includes/db/Database.php

   1 <?php
   2 /**
   3  * @defgroup Database Database
   4  *
   5  * @file
   6  * @ingroup Database
   7  * This file deals with database interface functions
   8  * and query specifics/optimisations
   9  */
  10
  11 /** Number of times to re-try an operation in case of deadlock */
  12 define( 'DEADLOCK_TRIES', 4 );
  13 /** Minimum time to wait before retry, in microseconds */
  14 define( 'DEADLOCK_DELAY_MIN', 500000 );
  15 /** Maximum time to wait before retry */
  16 define( 'DEADLOCK_DELAY_MAX', 1500000 );
  17
  18 /**
  19  * Base interface for all DBMS-specific code. At a bare minimum, all of the
  20  * following must be implemented to support MediaWiki
  21  *
  22  * @file
  23  * @ingroup Database
  24  */
  25 interface DatabaseType {
  26         /**
  27          * Get the type of the DBMS, as it appears in $wgDBtype.
  28          *
  29          * @return string
  30          */
  31         public function getType();
  32
  33         /**
  34          * Open a connection to the database. Usually aborts on failure
  35          * If the failFunction is set to a non-zero integer, returns success
  36          *
  37          * @param $server String: database server host
  38          * @param $user String: database user name
  39          * @param $password String: database user password
  40          * @param $dbName String: database name
  41          * @return bool
  42          * @throws DBConnectionError
  43          */
  44         public function open( $server, $user, $password, $dbName );
  45
  46         /**
  47          * The DBMS-dependent part of query()
  48          * @todo @fixme Make this private someday
  49          *
  50          * @param  $sql String: SQL query.
  51          * @return Result object to feed to fetchObject, fetchRow, ...; or false on failure
  52          * @private
  53          */
  54         /*private*/ function doQuery( $sql );
  55
  56         /**
  57          * Fetch the next row from the given result object, in object form.
  58          * Fields can be retrieved with $row->fieldname, with fields acting like
  59          * member variables.
  60          *
  61          * @param $res SQL result object as returned from DatabaseBase::query(), etc.
  62          * @return Row object
  63          * @throws DBUnexpectedError Thrown if the database returns an error
  64          */
  65         public function fetchObject( $res );
  66
  67         /**
  68          * Fetch the next row from the given result object, in associative array
  69          * form.  Fields are retrieved with $row['fieldname'].
  70          *
  71          * @param $res SQL result object as returned from DatabaseBase::query(), etc.
  72          * @return Row object
  73          * @throws DBUnexpectedError Thrown if the database returns an error
  74          */
  75         public function fetchRow( $res );
  76
  77         /**
  78          * Get the number of rows in a result object
  79          *
  80          * @param $res Mixed: A SQL result
  81          * @return int
  82          */
  83         public function numRows( $res );
  84
  85         /**
  86          * Get the number of fields in a result object
  87          * @see http://www.php.net/mysql_num_fields
  88          *
  89          * @param $res Mixed: A SQL result
  90          * @return int
  91          */
  92         public function numFields( $res );
  93
  94         /**
  95          * Get a field name in a result object
  96          * @see http://www.php.net/mysql_field_name
  97          *
  98          * @param $res Mixed: A SQL result
  99          * @param $n Integer
 100          * @return string
 101          */
 102         public function fieldName( $res, $n );
 103
 104         /**
 105          * Get the inserted value of an auto-increment row
 106          *
 107          * The value inserted should be fetched from nextSequenceValue()
 108          *
 109          * Example:
 110          * $id = $dbw->nextSequenceValue('page_page_id_seq');
 111          * $dbw->insert('page',array('page_id' => $id));
 112          * $id = $dbw->insertId();
 113          *
 114          * @return int
 115          */
 116         public function insertId();
 117
 118         /**
 119          * Change the position of the cursor in a result object
 120          * @see http://www.php.net/mysql_data_seek
 121          *
 122          * @param $res Mixed: A SQL result
 123          * @param $row Mixed: Either MySQL row or ResultWrapper
 124          */
 125         public function dataSeek( $res, $row );
 126
 127         /**
 128          * Get the last error number
 129          * @see http://www.php.net/mysql_errno
 130          *
 131          * @return int
 132          */
 133         public function lastErrno();
 134
 135         /**
 136          * Get a description of the last error
 137          * @see http://www.php.net/mysql_error
 138          *
 139          * @return string
 140          */
 141         public function lastError();
 142
 143         /**
 144          * mysql_fetch_field() wrapper
 145          * Returns false if the field doesn't exist
 146          *
 147          * @param $table string: table name
 148          * @param $field string: field name
 149          */
 150         public function fieldInfo( $table, $field );
 151
 152         /**
 153          * Get the number of rows affected by the last write query
 154          * @see http://www.php.net/mysql_affected_rows
 155          *
 156          * @return int
 157          */
 158         public function affectedRows();
 159
 160         /**
 161          * Wrapper for addslashes()
 162          *
 163          * @param $s string: to be slashed.
 164          * @return string: slashed string.
 165          */
 166         public function strencode( $s );
 167
 168         /**
 169          * Returns a wikitext link to the DB's website, e.g.,
 170          *     return "[http://www.mysql.com/ MySQL]";
 171          * Should at least contain plain text, if for some reason
 172          * your database has no website.
 173          *
 174          * @return string: wikitext of a link to the server software's web site
 175          */
 176         public static function getSoftwareLink();
 177
 178         /**
 179          * A string describing the current software version, like from
 180          * mysql_get_server_info().  Will be listed on Special:Version, etc.
 181          *
 182          * @return string: Version information from the database
 183          */
 184         public function getServerVersion();
 185 }
 186
 187 /**
 188  * Database abstraction object
 189  * @ingroup Database
 190  */
 191 abstract class DatabaseBase implements DatabaseType {
 192
 193 # ------------------------------------------------------------------------------
 194 # Variables
 195 # ------------------------------------------------------------------------------
 196
 197         protected $mLastQuery = '';
 198         protected $mDoneWrites = false;
 199         protected $mPHPError = false;
 200
 201         protected $mServer, $mUser, $mPassword, $mConn = null, $mDBname;
 202         protected $mOpened = false;
 203
 204         protected $mFailFunction;
 205         protected $mTablePrefix;
 206         protected $mFlags;
 207         protected $mTrxLevel = 0;
 208         protected $mErrorCount = 0;
 209         protected $mLBInfo = array();
 210         protected $mFakeSlaveLag = null, $mFakeMaster = false;
 211         protected $mDefaultBigSelects = null;
 212
 213 # ------------------------------------------------------------------------------
 214 # Accessors
 215 # ------------------------------------------------------------------------------
 216         # These optionally set a variable and return the previous state
 217
 218         /**
 219          * Fail function, takes a Database as a parameter
 220          * Set to false for default, 1 for ignore errors
 221          */
 222         function failFunction( $function = null ) {
 223                 return wfSetVar( $this->mFailFunction, $function );
 224         }
 225
 226         /**
 227          * Boolean, controls output of large amounts of debug information
 228          */
 229         function debug( $debug = null ) {
 230                 return wfSetBit( $this->mFlags, DBO_DEBUG, $debug );
 231         }
 232
 233         /**
 234          * Turns buffering of SQL result sets on (true) or off (false).
 235          * Default is "on" and it should not be changed without good reasons.
 236          */
 237         function bufferResults( $buffer = null ) {
 238                 if ( is_null( $buffer ) ) {
 239                         return !(bool)( $this->mFlags & DBO_NOBUFFER );
 240                 } else {
 241                         return !wfSetBit( $this->mFlags, DBO_NOBUFFER, !$buffer );
 242                 }
 243         }
 244
 245         /**
 246          * Turns on (false) or off (true) the automatic generation and sending
 247          * of a "we're sorry, but there has been a database error" page on
 248          * database errors. Default is on (false). When turned off, the
 249          * code should use lastErrno() and lastError() to handle the
 250          * situation as appropriate.
 251          */
 252         function ignoreErrors( $ignoreErrors = null ) {
 253                 return wfSetBit( $this->mFlags, DBO_IGNORE, $ignoreErrors );
 254         }
 255
 256         /**
 257          * The current depth of nested transactions
 258          * @param $level Integer: , default NULL.
 259          */
 260         function trxLevel( $level = null ) {
 261                 return wfSetVar( $this->mTrxLevel, $level );
 262         }
 263
 264         /**
 265          * Number of errors logged, only useful when errors are ignored
 266          */
 267         function errorCount( $count = null ) {
 268                 return wfSetVar( $this->mErrorCount, $count );
 269         }
 270
 271         function tablePrefix( $prefix = null ) {
 272                 return wfSetVar( $this->mTablePrefix, $prefix );
 273         }
 274
 275         /**
 276          * Properties passed down from the server info array of the load balancer
 277          */
 278         function getLBInfo( $name = null ) {
 279                 if ( is_null( $name ) ) {
 280                         return $this->mLBInfo;
 281                 } else {
 282                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 283                                 return $this->mLBInfo[$name];
 284                         } else {
 285                                 return null;
 286                         }
 287                 }
 288         }
 289
 290         function setLBInfo( $name, $value = null ) {
 291                 if ( is_null( $value ) ) {
 292                         $this->mLBInfo = $name;
 293                 } else {
 294                         $this->mLBInfo[$name] = $value;
 295                 }
 296         }
 297
 298         /**
 299          * Set lag time in seconds for a fake slave
 300          */
 301         function setFakeSlaveLag( $lag ) {
 302                 $this->mFakeSlaveLag = $lag;
 303         }
 304
 305         /**
 306          * Make this connection a fake master
 307          */
 308         function setFakeMaster( $enabled = true ) {
 309                 $this->mFakeMaster = $enabled;
 310         }
 311
 312         /**
 313          * Returns true if this database supports (and uses) cascading deletes
 314          */
 315         function cascadingDeletes() {
 316                 return false;
 317         }
 318
 319         /**
 320          * Returns true if this database supports (and uses) triggers (e.g. on the page table)
 321          */
 322         function cleanupTriggers() {
 323                 return false;
 324         }
 325
 326         /**
 327          * Returns true if this database is strict about what can be put into an IP field.
 328          * Specifically, it uses a NULL value instead of an empty string.
 329          */
 330         function strictIPs() {
 331                 return false;
 332         }
 333
 334         /**
 335          * Returns true if this database uses timestamps rather than integers
 336         */
 337         function realTimestamps() {
 338                 return false;
 339         }
 340
 341         /**
 342          * Returns true if this database does an implicit sort when doing GROUP BY
 343          */
 344         function implicitGroupby() {
 345                 return true;
 346         }
 347
 348         /**
 349          * Returns true if this database does an implicit order by when the column has an index
 350          * For example: SELECT page_title FROM page LIMIT 1
 351          */
 352         function implicitOrderby() {
 353                 return true;
 354         }
 355
 356         /**
 357          * Returns true if this database requires that SELECT DISTINCT queries require that all
 358            ORDER BY expressions occur in the SELECT list per the SQL92 standard
 359          */
 360         function standardSelectDistinct() {
 361                 return true;
 362         }
 363
 364         /**
 365          * Returns true if this database can do a native search on IP columns
 366          * e.g. this works as expected: .. WHERE rc_ip = '127.42.12.102/32';
 367          */
 368         function searchableIPs() {
 369                 return false;
 370         }
 371
 372         /**
 373          * Returns true if this database can use functional indexes
 374          */
 375         function functionalIndexes() {
 376                 return false;
 377         }
 378
 379         /**
 380          * Return the last query that went through DatabaseBase::query()
 381          * @return String
 382          */
 383         function lastQuery() { return $this->mLastQuery; }
 384
 385
 386         /**
 387          * Returns true if the connection may have been used for write queries.
 388          * Should return true if unsure.
 389          */
 390         function doneWrites() { return $this->mDoneWrites; }
 391
 392         /**
 393          * Is a connection to the database open?
 394          * @return Boolean
 395          */
 396         function isOpen() { return $this->mOpened; }
 397
 398         /**
 399          * Set a flag for this connection
 400          *
 401          * @param $flag Integer: DBO_* constants from Defines.php:
 402          *   - DBO_DEBUG: output some debug info (same as debug())
 403          *   - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
 404          *   - DBO_IGNORE: ignore errors (same as ignoreErrors())
 405          *   - DBO_TRX: automatically start transactions
 406          *   - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
 407          *       and removes it in command line mode
 408          *   - DBO_PERSISTENT: use persistant database connection
 409          */
 410         function setFlag( $flag ) {
 411                 $this->mFlags |= $flag;
 412         }
 413
 414         /**
 415          * Clear a flag for this connection
 416          *
 417          * @param $flag: same as setFlag()'s $flag param
 418          */
 419         function clearFlag( $flag ) {
 420                 $this->mFlags &= ~$flag;
 421         }
 422
 423         /**
 424          * Returns a boolean whether the flag $flag is set for this connection
 425          *
 426          * @param $flag: same as setFlag()'s $flag param
 427          * @return Boolean
 428          */
 429         function getFlag( $flag ) {
 430                 return !!( $this->mFlags & $flag );
 431         }
 432
 433         /**
 434          * General read-only accessor
 435          */
 436         function getProperty( $name ) {
 437                 return $this->$name;
 438         }
 439
 440         function getWikiID() {
 441                 if ( $this->mTablePrefix ) {
 442                         return "{$this->mDBname}-{$this->mTablePrefix}";
 443                 } else {
 444                         return $this->mDBname;
 445                 }
 446         }
 447
 448         /**
 449          * Return a path to the DBMS-specific schema, otherwise default to tables.sql
 450          */
 451         public function getSchema() {
 452                 global $IP;
 453                 if ( file_exists( "$IP/maintenance/" . $this->getType() . "/tables.sql" ) ) {
 454                         return "$IP/maintenance/" . $this->getType() . "/tables.sql";
 455                 } else {
 456                         return "$IP/maintenance/tables.sql";
 457                 }
 458         }
 459
 460 # ------------------------------------------------------------------------------
 461 # Other functions
 462 # ------------------------------------------------------------------------------
 463
 464         /**
 465          * Constructor.
