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 - 2015 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 BaseAbstractFile {
  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 group->hash
  37          */
  38         const SEPARATOR_GROUP_HASH = 0x03;
  39
  40         /**
  41          * Separator hash->value
  42          */
  43         const SEPARATOR_HASH_VALUE = 0x04;
  44
  45         /**
  46          * Separator entry->entry
  47          */
  48         const SEPARATOR_ENTRIES = 0x05;
  49
  50         /**
  51          * Separator type->position
  52          */
  53         const SEPARATOR_TYPE_POSITION = 0x06;
  54
  55         /**
  56          * Length of count
  57          */
  58         const LENGTH_COUNT = 20;
  59
  60         /**
  61          * Length of position
  62          */
  63         const LENGTH_POSITION = 20;
  64
  65         /**
  66          * Length of group
  67          */
  68         const LENGTH_GROUP = 10;
  69
  70         /**
  71          * Maximum length of entry type
  72          */
  73         const LENGTH_TYPE = 20;
  74
  75         //***** Array elements for 'gaps' array *****
  76
  77         /**
  78          * Start of gap
  79          */
  80         const GAPS_INDEX_START = 'start';
  81
  82         /**
  83          * End of gap
  84          */
  85         const GAPS_INDEX_END = 'end';
  86
  87         /**
  88          * Current seek position
  89          */
  90         private $seekPosition = 0;
  91
  92         /**
  93          * Size of header
  94          */
  95         private $headerSize = 0;
  96
  97         /**
  98          * File header
  99          */
 100         private $header = array();
 101
 102         /**
 103          * Seek positions for gaps ("fragmentation")
 104          */
 105         private $gaps = array();
 106
 107         /**
 108          * Seek positions for damaged entries (e.g. mismatching hash sum, ...)
 109          */
 110         private $damagedEntries = array();
 111
 112         /**
 113          * Back-buffer
 114          */
 115         private $backBuffer = '';
 116
 117         /**
 118          * Currently loaded block (will be returned by current())
 119          */
 120         private $currentBlock = '';
 121
 122         /**
 123          * Protected constructor
 124          *
 125          * @param       $className      Name of the class
 126          * @return      void
 127          */
 128         protected function __construct ($className) {
 129                 // Call parent constructor
 130                 parent::__construct($className);
 131
 132                 // Init counters and gaps array
 133                 $this->initCountersGapsArray();
 134         }
 135
 136         /**
 137          * Checks whether the abstracted file only contains gaps by counting all
 138          * gaps' bytes together and compare it to total length.
 139          *
 140          * @return      $isGapsOnly             Whether the abstracted file only contains gaps
 141          */
 142         private function isFileOnlyGaps () {
 143                 // First/last gap found?
 144                 /* Only for debugging
 145                 if (isset($this->gaps[0])) {
 146                         // Output first and last gap
 147                         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)));
 148                 } // END - if
 149                 */
 150
 151                 // Now count every gap
 152                 $gapsSize = 0;
 153                 foreach ($this->gaps as $gap) {
 154                         // Calculate size of found gap: end-start including both
 155                         $gapsSize += ($gap[self::GAPS_INDEX_END] - $gap[self::GAPS_INDEX_START]);
 156                 } // END - if
 157
 158                 // Debug output
 159                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] gapsSize=%s,this->headerSize=%s', __METHOD__, __LINE__, $gapsSize, $this->getHeaderSize()));
 160
 161                 // Total gap size + header size must be same as file size
 162                 $isGapsOnly = (($this->getHeaderSize() + $gapsSize) == $this->getFileSize());
 163
 164                 // Return status
 165                 return $isGapsOnly;
 166         }
 167
 168         /**
 169          * Initializes counter for valid entries, arrays for damaged entries and
 170          * an array for gap seek positions. If you call this method on your own,
 171          * please re-analyze the file structure. So you are better to call
 172          * analyzeFile() instead of this method.
