On Wed, Sep 27, 2023 at 3:56 PM Eric W. Biederman <ebiederm@xxxxxxxxx> wrote:
> As part of the transition plan, we'd like to add a file in the .git
> directory that maps loose objects between SHA-1 and SHA-256. Let's
> implement the specification in the transition plan and store this data
> on a per-repository basis in struct repository.
>
> Signed-off-by: brian m. carlson <sandals@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
> ---
> diff --git a/loose.c b/loose.c
> @@ -0,0 +1,245 @@
> +static int load_one_loose_object_map(struct repository *repo, struct object_directory *dir)
> +{
> + struct strbuf buf = STRBUF_INIT, path = STRBUF_INIT;
> + FILE *fp;
> +
> + if (!dir->loose_map)
> + loose_object_map_init(&dir->loose_map);
> +
> + insert_oid_pair(dir->loose_map->to_compat, repo->hash_algo->empty_tree, repo->compat_hash_algo->empty_tree);
> + insert_oid_pair(dir->loose_map->to_storage, repo->compat_hash_algo->empty_tree, repo->hash_algo->empty_tree);
> +
> + insert_oid_pair(dir->loose_map->to_compat, repo->hash_algo->empty_blob, repo->compat_hash_algo->empty_blob);
> + insert_oid_pair(dir->loose_map->to_storage, repo->compat_hash_algo->empty_blob, repo->hash_algo->empty_blob);
> +
> + insert_oid_pair(dir->loose_map->to_compat, repo->hash_algo->null_oid, repo->compat_hash_algo->null_oid);
> + insert_oid_pair(dir->loose_map->to_storage, repo->compat_hash_algo->null_oid, repo->hash_algo->null_oid);
> +
> + strbuf_git_common_path(&path, repo, "objects/loose-object-idx");
> + fp = fopen(path.buf, "rb");
> + if (!fp)
> + return 0;
This early return leaks `path`. At minimum, call
`strbuf_release(&path)` before returning.
> + errno = 0;
> + if (strbuf_getwholeline(&buf, fp, '\n') || strcmp(buf.buf, loose_object_header))
> + goto err;
> + while (!strbuf_getline_lf(&buf, fp)) {
> + const char *p;
> + struct object_id oid, compat_oid;
> + if (parse_oid_hex_algop(buf.buf, &oid, &p, repo->hash_algo) ||
> + *p++ != ' ' ||
> + parse_oid_hex_algop(p, &compat_oid, &p, repo->compat_hash_algo) ||
> + p != buf.buf + buf.len)
> + goto err;
> + insert_oid_pair(dir->loose_map->to_compat, &oid, &compat_oid);
> + insert_oid_pair(dir->loose_map->to_storage, &compat_oid, &oid);
> + }
> +
> + strbuf_release(&buf);
> + strbuf_release(&path);
> + return errno ? -1 : 0;
> +err:
> + strbuf_release(&buf);
> + strbuf_release(&path);
> + return -1;
> +}
> +
> +int repo_write_loose_object_map(struct repository *repo)
> +{
> + kh_oid_map_t *map = repo->objects->odb->loose_map->to_compat;
> + struct lock_file lock;
> + int fd;
> + khiter_t iter;
> + struct strbuf buf = STRBUF_INIT, path = STRBUF_INIT;
> +
> + if (!should_use_loose_object_map(repo))
> + return 0;
> +
> + strbuf_git_common_path(&path, repo, "objects/loose-object-idx");
> + fd = hold_lock_file_for_update_timeout(&lock, path.buf, LOCK_DIE_ON_ERROR, -1);
> + iter = kh_begin(map);
> + if (write_in_full(fd, loose_object_header, strlen(loose_object_header)) < 0)
> + goto errout;
> +
> + for (; iter != kh_end(map); iter++) {
> + if (kh_exist(map, iter)) {
> + if (oideq(&kh_key(map, iter), the_hash_algo->empty_tree) ||
> + oideq(&kh_key(map, iter), the_hash_algo->empty_blob))
> + continue;
> + strbuf_addf(&buf, "%s %s\n", oid_to_hex(&kh_key(map, iter)), oid_to_hex(kh_value(map, iter)));
> + if (write_in_full(fd, buf.buf, buf.len) < 0)
> + goto errout;
> + strbuf_reset(&buf);
> + }
> + }
Nit: If you call strbuf_reset() immediately before strbuf_addf(), then
you save the reader of the code the effort of having to scan backward
through the function to verify that `buf` is empty the first time
through the loop.
> + strbuf_release(&buf);
> + if (commit_lock_file(&lock) < 0) {
> + error_errno(_("could not write loose object index %s"), path.buf);
> + strbuf_release(&path);
> + return -1;
> + }
> + strbuf_release(&path);
> + return 0;
> +errout:
> + rollback_lock_file(&lock);
> + strbuf_release(&buf);
> + error_errno(_("failed to write loose object index %s\n"), path.buf);
> + strbuf_release(&path);
> + return -1;
> +}
> +
> +int repo_loose_object_map_oid(struct repository *repo,
> + const struct object_id *src,
> + const struct git_hash_algo *to,
> + struct object_id *dest)
> +
> +{
Style: unnecessary blank line before opening `{`
> + struct object_directory *dir;
> + kh_oid_map_t *map;
> + khiter_t pos;
> +
> + for (dir = repo->objects->odb; dir; dir = dir->next) {
> + struct loose_object_map *loose_map = dir->loose_map;
> + if (!loose_map)
> + continue;
> + map = (to == repo->compat_hash_algo) ?
> + loose_map->to_compat :
> + loose_map->to_storage;
> + pos = kh_get_oid_map(map, *src);
> + if (pos < kh_end(map)) {
> + oidcpy(dest, kh_value(map, pos));
> + return 0;
> + }
> + }
> + return -1;
> +}
