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commit-graph: fix generation number v2 overflow values

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The Generation Data Chunk was implemented and tested in e8b63005c
(commit-graph: implement generation data chunk, 2021-01-16), but the
test was carefully constructed to work on systems with 32-bit dates.
Since the corrected commit date offsets still required more than 31
bits, this triggered writing the generation_data_overflow chunk.

However, upon closer look, the
write_graph_chunk_generation_data_overflow() method writes the offsets
to the chunk (as dictated by the format) but fill_commit_graph_info()
treats the value in the chunk as if it is the full corrected commit date
(not an offset). For some reason, this does not cause an issue when
using the FUTURE_DATE specified in t5318-commit-graph.sh, but it does
show up as a failure in 'git commit-graph verify' if we increase that
FUTURE_DATE to be above four billion.

Fix this error and create a 64-bit timestamp version of the test so we
can test these larger values.

Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Derrick Stolee 2022-03-01 19:48:32 +00:00 committed by Junio C Hamano
parent 3b0199d4c3
commit c8d67b9a68
2 changed files with 28 additions and 1 deletions
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2
commit-graph.c
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@ -806,7 +806,7 @@ static void fill_commit_graph_info(struct commit *item, struct commit_graph *g,
die(_("commit-graph requires overflow generation data but has none"));
offset_pos = offset ^ CORRECTED_COMMIT_DATE_OFFSET_OVERFLOW;
graph_data->generation = get_be64(g->chunk_generation_data_overflow + 8 * offset_pos);
graph_data->generation = item->date + get_be64(g->chunk_generation_data_overflow + 8 * offset_pos);
} else
graph_data->generation = item->date + offset;
} else

27
t/t5328-commit-graph-64bit-time.sh
View File

@ -36,4 +36,31 @@ test_expect_success 'lower layers have overflow chunk' '
graph_git_behavior 'overflow' '' HEAD~2 HEAD
test_expect_success 'set up and verify repo with generation data overflow chunk' '
mkdir repo &&
cd repo &&
git init &&
test_commit --date "$UNIX_EPOCH_ZERO" 1 &&
test_commit 2 &&
test_commit --date "$UNIX_EPOCH_ZERO" 3 &&
git commit-graph write --reachable &&
graph_read_expect 3 generation_data &&
test_commit --date "$FUTURE_DATE" 4 &&
test_commit 5 &&
test_commit --date "$UNIX_EPOCH_ZERO" 6 &&
git branch left &&
git reset --hard 3 &&
test_commit 7 &&
test_commit --date "$FUTURE_DATE" 8 &&
test_commit 9 &&
git branch right &&
git reset --hard 3 &&
test_merge M left right &&
git commit-graph write --reachable &&
graph_read_expect 10 "generation_data generation_data_overflow" &&
git commit-graph verify
'
graph_git_behavior 'overflow 2' repo left right
test_done