minor warning fix

[JaylinYu]

Summary by CodeRabbit

• Bug Fixes
  • Fixed handling of NULL bridge names in MQTT configuration to prevent potential errors and improve stability.

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[coderabbitai]

📝 Walkthrough

Walkthrough

The PR makes two targeted improvements to MQTT protocol handling: removes a log_error statement from the nmq timer callback in nmq_mqtt.c, and adds NULL-safe assignment checking to bridge_name in mqtt_public.c to prevent NULL dereference.

Changes

Cohort / File(s)	Summary
MQTT Protocol Logging & Configuration src/sp/protocol/mqtt/nmq_mqtt.c, src/supplemental/mqtt/mqtt_public.c	Removed debug logging during pipe removal in timer callback; added NULL-safe conditional assignment for bridge_name string duplication to prevent dereferencing NULL values

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• fix #1406 #1408: Modifies the same nmq_mqtt.c timer callback and pipe/session expiry path where the log statement was removed.
• port a session keeping fix to sdv #1409: Also touches mqtt session handling and sqlite bridge_name allocation logic in both modified files within this PR.

Suggested reviewers

• wanghaEMQ

Poem

🐰 A log line fades away so bright,
NULL checks now hold the bridge just right,
Two tiny tweaks, so clean and lean,
The safest MQTT you've ever seen! 🌿

🚥 Pre-merge checks | ✅ 1 | ❌ 2

❌ Failed checks (2 warnings)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The PR description is completely missing; the required template format with issue reference and change description is not provided.	Add a PR description following the template format, including the issue number, synopsis, and comments explaining the changes made.
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (1 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'minor warning fix' accurately reflects the main changes in the PR, which remove a log_error line and implement a NULL-safe pattern to address compiler warnings.

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✨ Finishing touches

• 📝 Generate docstrings

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📜 Recent review details

Configuration used: defaults

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 1e8f3bf and 4bfd61f.

📒 Files selected for processing (2)

• src/sp/protocol/mqtt/nmq_mqtt.c
• src/supplemental/mqtt/mqtt_public.c

💤 Files with no reviewable changes (1)

• src/sp/protocol/mqtt/nmq_mqtt.c

🧰 Additional context used

🧠 Learnings (1)

📚 Learning: 2025-12-18T11:06:33.930Z

Learnt from: wanghaEMQ
Repo: nanomq/NanoNNG PR: 1384
File: src/sp/protocol/mqtt/auth_http.c:411-418
Timestamp: 2025-12-18T11:06:33.930Z
Learning: In C code using nng_id_map_foreach2 (as in NanoNNG), the callback receives the key as a void* pointing to the actual key value (e.g., a uint64_t*). Do not cast the void* directly to a value type; instead dereference properly, e.g., uint64_t key = *(uint64_t*)k, to obtain the real key. This avoids misinterpretation of the pointer and ensures correct key retrieval in all callbacks that pass a pointer to the key value.

Applied to files:

• src/supplemental/mqtt/mqtt_public.c

🧬 Code graph analysis (1)

src/supplemental/mqtt/mqtt_public.c (1)

src/nng.c (1)

• nng_strdup (106-110)

⏰ Context from checks skipped due to timeout of 90000ms. You can increase the timeout in your CodeRabbit configuration to a maximum of 15 minutes (900000ms). (1)

• GitHub Check: build

🔇 Additional comments (1)

src/supplemental/mqtt/mqtt_public.c (1)

1141-1149: LGTM! Correct NULL-safe guard for bridge_name.

The ternary check prevents passing NULL to nng_strdup, which would cause undefined behavior. The corresponding nng_strfree in nng_mqtt_free_sqlite_opt should handle NULL gracefully, so this change is safe.

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