 173          *
 174          * @return      void
 175          */
 176         public function initCountersGapsArray () {
 177                 // Init counter and seek position
 178                 $this->setCounter(0);
 179                 $this->setSeekPosition(0);
 180
 181                 // Init arrays
 182                 $this->gaps = array();
 183                 $this->damagedEntries = array();
 184         }
 185
 186         /**
 187          * Getter for header size
 188          *
 189          * @return      $totalEntries   Size of file header
 190          */
 191         public final function getHeaderSize () {
 192                 // Get it
 193                 return $this->headerSize;
 194         }
 195
 196         /**
 197          * Setter for header size
 198          *
 199          * @param       $headerSize             Size of file header
 200          * @return      void
 201          */
 202         public final function setHeaderSize ($headerSize) {
 203                 // Set it
 204                 $this->headerSize = $headerSize;
 205         }
 206
 207         /**
 208          * Getter for header array
 209          *
 210          * @return      $totalEntries   Size of file header
 211          */
 212         public final function getHeader () {
 213                 // Get it
 214                 return $this->header;
 215         }
 216
 217         /**
 218          * Setter for header
 219          *
 220          * @param       $header         Array for a file header
 221          * @return      void
 222          */
 223         public final function setHeader (array $header) {
 224                 // Set it
 225                 $this->header = $header;
 226         }
 227
 228         /**
 229          * Getter for seek position
 230          *
 231          * @return      $seekPosition   Current seek position (stored here in object)
 232          */
 233         public final function getSeekPosition () {
 234                 // Get it
 235                 return $this->seekPosition;
 236         }
 237
 238         /**
 239          * Setter for seek position
 240          *
 241          * @param       $seekPosition   Current seek position (stored here in object)
 242          * @return      void
 243          */
 244         protected final function setSeekPosition ($seekPosition) {
 245                 // And set it
 246                 $this->seekPosition = $seekPosition;
 247         }
 248
 249         /**
 250          * Updates seekPosition attribute from file to avoid to much access on file.
 251          *
 252          * @return      void
 253          */
 254         public function updateSeekPosition () {
 255                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 256
 257                 // Get key (= seek position)
 258                 $seekPosition = $this->key();
 259                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] Setting seekPosition=%s', __METHOD__, __LINE__, $seekPosition));
 260
 261                 // And set it here
 262                 $this->setSeekPosition($seekPosition);
 263
 264                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] EXIT!', __METHOD__, __LINE__));
 265         }
 266
 267         /**
 268          * Seeks to beginning of file, updates seek position in this object and
 269          * flushes the header.
 270          *
 271          * @return      void
 272          */
 273         protected function rewindUpdateSeekPosition () {
 274                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 275
 276                 // flushFileHeader must be callable
 277                 assert(is_callable(array($this, 'flushFileHeader')));
 278
 279                 // Seek to beginning of file
 280                 $this->rewind();
 281
 282                 // And update seek position ...
 283                 $this->updateSeekPosition();
 284
 285                 // ... to write it back into the file
 286                 $this->flushFileHeader();
 287
 288                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] EXIT!', __METHOD__, __LINE__));
 289         }
 290
 291         /**
 292          * Seeks to old position
 293          *
 294          * @return      void
 295          */
 296         protected function seekToOldPosition () {
 297                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 298
 299                 // Seek to currently ("old") saved position
 300                 $this->seek($this->getSeekPosition());
 301
 302                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] EXIT!', __METHOD__, __LINE__));
 303         }
 304
 305         /**
 306          * Checks whether the block separator has been found
 307          *
 308          * @param       $str            String to look in
 309          * @return      $isFound        Whether the block separator has been found
 310          */
 311         public static function isBlockSeparatorFound ($str) {
 312                 // Determine it
 313                 $isFound = (strpos($str, chr(self::SEPARATOR_ENTRIES)) !== FALSE);
 314
 315                 // Return result
 316                 return $isFound;
 317         }
 318
 319         /**
 320          * Initializes the back-buffer by setting it to an empty string.
