Mender update module, install-system-update

#!/bin/bash

STATE="$1"
FILES="$2"

switch_bootpart () {
    export $(fw_printenv bootpart)
    if [ $bootpart = 1 ]; then
        fw_setenv bootpart 2
    else
        fw_setenv bootpart 1
    fi
    export $(fw_printenv bootpart)
}

case "$STATE" in
    ArtifactInstall)
        # This variable will trigger bootcount to increment
        fw_setenv upgrade_available 1
        switch_bootpart
        rootfs_img="$(realpath $FILES/files/*.ext4)"
        target_partition="/dev/$(lsblk | awk 'NR==2 {print $1}')p$bootpart"
        # Write, check and resize the newly flashed partition
        ddrescue $rootfs_img $target_partition --force 1> /dev/null
        e2fsck $target_partition -f -y > /dev/null 2>&1
        resize2fs $target_partition 2> /dev/null
        reboot
        ;;
    ArtifactCommit)
        # If altbootcmd was triggred, upgrade_failed will be
        # set in U-Boot. Otherwise was able to boot into new
        # partition and commit update
        export $(fw_printenv upgrade_failed)
        if [ $upgrade_failed = 0 ]; then
            fw_setenv upgrade_available 0
            fw_setenv bootcount 0
            exit 0
        else
            exit 1
        fi
        ;;
    ArtifactFailure)
        # Failure means the updated partition could not start
        # and altbootcmd was triggered in U-Boot which switched the partion
        # back
        export $(fw_printenv upgrade_failed)
        if [ $upgrade_failed = 1 ]; then
            fw_setenv upgrade_available 0
            fw_setenv upgrade_failed 0
            fw_setenv bootcount 0
            exit 1
        fi
        ;;
esac
exit 0