Writing a file on a server via URL POST

writing-file-via-query.php

<?php
error_reporting(-1);

header('Access-Control-Allow-Origin: *');

$store = isset($_POST['store']) ? substr($_POST['store'],0,10) : false;

$fp = fopen('test.txt', 'r+');

if ($store) {
    fwrite($fp, $store);
}

$contents = fread($fp, 10000);

fclose($fp);

echo $contents;