Re: support for translators in tar

[Neal H Walfield]

> When 'tar' saves a translator, it must also save the file or
> directory underlying the translator, in case the translator wants
> to access it when run.  The underlying node can be opened with
> O_NOTRANS.

Do not forget, translators maybe stacked.

>    API:  There is S_IPTRANS for mode_t, but I think that's a bit
>    late since a stat already uses the translator.  'showtrans'
>    gets a Mach port to the file with file_name_lookup, reads the
>    passive-translator argz with file_get_translator, and closes
>    the port with mach_port_deallocate.  'settrans' uses
>    file_set_translator in a similar way.

That right thing to do is to slurp in everything (mode, owner, group,
et al) from the underlying (i.e. the bottom) node as the active
translator will be able to recreate all of its live state.

>    Format:  If the bits are zero, I think they needn't be saved.

I disagree; they may be zero for a good reason.