 466          * @param $server String: database server host
 467          * @param $user String: database user name
 468          * @param $password String: database user password
 469          * @param $dbName String: database name
 470          * @param $failFunction
 471          * @param $flags
 472          * @param $tablePrefix String: database table prefixes. By default use the prefix gave in LocalSettings.php
 473          */
 474         function __construct( $server = false, $user = false, $password = false, $dbName = false,
 475                 $failFunction = false, $flags = 0, $tablePrefix = 'get from global'
 476         ) {
 477                 global $wgOut, $wgDBprefix, $wgCommandLineMode;
 478
 479                 # Can't get a reference if it hasn't been set yet
 480                 if ( !isset( $wgOut ) ) {
 481                         $wgOut = null;
 482                 }
 483
 484                 $this->mFailFunction = $failFunction;
 485                 $this->mFlags = $flags;
 486
 487                 if ( $this->mFlags & DBO_DEFAULT ) {
 488                         if ( $wgCommandLineMode ) {
 489                                 $this->mFlags &= ~DBO_TRX;
 490                         } else {
 491                                 $this->mFlags |= DBO_TRX;
 492                         }
 493                 }
 494
 495                 /*
 496                 // Faster read-only access
 497                 if ( wfReadOnly() ) {
 498                         $this->mFlags |= DBO_PERSISTENT;
 499                         $this->mFlags &= ~DBO_TRX;
 500                 }*/
 501
 502                 /** Get the default table prefix*/
 503                 if ( $tablePrefix == 'get from global' ) {
 504                         $this->mTablePrefix = $wgDBprefix;
 505                 } else {
 506                         $this->mTablePrefix = $tablePrefix;
 507                 }
 508
 509                 if ( $server ) {
 510                         $this->open( $server, $user, $password, $dbName );
 511                 }
 512         }
 513
 514         /**
 515          * Same as new DatabaseMysql( ... ), kept for backward compatibility
 516          * @param $server String: database server host
 517          * @param $user String: database user name
 518          * @param $password String: database user password
 519          * @param $dbName String: database name
 520          * @param failFunction
 521          * @param $flags
 522          */
 523         static function newFromParams( $server, $user, $password, $dbName, $failFunction = false, $flags = 0 ) {
 524                 wfDeprecated( __METHOD__ );
 525                 return new DatabaseMysql( $server, $user, $password, $dbName, $failFunction, $flags );
 526         }
 527
 528         protected function installErrorHandler() {
 529                 $this->mPHPError = false;
 530                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 531                 set_error_handler( array( $this, 'connectionErrorHandler' ) );
 532         }
 533
 534         protected function restoreErrorHandler() {
 535                 restore_error_handler();
 536                 if ( $this->htmlErrors !== false ) {
 537                         ini_set( 'html_errors', $this->htmlErrors );
 538                 }
 539                 if ( $this->mPHPError ) {
 540                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 541                         $error = preg_replace( '!^.*?:(.*)$!', '$1', $error );
 542                         return $error;
 543                 } else {
 544                         return false;
 545                 }
 546         }
 547
 548         protected function connectionErrorHandler( $errno,  $errstr ) {
 549                 $this->mPHPError = $errstr;
 550         }
 551
 552         /**
 553          * Closes a database connection.
 554          * if it is open : commits any open transactions
 555          *
 556          * @return Bool operation success. true if already closed.
 557          */
 558         function close() {
 559                 # Stub, should probably be overridden
 560                 return true;
 561         }
 562
 563         /**
 564          * @param $error String: fallback error message, used if none is given by DB
 565          */
 566         function reportConnectionError( $error = 'Unknown error' ) {
 567                 $myError = $this->lastError();
 568                 if ( $myError ) {
 569                         $error = $myError;
 570                 }
 571
 572                 if ( $this->mFailFunction ) {
 573                         # Legacy error handling method
 574                         if ( !is_int( $this->mFailFunction ) ) {
 575                                 $ff = $this->mFailFunction;
 576                                 $ff( $this, $error );
 577                         }
 578                 } else {
 579                         # New method
 580                         throw new DBConnectionError( $this, $error );
 581                 }
 582         }
 583
 584         /**
 585          * Determine whether a query writes to the DB.
 586          * Should return true if unsure.
 587          */
 588         function isWriteQuery( $sql ) {
 589                 return !preg_match( '/^(?:SELECT|BEGIN|COMMIT|SET|SHOW|\(SELECT)\b/i', $sql );
 590         }
 591
 592         /**
 593          * Usually aborts on failure.  If errors are explicitly ignored, returns success.
 594          *
 595          * @param  $sql        String: SQL query
 596          * @param  $fname      String: Name of the calling function, for profiling/SHOW PROCESSLIST
 597          *     comment (you can use __METHOD__ or add some extra info)
 598          * @param  $tempIgnore Boolean:   Whether to avoid throwing an exception on errors...
 599          *     maybe best to catch the exception instead?
 600          * @return true for a successful write query, ResultWrapper object for a successful read query,
 601          *     or false on failure if $tempIgnore set
 602          * @throws DBQueryError Thrown when the database returns an error of any kind
 603          */
 604         public function query( $sql, $fname = '', $tempIgnore = false ) {
 605                 global $wgProfiler;
 606
 607                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 608                 if ( isset( $wgProfiler ) ) {
 609                         # generalizeSQL will probably cut down the query to reasonable
 610                         # logging size most of the time. The substr is really just a sanity check.
 611
 612                         # Who's been wasting my precious column space? -- TS
 613                         # $profName = 'query: ' . $fname . ' ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 614
 615                         if ( $isMaster ) {
 616                                 $queryProf = 'query-m: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 617                                 $totalProf = 'DatabaseBase::query-master';
 618                         } else {
 619                                 $queryProf = 'query: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 620                                 $totalProf = 'DatabaseBase::query';
 621                         }
 622
 623                         wfProfileIn( $totalProf );
 624                         wfProfileIn( $queryProf );
 625                 }
 626
 627                 $this->mLastQuery = $sql;
 628                 if ( !$this->mDoneWrites && $this->isWriteQuery( $sql ) ) {
 629                         // Set a flag indicating that writes have been done
 630                         wfDebug( __METHOD__ . ": Writes done: $sql\n" );
 631                         $this->mDoneWrites = true;
 632                 }
 633
 634                 # Add a comment for easy SHOW PROCESSLIST interpretation
 635                 # if ( $fname ) {
 636                         global $wgUser;
 637                         if ( is_object( $wgUser ) && !( $wgUser instanceof StubObject ) ) {
 638                                 $userName = $wgUser->getName();
 639                                 if ( mb_strlen( $userName ) > 15 ) {
 640                                         $userName = mb_substr( $userName, 0, 15 ) . '...';
 641                                 }
 642                                 $userName = str_replace( '/', '', $userName );
 643                         } else {
 644                                 $userName = '';
 645                         }
 646                         $commentedSql = preg_replace( '/\s/', " /* $fname $userName */ ", $sql, 1 );
 647                 # } else {
 648                 #       $commentedSql = $sql;
 649                 # }
 650
 651                 # If DBO_TRX is set, start a transaction
 652                 if ( ( $this->mFlags & DBO_TRX ) && !$this->trxLevel() &&
 653                         $sql != 'BEGIN' && $sql != 'COMMIT' && $sql != 'ROLLBACK' ) {
 654                         // avoid establishing transactions for SHOW and SET statements too -
 655                         // that would delay transaction initializations to once connection
 656                         // is really used by application
 657                         $sqlstart = substr( $sql, 0, 10 ); // very much worth it, benchmark certified(tm)
 658                         if ( strpos( $sqlstart, "SHOW " ) !== 0 and strpos( $sqlstart, "SET " ) !== 0 )
 659                                 $this->begin();
 660                 }
 661
 662                 if ( $this->debug() ) {
 663                         static $cnt = 0;
 664
 665                         $cnt++;
 666                         $sqlx = substr( $commentedSql, 0, 500 );
 667                         $sqlx = strtr( $sqlx, "\t\n", '  ' );
 668
 669                         if ( $isMaster ) {
 670                                 wfDebug( "Query $cnt (master): $sqlx\n" );
 671                         } else {
 672                                 wfDebug( "Query $cnt (slave): $sqlx\n" );
 673                         }
 674                 }
 675
 676                 if ( istainted( $sql ) & TC_MYSQL ) {
 677                         throw new MWException( 'Tainted query found' );
 678                 }
 679
 680                 # Do the query and handle errors
 681                 $ret = $this->doQuery( $commentedSql );
 682
 683                 # Try reconnecting if the connection was lost
 684                 if ( false === $ret && $this->wasErrorReissuable() ) {
 685                         # Transaction is gone, like it or not
 686                         $this->mTrxLevel = 0;
 687                         wfDebug( "Connection lost, reconnecting...\n" );
 688
 689                         if ( $this->ping() ) {
 690                                 wfDebug( "Reconnected\n" );
 691                                 $sqlx = substr( $commentedSql, 0, 500 );
 692                                 $sqlx = strtr( $sqlx, "\t\n", '  ' );
 693                                 global $wgRequestTime;
 694                                 $elapsed = round( microtime( true ) - $wgRequestTime, 3 );
 695                                 wfLogDBError( "Connection lost and reconnected after {$elapsed}s, query: $sqlx\n" );
 696                                 $ret = $this->doQuery( $commentedSql );
 697                         } else {
 698                                 wfDebug( "Failed\n" );
 699                         }
 700                 }
 701
 702                 if ( false === $ret ) {
 703                         $this->reportQueryError( $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 704                 }
 705
 706                 if ( isset( $wgProfiler ) ) {
 707                         wfProfileOut( $queryProf );
 708                         wfProfileOut( $totalProf );
 709                 }
 710
 711                 return $this->resultObject( $ret );
 712         }
 713
 714         /**
 715          * @param $error String
 716          * @param $errno Integer
 717          * @param $sql String
 718          * @param $fname String
 719          * @param $tempIgnore Boolean
 720          */
 721         function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 722                 # Ignore errors during error handling to avoid infinite recursion
 723                 $ignore = $this->ignoreErrors( true );
 724                 ++$this->mErrorCount;
 725
 726                 if ( $ignore || $tempIgnore ) {
 727                         wfDebug( "SQL ERROR (ignored): $error\n" );
 728                         $this->ignoreErrors( $ignore );
 729                 } else {
 730                         $sql1line = str_replace( "\n", "\\n", $sql );
 731                         wfLogDBError( "$fname\t{$this->mServer}\t$errno\t$error\t$sql1line\n" );
 732                         wfDebug( "SQL ERROR: " . $error . "\n" );
 733                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
 734                 }
 735         }
 736
 737
 738         /**
 739          * Intended to be compatible with the PEAR::DB wrapper functions.
 740          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
 741          *
 742          * ? = scalar value, quoted as necessary
 743          * ! = raw SQL bit (a function for instance)
 744          * & = filename; reads the file and inserts as a blob
 745          *     (we don't use this though...)
 746          */
 747         function prepare( $sql, $func = 'DatabaseBase::prepare' ) {
 748                 /* MySQL doesn't support prepared statements (yet), so just
 749                    pack up the query for reference. We'll manually replace
 750                    the bits later. */
 751                 return array( 'query' => $sql, 'func' => $func );
 752         }
 753
 754         function freePrepared( $prepared ) {
 755                 /* No-op by default */
 756         }
 757
 758         /**
 759          * Execute a prepared query with the various arguments
 760          * @param $prepared String: the prepared sql
 761          * @param $args Mixed: Either an array here, or put scalars as varargs
 762          */
 763         function execute( $prepared, $args = null ) {
 764                 if ( !is_array( $args ) ) {
 765                         # Pull the var args
 766                         $args = func_get_args();
 767                         array_shift( $args );
 768                 }
 769
 770                 $sql = $this->fillPrepared( $prepared['query'], $args );
 771
 772                 return $this->query( $sql, $prepared['func'] );
 773         }
 774
 775         /**
 776          * Prepare & execute an SQL statement, quoting and inserting arguments
 777          * in the appropriate places.
 778          * @param $query String
 779          * @param $args ...
 780          */
 781         function safeQuery( $query, $args = null ) {
 782                 $prepared = $this->prepare( $query, 'DatabaseBase::safeQuery' );
 783
 784                 if ( !is_array( $args ) ) {
 785                         # Pull the var args
 786                         $args = func_get_args();
 787                         array_shift( $args );
 788                 }
 789
 790                 $retval = $this->execute( $prepared, $args );
 791                 $this->freePrepared( $prepared );
 792
 793                 return $retval;
 794         }
 795
 796         /**
 797          * For faking prepared SQL statements on DBs that don't support
 798          * it directly.
