AoU: ETAS_RTACAR_SM_OS_102
**************************

The ETAS_RTACAR_SM_OS_102 AoU requires that all extended tasks are implemented as endless loops
around any calls to ``WaitEvent()``.

An extended task that is not structured as an endless loop may terminate unexpectedly. Calling
``WaitEvent()`` outside an infinite loop means the task body executes only once: after the first
``WaitEvent()`` returns, execution falls through the end of the task entry-point function and
the task terminates. This is a violation of the AUTOSAR OS model for extended tasks and may
cause undefined behaviour in safety-relevant systems.

Events and the ``WaitEvent`` API are exclusively used by extended tasks. If the project does not use
extended tasks at all, no events are declared and no ``WaitEvent`` calls are made, so the AoU is
trivially satisfied.

Verification Approach
=====================

The verification is performed by analyzing the OS ECUC configuration files (ARXML) provided via the
``--os-arxml`` parameter or discovered in the project directory specified by ``--dir``.

The tool performs the following steps:

1. **Configuration Loading**: Parses the ARXML files to extract the OS configuration, including task
   definitions and their properties.

2. **Extended Task Detection**: Identifies tasks configured as extended tasks (tasks that reference
   events via ``OsTaskEventRef``).

3. **Scalability Class Validation**: Checks that the ``OsScalabilityClass`` parameter is consistent
   across all configuration files. If incompatible values are detected, manual verification is required.

4. **Result Reporting**: Generates one of the following results based on the analysis outcome.


.. important:: Automated Verification Scope

   The current implementation **detects** the presence of extended tasks in the ECUC configuration but
   does **not yet implement full automated verification** that all extended tasks are implemented as
   endless loops around any calls to ``WaitEvent()``.

When extended tasks are detected, the tool reports a **review** result, requiring manual verification that:

    - Every extended task entry-point function contains an outer infinite loop (``while(1)``, ``for(;;)``,
      or equivalent).
    - All calls to ``WaitEvent()`` are reachable only from within that infinite loop.

This manual verification must confirm compliance with the complete AoU requirement as stated in the
RTA-CAR Safety Manual.


ARXML Configuration Requirements
================================

To enable this check, the OS ECUC configuration must be provided in AUTOSAR ARXML format. The tool
analyzes:

- **Task definitions** (``OsTask`` containers) to identify extended tasks
- **Event references** (``OsTaskEventRef``) to determine which tasks are extended
- **Scalability class settings** (``OsScalabilityClass``) to ensure configuration consistency


.. include:: ../rules/ETAS_RTACAR_SM_OS_102.rst

See Also
========

- :ref:`os_command_options` for information on providing ARXML files via ``--os-arxml`` or ``--dir``
- :cite:t:`ETAS_SM` section on extended task implementation requirements and the WaitEvent API
- :cite:t:`AUTOSAR` specification for extended task scheduling semantics