode is not implemented. If it\'s really needed, uncomment the line above.' );
 573                         default:
 574                                 wfDebugDieBacktrace( 'Received invalid match. This should never happen!' );
 575                 }
 576         }
 577
 578         /**#@+
 579          * @param mixed $res A SQL result
 580          */
 581         /**
 582          * Free a result object
 583          */
 584         function freeResult( $res ) {
 585                 if ( !@/**/mysql_free_result( $res ) ) {
 586                         wfDebugDieBacktrace( "Unable to free MySQL result\n" );
 587                 }
 588         }
 589
 590         /**
 591          * Fetch the next row from the given result object, in object form
 592          */
 593         function fetchObject( $res ) {
 594                 @/**/$row = mysql_fetch_object( $res );
 595                 if( mysql_errno() ) {
 596                         wfDebugDieBacktrace( 'Error in fetchObject(): ' . htmlspecialchars( mysql_error() ) );
 597                 }
 598                 return $row;
 599         }
 600
 601         /**
 602          * Fetch the next row from the given result object
 603          * Returns an array
 604          */
 605         function fetchRow( $res ) {
 606                 @/**/$row = mysql_fetch_array( $res );
 607                 if (mysql_errno() ) {
 608                         wfDebugDieBacktrace( 'Error in fetchRow(): ' . htmlspecialchars( mysql_error() ) );
 609                 }
 610                 return $row;
 611         }
 612
 613         /**
 614          * Get the number of rows in a result object
 615          */
 616         function numRows( $res ) {
 617                 @/**/$n = mysql_num_rows( $res );
 618                 if( mysql_errno() ) {
 619                         wfDebugDieBacktrace( 'Error in numRows(): ' . htmlspecialchars( mysql_error() ) );
 620                 }
 621                 return $n;
 622         }
 623
 624         /**
 625          * Get the number of fields in a result object
 626          * See documentation for mysql_num_fields()
 627          */
 628         function numFields( $res ) { return mysql_num_fields( $res ); }
 629
 630         /**
 631          * Get a field name in a result object
 632          * See documentation for mysql_field_name()
 633          */
 634         function fieldName( $res, $n ) { return mysql_field_name( $res, $n ); }
 635
 636         /**
 637          * Get the inserted value of an auto-increment row
 638          *
 639          * The value inserted should be fetched from nextSequenceValue()
 640          *
 641          * Example:
 642          * $id = $dbw->nextSequenceValue('page_page_id_seq');
 643          * $dbw->insert('page',array('page_id' => $id));
 644          * $id = $dbw->insertId();
 645          */
 646         function insertId() { return mysql_insert_id( $this->mConn ); }
 647
 648         /**
 649          * Change the position of the cursor in a result object
 650          * See mysql_data_seek()
 651          */
 652         function dataSeek( $res, $row ) { return mysql_data_seek( $res, $row ); }
 653
 654         /**
 655          * Get the last error number
 656          * See mysql_errno()
 657          */
 658         function lastErrno() {
 659                 if ( $this->mConn ) {
 660                         return mysql_errno( $this->mConn );
 661                 } else {
 662                         return mysql_errno();
 663                 }
 664         }
 665
 666         /**
 667          * Get a description of the last error
 668          * See mysql_error() for more details
 669          */
 670         function lastError() {
 671                 if ( $this->mConn ) {
 672                         # Even if it's non-zero, it can still be invalid
 673                         wfSuppressWarnings();
 674                         $error = mysql_error( $this->mConn );
 675                         if ( !$error ) {
 676                                 $error = mysql_error();
 677                         }
 678                         wfRestoreWarnings();
 679                 } else {
 680                         $error = mysql_error();
 681                 }
 682                 if( $error ) {
 683                         $error .= ' (' . $this->mServer . ')';
 684                 }
 685                 return $error;
 686         }
 687         /**
 688          * Get the number of rows affected by the last write query
 689          * See mysql_affected_rows() for more details
 690          */
 691         function affectedRows() { return mysql_affected_rows( $this->mConn ); }
 692         /**#@-*/ // end of template : @param $result
 693
 694         /**
 695          * Simple UPDATE wrapper
 696          * Usually aborts on failure
 697          * If errors are explicitly ignored, returns success
 698          *
 699          * This function exists for historical reasons, Database::update() has a more standard
 700          * calling convention and feature set
 701          */
 702         function set( $table, $var, $value, $cond, $fname = 'Database::set' )
 703         {
 704                 $table = $this->tableName( $table );
 705                 $sql = "UPDATE $table SET $var = '" .
 706                   $this->strencode( $value ) . "' WHERE ($cond)";
 707                 return (bool)$this->query( $sql, $fname );
 708         }
 709
 710         /**
 711          * Simple SELECT wrapper, returns a single field, input must be encoded
 712          * Usually aborts on failure
 713          * If errors are explicitly ignored, returns FALSE on failure
 714          */
 715         function selectField( $table, $var, $cond='', $fname = 'Database::selectField', $options = array() ) {
 716                 if ( !is_array( $options ) ) {
 717                         $options = array( $options );
 718                 }
 719                 $options['LIMIT'] = 1;
 720
 721                 $res = $this->select( $table, $var, $cond, $fname, $options );
 722                 if ( $res === false || !$this->numRows( $res ) ) {
 723                         return false;
 724                 }
 725                 $row = $this->fetchRow( $res );
 726                 if ( $row !== false ) {
 727                         $this->freeResult( $res );
 728                         return $row[0];
 729                 } else {
 730                         return false;
 731                 }
 732         }
 733
 734         /**
 735          * Returns an optional USE INDEX clause to go after the table, and a
 736          * string to go at the end of the query
 737          *
 738          * @access private
 739          *
 740          * @param array $options an associative array of options to be turned into
 741          *              an SQL query, valid keys are listed in the function.
