mirror of
https://github.com/git/git.git
synced 2024-11-24 10:26:17 +08:00
c38138cd78
We want to be able to check their integrity later, and putting the sha1-sum of the contents at the end is a good thing. The writing routines are generic, so we could try to re-use them for the index file, instead of having the same logic duplicated. Update unpack-objects to know about the extra 20 bytes at the end of the index.
400 lines
9.6 KiB
C
400 lines
9.6 KiB
C
#include <ctype.h>
|
|
#include "cache.h"
|
|
#include "object.h"
|
|
#include "delta.h"
|
|
#include "csum-file.h"
|
|
|
|
static const char pack_usage[] = "git-pack-objects [--window=N] [--depth=N] base-name < object-list";
|
|
|
|
enum object_type {
|
|
OBJ_NONE,
|
|
OBJ_COMMIT,
|
|
OBJ_TREE,
|
|
OBJ_BLOB,
|
|
OBJ_DELTA // NOTE! This is _not_ the same as a "delta" object in the filesystem
|
|
};
|
|
|
|
struct object_entry {
|
|
unsigned char sha1[20];
|
|
unsigned long size;
|
|
unsigned long offset;
|
|
unsigned int depth;
|
|
unsigned int hash;
|
|
enum object_type type;
|
|
unsigned long delta_size;
|
|
struct object_entry *delta;
|
|
};
|
|
|
|
static struct object_entry **sorted_by_sha, **sorted_by_type;
|
|
static struct object_entry *objects = NULL;
|
|
static int nr_objects = 0, nr_alloc = 0;
|
|
static const char *base_name;
|
|
|
|
static void *delta_against(void *buf, unsigned long size, struct object_entry *entry)
|
|
{
|
|
unsigned long othersize, delta_size;
|
|
char type[10];
|
|
void *otherbuf = read_sha1_file(entry->delta->sha1, type, &othersize);
|
|
void *delta_buf;
|
|
|
|
if (!otherbuf)
|
|
die("unable to read %s", sha1_to_hex(entry->delta->sha1));
|
|
delta_buf = diff_delta(otherbuf, othersize,
|
|
buf, size, &delta_size, ~0UL);
|
|
if (!delta_buf || delta_size != entry->delta_size)
|
|
die("delta size changed");
|
|
free(buf);
|
|
free(otherbuf);
|
|
return delta_buf;
|
|
}
|
|
|
|
static unsigned long write_object(struct sha1file *f, struct object_entry *entry)
|
|
{
|
|
unsigned long size;
|
|
char type[10];
|
|
void *buf = read_sha1_file(entry->sha1, type, &size);
|
|
char header[25];
|
|
unsigned hdrlen, datalen;
|
|
|
|
if (!buf)
|
|
die("unable to read %s", sha1_to_hex(entry->sha1));
|
|
if (size != entry->size)
|
|
die("object %s size inconsistency (%lu vs %lu)", sha1_to_hex(entry->sha1), size, entry->size);
|
|
|
|
/*
|
|
* The object header is a byte of 'type' followed by four bytes of
|
|
* length, except for deltas that has the 20 bytes of delta sha
|
|
* instead.
|
|
*/
|
|
header[0] = ".CTB"[entry->type];
|
|
hdrlen = 5;
|
|
if (entry->delta) {
|
|
header[0] = 'D';
|
|
memcpy(header+5, entry->delta, 20);
|
|
buf = delta_against(buf, size, entry);
|
|
size = entry->delta_size;
|
|
hdrlen = 25;
|
|
}
|
|
datalen = htonl(size);
|
|
memcpy(header+1, &datalen, 4);
|
|
sha1write(f, header, hdrlen);
|
|
datalen = sha1write_compressed(f, buf, size);
|
|
free(buf);
|
|
return hdrlen + datalen;
|
|
}
|
|
|
|
static void write_pack_file(void)
|
|
{
|
|
int i;
|
|
struct sha1file *f = sha1create("%s.%s", base_name, "pack");
|
|
unsigned long offset = 0;
|
|
unsigned long mb;
|
|
|
|
for (i = 0; i < nr_objects; i++) {
|
|
struct object_entry *entry = objects + i;
|
|
entry->offset = offset;
|
|
offset += write_object(f, entry);
|
|
}
|
|
sha1close(f);
|
|
mb = offset >> 20;
|
|
offset &= 0xfffff;
|
|
}
|
|
|
|
static void write_index_file(void)
|
|
{
|
|
int i;
|
|
struct sha1file *f = sha1create("%s.%s", base_name, "idx");
|
|
struct object_entry **list = sorted_by_sha;
|
|
struct object_entry **last = list + nr_objects;
|
|
unsigned int array[256];
|
|
|
|
/*
|
|
* 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 object_entry **next = list;
|
|
while (next < last) {
|
|
struct object_entry *entry = *next;
|
|
if (entry->sha1[0] != i)
|
|
break;
|
|
next++;
|
|
}
|
|
array[i] = htonl(next - sorted_by_sha);
|
|
list = next;
|
|
}
|
|
sha1write(f, array, 256 * sizeof(int));
|
|
|
|
/*
|
|
* Write the actual SHA1 entries..
