includes/db/DatabaseIbm_db2.php

   1 <?php
   2 /**
   3  * This script is the IBM DB2 database abstraction layer
   4  *
   5  * See maintenance/ibm_db2/README for development notes and other specific information
   6  * @ingroup Database
   7  * @file
   8  * @author leo.petr+mediawiki@gmail.com
   9  */
  10
  11 /**
  12  * This represents a column in a DB2 database
  13  * @ingroup Database
  14  */
  15 class IBM_DB2Field {
  16         private $name = '';
  17         private $tablename = '';
  18         private $type = '';
  19         private $nullable = false;
  20         private $max_length = 0;
  21
  22         /**
  23          * Builder method for the class
  24          * @param DatabaseIbm_db2 $db Database interface
  25          * @param string $table table name
  26          * @param string $field column name
  27          * @return IBM_DB2Field
  28          */
  29         static function fromText($db, $table, $field) {
  30                 global $wgDBmwschema;
  31
  32                 $q = <<<SQL
  33 SELECT
  34 lcase(coltype) AS typname,
  35 nulls AS attnotnull, length AS attlen
  36 FROM sysibm.syscolumns
  37 WHERE tbcreator=%s AND tbname=%s AND name=%s;
  38 SQL;
  39                 $res = $db->query(sprintf($q,
  40                                 $db->addQuotes($wgDBmwschema),
  41                                 $db->addQuotes($table),
  42                                 $db->addQuotes($field)));
  43                 $row = $db->fetchObject($res);
  44                 if (!$row)
  45                         return null;
  46                 $n = new IBM_DB2Field;
  47                 $n->type = $row->typname;
  48                 $n->nullable = ($row->attnotnull == 'N');
  49                 $n->name = $field;
  50                 $n->tablename = $table;
  51                 $n->max_length = $row->attlen;
  52                 return $n;
  53         }
  54         /**
  55          * Get column name
  56          * @return string column name
  57          */
  58         function name() { return $this->name; }
  59         /**
  60          * Get table name
  61          * @return string table name
  62          */
  63         function tableName() { return $this->tablename; }
  64         /**
  65          * Get column type
  66          * @return string column type
  67          */
  68         function type() { return $this->type; }
  69         /**
  70          * Can column be null?
  71          * @return bool true or false
  72          */
  73         function nullable() { return $this->nullable; }
  74         /**
  75          * How much can you fit in the column per row?
  76          * @return int length
  77          */
  78         function maxLength() { return $this->max_length; }
  79 }
  80
  81 /**
  82  * Wrapper around binary large objects
  83  * @ingroup Database
  84  */
  85 class IBM_DB2Blob {
  86         private $mData;
  87
  88         public function __construct($data) {
  89                 $this->mData = $data;
  90         }
  91
  92         public function getData() {
  93                 return $this->mData;
  94         }
  95
  96         public function __toString()
  97     {
  98         return $this->mData;
  99     }
 100 }
 101
 102 /**
 103  * Primary database interface
 104  * @ingroup Database
 105  */
 106 class DatabaseIbm_db2 extends DatabaseBase {
 107         /*
 108          * Inherited members
 109         protected $mLastQuery = '';
 110         protected $mPHPError = false;
 111
 112         protected $mServer, $mUser, $mPassword, $mConn = null, $mDBname;
 113         protected $mOut, $mOpened = false;
 114
 115         protected $mFailFunction;
 116         protected $mTablePrefix;
 117         protected $mFlags;
 118         protected $mTrxLevel = 0;
 119         protected $mErrorCount = 0;
 120         protected $mLBInfo = array();
 121         protected $mFakeSlaveLag = null, $mFakeMaster = false;
 122          *
 123          */
 124
 125         /// Server port for uncataloged connections
 126         protected $mPort = null;
 127         /// Whether connection is cataloged
 128         protected $mCataloged = null;
 129         /// Schema for tables, stored procedures, triggers
 130         protected $mSchema = null;
 131         /// Whether the schema has been applied in this session
 132         protected $mSchemaSet = false;
 133         /// Result of last query
 134         protected $mLastResult = null;
 135         /// Number of rows affected by last INSERT/UPDATE/DELETE
 136         protected $mAffectedRows = null;
 137         /// Number of rows returned by last SELECT
 138         protected $mNumRows = null;
 139
 140         /// Connection config options - see constructor
 141         public $mConnOptions = array();
 142         /// Statement config options -- see constructor
 143         public $mStmtOptions = array();
 144
 145
 146         const CATALOGED = "cataloged";
 147         const UNCATALOGED = "uncataloged";
 148         const USE_GLOBAL = "get from global";
 149
 150         const NONE_OPTION = 0x00;
 151         const CONN_OPTION = 0x01;
 152         const STMT_OPTION = 0x02;
 153
 154         const REGULAR_MODE = 'regular';
 155         const INSTALL_MODE = 'install';
 156
 157         // Whether this is regular operation or the initial installation
 158         protected $mMode = self::REGULAR_MODE;
 159
 160         /// Last sequence value used for a primary key
 161         protected $mInsertId = null;
 162
 163         /*
 164          * These can be safely inherited
 165          *
 166          * Getter/Setter: (18)
 167          * failFunction
 168          * setOutputPage
 169          * bufferResults
 170          * ignoreErrors
 171          * trxLevel
 172          * errorCount
 173          * getLBInfo
 174          * setLBInfo
 175          * lastQuery
 176          * isOpen
 177          * setFlag
 178          * clearFlag
 179          * getFlag
 180          * getProperty
 181          * getDBname
 182          * getServer
 183          * tableNameCallback
 184          * tablePrefix
 185          *
 186          * Administrative: (8)
 187          * debug
 188          * installErrorHandler
 189          * restoreErrorHandler
 190          * connectionErrorHandler
 191          * reportConnectionError
 192          * sourceFile
 193          * sourceStream
 194          * replaceVars
 195          *
 196          * Database: (5)
 197          * query
 198          * set
 199          * selectField
 200          * generalizeSQL
 201          * update
 202          * strreplace
 203          * deadlockLoop
 204          *
 205          * Prepared Statement: 6
 206          * prepare
 207          * freePrepared
 208          * execute
 209          * safeQuery
 210          * fillPrepared
 211          * fillPreparedArg
 212          *
 213          * Slave/Master: (4)
 214          * masterPosWait
 215          * getSlavePos
 216          * getMasterPos
 217          * getLag
 218          *
 219          * Generation: (9)
 220          * tableNames
 221          * tableNamesN
 222          * tableNamesWithUseIndexOrJOIN
 223          * escapeLike
 224          * delete
 225          * insertSelect
 226          * timestampOrNull
 227          * resultObject
 228          * aggregateValue
 229          * selectSQLText
 230          * selectRow
 231          * makeUpdateOptions
 232          *
 233          * Reflection: (1)
 234          * indexExists
 235          */
 236
 237         /*
 238          * These have been implemented
 239          *
 240          * Administrative: 7 / 7
 241          * constructor [Done]
 242          * open [Done]
 243          * openCataloged [Done]
 244          * close [Done]
 245          * newFromParams [Done]
 246          * openUncataloged [Done]
 247          * setup_database [Done]
 248          *
 249          * Getter/Setter: 13 / 13
 250          * cascadingDeletes [Done]
 251          * cleanupTriggers  [Done]
 252          * strictIPs  [Done]
 253          * realTimestamps  [Done]
 254          * impliciGroupby  [Done]
 255          * implicitOrderby  [Done]
 256          * searchableIPs  [Done]
 257          * functionalIndexes  [Done]
 258          * getWikiID  [Done]
 259          * isOpen [Done]
 260          * getServerVersion [Done]
 261          * getSoftwareLink [Done]
 262          * getSearchEngine [Done]
 263          *
 264          * Database driver wrapper: 23 / 23
 265          * lastError [Done]
 266          * lastErrno [Done]
 267          * doQuery [Done]
 268          * tableExists [Done]
 269          * fetchObject [Done]
 270          * fetchRow [Done]
 271          * freeResult [Done]
 272          * numRows [Done]
 273          * numFields [Done]
 274          * fieldName [Done]
 275          * insertId [Done]
 276          * dataSeek [Done]
 277          * affectedRows [Done]
 278          * selectDB [Done]
 279          * strencode [Done]
 280          * conditional [Done]
 281          * wasDeadlock [Done]
 282          * ping [Done]
 283          * getStatus [Done]
 284          * setTimeout [Done]
 285          * lock [Done]
 286          * unlock [Done]
 287          * insert [Done]
 288          * select [Done]
 289          *
 290          * Slave/master: 2 / 2
 291          * setFakeSlaveLag [Done]
 292          * setFakeMaster [Done]
 293          *
 294          * Reflection: 6 / 6
 295          * fieldExists [Done]
 296          * indexInfo [Done]
 297          * fieldInfo [Done]
 298          * fieldType [Done]
 299          * indexUnique [Done]
 300          * textFieldSize [Done]
 301          *
 302          * Generation: 16 / 16
 303          * tableName [Done]
 304          * addQuotes [Done]
 305          * makeList [Done]
 306          * makeSelectOptions [Done]
 307          * estimateRowCount [Done]
 308          * nextSequenceValue [Done]
 309          * useIndexClause [Done]
 310          * replace [Done]
 311          * deleteJoin [Done]
 312          * lowPriorityOption [Done]
 313          * limitResult [Done]
 314          * limitResultForUpdate [Done]
 315          * timestamp [Done]
 316          * encodeBlob [Done]
 317          * decodeBlob [Done]
 318          * buildConcat [Done]
 319          */
 320
 321         ######################################
 322         # Getters and Setters
 323         ######################################
 324
 325         /**
 326          * Returns true if this database supports (and uses) cascading deletes
 327          */
 328         function cascadingDeletes() {
 329                 return true;
 330         }
 331
 332         /**
 333          * Returns true if this database supports (and uses) triggers (e.g. on the page table)
 334          */
 335         function cleanupTriggers() {
 336                 return true;
 337         }
 338
 339         /**
 340          * Returns true if this database is strict about what can be put into an IP field.
