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
 268                 global $wgOut, $wgDBmwschema;
 269                 # Can't get a reference if it hasn't been set yet
 270                 if ( !isset( $wgOut ) ) {
 271                         $wgOut = null;
 272                 }
 273                 $this->mFlags = DBO_TRX | $flags;
 274
 275                 if ( $schema == self::USE_GLOBAL ) {
 276                         $this->mSchema = $wgDBmwschema;
 277                 } else {
 278                         $this->mSchema = $schema;
 279                 }
 280
 281                 // configure the connection and statement objects
 282                 $this->setDB2Option( 'db2_attr_case', 'DB2_CASE_LOWER',
 283                         self::CONN_OPTION | self::STMT_OPTION );
 284                 $this->setDB2Option( 'deferred_prepare', 'DB2_DEFERRED_PREPARE_ON',
 285                         self::STMT_OPTION );
 286                 $this->setDB2Option( 'rowcount', 'DB2_ROWCOUNT_PREFETCH_ON',
 287                         self::STMT_OPTION );
 288
 289                 $this->open( $server, $user, $password, $dbName );
 290         }
 291
 292         /**
 293          * Enables options only if the ibm_db2 extension version supports them
 294          * @param $name String: name of the option in the options array
 295          * @param $const String: name of the constant holding the right option value
 296          * @param $type Integer: whether this is a Connection or Statement otion
 297          */
 298         private function setDB2Option( $name, $const, $type ) {
 299                 if ( defined( $const ) ) {
 300                         if ( $type & self::CONN_OPTION ) {
 301                                 $this->mConnOptions[$name] = constant( $const );
 302                         }
 303                         if ( $type & self::STMT_OPTION ) {
 304                                 $this->mStmtOptions[$name] = constant( $const );
 305                         }
 306                 } else {
 307                         $this->installPrint(
 308                                 "$const is not defined. ibm_db2 version is likely too low." );
 309                 }
 310         }
 311
 312         /**
 313          * Outputs debug information in the appropriate place
 314          * @param $string String: the relevant debug message
 315          */
 316         private function installPrint( $string ) {
 317                 wfDebug( "$string\n" );
 318                 if ( $this->mMode == self::INSTALL_MODE ) {
 319                         print "<li><pre>$string</pre></li>";
 320                         flush();
 321                 }
 322         }
 323
 324         /**
 325          * Opens a database connection and returns it
 326          * Closes any existing connection
 327          *
 328          * @param $server String: hostname
 329          * @param $user String
 330          * @param $password String
 331          * @param $dbName String: database name
 332          * @return a fresh connection
 333          */
 334         public function open( $server, $user, $password, $dbName ) {
 335                 // Load the port number
 336                 global $wgDBport;
 337                 wfProfileIn( __METHOD__ );
 338
 339                 // Load IBM DB2 driver if missing
 340                 wfDl( 'ibm_db2' );
 341
 342                 // Test for IBM DB2 support, to avoid suppressed fatal error
 343                 if ( !function_exists( 'db2_connect' ) ) {
 344                         $error = <<<ERROR
 345 DB2 functions missing, have you enabled the ibm_db2 extension for PHP?
 346
 347 ERROR;
 348                         $this->installPrint( $error );
 349                         $this->reportConnectionError( $error );
 350                 }
 351
 352                 if ( strlen( $user ) < 1 ) {
 353                         return null;
 354                 }
 355
 356                 // Close existing connection
 357                 $this->close();
 358                 // Cache conn info
 359                 $this->mServer = $server;
 360                 $this->mPort = $port = $wgDBport;
 361                 $this->mUser = $user;
 362                 $this->mPassword = $password;
 363                 $this->mDBname = $dbName;
 364
 365                 $this->openUncataloged( $dbName, $user, $password, $server, $port );
 366
 367                 // Apply connection config
 368                 db2_set_option( $this->mConn, $this->mConnOptions, 1 );
 369                 // Some MediaWiki code is still transaction-less (?).
 370                 // The strategy is to keep AutoCommit on for that code
 371                 //  but switch it off whenever a transaction is begun.
 372                 db2_autocommit( $this->mConn, DB2_AUTOCOMMIT_ON );
 373
 374                 if ( !$this->mConn ) {
 375                         $this->installPrint( "DB connection error\n" );
 376                         $this->installPrint(
 377                                 "Server: $server, Database: $dbName, User: $user, Password: "
 378                                 . substr( $password, 0, 3 ) . "...\n" );
 379                         $this->installPrint( $this->lastError() . "\n" );
 380                         return null;
 381                 }
 382
 383                 $this->mOpened = true;
 384                 $this->applySchema();
 385
 386                 wfProfileOut( __METHOD__ );
 387                 return $this->mConn;
 388         }
 389
 390         /**
 391          * Opens a cataloged database connection, sets mConn
 392          */
 393         protected function openCataloged( $dbName, $user, $password ) {
 394                 @$this->mConn = db2_pconnect( $dbName, $user, $password );
 395         }
 396
 397         /**
 398          * Opens an uncataloged database connection, sets mConn
 399          */
 400         protected function openUncataloged( $dbName, $user, $password, $server, $port )
 401         {
 402                 $str = "DRIVER={IBM DB2 ODBC DRIVER};";
 403                 $str .= "DATABASE=$dbName;";
 404                 $str .= "HOSTNAME=$server;";
 405                 // port was formerly validated to not be 0
 406                 $str .= "PORT=$port;";
 407                 $str .= "PROTOCOL=TCPIP;";
 408                 $str .= "UID=$user;";
 409                 $str .= "PWD=$password;";
 410
 411                 @$this->mConn = db2_pconnect( $str, $user, $password );
 412         }
 413
 414         /**
 415          * Closes a database connection, if it is open
 416          * Returns success, true if already closed
 417          */
 418         public function close() {
 419                 $this->mOpened = false;
 420                 if ( $this->mConn ) {
 421                         if ( $this->trxLevel() > 0 ) {
 422                                 $this->commit();
 423                         }
 424                         return db2_close( $this->mConn );
 425                 } else {
 426                         return true;
 427                 }
 428         }
 429
 430         /**
 431          * Retrieves the most current database error
 432          * Forces a database rollback
 433          */
 434         public function lastError() {
 435                 $connerr = db2_conn_errormsg();
 436                 if ( $connerr ) {
 437                         //$this->rollback();
 438                         return $connerr;
 439                 }
 440                 $stmterr = db2_stmt_errormsg();
 441                 if ( $stmterr ) {
 442                         //$this->rollback();
 443                         return $stmterr;
 444                 }
 445
 446                 return false;
 447         }
 448
 449         /**
 450          * Get the last error number
 451          * Return 0 if no error
 452          * @return integer
 453          */
 454         public function lastErrno() {
 455                 $connerr = db2_conn_error();
 456                 if ( $connerr ) {
 457                         return $connerr;
 458                 }
 459                 $stmterr = db2_stmt_error();
 460                 if ( $stmterr ) {
 461                         return $stmterr;
 462                 }
 463                 return 0;
 464         }
 465
 466         /**
 467          * Is a database connection open?
