#!/bin/sh
# SPDX-Version: 3.0
# SPDX-CreationInfo: 2025-06-17; WEIDNER, Marc S.; <msw@coresecret.dev>
# SPDX-ExternalRef: GIT https://git.coresecret.dev/msw/CISS.debian.installer.git
# SPDX-FileContributor: WEIDNER, Marc S.; Centurion Intelligence Consulting Agency
# SPDX-FileCopyrightText: 2024-2025; WEIDNER, Marc S.; <msw@coresecret.dev>
# SPDX-FileType: SOURCE
# SPDX-License-Identifier: EUPL-1.2 OR LicenseRef-CCLA-1.0
# SPDX-LicenseComment: This file is part of the CISS.debian.installer.secure framework.
# SPDX-PackageName: CISS.debian.installer
# SPDX-Security-Contact: security@coresecret.eu
# SPDX-Comment: Enforce merged-/usr symlinks inside the initramfs image.

set -e

PREREQ=""
prereqs() { echo "${PREREQ}"; }
case "${1}" in
  prereqs) prereqs; exit 0 ;;
esac

. /usr/share/initramfs-tools/hook-functions

### Ensure target directories exist in the future initramfs root.
mkdir -p "${DESTDIR}/usr/bin" "${DESTDIR}/usr/sbin" "${DESTDIR}/usr/lib"

### /lib64 may or may not exist depending on arch; create if present on the host system.
# shellcheck disable=2292
[ -d "${DESTDIR}/usr/lib64" ] || mkdir -p "${DESTDIR}/usr/lib64" 2>/dev/null || true

# shellcheck disable=2292
move_dir_into_usr() {
  ### $1: top-level name (bin|sbin|lib|lib64)
  ### Moves all contents of /$1 into /usr/$1 and removes /$1 if it was a directory.
  ### Then creates a symlink /$1 -> usr/$1
  d="$1"
  top="${DESTDIR}/${d}"
  usr="${DESTDIR}/usr/${d}"

  if [ -L "${top}" ]; then
    ### Already a symlink, so nothing to do.
    return 0
  fi

  if [ -d "${top}" ]; then
    ### Copy including dotfiles; -a preserves perms/links if available (coreutils on build host).
    ### If 'cp -a' is unavailable, fallback to 'cp -rp'.
    if cp -a "${top}/." "${usr}/" 2>/dev/null; then
      :
    else
      cp -rp "${top}/." "${usr}/"
    fi
    ### Remove the original directory tree, then replace with symlink
    rm -rf "${top}"
  fi

  ### Create (or refresh) the canonical symlink
  ln -sfn "usr/${d}" "${top}"

  return 0
}

move_dir_into_usr bin
move_dir_into_usr sbin
move_dir_into_usr lib
### /lib64 exists only on some arch images; harmless if empty
# shellcheck disable=2292
[ -d "${DESTDIR}/usr/lib64" ] && move_dir_into_usr lib64

printf "\e[92mSuccessfully executed: [/etc/initramfs-tools/hooks/9999-custom-usrmerge.sh] \n\e[0m"

# vim: number et ts=2 sw=2 sts=2 ai tw=128 ft=sh