includes/db/DatabaseIbm_db2.php

   1 <?php
   2 /**
   3  * This is the IBM DB2 database abstraction layer.
   4  * See maintenance/ibm_db2/README for development notes
   5  * and other specific information
   6  *
   7  * @file
   8  * @ingroup Database
   9  * @author leo.petr+mediawiki@gmail.com
  10  */
  11
  12 /**
  13  * This represents a column in a DB2 database
  14  * @ingroup Database
  15  */
  16 class IBM_DB2Field implements Field {
  17         private $name = '';
  18         private $tablename = '';
  19         private $type = '';
  20         private $nullable = false;
  21         private $max_length = 0;
  22
  23         /**
  24          * Builder method for the class
  25          * @param $db DatabaseIbm_db2: Database interface
  26          * @param $table String: table name
  27          * @param $field String: column name
  28          * @return IBM_DB2Field
  29          */
  30         static function fromText( $db, $table, $field ) {
  31                 global $wgDBmwschema;
  32
  33                 $q = <<<SQL
  34 SELECT
  35 lcase( coltype ) AS typname,
  36 nulls AS attnotnull, length AS attlen
  37 FROM sysibm.syscolumns
  38 WHERE tbcreator=%s AND tbname=%s AND name=%s;
  39 SQL;
  40                 $res = $db->query(
  41                         sprintf( $q,
  42                                 $db->addQuotes( $wgDBmwschema ),
  43                                 $db->addQuotes( $table ),
  44                                 $db->addQuotes( $field )
  45                         )
  46                 );
  47                 $row = $db->fetchObject( $res );
  48                 if ( !$row ) {
  49                         return null;
  50                 }
  51                 $n = new IBM_DB2Field;
  52                 $n->type = $row->typname;
  53                 $n->nullable = ( $row->attnotnull == 'N' );
  54                 $n->name = $field;
  55                 $n->tablename = $table;
  56                 $n->max_length = $row->attlen;
  57                 return $n;
  58         }
  59         /**
  60          * Get column name
  61          * @return string column name
  62          */
  63         function name() { return $this->name; }
  64         /**
  65          * Get table name
  66          * @return string table name
  67          */
  68         function tableName() { return $this->tablename; }
  69         /**
  70          * Get column type
  71          * @return string column type
  72          */
  73         function type() { return $this->type; }
  74         /**
  75          * Can column be null?
  76          * @return bool true or false
  77          */
  78         function isNullable() { return $this->nullable; }
  79         /**
  80          * How much can you fit in the column per row?
  81          * @return int length
  82          */
  83         function maxLength() { return $this->max_length; }
  84 }
  85
  86 /**
  87  * Wrapper around binary large objects
  88  * @ingroup Database
  89  */
  90 class IBM_DB2Blob {
  91         private $mData;
  92
  93         public function __construct( $data ) {
  94                 $this->mData = $data;
  95         }
  96
  97         public function getData() {
  98                 return $this->mData;
  99         }
 100
 101         public function __toString() {
 102                 return $this->mData;
 103         }
 104 }
 105
 106 /**
 107  * Wrapper to address lack of certain operations in the DB2 driver
 108  *  ( seek, num_rows )
 109  * @ingroup Database
 110  * @since 1.19
 111  */
 112 class IBM_DB2Result{
 113         private $db;
 114         private $result;
 115         private $num_rows;
 116         private $current_pos;
 117         private $columns = array();
 118         private $sql;
 119
 120         private $resultSet = array();
 121         private $loadedLines = 0;
 122
 123         /**
 124          * Construct and initialize a wrapper for DB2 query results
 125          * @param $db DatabaseBase
 126          * @param $result Object
 127          * @param $num_rows Integer
 128          * @param $sql String
 129          * @param $columns Array
 130          */
 131         public function __construct( $db, $result, $num_rows, $sql, $columns ){
 132                 $this->db = $db;
 133
 134                 if( $result instanceof ResultWrapper ){
 135                         $this->result = $result->result;
 136                 }
 137                 else{
 138                         $this->result = $result;
 139                 }
 140
 141                 $this->num_rows = $num_rows;
 142                 $this->current_pos = 0;
 143                 if ( $this->num_rows > 0 ) {
 144                         // Make a lower-case list of the column names
 145                         // By default, DB2 column names are capitalized
 146                         //  while MySQL column names are lowercase
 147
 148                         // Is there a reasonable maximum value for $i?
 149                         // Setting to 2048 to prevent an infinite loop
 150                         for( $i = 0; $i < 2048; $i++ ) {
 151                                 $name = db2_field_name( $this->result, $i );
 152                                 if ( $name != false ) {
 153                                         continue;
 154                                 }
 155                                 else {
 156                                         return false;
 157                                 }
 158
 159                                 $this->columns[$i] = strtolower( $name );
 160                         }
 161                 }
 162
 163                 $this->sql = $sql;
 164         }
 165
 166         /**
 167          * Unwrap the DB2 query results
 168          * @return mixed Object on success, false on failure
 169          */
 170         public function getResult() {
 171                 if ( $this->result ) {
 172                         return $this->result;
 173                 }
 174                 else return false;
 175         }
 176
 177         /**
 178          * Get the number of rows in the result set
 179          * @return integer
 180          */
 181         public function getNum_rows() {
 182                 return $this->num_rows;
 183         }
 184
 185         /**
 186          * Return a row from the result set in object format
 187          * @return mixed Object on success, false on failure.
