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         protected 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          * Getter for the file pointer
 316          *
 317          * @return      $filePointer    The file pointer which shall be a valid file resource
 318          * @throws      UnsupportedOperationException   If this method is called
 319          */
 320         public final function getPointer () {
 321                 throw new UnsupportedOperationException(array($this, __FUNCTION__), self::EXCEPTION_UNSPPORTED_OPERATION);
 322         }
 323
 324         /**
 325          * Initializes the back-buffer by setting it to an empty string.
 326          *
 327          * @return      void
 328          */
 329         private function initBackBuffer () {
 330                 // Simply call the setter
 331                 $this->setBackBuffer('');
 332         }
 333
 334         /**
 335          * Setter for backBuffer field
 336          *
 337          * @param       $backBuffer             Characters to "store" in back-buffer
 338          * @return      void
 339          */
 340         private function setBackBuffer ($backBuffer) {
 341                 // Cast to string (so no arrays or objects)
 342                 $backBuffer = (string) $backBuffer;
 343
 344                 // ... and set it
 345                 $this->backBuffer = $backBuffer;
 346         }
 347
 348         /**
 349          * Getter for backBuffer field
 350          *
 351          * @return      $backBuffer             Characters "stored" in back-buffer
 352          */
 353         private function getBackBuffer () {
 354                 return $this->backBuffer;
 355         }
 356
 357         /**
 358          * Setter for currentBlock field
 359          *
 360          * @param       $currentBlock           Characters to set a currently loaded block
 361          * @return      void
 362          */
 363         private function setCurrentBlock ($currentBlock) {
 364                 // Cast to string (so no arrays or objects)
 365                 $currentBlock = (string) $currentBlock;
 366
 367                 // ... and set it
 368                 $this->currentBlock = $currentBlock;
 369         }
 370
 371         /**
 372          * Gets currently read data
 373          *
 374          * @return      $current        Currently read data
 375          */
 376         public function getCurrentBlock () {
 377                 // Return it
 378                 return $this->currentBlock;
 379         }
 380
 381         /**
 382          * Initializes this file class
 383          *
 384          * @param       $fileName       Name of this abstract file
 385          * @return      void
 386          */
 387         protected function initFile ($fileName) {
 388                 // Get a file i/o pointer instance
 389                 $pointerInstance = ObjectFactory::createObjectByConfiguredName('file_raw_input_output_class', array($fileName));
 390
 391                 // ... and set it here
 392                 $this->setPointerInstance($pointerInstance);
 393         }
 394
 395         /**
 396          * Writes data at given position
 397          *
 398          * @param       $seekPosition   Seek position
 399          * @param       $data                   Data to be written
 400          * @param       $flushHeader    Whether to flush the header (default: flush)
 401          * @return      void
 402          */
 403         protected function writeData ($seekPosition, $data, $flushHeader = TRUE) {
 404                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] seekPosition=%s,data()=%s - CALLED!', __METHOD__, __LINE__, $seekPosition, strlen($data)));
 405
 406                 // Write data at given position
 407                 $this->getPointerInstance()->writeAtPosition($seekPosition, $data);
 408
 409                 // Update seek position
 410                 $this->updateSeekPosition();
 411
 412                 // Flush the header?
 413                 if ($flushHeader === TRUE) {
 414                         // Flush header
 415                         $this->flushFileHeader();
 416
 417                         // Seek to old position
 418                         $this->seekToOldPosition();
 419                 } // END - if
 420
 421                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] EXIT!', __METHOD__, __LINE__));
 422         }
 423
 424         /**
 425          * Marks the currently loaded block as empty (with length of the block)
 426          *
 427          * @param       $length         Length of the block
 428          * @return      void
 429          */
 430         protected function markCurrentBlockAsEmpty ($length) {
 431                 // Get current seek position
 432                 $currentPosition = $this->key();
 433
 434                 // Now add it as gap entry
 435                 array_push($this->gaps, array(
 436                         self::GAPS_INDEX_START  => ($currentPosition - $length),
 437                         self::GAPS_INDEX_END    => $currentPosition,
 438                 ));
 439         }
 440
 441         /**
 442          * Checks whether the file header is initialized
 443          *
 444          * @return      $isInitialized  Whether the file header is initialized
 445          */
 446         public function isFileHeaderInitialized () {
 447                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 448
 449                 // Default is not initialized
 450                 $isInitialized = FALSE;
 451
 452                 // Is the file initialized?
