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  * Primary database interface
 108  * @ingroup Database
 109  */
 110 class DatabaseIbm_db2 extends DatabaseBase {
 111         /*
 112          * Inherited members
 113         protected $mLastQuery = '';
 114         protected $mPHPError = false;
 115
 116         protected $mServer, $mUser, $mPassword, $mConn = null, $mDBname;
 117         protected $mOpened = false;
 118
 119         protected $mTablePrefix;
 120         protected $mFlags;
 121         protected $mTrxLevel = 0;
 122         protected $mErrorCount = 0;
 123         protected $mLBInfo = array();
 124         protected $mFakeSlaveLag = null, $mFakeMaster = false;
 125          *
 126          */
 127
 128         /** Database server port */
 129         protected $mPort = null;
 130         /** Schema for tables, stored procedures, triggers */
 131         protected $mSchema = null;
 132         /** Whether the schema has been applied in this session */
 133         protected $mSchemaSet = false;
 134         /** Result of last query */
 135         protected $mLastResult = null;
 136         /** Number of rows affected by last INSERT/UPDATE/DELETE */
 137         protected $mAffectedRows = null;
 138         /** Number of rows returned by last SELECT */
 139         protected $mNumRows = null;
 140
 141         /** Connection config options - see constructor */
 142         public $mConnOptions = array();
 143         /** Statement config options -- see constructor */
 144         public $mStmtOptions = array();
 145
 146         /** Default schema */
 147         const USE_GLOBAL = 'mediawiki';
 148
 149         /** Option that applies to nothing */
 150         const NONE_OPTION = 0x00;
 151         /** Option that applies to connection objects */
 152         const CONN_OPTION = 0x01;
 153         /** Option that applies to statement objects */
 154         const STMT_OPTION = 0x02;
 155
 156         /** Regular operation mode -- minimal debug messages */
 157         const REGULAR_MODE = 'regular';
 158         /** Installation mode -- lots of debug messages */
 159         const INSTALL_MODE = 'install';
 160
 161         /** Controls the level of debug message output */
 162         protected $mMode = self::REGULAR_MODE;
 163
 164         /** Last sequence value used for a primary key */
 165         protected $mInsertId = null;
 166
 167         ######################################
 168         # Getters and Setters
 169         ######################################
 170
 171         /**
 172          * Returns true if this database supports (and uses) cascading deletes
 173          */
 174         function cascadingDeletes() {
 175                 return true;
 176         }
 177
 178         /**
 179          * Returns true if this database supports (and uses) triggers (e.g. on the
 180          *  page table)
 181          */
 182         function cleanupTriggers() {
 183                 return true;
 184         }
 185
 186         /**
 187          * Returns true if this database is strict about what can be put into an
 188          *  IP field.
 189          * Specifically, it uses a NULL value instead of an empty string.
 190          */
 191         function strictIPs() {
 192                 return true;
 193         }
 194
 195         /**
 196          * Returns true if this database uses timestamps rather than integers
 197         */
 198         function realTimestamps() {
 199                 return true;
 200         }
 201
 202         /**
 203          * Returns true if this database does an implicit sort when doing GROUP BY
 204          */
 205         function implicitGroupby() {
 206                 return false;
 207         }
 208
 209         /**
 210          * Returns true if this database does an implicit order by when the column
 211          *  has an index
 212          * For example: SELECT page_title FROM page LIMIT 1
 213          */
 214         function implicitOrderby() {
 215                 return false;
 216         }
 217
 218         /**
 219          * Returns true if this database can do a native search on IP columns
 220          * e.g. this works as expected: .. WHERE rc_ip = '127.42.12.102/32';
 221          */
 222         function searchableIPs() {
 223                 return true;
 224         }
 225
 226         /**
 227          * Returns true if this database can use functional indexes
 228          */
 229         function functionalIndexes() {
 230                 return true;
 231         }
 232
 233         /**
 234          * Returns a unique string representing the wiki on the server
 235          */
 236         function getWikiID() {
 237                 if( $this->mSchema ) {
 238                         return "{$this->mDBname}-{$this->mSchema}";
 239                 } else {
 240                         return $this->mDBname;
 241                 }
 242         }
 243
 244         function getType() {
 245                 return 'ibm_db2';
 246         }
 247
 248         ######################################
 249         # Setup
 250         ######################################
 251
 252
 253         /**
 254          *
 255          * @param $server String: hostname of database server
 256          * @param $user String: username
 257          * @param $password String: password
 258          * @param $dbName String: database name on the server
 259          * @param $flags Integer: database behaviour flags (optional, unused)
 260          * @param $schema String
 261          */
 262         public function __construct( $server = false, $user = false,
 263                                                         $password = false,
 264                                                         $dbName = false, $flags = 0,
 265                                                         $schema = self::USE_GLOBAL )
 266         {
 267                 global $wgDBmwschema;
 268
 269                 if ( $schema == self::USE_GLOBAL ) {
 270                         $this->mSchema = $wgDBmwschema;
 271                 } else {
 272                         $this->mSchema = $schema;
 273                 }
 274
 275                 // configure the connection and statement objects
 276                 $this->setDB2Option( 'db2_attr_case', 'DB2_CASE_LOWER',
 277                         self::CONN_OPTION | self::STMT_OPTION );
 278                 $this->setDB2Option( 'deferred_prepare', 'DB2_DEFERRED_PREPARE_ON',
 279                         self::STMT_OPTION );
 280                 $this->setDB2Option( 'rowcount', 'DB2_ROWCOUNT_PREFETCH_ON',
 281                         self::STMT_OPTION );
 282
 283                 parent::__construct( $server, $user, $password, $dbName, DBO_TRX | $flags );
 284         }
 285
 286         /**
 287          * Enables options only if the ibm_db2 extension version supports them
 288          * @param $name String: name of the option in the options array
 289          * @param $const String: name of the constant holding the right option value
 290          * @param $type Integer: whether this is a Connection or Statement otion
 291          */
 292         private function setDB2Option( $name, $const, $type ) {
 293                 if ( defined( $const ) ) {
 294                         if ( $type & self::CONN_OPTION ) {
 295                                 $this->mConnOptions[$name] = constant( $const );
 296                         }
 297                         if ( $type & self::STMT_OPTION ) {
 298                                 $this->mStmtOptions[$name] = constant( $const );
 299                         }
 300                 } else {
 301                         $this->installPrint(
 302                                 "$const is not defined. ibm_db2 version is likely too low." );
 303                 }
 304         }
 305
 306         /**
 307          * Outputs debug information in the appropriate place
 308          * @param $string String: the relevant debug message
 309          */
 310         private function installPrint( $string ) {
 311                 wfDebug( "$string\n" );
 312                 if ( $this->mMode == self::INSTALL_MODE ) {
 313                         print "<li><pre>$string</pre></li>";
 314                         flush();
 315                 }
 316         }
 317
 318         /**
 319          * Opens a database connection and returns it
 320          * Closes any existing connection
 321          *
 322          * @param $server String: hostname
 323          * @param $user String
 324          * @param $password String
 325          * @param $dbName String: database name
 326          * @return a fresh connection
 327          */
 328         public function open( $server, $user, $password, $dbName ) {
 329                 // Load the port number
 330                 global $wgDBport;
 331                 wfProfileIn( __METHOD__ );
 332
 333                 // Load IBM DB2 driver if missing
 334                 wfDl( 'ibm_db2' );
