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 = 'get from global';
 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          *
 250          * @param $server String: hostname of database server
 251          * @param $user String: username
 252          * @param $password String: password
 253          * @param $dbName String: database name on the server
 254          * @param $flags Integer: database behaviour flags (optional, unused)
 255          * @param $schema String
 256          */
 257         public function __construct( $server = false, $user = false,
 258                                                         $password = false,
 259                                                         $dbName = false, $flags = 0,
 260                                                         $schema = self::USE_GLOBAL )
 261         {
 262                 global $wgDBmwschema;
 263
 264                 if ( $schema == self::USE_GLOBAL ) {
 265                         $this->mSchema = $wgDBmwschema;
 266                 } else {
 267                         $this->mSchema = $schema;
 268                 }
 269
 270                 // configure the connection and statement objects
 271                 /*
 272                 $this->setDB2Option( 'cursor', 'DB2_SCROLLABLE',
 273                         self::CONN_OPTION | self::STMT_OPTION );
 274                 */
 275                 $this->setDB2Option( 'db2_attr_case', 'DB2_CASE_LOWER',
 276                         self::CONN_OPTION | self::STMT_OPTION );
 277                 $this->setDB2Option( 'deferred_prepare', 'DB2_DEFERRED_PREPARE_ON',
 278                         self::STMT_OPTION );
 279                 $this->setDB2Option( 'rowcount', 'DB2_ROWCOUNT_PREFETCH_ON',
 280                         self::STMT_OPTION );
 281
 282                 parent::__construct( $server, $user, $password, $dbName, DBO_TRX | $flags );
 283         }
 284
 285         /**
 286          * Enables options only if the ibm_db2 extension version supports them
 287          * @param $name String: name of the option in the options array
 288          * @param $const String: name of the constant holding the right option value
 289          * @param $type Integer: whether this is a Connection or Statement otion
 290          */
 291         private function setDB2Option( $name, $const, $type ) {
 292                 if ( defined( $const ) ) {
 293                         if ( $type & self::CONN_OPTION ) {
 294                                 $this->mConnOptions[$name] = constant( $const );
 295                         }
 296                         if ( $type & self::STMT_OPTION ) {
 297                                 $this->mStmtOptions[$name] = constant( $const );
 298                         }
 299                 } else {
 300                         $this->installPrint(
 301                                 "$const is not defined. ibm_db2 version is likely too low." );
 302                 }
 303         }
 304
 305         /**
 306          * Outputs debug information in the appropriate place
 307          * @param $string String: the relevant debug message
 308          */
 309         private function installPrint( $string ) {
 310                 wfDebug( "$string\n" );
 311                 if ( $this->mMode == self::INSTALL_MODE ) {
 312                         print "<li><pre>$string</pre></li>";
 313                         flush();
 314                 }
 315         }
 316
 317         /**
 318          * Opens a database connection and returns it
 319          * Closes any existing connection
 320          *
 321          * @param $server String: hostname
 322          * @param $user String
 323          * @param $password String
 324          * @param $dbName String: database name
 325          * @return a fresh connection
 326          */
 327         public function open( $server, $user, $password, $dbName ) {
 328                 wfProfileIn( __METHOD__ );
 329
 330                 # Load IBM DB2 driver if missing
 331                 wfDl( 'ibm_db2' );
 332
 333                 # Test for IBM DB2 support, to avoid suppressed fatal error
 334                 if ( !function_exists( 'db2_connect' ) ) {
 335                         throw new DBConnectionError( $this, "DB2 functions missing, have you enabled the ibm_db2 extension for PHP?" );
 336                 }
 337
 338                 global $wgDBport;
 339
 340                 // Close existing connection
 341                 $this->close();
 342                 // Cache conn info
 343                 $this->mServer = $server;
 344                 $this->mPort = $port = $wgDBport;
 345                 $this->mUser = $user;
 346                 $this->mPassword = $password;
 347                 $this->mDBname = $dbName;
 348
 349                 $this->openUncataloged( $dbName, $user, $password, $server, $port );
 350
 351                 if ( !$this->mConn ) {
 352                         $this->installPrint( "DB connection error\n" );
 353                         $this->installPrint(
 354                                 "Server: $server, Database: $dbName, User: $user, Password: "
 355                                 . substr( $password, 0, 3 ) . "...\n" );
 356                         $this->installPrint( $this->lastError() . "\n" );
 357                         wfProfileOut( __METHOD__ );
 358                         wfDebug( "DB connection error\n" );
 359                         wfDebug( "Server: $server, Database: $dbName, User: $user, Password: " . substr( $password, 0, 3 ) . "...\n" );
 360                         wfDebug( $this->lastError() . "\n" );
 361                         throw new DBConnectionError( $this, $this->lastError() );
 362                 }
 363
 364                 // Apply connection config
 365                 db2_set_option( $this->mConn, $this->mConnOptions, 1 );
 366                 // Some MediaWiki code is still transaction-less (?).
 367                 // The strategy is to keep AutoCommit on for that code
 368                 //  but switch it off whenever a transaction is begun.
 369                 db2_autocommit( $this->mConn, DB2_AUTOCOMMIT_ON );
 370
 371                 $this->mOpened = true;
 372                 $this->applySchema();
 373
 374                 wfProfileOut( __METHOD__ );
 375                 return $this->mConn;
 376         }
 377
 378         /**
 379          * Opens a cataloged database connection, sets mConn
 380          */
 381         protected function openCataloged( $dbName, $user, $password ) {
 382                 @$this->mConn = db2_pconnect( $dbName, $user, $password );
 383         }
 384
 385         /**
 386          * Opens an uncataloged database connection, sets mConn
 387          */
 388         protected function openUncataloged( $dbName, $user, $password, $server, $port )
 389         {
 390                 $dsn = "DRIVER={IBM DB2 ODBC DRIVER};DATABASE=$dbName;CHARSET=UTF-8;HOSTNAME=$server;PORT=$port;PROTOCOL=TCPIP;UID=$user;PWD=$password;";
 391                 @$this->mConn = db2_pconnect($dsn, "", "", array());
 392         }
 393
 394         /**
 395          * Closes a database connection, if it is open
 396          * Returns success, true if already closed
 397          */
 398         public function close() {
 399                 $this->mOpened = false;
 400                 if ( $this->mConn ) {
 401                         if ( $this->trxLevel() > 0 ) {
 402                                 $this->commit();
 403                         }
 404                         return db2_close( $this->mConn );
 405                 } else {
 406                         return true;
 407                 }
 408         }
 409
 410         /**
 411          * Retrieves the most current database error
 412          * Forces a database rollback
 413          */
 414         public function lastError() {
 415                 $connerr = db2_conn_errormsg();
 416                 if ( $connerr ) {
 417                         //$this->rollback();
 418                         return $connerr;
 419                 }
 420                 $stmterr = db2_stmt_errormsg();
 421                 if ( $stmterr ) {
 422                         //$this->rollback();
 423                         return $stmterr;
 424                 }
 425
 426                 return false;
 427         }
 428
 429         /**
 430          * Get the last error number
 431          * Return 0 if no error
 432          * @return integer
 433          */
 434         public function lastErrno() {
 435                 $connerr = db2_conn_error();
 436                 if ( $connerr ) {
 437                         return $connerr;
 438                 }
 439                 $stmterr = db2_stmt_error();
 440                 if ( $stmterr ) {
 441                         return $stmterr;
 442                 }
 443                 return 0;
 444         }
 445
 446         /**
 447          * Is a database connection open?
