diff options
Diffstat (limited to 'vendor/setasign/fpdi/src/PdfParser/CrossReference/CrossReference.php')
| -rw-r--r-- | vendor/setasign/fpdi/src/PdfParser/CrossReference/CrossReference.php | 326 |
1 files changed, 326 insertions, 0 deletions
diff --git a/vendor/setasign/fpdi/src/PdfParser/CrossReference/CrossReference.php b/vendor/setasign/fpdi/src/PdfParser/CrossReference/CrossReference.php new file mode 100644 index 0000000..c47e8c4 --- /dev/null +++ b/vendor/setasign/fpdi/src/PdfParser/CrossReference/CrossReference.php @@ -0,0 +1,326 @@ +<?php + +/** + * This file is part of FPDI + * + * @package setasign\Fpdi + * @copyright Copyright (c) 2020 Setasign GmbH & Co. KG (https://www.setasign.com) + * @license http://opensource.org/licenses/mit-license The MIT License + */ + +namespace setasign\Fpdi\PdfParser\CrossReference; + +use setasign\Fpdi\PdfParser\PdfParser; +use setasign\Fpdi\PdfParser\Type\PdfDictionary; +use setasign\Fpdi\PdfParser\Type\PdfIndirectObject; +use setasign\Fpdi\PdfParser\Type\PdfNumeric; +use setasign\Fpdi\PdfParser\Type\PdfStream; +use setasign\Fpdi\PdfParser\Type\PdfToken; +use setasign\Fpdi\PdfParser\Type\PdfTypeException; + +/** + * Class CrossReference + * + * This class processes the standard cross reference of a PDF document. + */ +class CrossReference +{ + /** + * The byte length in which the "startxref" keyword should be searched. + * + * @var int + */ + public static $trailerSearchLength = 5500; + + /** + * @var int + */ + protected $fileHeaderOffset = 0; + + /** + * @var PdfParser + */ + protected $parser; + + /** + * @var ReaderInterface[] + */ + protected $readers = []; + + /** + * CrossReference constructor. + * + * @param PdfParser $parser + * @throws CrossReferenceException + * @throws PdfTypeException + */ + public function __construct(PdfParser $parser, $fileHeaderOffset = 0) + { + $this->parser = $parser; + $this->fileHeaderOffset = $fileHeaderOffset; + + $offset = $this->findStartXref(); + $reader = null; + /** @noinspection TypeUnsafeComparisonInspection */ + while ($offset != false) { // By doing an unsafe comparsion we ignore faulty references to byte offset 0 + try { + $reader = $this->readXref($offset + $this->fileHeaderOffset); + } catch (CrossReferenceException $e) { + // sometimes the file header offset is part of the byte offsets, so let's retry by resetting it to zero. + if ($e->getCode() === CrossReferenceException::INVALID_DATA && $this->fileHeaderOffset !== 0) { + $this->fileHeaderOffset = 0; + $reader = $this->readXref($offset + $this->fileHeaderOffset); + } else { + throw $e; + } + } + + $trailer = $reader->getTrailer(); + $this->checkForEncryption($trailer); + $this->readers[] = $reader; + + if (isset($trailer->value['Prev'])) { + $offset = $trailer->value['Prev']->value; + } else { + $offset = false; + } + } + + // fix faulty sub-section header + if ($reader instanceof FixedReader) { + /** + * @var FixedReader $reader + */ + $reader->fixFaultySubSectionShift(); + } + + if ($reader === null) { + throw new CrossReferenceException('No cross-reference found.', CrossReferenceException::NO_XREF_FOUND); + } + } + + /** + * Get the size of the cross reference. + * + * @return integer + */ + public function getSize() + { + return $this->getTrailer()->value['Size']->value; + } + + /** + * Get the trailer dictionary. + * + * @return PdfDictionary + */ + public function getTrailer() + { + return $this->readers[0]->getTrailer(); + } + + /** + * Get the cross reference readser instances. + * + * @return ReaderInterface[] + */ + public function getReaders() + { + return $this->readers; + } + + /** + * Get the offset by an object number. + * + * @param int $objectNumber + * @return integer|bool + */ + public function getOffsetFor($objectNumber) + { + foreach ($this->getReaders() as $reader) { + $offset = $reader->getOffsetFor($objectNumber); + if ($offset !== false) { + return $offset; + } + } + + return false; + } + + /** + * Get an indirect object by its object number. + * + * @param int $objectNumber + * @return PdfIndirectObject + * @throws CrossReferenceException + */ + public function getIndirectObject($objectNumber) + { + $offset = $this->getOffsetFor($objectNumber); + if ($offset === false) { + throw new CrossReferenceException( + \sprintf('Object (id:%s) not found.', $objectNumber), + CrossReferenceException::OBJECT_NOT_FOUND + ); + } + + $parser = $this->parser; + + $parser->getTokenizer()->clearStack(); + $parser->getStreamReader()->reset($offset + $this->fileHeaderOffset); + + try { + /** @var PdfIndirectObject $object */ + $object = $parser->readValue(null, PdfIndirectObject::class); + } catch (PdfTypeException $e) { + throw new CrossReferenceException( + \sprintf('Object (id:%s) not found at location (%s).', $objectNumber, $offset), + CrossReferenceException::OBJECT_NOT_FOUND, + $e + ); + } + + if ($object->objectNumber !