 335
 336                 // Test for IBM DB2 support, to avoid suppressed fatal error
 337                 if ( !function_exists( 'db2_connect' ) ) {
 338                         $error = <<<ERROR
 339 DB2 functions missing, have you enabled the ibm_db2 extension for PHP?
 340
 341 ERROR;
 342                         $this->installPrint( $error );
 343                         $this->reportConnectionError( $error );
 344                 }
 345
 346                 if ( strlen( $user ) < 1 ) {
 347                         wfProfileOut( __METHOD__ );
 348                         return null;
 349                 }
 350
 351                 // Close existing connection
 352                 $this->close();
 353                 // Cache conn info
 354                 $this->mServer = $server;
 355                 $this->mPort = $port = $wgDBport;
 356                 $this->mUser = $user;
 357                 $this->mPassword = $password;
 358                 $this->mDBname = $dbName;
 359
 360                 $this->openUncataloged( $dbName, $user, $password, $server, $port );
 361
 362                 // Apply connection config
 363                 db2_set_option( $this->mConn, $this->mConnOptions, 1 );
 364                 // Some MediaWiki code is still transaction-less (?).
 365                 // The strategy is to keep AutoCommit on for that code
 366                 //  but switch it off whenever a transaction is begun.
 367                 db2_autocommit( $this->mConn, DB2_AUTOCOMMIT_ON );
 368
 369                 if ( !$this->mConn ) {
 370                         $this->installPrint( "DB connection error\n" );
 371                         $this->installPrint(
 372                                 "Server: $server, Database: $dbName, User: $user, Password: "
 373                                 . substr( $password, 0, 3 ) . "...\n" );
 374                         $this->installPrint( $this->lastError() . "\n" );
 375
 376                         wfProfileOut( __METHOD__ );
 377                         return null;
 378                 }
 379
 380                 $this->mOpened = true;
 381                 $this->applySchema();
 382
 383                 wfProfileOut( __METHOD__ );
 384                 return $this->mConn;
 385         }
 386
 387         /**
 388          * Opens a cataloged database connection, sets mConn
 389          */
 390         protected function openCataloged( $dbName, $user, $password ) {
 391                 @$this->mConn = db2_pconnect( $dbName, $user, $password );
 392         }
 393
 394         /**
 395          * Opens an uncataloged database connection, sets mConn
 396          */
 397         protected function openUncataloged( $dbName, $user, $password, $server, $port )
 398         {
 399                 $str = "DRIVER={IBM DB2 ODBC DRIVER};";
 400                 $str .= "DATABASE=$dbName;";
 401                 $str .= "HOSTNAME=$server;";
 402                 // port was formerly validated to not be 0
 403                 $str .= "PORT=$port;";
 404                 $str .= "PROTOCOL=TCPIP;";
 405                 $str .= "UID=$user;";
 406                 $str .= "PWD=$password;";
 407
 408                 @$this->mConn = db2_pconnect( $str, $user, $password );
 409         }
 410
 411         /**
 412          * Closes a database connection, if it is open
 413          * Returns success, true if already closed
 414          */
 415         public function close() {
 416                 $this->mOpened = false;
 417                 if ( $this->mConn ) {
 418                         if ( $this->trxLevel() > 0 ) {
 419                                 $this->commit();
 420                         }
 421                         return db2_close( $this->mConn );
 422                 } else {
 423                         return true;
 424                 }
 425         }
 426
 427         /**
 428          * Retrieves the most current database error
 429          * Forces a database rollback
 430          */
 431         public function lastError() {
 432                 $connerr = db2_conn_errormsg();
 433                 if ( $connerr ) {
 434                         //$this->rollback();
 435                         return $connerr;
 436                 }
 437                 $stmterr = db2_stmt_errormsg();
 438                 if ( $stmterr ) {
 439                         //$this->rollback();
 440                         return $stmterr;
 441                 }
 442
 443                 return false;
 444         }
 445
 446         /**
 447          * Get the last error number
 448          * Return 0 if no error
 449          * @return integer
 450          */
 451         public function lastErrno() {
 452                 $connerr = db2_conn_error();
 453                 if ( $connerr ) {
 454                         return $connerr;
 455                 }
 456                 $stmterr = db2_stmt_error();
 457                 if ( $stmterr ) {
 458                         return $stmterr;
 459                 }
 460                 return 0;
 461         }
 462
 463         /**
 464          * Is a database connection open?
 465          * @return
 466          */
 467         public function isOpen() { return $this->mOpened; }
 468
 469         /**
 470          * The DBMS-dependent part of query()
 471          * @param  $sql String: SQL query.
 472          * @return object Result object for fetch functions or false on failure
 473          * @access private
 474          */
 475         /*private*/
 476         public function doQuery( $sql ) {
 477                 $this->applySchema();
 478
 479                 $ret = db2_exec( $this->mConn, $sql, $this->mStmtOptions );
 480                 if( $ret == false ) {
 481                         $error = db2_stmt_errormsg();
 482                         $this->installPrint( "<pre>$sql</pre>" );
 483                         $this->installPrint( $error );
 484                         throw new DBUnexpectedError( $this, 'SQL error: '
 485                                 . htmlspecialchars( $error ) );
 486                 }
 487                 $this->mLastResult = $ret;
 488                 $this->mAffectedRows = null; // Not calculated until asked for
 489                 return $ret;
 490         }
 491
 492         /**
 493          * @return string Version information from the database
 494          */
 495         public function getServerVersion() {
 496                 $info = db2_server_info( $this->mConn );
 497                 return $info->DBMS_VER;
 498         }
 499
 500         /**
 501          * Queries whether a given table exists
 502          * @return boolean
 503          */
 504         public function tableExists( $table ) {
 505                 $schema = $this->mSchema;
 506                 $sql = <<< EOF
 507 SELECT COUNT( * ) FROM SYSIBM.SYSTABLES ST
 508 WHERE ST.NAME = '$table' AND ST.CREATOR = '$schema'
 509 EOF;
 510                 $res = $this->query( $sql );
 511                 if ( !$res ) {
 512                         return false;
 513                 }
 514
 515                 // If the table exists, there should be one of it
 516                 @$row = $this->fetchRow( $res );
 517                 $count = $row[0];
 518                 if ( $count == '1' || $count == 1 ) {
 519                         return true;
 520                 }
 521
 522                 return false;
 523         }
 524
 525         /**
 526          * Fetch the next row from the given result object, in object form.
 527          * Fields can be retrieved with $row->fieldname, with fields acting like
 528          * member variables.
 529          *
 530          * @param $res SQL result object as returned from Database::query(), etc.
