pack_json: fix data type assignation

[edsiper]

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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
  • Corrects output size reporting when packing JSON with stateful/streaming parsing, ensuring buffer sizes are accurately reflected.
  • Improves handling of incremental reads to prevent incorrect or zero-length output size updates.
  • Enhances stability of the JSON packing path for the JSMN-based backend under stateful operation.

[coderabbitai]

Walkthrough

Adds variables to capture return value and state-derived output size when using the JSMN backend with an existing state, conditionally updating the caller-provided out_size only on success, and returning the captured status. Resets state_out_size before incremental read handling.

Changes

Cohort / File(s)	Summary
JSON packing control flow src/flb_pack_json.c	Replaces direct return from flb_pack_json_state with captured ret and local state_out_size; on success, assigns computed size to caller’s out_size; returns ret. Initializes and later resets state_out_size to 0.

Sequence Diagram(s)

sequenceDiagram
  autonumber
  participant Caller
  participant Pack as flb_pack_json.c
  participant State as flb_pack_json_state

  Caller->>Pack: flb_pack_json(json, len, out_buf, out_size, state)
  alt Backend = JSMN and state exists
    Pack->>State: invoke(json, len, out_buf, state_out_size)
    State-->>Pack: ret, state_out_size
    alt ret == 0
      Note over Pack: Update *out_size = state_out_size
    else ret != 0
      Note over Pack: Do not modify out_size
    end
    Pack-->>Caller: return ret
  else Other paths
    Pack-->>Caller: existing behavior
  end

  rect rgba(230, 246, 255, 0.5)
  Note over Pack: Reset state_out_size = 0 before incremental read handling
  end

Loading

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Poem

I nudge the bytes with cautious cheer,
A hop, a check: is ret now clear?
If green, I tally sizes right,
If not, I keep my paws polite.
JSMN whispers, “All is set”—
I thump and safely pass the bet. 🐇

Pre-merge checks and finishing touches

❌ 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%.	You can run @coderabbitai generate docstrings to improve docstring coverage.

✅ 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 "pack_json: fix data type assignation" is concise, names the affected component (pack_json) and indicates a fix related to assignment/data type; this aligns with the changes in src/flb_pack_json.c that adjust how state_out_size and out_size are computed and assigned, so it accurately summarizes the main change.

✨ Finishing touches

• 📝 Generate Docstrings

🧪 Generate unit tests

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch pack-json-data-type

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[coderabbitai]

Actionable comments posted: 0

🧹 Nitpick comments (1)

src/flb_pack_json.c (1)

30-33: Narrow variable scope and drop redundant zeroing.

ret and state_out_size are only used in the JSMN+state branch. Limit their scope and remove the extra assignment.

-    int ret;
     int backend;
-    int state_out_size = 0;
     struct flb_pack_state *state = NULL;
@@
-        if (state) {
-            state_out_size = 0;
+        if (state) {
+            int ret;
+            int state_out_size = 0;

Also applies to: 50-50

📜 Review details

Configuration used: CodeRabbit UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 1946ade and 15def32.

📒 Files selected for processing (1)

• src/flb_pack_json.c (2 hunks)

🧰 Additional context used

🧬 Code graph analysis (1)

src/flb_pack_json.c (1)

src/flb_pack.c (1)

• flb_pack_json_state (613-684)

⏰ 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). (29)

