#!/bin/sh
#
# Copyright (C) 2014  Codethink Limited
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; version 2 of the License.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
#
# This is a "morph deploy" configuration extension to configure a system
# to use busybox for its init, if INIT_SYSTEM=busybox is specified.
#
# As well as checking INIT_SYSTEM, the following variables are used.
#
# Getty configuration:
#   * CONSOLE_DEVICE:   Which device to spawn a getty on (default: ttyS0)
#   * CONSOLE_BAUDRATE: Baud rate of the console (default: 115200)
#   * CONSOLE_MODE:     What kind of terminal this console emulates
#                       (default: vt100)

if [ "$INIT_SYSTEM" != busybox ]; then
    echo Not configuring system to use busybox init.
    exit 0
fi

set -e
echo Configuring system to use busybox init

RUN_SCRIPT=/etc/rcS
INIT_SCRIPT=/sbin/init

install_mdev_config(){
    install -D -m644 /dev/stdin "$1" <<'EOF'
# support module loading on hotplug
$MODALIAS=.*    root:root 660 @modprobe "$MODALIAS"

# null may already exist; therefore ownership has to be changed with command
null            root:root 666 @chmod 666 $MDEV
zero            root:root 666
full            root:root 666
random          root:root 444
urandom         root:root 444
hwrandom        root:root 444
grsec           root:root 660

kmem            root:root 640
mem             root:root 640
port            root:root 640
# console may already exist; therefore ownership has to be changed with command
console         root:root 600 @chmod 600 $MDEV
ptmx            root:root 666
pty.*           root:root 660

# Typical devices

tty             root:root 666
tty[0-9]*       root:root 660
vcsa*[0-9]*     root:root 660
ttyS[0-9]*      root:root 660

# block devices
ram[0-9]*       root:root 660
loop[0-9]+      root:root 660
sd[a-z].*       root:root 660
hd[a-z][0-9]*   root:root 660
md[0-9]*        root:root 660
sr[0-9]*        root:root 660 @ln -sf $MDEV cdrom
fd[0-9]*        root:root 660

# net devices
SUBSYSTEM=net;.* root:root 600 @nameif
tun[0-9]*       root:root 600 =net/
tap[0-9]*       root:root 600 =net/
EOF
}

install_start_script(){
    install -D -m755 /dev/stdin "$1" <<'EOF'
#!/bin/sh
mount -t devtmpfs devtmpfs /dev
mount -t proc proc /proc
mount -t sysfs sysfs /sys
mkdir -p /dev/pts
mount -t devpts devpts /dev/pts

echo /sbin/mdev >/proc/sys/kernel/hotplug
mdev -s

hostname -F /etc/hostname

run-parts -a start /etc/init.d
EOF
}

install_inittab(){
    local inittab="$1"
    local dev="$2"
    local baud="$3"
    local mode="$4"
    install -D -m644 /dev/stdin "$1" <<EOF
::sysinit:$RUN_SCRIPT

::askfirst:-/bin/cttyhack /bin/sh
::askfirst:/sbin/getty -L $dev $baud $mode

::ctrlaltdel:/sbin/reboot
::shutdown:/sbin/swapoff -a
::shutdown:/bin/umount -a -r
::restart:/sbin/init
EOF
}

install_init_symlink(){
    local initdir="$(dirname "$1")"
    local initname="$(basename "$1")"
    mkdir -p "$initdir"
    cd "$initdir"
    for busybox_dir in . ../bin ../sbin ../usr/bin ../usr/sbin; do
        local busybox="$busybox_dir/busybox"
        if [ ! -x "$busybox" ]; then
            continue
        fi
        ln -sf "$busybox" "$initname"
        return 0
    done
    echo Unable to find busybox >&2
    exit 1
}

install_mdev_config "$1/etc/mdev.conf"

install_start_script "$1$RUN_SCRIPT"

install_inittab "$1/etc/inittab" "${CONSOLE_DEV-ttyS0}" \
    "${CONSOLE_BAUD-115200}" "${CONSOLE_MODE-vt100}"

install_init_symlink "$1$INIT_SCRIPT"