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author | Taylor Blau <me@ttaylorr.com> | 2022-07-12 23:10:28 (GMT) |
---|---|---|
committer | Junio C Hamano <gitster@pobox.com> | 2022-07-15 23:51:38 (GMT) |
commit | 2dd804cd12143741ea4188346fba250e821609b5 (patch) | |
tree | 97f0c0b70cbe5a08b4d0d56e7daf9b83fe201b44 /t | |
parent | 6cd33dceed60949e2dbc32e3f0f5e67c4c882e1e (diff) | |
download | git-2dd804cd12143741ea4188346fba250e821609b5.zip git-2dd804cd12143741ea4188346fba250e821609b5.tar.gz git-2dd804cd12143741ea4188346fba250e821609b5.tar.bz2 |
t5318: demonstrate commit-graph generation v2 corruption
When upgrading a commit-graph using generation v1 to one using
generation v2, it is possible to force Git into a corrupt state where it
(incorrectly) believes that a GDO2 chunk is necessary, *after* deciding
not to write one.
This makes subsequent reads using the commit-graph produce the following
error message:
fatal: commit-graph requires overflow generation data but has none
Demonstrate this bug by increasing our test coverage to include a
minimal example of upgrading a commit-graph from generation v1 to v2.
The only notable components of this test are:
- The committer date of the commit is chosen carefully so that the
offset underflows when computed using a v1 generation number, but
would not overflow when using v2 generation numbers.
- The upgrade to generation number v2 must read in the v1 generation
numbers, which we can do by passing `--changed-paths`, which will
force the commit-graph internals to call `fill_commit_graph_info()`.
A future patch will squash this bug.
Reported-by: Jeff King <peff@peff.net>
Reproduced-by: Will Chandler <wfc@wfchandler.org>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 't')
-rwxr-xr-x | t/t5318-commit-graph.sh | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/t/t5318-commit-graph.sh b/t/t5318-commit-graph.sh index fbf0d64..b85d07f 100755 --- a/t/t5318-commit-graph.sh +++ b/t/t5318-commit-graph.sh @@ -811,4 +811,31 @@ test_expect_success 'set up and verify repo with generation data overflow chunk' graph_git_behavior 'generation data overflow chunk repo' repo left right +test_expect_failure 'overflow during generation version upgrade' ' + git init overflow-v2-upgrade && + ( + cd overflow-v2-upgrade && + + # This commit will have a date at two seconds past the Epoch, + # and a (v1) generation number of 1, since it is a root commit. + # + # The offset will then be computed as 1-2, which will underflow + # to 2^31, which is greater than the v2 offset small limit of + # 2^31-1. + # + # This is sufficient to need a large offset table for the v2 + # generation numbers. + test_commit --date "@2 +0000" base && + git repack -d && + + # Test that upgrading from generation v1 to v2 correctly + # produces the overflow table. + git -c commitGraph.generationVersion=1 commit-graph write && + git -c commitGraph.generationVersion=2 commit-graph write \ + --changed-paths && + + git rev-list --all + ) +' + test_done |