#!/bin/bash -e

kver=$(uname -r)
while read -r line; do
    # We only care about the running kernel
    if [[ "$line" == "usr/lib/modules/$kver/vmlinuz" ]];then
        if mountpoint --nofollow --quiet /${line%vmlinuz};then
            # Mount point is already present
            # This means we already ran that hook during 'remove case'
            #
            # Remove the mount so we can reinstall the kernel
            # Most of the time udevd would block the umount, so suppress the first error message
            umount /${line%vmlinuz} 2>/dev/null || umount --lazy /${line%vmlinuz}
            rmdir /${line%vmlinuz}
        elif [[ -f "$line" && ! -d "/usr/lib/modules/running-kernel/" ]];then
            # Kernel install is present and we do not have a copy
            #
            # This is the removal case, so we save the kernel
            mkdir /usr/lib/modules/running-kernel
            cp --archive --link --no-target-directory /usr/lib/modules/${kver}/ \
                /usr/lib/modules/running-kernel/
        fi
        # If we are re-removing the running kernel, (after removing + reinstalling),
        # we already have a backup and this hook is a no-op
    fi
done