 188          */
 189         public function fetchObject() {
 190                 if ( $this->result
 191                                 && $this->num_rows > 0
 192                                 && $this->current_pos >= 0
 193                                 && $this->current_pos < $this->num_rows )
 194                 {
 195                         $row = $this->fetchRow();
 196                         $ret = new stdClass();
 197
 198                         foreach ( $row as $k => $v ) {
 199                                 $lc = $this->columns[$k];
 200                                 $ret->$lc = $v;
 201                         }
 202                         return $ret;
 203                 }
 204                 return false;
 205         }
 206
 207         /**
 208          * Return a row form the result set in array format
 209          * @return mixed Array on success, false on failure
 210          * @throws DBUnexpectedError
 211          */
 212         public function fetchRow(){
 213                 if ( $this->result
 214                                 && $this->num_rows > 0
 215                                 && $this->current_pos >= 0
 216                                 && $this->current_pos < $this->num_rows )
 217                 {
 218                         if ( $this->loadedLines <= $this->current_pos ) {
 219                                 $row = db2_fetch_array( $this->result );
 220                                 $this->resultSet[$this->loadedLines++] = $row;
 221                                 if ( $this->db->lastErrno() ) {
 222                                         throw new DBUnexpectedError( $this->db, 'Error in fetchRow(): '
 223                                                 . htmlspecialchars( $this->db->lastError() ) );
 224                                 }
 225                         }
 226
 227                         if ( $this->loadedLines > $this->current_pos ){
 228                                 return $this->resultSet[$this->current_pos++];
 229                         }
 230
 231                 }
 232                 return false;
 233         }
 234
 235         /**
 236          * Free a DB2 result object
 237          * @throws DBUnexpectedError
 238          */
 239         public function freeResult(){
 240                 unset( $this->resultSet );
 241                 if ( !@db2_free_result( $this->result ) ) {
 242                         throw new DBUnexpectedError( $this, "Unable to free DB2 result\n" );
 243                 }
 244         }
 245 }
 246
 247 /**
 248  * Primary database interface
 249  * @ingroup Database
 250  */
 251 class DatabaseIbm_db2 extends DatabaseBase {
 252         /*
 253          * Inherited members
 254         protected $mLastQuery = '';
 255         protected $mPHPError = false;
 256
 257         protected $mServer, $mUser, $mPassword, $mConn = null, $mDBname;
 258         protected $mOpened = false;
 259
 260         protected $mTablePrefix;
 261         protected $mFlags;
 262         protected $mTrxLevel = 0;
 263         protected $mErrorCount = 0;
 264         protected $mLBInfo = array();
 265         protected $mFakeSlaveLag = null, $mFakeMaster = false;
 266          *
 267          */
 268
 269         /** Database server port */
 270         protected $mPort = null;
 271         /** Schema for tables, stored procedures, triggers */
 272         protected $mSchema = null;
 273         /** Whether the schema has been applied in this session */
 274         protected $mSchemaSet = false;
 275         /** Result of last query */
 276         protected $mLastResult = null;
 277         /** Number of rows affected by last INSERT/UPDATE/DELETE */
 278         protected $mAffectedRows = null;
 279         /** Number of rows returned by last SELECT */
 280         protected $mNumRows = null;
 281         /** Current row number on the cursor of the last SELECT */
 282         protected $currentRow = 0;
 283
 284         /** Connection config options - see constructor */
 285         public $mConnOptions = array();
 286         /** Statement config options -- see constructor */
 287         public $mStmtOptions = array();
 288
 289         /** Default schema */
 290         const USE_GLOBAL = 'get from global';
 291
 292         /** Option that applies to nothing */
 293         const NONE_OPTION = 0x00;
 294         /** Option that applies to connection objects */
 295         const CONN_OPTION = 0x01;
 296         /** Option that applies to statement objects */
 297         const STMT_OPTION = 0x02;
 298
 299         /** Regular operation mode -- minimal debug messages */
 300         const REGULAR_MODE = 'regular';
 301         /** Installation mode -- lots of debug messages */
 302         const INSTALL_MODE = 'install';
 303
 304         /** Controls the level of debug message output */
 305         protected $mMode = self::REGULAR_MODE;
 306
 307         /** Last sequence value used for a primary key */
 308         protected $mInsertId = null;
 309
 310         ######################################
 311         # Getters and Setters
 312         ######################################
 313
 314         /**
 315          * Returns true if this database supports (and uses) cascading deletes
 316          * @return bool
 317          */
 318         function cascadingDeletes() {
 319                 return true;
 320         }
 321
 322         /**
 323          * Returns true if this database supports (and uses) triggers (e.g. on the
 324          *  page table)
 325          * @return bool
 326          */
 327         function cleanupTriggers() {
 328                 return true;
 329         }
 330
 331         /**
 332          * Returns true if this database is strict about what can be put into an
 333          *  IP field.
 334          * Specifically, it uses a NULL value instead of an empty string.
 335          * @return bool
 336          */
 337         function strictIPs() {
 338                 return true;
 339         }
 340
 341         /**
 342          * Returns true if this database uses timestamps rather than integers
 343          * @return bool
 344          */
 345         function realTimestamps() {
 346                 return true;
 347         }
 348
 349         /**
 350          * Returns true if this database does an implicit sort when doing GROUP BY
 351          * @return bool
 352          */
 353         function implicitGroupby() {
 354                 return false;
 355         }
 356
 357         /**
 358          * Returns true if this database does an implicit order by when the column
 359          *  has an index
 360          * For example: SELECT page_title FROM page LIMIT 1
 361          * @return bool
 362          */
 363         function implicitOrderby() {
 364                 return false;
 365         }
 366
 367         /**
 368          * Returns true if this database can do a native search on IP columns
 369          * e.g. this works as expected: .. WHERE rc_ip = '127.42.12.102/32';
 370          * @return bool
 371          */
 372         function searchableIPs() {
 373                 return true;
 374         }
 375
 376         /**
 377          * Returns true if this database can use functional indexes
 378          * @return bool
 379          */
 380         function functionalIndexes() {
 381                 return true;
 382         }
 383
 384         /**
 385          * Returns a unique string representing the wiki on the server
 386          * @return string
 387          */
 388         public function getWikiID() {
 389                 if( $this->mSchema ) {
 390                         return "{$this->mDBname}-{$this->mSchema}";
 391                 } else {
 392                         return $this->mDBname;
 393                 }
 394         }
 395
 396         /**
 397          * Returns the database software identifieir
 398          * @return string
 399          */
 400         public function getType() {
 401                 return 'ibm_db2';
 402         }
 403
 404         /**
 405          * Returns the database connection object
 406          * @return Object
 407          */
 408         public function getDb(){
 409                 return $this->mConn;
 410         }
 411
 412         /**
 413          *
 414          * @param $server String: hostname of database server
 415          * @param $user String: username
 416          * @param $password String: password
 417          * @param $dbName String: database name on the server
 418          * @param $flags Integer: database behaviour flags (optional, unused)
 419          * @param $schema String
 420          */
 421         public function __construct( $server = false, $user = false,
 422                                                         $password = false,
 423                                                         $dbName = false, $flags = 0,
 424                                                         $schema = self::USE_GLOBAL )
 425         {
 426                 global $wgDBmwschema;
 427
 428                 if ( $schema == self::USE_GLOBAL ) {
 429                         $this->mSchema = $wgDBmwschema;
 430                 } else {
 431                         $this->mSchema = $schema;
 432                 }
 433
 434                 // configure the connection and statement objects
 435                 $this->setDB2Option( 'db2_attr_case', 'DB2_CASE_LOWER',
 436                         self::CONN_OPTION | self::STMT_OPTION );
 437                 $this->setDB2Option( 'deferred_prepare', 'DB2_DEFERRED_PREPARE_ON',
 438                         self::STMT_OPTION );
 439                 $this->setDB2Option( 'rowcount', 'DB2_ROWCOUNT_PREFETCH_ON',
 440                         self::STMT_OPTION );
 441                 parent::__construct( $server, $user, $password, $dbName, DBO_TRX | $flags );
 442         }
 443
 444         /**
 445          * Enables options only if the ibm_db2 extension version supports them
 446          * @param $name String: name of the option in the options array
 447          * @param $const String: name of the constant holding the right option value
 448          * @param $type Integer: whether this is a Connection or Statement otion
 449          */
 450         private function setDB2Option( $name, $const, $type ) {
 451                 if ( defined( $const ) ) {
 452                         if ( $type & self::CONN_OPTION ) {
 453                                 $this->mConnOptions[$name] = constant( $const );
 454                         }
 455                         if ( $type & self::STMT_OPTION ) {
 456                                 $this->mStmtOptions[$name] = constant( $const );
 457                         }
 458                 } else {
 459                         $this->installPrint(
 460                                 "$const is not defined. ibm_db2 version is likely too low." );
 461                 }
 462         }
 463
 464         /**
 465          * Outputs debug information in the appropriate place
 466          * @param $string String: the relevant debug message
 467          */
 468         private function installPrint( $string ) {
 469                 wfDebug( "$string\n" );
 470                 if ( $this->mMode == self::INSTALL_MODE ) {
 471                         print "<li><pre>$string</pre></li>";
 472                         flush();
 473                 }
 474         }
 475
 476         /**
 477          * Opens a database connection and returns it
 478          * Closes any existing connection
 479          *
 480          * @param $server String: hostname
 481          * @param $user String
 482          * @param $password String
 483          * @param $dbName String: database name
 484          * @return DatabaseBase a fresh connection
 485          */
 486         public function open( $server, $user, $password, $dbName ) {
 487                 wfProfileIn( __METHOD__ );
 488
 489                 # Load IBM DB2 driver if missing
 490                 wfDl( 'ibm_db2' );
 491
 492                 # Test for IBM DB2 support, to avoid suppressed fatal error
 493                 if ( !function_exists( 'db2_connect' ) ) {
 494                         throw new DBConnectionError( $this, "DB2 functions missing, have you enabled the ibm_db2 extension for PHP?" );
 495                 }
 496
 497                 global $wgDBport;
 498
 499                 // Close existing connection
 500                 $this->close();
 501                 // Cache conn info
 502                 $this->mServer = $server;
 503                 $this->mPort = $port = $wgDBport;
 504                 $this->mUser = $user;
 505                 $this->mPassword = $password;
 506                 $this->mDBname = $dbName;
 507
 508                 $this->openUncataloged( $dbName, $user, $password, $server, $port );
 509
 510                 if ( !$this->mConn ) {
 511                         $this->installPrint( "DB connection error\n" );
 512                         $this->installPrint(
 513                                 "Server: $server, Database: $dbName, User: $user, Password: "
 514                                 . substr( $password, 0, 3 ) . "...\n" );
 515                         $this->installPrint( $this->lastError() . "\n" );
 516                         wfProfileOut( __METHOD__ );
 517                         wfDebug( "DB connection error\n" );
 518                         wfDebug( "Server: $server, Database: $dbName, User: $user, Password: " . substr( $password, 0, 3 ) . "...\n" );
 519                         wfDebug( $this->lastError() . "\n" );
 520                         throw new DBConnectionError( $this, $this->lastError() );
 521                 }
 522
 523                 // Some MediaWiki code is still transaction-less (?).
