Solution:
There are two action hooks when you hook into wp_ajax
.
wp_ajax_{$action}
for for logged-in users. Docs
and
wp_ajax_nopriv_{$action}
for logged-out users. Docs
So to combine the two, you could use the following code:
add_action( 'wp_ajax_get_content_wino' , 'get_content_wino' );
add_action( 'wp_ajax_nopriv_get_content_wino' , 'get_content_wino' );
function get_content_wino()
{
if ( isset($_REQUEST) )
{
echo read_file();
die();
}
}