includes/db/DatabaseIbm_db2.php

   1 <?php
   2 /**
   3  * This is the IBM DB2 database abstraction layer.
   4  * See maintenance/ibm_db2/README for development notes
   5  * and other specific information
   6  *
   7  * @file
   8  * @ingroup Database
   9  * @author leo.petr+mediawiki@gmail.com
  10  */
  11
  12 /**
  13  * This represents a column in a DB2 database
  14  * @ingroup Database
  15  */
  16 class IBM_DB2Field implements Field {
  17         private $name = '';
  18         private $tablename = '';
  19         private $type = '';
  20         private $nullable = false;
  21         private $max_length = 0;
  22
  23         /**
  24          * Builder method for the class
  25          * @param $db DatabaseIbm_db2: Database interface
  26          * @param $table String: table name
  27          * @param $field String: column name
  28          * @return IBM_DB2Field
  29          */
  30         static function fromText( $db, $table, $field ) {
  31                 global $wgDBmwschema;
  32
  33                 $q = <<<SQL
  34 SELECT
  35 lcase( coltype ) AS typname,
  36 nulls AS attnotnull, length AS attlen
  37 FROM sysibm.syscolumns
  38 WHERE tbcreator=%s AND tbname=%s AND name=%s;
  39 SQL;
  40                 $res = $db->query(
  41                         sprintf( $q,
  42                                 $db->addQuotes( $wgDBmwschema ),
  43                                 $db->addQuotes( $table ),
  44                                 $db->addQuotes( $field )
  45                         )
  46                 );
  47                 $row = $db->fetchObject( $res );
  48                 if ( !$row ) {
  49                         return null;
  50                 }
  51                 $n = new IBM_DB2Field;
  52                 $n->type = $row->typname;
  53                 $n->nullable = ( $row->attnotnull == 'N' );
  54                 $n->name = $field;
  55                 $n->tablename = $table;
  56                 $n->max_length = $row->attlen;
  57                 return $n;
  58         }
  59         /**
  60          * Get column name
  61          * @return string column name
  62          */
  63         function name() { return $this->name; }
  64         /**
  65          * Get table name
  66          * @return string table name
  67          */
  68         function tableName() { return $this->tablename; }
  69         /**
  70          * Get column type
  71          * @return string column type
  72          */
  73         function type() { return $this->type; }
  74         /**
  75          * Can column be null?
  76          * @return bool true or false
  77          */
  78         function isNullable() { return $this->nullable; }
  79         /**
  80          * How much can you fit in the column per row?
  81          * @return int length
  82          */
  83         function maxLength() { return $this->max_length; }
  84 }
  85
  86 /**
  87  * Wrapper around binary large objects
  88  * @ingroup Database
  89  */
  90 class IBM_DB2Blob {
  91         private $mData;
  92
  93         public function __construct( $data ) {
  94                 $this->mData = $data;
  95         }
  96
  97         public function getData() {
  98                 return $this->mData;
  99         }
 100
 101         public function __toString() {
 102                 return $this->mData;
 103         }
 104 }
 105
 106 /**
 107  * Primary database interface
 108  * @ingroup Database
 109  */
 110 class DatabaseIbm_db2 extends DatabaseBase {
 111         /*
 112          * Inherited members
 113         protected $mLastQuery = '';
 114         protected $mPHPError = false;
 115
 116         protected $mServer, $mUser, $mPassword, $mConn = null, $mDBname;
 117         protected $mOpened = false;
 118
 119         protected $mTablePrefix;
 120         protected $mFlags;
 121         protected $mTrxLevel = 0;
 122         protected $mErrorCount = 0;
 123         protected $mLBInfo = array();
 124         protected $mFakeSlaveLag = null, $mFakeMaster = false;
 125          *
 126          */
 127
 128         /** Database server port */
 129         protected $mPort = null;
 130         /** Schema for tables, stored procedures, triggers */
 131         protected $mSchema = null;
 132         /** Whether the schema has been applied in this session */
 133         protected $mSchemaSet = false;
 134         /** Result of last query */
 135         protected $mLastResult = null;
 136         /** Number of rows affected by last INSERT/UPDATE/DELETE */
 137         protected $mAffectedRows = null;
 138         /** Number of rows returned by last SELECT */
 139         protected $mNumRows = null;
 140
 141         /** Connection config options - see constructor */
 142         public $mConnOptions = array();
 143         /** Statement config options -- see constructor */
 144         public $mStmtOptions = array();
 145
 146         /** Default schema */
 147         const USE_GLOBAL = 'mediawiki';
 148
 149         /** Option that applies to nothing */
 150         const NONE_OPTION = 0x00;
 151         /** Option that applies to connection objects */
 152         const CONN_OPTION = 0x01;
 153         /** Option that applies to statement objects */
 154         const STMT_OPTION = 0x02;
 155
 156         /** Regular operation mode -- minimal debug messages */
 157         const REGULAR_MODE = 'regular';
 158         /** Installation mode -- lots of debug messages */
 159         const INSTALL_MODE = 'install';
 160
 161         /** Controls the level of debug message output */
 162         protected $mMode = self::REGULAR_MODE;
 163
 164         /** Last sequence value used for a primary key */
 165         protected $mInsertId = null;
 166
 167         ######################################
 168         # Getters and Setters
 169         ######################################
 170
 171         /**
 172          * Returns true if this database supports (and uses) cascading deletes
 173          */
 174         function cascadingDeletes() {
 175                 return true;
 176         }
 177
 178         /**
 179          * Returns true if this database supports (and uses) triggers (e.g. on the
 180          *  page table)
 181          */
 182         function cleanupTriggers() {
 183                 return true;
 184         }
 185
 186         /**
 187          * Returns true if this database is strict about what can be put into an
 188          *  IP field.
 189          * Specifically, it uses a NULL value instead of an empty string.