|
|
*/
|
|
list = sorted_by_sha;
|
|
for (i = 0; i < nr_objects; i++) {
|
|
struct object_entry *entry = *list++;
|
|
unsigned int offset = htonl(entry->offset);
|
|
sha1write(f, &offset, 4);
|
|
sha1write(f, entry->sha1, 20);
|
|
}
|
|
sha1close(f);
|
|
}
|
|
|
|
static void add_object_entry(unsigned char *sha1, unsigned int hash)
|
|
{
|
|
unsigned int idx = nr_objects;
|
|
struct object_entry *entry;
|
|
|
|
if (idx >= nr_alloc) {
|
|
unsigned int needed = (idx + 1024) * 3 / 2;
|
|
objects = xrealloc(objects, needed * sizeof(*entry));
|
|
nr_alloc = needed;
|
|
}
|
|
entry = objects + idx;
|
|
memset(entry, 0, sizeof(*entry));
|
|
memcpy(entry->sha1, sha1, 20);
|
|
entry->hash = hash;
|
|
nr_objects = idx+1;
|
|
}
|
|
|
|
static void check_object(struct object_entry *entry)
|
|
{
|
|
char buffer[128];
|
|
char type[10];
|
|
unsigned long mapsize;
|
|
z_stream stream;
|
|
void *map;
|
|
|
|
map = map_sha1_file(entry->sha1, &mapsize);
|
|
if (!map)
|
|
die("unable to map %s", sha1_to_hex(entry->sha1));
|
|
if (unpack_sha1_header(&stream, map, mapsize, buffer, sizeof(buffer)) < 0)
|
|
die("unable to unpack %s header", sha1_to_hex(entry->sha1));
|
|
munmap(map, mapsize);
|
|
if (parse_sha1_header(buffer, type, &entry->size) < 0)
|
|
die("unable to parse %s header", sha1_to_hex(entry->sha1));
|
|
if (!strcmp(type, "commit")) {
|
|
entry->type = OBJ_COMMIT;
|
|
} else if (!strcmp(type, "tree")) {
|
|
entry->type = OBJ_TREE;
|
|
} else if (!strcmp(type, "blob")) {
|
|
entry->type = OBJ_BLOB;
|
|
} else
|
|
die("unable to pack object %s of type %s", sha1_to_hex(entry->sha1), type);
|
|
}
|
|
|
|
static void get_object_details(void)
|
|
{
|
|
int i;
|
|
struct object_entry *entry = objects;
|
|
|
|
for (i = 0; i < nr_objects; i++)
|
|
check_object(entry++);
|
|
}
|
|
|
|
typedef int (*entry_sort_t)(const struct object_entry *, const struct object_entry *);
|
|
|
|
static entry_sort_t current_sort;
|
|
|
|
static int sort_comparator(const void *_a, const void *_b)
|
|
{
|
|
struct object_entry *a = *(struct object_entry **)_a;
|
|
struct object_entry *b = *(struct object_entry **)_b;
|
|
return current_sort(a,b);
|
|
}
|
|
|
|
static struct object_entry **create_sorted_list(entry_sort_t sort)
|
|
{
|
|
struct object_entry **list = xmalloc(nr_objects * sizeof(struct object_entry *));
|
|
int i;
|
|
|
|
for (i = 0; i < nr_objects; i++)
|
|
list[i] = objects + i;
|
|
current_sort = sort;
|
|
qsort(list, nr_objects, sizeof(struct object_entry *), sort_comparator);
|
|
return list;
|
|
}
|
|
|
|
static int sha1_sort(const struct object_entry *a, const struct object_entry *b)
|
|
{
|
|
return memcmp(a->sha1, b->sha1, 20);
|
|
}
|
|
|
|
static int type_size_sort(const struct object_entry *a, const struct object_entry *b)
|
|
{
|
|
if (a->type < b->type)
|
|
return -1;
|
|
if (a->type > b->type)
|
|
return 1;
|
|
if (a->hash < b->hash)
|
|
return -1;
|
|
if (a->hash > b->hash)
|
|
return 1;
|
|
if (a->size < b->size)
|
|
return -1;
|
|
if (a->size > b->size)
|
|
return 1;
|
|
return a < b ? -1 : (a > b);
|
|
}
|
|
|
|
struct unpacked {
|
|
struct object_entry *entry;
|
|
void *data;
|
|
};
|
|
|
|
/*
|
|
* We search for deltas _backwards_ in a list sorted by type and
|
|
* by size, so that we see progressively smaller and smaller files.
|
|
* That's because we prefer deltas to be from the bigger file
|
|
* to the smaller - deletes are potentially cheaper, but perhaps
|
|
* more importantly, the bigger file is likely the more recent
|
|
* one.