 799          * @param $preparedQuery String: a 'preparable' SQL statement
 800          * @param $args Array of arguments to fill it with
 801          * @return string executable SQL
 802          */
 803         function fillPrepared( $preparedQuery, $args ) {
 804                 reset( $args );
 805                 $this->preparedArgs =& $args;
 806
 807                 return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
 808                         array( &$this, 'fillPreparedArg' ), $preparedQuery );
 809         }
 810
 811         /**
 812          * preg_callback func for fillPrepared()
 813          * The arguments should be in $this->preparedArgs and must not be touched
 814          * while we're doing this.
 815          *
 816          * @param $matches Array
 817          * @return String
 818          * @private
 819          */
 820         function fillPreparedArg( $matches ) {
 821                 switch( $matches[1] ) {
 822                         case '\\?': return '?';
 823                         case '\\!': return '!';
 824                         case '\\&': return '&';
 825                 }
 826
 827                 list( /* $n */ , $arg ) = each( $this->preparedArgs );
 828
 829                 switch( $matches[1] ) {
 830                         case '?': return $this->addQuotes( $arg );
 831                         case '!': return $arg;
 832                         case '&':
 833                                 # return $this->addQuotes( file_get_contents( $arg ) );
 834                                 throw new DBUnexpectedError( $this, '& mode is not implemented. If it\'s really needed, uncomment the line above.' );
 835                         default:
 836                                 throw new DBUnexpectedError( $this, 'Received invalid match. This should never happen!' );
 837                 }
 838         }
 839
 840         /**
 841          * Free a result object
 842          * @param $res Mixed: A SQL result
 843          */
 844         function freeResult( $res ) {
 845                 # Stub.  Might not really need to be overridden, since results should
 846                 # be freed by PHP when the variable goes out of scope anyway.
 847         }
 848
 849         /**
 850          * Simple UPDATE wrapper
 851          * Usually aborts on failure
 852          * If errors are explicitly ignored, returns success
 853          *
 854          * This function exists for historical reasons, DatabaseBase::update() has a more standard
 855          * calling convention and feature set
 856          */
 857         function set( $table, $var, $value, $cond, $fname = 'DatabaseBase::set' ) {
 858                 $table = $this->tableName( $table );
 859                 $sql = "UPDATE $table SET $var = '" .
 860                   $this->strencode( $value ) . "' WHERE ($cond)";
 861
 862                 return (bool)$this->query( $sql, $fname );
 863         }
 864
 865         /**
 866          * Simple SELECT wrapper, returns a single field, input must be encoded
 867          * Usually aborts on failure
 868          * If errors are explicitly ignored, returns FALSE on failure
 869          */
 870         function selectField( $table, $var, $cond = '', $fname = 'DatabaseBase::selectField', $options = array() ) {
 871                 if ( !is_array( $options ) ) {
 872                         $options = array( $options );
 873                 }
 874
 875                 $options['LIMIT'] = 1;
 876
 877                 $res = $this->select( $table, $var, $cond, $fname, $options );
 878
 879                 if ( $res === false || !$this->numRows( $res ) ) {
 880                         return false;
 881                 }
 882
 883                 $row = $this->fetchRow( $res );
 884
 885                 if ( $row !== false ) {
 886                         return reset( $row );
 887                 } else {
 888                         return false;
 889                 }
 890         }
 891
 892         /**
 893          * Returns an optional USE INDEX clause to go after the table, and a
 894          * string to go at the end of the query
 895          *
 896          * @private
 897          *
 898          * @param $options Array: associative array of options to be turned into
 899          *              an SQL query, valid keys are listed in the function.
 900          * @return Array
 901          */
 902         function makeSelectOptions( $options ) {
 903                 $preLimitTail = $postLimitTail = '';
 904                 $startOpts = '';
 905
 906                 $noKeyOptions = array();
 907
 908                 foreach ( $options as $key => $option ) {
 909                         if ( is_numeric( $key ) ) {
 910                                 $noKeyOptions[$option] = true;
 911                         }
 912                 }
 913
 914                 if ( isset( $options['GROUP BY'] ) ) {
 915                         $preLimitTail .= " GROUP BY {$options['GROUP BY']}";
 916                 }
 917
 918                 if ( isset( $options['HAVING'] ) ) {
 919                         $preLimitTail .= " HAVING {$options['HAVING']}";
 920                 }
 921
 922                 if ( isset( $options['ORDER BY'] ) ) {
 923                         $preLimitTail .= " ORDER BY {$options['ORDER BY']}";
 924                 }
 925
 926                 // if (isset($options['LIMIT'])) {
 927                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
 928                 //              isset($options['OFFSET']) ? $options['OFFSET']
 929                 //              : false);
 930                 // }
 931
 932                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
 933                         $postLimitTail .= ' FOR UPDATE';
 934                 }
 935
 936                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
 937                         $postLimitTail .= ' LOCK IN SHARE MODE';
 938                 }
 939
 940                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
 941                         $startOpts .= 'DISTINCT';
 942                 }
 943
 944                 # Various MySQL extensions
 945                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
 946                         $startOpts .= ' /*! STRAIGHT_JOIN */';
 947                 }
 948
 949                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
 950                         $startOpts .= ' HIGH_PRIORITY';
 951                 }
 952
 953                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
 954                         $startOpts .= ' SQL_BIG_RESULT';
 955                 }
 956
 957                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
 958                         $startOpts .= ' SQL_BUFFER_RESULT';
 959                 }
 960
 961                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
 962                         $startOpts .= ' SQL_SMALL_RESULT';
 963                 }
 964
 965                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
 966                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
 967                 }
 968
 969                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
 970                         $startOpts .= ' SQL_CACHE';
 971                 }
 972
 973                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
 974                         $startOpts .= ' SQL_NO_CACHE';
 975                 }
 976
 977                 if ( isset( $options['USE INDEX'] ) && ! is_array( $options['USE INDEX'] ) ) {
 978                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
 979                 } else {
 980                         $useIndex = '';
 981                 }
 982
 983                 return array( $startOpts, $useIndex, $preLimitTail, $postLimitTail );
 984         }
 985
 986         /**
 987          * SELECT wrapper
 988          *
 989          * @param $table   Mixed:  Array or string, table name(s) (prefix auto-added)
 990          * @param $vars    Mixed:  Array or string, field name(s) to be retrieved
 991          * @param $conds   Mixed:  Array or string, condition(s) for WHERE
 992          * @param $fname   String: Calling function name (use __METHOD__) for logs/profiling
 993          * @param $options Array:  Associative array of options (e.g. array('GROUP BY' => 'page_title')),
 994          *                         see DatabaseBase::makeSelectOptions code for list of supported stuff
 995          * @param $join_conds Array: Associative array of table join conditions (optional)
 996          *                           (e.g. array( 'page' => array('LEFT JOIN','page_latest=rev_id') )
 997          * @return mixed Database result resource (feed to DatabaseBase::fetchObject or whatever), or false on failure
 998          */
 999         function select( $table, $vars, $conds = '', $fname = 'DatabaseBase::select', $options = array(), $join_conds = array() ) {
1000                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1001
1002                 return $this->query( $sql, $fname );
1003         }
1004
1005         /**
1006          * SELECT wrapper
1007          *
1008          * @param $table   Mixed:  Array or string, table name(s) (prefix auto-added)
1009          * @param $vars    Mixed:  Array or string, field name(s) to be retrieved
1010          * @param $conds   Mixed:  Array or string, condition(s) for WHERE
1011          * @param $fname   String: Calling function name (use __METHOD__) for logs/profiling
1012          * @param $options Array:  Associative array of options (e.g. array('GROUP BY' => 'page_title')),
1013          *                         see DatabaseBase::makeSelectOptions code for list of supported stuff
1014          * @param $join_conds Array: Associative array of table join conditions (optional)
1015          *                           (e.g. array( 'page' => array('LEFT JOIN','page_latest=rev_id') )
1016          * @return string, the SQL text
1017          */
1018         function selectSQLText( $table, $vars, $conds = '', $fname = 'DatabaseBase::select', $options = array(), $join_conds = array() ) {
1019                 if ( is_array( $vars ) ) {
1020                         $vars = implode( ',', $vars );
1021                 }
1022
1023                 if ( !is_array( $options ) ) {
1024                         $options = array( $options );
1025                 }
1026
1027                 if ( is_array( $table ) ) {
1028                         if ( !empty( $join_conds ) || ( isset( $options['USE INDEX'] ) && is_array( @$options['USE INDEX'] ) ) ) {
1029                                 $from = ' FROM ' . $this->tableNamesWithUseIndexOrJOIN( $table, @$options['USE INDEX'], $join_conds );
1030                         } else {
1031                                 $from = ' FROM ' . implode( ',', array_map( array( &$this, 'tableName' ), $table ) );
1032                         }
1033                 } elseif ( $table != '' ) {
1034                         if ( $table { 0 } == ' ' ) {
1035                                 $from = ' FROM ' . $table;
1036                         } else {
1037                                 $from = ' FROM ' . $this->tableName( $table );
1038                         }
1039                 } else {
1040                         $from = '';
1041                 }
1042
1043                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail ) = $this->makeSelectOptions( $options );
1044
1045                 if ( !empty( $conds ) ) {
1046                         if ( is_array( $conds ) ) {
1047                                 $conds = $this->makeList( $conds, LIST_AND );
1048                         }
1049                         $sql = "SELECT $startOpts $vars $from $useIndex WHERE $conds $preLimitTail";
1050                 } else {
1051                         $sql = "SELECT $startOpts $vars $from $useIndex $preLimitTail";
1052                 }
1053
1054                 if ( isset( $options['LIMIT'] ) )
1055                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1056                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1057                 $sql = "$sql $postLimitTail";
1058
1059                 if ( isset( $options['EXPLAIN'] ) ) {
1060                         $sql = 'EXPLAIN ' . $sql;
1061                 }
1062
1063                 return $sql;
1064         }
1065
1066         /**
1067          * Single row SELECT wrapper
1068          * Aborts or returns FALSE on error
1069          *
1070          * @param $table String: table name
1071          * @param $vars String: the selected variables
1072          * @param $conds Array: a condition map, terms are ANDed together.
1073          *   Items with numeric keys are taken to be literal conditions
1074          * Takes an array of selected variables, and a condition map, which is ANDed
1075          * e.g: selectRow( "page", array( "page_id" ), array( "page_namespace" =>
1076          * NS_MAIN, "page_title" => "Astronomy" ) )   would return an object where
1077          * $obj- >page_id is the ID of the Astronomy article
1078          * @param $fname String: Calling function name
1079          * @param $options Array
1080          * @param $join_conds Array
1081          *
1082          * @todo migrate documentation to phpdocumentor format
1083          */
1084         function selectRow( $table, $vars, $conds, $fname = 'DatabaseBase::selectRow', $options = array(), $join_conds = array() ) {
1085                 $options['LIMIT'] = 1;
1086                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1087
1088                 if ( $res === false ) {
1089                         return false;
1090                 }
1091
1092                 if ( !$this->numRows( $res ) ) {
1093                         return false;
1094                 }
1095
1096                 $obj = $this->fetchObject( $res );
1097
1098                 return $obj;
1099         }
1100
1101         /**
1102          * Estimate rows in dataset
1103          * Returns estimated count - not necessarily an accurate estimate across different databases,
1104          * so use sparingly
1105          * Takes same arguments as DatabaseBase::select()
1106          *
1107          * @param $table String: table name
1108          * @param $vars Array: unused
1109          * @param $conds Array: filters on the table
1110          * @param $fname String: function name for profiling
1111          * @param $options Array: options for select
1112          * @return Integer: row count
1113          */
1114         public function estimateRowCount( $table, $vars = '*', $conds = '', $fname = 'DatabaseBase::estimateRowCount', $options = array() ) {
1115                 $rows = 0;
1116                 $res = $this->select ( $table, 'COUNT(*) AS rowcount', $conds, $fname, $options );
1117
1118                 if ( $res ) {
1119                         $row = $this->fetchRow( $res );
1120                         $rows = ( isset( $row['rowcount'] ) ) ? $row['rowcount'] : 0;
1121                 }
1122
1123                 return $rows;
1124         }
1125
1126         /**
1127          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1128          * It's only slightly flawed. Don't use for anything important.
1129          *
1130          * @param $sql String: A SQL Query
1131          */
1132         static function generalizeSQL( $sql ) {
1133                 # This does the same as the regexp below would do, but in such a way
1134                 # as to avoid crashing php on some large strings.
1135                 # $sql = preg_replace ( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql);
1136
1137                 $sql = str_replace ( "\\\\", '', $sql );
1138                 $sql = str_replace ( "\\'", '', $sql );
1139                 $sql = str_replace ( "\\\"", '', $sql );
1140                 $sql = preg_replace ( "/'.*'/s", "'X'", $sql );
1141                 $sql = preg_replace ( '/".*"/s', "'X'", $sql );
1142
1143                 # All newlines, tabs, etc replaced by single space
1144                 $sql = preg_replace ( '/\s+/', ' ', $sql );
1145
1146                 # All numbers => N
1147                 $sql = preg_replace ( '/-?[0-9]+/s', 'N', $sql );
1148
1149                 return $sql;
1150         }
1151
1152         /**
1153          * Determines whether a field exists in a table
1154          *
1155          * @param $table String: table name
1156          * @param $field String: filed to check on that table
1157          * @param $fname String: calling function name (optional)
1158          * @return Boolean: whether $table has filed $field
1159          */
1160         function fieldExists( $table, $field, $fname = 'DatabaseBase::fieldExists' ) {
1161                 $info = $this->fieldInfo( $table, $field );
1162
1163                 return (bool)$info;
1164         }
1165
1166         /**
1167          * Determines whether an index exists
1168          * Usually aborts on failure
1169          * If errors are explicitly ignored, returns NULL on failure
1170          */
1171         function indexExists( $table, $index, $fname = 'DatabaseBase::indexExists' ) {
1172                 $info = $this->indexInfo( $table, $index, $fname );
1173                 if ( is_null( $info ) ) {
1174                         return null;
1175                 } else {
1176                         return $info !== false;
1177                 }
1178         }
1179
1180
1181         /**
1182          * Get information about an index into an object
1183          * Returns false if the index does not exist
1184          */
1185         function indexInfo( $table, $index, $fname = 'DatabaseBase::indexInfo' ) {
1186                 # SHOW INDEX works in MySQL 3.23.58, but SHOW INDEXES does not.
