inc/classes/main/file_directories/binary/class_BaseBinaryFile.php

   1 <?php
   2 /**
   3  * A general binary file class
   4  *
   5  * @author              Roland Haeder <webmaster@ship-simu.org>
   6  * @version             0.0.0
   7  * @copyright   Copyright (c) 2007, 2008 Roland Haeder, 2009 - 2012 Core Developer Team
   8  * @license             GNU GPL 3.0 or any newer version
   9  * @link                http://www.ship-simu.org
  10  *
  11  * This program is free software: you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation, either version 3 of the License, or
  14  * (at your option) any later version.
  15  *
  16  * This program is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19  * GNU General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License
  22  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  23  */
  24 class BaseBinaryFile extends BaseFile {
  25         /**
  26          * Separator for header data
  27          */
  28         const SEPARATOR_HEADER_DATA = 0x01;
  29
  30         /**
  31          * Separator header->entries
  32          */
  33         const SEPARATOR_HEADER_ENTRIES = 0x02;
  34
  35         /**
  36          * Separator hash->name
  37          */
  38         const SEPARATOR_HASH_NAME = 0x03;
  39
  40         /**
  41          * Separator entry->entry
  42          */
  43         const SEPARATOR_ENTRIES = 0x04;
  44
  45         /**
  46          * Separator type->position
  47          */
  48         const SEPARATOR_TYPE_POSITION = 0x05;
  49
  50         /**
  51          * Length of count
  52          */
  53         const LENGTH_COUNT = 20;
  54
  55         /**
  56          * Length of position
  57          */
  58         const LENGTH_POSITION = 20;
  59
  60         /**
  61          * Length of name
  62          */
  63         const LENGTH_NAME = 10;
  64
  65         /**
  66          * Maximum length of entry type
  67          */
  68         const LENGTH_TYPE = 20;
  69
  70         //***** Array elements for 'gaps' array *****
  71
  72         /**
  73          * Start of gap
  74          */
  75         const GAPS_INDEX_START = 'start';
  76
  77         /**
  78          * End of gap
  79          */
  80         const GAPS_INDEX_END = 'end';
  81
  82         /**
  83          * Current seek position
  84          */
  85         private $seekPosition = 0;
  86
  87         /**
  88          * Size of header
  89          */
  90         private $headerSize = 0;
  91
  92         /**
  93          * File header
  94          */
  95         private $header = array();
  96
  97         /**
  98          * Seek positions for gaps ("fragmentation")
  99          */
 100         private $gaps = array();
 101
 102         /**
 103          * Seek positions for damaged entries (e.g. mismatching hash sum, ...)
 104          */
 105         private $damagedEntries = array();
 106
 107         /**
 108          * Back-buffer
 109          */
 110         private $backBuffer = '';
 111
 112         /**
 113          * Currently loaded block (will be returned by current())
 114          */
 115         private $currentBlock = '';
 116
 117         /**
 118          * Protected constructor
 119          *
 120          * @param       $className      Name of the class
 121          * @return      void
 122          */
 123         protected function __construct ($className) {
 124                 // Call parent constructor
 125                 parent::__construct($className);
 126
 127                 // Init counters and gaps array
 128                 $this->initCountersGapsArray();
 129         }
 130
 131         /**
 132          * Checks whether the abstracted file only contains gaps by counting all
 133          * gaps' bytes together and compare it to total length.
 134          *
 135          * @return      $isGapsOnly             Whether the abstracted file only contains gaps
 136          */
 137         private function isFileOnlyGaps () {
 138                 // First/last gap found?
 139                 /* Only for debugging
 140                 if (isset($this->gaps[0])) {
 141                         // Output first and last gap
 142                         self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] this->gaps[0]=%s,this->gaps[%s]=%s', __METHOD__, __LINE__, print_r($this->gaps[0], TRUE), (count($this->gaps) - 1), print_r($this->gaps[count($this->gaps) - 1], TRUE)));
 143                 } // END - if
 144                 */
 145
 146                 // Now count every gap
 147                 $gapsSize = 0;
 148                 foreach ($this->gaps as $gap) {
 149                         // Calculate size of found gap: end-start including both
 150                         $gapsSize += ($gap[self::GAPS_INDEX_END] - $gap[self::GAPS_INDEX_START]);
 151                 } // END - if
 152
 153                 // Debug output
 154                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] gapsSize=%s,this->headerSize=%s', __METHOD__, __LINE__, $gapsSize, $this->getHeaderSize()));
 155
 156                 // Total gap size + header size must be same as file size
 157                 $isGapsOnly = (($this->getHeaderSize() + $gapsSize) == $this->getFileSize());
 158
 159                 // Return status
 160                 return $isGapsOnly;
 161         }
 162
 163         /**
 164          * Initializes counter for valid entries, arrays for damaged entries and
 165          * an array for gap seek positions. If you call this method on your own,
 166          * please re-analyze the file structure. So you are better to call
 167          * analyzeFile() instead of this method.
