[comp.unix.wizards] How about a virtual file system ?

joefritz@aix01.aix.rpi.edu (Jochen M. Fritz) (06/28/91)

All this business of file attributes and ACL could be handled in a slightly
different manner--a Virtual File System (VFS).  Each file in this FS would
contain two links--one for the data, and another a driver program that can 
the file.  The driver program is the only way that the data can be gotten 
at (except a possible failsafe).  An open operation would cause the kernal
to run the driver task (as the file owner).  The driver would then set 
any number of pipes (or sockets) and inform the kernal.  If no pipe at
all is set up, this is a denied permission,  the read(2) or write(2) system
calls read or write the first pipe, and either another call or a varient
of read and write would read the other pipes (which could contain other
data including attributes if that was provided by the driver.

Aside from allowing the user to maintain his own ACL, this would anyone
(not just root) to add any data that is available in any manner (ie floppy,
FTP, etc) into the file system, thus making mounts obsolete, and special
device drivers unnecessary.

This does require some major changes to the system, but the result would
be an object-oriented OS with files as objects.  This archetcture may
well be the next generation of operating systems.

-- 
Jochen Fritz          | There's no way i can say the words more clearly
joefritz@rpi.edu      | There's no one left to point at anymore   
noah (peace monger)   | Just you and i and we must make the Choice now.
   <><                | And not destroy the life we're living for. (P. Yarrow)

sef@kithrup.COM (Sean Eric Fagan) (06/29/91)

In article <7fhlg4h@rpi.edu> joefritz@aix01.aix.rpi.edu (Jochen M. Fritz) writes:
>Each file in this FS would
>contain two links--one for the data, and another a driver program that can 
>the file.

It's been done before, as I've mentioned earlier in this thread.  Watchdogs.
When the FSF comes out with the GNU OS, watchdogs (or their moral
equivalent) should be relatively easy to add (they've got the trappings in
the filesystem already).

-- 
Sean Eric Fagan  | "What *does* that 33 do?  I have no idea."
sef@kithrup.COM  |           -- Chris Torek
-----------------+              (torek@ee.lbl.gov)
Any opinions expressed are my own, and generally unpopular with others.

lm@slovax.Eng.Sun.COM (Larry McVoy) (06/30/91)

> All this business of file attributes and ACL could be handled in a slightly
> different manner--a Virtual File System (VFS).  

Sort of.  SunOS, at least, has a VFS layer (UFS, RFS, TMPFS, NFS, etc,
are all abide by the VFS interface).  Unfortunately, there is no
interface in the (current) VFS that allows for extended attributes.  As
far as I can tell, this thread has been wandering around mindlessly.
Add an interface that lets you add <name, value> attributes to a file
and another which allows you to query (might want a "*" name to give
back a list) and be done with it.  All the normal Unix commands will
ignore this gunk, they'll never know it is there (the exceptions are
things that try to be file systems, like tar, cpio, shar, etc).
Stuff that wants to know, can.  What's the big deal?  As far as I can
tell, the only interesting part is how you migrate the attributes around.
---
Larry McVoy		(415) 821-5758			 lm@sunburn.stanford.edu

erik@srava.sra.co.jp (Erik M. van der Poel) (06/30/91)

Larry McVoy writes:
> Stuff that wants to know, can.  What's the big deal?

Finally, someone who understands what I'm getting at.
-
-- 
EvdP