 448          * @return
 449          */
 450         public function isOpen() { return $this->mOpened; }
 451
 452         /**
 453          * The DBMS-dependent part of query()
 454          * @param  $sql String: SQL query.
 455          * @return object Result object for fetch functions or false on failure
 456          * @access private
 457          */
 458         /*private*/
 459         public function doQuery( $sql ) {
 460                 $this->applySchema();
 461
 462                 // Needed to handle any UTF-8 encoding issues in the raw sql
 463                 // Note that we fully support prepared statements for DB2
 464                 // prepare() and execute() should be used instead of doQuery() whenever possible
 465                 $sql = utf8_decode($sql);
 466
 467                 $ret = db2_exec( $this->mConn, $sql, $this->mStmtOptions );
 468                 if( $ret == false ) {
 469                         //TODO: Remove commented-out debug code once done debugging
 470                         //echo '<pre>ERROR</pre>';
 471                         //echo '<pre>' . $sql . '</pre>';
 472                         $error = db2_stmt_errormsg();
 473                         //echo '<pre>' . $error . '</pre>';
 474                         $this->installPrint( "<pre>$sql</pre>" );
 475                         $this->installPrint( $error );
 476                         throw new DBUnexpectedError( $this, 'SQL error: '
 477                                 . htmlspecialchars( $error ) );
 478                 }
 479                 $this->mLastResult = $ret;
 480                 $this->mAffectedRows = null; // Not calculated until asked for
 481                 return $ret;
 482         }
 483
 484         /**
 485          * @return string Version information from the database
 486          */
 487         public function getServerVersion() {
 488                 $info = db2_server_info( $this->mConn );
 489                 return $info->DBMS_VER;
 490         }
 491
 492         /**
 493          * Queries whether a given table exists
 494          * @return boolean
 495          */
 496         public function tableExists( $table ) {
 497                 $schema = $this->mSchema;
 498                 /*$sql = <<< EOF
 499 SELECT COUNT( * ) FROM SYSIBM.SYSTABLES ST
 500 WHERE ST.NAME = '$table' AND ST.CREATOR = '$schema'
 501 EOF;*/
 502                 $sql = "SELECT COUNT( * ) FROM SYSIBM.SYSTABLES ST WHERE ST.NAME = '" .
 503                         strtoupper( $table ) .
 504                         "' AND ST.CREATOR = '" .
 505                         strtoupper( $schema ) . "'";
 506                 $res = $this->query( $sql );
 507                 if ( !$res ) {
 508                         return false;
 509                 }
 510
 511                 // If the table exists, there should be one of it
 512                 @$row = $this->fetchRow( $res );
 513                 $count = $row[0];
 514                 if ( $count == '1' || $count == 1 ) {
 515                         return true;
 516                 }
 517
 518                 return false;
 519         }
 520
 521         /**
 522          * Fetch the next row from the given result object, in object form.
 523          * Fields can be retrieved with $row->fieldname, with fields acting like
 524          * member variables.
 525          *
 526          * @param $res SQL result object as returned from Database::query(), etc.
 527          * @return DB2 row object
 528          * @throws DBUnexpectedError Thrown if the database returns an error
 529          */
 530         public function fetchObject( $res ) {
 531                 if ( $res instanceof ResultWrapper ) {
 532                         $res = $res->result;
 533                 }
 534                 @$row = db2_fetch_object( $res );
 535                 if( $this->lastErrno() ) {
 536                         throw new DBUnexpectedError( $this, 'Error in fetchObject(): '
 537                                 . htmlspecialchars( $this->lastError() ) );
 538                 }
 539                 return $row;
 540         }
 541
 542         /**
 543          * Fetch the next row from the given result object, in associative array
 544          * form. Fields are retrieved with $row['fieldname'].
 545          *
 546          * @param $res SQL result object as returned from Database::query(), etc.
