PHPでzipファイル内の画像ファイルを表示

<?php
$baseDir = "./archives";

if (!isset($_GET['name'])){
    return;
}

$name = htmlspecialchars($_GET["name"]);
$file = $baseDir . DIRECTORY_SEPARATOR . $name;

if (!isset($_GET["pageNo"])) {
    $zip = new ZipArchive;
    if ($zip->open($file)) {
    
        for($i=0;$i < $zip->numFiles;$i++){
            echo ($zip->getNameIndex($i) . "\n");
        }
    
        $zip->close();
    }
}
else {
    $page = "";
    $pageNo = htmlspecialchars($_GET["pageNo"]);

    $zip = new ZipArchive;
    if ($zip->open($file)) {
        $i = intval($pageNo);
        $page = $zip->getNameIndex($i);    
        $zip->close();
    }

    if ($page == "") {
        return;
    }

    $url = 'zip://' . dirname(__FILE__) . '/archives/' . $name . '#' . $page;
    
    $ext = pathinfo($page, PATHINFO_EXTENSION);

    if ($ext == "png") {
        $im = imagecreatefrompng($url);
        header('Content-Type: image/png');
        imagepng($im);
        imagedestroy($im);    
    }
    elseif ($ext == "gif") {
        $im = imagecreatefromgif($url);
        header('Content-Type: image/gif');
        imagegif($im);
        imagedestroy($im);    
    }
    elseif ($ext == "jpg") {
        $im = imagecreatefromjpeg($url);
        header('Content-Type: image/jpeg');
        imagejpeg($im);
        imagedestroy($im);    
    }
}

?>