#!/bin/bash
# SPDX-Version: 3.0
# SPDX-CreationInfo: 2025-05-05; WEIDNER, Marc S.; <msw@coresecret.dev>
# SPDX-ExternalRef: GIT https://git.coresecret.dev/msw/CISS.debian.live.builder.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.live.builder
# SPDX-Security-Contact: security@coresecret.eu

#######################################
# Prevents the caller LIB-file from being sourced twice.
# Derive a safe guard-variable name from the caller script filename.
# Globals:
#   BASH_SOURCE
# Arguments:
#   1: Explicitly provided Argument: filename of the caller LIB. (Better let the guard_sourcing() determine dynamically.)
# Returns:
#   0: Returns '0' in both cases as they are intended to be successful.
#######################################
guard_sourcing() {
  ### Determine the caller script (the library being sourced).
  declare var_src="${1:-${BASH_SOURCE[1]}}"
  ### Strip path, keep only the filename
  declare var_file_name="${var_src##*/}"
  ### Sanitize to valid var name.
  declare var_safe_name="${var_file_name//[^a-zA-Z0-9_]/_}"
  ### Build guard-variable name.
  declare var_guard_var="_${var_safe_name}_LOADED"

  ### If already loaded, abort sourcing
  if [[ -n "${!var_guard_var:-}" ]]; then
    return 0
  fi

  ### Mark as loaded (readonly + exported)
  declare -grx "${var_guard_var}"=1

  return 0
}
### Prevents accidental 'unset -f'.
# shellcheck disable=SC2034
readonly -f guard_sourcing
# vim: number et ts=2 sw=2 sts=2 ai tw=128 ft=sh