 341          * Specifically, it uses a NULL value instead of an empty string.
 342          */
 343         function strictIPs() {
 344                 return true;
 345         }
 346
 347         /**
 348          * Returns true if this database uses timestamps rather than integers
 349         */
 350         function realTimestamps() {
 351                 return true;
 352         }
 353
 354         /**
 355          * Returns true if this database does an implicit sort when doing GROUP BY
 356          */
 357         function implicitGroupby() {
 358                 return false;
 359         }
 360
 361         /**
 362          * Returns true if this database does an implicit order by when the column has an index
 363          * For example: SELECT page_title FROM page LIMIT 1
 364          */
 365         function implicitOrderby() {
 366                 return false;
 367         }
 368
 369         /**
 370          * Returns true if this database can do a native search on IP columns
 371          * e.g. this works as expected: .. WHERE rc_ip = '127.42.12.102/32';
 372          */
 373         function searchableIPs() {
 374                 return true;
 375         }
 376
 377         /**
 378          * Returns true if this database can use functional indexes
 379          */
 380         function functionalIndexes() {
 381                 return true;
 382         }
 383
 384         /**
 385          * Returns a unique string representing the wiki on the server
 386          */
 387         function getWikiID() {
 388                 if( $this->mSchema ) {
 389                         return "{$this->mDBname}-{$this->mSchema}";
 390                 } else {
 391                         return $this->mDBname;
 392                 }
 393         }
 394
 395         function getType() {
 396                 return 'ibm_db2';
 397         }
 398
 399         ######################################
 400         # Setup
 401         ######################################
 402
 403
 404         /**
 405          *
 406          * @param string $server hostname of database server
 407          * @param string $user username
 408          * @param string $password
 409          * @param string $dbName database name on the server
 410          * @param function $failFunction (optional)
 411          * @param integer $flags database behaviour flags (optional, unused)
 412          */
 413         public function DatabaseIbm_db2($server = false, $user = false, $password = false,
 414                                                         $dbName = false, $failFunction = false, $flags = 0,
 415                                                         $schema = self::USE_GLOBAL )
 416         {
 417
 418                 global $wgOut, $wgDBmwschema;
 419                 # Can't get a reference if it hasn't been set yet
 420                 if ( !isset( $wgOut ) ) {
 421                         $wgOut = null;
 422                 }
 423                 $this->mOut =& $wgOut;
 424                 $this->mFailFunction = $failFunction;
 425                 $this->mFlags = DBO_TRX | $flags;
 426
 427                 if ( $schema == self::USE_GLOBAL ) {
 428                         $this->mSchema = $wgDBmwschema;
 429                 }
 430                 else {
 431                         $this->mSchema = $schema;
 432                 }
 433
 434                 // configure the connection and statement objects
 435                 $this->setDB2Option('db2_attr_case', 'DB2_CASE_LOWER', self::CONN_OPTION | self::STMT_OPTION);
 436                 $this->setDB2Option('deferred_prepare', 'DB2_DEFERRED_PREPARE_ON', self::STMT_OPTION);
 437                 $this->setDB2Option('rowcount', 'DB2_ROWCOUNT_PREFETCH_ON', self::STMT_OPTION);
 438
 439                 $this->open( $server, $user, $password, $dbName);
 440         }
 441
 442         /**
 443          * Enables options only if the ibm_db2 extension version supports them
 444          * @param string $name Name of the option in the options array
 445          * @param string $const Name of the constant holding the right option value
 446          * @param int $type Whether this is a Connection or Statement otion
 447          */
 448         private function setDB2Option($name, $const, $type) {
 449                 if (defined($const)) {
 450                         if ($type & self::CONN_OPTION) $this->mConnOptions[$name] = constant($const);
 451                         if ($type & self::STMT_OPTION) $this->mStmtOptions[$name] = constant($const);
 452                 }
 453                 else {
 454                         $this->installPrint("$const is not defined. ibm_db2 version is likely too low.");
 455                 }
 456         }
 457
 458         /**
 459          * Outputs debug information in the appropriate place
 460          * @param string $string The relevant debug message
 461          */
 462         private function installPrint($string) {
 463                 wfDebug("$string");
 464                 if ($this->mMode == self::INSTALL_MODE) {
 465                         print "<li>$string</li>";
 466                         flush();
 467                 }
 468         }
 469
 470         /**
 471          * Opens a database connection and returns it
 472          * Closes any existing connection
 473          * @return a fresh connection
 474          * @param string $server hostname
 475          * @param string $user
 476          * @param string $password
 477          * @param string $dbName database name
 478          */
 479         public function open( $server, $user, $password, $dbName )
 480         {
 481                 // Load the port number
 482                 global $wgDBport_db2, $wgDBcataloged;
 483                 wfProfileIn( __METHOD__ );
 484
 485                 // Load IBM DB2 driver if missing
 486                 if (!@extension_loaded('ibm_db2')) {
 487                         @dl('ibm_db2.so');
 488                 }
 489                 // Test for IBM DB2 support, to avoid suppressed fatal error
 490                 if ( !function_exists( 'db2_connect' ) ) {
 491                         $error = "DB2 functions missing, have you enabled the ibm_db2 extension for PHP?\n";
 492                         $this->installPrint($error);
 493                         $this->reportConnectionError($error);
 494                 }
 495
 496                 if (!strlen($user)) { // Copied from Postgres
 497                         return null;
 498                 }
 499
 500                 // Close existing connection
 501                 $this->close();
 502                 // Cache conn info
 503                 $this->mServer = $server;
 504                 $this->mPort = $port = $wgDBport_db2;
 505                 $this->mUser = $user;
 506                 $this->mPassword = $password;
 507                 $this->mDBname = $dbName;
 508                 $this->mCataloged = $cataloged = $wgDBcataloged;
 509
 510                 if ( $cataloged == self::CATALOGED ) {
 511                         $this->openCataloged($dbName, $user, $password);
 512                 }
 513                 elseif ( $cataloged == self::UNCATALOGED ) {
 514                         $this->openUncataloged($dbName, $user, $password, $server, $port);
 515                 }
 516                 // Apply connection config
 517                 db2_set_option($this->mConn, $this->mConnOptions, 1);
 518                 // Not all MediaWiki code is transactional
 519                 // Rather, turn autocommit off in the begin function and turn on after a commit
 520                 db2_autocommit($this->mConn, DB2_AUTOCOMMIT_ON);
