mirror of
https://github.com/git/git
synced 2024-08-28 12:09:19 +00:00
![Linus Torvalds](/assets/img/avatar_default.png)
This makes it match the new delta encoding, and admittedly makes the code easier to follow. This also updates the PACK file version to 2, since this (and the delta encoding change in the previous commit) are incompatible with the old format.
288 lines
6.1 KiB
C
288 lines
6.1 KiB
C
#include "cache.h"
|
|
#include "object.h"
|
|
#include "delta.h"
|
|
#include "pack.h"
|
|
|
|
static int dry_run;
|
|
static const char unpack_usage[] = "git-unpack-objects < pack-file";
|
|
|
|
/* We always read in 4kB chunks. */
|
|
static unsigned char buffer[4096];
|
|
static unsigned long offset, len, eof;
|
|
static SHA_CTX ctx;
|
|
|
|
/*
|
|
* Make sure at least "min" bytes are available in the buffer, and
|
|
* return the pointer to the buffer.
|
|
*/
|
|
static void * fill(int min)
|
|
{
|
|
if (min <= len)
|
|
return buffer + offset;
|
|
if (eof)
|
|
die("unable to fill input");
|
|
if (min > sizeof(buffer))
|
|
die("cannot fill %d bytes", min);
|
|
if (offset) {
|
|
SHA1_Update(&ctx, buffer, offset);
|
|
memcpy(buffer, buffer + offset, len);
|
|
offset = 0;
|
|
}
|
|
do {
|
|
int ret = read(0, buffer + len, sizeof(buffer) - len);
|
|
if (ret <= 0) {
|
|
if (!ret)
|
|
die("early EOF");
|
|
if (errno == EAGAIN || errno == EINTR)
|
|
continue;
|
|
die("read error on input: %s", strerror(errno));
|
|
}
|
|
len += ret;
|
|
} while (len < min);
|
|
return buffer;
|
|
}
|
|
|
|
static void use(int bytes)
|
|
{
|
|
if (bytes > len)
|
|
die("used more bytes than were available");
|
|
len -= bytes;
|
|
offset += bytes;
|
|
}
|
|
|
|
static void *get_data(unsigned long size)
|
|
{
|
|
z_stream stream;
|
|
void *buf = xmalloc(size);
|
|
|
|
if (!size)
|
|
return buf;
|
|
memset(&stream, 0, sizeof(stream));
|
|
|
|
stream.next_out = buf;
|
|
stream.avail_out = size;
|
|
stream.next_in = fill(1);
|
|
stream.avail_in = len;
|
|
inflateInit(&stream);
|
|
|
|
for (;;) {
|
|
int ret = inflate(&stream, 0);
|
|
use(len - stream.avail_in);
|
|
if (stream.total_out == size && ret == Z_STREAM_END)
|
|
break;
|
|
if (ret != Z_OK)
|
|
die("inflate returned %d\n", ret);
|
|
stream.next_in = fill(1);
|
|
stream.avail_in = len;
|
|
}
|
|
return buf;
|
|
}
|
|
|
|
struct delta_info {
|
|
unsigned char base_sha1[20];
|
|
unsigned long size;
|
|
void *delta;
|
|
struct delta_info *next;
|
|
};
|
|
|
|
static struct delta_info *delta_list;
|
|
|
|
static void add_delta_to_list(unsigned char *base_sha1, void *delta, unsigned long size)
|
|
{
|
|
struct delta_info *info = xmalloc(sizeof(*info));
|
|
|
|
memcpy(info->base_sha1, base_sha1, 20);
|
|
info->size = size;
|
|
info->delta = delta;
|
|
info->next = delta_list;
|
|
delta_list = info;
|
|
}
|
|
|
|
static void added_object(unsigned char *sha1, char *type, void *data, unsigned long size);
|
|
|
|
static int resolve_delta(char *type,
|
|
void *base, unsigned long base_size,
|
|
void *delta, unsigned long delta_size)
|
|
{
|
|
void *result;
|
|
unsigned long result_size;
|
|
unsigned char sha1[20];
|
|
|
|
result = patch_delta(base, base_size,
|
|
delta, delta_size,
|
|
&result_size);
|
|
if (!result)
|
|
die("failed to apply delta");
|
|
free(delta);
|
|
|
|
if (write_sha1_file(result, result_size, type, sha1) < 0)
|
|
die("failed to write object");
|
|
added_object(sha1, type, result, result_size);
|
|
free(result);
|
|
return 0;
|
|
}
|
|
|
|
static void added_object(unsigned char *sha1, char *type, void *data, unsigned long size)
|
|
{
|
|
struct delta_info **p = &delta_list;
|
|
struct delta_info *info;
|
|
|
|
while ((info = *p) != NULL) {
|
|
if (!memcmp(info->base_sha1, sha1, 20)) {
|
|
*p = info->next;
|
|
p = &delta_list;
