pack: msgpack_append_message: Process boundary conditions strictly for extending msgpack maps

[cosmo0920]

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Fluent Bit is licensed under Apache 2.0, by submitting this pull request I understand that this code will be released under the terms of that license.

Summary by CodeRabbit

• Bug Fixes

  • Added overflow protection for large buffer operations to prevent size-related errors.

• Refactor

  • Updated function parameter types to better handle larger message and buffer sizes across the codebase.
  • Note: This includes a breaking API change for flb_msgpack_expand_map() function—callers must update their code to use the new parameter types.

[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: ebc8734c-b00a-4052-8cd2-68ed12293307

📥 Commits

Reviewing files that changed from the base of the PR and between a1d9c2a and ca2dfa9.

📒 Files selected for processing (6)

• include/fluent-bit/flb_pack.h
• plugins/filter_parser/filter_parser.c
• plugins/in_syslog/syslog_prot.c
• plugins/in_udp/udp_conn.c
• src/flb_msgpack_append_message.c
• src/flb_pack.c

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📝 Walkthrough

Walkthrough

Fluent-bit updates its public API and internal implementations to widen size-related parameters from int to size_t, affecting the flb_msgpack_expand_map function and related code paths across the core and plugin modules. Overflow guards are added to prevent size_t arithmetic overflows.

Changes

Cohort / File(s)	Summary
Public API Header include/fluent-bit/flb_pack.h	Function signature updated: obj_arr_len parameter changed from int to size_t, and out_size parameter changed from int* to size_t*.
Core Implementation src/flb_pack.c	Function implementation updated to match new signature; added #include <stdint.h> and #include <limits.h>; internal variables (map_num, i, len) changed to size_t; overflow guards added for kv_arr_len and map_num bounds checking; msgpack_pack_map call casted to uint32_t.
Plugin Updates plugins/filter_parser/filter_parser.c, plugins/in_syslog/syslog_prot.c, plugins/in_udp/udp_conn.c, src/flb_msgpack_append_message.c	Local variable modified_data_size (or new_size) changed from int to size_t to align with size semantics and handle larger buffer sizes correctly.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Suggested labels

docs-required, backport to v4.1.x

Suggested reviewers

• edsiper
• koleini
• stoksc
• alecholmes

Poem

🐰 From int to size\_t, we venture far,
Guarding overflows like a northern star,
Wider types now hold the truth,
Protecting memory, preserving youth! ✨

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
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 (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately reflects the main objective of the PR: converting integer types to size_t for proper boundary condition handling in msgpack map extension operations across multiple files.

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✨ Finishing Touches

• 📝 Generate docstrings (stacked PR)
• 📝 Generate docstrings (commit on current branch)

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch cosmo0920-process-boundary-conditions-strictly-for-extending-msgpack-maps

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