On Fri, Aug 11, 2023 at 01:05:39PM -0400, Taylor Blau wrote:
> Here's a small reroll of a series that I sent which expanded on a patch
> that Peff sent earlier in the thread to remove a section of unreachable
> code that was noticed by Coverity in the `verify_one_commit_graph()`
> function.
>
> Everything is the same in the first three patches. The fourth patch is
> slightly modified to (in addition to flipping the conditional) extract
> the mixed zero/non-zero generation number checks out to its own
> function.
>
> The fifth patch is new, and avoids repeatedly warning about mixed
> generation numbers by treating `generation_zero` as a bitfield.
This all looks correct to me. Let me show what I thought the result
might look like, just because I think the result is a bit simpler. We
may be hitting diminishing returns on refactoring here, though, so if
you're not wildly impressed, I'm happy enough if we go with what you've
written.
This applies on top of yours, but probably would replace patches 2, 4,
and 5 (the flip-flop case isn't even really worth testing after this,
since the message can obviously only be shown once).
commit-graph.c | 42 +++++++++--------------------------
t/t5318-commit-graph.sh | 18 ++-------------
2 files changed, 13 insertions(+), 47 deletions(-)
diff --git a/commit-graph.c b/commit-graph.c
index 8d924b4509..079bbc8598 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -2560,45 +2560,19 @@ static void graph_report(const char *fmt, ...)
va_end(ap);
}
-#define GENERATION_ZERO_EXISTS 1
-#define GENERATION_NUMBER_EXISTS 2
-#define GENERATION_NUMBER_BOTH_EXIST \
- (GENERATION_ZERO_EXISTS | GENERATION_NUMBER_EXISTS)
-
static int commit_graph_checksum_valid(struct commit_graph *g)
{
return hashfile_checksum_valid(g->data, g->data_len);
}
-static void verify_mixed_generation_numbers(struct commit_graph *g,
- struct commit *graph_commit,
- int *generation_zero)
-{
- if (commit_graph_generation_from_graph(graph_commit)) {
- if (*generation_zero & GENERATION_ZERO_EXISTS)
- graph_report(_("commit-graph has non-zero generation "
- "number for commit %s, but zero "
- "elsewhere"),
- oid_to_hex(&graph_commit->object.oid));
- *generation_zero |= GENERATION_NUMBER_EXISTS;
- } else {
- if (*generation_zero & GENERATION_NUMBER_EXISTS)
- graph_report(_("commit-graph has generation number "
- "zero for commit %s, but non-zero "
- "elsewhere"),
- oid_to_hex(&graph_commit->object.oid));
- *generation_zero |= GENERATION_ZERO_EXISTS;
- }
-}
-
static int verify_one_commit_graph(struct repository *r,
struct commit_graph *g,
struct progress *progress,
uint64_t *seen)
{
uint32_t i, cur_fanout_pos = 0;
struct object_id prev_oid, cur_oid;
- int generation_zero = 0;
+ struct commit *seen_gen_zero = NULL, *seen_gen_non_zero = NULL;
verify_commit_graph_error = verify_commit_graph_lite(g);
if (verify_commit_graph_error)
@@ -2704,11 +2678,12 @@ static int verify_one_commit_graph(struct repository *r,
graph_report(_("commit-graph parent list for commit %s terminates early"),
oid_to_hex(&cur_oid));
- if (generation_zero != GENERATION_NUMBER_BOTH_EXIST)
- verify_mixed_generation_numbers(g, graph_commit,
- &generation_zero);
+ if (!commit_graph_generation_from_graph(graph_commit))
+ seen_gen_zero = graph_commit;
+ else
+ seen_gen_non_zero = graph_commit;
- if (generation_zero & GENERATION_ZERO_EXISTS)
+ if (seen_gen_zero)
continue;
/*
@@ -2734,6 +2709,11 @@ static int verify_one_commit_graph(struct repository *r,
odb_commit->date);
}
+ if (seen_gen_zero && seen_gen_non_zero)
+ graph_report(_("commit-graph has both zero and non-zero generations (e.g., commits %s and %s"),
+ oid_to_hex(&seen_gen_zero->object.oid),
+ oid_to_hex(&seen_gen_non_zero->object.oid));
+
return verify_commit_graph_error;
}
diff --git a/t/t5318-commit-graph.sh b/t/t5318-commit-graph.sh
index 2626d41c94..ca5e2c87ae 100755
--- a/t/t5318-commit-graph.sh
+++ b/t/t5318-commit-graph.sh
@@ -620,26 +620,12 @@ test_expect_success 'detect incorrect chunk count' '
test_expect_success 'detect mixed generation numbers (non-zero to zero)' '
corrupt_graph_and_verify $GRAPH_BYTE_COMMIT_GENERATION_LAST "\0\0\0\0" \
- "but non-zero elsewhere"
+ "both zero and non-zero"
'
test_expect_success 'detect mixed generation numbers (zero to non-zero)' '
corrupt_graph_and_verify $GRAPH_BYTE_COMMIT_GENERATION "\0\0\0\0" \
- "but zero elsewhere"
-'
-
-test_expect_success 'detect mixed generation numbers (flip-flop)' '
- corrupt_graph_setup &&
- for pos in \
- $GRAPH_BYTE_COMMIT_GENERATION \
- $GRAPH_BYTE_COMMIT_GENERATION_LAST
- do
- printf "\0\0\0\0" | dd of="full/$objdir/info/commit-graph" bs=1 \
- seek="$pos" conv=notrunc || return 1
- done &&
-
- test_must_fail git -C full commit-graph verify 2>err &&
- test 1 -eq "$(grep -c "generation number" err)"
+ "both zero and non-zero"
'
test_expect_success 'git fsck (checks commit-graph when config set to true)' '
