mirror of
https://github.com/git/git
synced 2024-08-25 10:45:59 +00:00
![Taylor Blau](/assets/img/avatar_default.png)
This patch prepares for callers to be able to write reverse index files to disk. It adds the necessary machinery to write a format-compliant .rev file from within 'write_rev_file()', which is called from 'finish_tmp_packfile()'. Similar to the process by which the reverse index is computed in memory, these new paths also have to sort a list of objects by their offsets within a packfile. These new paths use a qsort() (as opposed to a radix sort), since our specialized radix sort requires a full revindex_entry struct per object, which is more memory than we need to allocate. The qsort is obviously slower, but the theoretical slowdown would require a repository with a large amount of objects, likely implying that the time spent in, say, pack-objects during a repack would dominate the overall runtime. Signed-off-by: Taylor Blau <me@ttaylorr.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
504 lines
14 KiB
C
504 lines
14 KiB
C
#include "cache.h"
|
|
#include "pack.h"
|
|
#include "csum-file.h"
|
|
#include "remote.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 oidcmp(&a->oid, &b->oid);
|
|
}
|
|
|
|
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);
|
|
}
|
|
|
|
/*
|
|
* The *sha1 contains the pack content SHA1 hash.
|
|
* 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,
|
|
const unsigned char *sha1)
|
|
{
|
|
struct hashfile *f;
|
|
struct pack_idx_entry **sorted_by_sha, **list, **last;
|
|
off_t last_obj_offset = 0;
|
|
int i, fd;
|
|
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, sha1_compare);
|
|
}
|
|
else
|
|
sorted_by_sha = list = last = NULL;
|
|
|
|
if (opts->flags & WRITE_IDX_VERIFY) {
|
|
assert(index_name);
|
|
f = hashfd_check(index_name);
|
|
} else {
|
|
if (!index_name) {
|
|
struct strbuf tmp_file = STRBUF_INIT;
|
|
fd = odb_mkstemp(&tmp_file, "pack/tmp_idx_XXXXXX");
|
|
index_name = strbuf_detach(&tmp_file, NULL);
|
|
} 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 = hashfd(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);
|
|
hashwrite(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->oid.hash[0] != i)
|
|
break;
|
|
next++;
|
|
}
|
|
hashwrite_be32(f, next - sorted_by_sha);
|
|
list = next;
|
|
}
|
|
|
|
/*
|
|
* 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)
|
|
hashwrite_be32(f, obj->offset);
|
|
hashwrite(f, obj->oid.hash, the_hash_algo->rawsz);
|
|
if ((opts->flags & WRITE_IDX_STRICT) &&
|
|
(i && oideq(&list[-2]->oid, &obj->oid)))
|
|
die("The same object %s appears twice in the pack",
|
|
oid_to_hex(&obj->oid));
|
|
}
|
|
|
|
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++;
|
|
hashwrite_be32(f, obj->crc32);
|
|
}
|
|
|
|
/* 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);
|
|
hashwrite_be32(f, offset);
|
|
}
|
|
|
|
/* 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 (!need_large_offset(offset, opts))
|
|
continue;
|
|
hashwrite_be64(f, offset);
|
|
nr_large_offset--;
|
|
}
|
|
}
|
|
|
|
hashwrite(f, sha1, the_hash_algo->rawsz);
|
|
finalize_hashfile(f, NULL, CSUM_HASH_IN_STREAM | CSUM_CLOSE |
|
|
((opts->flags & WRITE_IDX_VERIFY)
|
|
? 0 : CSUM_FSYNC));
|
|
return index_name;
|
|
}
|
|
|
|
static int pack_order_cmp(const void *va, const void *vb, void *ctx)
|
|
{
|
|
struct pack_idx_entry **objects = ctx;
|
|
|
|
off_t oa = objects[*(uint32_t*)va]->offset;
|
|
off_t ob = objects[*(uint32_t*)vb]->offset;
|
|
|
|
if (oa < ob)
|
|
return -1;
|
|
if (oa > ob)
|
|
return 1;
|
|
return 0;
|
|
}
|
|
|
|
static void write_rev_header(struct hashfile *f)
|
|
{
|
|
uint32_t oid_version;
|
|
switch (hash_algo_by_ptr(the_hash_algo)) {
|
|
case GIT_HASH_SHA1:
|
|
oid_version = 1;
|
|
break;
|
|
case GIT_HASH_SHA256:
|
|
oid_version = 2;
|
|
break;
|
|
default:
|
|
die("write_rev_header: unknown hash version");
|
|
}
|
|
|
|