 190          */
 191         function strictIPs() {
 192                 return true;
 193         }
 194
 195         /**
 196          * Returns true if this database uses timestamps rather than integers
 197         */
 198         function realTimestamps() {
 199                 return true;
 200         }
 201
 202         /**
 203          * Returns true if this database does an implicit sort when doing GROUP BY
 204          */
 205         function implicitGroupby() {
 206                 return false;
 207         }
 208
 209         /**
 210          * Returns true if this database does an implicit order by when the column
 211          *  has an index
 212          * For example: SELECT page_title FROM page LIMIT 1
 213          */
 214         function implicitOrderby() {
 215                 return false;
 216         }
 217
 218         /**
 219          * Returns true if this database can do a native search on IP columns
 220          * e.g. this works as expected: .. WHERE rc_ip = '127.42.12.102/32';
 221          */
 222         function searchableIPs() {
 223                 return true;
 224         }
 225
 226         /**
 227          * Returns true if this database can use functional indexes
 228          */
 229         function functionalIndexes() {
 230                 return true;
 231         }
 232
 233         /**
 234          * Returns a unique string representing the wiki on the server
 235          */
 236         function getWikiID() {
 237                 if( $this->mSchema ) {
 238                         return "{$this->mDBname}-{$this->mSchema}";
 239                 } else {
 240                         return $this->mDBname;
 241                 }
 242         }
 243
 244         function getType() {
 245                 return 'ibm_db2';
 246         }
 247
 248         ######################################
 249         # Setup
 250         ######################################
 251
 252
 253         /**
 254          *
 255          * @param $server String: hostname of database server
 256          * @param $user String: username
 257          * @param $password String: password
 258          * @param $dbName String: database name on the server
 259          * @param $flags Integer: database behaviour flags (optional, unused)
 260          * @param $schema String
 261          */
 262         public function __construct( $server = false, $user = false,
 263                                                         $password = false,
 264                                                         $dbName = false, $flags = 0,
 265                                                         $schema = self::USE_GLOBAL )
 266         {
 267                 global $wgDBmwschema;
 268
 269                 if ( $schema == self::USE_GLOBAL ) {
 270                         $this->mSchema = $wgDBmwschema;
 271                 } else {
 272                         $this->mSchema = $schema;
 273                 }
 274
 275                 // configure the connection and statement objects
 276                 $this->setDB2Option( 'db2_attr_case', 'DB2_CASE_LOWER',
 277                         self::CONN_OPTION | self::STMT_OPTION );
 278                 $this->setDB2Option( 'deferred_prepare', 'DB2_DEFERRED_PREPARE_ON',
 279                         self::STMT_OPTION );
 280                 $this->setDB2Option( 'rowcount', 'DB2_ROWCOUNT_PREFETCH_ON',
 281                         self::STMT_OPTION );
 282
 283                 parent::__construct( $server, $user, $password, $dbName, $flags );
 284         }
 285
 286         /**
 287          * Enables options only if the ibm_db2 extension version supports them
 288          * @param $name String: name of the option in the options array
 289          * @param $const String: name of the constant holding the right option value
 290          * @param $type Integer: whether this is a Connection or Statement otion
 291          */
 292         private function setDB2Option( $name, $const, $type ) {
 293                 if ( defined( $const ) ) {
 294                         if ( $type & self::CONN_OPTION ) {
 295                                 $this->mConnOptions[$name] = constant( $const );
 296                         }
 297                         if ( $type & self::STMT_OPTION ) {
 298                                 $this->mStmtOptions[$name] = constant( $const );
 299                         }
 300                 } else {
 301                         $this->installPrint(
 302                                 "$const is not defined. ibm_db2 version is likely too low." );
 303                 }
 304         }
 305
 306         /**
 307          * Outputs debug information in the appropriate place
 308          * @param $string String: the relevant debug message
 309          */
 310         private function installPrint( $string ) {
 311                 wfDebug( "$string\n" );
 312                 if ( $this->mMode == self::INSTALL_MODE ) {
 313                         print "<li><pre>$string</pre></li>";
 314                         flush();
 315                 }
 316         }
 317
 318         /**
 319          * Opens a database connection and returns it
 320          * Closes any existing connection
 321          *
 322          * @param $server String: hostname
 323          * @param $user String
 324          * @param $password String
 325          * @param $dbName String: database name
 326          * @return a fresh connection
 327          */
 328         public function open( $server, $user, $password, $dbName ) {
 329                 // Load the port number
 330                 global $wgDBport;
 331                 wfProfileIn( __METHOD__ );
 332
 333                 // Load IBM DB2 driver if missing
 334                 wfDl( 'ibm_db2' );
 335
 336                 // Test for IBM DB2 support, to avoid suppressed fatal error
 337                 if ( !function_exists( 'db2_connect' ) ) {
 338                         $error = <<<ERROR
 339 DB2 functions missing, have you enabled the ibm_db2 extension for PHP?
 340
 341 ERROR;
 342                         $this->installPrint( $error );
 343                         $this->reportConnectionError( $error );
 344                 }
 345
 346                 if ( strlen( $user ) < 1 ) {
 347                         return null;
 348                 }
 349
 350                 // Close existing connection
 351                 $this->close();
 352                 // Cache conn info
 353                 $this->mServer = $server;
 354                 $this->mPort = $port = $wgDBport;
 355                 $this->mUser = $user;
 356                 $this->mPassword = $password;
 357                 $this->mDBname = $dbName;
 358
 359                 $this->openUncataloged( $dbName, $user, $password, $server, $port );
 360
 361                 // Apply connection config
 362                 db2_set_option( $this->mConn, $this->mConnOptions, 1 );
 363                 // Some MediaWiki code is still transaction-less (?).
 364                 // The strategy is to keep AutoCommit on for that code
 365                 //  but switch it off whenever a transaction is begun.
 366                 db2_autocommit( $this->mConn, DB2_AUTOCOMMIT_ON );
 367
 368                 if ( !$this->mConn ) {
 369                         $this->installPrint( "DB connection error\n" );
 370                         $this->installPrint(
 371                                 "Server: $server, Database: $dbName, User: $user, Password: "
 372                                 . substr( $password, 0, 3 ) . "...\n" );
 373                         $this->installPrint( $this->lastError() . "\n" );
 374                         return null;
 375                 }
 376
 377                 $this->mOpened = true;
 378                 $this->applySchema();
 379
 380                 wfProfileOut( __METHOD__ );
 381                 return $this->mConn;
 382         }
 383
 384         /**
 385          * Opens a cataloged database connection, sets mConn
 386          */
 387         protected function openCataloged( $dbName, $user, $password ) {
 388                 @$this->mConn = db2_pconnect( $dbName, $user, $password );
 389         }
 390
 391         /**
 392          * Opens an uncataloged database connection, sets mConn
 393          */
 394         protected function openUncataloged( $dbName, $user, $password, $server, $port )
 395         {
 396                 $str = "DRIVER={IBM DB2 ODBC DRIVER};";
 397                 $str .= "DATABASE=$dbName;";
 398                 $str .= "HOSTNAME=$server;";
 399                 // port was formerly validated to not be 0
 400                 $str .= "PORT=$port;";
 401                 $str .= "PROTOCOL=TCPIP;";
 402                 $str .= "UID=$user;";
 403                 $str .= "PWD=$password;";
 404
 405                 @$this->mConn = db2_pconnect( $str, $user, $password );
 406         }
 407
 408         /**
 409          * Closes a database connection, if it is open
 410          * Returns success, true if already closed
 411          */
 412         public function close() {
 413                 $this->mOpened = false;
 414                 if ( $this->mConn ) {
 415                         if ( $this->trxLevel() > 0 ) {
 416                                 $this->commit();
 417                         }
 418                         return db2_close( $this->mConn );
 419                 } else {
 420                         return true;
 421                 }
 422         }
 423
 424         /**
 425          * Retrieves the most current database error
 426          * Forces a database rollback
 427          */
 428         public function lastError() {
 429                 $connerr = db2_conn_errormsg();
 430                 if ( $connerr ) {
 431                         //$this->rollback();
 432                         return $connerr;
 433                 }
 434                 $stmterr = db2_stmt_errormsg();
 435                 if ( $stmterr ) {
 436                         //$this->rollback();
 437                         return $stmterr;
 438                 }
 439
 440                 return false;
 441         }
 442
 443         /**
 444          * Get the last error number
 445          * Return 0 if no error
 446          * @return integer
 447          */
 448         public function lastErrno() {
 449                 $connerr = db2_conn_error();
 450                 if ( $connerr ) {
 451                         return $connerr;
 452                 }
 453                 $stmterr = db2_stmt_error();
 454                 if ( $stmterr ) {
 455                         return $stmterr;
 456                 }
 457                 return 0;
 458         }
 459
 460         /**
 461          * Is a database connection open?