 742          * @return array
 743          */
 744         function makeSelectOptions( $options ) {
 745                 $tailOpts = '';
 746
 747                 if ( isset( $options['GROUP BY'] ) ) {
 748                         $tailOpts .= " GROUP BY {$options['GROUP BY']}";
 749                 }
 750                 if ( isset( $options['ORDER BY'] ) ) {
 751                         $tailOpts .= " ORDER BY {$options['ORDER BY']}";
 752                 }
 753                 if (isset($options['LIMIT'])) {
 754                         $tailOpts .= $this->limitResult('', $options['LIMIT'],
 755                                 isset($options['OFFSET']) ? $options['OFFSET'] : false);
 756                 }
 757                 if ( is_numeric( array_search( 'FOR UPDATE', $options ) ) ) {
 758                         $tailOpts .= ' FOR UPDATE';
 759                 }
 760
 761                 if ( is_numeric( array_search( 'LOCK IN SHARE MODE', $options ) ) ) {
 762                         $tailOpts .= ' LOCK IN SHARE MODE';
 763                 }
 764
 765                 if ( isset( $options['USE INDEX'] ) && ! is_array( $options['USE INDEX'] ) ) {
 766                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
 767                 } else {
 768                         $useIndex = '';
 769                 }
 770                 return array( $useIndex, $tailOpts );
 771         }
 772
 773         /**
 774          * SELECT wrapper
 775          */
 776         function select( $table, $vars, $conds='', $fname = 'Database::select', $options = array() )
 777         {
 778                 if( is_array( $vars ) ) {
 779                         $vars = implode( ',', $vars );
 780                 }
 781                 if( !is_array( $options ) ) {
 782                         $options = array( $options );
 783                 }
 784                 if( is_array( $table ) ) {
 785                         if ( @is_array( $options['USE INDEX'] ) )
 786                                 $from = ' FROM ' . $this->tableNamesWithUseIndex( $table, $options['USE INDEX'] );
 787                         else
 788                                 $from = ' FROM ' . implode( ',', array_map( array( &$this, 'tableName' ), $table ) );
 789                 } elseif ($table!='') {
 790                         $from = ' FROM ' . $this->tableName( $table );
 791                 } else {
 792                         $from = '';
 793                 }
 794
 795                 list( $useIndex, $tailOpts ) = $this->makeSelectOptions( $options );
 796
 797                 if( !empty( $conds ) ) {
 798                         if ( is_array( $conds ) ) {
 799                                 $conds = $this->makeList( $conds, LIST_AND );
 800                         }
 801                         $sql = "SELECT $vars $from $useIndex WHERE $conds $tailOpts";
 802                 } else {
 803                         $sql = "SELECT $vars $from $useIndex $tailOpts";
 804                 }
 805
 806                 return $this->query( $sql, $fname );
 807         }
 808
 809         /**
 810          * Single row SELECT wrapper
 811          * Aborts or returns FALSE on error
 812          *
 813          * $vars: the selected variables
 814          * $conds: a condition map, terms are ANDed together.
 815          *   Items with numeric keys are taken to be literal conditions
 816          * Takes an array of selected variables, and a condition map, which is ANDed
 817          * e.g: selectRow( "page", array( "page_id" ), array( "page_namespace" =>
 818          * NS_MAIN, "page_title" => "Astronomy" ) )   would return an object where
 819          * $obj- >page_id is the ID of the Astronomy article
 820          *
 821          * @todo migrate documentation to phpdocumentor format
 822          */
 823         function selectRow( $table, $vars, $conds, $fname = 'Database::selectRow', $options = array() ) {
 824                 $options['LIMIT'] = 1;
 825                 $res = $this->select( $table, $vars, $conds, $fname, $options );
 826                 if ( $res === false )
 827                         return false;
 828                 if ( !$this->numRows($res) ) {
 829                         $this->freeResult($res);
 830                         return false;
 831                 }
 832                 $obj = $this->fetchObject( $res );
 833                 $this->freeResult( $res );
 834                 return $obj;
 835
 836         }
 837
 838         /**
 839          * Removes most variables from an SQL query and replaces them with X or N for numbers.
 840          * It's only slightly flawed. Don't use for anything important.
 841          *
 842          * @param string $sql A SQL Query
 843          * @static
 844          */
 845         function generalizeSQL( $sql ) {
 846                 # This does the same as the regexp below would do, but in such a way
 847                 # as to avoid crashing php on some large strings.
 848                 # $sql = preg_replace ( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql);
 849
 850                 $sql = str_replace ( "\\\\", '', $sql);
 851                 $sql = str_replace ( "\\'", '', $sql);
 852                 $sql = str_replace ( "\\\"", '', $sql);
 853                 $sql = preg_replace ("/'.*'/s", "'X'", $sql);
 854                 $sql = preg_replace ('/".*"/s', "'X'", $sql);
 855
 856                 # All newlines, tabs, etc replaced by single space
 857                 $sql = preg_replace ( "/\s+/", ' ', $sql);
 858
 859                 # All numbers => N
 860                 $sql = preg_replace ('/-?[0-9]+/s', 'N', $sql);
 861
 862                 return $sql;
 863         }
 864
 865         /**
 866          * Determines whether a field exists in a table
 867          * Usually aborts on failure
 868          * If errors are explicitly ignored, returns NULL on failure
 869          */
 870         function fieldExists( $table, $field, $fname = 'Database::fieldExists' ) {
 871                 $table = $this->tableName( $table );
 872                 $res = $this->query( 'DESCRIBE '.$table, $fname );
 873                 if ( !$res ) {
 874                         return NULL;
 875                 }
 876
 877                 $found = false;
 878
 879                 while ( $row = $this->fetchObject( $res ) ) {
 880                         if ( $row->Field == $field ) {
 881                                 $found = true;
 882                                 break;
 883                         }
 884                 }
 885                 return $found;
 886         }
 887
 888         /**
 889          * Determines whether an index exists
 890          * Usually aborts on failure
 891          * If errors are explicitly ignored, returns NULL on failure
 892          */
 893         function indexExists( $table, $index, $fname = 'Database::indexExists' ) {
 894                 $info = $this->indexInfo( $table, $index, $fname );
 895                 if ( is_null( $info ) ) {
 896                         return NULL;
 897                 } else {
 898                         return $info !== false;
 899                 }
 900         }
 901
 902
 903         /**
 904          * Get information about an index into an object
 905          * Returns false if the index does not exist
 906          */
 907         function indexInfo( $table, $index, $fname = 'Database::indexInfo' ) {
 908                 # SHOW INDEX works in MySQL 3.23.58, but SHOW INDEXES does not.
