Merge branch 'ps/clone-into-reftable-repository'

"git clone" has been prepared to allow cloning a repository with
non-default hash function into a repository that uses the reftable
backend.

* ps/clone-into-reftable-repository:
  builtin/clone: create the refdb with the correct object format
  builtin/clone: skip reading HEAD when retrieving remote
  builtin/clone: set up sparse checkout later
  builtin/clone: fix bundle URIs with mismatching object formats
  remote-curl: rediscover repository when fetching refs
  setup: allow skipping creation of the refdb
  setup: extract function to create the refdb

builtin/clone.c

@@ -1101,8 +1101,14 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
  }
  }
 
+ /*
+ * Initialize the repository, but skip initializing the reference
+ * database. We do not yet know about the object format of the
+ * repository, and reference backends may persist that information into
+ * their on-disk data structures.
+ */
  init_db(git_dir, real_git_dir, option_template, GIT_HASH_UNKNOWN, NULL,
- do_not_override_repo_unix_permissions, INIT_DB_QUIET);
+ do_not_override_repo_unix_permissions, INIT_DB_QUIET | INIT_DB_SKIP_REFDB);
 
  if (real_git_dir) {
  free((char *)git_dir);
@@ -1189,10 +1195,7 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
  if (option_required_reference.nr || option_optional_reference.nr)
  setup_reference();
 
- if (option_sparse_checkout && git_sparse_checkout_init(dir))
- return 1;
-
- remote = remote_get(remote_name);
+ remote = remote_get_early(remote_name);
 
  refspec_appendf(&remote->fetch, "+%s*:%s*", src_ref_prefix,
  branch_top.buf);
@@ -1270,6 +1273,27 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
  if (transport->smart_options && !deepen && !filter_options.choice)
  transport->smart_options->check_self_contained_and_connected = 1;
 
+ strvec_push(&transport_ls_refs_options.ref_prefixes, "HEAD");
+ refspec_ref_prefixes(&remote->fetch,
+ &transport_ls_refs_options.ref_prefixes);
+ if (option_branch)
+ expand_ref_prefix(&transport_ls_refs_options.ref_prefixes,
+ option_branch);
+ if (!option_no_tags)
+ strvec_push(&transport_ls_refs_options.ref_prefixes,
+ "refs/tags/");
+
+ refs = transport_get_remote_refs(transport, &transport_ls_refs_options);
+
+ /*
+ * Now that we know what algorithm the remote side is using, let's set
+ * ours to the same thing.
+ */
+ hash_algo = hash_algo_by_ptr(transport_get_hash_algo(transport));
+ initialize_repository_version(hash_algo, 1);
+ repo_set_hash_algo(the_repository, hash_algo);
+ create_reference_database(NULL, 1);
+
  /*
  * Before fetching from the remote, download and install bundle
  * data from the --bundle-uri option.
@@ -1285,24 +1309,7 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
  bundle_uri);
  else if (has_heuristic)
  git_config_set_gently("fetch.bundleuri", bundle_uri);
- }
-
- strvec_push(&transport_ls_refs_options.ref_prefixes, "HEAD");
- refspec_ref_prefixes(&remote->fetch,
- &transport_ls_refs_options.ref_prefixes);
- if (option_branch)
- expand_ref_prefix(&transport_ls_refs_options.ref_prefixes,
- option_branch);
- if (!option_no_tags)
- strvec_push(&transport_ls_refs_options.ref_prefixes,
- "refs/tags/");
-
- refs = transport_get_remote_refs(transport, &transport_ls_refs_options);
-
- if (refs)
- mapped_refs = wanted_peer_refs(refs, &remote->fetch);
-
- if (!bundle_uri) {
+ } else {
  /*
  * Populate transport->got_remote_bundle_uri and
  * transport->bundle_uri. We might get nothing.
@@ -1323,13 +1330,8 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
  }
  }
 
- /*
- * Now that we know what algorithm the remote side is using,
- * let's set ours to the same thing.
- */
- hash_algo = hash_algo_by_ptr(transport_get_hash_algo(transport));
- initialize_repository_version(hash_algo, 1);
- repo_set_hash_algo(the_repository, hash_algo);
+ if (refs)
+ mapped_refs = wanted_peer_refs(refs, &remote->fetch);
 
  if (mapped_refs) {
  /*
@@ -1432,6 +1434,9 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
  dissociate_from_references();
  }
 
+ if (option_sparse_checkout && git_sparse_checkout_init(dir))
+ return 1;
+
  junk_mode = JUNK_LEAVE_REPO;
  err = checkout(submodule_progress, filter_submodules);
 

remote-curl.c

@@ -1564,8 +1564,11 @@ int cmd_main(int argc, const char **argv)
  if (buf.len == 0)
  break;
  if (starts_with(buf.buf, "fetch ")) {
- if (nongit)
- die(_("remote-curl: fetch attempted without a local repo"));
+ if (nongit) {
+ setup_git_directory_gently(&nongit);
+ if (nongit)
+ die(_("remote-curl: fetch attempted without a local repo"));
+ }
  parse_fetch(&buf);
 
  } else if (!strcmp(buf.buf, "list") || starts_with(buf.buf, "list ")) {

remote.c

@@ -509,7 +509,7 @@ static void alias_all_urls(struct remote_state *remote_state)
  }
 }
 
-static void read_config(struct repository *repo)
+static void read_config(struct repository *repo, int early)
 {
  int flag;
 