 462          * @return
 463          */
 464         public function isOpen() { return $this->mOpened; }
 465
 466         /**
 467          * The DBMS-dependent part of query()
 468          * @param  $sql String: SQL query.
 469          * @return object Result object for fetch functions or false on failure
 470          * @access private
 471          */
 472         /*private*/
 473         public function doQuery( $sql ) {
 474                 $this->applySchema();
 475
 476                 $ret = db2_exec( $this->mConn, $sql, $this->mStmtOptions );
 477                 if( $ret == false ) {
 478                         $error = db2_stmt_errormsg();
 479                         $this->installPrint( "<pre>$sql</pre>" );
 480                         $this->installPrint( $error );
 481                         throw new DBUnexpectedError( $this, 'SQL error: '
 482                                 . htmlspecialchars( $error ) );
 483                 }
 484                 $this->mLastResult = $ret;
 485                 $this->mAffectedRows = null; // Not calculated until asked for
 486                 return $ret;
 487         }
 488
 489         /**
 490          * @return string Version information from the database
 491          */
 492         public function getServerVersion() {
 493                 $info = db2_server_info( $this->mConn );
 494                 return $info->DBMS_VER;
 495         }
 496
 497         /**
 498          * Queries whether a given table exists
 499          * @return boolean
 500          */
 501         public function tableExists( $table ) {
 502                 $schema = $this->mSchema;
 503                 $sql = <<< EOF
 504 SELECT COUNT( * ) FROM SYSIBM.SYSTABLES ST
 505 WHERE ST.NAME = '$table' AND ST.CREATOR = '$schema'
 506 EOF;
 507                 $res = $this->query( $sql );
 508                 if ( !$res ) {
 509                         return false;
 510                 }
 511
 512                 // If the table exists, there should be one of it
 513                 @$row = $this->fetchRow( $res );
 514                 $count = $row[0];
 515                 if ( $count == '1' || $count == 1 ) {
 516                         return true;
 517                 }
 518
 519                 return false;
 520         }
 521
 522         /**
 523          * Fetch the next row from the given result object, in object form.
 524          * Fields can be retrieved with $row->fieldname, with fields acting like
 525          * member variables.
 526          *
 527          * @param $res SQL result object as returned from Database::query(), etc.
 528          * @return DB2 row object
 529          * @throws DBUnexpectedError Thrown if the database returns an error
 530          */
 531         public function fetchObject( $res ) {
 532                 if ( $res instanceof ResultWrapper ) {
 533                         $res = $res->result;
 534                 }
 535                 @$row = db2_fetch_object( $res );
 536                 if( $this->lastErrno() ) {
 537                         throw new DBUnexpectedError( $this, 'Error in fetchObject(): '
 538                                 . htmlspecialchars( $this->lastError() ) );
 539                 }
 540                 return $row;
 541         }
 542
 543         /**
 544          * Fetch the next row from the given result object, in associative array
 545          * form. Fields are retrieved with $row['fieldname'].
 546          *
 547          * @param $res SQL result object as returned from Database::query(), etc.
 548          * @return DB2 row object
 549          * @throws DBUnexpectedError Thrown if the database returns an error
 550          */
 551         public function fetchRow( $res ) {
 552                 if ( $res instanceof ResultWrapper ) {
 553                         $res = $res->result;
 554                 }
 555                 @$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
 563         /**
 564          * Create tables, stored procedures, and so on
 565          */
 566         public function setup_database() {
 567                 try {
 568                         // TODO: switch to root login if available
 569
 570                         // Switch into the correct namespace
 571                         $this->applySchema();
 572                         $this->begin();
 573
 574                         $res = $this->sourceFile( "../maintenance/ibm_db2/tables.sql" );
 575                         if ( $res !== true ) {
 576                                 print ' <b>FAILED</b>: ' . htmlspecialchars( $res ) . '</li>';
 577                         } else {
 578                                 print ' done</li>';
 579                         }
 580                         $res = $this->sourceFile( "../maintenance/ibm_db2/foreignkeys.sql" );
 581                         if ( $res !== true ) {
 582                                 print ' <b>FAILED</b>: ' . htmlspecialchars( $res ) . '</li>';
 583                         } else {
 584                                 print '<li>Foreign keys done</li>';
 585                         }
 586
 587                         // TODO: populate interwiki links
 588
 589                         if ( $this->lastError() ) {
 590                                 $this->installPrint(
 591                                         'Errors encountered during table creation -- rolled back' );
 592                                 $this->installPrint( 'Please install again' );
 593                                 $this->rollback();
 594                         } else {
 595                                 $this->commit();
 596                         }
 597                 } catch ( MWException $mwe ) {
 598                         print "<br><pre>$mwe</pre><br>";
 599                 }
 600         }
 601
 602         /**
 603          * Escapes strings
 604          * Doesn't escape numbers
 605          *
 606          * @param $s String: string to escape
 607          * @return escaped string
 608          */
 609         public function addQuotes( $s ) {
 610                 //$this->installPrint( "DB2::addQuotes( $s )\n" );
 611                 if ( is_null( $s ) ) {
 612                         return 'NULL';
 613                 } elseif ( $s instanceof Blob ) {
 614                         return "'" . $s->fetch( $s ) . "'";
 615                 } elseif ( $s instanceof IBM_DB2Blob ) {
 616                         return "'" . $this->decodeBlob( $s ) . "'";
 617                 }
 618                 $s = $this->strencode( $s );
 619                 if ( is_numeric( $s ) ) {
 620                         return $s;
 621                 } else {
 622                         return "'$s'";
 623                 }
 624         }
 625
 626         /**
 627          * Verifies that a DB2 column/field type is numeric
 628          *
 629          * @param $type String: DB2 column type
 630          * @return Boolean: true if numeric
 631          */
 632         public function is_numeric_type( $type ) {
 633                 switch ( strtoupper( $type ) ) {
 634                         case 'SMALLINT':
 635                         case 'INTEGER':
 636                         case 'INT':
 637                         case 'BIGINT':
 638                         case 'DECIMAL':
 639                         case 'REAL':
 640                         case 'DOUBLE':
 641                         case 'DECFLOAT':
 642                                 return true;
 643                 }
 644                 return false;
 645         }
 646
 647         /**
 648          * Alias for addQuotes()
 649          * @param $s String: string to escape
 650          * @return escaped string
 651          */
 652         public function strencode( $s ) {
 653                 // Bloody useless function
 654                 //  Prepends backslashes to \x00, \n, \r, \, ', " and \x1a.
 655                 //  But also necessary
 656                 $s = db2_escape_string( $s );
 657                 // Wide characters are evil -- some of them look like '
 658                 $s = utf8_encode( $s );
 659                 // Fix its stupidity
 660                 $from = array(  "\\\\", "\\'",  '\\n',  '\\t',  '\\"',  '\\r' );
 661                 $to = array(            "\\",           "''",           "\n",           "\t",           '"',            "\r" );
 662                 $s = str_replace( $from, $to, $s ); // DB2 expects '', not \' escaping
 663                 return $s;
 664         }
 665
 666         /**
 667          * Switch into the database schema
 668          */
 669         protected function applySchema() {
 670                 if ( !( $this->mSchemaSet ) ) {
 671                         $this->mSchemaSet = true;
 672                         $this->begin();
 673                         $this->doQuery( "SET SCHEMA = $this->mSchema" );
 674                         $this->commit();
 675                 }
 676         }
 677
 678         /**
 679          * Start a transaction (mandatory)
 680          */
 681         public function begin( $fname = 'DatabaseIbm_db2::begin' ) {
 682                 // BEGIN is implicit for DB2
 683                 // However, it requires that AutoCommit be off.