 909                 # SHOW INDEX should work for 3.x and up:
 910                 # http://dev.mysql.com/doc/mysql/en/SHOW_INDEX.html
 911                 $table = $this->tableName( $table );
 912                 $sql = 'SHOW INDEX FROM '.$table;
 913                 $res = $this->query( $sql, $fname );
 914                 if ( !$res ) {
 915                         return NULL;
 916                 }
 917
 918                 while ( $row = $this->fetchObject( $res ) ) {
 919                         if ( $row->Key_name == $index ) {
 920                                 return $row;
 921                         }
 922                 }
 923                 return false;
 924         }
 925
 926         /**
 927          * Query whether a given table exists
 928          */
 929         function tableExists( $table ) {
 930                 $table = $this->tableName( $table );
 931                 $old = $this->ignoreErrors( true );
 932                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1" );
 933                 $this->ignoreErrors( $old );
 934                 if( $res ) {
 935                         $this->freeResult( $res );
 936                         return true;
 937                 } else {
 938                         return false;
 939                 }
 940         }
 941
 942         /**
 943          * mysql_fetch_field() wrapper
 944          * Returns false if the field doesn't exist
 945          *
 946          * @param $table
 947          * @param $field
 948          */
 949         function fieldInfo( $table, $field ) {
 950                 $table = $this->tableName( $table );
 951                 $res = $this->query( "SELECT * FROM $table LIMIT 1" );
 952                 $n = mysql_num_fields( $res );
 953                 for( $i = 0; $i < $n; $i++ ) {
 954                         $meta = mysql_fetch_field( $res, $i );
 955                         if( $field == $meta->name ) {
 956                                 return $meta;
 957                         }
 958                 }
 959                 return false;
 960         }
 961
 962         /**
 963          * mysql_field_type() wrapper
 964          */
 965         function fieldType( $res, $index ) {
 966                 return mysql_field_type( $res, $index );
 967         }
 968
 969         /**
 970          * Determines if a given index is unique
 971          */
 972         function indexUnique( $table, $index ) {
 973                 $indexInfo = $this->indexInfo( $table, $index );
 974                 if ( !$indexInfo ) {
 975                         return NULL;
 976                 }
 977                 return !$indexInfo->Non_unique;
 978         }
 979
 980         /**
 981          * INSERT wrapper, inserts an array into a table
 982          *
 983          * $a may be a single associative array, or an array of these with numeric keys, for
 984          * multi-row insert.
 985          *
 986          * Usually aborts on failure
 987          * If errors are explicitly ignored, returns success
 988          */
 989         function insert( $table, $a, $fname = 'Database::insert', $options = array() ) {
 990                 # No rows to insert, easy just return now
 991                 if ( !count( $a ) ) {
 992                         return true;
 993                 }
 994
 995                 $table = $this->tableName( $table );
 996                 if ( !is_array( $options ) ) {
 997                         $options = array( $options );
 998                 }
 999                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1000                         $multi = true;
1001                         $keys = array_keys( $a[0] );
1002                 } else {
1003                         $multi = false;
1004                         $keys = array_keys( $a );
1005                 }
1006
1007                 $sql = 'INSERT ' . implode( ' ', $options ) .
1008                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1009
1010                 if ( $multi ) {
1011                         $first = true;
1012                         foreach ( $a as $row ) {
1013                                 if ( $first ) {
1014                                         $first = false;
1015                                 } else {
1016                                         $sql .= ',';
1017                                 }
1018                                 $sql .= '(' . $this->makeList( $row ) . ')';
1019                         }
1020                 } else {
1021                         $sql .= '(' . $this->makeList( $a ) . ')';
1022                 }
1023                 return (bool)$this->query( $sql, $fname );
1024         }
1025
1026         /**
1027          * Make UPDATE options for the Database::update function
1028          *
1029          * @access private
1030          * @param array $options The options passed to Database::update
1031          * @return string
1032          */
1033         function makeUpdateOptions( $options ) {
1034                 if( !is_array( $options ) ) {
1035                         $options = array( $options );
1036                 }
1037                 $opts = array();
1038                 if ( in_array( 'LOW_PRIORITY', $options ) )
1039                         $opts[] = $this->lowPriorityOption();
1040                 if ( in_array( 'IGNORE', $options ) )
1041                         $opts[] = 'IGNORE';
1042                 return implode(' ', $opts);
1043         }
1044
1045         /**
1046          * UPDATE wrapper, takes a condition array and a SET array
1047          *
1048          * @param string $table  The table to UPDATE
1049          * @param array  $values An array of values to SET
1050          * @param array  $conds  An array of conditions (WHERE). Use '*' to update all rows.
