corrupt files after upload in php - php

Question

I have written php script for upload file. It seems to work properly but when open uploaded file in upload folder i get this error:
unknown format or damaged
my code:
HTML:
<form method="POST" action="<?=URL?>user/homework" enctype="multipart/form-data">
<input type="hidden" id="csrf" name="csrf" value="<?= $_SESSION['csrf'] ?>" />
<table class="table table-responsive">
<tr>
<td><label>file</label></td>
<td><input multiple="multiple" type="file" name="file"/></td>
</tr>
</table>
<input type="submit" name="sub" value="submit" class="btn btn-success"/>
</form>
PHP:
if (isset($_POST['sub'])) {
if (Security::chekCsrf($_POST['csrf']) == FALSE) {
$data = array('', 'dan');
$this->render('homework', $data);
exit();
}
if (!empty($_FILES['file'])) {
$name = time() . '_' . $_FILES['file']['name'];
if ($_FILES['file']['size'] > 20971520) {
$data = array('size high', 'war');
$this->render('homework', $data);
exit();
}
$valid = array('application/octet-stream', 'application/x-rar-compressed', 'application/zip');
$type = $_FILES['file']['type'];
if (!in_array($type, $valid)) {
$data = array('wrong format', 'war');
$this->render('homework', $data);
exit();
}
$dir = 'upload/' . $name;
if (move_uploaded_file($_FILES['file']['tmp_name'], $dir)) {
$data = array('ok', 'suc');
$this->render('homework', $data);
exit();
} else {
$data = array('problem', 'dan');
$this->render('homework', $data);
exit();
}
}
}

Answer 1

Had the same issue. Turns out i had two trailing spaces Outside of the quotations on a php file i use as a handler. Not knowing this can actually corrupt a file on upload. Then this 'unrecognised format' error is given upon attempting to open a downloaded file.