 168          *
 169          * @return      void
 170          */
 171         public function initCountersGapsArray () {
 172                 // Init counter and seek position
 173                 $this->setCounter(0);
 174                 $this->setSeekPosition(0);
 175
 176                 // Init arrays
 177                 $this->gaps = array();
 178                 $this->damagedEntries = array();
 179         }
 180
 181         /**
 182          * Getter for header size
 183          *
 184          * @return      $totalEntries   Size of file header
 185          */
 186         public final function getHeaderSize () {
 187                 // Get it
 188                 return $this->headerSize;
 189         }
 190
 191         /**
 192          * Setter for header size
 193          *
 194          * @param       $headerSize             Size of file header
 195          * @return      void
 196          */
 197         public final function setHeaderSize ($headerSize) {
 198                 // Set it
 199                 $this->headerSize = $headerSize;
 200         }
 201
 202         /**
 203          * Getter for header array
 204          *
 205          * @return      $totalEntries   Size of file header
 206          */
 207         public final function getHeader () {
 208                 // Get it
 209                 return $this->header;
 210         }
 211
 212         /**
 213          * Setter for header
 214          *
 215          * @param       $header         Array for a file header
 216          * @return      void
 217          */
 218         public final function setHeader (array $header) {
 219                 // Set it
 220                 $this->header = $header;
 221         }
 222
 223         /**
 224          * Getter for seek position
 225          *
 226          * @return      $seekPosition   Current seek position (stored here in object)
 227          */
 228         public final function getSeekPosition () {
 229                 // Get it
 230                 return $this->seekPosition;
 231         }
 232
 233         /**
 234          * Setter for seek position
 235          *
 236          * @param       $seekPosition   Current seek position (stored here in object)
 237          * @return      void
 238          */
 239         protected final function setSeekPosition ($seekPosition) {
 240                 // And set it
 241                 $this->seekPosition = $seekPosition;
 242         }
 243
 244         /**
 245          * Updates seekPosition attribute from file to avoid to much access on file.
 246          *
 247          * @return      void
 248          */
 249         public function updateSeekPosition () {
 250                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 251
 252                 // Get key (= seek position)
 253                 $seekPosition = $this->key();
 254                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] Setting seekPosition=%s', __METHOD__, __LINE__, $seekPosition));
 255
 256                 // And set it here
 257                 $this->setSeekPosition($seekPosition);
 258
 259                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] EXIT!', __METHOD__, __LINE__));
 260         }
 261
 262         /**
 263          * Seeks to beginning of file, updates seek position in this object and
 264          * flushes the header.
 265          *
 266          * @return      void
 267          */
 268         protected function rewindUpdateSeekPosition () {
 269                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 270
 271                 // flushFileHeader must be callable
 272                 assert(is_callable(array($this, 'flushFileHeader')));
 273
 274                 // Seek to beginning of file
 275                 $this->rewind();
 276
 277                 // And update seek position ...
 278                 $this->updateSeekPosition();
 279
 280                 // ... to write it back into the file
 281                 $this->flushFileHeader();
 282
 283                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] EXIT!!', __METHOD__, __LINE__));
 284         }
 285
 286         /**
 287          * Seeks to old position
 288          *
 289          * @return      void
 290          */
 291         protected function seekToOldPosition () {
 292                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 293
 294                 // Seek to currently ("old") saved position
 295                 $this->seek($this->getSeekPosition());
 296
 297                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] EXIT!!', __METHOD__, __LINE__));
 298         }
 299
 300         /**
 301          * Checks whether the block separator has been found
 302          *
 303          * @param       $str            String to look in
 304          * @return      $isFound        Whether the block separator has been found
 305          */
 306         public static function isBlockSeparatorFound ($str) {
 307                 // Determine it
 308                 $isFound = (strpos($str, chr(self::SEPARATOR_ENTRIES)) !== FALSE);
 309
 310                 // Return result
 311                 return $isFound;
 312         }
 313
 314         /**
 315          * Initializes the back-buffer by setting it to an empty string.