 524                 // The strategy is to keep AutoCommit on for that code
 525                 //  but switch it off whenever a transaction is begun.
 526                 db2_autocommit( $this->mConn, DB2_AUTOCOMMIT_ON );
 527
 528                 $this->mOpened = true;
 529                 $this->applySchema();
 530
 531                 wfProfileOut( __METHOD__ );
 532                 return $this->mConn;
 533         }
 534
 535         /**
 536          * Opens a cataloged database connection, sets mConn
 537          */
 538         protected function openCataloged( $dbName, $user, $password ) {
 539                 wfSuppressWarnings();
 540                 $this->mConn = db2_pconnect( $dbName, $user, $password );
 541                 wfRestoreWarnings();
 542         }
 543
 544         /**
 545          * Opens an uncataloged database connection, sets mConn
 546          */
 547         protected function openUncataloged( $dbName, $user, $password, $server, $port )
 548         {
 549                 $dsn = "DRIVER={IBM DB2 ODBC DRIVER};DATABASE=$dbName;CHARSET=UTF-8;HOSTNAME=$server;PORT=$port;PROTOCOL=TCPIP;UID=$user;PWD=$password;";
 550                 wfSuppressWarnings();
 551                 $this->mConn = db2_pconnect( $dsn, "", "", array() );
 552                 wfRestoreWarnings();
 553         }
 554
 555         /**
 556          * Closes a database connection, if it is open
 557          * Returns success, true if already closed
 558          * @return bool
 559          */
 560         public function close() {
 561                 $this->mOpened = false;
 562                 if ( $this->mConn ) {
 563                         if ( $this->trxLevel() > 0 ) {
 564                                 $this->commit();
 565                         }
 566                         return db2_close( $this->mConn );
 567                 } else {
 568                         return true;
 569                 }
 570         }
 571
 572         /**
 573          * Retrieves the most current database error
 574          * Forces a database rollback
 575          * @return bool|string
 576          */
 577         public function lastError() {
 578                 $connerr = db2_conn_errormsg();
 579                 if ( $connerr ) {
 580                         //$this->rollback();
 581                         return $connerr;
 582                 }
 583                 $stmterr = db2_stmt_errormsg();
 584                 if ( $stmterr ) {
 585                         //$this->rollback();
 586                         return $stmterr;
 587                 }
 588
 589                 return false;
 590         }
 591
 592         /**
 593          * Get the last error number
 594          * Return 0 if no error
 595          * @return integer
 596          */
 597         public function lastErrno() {
 598                 $connerr = db2_conn_error();
 599                 if ( $connerr ) {
 600                         return $connerr;
 601                 }
 602                 $stmterr = db2_stmt_error();
 603                 if ( $stmterr ) {
 604                         return $stmterr;
 605                 }
 606                 return 0;
 607         }
 608
 609         /**
 610          * Is a database connection open?
 611          * @return
 612          */
 613         public function isOpen() { return $this->mOpened; }
 614
 615         /**
 616          * The DBMS-dependent part of query()
 617          * @param  $sql String: SQL query.
 618          * @return object Result object for fetch functions or false on failure
 619          */
 620         protected function doQuery( $sql ) {
 621                 $this->applySchema();
 622
 623                 // Needed to handle any UTF-8 encoding issues in the raw sql
 624                 // Note that we fully support prepared statements for DB2
 625                 // prepare() and execute() should be used instead of doQuery() whenever possible
 626                 $sql = utf8_decode( $sql );
 627
 628                 $ret = db2_exec( $this->mConn, $sql, $this->mStmtOptions );
 629                 if( $ret == false ) {
 630                         $error = db2_stmt_errormsg();
 631
 632                         $this->installPrint( "<pre>$sql</pre>" );
 633                         $this->installPrint( $error );
 634                         throw new DBUnexpectedError( $this, 'SQL error: '
 635                                 . htmlspecialchars( $error ) );
 636                 }
 637                 $this->mLastResult = $ret;
 638                 $this->mAffectedRows = null; // Not calculated until asked for
 639                 return $ret;
 640         }
 641
 642         /**
 643          * @return string Version information from the database
 644          */
 645         public function getServerVersion() {
 646                 $info = db2_server_info( $this->mConn );
 647                 return $info->DBMS_VER;
 648         }
 649
 650         /**
 651          * Queries whether a given table exists
 652          * @return boolean
 653          */
 654         public function tableExists( $table, $fname = __METHOD__ ) {
 655                 $schema = $this->mSchema;
 656
 657                 $sql = "SELECT COUNT( * ) FROM SYSIBM.SYSTABLES ST WHERE ST.NAME = '" .
 658                         strtoupper( $table ) .
 659                         "' AND ST.CREATOR = '" .
 660                         strtoupper( $schema ) . "'";
 661                 $res = $this->query( $sql );
 662                 if ( !$res ) {
 663                         return false;
 664                 }
 665
 666                 // If the table exists, there should be one of it
 667                 $row = $this->fetchRow( $res );
 668                 $count = $row[0];
 669                 if ( $count == '1' || $count == 1 ) {
 670                         return true;
 671                 }
 672
 673                 return false;
 674         }
 675
 676         /**
 677          * Fetch the next row from the given result object, in object form.
 678          * Fields can be retrieved with $row->fieldname, with fields acting like
 679          * member variables.
 680          *
 681          * @param $res array|ResultWrapper SQL result object as returned from Database::query(), etc.
 682          * @return DB2 row object
 683          * @throws DBUnexpectedError Thrown if the database returns an error
 684          */
 685         public function fetchObject( $res ) {
 686                 if ( $res instanceof ResultWrapper ) {
 687                         $res = $res->result;
 688                 }
 689                 wfSuppressWarnings();
 690                 $row = db2_fetch_object( $res );
 691                 wfRestoreWarnings();
 692                 if( $this->lastErrno() ) {
 693                         throw new DBUnexpectedError( $this, 'Error in fetchObject(): '
 694                                 . htmlspecialchars( $this->lastError() ) );
 695                 }
 696                 return $row;
 697         }
 698
 699         /**
 700          * Fetch the next row from the given result object, in associative array
 701          * form. Fields are retrieved with $row['fieldname'].
