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shtk_import bool
shtk_import list


# List of registered cleanup handlers (function names).
_Shtk_Cleanup_Handlers=


# List of exit traps that execute the cleanup handlers.
_Shtk_Cleanup_Traps="EXIT HUP INT TERM"


# Whether the exit traps have been installed or not.
_Shtk_Cleanup_Installed=false


# Executes all installed cleanup handlers.
_shtk_cleanup_run_handlers() {
    local signo="${1}"; shift
    local exitcode="${1}"; shift

    for handler in ${_Shtk_Cleanup_Handlers}; do
        eval "${handler}" || true
    done

    trap - ${_Shtk_Cleanup_Traps}  # Prevent double execution.
    if [ "${signo}" = EXIT ]; then
        exit "${exitcode}"
    else
        kill "-${signo}" ${$}
    fi
}


# Sets up exit traips to run the cleanup handlers.
_shtk_cleanup_install_traps() {
    if shtk_bool_check "${_Shtk_Cleanup_Installed}"; then
        return 0
    fi
    for code in ${_Shtk_Cleanup_Traps}; do
        trap "_shtk_cleanup_run_handlers '${code}' \$?" "${code}"
    done
    _Shtk_Cleanup_Installed=true
}


shtk_cleanup_register() {
    for funcname in "${@}"; do
        shtk_list_contains "${funcname}" ${_Shtk_Cleanup_Handlers} \
            || _Shtk_Cleanup_Handlers="${_Shtk_Cleanup_Handlers} ${funcname}"
    done
    _shtk_cleanup_install_traps
}