 468          * @return
 469          */
 470         public function isOpen() { return $this->mOpened; }
 471
 472         /**
 473          * The DBMS-dependent part of query()
 474          * @param  $sql String: SQL query.
 475          * @return object Result object for fetch functions or false on failure
 476          * @access private
 477          */
 478         /*private*/
 479         public function doQuery( $sql ) {
 480                 $this->applySchema();
 481
 482                 $ret = db2_exec( $this->mConn, $sql, $this->mStmtOptions );
 483                 if( $ret == false ) {
 484                         $error = db2_stmt_errormsg();
 485                         $this->installPrint( "<pre>$sql</pre>" );
 486                         $this->installPrint( $error );
 487                         throw new DBUnexpectedError( $this, 'SQL error: '
 488                                 . htmlspecialchars( $error ) );
 489                 }
 490                 $this->mLastResult = $ret;
 491                 $this->mAffectedRows = null; // Not calculated until asked for
 492                 return $ret;
 493         }
 494
 495         /**
 496          * @return string Version information from the database
 497          */
 498         public function getServerVersion() {
 499                 $info = db2_server_info( $this->mConn );
 500                 return $info->DBMS_VER;
 501         }
 502
 503         /**
 504          * Queries whether a given table exists
 505          * @return boolean
 506          */
 507         public function tableExists( $table ) {
 508                 $schema = $this->mSchema;
 509                 $sql = <<< EOF
 510 SELECT COUNT( * ) FROM SYSIBM.SYSTABLES ST
 511 WHERE ST.NAME = '$table' AND ST.CREATOR = '$schema'
 512 EOF;
 513                 $res = $this->query( $sql );
 514                 if ( !$res ) {
 515                         return false;
 516                 }
 517
 518                 // If the table exists, there should be one of it
 519                 @$row = $this->fetchRow( $res );
 520                 $count = $row[0];
 521                 if ( $count == '1' || $count == 1 ) {
 522                         return true;
 523                 }
 524
 525                 return false;
 526         }
 527
 528         /**
 529          * Fetch the next row from the given result object, in object form.
 530          * Fields can be retrieved with $row->fieldname, with fields acting like
 531          * member variables.
 532          *
 533          * @param $res SQL result object as returned from Database::query(), etc.
 534          * @return DB2 row object
 535          * @throws DBUnexpectedError Thrown if the database returns an error
 536          */
 537         public function fetchObject( $res ) {
 538                 if ( $res instanceof ResultWrapper ) {
 539                         $res = $res->result;
 540                 }
 541                 @$row = db2_fetch_object( $res );
 542                 if( $this->lastErrno() ) {
 543                         throw new DBUnexpectedError( $this, 'Error in fetchObject(): '
 544                                 . htmlspecialchars( $this->lastError() ) );
 545                 }
 546                 return $row;
 547         }
 548
 549         /**
 550          * Fetch the next row from the given result object, in associative array
 551          * form. Fields are retrieved with $row['fieldname'].
 552          *
 553          * @param $res SQL result object as returned from Database::query(), etc.
 554          * @return DB2 row object
 555          * @throws DBUnexpectedError Thrown if the database returns an error
 556          */
 557         public function fetchRow( $res ) {
 558                 if ( $res instanceof ResultWrapper ) {
 559                         $res = $res->result;
 560                 }
 561                 @$row = db2_fetch_array( $res );
 562                 if ( $this->lastErrno() ) {
 563                         throw new DBUnexpectedError( $this, 'Error in fetchRow(): '
 564                                 . htmlspecialchars( $this->lastError() ) );
 565                 }
 566                 return $row;
 567         }
 568
 569         /**
 570          * Create tables, stored procedures, and so on
 571          */
 572         public function setup_database() {
 573                 try {
 574                         // TODO: switch to root login if available
 575
 576                         // Switch into the correct namespace
 577                         $this->applySchema();
 578                         $this->begin();
 579
 580                         $res = $this->sourceFile( "../maintenance/ibm_db2/tables.sql" );
 581                         if ( $res !== true ) {
 582                                 print ' <b>FAILED</b>: ' . htmlspecialchars( $res ) . '</li>';
 583                         } else {
 584                                 print ' done</li>';
 585                         }
 586                         $res = $this->sourceFile( "../maintenance/ibm_db2/foreignkeys.sql" );
 587                         if ( $res !== true ) {
 588                                 print ' <b>FAILED</b>: ' . htmlspecialchars( $res ) . '</li>';
 589                         } else {
 590                                 print '<li>Foreign keys done</li>';
 591                         }
 592
 593                         // TODO: populate interwiki links
 594
 595                         if ( $this->lastError() ) {
 596                                 $this->installPrint(
 597                                         'Errors encountered during table creation -- rolled back' );
 598                                 $this->installPrint( 'Please install again' );
 599                                 $this->rollback();
 600                         } else {
 601                                 $this->commit();
 602                         }
 603                 } catch ( MWException $mwe ) {
 604                         print "<br><pre>$mwe</pre><br>";
 605                 }
 606         }
 607
 608         /**
 609          * Escapes strings
 610          * Doesn't escape numbers
 611          *
 612          * @param $s String: string to escape
 613          * @return escaped string
 614          */
 615         public function addQuotes( $s ) {
 616                 //$this->installPrint( "DB2::addQuotes( $s )\n" );
 617                 if ( is_null( $s ) ) {
 618                         return 'NULL';
 619                 } elseif ( $s instanceof Blob ) {
 620                         return "'" . $s->fetch( $s ) . "'";
 621                 } elseif ( $s instanceof IBM_DB2Blob ) {
 622                         return "'" . $this->decodeBlob( $s ) . "'";
 623                 }
 624                 $s = $this->strencode( $s );
 625                 if ( is_numeric( $s ) ) {
 626                         return $s;
 627                 } else {
 628                         return "'$s'";
 629                 }
 630         }
 631
 632         /**
 633          * Verifies that a DB2 column/field type is numeric
 634          *
 635          * @param $type String: DB2 column type
 636          * @return Boolean: true if numeric
 637          */
 638         public function is_numeric_type( $type ) {
 639                 switch ( strtoupper( $type ) ) {
 640                         case 'SMALLINT':
 641                         case 'INTEGER':
 642                         case 'INT':
 643                         case 'BIGINT':
 644                         case 'DECIMAL':
 645                         case 'REAL':
 646                         case 'DOUBLE':
 647                         case 'DECFLOAT':
 648                                 return true;
 649                 }
 650                 return false;
 651         }
 652
 653         /**
 654          * Alias for addQuotes()
 655          * @param $s String: string to escape
 656          * @return escaped string
 657          */
 658         public function strencode( $s ) {
 659                 // Bloody useless function
 660                 //  Prepends backslashes to \x00, \n, \r, \, ', " and \x1a.
