Fetch everything in a folder based on extension and put into zip - php

Question

I have to make 3 buttons. On button click I want to download all files from selected folder with correct extension in zip file. Eveything on wordpress site. The problem is, zip file is saving as .zip, but when I open it in notepad, there's HTML code. Thanks for help!
<?php
if(isset($_POST['3dsdownload'])) {dddownloads();}
function dddownloads(){
$dir = realpath("/autoinstalator/wordpress/wp-content/uploads/");
$scan_arr = scandir($dir);
$zip = new ZipArchive();
$zip->open('3ds.zip', ZipArchive::CREATE);
$files = array_diff($scan_arr, array('.','..') );
foreach ($files as $name => $file) {
if (!is_dir($file)){
$filePath = $dir.$file;
$file_ext = pathinfo($filePath, PATHINFO_EXTENSION);
if ($file_ext=="3ds" || $file_ext=="3DS") {
$zip->addFile($filePath, basename($filePath));
}
}
}
$zip->close();
header('Content-disposition: attachment; filename=3ds.zip');
header('Content-type: application/zip');
readfile('3ds.zip');
exit;
}
?>
<form method="post">
<input type="submit" name="3dsdownload"
value="3dsdownload"/>
</form>

Answer 1

The problem was buffer and path. After adding ob_clean() and fixing path, everything works fine! Final code:
<?php //Strona z pobieraniem wszystkich plikow z podziałem na formaty
//3ds
if(isset($_POST['3dsdownload'])) {dddownloads();}
function dddownloads(){
ob_clean();
$dir = (dirname(__DIR__,2)."/uploads/");
$scan_arr = scandir($dir);
$zip = new ZipArchive();
$zip->open('3ds.zip', ZipArchive::CREATE | ZIPARCHIVE::OVERWRITE);
$files = array_diff($scan_arr, array('.','..') );
foreach ($files as $name => $file) {
if (!is_dir($file)){
$filePath = $dir.$file;
$file_ext = pathinfo($filePath, PATHINFO_EXTENSION);
if ($file_ext=="3ds" || $file_ext=="3DS") {
$zip->addFile($filePath, basename($filePath));
}
}
}
$zip->close();
header('Content-disposition: attachment; filename=3ds.zip');
header('Content-type: application/zip');
header("Content-Transfer-Encoding: binary");
ob_end_clean();
readfile('3ds.zip');
exit;
}
?>