@matheusbsbs / matheus-bagliano / commits / f90fca638e

commit-graph: consolidate fill_commit_graph_info

Both fill_commit_graph_info() and fill_commit_in_graph() parse information present in commit data chunk. Let's simplify the implementation by calling fill_commit_graph_info() within fill_commit_in_graph(). fill_commit_graph_info() used to not load committer data from commit data chunk. However, with the upcoming switch to using corrected committer date as generation number v2, we will have to load committer date to compute generation number value anyway. e51217e15 (t5000: test tar files that overflow ustar headers, 30-06-2016) introduced a test 'generate tar with future mtime' that creates a commit with committer date of (2^36 + 1) seconds since EPOCH. The CDAT chunk provides 34-bits for storing committer date, thus committer time overflows into generation number (within CDAT chunk) and has undefined behavior. The test used to pass as fill_commit_graph_info() would not set struct member `date` of struct commit and load committer date from the object database, generating a tar file with the expected mtime. However, with corrected commit date, we will load the committer date from CDAT chunk (truncated to lower 34-bits to populate the generation number. Thus, Git sets date and generates tar file with the truncated mtime. The ustar format (the header format used by most modern tar programs) only has room for 11 (or 12, depending on some implementations) octal digits for the size and mtime of each file. As the CDAT chunk is overflow by 12-octal digits but not 11-octal digits, we split the existing tests to test both implementations separately and add a new explicit test for 11-digit implementation. To test the 11-octal digit implementation, we create a future commit with committer date of 2^34 - 1, which overflows 11-octal digits without overflowing 34-bits of the Commit Date chunks. To test the 12-octal digit implementation, the smallest committer date possible is 2^36 + 1, which overflows the CDAT chunk and thus commit-graph must be disabled for the test. Signed-off-by: Abhishek Kumar <abhishekkumar8222@gmail.com> Reviewed-by: Taylor Blau <me@ttaylorr.com> Reviewed-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Abhishek Kumar committed Jan 16, 2021 at 18:11 UTC f90fca638e99a031dce8e3aca72427b2f9b4bb38

2 files changed +31 -20

commit-graph.c

+10 -17

@@ -753,15 +753,24 @@ static void fill_commit_graph_info(struct commit *item, struct commit_graph *g,

753 const unsigned char *commit_data;

754 struct commit_graph_data *graph_data;

755 uint32_t lex_index;

756 + uint64_t date_high, date_low;

757

758 while (pos < g->num_commits_in_base)

759 g = g->base_graph;

760

761 + if (pos >= g->num_commits + g->num_commits_in_base)

762 + die(_("invalid commit position. commit-graph is likely corrupt"));

763 +

764 lex_index = pos - g->num_commits_in_base;

765 commit_data = g->chunk_commit_data + GRAPH_DATA_WIDTH * lex_index;

766

767 graph_data = commit_graph_data_at(item);

768 graph_data->graph_pos = pos;

769 +

770 + date_high = get_be32(commit_data + g->hash_len + 8) & 0x3;

771 + date_low = get_be32(commit_data + g->hash_len + 12);

772 + item->date = (timestamp_t)((date_high << 32) | date_low);

773 +

774 graph_data->generation = get_be32(commit_data + g->hash_len + 8) >> 2;

775 }

776

@@ -776,38 +785,22 @@ static int fill_commit_in_graph(struct repository *r,

785 {

786 uint32_t edge_value;

787 uint32_t *parent_data_ptr;

779 - uint64_t date_low, date_high;

788 struct commit_list **pptr;

781 - struct commit_graph_data *graph_data;

789 const unsigned char *commit_data;

790 uint32_t lex_index;

791

792 while (pos < g->num_commits_in_base)

793 g = g->base_graph;

794

788 - if (pos >= g->num_commits + g->num_commits_in_base)

789 - die(_("invalid commit position. commit-graph is likely corrupt"));

795 + fill_commit_graph_info(item, g, pos);

796

791 - /*

792 - * Store the "full" position, but then use the

793 - * "local" position for the rest of the calculation.

794 - */

795 - graph_data = commit_graph_data_at(item);

796 - graph_data->graph_pos = pos;

797 lex_index = pos - g->num_commits_in_base;

798 -

798 commit_data = g->chunk_commit_data + (g->hash_len + 16) * lex_index;

799

800 item->object.parsed = 1;

801

802 set_commit_tree(item, NULL);

803

805 - date_high = get_be32(commit_data + g->hash_len + 8) & 0x3;

806 - date_low = get_be32(commit_data + g->hash_len + 12);

807 - item->date = (timestamp_t)((date_high << 32) | date_low);

808 -

809 - graph_data->generation = get_be32(commit_data + g->hash_len + 8) >> 2;

810 -

804 pptr = &item->parents;

805

806 edge_value = get_be32(commit_data + g->hash_len);

t/t5000-tar-tree.sh

+21 -3

@@ -431,15 +431,33 @@ test_expect_success TAR_HUGE,LONG_IS_64BIT 'system tar can read our huge size' '

431 test_cmp expect actual

432 '

433

434 -test_expect_success TIME_IS_64BIT 'set up repository with far-future commit' '

434 +test_expect_success TIME_IS_64BIT 'set up repository with far-future (2^34 - 1) commit' '

435 + rm -f .git/index &&

436 + echo foo >file &&

437 + git add file &&

438 + GIT_COMMITTER_DATE="@17179869183 +0000" \

439 + git commit -m "tempori parendum"

440 +'

441 +

442 +test_expect_success TIME_IS_64BIT 'generate tar with far-future mtime' '

443 + git archive HEAD >future.tar

444 +'

445 +

446 +test_expect_success TAR_HUGE,TIME_IS_64BIT,TIME_T_IS_64BIT 'system tar can read our future mtime' '

447 + echo 2514 >expect &&

448 + tar_info future.tar | cut -d" " -f2 >actual &&

449 + test_cmp expect actual

450 +'

451 +

452 +test_expect_success TIME_IS_64BIT 'set up repository with far-far-future (2^36 + 1) commit' '

453 rm -f .git/index &&

454 echo content >file &&

455 git add file &&

438 - GIT_COMMITTER_DATE="@68719476737 +0000" \

456 + GIT_TEST_COMMIT_GRAPH=0 GIT_COMMITTER_DATE="@68719476737 +0000" \

457 git commit -m "tempori parendum"

458 '

459

442 -test_expect_success TIME_IS_64BIT 'generate tar with future mtime' '

460 +test_expect_success TIME_IS_64BIT 'generate tar with far-far-future mtime' '

461 git archive HEAD >future.tar

462 '

463