[ILUG] Hacking the BBC Hmmm.... Was Bootable Business Cards - CD-Rs are ordered

[Conor Daly]

Just been looking at the BBC image.  Doesn't look too hackable :-(

It consists of a 26Mb "Rusty's compressed ext2 filesystem" called
"singularity" and a few other bits and pieces.  The singularity consists of
a #!/bin/sh , a command and 26Mb of binary data.

When I booted it, There was only one init file I could find in /sbin.defunct
which runs the boot sequence.  I've inserted some relevant lines at the end
of this.

Anyone else wann burn the iso to a standard CD and have a look.  I'm not
experienced enough with this sort of thing to tell quite what we could do
with it.

##############
I'd be inclined to suggest we shouldn't burn a bunch of these immediately
but rather get a copy each to use as a learning tool for writing our own.
##############

On the up side, the image contains X (fvwm), wvdial, loads of networking,
ssh (AFAIK, telnet etc are linked to run in ssh by default) and a cute
little easter egg (do a "SVGATextMode" and then "egg" in a shell).

Couldn't get X to run properly at home.  Hacked the XF86Config to match my
local one and got X up but the windows all have transparent backgrounds and
don't refresh properly (It was late and I was supposed to be doing something
else!).

---
Conor Daly
-------------------------------------
General Forecast Division
Met Eireann
Glasnevin Hill
Dublin 9.

ph +353 1 8064255
fax +353 1 8064275

conor.daly at met.ie

Here's the bit that uncompresses the main filesystem

      # Normal LNX rescue system code

      echo "Found the LNX CD-ROM on $drive, mounting under /mnt/cdrom-real"
      umount /mnt/tmp
      mount -r -t iso9660 $drive /mnt/cdrom-real 2>/dev/null

      # cloop mount happens here!

      if [ -f /mnt/cdrom-real/singularity ]
      then
        echo "Found compressed ext2 filesystem in /mnt/cdrom-real, loading
cloop driver"
 cd /mnt/cdrom-real

 # uses Rusty's compressed loopback block device driver, cloop.c

 # This associates the decompressed contents of the file "singularity"
 # with the block device /dev/cloop (block device 240, 0 for now)

 # Heaven forbid we should do something so difficult as

 #      /mnt/cdrom-real/insmod /mnt/cdrom-real/cloop.o <
/mnt/cdrom-real/singularity
        #      mount -r -t ext2 /dev/cloop /mnt/cdrom

 # instead, we just _RUN_ the thing!

        echo "Mounting compressed blockdevice /dev/cloop under /mnt/cdrom"
 ./singularity /mnt/cdrom

      else
        echo "Uh-oh, can't find compressed ext2 filesystem!"
      fi

     # cloop mount done