#!/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 "${@}"