 316          *
 317          * @return      void
 318          */
 319         private function initBackBuffer () {
 320                 // Simply call the setter
 321                 $this->setBackBuffer('');
 322         }
 323
 324         /**
 325          * Setter for backBuffer field
 326          *
 327          * @param       $backBuffer             Characters to "store" in back-buffer
 328          * @return      void
 329          */
 330         private function setBackBuffer ($backBuffer) {
 331                 // Cast to string (so no arrays or objects)
 332                 $backBuffer = (string) $backBuffer;
 333
 334                 // ... and set it
 335                 $this->backBuffer = $backBuffer;
 336         }
 337
 338         /**
 339          * Getter for backBuffer field
 340          *
 341          * @return      $backBuffer             Characters "stored" in back-buffer
 342          */
 343         private function getBackBuffer () {
 344                 return $this->backBuffer;
 345         }
 346
 347         /**
 348          * Setter for currentBlock field
 349          *
 350          * @param       $currentBlock           Characters to set a currently loaded block
 351          * @return      void
 352          */
 353         private function setCurrentBlock ($currentBlock) {
 354                 // Cast to string (so no arrays or objects)
 355                 $currentBlock = (string) $currentBlock;
 356
 357                 // ... and set it
 358                 $this->currentBlock = $currentBlock;
 359         }
 360
 361         /**
 362          * Gets currently read data
 363          *
 364          * @return      $current        Currently read data
 365          */
 366         public function getCurrentBlock () {
 367                 // Return it
 368                 return $this->currentBlock;
 369         }
 370
 371         /**
 372          * Initializes this file class
 373          *
 374          * @param       $fileName       Name of this abstract file
 375          * @return      void
 376          */
 377         protected function initFile ($fileName) {
 378                 // Get a file i/o pointer instance
 379                 $pointerInstance = ObjectFactory::createObjectByConfiguredName('file_raw_input_output_class', array($fileName));
 380
 381                 // ... and set it here
 382                 $this->setPointerInstance($pointerInstance);
 383         }
 384
 385         /**
 386          * Writes data at given position
 387          *
 388          * @param       $seekPosition   Seek position
 389          * @param       $data                   Data to be written
 390          * @param       $flushHeader    Whether to flush the header (default: flush)
 391          * @return      void
 392          */
 393         public function writeData ($seekPosition, $data, $flushHeader = TRUE) {
 394                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] seekPosition=%s,data()=%s - CALLED!', __METHOD__, __LINE__, $seekPosition, strlen($data)));
 395
 396                 // Write data at given position
 397                 $this->getPointerInstance()->writeAtPosition($seekPosition, $data);
 398
 399                 // Update seek position
 400                 $this->updateSeekPosition();
 401
 402                 // Flush the header?
 403                 if ($flushHeader === TRUE) {
 404                         // Flush header
 405                         $this->flushFileHeader();
 406
 407                         // Seek to old position
 408                         $this->seekToOldPosition();
 409                 } // END - if
 410
 411                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] EXIT!', __METHOD__, __LINE__));
 412         }
 413
 414         /**
 415          * Marks the currently loaded block as empty (with length of the block)
 416          *
 417          * @param       $length         Length of the block
 418          * @return      void
 419          */
 420         protected function markCurrentBlockAsEmpty ($length) {
 421                 // Get current seek position
 422                 $currentPosition = $this->key();
 423
 424                 // Now add it as gap entry
 425                 array_push($this->gaps, array(
 426                         self::GAPS_INDEX_START  => ($currentPosition - $length),
 427                         self::GAPS_INDEX_END    => $currentPosition,
 428                 ));
 429         }
 430
 431         /**
 432          * Checks whether the file header is initialized
 433          *
 434          * @return      $isInitialized  Whether the file header is initialized
 435          */
 436         public function isFileHeaderInitialized () {
 437                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 438
 439                 // Default is not initialized
 440                 $isInitialized = FALSE;
 441
 442                 // Is the file initialized?