1187                 # SHOW INDEX should work for 3.x and up:
1188                 # http://dev.mysql.com/doc/mysql/en/SHOW_INDEX.html
1189                 $table = $this->tableName( $table );
1190                 $index = $this->indexName( $index );
1191                 $sql = 'SHOW INDEX FROM ' . $table;
1192                 $res = $this->query( $sql, $fname );
1193
1194                 if ( !$res ) {
1195                         return null;
1196                 }
1197
1198                 $result = array();
1199
1200                 while ( $row = $this->fetchObject( $res ) ) {
1201                         if ( $row->Key_name == $index ) {
1202                                 $result[] = $row;
1203                         }
1204                 }
1205
1206                 return empty( $result ) ? false : $result;
1207         }
1208
1209         /**
1210          * Query whether a given table exists
1211          */
1212         function tableExists( $table ) {
1213                 $table = $this->tableName( $table );
1214                 $old = $this->ignoreErrors( true );
1215                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1" );
1216                 $this->ignoreErrors( $old );
1217
1218                 return (bool)$res;
1219         }
1220
1221         /**
1222          * mysql_field_type() wrapper
1223          */
1224         function fieldType( $res, $index ) {
1225                 if ( $res instanceof ResultWrapper ) {
1226                         $res = $res->result;
1227                 }
1228
1229                 return mysql_field_type( $res, $index );
1230         }
1231
1232         /**
1233          * Determines if a given index is unique
1234          */
1235         function indexUnique( $table, $index ) {
1236                 $indexInfo = $this->indexInfo( $table, $index );
1237
1238                 if ( !$indexInfo ) {
1239                         return null;
1240                 }
1241
1242                 return !$indexInfo[0]->Non_unique;
1243         }
1244
1245         /**
1246          * INSERT wrapper, inserts an array into a table
1247          *
1248          * $a may be a single associative array, or an array of these with numeric keys, for
1249          * multi-row insert.
1250          *
1251          * Usually aborts on failure
1252          * If errors are explicitly ignored, returns success
1253          *
1254          * @param $table   String: table name (prefix auto-added)
1255          * @param $a       Array: Array of rows to insert
1256          * @param $fname   String: Calling function name (use __METHOD__) for logs/profiling
1257          * @param $options Mixed: Associative array of options
1258          *
1259          * @return bool
1260          */
1261         function insert( $table, $a, $fname = 'DatabaseBase::insert', $options = array() ) {
1262                 # No rows to insert, easy just return now
1263                 if ( !count( $a ) ) {
1264                         return true;
1265                 }
1266
1267                 $table = $this->tableName( $table );
1268
1269                 if ( !is_array( $options ) ) {
1270                         $options = array( $options );
1271                 }
1272
1273                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1274                         $multi = true;
1275                         $keys = array_keys( $a[0] );
1276                 } else {
1277                         $multi = false;
1278                         $keys = array_keys( $a );
1279                 }
1280
1281                 $sql = 'INSERT ' . implode( ' ', $options ) .
1282                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1283
1284                 if ( $multi ) {
1285                         $first = true;
1286                         foreach ( $a as $row ) {
1287                                 if ( $first ) {
1288                                         $first = false;
1289                                 } else {
1290                                         $sql .= ',';
1291                                 }
1292                                 $sql .= '(' . $this->makeList( $row ) . ')';
1293                         }
1294                 } else {
1295                         $sql .= '(' . $this->makeList( $a ) . ')';
1296                 }
1297
1298                 return (bool)$this->query( $sql, $fname );
1299         }
1300
1301         /**
1302          * Make UPDATE options for the DatabaseBase::update function
1303          *
1304          * @private
1305          * @param $options Array: The options passed to DatabaseBase::update
1306          * @return string
1307          */
1308         function makeUpdateOptions( $options ) {
1309                 if ( !is_array( $options ) ) {
1310                         $options = array( $options );
1311                 }
1312
1313                 $opts = array();
1314
1315                 if ( in_array( 'LOW_PRIORITY', $options ) ) {
1316                         $opts[] = $this->lowPriorityOption();
1317                 }
1318
1319                 if ( in_array( 'IGNORE', $options ) ) {
1320                         $opts[] = 'IGNORE';
1321                 }
1322
1323                 return implode( ' ', $opts );
1324         }
1325
1326         /**
1327          * UPDATE wrapper, takes a condition array and a SET array
1328          *
1329          * @param $table  String: The table to UPDATE
1330          * @param $values Array:  An array of values to SET
1331          * @param $conds  Array:  An array of conditions (WHERE). Use '*' to update all rows.
1332          * @param $fname  String: The Class::Function calling this function
1333          *                        (for the log)
1334          * @param $options Array: An array of UPDATE options, can be one or
1335          *                        more of IGNORE, LOW_PRIORITY
1336          * @return Boolean
1337          */
1338         function update( $table, $values, $conds, $fname = 'DatabaseBase::update', $options = array() ) {
1339                 $table = $this->tableName( $table );
1340                 $opts = $this->makeUpdateOptions( $options );
1341                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1342
1343                 if ( $conds != '*' ) {
1344                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1345                 }
1346
1347                 return $this->query( $sql, $fname );
1348         }
1349
1350         /**
1351          * Makes an encoded list of strings from an array
1352          * $mode:
1353          *        LIST_COMMA         - comma separated, no field names
1354          *        LIST_AND           - ANDed WHERE clause (without the WHERE)
1355          *        LIST_OR            - ORed WHERE clause (without the WHERE)
1356          *        LIST_SET           - comma separated with field names, like a SET clause
1357          *        LIST_NAMES         - comma separated field names
1358          */
1359         function makeList( $a, $mode = LIST_COMMA ) {
1360                 if ( !is_array( $a ) ) {
1361                         throw new DBUnexpectedError( $this, 'DatabaseBase::makeList called with incorrect parameters' );
1362                 }
1363
1364                 $first = true;
1365                 $list = '';
1366
1367                 foreach ( $a as $field => $value ) {
1368                         if ( !$first ) {
1369                                 if ( $mode == LIST_AND ) {
1370                                         $list .= ' AND ';
1371                                 } elseif ( $mode == LIST_OR ) {
1372                                         $list .= ' OR ';
1373                                 } else {
1374                                         $list .= ',';
1375                                 }
1376                         } else {
1377                                 $first = false;
1378                         }
1379
1380                         if ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_numeric( $field ) ) {
1381                                 $list .= "($value)";
1382                         } elseif ( ( $mode == LIST_SET ) && is_numeric( $field ) ) {
1383                                 $list .= "$value";
1384                         } elseif ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_array( $value ) ) {
1385                                 if ( count( $value ) == 0 ) {
1386                                         throw new MWException( __METHOD__ . ': empty input' );
1387                                 } elseif ( count( $value ) == 1 ) {
1388                                         // Special-case single values, as IN isn't terribly efficient
1389                                         // Don't necessarily assume the single key is 0; we don't
1390                                         // enforce linear numeric ordering on other arrays here.
1391                                         $value = array_values( $value );
1392                                         $list .= $field . " = " . $this->addQuotes( $value[0] );
1393                                 } else {
1394                                         $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1395                                 }
1396                         } elseif ( $value === null ) {
1397                                 if ( $mode == LIST_AND || $mode == LIST_OR ) {
1398                                         $list .= "$field IS ";
1399                                 } elseif ( $mode == LIST_SET ) {
1400                                         $list .= "$field = ";
1401                                 }
1402                                 $list .= 'NULL';
1403                         } else {
1404                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
1405                                         $list .= "$field = ";
1406                                 }
1407                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
1408                         }
1409                 }
1410
1411                 return $list;
1412         }
1413
1414         /**
1415          * Build a partial where clause from a 2-d array such as used for LinkBatch.
1416          * The keys on each level may be either integers or strings.
1417          *
1418          * @param $data Array: organized as 2-d array(baseKeyVal => array(subKeyVal => <ignored>, ...), ...)
1419          * @param $baseKey String: field name to match the base-level keys to (eg 'pl_namespace')
1420          * @param $subKey String: field name to match the sub-level keys to (eg 'pl_title')
1421          * @return Mixed: string SQL fragment, or false if no items in array.
1422          */
1423         function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1424                 $conds = array();
1425
1426                 foreach ( $data as $base => $sub ) {
1427                         if ( count( $sub ) ) {
1428                                 $conds[] = $this->makeList(
1429                                         array( $baseKey => $base, $subKey => array_keys( $sub ) ),
1430                                         LIST_AND );
1431                         }
1432                 }
1433
1434                 if ( $conds ) {
1435                         return $this->makeList( $conds, LIST_OR );
1436                 } else {
1437                         // Nothing to search for...
1438                         return false;
1439                 }
1440         }
1441
1442         /**
1443          * Bitwise operations
1444          */
1445
1446         function bitNot( $field ) {
1447                 return "(~$field)";
1448         }
1449
1450         function bitAnd( $fieldLeft, $fieldRight ) {
1451                 return "($fieldLeft & $fieldRight)";
1452         }
1453
1454         function bitOr( $fieldLeft, $fieldRight ) {
1455                 return "($fieldLeft | $fieldRight)";
1456         }
1457
1458         /**
1459          * Change the current database
1460          *
1461          * @todo Explain what exactly will fail if this is not overridden.
1462          * @return bool Success or failure
1463          */
1464         function selectDB( $db ) {
1465                 # Stub.  Shouldn't cause serious problems if it's not overridden, but
1466                 # if your database engine supports a concept similar to MySQL's
1467                 # databases you may as well.
1468                 return true;
1469         }
1470
1471         /**
1472          * Get the current DB name
1473          */
1474         function getDBname() {
1475                 return $this->mDBname;
1476         }
1477
1478         /**
1479          * Get the server hostname or IP address
1480          */
1481         function getServer() {
1482                 return $this->mServer;
1483         }
1484
1485         /**
1486          * Format a table name ready for use in constructing an SQL query
1487          *
1488          * This does two important things: it quotes the table names to clean them up,
1489          * and it adds a table prefix if only given a table name with no quotes.
1490          *
1491          * All functions of this object which require a table name call this function
1492          * themselves. Pass the canonical name to such functions. This is only needed
1493          * when calling query() directly.
1494          *
1495          * @param $name String: database table name
1496          * @return String: full database name
1497          */
1498         function tableName( $name ) {
1499                 global $wgSharedDB, $wgSharedPrefix, $wgSharedTables;
1500                 # Skip the entire process when we have a string quoted on both ends.
1501                 # Note that we check the end so that we will still quote any use of
1502                 # use of `database`.table. But won't break things if someone wants
1503                 # to query a database table with a dot in the name.
1504                 if ( $name[0] == '`' && substr( $name, -1, 1 ) == '`' ) {
1505                         return $name;
1506                 }
1507
1508                 # Lets test for any bits of text that should never show up in a table
1509                 # name. Basically anything like JOIN or ON which are actually part of
1510                 # SQL queries, but may end up inside of the table value to combine
1511                 # sql. Such as how the API is doing.
1512                 # Note that we use a whitespace test rather than a \b test to avoid
1513                 # any remote case where a word like on may be inside of a table name
1514                 # surrounded by symbols which may be considered word breaks.
1515                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1516                         return $name;
1517                 }
1518
1519                 # Split database and table into proper variables.
1520                 # We reverse the explode so that database.table and table both output
1521                 # the correct table.
1522                 $dbDetails = array_reverse( explode( '.', $name, 2 ) );
1523                 if ( isset( $dbDetails[1] ) ) {
1524                         @list( $table, $database ) = $dbDetails;
1525                 } else {
1526                         @list( $table ) = $dbDetails;
1527                 }
1528                 $prefix = $this->mTablePrefix; # Default prefix
1529
1530                 # A database name has been specified in input. Quote the table name
1531                 # because we don't want any prefixes added.
1532                 if ( isset( $database ) ) {
1533                         $table = ( $table[0] == '`' ? $table : "`{$table}`" );
1534                 }
1535
1536                 # Note that we use the long format because php will complain in in_array if
1537                 # the input is not an array, and will complain in is_array if it is not set.
1538                 if ( !isset( $database ) # Don't use shared database if pre selected.
1539                  && isset( $wgSharedDB ) # We have a shared database
1540                  && $table[0] != '`' # Paranoia check to prevent shared tables listing '`table`'
1541                  && isset( $wgSharedTables )
1542                  && is_array( $wgSharedTables )
1543                  && in_array( $table, $wgSharedTables ) ) { # A shared table is selected
1544                         $database = $wgSharedDB;
1545                         $prefix   = isset( $wgSharedPrefix ) ? $wgSharedPrefix : $prefix;
1546                 }
1547
1548                 # Quote the $database and $table and apply the prefix if not quoted.
1549                 if ( isset( $database ) ) {
1550                         $database = ( $database[0] == '`' ? $database : "`{$database}`" );
1551                 }
1552                 $table = ( $table[0] == '`' ? $table : "`{$prefix}{$table}`" );
1553
1554                 # Merge our database and table into our final table name.