 661                 //  But also necessary
 662                 $s = db2_escape_string( $s );
 663                 // Wide characters are evil -- some of them look like '
 664                 $s = utf8_encode( $s );
 665                 // Fix its stupidity
 666                 $from = array(  "\\\\", "\\'",  '\\n',  '\\t',  '\\"',  '\\r' );
 667                 $to = array(            "\\",           "''",           "\n",           "\t",           '"',            "\r" );
 668                 $s = str_replace( $from, $to, $s ); // DB2 expects '', not \' escaping
 669                 return $s;
 670         }
 671
 672         /**
 673          * Switch into the database schema
 674          */
 675         protected function applySchema() {
 676                 if ( !( $this->mSchemaSet ) ) {
 677                         $this->mSchemaSet = true;
 678                         $this->begin();
 679                         $this->doQuery( "SET SCHEMA = $this->mSchema" );
 680                         $this->commit();
 681                 }
 682         }
 683
 684         /**
 685          * Start a transaction (mandatory)
 686          */
 687         public function begin( $fname = 'DatabaseIbm_db2::begin' ) {
 688                 // BEGIN is implicit for DB2
 689                 // However, it requires that AutoCommit be off.
 690
 691                 // Some MediaWiki code is still transaction-less (?).
 692                 // The strategy is to keep AutoCommit on for that code
 693                 //  but switch it off whenever a transaction is begun.
 694                 db2_autocommit( $this->mConn, DB2_AUTOCOMMIT_OFF );
 695
 696                 $this->mTrxLevel = 1;
 697         }
 698
 699         /**
 700          * End a transaction
 701          * Must have a preceding begin()
 702          */
 703         public function commit( $fname = 'DatabaseIbm_db2::commit' ) {
 704                 db2_commit( $this->mConn );
 705
 706                 // Some MediaWiki code is still transaction-less (?).
 707                 // The strategy is to keep AutoCommit on for that code
 708                 //  but switch it off whenever a transaction is begun.
 709                 db2_autocommit( $this->mConn, DB2_AUTOCOMMIT_ON );
 710
 711                 $this->mTrxLevel = 0;
 712         }
 713
 714         /**
 715          * Cancel a transaction
 716          */
 717         public function rollback( $fname = 'DatabaseIbm_db2::rollback' ) {
 718                 db2_rollback( $this->mConn );
 719                 // turn auto-commit back on
 720                 // not sure if this is appropriate
 721                 db2_autocommit( $this->mConn, DB2_AUTOCOMMIT_ON );
 722                 $this->mTrxLevel = 0;
 723         }
 724
 725         /**
 726          * Makes an encoded list of strings from an array
 727          * $mode:
 728          *   LIST_COMMA         - comma separated, no field names
 729          *   LIST_AND           - ANDed WHERE clause (without the WHERE)
 730          *   LIST_OR            - ORed WHERE clause (without the WHERE)
 731          *   LIST_SET           - comma separated with field names, like a SET clause
 732          *   LIST_NAMES         - comma separated field names
 733          *   LIST_SET_PREPARED  - like LIST_SET, except with ? tokens as values
 734          */
 735         function makeList( $a, $mode = LIST_COMMA ) {
 736                 if ( !is_array( $a ) ) {
 737                         throw new DBUnexpectedError( $this,
 738                                 'DatabaseIbm_db2::makeList called with incorrect parameters' );
 739                 }
 740
 741                 // if this is for a prepared UPDATE statement
 742                 // (this should be promoted to the parent class
 743                 //  once other databases use prepared statements)
 744                 if ( $mode == LIST_SET_PREPARED ) {
 745                         $first = true;
 746                         $list = '';
 747                         foreach ( $a as $field => $value ) {
 748                                 if ( !$first ) {
 749                                         $list .= ", $field = ?";
 750                                 } else {
 751                                         $list .= "$field = ?";
 752                                         $first = false;
 753                                 }
 754                         }
 755                         $list .= '';
 756
 757                         return $list;
 758                 }
 759
 760                 // otherwise, call the usual function
 761                 return parent::makeList( $a, $mode );
 762         }
 763
 764         /**
 765          * Construct a LIMIT query with optional offset
 766          * This is used for query pages
 767          *
 768          * @param $sql string SQL query we will append the limit too
 769          * @param $limit integer the SQL limit
 770          * @param $offset integer the SQL offset (default false)
 771          */
 772         public function limitResult( $sql, $limit, $offset=false ) {
 773                 if( !is_numeric( $limit ) ) {
 774                         throw new DBUnexpectedError( $this,
 775                                 "Invalid non-numeric limit passed to limitResult()\n" );
 776                 }
 777                 if( $offset ) {
 778                         if ( stripos( $sql, 'where' ) === false ) {
 779                                 return "$sql AND ( ROWNUM BETWEEN $offset AND $offset+$limit )";
 780                         } else {
 781                                 return "$sql WHERE ( ROWNUM BETWEEN $offset AND $offset+$limit )";
 782                         }
 783                 }
 784                 return "$sql FETCH FIRST $limit ROWS ONLY ";
 785         }
 786
 787         /**
 788          * Handle reserved keyword replacement in table names
 789          *
 790          * @param $name Object
 791          * @return String
 792          */
 793         public function tableName( $name ) {
 794                 // we want maximum compatibility with MySQL schema
 795                 return $name;
 796         }
 797
 798         /**
 799          * Generates a timestamp in an insertable format
 800          *
 801          * @param $ts timestamp
 802          * @return String: timestamp value
 803          */
 804         public function timestamp( $ts = 0 ) {
 805                 // TS_MW cannot be easily distinguished from an integer
 806                 return wfTimestamp( TS_DB2, $ts );
 807         }
 808
 809         /**
 810          * Return the next in a sequence, save the value for retrieval via insertId()
 811          * @param $seqName String: name of a defined sequence in the database
 812          * @return next value in that sequence
 813          */
 814         public function nextSequenceValue( $seqName ) {
 815                 // Not using sequences in the primary schema to allow for easier migration
 816                 //  from MySQL
 817                 // Emulating MySQL behaviour of using NULL to signal that sequences
 818                 // aren't used
 819                 /*
 820                 $safeseq = preg_replace( "/'/", "''", $seqName );
 821                 $res = $this->query( "VALUES NEXTVAL FOR $safeseq" );
 822                 $row = $this->fetchRow( $res );
 823                 $this->mInsertId = $row[0];
 824                 return $this->mInsertId;
 825                 */
 826                 return null;
 827         }
 828
 829         /**
