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tag: v1.8.1-rc0
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#include "cache.h"
#include "pack.h"
#include "csum-file.h"

void reset_pack_idx_option(struct pack_idx_option *opts)
{
memset(opts, 0, sizeof(*opts));
opts->version = 2;
opts->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);
}

static int cmp_uint32(const void *a_, const void *b_)
{
uint32_t a = *((uint32_t *)a_);
uint32_t b = *((uint32_t *)b_);

return (a < b) ? -1 : (a != b);
}

static int need_large_offset(off_t offset, const struct pack_idx_option *opts)
{
uint32_t ofsval;

if ((offset >> 31) || (opts->off32_limit < offset))
return 1;
if (!opts->anomaly_nr)
return 0;
ofsval = offset;
return !!bsearch(&ofsval, opts->anomaly, opts->anomaly_nr,
sizeof(ofsval), cmp_uint32);
}

/*
* 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.
*/
const char *write_idx_file(const char *index_name, struct pack_idx_entry **objects,
int nr_objects, const struct pack_idx_option *opts,
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;
git_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 (opts->flags & WRITE_IDX_VERIFY) {
assert(index_name);
f = sha1fd_check(index_name);
} else {
if (!index_name) {
static char tmp_file[PATH_MAX];
fd = odb_mkstemp(tmp_file, sizeof(tmp_file), "pack/tmp_idx_XXXXXX");
index_name = xstrdup(tmp_file);
} else {
unlink(index_name);
fd = open(index_name, O_CREAT|O_EXCL|O_WRONLY, 0600);
}
if (fd < 0)
die_errno("unable to create '%s'", index_name);
f = sha1fd(fd, index_name);
}

/* if last object's offset is >= 2^31 we should use index V2 */
index_version = need_large_offset(last_obj_offset, opts) ? 2 : opts->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. */
git_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);
git_SHA1_Update(&ctx, obj->sha1, 20);
if ((opts->flags & WRITE_IDX_STRICT) &&
(i && !hashcmp(list[-2]->sha1, obj->sha1)))
die("The same object %s appears twice in the pack",
sha1_to_hex(obj->sha1));
}

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;

offset = (need_large_offset(obj->offset, opts)
? (0x80000000 | nr_large_offset++)
: obj->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;
uint32_t split[2];

if (!need_large_offset(offset, opts))
continue;
split[0] = htonl(offset >> 32);
split[1] = htonl(offset & 0xffffffff);
sha1write(f, split, 8);
nr_large_offset--;
}
}

sha1write(f, sha1, 20);
sha1close(f, NULL, ((opts->flags & WRITE_IDX_VERIFY)
? CSUM_CLOSE : CSUM_FSYNC));
git_SHA1_Final(sha1, &ctx);
return index_name;
}

off_t write_pack_header(struct sha1file *f, uint32_t nr_entries)
{
struct pack_header hdr;

hdr.hdr_signature = htonl(PACK_SIGNATURE);
hdr.hdr_version = htonl(PACK_VERSION);
hdr.hdr_entries = htonl(nr_entries);
if (sha1write(f, &hdr, sizeof(hdr)))
return 0;
return sizeof(hdr);
}

/*
* Update pack header with object_count and compute new SHA1 for pack data
* associated to pack_fd, and write that SHA1 at the end. That new SHA1
* is also returned in new_pack_sha1.
*
* If partial_pack_sha1 is non null, then the SHA1 of the existing pack
* (without the header update) is computed and validated against the
* one provided in partial_pack_sha1. The validation is performed at
* partial_pack_offset bytes in the pack file. The SHA1 of the remaining
* data (i.e. from partial_pack_offset to the end) is then computed and
* returned in partial_pack_sha1.
*
* Note that new_pack_sha1 is updated last, so both new_pack_sha1 and
* partial_pack_sha1 can refer to the same buffer if the caller is not
* interested in the resulting SHA1 of pack data above partial_pack_offset.
*/
void fixup_pack_header_footer(int pack_fd,
unsigned char *new_pack_sha1,
const char *pack_name,
uint32_t object_count,
unsigned char *partial_pack_sha1,
off_t partial_pack_offset)
{
int aligned_sz, buf_sz = 8 * 1024;
git_SHA_CTX old_sha1_ctx, new_sha1_ctx;
struct pack_header hdr;
char *buf;

git_SHA1_Init(&old_sha1_ctx);
git_SHA1_Init(&new_sha1_ctx);

