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git/pack-write.c

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#define USE_THE_REPOSITORY_VARIABLE
#include "git-compat-util.h"
#include "environment.h"
#include "gettext.h"
#include "hex.h"
#include "pack.h"
#include "csum-file.h"
#include "remote.h"
#include "chunk-format.h"
#include "pack-mtimes.h"
#include "pack-objects.h"
#include "pack-revindex.h"
#include "path.h"
#include "strbuf.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 = xopen(index_name, O_CREAT|O_EXCL|O_WRONLY, 0600);
}
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, FSYNC_COMPONENT_PACK_METADATA,
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)
{
hashwrite_be32(f, RIDX_SIGNATURE);
hashwrite_be32(f, RIDX_VERSION);
hashwrite_be32(f, oid_version(the_hash_algo));
}
static void write_rev_index_positions(struct hashfile *f,
uint32_t *pack_order,
uint32_t nr_objects)
{
uint32_t i;
for (i = 0; i < nr_objects; i++)
hashwrite_be32(f, pack_order[i]);
}
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)
{
uint32_t *pack_order;
uint32_t i;
const char *ret;
if (!(flags & WRITE_REV) && !(flags & WRITE_REV_VERIFY))
return NULL;
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);
ret = write_rev_file_order(rev_name, pack_order, nr_objects, hash,
flags);
free(pack_order);
return ret;
}
const char *write_rev_file_order(const char *rev_name,
uint32_t *pack_order,
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 = xopen(rev_name, O_CREAT|O_EXCL|O_WRONLY, 0600);
}
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, pack_order, 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, FSYNC_COMPONENT_PACK_METADATA,
CSUM_HASH_IN_STREAM | CSUM_CLOSE |
((flags & WRITE_IDX_VERIFY) ? 0 : CSUM_FSYNC));
return rev_name;
}
static void write_mtimes_header(struct hashfile *f)
{
hashwrite_be32(f, MTIMES_SIGNATURE);
hashwrite_be32(f, MTIMES_VERSION);
hashwrite_be32(f, oid_version(the_hash_algo));
}
/*
* Writes the object mtimes of "objects" for use in a .mtimes file.
* Note that objects must be in lexicographic (index) order, which is
* the expected ordering of these values in the .mtimes file.
*/
static void write_mtimes_objects(struct hashfile *f,
struct packing_data *to_pack,
struct pack_idx_entry **objects,
uint32_t nr_objects)
{
uint32_t i;
for (i = 0; i < nr_objects; i++) {
struct object_entry *e = (struct object_entry*)objects[i];
hashwrite_be32(f, oe_cruft_mtime(to_pack, e));
}
}
static void write_mtimes_trailer(struct hashfile *f, const unsigned char *hash)
{
hashwrite(f, hash, the_hash_algo->rawsz);
}
static char *write_mtimes_file(struct packing_data *to_pack,
struct pack_idx_entry **objects,
uint32_t nr_objects,
const unsigned char *hash)
{
struct strbuf tmp_file = STRBUF_INIT;
char *mtimes_name;
struct hashfile *f;
int fd;
if (!to_pack)
BUG("cannot call write_mtimes_file with NULL packing_data");
fd = odb_mkstemp(&tmp_file, "pack/tmp_mtimes_XXXXXX");
mtimes_name = strbuf_detach(&tmp_file, NULL);
f = hashfd(fd, mtimes_name);
write_mtimes_header(f);
write_mtimes_objects(f, to_pack, objects, nr_objects);
write_mtimes_trailer(f, hash);
if (adjust_shared_perm(mtimes_name) < 0)
die(_("failed to make %s readable"), mtimes_name);
finalize_hashfile(f, NULL, FSYNC_COMPONENT_PACK_METADATA,
CSUM_HASH_IN_STREAM | CSUM_CLOSE | CSUM_FSYNC);
return mtimes_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,
the_repository->hash_algo))
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_component_or_die(FSYNC_COMPONENT_PACK, pack_fd, pack_name);
}
char *index_pack_lockfile(int ip_out, int *is_well_formed)
{
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;
if (is_well_formed)
*is_well_formed = 1;
packname[len-1] = 0;
if (skip_prefix(packname, "keep\t", &name))
return xstrfmt("%s/pack/pack-%s.keep",
get_object_directory(), name);
return NULL;
}
if (is_well_formed)
*is_well_formed = 0;
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);
}
static void rename_tmp_packfile(struct strbuf *name_prefix, const char *source,
const char *ext)
{
size_t name_prefix_len = name_prefix->len;
strbuf_addstr(name_prefix, ext);
if (rename(source, name_prefix->buf))
die_errno("unable to rename temporary file to '%s'",
name_prefix->buf);
strbuf_setlen(name_prefix, name_prefix_len);
}
void rename_tmp_packfile_idx(struct strbuf *name_buffer,
char **idx_tmp_name)
{
rename_tmp_packfile(name_buffer, *idx_tmp_name, "idx");
}
void stage_tmp_packfiles(struct strbuf *name_buffer,
const char *pack_tmp_name,
struct pack_idx_entry **written_list,
uint32_t nr_written,
struct packing_data *to_pack,
struct pack_idx_option *pack_idx_opts,
unsigned char hash[],
char **idx_tmp_name)
{
const char *rev_tmp_name = NULL;
char *mtimes_tmp_name = NULL;
if (adjust_shared_perm(pack_tmp_name))
die_errno("unable to make temporary pack file readable");
*idx_tmp_name = (char *)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);
if (pack_idx_opts->flags & WRITE_MTIMES) {
mtimes_tmp_name = write_mtimes_file(to_pack, written_list,
nr_written,
hash);
}
rename_tmp_packfile(name_buffer, pack_tmp_name, "pack");
if (rev_tmp_name)
rename_tmp_packfile(name_buffer, rev_tmp_name, "rev");
if (mtimes_tmp_name)
rename_tmp_packfile(name_buffer, mtimes_tmp_name, "mtimes");
free((char *)rev_tmp_name);
free(mtimes_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);
}
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