feat: add a private enterprise SD-ELEMENT for the log pipeline

[DavidCozens]

Pull request

What this stage adds

A worked example of the one part of RFC 5424 structured data that is yours to
define. SyslogPipelineSd implements the library's StructuredData extension point
directly, in its own translation unit, and emits logPipeline@32473 naming the
transport and the at-rest policy.

Flash +13,548 B (+124 on the previous stage)
RAM +35,688 B (+4)
Log stack +712 B (unchanged)
Service +3,800 B (unchanged)

The IANA elements say what any device can say; a private one says what only this
product knows. What it reports here is the integrity of the logging path itself,
which a collector can use to confirm a record arrived over TLS and was sealed at
rest, and to alert on a device whose pipeline has weakened.

Four bytes of static RAM is the whole instance. A stateless SD source needs no
_Create and no pool slot: the library never allocates one, so it is a vtable the
application owns and points at.

The enterprise number is what makes the SD-ID private — _Begin emits "name@number"
for a non-zero one and a bare IANA "name" for 0. This is the stage that needs the
number rather than the string, so SyslogEnterprise.h now defines the number and
derives the string origin's enterpriseId carries. The two forms cannot drift, and
adopting a real enterprise number stays a one-line edit.

Its own file rather than more of Syslog.c: this is an object implementing a library
interface, not wiring, and a reader after "how do I write my own SD source" should
find one file that is only that. It costs nothing to separate — the figures are
identical either way.

The record is 316 bytes against the 512-byte cap.

Files

 CMakeLists.txt                |  1 +
 README.md                     | 17 +++++++++++------
 app/syslog/Syslog.c           |  4 +++-
 app/syslog/SyslogEnterprise.h | 12 ++++++++----
 app/syslog/SyslogPipelineSd.c | 30 ++++++++++++++++++++++++++++++
 app/syslog/SyslogPipelineSd.h | 13 +++++++++++++
 measurements/pipeline-sd.csv  | 13 +++++++++++++
 measurements/stages.tsv       |  1 +
 run-report.md                 | 22 +++++++++++-----------
 9 files changed, 91 insertions(+), 22 deletions(-)

Checklist

• The diff touches build infra (1 file(s)) — see Files above; deliberate for this stage.
• measurements/pipeline-sd.csv committed.
• Row added to measurements/stages.tsv.
• README regenerated: python3 scripts/gen-cost-table.py.
• ./run.sh green (build + QEMU + baseline self-check) — run-report.md committed.

---

Context for review: 18 of 21 sequential single-commit PRs replaying the integration on top of the Baseline root. Each lands green and reviewed before the next is built on it, because a change to an early commit would force every commit above it to be re-run and re-measured.

Summary by CodeRabbit

• New Features

  • Added syslog pipeline structured data reporting with private SD-ELEMENT support, including transport and data-at-rest protection parameters.

• Documentation

  • Updated README to describe the new Private SD-ELEMENT stage and corresponding memory/flash cost metrics.

• Chores

  • Updated build configuration and test reports with refreshed baseline metrics.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 1deb5636-4365-4e3e-a3b4-3829b2b55847

📥 Commits

Reviewing files that changed from the base of the PR and between 4270f5b and 3d16120.

⛔ Files ignored due to path filters (2)

• measurements/pipeline-sd.csv is excluded by !**/*.csv
• measurements/stages.tsv is excluded by !**/*.tsv

📒 Files selected for processing (7)

• CMakeLists.txt
• README.md
• app/syslog/Syslog.c
• app/syslog/SyslogEnterprise.h
• app/syslog/SyslogPipelineSd.c
• app/syslog/SyslogPipelineSd.h
• run-report.md

---

📝 Walkthrough

Walkthrough

Adds a private RFC 5424 logPipeline structured-data element with fixed TLS and HMAC-SHA256 parameters, registers it in syslog output, includes it in the baseline build, and updates documentation and run-report measurements.

Changes

Pipeline structured data

Layer / File(s)	Summary
Define pipeline SD provider app/syslog/SyslogEnterprise.h, app/syslog/SyslogPipelineSd.h, app/syslog/SyslogPipelineSd.c	Defines the enterprise number and stringification helpers, declares the provider getter, and formats the logPipeline SD-ELEMENT.
Register pipeline SD provider app/syslog/Syslog.c, CMakeLists.txt	Adds the implementation to the baseline target and registers it as the fourth structured-data provider.
Document and validate pipeline SD output README.md, run-report.md	Documents the Private SD-ELEMENT stage and updates measured costs, captured output, and self-check values.

Estimated code review effort: 2 (Simple) | ~10 minutes

Sequence Diagram(s)

sequenceDiagram
  participant Syslog_Start
  participant SyslogPipelineSd_Get
  participant SyslogSender
  participant RFC5424Collector
  Syslog_Start->>SyslogPipelineSd_Get: register pipeline SD provider
  Syslog_Start->>SyslogSender: configure four structured-data providers
  SyslogSender->>RFC5424Collector: emit logPipeline with transport=tls and atRest=hmac-sha256

Loading

Possibly related PRs

• cososo-ltd/solid-syslog-example#23: Directly matches the private enterprise logPipeline SD-ELEMENT and enterprise-number changes.
• cososo-ltd/solid-syslog-example#25: Modifies the same SyslogPipelineSd formatting and atRest policy.
• cososo-ltd/solid-syslog-example#18: Extends the same syslog structured-data registration and enterprise-ID wiring.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 33.33% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly matches the main change: adding a private enterprise SD-ELEMENT for the syslog pipeline.
Description check	✅ Passed	The description follows the template and includes the stage summary plus a complete checklist with the required verification items.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches 💡 1

📝 Generate docstrings 💡

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch stage/pipeline-sd

---

_{Comment @coderabbitai help to get the list of available commands.}