hashwrite_be32(f, RIDX_SIGNATURE);
|
|
hashwrite_be32(f, RIDX_VERSION);
|
|
hashwrite_be32(f, oid_version);
|
|
}
|
|
|
|
static void write_rev_index_positions(struct hashfile *f,
|
|
struct pack_idx_entry **objects,
|
|
uint32_t nr_objects)
|
|
{
|
|
uint32_t *pack_order;
|
|
uint32_t i;
|
|
|
|
ALLOC_ARRAY(pack_order, nr_objects);
|
|
for (i = 0; i < nr_objects; i++)
|
|
pack_order[i] = i;
|
|
QSORT_S(pack_order, nr_objects, pack_order_cmp, objects);
|
|
|
|
for (i = 0; i < nr_objects; i++)
|
|
hashwrite_be32(f, pack_order[i]);
|
|
|
|
free(pack_order);
|
|
}
|
|
|
|
static void write_rev_trailer(struct hashfile *f, const unsigned char *hash)
|
|
{
|
|
hashwrite(f, hash, the_hash_algo->rawsz);
|
|
}
|
|
|
|
const char *write_rev_file(const char *rev_name,
|
|
struct pack_idx_entry **objects,
|
|
uint32_t nr_objects,
|
|
const unsigned char *hash,
|
|
unsigned flags)
|
|
{
|
|
struct hashfile *f;
|
|
int fd;
|
|
|
|
if ((flags & WRITE_REV) && (flags & WRITE_REV_VERIFY))
|
|
die(_("cannot both write and verify reverse index"));
|
|
|
|
if (flags & WRITE_REV) {
|
|
if (!rev_name) {
|
|
struct strbuf tmp_file = STRBUF_INIT;
|
|
fd = odb_mkstemp(&tmp_file, "pack/tmp_rev_XXXXXX");
|
|
rev_name = strbuf_detach(&tmp_file, NULL);
|
|
} else {
|
|
unlink(rev_name);
|
|
fd = open(rev_name, O_CREAT|O_EXCL|O_WRONLY, 0600);
|
|
if (fd < 0)
|
|
die_errno("unable to create '%s'", rev_name);
|
|
}
|
|
f = hashfd(fd, rev_name);
|
|
} else if (flags & WRITE_REV_VERIFY) {
|
|
struct stat statbuf;
|
|
if (stat(rev_name, &statbuf)) {
|
|
if (errno == ENOENT) {
|
|
/* .rev files are optional */
|
|
return NULL;
|
|
} else
|
|
die_errno(_("could not stat: %s"), rev_name);
|
|
}
|
|
f = hashfd_check(rev_name);
|
|
} else
|
|
return NULL;
|
|
|
|
write_rev_header(f);
|
|
|
|
write_rev_index_positions(f, objects, nr_objects);
|
|
write_rev_trailer(f, hash);
|
|
|
|
if (rev_name && adjust_shared_perm(rev_name) < 0)
|
|
die(_("failed to make %s readable"), rev_name);
|
|
|
|
finalize_hashfile(f, NULL, CSUM_HASH_IN_STREAM | CSUM_CLOSE |
|
|
((flags & WRITE_IDX_VERIFY) ? 0 : CSUM_FSYNC));
|
|
|
|
return rev_name;
|
|
}
|
|
|
|
off_t write_pack_header(struct hashfile *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);
|
|
hashwrite(f, &hdr, sizeof(hdr));
|
|
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_hash,
|
|
const char *pack_name,
|
|
uint32_t object_count,
|
|
unsigned char *partial_pack_hash,
|
|
off_t partial_pack_offset)
|
|
{
|
|
int aligned_sz, buf_sz = 8 * 1024;
|
|
git_hash_ctx old_hash_ctx, new_hash_ctx;
|
|
struct pack_header hdr;
|
|
char *buf;
|
|
ssize_t read_result;
|
|
|
|
the_hash_algo->init_fn(&old_hash_ctx);
|
|
the_hash_algo->init_fn(&new_hash_ctx);
|
|
|
|
if (lseek(pack_fd, 0, SEEK_SET) != 0)
|
|
die_errno("Failed seeking to start of '%s'", pack_name);
|
|
read_result = read_in_full(pack_fd, &hdr, sizeof(hdr));
|
|
if (read_result < 0)
|
|
die_errno("Unable to reread header of '%s'", pack_name);
|
|
else if (read_result != sizeof(hdr))
|
|
die_errno("Unexpected short read for header of '%s'",
|
|
pack_name);
|
|
if (lseek(pack_fd, 0, SEEK_SET) != 0)
|
|
die_errno("Failed seeking to start of '%s'", pack_name);
|
|
the_hash_algo->update_fn(&old_hash_ctx, &hdr, sizeof(hdr));
|
|
hdr.hdr_entries = htonl(object_count);
|
|
the_hash_algo->update_fn(&new_hash_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_hash && 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);
|
|
the_hash_algo->update_fn(&new_hash_ctx, buf, n);
|
|
|
|
aligned_sz -= n;
|
|
if (!aligned_sz)
|
|
aligned_sz = buf_sz;
|
|
|
|
if (!partial_pack_hash)
|
|
continue;
|
|
|
|
the_hash_algo->update_fn(&old_hash_ctx, buf, n);
|
|
partial_pack_offset -= n;
|
|
if (partial_pack_offset == 0) {
|
|
unsigned char hash[GIT_MAX_RAWSZ];
|
|
the_hash_algo->final_fn(hash, &old_hash_ctx);
|
|
if (!hasheq(hash, partial_pack_hash))
|
|
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.
