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Convert the verify_pack callback to struct object_id

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Make the verify_pack_callback take a pointer to struct object_id.
Change the pack checksum to use GIT_MAX_RAWSZ, even though it is not
strictly an object ID.  Doing so ensures resilience against future hash
size changes, and allows us to remove hard-coded assumptions about how
big the buffer needs to be.

Also, use a union to convert the pointer from nth_packed_object_sha1 to
to a pointer to struct object_id.  This behavior is compatible with GCC
and clang and explicitly sanctioned by C11.  The alternatives are to
just perform a cast, which would run afoul of strict aliasing rules, but
should just work, and changing the pointer into an instance of struct
object_id and copying the value.  The latter operation could seriously
bloat memory usage on fsck, which already uses a lot of memory on some
repositories.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
brian m. carlson
2017-05-06 22:10:20 +00:00
committed by Junio C Hamano
parent d3101b533d
commit 9fd750461b
3 changed files with 18 additions and 15 deletions
Download Patch File Download Diff File Expand all files Collapse all files

25
pack-check.c
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@@ -5,7 +5,10 @@
struct idx_entry {
off_t offset;
const unsigned char *sha1;
union idx_entry_object {
const unsigned char *hash;
struct object_id *oid;
} oid;
unsigned int nr;
};
@@ -51,7 +54,7 @@ static int verify_packfile(struct packed_git *p,
off_t index_size = p->index_size;
const unsigned char *index_base = p->index_data;
git_SHA_CTX ctx;
unsigned char sha1[20], *pack_sig;
unsigned char hash[GIT_MAX_RAWSZ], *pack_sig;
off_t offset = 0, pack_sig_ofs = 0;
uint32_t nr_objects, i;
int err = 0;
@@ -71,9 +74,9 @@ static int verify_packfile(struct packed_git *p,
remaining -= (unsigned int)(offset - pack_sig_ofs);
git_SHA1_Update(&ctx, in, remaining);
} while (offset < pack_sig_ofs);
git_SHA1_Final(sha1, &ctx);
git_SHA1_Final(hash, &ctx);
pack_sig = use_pack(p, w_curs, pack_sig_ofs, NULL);
if (hashcmp(sha1, pack_sig))
if (hashcmp(hash, pack_sig))
err = error("%s SHA1 checksum mismatch",
p->pack_name);
if (hashcmp(index_base + index_size - 40, pack_sig))
@@ -90,8 +93,8 @@ static int verify_packfile(struct packed_git *p,
entries[nr_objects].offset = pack_sig_ofs;
/* first sort entries by pack offset, since unpacking them is more efficient that way */
for (i = 0; i < nr_objects; i++) {
entries[i].sha1 = nth_packed_object_sha1(p, i);
if (!entries[i].sha1)
entries[i].oid.hash = nth_packed_object_sha1(p, i);
if (!entries[i].oid.hash)
die("internal error pack-check nth-packed-object");
entries[i].offset = nth_packed_object_offset(p, i);
entries[i].nr = i;
@@ -112,7 +115,7 @@ static int verify_packfile(struct packed_git *p,
if (check_pack_crc(p, w_curs, offset, len, nr))
err = error("index CRC mismatch for object %s "
"from %s at offset %"PRIuMAX"",
sha1_to_hex(entries[i].sha1),
oid_to_hex(entries[i].oid.oid),
p->pack_name, (uintmax_t)offset);
}
@@ -135,14 +138,14 @@ static int verify_packfile(struct packed_git *p,
if (data_valid && !data)
err = error("cannot unpack %s from %s at offset %"PRIuMAX"",
sha1_to_hex(entries[i].sha1), p->pack_name,
oid_to_hex(entries[i].oid.oid), p->pack_name,
(uintmax_t)entries[i].offset);
else if (check_sha1_signature(entries[i].sha1, data, size, typename(type)))
else if (check_sha1_signature(entries[i].oid.hash, data, size, typename(type)))
err = error("packed %s from %s is corrupt",
sha1_to_hex(entries[i].sha1), p->pack_name);
oid_to_hex(entries[i].oid.oid), p->pack_name);
else if (fn) {
int eaten = 0;
err |= fn(entries[i].sha1, type, size, data, &eaten);
err |= fn(entries[i].oid.oid, type, size, data, &eaten);
if (eaten)
data = NULL;
}