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pack-bitmap: add load corrupt bitmap test 

t5310 lacks a test to ensure git works correctly when commit bitmap
data is corrupted. So this patch add test helper in pack-bitmap.c to
list each commit bitmap position in bitmap file and `load corrupt bitmap`
test case in t/t5310 to corrupt a commit bitmap before loading it.

Signed-off-by: Lidong Yan <502024330056@smail.nju.edu.cn>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
maint
Lidong Yan 2025-07-01 05:32:09 +00:00 committed by Junio C Hamano
parent 73bf771b95
commit bfd5522e98
4 changed files with 96 additions and 5 deletions
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62
pack-bitmap.c
View File

@ -31,6 +31,7 @@ struct stored_bitmap {
struct object_id oid;
struct ewah_bitmap *root;
struct stored_bitmap *xor;
size_t map_pos;
int flags;
};

@ -314,13 +315,14 @@ static struct stored_bitmap *store_bitmap(struct bitmap_index *index,
struct ewah_bitmap *root,
const struct object_id *oid,
struct stored_bitmap *xor_with,
int flags)
int flags, size_t map_pos)
{
struct stored_bitmap *stored;
khiter_t hash_pos;
int ret;

stored = xmalloc(sizeof(struct stored_bitmap));
stored->map_pos = map_pos;
stored->root = root;
stored->xor = xor_with;
stored->flags = flags;
@ -376,10 +378,12 @@ static int load_bitmap_entries_v1(struct bitmap_index *index)
struct stored_bitmap *xor_bitmap = NULL;
uint32_t commit_idx_pos;
struct object_id oid;
size_t entry_map_pos;

if (index->map_size - index->map_pos < 6)
return error(_("corrupt ewah bitmap: truncated header for entry %d"), i);

entry_map_pos = index->map_pos;
commit_idx_pos = read_be32(index->map, &index->map_pos);
xor_offset = read_u8(index->map, &index->map_pos);
flags = read_u8(index->map, &index->map_pos);
@ -402,8 +406,9 @@ static int load_bitmap_entries_v1(struct bitmap_index *index)
if (!bitmap)
return -1;

recent_bitmaps[i % MAX_XOR_OFFSET] = store_bitmap(
index, bitmap, &oid, xor_bitmap, flags);
recent_bitmaps[i % MAX_XOR_OFFSET] =
store_bitmap(index, bitmap, &oid, xor_bitmap, flags,
entry_map_pos);
}

return 0;
@ -869,6 +874,7 @@ static struct stored_bitmap *lazy_bitmap_for_commit(struct bitmap_index *bitmap_
int xor_flags;
khiter_t hash_pos;
struct bitmap_lookup_table_xor_item *xor_item;
size_t entry_map_pos;

if (is_corrupt)
return NULL;
@ -928,6 +934,7 @@ static struct stored_bitmap *lazy_bitmap_for_commit(struct bitmap_index *bitmap_
goto corrupt;
}

entry_map_pos = bitmap_git->map_pos;
bitmap_git->map_pos += sizeof(uint32_t) + sizeof(uint8_t);
xor_flags = read_u8(bitmap_git->map, &bitmap_git->map_pos);
bitmap = read_bitmap_1(bitmap_git);
@ -935,7 +942,8 @@ static struct stored_bitmap *lazy_bitmap_for_commit(struct bitmap_index *bitmap_
if (!bitmap)
goto corrupt;

xor_bitmap = store_bitmap(bitmap_git, bitmap, &xor_item->oid, xor_bitmap, xor_flags);
xor_bitmap = store_bitmap(bitmap_git, bitmap, &xor_item->oid,
xor_bitmap, xor_flags, entry_map_pos);
xor_items_nr--;
}

@ -969,6 +977,7 @@ static struct stored_bitmap *lazy_bitmap_for_commit(struct bitmap_index *bitmap_
* Instead, we can skip ahead and immediately read the flags and
* ewah bitmap.
*/
entry_map_pos = bitmap_git->map_pos;
bitmap_git->map_pos += sizeof(uint32_t) + sizeof(uint8_t);
flags = read_u8(bitmap_git->map, &bitmap_git->map_pos);
bitmap = read_bitmap_1(bitmap_git);
@ -976,7 +985,8 @@ static struct stored_bitmap *lazy_bitmap_for_commit(struct bitmap_index *bitmap_
if (!bitmap)
goto corrupt;

return store_bitmap(bitmap_git, bitmap, oid, xor_bitmap, flags);
return store_bitmap(bitmap_git, bitmap, oid, xor_bitmap, flags,
entry_map_pos);

corrupt:
free(xor_items);
@ -2857,6 +2867,48 @@ int test_bitmap_commits(struct repository *r)
return 0;
}

int test_bitmap_commits_with_offset(struct repository *r)
{
struct object_id oid;
struct stored_bitmap *stored;
struct bitmap_index *bitmap_git;
size_t commit_idx_pos_map_pos, xor_offset_map_pos, flag_map_pos,
ewah_bitmap_map_pos;

bitmap_git = prepare_bitmap_git(r);
if (!bitmap_git)
die(_("failed to load bitmap indexes"));

