перемещаться по файловой иерархии (traverse a file hierarchy)
Ошибки (Error)
The function fts_open() may fail and set errno for any of the
errors specified for open(2) and malloc(3).
The function fts_close() may fail and set errno for any of the
errors specified for chdir(2) and close(2).
The functions fts_read() and fts_children() may fail and set
errno for any of the errors specified for chdir(2), malloc(3),
opendir(3), readdir(3), and stat(2).
In addition, fts_children(), fts_open(), and fts_set() may fail
and set errno as follows:
EINVAL options or instr was invalid.
