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 $mOut, $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 DatabaseIbm_db2( $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->mOut =& $wgOut;
 274                 $this->mFlags = DBO_TRX | $flags;
 275
 276                 if ( $schema == self::USE_GLOBAL ) {
 277                         $this->mSchema = $wgDBmwschema;
 278                 } else {
 279                         $this->mSchema = $schema;
 280                 }
 281
 282                 // configure the connection and statement objects
 283                 $this->setDB2Option( 'db2_attr_case', 'DB2_CASE_LOWER',
 284                         self::CONN_OPTION | self::STMT_OPTION );
 285                 $this->setDB2Option( 'deferred_prepare', 'DB2_DEFERRED_PREPARE_ON',
 286                         self::STMT_OPTION );
 287                 $this->setDB2Option( 'rowcount', 'DB2_ROWCOUNT_PREFETCH_ON',
 288                         self::STMT_OPTION );
 289
 290                 $this->open( $server, $user, $password, $dbName );
 291         }
 292
 293         /**
 294          * Enables options only if the ibm_db2 extension version supports them
 295          * @param $name String: name of the option in the options array
 296          * @param $const String: name of the constant holding the right option value
 297          * @param $type Integer: whether this is a Connection or Statement otion
 298          */
 299         private function setDB2Option( $name, $const, $type ) {
 300                 if ( defined( $const ) ) {
 301                         if ( $type & self::CONN_OPTION ) {
 302                                 $this->mConnOptions[$name] = constant( $const );
 303                         }
 304                         if ( $type & self::STMT_OPTION ) {
 305                                 $this->mStmtOptions[$name] = constant( $const );
 306                         }
 307                 } else {
 308                         $this->installPrint(
 309                                 "$const is not defined. ibm_db2 version is likely too low." );
 310                 }
 311         }
 312
 313         /**
 314          * Outputs debug information in the appropriate place
 315          * @param $string String: the relevant debug message
 316          */
 317         private function installPrint( $string ) {
 318                 wfDebug( "$string\n" );
 319                 if ( $this->mMode == self::INSTALL_MODE ) {
 320                         print "<li><pre>$string</pre></li>";
 321                         flush();
 322                 }
 323         }
 324
 325         /**
 326          * Opens a database connection and returns it
 327          * Closes any existing connection
 328          *
 329          * @param $server String: hostname
 330          * @param $user String
 331          * @param $password String
 332          * @param $dbName String: database name
 333          * @return a fresh connection
 334          */
 335         public function open( $server, $user, $password, $dbName ) {
 336                 // Load the port number
 337                 global $wgDBport;
 338                 wfProfileIn( __METHOD__ );
 339
 340                 // Load IBM DB2 driver if missing
 341                 wfDl( 'ibm_db2' );
 342
 343                 // Test for IBM DB2 support, to avoid suppressed fatal error
 344                 if ( !function_exists( 'db2_connect' ) ) {
 345                         $error = <<<ERROR
 346 DB2 functions missing, have you enabled the ibm_db2 extension for PHP?
 347
 348 ERROR;
 349                         $this->installPrint( $error );
 350                         $this->reportConnectionError( $error );
 351                 }
 352
 353                 if ( strlen( $user ) < 1 ) {
 354                         return null;
 355                 }
 356
 357                 // Close existing connection
 358                 $this->close();
 359                 // Cache conn info
 360                 $this->mServer = $server;
 361                 $this->mPort = $port = $wgDBport;
 362                 $this->mUser = $user;
 363                 $this->mPassword = $password;
 364                 $this->mDBname = $dbName;
 365
 366                 $this->openUncataloged( $dbName, $user, $password, $server, $port );
 367
 368                 // Apply connection config
 369                 db2_set_option( $this->mConn, $this->mConnOptions, 1 );
 370                 // Some MediaWiki code is still transaction-less (?).
 371                 // The strategy is to keep AutoCommit on for that code
 372                 //  but switch it off whenever a transaction is begun.
 373                 db2_autocommit( $this->mConn, DB2_AUTOCOMMIT_ON );
 374
 375                 if ( !$this->mConn ) {
 376                         $this->installPrint( "DB connection error\n" );
 377                         $this->installPrint(
 378                                 "Server: $server, Database: $dbName, User: $user, Password: "
 379                                 . substr( $password, 0, 3 ) . "...\n" );
 380                         $this->installPrint( $this->lastError() . "\n" );
 381                         return null;
 382                 }
 383
 384                 $this->mOpened = true;
 385                 $this->applySchema();
 386
 387                 wfProfileOut( __METHOD__ );
 388                 return $this->mConn;
 389         }
 390
 391         /**
 392          * Opens a cataloged database connection, sets mConn
 393          */
 394         protected function openCataloged( $dbName, $user, $password ) {
 395                 @$this->mConn = db2_pconnect( $dbName, $user, $password );
 396         }
 397
 398         /**
 399          * Opens an uncataloged database connection, sets mConn
 400          */
 401         protected function openUncataloged( $dbName, $user, $password, $server, $port )
 402         {
 403                 $str = "DRIVER={IBM DB2 ODBC DRIVER};";
 404                 $str .= "DATABASE=$dbName;";
 405                 $str .= "HOSTNAME=$server;";
 406                 // port was formerly validated to not be 0
 407                 $str .= "PORT=$port;";
 408                 $str .= "PROTOCOL=TCPIP;";
 409                 $str .= "UID=$user;";
 410                 $str .= "PWD=$password;";
 411
 412                 @$this->mConn = db2_pconnect( $str, $user, $password );
 413         }
 414
 415         /**
 416          * Closes a database connection, if it is open
 417          * Returns success, true if already closed
 418          */
 419         public function close() {
 420                 $this->mOpened = false;
 421                 if ( $this->mConn ) {
 422                         if ( $this->trxLevel() > 0 ) {
 423                                 $this->commit();
 424                         }
 425                         return db2_close( $this->mConn );
 426                 } else {
 427                         return true;
 428                 }
 429         }
 430
 431         /**
 432          * Returns a fresh instance of this class
 433          *
 434          * @param $server String: hostname of database server
 435          * @param $user String: username
 436          * @param $password String
 437          * @param $dbName String: database name on the server
 438          * @param $flags Integer: database behaviour flags (optional, unused)
 439          * @return DatabaseIbm_db2 object
 440          */
 441         static function newFromParams( $server, $user, $password, $dbName,
 442                 $flags = 0 )
 443         {
 444                 return new DatabaseIbm_db2( $server, $user, $password, $dbName,
 445                         $flags );
 446         }
 447
 448         /**
 449          * Retrieves the most current database error
 450          * Forces a database rollback
 451          */
 452         public function lastError() {
 453                 $connerr = db2_conn_errormsg();
 454                 if ( $connerr ) {
 455                         //$this->rollback();
 456                         return $connerr;
 457                 }
 458                 $stmterr = db2_stmt_errormsg();
 459                 if ( $stmterr ) {
 460                         //$this->rollback();
 461                         return $stmterr;
 462                 }
 463
 464                 return false;
 465         }
 466
 467         /**
 468          * Get the last error number
 469          * Return 0 if no error
 470          * @return integer
 471          */
 472         public function lastErrno() {
 473                 $connerr = db2_conn_error();
 474                 if ( $connerr ) {
 475                         return $connerr;
 476                 }
 477                 $stmterr = db2_stmt_error();
 478                 if ( $stmterr ) {
 479                         return $stmterr;
 480                 }
 481                 return 0;
 482         }
 483
 484         /**
 485          * Is a database connection open?