 684
 685                 // Some MediaWiki code is still transaction-less (?).
 686                 // The strategy is to keep AutoCommit on for that code
 687                 //  but switch it off whenever a transaction is begun.
 688                 db2_autocommit( $this->mConn, DB2_AUTOCOMMIT_OFF );
 689
 690                 $this->mTrxLevel = 1;
 691         }
 692
 693         /**
 694          * End a transaction
 695          * Must have a preceding begin()
 696          */
 697         public function commit( $fname = 'DatabaseIbm_db2::commit' ) {
 698                 db2_commit( $this->mConn );
 699
 700                 // Some MediaWiki code is still transaction-less (?).
 701                 // The strategy is to keep AutoCommit on for that code
 702                 //  but switch it off whenever a transaction is begun.
 703                 db2_autocommit( $this->mConn, DB2_AUTOCOMMIT_ON );
 704
 705                 $this->mTrxLevel = 0;
 706         }
 707
 708         /**
 709          * Cancel a transaction
 710          */
 711         public function rollback( $fname = 'DatabaseIbm_db2::rollback' ) {
 712                 db2_rollback( $this->mConn );
 713                 // turn auto-commit back on
 714                 // not sure if this is appropriate
 715                 db2_autocommit( $this->mConn, DB2_AUTOCOMMIT_ON );
 716                 $this->mTrxLevel = 0;
 717         }
 718
 719         /**
 720          * Makes an encoded list of strings from an array
 721          * $mode:
 722          *   LIST_COMMA         - comma separated, no field names
 723          *   LIST_AND           - ANDed WHERE clause (without the WHERE)
 724          *   LIST_OR            - ORed WHERE clause (without the WHERE)
 725          *   LIST_SET           - comma separated with field names, like a SET clause
 726          *   LIST_NAMES         - comma separated field names
 727          *   LIST_SET_PREPARED  - like LIST_SET, except with ? tokens as values
 728          */
 729         function makeList( $a, $mode = LIST_COMMA ) {
 730                 if ( !is_array( $a ) ) {
 731                         throw new DBUnexpectedError( $this,
 732                                 'DatabaseIbm_db2::makeList called with incorrect parameters' );
 733                 }
 734
 735                 // if this is for a prepared UPDATE statement
 736                 // (this should be promoted to the parent class
 737                 //  once other databases use prepared statements)
 738                 if ( $mode == LIST_SET_PREPARED ) {
 739                         $first = true;
 740                         $list = '';
 741                         foreach ( $a as $field => $value ) {
 742                                 if ( !$first ) {
 743                                         $list .= ", $field = ?";
 744                                 } else {
 745                                         $list .= "$field = ?";
 746                                         $first = false;
 747                                 }
 748                         }
 749                         $list .= '';
 750
 751                         return $list;
 752                 }
 753
 754                 // otherwise, call the usual function
 755                 return parent::makeList( $a, $mode );
 756         }
 757
 758         /**
 759          * Construct a LIMIT query with optional offset
 760          * This is used for query pages
 761          *
 762          * @param $sql string SQL query we will append the limit too
 763          * @param $limit integer the SQL limit
 764          * @param $offset integer the SQL offset (default false)
 765          */
 766         public function limitResult( $sql, $limit, $offset=false ) {
 767                 if( !is_numeric( $limit ) ) {
 768                         throw new DBUnexpectedError( $this,
 769                                 "Invalid non-numeric limit passed to limitResult()\n" );
 770                 }
 771                 if( $offset ) {
 772                         if ( stripos( $sql, 'where' ) === false ) {
 773                                 return "$sql AND ( ROWNUM BETWEEN $offset AND $offset+$limit )";
 774                         } else {
 775                                 return "$sql WHERE ( ROWNUM BETWEEN $offset AND $offset+$limit )";
 776                         }
 777                 }
 778                 return "$sql FETCH FIRST $limit ROWS ONLY ";
 779         }
 780
 781         /**
 782          * Handle reserved keyword replacement in table names
 783          *
 784          * @param $name Object
 785          * @return String
 786          */
 787         public function tableName( $name ) {
 788                 // we want maximum compatibility with MySQL schema
 789                 return $name;
 790         }
 791
 792         /**
 793          * Generates a timestamp in an insertable format
 794          *
 795          * @param $ts timestamp
 796          * @return String: timestamp value
 797          */
 798         public function timestamp( $ts = 0 ) {
 799                 // TS_MW cannot be easily distinguished from an integer
 800                 return wfTimestamp( TS_DB2, $ts );
 801         }
 802
 803         /**
 804          * Return the next in a sequence, save the value for retrieval via insertId()
 805          * @param $seqName String: name of a defined sequence in the database
 806          * @return next value in that sequence
 807          */
 808         public function nextSequenceValue( $seqName ) {
 809                 // Not using sequences in the primary schema to allow for easier migration
 810                 //  from MySQL
 811                 // Emulating MySQL behaviour of using NULL to signal that sequences
 812                 // aren't used
 813                 /*
 814                 $safeseq = preg_replace( "/'/", "''", $seqName );
 815                 $res = $this->query( "VALUES NEXTVAL FOR $safeseq" );
 816                 $row = $this->fetchRow( $res );
 817                 $this->mInsertId = $row[0];
 818                 return $this->mInsertId;
 819                 */
 820                 return null;
 821         }
 822
 823         /**
 824          * This must be called after nextSequenceVal
 825          * @return Last sequence value used as a primary key
 826          */
 827         public function insertId() {
 828                 return $this->mInsertId;
 829         }
 830
 831         /**
 832          * Updates the mInsertId property with the value of the last insert
 833          *  into a generated column
 834          *
 835          * @param $table      String: sanitized table name
 836          * @param $primaryKey Mixed: string name of the primary key
 837          * @param $stmt       Resource: prepared statement resource
 838          *  of the SELECT primary_key FROM FINAL TABLE ( INSERT ... ) form
 839          */
 840         private function calcInsertId( $table, $primaryKey, $stmt ) {
 841                 if ( $primaryKey ) {
 842                         $this->mInsertId = db2_last_insert_id( $this->mConn );
 843                 }
 844         }
 845
 846         /**
 847          * INSERT wrapper, inserts an array into a table
 848          *
 849          * $args may be a single associative array, or an array of arrays
 850          *  with numeric keys, for multi-row insert
 851          *
 852          * @param $table   String: Name of the table to insert to.
 853          * @param $args    Array: Items to insert into the table.
 854          * @param $fname   String: Name of the function, for profiling
 855          * @param $options String or Array. Valid options: IGNORE
 856          *
 857          * @return bool Success of insert operation. IGNORE always returns true.
