gmc/libvfs suggestion for removable media

[Daniel Burrows <Daniel_Burrows brown edu>]

  I apologize if this is already in gmc or done (done _better_ that is) in
some other program or a feature of Linux that I missed somehow. :-)
  Also, my understanding of libvfs is incomplete, this may be an incorrect
use of it.  But the problem is still there and I think that a solution
that at least works for Gnome apps would be in order.

  It occurs to me that Linux's handling of removable media, while certainly
good technically, leaves a lot to be desired in terms of usability.  It's
not just that users have to explicitly mount floppies, somewhat more
annoying is the fact that they have to umount them before doing anything
else with the drive.  To an extent, adding sync to the mount options in fstab
helps, but I think that there may be better solutions.  Here's what I was
thinking (this is almost certainly not a 1.0 option and I readily admit that
I probably wouldn't be able to implement this, it's just a proposal of a
feature.  Of course, if I get some time to learn how to implement it.. ):

  Add a "removable" VFS type in libvfs.  This type would be used for devices
which could be removed and vanish at any moment (like floppies).  Data would 
be synced to the disk when written and sudden removal would be handled fairly
nicely (eg pop up a warning dialog and maybe let the user reinsert the disk and
continue--the last might be difficult depending on how it's implemented)

  The two implementations I can think of are either 'automounting'--mount the
media when it's accessed, do stuff, and umount it--or 'raw'--directly access
the device. (like mtools).  Probably automounting is the best solution for
now; in addition to being simpler to implement, it can be done by normal users
if root adds "user" to the options in the fstab. (also we can get synchronous
data transfer with the 'sync' option but I don't think I'd rely on that..it
also doesn't solve the problem of the user removing a mounted disk)

  This'll work for moving stuff around in gmc; I think some trickery may
be involved in actually accessing files for programs.  I don't know enough
about libvfs :-( but I believe that it must redirect read(), write(), seek(),
etc requests in order to work?  Probably the best way to do it then would
be to wrap all requests with mount/umount calls, and prompting the user (using
callbacks so console apps can prompt in the console and Gnome apps pop up
a dialog box) when the disk isn't available.

  Another useful thing might be to somehow ID disks somehow (serial number? Can
a non-privileged process get that?) to detect 'disk switches' and even allow
two separate removable VFSs to be open at once (for example, I open a VFS
on one floppy and another on another floppy, then copy a file from one floppy
to the other..the VFS asks me to insert each floppy at the appropriate time).

  Of course, it's possible that no-one uses floppies anymore and this is
a useless suggestion. :-)

-- 
"It is hard to think of anything less sentient than a pumpkin."
  -- Terry Pratchett, "Witches Abroad"