 486          * @return
 487          */
 488         public function isOpen() { return $this->mOpened; }
 489
 490         /**
 491          * The DBMS-dependent part of query()
 492          * @param  $sql String: SQL query.
 493          * @return object Result object for fetch functions or false on failure
 494          * @access private
 495          */
 496         /*private*/
 497         public function doQuery( $sql ) {
 498                 $this->applySchema();
 499
 500                 $ret = db2_exec( $this->mConn, $sql, $this->mStmtOptions );
 501                 if( $ret == false ) {
 502                         $error = db2_stmt_errormsg();
 503                         $this->installPrint( "<pre>$sql</pre>" );
 504                         $this->installPrint( $error );
 505                         throw new DBUnexpectedError( $this, 'SQL error: '
 506                                 . htmlspecialchars( $error ) );
 507                 }
 508                 $this->mLastResult = $ret;
 509                 $this->mAffectedRows = null; // Not calculated until asked for
 510                 return $ret;
 511         }
 512
 513         /**
 514          * @return string Version information from the database
 515          */
 516         public function getServerVersion() {
 517                 $info = db2_server_info( $this->mConn );
 518                 return $info->DBMS_VER;
 519         }
 520
 521         /**
 522          * Queries whether a given table exists
 523          * @return boolean
 524          */
 525         public function tableExists( $table ) {
 526                 $schema = $this->mSchema;
 527                 $sql = <<< EOF
 528 SELECT COUNT( * ) FROM SYSIBM.SYSTABLES ST
 529 WHERE ST.NAME = '$table' AND ST.CREATOR = '$schema'
 530 EOF;
 531                 $res = $this->query( $sql );
 532                 if ( !$res ) {
 533                         return false;
 534                 }
 535
 536                 // If the table exists, there should be one of it
 537                 @$row = $this->fetchRow( $res );
 538                 $count = $row[0];
 539                 if ( $count == '1' || $count == 1 ) {
 540                         return true;
 541                 }
 542
 543                 return false;
 544         }
 545
 546         /**
 547          * Fetch the next row from the given result object, in object form.
 548          * Fields can be retrieved with $row->fieldname, with fields acting like
 549          * member variables.
 550          *
 551          * @param $res SQL result object as returned from Database::query(), etc.
 552          * @return DB2 row object
 553          * @throws DBUnexpectedError Thrown if the database returns an error
 554          */
 555         public function fetchObject( $res ) {
 556                 if ( $res instanceof ResultWrapper ) {
 557                         $res = $res->result;
 558                 }
 559                 @$row = db2_fetch_object( $res );
 560                 if( $this->lastErrno() ) {
 561                         throw new DBUnexpectedError( $this, 'Error in fetchObject(): '
 562                                 . htmlspecialchars( $this->lastError() ) );
 563                 }
 564                 return $row;
 565         }
 566
 567         /**
 568          * Fetch the next row from the given result object, in associative array
 569          * form. Fields are retrieved with $row['fieldname'].
 570          *
 571          * @param $res SQL result object as returned from Database::query(), etc.
 572          * @return DB2 row object
 573          * @throws DBUnexpectedError Thrown if the database returns an error
 574          */
 575         public function fetchRow( $res ) {
 576                 if ( $res instanceof ResultWrapper ) {
 577                         $res = $res->result;
 578                 }
 579                 @$row = db2_fetch_array( $res );
 580                 if ( $this->lastErrno() ) {
 581                         throw new DBUnexpectedError( $this, 'Error in fetchRow(): '
 582                                 . htmlspecialchars( $this->lastError() ) );
 583                 }
 584                 return $row;
 585         }
 586
 587         /**
 588          * Create tables, stored procedures, and so on
 589          */
 590         public function setup_database() {
 591                 try {
 592                         // TODO: switch to root login if available
 593
 594                         // Switch into the correct namespace
 595                         $this->applySchema();
 596                         $this->begin();
 597
 598                         $res = $this->sourceFile( "../maintenance/ibm_db2/tables.sql" );
 599                         if ( $res !== true ) {
 600                                 print ' <b>FAILED</b>: ' . htmlspecialchars( $res ) . '</li>';
 601                         } else {
 602                                 print ' done</li>';
 603                         }
 604                         $res = $this->sourceFile( "../maintenance/ibm_db2/foreignkeys.sql" );
 605                         if ( $res !== true ) {
 606                                 print ' <b>FAILED</b>: ' . htmlspecialchars( $res ) . '</li>';
 607                         } else {
 608                                 print '<li>Foreign keys done</li>';
 609                         }
 610
 611                         // TODO: populate interwiki links
 612
 613                         if ( $this->lastError() ) {
 614                                 $this->installPrint(
 615                                         'Errors encountered during table creation -- rolled back' );
 616                                 $this->installPrint( 'Please install again' );
 617                                 $this->rollback();
 618                         } else {
 619                                 $this->commit();
 620                         }
 621                 } catch ( MWException $mwe ) {
 622                         print "<br><pre>$mwe</pre><br>";
 623                 }
 624         }
 625
 626         /**
 627          * Escapes strings
 628          * Doesn't escape numbers
 629          *
 630          * @param $s String: string to escape
 631          * @return escaped string
 632          */
 633         public function addQuotes( $s ) {
 634                 //$this->installPrint( "DB2::addQuotes( $s )\n" );
 635                 if ( is_null( $s ) ) {
 636                         return 'NULL';
 637                 } elseif ( $s instanceof Blob ) {
 638                         return "'" . $s->fetch( $s ) . "'";
 639                 } elseif ( $s instanceof IBM_DB2Blob ) {
 640                         return "'" . $this->decodeBlob( $s ) . "'";
 641                 }
 642                 $s = $this->strencode( $s );
 643                 if ( is_numeric( $s ) ) {
 644                         return $s;
 645                 } else {
 646                         return "'$s'";
 647                 }
 648         }
 649
 650         /**
 651          * Verifies that a DB2 column/field type is numeric
 652          *
 653          * @param $type String: DB2 column type
 654          * @return Boolean: true if numeric
 655          */
 656         public function is_numeric_type( $type ) {
 657                 switch ( strtoupper( $type ) ) {
 658                         case 'SMALLINT':
 659                         case 'INTEGER':
 660                         case 'INT':
 661                         case 'BIGINT':
 662                         case 'DECIMAL':
 663                         case 'REAL':
 664                         case 'DOUBLE':
 665                         case 'DECFLOAT':
 666                                 return true;
 667                 }
 668                 return false;
 669         }
 670
 671         /**
 672          * Alias for addQuotes()
 673          * @param $s String: string to escape
 674          * @return escaped string
 675          */
 676         public function strencode( $s ) {
 677                 // Bloody useless function
 678                 //  Prepends backslashes to \x00, \n, \r, \, ', " and \x1a.