 858          */
 859         public function insert( $table, $args, $fname = 'DatabaseIbm_db2::insert',
 860                 $options = array() )
 861         {
 862                 if ( !count( $args ) ) {
 863                         return true;
 864                 }
 865                 // get database-specific table name (not used)
 866                 $table = $this->tableName( $table );
 867                 // format options as an array
 868                 $options = IBM_DB2Helper::makeArray( $options );
 869                 // format args as an array of arrays
 870                 if ( !( isset( $args[0] ) && is_array( $args[0] ) ) ) {
 871                         $args = array( $args );
 872                 }
 873
 874                 // prevent insertion of NULL into primary key columns
 875                 list( $args, $primaryKeys ) = $this->removeNullPrimaryKeys( $table, $args );
 876                 // if there's only one primary key
 877                 // we'll be able to read its value after insertion
 878                 $primaryKey = false;
 879                 if ( count( $primaryKeys ) == 1 ) {
 880                         $primaryKey = $primaryKeys[0];
 881                 }
 882
 883                 // get column names
 884                 $keys = array_keys( $args[0] );
 885                 $key_count = count( $keys );
 886
 887                 // If IGNORE is set, we use savepoints to emulate mysql's behavior
 888                 $ignore = in_array( 'IGNORE', $options ) ? 'mw' : '';
 889
 890                 // assume success
 891                 $res = true;
 892                 // If we are not in a transaction, we need to be for savepoint trickery
 893                 if ( !$this->mTrxLevel ) {
 894                         $this->begin();
 895                 }
 896
 897                 $sql = "INSERT INTO $table ( " . implode( ',', $keys ) . ' ) VALUES ';
 898                 if ( $key_count == 1 ) {
 899                         $sql .= '( ? )';
 900                 } else {
 901                         $sql .= '( ?' . str_repeat( ',?', $key_count-1 ) . ' )';
 902                 }
 903                 //$this->installPrint( "Preparing the following SQL:" );
 904                 //$this->installPrint( "$sql" );
 905                 //$this->installPrint( print_r( $args, true ));
 906                 $stmt = $this->prepare( $sql );
 907
 908                 // start a transaction/enter transaction mode
 909                 $this->begin();
 910
 911                 if ( !$ignore ) {
 912                         //$first = true;
 913                         foreach ( $args as $row ) {
 914                                 //$this->installPrint( "Inserting " . print_r( $row, true ));
 915                                 // insert each row into the database
 916                                 $res = $res & $this->execute( $stmt, $row );
 917                                 if ( !$res ) {
 918                                         $this->installPrint( 'Last error:' );
 919                                         $this->installPrint( $this->lastError() );
 920                                 }
 921                                 // get the last inserted value into a generated column
 922                                 $this->calcInsertId( $table, $primaryKey, $stmt );
 923                         }
 924                 } else {
 925                         $olde = error_reporting( 0 );
 926                         // For future use, we may want to track the number of actual inserts
 927                         // Right now, insert (all writes) simply return true/false
 928                         $numrowsinserted = 0;
 929
 930                         // always return true
 931                         $res = true;
 932
 933                         foreach ( $args as $row ) {
 934                                 $overhead = "SAVEPOINT $ignore ON ROLLBACK RETAIN CURSORS";
 935                                 db2_exec( $this->mConn, $overhead, $this->mStmtOptions );
 936
 937                                 $this->execute( $stmt, $row );
 938
 939                                 if ( !$res2 ) {
 940                                         $this->installPrint( 'Last error:' );
 941                                         $this->installPrint( $this->lastError() );
 942                                 }
 943                                 // get the last inserted value into a generated column
 944                                 $this->calcInsertId( $table, $primaryKey, $stmt );
 945
 946                                 $errNum = $this->lastErrno();
 947                                 if ( $errNum ) {
 948                                         db2_exec( $this->mConn, "ROLLBACK TO SAVEPOINT $ignore",
 949                                                 $this->mStmtOptions );
 950                                 } else {
 951                                         db2_exec( $this->mConn, "RELEASE SAVEPOINT $ignore",
 952                                                 $this->mStmtOptions );
 953                                         $numrowsinserted++;
 954                                 }
 955                         }
 956
 957                         $olde = error_reporting( $olde );
 958                         // Set the affected row count for the whole operation
 959                         $this->mAffectedRows = $numrowsinserted;
 960                 }
 961                 // commit either way
 962                 $this->commit();
 963                 $this->freePrepared( $stmt );
 964
 965                 return $res;
 966         }
 967
 968         /**
 969          * Given a table name and a hash of columns with values
 970          * Removes primary key columns from the hash where the value is NULL
 971          *
 972          * @param $table String: name of the table
 973          * @param $args Array of hashes of column names with values
 974          * @return Array: tuple( filtered array of columns, array of primary keys )
 975          */
 976         private function removeNullPrimaryKeys( $table, $args ) {
 977                 $schema = $this->mSchema;
 978                 // find out the primary keys
 979                 $keyres = db2_primary_keys( $this->mConn, null, strtoupper( $schema ),
 980                         strtoupper( $table )
 981                 );
 982                 $keys = array();
 983                 for (
 984                         $row = $this->fetchObject( $keyres );
 985                         $row != null;
 986                         $row = $this->fetchObject( $keyres )
 987                 )
 988                 {
 989                         $keys[] = strtolower( $row->column_name );
 990                 }
 991                 // remove primary keys
 992                 foreach ( $args as $ai => $row ) {
 993                         foreach ( $keys as $key ) {
 994                                 if ( $row[$key] == null ) {
 995                                         unset( $row[$key] );
 996                                 }
 997                         }
 998                         $args[$ai] = $row;
 999                 }
1000                 // return modified hash
1001                 return array( $args, $keys );
1002         }
1003
1004         /**
1005          * UPDATE wrapper, takes a condition array and a SET array
1006          *
1007          * @param $table  String: The table to UPDATE
1008          * @param $values An array of values to SET
1009          * @param $conds  An array of conditions ( WHERE ). Use '*' to update all rows.