 321          *
 322          * @return      void
 323          */
 324         private function initBackBuffer () {
 325                 // Simply call the setter
 326                 $this->setBackBuffer('');
 327         }
 328
 329         /**
 330          * Setter for backBuffer field
 331          *
 332          * @param       $backBuffer             Characters to "store" in back-buffer
 333          * @return      void
 334          */
 335         private function setBackBuffer ($backBuffer) {
 336                 // Cast to string (so no arrays or objects)
 337                 $backBuffer = (string) $backBuffer;
 338
 339                 // ... and set it
 340                 $this->backBuffer = $backBuffer;
 341         }
 342
 343         /**
 344          * Getter for backBuffer field
 345          *
 346          * @return      $backBuffer             Characters "stored" in back-buffer
 347          */
 348         private function getBackBuffer () {
 349                 return $this->backBuffer;
 350         }
 351
 352         /**
 353          * Setter for currentBlock field
 354          *
 355          * @param       $currentBlock           Characters to set a currently loaded block
 356          * @return      void
 357          */
 358         private function setCurrentBlock ($currentBlock) {
 359                 // Cast to string (so no arrays or objects)
 360                 $currentBlock = (string) $currentBlock;
 361
 362                 // ... and set it
 363                 $this->currentBlock = $currentBlock;
 364         }
 365
 366         /**
 367          * Gets currently read data
 368          *
 369          * @return      $current        Currently read data
 370          */
 371         public function getCurrentBlock () {
 372                 // Return it
 373                 return $this->currentBlock;
 374         }
 375
 376         /**
 377          * Initializes this file class
 378          *
 379          * @param       $fileName       Name of this abstract file
 380          * @return      void
 381          */
 382         protected function initFile ($fileName) {
 383                 // Get a file i/o pointer instance
 384                 $pointerInstance = ObjectFactory::createObjectByConfiguredName('file_raw_input_output_class', array($fileName));
 385
 386                 // ... and set it here
 387                 $this->setPointerInstance($pointerInstance);
 388         }
 389
 390         /**
 391          * Writes data at given position
 392          *
 393          * @param       $seekPosition   Seek position
 394          * @param       $data                   Data to be written
 395          * @param       $flushHeader    Whether to flush the header (default: flush)
 396          * @return      void
 397          */
 398         public function writeData ($seekPosition, $data, $flushHeader = TRUE) {
 399                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] seekPosition=%s,data()=%s - CALLED!', __METHOD__, __LINE__, $seekPosition, strlen($data)));
 400
 401                 // Write data at given position
 402                 $this->getPointerInstance()->writeAtPosition($seekPosition, $data);
 403
 404                 // Increment counter
 405                 $this->incrementCounter();
 406
 407                 // Update seek position
 408                 $this->updateSeekPosition();
 409
 410                 // Flush the header?
 411                 if ($flushHeader === TRUE) {
 412                         // Flush header
 413                         $this->flushFileHeader();
 414
 415                         // Seek to old position
 416                         $this->seekToOldPosition();
 417                 } // END - if
 418
 419                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] EXIT!', __METHOD__, __LINE__));
 420         }
 421
 422         /**
 423          * Marks the currently loaded block as empty (with length of the block)
 424          *
 425          * @param       $length         Length of the block
 426          * @return      void
 427          */
 428         protected function markCurrentBlockAsEmpty ($length) {
 429                 // Get current seek position
 430                 $currentPosition = $this->key();
 431
 432                 // Now add it as gap entry
 433                 array_push($this->gaps, array(
 434                         self::GAPS_INDEX_START  => ($currentPosition - $length),
 435                         self::GAPS_INDEX_END    => $currentPosition,
 436                 ));
 437         }
 438
 439         /**
 440          * Checks whether the file header is initialized
 441          *
 442          * @return      $isInitialized  Whether the file header is initialized
 443          */
 444         public function isFileHeaderInitialized () {
 445                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 446
 447                 // Default is not initialized
 448                 $isInitialized = FALSE;
 449
 450                 // Is the file initialized?
 451                 if ($this->isFileInitialized()) {
 452                         // Some bytes has been written, so rewind to start of it.
 453                         $rewindStatus = $this->rewind();
 454                         //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] rewindStatus=%s', __METHOD__, __LINE__, $rewindStatus));
 455
 456                         // Is the rewind() call successfull?
 457                         if ($rewindStatus != 1) {
 458                                 // Something bad happened
 459                                 self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] Could not rewind().', __METHOD__, __LINE__));
 460                         } // END - if
 461
 462                         // Read file header
 463                         $this->readFileHeader();
 464
 465                         // The above method does already check the header
 466                         $isInitialized = TRUE;
 467                 } // END - if
 468
 469                 // Return result
 470                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] isInitialized=%d - EXIT!', __METHOD__, __LINE__, intval($isInitialized)));
 471                 return $isInitialized;
 472         }
 473
 474         /**
 475          * Checks whether the assigned file has been initialized
 476          *
 477          * @return      $isInitialized          Whether the file's size is zero
 478          */
 479         public function isFileInitialized () {
 480                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 481
 482                 // Get it from iterator which holds the pointer instance. If FALSE is returned
 483                 $fileSize = $this->size();
 484                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] fileSize=%s', __METHOD__, __LINE__, $fileSize));
 485
 486                 /*
 487                  * The returned file size should not be FALSE or NULL as this means
 488                  * that the pointer class does not work correctly.
