определить тип файла (determine file type)
LEGAL NOTICE
Copyright (c) Ian F. Darwin, Toronto, Canada, 1986-1999. Covered
by the standard Berkeley Software Distribution copyright; see the
file COPYING in the source distribution.
The files tar.h and is_tar.c were written by John Gilmore from his
public-domain tar(1) program, and are not covered by the above
license.
