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MISRA-C:2012 Compliance

LibUDS targets MISRA-C:2012 for its core (src/, include/). Compliance is checked in CI on every push via scripts/check_misra.sh, which runs cppcheck's MISRA addon against the documented deviation baseline below.

  • No mandatory-rule violations. The baseline contains only Required and Advisory rules, so any mandatory-rule violation introduced later fails CI.
  • Regression gate. Any rule not in the baseline fails the build — it must be fixed, or added here with rationale and to the ACCEPTED list in scripts/check_misra.sh.

Reproduce locally

./scripts/docker_run.sh ./scripts/check_misra.sh
# or directly:
cppcheck --addon=misra --enable=all --inline-suppr -I include -I src/core src/

Documented deviations

Rule Cat. Rationale
15.5 Advisory Single point of exit. Handlers return early on each negative-response path; this is clearer than nesting and is the dominant deviation.
12.1 Advisory Explicit operator-precedence parentheses; the existing expressions are reviewed and unambiguous.
12.3 Advisory Comma operator (initializer lists / loop forms).
2.3 / 2.4 / 2.5 Advisory Unused type/tag/macro: the public API intentionally exposes enums, NRC/SID macros, and types for integrators that are not all referenced inside the library's own translation units.
8.7 / 8.9 Advisory External-linkage symbols and object scope kept for the public API and the per-instance design.
10.1 / 10.4 / 10.8 Required Essential-type arithmetic and casts on protocol fields (byte/bit packing of CAN/ISO-TP/UDS data) use explicit casts; each is reviewed for correctness.
11.1 Required The service dispatch table stores handlers behind a single generic signature.
11.5 Advisory The optional DTC store's callbacks recover their instance by casting the core's opaque void *app_data field back to uds_dtc_store_t *. The field is kept void * deliberately so the protocol core carries no dependency on the optional store.
11.9 Required NULL usage for optional callbacks/pointers.
14.4 Required Idiomatic non-boolean controlling expressions (if (ptr), if (len)).
15.6 / 15.7 Required A few terse compound-statement / else if forms, reviewed.
17.7 Required The transport return value from uds_send_nrc() is intentionally not used on some negative-response paths.

These deviations are stylistic or reflect the protocol-parsing and public-API nature of the code; none affect determinism, memory safety, or the zero-malloc guarantee.