|
|
*/
|
|
static int try_delta(struct unpacked *cur, struct unpacked *old, unsigned max_depth)
|
|
{
|
|
struct object_entry *cur_entry = cur->entry;
|
|
struct object_entry *old_entry = old->entry;
|
|
unsigned long size, oldsize, delta_size, sizediff;
|
|
long max_size;
|
|
void *delta_buf;
|
|
|
|
/* Don't bother doing diffs between different types */
|
|
if (cur_entry->type != old_entry->type)
|
|
return -1;
|
|
|
|
size = cur_entry->size;
|
|
if (size < 50)
|
|
return -1;
|
|
oldsize = old_entry->size;
|
|
sizediff = oldsize > size ? oldsize - size : size - oldsize;
|
|
if (sizediff > size / 8)
|
|
return -1;
|
|
if (old_entry->depth >= max_depth)
|
|
return 0;
|
|
|
|
/*
|
|
* NOTE!
|
|
*
|
|
* We always delta from the bigger to the smaller, since that's
|
|
* more space-efficient (deletes don't have to say _what_ they
|
|
* delete).
|
|
*/
|
|
max_size = size / 2 - 20;
|
|
if (cur_entry->delta)
|
|
max_size = cur_entry->delta_size-1;
|
|
if (sizediff >= max_size)
|
|
return -1;
|
|
delta_buf = diff_delta(old->data, oldsize,
|
|
cur->data, size, &delta_size, max_size);
|
|
if (!delta_buf)
|
|
return 0;
|
|
cur_entry->delta = old_entry;
|
|
cur_entry->delta_size = delta_size;
|
|
cur_entry->depth = old_entry->depth + 1;
|
|
free(delta_buf);
|
|
return 0;
|
|
}
|
|
|
|
static void find_deltas(struct object_entry **list, int window, int depth)
|
|
{
|
|
int i, idx;
|
|
unsigned int array_size = window * sizeof(struct unpacked);
|
|
struct unpacked *array = xmalloc(array_size);
|
|
|
|
memset(array, 0, array_size);
|
|
i = nr_objects;
|
|
idx = 0;
|
|
while (--i >= 0) {
|
|
struct object_entry *entry = list[i];
|
|
struct unpacked *n = array + idx;
|
|
unsigned long size;
|
|
char type[10];
|
|
int j;
|
|
|
|
free(n->data);
|
|
n->entry = entry;
|
|
n->data = read_sha1_file(entry->sha1, type, &size);
|
|
if (size != entry->size)
|
|
die("object %s inconsistent object length (%lu vs %lu)", sha1_to_hex(entry->sha1), size, entry->size);
|
|
j = window;
|
|
while (--j > 0) {
|
|
unsigned int other_idx = idx + j;
|
|
struct unpacked *m;
|
|
if (other_idx >= window)
|
|
other_idx -= window;
|
|
m = array + other_idx;
|
|
if (!m->entry)
|
|
break;
|
|
if (try_delta(n, m, depth) < 0)
|
|
break;
|
|
}
|
|
idx++;
|
|
if (idx >= window)
|
|
idx = 0;
|
|
}
|
|
}
|
|
|
|
int main(int argc, char **argv)
|
|
{
|
|
char line[PATH_MAX + 20];
|
|
int window = 10, depth = 10;
|
|
int i;
|
|
|
|
for (i = 1; i < argc; i++) {
|
|
const char *arg = argv[i];
|
|
|
|
if (*arg == '-') {
|
|
if (!strncmp("--window=", arg, 9)) {
|
|
char *end;
|
|
window = strtoul(arg+9, &end, 0);
|
|
if (!arg[9] || *end)
|
|
usage(pack_usage);
|
|
continue;
|
|
}
|
|
if (!strncmp("--depth=", arg, 8)) {
|
|
char *end;
|
|
depth = strtoul(arg+8, &end, 0);
|
|
if (!arg[8] || *end)
|
|
usage(pack_usage);
|
|
continue;
|
|
}
|
|
usage(pack_usage);
|
|
}
|
|
if (base_name)
|
|
usage(pack_usage);
|
|
base_name = arg;
|
|
}
|
|
|
|
if (!base_name)
|
|
usage(pack_usage);
|
|
|
|
while (fgets(line, sizeof(line), stdin) != NULL) {
|
|
unsigned int hash;
|
|
char *p;
|
|
unsigned char sha1[20];
|
|
|
|
if (get_sha1_hex(line, sha1))
|
|
die("expected sha1, got garbage");
|
|
hash = 0;
|
|
p = line+40;
|
|
while (*p) {
|
|
unsigned char c = *p++;
|
|
if (isspace(c))
|
|
continue;
|
|
hash = hash * 11 + c;
|
|
}
|
|
add_object_entry(sha1, hash);
|
|
}
|
|
get_object_details();
|
|
|
|
printf("Packing %d objects\n", nr_objects);
|
|
|
|
sorted_by_sha = create_sorted_list(sha1_sort);
|
|
sorted_by_type = create_sorted_list(type_size_sort);
|
|
if (window && depth)
|
|
find_deltas(sorted_by_type, window+1, depth);
|
|
|
|
write_pack_file();
|
|
write_index_file();
|
|
return 0;
|
|
}
|