fix(contrib/mqtt): ignore unused retval by stephenkgu · Pull Request #34735 · taosdata/TDengine

stephenkgu · 2026-03-10T07:16:08Z

Description

Issue(s)

Close/close/Fix/fix/Resolve/resolve: Issue Link
https://project.feishu.cn/taosdata_td/defect/detail/6779787380

Checklist

Please check the items in the checklist if applicable.

Is the user manual updated?
Are the test cases passed and automated?
Is there no significant decrease in test coverage?

gemini-code-assist · 2026-03-10T07:19:18Z

Summary of Changes

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This pull request focuses on improving code hygiene within the MQTT contributor library by explicitly marking function return values that are intentionally ignored. This change suppresses compiler warnings and clarifies the code's intent without altering its functional behavior, ensuring a cleaner build process.

Highlights

Compiler Warning Fixes: Addressed compiler warnings related to unused return values by wrapping relevant function calls with the UNUSED() macro across multiple C source files.
Code Hygiene Improvement: Enhanced code quality by explicitly indicating that certain function return values are intentionally ignored, preventing potential future issues or confusion.

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Changelog

contrib/libmqtt/ttq/src/ttqMisc.c
- Wrapped umask(old_mask) with UNUSED() to ignore its return value.
- Wrapped getpwuid_r() with UNUSED() to ignore its return value.
- Wrapped getgrgid_r() with UNUSED() to ignore its return value.
contrib/libmqtt/ttq/src/ttqNet.c
- Wrapped multiple calls to COMPAT_CLOSE(*sock) with UNUSED().
- Wrapped multiple calls to net__socket_close(ttq) with UNUSED().
- Wrapped SSL_set_tlsext_host_name(ttq->ssl, host) with UNUSED().
- Wrapped fcntl(*sock, F_GETFL, 0) and fcntl(*sock, F_SETFL, opt | O_NONBLOCK) with UNUSED().
contrib/libmqtt/ttq/src/ttqNet2.c
- Wrapped net__init() with UNUSED().
- Wrapped COMPAT_CLOSE(spare_sock) and COMPAT_CLOSE(new_sock) with UNUSED() in several instances.
- Wrapped COMPAT_CLOSE(sock) with UNUSED() in error handling paths.
contrib/libmqtt/ttq/src/ttqPacket.c
- Wrapped ttqMuxAddOut(ttq) with UNUSED().
- Wrapped ttqMuxRemoveOut(ttq) with UNUSED().
contrib/libmqtt/ttq/src/ttqSendPublish.c
- Wrapped packet__write_varint(packet, proplen) with UNUSED().
contrib/libmqtt/ttq/src/ttqUtil.c
- Wrapped net__socket_close(ttq) with UNUSED() in keepalive checks.
- Wrapped send__pingreq(ttq) with UNUSED().

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Code Review

The pull request primarily introduces UNUSED() macros around various function calls in ttqMisc.c, ttqNet.c, ttqNet2.c, ttqPacket.c, ttqSendPublish.c, and ttqUtil.c to silence compiler warnings about unused return values. Review comments highlight that ignoring these return values for functions like ttqMuxAddOut(), ttqMuxRemoveOut(), packet__write_varint(), getpwuid_r(), getgrgid_r(), and net__init() could lead to issues such as stalled packets, incorrect event monitoring, malformed packets, or masked system/initialization errors. The reviewer suggests checking and handling these return values to improve robustness and prevent potential bugs.

contrib/libmqtt/ttq/src/ttqPacket.c

contrib/libmqtt/ttq/src/ttqSendPublish.c

gemini-code-assist · 2026-03-10T07:34:12Z

contrib/libmqtt/ttq/src/ttqMisc.c

      struct passwd pw, *result;

-      getpwuid_r(getuid(), &pw, buf, sizeof(buf), &result);
+      UNUSED(getpwuid_r(getuid(), &pw, buf, sizeof(buf), &result));


While UNUSED silences the compiler warning, it's better to handle the return value of getpwuid_r. It returns an error code on failure (e.g., if the buffer is too small), which is different from not finding a user. Ignoring this error could hide underlying system issues. Consider checking the return value and logging an error if it's non-zero.

gemini-code-assist · 2026-03-10T07:34:12Z

contrib/libmqtt/ttq/src/ttqMisc.c

      struct group grp, *result;

-      getgrgid_r(getgid(), &grp, buf, sizeof(buf), &result);
+      UNUSED(getgrgid_r(getgid(), &grp, buf, sizeof(buf), &result));


Similar to getpwuid_r, the return value of getgrgid_r should be checked to distinguish between errors (like a too-small buffer) and a group not being found. Please consider handling the error case to make the code more robust.

gemini-code-assist · 2026-03-10T07:34:12Z

contrib/libmqtt/ttq/src/ttqNet.c

  int rc = net__init_ssl_ctx(ttq);
  if (rc) {
-    net__socket_close(ttq);
+    UNUSED(net__socket_close(ttq));


While this change silences the warning, it's worth noting that net__socket_close can return an error. In this specific error-handling path, ignoring it is acceptable to preserve the original error code. However, in other contexts, it might be important to handle it.

gemini-code-assist · 2026-03-10T07:34:12Z

contrib/libmqtt/ttq/src/ttqNet2.c

 void ttqNetBrokerInit(void) {
  spare_sock = socket(AF_INET, SOCK_STREAM, 0);
-  net__init();
+  UNUSED(net__init());


The function net__init() can fail (e.g., if ares_library_init() fails within it), but its return value is being ignored here. This could mask initialization problems with the DNS library. It would be safer to check the return value and handle any potential failure.

fix(contrib/mqtt): ignore unused retval

b56ba8d

stephenkgu requested a review from guanshengliang as a code owner March 10, 2026 07:16

taosdata-bot bot added the team engine label Mar 10, 2026

gemini-code-assist bot reviewed Mar 10, 2026

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JinqingKuang approved these changes Mar 11, 2026

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guanshengliang approved these changes Mar 11, 2026

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guanshengliang merged commit 5ce8153 into main Mar 11, 2026
12 of 13 checks passed

guanshengliang deleted the fix/6779787380 branch March 11, 2026 02:29

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fix(contrib/mqtt): ignore unused retval#34735

fix(contrib/mqtt): ignore unused retval#34735
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fix/6779787380

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stephenkgu commented Mar 10, 2026

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