1051          * @param string $fname  The Class::Function calling this function
1052          *                       (for the log)
1053          * @param array  $options An array of UPDATE options, can be one or
1054          *                        more of IGNORE, LOW_PRIORITY
1055          */
1056         function update( $table, $values, $conds, $fname = 'Database::update', $options = array() ) {
1057                 $table = $this->tableName( $table );
1058                 $opts = $this->makeUpdateOptions( $options );
1059                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1060                 if ( $conds != '*' ) {
1061                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1062                 }
1063                 $this->query( $sql, $fname );
1064         }
1065
1066         /**
1067          * Makes a wfStrencoded list from an array
1068          * $mode: LIST_COMMA         - comma separated, no field names
1069          *        LIST_AND           - ANDed WHERE clause (without the WHERE)
1070          *        LIST_SET           - comma separated with field names, like a SET clause
1071          *        LIST_NAMES         - comma separated field names
1072          */
1073         function makeList( $a, $mode = LIST_COMMA ) {
1074                 if ( !is_array( $a ) ) {
1075                         wfDebugDieBacktrace( 'Database::makeList called with incorrect parameters' );
1076                 }
1077
1078                 $first = true;
1079                 $list = '';
1080                 foreach ( $a as $field => $value ) {
1081                         if ( !$first ) {
1082                                 if ( $mode == LIST_AND ) {
1083                                         $list .= ' AND ';
1084                                 } elseif($mode == LIST_OR) {
1085                                         $list .= ' OR ';
1086                                 } else {
1087                                         $list .= ',';
1088                                 }
1089                         } else {
1090                                 $first = false;
1091                         }
1092                         if ( ($mode == LIST_AND || $mode == LIST_OR) && is_numeric( $field ) ) {
1093                                 $list .= "($value)";
1094                         } elseif ( $mode == LIST_AND && is_array ($value) ) {
1095                                 $list .= $field." IN (".$this->makeList($value).") ";
1096                         } else {
1097                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
1098                                         $list .= "$field = ";
1099                                 }
1100                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
1101                         }
1102                 }
1103                 return $list;
1104         }
1105
1106         /**
1107          * Change the current database
1108          */
1109         function selectDB( $db ) {
1110                 $this->mDBname = $db;
1111                 return mysql_select_db( $db, $this->mConn );
1112         }
1113
1114         /**
1115          * Format a table name ready for use in constructing an SQL query
1116          *
1117          * This does two important things: it quotes table names which as necessary,
1118          * and it adds a table prefix if there is one.
1119          *
1120          * All functions of this object which require a table name call this function
1121          * themselves. Pass the canonical name to such functions. This is only needed
1122          * when calling query() directly.
1123          *
1124          * @param string $name database table name
1125          */
1126         function tableName( $name ) {
1127                 global $wgSharedDB;
1128                 # Skip quoted literals
1129                 if ( $name{0} != '`' ) {
1130                         if ( $this->mTablePrefix !== '' &&  strpos( '.', $name ) === false ) {
1131                                 $name = "{$this->mTablePrefix}$name";
1132                         }
1133                         if ( isset( $wgSharedDB ) && "{$this->mTablePrefix}user" == $name ) {
1134                                 $name = "`$wgSharedDB`.`$name`";
1135                         } else {
1136                                 # Standard quoting
1137                                 $name = "`$name`";
1138                         }
1139                 }
1140                 return $name;
1141         }
1142
1143         /**
1144          * Fetch a number of table names into an array
1145          * This is handy when you need to construct SQL for joins
1146          *
1147          * Example:
1148          * extract($dbr->tableNames('user','watchlist'));
1149          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1150          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1151          */
1152         function tableNames() {
1153                 $inArray = func_get_args();
1154                 $retVal = array();
1155                 foreach ( $inArray as $name ) {
1156                         $retVal[$name] = $this->tableName( $name );
1157                 }
1158                 return $retVal;
1159         }
1160
1161         /**
1162          * @access private
1163          */
1164         function tableNamesWithUseIndex( $tables, $use_index ) {
1165                 $ret = array();
1166
1167                 foreach ( $tables as $table )
1168                         if ( @$use_index[$table] !== null )
1169                                 $ret[] = $this->tableName( $table ) . ' ' . $this->useIndexClause( implode( ',', (array)$use_index[$table] ) );
1170                         else
1171                                 $ret[] = $this->tableName( $table );
1172
1173                 return implode( ',', $ret );
1174         }
1175
1176         /**
1177          * Wrapper for addslashes()
1178          * @param string $s String to be slashed.
1179          * @return string slashed string.
1180          */
1181         function strencode( $s ) {
1182                 return addslashes( $s );
1183         }
1184
1185         /**
1186          * If it's a string, adds quotes and backslashes
1187          * Otherwise returns as-is
1188          */
1189         function addQuotes( $s ) {
1190                 if ( is_null( $s ) ) {
1191                         return 'NULL';
1192                 } else {
1193                         # This will also quote numeric values. This should be harmless,
1194                         # and protects against weird problems that occur when they really
1195                         # _are_ strings such as article titles and string->number->string
1196                         # conversion is not 1:1.
1197                         return "'" . $this->strencode( $s ) . "'";
1198                 }
1199         }
1200
1201         /**
1202          * Escape string for safe LIKE usage
1203          */
1204         function escapeLike( $s ) {
1205                 $s=$this->strencode( $s );
1206                 $s=str_replace(array('%','_'),array('\%','\_'),$s);
1207                 return $s;
1208         }
1209
1210         /**
1211          * Returns an appropriately quoted sequence value for inserting a new row.
1212          * MySQL has autoincrement fields, so this is just NULL. But the PostgreSQL
1213          * subclass will return an integer, and save the value for insertId()
1214          */
1215         function nextSequenceValue( $seqName ) {
1216                 return NULL;
1217         }
1218
1219         /**
1220          * USE INDEX clause
1221          * PostgreSQL doesn't have them and returns ""
1222          */
1223         function useIndexClause( $index ) {
1224                 return "FORCE INDEX ($index)";
1225         }
1226
1227         /**
1228          * REPLACE query wrapper
1229          * PostgreSQL simulates this with a DELETE followed by INSERT
1230          * $row is the row to insert, an associative array
1231          * $uniqueIndexes is an array of indexes. Each element may be either a
1232          * field name or an array of field names
1233          *
1234          * It may be more efficient to leave off unique indexes which are unlikely to collide.
