mirror of
https://github.com/git/git.git
synced 2024-10-18 16:58:12 +02:00
33a14e81ae
In the future, we're going to want to provide SHA-256 repositories that have compatibility support for SHA-1 as well. In order to do so, we'll need to be able to convert tree objects from SHA-256 to SHA-1 by writing a tree with each SHA-256 object ID mapped to a SHA-1 object ID. We implement a function, convert_tree_object, that takes an existing tree buffer and writes it to a new strbuf, converting between algorithms. Let's make this function generic, because while we only need it to convert from the main algorithm to the compatibility algorithm now, we may need to do the other way around in the future, such as for transport. We avoid reusing the code in decode_tree_entry because that code normalizes data, and we don't want that here. We want to produce a complete round trip of data, so if, for example, the old entry had a wrongly zero-padded mode, we'd want to preserve that when converting to ensure a stable hash value. Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
119 lines
3.0 KiB
C
119 lines
3.0 KiB
C
#include "git-compat-util.h"
|
|
#include "gettext.h"
|
|
#include "strbuf.h"
|
|
#include "hex.h"
|
|
#include "repository.h"
|
|
#include "hash-ll.h"
|
|
#include "hash.h"
|
|
#include "object.h"
|
|
#include "loose.h"
|
|
#include "object-file-convert.h"
|
|
|
|
int repo_oid_to_algop(struct repository *repo, const struct object_id *src,
|
|
const struct git_hash_algo *to, struct object_id *dest)
|
|
{
|
|
/*
|
|
* If the source algorithm is not set, then we're using the
|
|
* default hash algorithm for that object.
|
|
*/
|
|
const struct git_hash_algo *from =
|
|
src->algo ? &hash_algos[src->algo] : repo->hash_algo;
|
|
|
|
if (from == to) {
|
|
if (src != dest)
|
|
oidcpy(dest, src);
|
|
return 0;
|
|
}
|
|
if (repo_loose_object_map_oid(repo, src, to, dest)) {
|
|
/*
|
|
* We may have loaded the object map at repo initialization but
|
|
* another process (perhaps upstream of a pipe from us) may have
|
|
* written a new object into the map. If the object is missing,
|
|
* let's reload the map to see if the object has appeared.
|
|
*/
|
|
repo_read_loose_object_map(repo);
|
|
if (repo_loose_object_map_oid(repo, src, to, dest))
|
|
return -1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static int decode_tree_entry_raw(struct object_id *oid, const char **path,
|
|
size_t *len, const struct git_hash_algo *algo,
|
|
const char *buf, unsigned long size)
|
|
{
|
|
uint16_t mode;
|
|
const unsigned hashsz = algo->rawsz;
|
|
|
|
if (size < hashsz + 3 || buf[size - (hashsz + 1)]) {
|
|
return -1;
|
|
}
|
|
|
|
*path = parse_mode(buf, &mode);
|
|
if (!*path || !**path)
|
|
return -1;
|
|
*len = strlen(*path) + 1;
|
|
|
|
oidread_algop(oid, (const unsigned char *)*path + *len, algo);
|
|
return 0;
|
|
}
|
|
|
|
static int convert_tree_object(struct strbuf *out,
|
|
const struct git_hash_algo *from,
|
|
const struct git_hash_algo *to,
|
|
const char *buffer, size_t size)
|
|
{
|
|
const char *p = buffer, *end = buffer + size;
|
|
|
|
while (p < end) {
|
|
struct object_id entry_oid, mapped_oid;
|
|
const char *path = NULL;
|
|
size_t pathlen;
|
|
|
|
if (decode_tree_entry_raw(&entry_oid, &path, &pathlen, from, p,
|
|
end - p))
|
|
return error(_("failed to decode tree entry"));
|
|
if (repo_oid_to_algop(the_repository, &entry_oid, to, &mapped_oid))
|
|
return error(_("failed to map tree entry for %s"), oid_to_hex(&entry_oid));
|
|
strbuf_add(out, p, path - p);
|
|
strbuf_add(out, path, pathlen);
|
|
strbuf_add(out, mapped_oid.hash, to->rawsz);
|
|
p = path + pathlen + from->rawsz;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
int convert_object_file(struct strbuf *outbuf,
|
|
const struct git_hash_algo *from,
|
|
const struct git_hash_algo *to,
|
|
const void *buf, size_t len,
|
|
enum object_type type,
|
|
int gentle)
|
|
{
|
|
int ret;
|
|
|
|
/* Don't call this function when no conversion is necessary */
|
|
if ((from == to) || (type == OBJ_BLOB))
|
|
BUG("Refusing noop object file conversion");
|
|
|
|
switch (type) {
|
|
case OBJ_TREE:
|
|
ret = convert_tree_object(outbuf, from, to, buf, len);
|
|
break;
|
|
case OBJ_COMMIT:
|
|
case OBJ_TAG:
|
|
default:
|
|
/* Not implemented yet, so fail. */
|
|
ret = -1;
|
|
break;
|
|
}
|
|
if (!ret)
|
|
return 0;
|
|
if (gentle) {
|
|
strbuf_release(outbuf);
|
|
return ret;
|
|
}
|
|
die(_("Failed to convert object from %s to %s"),
|
|
from->name, to->name);
|
|
}
|