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@xxxxxxx>
---
sha1_file.c | 118 ++++++++++++++++++++++++++++++++++++++++++++--------------
1 files changed, 89 insertions(+), 29 deletions(-)
diff --git a/sha1_file.c b/sha1_file.c
index ebdd497..5f3a15d 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -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
--
1.5.1.696.g6d352-dirty
-
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