 830          * This must be called after nextSequenceVal
 831          * @return Last sequence value used as a primary key
 832          */
 833         public function insertId() {
 834                 return $this->mInsertId;
 835         }
 836
 837         /**
 838          * Updates the mInsertId property with the value of the last insert
 839          *  into a generated column
 840          *
 841          * @param $table      String: sanitized table name
 842          * @param $primaryKey Mixed: string name of the primary key
 843          * @param $stmt       Resource: prepared statement resource
 844          *  of the SELECT primary_key FROM FINAL TABLE ( INSERT ... ) form
 845          */
 846         private function calcInsertId( $table, $primaryKey, $stmt ) {
 847                 if ( $primaryKey ) {
 848                         $this->mInsertId = db2_last_insert_id( $this->mConn );
 849                 }
 850         }
 851
 852         /**
 853          * INSERT wrapper, inserts an array into a table
 854          *
 855          * $args may be a single associative array, or an array of arrays
 856          *  with numeric keys, for multi-row insert
 857          *
 858          * @param $table   String: Name of the table to insert to.
 859          * @param $args    Array: Items to insert into the table.
 860          * @param $fname   String: Name of the function, for profiling
 861          * @param $options String or Array. Valid options: IGNORE
 862          *
 863          * @return bool Success of insert operation. IGNORE always returns true.
 864          */
 865         public function insert( $table, $args, $fname = 'DatabaseIbm_db2::insert',
 866                 $options = array() )
 867         {
 868                 if ( !count( $args ) ) {
 869                         return true;
 870                 }
 871                 // get database-specific table name (not used)
 872                 $table = $this->tableName( $table );
 873                 // format options as an array
 874                 $options = IBM_DB2Helper::makeArray( $options );
 875                 // format args as an array of arrays
 876                 if ( !( isset( $args[0] ) && is_array( $args[0] ) ) ) {
 877                         $args = array( $args );
 878                 }
 879
 880                 // prevent insertion of NULL into primary key columns
 881                 list( $args, $primaryKeys ) = $this->removeNullPrimaryKeys( $table, $args );
 882                 // if there's only one primary key
 883                 // we'll be able to read its value after insertion
 884                 $primaryKey = false;
 885                 if ( count( $primaryKeys ) == 1 ) {
 886                         $primaryKey = $primaryKeys[0];
 887                 }
 888
 889                 // get column names
 890                 $keys = array_keys( $args[0] );
 891                 $key_count = count( $keys );
 892
 893                 // If IGNORE is set, we use savepoints to emulate mysql's behavior
 894                 $ignore = in_array( 'IGNORE', $options ) ? 'mw' : '';
 895
 896                 // assume success
 897                 $res = true;
 898                 // If we are not in a transaction, we need to be for savepoint trickery
 899                 if ( !$this->mTrxLevel ) {
 900                         $this->begin();
 901                 }
 902
 903                 $sql = "INSERT INTO $table ( " . implode( ',', $keys ) . ' ) VALUES ';
 904                 if ( $key_count == 1 ) {
 905                         $sql .= '( ? )';
 906                 } else {
 907                         $sql .= '( ?' . str_repeat( ',?', $key_count-1 ) . ' )';
 908                 }
 909                 //$this->installPrint( "Preparing the following SQL:" );
 910                 //$this->installPrint( "$sql" );
 911                 //$this->installPrint( print_r( $args, true ));
 912                 $stmt = $this->prepare( $sql );
 913
 914                 // start a transaction/enter transaction mode
 915                 $this->begin();
 916
 917                 if ( !$ignore ) {
 918                         //$first = true;
 919                         foreach ( $args as $row ) {
 920                                 //$this->installPrint( "Inserting " . print_r( $row, true ));
 921                                 // insert each row into the database
 922                                 $res = $res & $this->execute( $stmt, $row );
 923                                 if ( !$res ) {
 924                                         $this->installPrint( 'Last error:' );
 925                                         $this->installPrint( $this->lastError() );
 926                                 }
 927                                 // get the last inserted value into a generated column
 928                                 $this->calcInsertId( $table, $primaryKey, $stmt );
 929                         }
 930                 } else {
 931                         $olde = error_reporting( 0 );
 932                         // For future use, we may want to track the number of actual inserts
 933                         // Right now, insert (all writes) simply return true/false
 934                         $numrowsinserted = 0;
 935
 936                         // always return true
 937                         $res = true;
 938
 939                         foreach ( $args as $row ) {
 940                                 $overhead = "SAVEPOINT $ignore ON ROLLBACK RETAIN CURSORS";
 941                                 db2_exec( $this->mConn, $overhead, $this->mStmtOptions );
 942
 943                                 $this->execute( $stmt, $row );
 944
 945                                 if ( !$res2 ) {
 946                                         $this->installPrint( 'Last error:' );
 947                                         $this->installPrint( $this->lastError() );
 948                                 }
 949                                 // get the last inserted value into a generated column
 950                                 $this->calcInsertId( $table, $primaryKey, $stmt );
 951
 952                                 $errNum = $this->lastErrno();
 953                                 if ( $errNum ) {
 954                                         db2_exec( $this->mConn, "ROLLBACK TO SAVEPOINT $ignore",
 955                                                 $this->mStmtOptions );
 956                                 } else {
 957                                         db2_exec( $this->mConn, "RELEASE SAVEPOINT $ignore",
 958                                                 $this->mStmtOptions );
 959                                         $numrowsinserted++;
 960                                 }
 961                         }
 962
 963                         $olde = error_reporting( $olde );
 964                         // Set the affected row count for the whole operation
 965                         $this->mAffectedRows = $numrowsinserted;
 966                 }
 967                 // commit either way
 968                 $this->commit();
 969                 $this->freePrepared( $stmt );
 970
 971                 return $res;
 972         }
 973
 974         /**
 975          * Given a table name and a hash of columns with values
 976          * Removes primary key columns from the hash where the value is NULL
 977          *
 978          * @param $table String: name of the table
 979          * @param $args Array of hashes of column names with values
 980          * @return Array: tuple( filtered array of columns, array of primary keys )
