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authorJunio C Hamano <gitster@pobox.com>2011-02-26 00:55:26 (GMT)
committerJunio C Hamano <gitster@pobox.com>2011-02-28 07:29:03 (GMT)
commit3c9fc074c220d5d1d2173c84cc6ae57d750e2a2c (patch)
tree99a89b4e8eaf51852e90679e553eeb44cf5e7cf6 /builtin/index-pack.c
parentfb956c1f44b5c99273eb9e3850717c8b489ff78f (diff)
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index-pack --verify: read anomalous offsets from v2 idx file
A pack v2 .idx file usually records offset using 64-bit representation only when the offset does not fit within 31-bit, but you can handcraft your .idx file to record smaller offset using 64-bit, storing all zero in the upper 4-byte. By inspecting the original idx file when running index-pack --verify, encode such low offsets that do not need to be in 64-bit but are encoded using 64-bit just like the original idx file so that we can still validate the pack/idx pair by comparing the idx file recomputed with the original. Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'builtin/index-pack.c')
-rw-r--r--builtin/index-pack.c48
1 files changed, 48 insertions, 0 deletions
diff --git a/builtin/index-pack.c b/builtin/index-pack.c
index 24a9a16..513fbbc 100644
--- a/builtin/index-pack.c
+++ b/builtin/index-pack.c
@@ -891,6 +891,51 @@ static int git_index_pack_config(const char *k, const char *v, void *cb)
return git_default_config(k, v, cb);
}
+static int cmp_uint32(const void *a_, const void *b_)
+{
+ uint32_t a = *((uint32_t *)a_);
+ uint32_t b = *((uint32_t *)b_);
+
+ return (a < b) ? -1 : (a != b);
+}
+
+static void read_v2_anomalous_offsets(struct packed_git *p,
+ struct pack_idx_option *opts)
+{
+ const uint32_t *idx1, *idx2;
+ uint32_t i;
+
+ /* The address of the 4-byte offset table */
+ idx1 = (((const uint32_t *)p->index_data)
+ + 2 /* 8-byte header */
+ + 256 /* fan out */
+ + 5 * p->num_objects /* 20-byte SHA-1 table */
+ + p->num_objects /* CRC32 table */
+ );
+
+ /* The address of the 8-byte offset table */
+ idx2 = idx1 + p->num_objects;
+
+ for (i = 0; i < p->num_objects; i++) {
+ uint32_t off = ntohl(idx1[i]);
+ if (!(off & 0x80000000))
+ continue;
+ off = off & 0x7fffffff;
+ if (idx2[off * 2])
+ continue;
+ /*
+ * The real offset is ntohl(idx2[off * 2]) in high 4
+ * octets, and ntohl(idx2[off * 2 + 1]) in low 4
+ * octets. But idx2[off * 2] is Zero!!!
+ */
+ ALLOC_GROW(opts->anomaly, opts->anomaly_nr + 1, opts->anomaly_alloc);
+ opts->anomaly[opts->anomaly_nr++] = ntohl(idx2[off * 2 + 1]);
+ }
+
+ if (1 < opts->anomaly_nr)
+ qsort(opts->anomaly, opts->anomaly_nr, sizeof(uint32_t), cmp_uint32);
+}
+
static void read_idx_option(struct pack_idx_option *opts, const char *pack_name)
{
struct packed_git *p = add_packed_git(pack_name, strlen(pack_name), 1);
@@ -903,6 +948,9 @@ static void read_idx_option(struct pack_idx_option *opts, const char *pack_name)
/* Read the attributes from the existing idx file */
opts->version = p->index_version;
+ if (opts->version == 2)
+ read_v2_anomalous_offsets(p, opts);
+
/*
* Get rid of the idx file as we do not need it anymore.
* NEEDSWORK: extract this bit from free_pack_by_name() in