 702          *
 703          * @param $res array|ResultWrapper SQL result object as returned from Database::query(), etc.
 704          * @return ResultWrapper row object
 705          * @throws DBUnexpectedError Thrown if the database returns an error
 706          */
 707         public function fetchRow( $res ) {
 708                 if ( $res instanceof ResultWrapper ) {
 709                         $res = $res->result;
 710                 }
 711                 if ( db2_num_rows( $res ) > 0) {
 712                         wfSuppressWarnings();
 713                         $row = db2_fetch_array( $res );
 714                         wfRestoreWarnings();
 715                         if ( $this->lastErrno() ) {
 716                                 throw new DBUnexpectedError( $this, 'Error in fetchRow(): '
 717                                         . htmlspecialchars( $this->lastError() ) );
 718                         }
 719                         return $row;
 720                 }
 721                 return false;
 722         }
 723
 724         /**
 725          * Escapes strings
 726          * Doesn't escape numbers
 727          *
 728          * @param $s String: string to escape
 729          * @return string escaped string
 730          */
 731         public function addQuotes( $s ) {
 732                 //$this->installPrint( "DB2::addQuotes( $s )\n" );
 733                 if ( is_null( $s ) ) {
 734                         return 'NULL';
 735                 } elseif ( $s instanceof Blob ) {
 736                         return "'" . $s->fetch( $s ) . "'";
 737                 } elseif ( $s instanceof IBM_DB2Blob ) {
 738                         return "'" . $this->decodeBlob( $s ) . "'";
 739                 }
 740                 $s = $this->strencode( $s );
 741                 if ( is_numeric( $s ) ) {
 742                         return $s;
 743                 } else {
 744                         return "'$s'";
 745                 }
 746         }
 747
 748         /**
 749          * Verifies that a DB2 column/field type is numeric
 750          *
 751          * @param $type String: DB2 column type
 752          * @return Boolean: true if numeric
 753          */
 754         public function is_numeric_type( $type ) {
 755                 switch ( strtoupper( $type ) ) {
 756                         case 'SMALLINT':
 757                         case 'INTEGER':
 758                         case 'INT':
 759                         case 'BIGINT':
 760                         case 'DECIMAL':
 761                         case 'REAL':
 762                         case 'DOUBLE':
 763                         case 'DECFLOAT':
 764                                 return true;
 765                 }
 766                 return false;
 767         }
 768
 769         /**
 770          * Alias for addQuotes()
 771          * @param $s String: string to escape
 772          * @return string escaped string
 773          */
 774         public function strencode( $s ) {
 775                 // Bloody useless function
 776                 //  Prepends backslashes to \x00, \n, \r, \, ', " and \x1a.
 777                 //  But also necessary
 778                 $s = db2_escape_string( $s );
 779                 // Wide characters are evil -- some of them look like '
 780                 $s = utf8_encode( $s );
 781                 // Fix its stupidity
 782                 $from = array(  "\\\\", "\\'",  '\\n',  '\\t',  '\\"',  '\\r' );
 783                 $to = array(            "\\",           "''",           "\n",           "\t",           '"',            "\r" );
 784                 $s = str_replace( $from, $to, $s ); // DB2 expects '', not \' escaping
 785                 return $s;
 786         }
 787
 788         /**
 789          * Switch into the database schema
 790          */
 791         protected function applySchema() {
 792                 if ( !( $this->mSchemaSet ) ) {
 793                         $this->mSchemaSet = true;
 794                         $this->begin();
 795                         $this->doQuery( "SET SCHEMA = $this->mSchema" );
 796                         $this->commit();
 797                 }
 798         }
 799
 800         /**
 801          * Start a transaction (mandatory)
 802          */
 803         public function begin( $fname = 'DatabaseIbm_db2::begin' ) {
 804                 // BEGIN is implicit for DB2
 805                 // However, it requires that AutoCommit be off.
 806
 807                 // Some MediaWiki code is still transaction-less (?).
 808                 // The strategy is to keep AutoCommit on for that code
 809                 //  but switch it off whenever a transaction is begun.
 810                 db2_autocommit( $this->mConn, DB2_AUTOCOMMIT_OFF );
 811
 812                 $this->mTrxLevel = 1;
 813         }
 814
 815         /**
 816          * End a transaction
 817          * Must have a preceding begin()
 818          */
 819         public function commit( $fname = 'DatabaseIbm_db2::commit' ) {
 820                 db2_commit( $this->mConn );
 821
 822                 // Some MediaWiki code is still transaction-less (?).
 823                 // The strategy is to keep AutoCommit on for that code
 824                 //  but switch it off whenever a transaction is begun.
 825                 db2_autocommit( $this->mConn, DB2_AUTOCOMMIT_ON );
 826
 827                 $this->mTrxLevel = 0;
 828         }
 829
 830         /**
 831          * Cancel a transaction
 832          */
 833         public function rollback( $fname = 'DatabaseIbm_db2::rollback' ) {
 834                 db2_rollback( $this->mConn );
 835                 // turn auto-commit back on
 836                 // not sure if this is appropriate
 837                 db2_autocommit( $this->mConn, DB2_AUTOCOMMIT_ON );
 838                 $this->mTrxLevel = 0;
 839         }
 840
 841         /**
 842          * Makes an encoded list of strings from an array
 843          * $mode:
 844          *   LIST_COMMA         - comma separated, no field names
 845          *   LIST_AND           - ANDed WHERE clause (without the WHERE)
 846          *   LIST_OR            - ORed WHERE clause (without the WHERE)
 847          *   LIST_SET           - comma separated with field names, like a SET clause
 848          *   LIST_NAMES         - comma separated field names
 849          *   LIST_SET_PREPARED  - like LIST_SET, except with ? tokens as values
 850          * @return string
 851          */
 852         function makeList( $a, $mode = LIST_COMMA ) {
 853                 if ( !is_array( $a ) ) {
 854                         throw new DBUnexpectedError( $this,
 855                                 'DatabaseIbm_db2::makeList called with incorrect parameters' );
 856                 }
 857
 858                 // if this is for a prepared UPDATE statement
 859                 // (this should be promoted to the parent class
 860                 //  once other databases use prepared statements)
 861                 if ( $mode == LIST_SET_PREPARED ) {
 862                         $first = true;
 863                         $list = '';
 864                         foreach ( $a as $field => $value ) {
 865                                 if ( !$first ) {
 866                                         $list .= ", $field = ?";
 867                                 } else {
 868                                         $list .= "$field = ?";
 869                                         $first = false;
 870                                 }
 871                         }
 872                         $list .= '';
 873
 874                         return $list;
 875                 }
 876
 877                 // otherwise, call the usual function
 878                 return parent::makeList( $a, $mode );
 879         }
 880
 881         /**
 882          * Construct a LIMIT query with optional offset
 883          * This is used for query pages
 884          *
 885          * @param $sql string SQL query we will append the limit too
 886          * @param $limit integer the SQL limit
 887          * @param $offset integer the SQL offset (default false)
 888          * @return string
 889          */
 890         public function limitResult( $sql, $limit, $offset=false ) {
 891                 if( !is_numeric( $limit ) ) {
 892                         throw new DBUnexpectedError( $this,
 893                                 "Invalid non-numeric limit passed to limitResult()\n" );
 894                 }
 895                 if( $offset ) {
 896                         if ( stripos( $sql, 'where' ) === false ) {
 897                                 return "$sql AND ( ROWNUM BETWEEN $offset AND $offset+$limit )";
 898                         } else {
 899                                 return "$sql WHERE ( ROWNUM BETWEEN $offset AND $offset+$limit )";
 900                         }
 901                 }
 902                 return "$sql FETCH FIRST $limit ROWS ONLY ";
 903         }
 904
 905         /**
 906          * Handle reserved keyword replacement in table names
 907          *
 908          * @param $name Object
 909          * @param $format String Ignored parameter Default 'quoted'Boolean
 910          * @return String
 911          */
 912         public function tableName( $name, $format = 'quoted' ) {
 913                 // we want maximum compatibility with MySQL schema
 914                 return $name;
 915         }
 916
 917         /**
 918          * Generates a timestamp in an insertable format
 919          *
 920          * @param $ts string timestamp
 921          * @return String: timestamp value
 922          */
 923         public function timestamp( $ts = 0 ) {
 924                 // TS_MW cannot be easily distinguished from an integer
 925                 return wfTimestamp( TS_DB2, $ts );
 926         }
 927
 928         /**
 929          * Return the next in a sequence, save the value for retrieval via insertId()
 930          * @param $seqName String: name of a defined sequence in the database
 931          * @return int next value in that sequence
