smbd: Return OBJECT_NAME_NOT_FOUND if lcomp points outside the share

smbd: Return OBJECT_NAME_NOT_FOUND if lcomp points outside the share

filename_convert_dirfsp() is the only caller of
safe_symlink_target_path(). Right now this is not called with
"unparsed==0" because the last component is handled in
openat_pathref_fsp() and thus non_widelink_open(). I have code that
will change this, so that we can simplify
openat_pathref_fsp_case_insensitive() to directly call OPENAT, not
going through non_widelink_open. This will cause
safe_symlink_target_path() also be called for the last component,
which means it needs logic to distinguish between PATH_ and
NAME_NOT_FOUND.

Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>