In my installation (OSX 10.3.8, PHP 5.0.4, Moodle 1.4.4+), the file to patch is
/moodle/file.php
And the actual PHP code to replace readfile() is:
if (filesize($pathname) < 2000000) {
readfile($pathname);
} else {
$fp = fopen($pathname,"rb");
while (strlen($data = fread($fp,256*1024))) {
echo $data;
}
fclose($fp);
}
Actually, since I do not filter downloadable files, I needed to replace only the second readfile().