 521
 522                 if ( $this->mConn == false ) {
 523                         $this->installPrint( "DB connection error\n" );
 524                         $this->installPrint( "Server: $server, Database: $dbName, User: $user, Password: " . substr( $password, 0, 3 ) . "...\n" );
 525                         $this->installPrint( $this->lastError()."\n" );
 526                         return null;
 527                 }
 528
 529                 $this->mOpened = true;
 530                 $this->applySchema();
 531
 532                 wfProfileOut( __METHOD__ );
 533                 return $this->mConn;
 534         }
 535
 536         /**
 537          * Opens a cataloged database connection, sets mConn
 538          */
 539         protected function openCataloged( $dbName, $user, $password )
 540         {
 541                 @$this->mConn = db2_connect($dbName, $user, $password);
 542         }
 543
 544         /**
 545          * Opens an uncataloged database connection, sets mConn
 546          */
 547         protected function openUncataloged( $dbName, $user, $password, $server, $port )
 548         {
 549                 $str = "DRIVER={IBM DB2 ODBC DRIVER};";
 550                 $str .= "DATABASE=$dbName;";
 551                 $str .= "HOSTNAME=$server;";
 552                 if ($port) $str .= "PORT=$port;";
 553                 $str .= "PROTOCOL=TCPIP;";
 554                 $str .= "UID=$user;";
 555                 $str .= "PWD=$password;";
 556
 557                 @$this->mConn = db2_connect($str, $user, $password);
 558         }
 559
 560         /**
 561          * Closes a database connection, if it is open
 562          * Returns success, true if already closed
 563          */
 564         public function close() {
 565                 $this->mOpened = false;
 566                 if ( $this->mConn ) {
 567                         if ($this->trxLevel() > 0) {
 568                                 $this->commit();
 569                         }
 570                         return db2_close( $this->mConn );
 571                 }
 572                 else {
 573                         return true;
 574                 }
 575         }
 576
 577         /**
 578          * Returns a fresh instance of this class
 579          * @static
 580          * @return
 581          * @param string $server hostname of database server
 582          * @param string $user username
 583          * @param string $password
 584          * @param string $dbName database name on the server
 585          * @param function $failFunction (optional)
 586          * @param integer $flags database behaviour flags (optional, unused)
 587          */
 588         static function newFromParams( $server, $user, $password, $dbName, $failFunction = false, $flags = 0)
 589         {
 590                 return new DatabaseIbm_db2( $server, $user, $password, $dbName, $failFunction, $flags );
 591         }
 592
 593         /**
 594          * Retrieves the most current database error
 595          * Forces a database rollback
 596          */
 597         public function lastError() {
 598                 $connerr = db2_conn_errormsg();
 599                 if ($connerr) {
 600                         //$this->rollback();
 601                         return $connerr;
 602                 }
 603                 $stmterr = db2_stmt_errormsg();
 604                 if ($stmterr) {
 605                         //$this->rollback();
 606                         return $stmterr;
 607                 }
 608
 609                 return false;
 610         }
 611
 612         /**
 613          * Get the last error number
 614          * Return 0 if no error
 615          * @return integer
 616          */
 617         public function lastErrno() {
 618                 $connerr = db2_conn_error();
 619                 if ($connerr) return $connerr;
 620                 $stmterr = db2_stmt_error();
 621                 if ($stmterr) return $stmterr;
 622                 return 0;
 623         }
 624
 625         /**
 626          * Is a database connection open?
 627          * @return
 628          */
 629         public function isOpen() { return $this->mOpened; }
 630
 631         /**
 632          * The DBMS-dependent part of query()
 633          * @param  $sql String: SQL query.
 634          * @return object Result object to feed to fetchObject, fetchRow, ...; or false on failure
 635          * @access private
 636          */
 637         /*private*/
 638         public function doQuery( $sql ) {
 639                 //print "<li><pre>$sql</pre></li>";
 640                 // Switch into the correct namespace
 641                 $this->applySchema();
 642
 643                 $ret = db2_exec( $this->mConn, $sql, $this->mStmtOptions );
 644                 if( !$ret ) {
 645                         print "<br><pre>";
 646                         print $sql;
 647                         print "</pre><br>";
 648                         $error = db2_stmt_errormsg();
 649                         throw new DBUnexpectedError($this,  'SQL error: ' . htmlspecialchars( $error ) );
 650                 }
 651                 $this->mLastResult = $ret;
 652                 $this->mAffectedRows = null;    // Not calculated until asked for
 653                 return $ret;
 654         }
 655
 656         /**
 657          * @return string Version information from the database
 658          */
 659         public function getServerVersion() {
 660                 $info = db2_server_info( $this->mConn );
 661                 return $info->DBMS_VER;
 662         }
 663
 664         /**
 665          * Queries whether a given table exists
 666          * @return boolean
 667          */
 668         public function tableExists( $table ) {
 669                 $schema = $this->mSchema;
 670                 $sql = <<< EOF
 671 SELECT COUNT(*) FROM SYSIBM.SYSTABLES ST
 672 WHERE ST.NAME = '$table' AND ST.CREATOR = '$schema'
 673 EOF;
 674                 $res = $this->query( $sql );
 675                 if (!$res) return false;
 676
 677                 // If the table exists, there should be one of it
 678                 @$row = $this->fetchRow($res);
 679                 $count = $row[0];
 680                 if ($count == '1' or $count == 1) {
 681                         return true;
 682                 }
 683
 684                 return false;
 685         }
 686
 687         /**
 688          * Fetch the next row from the given result object, in object form.
 689          * Fields can be retrieved with $row->fieldname, with fields acting like
 690          * member variables.
 691          *
 692          * @param $res SQL result object as returned from Database::query(), etc.
 693          * @return DB2 row object
 694          * @throws DBUnexpectedError Thrown if the database returns an error
 695          */
 696         public function fetchObject( $res ) {
 697                 if ( $res instanceof ResultWrapper ) {
 698                         $res = $res->result;
 699                 }
 700                 @$row = db2_fetch_object( $res );
 701                 if( $this->lastErrno() ) {
 702                         throw new DBUnexpectedError( $this, 'Error in fetchObject(): ' . htmlspecialchars( $this->lastError() ) );
 703                 }
 704                 return $row;
 705         }
 706
 707         /**
 708          * Fetch the next row from the given result object, in associative array
 709          * form.  Fields are retrieved with $row['fieldname'].
 710          *
 711          * @param $res SQL result object as returned from Database::query(), etc.