 547          * @return DB2 row object
 548          * @throws DBUnexpectedError Thrown if the database returns an error
 549          */
 550         public function fetchRow( $res ) {
 551                 if ( $res instanceof ResultWrapper ) {
 552                         $res = $res->result;
 553                 }
 554                 if ( db2_num_rows( $res ) > 0) {
 555                         @$row = db2_fetch_array( $res );
 556                         if ( $this->lastErrno() ) {
 557                                 throw new DBUnexpectedError( $this, 'Error in fetchRow(): '
 558                                         . htmlspecialchars( $this->lastError() ) );
 559                         }
 560                         return $row;
 561                 }
 562                 return false;
 563         }
 564
 565         /**
 566          * Create tables, stored procedures, and so on
 567          */
 568         public function setup_database() {
 569                 try {
 570                         // TODO: switch to root login if available
 571
 572                         // Switch into the correct namespace
 573                         $this->applySchema();
 574                         $this->begin();
 575
 576                         $res = $this->sourceFile( "../maintenance/ibm_db2/tables.sql" );
 577                         if ( $res !== true ) {
 578                                 print ' <b>FAILED</b>: ' . htmlspecialchars( $res ) . '</li>';
 579                         } else {
 580                                 print ' done</li>';
 581                         }
 582                         $res = $this->sourceFile( "../maintenance/ibm_db2/foreignkeys.sql" );
 583                         if ( $res !== true ) {
 584                                 print ' <b>FAILED</b>: ' . htmlspecialchars( $res ) . '</li>';
 585                         } else {
 586                                 print '<li>Foreign keys done</li>';
 587                         }
 588
 589                         // TODO: populate interwiki links
 590
 591                         if ( $this->lastError() ) {
 592                                 $this->installPrint(
 593                                         'Errors encountered during table creation -- rolled back' );
 594                                 $this->installPrint( 'Please install again' );
 595                                 $this->rollback();
 596                         } else {
 597                                 $this->commit();
 598                         }
 599                 } catch ( MWException $mwe ) {
 600                         print "<br><pre>$mwe</pre><br>";
 601                 }
 602         }
 603
 604         /**
 605          * Escapes strings
 606          * Doesn't escape numbers
 607          *
 608          * @param $s String: string to escape
 609          * @return escaped string
 610          */
 611         public function addQuotes( $s ) {
 612                 //$this->installPrint( "DB2::addQuotes( $s )\n" );
 613                 if ( is_null( $s ) ) {
 614                         return 'NULL';
 615                 } elseif ( $s instanceof Blob ) {
 616                         return "'" . $s->fetch( $s ) . "'";
 617                 } elseif ( $s instanceof IBM_DB2Blob ) {
 618                         return "'" . $this->decodeBlob( $s ) . "'";
 619                 }
 620                 $s = $this->strencode( $s );
 621                 if ( is_numeric( $s ) ) {
 622                         return $s;
 623                 } else {
 624                         return "'$s'";
 625                 }
 626         }
 627
 628         /**
 629          * Verifies that a DB2 column/field type is numeric
 630          *
 631          * @param $type String: DB2 column type
 632          * @return Boolean: true if numeric
 633          */
 634         public function is_numeric_type( $type ) {
 635                 switch ( strtoupper( $type ) ) {
 636                         case 'SMALLINT':
 637                         case 'INTEGER':
 638                         case 'INT':
 639                         case 'BIGINT':
 640                         case 'DECIMAL':
 641                         case 'REAL':
 642                         case 'DOUBLE':
 643                         case 'DECFLOAT':
 644                                 return true;
 645                 }
 646                 return false;
 647         }
 648
 649         /**
 650          * Alias for addQuotes()
 651          * @param $s String: string to escape
 652          * @return escaped string
 653          */
 654         public function strencode( $s ) {
 655                 // Bloody useless function
 656                 //  Prepends backslashes to \x00, \n, \r, \, ', " and \x1a.
 657                 //  But also necessary
 658                 $s = db2_escape_string( $s );
 659                 // Wide characters are evil -- some of them look like '
 660                 $s = utf8_encode( $s );
 661                 // Fix its stupidity
 662                 $from = array(  "\\\\", "\\'",  '\\n',  '\\t',  '\\"',  '\\r' );
 663                 $to = array(            "\\",           "''",           "\n",           "\t",           '"',            "\r" );
 664                 $s = str_replace( $from, $to, $s ); // DB2 expects '', not \' escaping
 665                 return $s;
 666         }
 667
 668         /**
 669          * Switch into the database schema
 670          */
 671         protected function applySchema() {
 672                 if ( !( $this->mSchemaSet ) ) {
 673                         $this->mSchemaSet = true;
 674                         $this->begin();
 675                         $this->doQuery( "SET SCHEMA = $this->mSchema" );
 676                         $this->commit();
 677                 }
 678         }
 679
 680         /**
 681          * Start a transaction (mandatory)
 682          */
 683         public function begin( $fname = 'DatabaseIbm_db2::begin' ) {
 684                 // BEGIN is implicit for DB2
 685                 // However, it requires that AutoCommit be off.
 686
 687                 // Some MediaWiki code is still transaction-less (?).
 688                 // The strategy is to keep AutoCommit on for that code
 689                 //  but switch it off whenever a transaction is begun.
 690                 db2_autocommit( $this->mConn, DB2_AUTOCOMMIT_OFF );
 691
 692                 $this->mTrxLevel = 1;
 693         }
 694
 695         /**
 696          * End a transaction
 697          * Must have a preceding begin()
 698          */
 699         public function commit( $fname = 'DatabaseIbm_db2::commit' ) {
 700                 db2_commit( $this->mConn );
 701
 702                 // Some MediaWiki code is still transaction-less (?).
 703                 // The strategy is to keep AutoCommit on for that code
 704                 //  but switch it off whenever a transaction is begun.
 705                 db2_autocommit( $this->mConn, DB2_AUTOCOMMIT_ON );
 706
 707                 $this->mTrxLevel = 0;
 708         }
 709
 710         /**
 711          * Cancel a transaction
 712          */
 713         public function rollback( $fname = 'DatabaseIbm_db2::rollback' ) {
 714                 db2_rollback( $this->mConn );
 715                 // turn auto-commit back on
 716                 // not sure if this is appropriate
 717                 db2_autocommit( $this->mConn, DB2_AUTOCOMMIT_ON );
 718                 $this->mTrxLevel = 0;
 719         }
 720
 721         /**
 722          * Makes an encoded list of strings from an array
 723          * $mode:
 724          *   LIST_COMMA         - comma separated, no field names
 725          *   LIST_AND           - ANDed WHERE clause (without the WHERE)
 726          *   LIST_OR            - ORed WHERE clause (without the WHERE)
 727          *   LIST_SET           - comma separated with field names, like a SET clause
 728          *   LIST_NAMES         - comma separated field names
 729          *   LIST_SET_PREPARED  - like LIST_SET, except with ? tokens as values
 730          */
 731         function makeList( $a, $mode = LIST_COMMA ) {
 732                 if ( !is_array( $a ) ) {
 733                         throw new DBUnexpectedError( $this,
 734                                 'DatabaseIbm_db2::makeList called with incorrect parameters' );
 735                 }
 736
 737                 // if this is for a prepared UPDATE statement
 738                 // (this should be promoted to the parent class
 739                 //  once other databases use prepared statements)
 740                 if ( $mode == LIST_SET_PREPARED ) {
 741                         $first = true;
 742                         $list = '';