 679                 //  But also necessary
 680                 $s = db2_escape_string( $s );
 681                 // Wide characters are evil -- some of them look like '
 682                 $s = utf8_encode( $s );
 683                 // Fix its stupidity
 684                 $from = array(  "\\\\", "\\'",  '\\n',  '\\t',  '\\"',  '\\r' );
 685                 $to = array(            "\\",           "''",           "\n",           "\t",           '"',            "\r" );
 686                 $s = str_replace( $from, $to, $s ); // DB2 expects '', not \' escaping
 687                 return $s;
 688         }
 689
 690         /**
 691          * Switch into the database schema
 692          */
 693         protected function applySchema() {
 694                 if ( !( $this->mSchemaSet ) ) {
 695                         $this->mSchemaSet = true;
 696                         $this->begin();
 697                         $this->doQuery( "SET SCHEMA = $this->mSchema" );
 698                         $this->commit();
 699                 }
 700         }
 701
 702         /**
 703          * Start a transaction (mandatory)
 704          */
 705         public function begin( $fname = 'DatabaseIbm_db2::begin' ) {
 706                 // BEGIN is implicit for DB2
 707                 // However, it requires that AutoCommit be off.
 708
 709                 // Some MediaWiki code is still transaction-less (?).
 710                 // The strategy is to keep AutoCommit on for that code
 711                 //  but switch it off whenever a transaction is begun.
 712                 db2_autocommit( $this->mConn, DB2_AUTOCOMMIT_OFF );
 713
 714                 $this->mTrxLevel = 1;
 715         }
 716
 717         /**
 718          * End a transaction
 719          * Must have a preceding begin()
 720          */
 721         public function commit( $fname = 'DatabaseIbm_db2::commit' ) {
 722                 db2_commit( $this->mConn );
 723
 724                 // Some MediaWiki code is still transaction-less (?).
 725                 // The strategy is to keep AutoCommit on for that code
 726                 //  but switch it off whenever a transaction is begun.
 727                 db2_autocommit( $this->mConn, DB2_AUTOCOMMIT_ON );
 728
 729                 $this->mTrxLevel = 0;
 730         }
 731
 732         /**
 733          * Cancel a transaction
 734          */
 735         public function rollback( $fname = 'DatabaseIbm_db2::rollback' ) {
 736                 db2_rollback( $this->mConn );
 737                 // turn auto-commit back on
 738                 // not sure if this is appropriate
 739                 db2_autocommit( $this->mConn, DB2_AUTOCOMMIT_ON );
 740                 $this->mTrxLevel = 0;
 741         }
 742
 743         /**
 744          * Makes an encoded list of strings from an array
 745          * $mode:
 746          *   LIST_COMMA         - comma separated, no field names
 747          *   LIST_AND           - ANDed WHERE clause (without the WHERE)
 748          *   LIST_OR            - ORed WHERE clause (without the WHERE)
 749          *   LIST_SET           - comma separated with field names, like a SET clause
 750          *   LIST_NAMES         - comma separated field names
 751          *   LIST_SET_PREPARED  - like LIST_SET, except with ? tokens as values
 752          */
 753         function makeList( $a, $mode = LIST_COMMA ) {
 754                 if ( !is_array( $a ) ) {
 755                         throw new DBUnexpectedError( $this,
 756                                 'DatabaseBase::makeList called with incorrect parameters' );
 757                 }
 758
 759                 // if this is for a prepared UPDATE statement
 760                 // (this should be promoted to the parent class
 761                 //  once other databases use prepared statements)
 762                 if ( $mode == LIST_SET_PREPARED ) {
 763                         $first = true;
 764                         $list = '';
 765                         foreach ( $a as $field => $value ) {
 766                                 if ( !$first ) {
 767                                         $list .= ", $field = ?";
 768                                 } else {
 769                                         $list .= "$field = ?";
 770                                         $first = false;
 771                                 }
 772                         }
 773                         $list .= '';
 774
 775                         return $list;
 776                 }
 777
 778                 // otherwise, call the usual function
 779                 return parent::makeList( $a, $mode );
 780         }
 781
 782         /**
 783          * Construct a LIMIT query with optional offset
 784          * This is used for query pages
 785          *
 786          * @param $sql string SQL query we will append the limit too
 787          * @param $limit integer the SQL limit
 788          * @param $offset integer the SQL offset (default false)
 789          */
 790         public function limitResult( $sql, $limit, $offset=false ) {
 791                 if( !is_numeric( $limit ) ) {
 792                         throw new DBUnexpectedError( $this,
 793                                 "Invalid non-numeric limit passed to limitResult()\n" );
 794                 }
 795                 if( $offset ) {
 796                         if ( stripos( $sql, 'where' ) === false ) {
 797                                 return "$sql AND ( ROWNUM BETWEEN $offset AND $offset+$limit )";
 798                         } else {
 799                                 return "$sql WHERE ( ROWNUM BETWEEN $offset AND $offset+$limit )";
 800                         }
 801                 }
 802                 return "$sql FETCH FIRST $limit ROWS ONLY ";
 803         }
 804
 805         /**
 806          * Handle reserved keyword replacement in table names
 807          *
 808          * @param $name Object
 809          * @return String
 810          */
 811         public function tableName( $name ) {
 812                 // we want maximum compatibility with MySQL schema
 813                 return $name;
 814         }
 815
 816         /**
 817          * Generates a timestamp in an insertable format
 818          *
 819          * @param $ts timestamp
 820          * @return String: timestamp value
 821          */
 822         public function timestamp( $ts = 0 ) {
 823                 // TS_MW cannot be easily distinguished from an integer
 824                 return wfTimestamp( TS_DB2, $ts );
 825         }
 826
 827         /**
 828          * Return the next in a sequence, save the value for retrieval via insertId()
 829          * @param $seqName String: name of a defined sequence in the database
 830          * @return next value in that sequence
 831          */
 832         public function nextSequenceValue( $seqName ) {
 833                 // Not using sequences in the primary schema to allow for easier migration
 834                 //  from MySQL
 835                 // Emulating MySQL behaviour of using NULL to signal that sequences
 836                 // aren't used
 837                 /*
 838                 $safeseq = preg_replace( "/'/", "''", $seqName );
 839                 $res = $this->query( "VALUES NEXTVAL FOR $safeseq" );
 840                 $row = $this->fetchRow( $res );
 841                 $this->mInsertId = $row[0];
 842                 return $this->mInsertId;
 843                 */
 844                 return null;
 845         }
 846
 847         /**