/*
* Since this function needs to know the position of each individual
* bitmap, bypass the commit lookup table (if one exists) by forcing
* the bitmap to eagerly load its entries.
*/
if (bitmap_git->table_lookup) {
if (load_bitmap_entries_v1(bitmap_git) < 0)
die(_("failed to load bitmap indexes"));
}

kh_foreach (bitmap_git->bitmaps, oid, stored, {
commit_idx_pos_map_pos = stored->map_pos;
xor_offset_map_pos = stored->map_pos + sizeof(uint32_t);
flag_map_pos = xor_offset_map_pos + sizeof(uint8_t);
ewah_bitmap_map_pos = flag_map_pos + sizeof(uint8_t);

printf_ln("%s %"PRIuMAX" %"PRIuMAX" %"PRIuMAX" %"PRIuMAX,
oid_to_hex(&oid),
(uintmax_t)commit_idx_pos_map_pos,
(uintmax_t)xor_offset_map_pos,
(uintmax_t)flag_map_pos,
(uintmax_t)ewah_bitmap_map_pos);
})
;

free_bitmap_index(bitmap_git);

return 0;
}

int test_bitmap_hashes(struct repository *r)
{
struct bitmap_index *bitmap_git = prepare_bitmap_git(r);

1
pack-bitmap.h
View File

@ -81,6 +81,7 @@ void traverse_bitmap_commit_list(struct bitmap_index *,
show_reachable_fn show_reachable);
void test_bitmap_walk(struct rev_info *revs);
int test_bitmap_commits(struct repository *r);
int test_bitmap_commits_with_offset(struct repository *r);
int test_bitmap_hashes(struct repository *r);
int test_bitmap_pseudo_merges(struct repository *r);
int test_bitmap_pseudo_merge_commits(struct repository *r, uint32_t n);

8
t/helper/test-bitmap.c
View File

@ -10,6 +10,11 @@ static int bitmap_list_commits(void)
return test_bitmap_commits(the_repository);
}

static int bitmap_list_commits_with_offset(void)
{
return test_bitmap_commits_with_offset(the_repository);
}

static int bitmap_dump_hashes(void)
{
return test_bitmap_hashes(the_repository);
@ -36,6 +41,8 @@ int cmd__bitmap(int argc, const char **argv)

if (argc == 2 && !strcmp(argv[1], "list-commits"))
return bitmap_list_commits();
if (argc == 2 && !strcmp(argv[1], "list-commits-with-offset"))
return bitmap_list_commits_with_offset();
if (argc == 2 && !strcmp(argv[1], "dump-hashes"))
return bitmap_dump_hashes();
if (argc == 2 && !strcmp(argv[1], "dump-pseudo-merges"))
@ -46,6 +53,7 @@ int cmd__bitmap(int argc, const char **argv)
return bitmap_dump_pseudo_merge_objects(atoi(argv[2]));

usage("\ttest-tool bitmap list-commits\n"
"\ttest-tool bitmap list-commits-with-offset\n"
"\ttest-tool bitmap dump-hashes\n"
"\ttest-tool bitmap dump-pseudo-merges\n"
"\ttest-tool bitmap dump-pseudo-merge-commits <n>\n"

30
t/t5310-pack-bitmaps.sh
View File

@ -486,6 +486,36 @@ test_bitmap_cases () {
grep "ignoring extra bitmap" trace2.txt
)
'

test_expect_success 'load corrupt bitmap' '
rm -fr repo &&
git init repo &&
test_when_finished "rm -fr repo" &&
(
cd repo &&
git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&

test_commit base &&

git repack -adb &&
bitmap="$(ls .git/objects/pack/pack-*.bitmap)" &&
chmod +w $bitmap &&

test-tool bitmap list-commits-with-offset >offsets &&
xor_off=$(head -n1 offsets | awk "{print \$3}") &&
printf '\161' |
dd of=$bitmap count=1 bs=1 conv=notrunc seek=$xor_off &&

git rev-list --objects --no-object-names HEAD >expect.raw &&
git rev-list --objects --use-bitmap-index --no-object-names HEAD \
>actual.raw &&

sort expect.raw >expect &&
sort actual.raw >actual &&

test_cmp expect actual
)
'
}

test_bitmap_cases