1555                 $tableName = ( isset( $database ) ? "{$database}.{$table}" : "{$table}" );
1556
1557                 return $tableName;
1558         }
1559
1560         /**
1561          * Fetch a number of table names into an array
1562          * This is handy when you need to construct SQL for joins
1563          *
1564          * Example:
1565          * extract($dbr->tableNames('user','watchlist'));
1566          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1567          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1568          */
1569         public function tableNames() {
1570                 $inArray = func_get_args();
1571                 $retVal = array();
1572
1573                 foreach ( $inArray as $name ) {
1574                         $retVal[$name] = $this->tableName( $name );
1575                 }
1576
1577                 return $retVal;
1578         }
1579
1580         /**
1581          * Fetch a number of table names into an zero-indexed numerical array
1582          * This is handy when you need to construct SQL for joins
1583          *
1584          * Example:
1585          * list( $user, $watchlist ) = $dbr->tableNamesN('user','watchlist');
1586          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1587          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1588          */
1589         public function tableNamesN() {
1590                 $inArray = func_get_args();
1591                 $retVal = array();
1592
1593                 foreach ( $inArray as $name ) {
1594                         $retVal[] = $this->tableName( $name );
1595                 }
1596
1597                 return $retVal;
1598         }
1599
1600         /**
1601          * @private
1602          */
1603         function tableNamesWithUseIndexOrJOIN( $tables, $use_index = array(), $join_conds = array() ) {
1604                 $ret = array();
1605                 $retJOIN = array();
1606                 $use_index_safe = is_array( $use_index ) ? $use_index : array();
1607                 $join_conds_safe = is_array( $join_conds ) ? $join_conds : array();
1608
1609                 foreach ( $tables as $table ) {
1610                         // Is there a JOIN and INDEX clause for this table?
1611                         if ( isset( $join_conds_safe[$table] ) && isset( $use_index_safe[$table] ) ) {
1612                                 $tableClause = $join_conds_safe[$table][0] . ' ' . $this->tableName( $table );
1613                                 $tableClause .= ' ' . $this->useIndexClause( implode( ',', (array)$use_index_safe[$table] ) );
1614                                 $on = $this->makeList( (array)$join_conds_safe[$table][1], LIST_AND );
1615
1616                                 if ( $on != '' ) {
1617                                         $tableClause .= ' ON (' . $on . ')';
1618                                 }
1619
1620                                 $retJOIN[] = $tableClause;
1621                         // Is there an INDEX clause?
1622                         } else if ( isset( $use_index_safe[$table] ) ) {
1623                                 $tableClause = $this->tableName( $table );
1624                                 $tableClause .= ' ' . $this->useIndexClause( implode( ',', (array)$use_index_safe[$table] ) );
1625                                 $ret[] = $tableClause;
1626                         // Is there a JOIN clause?
1627                         } else if ( isset( $join_conds_safe[$table] ) ) {
1628                                 $tableClause = $join_conds_safe[$table][0] . ' ' . $this->tableName( $table );
1629                                 $on = $this->makeList( (array)$join_conds_safe[$table][1], LIST_AND );
1630
1631                                 if ( $on != '' ) {
1632                                         $tableClause .= ' ON (' . $on . ')';
1633                                 }
1634
1635                                 $retJOIN[] = $tableClause;
1636                         } else {
1637                                 $tableClause = $this->tableName( $table );
1638                                 $ret[] = $tableClause;
1639                         }
1640                 }
1641
1642                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
1643                 $straightJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
1644                 $otherJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
1645
1646                 // Compile our final table clause
1647                 return implode( ' ', array( $straightJoins, $otherJoins ) );
1648         }
1649
1650         /**
1651          * Get the name of an index in a given table
1652          */
1653         function indexName( $index ) {
1654                 // Backwards-compatibility hack
1655                 $renamed = array(
1656                         'ar_usertext_timestamp' => 'usertext_timestamp',
1657                         'un_user_id'            => 'user_id',
1658                         'un_user_ip'            => 'user_ip',
1659                 );
1660
1661                 if ( isset( $renamed[$index] ) ) {
1662                         return $renamed[$index];
1663                 } else {
1664                         return $index;
1665                 }
1666         }
1667
1668         /**
1669          * If it's a string, adds quotes and backslashes
1670          * Otherwise returns as-is
1671          */
1672         function addQuotes( $s ) {
1673                 if ( $s === null ) {
1674                         return 'NULL';
1675                 } else {
1676                         # This will also quote numeric values. This should be harmless,
1677                         # and protects against weird problems that occur when they really
1678                         # _are_ strings such as article titles and string->number->string
1679                         # conversion is not 1:1.
1680                         return "'" . $this->strencode( $s ) . "'";
1681                 }
1682         }
1683
1684         /**
1685          * Escape string for safe LIKE usage.
1686          * WARNING: you should almost never use this function directly,
1687          * instead use buildLike() that escapes everything automatically
1688          * Deprecated in 1.17, warnings in 1.17, removed in ???
1689          */
1690         public function escapeLike( $s ) {
1691                 wfDeprecated( __METHOD__ );
1692                 return $this->escapeLikeInternal( $s );
1693         }
1694
1695         protected function escapeLikeInternal( $s ) {
1696                 $s = str_replace( '\\', '\\\\', $s );
1697                 $s = $this->strencode( $s );
1698                 $s = str_replace( array( '%', '_' ), array( '\%', '\_' ), $s );
1699
1700                 return $s;
1701         }
1702
1703         /**
1704          * LIKE statement wrapper, receives a variable-length argument list with parts of pattern to match
1705          * containing either string literals that will be escaped or tokens returned by anyChar() or anyString().
1706          * Alternatively, the function could be provided with an array of aforementioned parameters.
1707          *
1708          * Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns a LIKE clause that searches
1709          * for subpages of 'My page title'.
1710          * Alternatively: $pattern = array( 'My_page_title/', $dbr->anyString() ); $query .= $dbr->buildLike( $pattern );
1711          *
1712          * @since 1.16
1713          * @return String: fully built LIKE statement
1714          */
1715         function buildLike() {
1716                 $params = func_get_args();
1717
1718                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
1719                         $params = $params[0];
1720                 }
1721
1722                 $s = '';
1723
1724                 foreach ( $params as $value ) {
1725                         if ( $value instanceof LikeMatch ) {
1726                                 $s .= $value->toString();
1727                         } else {
1728                                 $s .= $this->escapeLikeInternal( $value );
1729                         }
1730                 }
1731
1732                 return " LIKE '" . $s . "' ";
1733         }
1734
1735         /**
1736          * Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
1737          */
1738         function anyChar() {
1739                 return new LikeMatch( '_' );
1740         }
1741
1742         /**
1743          * Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
1744          */
1745         function anyString() {
1746                 return new LikeMatch( '%' );
1747         }
1748
1749         /**
1750          * Returns an appropriately quoted sequence value for inserting a new row.
1751          * MySQL has autoincrement fields, so this is just NULL. But the PostgreSQL
1752          * subclass will return an integer, and save the value for insertId()
1753          */
1754         function nextSequenceValue( $seqName ) {
1755                 return null;
1756         }
1757
1758         /**
1759          * USE INDEX clause.  Unlikely to be useful for anything but MySQL.  This
1760          * is only needed because a) MySQL must be as efficient as possible due to
1761          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
1762          * which index to pick.  Anyway, other databases might have different
1763          * indexes on a given table.  So don't bother overriding this unless you're
1764          * MySQL.
1765          */
1766         function useIndexClause( $index ) {
1767                 return '';
1768         }
1769
1770         /**
1771          * REPLACE query wrapper
1772          * PostgreSQL simulates this with a DELETE followed by INSERT
1773          * $row is the row to insert, an associative array
1774          * $uniqueIndexes is an array of indexes. Each element may be either a
1775          * field name or an array of field names
1776          *
1777          * It may be more efficient to leave off unique indexes which are unlikely to collide.
1778          * However if you do this, you run the risk of encountering errors which wouldn't have
1779          * occurred in MySQL
1780          *
1781          * @param $table String: The table to replace the row(s) in.
1782          * @param $uniqueIndexes Array: An associative array of indexes
1783          * @param $rows Array: Array of rows to replace
1784          * @param $fname String: Calling function name (use __METHOD__) for logs/profiling
1785          */
1786         function replace( $table, $uniqueIndexes, $rows, $fname = 'DatabaseBase::replace' ) {
1787                 $table = $this->tableName( $table );
1788
1789                 # Single row case
1790                 if ( !is_array( reset( $rows ) ) ) {
1791                         $rows = array( $rows );
1792                 }
1793
1794                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
1795                 $first = true;
1796
1797                 foreach ( $rows as $row ) {
1798                         if ( $first ) {
1799                                 $first = false;
1800                         } else {
1801                                 $sql .= ',';
1802                         }
1803
1804                         $sql .= '(' . $this->makeList( $row ) . ')';
1805                 }
1806
1807                 return $this->query( $sql, $fname );
1808         }
1809
1810         /**
1811          * DELETE where the condition is a join
1812          * MySQL does this with a multi-table DELETE syntax, PostgreSQL does it with sub-selects
1813          *
1814          * For safety, an empty $conds will not delete everything. If you want to delete all rows where the
1815          * join condition matches, set $conds='*'
1816          *
1817          * DO NOT put the join condition in $conds
1818          *
1819          * @param $delTable String: The table to delete from.
1820          * @param $joinTable String: The other table.
1821          * @param $delVar String: The variable to join on, in the first table.
1822          * @param $joinVar String: The variable to join on, in the second table.
1823          * @param $conds Array: Condition array of field names mapped to variables, ANDed together in the WHERE clause
1824          * @param $fname String: Calling function name (use __METHOD__) for logs/profiling
1825          */
1826         function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds, $fname = 'DatabaseBase::deleteJoin' ) {
1827                 if ( !$conds ) {
1828                         throw new DBUnexpectedError( $this, 'DatabaseBase::deleteJoin() called with empty $conds' );
1829                 }
1830
1831                 $delTable = $this->tableName( $delTable );
1832                 $joinTable = $this->tableName( $joinTable );
1833                 $sql = "DELETE $delTable FROM $delTable, $joinTable WHERE $delVar=$joinVar ";
1834
1835                 if ( $conds != '*' ) {
1836                         $sql .= ' AND ' . $this->makeList( $conds, LIST_AND );
1837                 }
1838
1839                 return $this->query( $sql, $fname );
1840         }
1841
1842         /**
1843          * Returns the size of a text field, or -1 for "unlimited"
1844          */
1845         function textFieldSize( $table, $field ) {
1846                 $table = $this->tableName( $table );
1847                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
1848                 $res = $this->query( $sql, 'DatabaseBase::textFieldSize' );
1849                 $row = $this->fetchObject( $res );
1850
1851                 $m = array();
1852
1853                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
1854                         $size = $m[1];
1855                 } else {
1856                         $size = -1;
1857                 }
1858
1859                 return $size;
1860         }
1861
1862         /**
1863          * A string to insert into queries to show that they're low-priority, like
1864          * MySQL's LOW_PRIORITY.  If no such feature exists, return an empty
1865          * string and nothing bad should happen.
1866          *
1867          * @return string Returns the text of the low priority option if it is supported, or a blank string otherwise
1868          */
1869         function lowPriorityOption() {
1870                 return '';
1871         }
1872
1873         /**
1874          * DELETE query wrapper
1875          *
1876          * Use $conds == "*" to delete all rows
1877          */
1878         function delete( $table, $conds, $fname = 'DatabaseBase::delete' ) {
1879                 if ( !$conds ) {
1880                         throw new DBUnexpectedError( $this, 'DatabaseBase::delete() called with no conditions' );
1881                 }
1882
1883                 $table = $this->tableName( $table );
1884                 $sql = "DELETE FROM $table";
1885
1886                 if ( $conds != '*' ) {
1887                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1888                 }
1889
1890                 return $this->query( $sql, $fname );
1891         }
1892
1893         /**
1894          * INSERT SELECT wrapper
1895          * $varMap must be an associative array of the form array( 'dest1' => 'source1', ...)
1896          * Source items may be literals rather than field names, but strings should be quoted with DatabaseBase::addQuotes()
1897          * $conds may be "*" to copy the whole table
1898          * srcTable may be an array of tables.
1899          */
1900         function insertSelect( $destTable, $srcTable, $varMap, $conds, $fname = 'DatabaseBase::insertSelect',
1901                 $insertOptions = array(), $selectOptions = array() )
1902         {
1903                 $destTable = $this->tableName( $destTable );
1904
1905                 if ( is_array( $insertOptions ) ) {
1906                         $insertOptions = implode( ' ', $insertOptions );
1907                 }
1908
1909                 if ( !is_array( $selectOptions ) ) {
1910                         $selectOptions = array( $selectOptions );
1911                 }
1912
1913                 list( $startOpts, $useIndex, $tailOpts ) = $this->makeSelectOptions( $selectOptions );
1914
1915                 if ( is_array( $srcTable ) ) {
1916                         $srcTable =  implode( ',', array_map( array( &$this, 'tableName' ), $srcTable ) );
1917                 } else {
1918                         $srcTable = $this->tableName( $srcTable );
1919                 }
1920
1921                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
1922                         " SELECT $startOpts " . implode( ',', $varMap ) .
