when you upload the file, $_FILES['file']['name'] contains its original name converted into server's default charset.
if a name contain characters that aren't present in default charset, the conversion fails and the $_FILES['file']['name'] remains in original charset.
i've got this behavior when uploading from a windows-1251 environment into koi8-r. if a filename has the number sign "?" (0xb9), it DOES NOT GET CONVERTED as soon as there is no such character in koi8-r.
Workaround i use:
<?php
if (strstr ($_FILES['file']['name'], chr(0xb9)) != "")
{
$_FILES['file']['name'] = iconv (
"windows-1251",
"koi8-r",
str_replace (chr(0xb9), "N.", $_FILES['file']['name']));
};
?>