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Re: [PATCH 4/4] pack-check: fix verification of large objects

From
Jeff King <peff@peff.net>
Date
Feb 23, 2026, 11:11 UTC
Message-ID
<20260223111120.GC215364@coredump.intra.peff.net>
In-Reply-To
<20260223-pks-fsck-fix-v1-4-c29036832b6e@pks.im>
On Mon, Feb 23, 2026 at 10:50:43AM +0100, Patrick Steinhardt wrote:
Show 10 quoted lines
> diff --git a/pack-check.c b/pack-check.c
> index 46782a29d5..6149567060 100644
> --- a/pack-check.c
> +++ b/pack-check.c
> @@ -155,7 +155,7 @@ static int verify_packfile(struct repository *r,
>  			err = error("packed %s from %s is corrupt",
>  				    oid_to_hex(&oid), p->pack_name);
>  		else if (!data &&
> -			 (!(stream = odb_read_stream_open(r->objects, &oid, NULL)) ||
> +			 (packfile_read_object_stream(&stream, p, entries[i].offset) < 0 ||
And now this change is delightfully simple.
Show 14 quoted lines
> +test_expect_success 'fsck handles multiple packfiles with big blobs' '
> +	test_when_finished "rm -rf repo" &&
> +	git init repo &&
> +	(
> +		cd repo &&
> +		blob_one=$(test-tool genrandom one 200k | git hash-object -t blob -w --stdin) &&
> +		blob_two=$(test-tool genrandom two 200k | git hash-object -t blob -w --stdin) &&
> +		printf "%s\n" "$blob_one" | git pack-objects .git/objects/pack/pack &&
> +		printf "%s\n" "$blob_two" | git pack-objects .git/objects/pack/pack &&
> +		remove_object "$blob_one" &&
> +		remove_object "$blob_two" &&
> +		git -c core.bigFileThreshold=100k fsck
> +	)
> +'

I like seeing this much-more-specific test case. It does sort of become a noop if we fix the iteration problem, though.

A more concrete test would probably be something like:
   1. Two packs, $X and $Y, both contain the same object.
   2. The object is corrupt in $X but not in $Y.
   3. Running fsck detects that one copy is corrupt but the other is
      not.

Right now it may or may not fail depending on the ordering of the packs in the MRU list (which we might be able to tweak via mtimes). But hopefully in the "after" state it should deterministically complain about $X.

-Peff
Previous: Patrick SteinhardtNext: Patrick Steinhardt
Message 16 of 26 in “pack-check: fix verification of large objects”
  1. 0/4 pack-check: fix verification of large objectsPatrick Steinhardt, Feb 23, 2026
  2. 1/4 t/helper: improve "genrandom" test helperPatrick Steinhardt, Feb 23, 2026
  3. Jeff KingFeb 23, 2026
  4. Patrick SteinhardtFeb 23, 2026
  5. Eric SunshineFeb 23, 2026
  6. 2/4 object-file: adapt `stream_object_signature()` to take a streamPatrick Steinhardt, Feb 23, 2026
  7. Jeff KingFeb 23, 2026
  8. Patrick SteinhardtFeb 23, 2026
  9. Jeff KingFeb 23, 2026
  10. 3/4 packfile: expose function to read object stream for an offsetPatrick Steinhardt, Feb 23, 2026
  11. Jeff KingFeb 23, 2026
  12. Patrick SteinhardtFeb 23, 2026
  13. Jeff KingFeb 23, 2026
  14. Patrick SteinhardtFeb 23, 2026
  15. 4/4 pack-check: fix verification of large objectsPatrick Steinhardt, Feb 23, 2026
  16. Jeff KingFeb 23, 2026
  17. Patrick SteinhardtFeb 23, 2026
  18. Jeff KingFeb 23, 2026
  19. Patrick SteinhardtFeb 23, 2026
  20. Junio C HamanoFeb 23, 2026
  21. Patrick SteinhardtFeb 24, 2026
  22. 0/4 pack-check: fix verification of large objectsPatrick Steinhardt, Feb 23, 2026
  23. 1/4 t/helper: improve "genrandom" test helperPatrick Steinhardt, Feb 23, 2026
  24. 2/4 object-file: adapt `stream_object_signature()` to take a streamPatrick Steinhardt, Feb 23, 2026
  25. 3/4 packfile: expose function to read object stream for an offsetPatrick Steinhardt, Feb 23, 2026
  26. 4/4 pack-check: fix verification of large objectsPatrick Steinhardt, Feb 23, 2026

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