 443                 if ($this->isFileInitialized()) {
 444                         // Some bytes has been written, so rewind to start of it.
 445                         $rewindStatus = $this->rewind();
 446                         //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] rewindStatus=%s', __METHOD__, __LINE__, $rewindStatus));
 447
 448                         // Is the rewind() call successfull?
 449                         if ($rewindStatus != 1) {
 450                                 // Something bad happened
 451                                 self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] Could not rewind().', __METHOD__, __LINE__));
 452                         } // END - if
 453
 454                         // Read file header
 455                         $this->readFileHeader();
 456
 457                         // The above method does already check the header
 458                         $isInitialized = TRUE;
 459                 } // END - if
 460
 461                 // Return result
 462                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] isInitialized=%d - EXIT!', __METHOD__, __LINE__, intval($isInitialized)));
 463                 return $isInitialized;
 464         }
 465
 466         /**
 467          * Checks whether the assigned file has been initialized
 468          *
 469          * @return      $isInitialized          Whether the file's size is zero
 470          */
 471         public function isFileInitialized () {
 472                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 473
 474                 // Get it from iterator which holds the pointer instance. If FALSE is returned
 475                 $fileSize = $this->size();
 476                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] fileSize=%s', __METHOD__, __LINE__, $fileSize));
 477
 478                 /*
 479                  * The returned file size should not be FALSE or NULL as this means
 480                  * that the pointer class does not work correctly.
 481                  */
 482                 assert(is_int($fileSize));
 483
 484                 // Is more than 0 returned?
 485                 $isInitialized = ($fileSize > 0);
 486
 487                 // Return result
 488                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] isInitialized=%d - EXIT!', __METHOD__, __LINE__, intval($isInitialized)));
 489                 return $isInitialized;
 490         }
 491
 492         /**
 493          * Creates the assigned file
 494          *
 495          * @return      void
 496          */
 497         public function createFileHeader () {
 498                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 499
 500                 // The file's header should not be initialized here
 501                 assert(!$this->isFileHeaderInitialized());
 502
 503                 // Simple flush file header which will create it.
 504                 $this->flushFileHeader();
 505
 506                 // Rewind seek position (to beginning of file) and update/flush file header
 507                 $this->rewindUpdateSeekPosition();
 508
 509                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] EXIT!!', __METHOD__, __LINE__));
 510         }
 511
 512         /**
 513          * Pre-allocates file (if enabled) with some space for later faster write access.
 514          *
 515          * @param       $type   Type of the file
 516          * @return      void
 517          */
 518         public function preAllocateFile ($type) {
 519                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 520
 521                 // Is it enabled?
 522                 if ($this->getConfigInstance()->getConfigEntry($type . '_pre_allocate_enabled') != 'Y') {
 523                         // Not enabled
 524                         self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] Not pre-allocating file.', __METHOD__, __LINE__));
 525
 526                         // Don't continue here.
 527                         return;
 528                 } // END - if
 529
 530                 // Message to user
 531                 self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] Pre-allocating file ...', __METHOD__, __LINE__));
 532
 533                 // Calculate minimum length for one entry
 534                 $minLengthEntry = $this->getBlockInstance()->calculateMinimumBlockLength();
 535                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] minLengthEntry=%s', __METHOD__, __LINE__, $minLengthEntry));
 536
 537                 // Calulcate seek position
 538                 $seekPosition = $minLengthEntry * $this->getConfigInstance()->getConfigEntry($type . '_pre_allocate_count');
 539                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] seekPosition=%s', __METHOD__, __LINE__, $seekPosition));
 540
 541                 // Now simply write a NUL there. This will pre-allocate the file.
 542                 $this->writeData($seekPosition, chr(0));
 543
 544                 // Rewind seek position (to beginning of file) and update/flush file header
 545                 $this->rewindUpdateSeekPosition();
 546
 547                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] EXIT!', __METHOD__, __LINE__));
 548         }
 549
 550         /**
 551          * Determines seek position
 552          *
 553          * @return      $seekPosition   Current seek position
 554          */
 555         public function determineSeekPosition () {
 556                 // Call pointer instance
 557                 return $this->getPointerInstance()->determineSeekPosition();
 558         }
 559
 560         /**
 561          * Seek to given offset (default) or other possibilities as fseek() gives.