 932          */
 933         public function nextSequenceValue( $seqName ) {
 934                 // Not using sequences in the primary schema to allow for easier migration
 935                 //  from MySQL
 936                 // Emulating MySQL behaviour of using NULL to signal that sequences
 937                 // aren't used
 938                 /*
 939                 $safeseq = preg_replace( "/'/", "''", $seqName );
 940                 $res = $this->query( "VALUES NEXTVAL FOR $safeseq" );
 941                 $row = $this->fetchRow( $res );
 942                 $this->mInsertId = $row[0];
 943                 return $this->mInsertId;
 944                 */
 945                 return null;
 946         }
 947
 948         /**
 949          * This must be called after nextSequenceVal
 950          * @return int Last sequence value used as a primary key
 951          */
 952         public function insertId() {
 953                 return $this->mInsertId;
 954         }
 955
 956         /**
 957          * Updates the mInsertId property with the value of the last insert
 958          *  into a generated column
 959          *
 960          * @param $table      String: sanitized table name
 961          * @param $primaryKey Mixed: string name of the primary key
 962          * @param $stmt       Resource: prepared statement resource
 963          *  of the SELECT primary_key FROM FINAL TABLE ( INSERT ... ) form
 964          */
 965         private function calcInsertId( $table, $primaryKey, $stmt ) {
 966                 if ( $primaryKey ) {
 967                         $this->mInsertId = db2_last_insert_id( $this->mConn );
 968                 }
 969         }
 970
 971         /**
 972          * INSERT wrapper, inserts an array into a table
 973          *
 974          * $args may be a single associative array, or an array of arrays
 975          *  with numeric keys, for multi-row insert
 976          *
 977          * @param $table   String: Name of the table to insert to.
 978          * @param $args    Array: Items to insert into the table.
 979          * @param $fname   String: Name of the function, for profiling
 980          * @param $options String or Array. Valid options: IGNORE
 981          *
 982          * @return bool Success of insert operation. IGNORE always returns true.
 983          */
 984         public function insert( $table, $args, $fname = 'DatabaseIbm_db2::insert',
 985                 $options = array() )
 986         {
 987                 if ( !count( $args ) ) {
 988                         return true;
 989                 }
 990                 // get database-specific table name (not used)
 991                 $table = $this->tableName( $table );
 992                 // format options as an array
 993                 $options = IBM_DB2Helper::makeArray( $options );
 994                 // format args as an array of arrays
 995                 if ( !( isset( $args[0] ) && is_array( $args[0] ) ) ) {
 996                         $args = array( $args );
 997                 }
 998
 999                 // prevent insertion of NULL into primary key columns
1000                 list( $args, $primaryKeys ) = $this->removeNullPrimaryKeys( $table, $args );
1001                 // if there's only one primary key
1002                 // we'll be able to read its value after insertion
1003                 $primaryKey = false;
1004                 if ( count( $primaryKeys ) == 1 ) {
1005                         $primaryKey = $primaryKeys[0];
1006                 }
1007
1008                 // get column names
1009                 $keys = array_keys( $args[0] );
1010                 $key_count = count( $keys );
1011
1012                 // If IGNORE is set, we use savepoints to emulate mysql's behavior
1013                 $ignore = in_array( 'IGNORE', $options ) ? 'mw' : '';
1014
1015                 // assume success
1016                 $res = true;
1017                 // If we are not in a transaction, we need to be for savepoint trickery
1018                 if ( !$this->mTrxLevel ) {
1019                         $this->begin();
1020                 }
1021
1022                 $sql = "INSERT INTO $table ( " . implode( ',', $keys ) . ' ) VALUES ';
1023                 if ( $key_count == 1 ) {
1024                         $sql .= '( ? )';
1025                 } else {
1026                         $sql .= '( ?' . str_repeat( ',?', $key_count-1 ) . ' )';
1027                 }
1028                 $this->installPrint( "Preparing the following SQL:" );
1029                 $this->installPrint( "$sql" );
1030                 $this->installPrint( print_r( $args, true ));
1031                 $stmt = $this->prepare( $sql );
1032
1033                 // start a transaction/enter transaction mode
1034                 $this->begin();
1035
1036                 if ( !$ignore ) {
1037                         //$first = true;
1038                         foreach ( $args as $row ) {
1039                                 //$this->installPrint( "Inserting " . print_r( $row, true ));
1040                                 // insert each row into the database
1041                                 $res = $res & $this->execute( $stmt, $row );
1042                                 if ( !$res ) {
1043                                         $this->installPrint( 'Last error:' );
1044                                         $this->installPrint( $this->lastError() );
1045                                 }
1046                                 // get the last inserted value into a generated column
1047                                 $this->calcInsertId( $table, $primaryKey, $stmt );
1048                         }
1049                 } else {
1050                         $olde = error_reporting( 0 );
1051                         // For future use, we may want to track the number of actual inserts
1052                         // Right now, insert (all writes) simply return true/false
1053                         $numrowsinserted = 0;
1054
1055                         // always return true
1056                         $res = true;
1057
1058                         foreach ( $args as $row ) {
1059                                 $overhead = "SAVEPOINT $ignore ON ROLLBACK RETAIN CURSORS";
1060                                 db2_exec( $this->mConn, $overhead, $this->mStmtOptions );
1061
1062                                 $res2 = $this->execute( $stmt, $row );
1063
1064                                 if ( !$res2 ) {
1065                                         $this->installPrint( 'Last error:' );
1066                                         $this->installPrint( $this->lastError() );
1067                                 }
1068                                 // get the last inserted value into a generated column
1069                                 $this->calcInsertId( $table, $primaryKey, $stmt );
1070
1071                                 $errNum = $this->lastErrno();
1072                                 if ( $errNum ) {
1073                                         db2_exec( $this->mConn, "ROLLBACK TO SAVEPOINT $ignore",
1074                                                 $this->mStmtOptions );
1075                                 } else {
1076                                         db2_exec( $this->mConn, "RELEASE SAVEPOINT $ignore",
1077                                                 $this->mStmtOptions );
1078                                         $numrowsinserted++;
1079                                 }
1080                         }
1081
1082                         $olde = error_reporting( $olde );
1083                         // Set the affected row count for the whole operation
1084                         $this->mAffectedRows = $numrowsinserted;
1085                 }
1086                 // commit either way
1087                 $this->commit();
1088                 $this->freePrepared( $stmt );
1089
1090                 return $res;
1091         }
1092
1093         /**
1094          * Given a table name and a hash of columns with values
1095          * Removes primary key columns from the hash where the value is NULL
1096          *
1097          * @param $table String: name of the table
1098          * @param $args Array of hashes of column names with values
1099          * @return Array: tuple( filtered array of columns, array of primary keys )
1100          */
1101         private function removeNullPrimaryKeys( $table, $args ) {
1102                 $schema = $this->mSchema;
1103
1104                 // find out the primary keys
1105                 $keyres = $this->doQuery( "SELECT NAME FROM SYSIBM.SYSCOLUMNS WHERE TBNAME = '"
1106                   . strtoupper( $table )
1107                   . "' AND TBCREATOR = '"
1108                   . strtoupper( $schema )
1109                   . "' AND KEYSEQ > 0" );
1110
1111                 $keys = array();
1112                 for (
1113                         $row = $this->fetchRow( $keyres );
1114                         $row != null;
1115                         $row = $this->fetchRow( $keyres )
1116                 )
1117                 {
1118                         $keys[] = strtolower( $row[0] );
1119                 }
1120                 // remove primary keys
1121                 foreach ( $args as $ai => $row ) {
1122                         foreach ( $keys as $key ) {
1123                                 if ( $row[$key] == null ) {
1124                                         unset( $row[$key] );
1125                                 }
1126                         }
1127                         $args[$ai] = $row;
1128                 }
1129                 // return modified hash
1130                 return array( $args, $keys );
1131         }
1132
1133         /**
1134          * UPDATE wrapper, takes a condition array and a SET array
1135          *
1136          * @param $table  String: The table to UPDATE
1137          * @param $values array An array of values to SET
1138          * @param $conds  array An array of conditions ( WHERE ). Use '*' to update all rows.