 489                  */
 490                 assert(is_int($fileSize));
 491
 492                 // Is more than 0 returned?
 493                 $isInitialized = ($fileSize > 0);
 494
 495                 // Return result
 496                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] isInitialized=%d - EXIT!', __METHOD__, __LINE__, intval($isInitialized)));
 497                 return $isInitialized;
 498         }
 499
 500         /**
 501          * Creates the assigned file
 502          *
 503          * @return      void
 504          */
 505         public function createFileHeader () {
 506                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 507
 508                 // The file's header should not be initialized here
 509                 assert(!$this->isFileHeaderInitialized());
 510
 511                 // Simple flush file header which will create it.
 512                 $this->flushFileHeader();
 513
 514                 // Rewind seek position (to beginning of file) and update/flush file header
 515                 $this->rewindUpdateSeekPosition();
 516
 517                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] EXIT!', __METHOD__, __LINE__));
 518         }
 519
 520         /**
 521          * Pre-allocates file (if enabled) with some space for later faster write access.
 522          *
 523          * @param       $type   Type of the file
 524          * @return      void
 525          */
 526         public function preAllocateFile ($type) {
 527                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 528
 529                 // Is it enabled?
 530                 if ($this->getConfigInstance()->getConfigEntry($type . '_pre_allocate_enabled') != 'Y') {
 531                         // Not enabled
 532                         self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] Not pre-allocating file.', __METHOD__, __LINE__));
 533
 534                         // Don't continue here.
 535                         return;
 536                 } // END - if
 537
 538                 // Message to user
 539                 self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] Pre-allocating file ...', __METHOD__, __LINE__));
 540
 541                 // Calculate minimum length for one entry
 542                 $minLengthEntry = $this->getBlockInstance()->calculateMinimumBlockLength();
 543                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] minLengthEntry=%s', __METHOD__, __LINE__, $minLengthEntry));
 544
 545                 // Calulcate seek position
 546                 $seekPosition = $minLengthEntry * $this->getConfigInstance()->getConfigEntry($type . '_pre_allocate_count');
 547                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] seekPosition=%s', __METHOD__, __LINE__, $seekPosition));
 548
 549                 // Now simply write a NUL there. This will pre-allocate the file.
 550                 $this->writeData($seekPosition, chr(0));
 551
 552                 // Rewind seek position (to beginning of file) and update/flush file header
 553                 $this->rewindUpdateSeekPosition();
 554
 555                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] EXIT!', __METHOD__, __LINE__));
 556         }
 557
 558         /**
 559          * Determines seek position
 560          *
 561          * @return      $seekPosition   Current seek position
 562          */
 563         public function determineSeekPosition () {
 564                 // Call pointer instance
 565                 return $this->getPointerInstance()->determineSeekPosition();
 566         }
 567
 568         /**
 569          * Seek to given offset (default) or other possibilities as fseek() gives.
 570          *
 571          * @param       $offset         Offset to seek to (or used as "base" for other seeks)
 572          * @param       $whence         Added to offset (default: only use offset to seek to)
 573          * @return      $status         Status of file seek: 0 = success, -1 = failed
 574          */
 575         public function seek ($offset, $whence = SEEK_SET) {
 576                 // Call pointer instance
 577                 return $this->getPointerInstance()->seek($offset, $whence);
 578         }
 579
 580         /**
 581          * Reads given amount of bytes from file.