 531          * @return DB2 row object
 532          * @throws DBUnexpectedError Thrown if the database returns an error
 533          */
 534         public function fetchObject( $res ) {
 535                 if ( $res instanceof ResultWrapper ) {
 536                         $res = $res->result;
 537                 }
 538                 @$row = db2_fetch_object( $res );
 539                 if( $this->lastErrno() ) {
 540                         throw new DBUnexpectedError( $this, 'Error in fetchObject(): '
 541                                 . htmlspecialchars( $this->lastError() ) );
 542                 }
 543                 return $row;
 544         }
 545
 546         /**
 547          * Fetch the next row from the given result object, in associative array
 548          * form. Fields are retrieved with $row['fieldname'].
 549          *
 550          * @param $res SQL result object as returned from Database::query(), etc.
 551          * @return DB2 row object
 552          * @throws DBUnexpectedError Thrown if the database returns an error
 553          */
 554         public function fetchRow( $res ) {
 555                 if ( $res instanceof ResultWrapper ) {
 556                         $res = $res->result;
 557                 }
 558                 @$row = db2_fetch_array( $res );
 559                 if ( $this->lastErrno() ) {
 560                         throw new DBUnexpectedError( $this, 'Error in fetchRow(): '
 561                                 . htmlspecialchars( $this->lastError() ) );
 562                 }
 563                 return $row;
 564         }
 565
 566         /**
 567          * Create tables, stored procedures, and so on
 568          */
 569         public function setup_database() {
 570                 try {
 571                         // TODO: switch to root login if available
 572
 573                         // Switch into the correct namespace
 574                         $this->applySchema();
 575                         $this->begin();
 576
 577                         $res = $this->sourceFile( "../maintenance/ibm_db2/tables.sql" );
 578                         if ( $res !== true ) {
 579                                 print ' <b>FAILED</b>: ' . htmlspecialchars( $res ) . '</li>';
 580                         } else {
 581                                 print ' done</li>';
 582                         }
 583                         $res = $this->sourceFile( "../maintenance/ibm_db2/foreignkeys.sql" );
 584                         if ( $res !== true ) {
 585                                 print ' <b>FAILED</b>: ' . htmlspecialchars( $res ) . '</li>';
 586                         } else {
 587                                 print '<li>Foreign keys done</li>';
 588                         }
 589
 590                         // TODO: populate interwiki links
 591
 592                         if ( $this->lastError() ) {
 593                                 $this->installPrint(
 594                                         'Errors encountered during table creation -- rolled back' );
 595                                 $this->installPrint( 'Please install again' );
 596                                 $this->rollback();
 597                         } else {
 598                                 $this->commit();
 599                         }
 600                 } catch ( MWException $mwe ) {
 601                         print "<br><pre>$mwe</pre><br>";
 602                 }
 603         }
 604
 605         /**
 606          * Escapes strings
 607          * Doesn't escape numbers
 608          *
 609          * @param $s String: string to escape
 610          * @return escaped string
 611          */
 612         public function addQuotes( $s ) {
 613                 //$this->installPrint( "DB2::addQuotes( $s )\n" );
 614                 if ( is_null( $s ) ) {
 615                         return 'NULL';
 616                 } elseif ( $s instanceof Blob ) {
 617                         return "'" . $s->fetch( $s ) . "'";
 618                 } elseif ( $s instanceof IBM_DB2Blob ) {
 619                         return "'" . $this->decodeBlob( $s ) . "'";
 620                 }
 621                 $s = $this->strencode( $s );
 622                 if ( is_numeric( $s ) ) {
 623                         return $s;
 624                 } else {
 625                         return "'$s'";
 626                 }
 627         }
 628
 629         /**
 630          * Verifies that a DB2 column/field type is numeric
 631          *
 632          * @param $type String: DB2 column type
 633          * @return Boolean: true if numeric
 634          */
 635         public function is_numeric_type( $type ) {
 636                 switch ( strtoupper( $type ) ) {
 637                         case 'SMALLINT':
 638                         case 'INTEGER':
 639                         case 'INT':
 640                         case 'BIGINT':
 641                         case 'DECIMAL':
 642                         case 'REAL':
 643                         case 'DOUBLE':
 644                         case 'DECFLOAT':
 645                                 return true;
 646                 }
 647                 return false;
 648         }
 649
 650         /**
 651          * Alias for addQuotes()
 652          * @param $s String: string to escape
 653          * @return escaped string
 654          */
 655         public function strencode( $s ) {
 656                 // Bloody useless function
 657                 //  Prepends backslashes to \x00, \n, \r, \, ', " and \x1a.
 658                 //  But also necessary
 659                 $s = db2_escape_string( $s );
 660                 // Wide characters are evil -- some of them look like '
 661                 $s = utf8_encode( $s );
 662                 // Fix its stupidity
 663                 $from = array(  "\\\\", "\\'",  '\\n',  '\\t',  '\\"',  '\\r' );
 664                 $to = array(            "\\",           "''",           "\n",           "\t",           '"',            "\r" );
 665                 $s = str_replace( $from, $to, $s ); // DB2 expects '', not \' escaping
 666                 return $s;
 667         }
 668
 669         /**
 670          * Switch into the database schema
 671          */
 672         protected function applySchema() {
 673                 if ( !( $this->mSchemaSet ) ) {
 674                         $this->mSchemaSet = true;
 675                         $this->begin();
 676                         $this->doQuery( "SET SCHEMA = $this->mSchema" );
 677                         $this->commit();
 678                 }
 679         }
 680
 681         /**
 682          * Start a transaction (mandatory)
 683          */
 684         public function begin( $fname = 'DatabaseIbm_db2::begin' ) {
 685                 // BEGIN is implicit for DB2
 686                 // However, it requires that AutoCommit be off.
 687
 688                 // Some MediaWiki code is still transaction-less (?).
 689                 // The strategy is to keep AutoCommit on for that code
 690                 //  but switch it off whenever a transaction is begun.
 691                 db2_autocommit( $this->mConn, DB2_AUTOCOMMIT_OFF );
 692
 693                 $this->mTrxLevel = 1;
 694         }
 695
 696         /**
 697          * End a transaction
 698          * Must have a preceding begin()
 699          */
 700         public function commit( $fname = 'DatabaseIbm_db2::commit' ) {
 701                 db2_commit( $this->mConn );
 702
 703                 // Some MediaWiki code is still transaction-less (?).
 704                 // The strategy is to keep AutoCommit on for that code
 705                 //  but switch it off whenever a transaction is begun.
