<?php
namespace PhpZip\Extra\Fields;
use PhpZip\Exception\InvalidArgumentException;
use PhpZip\Extra\ExtraField;
/**
* Apk Alignment Extra Field
*
* @author Ne-Lexa [email protected]
* @license MIT
*/
class ApkAlignmentExtraField implements ExtraField
{
/**
* Minimum size (in bytes) of the extensible data block/field used
* for alignment of uncompressed entries.
*/
const ALIGNMENT_ZIP_EXTRA_MIN_SIZE_BYTES = 6;
const ANDROID_COMMON_PAGE_ALIGNMENT_BYTES = 4096;
/**
* @var int
*/
private $multiple;
/**
* @var int
*/
private $padding;
/**
* Returns the Header ID (type) of this Extra Field.
* The Header ID is an unsigned short integer (two bytes)
* which must be constant during the life cycle of this object.
*
* @return int
*/
public static function getHeaderId()
{
return 0xD935;
}
/**
* Serializes a Data Block.
* @return string
*/
public function serialize()
{
if ($this->padding > 0) {
$args = array_merge(
['vc*', $this->multiple],
array_fill(2, $this->padding, 0)
);
return call_user_func_array('pack', $args);
}
return pack('v', $this->multiple);
}
/**
* Initializes this Extra Field by deserializing a Data Block.
* @param string $data
*/
public function deserialize($data)
{
$length = strlen($data);
if ($length < 2) {
// This is APK alignment field.
// FORMAT:
// * uint16 alignment multiple (in bytes)
// * remaining bytes -- padding to achieve alignment of data which starts after
// the extra field
throw new InvalidArgumentException("Minimum 6 bytes of the extensible data block/field used for alignment of uncompressed entries.");
}
$this->multiple = unpack('v', $data)[1];
$this->padding = $length - 2;
}
/**
* @return mixed
*/
public function getMultiple()
{
return $this->multiple;
}
/**
* @return int
*/
public function getPadding()
{
return $this->padding;
}
/**
* @param int $multiple
*/
public function setMultiple($multiple)
{
$this->multiple = $multiple;
}
/**
* @param int $padding
*/
public function setPadding($padding)
{
$this->padding = $padding;
}
}