1235          * However if you do this, you run the risk of encountering errors which wouldn't have
1236          * occurred in MySQL
1237          *
1238          * @todo migrate comment to phodocumentor format
1239          */
1240         function replace( $table, $uniqueIndexes, $rows, $fname = 'Database::replace' ) {
1241                 $table = $this->tableName( $table );
1242
1243                 # Single row case
1244                 if ( !is_array( reset( $rows ) ) ) {
1245                         $rows = array( $rows );
1246                 }
1247
1248                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) .') VALUES ';
1249                 $first = true;
1250                 foreach ( $rows as $row ) {
1251                         if ( $first ) {
1252                                 $first = false;
1253                         } else {
1254                                 $sql .= ',';
1255                         }
1256                         $sql .= '(' . $this->makeList( $row ) . ')';
1257                 }
1258                 return $this->query( $sql, $fname );
1259         }
1260
1261         /**
1262          * DELETE where the condition is a join
1263          * MySQL does this with a multi-table DELETE syntax, PostgreSQL does it with sub-selects
1264          *
1265          * For safety, an empty $conds will not delete everything. If you want to delete all rows where the
1266          * join condition matches, set $conds='*'
1267          *
1268          * DO NOT put the join condition in $conds
1269          *
1270          * @param string $delTable The table to delete from.
1271          * @param string $joinTable The other table.
1272          * @param string $delVar The variable to join on, in the first table.
1273          * @param string $joinVar The variable to join on, in the second table.
1274          * @param array $conds Condition array of field names mapped to variables, ANDed together in the WHERE clause
1275          */
1276         function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds, $fname = 'Database::deleteJoin' ) {
1277                 if ( !$conds ) {
1278                         wfDebugDieBacktrace( 'Database::deleteJoin() called with empty $conds' );
1279                 }
1280
1281                 $delTable = $this->tableName( $delTable );
1282                 $joinTable = $this->tableName( $joinTable );
1283                 $sql = "DELETE $delTable FROM $delTable, $joinTable WHERE $delVar=$joinVar ";
1284                 if ( $conds != '*' ) {
1285                         $sql .= ' AND ' . $this->makeList( $conds, LIST_AND );
1286                 }
1287
1288                 return $this->query( $sql, $fname );
1289         }
1290
1291         /**
1292          * Returns the size of a text field, or -1 for "unlimited"
1293          */
1294         function textFieldSize( $table, $field ) {
1295                 $table = $this->tableName( $table );
1296                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
1297                 $res = $this->query( $sql, 'Database::textFieldSize' );
1298                 $row = $this->fetchObject( $res );
1299                 $this->freeResult( $res );
1300
1301                 if ( preg_match( "/\((.*)\)/", $row->Type, $m ) ) {
1302                         $size = $m[1];
1303                 } else {
1304                         $size = -1;
1305                 }
1306                 return $size;
1307         }
1308
1309         /**
1310          * @return string Returns the text of the low priority option if it is supported, or a blank string otherwise
1311          */
1312         function lowPriorityOption() {
1313                 return 'LOW_PRIORITY';
1314         }
1315
1316         /**
1317          * DELETE query wrapper
1318          *
1319          * Use $conds == "*" to delete all rows
1320          */
1321         function delete( $table, $conds, $fname = 'Database::delete' ) {
1322                 if ( !$conds ) {
1323                         wfDebugDieBacktrace( 'Database::delete() called with no conditions' );
1324                 }
1325                 $table = $this->tableName( $table );
1326                 $sql = "DELETE FROM $table";
1327                 if ( $conds != '*' ) {
1328                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1329                 }
1330                 return $this->query( $sql, $fname );
1331         }
1332
1333         /**
1334          * INSERT SELECT wrapper
1335          * $varMap must be an associative array of the form array( 'dest1' => 'source1', ...)
1336          * Source items may be literals rather than field names, but strings should be quoted with Database::addQuotes()
1337          * $conds may be "*" to copy the whole table
1338          * srcTable may be an array of tables.
1339          */
1340         function insertSelect( $destTable, $srcTable, $varMap, $conds, $fname = 'Database::insertSelect',
1341                 $insertOptions = array(), $selectOptions = array() )
1342         {
1343                 $destTable = $this->tableName( $destTable );
1344                 if ( is_array( $insertOptions ) ) {
1345                         $insertOptions = implode( ' ', $insertOptions );
1346                 }
1347                 if( !is_array( $selectOptions ) ) {
1348                         $selectOptions = array( $selectOptions );
1349                 }
1350                 list( $useIndex, $tailOpts ) = $this->makeSelectOptions( $selectOptions );
1351                 if( is_array( $srcTable ) ) {
1352                         $srcTable =  implode( ',', array_map( array( &$this, 'tableName' ), $srcTable ) );
1353                 } else {
1354                         $srcTable = $this->tableName( $srcTable );
1355                 }
1356                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
1357                         ' SELECT ' . implode( ',', $varMap ) .
1358                         " FROM $srcTable $useIndex ";
1359                 if ( $conds != '*' ) {
1360                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1361                 }
1362                 $sql .= " $tailOpts";
1363                 return $this->query( $sql, $fname );
1364         }
1365
1366         /**
1367          * Construct a LIMIT query with optional offset
1368          * This is used for query pages
1369          * $sql string SQL query we will append the limit too
1370          * $limit integer the SQL limit
1371          * $offset integer the SQL offset (default false)
1372          */
1373         function limitResult($sql, $limit, $offset=false) {
1374                 return " $sql LIMIT ".((is_numeric($offset) && $offset != 0)?"{$offset},":"")."{$limit} ";
1375         }
1376         function limitResultForUpdate($sql, $num) {
1377                 return $this->limitResult($sql, $num, 0);
1378         }
1379
1380         /**
1381          * Returns an SQL expression for a simple conditional.
1382          * Uses IF on MySQL.
1383          *
1384          * @param string $cond SQL expression which will result in a boolean value
1385          * @param string $trueVal SQL expression to return if true
1386          * @param string $falseVal SQL expression to return if false
1387          * @return string SQL fragment
1388          */
1389         function conditional( $cond, $trueVal, $falseVal ) {
1390                 return " IF($cond, $trueVal, $falseVal) ";
1391         }
1392
1393         /**
1394          * Determines if the last failure was due to a deadlock
1395          */
1396         function wasDeadlock() {
1397                 return $this->lastErrno() == 1213;
1398         }
1399
1400         /**
1401          * Perform a deadlock-prone transaction.
