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