 582          *
 583          * @param       $bytes  Amount of bytes to read
 584          * @return      $data   Data read from file
 585          */
 586         public function read ($bytes = NULL) {
 587                 // $bytes shall be integer
 588                 assert(is_int($bytes));
 589
 590                 // Call pointer instance
 591                 return $this->getPointerInstance()->read($bytes);
 592         }
 593
 594         /**
 595          * Rewinds to the beginning of the file
 596          *
 597          * @return      $status         Status of this operation
 598          */
 599         public function rewind () {
 600                 // Call pointer instance
 601                 return $this->getPointerInstance()->rewind();
 602         }
 603
 604         /**
 605          * Analyzes entries in index file. This will count all found (and valid)
 606          * entries, mark invalid as damaged and count gaps ("fragmentation"). If
 607          * only gaps are found, the file is considered as "virgin" (no entries).
 608          *
 609          * @return      void
 610          */
 611         public function analyzeFile () {
 612                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 613
 614                 // Make sure the file is initialized
 615                 assert($this->isFileInitialized());
 616
 617                 // Init counters and gaps array
 618                 $this->initCountersGapsArray();
 619
 620                 // Output message (as this may take some time)
 621                 self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] Analyzing file structure ... (this may take some time)', __METHOD__, __LINE__));
 622
 623                 // First rewind to the begining
 624                 $this->rewind();
 625
 626                 // Then try to load all entries
 627                 while ($this->valid()) {
 628                         // Go to next entry
 629                         $this->next();
 630
 631                         // Get current entry
 632                         $current = $this->getCurrentBlock();
 633
 634                         /*
 635                          * If the block is empty, maybe the whole file is? This could mean
 636                          * that the file has been pre-allocated.
 637                          */
 638                         if (empty($current)) {
 639                                 // Then skip this part
 640                                 continue;
 641                         } // END - if
 642
 643                         // Debug message
 644                         /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] current()=%s', __METHOD__, __LINE__, strlen($current)));
 645                 } // END - while
 646
 647                 // If the last read block is empty, check gaps
 648                 if (empty($current)) {
 649                         // Output message
 650                         self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] Found a total of %s gaps.', __METHOD__, __LINE__, count($this->gaps)));
 651
 652                         // Check gaps, if the whole file is empty.
 653                         if ($this->isFileOnlyGaps()) {
 654                                 // Only gaps, so don't continue here.
 655                                 return;
 656                         } // END - if
 657
 658                         /*
 659                          * The above call has calculated a total size of all gaps. If the
 660                          * percentage of gaps passes a "soft" limit and last
 661                          * defragmentation is to far in the past, or if a "hard" limit has
 662                          * reached, run defragmentation.
 663                          */
 664                         if ($this->isDefragmentationNeeded()) {
 665                                 // Run "defragmentation"
 666                                 $this->doRunDefragmentation();
 667                         } // END - if
 668                 } // END - if
 669                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] EXIT!', __METHOD__, __LINE__));
 670         }
 671
 672         /**
 673          * Advances to next "block" of bytes
 674          *
 675          * @return      void
 676          */
 677         public function next () {
 678                 // Is there nothing to read?
 679                 if (!$this->valid()) {
 680                         // Nothing to read
 681                         return;
 682                 } // END - if
 683
 684                 // Debug message
 685                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d] key()=%s', __FUNCTION__, __LINE__, $this->key()));
 686
 687                 // Make sure the block instance is set
 688                 assert($this->getBlockInstance() instanceof CalculatableBlock);
 689
 690                 // First calculate minimum block length
 691                 $length = $this->getBlockInstance()->calculateMinimumBlockLength();
 692                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d] length=%s', __FUNCTION__, __LINE__, $length));
 693
 694                 // Short be more than zero!
 695                 assert($length > 0);
 696
 697                 // Read possibly back-buffered bytes from previous call of next().
 698                 $data = $this->getBackBuffer();
 699
 700                 /*
 701                  * Read until a entry/block separator has been found. The next read
 702                  * "block" may not fit, so this loop will continue until the EOB or EOF
 703                  * has been reached whatever comes first.
 704                  */
 705                 while ((!$this->isEndOfFileReached()) && (!self::isBlockSeparatorFound($data))) {
 706                         // Then read the next possible block
 707                         $block = $this->read($length);
 708
 709                         // Debug message
 710                         //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d] block()=%s,length=%s', __FUNCTION__, __LINE__, strlen($block), $length));
 711
 712                         // Is it all empty?