|
|
resolve_delta(type, data, size, info->delta, info->size);
|
|
free(info);
|
|
continue;
|
|
}
|
|
p = &info->next;
|
|
}
|
|
}
|
|
|
|
static int unpack_non_delta_entry(enum object_type kind, unsigned long size)
|
|
{
|
|
void *buf = get_data(size);
|
|
unsigned char sha1[20];
|
|
char *type;
|
|
|
|
switch (kind) {
|
|
case OBJ_COMMIT: type = "commit"; break;
|
|
case OBJ_TREE: type = "tree"; break;
|
|
case OBJ_BLOB: type = "blob"; break;
|
|
case OBJ_TAG: type = "tag"; break;
|
|
default: die("bad type %d", kind);
|
|
}
|
|
if (write_sha1_file(buf, size, type, sha1) < 0)
|
|
die("failed to write object");
|
|
added_object(sha1, type, buf, size);
|
|
free(buf);
|
|
return 0;
|
|
}
|
|
|
|
static int unpack_delta_entry(unsigned long delta_size)
|
|
{
|
|
void *delta_data, *base;
|
|
unsigned long base_size;
|
|
char type[20];
|
|
unsigned char base_sha1[20];
|
|
|
|
memcpy(base_sha1, fill(20), 20);
|
|
use(20);
|
|
|
|
delta_data = get_data(delta_size);
|
|
|
|
if (!has_sha1_file(base_sha1)) {
|
|
add_delta_to_list(base_sha1, delta_data, delta_size);
|
|
return 0;
|
|
}
|
|
base = read_sha1_file(base_sha1, type, &base_size);
|
|
if (!base)
|
|
die("failed to read delta-pack base object %s", sha1_to_hex(base_sha1));
|
|
return resolve_delta(type, base, base_size, delta_data, delta_size);
|
|
}
|
|
|
|
static void unpack_one(void)
|
|
{
|
|
unsigned shift;
|
|
unsigned char *pack, c;
|
|
unsigned long size;
|
|
enum object_type type;
|
|
|
|
pack = fill(1);
|
|
c = *pack;
|
|
use(1);
|
|
type = (c >> 4) & 7;
|
|
size = (c & 15);
|
|
shift = 4;
|
|
while (c & 0x80) {
|
|
pack = fill(1);
|
|
c = *pack++;
|
|
use(1);
|
|
size += (c & 0x7f) << shift;
|
|
shift += 7;
|
|
}
|
|
switch (type) {
|
|
case OBJ_COMMIT:
|
|
case OBJ_TREE:
|
|
case OBJ_BLOB:
|
|
case OBJ_TAG:
|
|
unpack_non_delta_entry(type, size);
|
|
return;
|
|
case OBJ_DELTA:
|
|
unpack_delta_entry(size);
|
|
return;
|
|
default:
|
|
die("bad object type %d", type);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* We unpack from the end, older files first. Now, usually
|
|
* there are deltas etc, so we'll not actually write the
|
|
* objects in that order, but we might as well try..
|
|
*/
|
|
static void unpack_all(void)
|
|
{
|
|
int i;
|
|
struct pack_header *hdr = fill(sizeof(struct pack_header));
|
|
unsigned version = ntohl(hdr->hdr_version);
|
|
unsigned nr_objects = ntohl(hdr->hdr_entries);
|
|
|
|
if (ntohl(hdr->hdr_signature) != PACK_SIGNATURE)
|
|
die("bad pack file");
|
|
if (version != PACK_VERSION)
|
|
die("unable to handle pack file version %d", version);
|
|
fprintf(stderr, "Unpacking %d objects\n", nr_objects);
|
|
|
|
use(sizeof(struct pack_header));
|
|
for (i = 0; i < nr_objects; i++)
|
|
unpack_one();
|
|
if (delta_list)
|
|
die("unresolved deltas left after unpacking");
|
|
}
|
|
|
|
int main(int argc, char **argv)
|
|
{
|
|
int i;
|
|
unsigned char sha1[20];
|
|
|
|
for (i = 1 ; i < argc; i++) {
|
|
const char *arg = argv[i];
|
|
|
|
if (*arg == '-') {
|
|
if (!strcmp(arg, "-n")) {
|
|
dry_run = 1;
|
|
continue;
|
|
}
|
|
usage(unpack_usage);
|
|
}
|
|
|
|
/* We don't take any non-flag arguments now.. Maybe some day */
|
|
usage(unpack_usage);
|
|
}
|
|
SHA1_Init(&ctx);
|
|
unpack_all();
|
|
SHA1_Update(&ctx, buffer, offset);
|
|
SHA1_Final(sha1, &ctx);
|
|
if (memcmp(fill(20), sha1, 20))
|
|
die("final sha1 did not match");
|
|
use(20);
|
|
|
|
/* Write the last part of the buffer to stdout */
|
|
while (len) {
|
|
int ret = write(1, buffer + offset, len);
|
|
if (!ret)
|
|
break;
|
|
if (ret < 0) {
|
|
if (errno == EAGAIN || errno == EINTR)
|
|
continue;
|
|
break;
|
|
}
|
|
len -= ret;
|
|
offset += ret;
|
|
}
|
|
|
|
/* All done */
|
|
return 0;
|
|
}
|