1010          * @param $fname  String: The Class::Function calling this function
1011          *                ( for the log )
1012          * @param $options An array of UPDATE options, can be one or
1013          *                 more of IGNORE, LOW_PRIORITY
1014          * @return Boolean
1015          */
1016         public function update( $table, $values, $conds, $fname = 'DatabaseIbm_db2::update',
1017                 $options = array() )
1018         {
1019                 $table = $this->tableName( $table );
1020                 $opts = $this->makeUpdateOptions( $options );
1021                 $sql = "UPDATE $opts $table SET "
1022                         . $this->makeList( $values, LIST_SET_PREPARED );
1023                 if ( $conds != '*' ) {
1024                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1025                 }
1026                 $stmt = $this->prepare( $sql );
1027                 $this->installPrint( 'UPDATE: ' . print_r( $values, true ) );
1028                 // assuming for now that an array with string keys will work
1029                 // if not, convert to simple array first
1030                 $result = $this->execute( $stmt, $values );
1031                 $this->freePrepared( $stmt );
1032
1033                 return $result;
1034         }
1035
1036         /**
1037          * DELETE query wrapper
1038          *
1039          * Use $conds == "*" to delete all rows
1040          */
1041         public function delete( $table, $conds, $fname = 'DatabaseIbm_db2::delete' ) {
1042                 if ( !$conds ) {
1043                         throw new DBUnexpectedError( $this,
1044                                 'DatabaseIbm_db2::delete() called with no conditions' );
1045                 }
1046                 $table = $this->tableName( $table );
1047                 $sql = "DELETE FROM $table";
1048                 if ( $conds != '*' ) {
1049                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1050                 }
1051                 $result = $this->query( $sql, $fname );
1052
1053                 return $result;
1054         }
1055
1056         /**
1057          * Returns the number of rows affected by the last query or 0
1058          * @return Integer: the number of rows affected by the last query
1059          */
1060         public function affectedRows() {
1061                 if ( !is_null( $this->mAffectedRows ) ) {
1062                         // Forced result for simulated queries
1063                         return $this->mAffectedRows;
1064                 }
1065                 if( empty( $this->mLastResult ) ) {
1066                         return 0;
1067                 }
1068                 return db2_num_rows( $this->mLastResult );
1069         }
1070
1071         /**
1072          * Simulates REPLACE with a DELETE followed by INSERT
1073          * @param $table Object
1074          * @param $uniqueIndexes Array consisting of indexes and arrays of indexes
1075          * @param $rows Array: rows to insert
1076          * @param $fname String: name of the function for profiling
1077          * @return nothing
1078          */
1079         function replace( $table, $uniqueIndexes, $rows,
1080                 $fname = 'DatabaseIbm_db2::replace' )
1081         {
1082                 $table = $this->tableName( $table );
1083
1084                 if ( count( $rows )==0 ) {
1085                         return;
1086                 }
1087
1088                 # Single row case
1089                 if ( !is_array( reset( $rows ) ) ) {
1090                         $rows = array( $rows );
1091                 }
1092
1093                 foreach( $rows as $row ) {
1094                         # Delete rows which collide
1095                         if ( $uniqueIndexes ) {
1096                                 $sql = "DELETE FROM $table WHERE ";
1097                                 $first = true;
1098                                 foreach ( $uniqueIndexes as $index ) {
1099                                         if ( $first ) {
1100                                                 $first = false;
1101                                                 $sql .= '( ';
1102                                         } else {
1103                                                 $sql .= ' ) OR ( ';
1104                                         }
1105                                         if ( is_array( $index ) ) {
1106                                                 $first2 = true;
1107                                                 foreach ( $index as $col ) {
1108                                                         if ( $first2 ) {
1109                                                                 $first2 = false;
1110                                                         } else {
1111                                                                 $sql .= ' AND ';
1112                                                         }
1113                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
1114                                                 }
1115                                         } else {
1116                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
1117                                         }
1118                                 }
1119                                 $sql .= ' )';
1120                                 $this->query( $sql, $fname );
1121                         }
1122
1123                         # Now insert the row
1124                         $sql = "INSERT INTO $table ( "
1125                                 . $this->makeList( array_keys( $row ), LIST_NAMES )
1126                                 .' ) VALUES ( ' . $this->makeList( $row, LIST_COMMA ) . ' )';
1127                         $this->query( $sql, $fname );
1128                 }
1129         }
1130
1131         /**
1132          * Returns the number of rows in the result set
1133          * Has to be called right after the corresponding select query
1134          * @param $res Object result set
1135          * @return Integer: number of rows
1136          */
1137         public function numRows( $res ) {
1138                 if ( $res instanceof ResultWrapper ) {
1139                         $res = $res->result;
1140                 }
1141                 if ( $this->mNumRows ) {
1142                         return $this->mNumRows;
1143                 } else {
1144                         return 0;
1145                 }
1146         }
1147
1148         /**
1149          * Moves the row pointer of the result set
1150          * @param $res Object: result set
1151          * @param $row Integer: row number
1152          * @return success or failure
1153          */
1154         public function dataSeek( $res, $row ) {
1155                 if ( $res instanceof ResultWrapper ) {
1156                         $res = $res->result;
1157                 }
1158                 return db2_fetch_row( $res, $row );
1159         }
1160
1161         ###
1162         # Fix notices in Block.php
1163         ###
1164
1165         /**
1166          * Frees memory associated with a statement resource
1167          * @param $res Object: statement resource to free
1168          * @return Boolean success or failure
1169          */
1170         public function freeResult( $res ) {
1171                 if ( $res instanceof ResultWrapper ) {
1172                         $res = $res->result;
1173                 }
1174                 if ( !@db2_free_result( $res ) ) {
1175                         throw new DBUnexpectedError( $this, "Unable to free DB2 result\n" );
1176                 }
1177         }
1178
1179         /**
1180          * Returns the number of columns in a resource
1181          * @param $res Object: statement resource
1182          * @return Number of fields/columns in resource
1183          */
1184         public function numFields( $res ) {
1185                 if ( $res instanceof ResultWrapper ) {
1186                         $res = $res->result;
1187                 }
1188                 return db2_num_fields( $res );
1189         }
1190
1191         /**
1192          * Returns the nth column name
1193          * @param $res Object: statement resource
1194          * @param $n Integer: Index of field or column
1195          * @return String name of nth column
1196          */
1197         public function fieldName( $res, $n ) {
1198                 if ( $res instanceof ResultWrapper ) {
1199                         $res = $res->result;
1200                 }
1201                 return db2_field_name( $res, $n );
1202         }
1203
1204         /**
1205          * SELECT wrapper
1206          *
1207          * @param $table   Array or string, table name(s) (prefix auto-added)
1208          * @param $vars    Array or string, field name(s) to be retrieved
1209          * @param $conds   Array or string, condition(s) for WHERE
1210          * @param $fname   String: calling function name (use __METHOD__)
1211          *                 for logs/profiling
1212          * @param $options Associative array of options
1213          *                 (e.g. array('GROUP BY' => 'page_title')),
1214          *                 see Database::makeSelectOptions code for list of
1215          *                 supported stuff
1216          * @param $join_conds Associative array of table join conditions (optional)
1217          *                    (e.g. array( 'page' => array('LEFT JOIN',
1218          *                    'page_latest=rev_id') )
1219          * @return Mixed: database result resource for fetch functions or false
1220          *                 on failure
1221          */
1222         public function select( $table, $vars, $conds = '', $fname = 'DatabaseIbm_db2::select', $options = array(), $join_conds = array() )
1223         {
1224                 $res = parent::select( $table, $vars, $conds, $fname, $options,
1225                         $join_conds );
1226
1227                 // We must adjust for offset
1228                 if ( isset( $options['LIMIT'] ) && isset ( $options['OFFSET'] ) ) {
1229                         $limit = $options['LIMIT'];
1230                         $offset = $options['OFFSET'];
1231                 }
1232
1233                 // DB2 does not have a proper num_rows() function yet, so we must emulate
1234                 // DB2 9.5.4 and the corresponding ibm_db2 driver will introduce
1235                 //  a working one
1236                 // TODO: Yay!
1237
1238                 // we want the count
1239                 $vars2 = array( 'count( * ) as num_rows' );
1240                 // respecting just the limit option
1241                 $options2 = array();
1242                 if ( isset( $options['LIMIT'] ) ) {
1243                         $options2['LIMIT'] = $options['LIMIT'];
1244                 }
1245                 // but don't try to emulate for GROUP BY
1246                 if ( isset( $options['GROUP BY'] ) ) {
1247                         return $res;
1248                 }
1249
1250                 $res2 = parent::select( $table, $vars2, $conds, $fname, $options2,
1251                         $join_conds );
1252                 $obj = $this->fetchObject( $res2 );
1253                 $this->mNumRows = $obj->num_rows;
1254
1255                 return $res;
1256         }
1257
1258         /**
1259          * Handles ordering, grouping, and having options ('GROUP BY' => colname)
1260          * Has limited support for per-column options (colnum => 'DISTINCT')
1261          *
1262          * @private
1263          *
1264          * @param $options Associative array of options to be turned into
1265          *              an SQL query, valid keys are listed in the function.
