mirror of
https://github.com/git/git
synced 2024-08-28 20:20:07 +00:00
![Junio C Hamano](/assets/img/avatar_default.png)
The size of objects we read from the repository and data we try to put into the repository are represented in "unsigned long", so that on larger architectures we can handle objects that weigh more than 4GB. But the interface defined in zlib.h to communicate with inflate/deflate limits avail_in (how many bytes of input are we calling zlib with) and avail_out (how many bytes of output from zlib are we ready to accept) fields effectively to 4GB by defining their type to be uInt. In many places in our code, we allocate a large buffer (e.g. mmap'ing a large loose object file) and tell zlib its size by assigning the size to avail_in field of the stream, but that will truncate the high octets of the real size. The worst part of this story is that we often pass around z_stream (the state object used by zlib) to keep track of the number of used bytes in input/output buffer by inspecting these two fields, which practically limits our callchain to the same 4GB limit. Wrap z_stream in another structure git_zstream that can express avail_in and avail_out in unsigned long. For now, just die() when the caller gives a size that cannot be given to a single zlib call. In later patches in the series, we would make git_inflate() and git_deflate() internally loop to give callers an illusion that our "improved" version of zlib interface can operate on a buffer larger than 4GB in one go. Signed-off-by: Junio C Hamano <gitster@pobox.com>
172 lines
4.6 KiB
C
172 lines
4.6 KiB
C
#include "cache.h"
|
|
#include "pack.h"
|
|
#include "pack-revindex.h"
|
|
|
|
struct idx_entry {
|
|
off_t offset;
|
|
const unsigned char *sha1;
|
|
unsigned int nr;
|
|
};
|
|
|
|
static int compare_entries(const void *e1, const void *e2)
|
|
{
|
|
const struct idx_entry *entry1 = e1;
|
|
const struct idx_entry *entry2 = e2;
|
|
if (entry1->offset < entry2->offset)
|
|
return -1;
|
|
if (entry1->offset > entry2->offset)
|
|
return 1;
|
|
return 0;
|
|
}
|
|
|
|
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, NULL, 0);
|
|
|
|
do {
|
|
unsigned long 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 int verify_packfile(struct packed_git *p,
|
|
struct pack_window **w_curs)
|
|
{
|
|
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;
|
|
off_t offset = 0, pack_sig_ofs = 0;
|
|
uint32_t nr_objects, i;
|
|
int err = 0;
|
|
struct idx_entry *entries;
|
|
|
|
/* Note that the pack header checks are actually performed by
|
|
* use_pack when it first opens the pack file. If anything
|
|
* goes wrong during those checks then the call will die out
|
|
* immediately.
|
|
*/
|
|
|
|
git_SHA1_Init(&ctx);
|
|
do {
|
|
unsigned long remaining;
|
|
unsigned char *in = use_pack(p, w_curs, offset, &remaining);
|
|
offset += remaining;
|
|
if (!pack_sig_ofs)
|
|
pack_sig_ofs = p->pack_size - 20;
|
|
if (offset > pack_sig_ofs)
|
|
remaining -= (unsigned int)(offset - pack_sig_ofs);
|
|
git_SHA1_Update(&ctx, in, remaining);
|
|
} while (offset < pack_sig_ofs);
|
|
git_SHA1_Final(sha1, &ctx);
|
|
pack_sig = use_pack(p, w_curs, pack_sig_ofs, NULL);
|
|
if (hashcmp(sha1, pack_sig))
|
|
err = error("%s SHA1 checksum mismatch",
|
|
p->pack_name);
|
|
if (hashcmp(index_base + index_size - 40, pack_sig))
|
|
err = error("%s SHA1 does not match its index",
|
|
p->pack_name);
|
|
unuse_pack(w_curs);
|
|
|
|
/* Make sure everything reachable from idx is valid. Since we
|
|
* have verified that nr_objects matches between idx and pack,
|
|
* we do not do scan-streaming check on the pack file.
|
|
*/
|
|
nr_objects = p->num_objects;
|
|
entries = xmalloc((nr_objects + 1) * sizeof(*entries));
|
|
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)
|
|
die("internal error pack-check nth-packed-object");
|
|
entries[i].offset = nth_packed_object_offset(p, i);
|
|
entries[i].nr = i;
|
|
}
|
|
qsort(entries, nr_objects, sizeof(*entries), compare_entries);
|
|
|
|
for (i = 0; i < nr_objects; i++) {
|
|
void *data;
|
|
enum object_type type;
|
|
unsigned long size;
|
|
|
|
if (p->index_version > 1) {
|
|
off_t offset = entries[i].offset;
|
|
off_t len = entries[i+1].offset - offset;
|
|
unsigned int nr = entries[i].nr;
|
|
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),
|
|
p->pack_name, (uintmax_t)offset);
|
|
}
|
|
data = unpack_entry(p, entries[i].offset, &type, &size);
|
|
if (!data) {
|
|
err = error("cannot unpack %s from %s at offset %"PRIuMAX"",
|
|
sha1_to_hex(entries[i].sha1), p->pack_name,
|
|
(uintmax_t)entries[i].offset);
|
|
break;
|
|
}
|
|
if (check_sha1_signature(entries[i].sha1, data, size, typename(type))) {
|
|
err = error("packed %s from %s is corrupt",
|
|
sha1_to_hex(entries[i].sha1), p->pack_name);
|
|
free(data);
|
|
break;
|
|
}
|
|
free(data);
|
|
}
|
|
free(entries);
|
|
|
|
return err;
|
|
}
|
|
|
|
int verify_pack_index(struct packed_git *p)
|
|
{
|
|
off_t index_size;
|
|
const unsigned char *index_base;
|
|
git_SHA_CTX ctx;
|
|
unsigned char sha1[20];
|
|
int err = 0;
|
|
|
|
if (open_pack_index(p))
|
|
return error("packfile %s index not opened", p->pack_name);
|
|
index_size = p->index_size;
|
|
index_base = p->index_data;
|
|
|
|
/* Verify SHA1 sum of the index file */
|
|
git_SHA1_Init(&ctx);
|
|
git_SHA1_Update(&ctx, index_base, (unsigned int)(index_size - 20));
|
|
git_SHA1_Final(sha1, &ctx);
|
|
if (hashcmp(sha1, index_base + index_size - 20))
|
|
err = error("Packfile index for %s SHA1 mismatch",
|
|
p->pack_name);
|
|
return err;
|
|
}
|
|
|
|
int verify_pack(struct packed_git *p)
|
|
{
|
|
int err = 0;
|
|
struct pack_window *w_curs = NULL;
|
|
|
|
err |= verify_pack_index(p);
|
|
if (!p->index_data)
|
|
return -1;
|
|
|
|
err |= verify_packfile(p, &w_curs);
|
|
unuse_pack(&w_curs);
|
|
|
|
return err;
|
|
}
|