tinyramfs/init

#!/sbin/busybox sh
#
# tiny init script

panic() {
    printf "panic >> %s\n" "$1"
    sh -l
}

# parse_cmdline() {
# TODO parse /proc/cmdline
#}

mnt_pseudofs() {
    mount -t proc none /proc
    mount -t sysfs none /sys
    mount -t devtmpfs none /dev
    mount -t tmpfs none /tmp
}

setup_mdev() {
    # setup hotplugger
    if [ -e /proc/sys/kernel/hotplug ]; then
        printf /sbin/mdev > /proc/sys/kernel/hotplug
    else
        uevent mdev &
    fi

    # trigger mdev
    mdev -s

    # trigger uevent for usb devices
    for device in /sys/bus/usb/devices/*; do
        case ${device##*/} in
            [0-9]*-[0-9]*)
                printf add > "${device}/uevent"
                ;;
        esac
    done

    # load drivers
    find /sys -name modalias -type f -exec sort -u "{}" "+" | xargs modprobe -qba
}

setup_mdevd() {
    # setup daemon
    mdevd &
    # trigger uevents
    mdevd-coldplug
}

setup_udev() {
    udevd --daemon
    udevadm trigger --action=add --type=subsystems
    udevadm trigger --action=add --type=devices
    udevadm settle
}

findfs_sh() {
    case "${1%%=*}" in
        LABEL)    device="/dev/disk/by-label/${1##*=}" ;;
        UUID)     device="/dev/disk/by-uuid/${1##*=}" ;;
        PARTUUID) device="/dev/disk/by-partuuid/${1##*=}" ;;
        /dev/*)   device="$1" ;;
        *)        panic "findfs option broken" ;;
    esac

    # avoid race condition
    while [ ! -e "$device" ]; do
        sleep 0.5
        [ "$increment" ] || increment=0
        increment=$(( increment + 1 ))
        [ "$increment" = 10 ] && panic "failed to lookup rootfs"
    done

    printf "%s\n" "$device"
}

unlock_luks() {
    cryptsetup $luks_args luksOpen $(findfs_sh "$luks_root") ${luks_name:-luks_root} || panic "failed to unlock luks container"
}

trigger_lvm() {
    lvm vgchange --quiet --sysinit -a y > /dev/null
}

mnt_rootfs() {
    mount ${root_type:+-t $root_type} ${root_args:+-o $root_args} $(findfs_sh "$root") /mnt/root || panic "failed to mount rootfs"
}

cleanup() {
    case "$devmgr" in
        mdev)  { printf "" > /proc/sys/kernel/hotplug || killall uevent; } > /dev/null 2>&1 ;;
        mdevd) killall mdevd ;;
        udev)  udevadm control --exit ;;
    esac

    # unmount pseudofs's
    umount /dev /sys /proc /tmp
}

boot_system() {
    exec switch_root /mnt/root /sbin/init || panic "failed to boot system"
}

/sbin/busybox --install -s

. /config || panic "failed to source config"

# debug shell commands
[ "$debug" = 1 ] && set -x

#parse_cmdline
mnt_pseudofs

case "$devmgr" in
    mdev)  setup_mdev ;;
    mdevd) setup_mdevd ;;
    udev)  setup_udev ;;
    *)     panic "devmgr option broken" ;;
esac

# TODO handle situations when LUKS on LVM
[ "$luks" = 1 ] && unlock_luks
[ "$lvm" = 1 ] && trigger_lvm
mnt_rootfs
cleanup
boot_system