Derrick Stolee <dstolee@xxxxxxxxxxxxx> writes:
> While iterating through the commit parents, perform the generation
> number calculation and compare against the value stored in the
> commit-graph.
All right, that's good.
What about commit-graph files that have GENERATION_NUMBER_ZERO for all
its commits (because we verify single commit-graph file only, there
wouldn't be GENERATION_NUMBER_ZERO mixed with non-zero generation
numbers)?
Unless we can assume that no commit-graph file in the wild would have
GENERATION_NUMBER_ZERO.
>
> The tests demonstrate that having a different set of parents affects
> the generation number calculation, and this value propagates to
> descendants. Hence, we drop the single-line condition on the output.
I don't understand what part of changes this paragraph of the commit
message refers to.
Anyway, changing parents may not lead to changed generation numbers;
take for example commit with single parent, which we change to other
commit with the same generation number.
>
> Signed-off-by: Derrick Stolee <dstolee@xxxxxxxxxxxxx>
> ---
> commit-graph.c | 18 ++++++++++++++++++
> t/t5318-commit-graph.sh | 6 ++++++
Sidenote: I have just realized that it may be better to put
validation-related tests into different test file.
> 2 files changed, 24 insertions(+)
>
> diff --git a/commit-graph.c b/commit-graph.c
> index fff22dc0c3..ead92460c1 100644
> --- a/commit-graph.c
> +++ b/commit-graph.c
> @@ -922,6 +922,7 @@ int verify_commit_graph(struct commit_graph *g)
> for (i = 0; i < g->num_commits; i++) {
> struct commit *graph_commit, *odb_commit;
> struct commit_list *graph_parents, *odb_parents;
> + uint32_t max_generation = 0;
>
> hashcpy(cur_oid.hash, g->chunk_oid_lookup + g->hash_len * i);
>
> @@ -956,6 +957,9 @@ int verify_commit_graph(struct commit_graph *g)
> oid_to_hex(&graph_parents->item->object.oid),
> oid_to_hex(&odb_parents->item->object.oid));
>
> + if (graph_parents->item->generation > max_generation)
> + max_generation = graph_parents->item->generation;
> +
All right, that calculates the maximum of generation number of commit
parents.
> graph_parents = graph_parents->next;
> odb_parents = odb_parents->next;
> }
> @@ -963,6 +967,20 @@ int verify_commit_graph(struct commit_graph *g)
> if (odb_parents != NULL)
> graph_report("commit-graph parent list for commit %s terminates early",
> oid_to_hex(&cur_oid));
> +
> + /*
> + * If one of our parents has generation GENERATION_NUMBER_MAX, then
> + * our generation is also GENERATION_NUMBER_MAX. Decrement to avoid
> + * extra logic in the following condition.
> + */
Nice trick.
> + if (max_generation == GENERATION_NUMBER_MAX)
> + max_generation--;
What about GENERATION_NUMBER_ZERO?
> +
> + if (graph_commit->generation != max_generation + 1)
> + graph_report("commit-graph generation for commit %s is %u != %u",
> + oid_to_hex(&cur_oid),
> + graph_commit->generation,
> + max_generation + 1);
I think we should also check that generation numbers do not exceed
GENERATION_NUMBER_MAX... unless it is already taken care of?
> }
>
> return verify_commit_graph_error;
> diff --git a/t/t5318-commit-graph.sh b/t/t5318-commit-graph.sh
> index 12f0d7f54d..673b0d37d5 100755
> --- a/t/t5318-commit-graph.sh
> +++ b/t/t5318-commit-graph.sh
> @@ -272,6 +272,7 @@ GRAPH_BYTE_COMMIT_TREE=$GRAPH_COMMIT_DATA_OFFSET
> GRAPH_BYTE_COMMIT_PARENT=`expr $GRAPH_COMMIT_DATA_OFFSET + $HASH_LEN`
> GRAPH_BYTE_COMMIT_EXTRA_PARENT=`expr $GRAPH_COMMIT_DATA_OFFSET + $HASH_LEN + 4`
> GRAPH_BYTE_COMMIT_WRONG_PARENT=`expr $GRAPH_COMMIT_DATA_OFFSET + $HASH_LEN + 3`
> +GRAPH_BYTE_COMMIT_GENERATION=`expr $GRAPH_COMMIT_DATA_OFFSET + $HASH_LEN + 8`
>
> # usage: corrupt_graph_and_verify <position> <data> <string>
> # Manipulates the commit-graph file at the position
> @@ -366,4 +367,9 @@ test_expect_success 'detect incorrect tree OID' '
> "commit-graph parent for"
> '
>
> +test_expect_success 'detect incorrect generation number' '
> + corrupt_graph_and_verify $GRAPH_BYTE_COMMIT_GENERATION "\01" \
I assume that you have checked that it actually corrupts generation
number (without affecting commit date).
> + "generation"
A very minor nitpick: Not "generation for commit"?
> +'
> +
> test_done
