@matheusbsbs / matheus-bagliano / commits / 1373e547f7

commit-graph: verify generation number

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@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Derrick Stolee committed Jun 27, 2018 at 09:24 UTC 1373e547f7d38b9444fcaae16c1de698b719aa15

2 files changed +45

commit-graph.c

+34

@@ -846,10 +846,14 @@ static void graph_report(const char *fmt, ...)

846 va_end(ap);

847 }

848

849 +#define GENERATION_ZERO_EXISTS 1

850 +#define GENERATION_NUMBER_EXISTS 2

851 +

852 int verify_commit_graph(struct repository *r, struct commit_graph *g)

853 {

854 uint32_t i, cur_fanout_pos = 0;

855 struct object_id prev_oid, cur_oid;

856 + int generation_zero = 0;

857

858 if (!g) {

859 graph_report("no commit-graph file loaded");

@@ -911,6 +915,7 @@ int verify_commit_graph(struct repository *r, struct commit_graph *g)

915 for (i = 0; i < g->num_commits; i++) {

916 struct commit *graph_commit, *odb_commit;

917 struct commit_list *graph_parents, *odb_parents;

918 + uint32_t max_generation = 0;

919

920 hashcpy(cur_oid.hash, g->chunk_oid_lookup + g->hash_len * i);

921

@@ -945,6 +950,9 @@ int verify_commit_graph(struct repository *r, struct commit_graph *g)

950 oid_to_hex(&graph_parents->item->object.oid),

951 oid_to_hex(&odb_parents->item->object.oid));

952

953 + if (graph_parents->item->generation > max_generation)

954 + max_generation = graph_parents->item->generation;

955 +

956 graph_parents = graph_parents->next;

957 odb_parents = odb_parents->next;

958 }

@@ -952,6 +960,32 @@ int verify_commit_graph(struct repository *r, struct commit_graph *g)

960 if (odb_parents != NULL)

961 graph_report("commit-graph parent list for commit %s terminates early",

962 oid_to_hex(&cur_oid));

963 +

964 + if (!graph_commit->generation) {

965 + if (generation_zero == GENERATION_NUMBER_EXISTS)

966 + graph_report("commit-graph has generation number zero for commit %s, but non-zero elsewhere",

967 + oid_to_hex(&cur_oid));

968 + generation_zero = GENERATION_ZERO_EXISTS;

969 + } else if (generation_zero == GENERATION_ZERO_EXISTS)

970 + graph_report("commit-graph has non-zero generation number for commit %s, but zero elsewhere",

971 + oid_to_hex(&cur_oid));

972 +

973 + if (generation_zero == GENERATION_ZERO_EXISTS)

974 + continue;

975 +

976 + /*

977 + * If one of our parents has generation GENERATION_NUMBER_MAX, then

978 + * our generation is also GENERATION_NUMBER_MAX. Decrement to avoid

979 + * extra logic in the following condition.

980 + */

981 + if (max_generation == GENERATION_NUMBER_MAX)

982 + max_generation--;

983 +

984 + if (graph_commit->generation != max_generation + 1)

985 + graph_report("commit-graph generation for commit %s is %u != %u",

986 + oid_to_hex(&cur_oid),

987 + graph_commit->generation,

988 + max_generation + 1);

989 }

990

991 return verify_commit_graph_error;

t/t5318-commit-graph.sh

+11

@@ -272,6 +272,7 @@ GRAPH_BYTE_COMMIT_TREE=$GRAPH_COMMIT_DATA_OFFSET

272 GRAPH_BYTE_COMMIT_PARENT=$(($GRAPH_COMMIT_DATA_OFFSET + $HASH_LEN))

273 GRAPH_BYTE_COMMIT_EXTRA_PARENT=$(($GRAPH_COMMIT_DATA_OFFSET + $HASH_LEN + 4))

274 GRAPH_BYTE_COMMIT_WRONG_PARENT=$(($GRAPH_COMMIT_DATA_OFFSET + $HASH_LEN + 3))

275 +GRAPH_BYTE_COMMIT_GENERATION=$(($GRAPH_COMMIT_DATA_OFFSET + $HASH_LEN + 11))

276

277 # usage: corrupt_graph_and_verify <position> <data> <string>

278 # Manipulates the commit-graph file at the position

@@ -366,4 +367,14 @@ test_expect_success 'detect wrong parent' '

367 "commit-graph parent for"

368 '

369

370 +test_expect_success 'detect incorrect generation number' '

371 + corrupt_graph_and_verify $GRAPH_BYTE_COMMIT_GENERATION "\070" \

372 + "generation for commit"

373 +'

374 +

375 +test_expect_success 'detect incorrect generation number' '

376 + corrupt_graph_and_verify $GRAPH_BYTE_COMMIT_GENERATION "\01" \

377 + "non-zero generation number"

378 +'

379 +

380 test_done