 453                 if ($this->isFileInitialized()) {
 454                         // Some bytes has been written, so rewind to start of it.
 455                         $rewindStatus = $this->rewind();
 456                         //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] rewindStatus=%s', __METHOD__, __LINE__, $rewindStatus));
 457
 458                         // Is the rewind() call successfull?
 459                         if ($rewindStatus != 1) {
 460                                 // Something bad happened
 461                                 self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] Could not rewind().', __METHOD__, __LINE__));
 462                         } // END - if
 463
 464                         // Read file header
 465                         $this->readFileHeader();
 466
 467                         // The above method does already check the header
 468                         $isInitialized = TRUE;
 469                 } // END - if
 470
 471                 // Return result
 472                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] isInitialized=%d - EXIT!', __METHOD__, __LINE__, intval($isInitialized)));
 473                 return $isInitialized;
 474         }
 475
 476         /**
 477          * Checks whether the assigned file has been initialized
 478          *
 479          * @return      $isInitialized          Whether the file's size is zero
 480          */
 481         public function isFileInitialized () {
 482                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 483
 484                 // Get it from iterator which holds the pointer instance. If FALSE is returned
 485                 $fileSize = $this->size();
 486                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] fileSize=%s', __METHOD__, __LINE__, $fileSize));
 487
 488                 /*
 489                  * The returned file size should not be FALSE or NULL as this means
 490                  * that the pointer class does not work correctly.
 491                  */
 492                 assert(is_int($fileSize));
 493
 494                 // Is more than 0 returned?
 495                 $isInitialized = ($fileSize > 0);
 496
 497                 // Return result
 498                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] isInitialized=%d - EXIT!', __METHOD__, __LINE__, intval($isInitialized)));
 499                 return $isInitialized;
 500         }
 501
 502         /**
 503          * Creates the assigned file
 504          *
 505          * @return      void
 506          */
 507         public function createFileHeader () {
 508                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 509
 510                 // The file's header should not be initialized here
 511                 assert(!$this->isFileHeaderInitialized());
 512
 513                 // Simple flush file header which will create it.
 514                 $this->flushFileHeader();
 515
 516                 // Rewind seek position (to beginning of file) and update/flush file header
 517                 $this->rewindUpdateSeekPosition();
 518
 519                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] EXIT!!', __METHOD__, __LINE__));
 520         }
 521
 522         /**
 523          * Pre-allocates file (if enabled) with some space for later faster write access.
 524          *
 525          * @param       $type   Type of the file
 526          * @return      void
 527          */
 528         public function preAllocateFile ($type) {
 529                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 530
 531                 // Is it enabled?
 532                 if ($this->getConfigInstance()->getConfigEntry($type . '_pre_allocate_enabled') != 'Y') {
 533                         // Not enabled
 534                         self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] Not pre-allocating file.', __METHOD__, __LINE__));
 535
 536                         // Don't continue here.
 537                         return;
 538                 } // END - if
 539
 540                 // Message to user
 541                 self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] Pre-allocating file ...', __METHOD__, __LINE__));
 542
 543                 // Calculate minimum length for one entry
 544                 $minLengthEntry = $this->getBlockInstance()->calculateMinimumBlockLength();
 545                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] minLengthEntry=%s', __METHOD__, __LINE__, $minLengthEntry));
 546
 547                 // Calulcate seek position
 548                 $seekPosition = $minLengthEntry * $this->getConfigInstance()->getConfigEntry($type . '_pre_allocate_count');
 549                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] seekPosition=%s', __METHOD__, __LINE__, $seekPosition));
 550
 551                 // Now simply write a NUL there. This will pre-allocate the file.
 552                 $this->writeData($seekPosition, chr(0));
 553
 554                 // Rewind seek position (to beginning of file) and update/flush file header
 555                 $this->rewindUpdateSeekPosition();
 556
 557                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] EXIT!', __METHOD__, __LINE__));
 558         }
 559
 560         /**
 561          * Determines seek position
 562          *
 563          * @return      $seekPosition   Current seek position
 564          */
 565         public function determineSeekPosition () {
 566                 // Call pointer instance
 567                 return $this->getPointerInstance()->determineSeekPosition();
 568         }
 569
 570         /**
 571          * Seek to given offset (default) or other possibilities as fseek() gives.
