midx: use chunk-format read API

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>

diff --git a/midx.c b/midx.c
index d2fd9c10feea03e8975c153c47a03ecedc4e6b06..d7ea0d1375fa70cf73169f80cd6c4a6c33e7678f 100644 (file)
--- a/midx.c
+++ b/midx.c
@@ -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);
-
-               if (chunk_offset >= m->data_len)
-                       die(_("invalid chunk offset (too large)"));
-
-               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;
-               }
-       }
+       cf = init_chunkfile(NULL);
 
-       if (!m->chunk_pack_names)
+       if (read_table_of_contents(cf, m->data, midx_size,
+                                  MIDX_HEADER_SIZE, m->num_chunks))
+               goto cleanup_fail;
+
+       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)

diff --git a/t/t5319-multi-pack-index.sh b/t/t5319-multi-pack-index.sh
index 297de502a94fdfc255e9e3de4db801e2f15d02f2..ad4e878b65b82799ba03498b43e5b2968618e5e8 100755 (executable)
--- a/t/t5319-multi-pack-index.sh
+++ b/t/t5319-multi-pack-index.sh
@@ -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' '