1266          * @return Array
1267          */
1268         function makeSelectOptions( $options ) {
1269                 $preLimitTail = $postLimitTail = '';
1270                 $startOpts = '';
1271
1272                 $noKeyOptions = array();
1273                 foreach ( $options as $key => $option ) {
1274                         if ( is_numeric( $key ) ) {
1275                                 $noKeyOptions[$option] = true;
1276                         }
1277                 }
1278
1279                 if ( isset( $options['GROUP BY'] ) ) {
1280                         $preLimitTail .= " GROUP BY {$options['GROUP BY']}";
1281                 }
1282                 if ( isset( $options['HAVING'] ) ) {
1283                         $preLimitTail .= " HAVING {$options['HAVING']}";
1284                 }
1285                 if ( isset( $options['ORDER BY'] ) ) {
1286                         $preLimitTail .= " ORDER BY {$options['ORDER BY']}";
1287                 }
1288
1289                 if ( isset( $noKeyOptions['DISTINCT'] )
1290                         || isset( $noKeyOptions['DISTINCTROW'] ) )
1291                 {
1292                         $startOpts .= 'DISTINCT';
1293                 }
1294
1295                 return array( $startOpts, '', $preLimitTail, $postLimitTail );
1296         }
1297
1298         /**
1299          * Returns link to IBM DB2 free download
1300          * @return String: wikitext of a link to the server software's web site
1301          */
1302         public static function getSoftwareLink() {
1303                 return '[http://www.ibm.com/db2/express/ IBM DB2]';
1304         }
1305
1306         /**
1307          * Get search engine class. All subclasses of this
1308          * need to implement this if they wish to use searching.
1309          *
1310          * @return String
1311          */
1312         public function getSearchEngine() {
1313                 return 'SearchIBM_DB2';
1314         }
1315
1316         /**
1317          * Did the last database access fail because of deadlock?
1318          * @return Boolean
1319          */
1320         public function wasDeadlock() {
1321                 // get SQLSTATE
1322                 $err = $this->lastErrno();
1323                 switch( $err ) {
1324                         // This is literal port of the MySQL logic and may be wrong for DB2
1325                         case '40001':   // sql0911n, Deadlock or timeout, rollback
1326                         case '57011':   // sql0904n, Resource unavailable, no rollback
1327                         case '57033':   // sql0913n, Deadlock or timeout, no rollback
1328                         $this->installPrint( "In a deadlock because of SQLSTATE $err" );
1329                         return true;
1330                 }
1331                 return false;
1332         }
1333
1334         /**
1335          * Ping the server and try to reconnect if it there is no connection
1336          * The connection may be closed and reopened while this happens
1337          * @return Boolean: whether the connection exists
1338          */
1339         public function ping() {
1340                 // db2_ping() doesn't exist
1341                 // Emulate
1342                 $this->close();
1343                 $this->mConn = $this->openUncataloged( $this->mDBName, $this->mUser,
1344                         $this->mPassword, $this->mServer, $this->mPort );
1345
1346                 return false;
1347         }
1348         ######################################
1349         # Unimplemented and not applicable
1350         ######################################
1351         /**
1352          * Not implemented
1353          * @return string ''
1354          */
1355         public function getStatus( $which = '%' ) {
1356                 $this->installPrint( 'Not implemented for DB2: getStatus()' );
1357                 return '';
1358         }
1359         /**
1360          * Not implemented
1361          * @return string $sql
1362          */
1363         public function limitResultForUpdate( $sql, $num ) {
1364                 $this->installPrint( 'Not implemented for DB2: limitResultForUpdate()' );
1365                 return $sql;
1366         }
1367
1368         /**
1369          * Only useful with fake prepare like in base Database class
1370          * @return      string
1371          */
1372         public function fillPreparedArg( $matches ) {
1373                 $this->installPrint( 'Not useful for DB2: fillPreparedArg()' );
1374                 return '';
1375         }
1376
1377         ######################################
1378         # Reflection
1379         ######################################
1380
1381         /**
1382          * Returns information about an index
1383          * If errors are explicitly ignored, returns NULL on failure
1384          * @param $table String: table name
1385          * @param $index String: index name
1386          * @param $fname String: function name for logging and profiling
1387          * @return Object query row in object form
1388          */
1389         public function indexInfo( $table, $index,
1390                 $fname = 'DatabaseIbm_db2::indexExists' )
1391         {
1392                 $table = $this->tableName( $table );
1393                 $sql = <<<SQL
1394 SELECT name as indexname
1395 FROM sysibm.sysindexes si
1396 WHERE si.name='$index' AND si.tbname='$table'
1397 AND sc.tbcreator='$this->mSchema'
1398 SQL;
1399                 $res = $this->query( $sql, $fname );
1400                 if ( !$res ) {
1401                         return null;
1402                 }
1403                 $row = $this->fetchObject( $res );
1404                 if ( $row != null ) {
1405                         return $row;
1406                 } else {
1407                         return false;
1408                 }
1409         }
1410
1411         /**
1412          * Returns an information object on a table column
1413          * @param $table String: table name
1414          * @param $field String: column name
1415          * @return IBM_DB2Field
1416          */
1417         public function fieldInfo( $table, $field ) {
1418                 return IBM_DB2Field::fromText( $this, $table, $field );
1419         }
1420
1421         /**
1422          * db2_field_type() wrapper
1423          * @param $res Object: result of executed statement
1424          * @param $index Mixed: number or name of the column
1425          * @return String column type
1426          */
1427         public function fieldType( $res, $index ) {
1428                 if ( $res instanceof ResultWrapper ) {
1429                         $res = $res->result;
1430                 }
1431                 return db2_field_type( $res, $index );
1432         }
1433
1434         /**
1435          * Verifies that an index was created as unique
1436          * @param $table String: table name
1437          * @param $index String: index name
1438          * @param $fname function name for profiling
1439          * @return Bool
1440          */
1441         public function indexUnique ( $table, $index,
1442                 $fname = 'DatabaseIbm_db2::indexUnique' )
1443         {
1444                 $table = $this->tableName( $table );
1445                 $sql = <<<SQL
1446 SELECT si.name as indexname
1447 FROM sysibm.sysindexes si
1448 WHERE si.name='$index' AND si.tbname='$table'
1449 AND sc.tbcreator='$this->mSchema'
1450 AND si.uniquerule IN ( 'U', 'P' )
1451 SQL;
1452                 $res = $this->query( $sql, $fname );
1453                 if ( !$res ) {
1454                         return null;
1455                 }
1456                 if ( $this->fetchObject( $res ) ) {
1457                         return true;
1458                 }
1459                 return false;
1460
1461         }
1462
1463         /**
1464          * Returns the size of a text field, or -1 for "unlimited"
1465          * @param $table String: table name
1466          * @param $field String: column name
1467          * @return Integer: length or -1 for unlimited
1468          */
1469         public function textFieldSize( $table, $field ) {
1470                 $table = $this->tableName( $table );
1471                 $sql = <<<SQL
1472 SELECT length as size
1473 FROM sysibm.syscolumns sc
1474 WHERE sc.name='$field' AND sc.tbname='$table'
1475 AND sc.tbcreator='$this->mSchema'
1476 SQL;
1477                 $res = $this->query( $sql );