1402          *
1403          * This function invokes a callback function to perform a set of write
1404          * queries. If a deadlock occurs during the processing, the transaction
1405          * will be rolled back and the callback function will be called again.
1406          *
1407          * Usage:
1408          *   $dbw->deadlockLoop( callback, ... );
1409          *
1410          * Extra arguments are passed through to the specified callback function.
1411          *
1412          * Returns whatever the callback function returned on its successful,
1413          * iteration, or false on error, for example if the retry limit was
1414          * reached.
1415          */
1416         function deadlockLoop() {
1417                 $myFname = 'Database::deadlockLoop';
1418
1419                 $this->begin();
1420                 $args = func_get_args();
1421                 $function = array_shift( $args );
1422                 $oldIgnore = $this->ignoreErrors( true );
1423                 $tries = DEADLOCK_TRIES;
1424                 if ( is_array( $function ) ) {
1425                         $fname = $function[0];
1426                 } else {
1427                         $fname = $function;
1428                 }
1429                 do {
1430                         $retVal = call_user_func_array( $function, $args );
1431                         $error = $this->lastError();
1432                         $errno = $this->lastErrno();
1433                         $sql = $this->lastQuery();
1434
1435                         if ( $errno ) {
1436                                 if ( $this->wasDeadlock() ) {
1437                                         # Retry
1438                                         usleep( mt_rand( DEADLOCK_DELAY_MIN, DEADLOCK_DELAY_MAX ) );
1439                                 } else {
1440                                         $this->reportQueryError( $error, $errno, $sql, $fname );
1441                                 }
1442                         }
1443                 } while( $this->wasDeadlock() && --$tries > 0 );
1444                 $this->ignoreErrors( $oldIgnore );
1445                 if ( $tries <= 0 ) {
1446                         $this->query( 'ROLLBACK', $myFname );
1447                         $this->reportQueryError( $error, $errno, $sql, $fname );
1448                         return false;
1449                 } else {
1450                         $this->query( 'COMMIT', $myFname );
1451                         return $retVal;
1452                 }
1453         }
1454
1455         /**
1456          * Do a SELECT MASTER_POS_WAIT()
1457          *
1458          * @param string $file the binlog file
1459          * @param string $pos the binlog position
1460          * @param integer $timeout the maximum number of seconds to wait for synchronisation
1461          */
1462         function masterPosWait( $file, $pos, $timeout ) {
1463                 $fname = 'Database::masterPosWait';
1464                 wfProfileIn( $fname );
1465
1466
1467                 # Commit any open transactions
1468                 $this->immediateCommit();
1469
1470                 # Call doQuery() directly, to avoid opening a transaction if DBO_TRX is set
1471                 $encFile = $this->strencode( $file );
1472                 $sql = "SELECT MASTER_POS_WAIT('$encFile', $pos, $timeout)";
1473                 $res = $this->doQuery( $sql );
1474                 if ( $res && $row = $this->fetchRow( $res ) ) {
1475                         $this->freeResult( $res );
1476                         wfProfileOut( $fname );
1477                         return $row[0];
1478                 } else {
1479                         wfProfileOut( $fname );
1480                         return false;
1481                 }
1482         }
1483
1484         /**
1485          * Get the position of the master from SHOW SLAVE STATUS
1486          */
1487         function getSlavePos() {
1488                 $res = $this->query( 'SHOW SLAVE STATUS', 'Database::getSlavePos' );
1489                 $row = $this->fetchObject( $res );
1490                 if ( $row ) {
1491                         return array( $row->Master_Log_File, $row->Read_Master_Log_Pos );
1492                 } else {
1493                         return array( false, false );
1494                 }
1495         }
1496
1497         /**
1498          * Get the position of the master from SHOW MASTER STATUS
1499          */
1500         function getMasterPos() {
1501                 $res = $this->query( 'SHOW MASTER STATUS', 'Database::getMasterPos' );
1502                 $row = $this->fetchObject( $res );
1503                 if ( $row ) {
1504                         return array( $row->File, $row->Position );
1505                 } else {
1506                         return array( false, false );
1507                 }
1508         }
1509
1510         /**
1511          * Begin a transaction, or if a transaction has already started, continue it
1512          */
1513         function begin( $fname = 'Database::begin' ) {
1514                 if ( !$this->mTrxLevel ) {
1515                         $this->immediateBegin( $fname );
1516                 } else {
1517                         $this->mTrxLevel++;
1518                 }
1519         }
1520
1521         /**
1522          * End a transaction, or decrement the nest level if transactions are nested
1523          */
1524         function commit( $fname = 'Database::commit' ) {
1525                 if ( $this->mTrxLevel ) {
1526                         $this->mTrxLevel--;
1527                 }
1528                 if ( !$this->mTrxLevel ) {
1529                         $this->immediateCommit( $fname );
1530                 }
1531         }
1532
1533         /**
1534          * Rollback a transaction
1535          */
1536         function rollback( $fname = 'Database::rollback' ) {
1537                 $this->query( 'ROLLBACK', $fname );
1538                 $this->mTrxLevel = 0;
1539         }
1540
1541         /**
1542          * Begin a transaction, committing any previously open transaction
1543          */
1544         function immediateBegin( $fname = 'Database::immediateBegin' ) {
1545                 $this->query( 'BEGIN', $fname );
1546                 $this->mTrxLevel = 1;
1547         }
1548
1549         /**
1550          * Commit transaction, if one is open
1551          */
1552         function immediateCommit( $fname = 'Database::immediateCommit' ) {
1553                 $this->query( 'COMMIT', $fname );
1554                 $this->mTrxLevel = 0;
1555         }
1556
1557         /**
1558          * Return MW-style timestamp used for MySQL schema
1559          */
1560         function timestamp( $ts=0 ) {
1561                 return wfTimestamp(TS_MW,$ts);
1562         }
1563
1564         /**
1565          * Local database timestamp format or null
1566          */
1567         function timestampOrNull( $ts = null ) {
1568                 if( is_null( $ts ) ) {
1569                         return null;
1570                 } else {
1571                         return $this->timestamp( $ts );
1572                 }
1573         }
1574
1575         /**
1576          * @todo document
1577          */
1578         function resultObject( $result ) {
1579                 if( empty( $result ) ) {
1580                         return NULL;
1581                 } else {
1582                         return new ResultWrapper( $this, $result );
1583                 }
1584         }
1585
1586         /**
1587          * Return aggregated value alias
1588          */
1589         function aggregateValue ($valuedata,$valuename='value') {
1590                 return $valuename;
1591         }
1592
1593         /**
1594          * @return string wikitext of a link to the server software's web site
1595          */
1596         function getSoftwareLink() {
1597                 return "[http://www.mysql.com/ MySQL]";
1598         }
1599
1600         /**
1601          * @return string Version information from the database
1602          */
1603         function getServerVersion() {
1604                 return mysql_get_server_info();
1605         }
1606
1607         /**
1608          * Ping the server and try to reconnect if it there is no connection
1609          */
1610         function ping() {
1611                 if( function_exists( 'mysql_ping' ) ) {
1612                         return mysql_ping( $this->mConn );
1613                 } else {
1614                         wfDebug( "Tried to call mysql_ping but this is ancient PHP version. Faking it!\n" );
1615                         return true;
1616                 }
1617         }
1618
1619         /**
1620          * Get slave lag.
