[perfloop-agent]

What and why

ZSTD_seekable_loadSeekTable() now frees the installed entries immediately before replacing them with a fully loaded table. It also frees the newly allocated entries when a later refill read fails, returning the same I/O error.

This fixes lost seek-table allocations when a decoder is reused or a multi-read load fails. Failed loads keep the previously installed table's metadata, and exported seek tables remain independent copies. The initialization APIs' source-switching behavior is unchanged. Re-initialization frequency in applications has not been measured.

The test in contrib/seekable_format/tests/seekable_tests.c reuses a decoder across successful and failed loads, retries with a smaller archive, and checks an exported table after decoder destruction. It exercises refill failures with and without checksums.

The seekable tests passed in normal and AddressSanitizer/UndefinedBehaviorSanitizer builds. The parallel-compression consumer test also passed. Focused clang static analysis reported no bugs.

Checklist

• I searched open pull requests and issues: this problem is not already being addressed.
• Bug fix: it comes with a reproducer or a test that fails without the fix.
• Performance change: numbers from repeated runs are included, with CPU, compiler, flags and data. Not applicable: correctness fix.
• I stated below whether AI or other automated tools were used.

Tools used

AI tools were used to investigate ownership, implement the fix, and write the tests.

Case and evidence

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Made by Perfloop. Human sponsor: Tomás Senart. To ask for a change, comment or review in plain words. How Perfloop handles pull requests.

[meta-cla]

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[tsenart]

Hi, I'm Tomás, I build Perfloop. I approved this contribution and will handle review feedback here.

@Cyan4973, this fixes two memory leaks in the same seekable-format module as #4902 and #4717. Successful reinitialization with ZSTD_seekable_initBuff, ZSTD_seekable_initFile or ZSTD_seekable_initAdvanced leaks the previous seek table, and a failed refill read after allocation leaks the new entries. This change frees the previous table when installing a replacement and frees the unpublished entries on refill failure. We found it while hunting correctness bugs with Perfloop. We've had changes merged in Redis, Dolt, Prometheus, ClickHouse, Distribution, and more.

If you'd like anything in this patch changed, just let me know and I'll update it.

[meta-cla]

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[perfloop-agent]

Closing in favor of #4941, which covers both leaks and the reset contract. Thanks!