== $objectNumber) { + throw new CrossReferenceException( + \sprintf('Wrong object found, got %s while %s was expected.', $object->objectNumber, $objectNumber), + CrossReferenceException::OBJECT_NOT_FOUND + ); + } + + return $object; + } + + /** + * Read the cross-reference table at a given offset. + * + * Internally the method will try to evaluate the best reader for this cross-reference. + * + * @param int $offset + * @return ReaderInterface + * @throws CrossReferenceException + * @throws PdfTypeException + */ + protected function readXref($offset) + { + $this->parser->getStreamReader()->reset($offset); + $this->parser->getTokenizer()->clearStack(); + $initValue = $this->parser->readValue(); + + return $this->initReaderInstance($initValue); + } + + /** + * Get a cross-reference reader instance. + * + * @param PdfToken|PdfIndirectObject $initValue + * @return ReaderInterface|bool + * @throws CrossReferenceException + * @throws PdfTypeException + */ + protected function initReaderInstance($initValue) + { + $position = $this->parser->getStreamReader()->getPosition() + + $this->parser->getStreamReader()->getOffset() + $this->fileHeaderOffset; + + if ($initValue instanceof PdfToken && $initValue->value === 'xref') { + try { + return new FixedReader($this->parser); + } catch (CrossReferenceException $e) { + $this->parser->getStreamReader()->reset($position); + $this->parser->getTokenizer()->clearStack(); + + return new LineReader($this->parser); + } + } + + if ($initValue instanceof PdfIndirectObject) { + try { + $stream = PdfStream::ensure($initValue->value); + } catch (PdfTypeException $e) { + throw new CrossReferenceException( + 'Invalid object type at xref reference offset.', + CrossReferenceException::INVALID_DATA, + $e + ); + } + + $type = PdfDictionary::get($stream->value, 'Type'); + if ($type->value !== 'XRef') { + throw new CrossReferenceException( + 'The xref position points to an incorrect object type.', + CrossReferenceException::INVALID_DATA + ); + } + + $this->checkForEncryption($stream->value); + + throw new CrossReferenceException( + 'This PDF document probably uses a compression technique which is not supported by the ' . + 'free parser shipped with FPDI. (See https://www.setasign.com/fpdi-pdf-parser for more details)', + CrossReferenceException::COMPRESSED_XREF + ); + } + + throw new CrossReferenceException( + 'The xref position points to an incorrect object type.', + CrossReferenceException::INVALID_DATA + ); + } + + /** + * Check for encryption. + * + * @param PdfDictionary $dictionary + * @throws CrossReferenceException + */ + protected function checkForEncryption(PdfDictionary $dictionary) + { + if (isset($dictionary->value['Encrypt'])) { + throw new CrossReferenceException( + 'This PDF document is encrypted and cannot be processed with FPDI.', + CrossReferenceException::ENCRYPTED + ); + } + } + + /** + * Find the start position for the first cross-reference. + * + * @return int The byte-offset position of the first cross-reference. + * @throws CrossReferenceException + */ + protected function findStartXref() + { + $reader = $this->parser->getStreamReader(); + $reader->reset(-self::$trailerSearchLength, self::$trailerSearchLength); + + $buffer = $reader->getBuffer(false); + $pos = \strrpos($buffer, 'startxref'); + $addOffset = 9; + if ($pos === false) { + // Some corrupted documents uses startref, instead of startxref + $pos = \strrpos($buffer, 'startref'); + if ($pos === false) { + throw new CrossReferenceException( + 'Unable to find pointer to xref table', + CrossReferenceException::NO_STARTXREF_FOUND + ); + } + $addOffset = 8; + } + + $reader->setOffset($pos + $addOffset); + + try { + $value = $this->parser->readValue(null, PdfNumeric::class); + } catch (PdfTypeException $e) { + throw new CrossReferenceException( + 'Invalid data after startxref keyword.', + CrossReferenceException::INVALID_DATA, + $e + ); + } + + return $value->value; + } +} |