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[PATCH 1/5] pack-bitmap.c: fix broken warning() when missing MIDX'd pack

From
Taylor Blau <me@ttaylorr.com>
Date
May 25, 2025, 18:41 UTC
Message-ID
<ad7295b11b2e2c48d859623bf1bcfd92ef15ef9d.1748198489.git.me@ttaylorr.com>
In-Reply-To
<cover.1748198489.git.me@ttaylorr.com>

In commit 44f9fd6496 (pack-bitmap.c: check preferred pack validity when opening MIDX bitmap, 2022-05-24) we started opening all packs contained within a MIDX when loading its corresponding bitmap.

However, if a pack is missing, then we will emit a warning like:
    warning: could not open pack pack-$HASH.pack

Later on commit f31a17cea5 (pack-bitmap.c: open and store incremental bitmap layers, 2025-03-20) updated this code to work with incremental MIDX bitmaps, but did not adjust the index into the 'pack_names' field.

So if there is a pack in an incremental MIDX chain with a pack in a MIDX layer with a non-zero number of packs in its base layer(s) (in other words, any MIDX layer outside of the first one) that cannot be loaded, we will do an out-of-bounds lookup.

Adjust the lookup into the 'pack_names' array by the number of packs in the base to prevent a potential SIGSEGV here.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
---
 pack-bitmap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/pack-bitmap.c b/pack-bitmap.c
index b9f1d86604..99c4927e9c 100644
--- a/pack-bitmap.c
+++ b/pack-bitmap.c
@@ -490,7 +490,7 @@ static int open_midx_bitmap_1(struct bitmap_index *bitmap_git,
 	for (i = 0; i < bitmap_git->midx->num_packs + bitmap_git->midx->num_packs_in_base; i++) {
 		if (prepare_midx_pack(bitmap_repo(bitmap_git), bitmap_git->midx, i)) {
 			warning(_("could not open pack %s"),
-				bitmap_git->midx->pack_names[i]);
+				bitmap_git->midx->pack_names[i - bitmap_git->midx->num_packs_in_base]);
 			goto cleanup;
 		}
 	}
-- 
2.49.0.641.gb9c9c4c3bd
Previous: Taylor BlauNext: Patrick Steinhardt
Message 21 of 53 in “packfile: avoid access(3p) calls for missing packs”
  1. packfile: avoid access(3p) calls for missing packsPatrick Steinhardt, May 16, 2025
  2. Junio C HamanoMay 16, 2025
  3. Jeff KingMay 19, 2025
  4. Junio C HamanoMay 19, 2025
  5. Patrick SteinhardtMay 20, 2025
  6. Jeff KingMay 22, 2025
  7. Taylor BlauMay 23, 2025
  8. Jeff KingMay 23, 2025
  9. 0/2 packfile: avoid access(3p) calls for missing packsPatrick Steinhardt, May 20, 2025
  10. 1/2 packfile: explain ordering of how we look up auxiliary pack filesPatrick Steinhardt, May 20, 2025
  11. Taylor BlauMay 23, 2025
  12. 2/2 midx: stop repeatedly looking up nonexistent packfilesPatrick Steinhardt, May 20, 2025
  13. Jeff KingMay 22, 2025
  14. Junio C HamanoMay 22, 2025
  15. Jeff KingMay 22, 2025
  16. Junio C HamanoMay 22, 2025
  17. Taylor BlauMay 23, 2025
  18. Jeff KingMay 23, 2025
  19. Taylor BlauMay 23, 2025
  20. 0/5 midx: improve prepare_midx_pack() ergonomicsTaylor Blau, May 25, 2025
  21. 1/5 pack-bitmap.c: fix broken warning() when missing MIDX'd packTaylor Blau, May 25, 2025
  22. Patrick SteinhardtMay 26, 2025
  23. Taylor BlauMay 28, 2025
  24. 2/5 midx-write.c: guard against incremental MIDXs in want_included_pack()Taylor Blau, May 25, 2025
  25. Patrick SteinhardtMay 26, 2025
  26. Taylor BlauMay 28, 2025
  27. 3/5 midx-write.c: simplify fill_packs_from_midx()Taylor Blau, May 25, 2025
  28. Patrick SteinhardtMay 26, 2025
  29. Taylor BlauMay 28, 2025
  30. 4/5 midx-write.c: extract inner loop from fill_packs_from_midx()Taylor Blau, May 25, 2025
  31. 5/5 midx: return a `packed_git` pointer from `prepare_midx_pack()`Taylor Blau, May 25, 2025
  32. Patrick SteinhardtMay 26, 2025
  33. Taylor BlauMay 28, 2025
  34. Patrick SteinhardtMay 28, 2025
  35. 0/4 midx: improve prepare_midx_pack() ergonomicsTaylor Blau, May 28, 2025
  36. 1/4 midx: access pack names through `nth_midxed_pack_name()`Taylor Blau, May 28, 2025
  37. Junio C HamanoMay 29, 2025
  38. Taylor BlauJun 3, 2025
  39. Junio C HamanoMay 29, 2025
  40. Taylor BlauJun 3, 2025
  41. 2/4 midx-write.c: guard against incremental MIDXs in want_included_pack()Taylor Blau, May 28, 2025
  42. 3/4 midx-write.c: extract inner loop from fill_packs_from_midx()Taylor Blau, May 28, 2025
  43. 4/4 midx: return a `packed_git` pointer from `prepare_midx_pack()`Taylor Blau, May 28, 2025
  44. Jeff KingMay 30, 2025
  45. Taylor BlauJun 3, 2025
  46. Junio C HamanoAug 28, 2025
  47. Taylor BlauMay 23, 2025
  48. Jeff KingMay 23, 2025
  49. Junio C HamanoMay 21, 2025
  50. 0/2 packfile: avoid access(3p) calls for missing packsPatrick Steinhardt, May 28, 2025
  51. 2/2 midx: stop repeatedly looking up nonexistent packfilesPatrick Steinhardt, May 28, 2025
  52. 1/2 packfile: explain ordering of how we look up auxiliary pack filesPatrick Steinhardt, May 28, 2025
  53. Jeff KingMay 30, 2025

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