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#include "cache.h"
#include "pack.h"
#include "csum-file.h"

uint32_t pack_idx_default_version = 1;
uint32_t pack_idx_off32_limit = 0x7fffffff;

static int sha1_compare(const void *_a, const void *_b)
{
struct pack_idx_entry *a = *(struct pack_idx_entry **)_a;
struct pack_idx_entry *b = *(struct pack_idx_entry **)_b;
return hashcmp(a->sha1, b->sha1);
}

/*
* On entry *sha1 contains the pack content SHA1 hash, on exit it is
* the SHA1 hash of sorted object names. The objects array passed in
* will be sorted by SHA1 on exit.
*/
char *write_idx_file(char *index_name, struct pack_idx_entry **objects,
int nr_objects, unsigned char *sha1)
{
struct sha1file *f;
struct pack_idx_entry **sorted_by_sha, **list, **last;
off_t last_obj_offset = 0;
uint32_t array[256];
int i, fd;
SHA_CTX ctx;
uint32_t index_version;

if (nr_objects) {
sorted_by_sha = objects;
list = sorted_by_sha;
last = sorted_by_sha + nr_objects;
for (i = 0; i < nr_objects; ++i) {
if (objects[i]->offset > last_obj_offset)
last_obj_offset = objects[i]->offset;
}
qsort(sorted_by_sha, nr_objects, sizeof(sorted_by_sha[0]),
sha1_compare);
}
else
sorted_by_sha = list = last = NULL;

if (!index_name) {
static char tmpfile[PATH_MAX];
snprintf(tmpfile, sizeof(tmpfile),
"%s/tmp_idx_XXXXXX", get_object_directory());
fd = xmkstemp(tmpfile);
index_name = xstrdup(tmpfile);
} else {
unlink(index_name);
fd = open(index_name, O_CREAT|O_EXCL|O_WRONLY, 0600);
}
if (fd < 0)
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 = (last_obj_offset >> 31) ? 2 : pack_idx_default_version;

/* 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
* having to do eight extra binary search iterations).
*/
for (i = 0; i < 256; i++) {
struct pack_idx_entry **next = list;
while (next < last) {
struct pack_idx_entry *obj = *next;
if (obj->sha1[0] != i)
break;
next++;
}
array[i] = htonl(next - sorted_by_sha);
list = next;
}
sha1write(f, array, 256 * 4);

/* 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 pack_idx_entry *obj = *list++;
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 pack_idx_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 pack_idx_entry *obj = *list++;
uint32_t offset = (obj->offset <= pack_idx_off32_limit) ?
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 pack_idx_entry *obj = *list++;
uint64_t offset = obj->offset;
if (offset > pack_idx_off32_limit) {
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);
SHA1_Final(sha1, &ctx);
return index_name;
}

void fixup_pack_header_footer(int pack_fd,
unsigned char *pack_file_sha1,
const char *pack_name,
uint32_t object_count)
{
static const int buf_sz = 128 * 1024;
SHA_CTX c;
struct pack_header hdr;
char *buf;

if (lseek(pack_fd, 0, SEEK_SET) != 0)
die("Failed seeking to start: %s", strerror(errno));
if (read_in_full(pack_fd, &hdr, sizeof(hdr)) != sizeof(hdr))
die("Unable to reread header of %s: %s", pack_name, strerror(errno));
if (lseek(pack_fd, 0, SEEK_SET) != 0)
die("Failed seeking to start: %s", strerror(errno));
hdr.hdr_entries = htonl(object_count);
write_or_die(pack_fd, &hdr, sizeof(hdr));

SHA1_Init(&c);
SHA1_Update(&c, &hdr, sizeof(hdr));

buf = xmalloc(buf_sz);
for (;;) {
ssize_t n = xread(pack_fd, buf, buf_sz);
if (!n)
break;
if (n < 0)
die("Failed to checksum %s: %s", pack_name, strerror(errno));
SHA1_Update(&c, buf, n);
}
free(buf);

SHA1_Final(pack_file_sha1, &c);
write_or_die(pack_fd, pack_file_sha1, 20);
}

char *index_pack_lockfile(int ip_out)
{
char packname[46];

/*
* The first thing we expects from index-pack's output
* is "pack\t%40s\n" or "keep\t%40s\n" (46 bytes) where
* %40s is the newly created pack SHA1 name. In the "keep"
* case, we need it to remove the corresponding .keep file
* later on. If we don't get that then tough luck with it.
*/
if (read_in_full(ip_out, packname, 46) == 46 && packname[45] == '\n' &&
memcmp(packname, "keep\t", 5) == 0) {
char path[PATH_MAX];
packname[45] = 0;
snprintf(path, sizeof(path), "%s/pack/pack-%s.keep",
get_object_directory(), packname + 5);
return xstrdup(path);
}
return NULL;
}
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