#!/bin/sh

ROOTFS=/tmp/jail

# ensure that the TC initrd file is available
mount | grep -qF '/dev/hdc' || mount /dev/hdc
[ -f /mnt/hdc/boot/tinycore.gz ] || ! echo "can not find initrd file" || exit 1

# remove all traces of a previous run
MOUNTS=$(mount | grep -F " on ${ROOTFS}/" | sed -e 's#.* on ##' -e 's# .*##')
[ -z "$MOUNTS" ] || echo "$MOUNTS" | xargs -n 1 umount \
    || ! echo "umount failed" || exit 3
sudo rm -rf $ROOTFS 2> /dev/null || ! echo "rm $ROOTFS failed" || exit 4

# prepare the "jail" (step 1): extract initrd
mkdir -p $ROOTFS
cd $ROOTFS
zcat /mnt/hdc/boot/tinycore.gz | sudo cpio -idum > /dev/null

# prepare the "jail" (step 2): execute a subset of /etc/init.d/tc-config + more
for D in usr/local/tce.icons usr/local/tce.installed usr/local/tce.menu \
        tmp/tce tmp/tcloop ; do
    [ -d "$D" ] || sudo mkdir "$D"
    sudo chgrp staff "$D"
    sudo chmod g+w "$D"
done
echo '/tmp/tce' > opt/.tce_dir
#   ensure the presence of ~/.Xauthority
[ -f $HOME/.Xauthority ] && cp -p $HOME/.Xauthority ${HOME#/}

# prepare the "jail" (step 3): mount the required file systems
sudo mount -o bind /proc $ROOTFS/proc
sudo mount -o bind /dev/pts $ROOTFS/dev/pts
sudo mount -o bind /tmp $ROOTFS/tmp

echo "you should now be able to execute:   sudo chroot $ROOTFS su $USER"