 848          * This must be called after nextSequenceVal
 849          * @return Last sequence value used as a primary key
 850          */
 851         public function insertId() {
 852                 return $this->mInsertId;
 853         }
 854
 855         /**
 856          * Updates the mInsertId property with the value of the last insert
 857          *  into a generated column
 858          *
 859          * @param $table      String: sanitized table name
 860          * @param $primaryKey Mixed: string name of the primary key
 861          * @param $stmt       Resource: prepared statement resource
 862          *  of the SELECT primary_key FROM FINAL TABLE ( INSERT ... ) form
 863          */
 864         private function calcInsertId( $table, $primaryKey, $stmt ) {
 865                 if ( $primaryKey ) {
 866                         $this->mInsertId = db2_last_insert_id( $this->mConn );
 867                 }
 868         }
 869
 870         /**
 871          * INSERT wrapper, inserts an array into a table
 872          *
 873          * $args may be a single associative array, or an array of arrays
 874          *  with numeric keys, for multi-row insert
 875          *
 876          * @param $table   String: Name of the table to insert to.
 877          * @param $args    Array: Items to insert into the table.
 878          * @param $fname   String: Name of the function, for profiling
 879          * @param $options String or Array. Valid options: IGNORE
 880          *
 881          * @return bool Success of insert operation. IGNORE always returns true.
 882          */
 883         public function insert( $table, $args, $fname = 'DatabaseIbm_db2::insert',
 884                 $options = array() )
 885         {
 886                 if ( !count( $args ) ) {
 887                         return true;
 888                 }
 889                 // get database-specific table name (not used)
 890                 $table = $this->tableName( $table );
 891                 // format options as an array
 892                 $options = IBM_DB2Helper::makeArray( $options );
 893                 // format args as an array of arrays
 894                 if ( !( isset( $args[0] ) && is_array( $args[0] ) ) ) {
 895                         $args = array( $args );
 896                 }
 897
 898                 // prevent insertion of NULL into primary key columns
 899                 list( $args, $primaryKeys ) = $this->removeNullPrimaryKeys( $table, $args );
 900                 // if there's only one primary key
 901                 // we'll be able to read its value after insertion
 902                 $primaryKey = false;
 903                 if ( count( $primaryKeys ) == 1 ) {
 904                         $primaryKey = $primaryKeys[0];
 905                 }
 906
 907                 // get column names
 908                 $keys = array_keys( $args[0] );
 909                 $key_count = count( $keys );
 910
 911                 // If IGNORE is set, we use savepoints to emulate mysql's behavior
 912                 $ignore = in_array( 'IGNORE', $options ) ? 'mw' : '';
 913
 914                 // assume success
 915                 $res = true;
 916                 // If we are not in a transaction, we need to be for savepoint trickery
 917                 if ( !$this->mTrxLevel ) {
 918                         $this->begin();
 919                 }
 920
 921                 $sql = "INSERT INTO $table ( " . implode( ',', $keys ) . ' ) VALUES ';
 922                 if ( $key_count == 1 ) {
 923                         $sql .= '( ? )';
 924                 } else {
 925                         $sql .= '( ?' . str_repeat( ',?', $key_count-1 ) . ' )';
 926                 }
 927                 //$this->installPrint( "Preparing the following SQL:" );
 928                 //$this->installPrint( "$sql" );
 929                 //$this->installPrint( print_r( $args, true ));
 930                 $stmt = $this->prepare( $sql );
 931
 932                 // start a transaction/enter transaction mode
 933                 $this->begin();
 934
 935                 if ( !$ignore ) {
 936                         //$first = true;
 937                         foreach ( $args as $row ) {
 938                                 //$this->installPrint( "Inserting " . print_r( $row, true ));
 939                                 // insert each row into the database
 940                                 $res = $res & $this->execute( $stmt, $row );
 941                                 if ( !$res ) {
 942                                         $this->installPrint( 'Last error:' );
 943                                         $this->installPrint( $this->lastError() );
 944                                 }
 945                                 // get the last inserted value into a generated column
 946                                 $this->calcInsertId( $table, $primaryKey, $stmt );
 947                         }
 948                 } else {
 949                         $olde = error_reporting( 0 );
 950                         // For future use, we may want to track the number of actual inserts
 951                         // Right now, insert (all writes) simply return true/false
 952                         $numrowsinserted = 0;
 953
 954                         // always return true
 955                         $res = true;
 956
 957                         foreach ( $args as $row ) {
 958                                 $overhead = "SAVEPOINT $ignore ON ROLLBACK RETAIN CURSORS";
 959                                 db2_exec( $this->mConn, $overhead, $this->mStmtOptions );
 960
 961                                 $this->execute( $stmt, $row );
 962
 963                                 if ( !$res2 ) {
 964                                         $this->installPrint( 'Last error:' );
 965                                         $this->installPrint( $this->lastError() );
 966                                 }
 967                                 // get the last inserted value into a generated column
 968                                 $this->calcInsertId( $table, $primaryKey, $stmt );
 969
 970                                 $errNum = $this->lastErrno();
 971                                 if ( $errNum ) {
 972                                         db2_exec( $this->mConn, "ROLLBACK TO SAVEPOINT $ignore",
 973                                                 $this->mStmtOptions );
 974                                 } else {
 975                                         db2_exec( $this->mConn, "RELEASE SAVEPOINT $ignore",
 976                                                 $this->mStmtOptions );
 977                                         $numrowsinserted++;
 978                                 }
 979                         }
 980
 981                         $olde = error_reporting( $olde );
 982                         // Set the affected row count for the whole operation
 983                         $this->mAffectedRows = $numrowsinserted;
 984                 }
 985                 // commit either way
 986                 $this->commit();
 987                 $this->freePrepared( $stmt );
 988
 989                 return $res;
 990         }
 991
 992         /**
 993          * Given a table name and a hash of columns with values
 994          * Removes primary key columns from the hash where the value is NULL
 995          *
 996          * @param $table String: name of the table
 997          * @param $args Array of hashes of column names with values
 998          * @return Array: tuple( filtered array of columns, array of primary keys )
