<?php
declare(strict_types=1);
namespace PhpMyAdmin\WebAuthn;
use function fopen;
use function fread;
use function ftell;
use function fwrite;
use function rewind;
final class DataStream
{
/** @var resource */
private $stream;
/**
* @throws WebAuthnException
*/
public function __construct(string $binaryString)
{
$resource = fopen('php://memory', 'rb+');
if ($resource === false || fwrite($resource, $binaryString) === false) {
throw new WebAuthnException();
}
if (! rewind($resource)) {
throw new WebAuthnException();
}
$this->stream = $resource;
}
/**
* @throws WebAuthnException
*/
public function take(int $length): string
{
if ($length < 0) {
throw new WebAuthnException();
}
if ($length === 0) {
return '';
}
$string = fread($this->stream, $length);
if ($string === false) {
throw new WebAuthnException();
}
return $string;
}
/**
* @throws WebAuthnException
*/
public function getPosition(): int
{
$position = ftell($this->stream);
if ($position === false) {
throw new WebAuthnException();
}
return $position;
}
}