1139          * @param $fname  String: The Class::Function calling this function
1140          *                ( for the log )
1141          * @param $options array An array of UPDATE options, can be one or
1142          *                 more of IGNORE, LOW_PRIORITY
1143          * @return Boolean
1144          */
1145         public function update( $table, $values, $conds, $fname = 'DatabaseIbm_db2::update',
1146                 $options = array() )
1147         {
1148                 $table = $this->tableName( $table );
1149                 $opts = $this->makeUpdateOptions( $options );
1150                 $sql = "UPDATE $opts $table SET "
1151                         . $this->makeList( $values, LIST_SET_PREPARED );
1152                 if ( $conds != '*' ) {
1153                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1154                 }
1155                 $stmt = $this->prepare( $sql );
1156                 $this->installPrint( 'UPDATE: ' . print_r( $values, true ) );
1157                 // assuming for now that an array with string keys will work
1158                 // if not, convert to simple array first
1159                 $result = $this->execute( $stmt, $values );
1160                 $this->freePrepared( $stmt );
1161
1162                 return $result;
1163         }
1164
1165         /**
1166          * DELETE query wrapper
1167          *
1168          * Use $conds == "*" to delete all rows
1169          * @return bool|\ResultWrapper
1170          */
1171         public function delete( $table, $conds, $fname = 'DatabaseIbm_db2::delete' ) {
1172                 if ( !$conds ) {
1173                         throw new DBUnexpectedError( $this,
1174                                 'DatabaseIbm_db2::delete() called with no conditions' );
1175                 }
1176                 $table = $this->tableName( $table );
1177                 $sql = "DELETE FROM $table";
1178                 if ( $conds != '*' ) {
1179                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1180                 }
1181                 $result = $this->query( $sql, $fname );
1182
1183                 return $result;
1184         }
1185
1186         /**
1187          * Returns the number of rows affected by the last query or 0
1188          * @return Integer: the number of rows affected by the last query
1189          */
1190         public function affectedRows() {
1191                 if ( !is_null( $this->mAffectedRows ) ) {
1192                         // Forced result for simulated queries
1193                         return $this->mAffectedRows;
1194                 }
1195                 if( empty( $this->mLastResult ) ) {
1196                         return 0;
1197                 }
1198                 return db2_num_rows( $this->mLastResult );
1199         }
1200
1201         /**
1202          * Returns the number of rows in the result set
1203          * Has to be called right after the corresponding select query
1204          * @param $res Object result set
1205          * @return Integer: number of rows
1206          */
1207         public function numRows( $res ) {
1208                 if ( $res instanceof ResultWrapper ) {
1209                         $res = $res->result;
1210                 }
1211
1212                 if ( $this->mNumRows ) {
1213                         return $this->mNumRows;
1214                 } else {
1215                         return 0;
1216                 }
1217         }
1218
1219         /**
1220          * Moves the row pointer of the result set
1221          * @param $res Object: result set
1222          * @param $row Integer: row number
1223          * @return bool success or failure
1224          */
1225         public function dataSeek( $res, $row ) {
1226                 if ( $res instanceof ResultWrapper ) {
1227                         return $res = $res->result;
1228                 }
1229                 if ( $res instanceof IBM_DB2Result ) {
1230                         return $res->dataSeek( $row );
1231                 }
1232                 wfDebug( "dataSeek operation in DB2 database\n" );
1233                 return false;
1234         }
1235
1236         ###
1237         # Fix notices in Block.php
1238         ###
1239
1240         /**
1241          * Frees memory associated with a statement resource
1242          * @param $res Object: statement resource to free
1243          * @return Boolean success or failure
1244          */
1245         public function freeResult( $res ) {
1246                 if ( $res instanceof ResultWrapper ) {
1247                         $res = $res->result;
1248                 }
1249                 wfSuppressWarnings();
1250                 $ok = db2_free_result( $res );
1251                 wfRestoreWarnings();
1252                 if ( !$ok ) {
1253                         throw new DBUnexpectedError( $this, "Unable to free DB2 result\n" );
1254                 }
1255         }
1256
1257         /**
1258          * Returns the number of columns in a resource
1259          * @param $res Object: statement resource
1260          * @return Number of fields/columns in resource
1261          */
1262         public function numFields( $res ) {
1263                 if ( $res instanceof ResultWrapper ) {
1264                         $res = $res->result;
1265                 }
1266                 if ( $res instanceof IBM_DB2Result ) {
1267                         $res = $res->getResult();
1268                 }
1269                 return db2_num_fields( $res );
1270         }
1271
1272         /**
1273          * Returns the nth column name
1274          * @param $res Object: statement resource
1275          * @param $n Integer: Index of field or column
1276          * @return String name of nth column
1277          */
1278         public function fieldName( $res, $n ) {
1279                 if ( $res instanceof ResultWrapper ) {
1280                         $res = $res->result;
1281                 }
1282                 if ( $res instanceof IBM_DB2Result ) {
1283                         $res = $res->getResult();
1284                 }
1285                 return db2_field_name( $res, $n );
1286         }
1287
1288         /**
1289          * SELECT wrapper
1290          *
1291          * @param $table   Array or string, table name(s) (prefix auto-added)
1292          * @param $vars    Array or string, field name(s) to be retrieved
1293          * @param $conds   Array or string, condition(s) for WHERE
1294          * @param $fname   String: calling function name (use __METHOD__)
1295          *                 for logs/profiling
1296          * @param $options array Associative array of options
1297          *                 (e.g. array( 'GROUP BY' => 'page_title' )),
1298          *                 see Database::makeSelectOptions code for list of
1299          *                 supported stuff
1300          * @param $join_conds array Associative array of table join conditions (optional)
1301          *                    (e.g. array( 'page' => array('LEFT JOIN',
1302          *                    'page_latest=rev_id') )
1303          * @return Mixed: database result resource for fetch functions or false
1304          *                 on failure
1305          */
1306         public function select( $table, $vars, $conds = '', $fname = 'DatabaseIbm_db2::select', $options = array(), $join_conds = array() )
1307         {
1308                 $res = parent::select( $table, $vars, $conds, $fname, $options,
1309                         $join_conds );
1310                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1311
1312                 // We must adjust for offset
1313                 if ( isset( $options['LIMIT'] ) && isset ( $options['OFFSET'] ) ) {
1314                         $limit = $options['LIMIT'];
1315                         $offset = $options['OFFSET'];
1316                 }
1317
1318                 // DB2 does not have a proper num_rows() function yet, so we must emulate
1319                 // DB2 9.5.4 and the corresponding ibm_db2 driver will introduce
1320                 //  a working one
1321                 // TODO: Yay!