 981          */
 982         private function removeNullPrimaryKeys( $table, $args ) {
 983                 $schema = $this->mSchema;
 984                 // find out the primary keys
 985                 $keyres = db2_primary_keys( $this->mConn, null, strtoupper( $schema ),
 986                         strtoupper( $table )
 987                 );
 988                 $keys = array();
 989                 for (
 990                         $row = $this->fetchObject( $keyres );
 991                         $row != null;
 992                         $row = $this->fetchObject( $keyres )
 993                 )
 994                 {
 995                         $keys[] = strtolower( $row->column_name );
 996                 }
 997                 // remove primary keys
 998                 foreach ( $args as $ai => $row ) {
 999                         foreach ( $keys as $key ) {
1000                                 if ( $row[$key] == null ) {
1001                                         unset( $row[$key] );
1002                                 }
1003                         }
1004                         $args[$ai] = $row;
1005                 }
1006                 // return modified hash
1007                 return array( $args, $keys );
1008         }
1009
1010         /**
1011          * UPDATE wrapper, takes a condition array and a SET array
1012          *
1013          * @param $table  String: The table to UPDATE
1014          * @param $values An array of values to SET
1015          * @param $conds  An array of conditions ( WHERE ). Use '*' to update all rows.
1016          * @param $fname  String: The Class::Function calling this function
1017          *                ( for the log )
1018          * @param $options An array of UPDATE options, can be one or
1019          *                 more of IGNORE, LOW_PRIORITY
1020          * @return Boolean
1021          */
1022         public function update( $table, $values, $conds, $fname = 'DatabaseIbm_db2::update',
1023                 $options = array() )
1024         {
1025                 $table = $this->tableName( $table );
1026                 $opts = $this->makeUpdateOptions( $options );
1027                 $sql = "UPDATE $opts $table SET "
1028                         . $this->makeList( $values, LIST_SET_PREPARED );
1029                 if ( $conds != '*' ) {
1030                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1031                 }
1032                 $stmt = $this->prepare( $sql );
1033                 $this->installPrint( 'UPDATE: ' . print_r( $values, true ) );
1034                 // assuming for now that an array with string keys will work
1035                 // if not, convert to simple array first
1036                 $result = $this->execute( $stmt, $values );
1037                 $this->freePrepared( $stmt );
1038
1039                 return $result;
1040         }
1041
1042         /**
1043          * DELETE query wrapper
1044          *
1045          * Use $conds == "*" to delete all rows
1046          */
1047         public function delete( $table, $conds, $fname = 'DatabaseIbm_db2::delete' ) {
1048                 if ( !$conds ) {
1049                         throw new DBUnexpectedError( $this,
1050                                 'DatabaseIbm_db2::delete() called with no conditions' );
1051                 }
1052                 $table = $this->tableName( $table );
1053                 $sql = "DELETE FROM $table";
1054                 if ( $conds != '*' ) {
1055                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1056                 }
1057                 $result = $this->query( $sql, $fname );
1058
1059                 return $result;
1060         }
1061
1062         /**
1063          * Returns the number of rows affected by the last query or 0
1064          * @return Integer: the number of rows affected by the last query
1065          */
1066         public function affectedRows() {
1067                 if ( !is_null( $this->mAffectedRows ) ) {
1068                         // Forced result for simulated queries
1069                         return $this->mAffectedRows;
1070                 }
1071                 if( empty( $this->mLastResult ) ) {
1072                         return 0;
1073                 }
1074                 return db2_num_rows( $this->mLastResult );
1075         }
1076
1077         /**
1078          * Simulates REPLACE with a DELETE followed by INSERT
1079          * @param $table Object
1080          * @param $uniqueIndexes Array consisting of indexes and arrays of indexes
1081          * @param $rows Array: rows to insert
1082          * @param $fname String: name of the function for profiling
1083          * @return nothing
1084          */
1085         function replace( $table, $uniqueIndexes, $rows,
1086                 $fname = 'DatabaseIbm_db2::replace' )
1087         {
1088                 $table = $this->tableName( $table );
1089
1090                 if ( count( $rows )==0 ) {
1091                         return;
1092                 }
1093
1094                 # Single row case
1095                 if ( !is_array( reset( $rows ) ) ) {
1096                         $rows = array( $rows );
1097                 }
1098
1099                 foreach( $rows as $row ) {
1100                         # Delete rows which collide
1101                         if ( $uniqueIndexes ) {
1102                                 $sql = "DELETE FROM $table WHERE ";
1103                                 $first = true;
1104                                 foreach ( $uniqueIndexes as $index ) {
1105                                         if ( $first ) {
1106                                                 $first = false;
1107                                                 $sql .= '( ';
1108                                         } else {
1109                                                 $sql .= ' ) OR ( ';
1110                                         }
1111                                         if ( is_array( $index ) ) {
1112                                                 $first2 = true;
1113                                                 foreach ( $index as $col ) {
1114                                                         if ( $first2 ) {
1115                                                                 $first2 = false;
1116                                                         } else {
1117                                                                 $sql .= ' AND ';
1118                                                         }
1119                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
1120                                                 }
1121                                         } else {
1122                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
1123                                         }
1124                                 }
1125                                 $sql .= ' )';
1126                                 $this->query( $sql, $fname );
1127                         }
1128
1129                         # Now insert the row
1130                         $sql = "INSERT INTO $table ( "
1131                                 . $this->makeList( array_keys( $row ), LIST_NAMES )
1132                                 .' ) VALUES ( ' . $this->makeList( $row, LIST_COMMA ) . ' )';
1133                         $this->query( $sql, $fname );
1134                 }
1135         }
1136
1137         /**
1138          * Returns the number of rows in the result set
1139          * Has to be called right after the corresponding select query
