qubes-installer-qubes-os/anaconda/dracut/fetch-updates-disk

#!/bin/bash
# fetch-updates-disk - fetch updates from a block device

command -v getarg >/dev/null || . /lib/dracut-lib.sh
command -v unpack_updates_img >/dev/null || . /lib/anaconda-lib.sh

dev="$1"
path="${2:-/updates.img}"

[ -d "$path" ] && path=$path/updates.img
[ -b "$dev" ] || exit 1

info "anaconda: fetching updates from $dev:$path"

mnt="$(find_mount $dev)"
if [ -n "$mnt" ]; then
    cp $mnt$path /tmp/updates.img
else
    tmpmnt="$(mkuniqdir /run/install tmpmnt)"
    if mount -o ro $dev $tmpmnt; then
        cp $tmpmnt$path /tmp/updates.img
        umount $tmpmnt
    fi
    rmdir $tmpmnt
fi

if [ -f /tmp/updates.img ]; then
    unpack_updates_img /tmp/updates.img /updates
    rm /tmp/updates.img
    echo "$dev:$path" >> /tmp/liveupdates.done
else
    warn "anaconda: failed to get updates from $dev:$path"
fi