 999          */
1000         private function removeNullPrimaryKeys( $table, $args ) {
1001                 $schema = $this->mSchema;
1002                 // find out the primary keys
1003                 $keyres = db2_primary_keys( $this->mConn, null, strtoupper( $schema ),
1004                         strtoupper( $table )
1005                 );
1006                 $keys = array();
1007                 for (
1008                         $row = $this->fetchObject( $keyres );
1009                         $row != null;
1010                         $row = $this->fetchObject( $keyres )
1011                 )
1012                 {
1013                         $keys[] = strtolower( $row->column_name );
1014                 }
1015                 // remove primary keys
1016                 foreach ( $args as $ai => $row ) {
1017                         foreach ( $keys as $key ) {
1018                                 if ( $row[$key] == null ) {
1019                                         unset( $row[$key] );
1020                                 }
1021                         }
1022                         $args[$ai] = $row;
1023                 }
1024                 // return modified hash
1025                 return array( $args, $keys );
1026         }
1027
1028         /**
1029          * UPDATE wrapper, takes a condition array and a SET array
1030          *
1031          * @param $table  String: The table to UPDATE
1032          * @param $values An array of values to SET
1033          * @param $conds  An array of conditions ( WHERE ). Use '*' to update all rows.
1034          * @param $fname  String: The Class::Function calling this function
1035          *                ( for the log )
1036          * @param $options An array of UPDATE options, can be one or
1037          *                 more of IGNORE, LOW_PRIORITY
1038          * @return Boolean
1039          */
1040         public function update( $table, $values, $conds, $fname = 'Database::update',
1041                 $options = array() )
1042         {
1043                 $table = $this->tableName( $table );
1044                 $opts = $this->makeUpdateOptions( $options );
1045                 $sql = "UPDATE $opts $table SET "
1046                         . $this->makeList( $values, LIST_SET_PREPARED );
1047                 if ( $conds != '*' ) {
1048                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1049                 }
1050                 $stmt = $this->prepare( $sql );
1051                 $this->installPrint( 'UPDATE: ' . print_r( $values, true ) );
1052                 // assuming for now that an array with string keys will work
1053                 // if not, convert to simple array first
1054                 $result = $this->execute( $stmt, $values );
1055                 $this->freePrepared( $stmt );
1056
1057                 return $result;
1058         }
1059
1060         /**
1061          * DELETE query wrapper
1062          *
1063          * Use $conds == "*" to delete all rows
1064          */
1065         public function delete( $table, $conds, $fname = 'Database::delete' ) {
1066                 if ( !$conds ) {
1067                         throw new DBUnexpectedError( $this,
1068                         'Database::delete() called with no conditions' );
1069                 }
1070                 $table = $this->tableName( $table );
1071                 $sql = "DELETE FROM $table";
1072                 if ( $conds != '*' ) {
1073                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1074                 }
1075                 $result = $this->query( $sql, $fname );
1076
1077                 return $result;
1078         }
1079
1080         /**
1081          * Returns the number of rows affected by the last query or 0
1082          * @return Integer: the number of rows affected by the last query
1083          */
1084         public function affectedRows() {
1085                 if ( !is_null( $this->mAffectedRows ) ) {
1086                         // Forced result for simulated queries
1087                         return $this->mAffectedRows;
1088                 }
1089                 if( empty( $this->mLastResult ) ) {
1090                         return 0;
1091                 }
1092                 return db2_num_rows( $this->mLastResult );
1093         }
1094
1095         /**
1096          * Simulates REPLACE with a DELETE followed by INSERT
1097          * @param $table Object
1098          * @param $uniqueIndexes Array consisting of indexes and arrays of indexes
1099          * @param $rows Array: rows to insert
1100          * @param $fname String: name of the function for profiling
1101          * @return nothing
1102          */
1103         function replace( $table, $uniqueIndexes, $rows,
1104                 $fname = 'DatabaseIbm_db2::replace' )
1105         {
1106                 $table = $this->tableName( $table );
1107
1108                 if ( count( $rows )==0 ) {
1109                         return;
1110                 }
1111
1112                 # Single row case
1113                 if ( !is_array( reset( $rows ) ) ) {
1114                         $rows = array( $rows );
1115                 }
1116
1117                 foreach( $rows as $row ) {
1118                         # Delete rows which collide
1119                         if ( $uniqueIndexes ) {
1120                                 $sql = "DELETE FROM $table WHERE ";
1121                                 $first = true;
1122                                 foreach ( $uniqueIndexes as $index ) {
1123                                         if ( $first ) {
1124                                                 $first = false;
1125                                                 $sql .= '( ';
1126                                         } else {
1127                                                 $sql .= ' ) OR ( ';
1128                                         }
1129                                         if ( is_array( $index ) ) {
1130                                                 $first2 = true;
1131                                                 foreach ( $index as $col ) {
1132                                                         if ( $first2 ) {
1133                                                                 $first2 = false;
1134                                                         } else {
1135                                                                 $sql .= ' AND ';
1136                                                         }
1137                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
1138                                                 }
1139                                         } else {
1140                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
1141                                         }
1142                                 }
1143                                 $sql .= ' )';
1144                                 $this->query( $sql, $fname );
1145                         }
1146
1147                         # Now insert the row
1148                         $sql = "INSERT INTO $table ( "
1149                                 . $this->makeList( array_keys( $row ), LIST_NAMES )
1150                                 .' ) VALUES ( ' . $this->makeList( $row, LIST_COMMA ) . ' )';
1151                         $this->query( $sql, $fname );
1152                 }
1153         }
1154
1155         /**
1156          * Returns the number of rows in the result set
1157          * Has to be called right after the corresponding select query
