[fitsbits] Start of "Foreign File Encapsulation" Public Comment Period

[Rob Seaman]

Hi  Pete,

> Why would a file be executable? In the tradition of the omni- 
> platform transportability of FITS files, it is unlikely that a file  
> would be really executable.

Just to provide some context, foreign file encapsulation was created  
as part of a prior NOAO archive project several years ago to  
encapsulate various non-FITS metadata products generated on Kitt Peak  
– observing logs, weather pictures, etc.  NOAO is using it again to  
transport PNG files from the Mosaic camera pipeline to the next  
generation NSA archive.  It was designed to be very general purpose,  
hence the authors' interest in reminding the community of its  
existence.  You can certainly create file collections that a third  
party would be foolish to unpack on their own system.  The same is  
true of tar.  In any event, if the fgread program isn't setuid, such  
files would only be executable as the UID of user, containing any risk.

Nelson Zárate will have an ADASS poster, and perhaps we can expect  
foreign encapsulation and the general topic of FITS extension types  
to enliven the FITS BoF.

> If the executable was intended to go onto a machine of the same  
> architecture (and libc....) then why use FITS?

We've long since moved past the point of regarding FITS as a pure  
transport format.  It's used in all our archives, for one thing.  One  
might well want to package up processing scripts with the data they  
were applied to, for instance.

> An example of an executable file, however, would be a virus.
> Surely we don't want to go there?

One person's virus is another's intelligent agent.  I suspect that a  
lot of us have entertained the notion of an IRAF or IDL virus in the  
past.  Why not FITS?  VO will certainly have its hands full with XML  
and web services, many of whose features are intended to be very  
"intelligent" indeed.

I suspect that foreign encapsulation is a sufficiently narrow niche  
market that we need not fret too much.

Rob