1140          * @param $res Object result set
1141          * @return Integer: number of rows
1142          */
1143         public function numRows( $res ) {
1144                 if ( $res instanceof ResultWrapper ) {
1145                         $res = $res->result;
1146                 }
1147                 if ( $this->mNumRows ) {
1148                         return $this->mNumRows;
1149                 } else {
1150                         return 0;
1151                 }
1152         }
1153
1154         /**
1155          * Moves the row pointer of the result set
1156          * @param $res Object: result set
1157          * @param $row Integer: row number
1158          * @return success or failure
1159          */
1160         public function dataSeek( $res, $row ) {
1161                 if ( $res instanceof ResultWrapper ) {
1162                         $res = $res->result;
1163                 }
1164                 return db2_fetch_row( $res, $row );
1165         }
1166
1167         ###
1168         # Fix notices in Block.php
1169         ###
1170
1171         /**
1172          * Frees memory associated with a statement resource
1173          * @param $res Object: statement resource to free
1174          * @return Boolean success or failure
1175          */
1176         public function freeResult( $res ) {
1177                 if ( $res instanceof ResultWrapper ) {
1178                         $res = $res->result;
1179                 }
1180                 if ( !@db2_free_result( $res ) ) {
1181                         throw new DBUnexpectedError( $this, "Unable to free DB2 result\n" );
1182                 }
1183         }
1184
1185         /**
1186          * Returns the number of columns in a resource
1187          * @param $res Object: statement resource
1188          * @return Number of fields/columns in resource
1189          */
1190         public function numFields( $res ) {
1191                 if ( $res instanceof ResultWrapper ) {
1192                         $res = $res->result;
1193                 }
1194                 return db2_num_fields( $res );
1195         }
1196
1197         /**
1198          * Returns the nth column name
1199          * @param $res Object: statement resource
1200          * @param $n Integer: Index of field or column
1201          * @return String name of nth column
1202          */
1203         public function fieldName( $res, $n ) {
1204                 if ( $res instanceof ResultWrapper ) {
1205                         $res = $res->result;
1206                 }
1207                 return db2_field_name( $res, $n );
1208         }
1209
1210         /**
1211          * SELECT wrapper
1212          *
1213          * @param $table   Array or string, table name(s) (prefix auto-added)
1214          * @param $vars    Array or string, field name(s) to be retrieved
1215          * @param $conds   Array or string, condition(s) for WHERE
1216          * @param $fname   String: calling function name (use __METHOD__)
1217          *                 for logs/profiling
1218          * @param $options Associative array of options
1219          *                 (e.g. array('GROUP BY' => 'page_title')),
1220          *                 see Database::makeSelectOptions code for list of
1221          *                 supported stuff
1222          * @param $join_conds Associative array of table join conditions (optional)
1223          *                    (e.g. array( 'page' => array('LEFT JOIN',
1224          *                    'page_latest=rev_id') )
1225          * @return Mixed: database result resource for fetch functions or false
1226          *                 on failure
1227          */
1228         public function select( $table, $vars, $conds = '', $fname = 'DatabaseIbm_db2::select', $options = array(), $join_conds = array() )
1229         {
1230                 $res = parent::select( $table, $vars, $conds, $fname, $options,
1231                         $join_conds );
1232
1233                 // We must adjust for offset
1234                 if ( isset( $options['LIMIT'] ) && isset ( $options['OFFSET'] ) ) {
1235                         $limit = $options['LIMIT'];
1236                         $offset = $options['OFFSET'];
1237                 }
1238
1239                 // DB2 does not have a proper num_rows() function yet, so we must emulate
1240                 // DB2 9.5.4 and the corresponding ibm_db2 driver will introduce
1241                 //  a working one
1242                 // TODO: Yay!
1243
1244                 // we want the count
1245                 $vars2 = array( 'count( * ) as num_rows' );
1246                 // respecting just the limit option
1247                 $options2 = array();
1248                 if ( isset( $options['LIMIT'] ) ) {
1249                         $options2['LIMIT'] = $options['LIMIT'];
1250                 }
1251                 // but don't try to emulate for GROUP BY
1252                 if ( isset( $options['GROUP BY'] ) ) {
1253                         return $res;
1254                 }
1255
1256                 $res2 = parent::select( $table, $vars2, $conds, $fname, $options2,
1257                         $join_conds );
1258                 $obj = $this->fetchObject( $res2 );
1259                 $this->mNumRows = $obj->num_rows;
1260
1261                 return $res;
1262         }
1263
1264         /**
1265          * Handles ordering, grouping, and having options ('GROUP BY' => colname)
1266          * Has limited support for per-column options (colnum => 'DISTINCT')
1267          *
1268          * @private
1269          *
1270          * @param $options Associative array of options to be turned into
1271          *              an SQL query, valid keys are listed in the function.
1272          * @return Array
1273          */
1274         function makeSelectOptions( $options ) {
1275                 $preLimitTail = $postLimitTail = '';
1276                 $startOpts = '';
1277
1278                 $noKeyOptions = array();
1279                 foreach ( $options as $key => $option ) {
1280                         if ( is_numeric( $key ) ) {
1281                                 $noKeyOptions[$option] = true;
1282                         }
1283                 }
1284
1285                 if ( isset( $options['GROUP BY'] ) ) {
1286                         $preLimitTail .= " GROUP BY {$options['GROUP BY']}";
1287                 }
1288                 if ( isset( $options['HAVING'] ) ) {
1289                         $preLimitTail .= " HAVING {$options['HAVING']}";
1290                 }
1291                 if ( isset( $options['ORDER BY'] ) ) {
1292                         $preLimitTail .= " ORDER BY {$options['ORDER BY']}";
1293                 }
1294
1295                 if ( isset( $noKeyOptions['DISTINCT'] )
1296                         || isset( $noKeyOptions['DISTINCTROW'] ) )
1297                 {
1298                         $startOpts .= 'DISTINCT';
1299                 }
1300
1301                 return array( $startOpts, '', $preLimitTail, $postLimitTail );
1302         }
1303
1304         /**
1305          * Returns link to IBM DB2 free download
1306          * @return String: wikitext of a link to the server software's web site
1307          */
1308         public static function getSoftwareLink() {
1309                 return '[http://www.ibm.com/db2/express/ IBM DB2]';
1310         }
1311
1312         /**
1313          * Get search engine class. All subclasses of this
1314          * need to implement this if they wish to use searching.
