#!/bin/bash

# Update an existing system to use a read only sysroot

# and https://bugzilla.redhat.com/show_bug.cgi?id=2060976

set -euo pipefail

main() {

    # Used to condition execution of this unit at the systemd level

    local -r stamp_file="/var/lib/.ostree-readonly-sysroot"

    if [[ -f "${stamp_file}" ]]; then

        exit 0

    fi

    local -r ostree_sysroot_readonly="$(ostree config --repo=/sysroot/ostree/repo get "sysroot.readonly" &> /dev/null || echo "false")"

    if [[ "${ostree_sysroot_readonly}" == "true" ]]; then

        # Nothing to do

        touch "${stamp_file}"

        exit 0

    fi

    local -r boot_entries="$(ls -A /boot/loader/entries/ | wc -l)"

    # Ensure that we can read BLS entries to avoid touching systems where /boot

    # is not mounted

    if [[ "${boot_entries}" -eq 0 ]]; then

        echo "No BLS entry found: Maybe /boot is not mounted?" 1>&2

        echo "This is unexpected thus no migration will be performed" 1>&2

        touch "${stamp_file}"

        exit 0

    fi

    # Check if any existing deployment is still missing the rw karg

    local rw_kargs_found=0

    local count=0

    for f in "/boot/loader/entries/"*; do

        count="$(grep -c "^options .* rw" "${f}" || true)"

        if [[ "${count}" -ge 1 ]]; then

            rw_kargs_found=$((rw_kargs_found + 1))

        fi

    done

    # Some deployments are still missing the rw karg. Let's try to update them

    if [[ "${boot_entries}" -ne "${rw_kargs_found}" ]]; then

        ostree admin kargs edit-in-place --append-if-missing=rw || \

            echo "Failed to edit kargs in place with ostree" 1>&2

    fi

    # Re-check if any existing deployment is still missing the rw karg

    rw_kargs_found=0

    count=0

    for f in "/boot/loader/entries/"*; do

        count="$(grep -c "^options .* rw" "${f}" || true)"

        if [[ "${count}" -ge 1 ]]; then

            rw_kargs_found=$((rw_kargs_found + 1))

        fi

    done

    unset count

    # If all deployments are good, then we can set the sysroot.readonly option

    # in the ostree repo config

    if [[ "${boot_entries}" -eq "${rw_kargs_found}" ]]; then

        echo "Setting up the sysroot.readonly option in the ostree repo config"

        ostree config --repo=/sysroot/ostree/repo set "sysroot.readonly" "true"

        touch "${stamp_file}"

        exit 0

    fi

    # If anything else before failed, we will retry on next boot

    echo "Will retry next boot" 1>&2

    exit 0

}

main "${@}"