1478                 $row = $this->fetchObject( $res );
1479                 $size = $row->size;
1480                 return $size;
1481         }
1482
1483         /**
1484          * DELETE where the condition is a join
1485          * @param $delTable String: deleting from this table
1486          * @param $joinTable String: using data from this table
1487          * @param $delVar String: variable in deleteable table
1488          * @param $joinVar String: variable in data table
1489          * @param $conds Array: conditionals for join table
1490          * @param $fname String: function name for profiling
1491          */
1492         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar,
1493                 $conds, $fname = "DatabaseIbm_db2::deleteJoin" )
1494         {
1495                 if ( !$conds ) {
1496                         throw new DBUnexpectedError( $this,
1497                                 'DatabaseIbm_db2::deleteJoin() called with empty $conds' );
1498                 }
1499
1500                 $delTable = $this->tableName( $delTable );
1501                 $joinTable = $this->tableName( $joinTable );
1502                 $sql = <<<SQL
1503 DELETE FROM $delTable
1504 WHERE $delVar IN (
1505   SELECT $joinVar FROM $joinTable
1506
1507 SQL;
1508                 if ( $conds != '*' ) {
1509                         $sql .= 'WHERE ' . $this->makeList( $conds, LIST_AND );
1510                 }
1511                 $sql .= ' )';
1512
1513                 $this->query( $sql, $fname );
1514         }
1515
1516         /**
1517          * Description is left as an exercise for the reader
1518          * @param $b Mixed: data to be encoded
1519          * @return IBM_DB2Blob
1520          */
1521         public function encodeBlob( $b ) {
1522                 return new IBM_DB2Blob( $b );
1523         }
1524
1525         /**
1526          * Description is left as an exercise for the reader
1527          * @param $b IBM_DB2Blob: data to be decoded
1528          * @return mixed
1529          */
1530         public function decodeBlob( $b ) {
1531                 return "$b";
1532         }
1533
1534         /**
1535          * Convert into a list of string being concatenated
1536          * @param $stringList Array: strings that need to be joined together
1537          *                    by the SQL engine
1538          * @return String: joined by the concatenation operator
1539          */
1540         public function buildConcat( $stringList ) {
1541                 // || is equivalent to CONCAT
1542                 // Sample query: VALUES 'foo' CONCAT 'bar' CONCAT 'baz'
1543                 return implode( ' || ', $stringList );
1544         }
1545
1546         /**
1547          * Generates the SQL required to convert a DB2 timestamp into a Unix epoch
1548          * @param $column String: name of timestamp column
1549          * @return String: SQL code
1550          */
1551         public function extractUnixEpoch( $column ) {
1552                 // TODO
1553                 // see SpecialAncientpages
1554         }
1555
1556         ######################################
1557         # Prepared statements
1558         ######################################
1559
1560         /**
1561          * Intended to be compatible with the PEAR::DB wrapper functions.
1562          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
1563          *
1564          * ? = scalar value, quoted as necessary
1565          * ! = raw SQL bit (a function for instance)
1566          * & = filename; reads the file and inserts as a blob
1567          *     (we don't use this though...)
1568          * @param $sql String: SQL statement with appropriate markers
1569          * @param $func String: Name of the function, for profiling
1570          * @return resource a prepared DB2 SQL statement
1571          */
1572         public function prepare( $sql, $func = 'DB2::prepare' ) {
1573                 $stmt = db2_prepare( $this->mConn, $sql, $this->mStmtOptions );
1574                 return $stmt;
1575         }
1576
1577         /**
1578          * Frees resources associated with a prepared statement
1579          * @return Boolean success or failure
1580          */
1581         public function freePrepared( $prepared ) {
1582                 return db2_free_stmt( $prepared );
1583         }
1584
1585         /**
1586          * Execute a prepared query with the various arguments
1587          * @param $prepared String: the prepared sql
1588          * @param $args Mixed: either an array here, or put scalars as varargs
1589          * @return Resource: results object
1590          */
1591         public function execute( $prepared, $args = null ) {
1592                 if( !is_array( $args ) ) {
1593                         # Pull the var args
1594                         $args = func_get_args();
1595                         array_shift( $args );
1596                 }
1597                 $res = db2_execute( $prepared, $args );
1598                 if ( !$res ) {
1599                         $this->installPrint( db2_stmt_errormsg() );
1600                 }
1601                 return $res;
1602         }
1603
1604         /**
1605          * Prepare & execute an SQL statement, quoting and inserting arguments
1606          * in the appropriate places.
1607          * @param $query String
1608          * @param $args ...
1609          */
1610         public function safeQuery( $query, $args = null ) {
1611                 // copied verbatim from Database.php
1612                 $prepared = $this->prepare( $query, 'DB2::safeQuery' );
1613                 if( !is_array( $args ) ) {
1614                         # Pull the var args
1615                         $args = func_get_args();
1616                         array_shift( $args );
1617                 }
1618                 $retval = $this->execute( $prepared, $args );
1619                 $this->freePrepared( $prepared );
1620                 return $retval;
1621         }
1622
1623         /**
1624          * For faking prepared SQL statements on DBs that don't support
1625          * it directly.
1626          * @param $preparedQuery String: a 'preparable' SQL statement
1627          * @param $args Array of arguments to fill it with
1628          * @return String: executable statement
1629          */
1630         public function fillPrepared( $preparedQuery, $args ) {
1631                 reset( $args );
1632                 $this->preparedArgs =& $args;
1633
1634                 foreach ( $args as $i => $arg ) {
1635                         db2_bind_param( $preparedQuery, $i+1, $args[$i] );
1636                 }
1637
1638                 return $preparedQuery;
1639         }
1640
1641         /**
1642          * Switches module between regular and install modes
1643          */
1644         public function setMode( $mode ) {
1645                 $old = $this->mMode;
1646                 $this->mMode = $mode;
1647                 return $old;
1648         }
1649
1650         /**
1651          * Bitwise negation of a column or value in SQL
1652          * Same as (~field) in C
1653          * @param $field String
1654          * @return String
1655          */
1656         function bitNot( $field ) {
1657                 // expecting bit-fields smaller than 4bytes
1658                 return "BITNOT( $field )";
1659         }
1660
1661         /**
1662          * Bitwise AND of two columns or values in SQL
1663          * Same as (fieldLeft & fieldRight) in C
1664          * @param $fieldLeft String
1665          * @param $fieldRight String
1666          * @return String
1667          */
1668         function bitAnd( $fieldLeft, $fieldRight ) {
1669                 return "BITAND( $fieldLeft, $fieldRight )";
1670         }
1671
1672         /**
1673          * Bitwise OR of two columns or values in SQL
1674          * Same as (fieldLeft | fieldRight) in C
1675          * @param $fieldLeft String
1676          * @param $fieldRight String
1677          * @return String
1678          */
1679         function bitOr( $fieldLeft, $fieldRight ) {
1680                 return "BITOR( $fieldLeft, $fieldRight )";
1681         }
1682 }
1683
1684 class IBM_DB2Helper {
1685         public static function makeArray( $maybeArray ) {
1686                 if ( !is_array( $maybeArray ) ) {
1687                         return array( $maybeArray );
1688                 }
1689
1690                 return $maybeArray;
1691         }
1692 }