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#include "cache.h"
#include "csum-file.h"
#include "lockfile.h"
#include "object-store.h"
#include "midx.h"
#define MIDX_SIGNATURE 0x4d494458 /* "MIDX" */
#define MIDX_VERSION 1
#define MIDX_BYTE_FILE_VERSION 4
#define MIDX_BYTE_HASH_VERSION 5
#define MIDX_BYTE_NUM_CHUNKS 6
#define MIDX_BYTE_NUM_PACKS 8
#define MIDX_HASH_VERSION 1
#define MIDX_HEADER_SIZE 12
#define MIDX_HASH_LEN 20
#define MIDX_MIN_SIZE (MIDX_HEADER_SIZE + MIDX_HASH_LEN)
static char *get_midx_filename(const char *object_dir)
{
return xstrfmt("%s/pack/multi-pack-index", object_dir);
}
struct multi_pack_index *load_multi_pack_index(const char *object_dir)
{
struct multi_pack_index *m = NULL;
int fd;
struct stat st;
size_t midx_size;
void *midx_map = NULL;
uint32_t hash_version;
char *midx_name = get_midx_filename(object_dir);
fd = git_open(midx_name);
if (fd < 0)
goto cleanup_fail;
if (fstat(fd, &st)) {
error_errno(_("failed to read %s"), midx_name);
goto cleanup_fail;
}
midx_size = xsize_t(st.st_size);
if (midx_size < MIDX_MIN_SIZE) {
error(_("multi-pack-index file %s is too small"), midx_name);
goto cleanup_fail;
}
FREE_AND_NULL(midx_name);
midx_map = xmmap(NULL, midx_size, PROT_READ, MAP_PRIVATE, fd, 0);
FLEX_ALLOC_MEM(m, object_dir, object_dir, strlen(object_dir));
m->fd = fd;
m->data = midx_map;
m->data_len = midx_size;
m->signature = get_be32(m->data);
if (m->signature != MIDX_SIGNATURE) {
error(_("multi-pack-index signature 0x%08x does not match signature 0x%08x"),
m->signature, MIDX_SIGNATURE);
goto cleanup_fail;
}
m->version = m->data[MIDX_BYTE_FILE_VERSION];
if (m->version != MIDX_VERSION) {
error(_("multi-pack-index version %d not recognized"),
m->version);
goto cleanup_fail;
}
hash_version = m->data[MIDX_BYTE_HASH_VERSION];
if (hash_version != MIDX_HASH_VERSION) {
error(_("hash version %u does not match"), hash_version);
goto cleanup_fail;
}
m->hash_len = MIDX_HASH_LEN;
m->num_chunks = m->data[MIDX_BYTE_NUM_CHUNKS];
m->num_packs = get_be32(m->data + MIDX_BYTE_NUM_PACKS);
return m;
cleanup_fail:
free(m);
free(midx_name);
if (midx_map)
munmap(midx_map, midx_size);
if (0 <= fd)
close(fd);
return NULL;
}
static size_t write_midx_header(struct hashfile *f,
unsigned char num_chunks,
uint32_t num_packs)
{
unsigned char byte_values[4];
hashwrite_be32(f, MIDX_SIGNATURE);
byte_values[0] = MIDX_VERSION;
byte_values[1] = MIDX_HASH_VERSION;
byte_values[2] = num_chunks;
byte_values[3] = 0; /* unused */
hashwrite(f, byte_values, sizeof(byte_values));
hashwrite_be32(f, num_packs);
return MIDX_HEADER_SIZE;
}
int write_midx_file(const char *object_dir)
{
unsigned char num_chunks = 0;
char *midx_name;
struct hashfile *f = NULL;
struct lock_file lk;
midx_name = get_midx_filename(object_dir);
if (safe_create_leading_directories(midx_name)) {
UNLEAK(midx_name);
die_errno(_("unable to create leading directories of %s"),
midx_name);
}
hold_lock_file_for_update(&lk, midx_name, LOCK_DIE_ON_ERROR);
f = hashfd(lk.tempfile->fd, lk.tempfile->filename.buf);
FREE_AND_NULL(midx_name);
write_midx_header(f, num_chunks, 0);
finalize_hashfile(f, NULL, CSUM_FSYNC | CSUM_HASH_IN_STREAM);
commit_lock_file(&lk);
return 0;
}
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