|
|
*/
|
|
the_hash_algo->init_fn(&old_hash_ctx);
|
|
partial_pack_offset = ~partial_pack_offset;
|
|
partial_pack_offset -= MSB(partial_pack_offset, 1);
|
|
}
|
|
}
|
|
free(buf);
|
|
|
|
if (partial_pack_hash)
|
|
the_hash_algo->final_fn(partial_pack_hash, &old_hash_ctx);
|
|
the_hash_algo->final_fn(new_pack_hash, &new_hash_ctx);
|
|
write_or_die(pack_fd, new_pack_hash, the_hash_algo->rawsz);
|
|
fsync_or_die(pack_fd, pack_name);
|
|
}
|
|
|
|
char *index_pack_lockfile(int ip_out)
|
|
{
|
|
char packname[GIT_MAX_HEXSZ + 6];
|
|
const int len = the_hash_algo->hexsz + 6;
|
|
|
|
/*
|
|
* 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, len) == len && packname[len-1] == '\n') {
|
|
const char *name;
|
|
packname[len-1] = 0;
|
|
if (skip_prefix(packname, "keep\t", &name))
|
|
return xstrfmt("%s/pack/pack-%s.keep",
|
|
get_object_directory(), name);
|
|
}
|
|
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(unsigned char *hdr, int hdr_len,
|
|
enum object_type type, uintmax_t size)
|
|
{
|
|
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) {
|
|
if (n == hdr_len)
|
|
die("object size is too enormous to format");
|
|
*hdr++ = c | 0x80;
|
|
c = size & 0x7f;
|
|
size >>= 7;
|
|
n++;
|
|
}
|
|
*hdr = c;
|
|
return n;
|
|
}
|
|
|
|
struct hashfile *create_tmp_packfile(char **pack_tmp_name)
|
|
{
|
|
struct strbuf tmpname = STRBUF_INIT;
|
|
int fd;
|
|
|
|
fd = odb_mkstemp(&tmpname, "pack/tmp_pack_XXXXXX");
|
|
*pack_tmp_name = strbuf_detach(&tmpname, NULL);
|
|
return hashfd(fd, *pack_tmp_name);
|
|
}
|
|
|
|
void finish_tmp_packfile(struct strbuf *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 hash[])
|
|
{
|
|
const char *idx_tmp_name, *rev_tmp_name = NULL;
|
|
int basename_len = name_buffer->len;
|
|
|
|
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, hash);
|
|
if (adjust_shared_perm(idx_tmp_name))
|
|
die_errno("unable to make temporary index file readable");
|
|
|
|
rev_tmp_name = write_rev_file(NULL, written_list, nr_written, hash,
|
|
pack_idx_opts->flags);
|
|
|
|
strbuf_addf(name_buffer, "%s.pack", hash_to_hex(hash));
|
|
|
|
if (rename(pack_tmp_name, name_buffer->buf))
|
|
die_errno("unable to rename temporary pack file");
|
|
|
|
strbuf_setlen(name_buffer, basename_len);
|
|
|
|
strbuf_addf(name_buffer, "%s.idx", hash_to_hex(hash));
|
|
if (rename(idx_tmp_name, name_buffer->buf))
|
|
die_errno("unable to rename temporary index file");
|
|
|
|
strbuf_setlen(name_buffer, basename_len);
|
|
|
|
if (rev_tmp_name) {
|
|
strbuf_addf(name_buffer, "%s.rev", hash_to_hex(hash));
|
|
if (rename(rev_tmp_name, name_buffer->buf))
|
|
die_errno("unable to rename temporary reverse-index file");
|
|
}
|
|
|
|
strbuf_setlen(name_buffer, basename_len);
|
|
|
|
free((void *)idx_tmp_name);
|
|
}
|
|
|
|
void write_promisor_file(const char *promisor_name, struct ref **sought, int nr_sought)
|
|
{
|
|
int i, err;
|
|
FILE *output = xfopen(promisor_name, "w");
|
|
|
|
for (i = 0; i < nr_sought; i++)
|
|
fprintf(output, "%s %s\n", oid_to_hex(&sought[i]->old_oid),
|
|
sought[i]->name);
|
|
|
|
err = ferror(output);
|
|
err |= fclose(output);
|
|
if (err)
|
|
die(_("could not write '%s' promisor file"), promisor_name);
|
|
}
|