 743                         foreach ( $a as $field => $value ) {
 744                                 if ( !$first ) {
 745                                         $list .= ", $field = ?";
 746                                 } else {
 747                                         $list .= "$field = ?";
 748                                         $first = false;
 749                                 }
 750                         }
 751                         $list .= '';
 752
 753                         return $list;
 754                 }
 755
 756                 // otherwise, call the usual function
 757                 return parent::makeList( $a, $mode );
 758         }
 759
 760         /**
 761          * Construct a LIMIT query with optional offset
 762          * This is used for query pages
 763          *
 764          * @param $sql string SQL query we will append the limit too
 765          * @param $limit integer the SQL limit
 766          * @param $offset integer the SQL offset (default false)
 767          */
 768         public function limitResult( $sql, $limit, $offset=false ) {
 769                 if( !is_numeric( $limit ) ) {
 770                         throw new DBUnexpectedError( $this,
 771                                 "Invalid non-numeric limit passed to limitResult()\n" );
 772                 }
 773                 if( $offset ) {
 774                         if ( stripos( $sql, 'where' ) === false ) {
 775                                 return "$sql AND ( ROWNUM BETWEEN $offset AND $offset+$limit )";
 776                         } else {
 777                                 return "$sql WHERE ( ROWNUM BETWEEN $offset AND $offset+$limit )";
 778                         }
 779                 }
 780                 return "$sql FETCH FIRST $limit ROWS ONLY ";
 781         }
 782
 783         /**
 784          * Handle reserved keyword replacement in table names
 785          *
 786          * @param $name Object
 787          * @return String
 788          */
 789         public function tableName( $name ) {
 790                 // we want maximum compatibility with MySQL schema
 791                 return $name;
 792         }
 793
 794         /**
 795          * Generates a timestamp in an insertable format
 796          *
 797          * @param $ts timestamp
 798          * @return String: timestamp value
 799          */
 800         public function timestamp( $ts = 0 ) {
 801                 // TS_MW cannot be easily distinguished from an integer
 802                 return wfTimestamp( TS_DB2, $ts );
 803         }
 804
 805         /**
 806          * Return the next in a sequence, save the value for retrieval via insertId()
 807          * @param $seqName String: name of a defined sequence in the database
 808          * @return next value in that sequence
 809          */
 810         public function nextSequenceValue( $seqName ) {
 811                 // Not using sequences in the primary schema to allow for easier migration
 812                 //  from MySQL
 813                 // Emulating MySQL behaviour of using NULL to signal that sequences
 814                 // aren't used
 815                 /*
 816                 $safeseq = preg_replace( "/'/", "''", $seqName );
 817                 $res = $this->query( "VALUES NEXTVAL FOR $safeseq" );
 818                 $row = $this->fetchRow( $res );
 819                 $this->mInsertId = $row[0];
 820                 return $this->mInsertId;
 821                 */
 822                 return null;
 823         }
 824
 825         /**
 826          * This must be called after nextSequenceVal
 827          * @return Last sequence value used as a primary key
 828          */
 829         public function insertId() {
 830                 return $this->mInsertId;
 831         }
 832
 833         /**
 834          * Updates the mInsertId property with the value of the last insert
 835          *  into a generated column
 836          *
 837          * @param $table      String: sanitized table name
 838          * @param $primaryKey Mixed: string name of the primary key
 839          * @param $stmt       Resource: prepared statement resource
 840          *  of the SELECT primary_key FROM FINAL TABLE ( INSERT ... ) form
 841          */
 842         private function calcInsertId( $table, $primaryKey, $stmt ) {
 843                 if ( $primaryKey ) {
 844                         $this->mInsertId = db2_last_insert_id( $this->mConn );
 845                 }
 846         }
 847
 848         /**
 849          * INSERT wrapper, inserts an array into a table
 850          *
 851          * $args may be a single associative array, or an array of arrays
 852          *  with numeric keys, for multi-row insert
 853          *
 854          * @param $table   String: Name of the table to insert to.
 855          * @param $args    Array: Items to insert into the table.
 856          * @param $fname   String: Name of the function, for profiling
 857          * @param $options String or Array. Valid options: IGNORE
 858          *
 859          * @return bool Success of insert operation. IGNORE always returns true.
 860          */
 861         public function insert( $table, $args, $fname = 'DatabaseIbm_db2::insert',
 862                 $options = array() )
 863         {
 864                 if ( !count( $args ) ) {
 865                         return true;
 866                 }
 867                 // get database-specific table name (not used)
 868                 $table = $this->tableName( $table );
 869                 // format options as an array
 870                 $options = IBM_DB2Helper::makeArray( $options );
 871                 // format args as an array of arrays
 872                 if ( !( isset( $args[0] ) && is_array( $args[0] ) ) ) {
 873                         $args = array( $args );
 874                 }
 875
 876                 // prevent insertion of NULL into primary key columns
 877                 list( $args, $primaryKeys ) = $this->removeNullPrimaryKeys( $table, $args );
 878                 // if there's only one primary key
 879                 // we'll be able to read its value after insertion
 880                 $primaryKey = false;
 881                 if ( count( $primaryKeys ) == 1 ) {
 882                         $primaryKey = $primaryKeys[0];
 883                 }
 884
 885                 // get column names
 886                 $keys = array_keys( $args[0] );
 887                 $key_count = count( $keys );
 888
 889                 // If IGNORE is set, we use savepoints to emulate mysql's behavior
 890                 $ignore = in_array( 'IGNORE', $options ) ? 'mw' : '';
 891
 892                 // assume success
 893                 $res = true;
 894                 // If we are not in a transaction, we need to be for savepoint trickery
 895                 if ( !$this->mTrxLevel ) {
 896                         $this->begin();
 897                 }
 898
 899                 $sql = "INSERT INTO $table ( " . implode( ',', $keys ) . ' ) VALUES ';
 900                 if ( $key_count == 1 ) {
 901                         $sql .= '( ? )';
 902                 } else {
 903                         $sql .= '( ?' . str_repeat( ',?', $key_count-1 ) . ' )';
 904                 }
 905                 $this->installPrint( "Preparing the following SQL:" );
 906                 $this->installPrint( "$sql" );
 907                 $this->installPrint( print_r( $args, true ));
 908                 $stmt = $this->prepare( $sql );
 909
 910                 // start a transaction/enter transaction mode
 911                 $this->begin();
 912
 913                 if ( !$ignore ) {
 914                         //$first = true;
 915                         foreach ( $args as $row ) {
 916                                 //$this->installPrint( "Inserting " . print_r( $row, true ));
 917                                 // insert each row into the database
 918                                 $res = $res & $this->execute( $stmt, $row );
 919                                 if ( !$res ) {
 920                                         $this->installPrint( 'Last error:' );
 921                                         $this->installPrint( $this->lastError() );
 922                                 }
 923                                 // get the last inserted value into a generated column
 924                                 $this->calcInsertId( $table, $primaryKey, $stmt );
 925                         }
 926                 } else {
 927                         $olde = error_reporting( 0 );
 928                         // For future use, we may want to track the number of actual inserts
