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

[cosmo0920]

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Backporting

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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 parameter types across message-pack and buffer handling APIs to better support large sizes.
  • Breaking API change: callers must update uses of the affected message-pack expansion API to match the new size-based 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: cb2b1025-1b1c-487b-84fe-7ec7d0b07e7b

📥 Commits

Reviewing files that changed from the base of the PR and between ca2dfa9 and cb98409.

📒 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

🚧 Files skipped from review as they are similar to previous changes (2)

• plugins/in_syslog/syslog_prot.c
• plugins/in_udp/udp_conn.c

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📝 Walkthrough

Walkthrough

Widened size-related types from int to size_t for flb_msgpack_expand_map and propagated matching local variable/parameter type changes across core and plugin code; added overflow guards in core packing logic. No control-flow or behavioral changes beyond size/overflow handling.

Changes

Cohort / File(s)	Summary
Public API Header include/fluent-bit/flb_pack.h	Updated flb_msgpack_expand_map signature: obj_arr_len from int → size_t, out_size from int* → size_t*.
Core Implementation src/flb_pack.c, src/flb_msgpack_append_message.c	Implementation signature and local variables changed to size_t; added #include <stdint.h> and #include <limits.h>; added overflow guards and explicit cast to uint32_t for msgpack_pack_map.
Plugin Updates plugins/filter_parser/filter_parser.c, plugins/in_syslog/syslog_prot.c, plugins/in_udp/udp_conn.c	Local buffer-size variables (new_size, modified_data_size, etc.) changed from int → size_t to match updated semantics; no logic changes.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Suggested labels

docs-required, backport to v4.0.x

Suggested reviewers

• edsiper
• koleini
• fujimotos

Poem

🐰 From int to size_t I hop with glee,
Bigger bins for bytes, safer memory,
I check for overflows, tidy and light,
Nibbles of code made firm and right,
Hoppity-hop — a tiny bytey sight! 🥕

🚥 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 directly addresses the main change: strict boundary condition handling for extending msgpack maps, which aligns with the primary commit message and code changes implementing overflow guards and size_t type safety.

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✨ Finishing Touches

• 📝 Generate docstrings (stacked PR)
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• Commit unit tests in branch cosmo0920-process-boundary-conditions-strictly-for-extending-msgpack-maps

📝 Coding Plan

• Generate coding plan for human review comments

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