1923                         " FROM $srcTable $useIndex ";
1924
1925                 if ( $conds != '*' ) {
1926                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1927                 }
1928
1929                 $sql .= " $tailOpts";
1930
1931                 return $this->query( $sql, $fname );
1932         }
1933
1934         /**
1935          * Construct a LIMIT query with optional offset.  This is used for query
1936          * pages.  The SQL should be adjusted so that only the first $limit rows
1937          * are returned.  If $offset is provided as well, then the first $offset
1938          * rows should be discarded, and the next $limit rows should be returned.
1939          * If the result of the query is not ordered, then the rows to be returned
1940          * are theoretically arbitrary.
1941          *
1942          * $sql is expected to be a SELECT, if that makes a difference.  For
1943          * UPDATE, limitResultForUpdate should be used.
1944          *
1945          * The version provided by default works in MySQL and SQLite.  It will very
1946          * likely need to be overridden for most other DBMSes.
1947          *
1948          * @param $sql String: SQL query we will append the limit too
1949          * @param $limit Integer: the SQL limit
1950          * @param $offset Integer the SQL offset (default false)
1951          */
1952         function limitResult( $sql, $limit, $offset = false ) {
1953                 if ( !is_numeric( $limit ) ) {
1954                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
1955                 }
1956
1957                 return "$sql LIMIT "
1958                                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
1959                                 . "{$limit} ";
1960         }
1961
1962         function limitResultForUpdate( $sql, $num ) {
1963                 return $this->limitResult( $sql, $num, 0 );
1964         }
1965
1966         /**
1967          * Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
1968          * within the UNION construct.
1969          * @return Boolean
1970          */
1971         function unionSupportsOrderAndLimit() {
1972                 return true; // True for almost every DB supported
1973         }
1974
1975         /**
1976          * Construct a UNION query
1977          * This is used for providing overload point for other DB abstractions
1978          * not compatible with the MySQL syntax.
1979          * @param $sqls Array: SQL statements to combine
1980          * @param $all Boolean: use UNION ALL
1981          * @return String: SQL fragment
1982          */
1983         function unionQueries( $sqls, $all ) {
1984                 $glue = $all ? ') UNION ALL (' : ') UNION (';
1985                 return '(' . implode( $glue, $sqls ) . ')';
1986         }
1987
1988         /**
1989          * Returns an SQL expression for a simple conditional.  This doesn't need
1990          * to be overridden unless CASE isn't supported in your DBMS.
1991          *
1992          * @param $cond String: SQL expression which will result in a boolean value
1993          * @param $trueVal String: SQL expression to return if true
1994          * @param $falseVal String: SQL expression to return if false
1995          * @return String: SQL fragment
1996          */
1997         function conditional( $cond, $trueVal, $falseVal ) {
1998                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
1999         }
2000
2001         /**
2002          * Returns a comand for str_replace function in SQL query.
2003          * Uses REPLACE() in MySQL
2004          *
2005          * @param $orig String: column to modify
2006          * @param $old String: column to seek
2007          * @param $new String: column to replace with
2008          */
2009         function strreplace( $orig, $old, $new ) {
2010                 return "REPLACE({$orig}, {$old}, {$new})";
2011         }
2012
2013         /**
2014          * Determines if the last failure was due to a deadlock
2015          * STUB
2016          */
2017         function wasDeadlock() {
2018                 return false;
2019         }
2020
2021         /**
2022          * Determines if the last query error was something that should be dealt
2023          * with by pinging the connection and reissuing the query.
2024          * STUB
2025          */
2026         function wasErrorReissuable() {
2027                 return false;
2028         }
2029
2030         /**
2031          * Determines if the last failure was due to the database being read-only.
2032          * STUB
2033          */
2034         function wasReadOnlyError() {
2035                 return false;
2036         }
2037
2038         /**
2039          * Perform a deadlock-prone transaction.
2040          *
2041          * This function invokes a callback function to perform a set of write
2042          * queries. If a deadlock occurs during the processing, the transaction
2043          * will be rolled back and the callback function will be called again.
2044          *
2045          * Usage:
2046          *   $dbw->deadlockLoop( callback, ... );
2047          *
2048          * Extra arguments are passed through to the specified callback function.
2049          *
2050          * Returns whatever the callback function returned on its successful,
2051          * iteration, or false on error, for example if the retry limit was
2052          * reached.
2053          */
2054         function deadlockLoop() {
2055                 $myFname = 'DatabaseBase::deadlockLoop';
2056
2057                 $this->begin();
2058                 $args = func_get_args();
2059                 $function = array_shift( $args );
2060                 $oldIgnore = $this->ignoreErrors( true );
2061                 $tries = DEADLOCK_TRIES;
2062
2063                 if ( is_array( $function ) ) {
2064                         $fname = $function[0];
2065                 } else {
2066                         $fname = $function;
2067                 }
2068
2069                 do {
2070                         $retVal = call_user_func_array( $function, $args );
2071                         $error = $this->lastError();
2072                         $errno = $this->lastErrno();
2073                         $sql = $this->lastQuery();
2074
2075                         if ( $errno ) {
2076                                 if ( $this->wasDeadlock() ) {
2077                                         # Retry
2078                                         usleep( mt_rand( DEADLOCK_DELAY_MIN, DEADLOCK_DELAY_MAX ) );
2079                                 } else {
2080                                         $this->reportQueryError( $error, $errno, $sql, $fname );
2081                                 }
2082                         }
2083                 } while ( $this->wasDeadlock() && --$tries > 0 );
2084
2085                 $this->ignoreErrors( $oldIgnore );
2086
2087                 if ( $tries <= 0 ) {
2088                         $this->rollback( $myFname );
2089                         $this->reportQueryError( $error, $errno, $sql, $fname );
2090                         return false;
2091                 } else {
2092                         $this->commit( $myFname );
2093                         return $retVal;
2094                 }
2095         }
2096
2097         /**
2098          * Do a SELECT MASTER_POS_WAIT()
2099          *
2100          * @param $pos MySQLMasterPos object
2101          * @param $timeout Integer: the maximum number of seconds to wait for synchronisation
2102          */
2103         function masterPosWait( MySQLMasterPos $pos, $timeout ) {
2104                 $fname = 'DatabaseBase::masterPosWait';
2105                 wfProfileIn( $fname );
2106
2107                 # Commit any open transactions
2108                 if ( $this->mTrxLevel ) {
2109                         $this->commit();
2110                 }
2111
2112                 if ( !is_null( $this->mFakeSlaveLag ) ) {
2113                         $wait = intval( ( $pos->pos - microtime( true ) + $this->mFakeSlaveLag ) * 1e6 );
2114
2115                         if ( $wait > $timeout * 1e6 ) {
2116                                 wfDebug( "Fake slave timed out waiting for $pos ($wait us)\n" );
2117                                 wfProfileOut( $fname );
2118                                 return -1;
2119                         } elseif ( $wait > 0 ) {
2120                                 wfDebug( "Fake slave waiting $wait us\n" );
2121                                 usleep( $wait );
2122                                 wfProfileOut( $fname );
2123                                 return 1;
2124                         } else {
2125                                 wfDebug( "Fake slave up to date ($wait us)\n" );
2126                                 wfProfileOut( $fname );
2127                                 return 0;
2128                         }
2129                 }
2130
2131                 # Call doQuery() directly, to avoid opening a transaction if DBO_TRX is set
2132                 $encFile = $this->addQuotes( $pos->file );
2133                 $encPos = intval( $pos->pos );
2134                 $sql = "SELECT MASTER_POS_WAIT($encFile, $encPos, $timeout)";
2135                 $res = $this->doQuery( $sql );
2136
2137                 if ( $res && $row = $this->fetchRow( $res ) ) {
2138                         wfProfileOut( $fname );
2139                         return $row[0];
2140                 } else {
2141                         wfProfileOut( $fname );
2142                         return false;
2143                 }
2144         }
2145
2146         /**
2147          * Get the position of the master from SHOW SLAVE STATUS
2148          */
2149         function getSlavePos() {
2150                 if ( !is_null( $this->mFakeSlaveLag ) ) {
2151                         $pos = new MySQLMasterPos( 'fake', microtime( true ) - $this->mFakeSlaveLag );
2152                         wfDebug( __METHOD__ . ": fake slave pos = $pos\n" );
2153                         return $pos;
2154                 }
2155
2156                 $res = $this->query( 'SHOW SLAVE STATUS', 'DatabaseBase::getSlavePos' );
2157                 $row = $this->fetchObject( $res );
2158
2159                 if ( $row ) {
2160                         $pos = isset( $row->Exec_master_log_pos ) ? $row->Exec_master_log_pos : $row->Exec_Master_Log_Pos;
2161                         return new MySQLMasterPos( $row->Relay_Master_Log_File, $pos );
2162                 } else {
2163                         return false;
2164                 }
2165         }
2166
2167         /**
2168          * Get the position of the master from SHOW MASTER STATUS
2169          */
2170         function getMasterPos() {
2171                 if ( $this->mFakeMaster ) {
2172                         return new MySQLMasterPos( 'fake', microtime( true ) );
2173                 }
2174
2175                 $res = $this->query( 'SHOW MASTER STATUS', 'DatabaseBase::getMasterPos' );
2176                 $row = $this->fetchObject( $res );
2177
2178                 if ( $row ) {
2179                         return new MySQLMasterPos( $row->File, $row->Position );
2180                 } else {
2181                         return false;
2182                 }
2183         }
2184
2185         /**
2186          * Begin a transaction, committing any previously open transaction
2187          */
2188         function begin( $fname = 'DatabaseBase::begin' ) {
2189                 $this->query( 'BEGIN', $fname );
2190                 $this->mTrxLevel = 1;
2191         }
2192
2193         /**
2194          * End a transaction
2195          */
2196         function commit( $fname = 'DatabaseBase::commit' ) {
2197                 if ( $this->mTrxLevel ) {
2198                         $this->query( 'COMMIT', $fname );
2199                         $this->mTrxLevel = 0;
2200                 }
2201         }
2202
2203         /**
2204          * Rollback a transaction.
2205          * No-op on non-transactional databases.
2206          */
2207         function rollback( $fname = 'DatabaseBase::rollback' ) {
2208                 if ( $this->mTrxLevel ) {
2209                         $this->query( 'ROLLBACK', $fname, true );
2210                         $this->mTrxLevel = 0;
2211                 }
2212         }
2213
2214         /**
2215          * Begin a transaction, committing any previously open transaction
2216          * @deprecated use begin()
2217          */
2218         function immediateBegin( $fname = 'DatabaseBase::immediateBegin' ) {
2219                 wfDeprecated( __METHOD__ );
2220                 $this->begin();
2221         }
2222
2223         /**
2224          * Commit transaction, if one is open
2225          * @deprecated use commit()
2226          */
2227         function immediateCommit( $fname = 'DatabaseBase::immediateCommit' ) {
2228                 wfDeprecated( __METHOD__ );
2229                 $this->commit();
2230         }
2231
2232         /**
2233          * Creates a new table with structure copied from existing table
2234          * Note that unlike most database abstraction functions, this function does not
2235          * automatically append database prefix, because it works at a lower
2236          * abstraction level.
2237          *
2238          * @param $oldName String: name of table whose structure should be copied
2239          * @param $newName String: name of table to be created
2240          * @param $temporary Boolean: whether the new table should be temporary
2241          * @param $fname String: calling function name
2242          * @return Boolean: true if operation was successful
2243          */
2244         function duplicateTableStructure( $oldName, $newName, $temporary = false, $fname = 'DatabaseBase::duplicateTableStructure' ) {
2245                 throw new MWException( 'DatabaseBase::duplicateTableStructure is not implemented in descendant class' );
2246         }
2247
2248         /**
2249          * Return MW-style timestamp used for MySQL schema
2250          */
2251         function timestamp( $ts = 0 ) {
2252                 return wfTimestamp( TS_MW, $ts );
2253         }
2254
2255         /**
2256          * Local database timestamp format or null
2257          */
2258         function timestampOrNull( $ts = null ) {
2259                 if ( is_null( $ts ) ) {
2260                         return null;
2261                 } else {
2262                         return $this->timestamp( $ts );
2263                 }
2264         }
2265
2266         /**
2267          * @todo document
2268          */
2269         function resultObject( $result ) {
2270                 if ( empty( $result ) ) {
2271                         return false;
2272                 } elseif ( $result instanceof ResultWrapper ) {
2273                         return $result;
2274                 } elseif ( $result === true ) {
2275                         // Successful write query
2276                         return $result;
2277                 } else {
2278                         return new ResultWrapper( $this, $result );
2279                 }
2280         }
2281
2282         /**
2283          * Return aggregated value alias
2284          */
2285         function aggregateValue ( $valuedata, $valuename = 'value' ) {
2286                 return $valuename;
2287         }
2288
2289         /**
2290          * Ping the server and try to reconnect if it there is no connection
2291          *
2292          * @return bool Success or failure
2293          */
2294         function ping() {
2295                 # Stub.  Not essential to override.
2296                 return true;
2297         }
2298
2299         /**
2300          * Get slave lag.
2301          * Currently supported only by MySQL
2302          * @return Database replication lag in seconds
2303          */
2304         function getLag() {
2305                 return $this->mFakeSlaveLag;
2306         }
2307
2308         /**
2309          * Get status information from SHOW STATUS in an associative array
2310          */
2311         function getStatus( $which = "%" ) {
2312                 $res = $this->query( "SHOW STATUS LIKE '{$which}'" );
2313                 $status = array();
2314
2315                 while ( $row = $this->fetchObject( $res ) ) {
2316                         $status[$row->Variable_name] = $row->Value;
2317                 }
2318
2319                 return $status;
2320         }
2321
2322         /**
2323          * Return the maximum number of items allowed in a list, or 0 for unlimited.
