does not belong to, in these two ways:
1. If a group mapping doesn't exist for a group name, do not preserve
it for a non-root receiver. This is especially evident with the
sender is a daemon using chroot because then no mappings are
available.
2. Before setting the group on a file make sure that it is in the list
of groups returned by getgroups(). The same thing is done by chgrp
on systems that support bsd-style chown/chgrp, and this enforces
that it happens the same way on all systems. Overhead is very
little, especially since most systems don't allow more then 16
groups per user.
in 3 ways:
1) the realloc is done on a list of pointers, not a list of structures
2) only the basename of the file is now kept in the file struct an a
util function f_name() is now used to access the full name when
required.
3) pointers to directory names are re-used
hopefully I haven't broken anything. This will need lots of testing.