 706                 db2_autocommit( $this->mConn, DB2_AUTOCOMMIT_ON );
 707
 708                 $this->mTrxLevel = 0;
 709         }
 710
 711         /**
 712          * Cancel a transaction
 713          */
 714         public function rollback( $fname = 'DatabaseIbm_db2::rollback' ) {
 715                 db2_rollback( $this->mConn );
 716                 // turn auto-commit back on
 717                 // not sure if this is appropriate
 718                 db2_autocommit( $this->mConn, DB2_AUTOCOMMIT_ON );
 719                 $this->mTrxLevel = 0;
 720         }
 721
 722         /**
 723          * Makes an encoded list of strings from an array
 724          * $mode:
 725          *   LIST_COMMA         - comma separated, no field names
 726          *   LIST_AND           - ANDed WHERE clause (without the WHERE)
 727          *   LIST_OR            - ORed WHERE clause (without the WHERE)
 728          *   LIST_SET           - comma separated with field names, like a SET clause
 729          *   LIST_NAMES         - comma separated field names
 730          *   LIST_SET_PREPARED  - like LIST_SET, except with ? tokens as values
 731          */
 732         function makeList( $a, $mode = LIST_COMMA ) {
 733                 if ( !is_array( $a ) ) {
 734                         throw new DBUnexpectedError( $this,
 735                                 'DatabaseIbm_db2::makeList called with incorrect parameters' );
 736                 }
 737
 738                 // if this is for a prepared UPDATE statement
 739                 // (this should be promoted to the parent class
 740                 //  once other databases use prepared statements)
 741                 if ( $mode == LIST_SET_PREPARED ) {
 742                         $first = true;
 743                         $list = '';
 744                         foreach ( $a as $field => $value ) {
 745                                 if ( !$first ) {
 746                                         $list .= ", $field = ?";
 747                                 } else {
 748                                         $list .= "$field = ?";
 749                                         $first = false;
 750                                 }
 751                         }
 752                         $list .= '';
 753
 754                         return $list;
 755                 }
 756
 757                 // otherwise, call the usual function
 758                 return parent::makeList( $a, $mode );
 759         }
 760
 761         /**
 762          * Construct a LIMIT query with optional offset
 763          * This is used for query pages
 764          *
 765          * @param $sql string SQL query we will append the limit too
 766          * @param $limit integer the SQL limit
 767          * @param $offset integer the SQL offset (default false)
 768          */
 769         public function limitResult( $sql, $limit, $offset=false ) {
 770                 if( !is_numeric( $limit ) ) {
 771                         throw new DBUnexpectedError( $this,
 772                                 "Invalid non-numeric limit passed to limitResult()\n" );
 773                 }
 774                 if( $offset ) {
 775                         if ( stripos( $sql, 'where' ) === false ) {
 776                                 return "$sql AND ( ROWNUM BETWEEN $offset AND $offset+$limit )";
 777                         } else {
 778                                 return "$sql WHERE ( ROWNUM BETWEEN $offset AND $offset+$limit )";
 779                         }
 780                 }
 781                 return "$sql FETCH FIRST $limit ROWS ONLY ";
 782         }
 783
 784         /**
 785          * Handle reserved keyword replacement in table names
 786          *
 787          * @param $name Object
 788          * @return String
 789          */
 790         public function tableName( $name ) {
 791                 // we want maximum compatibility with MySQL schema
 792                 return $name;
 793         }
 794
 795         /**
 796          * Generates a timestamp in an insertable format
 797          *
 798          * @param $ts timestamp
 799          * @return String: timestamp value
 800          */
 801         public function timestamp( $ts = 0 ) {
 802                 // TS_MW cannot be easily distinguished from an integer
 803                 return wfTimestamp( TS_DB2, $ts );
 804         }
 805
 806         /**
 807          * Return the next in a sequence, save the value for retrieval via insertId()
 808          * @param $seqName String: name of a defined sequence in the database
 809          * @return next value in that sequence
 810          */
 811         public function nextSequenceValue( $seqName ) {
 812                 // Not using sequences in the primary schema to allow for easier migration
 813                 //  from MySQL
 814                 // Emulating MySQL behaviour of using NULL to signal that sequences
 815                 // aren't used
 816                 /*
 817                 $safeseq = preg_replace( "/'/", "''", $seqName );
 818                 $res = $this->query( "VALUES NEXTVAL FOR $safeseq" );
 819                 $row = $this->fetchRow( $res );
 820                 $this->mInsertId = $row[0];
 821                 return $this->mInsertId;
 822                 */
 823                 return null;
 824         }
 825
 826         /**
 827          * This must be called after nextSequenceVal
 828          * @return Last sequence value used as a primary key
 829          */
 830         public function insertId() {
 831                 return $this->mInsertId;
 832         }
 833
 834         /**
 835          * Updates the mInsertId property with the value of the last insert
 836          *  into a generated column
 837          *
 838          * @param $table      String: sanitized table name
 839          * @param $primaryKey Mixed: string name of the primary key
 840          * @param $stmt       Resource: prepared statement resource
 841          *  of the SELECT primary_key FROM FINAL TABLE ( INSERT ... ) form
 842          */
 843         private function calcInsertId( $table, $primaryKey, $stmt ) {
 844                 if ( $primaryKey ) {
 845                         $this->mInsertId = db2_last_insert_id( $this->mConn );
 846                 }
 847         }
 848
 849         /**
 850          * INSERT wrapper, inserts an array into a table
 851          *
 852          * $args may be a single associative array, or an array of arrays
 853          *  with numeric keys, for multi-row insert
 854          *
 855          * @param $table   String: Name of the table to insert to.
 856          * @param $args    Array: Items to insert into the table.
 857          * @param $fname   String: Name of the function, for profiling
 858          * @param $options String or Array. Valid options: IGNORE
 859          *
 860          * @return bool Success of insert operation. IGNORE always returns true.
