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