 712          * @return DB2 row object
 713          * @throws DBUnexpectedError Thrown if the database returns an error
 714          */
 715         public function fetchRow( $res ) {
 716                 if ( $res instanceof ResultWrapper ) {
 717                         $res = $res->result;
 718                 }
 719                 @$row = db2_fetch_array( $res );
 720                 if ( $this->lastErrno() ) {
 721                         throw new DBUnexpectedError( $this, 'Error in fetchRow(): ' . htmlspecialchars( $this->lastError() ) );
 722                 }
 723                 return $row;
 724         }
 725
 726         /**
 727          * Override if introduced to base Database class
 728          */
 729         public function initial_setup() {
 730                 // do nothing
 731         }
 732
 733         /**
 734          * Create tables, stored procedures, and so on
 735          */
 736         public function setup_database() {
 737                 // Timeout was being changed earlier due to mysterious crashes
 738                 // Changing it now may cause more problems than not changing it
 739                 //set_time_limit(240);
 740                 try {
 741                         // TODO: switch to root login if available
 742
 743                         // Switch into the correct namespace
 744                         $this->applySchema();
 745                         $this->begin();
 746
 747                         $res = $this->sourceFile( "../maintenance/ibm_db2/tables.sql" );
 748                         $res = null;
 749
 750                         // TODO: update mediawiki_version table
 751
 752                         // TODO: populate interwiki links
 753
 754                         if ($this->lastError()) {
 755                                 print "<li>Errors encountered during table creation -- rolled back</li>\n";
 756                                 print "<li>Please install again</li>\n";
 757                                 $this->rollback();
 758                         }
 759                         else {
 760                                 $this->commit();
 761                         }
 762                 }
 763                 catch (MWException $mwe)
 764                 {
 765                         print "<br><pre>$mwe</pre><br>";
 766                 }
 767         }
 768
 769         /**
 770          * Escapes strings
 771          * Doesn't escape numbers
 772          * @param string s string to escape
 773          * @return escaped string
 774          */
 775         public function addQuotes( $s ) {
 776                 //$this->installPrint("DB2::addQuotes($s)\n");
 777                 if ( is_null( $s ) ) {
 778                         return "NULL";
 779                 } else if ($s instanceof Blob) {
 780                         return "'".$s->fetch($s)."'";
 781                 } else if ($s instanceof IBM_DB2Blob) {
 782                         return "'".$this->decodeBlob($s)."'";
 783                 }
 784                 $s = $this->strencode($s);
 785                 if ( is_numeric($s) ) {
 786                         return $s;
 787                 }
 788                 else {
 789                         return "'$s'";
 790                 }
 791         }
 792
 793         /**
 794          * Verifies that a DB2 column/field type is numeric
 795          * @return bool true if numeric
 796          * @param string $type DB2 column type
 797          */
 798         public function is_numeric_type( $type ) {
 799                 switch (strtoupper($type)) {
 800                 case 'SMALLINT':
 801                 case 'INTEGER':
 802                 case 'INT':
 803                 case 'BIGINT':
 804                 case 'DECIMAL':
 805                 case 'REAL':
 806                 case 'DOUBLE':
 807                 case 'DECFLOAT':
 808                         return true;
 809                 }
 810                 return false;
 811         }
 812
 813         /**
 814          * Alias for addQuotes()
 815          * @param string s string to escape
 816          * @return escaped string
 817          */
 818         public function strencode( $s ) {
 819                 // Bloody useless function
 820                 //  Prepends backslashes to \x00, \n, \r, \, ', " and \x1a.
 821                 //  But also necessary
 822                 $s = db2_escape_string($s);
 823                 // Wide characters are evil -- some of them look like '
 824                 $s = utf8_encode($s);
 825                 // Fix its stupidity
 826                 $from = array("\\\\",   "\\'",  '\\n',  '\\t',  '\\"',  '\\r');
 827                 $to =   array("\\",             "''",   "\n",   "\t",   '"',    "\r");
 828                 $s = str_replace($from, $to, $s); // DB2 expects '', not \' escaping
 829                 return $s;
 830         }
 831
 832         /**
 833          * Switch into the database schema
 834          */
 835         protected function applySchema() {
 836                 if ( !($this->mSchemaSet) ) {
 837                         $this->mSchemaSet = true;
 838                         $this->begin();
 839                         $this->doQuery("SET SCHEMA = $this->mSchema");
 840                         $this->commit();
 841                 }
 842         }
 843
 844         /**
 845          * Start a transaction (mandatory)
 846          */
 847         public function begin( $fname = 'DatabaseIbm_db2::begin' ) {
 848                 // turn off auto-commit
 849                 db2_autocommit($this->mConn, DB2_AUTOCOMMIT_OFF);
 850                 $this->mTrxLevel = 1;
 851         }
 852
 853         /**
 854          * End a transaction
 855          * Must have a preceding begin()
 856          */
 857         public function commit( $fname = 'DatabaseIbm_db2::commit' ) {
 858                 db2_commit($this->mConn);
 859                 // turn auto-commit back on
 860                 db2_autocommit($this->mConn, DB2_AUTOCOMMIT_ON);
 861                 $this->mTrxLevel = 0;
 862         }
 863
 864         /**
 865          * Cancel a transaction
 866          */
 867         public function rollback( $fname = 'DatabaseIbm_db2::rollback' ) {
 868                 db2_rollback($this->mConn);
 869                 // turn auto-commit back on
 870                 // not sure if this is appropriate
 871                 db2_autocommit($this->mConn, DB2_AUTOCOMMIT_ON);
 872                 $this->mTrxLevel = 0;
 873         }
 874
 875         /**
 876          * Makes an encoded list of strings from an array
 877          * $mode:
 878          *        LIST_COMMA         - comma separated, no field names
 879          *        LIST_AND           - ANDed WHERE clause (without the WHERE)
 880          *        LIST_OR            - ORed WHERE clause (without the WHERE)
 881          *        LIST_SET           - comma separated with field names, like a SET clause
 882          *        LIST_NAMES         - comma separated field names
 883          */
 884         public function makeList( $a, $mode = LIST_COMMA ) {
 885                 if ( !is_array( $a ) ) {
 886                         throw new DBUnexpectedError( $this, 'Database::makeList called with incorrect parameters' );
 887                 }
 888
 889                 $first = true;
 890                 $list = '';
 891                 foreach ( $a as $field => $value ) {
 892                         if ( !$first ) {
 893                                 if ( $mode == LIST_AND ) {
 894                                         $list .= ' AND ';
 895                                 } elseif($mode == LIST_OR) {
 896                                         $list .= ' OR ';
 897                                 } else {
 898                                         $list .= ',';
 899                                 }
 900                         } else {
 901                                 $first = false;
 902                         }
 903                         if ( ($mode == LIST_AND || $mode == LIST_OR) && is_numeric( $field ) ) {
 904                                 $list .= "($value)";
 905                         } elseif ( ($mode == LIST_SET) && is_numeric( $field ) ) {
 906                                 $list .= "$value";
 907                         } elseif ( ($mode == LIST_AND || $mode == LIST_OR) && is_array($value) ) {
 908                                 if( count( $value ) == 0 ) {
 909                                         throw new MWException( __METHOD__.': empty input' );
 910                                 } elseif( count( $value ) == 1 ) {
 911                                         // Special-case single values, as IN isn't terribly efficient
 912                                         // Don't necessarily assume the single key is 0; we don't
 913                                         // enforce linear numeric ordering on other arrays here.
 914                                         $value = array_values( $value );
 915                                         $list .= $field." = ".$this->addQuotes( $value[0] );
 916                                 } else {
 917                                         $list .= $field." IN (".$this->makeList($value).") ";
 918                                 }
 919                         } elseif( is_null($value) ) {
 920                                 if ( $mode == LIST_AND || $mode == LIST_OR ) {
 921                                         $list .= "$field IS ";
 922                                 } elseif ( $mode == LIST_SET ) {
 923                                         $list .= "$field = ";
 924                                 }
 925                                 $list .= 'NULL';
 926                         } else {
 927                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
 928                                         $list .= "$field = ";
 929                                 }
 930                                 if ( $mode == LIST_NAMES ) {
 931                                         $list .= $value;
 932                                 }
 933                                 // Leo: Can't insert quoted numbers into numeric columns
 934                                 // (?) Might cause other problems. May have to check column type before insertion.