 572          *
 573          * @param       $offset         Offset to seek to (or used as "base" for other seeks)
 574          * @param       $whence         Added to offset (default: only use offset to seek to)
 575          * @return      $status         Status of file seek: 0 = success, -1 = failed
 576          */
 577         public function seek ($offset, $whence = SEEK_SET) {
 578                 // Call pointer instance
 579                 return $this->getPointerInstance()->seek($offset, $whence);
 580         }
 581
 582         /**
 583          * Reads given amount of bytes from file.
 584          *
 585          * @param       $bytes  Amount of bytes to read
 586          * @return      $data   Data read from file
 587          */
 588         public function read ($bytes) {
 589                 // Call pointer instance
 590                 return $this->getPointerInstance()->read($bytes);
 591         }
 592
 593         /**
 594          * Rewinds to the beginning of the file
 595          *
 596          * @return      $status         Status of this operation
 597          */
 598         public function rewind () {
 599                 // Call pointer instance
 600                 return $this->getPointerInstance()->rewind();
 601         }
 602
 603         /**
 604          * Analyzes entries in index file. This will count all found (and valid)
 605          * entries, mark invalid as damaged and count gaps ("fragmentation"). If
 606          * only gaps are found, the file is considered as "virgin" (no entries).
 607          *
 608          * @return      void
 609          */
 610         public function analyzeFile () {
 611                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 612
 613                 // Make sure the file is initialized
 614                 assert($this->isFileInitialized());
 615
 616                 // Init counters and gaps array
 617                 $this->initCountersGapsArray();
 618
 619                 // Output message (as this may take some time)
 620                 self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] Analyzing file structure ... (this may take some time)', __METHOD__, __LINE__));
 621
 622                 // First rewind to the begining
 623                 $this->rewind();
 624
 625                 // Then try to load all entries
 626                 while ($this->valid()) {
 627                         // Go to next entry
 628                         $this->next();
 629
 630                         // Get current entry
 631                         $current = $this->getCurrentBlock();
 632
 633                         /*
 634                          * If the block is empty, maybe the whole file is? This could mean
 635                          * that the file has been pre-allocated.
 636                          */
 637                         if (empty($current)) {
 638                                 // Then skip this part
 639                                 continue;
 640                         } // END - if
 641
 642                         // Debug message
 643                         /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] current()=%s', __METHOD__, __LINE__, strlen($current)));
 644                 } // END - while
 645
 646                 // If the last read block is empty, check gaps
 647                 if (empty($current)) {
 648                         // Output message
 649                         self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] Found a total of %s gaps.', __METHOD__, __LINE__, count($this->gaps)));
 650
 651                         // Check gaps, if the whole file is empty.
 652                         if ($this->isFileOnlyGaps()) {
 653                                 // Only gaps, so don't continue here.
 654                                 return;
 655                         } // END - if
 656
 657                         /*
 658                          * The above call has calculated a total size of all gaps. If the
 659                          * percentage of gaps passes a "soft" limit and last
 660                          * defragmentation is to far in the past, or if a "hard" limit has
 661                          * reached, run defragmentation.
 662                          */
 663                         if ($this->isDefragmentationNeeded()) {
 664                                 // Run "defragmentation"
 665                                 $this->doRunDefragmentation();
 666                         } // END - if
 667                 } // END - if
 668                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] EXIT!', __METHOD__, __LINE__));
 669         }
 670
 671         /**
 672          * Advances to next "block" of bytes
 673          *
 674          * @return      void
 675          */
 676         public function next () {
 677                 // Is there nothing to read?
 678                 if (!$this->valid()) {
 679                         // Nothing to read
 680                         return;
 681                 } // END - if
 682
 683                 // Debug message
 684                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d] key()=%s', __FUNCTION__, __LINE__, $this->key()));
 685
 686                 // Make sure the block instance is set
 687                 assert($this->getBlockInstance() instanceof CalculatableBlock);
 688
 689                 // First calculate minimum block length
 690                 $length = $this->getBlockInstance()->calculateMinimumBlockLength();
 691                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d] length=%s', __FUNCTION__, __LINE__, $length));
 692
 693                 // Short be more than zero!
 694                 assert($length > 0);
 695
 696                 // Read possibly back-buffered bytes from previous call of next().
 697                 $data = $this->getBackBuffer();
 698
 699                 /*
 700                  * Read until a entry/block separator has been found. The next read
 701                  * "block" may not fit, so this loop will continue until the EOB or EOF
 702                  * has been reached whatever comes first.