 713                         if (strlen(trim($block)) == 0) {
 714                                 // Mark this block as empty
 715                                 $this->markCurrentBlockAsEmpty(strlen($block));
 716
 717                                 // Skip to next block
 718                                 continue;
 719                         } // END - if
 720
 721                         // At this block then
 722                         $data .= $block;
 723
 724                         // A debug message
 725                         //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d] data()=%s', __FUNCTION__, __LINE__, strlen($data)));
 726                 } // END - while
 727
 728                 // EOF reached?
 729                 if ($this->isEndOfFileReached()) {
 730                         // Set whole data as current read block
 731                         //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput('Calling setCurrentBlock(' . strlen($data) . ') ...');
 732                         $this->setCurrentBlock($data);
 733
 734                         // Then abort here silently
 735                         //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput('EOF reached.');
 736                         return;
 737                 } // END - if
 738
 739                 /*
 740                  * Init back-buffer which is the data that has been found beyond the
 741                  * separator.
 742                  */
 743                 $this->initBackBuffer();
 744
 745                 // Separate data
 746                 $dataArray = explode(chr(self::SEPARATOR_ENTRIES), $data);
 747
 748                 // This array must contain two elements
 749                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput('dataArray=' . print_r($dataArray, TRUE));
 750                 assert(count($dataArray) == 2);
 751
 752                 // Left part is the actual block, right one the back-buffer data
 753                 $this->setCurrentBlock($dataArray[0]);
 754                 $this->setBackBuffer($dataArray[1]);
 755         }
 756
 757         /**
 758          * Checks wether the current entry is valid (not at the end of the file).
 759          * This method will return TRUE if an emptied (nulled) entry has been found.
 760          *
 761          * @return      $isValid        Whether the next entry is valid
 762          */
 763         public function valid () {
 764                 // Make sure the block instance is set
 765                 assert($this->getBlockInstance() instanceof Block);
 766
 767                 // First calculate minimum block length
 768                 $length = $this->getBlockInstance()->calculateMinimumBlockLength();
 769
 770                 // Short be more than zero!
 771                 assert($length > 0);
 772
 773                 // Get current seek position
 774                 $seekPosition = $this->key();
 775
 776                 // Then try to read it
 777                 $data = $this->read($length);
 778
 779                 // If some bytes could be read, all is fine
 780                 $isValid = ((is_string($data)) && (strlen($data) > 0));
 781
 782                 // Get header size
 783                 $headerSize = $this->getHeaderSize();
 784
 785                 // Is the seek position at or beyond the header?
 786                 if ($seekPosition >= $headerSize) {
 787                         // Seek back to old position
 788                         $this->seek($seekPosition);
 789                 } else {
 790                         // Seek directly behind the header
 791                         $this->seek($headerSize);
 792                 }
 793
 794                 // Return result
 795                 return $isValid;
 796         }
 797
 798         /**
 799          * Gets current seek position ("key").
 800          *
 801          * @return      $key    Current key in iteration
 802          */
 803         public function key () {
 804                 // Call pointer instance
 805                 return $this->getPointerInstance()->determineSeekPosition();
 806         }
 807
 808         /**
 809          * Reads the file header
 810          *
 811          * @return      void
 812          */
 813         public function readFileHeader () {
 814                 // Make sure the block instance is set
 815                 assert($this->getBlockInstance() instanceof Block);
 816
 817                 // Call block instance
 818                 $this->getBlockInstance()->readFileHeader();
 819         }
 820
 821         /**
 822          * Flushes the file header
 823          *
 824          * @return      void
 825          */
 826         public function flushFileHeader () {
 827                 // Make sure the block instance is set
 828                 assert($this->getBlockInstance() instanceof Block);
 829
 830                 // Call block instance
 831                 $this->getBlockInstance()->flushFileHeader();
 832         }
 833
 834         /**
 835          * Searches for next suitable gap the given length of data can fit in
 836          * including padding bytes.
 837          *
 838          * @param       $length                 Length of raw data
 839          * @return      $seekPosition   Found next gap's seek position
 840          */
 841         public function searchNextGap ($length) {
 842                 // If the file is only gaps, no need to seek
 843                 if ($this->isFileOnlyGaps()) {
 844                         // The first empty block is the first one right after the header
 845                         return ($this->getHeaderSize() + 1);
 846                 } // END - if
 847
 848                 // @TODO Unfinished
 849                 $this->partialStub('length=' . $length);
 850         }
 851 }
 852
 853 // [EOF]
 854 ?>