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sha1_file.c: learn about index version 2

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With this patch, packs larger than 4GB are usable, even on a 32-bit machine
(at least on Linux).  If off_t is not large enough to deal with a large
pack then die() is called instead of attempting to use the pack and
producing garbage.

This was tested with a 8GB pack specially created for the occasion on
a 32-bit machine.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
This commit is contained in:
Nicolas Pitre 2007-04-09 01:06:35 -04:00 committed by Junio C Hamano
parent d1a46a9eab
commit 74e34e1fca
1 changed files with 89 additions and 29 deletions
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118
sha1_file.c
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@ -437,7 +437,7 @@ static int check_packed_git_idx(const char *path, struct packed_git *p)
void *idx_map;
struct pack_idx_header *hdr;
size_t idx_size;
uint32_t nr, i, *index;
uint32_t version, nr, i, *index;
int fd = open(path, O_RDONLY);
struct stat st;
@ -455,21 +455,23 @@ static int check_packed_git_idx(const char *path, struct packed_git *p)
idx_map = xmmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
close(fd);
/* a future index format would start with this, as older git
* binaries would fail the non-monotonic index check below.
* give a nicer warning to the user if we can.
*/
hdr = idx_map;
if (hdr->idx_signature == htonl(PACK_IDX_SIGNATURE)) {
munmap(idx_map, idx_size);
return error("index file %s is a newer version"
" and is not supported by this binary"
" (try upgrading GIT to a newer version)",
path);
}
version = ntohl(hdr->idx_version);
if (version < 2 || version > 2) {
munmap(idx_map, idx_size);
return error("index file %s is version %d"
" and is not supported by this binary"
" (try upgrading GIT to a newer version)",
path, version);
}
} else
version = 1;
nr = 0;
index = idx_map;
if (version > 1)
index += 2; /* skip index header */
for (i = 0; i < 256; i++) {
uint32_t n = ntohl(index[i]);
if (n < nr) {
@ -479,19 +481,48 @@ static int check_packed_git_idx(const char *path, struct packed_git *p)
nr = n;
}
/*
* Total size:
* - 256 index entries 4 bytes each
* - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
* - 20-byte SHA1 of the packfile
* - 20-byte SHA1 file checksum
*/
if (idx_size != 4*256 + nr * 24 + 20 + 20) {
munmap(idx_map, idx_size);
return error("wrong index file size in %s", path);
if (version == 1) {
/*
* Total size:
* - 256 index entries 4 bytes each
* - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
* - 20-byte SHA1 of the packfile
* - 20-byte SHA1 file checksum
*/
if (idx_size != 4*256 + nr * 24 + 20 + 20) {
munmap(idx_map, idx_size);
return error("wrong index file size in %s", path);
}
} else if (version == 2) {
/*
* Minimum size:
* - 8 bytes of header
* - 256 index entries 4 bytes each
* - 20-byte sha1 entry * nr
* - 4-byte crc entry * nr
* - 4-byte offset entry * nr
* - 20-byte SHA1 of the packfile
* - 20-byte SHA1 file checksum
* And after the 4-byte offset table might be a
* variable sized table containing 8-byte entries
* for offsets larger than 2^31.
*/
unsigned long min_size = 8 + 4*256 + nr*(20 + 4 + 4) + 20 + 20;
if (idx_size < min_size || idx_size > min_size + (nr - 1)*8) {
munmap(idx_map, idx_size);
return error("wrong index file size in %s", path);
}
if (idx_size != min_size) {
/* make sure we can deal with large pack offsets */
off_t x = 0x7fffffffUL, y = 0xffffffffUL;
if (x > (x + 1) || y > (y + 1)) {
munmap(idx_map, idx_size);
return error("pack too large for current definition of off_t in %s", path);
}
}
}
p->index_version = 1;
p->index_version = version;
p->index_data = idx_map;
p->index_size = idx_size;
p->num_objects = nr;
@ -1531,27 +1562,56 @@ const unsigned char *nth_packed_object_sha1(const struct packed_git *p,
uint32_t n)
{
const unsigned char *index = p->index_data;
index += 4 * 256;
if (n >= p->num_objects)
return NULL;
return index + 24 * n + 4;
index += 4 * 256;
if (p->index_version == 1) {
return index + 24 * n + 4;
} else {
index += 8;
return index + 20 * n;
}
}
static off_t nth_packed_object_offset(const struct packed_git *p, uint32_t n)
{
const unsigned char *index = p->index_data;
index += 4 * 256;
if (p->index_version == 1) {
return ntohl(*((uint32_t *)(index + 24 * n)));
} else {
uint32_t off;
index += 8 + p->num_objects * (20 + 4);
off = ntohl(*((uint32_t *)(index + 4 * n)));
if (!(off & 0x80000000))
return off;
index += p->num_objects * 4 + (off & 0x7fffffff) * 8;
return (((uint64_t)ntohl(*((uint32_t *)(index + 0)))) << 32) |
ntohl(*((uint32_t *)(index + 4)));
}
}
off_t find_pack_entry_one(const unsigned char *sha1,
struct packed_git *p)
{
const uint32_t *level1_ofs = p->index_data;
int hi = ntohl(level1_ofs[*sha1]);
int lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
const unsigned char *index = p->index_data;
unsigned hi, lo;
if (p->index_version > 1) {
level1_ofs += 2;
index += 8;
}
index += 4 * 256;
hi = ntohl(level1_ofs[*sha1]);
lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
do {
int mi = (lo + hi) / 2;
int cmp = hashcmp(index + 24 * mi + 4, sha1);
unsigned mi = (lo + hi) / 2;
unsigned x = (p->index_version > 1) ? (mi * 20) : (mi * 24 + 4);
int cmp = hashcmp(index + x, sha1);
if (!cmp)
return ntohl(*((uint32_t *)((char *)index + (24 * mi))));
return nth_packed_object_offset(p, mi);
if (cmp > 0)
hi = mi;
else