 562          *
 563          * @param       $offset         Offset to seek to (or used as "base" for other seeks)
 564          * @param       $whence         Added to offset (default: only use offset to seek to)
 565          * @return      $status         Status of file seek: 0 = success, -1 = failed
 566          */
 567         public function seek ($offset, $whence = SEEK_SET) {
 568                 // Call pointer instance
 569                 return $this->getPointerInstance()->seek($offset, $whence);
 570         }
 571
 572         /**
 573          * Reads given amount of bytes from file.
 574          *
 575          * @param       $bytes  Amount of bytes to read
 576          * @return      $data   Data read from file
 577          */
 578         public function read ($bytes) {
 579                 // Call pointer instance
 580                 return $this->getPointerInstance()->read($bytes);
 581         }
 582
 583         /**
 584          * Rewinds to the beginning of the file
 585          *
 586          * @return      $status         Status of this operation
 587          */
 588         public function rewind () {
 589                 // Call pointer instance
 590                 return $this->getPointerInstance()->rewind();
 591         }
 592
 593         /**
 594          * Analyzes entries in index file. This will count all found (and valid)
 595          * entries, mark invalid as damaged and count gaps ("fragmentation"). If
 596          * only gaps are found, the file is considered as "virgin" (no entries).
 597          *
 598          * @return      void
 599          */
 600         public function analyzeFile () {
 601                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 602
 603                 // Make sure the file is initialized
 604                 assert($this->isFileInitialized());
 605
 606                 // Init counters and gaps array
 607                 $this->initCountersGapsArray();
 608
 609                 // Output message (as this may take some time)
 610                 self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] Analyzing file structure ... (this may take some time)', __METHOD__, __LINE__));
 611
 612                 // First rewind to the begining
 613                 $this->rewind();
 614
 615                 // Then try to load all entries
 616                 while ($this->valid()) {
 617                         // Go to next entry
 618                         $this->next();
 619
 620                         // Get current entry
 621                         $current = $this->getCurrentBlock();
 622
 623                         /*
 624                          * If the block is empty, maybe the whole file is? This could mean
 625                          * that the file has been pre-allocated.
 626                          */
 627                         if (empty($current)) {
 628                                 // Then skip this part
 629                                 continue;
 630                         } // END - if
 631
 632                         // Debug message
 633                         /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] current()=%s', __METHOD__, __LINE__, strlen($current)));
 634                 } // END - while
 635
 636                 // If the last read block is empty, check gaps
 637                 if (empty($current)) {
 638                         // Output message
 639                         self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] Found a total of %s gaps.', __METHOD__, __LINE__, count($this->gaps)));
 640
 641                         // Check gaps, if the whole file is empty.
 642                         if ($this->isFileOnlyGaps()) {
 643                                 // Only gaps, so don't continue here.
 644                                 return;
 645                         } // END - if
 646
 647                         /*
 648                          * The above call has calculated a total size of all gaps. If the
 649                          * percentage of gaps passes a "soft" limit and last
 650                          * defragmentation is to far in the past, or if a "hard" limit has
 651                          * reached, run defragmentation.
 652                          */
 653                         if ($this->isDefragmentationNeeded()) {
 654                                 // Run "defragmentation"
 655                                 $this->doRunDefragmentation();
 656                         } // END - if
 657                 } // END - if
 658                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] EXIT!', __METHOD__, __LINE__));
 659         }
 660
 661         /**
 662          * Advances to next "block" of bytes
 663          *
 664          * @return      void
 665          */
 666         public function next () {
 667                 // Is there nothing to read?
 668                 if (!$this->valid()) {
 669                         // Nothing to read
 670                         return;
 671                 } // END - if
 672
 673                 // Debug message
 674                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d] key()=%s', __FUNCTION__, __LINE__, $this->key()));
 675
 676                 // Make sure the block instance is set
 677                 assert($this->getBlockInstance() instanceof CalculatableBlock);
 678
 679                 // First calculate minimum block length
 680                 $length = $this->getBlockInstance()->calculateMinimumBlockLength();
 681                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d] length=%s', __FUNCTION__, __LINE__, $length));
 682
 683                 // Short be more than zero!
 684                 assert($length > 0);
 685
 686                 // Read possibly back-buffered bytes from previous call of next().
 687                 $data = $this->getBackBuffer();
 688
 689                 /*
 690                  * Read until a entry/block separator has been found. The next read
 691                  * "block" may not fit, so this loop will continue until the EOB or EOF
 692                  * has been reached whatever comes first.