 703                  */
 704                 while ((!$this->isEndOfFileReached()) && (!self::isBlockSeparatorFound($data))) {
 705                         // Then read the next possible block
 706                         $block = $this->read($length);
 707
 708                         // Debug message
 709                         //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d] block()=%s,length=%s', __FUNCTION__, __LINE__, strlen($block), $length));
 710
 711                         // Is it all empty?
 712                         if (strlen(trim($block)) == 0) {
 713                                 // Mark this block as empty
 714                                 $this->markCurrentBlockAsEmpty(strlen($block));
 715
 716                                 // Skip to next block
 717                                 continue;
 718                         } // END - if
 719
 720                         // At this block then
 721                         $data .= $block;
 722
 723                         // A debug message
 724                         //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d] data()=%s', __FUNCTION__, __LINE__, strlen($data)));
 725                 } // END - while
 726
 727                 // EOF reached?
 728                 if ($this->isEndOfFileReached()) {
 729                         // Set whole data as current read block
 730                         //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput('Calling setCurrentBlock(' . strlen($data) . ') ...');
 731                         $this->setCurrentBlock($data);
 732
 733                         // Then abort here silently
 734                         //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput('EOF reached.');
 735                         return;
 736                 } // END - if
 737
 738                 /*
 739                  * Init back-buffer which is the data that has been found beyond the
 740                  * separator.
 741                  */
 742                 $this->initBackBuffer();
 743
 744                 // Separate data
 745                 $dataArray = explode(chr(self::SEPARATOR_ENTRIES), $data);
 746
 747                 // This array must contain two elements
 748                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput('dataArray=' . print_r($dataArray, TRUE));
 749                 assert(count($dataArray) == 2);
 750
 751                 // Left part is the actual block, right one the back-buffer data
 752                 $this->setCurrentBlock($dataArray[0]);
 753                 $this->setBackBuffer($dataArray[1]);
 754         }
 755
 756         /**
 757          * Checks wether the current entry is valid (not at the end of the file).
 758          * This method will return TRUE if an emptied (nulled) entry has been found.
 759          *
 760          * @return      $isValid        Whether the next entry is valid
 761          */
 762         public function valid () {
 763                 // Make sure the block instance is set
 764                 assert($this->getBlockInstance() instanceof Block);
 765
 766                 // First calculate minimum block length
 767                 $length = $this->getBlockInstance()->calculateMinimumBlockLength();
 768
 769                 // Short be more than zero!
 770                 assert($length > 0);
 771
 772                 // Get current seek position
 773                 $seekPosition = $this->key();
 774
 775                 // Then try to read it
 776                 $data = $this->read($length);
 777
 778                 // If some bytes could be read, all is fine
 779                 $isValid = ((is_string($data)) && (strlen($data) > 0));
 780
 781                 // Get header size
 782                 $headerSize = $this->getHeaderSize();
 783
 784                 // Is the seek position at or beyond the header?
 785                 if ($seekPosition >= $headerSize) {
 786                         // Seek back to old position
 787                         $this->seek($seekPosition);
 788                 } else {
 789                         // Seek directly behind the header
 790                         $this->seek($headerSize);
 791                 }
 792
 793                 // Return result
 794                 return $isValid;
 795         }
 796
 797         /**
 798          * Gets current seek position ("key").
 799          *
 800          * @return      $key    Current key in iteration
 801          */
 802         public function key () {
 803                 // Call pointer instance
 804                 return $this->getPointerInstance()->determineSeekPosition();
 805         }
 806
 807         /**
 808          * Reads the file header
 809          *
 810          * @return      void
 811          */
 812         public function readFileHeader () {
 813                 // Make sure the block instance is set
 814                 assert($this->getBlockInstance() instanceof Block);
 815
 816                 // Call block instance
 817                 $this->getBlockInstance()->readFileHeader();
 818         }
 819
 820         /**
 821          * Flushes the file header
 822          *
 823          * @return      void
 824          */
 825         public function flushFileHeader () {
 826                 // Make sure the block instance is set
 827                 assert($this->getBlockInstance() instanceof Block);
 828
 829                 // Call block instance
 830                 $this->getBlockInstance()->flushFileHeader();
 831         }
 832 }
 833
 834 // [EOF]
 835 ?>