• GitHub Check: pr-windows-build / call-build-windows-package (Windows 64bit, x64, x64-windows-static, 3.31.6)
• GitHub Check: pr-windows-build / call-build-windows-package (Windows 32bit, x86, x86-windows-static, 3.31.6)
• GitHub Check: pr-windows-build / call-build-windows-package (Windows 64bit (Arm64), amd64_arm64, -DCMAKE_SYSTEM_NAME=Windows -DCMA...
• GitHub Check: run-ubuntu-unit-tests (-DFLB_COVERAGE=On, 3.31.6, gcc, g++)
• GitHub Check: run-ubuntu-unit-tests (-DFLB_SIMD=On, 3.31.6, clang, clang++)
• GitHub Check: run-ubuntu-unit-tests (-DFLB_SANITIZE_MEMORY=On, 3.31.6, gcc, g++)
• GitHub Check: run-ubuntu-unit-tests (-DFLB_SANITIZE_MEMORY=On, 3.31.6, clang, clang++)
• GitHub Check: run-ubuntu-unit-tests (-DFLB_SIMD=Off, 3.31.6, clang, clang++)
• GitHub Check: run-ubuntu-unit-tests (-DFLB_SIMD=Off, 3.31.6, gcc, g++)
• GitHub Check: run-ubuntu-unit-tests (-DFLB_SANITIZE_THREAD=On, 3.31.6, gcc, g++)
• GitHub Check: run-ubuntu-unit-tests (-DFLB_SANITIZE_THREAD=On, 3.31.6, clang, clang++)
• GitHub Check: run-ubuntu-unit-tests (-DFLB_ARROW=On, 3.31.6, gcc, g++)
• GitHub Check: run-ubuntu-unit-tests (-DSANITIZE_ADDRESS=On, 3.31.6, clang, clang++)
• GitHub Check: run-ubuntu-unit-tests (-DFLB_SIMD=On, 3.31.6, gcc, g++)
• GitHub Check: run-ubuntu-unit-tests (-DSANITIZE_UNDEFINED=On, 3.31.6, gcc, g++)
• GitHub Check: run-ubuntu-unit-tests (-DSANITIZE_UNDEFINED=On, 3.31.6, clang, clang++)
• GitHub Check: run-ubuntu-unit-tests (-DFLB_JEMALLOC=On, 3.31.6, clang, clang++)
• GitHub Check: run-ubuntu-unit-tests (-DFLB_JEMALLOC=Off, 3.31.6, clang, clang++)
• GitHub Check: run-ubuntu-unit-tests (-DFLB_JEMALLOC=On, 3.31.6, gcc, g++)
• GitHub Check: run-ubuntu-unit-tests (-DFLB_SMALL=On, 3.31.6, gcc, g++)
• GitHub Check: run-ubuntu-unit-tests (-DFLB_SMALL=On, 3.31.6, clang, clang++)
• GitHub Check: run-ubuntu-unit-tests (-DSANITIZE_ADDRESS=On, 3.31.6, gcc, g++)
• GitHub Check: run-ubuntu-unit-tests (-DFLB_JEMALLOC=Off, 3.31.6, gcc, g++)
• GitHub Check: pr-compile-system-libs (-DFLB_PREFER_SYSTEM_LIBS=On, 3.31.6, gcc, g++, ubuntu-22.04, clang-12)
• GitHub Check: PR - fuzzing test
• GitHub Check: pr-compile-system-libs (-DFLB_PREFER_SYSTEM_LIBS=On, 3.31.6, gcc, g++, ubuntu-24.04, clang-14)
• GitHub Check: pr-compile-system-libs (-DFLB_PREFER_SYSTEM_LIBS=On, 3.31.6, clang, clang++, ubuntu-24.04, clang-14)
• GitHub Check: pr-compile-system-libs (-DFLB_PREFER_SYSTEM_LIBS=On, 3.31.6, clang, clang++, ubuntu-22.04, clang-12)
• GitHub Check: pr-compile-centos-7

🔇 Additional comments (1)

src/flb_pack_json.c (1)

57-64: Good fix: remove size_t/int pointer mismatch and gate out_size updates on success.

Capturing into a local int and assigning to size_t only on success avoids UB on 64‑bit and prevents stale values from leaking through. rg shows many callers still pass &out_size — verify those callers declare an int (not size_t). Run this to locate callers that may be passing a size_t address:

#!/bin/bash
set -euo pipefail
rg -nP '\bflb_pack_json_state\s*\(' -n --hidden | while IFS=: read -r file lineno _; do
  start=$((lineno-40)); [ $start -lt 1 ] && start=1
  echo "== $file:$lineno =="
  sed -n "${start},$((lineno+3))p" "$file"
  sed -n "${start},$((lineno))p" "$file" | rg -nP --color=never 'size_t\s+\w+' || true
done