 935                                 else if ( is_numeric($value) ) {
 936                                         $list .= $value;
 937                                 }
 938                                 else {
 939                                         $list .= $this->addQuotes( $value );
 940                                 }
 941                         }
 942                 }
 943                 return $list;
 944         }
 945
 946         /**
 947          * Construct a LIMIT query with optional offset
 948          * This is used for query pages
 949          * $sql string SQL query we will append the limit too
 950          * $limit integer the SQL limit
 951          * $offset integer the SQL offset (default false)
 952          */
 953         public function limitResult($sql, $limit, $offset=false) {
 954                 if( !is_numeric($limit) ) {
 955                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
 956                 }
 957                 if( $offset ) {
 958                         $this->installPrint("Offset parameter not supported in limitResult()\n");
 959                 }
 960                 // TODO implement proper offset handling
 961                 // idea: get all the rows between 0 and offset, advance cursor to offset
 962                 return "$sql FETCH FIRST $limit ROWS ONLY ";
 963         }
 964
 965         /**
 966          * Handle reserved keyword replacement in table names
 967          * @return
 968          * @param $name Object
 969          */
 970         public function tableName( $name ) {
 971                 # Replace reserved words with better ones
 972 //              switch( $name ) {
 973 //                      case 'user':
 974 //                              return 'mwuser';
 975 //                      case 'text':
 976 //                              return 'pagecontent';
 977 //                      default:
 978 //                              return $name;
 979 //              }
 980                 // we want maximum compatibility with MySQL schema
 981                 return $name;
 982         }
 983
 984         /**
 985          * Generates a timestamp in an insertable format
 986          * @return string timestamp value
 987          * @param timestamp $ts
 988          */
 989         public function timestamp( $ts=0 ) {
 990                 // TS_MW cannot be easily distinguished from an integer
 991                 return wfTimestamp(TS_DB2,$ts);
 992         }
 993
 994         /**
 995          * Return the next in a sequence, save the value for retrieval via insertId()
 996          * @param string seqName Name of a defined sequence in the database
 997          * @return next value in that sequence
 998          */
 999         public function nextSequenceValue( $seqName ) {
1000                 // Not using sequences in the primary schema to allow for easy third-party migration scripts
1001                 // Emulating MySQL behaviour of using NULL to signal that sequences aren't used
1002                 /*
1003                 $safeseq = preg_replace( "/'/", "''", $seqName );
1004                 $res = $this->query( "VALUES NEXTVAL FOR $safeseq" );
1005                 $row = $this->fetchRow( $res );
1006                 $this->mInsertId = $row[0];
1007                 $this->freeResult( $res );
1008                 return $this->mInsertId;
1009                 */
1010                 return null;
1011         }
1012
1013         /**
1014          * This must be called after nextSequenceVal
1015          * @return Last sequence value used as a primary key
1016          */
1017         public function insertId() {
1018                 return $this->mInsertId;
1019         }
1020
1021         /**
1022          * Updates the mInsertId property with the value of the last insert into a generated column
1023          * @param string        $table          Sanitized table name
1024          * @param mixed         $primaryKey     String name of the primary key or a bool if this call is a do-nothing
1025          * @param resource      $stmt           Prepared statement resource
1026          *  of the SELECT primary_key FROM FINAL TABLE ( INSERT ... ) form
1027          */
1028         private function calcInsertId($table, $primaryKey, $stmt) {
1029                 if ($primaryKey) {
1030                         $id_row = $this->fetchRow($stmt);
1031                         $this->mInsertId = $id_row[0];
1032                 }
1033         }
1034
1035         /**
1036          * INSERT wrapper, inserts an array into a table
1037          *
1038          * $args may be a single associative array, or an array of these with numeric keys,
1039          * for multi-row insert
1040          *
1041          * @param array $table   String: Name of the table to insert to.
1042          * @param array $args    Array: Items to insert into the table.
1043          * @param array $fname   String: Name of the function, for profiling
1044          * @param mixed $options String or Array. Valid options: IGNORE
1045          *
1046          * @return bool Success of insert operation. IGNORE always returns true.
1047          */
1048         public function insert( $table, $args, $fname = 'DatabaseIbm_db2::insert', $options = array() ) {
1049                 if ( !count( $args ) ) {
1050                         return true;
1051                 }
1052                 // get database-specific table name (not used)
1053                 $table = $this->tableName( $table );
1054                 // format options as an array
1055                 if ( !is_array( $options ) ) $options = array( $options );
1056                 // format args as an array of arrays
1057                 if ( !( isset( $args[0] ) && is_array( $args[0] ) ) ) {
1058                         $args = array($args);
1059                 }
1060                 // prevent insertion of NULL into primary key columns
1061                 list($args, $primaryKeys) = $this->removeNullPrimaryKeys($table, $args);
1062                 // if there's only one primary key
1063                 // we'll be able to read its value after insertion
1064                 $primaryKey = false;
1065                 if (count($primaryKeys) == 1) {
1066                         $primaryKey = $primaryKeys[0];
1067                 }
1068
1069                 // get column names
1070                 $keys = array_keys( $args[0] );
1071                 $key_count = count($keys);
1072
1073                 // If IGNORE is set, we use savepoints to emulate mysql's behavior
1074                 $ignore = in_array( 'IGNORE', $options ) ? 'mw' : '';
1075
1076                 // assume success
1077                 $res = true;
1078                 // If we are not in a transaction, we need to be for savepoint trickery
1079                 $didbegin = 0;
1080                 if (! $this->mTrxLevel) {
1081                         $this->begin();
1082                         $didbegin = 1;
1083                 }
1084
1085                 $sql = "INSERT INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1086                 switch($key_count) {
1087                         //case 0 impossible
1088                         case 1:
1089                                 $sql .= '(?)';
1090                                 break;
1091                         default:
1092                                 $sql .= '(?' . str_repeat(',?', $key_count-1) . ')';
1093                 }
1094                 // add logic to read back the new primary key value
1095                 if ($primaryKey) {
1096                         $sql = "SELECT $primaryKey FROM FINAL TABLE($sql)";
1097                 }
1098                 $stmt = $this->prepare($sql);
1099
1100                 // start a transaction/enter transaction mode
1101                 $this->begin();
1102
1103                 if ( !$ignore ) {
1104                         $first = true;
1105                         foreach ( $args as $row ) {
1106                                 // insert each row into the database
1107                                 $res = $res & $this->execute($stmt, $row);
1108                                 // get the last inserted value into a generated column
1109                                 $this->calcInsertId($table, $primaryKey, $stmt);
1110                         }
1111                 }
1112                 else {
1113                         $olde = error_reporting( 0 );
1114                         // For future use, we may want to track the number of actual inserts
1115                         // Right now, insert (all writes) simply return true/false
1116                         $numrowsinserted = 0;
1117
1118                         // always return true
1119                         $res = true;
1120
1121                         foreach ( $args as $row ) {
1122                                 $overhead = "SAVEPOINT $ignore ON ROLLBACK RETAIN CURSORS";
1123                                 db2_exec($this->mConn, $overhead, $this->mStmtOptions);
1124
1125                                 $res2 = $this->execute($stmt, $row);
1126                                 // get the last inserted value into a generated column
1127                                 $this->calcInsertId($table, $primaryKey, $stmt);
1128
1129                                 $errNum = $this->lastErrno();
1130                                 if ($errNum) {
1131                                         db2_exec( $this->mConn, "ROLLBACK TO SAVEPOINT $ignore", $this->mStmtOptions );
1132                                 }
1133                                 else {
1134                                         db2_exec( $this->mConn, "RELEASE SAVEPOINT $ignore", $this->mStmtOptions );
1135                                         $numrowsinserted++;
1136                                 }
1137                         }
1138
1139                         $olde = error_reporting( $olde );
1140                         // Set the affected row count for the whole operation
1141                         $this->mAffectedRows = $numrowsinserted;
1142                 }
1143                 // commit either way
1144                 $this->commit();
1145
1146                 return $res;
1147         }
1148
1149         /**
1150          * Given a table name and a hash of columns with values
1151          * Removes primary key columns from the hash where the value is NULL
1152          *
1153          * @param string $table Name of the table
1154          * @param array $args Array of hashes of column names with values
1155          * @return array Tuple containing filtered array of columns, array of primary keys
1156          */
1157         private function removeNullPrimaryKeys($table, $args) {
1158                 $schema = $this->mSchema;
1159                 // find out the primary keys
1160                 $keyres = db2_primary_keys($this->mConn, null, strtoupper($schema), strtoupper($table));
1161                 $keys = array();
1162                 for ($row = $this->fetchObject($keyres); $row != null; $row = $this->fetchRow($keyres)) {
1163                         $keys[] = strtolower($row->column_name);
1164                 }
1165                 // remove primary keys
1166                 foreach ($args as $ai => $row) {
1167                         foreach ($keys as $ki => $key) {
1168                                 if ($row[$key] == null) {
1169                                         unset($row[$key]);
1170                                 }
1171                         }
1172                         $args[$ai] = $row;
1173                 }
1174                 // return modified hash
1175                 return array($args, $keys);
1176         }
1177
1178         /**
1179          * UPDATE wrapper, takes a condition array and a SET array
1180          *
1181          * @param string $table  The table to UPDATE
1182          * @param array  $values An array of values to SET
1183          * @param array  $conds  An array of conditions (WHERE). Use '*' to update all rows.