1621          * At the moment, this will only work if the DB user has the PROCESS privilege
1622          */
1623         function getLag() {
1624                 $res = $this->query( 'SHOW PROCESSLIST' );
1625                 # Find slave SQL thread. Assumed to be the second one running, which is a bit
1626                 # dubious, but unfortunately there's no easy rigorous way
1627                 $slaveThreads = 0;
1628                 while ( $row = $this->fetchObject( $res ) ) {
1629                         if ( $row->User == 'system user' ) {
1630                                 if ( ++$slaveThreads == 2 ) {
1631                                         # This is it, return the time (except -ve)
1632                                         if ( $row->Time > 1<<31 ) {
1633                                                 return 0;
1634                                         } else {
1635                                                 return $row->Time;
1636                                         }
1637                                 }
1638                         }
1639                 }
1640                 return false;
1641         }
1642
1643         /**
1644          * Get status information from SHOW STATUS in an associative array
1645          */
1646         function getStatus($which="%") {
1647                 $res = $this->query( "SHOW STATUS LIKE '{$which}'" );
1648                 $status = array();
1649                 while ( $row = $this->fetchObject( $res ) ) {
1650                         $status[$row->Variable_name] = $row->Value;
1651                 }
1652                 return $status;
1653         }
1654
1655         /**
1656          * Return the maximum number of items allowed in a list, or 0 for unlimited.
1657          */
1658         function maxListLen() {
1659                 return 0;
1660         }
1661
1662         function encodeBlob($b) {
1663                 return $b;
1664         }
1665
1666         /**
1667          * Read and execute SQL commands from a file.
1668          * Returns true on success, error string on failure
1669          */
1670         function sourceFile( $filename ) {
1671                 $fp = fopen( $filename, 'r' );
1672                 if ( false === $fp ) {
1673                         return "Could not open \"{$fname}\".\n";
1674                 }
1675
1676                 $cmd = "";
1677                 $done = false;
1678
1679                 while ( ! feof( $fp ) ) {
1680                         $line = trim( fgets( $fp, 1024 ) );
1681                         $sl = strlen( $line ) - 1;
1682
1683                         if ( $sl < 0 ) { continue; }
1684                         if ( '-' == $line{0} && '-' == $line{1} ) { continue; }
1685
1686                         if ( ';' == $line{$sl} && ($sl < 2 || ';' != $line{$sl - 1})) {
1687                                 $done = true;
1688                                 $line = substr( $line, 0, $sl );
1689                         }
1690
1691                         if ( '' != $cmd ) { $cmd .= ' '; }
1692                         $cmd .= "$line\n";
1693
1694                         if ( $done ) {
1695                                 $cmd = str_replace(';;', ";", $cmd);
1696                                 $cmd = $this->replaceVars( $cmd );
1697                                 $res = $this->query( $cmd, 'dbsource', true );
1698
1699                                 if ( false === $res ) {
1700                                         $err = $this->lastError();
1701                                         return "Query \"{$cmd}\" failed with error code \"$err\".\n";
1702                                 }
1703
1704                                 $cmd = '';
1705                                 $done = false;
1706                         }
1707                 }
1708                 fclose( $fp );
1709                 return true;
1710         }
1711
1712         /**
1713          * Replace variables in sourced SQL
1714          */
1715         function replaceVars( $ins ) {
1716                 $varnames = array(
1717                         'wgDBserver', 'wgDBname', 'wgDBintlname', 'wgDBuser',
1718                         'wgDBpassword', 'wgDBsqluser', 'wgDBsqlpassword',
1719                         'wgDBadminuser', 'wgDBadminpassword',
1720                 );
1721
1722                 // Ordinary variables
1723                 foreach ( $varnames as $var ) {
1724                         if( isset( $GLOBALS[$var] ) ) {
1725                                 $val = addslashes( $GLOBALS[$var] );
1726                                 $ins = str_replace( '{$' . $var . '}', $val, $ins );
1727                                 $ins = str_replace( '/*$' . $var . '*/`', '`' . $val, $ins );
1728                                 $ins = str_replace( '/*$' . $var . '*/', $val, $ins );
1729                         }
1730                 }
1731
1732                 // Table prefixes
1733                 $ins = preg_replace_callback( '/\/\*(?:\$wgDBprefix|_)\*\/([a-z_]*)/',
1734                         array( &$this, 'tableNameCallback' ), $ins );
1735                 return $ins;
1736         }
1737
1738         /**
1739          * Table name callback
1740          * @access private
1741          */
1742         function tableNameCallback( $matches ) {
1743                 return $this->tableName( $matches[1] );
1744         }
1745
1746 }
1747
1748 /**
1749  * Database abstraction object for mySQL
1750  * Inherit all methods and properties of Database::Database()
1751  *
1752  * @package MediaWiki
1753  * @see Database
1754  */
1755 class DatabaseMysql extends Database {
1756         # Inherit all
1757 }
1758
1759
1760 /**
1761  * Result wrapper for grabbing data queried by someone else
1762  *