1322
1323                 // we want the count
1324                 $vars2 = array( 'count( * ) as num_rows' );
1325                 // respecting just the limit option
1326                 $options2 = array();
1327                 if ( isset( $options['LIMIT'] ) ) {
1328                         $options2['LIMIT'] = $options['LIMIT'];
1329                 }
1330                 // but don't try to emulate for GROUP BY
1331                 if ( isset( $options['GROUP BY'] ) ) {
1332                         return $res;
1333                 }
1334
1335                 $res2 = parent::select( $table, $vars2, $conds, $fname, $options2,
1336                         $join_conds );
1337
1338                 $obj = $this->fetchObject( $res2 );
1339                 $this->mNumRows = $obj->num_rows;
1340
1341                 return new ResultWrapper( $this, new IBM_DB2Result( $this, $res, $obj->num_rows, $vars, $sql ) );
1342         }
1343
1344         /**
1345          * Handles ordering, grouping, and having options ('GROUP BY' => colname)
1346          * Has limited support for per-column options (colnum => 'DISTINCT')
1347          *
1348          * @private
1349          *
1350          * @param $options array Associative array of options to be turned into
1351          *              an SQL query, valid keys are listed in the function.
1352          * @return Array
1353          */
1354         function makeSelectOptions( $options ) {
1355                 $preLimitTail = $postLimitTail = '';
1356                 $startOpts = '';
1357
1358                 $noKeyOptions = array();
1359                 foreach ( $options as $key => $option ) {
1360                         if ( is_numeric( $key ) ) {
1361                                 $noKeyOptions[$option] = true;
1362                         }
1363                 }
1364
1365                 if ( isset( $options['GROUP BY'] ) ) {
1366                         $preLimitTail .= " GROUP BY {$options['GROUP BY']}";
1367                 }
1368                 if ( isset( $options['HAVING'] ) ) {
1369                         $preLimitTail .= " HAVING {$options['HAVING']}";
1370                 }
1371                 if ( isset( $options['ORDER BY'] ) ) {
1372                         $preLimitTail .= " ORDER BY {$options['ORDER BY']}";
1373                 }
1374
1375                 if ( isset( $noKeyOptions['DISTINCT'] )
1376                         || isset( $noKeyOptions['DISTINCTROW'] ) )
1377                 {
1378                         $startOpts .= 'DISTINCT';
1379                 }
1380
1381                 return array( $startOpts, '', $preLimitTail, $postLimitTail );
1382         }
1383
1384         /**
1385          * Returns link to IBM DB2 free download
1386          * @return String: wikitext of a link to the server software's web site
1387          */
1388         public static function getSoftwareLink() {
1389                 return '[http://www.ibm.com/db2/express/ IBM DB2]';
1390         }
1391
1392         /**
1393          * Get search engine class. All subclasses of this
1394          * need to implement this if they wish to use searching.
1395          *
1396          * @return String
1397          */
1398         public function getSearchEngine() {
1399                 return 'SearchIBM_DB2';
1400         }
1401
1402         /**
1403          * Did the last database access fail because of deadlock?
1404          * @return Boolean
1405          */
1406         public function wasDeadlock() {
1407                 // get SQLSTATE
1408                 $err = $this->lastErrno();
1409                 switch( $err ) {
1410                         // This is literal port of the MySQL logic and may be wrong for DB2
1411                         case '40001':   // sql0911n, Deadlock or timeout, rollback
1412                         case '57011':   // sql0904n, Resource unavailable, no rollback
1413                         case '57033':   // sql0913n, Deadlock or timeout, no rollback
1414                         $this->installPrint( "In a deadlock because of SQLSTATE $err" );
1415                         return true;
1416                 }
1417                 return false;
1418         }
1419
1420         /**
1421          * Ping the server and try to reconnect if it there is no connection
1422          * The connection may be closed and reopened while this happens
1423          * @return Boolean: whether the connection exists
1424          */
1425         public function ping() {
1426                 // db2_ping() doesn't exist
1427                 // Emulate
1428                 $this->close();
1429                 $this->mConn = $this->openUncataloged( $this->mDBName, $this->mUser,
1430                         $this->mPassword, $this->mServer, $this->mPort );
1431
1432                 return false;
1433         }
1434         ######################################
1435         # Unimplemented and not applicable
1436         ######################################
1437         /**
1438          * Not implemented
1439          * @return string $sql
1440          */
1441         public function limitResultForUpdate( $sql, $num ) {
1442                 $this->installPrint( 'Not implemented for DB2: limitResultForUpdate()' );
1443                 return $sql;
1444         }
1445
1446         /**
1447          * Only useful with fake prepare like in base Database class
1448          * @return      string
1449          */
1450         public function fillPreparedArg( $matches ) {
1451                 $this->installPrint( 'Not useful for DB2: fillPreparedArg()' );
1452                 return '';
1453         }
1454
1455         ######################################
1456         # Reflection
1457         ######################################
1458
1459         /**
1460          * Returns information about an index
1461          * If errors are explicitly ignored, returns NULL on failure
1462          * @param $table String: table name
1463          * @param $index String: index name
1464          * @param $fname String: function name for logging and profiling
1465          * @return Object query row in object form
1466          */
1467         public function indexInfo( $table, $index,
1468                 $fname = 'DatabaseIbm_db2::indexExists' )
1469         {
1470                 $table = $this->tableName( $table );
1471                 $sql = <<<SQL
1472 SELECT name as indexname
1473 FROM sysibm.sysindexes si
1474 WHERE si.name='$index' AND si.tbname='$table'
1475 AND sc.tbcreator='$this->mSchema'
1476 SQL;
1477                 $res = $this->query( $sql, $fname );
1478                 if ( !$res ) {
1479                         return null;
1480                 }
1481                 $row = $this->fetchObject( $res );
1482                 if ( $row != null ) {
1483                         return $row;
1484                 } else {
1485                         return false;
1486                 }
1487         }
1488
1489         /**
1490          * Returns an information object on a table column
1491          * @param $table String: table name
1492          * @param $field String: column name
1493          * @return IBM_DB2Field
1494          */
1495         public function fieldInfo( $table, $field ) {
1496                 return IBM_DB2Field::fromText( $this, $table, $field );
1497         }
1498
1499         /**
1500          * db2_field_type() wrapper
1501          * @param $res Object: result of executed statement
1502          * @param $index Mixed: number or name of the column
1503          * @return String column type
1504          */
1505         public function fieldType( $res, $index ) {
1506                 if ( $res instanceof ResultWrapper ) {
1507                         $res = $res->result;
1508                 }
1509                 if ( $res instanceof IBM_DB2Result ) {
1510                         $res = $res->getResult();
1511                 }
1512                 return db2_field_type( $res, $index );
1513         }
1514
1515         /**
1516          * Verifies that an index was created as unique
1517          * @param $table String: table name
1518          * @param $index String: index name
1519          * @param $fname string function name for profiling
1520          * @return Bool
1521          */
1522         public function indexUnique ( $table, $index,
1523                 $fname = 'DatabaseIbm_db2::indexUnique' )
1524         {