 929                         // Right now, insert (all writes) simply return true/false
 930                         $numrowsinserted = 0;
 931
 932                         // always return true
 933                         $res = true;
 934
 935                         foreach ( $args as $row ) {
 936                                 $overhead = "SAVEPOINT $ignore ON ROLLBACK RETAIN CURSORS";
 937                                 db2_exec( $this->mConn, $overhead, $this->mStmtOptions );
 938
 939                                 $res2 = $this->execute( $stmt, $row );
 940
 941                                 if ( !$res2 ) {
 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                                 $errNum = $this->lastErrno();
 949                                 if ( $errNum ) {
 950                                         db2_exec( $this->mConn, "ROLLBACK TO SAVEPOINT $ignore",
 951                                                 $this->mStmtOptions );
 952                                 } else {
 953                                         db2_exec( $this->mConn, "RELEASE SAVEPOINT $ignore",
 954                                                 $this->mStmtOptions );
 955                                         $numrowsinserted++;
 956                                 }
 957                         }
 958
 959                         $olde = error_reporting( $olde );
 960                         // Set the affected row count for the whole operation
 961                         $this->mAffectedRows = $numrowsinserted;
 962                 }
 963                 // commit either way
 964                 $this->commit();
 965                 $this->freePrepared( $stmt );
 966
 967                 return $res;
 968         }
 969
 970         /**
 971          * Given a table name and a hash of columns with values
 972          * Removes primary key columns from the hash where the value is NULL
 973          *
 974          * @param $table String: name of the table
 975          * @param $args Array of hashes of column names with values
 976          * @return Array: tuple( filtered array of columns, array of primary keys )
 977          */
 978         private function removeNullPrimaryKeys( $table, $args ) {
 979                 $schema = $this->mSchema;
 980                 // find out the primary keys
 981                 /*$keyres = db2_primary_keys( $this->mConn, null, strtoupper( $schema ),
 982                         strtoupper( $table )
 983                 );*/
 984                 $keyres = $this->doQuery( "SELECT NAME FROM SYSIBM.SYSCOLUMNS WHERE TBNAME = '" . strtoupper( $table ) . "' AND TBCREATOR = '" . strtoupper( $schema ) . "' AND KEYSEQ > 0" );
 985                 $keys = array();
 986                 for (
 987                         $row = $this->fetchRow( $keyres );
 988                         $row != null;
 989                         $row = $this->fetchRow( $keyres )
 990                 )
 991                 {
 992                         $keys[] = strtolower( $row[0] );
 993                 }
 994                 // remove primary keys
 995                 foreach ( $args as $ai => $row ) {
 996                         foreach ( $keys as $key ) {
 997                                 if ( $row[$key] == null ) {
 998                                         unset( $row[$key] );
 999                                 }
1000                         }
1001                         $args[$ai] = $row;
1002                 }
1003                 // return modified hash
1004                 return array( $args, $keys );
1005         }
1006
1007         /**
1008          * UPDATE wrapper, takes a condition array and a SET array
1009          *
1010          * @param $table  String: The table to UPDATE
1011          * @param $values An array of values to SET
1012          * @param $conds  An array of conditions ( WHERE ). Use '*' to update all rows.
1013          * @param $fname  String: The Class::Function calling this function
1014          *                ( for the log )
1015          * @param $options An array of UPDATE options, can be one or
1016          *                 more of IGNORE, LOW_PRIORITY
1017          * @return Boolean
1018          */
1019         public function update( $table, $values, $conds, $fname = 'DatabaseIbm_db2::update',
1020                 $options = array() )
1021         {
1022                 $table = $this->tableName( $table );
1023                 $opts = $this->makeUpdateOptions( $options );
1024                 $sql = "UPDATE $opts $table SET "
1025                         . $this->makeList( $values, LIST_SET_PREPARED );
1026                 if ( $conds != '*' ) {
1027                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1028                 }
1029                 $stmt = $this->prepare( $sql );
1030                 $this->installPrint( 'UPDATE: ' . print_r( $values, true ) );
1031                 // assuming for now that an array with string keys will work
1032                 // if not, convert to simple array first
1033                 $result = $this->execute( $stmt, $values );
1034                 $this->freePrepared( $stmt );
1035
1036                 return $result;
1037         }
1038
1039         /**
1040          * DELETE query wrapper
1041          *
1042          * Use $conds == "*" to delete all rows
1043          */
1044         public function delete( $table, $conds, $fname = 'DatabaseIbm_db2::delete' ) {
1045                 if ( !$conds ) {
1046                         throw new DBUnexpectedError( $this,
1047                                 'DatabaseIbm_db2::delete() called with no conditions' );
1048                 }
1049                 $table = $this->tableName( $table );
1050                 $sql = "DELETE FROM $table";
1051                 if ( $conds != '*' ) {
1052                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1053                 }
1054                 $result = $this->query( $sql, $fname );
1055
1056                 return $result;
1057         }
1058
1059         /**
1060          * Returns the number of rows affected by the last query or 0
1061          * @return Integer: the number of rows affected by the last query
1062          */
1063         public function affectedRows() {
1064                 if ( !is_null( $this->mAffectedRows ) ) {
1065                         // Forced result for simulated queries
1066                         return $this->mAffectedRows;
1067                 }
1068                 if( empty( $this->mLastResult ) ) {
1069                         return 0;
1070                 }
1071                 return db2_num_rows( $this->mLastResult );
1072         }
1073
1074         /**
1075          * Simulates REPLACE with a DELETE followed by INSERT
1076          * @param $table Object
1077          * @param $uniqueIndexes Array consisting of indexes and arrays of indexes
1078          * @param $rows Array: rows to insert
1079          * @param $fname String: name of the function for profiling
1080          * @return nothing
1081          */
1082         function replace( $table, $uniqueIndexes, $rows,
1083                 $fname = 'DatabaseIbm_db2::replace' )
1084         {
1085                 $table = $this->tableName( $table );
1086
1087                 if ( count( $rows )==0 ) {
1088                         return;
1089                 }
1090
1091                 # Single row case
1092                 if ( !is_array( reset( $rows ) ) ) {
1093                         $rows = array( $rows );
1094                 }
1095
1096                 foreach( $rows as $row ) {
1097                         # Delete rows which collide
1098                         if ( $uniqueIndexes ) {
1099                                 $sql = "DELETE FROM $table WHERE ";
1100                                 $first = true;
1101                                 foreach ( $uniqueIndexes as $index ) {
1102                                         if ( $first ) {
1103                                                 $first = false;
1104                                                 $sql .= '( ';
1105                                         } else {
1106                                                 $sql .= ' ) OR ( ';
1107                                         }
1108                                         if ( is_array( $index ) ) {
1109                                                 $first2 = true;
1110                                                 foreach ( $index as $col ) {
1111                                                         if ( $first2 ) {
1112                                                                 $first2 = false;
1113                                                         } else {
1114                                                                 $sql .= ' AND ';