1184          * @param string $fname  The Class::Function calling this function
1185          *                       (for the log)
1186          * @param array  $options An array of UPDATE options, can be one or
1187          *                        more of IGNORE, LOW_PRIORITY
1188          * @return bool
1189          */
1190         public function update( $table, $values, $conds, $fname = 'Database::update', $options = array() ) {
1191                 $table = $this->tableName( $table );
1192                 $opts = $this->makeUpdateOptions( $options );
1193                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1194                 if ( $conds != '*' ) {
1195                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1196                 }
1197                 return $this->query( $sql, $fname );
1198         }
1199
1200         /**
1201          * DELETE query wrapper
1202          *
1203          * Use $conds == "*" to delete all rows
1204          */
1205         public function delete( $table, $conds, $fname = 'Database::delete' ) {
1206                 if ( !$conds ) {
1207                         throw new DBUnexpectedError( $this, 'Database::delete() called with no conditions' );
1208                 }
1209                 $table = $this->tableName( $table );
1210                 $sql = "DELETE FROM $table";
1211                 if ( $conds != '*' ) {
1212                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1213                 }
1214                 return $this->query( $sql, $fname );
1215         }
1216
1217         /**
1218          * Returns the number of rows affected by the last query or 0
1219          * @return int the number of rows affected by the last query
1220          */
1221         public function affectedRows() {
1222                 if ( !is_null( $this->mAffectedRows ) ) {
1223                         // Forced result for simulated queries
1224                         return $this->mAffectedRows;
1225                 }
1226                 if( empty( $this->mLastResult ) )
1227                         return 0;
1228                 return db2_num_rows( $this->mLastResult );
1229         }
1230
1231         /**
1232          * Simulates REPLACE with a DELETE followed by INSERT
1233          * @param $table Object
1234          * @param array $uniqueIndexes array consisting of indexes and arrays of indexes
1235          * @param array $rows Rows to insert
1236          * @param string $fname Name of the function for profiling
1237          * @return nothing
1238          */
1239         function replace( $table, $uniqueIndexes, $rows, $fname = 'DatabaseIbm_db2::replace' ) {
1240                 $table = $this->tableName( $table );
1241
1242                 if (count($rows)==0) {
1243                         return;
1244                 }
1245
1246                 # Single row case
1247                 if ( !is_array( reset( $rows ) ) ) {
1248                         $rows = array( $rows );
1249                 }
1250
1251                 foreach( $rows as $row ) {
1252                         # Delete rows which collide
1253                         if ( $uniqueIndexes ) {
1254                                 $sql = "DELETE FROM $table WHERE ";
1255                                 $first = true;
1256                                 foreach ( $uniqueIndexes as $index ) {
1257                                         if ( $first ) {
1258                                                 $first = false;
1259                                                 $sql .= "(";
1260                                         } else {
1261                                                 $sql .= ') OR (';
1262                                         }
1263                                         if ( is_array( $index ) ) {
1264                                                 $first2 = true;
1265                                                 foreach ( $index as $col ) {
1266                                                         if ( $first2 ) {
1267                                                                 $first2 = false;
1268                                                         } else {
1269                                                                 $sql .= ' AND ';
1270                                                         }
1271                                                         $sql .= $col.'=' . $this->addQuotes( $row[$col] );
1272                                                 }
1273                                         } else {
1274                                                 $sql .= $index.'=' . $this->addQuotes( $row[$index] );
1275                                         }
1276                                 }
1277                                 $sql .= ')';
1278                                 $this->query( $sql, $fname );
1279                         }
1280
1281                         # Now insert the row
1282                         $sql = "INSERT INTO $table (" . $this->makeList( array_keys( $row ), LIST_NAMES ) .') VALUES (' .
1283                                 $this->makeList( $row, LIST_COMMA ) . ')';
1284                         $this->query( $sql, $fname );
1285                 }
1286         }
1287
1288         /**
1289          * Returns the number of rows in the result set
1290          * Has to be called right after the corresponding select query
1291          * @param object $res result set
1292          * @return int number of rows
1293          */
1294         public function numRows( $res ) {
1295                 if ( $res instanceof ResultWrapper ) {
1296                         $res = $res->result;
1297                 }
1298                 if ( $this->mNumRows ) {
1299                         return $this->mNumRows;
1300                 }
1301                 else {
1302                         return 0;
1303                 }
1304         }
1305
1306         /**
1307          * Moves the row pointer of the result set
1308          * @param object $res result set
1309          * @param int $row row number
1310          * @return success or failure
1311          */
1312         public function dataSeek( $res, $row ) {
1313                 if ( $res instanceof ResultWrapper ) {
1314                         $res = $res->result;
1315                 }
1316                 return db2_fetch_row( $res, $row );
1317         }
1318
1319         ###
1320         # Fix notices in Block.php
1321         ###
1322
1323         /**
1324          * Frees memory associated with a statement resource
1325          * @param object $res Statement resource to free
1326          * @return bool success or failure
1327          */
1328         public function freeResult( $res ) {
1329                 if ( $res instanceof ResultWrapper ) {
1330                         $res = $res->result;
1331                 }
1332                 if ( !@db2_free_result( $res ) ) {
1333                         throw new DBUnexpectedError($this,  "Unable to free DB2 result\n" );
1334                 }
1335         }
1336
1337         /**
1338          * Returns the number of columns in a resource
1339          * @param object $res Statement resource
1340          * @return Number of fields/columns in resource
1341          */
1342         public function numFields( $res ) {
1343                 if ( $res instanceof ResultWrapper ) {
1344                         $res = $res->result;
1345                 }
1346                 return db2_num_fields( $res );
1347         }
1348
1349         /**
1350          * Returns the nth column name
1351          * @param object $res Statement resource
1352          * @param int $n Index of field or column
1353          * @return string name of nth column
1354          */
1355         public function fieldName( $res, $n ) {
1356                 if ( $res instanceof ResultWrapper ) {
1357                         $res = $res->result;
1358                 }
1359                 return db2_field_name( $res, $n );
1360         }
1361
1362         /**
1363          * SELECT wrapper
1364          *
1365          * @param mixed  $table   Array or string, table name(s) (prefix auto-added)
1366          * @param mixed  $vars    Array or string, field name(s) to be retrieved
1367          * @param mixed  $conds   Array or string, condition(s) for WHERE
1368          * @param string $fname   Calling function name (use __METHOD__) for logs/profiling
1369          * @param array  $options Associative array of options (e.g. array('GROUP BY' => 'page_title')),
1370          *                        see Database::makeSelectOptions code for list of supported stuff
1371          * @param array $join_conds Associative array of table join conditions (optional)
1372          *                        (e.g. array( 'page' => array('LEFT JOIN','page_latest=rev_id') )
1373          * @return mixed Database result resource (feed to Database::fetchObject or whatever), or false on failure
1374          */
1375         public function select( $table, $vars, $conds='', $fname = 'DatabaseIbm_db2::select', $options = array(), $join_conds = array() )
1376         {
1377                 $res = parent::select( $table, $vars, $conds, $fname, $options, $join_conds );
1378
1379                 // We must adjust for offset
1380                 if ( isset( $options['LIMIT'] ) ) {
1381                         if ( isset ($options['OFFSET'] ) ) {
1382                                 $limit = $options['LIMIT'];
1383                                 $offset = $options['OFFSET'];
1384                         }
1385                 }
1386
1387
1388                 // DB2 does not have a proper num_rows() function yet, so we must emulate it
1389                 // DB2 9.5.3/9.5.4 and the corresponding ibm_db2 driver will introduce a working one
1390                 // Yay!