 861          */
 862         public function insert( $table, $args, $fname = 'DatabaseIbm_db2::insert',
 863                 $options = array() )
 864         {
 865                 if ( !count( $args ) ) {
 866                         return true;
 867                 }
 868                 // get database-specific table name (not used)
 869                 $table = $this->tableName( $table );
 870                 // format options as an array
 871                 $options = IBM_DB2Helper::makeArray( $options );
 872                 // format args as an array of arrays
 873                 if ( !( isset( $args[0] ) && is_array( $args[0] ) ) ) {
 874                         $args = array( $args );
 875                 }
 876
 877                 // prevent insertion of NULL into primary key columns
 878                 list( $args, $primaryKeys ) = $this->removeNullPrimaryKeys( $table, $args );
 879                 // if there's only one primary key
 880                 // we'll be able to read its value after insertion
 881                 $primaryKey = false;
 882                 if ( count( $primaryKeys ) == 1 ) {
 883                         $primaryKey = $primaryKeys[0];
 884                 }
 885
 886                 // get column names
 887                 $keys = array_keys( $args[0] );
 888                 $key_count = count( $keys );
 889
 890                 // If IGNORE is set, we use savepoints to emulate mysql's behavior
 891                 $ignore = in_array( 'IGNORE', $options ) ? 'mw' : '';
 892
 893                 // assume success
 894                 $res = true;
 895                 // If we are not in a transaction, we need to be for savepoint trickery
 896                 if ( !$this->mTrxLevel ) {
 897                         $this->begin();
 898                 }
 899
 900                 $sql = "INSERT INTO $table ( " . implode( ',', $keys ) . ' ) VALUES ';
 901                 if ( $key_count == 1 ) {
 902                         $sql .= '( ? )';
 903                 } else {
 904                         $sql .= '( ?' . str_repeat( ',?', $key_count-1 ) . ' )';
 905                 }
 906                 //$this->installPrint( "Preparing the following SQL:" );
 907                 //$this->installPrint( "$sql" );
 908                 //$this->installPrint( print_r( $args, true ));
 909                 $stmt = $this->prepare( $sql );
 910
 911                 // start a transaction/enter transaction mode
 912                 $this->begin();
 913
 914                 if ( !$ignore ) {
 915                         //$first = true;
 916                         foreach ( $args as $row ) {
 917                                 //$this->installPrint( "Inserting " . print_r( $row, true ));
 918                                 // insert each row into the database
 919                                 $res = $res & $this->execute( $stmt, $row );
 920                                 if ( !$res ) {
 921                                         $this->installPrint( 'Last error:' );
 922                                         $this->installPrint( $this->lastError() );
 923                                 }
 924                                 // get the last inserted value into a generated column
 925                                 $this->calcInsertId( $table, $primaryKey, $stmt );
 926                         }
 927                 } else {
 928                         $olde = error_reporting( 0 );
 929                         // For future use, we may want to track the number of actual inserts
 930                         // Right now, insert (all writes) simply return true/false
 931                         $numrowsinserted = 0;
 932
 933                         // always return true
 934                         $res = true;
 935
 936                         foreach ( $args as $row ) {
 937                                 $overhead = "SAVEPOINT $ignore ON ROLLBACK RETAIN CURSORS";
 938                                 db2_exec( $this->mConn, $overhead, $this->mStmtOptions );
 939
 940                                 $this->execute( $stmt, $row );
 941
 942                                 if ( !$res2 ) {
 943                                         $this->installPrint( 'Last error:' );
 944                                         $this->installPrint( $this->lastError() );
 945                                 }
 946                                 // get the last inserted value into a generated column
 947                                 $this->calcInsertId( $table, $primaryKey, $stmt );
 948
 949                                 $errNum = $this->lastErrno();
 950                                 if ( $errNum ) {
 951                                         db2_exec( $this->mConn, "ROLLBACK TO SAVEPOINT $ignore",
 952                                                 $this->mStmtOptions );
 953                                 } else {
 954                                         db2_exec( $this->mConn, "RELEASE SAVEPOINT $ignore",
 955                                                 $this->mStmtOptions );
 956                                         $numrowsinserted++;
 957                                 }
 958                         }
 959
 960                         $olde = error_reporting( $olde );
 961                         // Set the affected row count for the whole operation
 962                         $this->mAffectedRows = $numrowsinserted;
 963                 }
 964                 // commit either way
 965                 $this->commit();
 966                 $this->freePrepared( $stmt );
 967
 968                 return $res;
 969         }
 970
 971         /**
 972          * Given a table name and a hash of columns with values
 973          * Removes primary key columns from the hash where the value is NULL
 974          *
 975          * @param $table String: name of the table
 976          * @param $args Array of hashes of column names with values
 977          * @return Array: tuple( filtered array of columns, array of primary keys )
 978          */
 979         private function removeNullPrimaryKeys( $table, $args ) {
 980                 $schema = $this->mSchema;
 981                 // find out the primary keys
 982                 $keyres = db2_primary_keys( $this->mConn, null, strtoupper( $schema ),
 983                         strtoupper( $table )
 984                 );
 985                 $keys = array();
 986                 for (
 987                         $row = $this->fetchObject( $keyres );
 988                         $row != null;
 989                         $row = $this->fetchObject( $keyres )
 990                 )
 991                 {
 992                         $keys[] = strtolower( $row->column_name );
 993                 }
 994                 // remove primary keys
 995                 foreach ( $args as $ai => $row ) {
 996                         foreach ( $keys as $key ) {
 997                                 if ( $row[$key] == null ) {
 998                                         unset( $row[$key] );
 999                                 }
1000                         }
1001                         $args[$ai] = $row;
1002                 }
1003                 // return modified hash
1004                 return array( $args, $keys );
1005         }
1006
1007         /**
1008          * UPDATE wrapper, takes a condition array and a SET array
1009          *
1010          * @param $table  String: The table to UPDATE
1011          * @param $values An array of values to SET
1012          * @param $conds  An array of conditions ( WHERE ). Use '*' to update all rows.
1013          * @param $fname  String: The Class::Function calling this function
1014          *                ( for the log )
1015          * @param $options An array of UPDATE options, can be one or
1016          *                 more of IGNORE, LOW_PRIORITY
1017          * @return Boolean
1018          */
1019         public function update( $table, $values, $conds, $fname = 'DatabaseIbm_db2::update',
1020                 $options = array() )
1021         {
1022                 $table = $this->tableName( $table );
1023                 $opts = $this->makeUpdateOptions( $options );
1024                 $sql = "UPDATE $opts $table SET "
1025                         . $this->makeList( $values, LIST_SET_PREPARED );
1026                 if ( $conds != '*' ) {
1027                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1028                 }
1029                 $stmt = $this->prepare( $sql );
1030                 $this->installPrint( 'UPDATE: ' . print_r( $values, true ) );
1031                 // assuming for now that an array with string keys will work
1032                 // if not, convert to simple array first
1033                 $result = $this->execute( $stmt, $values );
1034                 $this->freePrepared( $stmt );
1035
1036                 return $result;
1037         }
1038
1039         /**
1040          * DELETE query wrapper
1041          *
1042          * Use $conds == "*" to delete all rows
1043          */
1044         public function delete( $table, $conds, $fname = 'DatabaseIbm_db2::delete' ) {
1045                 if ( !$conds ) {
1046                         throw new DBUnexpectedError( $this,
1047                                 'DatabaseIbm_db2::delete() called with no conditions' );
1048                 }
1049                 $table = $this->tableName( $table );
1050                 $sql = "DELETE FROM $table";
1051                 if ( $conds != '*' ) {
1052                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1053                 }
1054                 $result = $this->query( $sql, $fname );