 693                  */
 694                 while ((!$this->isEndOfFileReached()) && (!self::isBlockSeparatorFound($data))) {
 695                         // Then read the next possible block
 696                         $block = $this->read($length);
 697
 698                         // Debug message
 699                         //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d] block()=%s,length=%s', __FUNCTION__, __LINE__, strlen($block), $length));
 700
 701                         // Is it all empty?
 702                         if (strlen(trim($block)) == 0) {
 703                                 // Mark this block as empty
 704                                 $this->markCurrentBlockAsEmpty(strlen($block));
 705
 706                                 // Skip to next block
 707                                 continue;
 708                         } // END - if
 709
 710                         // At this block then
 711                         $data .= $block;
 712
 713                         // A debug message
 714                         //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d] data()=%s', __FUNCTION__, __LINE__, strlen($data)));
 715                 } // END - while
 716
 717                 // EOF reached?
 718                 if ($this->isEndOfFileReached()) {
 719                         // Set whole data as current read block
 720                         //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput('Calling setCurrentBlock(' . strlen($data) . ') ...');
 721                         $this->setCurrentBlock($data);
 722
 723                         // Then abort here silently
 724                         //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput('EOF reached.');
 725                         return;
 726                 } // END - if
 727
 728                 /*
 729                  * Init back-buffer which is the data that has been found beyond the
 730                  * separator.
 731                  */
 732                 $this->initBackBuffer();
 733
 734                 // Separate data
 735                 $dataArray = explode(chr(self::SEPARATOR_ENTRIES), $data);
 736
 737                 // This array must contain two elements
 738                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput('dataArray=' . print_r($dataArray, TRUE));
 739                 assert(count($dataArray) == 2);
 740
 741                 // Left part is the actual block, right one the back-buffer data
 742                 $this->setCurrentBlock($dataArray[0]);
 743                 $this->setBackBuffer($dataArray[1]);
 744         }
 745
 746         /**
 747          * Checks wether the current entry is valid (not at the end of the file).
 748          * This method will return TRUE if an emptied (nulled) entry has been found.
 749          *
 750          * @return      $isValid        Whether the next entry is valid
 751          */
 752         public function valid () {
 753                 // Make sure the block instance is set
 754                 assert($this->getBlockInstance() instanceof Block);
 755
 756                 // First calculate minimum block length
 757                 $length = $this->getBlockInstance()->calculateMinimumBlockLength();
 758
 759                 // Short be more than zero!
 760                 assert($length > 0);
 761
 762                 // Get current seek position
 763                 $seekPosition = $this->key();
 764
 765                 // Then try to read it
 766                 $data = $this->read($length);
 767
 768                 // If some bytes could be read, all is fine
 769                 $isValid = ((is_string($data)) && (strlen($data) > 0));
 770
 771                 // Get header size
 772                 $headerSize = $this->getHeaderSize();
 773
 774                 // Is the seek position at or beyond the header?
 775                 if ($seekPosition >= $headerSize) {
 776                         // Seek back to old position
 777                         $this->seek($seekPosition);
 778                 } else {
 779                         // Seek directly behind the header
 780                         $this->seek($headerSize);
 781                 }
 782
 783                 // Return result
 784                 return $isValid;
 785         }
 786
 787         /**
 788          * Gets current seek position ("key").
 789          *
 790          * @return      $key    Current key in iteration
 791          */
 792         public function key () {
 793                 // Call pointer instance
 794                 return $this->getPointerInstance()->determineSeekPosition();
 795         }
 796
 797         /**
 798          * Reads the file header
 799          *
 800          * @return      void
 801          */
 802         public function readFileHeader () {
 803                 // Make sure the block instance is set
 804                 assert($this->getBlockInstance() instanceof Block);
 805
 806                 // Call block instance
 807                 $this->getBlockInstance()->readFileHeader();
 808         }
 809
 810         /**
 811          * Flushes the file header
 812          *
 813          * @return      void
 814          */
 815         public function flushFileHeader () {
 816                 // Make sure the block instance is set
 817                 assert($this->getBlockInstance() instanceof Block);
 818
 819                 // Call block instance
 820                 $this->getBlockInstance()->flushFileHeader();
 821         }
 822 }
 823
 824 // [EOF]
 825 ?>