#!/bin/sh
# Copyright 2011 CyberLeo, All Rights Reserved
# http://wiki.cyberleo.net/wiki/CyberLeo/COPYRIGHT

meh() { printf " \033[1;32m*\033[0m %s%s\n" "${jail:+${jail}: }" "${*}"; }
omg() { printf " \033[1;33m*\033[0m %s%s\n" "${jail:+${jail}: }" "${*}"; }
wtf() { printf " \033[1;31m*\033[0m %s%s\n" "${jail:+${jail}: }" "${*}"; exit 1; }
pebkac() {
  [ "${*}" ] && printf "%s\n\n" "${*}"
  cat <<EOF
Usage: <start|enter|stop> <jailname>
EOF
  exit 1
}

cmd="$(basename "${0}")"
base="${J_BASE:-$(realpath "$(dirname "${0}")/../")}"
jail="${J_NAME:-$(basename "${1:-DebianChroot}")}" #"
jdir="${base}/${jail}"
jail_shell=""

# Propagate certain environment variables; sterilize the rest of the environment
jail_env="
  TERM=${TERM}
  USER=${USER}
"

# Create a new jail (Will not work, since a new jail will not exist and will not pass the 'not a jail' check above)
jail_new() {
  DEBOOTSTRAP_DIR="$(base)/debootstrap" "${DEBOOTSTRAP_DIR}/debootstrap" --arch=amd64 squeeze "${jdir}"
}

# Figure out jail parameters
jail_params() {
  # Where is the shell?
  for shell in /bin/bash /usr/bin/bash /usr/local/bin/bash /bin/sh
  do
    if [ -f "${jdir}/${shell}" ]
    then
      jail_shell=${shell}
      break
    fi
    wtf "cannot locate usable shell; is this a real jail?"
  done
}

# Jail is 'up' if /dev/pts and /proc are mounted
jail_up() {
  grep -q "^devpts ${jdir}/dev/pts devpts" /proc/mounts || return 1
  grep -q "^proc ${jdir}/proc proc" /proc/mounts || return 1
  return 0
}

jail_status() {
  jail_up && meh "$(printf '\033[1;32mup\033[0m')" || meh "$(printf '\033[1;31mdown\033[0m')"
}

# Mount /dev/pts and /proc in the jail
jail_start() {
  jail_up && return 0
  meh "starting ${jail} ..."
  mount -t devpts devpts "${jdir}/dev/pts"
  mount -t proc proc "${jdir}/proc"
}

# Enter jail
jail_enter() {
  jail_up || wtf "jail not up"
  meh "entering ${jail} ..."
  env -i ${jail_env} /usr/bin/chroot "${jdir}" /bin/su "${USER}" -c "${jail_shell}" -l
}

# Unmount /dev/pts and /proc in the jail
jail_stop() {
  jail_up || return 0
  meh "stopping ${jail} ..."
  umount "${jdir}/proc"
  umount "${jdir}/dev/pts"
}

# Need root beyond here
[ "$(id -u)" -eq 0 ] || exec sudo env ${jail_env} "${0}" "${@}"

jail_params

case "${cmd}" in
status) jail_status ;;
start) jail_start ;;
enter) jail_enter ;;
stop)  jail_stop  ;;
*) pebkac ;;
esac