1315          *
1316          * @return String
1317          */
1318         public function getSearchEngine() {
1319                 return 'SearchIBM_DB2';
1320         }
1321
1322         /**
1323          * Did the last database access fail because of deadlock?
1324          * @return Boolean
1325          */
1326         public function wasDeadlock() {
1327                 // get SQLSTATE
1328                 $err = $this->lastErrno();
1329                 switch( $err ) {
1330                         // This is literal port of the MySQL logic and may be wrong for DB2
1331                         case '40001':   // sql0911n, Deadlock or timeout, rollback
1332                         case '57011':   // sql0904n, Resource unavailable, no rollback
1333                         case '57033':   // sql0913n, Deadlock or timeout, no rollback
1334                         $this->installPrint( "In a deadlock because of SQLSTATE $err" );
1335                         return true;
1336                 }
1337                 return false;
1338         }
1339
1340         /**
1341          * Ping the server and try to reconnect if it there is no connection
1342          * The connection may be closed and reopened while this happens
1343          * @return Boolean: whether the connection exists
1344          */
1345         public function ping() {
1346                 // db2_ping() doesn't exist
1347                 // Emulate
1348                 $this->close();
1349                 $this->mConn = $this->openUncataloged( $this->mDBName, $this->mUser,
1350                         $this->mPassword, $this->mServer, $this->mPort );
1351
1352                 return false;
1353         }
1354         ######################################
1355         # Unimplemented and not applicable
1356         ######################################
1357         /**
1358          * Not implemented
1359          * @return string ''
1360          */
1361         public function getStatus( $which = '%' ) {
1362                 $this->installPrint( 'Not implemented for DB2: getStatus()' );
1363                 return '';
1364         }
1365         /**
1366          * Not implemented
1367          * @return string $sql
1368          */
1369         public function limitResultForUpdate( $sql, $num ) {
1370                 $this->installPrint( 'Not implemented for DB2: limitResultForUpdate()' );
1371                 return $sql;
1372         }
1373
1374         /**
1375          * Only useful with fake prepare like in base Database class
1376          * @return      string
1377          */
1378         public function fillPreparedArg( $matches ) {
1379                 $this->installPrint( 'Not useful for DB2: fillPreparedArg()' );
1380                 return '';
1381         }
1382
1383         ######################################
1384         # Reflection
1385         ######################################
1386
1387         /**
1388          * Returns information about an index
1389          * If errors are explicitly ignored, returns NULL on failure
1390          * @param $table String: table name
1391          * @param $index String: index name
1392          * @param $fname String: function name for logging and profiling
1393          * @return Object query row in object form
1394          */
1395         public function indexInfo( $table, $index,
1396                 $fname = 'DatabaseIbm_db2::indexExists' )
1397         {
1398                 $table = $this->tableName( $table );
1399                 $sql = <<<SQL
1400 SELECT name as indexname
1401 FROM sysibm.sysindexes si
1402 WHERE si.name='$index' AND si.tbname='$table'
1403 AND sc.tbcreator='$this->mSchema'
1404 SQL;
1405                 $res = $this->query( $sql, $fname );
1406                 if ( !$res ) {
1407                         return null;
1408                 }
1409                 $row = $this->fetchObject( $res );
1410                 if ( $row != null ) {
1411                         return $row;
1412                 } else {
1413                         return false;
1414                 }
1415         }
1416
1417         /**
1418          * Returns an information object on a table column
1419          * @param $table String: table name
1420          * @param $field String: column name
1421          * @return IBM_DB2Field
1422          */
1423         public function fieldInfo( $table, $field ) {
1424                 return IBM_DB2Field::fromText( $this, $table, $field );
1425         }
1426
1427         /**
1428          * db2_field_type() wrapper
1429          * @param $res Object: result of executed statement
1430          * @param $index Mixed: number or name of the column
1431          * @return String column type
1432          */
1433         public function fieldType( $res, $index ) {
1434                 if ( $res instanceof ResultWrapper ) {
1435                         $res = $res->result;
1436                 }
1437                 return db2_field_type( $res, $index );
1438         }
1439
1440         /**
1441          * Verifies that an index was created as unique
1442          * @param $table String: table name
1443          * @param $index String: index name
1444          * @param $fname function name for profiling
1445          * @return Bool
1446          */
1447         public function indexUnique ( $table, $index,
1448                 $fname = 'DatabaseIbm_db2::indexUnique' )
1449         {
1450                 $table = $this->tableName( $table );
1451                 $sql = <<<SQL
1452 SELECT si.name as indexname
1453 FROM sysibm.sysindexes si
1454 WHERE si.name='$index' AND si.tbname='$table'
1455 AND sc.tbcreator='$this->mSchema'
1456 AND si.uniquerule IN ( 'U', 'P' )
1457 SQL;
1458                 $res = $this->query( $sql, $fname );
1459                 if ( !$res ) {
1460                         return null;
1461                 }
1462                 if ( $this->fetchObject( $res ) ) {
1463                         return true;
1464                 }
1465                 return false;
1466
1467         }
1468
1469         /**
1470          * Returns the size of a text field, or -1 for "unlimited"
1471          * @param $table String: table name
1472          * @param $field String: column name
1473          * @return Integer: length or -1 for unlimited
1474          */
1475         public function textFieldSize( $table, $field ) {
1476                 $table = $this->tableName( $table );
1477                 $sql = <<<SQL
1478 SELECT length as size
1479 FROM sysibm.syscolumns sc
1480 WHERE sc.name='$field' AND sc.tbname='$table'
1481 AND sc.tbcreator='$this->mSchema'
1482 SQL;
1483                 $res = $this->query( $sql );
1484                 $row = $this->fetchObject( $res );
1485                 $size = $row->size;
1486                 return $size;
1487         }
1488
1489         /**
1490          * DELETE where the condition is a join
1491          * @param $delTable String: deleting from this table
1492          * @param $joinTable String: using data from this table
1493          * @param $delVar String: variable in deleteable table
1494          * @param $joinVar String: variable in data table
1495          * @param $conds Array: conditionals for join table
1496          * @param $fname String: function name for profiling
1497          */
1498         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar,
1499                 $conds, $fname = "DatabaseIbm_db2::deleteJoin" )
1500         {
1501                 if ( !$conds ) {
1502                         throw new DBUnexpectedError( $this,
