While iterating through the commit parents, perform the generation
number calculation and compare against the value stored in the
commit-graph.
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.
Since Git will ship with the commit-graph feature without generation
numbers, we need to accept commit-graphs with all generation numbers
equal to zero. In this case, ignore the generation number calculation.
However, verify that we should never have a mix of zero and non-zero
generation numbers. Create a test that sets one commit to generation
zero and all following commits report a failure as they have non-zero
generation in a file that contains generation number zero.
Signed-off-by: Derrick Stolee <dstolee@xxxxxxxxxxxxx>
---
commit-graph.c | 34 ++++++++++++++++++++++++++++++++++
t/t5318-commit-graph.sh | 11 +++++++++++
2 files changed, 45 insertions(+)
diff --git a/commit-graph.c b/commit-graph.c
index fcebd0925c..b97fa05ec9 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -845,10 +845,14 @@ static void graph_report(const char *fmt, ...)
va_end(ap);
}
+#define GENERATION_ZERO_EXISTS 1
+#define GENERATION_NUMBER_EXISTS 2
+
int verify_commit_graph(struct commit_graph *g)
{
uint32_t i, cur_fanout_pos = 0;
struct object_id prev_oid, cur_oid;
+ int generation_zero = 0;
if (!g) {
graph_report("no commit-graph file loaded");
@@ -910,6 +914,7 @@ 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);
@@ -944,6 +949,9 @@ 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;
+
graph_parents = graph_parents->next;
odb_parents = odb_parents->next;
}
@@ -951,6 +959,32 @@ 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 (!graph_commit->generation) {
+ if (generation_zero == GENERATION_NUMBER_EXISTS)
+ graph_report("commit-graph has generation number zero for commit %s, but non-zero elsewhere",
+ oid_to_hex(&cur_oid));
+ generation_zero = GENERATION_ZERO_EXISTS;
+ } else if (generation_zero == GENERATION_ZERO_EXISTS)
+ graph_report("commit-graph has non-zero generation number for commit %s, but zero elsewhere",
+ oid_to_hex(&cur_oid));
+
+ if (generation_zero == GENERATION_ZERO_EXISTS)
+ continue;
+
+ /*
+ * 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.
+ */
+ if (max_generation == GENERATION_NUMBER_MAX)
+ max_generation--;
+
+ 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);
}
return verify_commit_graph_error;
diff --git a/t/t5318-commit-graph.sh b/t/t5318-commit-graph.sh
index ec0964112a..a6ea1341dc 100755
--- a/t/t5318-commit-graph.sh
+++ b/t/t5318-commit-graph.sh
@@ -272,6 +272,7 @@ GRAPH_BYTE_COMMIT_TREE=$GRAPH_COMMIT_DATA_OFFSET
GRAPH_BYTE_COMMIT_PARENT=$(($GRAPH_COMMIT_DATA_OFFSET + $HASH_LEN))
GRAPH_BYTE_COMMIT_EXTRA_PARENT=$(($GRAPH_COMMIT_DATA_OFFSET + $HASH_LEN + 4))
GRAPH_BYTE_COMMIT_WRONG_PARENT=$(($GRAPH_COMMIT_DATA_OFFSET + $HASH_LEN + 3))
+GRAPH_BYTE_COMMIT_GENERATION=$(($GRAPH_COMMIT_DATA_OFFSET + $HASH_LEN + 11))
# usage: corrupt_graph_and_verify <position> <data> <string>
# Manipulates the commit-graph file at the position
@@ -366,4 +367,14 @@ test_expect_success 'detect wrong parent' '
"commit-graph parent for"
'
+test_expect_success 'detect incorrect generation number' '
+ corrupt_graph_and_verify $GRAPH_BYTE_COMMIT_GENERATION "\070" \
+ "generation for commit"
+'
+
+test_expect_success 'detect incorrect generation number' '
+ corrupt_graph_and_verify $GRAPH_BYTE_COMMIT_GENERATION "\01" \
+ "non-zero generation number"
+'
+
test_done
--
2.18.0.rc1
