recipes-google/emmc-image/emmc-image-setup/emmc-image-setup.sh

#!/bin/bash

GBMC_IMAGE=@GBMC_IMAGE@

if [ "${GBMC_IMAGE}" == "true" ]; then
    echo "Getting activation half" >&2
    source /usr/lib/payload-lib.sh || exit 1
    payload_status || exit 1
else
    echo "vendor image, using fixed location"
    active_half=0
fi

MACHINE=@MACHINE@

img="emmc-image-${MACHINE}.squashfs-xz.verity"
emmcdir="/mnt/luks-mmcblk0_fs/emmc-image/${active_half}"
hashfile="/usr/share/emmc-image-verity/${img}.env"
mountdir="/run/emmc-image"
mutableconfdir=/var/lib/extensions.mutable

clear_mount_ref() {
    local mergetime=$(systemctl show emmc-image-setup | grep ExecMainStartTimestampMonotonic | cut -d'=' -f 2)
    local service
    for service in $(systemctl list-units | grep service | grep running | cut -d" " -f 3); do
      local starttime=$(systemctl show $service | grep ExecMainStartTimestampMonotonic | cut -d'=' -f 2)
      (( starttime > mergetime )) && systemctl restart "${service}"
    done
}

if [ $1 == "start" ]; then
    if [[ -f "/run/emmc-image-runtime/VERSION" ]]; then
        echo "already have a running eMMC image, probably in netboot" >&2
        exit 0
    fi

    if ! source "${hashfile}"; then
        echo "${emmcimg}: hash file not found" >&2
        exit 1
    fi

    if [[ ! -f "${emmcdir}/VERSION" ]]; then
        echo "${emmcimg}: VERSION file not found" >&2
        exit 1
    fi

    mkdir -p "${mountdir}/${img}"
    mkdir -p /run/extensions/
    mkdir -p /run/confexts/

    echo "Loading image ${emmcdir}/${img}" >&2
    veritysetup --data-block-size=$DATA_BLOCK_SIZE --hash=$HASH_ALGORITHM --hash-block-size=$HASH_BLOCK_SIZE --hash-offset=$DATA_SIZE open "${emmcdir}/${img}" "${img}" "${emmcdir}/${img}" $ROOT_HASH
    echo "Mounting image links for ${img}" >&2
    mount /dev/mapper/${img} "${mountdir}/${img}" || exit
    echo "Setting sysext links for ${img}" >&2
    rm -f /run/extensions/${img} && ln -s "${mountdir}/${img}" "/run/extensions/${img}"
    rm -f /run/confexts/${img} && ln -s "${mountdir}/${img}" "/run/confexts/${img}"
    echo "Finished setup runtime image ${img}" >&2
    # make the overlay mutable after merge
    mkdir -p ${mutableconfdir} && rm -f ${mutableconfdir}/*
    ln -s /run/initramfs/rw/cow/etc ${mutableconfdir}/etc
    ln -s /run/initramfs/rw/cow/usr ${mutableconfdir}/usr

    echo "Merging sysext ..." >&2
    systemd-sysext merge --force --mutable=auto || exit
    echo "Merging confext ..." >&2
    systemd-confext merge --force --mutable=auto --noexec=false || exit
    echo "Starting all services"
    systemctl daemon-reload
    systemctl start emmc-image.target
    cp ${emmcdir}/VERSION ${mountdir}/VERSION
    echo "Loaded emmc images" >&2

elif [ $1 == "stop" ]; then
    # In regular cases, eMMC image will stay alive until reboot/powercycle.
    # Clean up could happen in maintenance mode for emmc erase

    # skip process when reboot
    systemctl is-active -q reboot.target && exit 0
    # skip clean up if eMMC does not exist
    [[ -f "${emmcdir}/VERSION" ]] || exit 0
    echo "clearing emmc image configurations in best effort" >&2
    echo "This should be an operation only during maintenance" >&2
    rm -rf "${mountdir}/VERSION"
    # no need to unmerge and reload if no extension config at all.
    if [[ -d ${mutableconfdir} ]]; then
        systemctl stop emmc-image.target
        systemd-confext unmerge
        systemd-sysext unmerge
        systemctl daemon-reload
        rm -rf ${mutableconfdir}
        # services running after merge is possibly still using the mount.
        # stop them here
        clear_mount_ref
    fi
    rm -rf /run/extensions /run/confexts

    umount -l /dev/mapper/${img}
    rm -rf "${mountdir}/${img}"
    # deferred close, it won't close until this clean up process quit itself.
    veritysetup close --deferred "${img}"
    # waiting for periodic oneshot process to clean up, most of the process can finish within 60s.
    sleep 120
fi