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validate reused pack data with CRC when possible

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This replaces the inflate validation with a CRC validation when reusing
data from a pack which uses index version 2.  That makes repacking much
safer against corruptions, and it should be a bit faster too.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
This commit is contained in:
Nicolas Pitre 2007-04-10 00:15:41 -04:00 committed by Junio C Hamano
parent 4ba7d71153
commit 91ecbeca48
1 changed files with 34 additions and 12 deletions
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46
builtin-pack-objects.c
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@ -233,12 +233,6 @@ static struct revindex_entry * find_packed_object(struct packed_git *p,
die("internal error: pack revindex corrupt");
}
static off_t find_packed_object_size(struct packed_git *p, off_t ofs)
{
struct revindex_entry *entry = find_packed_object(p, ofs);
return entry[1].offset - ofs;
}
static const unsigned char *find_packed_object_name(struct packed_git *p,
off_t ofs)
{
@ -321,6 +315,28 @@ static int check_pack_inflate(struct packed_git *p,
stream.total_in == len) ? 0 : -1;
}
static int check_pack_crc(struct packed_git *p, struct pack_window **w_curs,
off_t offset, off_t len, unsigned int nr)
{
const uint32_t *index_crc;
uint32_t data_crc = crc32(0, Z_NULL, 0);
do {
unsigned int avail;
void *data = use_pack(p, w_curs, offset, &avail);
if (avail > len)
avail = len;
data_crc = crc32(data_crc, data, avail);
offset += avail;
len -= avail;
} while (len);
index_crc = p->index_data;
index_crc += 2 + 256 + p->num_objects * (20/4) + nr;
return data_crc != ntohl(*index_crc);
}
static void copy_pack_data(struct sha1file *f,
struct packed_git *p,
struct pack_window **w_curs,
@ -485,6 +501,7 @@ static unsigned long write_object(struct sha1file *f,
else {
struct packed_git *p = entry->in_pack;
struct pack_window *w_curs = NULL;
struct revindex_entry *revidx;
off_t offset;
if (entry->delta) {
@ -507,12 +524,17 @@ static unsigned long write_object(struct sha1file *f,
hdrlen += 20;
}
offset = entry->in_pack_offset + entry->in_pack_header_size;
datalen = find_packed_object_size(p, entry->in_pack_offset)
- entry->in_pack_header_size;
if (!pack_to_stdout && check_pack_inflate(p, &w_curs,
offset, datalen, entry->size))
die("corrupt delta in pack %s", sha1_to_hex(entry->sha1));
offset = entry->in_pack_offset;
revidx = find_packed_object(p, offset);
datalen = revidx[1].offset - offset;
if (!pack_to_stdout && p->index_version > 1 &&
check_pack_crc(p, &w_curs, offset, datalen, revidx->nr))
die("bad packed object CRC for %s", sha1_to_hex(entry->sha1));
offset += entry->in_pack_header_size;
datalen -= entry->in_pack_header_size;
if (!pack_to_stdout && p->index_version == 1 &&
check_pack_inflate(p, &w_curs, offset, datalen, entry->size))
die("corrupt packed object for %s", sha1_to_hex(entry->sha1));
copy_pack_data(f, p, &w_curs, offset, datalen);
unuse_pack(&w_curs);
reused++;