2324          */
2325         function maxListLen() {
2326                 return 0;
2327         }
2328
2329         function encodeBlob( $b ) {
2330                 return $b;
2331         }
2332
2333         function decodeBlob( $b ) {
2334                 return $b;
2335         }
2336
2337         /**
2338          * Override database's default connection timeout.  May be useful for very
2339          * long batch queries such as full-wiki dumps, where a single query reads
2340          * out over hours or days.  May or may not be necessary for non-MySQL
2341          * databases.  For most purposes, leaving it as a no-op should be fine.
2342          *
2343          * @param $timeout Integer in seconds
2344          */
2345         public function setTimeout( $timeout ) {}
2346
2347         /**
2348          * Read and execute SQL commands from a file.
2349          * Returns true on success, error string or exception on failure (depending on object's error ignore settings)
2350          * @param $filename String: File name to open
2351          * @param $lineCallback Callback: Optional function called before reading each line
2352          * @param $resultCallback Callback: Optional function called for each MySQL result
2353          * @param $fname String: Calling function name or false if name should be generated dynamically
2354          *              using $filename
2355          */
2356         function sourceFile( $filename, $lineCallback = false, $resultCallback = false, $fname = false ) {
2357                 $fp = fopen( $filename, 'r' );
2358
2359                 if ( false === $fp ) {
2360                         if ( !defined( "MEDIAWIKI_INSTALL" ) )
2361                                 throw new MWException( "Could not open \"{$filename}\".\n" );
2362                         else
2363                                 return "Could not open \"{$filename}\".\n";
2364                 }
2365
2366                 if ( !$fname ) {
2367                         $fname = __METHOD__ . "( $filename )";
2368                 }
2369
2370                 try {
2371                         $error = $this->sourceStream( $fp, $lineCallback, $resultCallback, $fname );
2372                 }
2373                 catch ( MWException $e ) {
2374                         if ( defined( "MEDIAWIKI_INSTALL" ) ) {
2375                                 $error = $e->getMessage();
2376                         } else {
2377                                 fclose( $fp );
2378                                 throw $e;
2379                         }
2380                 }
2381
2382                 fclose( $fp );
2383
2384                 return $error;
2385         }
2386
2387         /**
2388          * Get the full path of a patch file. Originally based on archive()
2389          * from updaters.inc. Keep in mind this always returns a patch, as
2390          * it fails back to MySQL if no DB-specific patch can be found
2391          *
2392          * @param $patch String The name of the patch, like patch-something.sql
2393          * @return String Full path to patch file
2394          */
2395         public static function patchPath( $patch ) {
2396                 global $wgDBtype, $IP;
2397
2398                 if ( file_exists( "$IP/maintenance/$wgDBtype/archives/$patch" ) ) {
2399                         return "$IP/maintenance/$wgDBtype/archives/$patch";
2400                 } else {
2401                         return "$IP/maintenance/archives/$patch";
2402                 }
2403         }
2404
2405         /**
2406          * Read and execute commands from an open file handle
2407          * Returns true on success, error string or exception on failure (depending on object's error ignore settings)
2408          * @param $fp String: File handle
2409          * @param $lineCallback Callback: Optional function called before reading each line
2410          * @param $resultCallback Callback: Optional function called for each MySQL result
2411          * @param $fname String: Calling function name
2412          */
2413         function sourceStream( $fp, $lineCallback = false, $resultCallback = false, $fname = 'DatabaseBase::sourceStream' ) {
2414                 $cmd = "";
2415                 $done = false;
2416                 $dollarquote = false;
2417
2418                 while ( ! feof( $fp ) ) {
2419                         if ( $lineCallback ) {
2420                                 call_user_func( $lineCallback );
2421                         }
2422
2423                         $line = trim( fgets( $fp, 1024 ) );
2424                         $sl = strlen( $line ) - 1;
2425
2426                         if ( $sl < 0 ) {
2427                                 continue;
2428                         }
2429
2430                         if ( '-' == $line { 0 } && '-' == $line { 1 } ) {
2431                                 continue;
2432                         }
2433
2434                         # # Allow dollar quoting for function declarations
2435                         if ( substr( $line, 0, 4 ) == '$mw$' ) {
2436                                 if ( $dollarquote ) {
2437                                         $dollarquote = false;
2438                                         $done = true;
2439                                 }
2440                                 else {
2441                                         $dollarquote = true;
2442                                 }
2443                         }
2444                         else if ( !$dollarquote ) {
2445                                 if ( ';' == $line { $sl } && ( $sl < 2 || ';' != $line { $sl - 1 } ) ) {
2446                                         $done = true;
2447                                         $line = substr( $line, 0, $sl );
2448                                 }
2449                         }
2450
2451                         if ( $cmd != '' ) {
2452                                 $cmd .= ' ';
2453                         }
2454
2455                         $cmd .= "$line\n";
2456
2457                         if ( $done ) {
2458                                 $cmd = str_replace( ';;', ";", $cmd );
2459                                 $cmd = $this->replaceVars( $cmd );
2460                                 $res = $this->query( $cmd, $fname );
2461
2462                                 if ( $resultCallback ) {
2463                                         call_user_func( $resultCallback, $res, $this );
2464                                 }
2465
2466                                 if ( false === $res ) {
2467                                         $err = $this->lastError();
2468                                         return "Query \"{$cmd}\" failed with error code \"$err\".\n";
2469                                 }
2470
2471                                 $cmd = '';
2472                                 $done = false;
2473                         }
2474                 }
2475
2476                 return true;
2477         }
2478
2479         /**
2480          * Replace variables in sourced SQL
2481          */
2482         protected function replaceVars( $ins ) {
2483                 $varnames = array(
2484                         'wgDBserver', 'wgDBname', 'wgDBintlname', 'wgDBuser',
2485                         'wgDBpassword', 'wgDBsqluser', 'wgDBsqlpassword',
2486                         'wgDBadminuser', 'wgDBadminpassword', 'wgDBTableOptions',
2487                 );
2488
2489                 // Ordinary variables
2490                 foreach ( $varnames as $var ) {
2491                         if ( isset( $GLOBALS[$var] ) ) {
2492                                 $val = addslashes( $GLOBALS[$var] ); // FIXME: safety check?
2493                                 $ins = str_replace( '{$' . $var . '}', $val, $ins );
2494                                 $ins = str_replace( '/*$' . $var . '*/`', '`' . $val, $ins );
2495                                 $ins = str_replace( '/*$' . $var . '*/', $val, $ins );
2496                         }
2497                 }
2498
2499                 // Table prefixes
2500                 $ins = preg_replace_callback( '!/\*(?:\$wgDBprefix|_)\*/([a-zA-Z_0-9]*)!',
2501                         array( $this, 'tableNameCallback' ), $ins );
2502
2503                 // Index names
2504                 $ins = preg_replace_callback( '!/\*i\*/([a-zA-Z_0-9]*)!',
2505                         array( $this, 'indexNameCallback' ), $ins );
2506
2507                 return $ins;
2508         }
2509
2510         /**
2511          * Table name callback
2512          * @private
2513          */
2514         protected function tableNameCallback( $matches ) {
2515                 return $this->tableName( $matches[1] );
2516         }
2517
2518         /**
2519          * Index name callback
2520          */
2521         protected function indexNameCallback( $matches ) {
2522                 return $this->indexName( $matches[1] );
2523         }
2524
2525         /**
2526          * Build a concatenation list to feed into a SQL query
2527          * @param $stringList Array: list of raw SQL expressions; caller is responsible for any quoting
2528          * @return String
2529          */
2530         function buildConcat( $stringList ) {
2531                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
2532         }
2533
2534         /**
2535          * Acquire a named lock
2536          *
2537          * Abstracted from Filestore::lock() so child classes can implement for
2538          * their own needs.
2539          *
2540          * @param $lockName String: name of lock to aquire
2541          * @param $method String: name of method calling us
2542          * @param $timeout Integer: timeout
2543          * @return Boolean
2544          */
2545         public function lock( $lockName, $method, $timeout = 5 ) {
2546                 return true;
2547         }
2548
2549         /**
2550          * Release a lock.
2551          *
2552          * @param $lockName String: Name of lock to release
2553          * @param $method String: Name of method calling us
2554          *
2555          * @return Returns 1 if the lock was released, 0 if the lock was not established
2556          * by this thread (in which case the lock is not released), and NULL if the named
2557          * lock did not exist
2558          */
2559         public function unlock( $lockName, $method ) {
2560                 return true;
2561         }
2562
2563         /**
2564          * Lock specific tables
2565          *
2566          * @param $read Array of tables to lock for read access
2567          * @param $write Array of tables to lock for write access
2568          * @param $method String name of caller
2569          * @param $lowPriority bool Whether to indicate writes to be LOW PRIORITY
2570          */
2571         public function lockTables( $read, $write, $method, $lowPriority = true ) {
2572                 return true;
2573         }
2574
2575         /**
2576          * Unlock specific tables
2577          *
2578          * @param $method String the caller
2579          */
2580         public function unlockTables( $method ) {
2581                 return true;
2582         }
2583
2584         /**
2585          * Get search engine class. All subclasses of this need to implement this
2586          * if they wish to use searching.
2587          *
2588          * @return String
2589          */
2590         public function getSearchEngine() {
2591                 return 'SearchEngineDummy';
2592         }
2593
2594         /**
2595          * Allow or deny "big selects" for this session only. This is done by setting
2596          * the sql_big_selects session variable.
2597          *
2598          * This is a MySQL-specific feature.
2599          *
2600          * @param $value Mixed: true for allow, false for deny, or "default" to restore the initial value
2601          */
2602         public function setBigSelects( $value = true ) {
2603                 // no-op
2604         }
2605 }
2606
2607 /******************************************************************************
2608  * Utility classes
2609  *****************************************************************************/
2610
2611 /**
2612  * Utility class.
2613  * @ingroup Database
2614  */
2615 class DBObject {
2616         public $mData;
2617
2618         function __construct( $data ) {
2619                 $this->mData = $data;
2620         }
2621
2622         function isLOB() {
2623                 return false;
2624         }
2625
2626         function data() {
2627                 return $this->mData;
2628         }
2629 }
2630
2631 /**
2632  * Utility class
2633  * @ingroup Database
2634  *
2635  * This allows us to distinguish a blob from a normal string and an array of strings
2636  */
2637 class Blob {
2638         private $mData;
2639
2640         function __construct( $data ) {
2641                 $this->mData = $data;
2642         }
2643
2644         function fetch() {
2645                 return $this->mData;
2646         }
2647 }
2648
2649 /**
2650  * Utility class.
2651  * @ingroup Database
2652  */
2653 class MySQLField {
2654         private $name, $tablename, $default, $max_length, $nullable,
2655                 $is_pk, $is_unique, $is_multiple, $is_key, $type;
2656
2657         function __construct ( $info ) {
2658                 $this->name = $info->name;
2659                 $this->tablename = $info->table;
2660                 $this->default = $info->def;
2661                 $this->max_length = $info->max_length;
2662                 $this->nullable = !$info->not_null;
2663                 $this->is_pk = $info->primary_key;
2664                 $this->is_unique = $info->unique_key;
2665                 $this->is_multiple = $info->multiple_key;
2666                 $this->is_key = ( $this->is_pk || $this->is_unique || $this->is_multiple );
2667                 $this->type = $info->type;
2668         }
2669
2670         function name() {
2671                 return $this->name;
2672         }
2673
2674         function tableName() {
2675                 return $this->tableName;
2676         }
2677
2678         function defaultValue() {
2679                 return $this->default;
2680         }
2681
2682         function maxLength() {
2683                 return $this->max_length;
2684         }
2685
2686         function nullable() {
2687                 return $this->nullable;
2688         }
2689
2690         function isKey() {
2691                 return $this->is_key;
2692         }
2693
2694         function isMultipleKey() {
2695                 return $this->is_multiple;
2696         }
2697
2698         function type() {
2699                 return $this->type;
2700         }
2701 }
2702
2703 /******************************************************************************
2704  * Error classes
2705  *****************************************************************************/
2706
2707 /**
2708  * Database error base class
2709  * @ingroup Database
2710  */
2711 class DBError extends MWException {
2712         public $db;
2713
2714         /**
2715          * Construct a database error
2716          * @param $db Database object which threw the error
2717          * @param $error A simple error message to be used for debugging
2718          */
2719         function __construct( DatabaseBase &$db, $error ) {
2720                 $this->db =& $db;
2721                 parent::__construct( $error );
2722         }
2723
2724         function getText() {
2725                 global $wgShowDBErrorBacktrace;
2726
2727                 $s = $this->getMessage() . "\n";
2728
2729                 if ( $wgShowDBErrorBacktrace ) {
2730                         $s .= "Backtrace:\n" . $this->getTraceAsString() . "\n";
2731                 }
2732
2733                 return $s;
2734         }
2735 }
2736
2737 /**
2738  * @ingroup Database
2739  */
2740 class DBConnectionError extends DBError {
2741         public $error;
2742
2743         function __construct( DatabaseBase &$db, $error = 'unknown error' ) {
2744                 $msg = 'DB connection error';
2745
2746                 if ( trim( $error ) != '' ) {
2747                         $msg .= ": $error";
2748                 }
2749
2750                 $this->error = $error;
2751
2752                 parent::__construct( $db, $msg );
2753         }
2754
2755         function useOutputPage() {
2756                 // Not likely to work
2757                 return false;
2758         }
2759
2760         function useMessageCache() {
2761                 // Not likely to work
2762                 return false;
2763         }
2764
2765         function getLogMessage() {
2766                 # Don't send to the exception log
2767                 return false;
2768         }
2769
2770         function getPageTitle() {
2771                 global $wgSitename, $wgLang;
2772
2773                 $header = "$wgSitename has a problem";
2774
2775                 if ( $wgLang instanceof Language ) {
2776                         $header = htmlspecialchars( $wgLang->getMessage( 'dberr-header' ) );
2777                 }
2778
2779                 return $header;
2780         }
2781
2782         function getHTML() {
2783                 global $wgLang, $wgMessageCache, $wgUseFileCache, $wgShowDBErrorBacktrace;
2784
2785                 $sorry = 'Sorry! This site is experiencing technical difficulties.';
2786                 $again = 'Try waiting a few minutes and reloading.';
2787                 $info  = '(Can\'t contact the database server: $1)';
2788
2789                 if ( $wgLang instanceof Language ) {
2790                         $sorry = htmlspecialchars( $wgLang->getMessage( 'dberr-problems' ) );
2791                         $again = htmlspecialchars( $wgLang->getMessage( 'dberr-again' ) );
2792                         $info  = htmlspecialchars( $wgLang->getMessage( 'dberr-info' ) );
2793                 }
2794
2795                 # No database access
2796                 if ( is_object( $wgMessageCache ) ) {
2797                         $wgMessageCache->disable();
2798                 }
2799
2800                 if ( trim( $this->error ) == '' ) {
2801                         $this->error = $this->db->getProperty( 'mServer' );
2802                 }
2803
2804                 $noconnect = "<p><strong>$sorry</strong><br />$again</p><p><small>$info</small></p>";
2805                 $text = str_replace( '$1', $this->error, $noconnect );
2806
2807                 if ( $wgShowDBErrorBacktrace ) {
2808                         $text .= '<p>Backtrace:</p><p>' . nl2br( htmlspecialchars( $this->getTraceAsString() ) );
2809                 }
2810
2811                 $extra = $this->searchForm();
2812
2813                 if ( $wgUseFileCache ) {
2814                         try {
2815                                 $cache = $this->fileCachedPage();
2816                                 # Cached version on file system?
