hook_field() "validate" op executed on "Save field settings"

hook_field() "validate" op executed on "Save field settings"
And $node is an array (not an object) and contains following:

Array ( [field_torrent_file] => Array ( [0] => Array ( [fid] => 0 [list] => 1 [data] => Array ( [description] => ) [filepath] => [filename] => [filemime] => [filesize] => 0 [filefield_upload] => Upload [filefield_remove] => Remove [upload] => ) ) )

P.S. Maybe this issue is related to FileField module...