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midx: use chunk-format read API

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Instead of parsing the table of contents directly, use the chunk-format
API methods read_table_of_contents() and pair_chunk(). In particular, we
can use the return value of pair_chunk() to generate an error when a
required chunk is missing.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Derrick Stolee 2021-02-18 14:07:36 +00:00 committed by Junio C Hamano
parent 2692c2f6fd
commit 6ab3b8b8b8
2 changed files with 28 additions and 49 deletions
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71
midx.c
View File

@ -28,7 +28,6 @@
#define MIDX_CHUNKID_OIDLOOKUP 0x4f49444c /* "OIDL" */
#define MIDX_CHUNKID_OBJECTOFFSETS 0x4f4f4646 /* "OOFF" */
#define MIDX_CHUNKID_LARGEOFFSETS 0x4c4f4646 /* "LOFF" */
#define MIDX_CHUNKLOOKUP_WIDTH (sizeof(uint32_t) + sizeof(uint64_t))
#define MIDX_CHUNK_FANOUT_SIZE (sizeof(uint32_t) * 256)
#define MIDX_CHUNK_OFFSET_WIDTH (2 * sizeof(uint32_t))
#define MIDX_CHUNK_LARGE_OFFSET_WIDTH (sizeof(uint64_t))
@ -53,6 +52,19 @@ static char *get_midx_filename(const char *object_dir)
return xstrfmt("%s/pack/multi-pack-index", object_dir);
}
static int midx_read_oid_fanout(const unsigned char *chunk_start,
size_t chunk_size, void *data)
{
struct multi_pack_index *m = data;
m->chunk_oid_fanout = (uint32_t *)chunk_start;
if (chunk_size != 4 * 256) {
error(_("multi-pack-index OID fanout is of the wrong size"));
return 1;
}
return 0;
}
struct multi_pack_index *load_multi_pack_index(const char *object_dir, int local)
{
struct multi_pack_index *m = NULL;
@ -64,6 +76,7 @@ struct multi_pack_index *load_multi_pack_index(const char *object_dir, int local
char *midx_name = get_midx_filename(object_dir);
uint32_t i;
const char *cur_pack_name;
struct chunkfile *cf = NULL;
fd = git_open(midx_name);
@ -113,58 +126,23 @@ struct multi_pack_index *load_multi_pack_index(const char *object_dir, int local
m->num_packs = get_be32(m->data + MIDX_BYTE_NUM_PACKS);
for (i = 0; i < m->num_chunks; i++) {
uint32_t chunk_id = get_be32(m->data + MIDX_HEADER_SIZE +
MIDX_CHUNKLOOKUP_WIDTH * i);
uint64_t chunk_offset = get_be64(m->data + MIDX_HEADER_SIZE + 4 +
MIDX_CHUNKLOOKUP_WIDTH * i);
cf = init_chunkfile(NULL);
if (chunk_offset >= m->data_len)
die(_("invalid chunk offset (too large)"));
if (read_table_of_contents(cf, m->data, midx_size,
MIDX_HEADER_SIZE, m->num_chunks))
goto cleanup_fail;
switch (chunk_id) {
case MIDX_CHUNKID_PACKNAMES:
m->chunk_pack_names = m->data + chunk_offset;
break;
case MIDX_CHUNKID_OIDFANOUT:
m->chunk_oid_fanout = (uint32_t *)(m->data + chunk_offset);
break;
case MIDX_CHUNKID_OIDLOOKUP:
m->chunk_oid_lookup = m->data + chunk_offset;
break;
case MIDX_CHUNKID_OBJECTOFFSETS:
m->chunk_object_offsets = m->data + chunk_offset;
break;
case MIDX_CHUNKID_LARGEOFFSETS:
m->chunk_large_offsets = m->data + chunk_offset;
break;
case 0:
die(_("terminating multi-pack-index chunk id appears earlier than expected"));
break;
default:
/*
* Do nothing on unrecognized chunks, allowing future
* extensions to add optional chunks.
*/
break;
}
}
if (!m->chunk_pack_names)
if (pair_chunk(cf, MIDX_CHUNKID_PACKNAMES, &m->chunk_pack_names) == CHUNK_NOT_FOUND)
die(_("multi-pack-index missing required pack-name chunk"));
if (!m->chunk_oid_fanout)
if (read_chunk(cf, MIDX_CHUNKID_OIDFANOUT, midx_read_oid_fanout, m) == CHUNK_NOT_FOUND)
die(_("multi-pack-index missing required OID fanout chunk"));
if (!m->chunk_oid_lookup)
if (pair_chunk(cf, MIDX_CHUNKID_OIDLOOKUP, &m->chunk_oid_lookup) == CHUNK_NOT_FOUND)
die(_("multi-pack-index missing required OID lookup chunk"));
if (!m->chunk_object_offsets)
if (pair_chunk(cf, MIDX_CHUNKID_OBJECTOFFSETS, &m->chunk_object_offsets) == CHUNK_NOT_FOUND)
die(_("multi-pack-index missing required object offsets chunk"));
pair_chunk(cf, MIDX_CHUNKID_LARGEOFFSETS, &m->chunk_large_offsets);
m->num_objects = ntohl(m->chunk_oid_fanout[255]);
m->pack_names = xcalloc(m->num_packs, sizeof(*m->pack_names));
@ -190,6 +168,7 @@ struct multi_pack_index *load_multi_pack_index(const char *object_dir, int local
cleanup_fail:
free(m);
free(midx_name);
free(cf);
if (midx_map)
munmap(midx_map, midx_size);
if (0 <= fd)

6
t/t5319-multi-pack-index.sh
View File

@ -314,12 +314,12 @@ test_expect_success 'verify bad OID version' '
test_expect_success 'verify truncated chunk count' '
corrupt_midx_and_verify $MIDX_BYTE_CHUNK_COUNT "\01" $objdir \
"missing required"
"final chunk has non-zero id"
'
test_expect_success 'verify extended chunk count' '
corrupt_midx_and_verify $MIDX_BYTE_CHUNK_COUNT "\07" $objdir \
"terminating multi-pack-index chunk id appears earlier than expected"
"terminating chunk id appears earlier than expected"
'
test_expect_success 'verify missing required chunk' '
@ -329,7 +329,7 @@ test_expect_success 'verify missing required chunk' '
test_expect_success 'verify invalid chunk offset' '
corrupt_midx_and_verify $MIDX_BYTE_CHUNK_OFFSET "\01" $objdir \
"invalid chunk offset (too large)"
"improper chunk offset(s)"
'
test_expect_success 'verify packnames out of order' '