if (lseek(pack_fd, 0, SEEK_SET) != 0)
die_errno("Failed seeking to start of '%s'", pack_name);
if (read_in_full(pack_fd, &hdr, sizeof(hdr)) != sizeof(hdr))
die_errno("Unable to reread header of '%s'", pack_name);
if (lseek(pack_fd, 0, SEEK_SET) != 0)
die_errno("Failed seeking to start of '%s'", pack_name);
git_SHA1_Update(&old_sha1_ctx, &hdr, sizeof(hdr));
hdr.hdr_entries = htonl(object_count);
git_SHA1_Update(&new_sha1_ctx, &hdr, sizeof(hdr));
write_or_die(pack_fd, &hdr, sizeof(hdr));
partial_pack_offset -= sizeof(hdr);

buf = xmalloc(buf_sz);
aligned_sz = buf_sz - sizeof(hdr);
for (;;) {
ssize_t m, n;
m = (partial_pack_sha1 && partial_pack_offset < aligned_sz) ?
partial_pack_offset : aligned_sz;
n = xread(pack_fd, buf, m);
if (!n)
break;
if (n < 0)
die_errno("Failed to checksum '%s'", pack_name);
git_SHA1_Update(&new_sha1_ctx, buf, n);

aligned_sz -= n;
if (!aligned_sz)
aligned_sz = buf_sz;

if (!partial_pack_sha1)
continue;

git_SHA1_Update(&old_sha1_ctx, buf, n);
partial_pack_offset -= n;
if (partial_pack_offset == 0) {
unsigned char sha1[20];
git_SHA1_Final(sha1, &old_sha1_ctx);
if (hashcmp(sha1, partial_pack_sha1) != 0)
die("Unexpected checksum for %s "
"(disk corruption?)", pack_name);
/*
* Now let's compute the SHA1 of the remainder of the
* pack, which also means making partial_pack_offset
* big enough not to matter anymore.
*/
git_SHA1_Init(&old_sha1_ctx);
partial_pack_offset = ~partial_pack_offset;
partial_pack_offset -= MSB(partial_pack_offset, 1);
}
}
free(buf);

if (partial_pack_sha1)
git_SHA1_Final(partial_pack_sha1, &old_sha1_ctx);
git_SHA1_Final(new_pack_sha1, &new_sha1_ctx);
write_or_die(pack_fd, new_pack_sha1, 20);
fsync_or_die(pack_fd, pack_name);
}

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

/*
* The first thing we expect 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;
}

/*
* The per-object header is a pretty dense thing, which is
* - first byte: low four bits are "size", then three bits of "type",
* and the high bit is "size continues".
* - each byte afterwards: low seven bits are size continuation,
* with the high bit being "size continues"
*/
int encode_in_pack_object_header(enum object_type type, uintmax_t size, unsigned char *hdr)
{
int n = 1;
unsigned char c;

if (type < OBJ_COMMIT || type > OBJ_REF_DELTA)
die("bad type %d", type);

c = (type << 4) | (size & 15);
size >>= 4;
while (size) {
*hdr++ = c | 0x80;
c = size & 0x7f;
size >>= 7;
n++;
}
*hdr = c;
return n;
}

struct sha1file *create_tmp_packfile(char **pack_tmp_name)
{
char tmpname[PATH_MAX];
int fd;

fd = odb_mkstemp(tmpname, sizeof(tmpname), "pack/tmp_pack_XXXXXX");
*pack_tmp_name = xstrdup(tmpname);
return sha1fd(fd, *pack_tmp_name);
}

void finish_tmp_packfile(char *name_buffer,
const char *pack_tmp_name,
struct pack_idx_entry **written_list,
uint32_t nr_written,
struct pack_idx_option *pack_idx_opts,
unsigned char sha1[])
{
const char *idx_tmp_name;
char *end_of_name_prefix = strrchr(name_buffer, 0);

if (adjust_shared_perm(pack_tmp_name))
die_errno("unable to make temporary pack file readable");

idx_tmp_name = write_idx_file(NULL, written_list, nr_written,
pack_idx_opts, sha1);
if (adjust_shared_perm(idx_tmp_name))
die_errno("unable to make temporary index file readable");

sprintf(end_of_name_prefix, "%s.pack", sha1_to_hex(sha1));
free_pack_by_name(name_buffer);

if (rename(pack_tmp_name, name_buffer))
die_errno("unable to rename temporary pack file");

sprintf(end_of_name_prefix, "%s.idx", sha1_to_hex(sha1));
if (rename(idx_tmp_name, name_buffer))
die_errno("unable to rename temporary index file");

free((void *)idx_tmp_name);
}
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