1158          * @param $res Object result set
1159          * @return Integer: number of rows
1160          */
1161         public function numRows( $res ) {
1162                 if ( $res instanceof ResultWrapper ) {
1163                         $res = $res->result;
1164                 }
1165                 if ( $this->mNumRows ) {
1166                         return $this->mNumRows;
1167                 } else {
1168                         return 0;
1169                 }
1170         }
1171
1172         /**
1173          * Moves the row pointer of the result set
1174          * @param $res Object: result set
1175          * @param $row Integer: row number
1176          * @return success or failure
1177          */
1178         public function dataSeek( $res, $row ) {
1179                 if ( $res instanceof ResultWrapper ) {
1180                         $res = $res->result;
1181                 }
1182                 return db2_fetch_row( $res, $row );
1183         }
1184
1185         ###
1186         # Fix notices in Block.php
1187         ###
1188
1189         /**
1190          * Frees memory associated with a statement resource
1191          * @param $res Object: statement resource to free
1192          * @return Boolean success or failure
1193          */
1194         public function freeResult( $res ) {
1195                 if ( $res instanceof ResultWrapper ) {
1196                         $res = $res->result;
1197                 }
1198                 if ( !@db2_free_result( $res ) ) {
1199                         throw new DBUnexpectedError( $this, "Unable to free DB2 result\n" );
1200                 }
1201         }
1202
1203         /**
1204          * Returns the number of columns in a resource
1205          * @param $res Object: statement resource
1206          * @return Number of fields/columns in resource
1207          */
1208         public function numFields( $res ) {
1209                 if ( $res instanceof ResultWrapper ) {
1210                         $res = $res->result;
1211                 }
1212                 return db2_num_fields( $res );
1213         }
1214
1215         /**
1216          * Returns the nth column name
1217          * @param $res Object: statement resource
1218          * @param $n Integer: Index of field or column
1219          * @return String name of nth column
1220          */
1221         public function fieldName( $res, $n ) {
1222                 if ( $res instanceof ResultWrapper ) {
1223                         $res = $res->result;
1224                 }
1225                 return db2_field_name( $res, $n );
1226         }
1227
1228         /**
1229          * SELECT wrapper
1230          *
1231          * @param $table   Array or string, table name(s) (prefix auto-added)
1232          * @param $vars    Array or string, field name(s) to be retrieved
1233          * @param $conds   Array or string, condition(s) for WHERE
1234          * @param $fname   String: calling function name (use __METHOD__)
1235          *                 for logs/profiling
1236          * @param $options Associative array of options
1237          *                 (e.g. array('GROUP BY' => 'page_title')),
1238          *                 see Database::makeSelectOptions code for list of
1239          *                 supported stuff
1240          * @param $join_conds Associative array of table join conditions (optional)
1241          *                    (e.g. array( 'page' => array('LEFT JOIN',
1242          *                    'page_latest=rev_id') )
1243          * @return Mixed: database result resource for fetch functions or false
1244          *                 on failure
1245          */
1246         public function select( $table, $vars, $conds = '', $fname = 'DatabaseIbm_db2::select', $options = array(), $join_conds = array() )
1247         {
1248                 $res = parent::select( $table, $vars, $conds, $fname, $options,
1249                         $join_conds );
1250
1251                 // We must adjust for offset
1252                 if ( isset( $options['LIMIT'] ) && isset ( $options['OFFSET'] ) ) {
1253                         $limit = $options['LIMIT'];
1254                         $offset = $options['OFFSET'];
1255                 }
1256
1257                 // DB2 does not have a proper num_rows() function yet, so we must emulate
1258                 // DB2 9.5.4 and the corresponding ibm_db2 driver will introduce
1259                 //  a working one
1260                 // TODO: Yay!
1261
1262                 // we want the count
1263                 $vars2 = array( 'count( * ) as num_rows' );
1264                 // respecting just the limit option
1265                 $options2 = array();
1266                 if ( isset( $options['LIMIT'] ) ) {
1267                         $options2['LIMIT'] = $options['LIMIT'];
1268                 }
1269                 // but don't try to emulate for GROUP BY
1270                 if ( isset( $options['GROUP BY'] ) ) {
1271                         return $res;
1272                 }
1273
1274                 $res2 = parent::select( $table, $vars2, $conds, $fname, $options2,
1275                         $join_conds );
1276                 $obj = $this->fetchObject( $res2 );
1277                 $this->mNumRows = $obj->num_rows;
1278
1279                 return $res;
1280         }
1281
1282         /**
1283          * Handles ordering, grouping, and having options ('GROUP BY' => colname)
1284          * Has limited support for per-column options (colnum => 'DISTINCT')
1285          *
1286          * @private
1287          *
1288          * @param $options Associative array of options to be turned into
1289          *              an SQL query, valid keys are listed in the function.
1290          * @return Array
1291          */
1292         function makeSelectOptions( $options ) {
1293                 $preLimitTail = $postLimitTail = '';
1294                 $startOpts = '';
1295
1296                 $noKeyOptions = array();
1297                 foreach ( $options as $key => $option ) {
1298                         if ( is_numeric( $key ) ) {
1299                                 $noKeyOptions[$option] = true;
1300                         }
1301                 }
1302
1303                 if ( isset( $options['GROUP BY'] ) ) {
1304                         $preLimitTail .= " GROUP BY {$options['GROUP BY']}";
1305                 }
1306                 if ( isset( $options['HAVING'] ) ) {
1307                         $preLimitTail .= " HAVING {$options['HAVING']}";
1308                 }
1309                 if ( isset( $options['ORDER BY'] ) ) {
1310                         $preLimitTail .= " ORDER BY {$options['ORDER BY']}";
1311                 }
1312
1313                 if ( isset( $noKeyOptions['DISTINCT'] )
1314                         || isset( $noKeyOptions['DISTINCTROW'] ) )
1315                 {
1316                         $startOpts .= 'DISTINCT';
1317                 }
1318
1319                 return array( $startOpts, '', $preLimitTail, $postLimitTail );
1320         }
1321
1322         /**
1323          * Returns link to IBM DB2 free download
1324          * @return String: wikitext of a link to the server software's web site
1325          */
1326         public static function getSoftwareLink() {
1327                 return '[http://www.ibm.com/db2/express/ IBM DB2]';
1328         }
1329
1330         /**
1331          * Get search engine class. All subclasses of this
1332          * need to implement this if they wish to use searching.
