Alter the URL to a file.
This hook is called from file_create_url(), and is called fairly frequently (10+ times per page), depending on how many files there are in a given page. If CSS and JS aggregation are disabled, this can become very frequently (50+ times per page) so performance is critical.
This function should alter the URI, if it wants to rewrite the file URL.
$uri: The URI to a file for which we need an external URL, or the path to a shipped file.
Note: this list is generated by pattern matching, so it may include some functions that are not actually implementations of this hook.
function hook_file_url_alter(&$uri) {
global $user;
// User 1 will always see the local file in this example.
if ($user->uid == 1) {
return;
}
$cdn1 = 'http://cdn1.example.com';
$cdn2 = 'http://cdn2.example.com';
$cdn_extensions = array(
'css',
'js',
'gif',
'jpg',
'jpeg',
'png',
);
// Most CDNs don't support private file transfers without a lot of hassle,
// so don't support this in the common case.
$schemes = array(
'public',
);
$scheme = file_uri_scheme($uri);
// Only serve shipped files and public created files from the CDN.
if (!$scheme || in_array($scheme, $schemes)) {
// Shipped files.
if (!$scheme) {
$path = $uri;
}
else {
$wrapper = file_stream_wrapper_get_instance_by_scheme($scheme);
$path = $wrapper
->getDirectoryPath() . '/' . file_uri_target($uri);
}
// Clean up Windows paths.
$path = str_replace('\\', '/', $path);
// Serve files with one of the CDN extensions from CDN 1, all others from
// CDN 2.
$pathinfo = pathinfo($path);
if (isset($pathinfo['extension']) && in_array($pathinfo['extension'], $cdn_extensions)) {
$uri = $cdn1 . '/' . $path;
}
else {
$uri = $cdn2 . '/' . $path;
}
}
}