1391
1392                 // we want the count
1393                 $vars2 = array('count(*) as num_rows');
1394                 // respecting just the limit option
1395                 $options2 = array();
1396                 if ( isset( $options['LIMIT'] ) ) $options2['LIMIT'] = $options['LIMIT'];
1397                 // but don't try to emulate for GROUP BY
1398                 if ( isset( $options['GROUP BY'] ) ) return $res;
1399
1400                 $res2 = parent::select( $table, $vars2, $conds, $fname, $options2, $join_conds );
1401                 $obj = $this->fetchObject($res2);
1402                 $this->mNumRows = $obj->num_rows;
1403
1404
1405                 return $res;
1406         }
1407
1408         /**
1409          * Handles ordering, grouping, and having options ('GROUP BY' => colname)
1410          * Has limited support for per-column options (colnum => 'DISTINCT')
1411          *
1412          * @private
1413          *
1414          * @param array $options an associative array of options to be turned into
1415          *              an SQL query, valid keys are listed in the function.
1416          * @return array
1417          */
1418         function makeSelectOptions( $options ) {
1419                 $preLimitTail = $postLimitTail = '';
1420                 $startOpts = '';
1421
1422                 $noKeyOptions = array();
1423                 foreach ( $options as $key => $option ) {
1424                         if ( is_numeric( $key ) ) {
1425                                 $noKeyOptions[$option] = true;
1426                         }
1427                 }
1428
1429                 if ( isset( $options['GROUP BY'] ) ) $preLimitTail .= " GROUP BY {$options['GROUP BY']}";
1430                 if ( isset( $options['HAVING'] ) ) $preLimitTail .= " HAVING {$options['HAVING']}";
1431                 if ( isset( $options['ORDER BY'] ) ) $preLimitTail .= " ORDER BY {$options['ORDER BY']}";
1432
1433                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) $startOpts .= 'DISTINCT';
1434
1435                 return array( $startOpts, '', $preLimitTail, $postLimitTail );
1436         }
1437
1438         /**
1439          * Returns link to IBM DB2 free download
1440          * @return string wikitext of a link to the server software's web site
1441          */
1442         public function getSoftwareLink() {
1443                 return "[http://www.ibm.com/software/data/db2/express/?s_cmp=ECDDWW01&s_tact=MediaWiki IBM DB2]";
1444         }
1445
1446         /**
1447          * Get search engine class. All subclasses of this
1448          * need to implement this if they wish to use searching.
1449          *
1450          * @return string
1451          */
1452         public function getSearchEngine() {
1453                 return "SearchIBM_DB2";
1454         }
1455
1456         /**
1457          * Did the last database access fail because of deadlock?
1458          * @return bool
1459          */
1460         public function wasDeadlock() {
1461                 // get SQLSTATE
1462                 $err = $this->lastErrno();
1463                 switch($err) {
1464                         case '40001':   // sql0911n, Deadlock or timeout, rollback
1465                         case '57011':   // sql0904n, Resource unavailable, no rollback
1466                         case '57033':   // sql0913n, Deadlock or timeout, no rollback
1467                         $this->installPrint("In a deadlock because of SQLSTATE $err");
1468                         return true;
1469                 }
1470                 return false;
1471         }
1472
1473         /**
1474          * Ping the server and try to reconnect if it there is no connection
1475          * The connection may be closed and reopened while this happens
1476          * @return bool whether the connection exists
1477          */
1478         public function ping() {
1479                 // db2_ping() doesn't exist
1480                 // Emulate
1481                 $this->close();
1482                 if ($this->mCataloged == null) {
1483                         return false;
1484                 }
1485                 else if ($this->mCataloged) {
1486                         $this->mConn = $this->openCataloged($this->mDBName, $this->mUser, $this->mPassword);
1487                 }
1488                 else if (!$this->mCataloged) {
1489                         $this->mConn = $this->openUncataloged($this->mDBName, $this->mUser, $this->mPassword, $this->mServer, $this->mPort);
1490                 }
1491                 return false;
1492         }
1493         ######################################
1494         # Unimplemented and not applicable
1495         ######################################
1496         /**
1497          * Not implemented
1498          * @return string ''
1499          * @deprecated
1500          */
1501         public function getStatus( $which="%" ) { $this->installPrint('Not implemented for DB2: getStatus()'); return ''; }
1502         /**
1503          * Not implemented
1504          * TODO
1505          * @return bool true
1506          */
1507         /**
1508          * Not implemented
1509          * @deprecated
1510          */
1511         public function setFakeSlaveLag( $lag ) { $this->installPrint('Not implemented for DB2: setFakeSlaveLag()'); }
1512         /**
1513          * Not implemented
1514          * @deprecated
1515          */
1516         public function setFakeMaster( $enabled = true ) { $this->installPrint('Not implemented for DB2: setFakeMaster()'); }
1517         /**
1518          * Not implemented
1519          * @return string $sql
1520          * @deprecated
1521          */
1522         public function limitResultForUpdate($sql, $num) { $this->installPrint('Not implemented for DB2: limitResultForUpdate()'); return $sql; }
1523
1524         /**
1525          * Only useful with fake prepare like in base Database class
1526          * @return      string
1527          */
1528         public function fillPreparedArg( $matches ) { $this->installPrint('Not useful for DB2: fillPreparedArg()'); return ''; }
1529
1530         ######################################
1531         # Reflection
1532         ######################################
1533
1534         /**
1535          * Query whether a given column exists in the mediawiki schema
1536          * @param string $table name of the table
1537          * @param string $field name of the column
1538          * @param string $fname function name for logging and profiling
1539          */
1540         public function fieldExists( $table, $field, $fname = 'DatabaseIbm_db2::fieldExists' ) {
1541                 $table = $this->tableName( $table );
1542                 $schema = $this->mSchema;
1543                 $etable = preg_replace("/'/", "''", $table);
1544                 $eschema = preg_replace("/'/", "''", $schema);
1545                 $ecol = preg_replace("/'/", "''", $field);
1546                 $sql = <<<SQL
1547 SELECT 1 as fieldexists
1548 FROM sysibm.syscolumns sc
1549 WHERE sc.name='$ecol' AND sc.tbname='$etable' AND sc.tbcreator='$eschema'
1550 SQL;
1551                 $res = $this->query( $sql, $fname );
1552                 $count = $res ? $this->numRows($res) : 0;
1553                 if ($res)
1554                         $this->freeResult( $res );
1555                 return $count;
1556         }
1557
1558         /**
1559          * Returns information about an index
1560          * If errors are explicitly ignored, returns NULL on failure
1561          * @param string $table table name
1562          * @param string $index index name
1563          * @param string
1564          * @return object query row in object form
1565          */
1566         public function indexInfo( $table, $index, $fname = 'DatabaseIbm_db2::indexExists' ) {
1567                 $table = $this->tableName( $table );
1568                 $sql = <<<SQL
1569 SELECT name as indexname
1570 FROM sysibm.sysindexes si
1571 WHERE si.name='$index' AND si.tbname='$table' AND sc.tbcreator='$this->mSchema'
1572 SQL;
1573                 $res = $this->query( $sql, $fname );
1574                 if ( !$res ) {
1575                         return null;
1576                 }
1577                 $row = $this->fetchObject( $res );
1578                 if ($row != null) return $row;
1579                 else return false;
1580         }
1581
1582         /**
1583          * Returns an information object on a table column
1584          * @param string $table table name
1585          * @param string $field column name
1586          * @return IBM_DB2Field
1587          */
1588         public function fieldInfo( $table, $field ) {
1589                 return IBM_DB2Field::fromText($this, $table, $field);
1590         }
1591
1592         /**
1593          * db2_field_type() wrapper
1594          * @param object $res Result of executed statement
1595          * @param mixed $index number or name of the column
1596          * @return string column type
1597          */
1598         public function fieldType( $res, $index ) {
1599                 if ( $res instanceof ResultWrapper ) {
1600                         $res = $res->result;
1601                 }
1602                 return db2_field_type( $res, $index );
1603         }
1604
1605         /**
1606          * Verifies that an index was created as unique
1607          * @param string $table table name
1608          * @param string $index index name