1525                 $table = $this->tableName( $table );
1526                 $sql = <<<SQL
1527 SELECT si.name as indexname
1528 FROM sysibm.sysindexes si
1529 WHERE si.name='$index' AND si.tbname='$table'
1530 AND sc.tbcreator='$this->mSchema'
1531 AND si.uniquerule IN ( 'U', 'P' )
1532 SQL;
1533                 $res = $this->query( $sql, $fname );
1534                 if ( !$res ) {
1535                         return null;
1536                 }
1537                 if ( $this->fetchObject( $res ) ) {
1538                         return true;
1539                 }
1540                 return false;
1541
1542         }
1543
1544         /**
1545          * Returns the size of a text field, or -1 for "unlimited"
1546          * @param $table String: table name
1547          * @param $field String: column name
1548          * @return Integer: length or -1 for unlimited
1549          */
1550         public function textFieldSize( $table, $field ) {
1551                 $table = $this->tableName( $table );
1552                 $sql = <<<SQL
1553 SELECT length as size
1554 FROM sysibm.syscolumns sc
1555 WHERE sc.name='$field' AND sc.tbname='$table'
1556 AND sc.tbcreator='$this->mSchema'
1557 SQL;
1558                 $res = $this->query( $sql );
1559                 $row = $this->fetchObject( $res );
1560                 $size = $row->size;
1561                 return $size;
1562         }
1563
1564         /**
1565          * Description is left as an exercise for the reader
1566          * @param $b Mixed: data to be encoded
1567          * @return IBM_DB2Blob
1568          */
1569         public function encodeBlob( $b ) {
1570                 return new IBM_DB2Blob( $b );
1571         }
1572
1573         /**
1574          * Description is left as an exercise for the reader
1575          * @param $b IBM_DB2Blob: data to be decoded
1576          * @return mixed
1577          */
1578         public function decodeBlob( $b ) {
1579                 return "$b";
1580         }
1581
1582         /**
1583          * Convert into a list of string being concatenated
1584          * @param $stringList Array: strings that need to be joined together
1585          *                    by the SQL engine
1586          * @return String: joined by the concatenation operator
1587          */
1588         public function buildConcat( $stringList ) {
1589                 // || is equivalent to CONCAT
1590                 // Sample query: VALUES 'foo' CONCAT 'bar' CONCAT 'baz'
1591                 return implode( ' || ', $stringList );
1592         }
1593
1594         /**
1595          * Generates the SQL required to convert a DB2 timestamp into a Unix epoch
1596          * @param $column String: name of timestamp column
1597          * @return String: SQL code
1598          */
1599         public function extractUnixEpoch( $column ) {
1600                 // TODO
1601                 // see SpecialAncientpages
1602         }
1603
1604         ######################################
1605         # Prepared statements
1606         ######################################
1607
1608         /**
1609          * Intended to be compatible with the PEAR::DB wrapper functions.
1610          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
1611          *
1612          * ? = scalar value, quoted as necessary
1613          * ! = raw SQL bit (a function for instance)
1614          * & = filename; reads the file and inserts as a blob
1615          *     (we don't use this though...)
1616          * @param $sql String: SQL statement with appropriate markers
1617          * @param $func String: Name of the function, for profiling
1618          * @return resource a prepared DB2 SQL statement
1619          */
1620         public function prepare( $sql, $func = 'DB2::prepare' ) {
1621                 $stmt = db2_prepare( $this->mConn, $sql, $this->mStmtOptions );
1622                 return $stmt;
1623         }
1624
1625         /**
1626          * Frees resources associated with a prepared statement
1627          * @return Boolean success or failure
1628          */
1629         public function freePrepared( $prepared ) {
1630                 return db2_free_stmt( $prepared );
1631         }
1632
1633         /**
1634          * Execute a prepared query with the various arguments
1635          * @param $prepared String: the prepared sql
1636          * @param $args Mixed: either an array here, or put scalars as varargs
1637          * @return Resource: results object
1638          */
1639         public function execute( $prepared, $args = null ) {
1640                 if( !is_array( $args ) ) {
1641                         # Pull the var args
1642                         $args = func_get_args();
1643                         array_shift( $args );
1644                 }
1645                 $res = db2_execute( $prepared, $args );
1646                 if ( !$res ) {
1647                         $this->installPrint( db2_stmt_errormsg() );
1648                 }
1649                 return $res;
1650         }
1651
1652         /**
1653          * Prepare & execute an SQL statement, quoting and inserting arguments
1654          * in the appropriate places.
1655          * @param $query String
1656          * @param $args ...
1657          * @return Resource
1658          */
1659         public function safeQuery( $query, $args = null ) {
1660                 // copied verbatim from Database.php
1661                 $prepared = $this->prepare( $query, 'DB2::safeQuery' );
1662                 if( !is_array( $args ) ) {
1663                         # Pull the var args
1664                         $args = func_get_args();
1665                         array_shift( $args );
1666                 }
1667                 $retval = $this->execute( $prepared, $args );
1668                 $this->freePrepared( $prepared );
1669                 return $retval;
1670         }
1671
1672         /**
1673          * For faking prepared SQL statements on DBs that don't support
1674          * it directly.
1675          * @param $preparedQuery String: a 'preparable' SQL statement
1676          * @param $args Array of arguments to fill it with
1677          * @return String: executable statement
1678          */
1679         public function fillPrepared( $preparedQuery, $args ) {
1680                 reset( $args );
1681                 $this->preparedArgs =& $args;
1682
1683                 foreach ( $args as $i => $arg ) {
1684                         db2_bind_param( $preparedQuery, $i+1, $args[$i] );
1685                 }
1686
1687                 return $preparedQuery;
1688         }
1689
1690         /**
1691          * Switches module between regular and install modes
1692          * @return string
1693          */
1694         public function setMode( $mode ) {
1695                 $old = $this->mMode;
1696                 $this->mMode = $mode;
1697                 return $old;
1698         }
1699
1700         /**
1701          * Bitwise negation of a column or value in SQL
1702          * Same as (~field) in C
1703          * @param $field String
1704          * @return String
1705          */
1706         function bitNot( $field ) {
1707                 // expecting bit-fields smaller than 4bytes
1708                 return "BITNOT( $field )";
1709         }
1710
1711         /**
1712          * Bitwise AND of two columns or values in SQL
1713          * Same as (fieldLeft & fieldRight) in C
1714          * @param $fieldLeft String
1715          * @param $fieldRight String
1716          * @return String
1717          */
1718         function bitAnd( $fieldLeft, $fieldRight ) {
1719                 return "BITAND( $fieldLeft, $fieldRight )";
1720         }
1721
1722         /**
1723          * Bitwise OR of two columns or values in SQL
1724          * Same as (fieldLeft | fieldRight) in C
1725          * @param $fieldLeft String
1726          * @param $fieldRight String
1727          * @return String
1728          */
1729         function bitOr( $fieldLeft, $fieldRight ) {
1730                 return "BITOR( $fieldLeft, $fieldRight )";
1731         }
1732 }
1733
1734 class IBM_DB2Helper {
1735         public static function makeArray( $maybeArray ) {
1736                 if ( !is_array( $maybeArray ) ) {
1737                         return array( $maybeArray );
1738                 }
1739
1740                 return $maybeArray;
1741         }
1742 }