1055
1056                 return $result;
1057         }
1058
1059         /**
1060          * Returns the number of rows affected by the last query or 0
1061          * @return Integer: the number of rows affected by the last query
1062          */
1063         public function affectedRows() {
1064                 if ( !is_null( $this->mAffectedRows ) ) {
1065                         // Forced result for simulated queries
1066                         return $this->mAffectedRows;
1067                 }
1068                 if( empty( $this->mLastResult ) ) {
1069                         return 0;
1070                 }
1071                 return db2_num_rows( $this->mLastResult );
1072         }
1073
1074         /**
1075          * Simulates REPLACE with a DELETE followed by INSERT
1076          * @param $table Object
1077          * @param $uniqueIndexes Array consisting of indexes and arrays of indexes
1078          * @param $rows Array: rows to insert
1079          * @param $fname String: name of the function for profiling
1080          * @return nothing
1081          */
1082         function replace( $table, $uniqueIndexes, $rows,
1083                 $fname = 'DatabaseIbm_db2::replace' )
1084         {
1085                 $table = $this->tableName( $table );
1086
1087                 if ( count( $rows )==0 ) {
1088                         return;
1089                 }
1090
1091                 # Single row case
1092                 if ( !is_array( reset( $rows ) ) ) {
1093                         $rows = array( $rows );
1094                 }
1095
1096                 foreach( $rows as $row ) {
1097                         # Delete rows which collide
1098                         if ( $uniqueIndexes ) {
1099                                 $sql = "DELETE FROM $table WHERE ";
1100                                 $first = true;
1101                                 foreach ( $uniqueIndexes as $index ) {
1102                                         if ( $first ) {
1103                                                 $first = false;
1104                                                 $sql .= '( ';
1105                                         } else {
1106                                                 $sql .= ' ) OR ( ';
1107                                         }
1108                                         if ( is_array( $index ) ) {
1109                                                 $first2 = true;
1110                                                 foreach ( $index as $col ) {
1111                                                         if ( $first2 ) {
1112                                                                 $first2 = false;
1113                                                         } else {
1114                                                                 $sql .= ' AND ';
1115                                                         }
1116                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
1117                                                 }
1118                                         } else {
1119                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
1120                                         }
1121                                 }
1122                                 $sql .= ' )';
1123                                 $this->query( $sql, $fname );
1124                         }
1125
1126                         # Now insert the row
1127                         $sql = "INSERT INTO $table ( "
1128                                 . $this->makeList( array_keys( $row ), LIST_NAMES )
1129                                 .' ) VALUES ( ' . $this->makeList( $row, LIST_COMMA ) . ' )';
1130                         $this->query( $sql, $fname );
1131                 }
1132         }
1133
1134         /**
1135          * Returns the number of rows in the result set
1136          * Has to be called right after the corresponding select query
1137          * @param $res Object result set
1138          * @return Integer: number of rows
1139          */
1140         public function numRows( $res ) {
1141                 if ( $res instanceof ResultWrapper ) {
1142                         $res = $res->result;
1143                 }
1144                 if ( $this->mNumRows ) {
1145                         return $this->mNumRows;
1146                 } else {
1147                         return 0;
1148                 }
1149         }
1150
1151         /**
1152          * Moves the row pointer of the result set
1153          * @param $res Object: result set
1154          * @param $row Integer: row number
1155          * @return success or failure
1156          */
1157         public function dataSeek( $res, $row ) {
1158                 if ( $res instanceof ResultWrapper ) {
1159                         $res = $res->result;
1160                 }
1161                 return db2_fetch_row( $res, $row );
1162         }
1163
1164         ###
1165         # Fix notices in Block.php
1166         ###
1167
1168         /**
1169          * Frees memory associated with a statement resource
1170          * @param $res Object: statement resource to free
1171          * @return Boolean success or failure
1172          */
1173         public function freeResult( $res ) {
1174                 if ( $res instanceof ResultWrapper ) {
1175                         $res = $res->result;
1176                 }
1177                 if ( !@db2_free_result( $res ) ) {
1178                         throw new DBUnexpectedError( $this, "Unable to free DB2 result\n" );
1179                 }
1180         }
1181
1182         /**
1183          * Returns the number of columns in a resource
1184          * @param $res Object: statement resource
1185          * @return Number of fields/columns in resource
1186          */
1187         public function numFields( $res ) {
1188                 if ( $res instanceof ResultWrapper ) {
1189                         $res = $res->result;
1190                 }
1191                 return db2_num_fields( $res );
1192         }
1193
1194         /**
1195          * Returns the nth column name
1196          * @param $res Object: statement resource
1197          * @param $n Integer: Index of field or column
1198          * @return String name of nth column
1199          */
1200         public function fieldName( $res, $n ) {
1201                 if ( $res instanceof ResultWrapper ) {
1202                         $res = $res->result;
1203                 }
1204                 return db2_field_name( $res, $n );
1205         }
1206
1207         /**
1208          * SELECT wrapper
1209          *
1210          * @param $table   Array or string, table name(s) (prefix auto-added)
1211          * @param $vars    Array or string, field name(s) to be retrieved
1212          * @param $conds   Array or string, condition(s) for WHERE
1213          * @param $fname   String: calling function name (use __METHOD__)
1214          *                 for logs/profiling
1215          * @param $options Associative array of options
1216          *                 (e.g. array('GROUP BY' => 'page_title')),
1217          *                 see Database::makeSelectOptions code for list of
1218          *                 supported stuff
1219          * @param $join_conds Associative array of table join conditions (optional)
1220          *                    (e.g. array( 'page' => array('LEFT JOIN',
1221          *                    'page_latest=rev_id') )
1222          * @return Mixed: database result resource for fetch functions or false
1223          *                 on failure
1224          */
1225         public function select( $table, $vars, $conds = '', $fname = 'DatabaseIbm_db2::select', $options = array(), $join_conds = array() )
1226         {
1227                 $res = parent::select( $table, $vars, $conds, $fname, $options,
1228                         $join_conds );
1229
1230                 // We must adjust for offset
1231                 if ( isset( $options['LIMIT'] ) && isset ( $options['OFFSET'] ) ) {
1232                         $limit = $options['LIMIT'];
1233                         $offset = $options['OFFSET'];
1234                 }
1235
1236                 // DB2 does not have a proper num_rows() function yet, so we must emulate
1237                 // DB2 9.5.4 and the corresponding ibm_db2 driver will introduce
1238                 //  a working one
1239                 // TODO: Yay!
1240
1241                 // we want the count
1242                 $vars2 = array( 'count( * ) as num_rows' );
1243                 // respecting just the limit option
1244                 $options2 = array();
1245                 if ( isset( $options['LIMIT'] ) ) {
1246                         $options2['LIMIT'] = $options['LIMIT'];
1247                 }
1248                 // but don't try to emulate for GROUP BY
1249                 if ( isset( $options['GROUP BY'] ) ) {
1250                         return $res;
1251                 }
1252
1253                 $res2 = parent::select( $table, $vars2, $conds, $fname, $options2,
1254                         $join_conds );
1255                 $obj = $this->fetchObject( $res2 );
1256                 $this->mNumRows = $obj->num_rows;
1257
1258                 return $res;
1259         }
1260
1261         /**
1262          * Handles ordering, grouping, and having options ('GROUP BY' => colname)
1263          * Has limited support for per-column options (colnum => 'DISTINCT')
1264          *
1265          * @private
1266          *
1267          * @param $options Associative array of options to be turned into
1268          *              an SQL query, valid keys are listed in the function.