1115                                                         }
1116                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
1117                                                 }
1118                                         } else {
1119                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
1120                                         }
1121                                 }
1122                                 $sql .= ' )';
1123                                 $this->query( $sql, $fname );
1124                         }
1125
1126                         $this->insert($table, $row);
1127                         # Now insert the row
1128                         /*$sql = "INSERT INTO $table ( "
1129                                 . $this->makeList( array_keys( $row ), LIST_NAMES )
1130                                 .' ) VALUES ( ' . $this->makeList( $row, LIST_COMMA ) . ' )';
1131                         $this->query( $sql, $fname );*/
1132                 }
1133         }
1134
1135         /**
1136          * Returns the number of rows in the result set
1137          * Has to be called right after the corresponding select query
1138          * @param $res Object result set
1139          * @return Integer: number of rows
1140          */
1141         public function numRows( $res ) {
1142                 if ( $res instanceof ResultWrapper ) {
1143                         $res = $res->result;
1144                 }
1145
1146                 if ( $this->mNumRows ) {
1147                         return $this->mNumRows;
1148                 } else {
1149                         return 0;
1150                 }
1151         }
1152
1153         /**
1154          * Moves the row pointer of the result set
1155          * @param $res Object: result set
1156          * @param $row Integer: row number
1157          * @return success or failure
1158          */
1159         public function dataSeek( $res, $row ) {
1160                 if ( $res instanceof ResultWrapper ) {
1161                         $res = $res->result;
1162                 }
1163                 return db2_fetch_row( $res, $row );
1164         }
1165
1166         ###
1167         # Fix notices in Block.php
1168         ###
1169
1170         /**
1171          * Frees memory associated with a statement resource
1172          * @param $res Object: statement resource to free
1173          * @return Boolean success or failure
1174          */
1175         public function freeResult( $res ) {
1176                 if ( $res instanceof ResultWrapper ) {
1177                         $res = $res->result;
1178                 }
1179                 if ( !@db2_free_result( $res ) ) {
1180                         throw new DBUnexpectedError( $this, "Unable to free DB2 result\n" );
1181                 }
1182         }
1183
1184         /**
1185          * Returns the number of columns in a resource
1186          * @param $res Object: statement resource
1187          * @return Number of fields/columns in resource
1188          */
1189         public function numFields( $res ) {
1190                 if ( $res instanceof ResultWrapper ) {
1191                         $res = $res->result;
1192                 }
1193                 return db2_num_fields( $res );
1194         }
1195
1196         /**
1197          * Returns the nth column name
1198          * @param $res Object: statement resource
1199          * @param $n Integer: Index of field or column
1200          * @return String name of nth column
1201          */
1202         public function fieldName( $res, $n ) {
1203                 if ( $res instanceof ResultWrapper ) {
1204                         $res = $res->result;
1205                 }
1206                 return db2_field_name( $res, $n );
1207         }
1208
1209         /**
1210          * SELECT wrapper
1211          *
1212          * @param $table   Array or string, table name(s) (prefix auto-added)
1213          * @param $vars    Array or string, field name(s) to be retrieved
1214          * @param $conds   Array or string, condition(s) for WHERE
1215          * @param $fname   String: calling function name (use __METHOD__)
1216          *                 for logs/profiling
1217          * @param $options Associative array of options
1218          *                 (e.g. array('GROUP BY' => 'page_title')),
1219          *                 see Database::makeSelectOptions code for list of
1220          *                 supported stuff
1221          * @param $join_conds Associative array of table join conditions (optional)
1222          *                    (e.g. array( 'page' => array('LEFT JOIN',
1223          *                    'page_latest=rev_id') )
1224          * @return Mixed: database result resource for fetch functions or false
1225          *                 on failure
1226          */
1227         public function select( $table, $vars, $conds = '', $fname = 'DatabaseIbm_db2::select', $options = array(), $join_conds = array() )
1228         {
1229                 $res = parent::select( $table, $vars, $conds, $fname, $options,
1230                         $join_conds );
1231
1232                 // We must adjust for offset
1233                 if ( isset( $options['LIMIT'] ) && isset ( $options['OFFSET'] ) ) {
1234                         $limit = $options['LIMIT'];
1235                         $offset = $options['OFFSET'];
1236                 }
1237
1238                 // DB2 does not have a proper num_rows() function yet, so we must emulate
1239                 // DB2 9.5.4 and the corresponding ibm_db2 driver will introduce
1240                 //  a working one
1241                 // TODO: Yay!
1242
1243                 // we want the count
1244                 $vars2 = array( 'count( * ) as num_rows' );
1245                 // respecting just the limit option
1246                 $options2 = array();
1247                 if ( isset( $options['LIMIT'] ) ) {
1248                         $options2['LIMIT'] = $options['LIMIT'];
1249                 }
1250                 // but don't try to emulate for GROUP BY
1251                 if ( isset( $options['GROUP BY'] ) ) {
1252                         return $res;
1253                 }
1254
1255                 $res2 = parent::select( $table, $vars2, $conds, $fname, $options2,
1256                         $join_conds );
1257                 $obj = $this->fetchObject( $res2 );
1258                 $this->mNumRows = $obj->num_rows;
1259
1260                 return $res;
1261         }
1262
1263         /**
1264          * Handles ordering, grouping, and having options ('GROUP BY' => colname)
1265          * Has limited support for per-column options (colnum => 'DISTINCT')
1266          *
1267          * @private
1268          *
1269          * @param $options Associative array of options to be turned into
1270          *              an SQL query, valid keys are listed in the function.
1271          * @return Array
1272          */
1273         function makeSelectOptions( $options ) {
1274                 $preLimitTail = $postLimitTail = '';
1275                 $startOpts = '';
1276
1277                 $noKeyOptions = array();
1278                 foreach ( $options as $key => $option ) {
1279                         if ( is_numeric( $key ) ) {
1280                                 $noKeyOptions[$option] = true;
1281                         }
1282                 }
1283
1284                 if ( isset( $options['GROUP BY'] ) ) {
1285                         $preLimitTail .= " GROUP BY {$options['GROUP BY']}";
1286                 }
1287                 if ( isset( $options['HAVING'] ) ) {
1288                         $preLimitTail .= " HAVING {$options['HAVING']}";
1289                 }
1290                 if ( isset( $options['ORDER BY'] ) ) {
1291                         $preLimitTail .= " ORDER BY {$options['ORDER BY']}";
1292                 }
1293
1294                 if ( isset( $noKeyOptions['DISTINCT'] )
1295                         || isset( $noKeyOptions['DISTINCTROW'] ) )
1296                 {
1297                         $startOpts .= 'DISTINCT';
1298                 }
1299
1300                 return array( $startOpts, '', $preLimitTail, $postLimitTail );
1301         }
1302
1303         /**
1304          * Returns link to IBM DB2 free download
1305          * @return String: wikitext of a link to the server software's web site
1306          */
1307         public static function getSoftwareLink() {
1308                 return '[http://www.ibm.com/db2/express/ IBM DB2]';
1309         }
1310
1311         /**
1312          * Get search engine class. All subclasses of this
1313          * need to implement this if they wish to use searching.