1503                                 'DatabaseIbm_db2::deleteJoin() called with empty $conds' );
1504                 }
1505
1506                 $delTable = $this->tableName( $delTable );
1507                 $joinTable = $this->tableName( $joinTable );
1508                 $sql = <<<SQL
1509 DELETE FROM $delTable
1510 WHERE $delVar IN (
1511   SELECT $joinVar FROM $joinTable
1512
1513 SQL;
1514                 if ( $conds != '*' ) {
1515                         $sql .= 'WHERE ' . $this->makeList( $conds, LIST_AND );
1516                 }
1517                 $sql .= ' )';
1518
1519                 $this->query( $sql, $fname );
1520         }
1521
1522         /**
1523          * Description is left as an exercise for the reader
1524          * @param $b Mixed: data to be encoded
1525          * @return IBM_DB2Blob
1526          */
1527         public function encodeBlob( $b ) {
1528                 return new IBM_DB2Blob( $b );
1529         }
1530
1531         /**
1532          * Description is left as an exercise for the reader
1533          * @param $b IBM_DB2Blob: data to be decoded
1534          * @return mixed
1535          */
1536         public function decodeBlob( $b ) {
1537                 return "$b";
1538         }
1539
1540         /**
1541          * Convert into a list of string being concatenated
1542          * @param $stringList Array: strings that need to be joined together
1543          *                    by the SQL engine
1544          * @return String: joined by the concatenation operator
1545          */
1546         public function buildConcat( $stringList ) {
1547                 // || is equivalent to CONCAT
1548                 // Sample query: VALUES 'foo' CONCAT 'bar' CONCAT 'baz'
1549                 return implode( ' || ', $stringList );
1550         }
1551
1552         /**
1553          * Generates the SQL required to convert a DB2 timestamp into a Unix epoch
1554          * @param $column String: name of timestamp column
1555          * @return String: SQL code
1556          */
1557         public function extractUnixEpoch( $column ) {
1558                 // TODO
1559                 // see SpecialAncientpages
1560         }
1561
1562         ######################################
1563         # Prepared statements
1564         ######################################
1565
1566         /**
1567          * Intended to be compatible with the PEAR::DB wrapper functions.
1568          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
1569          *
1570          * ? = scalar value, quoted as necessary
1571          * ! = raw SQL bit (a function for instance)
1572          * & = filename; reads the file and inserts as a blob
1573          *     (we don't use this though...)
1574          * @param $sql String: SQL statement with appropriate markers
1575          * @param $func String: Name of the function, for profiling
1576          * @return resource a prepared DB2 SQL statement
1577          */
1578         public function prepare( $sql, $func = 'DB2::prepare' ) {
1579                 $stmt = db2_prepare( $this->mConn, $sql, $this->mStmtOptions );
1580                 return $stmt;
1581         }
1582
1583         /**
1584          * Frees resources associated with a prepared statement
1585          * @return Boolean success or failure
1586          */
1587         public function freePrepared( $prepared ) {
1588                 return db2_free_stmt( $prepared );
1589         }
1590
1591         /**
1592          * Execute a prepared query with the various arguments
1593          * @param $prepared String: the prepared sql
1594          * @param $args Mixed: either an array here, or put scalars as varargs
1595          * @return Resource: results object
1596          */
1597         public function execute( $prepared, $args = null ) {
1598                 if( !is_array( $args ) ) {
1599                         # Pull the var args
1600                         $args = func_get_args();
1601                         array_shift( $args );
1602                 }
1603                 $res = db2_execute( $prepared, $args );
1604                 if ( !$res ) {
1605                         $this->installPrint( db2_stmt_errormsg() );
1606                 }
1607                 return $res;
1608         }
1609
1610         /**
1611          * Prepare & execute an SQL statement, quoting and inserting arguments
1612          * in the appropriate places.
1613          * @param $query String
1614          * @param $args ...
1615          */
1616         public function safeQuery( $query, $args = null ) {
1617                 // copied verbatim from Database.php
1618                 $prepared = $this->prepare( $query, 'DB2::safeQuery' );
1619                 if( !is_array( $args ) ) {
1620                         # Pull the var args
1621                         $args = func_get_args();
1622                         array_shift( $args );
1623                 }
1624                 $retval = $this->execute( $prepared, $args );
1625                 $this->freePrepared( $prepared );
1626                 return $retval;
1627         }
1628
1629         /**
1630          * For faking prepared SQL statements on DBs that don't support
1631          * it directly.
1632          * @param $preparedQuery String: a 'preparable' SQL statement
1633          * @param $args Array of arguments to fill it with
1634          * @return String: executable statement
1635          */
1636         public function fillPrepared( $preparedQuery, $args ) {
1637                 reset( $args );
1638                 $this->preparedArgs =& $args;
1639
1640                 foreach ( $args as $i => $arg ) {
1641                         db2_bind_param( $preparedQuery, $i+1, $args[$i] );
1642                 }
1643
1644                 return $preparedQuery;
1645         }
1646
1647         /**
1648          * Switches module between regular and install modes
1649          */
1650         public function setMode( $mode ) {
1651                 $old = $this->mMode;
1652                 $this->mMode = $mode;
1653                 return $old;
1654         }
1655
1656         /**
1657          * Bitwise negation of a column or value in SQL
1658          * Same as (~field) in C
1659          * @param $field String
1660          * @return String
1661          */
1662         function bitNot( $field ) {
1663                 // expecting bit-fields smaller than 4bytes
1664                 return "BITNOT( $field )";
1665         }
1666
1667         /**
1668          * Bitwise AND of two columns or values in SQL
1669          * Same as (fieldLeft & fieldRight) in C
1670          * @param $fieldLeft String
1671          * @param $fieldRight String
1672          * @return String
1673          */
1674         function bitAnd( $fieldLeft, $fieldRight ) {
1675                 return "BITAND( $fieldLeft, $fieldRight )";
1676         }
1677
1678         /**
1679          * Bitwise OR of two columns or values in SQL
1680          * Same as (fieldLeft | fieldRight) in C
1681          * @param $fieldLeft String
1682          * @param $fieldRight String
1683          * @return String
1684          */
1685         function bitOr( $fieldLeft, $fieldRight ) {
1686                 return "BITOR( $fieldLeft, $fieldRight )";
1687         }
1688 }
1689
1690 class IBM_DB2Helper {
1691         public static function makeArray( $maybeArray ) {
1692                 if ( !is_array( $maybeArray ) ) {
1693                         return array( $maybeArray );
1694                 }
1695
1696                 return $maybeArray;
1697         }
1698 }