2817                                 if ( $cache !== null ) {
2818                                         # Hack: extend the body for error messages
2819                                         $cache = str_replace( array( '</html>', '</body>' ), '', $cache );
2820                                         # Add cache notice...
2821                                         $cachederror = "This is a cached copy of the requested page, and may not be up to date. ";
2822
2823                                         # Localize it if possible...
2824                                         if ( $wgLang instanceof Language ) {
2825                                                 $cachederror = htmlspecialchars( $wgLang->getMessage( 'dberr-cachederror' ) );
2826                                         }
2827
2828                                         $warning = "<div style='color:red;font-size:150%;font-weight:bold;'>$cachederror</div>";
2829
2830                                         # Output cached page with notices on bottom and re-close body
2831                                         return "{$cache}{$warning}<hr />$text<hr />$extra</body></html>";
2832                                 }
2833                         } catch ( MWException $e ) {
2834                                 // Do nothing, just use the default page
2835                         }
2836                 }
2837
2838                 # Headers needed here - output is just the error message
2839                 return $this->htmlHeader() . "$text<hr />$extra" . $this->htmlFooter();
2840         }
2841
2842         function searchForm() {
2843                 global $wgSitename, $wgServer, $wgLang, $wgInputEncoding;
2844
2845                 $usegoogle = "You can try searching via Google in the meantime.";
2846                 $outofdate = "Note that their indexes of our content may be out of date.";
2847                 $googlesearch = "Search";
2848
2849                 if ( $wgLang instanceof Language ) {
2850                         $usegoogle = htmlspecialchars( $wgLang->getMessage( 'dberr-usegoogle' ) );
2851                         $outofdate = htmlspecialchars( $wgLang->getMessage( 'dberr-outofdate' ) );
2852                         $googlesearch  = htmlspecialchars( $wgLang->getMessage( 'searchbutton' ) );
2853                 }
2854
2855                 $search = htmlspecialchars( @$_REQUEST['search'] );
2856
2857                 $trygoogle = <<<EOT
2858 <div style="margin: 1.5em">$usegoogle<br />
2859 <small>$outofdate</small></div>
2860 <!-- SiteSearch Google -->
2861 <form method="get" action="http://www.google.com/search" id="googlesearch">
2862         <input type="hidden" name="domains" value="$wgServer" />
2863         <input type="hidden" name="num" value="50" />
2864         <input type="hidden" name="ie" value="$wgInputEncoding" />
2865         <input type="hidden" name="oe" value="$wgInputEncoding" />
2866
2867         <input type="text" name="q" size="31" maxlength="255" value="$search" />
2868         <input type="submit" name="btnG" value="$googlesearch" />
2869   <div>
2870         <input type="radio" name="sitesearch" id="gwiki" value="$wgServer" checked="checked" /><label for="gwiki">$wgSitename</label>
2871         <input type="radio" name="sitesearch" id="gWWW" value="" /><label for="gWWW">WWW</label>
2872   </div>
2873 </form>
2874 <!-- SiteSearch Google -->
2875 EOT;
2876                 return $trygoogle;
2877         }
2878
2879         function fileCachedPage() {
2880                 global $wgTitle, $title, $wgLang, $wgOut;
2881
2882                 if ( $wgOut->isDisabled() ) {
2883                         return; // Done already?
2884                 }
2885
2886                 $mainpage = 'Main Page';
2887
2888                 if ( $wgLang instanceof Language ) {
2889                         $mainpage    = htmlspecialchars( $wgLang->getMessage( 'mainpage' ) );
2890                 }
2891
2892                 if ( $wgTitle ) {
2893                         $t =& $wgTitle;
2894                 } elseif ( $title ) {
2895                         $t = Title::newFromURL( $title );
2896                 } else {
2897                         $t = Title::newFromText( $mainpage );
2898                 }
2899
2900                 $cache = new HTMLFileCache( $t );
2901                 if ( $cache->isFileCached() ) {
2902                         return $cache->fetchPageText();
2903                 } else {
2904                         return '';
2905                 }
2906         }
2907
2908         function htmlBodyOnly() {
2909                 return true;
2910         }
2911 }
2912
2913 /**
2914  * @ingroup Database
2915  */
2916 class DBQueryError extends DBError {
2917         public $error, $errno, $sql, $fname;
2918
2919         function __construct( DatabaseBase &$db, $error, $errno, $sql, $fname ) {
2920                 $message = "A database error has occurred.  Did you forget to run maintenance/update.php after upgrading?  See: http://www.mediawiki.org/wiki/Manual:Upgrading#Run_the_update_script\n" .
2921                   "Query: $sql\n" .
2922                   "Function: $fname\n" .
2923                   "Error: $errno $error\n";
2924
2925                 parent::__construct( $db, $message );
2926
2927                 $this->error = $error;
2928                 $this->errno = $errno;
2929                 $this->sql = $sql;
2930                 $this->fname = $fname;
2931         }
2932
2933         function getText() {
2934                 global $wgShowDBErrorBacktrace;
2935
2936                 if ( $this->useMessageCache() ) {
2937                         $s = wfMsg( 'dberrortextcl', htmlspecialchars( $this->getSQL() ),
2938                                 htmlspecialchars( $this->fname ), $this->errno, htmlspecialchars( $this->error ) ) . "\n";
2939
2940                         if ( $wgShowDBErrorBacktrace ) {
2941                                 $s .= "Backtrace:\n" . $this->getTraceAsString() . "\n";
2942                         }
2943
2944                         return $s;
2945                 } else {
2946                         return parent::getText();
2947                 }
2948         }
2949
2950         function getSQL() {
2951                 global $wgShowSQLErrors;
2952
2953                 if ( !$wgShowSQLErrors ) {
2954                         return $this->msg( 'sqlhidden', 'SQL hidden' );
2955                 } else {
2956                         return $this->sql;
2957                 }
2958         }
2959
2960         function getLogMessage() {
2961                 # Don't send to the exception log
2962                 return false;
2963         }
2964
2965         function getPageTitle() {
2966                 return $this->msg( 'databaseerror', 'Database error' );
2967         }
2968
2969         function getHTML() {
2970                 global $wgShowDBErrorBacktrace;
2971
2972                 if ( $this->useMessageCache() ) {
2973                         $s = wfMsgNoDB( 'dberrortext', htmlspecialchars( $this->getSQL() ),
2974                           htmlspecialchars( $this->fname ), $this->errno, htmlspecialchars( $this->error ) );
2975                 } else {
2976                         $s = nl2br( htmlspecialchars( $this->getMessage() ) );
2977                 }
2978
2979                 if ( $wgShowDBErrorBacktrace ) {
2980                         $s .= '<p>Backtrace:</p><p>' . nl2br( htmlspecialchars( $this->getTraceAsString() ) );
2981                 }
2982
2983                 return $s;
2984         }
2985 }
2986
2987 /**
2988  * @ingroup Database
2989  */
2990 class DBUnexpectedError extends DBError {}
2991
2992
2993 /**
2994  * Result wrapper for grabbing data queried by someone else
2995  * @ingroup Database
2996  */
2997 class ResultWrapper implements Iterator {
2998         var $db, $result, $pos = 0, $currentRow = null;
2999
3000         /**
3001          * Create a new result object from a result resource and a Database object
3002          */
3003         function __construct( $database, $result ) {
3004                 $this->db = $database;
3005
3006                 if ( $result instanceof ResultWrapper ) {
3007                         $this->result = $result->result;
3008                 } else {
3009                         $this->result = $result;
3010                 }
3011         }
3012
3013         /**
3014          * Get the number of rows in a result object
3015          */
3016         function numRows() {
3017                 return $this->db->numRows( $this );
3018         }
3019
3020         /**
3021          * Fetch the next row from the given result object, in object form.
3022          * Fields can be retrieved with $row->fieldname, with fields acting like
3023          * member variables.
3024          *
3025          * @return MySQL row object
3026          * @throws DBUnexpectedError Thrown if the database returns an error
3027          */
3028         function fetchObject() {
3029                 return $this->db->fetchObject( $this );
3030         }
3031
3032         /**
3033          * Fetch the next row from the given result object, in associative array
3034          * form.  Fields are retrieved with $row['fieldname'].
3035          *
3036          * @return MySQL row object
3037          * @throws DBUnexpectedError Thrown if the database returns an error
3038          */
3039         function fetchRow() {
3040                 return $this->db->fetchRow( $this );
3041         }
3042
3043         /**
3044          * Free a result object
3045          */
3046         function free() {
3047                 $this->db->freeResult( $this );
3048                 unset( $this->result );
3049                 unset( $this->db );
3050         }
3051
3052         /**
3053          * Change the position of the cursor in a result object
3054          * See mysql_data_seek()
3055          */
3056         function seek( $row ) {
3057                 $this->db->dataSeek( $this, $row );
3058         }
3059
3060         /*********************
3061          * Iterator functions
3062          * Note that using these in combination with the non-iterator functions
3063          * above may cause rows to be skipped or repeated.
3064          */
3065
3066         function rewind() {
3067                 if ( $this->numRows() ) {
3068                         $this->db->dataSeek( $this, 0 );
3069                 }
3070                 $this->pos = 0;
3071                 $this->currentRow = null;
3072         }
3073
3074         function current() {
3075                 if ( is_null( $this->currentRow ) ) {
3076                         $this->next();
3077                 }
3078                 return $this->currentRow;
3079         }
3080
3081         function key() {
3082                 return $this->pos;
3083         }
3084
3085         function next() {
3086                 $this->pos++;
3087                 $this->currentRow = $this->fetchObject();
3088                 return $this->currentRow;
3089         }
3090
3091         function valid() {
3092                 return $this->current() !== false;
3093         }
3094 }
3095
3096 /**
3097  * Overloads the relevant methods of the real ResultsWrapper so it
3098  * doesn't go anywhere near an actual database.
3099  */
3100 class FakeResultWrapper extends ResultWrapper {
3101         var $result     = array();
3102         var $db         = null; // And it's going to stay that way :D
3103         var $pos        = 0;
3104         var $currentRow = null;
3105
3106         function __construct( $array ) {
3107                 $this->result = $array;
3108         }
3109
3110         function numRows() {
3111                 return count( $this->result );
3112         }
3113
3114         function fetchRow() {
3115                 $this->currentRow = $this->result[$this->pos++];
3116                 return $this->currentRow;
3117         }
3118
3119         function seek( $row ) {
3120                 $this->pos = $row;
3121         }
3122
3123         function free() {}
3124
3125         // Callers want to be able to access fields with $this->fieldName
3126         function fetchObject() {
3127                 $this->currentRow = $this->result[$this->pos++];
3128                 return (object)$this->currentRow;
3129         }
3130
3131         function rewind() {
3132                 $this->pos = 0;
3133                 $this->currentRow = null;
3134         }
3135 }
3136
3137 /**
3138  * Used by DatabaseBase::buildLike() to represent characters that have special meaning in SQL LIKE clauses
3139  * and thus need no escaping. Don't instantiate it manually, use DatabaseBase::anyChar() and anyString() instead.
3140  */
3141 class LikeMatch {
3142         private $str;
3143
3144         public function __construct( $s ) {
3145                 $this->str = $s;
3146         }
3147
3148         public function toString() {
3149                 return $this->str;
3150         }
3151 }