1269          * @return Array
1270          */
1271         function makeSelectOptions( $options ) {
1272                 $preLimitTail = $postLimitTail = '';
1273                 $startOpts = '';
1274
1275                 $noKeyOptions = array();
1276                 foreach ( $options as $key => $option ) {
1277                         if ( is_numeric( $key ) ) {
1278                                 $noKeyOptions[$option] = true;
1279                         }
1280                 }
1281
1282                 if ( isset( $options['GROUP BY'] ) ) {
1283                         $preLimitTail .= " GROUP BY {$options['GROUP BY']}";
1284                 }
1285                 if ( isset( $options['HAVING'] ) ) {
1286                         $preLimitTail .= " HAVING {$options['HAVING']}";
1287                 }
1288                 if ( isset( $options['ORDER BY'] ) ) {
1289                         $preLimitTail .= " ORDER BY {$options['ORDER BY']}";
1290                 }
1291
1292                 if ( isset( $noKeyOptions['DISTINCT'] )
1293                         || isset( $noKeyOptions['DISTINCTROW'] ) )
1294                 {
1295                         $startOpts .= 'DISTINCT';
1296                 }
1297
1298                 return array( $startOpts, '', $preLimitTail, $postLimitTail );
1299         }
1300
1301         /**
1302          * Returns link to IBM DB2 free download
1303          * @return String: wikitext of a link to the server software's web site
1304          */
1305         public static function getSoftwareLink() {
1306                 return '[http://www.ibm.com/db2/express/ IBM DB2]';
1307         }
1308
1309         /**
1310          * Get search engine class. All subclasses of this
1311          * need to implement this if they wish to use searching.
1312          *
1313          * @return String
1314          */
1315         public function getSearchEngine() {
1316                 return 'SearchIBM_DB2';
1317         }
1318
1319         /**
1320          * Did the last database access fail because of deadlock?
1321          * @return Boolean
1322          */
1323         public function wasDeadlock() {
1324                 // get SQLSTATE
1325                 $err = $this->lastErrno();
1326                 switch( $err ) {
1327                         // This is literal port of the MySQL logic and may be wrong for DB2
1328                         case '40001':   // sql0911n, Deadlock or timeout, rollback
1329                         case '57011':   // sql0904n, Resource unavailable, no rollback
1330                         case '57033':   // sql0913n, Deadlock or timeout, no rollback
1331                         $this->installPrint( "In a deadlock because of SQLSTATE $err" );
1332                         return true;
1333                 }
1334                 return false;
1335         }
1336
1337         /**
1338          * Ping the server and try to reconnect if it there is no connection
1339          * The connection may be closed and reopened while this happens
1340          * @return Boolean: whether the connection exists
1341          */
1342         public function ping() {
1343                 // db2_ping() doesn't exist
1344                 // Emulate
1345                 $this->close();
1346                 $this->mConn = $this->openUncataloged( $this->mDBName, $this->mUser,
1347                         $this->mPassword, $this->mServer, $this->mPort );
1348
1349                 return false;
1350         }
1351         ######################################
1352         # Unimplemented and not applicable
1353         ######################################
1354         /**
1355          * Not implemented
1356          * @return string ''
1357          */
1358         public function getStatus( $which = '%' ) {
1359                 $this->installPrint( 'Not implemented for DB2: getStatus()' );
1360                 return '';
1361         }
1362         /**
1363          * Not implemented
1364          * @return string $sql
1365          */
1366         public function limitResultForUpdate( $sql, $num ) {
1367                 $this->installPrint( 'Not implemented for DB2: limitResultForUpdate()' );
1368                 return $sql;
1369         }
1370
1371         /**
1372          * Only useful with fake prepare like in base Database class
1373          * @return      string
1374          */
1375         public function fillPreparedArg( $matches ) {
1376                 $this->installPrint( 'Not useful for DB2: fillPreparedArg()' );
1377                 return '';
1378         }
1379
1380         ######################################
1381         # Reflection
1382         ######################################
1383
1384         /**
1385          * Returns information about an index
1386          * If errors are explicitly ignored, returns NULL on failure
1387          * @param $table String: table name
1388          * @param $index String: index name
1389          * @param $fname String: function name for logging and profiling
1390          * @return Object query row in object form
1391          */
1392         public function indexInfo( $table, $index,
1393                 $fname = 'DatabaseIbm_db2::indexExists' )
1394         {
1395                 $table = $this->tableName( $table );
1396                 $sql = <<<SQL
1397 SELECT name as indexname
1398 FROM sysibm.sysindexes si
1399 WHERE si.name='$index' AND si.tbname='$table'
1400 AND sc.tbcreator='$this->mSchema'
1401 SQL;
1402                 $res = $this->query( $sql, $fname );
1403                 if ( !$res ) {
1404                         return null;
1405                 }
1406                 $row = $this->fetchObject( $res );
1407                 if ( $row != null ) {
1408                         return $row;
1409                 } else {
1410                         return false;
1411                 }
1412         }
1413
1414         /**
1415          * Returns an information object on a table column
1416          * @param $table String: table name
1417          * @param $field String: column name
1418          * @return IBM_DB2Field
1419          */
1420         public function fieldInfo( $table, $field ) {
1421                 return IBM_DB2Field::fromText( $this, $table, $field );
1422         }
1423
1424         /**
1425          * db2_field_type() wrapper
1426          * @param $res Object: result of executed statement
1427          * @param $index Mixed: number or name of the column
1428          * @return String column type
1429          */
1430         public function fieldType( $res, $index ) {
1431                 if ( $res instanceof ResultWrapper ) {
1432                         $res = $res->result;
1433                 }
1434                 return db2_field_type( $res, $index );
1435         }
1436
1437         /**
1438          * Verifies that an index was created as unique
1439          * @param $table String: table name
1440          * @param $index String: index name
1441          * @param $fname function name for profiling
1442          * @return Bool
1443          */
1444         public function indexUnique ( $table, $index,
1445                 $fname = 'DatabaseIbm_db2::indexUnique' )
1446         {
1447                 $table = $this->tableName( $table );
1448                 $sql = <<<SQL
1449 SELECT si.name as indexname
1450 FROM sysibm.sysindexes si
1451 WHERE si.name='$index' AND si.tbname='$table'
1452 AND sc.tbcreator='$this->mSchema'
1453 AND si.uniquerule IN ( 'U', 'P' )
1454 SQL;
1455                 $res = $this->query( $sql, $fname );
1456                 if ( !$res ) {
1457                         return null;
1458                 }
1459                 if ( $this->fetchObject( $res ) ) {
1460                         return true;
1461                 }
1462                 return false;
1463
1464         }
1465
1466         /**
1467          * Returns the size of a text field, or -1 for "unlimited"
1468          * @param $table String: table name
1469          * @param $field String: column name
1470          * @return Integer: length or -1 for unlimited
1471          */
1472         public function textFieldSize( $table, $field ) {
1473                 $table = $this->tableName( $table );
1474                 $sql = <<<SQL
1475 SELECT length as size
1476 FROM sysibm.syscolumns sc
1477 WHERE sc.name='$field' AND sc.tbname='$table'
1478 AND sc.tbcreator='$this->mSchema'
1479 SQL;
1480                 $res = $this->query( $sql );
