struct apext::tsync::FVContainer

In module tsync, the structure apext::tsync::FVContainer serves as a data container for passing and returning freshness values between applications and Freshness Value Management. It encapsulates the actual freshness value as a byte vector in value, which contains complete or truncated values depending on the direction [SWS_TS_14196], as well as its exact bit length in attribute length [SWS_TS_14195]. Concurrent access requires external coordination by the caller.

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Context

The structure apext::tsync::FVContainer functions within the functional cluster tsync of the AUTOSAR Adaptive Platform as a dedicated data container for freshness values. Included via the header file apext/tsync/fvm.h, it serves as a standardized interface in interaction with the Freshness Value Management (FVM). Its primary responsibility is to provide the actual cryptographic freshness value together with its exact length. For this purpose, the container encapsulates the bit length in data element length [SWS_TS_14195] and the actual payload in the byte vector value [SWS_TS_14196]. The structure thus acts as a bridge between calling applications or protocol layers and the FVM calculation routines.

Lifecycle

As a lightweight data structure (struct), apext::tsync::FVContainer is subject to regular C++ value semantics. Creation typically takes place locally on the caller's stack or dynamically as part of higher-level message creation. With instantiation, the structure assumes responsibility for the lifecycle of the contained vector value of type ara::core::Vector<std::uint8_t> [SWS_TS_14196]. If the structure is passed to interfaces by value or reference, the RAII principle of the vector ensures deterministic release of the allocated memory upon destruction of the container. Question Q-416ceca84f9cfdaf (open) Since apext::tsync::FVContainer provides no internal mechanisms for synchronization, thread-safe coordination during concurrent read and write access rests entirely with the calling software component.

Usage Path

In practical use, apext::tsync::FVContainer undergoes two central directions within interface communication:

• Input parameter: During verification or processing of incoming messages, the container is populated by the application and passed to methods of the FVM. Depending on the context, the field value accommodates either complete freshness values or truncated values [SWS_TS_14196]. In parallel, field length specifies the exact bit count of the contained value [SWS_TS_14195]. This is particularly relevant when the validity of the freshness value does not end on an integer byte boundary.
• Return value: When fresh values are generated by the FVM, the respective method returns an instance of apext::tsync::FVContainer. The calling context subsequently reads out the effective length in bits determined by the FVM via length [SWS_TS_14195] and extracts the corresponding bytes from value [SWS_TS_14196] in order to embed them into downstream security protocols.

Interpretation: The bit count stored in length presumably always corresponds to the rounded-up byte size of vector value, so that incompletely used remaining bits in the last byte of the vector can be precisely delimited by the length specification. Question Q-e8feae8a93c14191 (open)