Fix #84: Failure in brotli_uncompress_add() is not propagated to the user

[ndossche]

Crucially, must check against hard errors
(BROTLI_DECODER_RESULT_ERROR) not against
BROTLI_DECODER_RESULT_SUCCESS because then NEEDS_MORE_INPUT is misinterpreted as error.

Note: this was found by a hybrid static-dynamic analyzer I'm developing.

Summary by CodeRabbit

• Bug Fixes
  • Improved error handling and reporting for Brotli decompression operations. The system now properly detects and emits warnings when decompression errors occur, while ensuring proper resource cleanup in all scenarios.

[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: b5064e29-cc33-4ab9-a355-5047c089d1b6

📥 Commits

Reviewing files that changed from the base of the PR and between 40c7526 and 987ad82.

📒 Files selected for processing (1)

• brotli.c

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📝 Walkthrough

Walkthrough

The PR modifies brotli_uncompress_add to properly handle Brotli decoder errors. It reorders cleanup by freeing the input buffer before checking the decoder result, adds explicit error detection for BROTLI_DECODER_RESULT_ERROR, and returns FALSE when decoding fails instead of returning output unconditionally.

Changes

Brotli decompression error handling

Layer / File(s)	Summary
Decoder error checking and cleanup reordering brotli.c	brotli_uncompress_add frees the input buffer before evaluating decoder outcome and explicitly checks for BROTLI_DECODER_RESULT_ERROR, emitting a warning, freeing output, and returning FALSE on failure. Previously, output was returned unconditionally before buffer cleanup.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Possibly related issues

• kjdev/php-ext-brotli#84: This PR directly addresses the failure-propagation problem by adding explicit decoder error detection and returning FALSE instead of unconditionally returning output.

Possibly related PRs

• kjdev/php-ext-brotli#83: Both PRs modify error handling and cleanup in brotli_uncompress_add, with PR #83 introducing smart_str output and this PR adding explicit decoder-error checking before returning.

Poem

🐰 A buffer freed, an error caught,
No more confusion, no more thought—
When Brotli falters, speak it true,
Return FALSE, not garbled goo!

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 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: fixing error propagation in brotli_uncompress_add() to properly detect and report failures to users.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[kjdev]

Thanks.