1481                 $row = $this->fetchObject( $res );
1482                 $size = $row->size;
1483                 return $size;
1484         }
1485
1486         /**
1487          * DELETE where the condition is a join
1488          * @param $delTable String: deleting from this table
1489          * @param $joinTable String: using data from this table
1490          * @param $delVar String: variable in deleteable table
1491          * @param $joinVar String: variable in data table
1492          * @param $conds Array: conditionals for join table
1493          * @param $fname String: function name for profiling
1494          */
1495         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar,
1496                 $conds, $fname = "DatabaseIbm_db2::deleteJoin" )
1497         {
1498                 if ( !$conds ) {
1499                         throw new DBUnexpectedError( $this,
1500                                 'DatabaseIbm_db2::deleteJoin() called with empty $conds' );
1501                 }
1502
1503                 $delTable = $this->tableName( $delTable );
1504                 $joinTable = $this->tableName( $joinTable );
1505                 $sql = <<<SQL
1506 DELETE FROM $delTable
1507 WHERE $delVar IN (
1508   SELECT $joinVar FROM $joinTable
1509
1510 SQL;
1511                 if ( $conds != '*' ) {
1512                         $sql .= 'WHERE ' . $this->makeList( $conds, LIST_AND );
1513                 }
1514                 $sql .= ' )';
1515
1516                 $this->query( $sql, $fname );
1517         }
1518
1519         /**
1520          * Description is left as an exercise for the reader
1521          * @param $b Mixed: data to be encoded
1522          * @return IBM_DB2Blob
1523          */
1524         public function encodeBlob( $b ) {
1525                 return new IBM_DB2Blob( $b );
1526         }
1527
1528         /**
1529          * Description is left as an exercise for the reader
1530          * @param $b IBM_DB2Blob: data to be decoded
1531          * @return mixed
1532          */
1533         public function decodeBlob( $b ) {
1534                 return "$b";
1535         }
1536
1537         /**
1538          * Convert into a list of string being concatenated
1539          * @param $stringList Array: strings that need to be joined together
1540          *                    by the SQL engine
1541          * @return String: joined by the concatenation operator
1542          */
1543         public function buildConcat( $stringList ) {
1544                 // || is equivalent to CONCAT
1545                 // Sample query: VALUES 'foo' CONCAT 'bar' CONCAT 'baz'
1546                 return implode( ' || ', $stringList );
1547         }
1548
1549         /**
1550          * Generates the SQL required to convert a DB2 timestamp into a Unix epoch
1551          * @param $column String: name of timestamp column
1552          * @return String: SQL code
1553          */
1554         public function extractUnixEpoch( $column ) {
1555                 // TODO
1556                 // see SpecialAncientpages
1557         }
1558
1559         ######################################
1560         # Prepared statements
1561         ######################################
1562
1563         /**
1564          * Intended to be compatible with the PEAR::DB wrapper functions.
1565          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
1566          *
1567          * ? = scalar value, quoted as necessary
1568          * ! = raw SQL bit (a function for instance)
1569          * & = filename; reads the file and inserts as a blob
1570          *     (we don't use this though...)
1571          * @param $sql String: SQL statement with appropriate markers
1572          * @param $func String: Name of the function, for profiling
1573          * @return resource a prepared DB2 SQL statement
1574          */
1575         public function prepare( $sql, $func = 'DB2::prepare' ) {
1576                 $stmt = db2_prepare( $this->mConn, $sql, $this->mStmtOptions );
1577                 return $stmt;
1578         }
1579
1580         /**
1581          * Frees resources associated with a prepared statement
1582          * @return Boolean success or failure
1583          */
1584         public function freePrepared( $prepared ) {
1585                 return db2_free_stmt( $prepared );
1586         }
1587
1588         /**
1589          * Execute a prepared query with the various arguments
1590          * @param $prepared String: the prepared sql
1591          * @param $args Mixed: either an array here, or put scalars as varargs
1592          * @return Resource: results object
1593          */
1594         public function execute( $prepared, $args = null ) {
1595                 if( !is_array( $args ) ) {
1596                         # Pull the var args
1597                         $args = func_get_args();
1598                         array_shift( $args );
1599                 }
1600                 $res = db2_execute( $prepared, $args );
1601                 if ( !$res ) {
1602                         $this->installPrint( db2_stmt_errormsg() );
1603                 }
1604                 return $res;
1605         }
1606
1607         /**
1608          * Prepare & execute an SQL statement, quoting and inserting arguments
1609          * in the appropriate places.
1610          * @param $query String
1611          * @param $args ...
1612          */
1613         public function safeQuery( $query, $args = null ) {
1614                 // copied verbatim from Database.php
1615                 $prepared = $this->prepare( $query, 'DB2::safeQuery' );
1616                 if( !is_array( $args ) ) {
1617                         # Pull the var args
1618                         $args = func_get_args();
1619                         array_shift( $args );
1620                 }
1621                 $retval = $this->execute( $prepared, $args );
1622                 $this->freePrepared( $prepared );
1623                 return $retval;
1624         }
1625
1626         /**
1627          * For faking prepared SQL statements on DBs that don't support
1628          * it directly.
1629          * @param $preparedQuery String: a 'preparable' SQL statement
1630          * @param $args Array of arguments to fill it with
1631          * @return String: executable statement
1632          */
1633         public function fillPrepared( $preparedQuery, $args ) {
1634                 reset( $args );
1635                 $this->preparedArgs =& $args;
1636
1637                 foreach ( $args as $i => $arg ) {
1638                         db2_bind_param( $preparedQuery, $i+1, $args[$i] );
1639                 }
1640
1641                 return $preparedQuery;
1642         }
1643
1644         /**
1645          * Switches module between regular and install modes
1646          */
1647         public function setMode( $mode ) {
1648                 $old = $this->mMode;
1649                 $this->mMode = $mode;
1650                 return $old;
1651         }
1652
1653         /**
1654          * Bitwise negation of a column or value in SQL
1655          * Same as (~field) in C
1656          * @param $field String
1657          * @return String
1658          */
1659         function bitNot( $field ) {
1660                 // expecting bit-fields smaller than 4bytes
1661                 return "BITNOT( $field )";
1662         }
1663
1664         /**
1665          * Bitwise AND of two columns or values in SQL
1666          * Same as (fieldLeft & fieldRight) in C
1667          * @param $fieldLeft String
1668          * @param $fieldRight String
1669          * @return String
1670          */
1671         function bitAnd( $fieldLeft, $fieldRight ) {
1672                 return "BITAND( $fieldLeft, $fieldRight )";
1673         }
1674
1675         /**
1676          * Bitwise OR of two columns or values in SQL
1677          * Same as (fieldLeft | fieldRight) in C
1678          * @param $fieldLeft String
1679          * @param $fieldRight String
1680          * @return String
1681          */
1682         function bitOr( $fieldLeft, $fieldRight ) {
1683                 return "BITOR( $fieldLeft, $fieldRight )";
1684         }
1685 }
1686
1687 class IBM_DB2Helper {
1688         public static function makeArray( $maybeArray ) {
1689                 if ( !is_array( $maybeArray ) ) {
1690                         return array( $maybeArray );
1691                 }
1692
1693                 return $maybeArray;
1694         }
1695 }