1333          *
1334          * @return String
1335          */
1336         public function getSearchEngine() {
1337                 return 'SearchIBM_DB2';
1338         }
1339
1340         /**
1341          * Did the last database access fail because of deadlock?
1342          * @return Boolean
1343          */
1344         public function wasDeadlock() {
1345                 // get SQLSTATE
1346                 $err = $this->lastErrno();
1347                 switch( $err ) {
1348                         // This is literal port of the MySQL logic and may be wrong for DB2
1349                         case '40001':   // sql0911n, Deadlock or timeout, rollback
1350                         case '57011':   // sql0904n, Resource unavailable, no rollback
1351                         case '57033':   // sql0913n, Deadlock or timeout, no rollback
1352                         $this->installPrint( "In a deadlock because of SQLSTATE $err" );
1353                         return true;
1354                 }
1355                 return false;
1356         }
1357
1358         /**
1359          * Ping the server and try to reconnect if it there is no connection
1360          * The connection may be closed and reopened while this happens
1361          * @return Boolean: whether the connection exists
1362          */
1363         public function ping() {
1364                 // db2_ping() doesn't exist
1365                 // Emulate
1366                 $this->close();
1367                 $this->mConn = $this->openUncataloged( $this->mDBName, $this->mUser,
1368                         $this->mPassword, $this->mServer, $this->mPort );
1369
1370                 return false;
1371         }
1372         ######################################
1373         # Unimplemented and not applicable
1374         ######################################
1375         /**
1376          * Not implemented
1377          * @return string ''
1378          */
1379         public function getStatus( $which = '%' ) {
1380                 $this->installPrint( 'Not implemented for DB2: getStatus()' );
1381                 return '';
1382         }
1383         /**
1384          * Not implemented
1385          * @return string $sql
1386          */
1387         public function limitResultForUpdate( $sql, $num ) {
1388                 $this->installPrint( 'Not implemented for DB2: limitResultForUpdate()' );
1389                 return $sql;
1390         }
1391
1392         /**
1393          * Only useful with fake prepare like in base Database class
1394          * @return      string
1395          */
1396         public function fillPreparedArg( $matches ) {
1397                 $this->installPrint( 'Not useful for DB2: fillPreparedArg()' );
1398                 return '';
1399         }
1400
1401         ######################################
1402         # Reflection
1403         ######################################
1404
1405         /**
1406          * Returns information about an index
1407          * If errors are explicitly ignored, returns NULL on failure
1408          * @param $table String: table name
1409          * @param $index String: index name
1410          * @param $fname String: function name for logging and profiling
1411          * @return Object query row in object form
1412          */
1413         public function indexInfo( $table, $index,
1414                 $fname = 'DatabaseIbm_db2::indexExists' )
1415         {
1416                 $table = $this->tableName( $table );
1417                 $sql = <<<SQL
1418 SELECT name as indexname
1419 FROM sysibm.sysindexes si
1420 WHERE si.name='$index' AND si.tbname='$table'
1421 AND sc.tbcreator='$this->mSchema'
1422 SQL;
1423                 $res = $this->query( $sql, $fname );
1424                 if ( !$res ) {
1425                         return null;
1426                 }
1427                 $row = $this->fetchObject( $res );
1428                 if ( $row != null ) {
1429                         return $row;
1430                 } else {
1431                         return false;
1432                 }
1433         }
1434
1435         /**
1436          * Returns an information object on a table column
1437          * @param $table String: table name
1438          * @param $field String: column name
1439          * @return IBM_DB2Field
1440          */
1441         public function fieldInfo( $table, $field ) {
1442                 return IBM_DB2Field::fromText( $this, $table, $field );
1443         }
1444
1445         /**
1446          * db2_field_type() wrapper
1447          * @param $res Object: result of executed statement
1448          * @param $index Mixed: number or name of the column
1449          * @return String column type
1450          */
1451         public function fieldType( $res, $index ) {
1452                 if ( $res instanceof ResultWrapper ) {
1453                         $res = $res->result;
1454                 }
1455                 return db2_field_type( $res, $index );
1456         }
1457
1458         /**
1459          * Verifies that an index was created as unique
1460          * @param $table String: table name
1461          * @param $index String: index name
1462          * @param $fname function name for profiling
1463          * @return Bool
1464          */
1465         public function indexUnique ( $table, $index,
1466                 $fname = 'Database::indexUnique' )
1467         {
1468                 $table = $this->tableName( $table );
1469                 $sql = <<<SQL
1470 SELECT si.name as indexname
1471 FROM sysibm.sysindexes si
1472 WHERE si.name='$index' AND si.tbname='$table'
1473 AND sc.tbcreator='$this->mSchema'
1474 AND si.uniquerule IN ( 'U', 'P' )
1475 SQL;
1476                 $res = $this->query( $sql, $fname );
1477                 if ( !$res ) {
1478                         return null;
1479                 }
1480                 if ( $this->fetchObject( $res ) ) {
1481                         return true;
1482                 }
1483                 return false;
1484
1485         }
1486
1487         /**
1488          * Returns the size of a text field, or -1 for "unlimited"
1489          * @param $table String: table name
1490          * @param $field String: column name
1491          * @return Integer: length or -1 for unlimited
1492          */
1493         public function textFieldSize( $table, $field ) {
1494                 $table = $this->tableName( $table );
1495                 $sql = <<<SQL
1496 SELECT length as size
1497 FROM sysibm.syscolumns sc
1498 WHERE sc.name='$field' AND sc.tbname='$table'
1499 AND sc.tbcreator='$this->mSchema'
1500 SQL;
1501                 $res = $this->query( $sql );
1502                 $row = $this->fetchObject( $res );
1503                 $size = $row->size;
1504                 return $size;
1505         }
1506
1507         /**
1508          * DELETE where the condition is a join
1509          * @param $delTable String: deleting from this table
1510          * @param $joinTable String: using data from this table
1511          * @param $delVar String: variable in deleteable table
1512          * @param $joinVar String: variable in data table
1513          * @param $conds Array: conditionals for join table
1514          * @param $fname String: function name for profiling
1515          */
1516         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar,
1517                 $conds, $fname = "DatabaseIbm_db2::deleteJoin" )
1518         {
1519                 if ( !$conds ) {
1520                         throw new DBUnexpectedError( $this,
