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