1609          * @param string $fnam function name for profiling
1610          * @return bool
1611          */
1612         public function indexUnique ($table, $index, $fname = 'Database::indexUnique' ) {
1613                 $table = $this->tableName( $table );
1614                 $sql = <<<SQL
1615 SELECT si.name as indexname
1616 FROM sysibm.sysindexes si
1617 WHERE si.name='$index' AND si.tbname='$table' AND sc.tbcreator='$this->mSchema'
1618 AND si.uniquerule IN ('U', 'P')
1619 SQL;
1620                 $res = $this->query( $sql, $fname );
1621                 if ( !$res ) {
1622                         return null;
1623                 }
1624                 if ($this->fetchObject( $res )) {
1625                         return true;
1626                 }
1627                 return false;
1628
1629         }
1630
1631         /**
1632          * Returns the size of a text field, or -1 for "unlimited"
1633          * @param string $table table name
1634          * @param string $field column name
1635          * @return int length or -1 for unlimited
1636          */
1637         public function textFieldSize( $table, $field ) {
1638                 $table = $this->tableName( $table );
1639                 $sql = <<<SQL
1640 SELECT length as size
1641 FROM sysibm.syscolumns sc
1642 WHERE sc.name='$field' AND sc.tbname='$table' AND sc.tbcreator='$this->mSchema'
1643 SQL;
1644                 $res = $this->query($sql);
1645                 $row = $this->fetchObject($res);
1646                 $size = $row->size;
1647                 $this->freeResult( $res );
1648                 return $size;
1649         }
1650
1651         /**
1652          * DELETE where the condition is a join
1653          * @param string $delTable deleting from this table
1654          * @param string $joinTable using data from this table
1655          * @param string $delVar variable in deleteable table
1656          * @param string $joinVar variable in data table
1657          * @param array $conds conditionals for join table
1658          * @param string $fname function name for profiling
1659          */
1660         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds, $fname = "DatabaseIbm_db2::deleteJoin" ) {
1661                 if ( !$conds ) {
1662                         throw new DBUnexpectedError($this,  'Database::deleteJoin() called with empty $conds' );
1663                 }
1664
1665                 $delTable = $this->tableName( $delTable );
1666                 $joinTable = $this->tableName( $joinTable );
1667                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
1668                 if ( $conds != '*' ) {
1669                         $sql .= 'WHERE ' . $this->makeList( $conds, LIST_AND );
1670                 }
1671                 $sql .= ')';
1672
1673                 $this->query( $sql, $fname );
1674         }
1675
1676         /**
1677          * Description is left as an exercise for the reader
1678          * @param mixed $b data to be encoded
1679          * @return IBM_DB2Blob
1680          */
1681         public function encodeBlob($b) {
1682                 return new IBM_DB2Blob($b);
1683         }
1684
1685         /**
1686          * Description is left as an exercise for the reader
1687          * @param IBM_DB2Blob $b data to be decoded
1688          * @return mixed
1689          */
1690         public function decodeBlob($b) {
1691                 return $b->getData();
1692         }
1693
1694         /**
1695          * Convert into a list of string being concatenated
1696          * @param array $stringList strings that need to be joined together by the SQL engine
1697          * @return string joined by the concatenation operator
1698          */
1699         public function buildConcat( $stringList ) {
1700                 // || is equivalent to CONCAT
1701                 // Sample query: VALUES 'foo' CONCAT 'bar' CONCAT 'baz'
1702                 return implode( ' || ', $stringList );
1703         }
1704
1705         /**
1706          * Generates the SQL required to convert a DB2 timestamp into a Unix epoch
1707          * @param string $column name of timestamp column
1708          * @return string SQL code
1709          */
1710         public function extractUnixEpoch( $column ) {
1711                 // TODO
1712                 // see SpecialAncientpages
1713         }
1714
1715         ######################################
1716         # Prepared statements
1717         ######################################
1718
1719         /**
1720          * Intended to be compatible with the PEAR::DB wrapper functions.
1721          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
1722          *
1723          * ? = scalar value, quoted as necessary
1724          * ! = raw SQL bit (a function for instance)
1725          * & = filename; reads the file and inserts as a blob
1726          *     (we don't use this though...)
1727          * @param string $sql SQL statement with appropriate markers
1728          * @return resource a prepared DB2 SQL statement
1729          */
1730         public function prepare( $sql, $func = 'DB2::prepare' ) {
1731                 $stmt = db2_prepare($this->mConn, $sql, $this->mStmtOptions);
1732                 return $stmt;
1733         }
1734
1735         /**
1736          * Frees resources associated with a prepared statement
1737          * @return bool success or failure
1738          */
1739         public function freePrepared( $prepared ) {
1740                 return db2_free_stmt($prepared);
1741         }
1742
1743         /**
1744          * Execute a prepared query with the various arguments
1745          * @param       string          $prepared       the prepared sql
1746          * @param       mixed           $args           Either an array here, or put scalars as varargs
1747          * @return      resource                                Results object
1748          */
1749         public function execute( $prepared, $args = null ) {
1750                 if( !is_array( $args ) ) {
1751                         # Pull the var args
1752                         $args = func_get_args();
1753                         array_shift( $args );
1754                 }
1755                 $res = db2_execute($prepared, $args);
1756                 return $res;
1757         }
1758
1759         /**
1760          * Prepare & execute an SQL statement, quoting and inserting arguments
1761          * in the appropriate places.
1762          * @param $query String
1763          * @param $args ...
1764          */
1765         public function safeQuery( $query, $args = null ) {
1766                 // copied verbatim from Database.php
1767                 $prepared = $this->prepare( $query, 'DB2::safeQuery' );
1768                 if( !is_array( $args ) ) {
1769                         # Pull the var args
1770                         $args = func_get_args();
1771                         array_shift( $args );
1772                 }
1773                 $retval = $this->execute( $prepared, $args );
1774                 $this->freePrepared( $prepared );
1775                 return $retval;
1776         }
1777
1778         /**
1779          * For faking prepared SQL statements on DBs that don't support
1780          * it directly.
1781          * @param       resource        $preparedQuery  String: a 'preparable' SQL statement
1782          * @param       array           $args                   Array of arguments to fill it with
1783          * @return      string                                          executable statement
1784          */
1785         public function fillPrepared( $preparedQuery, $args ) {
1786                 reset( $args );
1787                 $this->preparedArgs =& $args;
1788
1789                 foreach ($args as $i => $arg) {
1790                         db2_bind_param($preparedQuery, $i+1, $args[$i]);
1791                 }
1792
1793                 return $preparedQuery;
1794         }
1795
1796         /**
1797          * Switches module between regular and install modes
1798          */
1799         public function setMode($mode) {
1800                 $old =  $this->mMode;
1801                 $this->mMode = $mode;
1802                 return $old;
1803         }
1804
1805         /**
1806          * Bitwise negation of a column or value in SQL
1807          * Same as (~field) in C
1808          * @param       string  $field
1809          * @return      string
1810          */
1811         function bitNot($field) {
1812                 //expecting bit-fields smaller than 4bytes
1813                 return 'BITNOT('.$bitField.')';
1814         }
1815
1816         /**
1817          * Bitwise AND of two columns or values in SQL
1818          * Same as (fieldLeft & fieldRight) in C
1819          * @param       string  $fieldLeft
1820          * @param       string  $fieldRight
1821          * @return      string
1822          */
1823         function bitAnd($fieldLeft, $fieldRight) {
1824                 return 'BITAND('.$fieldLeft.', '.$fieldRight.')';
1825         }
1826
1827         /**
1828          * Bitwise OR of two columns or values in SQL
1829          * Same as (fieldLeft | fieldRight) in C
1830          * @param       string  $fieldLeft
1831          * @param       string  $fieldRight
1832          * @return      string
1833          */
1834         function bitOr($fieldLeft, $fieldRight) {
1835                 return 'BITOR('.$fieldLeft.', '.$fieldRight.')';
1836         }
1837 }