1521                         'Database::deleteJoin() called with empty $conds' );
1522                 }
1523
1524                 $delTable = $this->tableName( $delTable );
1525                 $joinTable = $this->tableName( $joinTable );
1526                 $sql = <<<SQL
1527 DELETE FROM $delTable
1528 WHERE $delVar IN (
1529   SELECT $joinVar FROM $joinTable
1530
1531 SQL;
1532                 if ( $conds != '*' ) {
1533                         $sql .= 'WHERE ' . $this->makeList( $conds, LIST_AND );
1534                 }
1535                 $sql .= ' )';
1536
1537                 $this->query( $sql, $fname );
1538         }
1539
1540         /**
1541          * Description is left as an exercise for the reader
1542          * @param $b Mixed: data to be encoded
1543          * @return IBM_DB2Blob
1544          */
1545         public function encodeBlob( $b ) {
1546                 return new IBM_DB2Blob( $b );
1547         }
1548
1549         /**
1550          * Description is left as an exercise for the reader
1551          * @param $b IBM_DB2Blob: data to be decoded
1552          * @return mixed
1553          */
1554         public function decodeBlob( $b ) {
1555                 return "$b";
1556         }
1557
1558         /**
1559          * Convert into a list of string being concatenated
1560          * @param $stringList Array: strings that need to be joined together
1561          *                    by the SQL engine
1562          * @return String: joined by the concatenation operator
1563          */
1564         public function buildConcat( $stringList ) {
1565                 // || is equivalent to CONCAT
1566                 // Sample query: VALUES 'foo' CONCAT 'bar' CONCAT 'baz'
1567                 return implode( ' || ', $stringList );
1568         }
1569
1570         /**
1571          * Generates the SQL required to convert a DB2 timestamp into a Unix epoch
1572          * @param $column String: name of timestamp column
1573          * @return String: SQL code
1574          */
1575         public function extractUnixEpoch( $column ) {
1576                 // TODO
1577                 // see SpecialAncientpages
1578         }
1579
1580         ######################################
1581         # Prepared statements
1582         ######################################
1583
1584         /**
1585          * Intended to be compatible with the PEAR::DB wrapper functions.
1586          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
1587          *
1588          * ? = scalar value, quoted as necessary
1589          * ! = raw SQL bit (a function for instance)
1590          * & = filename; reads the file and inserts as a blob
1591          *     (we don't use this though...)
1592          * @param $sql String: SQL statement with appropriate markers
1593          * @param $func String: Name of the function, for profiling
1594          * @return resource a prepared DB2 SQL statement
1595          */
1596         public function prepare( $sql, $func = 'DB2::prepare' ) {
1597                 $stmt = db2_prepare( $this->mConn, $sql, $this->mStmtOptions );
1598                 return $stmt;
1599         }
1600
1601         /**
1602          * Frees resources associated with a prepared statement
1603          * @return Boolean success or failure
1604          */
1605         public function freePrepared( $prepared ) {
1606                 return db2_free_stmt( $prepared );
1607         }
1608
1609         /**
1610          * Execute a prepared query with the various arguments
1611          * @param $prepared String: the prepared sql
1612          * @param $args Mixed: either an array here, or put scalars as varargs
1613          * @return Resource: results object
1614          */
1615         public function execute( $prepared, $args = null ) {
1616                 if( !is_array( $args ) ) {
1617                         # Pull the var args
1618                         $args = func_get_args();
1619                         array_shift( $args );
1620                 }
1621                 $res = db2_execute( $prepared, $args );
1622                 if ( !$res ) {
1623                         $this->installPrint( db2_stmt_errormsg() );
1624                 }
1625                 return $res;
1626         }
1627
1628         /**
1629          * Prepare & execute an SQL statement, quoting and inserting arguments
1630          * in the appropriate places.
1631          * @param $query String
1632          * @param $args ...
1633          */
1634         public function safeQuery( $query, $args = null ) {
1635                 // copied verbatim from Database.php
1636                 $prepared = $this->prepare( $query, 'DB2::safeQuery' );
1637                 if( !is_array( $args ) ) {
1638                         # Pull the var args
1639                         $args = func_get_args();
1640                         array_shift( $args );
1641                 }
1642                 $retval = $this->execute( $prepared, $args );
1643                 $this->freePrepared( $prepared );
1644                 return $retval;
1645         }
1646
1647         /**
1648          * For faking prepared SQL statements on DBs that don't support
1649          * it directly.
1650          * @param $preparedQuery String: a 'preparable' SQL statement
1651          * @param $args Array of arguments to fill it with
1652          * @return String: executable statement
1653          */
1654         public function fillPrepared( $preparedQuery, $args ) {
1655                 reset( $args );
1656                 $this->preparedArgs =& $args;
1657
1658                 foreach ( $args as $i => $arg ) {
1659                         db2_bind_param( $preparedQuery, $i+1, $args[$i] );
1660                 }
1661
1662                 return $preparedQuery;
1663         }
1664
1665         /**
1666          * Switches module between regular and install modes
1667          */
1668         public function setMode( $mode ) {
1669                 $old = $this->mMode;
1670                 $this->mMode = $mode;
1671                 return $old;
1672         }
1673
1674         /**
1675          * Bitwise negation of a column or value in SQL
1676          * Same as (~field) in C
1677          * @param $field String
1678          * @return String
1679          */
1680         function bitNot( $field ) {
1681                 // expecting bit-fields smaller than 4bytes
1682                 return "BITNOT( $field )";
1683         }
1684
1685         /**
1686          * Bitwise AND of two columns or values in SQL
1687          * Same as (fieldLeft & fieldRight) in C
1688          * @param $fieldLeft String
1689          * @param $fieldRight String
1690          * @return String
1691          */
1692         function bitAnd( $fieldLeft, $fieldRight ) {
1693                 return "BITAND( $fieldLeft, $fieldRight )";
1694         }
1695
1696         /**
1697          * Bitwise OR of two columns or values in SQL
1698          * Same as (fieldLeft | fieldRight) in C
1699          * @param $fieldLeft String
1700          * @param $fieldRight String
1701          * @return String
1702          */
1703         function bitOr( $fieldLeft, $fieldRight ) {
1704                 return "BITOR( $fieldLeft, $fieldRight )";
1705         }
1706 }
1707
1708 class IBM_DB2Helper {
1709         public static function makeArray( $maybeArray ) {
1710                 if ( !is_array( $maybeArray ) ) {
1711                         return array( $maybeArray );
1712                 }
1713
1714                 return $maybeArray;
1715         }
1716 }