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<?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\StreamReader;
/**
* Class LineReader
*
* This reader class read all cross-reference entries in a single run.
* It supports reading cross-references with e.g. invalid data (e.g. entries with a length < or > 20 bytes).
*/
class LineReader extends AbstractReader implements ReaderInterface
{
/**
* The object offsets.
*
* @var array
*/
protected $offsets;
/**
* LineReader constructor.
*
* @param PdfParser $parser
* @throws CrossReferenceException
*/
public function __construct(PdfParser $parser)
{
$this->read($this->extract($parser->getStreamReader()));
parent::__construct($parser);
}
/**
* @inheritdoc
*/
public function getOffsetFor($objectNumber)
{
if (isset($this->offsets[$objectNumber])) {
return $this->offsets[$objectNumber][0];
}
return false;
}
/**
* Get all found offsets.
*
* @return array
*/
public function getOffsets()
{
return $this->offsets;
}
/**
* Extracts the cross reference data from the stream reader.
*
* @param StreamReader $reader
* @return string
* @throws CrossReferenceException
*/
protected function extract(StreamReader $reader)
{
$bytesPerCycle = 100;
$reader->reset(null, $bytesPerCycle);
$cycles = 0;
do {
// 6 = length of "trailer" - 1
$pos = \max(($bytesPerCycle * $cycles) - 6, 0);
$trailerPos = \strpos($reader->getBuffer(false), 'trailer', $pos);
$cycles++;
} while ($trailerPos === false && $reader->increaseLength($bytesPerCycle) !== false);
if ($trailerPos === false) {
throw new CrossReferenceException(
'Unexpected end of cross reference. "trailer"-keyword not found.',
CrossReferenceException::NO_TRAILER_FOUND
);
}
$xrefContent = \substr($reader->getBuffer(false), 0, $trailerPos);
$reader->reset($reader->getPosition() + $trailerPos);
return $xrefContent;
}
/**
* Read the cross-reference entries.
*
* @param string $xrefContent
* @throws CrossReferenceException
*/
protected function read($xrefContent)
{
// get eol markers in the first 100 bytes
\preg_match_all("/(\r\n|\n|\r)/", \substr($xrefContent, 0, 100), $m);
if (\count($m[0]) === 0) {
throw new CrossReferenceException(
'No data found in cross-reference.',
CrossReferenceException::INVALID_DATA
);
}
// count(array_count_values()) is faster then count(array_unique())
// @see https://github.com/symfony/symfony/pull/23731
// can be reverted for php7.2
$differentLineEndings = \count(\array_count_values($m[0]));
if ($differentLineEndings > 1) {
$lines = \preg_split("/(\r\n|\n|\r)/", $xrefContent, -1, PREG_SPLIT_NO_EMPTY);
} else {
$lines = \explode($m[0][0], $xrefContent);
}
unset($differentLineEndings, $m);
if (!\is_array($lines)) {
$this->offsets = [];
return;
}
$start = 0;
$offsets = [];
// trim all lines and remove empty lines
$lines = \array_filter(\array_map('\trim', $lines));
foreach ($lines as $line) {
$pieces = \explode(' ', $line);
switch (\count($pieces)) {
case 2:
$start = (int) $pieces[0];
break;
case 3:
switch ($pieces[2]) {
case 'n':
$offsets[$start] = [(int) $pieces[0], (int) $pieces[1]];
$start++;
break 2;
case 'f':
$start++;
break 2;
}
// fall through if pieces doesn't match
default:
throw new CrossReferenceException(
\sprintf('Unexpected data in xref table (%s)', \implode(' ', $pieces)),
CrossReferenceException::INVALID_DATA
);
}
}
$this->offsets = $offsets;
}
}
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