1314          *
1315          * @return String
1316          */
1317         public function getSearchEngine() {
1318                 return 'SearchIBM_DB2';
1319         }
1320
1321         /**
1322          * Did the last database access fail because of deadlock?
1323          * @return Boolean
1324          */
1325         public function wasDeadlock() {
1326                 // get SQLSTATE
1327                 $err = $this->lastErrno();
1328                 switch( $err ) {
1329                         // This is literal port of the MySQL logic and may be wrong for DB2
1330                         case '40001':   // sql0911n, Deadlock or timeout, rollback
1331                         case '57011':   // sql0904n, Resource unavailable, no rollback
1332                         case '57033':   // sql0913n, Deadlock or timeout, no rollback
1333                         $this->installPrint( "In a deadlock because of SQLSTATE $err" );
1334                         return true;
1335                 }
1336                 return false;
1337         }
1338
1339         /**
1340          * Ping the server and try to reconnect if it there is no connection
1341          * The connection may be closed and reopened while this happens
1342          * @return Boolean: whether the connection exists
1343          */
1344         public function ping() {
1345                 // db2_ping() doesn't exist
1346                 // Emulate
1347                 $this->close();
1348                 $this->mConn = $this->openUncataloged( $this->mDBName, $this->mUser,
1349                         $this->mPassword, $this->mServer, $this->mPort );
1350
1351                 return false;
1352         }
1353         ######################################
1354         # Unimplemented and not applicable
1355         ######################################
1356         /**
1357          * Not implemented
1358          * @return string ''
1359          */
1360         public function getStatus( $which = '%' ) {
1361                 $this->installPrint( 'Not implemented for DB2: getStatus()' );
1362                 return '';
1363         }
1364         /**
1365          * Not implemented
1366          * @return string $sql
1367          */
1368         public function limitResultForUpdate( $sql, $num ) {
1369                 $this->installPrint( 'Not implemented for DB2: limitResultForUpdate()' );
1370                 return $sql;
1371         }
1372
1373         /**
1374          * Only useful with fake prepare like in base Database class
1375          * @return      string
1376          */
1377         public function fillPreparedArg( $matches ) {
1378                 $this->installPrint( 'Not useful for DB2: fillPreparedArg()' );
1379                 return '';
1380         }
1381
1382         ######################################
1383         # Reflection
1384         ######################################
1385
1386         /**
1387          * Returns information about an index
1388          * If errors are explicitly ignored, returns NULL on failure
1389          * @param $table String: table name
1390          * @param $index String: index name
1391          * @param $fname String: function name for logging and profiling
1392          * @return Object query row in object form
1393          */
1394         public function indexInfo( $table, $index,
1395                 $fname = 'DatabaseIbm_db2::indexExists' )
1396         {
1397                 $table = $this->tableName( $table );
1398                 $sql = <<<SQL
1399 SELECT name as indexname
1400 FROM sysibm.sysindexes si
1401 WHERE si.name='$index' AND si.tbname='$table'
1402 AND sc.tbcreator='$this->mSchema'
1403 SQL;
1404                 $res = $this->query( $sql, $fname );
1405                 if ( !$res ) {
1406                         return null;
1407                 }
1408                 $row = $this->fetchObject( $res );
1409                 if ( $row != null ) {
1410                         return $row;
1411                 } else {
1412                         return false;
1413                 }
1414         }
1415
1416         /**
1417          * Returns an information object on a table column
1418          * @param $table String: table name
1419          * @param $field String: column name
1420          * @return IBM_DB2Field
1421          */
1422         public function fieldInfo( $table, $field ) {
1423                 return IBM_DB2Field::fromText( $this, $table, $field );
1424         }
1425
1426         /**
1427          * db2_field_type() wrapper
1428          * @param $res Object: result of executed statement
1429          * @param $index Mixed: number or name of the column
1430          * @return String column type
1431          */
1432         public function fieldType( $res, $index ) {
1433                 if ( $res instanceof ResultWrapper ) {
1434                         $res = $res->result;
1435                 }
1436                 return db2_field_type( $res, $index );
1437         }
1438
1439         /**
1440          * Verifies that an index was created as unique
1441          * @param $table String: table name
1442          * @param $index String: index name
1443          * @param $fname function name for profiling
1444          * @return Bool
1445          */
1446         public function indexUnique ( $table, $index,
1447                 $fname = 'DatabaseIbm_db2::indexUnique' )
1448         {
1449                 $table = $this->tableName( $table );
1450                 $sql = <<<SQL
1451 SELECT si.name as indexname
1452 FROM sysibm.sysindexes si
1453 WHERE si.name='$index' AND si.tbname='$table'
1454 AND sc.tbcreator='$this->mSchema'
1455 AND si.uniquerule IN ( 'U', 'P' )
1456 SQL;
1457                 $res = $this->query( $sql, $fname );
1458                 if ( !$res ) {
1459                         return null;
1460                 }
1461                 if ( $this->fetchObject( $res ) ) {
1462                         return true;
1463                 }
1464                 return false;
1465
1466         }
1467
1468         /**
1469          * Returns the size of a text field, or -1 for "unlimited"
1470          * @param $table String: table name
1471          * @param $field String: column name
1472          * @return Integer: length or -1 for unlimited
1473          */
1474         public function textFieldSize( $table, $field ) {
1475                 $table = $this->tableName( $table );
1476                 $sql = <<<SQL
1477 SELECT length as size
1478 FROM sysibm.syscolumns sc
1479 WHERE sc.name='$field' AND sc.tbname='$table'
1480 AND sc.tbcreator='$this->mSchema'
1481 SQL;
1482                 $res = $this->query( $sql );
1483                 $row = $this->fetchObject( $res );
1484                 $size = $row->size;
1485                 return $size;
1486         }
1487
1488         /**
1489          * DELETE where the condition is a join
1490          * @param $delTable String: deleting from this table
1491          * @param $joinTable String: using data from this table
1492          * @param $delVar String: variable in deleteable table
1493          * @param $joinVar String: variable in data table
1494          * @param $conds Array: conditionals for join table
1495          * @param $fname String: function name for profiling
1496          */
1497         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar,
1498                 $conds, $fname = "DatabaseIbm_db2::deleteJoin" )
1499         {
1500                 if ( !$conds ) {
1501                         throw new DBUnexpectedError( $this,