1763  * @package MediaWiki
1764  */
1765 class ResultWrapper {
1766         var $db, $result;
1767
1768         /**
1769          * @todo document
1770          */
1771         function ResultWrapper( &$database, $result ) {
1772                 $this->db =& $database;
1773                 $this->result =& $result;
1774         }
1775
1776         /**
1777          * @todo document
1778          */
1779         function numRows() {
1780                 return $this->db->numRows( $this->result );
1781         }
1782
1783         /**
1784          * @todo document
1785          */
1786         function fetchObject() {
1787                 return $this->db->fetchObject( $this->result );
1788         }
1789
1790         /**
1791          * @todo document
1792          */
1793         function &fetchRow() {
1794                 return $this->db->fetchRow( $this->result );
1795         }
1796
1797         /**
1798          * @todo document
1799          */
1800         function free() {
1801                 $this->db->freeResult( $this->result );
1802                 unset( $this->result );
1803                 unset( $this->db );
1804         }
1805
1806         function seek( $row ) {
1807                 $this->db->dataSeek( $this->result, $row );
1808         }
1809
1810 }
1811
1812
1813 #------------------------------------------------------------------------------
1814 # Global functions
1815 #------------------------------------------------------------------------------
1816
1817 /**
1818  * Standard fail function, called by default when a connection cannot be
1819  * established.
1820  * Displays the file cache if possible
1821  */
1822 function wfEmergencyAbort( &$conn, $error ) {
1823         global $wgTitle, $wgUseFileCache, $title, $wgInputEncoding, $wgOutputEncoding;
1824         global $wgSitename, $wgServer, $wgMessageCache, $wgLogo;
1825
1826         # I give up, Brion is right. Getting the message cache to work when there is no DB is tricky.
1827         # Hard coding strings instead.
1828
1829         $noconnect = "<h1><img src='$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>";
1830         $mainpage = 'Main Page';
1831         $searchdisabled = <<<EOT
1832 <p style="margin: 1.5em 2em 1em">$wgSitename search is disabled for performance reasons. You can search via Google in the meantime.
1833 <span style="font-size: 89%; display: block; margin-left: .2em">Note that their indexes of $wgSitename content may be out of date.</span></p>',
1834 EOT;
1835
1836         $googlesearch = "
1837 <!-- SiteSearch Google -->
1838 <FORM method=GET action=\"http://www.google.com/search\">
1839 <TABLE bgcolor=\"#FFFFFF\"><tr><td>
1840 <A HREF=\"http://www.google.com/\">
1841 <IMG SRC=\"http://www.google.com/logos/Logo_40wht.gif\"
1842 border=\"0\" ALT=\"Google\"></A>
1843 </td>
1844 <td>
1845 <INPUT TYPE=text name=q size=31 maxlength=255 value=\"$1\">
1846 <INPUT type=submit name=btnG VALUE=\"Google Search\">
1847 <font size=-1>
1848 <input type=hidden name=domains value=\"$wgServer\"><br /><input type=radio name=sitesearch value=\"\"> WWW <input type=radio name=sitesearch value=\"$wgServer\" checked> $wgServer <br />
1849 <input type='hidden' name='ie' value='$2'>
1850 <input type='hidden' name='oe' value='$2'>
1851 </font>
1852 </td></tr></TABLE>
1853 </FORM>
1854 <!-- SiteSearch Google -->";
1855         $cachederror = "The following is a cached copy of the requested page, and may not be up to date. ";
1856
1857
1858         if( !headers_sent() ) {
1859                 header( 'HTTP/1.0 500 Internal Server Error' );
1860                 header( 'Content-type: text/html; charset='.$wgOutputEncoding );
1861                 /* Don't cache error pages!  They cause no end of trouble... */
1862                 header( 'Cache-control: none' );
1863                 header( 'Pragma: nocache' );
1864         }
1865
1866         # No database access
1867         if ( is_object( $wgMessageCache ) ) {
1868                 $wgMessageCache->disable();
1869         }
1870
1871         if ( trim( $error ) == '' ) {
1872                 $error = $this->mServer;
1873         }
1874
1875         wfLogDBError( "Connection error: $error\n" );
1876
1877         $text = str_replace( '$1', $error, $noconnect );
1878         $text .= wfGetSiteNotice();
1879
1880         if($wgUseFileCache) {
1881                 if($wgTitle) {
1882                         $t =& $wgTitle;
1883                 } else {
1884                         if($title) {
1885                                 $t = Title::newFromURL( $title );
1886                         } elseif (@/**/$_REQUEST['search']) {
1887                                 $search = $_REQUEST['search'];
1888                                 echo $searchdisabled;
1889                                 echo str_replace( array( '$1', '$2' ), array( htmlspecialchars( $search ),
1890                                   $wgInputEncoding ), $googlesearch );
1891                                 wfErrorExit();
1892                         } else {
1893                                 $t = Title::newFromText( $mainpage );
1894                         }
1895                 }
1896
1897                 $cache = new CacheManager( $t );
1898                 if( $cache->isFileCached() ) {
1899                         $msg = '<p style="color: red"><b>'.$msg."<br />\n" .
1900                                 $cachederror . "</b></p>\n";
1901
1902                         $tag = '<div id="article">';
1903                         $text = str_replace(
1904                                 $tag,
1905                                 $tag . $msg,
1906                                 $cache->fetchPageText() );
1907                 }
1908         }
1909
1910         echo $text;
1911         wfErrorExit();
1912 }
1913
1914 ?>