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index-pack: learn about pack index version 2 

Like previous patch but for index-pack.

[ There is quite some code duplication between pack-objects and index-pack
  for generating a pack index (and fast-import as well I suppose).  This
  should be reworked into a common function eventually. But not now. ]

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 01:06:34 -04:00 committed by Junio C Hamano
parent c553ca25bd
commit d1a46a9eab
1 changed files with 57 additions and 9 deletions
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66
index-pack.c
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@ -686,9 +686,10 @@ static const char *write_index_file(const char *index_name, unsigned char *sha1)
{
struct sha1file *f;
struct object_entry **sorted_by_sha, **list, **last;
unsigned int array[256];
uint32_t array[256];
int i, fd;
SHA_CTX ctx;
uint32_t index_version;
if (nr_objects) {
sorted_by_sha =
@ -699,7 +700,6 @@ static const char *write_index_file(const char *index_name, unsigned char *sha1)
sorted_by_sha[i] = &objects[i];
qsort(sorted_by_sha, nr_objects, sizeof(sorted_by_sha[0]),
sha1_compare);
}
else
sorted_by_sha = list = last = NULL;
@ -718,6 +718,17 @@ static const char *write_index_file(const char *index_name, unsigned char *sha1)
die("unable to create %s: %s", index_name, strerror(errno));
f = sha1fd(fd, index_name);
/* if last object's offset is >= 2^31 we should use index V2 */
index_version = (objects[nr_objects-1].offset >> 31) ? 2 : 1;
/* index versions 2 and above need a header */
if (index_version >= 2) {
struct pack_idx_header hdr;
hdr.idx_signature = htonl(PACK_IDX_SIGNATURE);
hdr.idx_version = htonl(index_version);
sha1write(f, &hdr, sizeof(hdr));
}
/*
* Write the first-level table (the list is sorted,
* but we use a 256-entry lookup to be able to avoid
@ -734,24 +745,61 @@ static const char *write_index_file(const char *index_name, unsigned char *sha1)
array[i] = htonl(next - sorted_by_sha);
list = next;
}
sha1write(f, array, 256 * sizeof(int));
sha1write(f, array, 256 * 4);
/* recompute the SHA1 hash of sorted object names.
* currently pack-objects does not do this, but that
* can be fixed.
*/
/* compute the SHA1 hash of sorted object names. */
SHA1_Init(&ctx);
/*
* Write the actual SHA1 entries..
*/
list = sorted_by_sha;
for (i = 0; i < nr_objects; i++) {
struct object_entry *obj = *list++;
unsigned int offset = htonl(obj->offset);
sha1write(f, &offset, 4);
if (index_version < 2) {
uint32_t offset = htonl(obj->offset);
sha1write(f, &offset, 4);
}
sha1write(f, obj->sha1, 20);
SHA1_Update(&ctx, obj->sha1, 20);
}
if (index_version >= 2) {
unsigned int nr_large_offset = 0;
/* write the crc32 table */
list = sorted_by_sha;
for (i = 0; i < nr_objects; i++) {
struct object_entry *obj = *list++;
uint32_t crc32_val = htonl(obj->crc32);
sha1write(f, &crc32_val, 4);
}
/* write the 32-bit offset table */
list = sorted_by_sha;
for (i = 0; i < nr_objects; i++) {
struct object_entry *obj = *list++;
uint32_t offset = (obj->offset <= 0x7fffffff) ?
obj->offset : (0x80000000 | nr_large_offset++);
offset = htonl(offset);
sha1write(f, &offset, 4);
}
/* write the large offset table */
list = sorted_by_sha;
while (nr_large_offset) {
struct object_entry *obj = *list++;
uint64_t offset = obj->offset;
if (offset > 0x7fffffff) {
uint32_t split[2];
split[0] = htonl(offset >> 32);
split[1] = htonl(offset & 0xffffffff);
sha1write(f, split, 8);
nr_large_offset--;
}
}
}
sha1write(f, sha1, 20);
sha1close(f, NULL, 1);
free(sorted_by_sha);