Here are a few functions to help you when interacting with files:

Find the owner of a file:
An array of information about the owner is returned.

function foo_get_file_ownership($file){
	$stat = stat($file);
	if($stat){
		$group = posix_getgrgid($stat[5]);
		$user = posix_getpwuid($stat[4]);
		return compact('user', 'group');
	}
	else
		return false;
}

Get the four digit file permissions number:
A permissions string is returned. Example: 0755

function foo_get_file_perms($file){
	return substr(sprintf('%o', fileperms($file)), -4);
}

Convert permissions number to Read Write eXecute format:
Directory Example: 0755 converts to drwxr-xr-x
File Example: 0664 coverts to -rw-rw-r–

function foo_convert_perms_to_rwx($perms, $file){
	$rwx = array(
		'---',
		'--x',
		'-w-',
		'-wx',
		'r--',
		'r-x',
		'rw-',
		'rwx'
	);
	$type = is_dir($file) ? 'd' : '-';
	$owner = $perms[1];
	$group = $perms[2];
	$public = $perms[3];
	return $type.$rwx[$owner].$rwx[$group].$rwx[$public];
}