Create an item type that returns the ownership of a file.
A positional argument should be used to select user or group ownership and numerical (id) or textual output (name). Id and user should be the defaults.

e.g. :
vfs.file.owner['/tmp/test.txt'] => 1001
vfs.file.owner['/tmp/test.txt',user,id] => 1001
vfs.file.owner['/tmp/test.txt',,id] => 1001
vfs.file.owner['/tmp/test.txt',user,name] => zabbix
vfs.file.owner['/tmp/test.txt',,name] => zabbix

vfs.file.owner['/tmp/test.txt',group] => 100
vfs.file.owner['/tmp/test.txt',group,id => 100
vfs.file.owner['/tmp/test.txt',group,name] => users

In case the file doesn't exist or something else goes wrong reading the file ownership, return ZBX_NOTSUPPORTED.