1502                                 'DatabaseIbm_db2::deleteJoin() called with empty $conds' );
1503                 }
1504
1505                 $delTable = $this->tableName( $delTable );
1506                 $joinTable = $this->tableName( $joinTable );
1507                 $sql = <<<SQL
1508 DELETE FROM $delTable
1509 WHERE $delVar IN (
1510   SELECT $joinVar FROM $joinTable
1511
1512 SQL;
1513                 if ( $conds != '*' ) {
1514                         $sql .= 'WHERE ' . $this->makeList( $conds, LIST_AND );
1515                 }
1516                 $sql .= ' )';
1517
1518                 $this->query( $sql, $fname );
1519         }
1520
1521         /**
1522          * Description is left as an exercise for the reader
1523          * @param $b Mixed: data to be encoded
1524          * @return IBM_DB2Blob
1525          */
1526         public function encodeBlob( $b ) {
1527                 return new IBM_DB2Blob( $b );
1528         }
1529
1530         /**
1531          * Description is left as an exercise for the reader
1532          * @param $b IBM_DB2Blob: data to be decoded
1533          * @return mixed
1534          */
1535         public function decodeBlob( $b ) {
1536                 return "$b";
1537         }
1538
1539         /**
1540          * Convert into a list of string being concatenated
1541          * @param $stringList Array: strings that need to be joined together
1542          *                    by the SQL engine
1543          * @return String: joined by the concatenation operator
1544          */
1545         public function buildConcat( $stringList ) {
1546                 // || is equivalent to CONCAT
1547                 // Sample query: VALUES 'foo' CONCAT 'bar' CONCAT 'baz'
1548                 return implode( ' || ', $stringList );
1549         }
1550
1551         /**
1552          * Generates the SQL required to convert a DB2 timestamp into a Unix epoch
1553          * @param $column String: name of timestamp column
1554          * @return String: SQL code
1555          */
1556         public function extractUnixEpoch( $column ) {
1557                 // TODO
1558                 // see SpecialAncientpages
1559         }
1560
1561         ######################################
1562         # Prepared statements
1563         ######################################
1564
1565         /**
1566          * Intended to be compatible with the PEAR::DB wrapper functions.
1567          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
1568          *
1569          * ? = scalar value, quoted as necessary
1570          * ! = raw SQL bit (a function for instance)
1571          * & = filename; reads the file and inserts as a blob
1572          *     (we don't use this though...)
1573          * @param $sql String: SQL statement with appropriate markers
1574          * @param $func String: Name of the function, for profiling
1575          * @return resource a prepared DB2 SQL statement
1576          */
1577         public function prepare( $sql, $func = 'DB2::prepare' ) {
1578                 $stmt = db2_prepare( $this->mConn, $sql, $this->mStmtOptions );
1579                 return $stmt;
1580         }
1581
1582         /**
1583          * Frees resources associated with a prepared statement
1584          * @return Boolean success or failure
1585          */
1586         public function freePrepared( $prepared ) {
1587                 return db2_free_stmt( $prepared );
1588         }
1589
1590         /**
1591          * Execute a prepared query with the various arguments
1592          * @param $prepared String: the prepared sql
1593          * @param $args Mixed: either an array here, or put scalars as varargs
1594          * @return Resource: results object
1595          */
1596         public function execute( $prepared, $args = null ) {
1597                 if( !is_array( $args ) ) {
1598                         # Pull the var args
1599                         $args = func_get_args();
1600                         array_shift( $args );
1601                 }
1602                 $res = db2_execute( $prepared, $args );
1603                 if ( !$res ) {
1604                         $this->installPrint( db2_stmt_errormsg() );
1605                 }
1606                 return $res;
1607         }
1608
1609         /**
1610          * Prepare & execute an SQL statement, quoting and inserting arguments
1611          * in the appropriate places.
1612          * @param $query String
1613          * @param $args ...
1614          */
1615         public function safeQuery( $query, $args = null ) {
1616                 // copied verbatim from Database.php
1617                 $prepared = $this->prepare( $query, 'DB2::safeQuery' );
1618                 if( !is_array( $args ) ) {
1619                         # Pull the var args
1620                         $args = func_get_args();
1621                         array_shift( $args );
1622                 }
1623                 $retval = $this->execute( $prepared, $args );
1624                 $this->freePrepared( $prepared );
1625                 return $retval;
1626         }
1627
1628         /**
1629          * For faking prepared SQL statements on DBs that don't support
1630          * it directly.
1631          * @param $preparedQuery String: a 'preparable' SQL statement
1632          * @param $args Array of arguments to fill it with
1633          * @return String: executable statement
1634          */
1635         public function fillPrepared( $preparedQuery, $args ) {
1636                 reset( $args );
1637                 $this->preparedArgs =& $args;
1638
1639                 foreach ( $args as $i => $arg ) {
1640                         db2_bind_param( $preparedQuery, $i+1, $args[$i] );
1641                 }
1642
1643                 return $preparedQuery;
1644         }
1645
1646         /**
1647          * Switches module between regular and install modes
1648          */
1649         public function setMode( $mode ) {
1650                 $old = $this->mMode;
1651                 $this->mMode = $mode;
1652                 return $old;
1653         }
1654
1655         /**
1656          * Bitwise negation of a column or value in SQL
1657          * Same as (~field) in C
1658          * @param $field String
1659          * @return String
1660          */
1661         function bitNot( $field ) {
1662                 // expecting bit-fields smaller than 4bytes
1663                 return "BITNOT( $field )";
1664         }
1665
1666         /**
1667          * Bitwise AND of two columns or values in SQL
1668          * Same as (fieldLeft & fieldRight) in C
1669          * @param $fieldLeft String
1670          * @param $fieldRight String
1671          * @return String
1672          */
1673         function bitAnd( $fieldLeft, $fieldRight ) {
1674                 return "BITAND( $fieldLeft, $fieldRight )";
1675         }
1676
1677         /**
1678          * Bitwise OR of two columns or values in SQL
1679          * Same as (fieldLeft | fieldRight) in C
1680          * @param $fieldLeft String
1681          * @param $fieldRight String
1682          * @return String
1683          */
1684         function bitOr( $fieldLeft, $fieldRight ) {
1685                 return "BITOR( $fieldLeft, $fieldRight )";
1686         }
1687 }
1688
1689 class IBM_DB2Helper {
1690         public static function makeArray( $maybeArray ) {
1691                 if ( !is_array( $maybeArray ) ) {
1692                         return array( $maybeArray );
1693                 }
1694
1695                 return $maybeArray;
1696         }
1697 }