mkmm.sh

#!/usr/bin/env bash

# Moviuro's Kernel Modules Manager
# A successor to https://github.com/saber-nyan/kernel-modules-hook
# Released under the UNLICENSE

_myname="mkmm"

__usage(){
  cat << EOH
mkmm [-vf] save|restore|clean|bleach [kver]

mkmm is Moviuro's Kernel Module Manager intended to be used in an
alpm-hook(5) to save and restore the running kernel's modules because pacman(8)
will remove them during an upgrade

-v : verbose (bash set -x)
-f : force (see below)

save       : use cp(1) to hardlink the kernel modules in a backup directory
             (--archive --link)
-f save    : use cp --force
restore    : use cp(1) to hardlink the backed-up kernel modules back in place
-f restore : use cp --force
clean      : rm(1) the backup directory
-f clean   : use rm --force
bleach     : rm(1) -rf modules' directories that don't belong to a pacman(8)
             package, except for the currently running kernel
-f bleach  : rm(1) -rf modules' directories that don't belong to a pacman(8)
             package

kver : an optional argument to specify which kernel modules to save;
       defaults to the current running kernel (uname(1) -r)

SEE ALSO

https://bugs.archlinux.org/task/16702
https://github.com/saber-nyan/kernel-modules-hook
EOH
}

# __save kver [force]
__save() {
  : "${1?Missing kver}"
  [[ -n "$2" ]] && _force="--force"

  mkdir -p "/usr/lib/modules/$_myname"
  cp --archive --link $_force -- \
   "/usr/lib/modules/$1" "/usr/lib/modules/$_myname"
  exit $?
}

# __restore kver [force]
__restore() {
  : "${1?Missing kver}"
  [[ -n "$2" ]] && _force="--force"

  cp --archive --link $_force -- \
   "/usr/lib/modules/$_myname" "/usr/lib/modules/$1"
  exit $?
}

# __clean [force]
__clean() {
  [[ -n "$1" ]] && _force="--force"

  rm --recursive $_force -- "/usr/lib/modules/$_myname"
  exit $?
}

# __bleach [force]
__bleach() {
  [[ -n "$1" ]] && _force="--force"
  _ret=0

  while IFS='' read -r _moddir; do
    if ! pacman -Qqo "$_moddir" >/dev/null 2>&1; then
      if [[ "$_moddir" != "/usr/lib/modules/$(uname -r)" ]] ||
         [[ -n "$_force" ]]; then
        rm --recursive --force -- "$_moddir"
        ((_ret+=$?))
      fi
    fi
  done < <(find /usr/lib/modules -mindepth 1 -maxdepth 1 -type d)
  exit "$_ret"
}

_force=""
while getopts ":vfh" _opt; do
  case "$_opt" in
    h) __usage ; exit 0     ;;
    f) _force=1             ;;
    v) set -x               ;;
    *) __usage >&2 ; exit 1 ;;
  esac
done

shift "$((OPTIND - 1))"
_kver="${2:-"$(uname -r)"}"

case "$1" in
  save) __save "$_kver" "$_force" ;;
  restore) __restore "$_kver" "$_force" ;;
  clean) __clean "$_force" ;;
  bleach) __bleach "$_force" ;;
  *) __usage >&2 ; exit 1 ;;
esac