@@ -518,7 +518,7 @@ static void read_config(struct repository *repo)
  repo->remote_state->initialized = 1;
 
  repo->remote_state->current_branch = NULL;
- if (startup_info->have_repository) {
+ if (startup_info->have_repository && !early) {
  const char *head_ref = refs_resolve_ref_unsafe(
  get_main_ref_store(repo), "HEAD", 0, NULL, &flag);
  if (head_ref && (flag & REF_ISSYMREF) &&
@@ -561,7 +561,7 @@ static const char *remotes_remote_for_branch(struct remote_state *remote_state,
 
 const char *remote_for_branch(struct branch *branch, int *explicit)
 {
- read_config(the_repository);
+ read_config(the_repository, 0);
  die_on_missing_branch(the_repository, branch);
 
  return remotes_remote_for_branch(the_repository->remote_state, branch,
@@ -587,7 +587,7 @@ remotes_pushremote_for_branch(struct remote_state *remote_state,
 
 const char *pushremote_for_branch(struct branch *branch, int *explicit)
 {
- read_config(the_repository);
+ read_config(the_repository, 0);
  die_on_missing_branch(the_repository, branch);
 
  return remotes_pushremote_for_branch(the_repository->remote_state,
@@ -599,7 +599,7 @@ static struct remote *remotes_remote_get(struct remote_state *remote_state,
 
 const char *remote_ref_for_branch(struct branch *branch, int for_push)
 {
- read_config(the_repository);
+ read_config(the_repository, 0);
  die_on_missing_branch(the_repository, branch);
 
  if (branch) {
@@ -709,7 +709,13 @@ remotes_remote_get(struct remote_state *remote_state, const char *name)
 
 struct remote *remote_get(const char *name)
 {
- read_config(the_repository);
+ read_config(the_repository, 0);
+ return remotes_remote_get(the_repository->remote_state, name);
+}
+
+struct remote *remote_get_early(const char *name)
+{
+ read_config(the_repository, 1);
  return remotes_remote_get(the_repository->remote_state, name);
 }
 
@@ -722,7 +728,7 @@ remotes_pushremote_get(struct remote_state *remote_state, const char *name)
 
 struct remote *pushremote_get(const char *name)
 {
- read_config(the_repository);
+ read_config(the_repository, 0);
  return remotes_pushremote_get(the_repository->remote_state, name);
 }
 
@@ -738,7 +744,7 @@ int remote_is_configured(struct remote *remote, int in_repo)
 int for_each_remote(each_remote_fn fn, void *priv)
 {
  int i, result = 0;
- read_config(the_repository);
+ read_config(the_repository, 0);
  for (i = 0; i < the_repository->remote_state->remotes_nr && !result;
  i++) {
  struct remote *remote =
@@ -1831,7 +1837,7 @@ struct branch *branch_get(const char *name)
 {
  struct branch *ret;
 
- read_config(the_repository);
+ read_config(the_repository, 0);
  if (!name || !*name || !strcmp(name, "HEAD"))
  ret = the_repository->remote_state->current_branch;
  else
@@ -1973,7 +1979,7 @@ static const char *branch_get_push_1(struct remote_state *remote_state,
 
 const char *branch_get_push(struct branch *branch, struct strbuf *err)
 {
- read_config(the_repository);
+ read_config(the_repository, 0);
  die_on_missing_branch(the_repository, branch);
 
  if (!branch)

remote.h

@@ -118,6 +118,7 @@ struct remote {
  * and configuration.
  */
 struct remote *remote_get(const char *name);
+struct remote *remote_get_early(const char *name);
 
 struct remote *pushremote_get(const char *name);
 int remote_is_configured(struct remote *remote, int in_repo);

setup.c

@@ -1887,21 +1887,79 @@ void initialize_repository_version(int hash_algo, int reinit)
  git_config_set_gently("extensions.objectformat", NULL);
 }
 
+static int is_reinit(void)
+{
+ struct strbuf buf = STRBUF_INIT;
+ char junk[2];
+ int ret;
+
+ git_path_buf(&buf, "HEAD");
+ ret = !access(buf.buf, R_OK) || readlink(buf.buf, junk, sizeof(junk) - 1) != -1;
+ strbuf_release(&buf);
+ return ret;
+}
+
+void create_reference_database(const char *initial_branch, int quiet)
+{
+ struct strbuf err = STRBUF_INIT;
+ int reinit = is_reinit();
+
+ /*
+ * We need to create a "refs" dir in any case so that older versions of
+ * Git can tell that this is a repository. This serves two main purposes:
+ *
+ * - Clients will know to stop walking the parent-directory chain when
+ * detecting the Git repository. Otherwise they may end up detecting
+ * a Git repository in a parent directory instead.
+ *
+ * - Instead of failing to detect a repository with unknown reference
+ * format altogether, old clients will print an error saying that
+ * they do not understand the reference format extension.
+ */
+ safe_create_dir(git_path("refs"), 1);
+ adjust_shared_perm(git_path("refs"));
+
+ if (refs_init_db(&err))
+ die("failed to set up refs db: %s", err.buf);
+
+ /*
+ * Point the HEAD symref to the initial branch with if HEAD does
+ * not yet exist.
+ */
+ if (!reinit) {
+ char *ref;
+
+ if (!initial_branch)
+ initial_branch = git_default_branch_name(quiet);
+
+ ref = xstrfmt("refs/heads/%s", initial_branch);
+ if (check_refname_format(ref, 0) < 0)
+ die(_("invalid initial branch name: '%s'"),
+ initial_branch);
+
+ if (create_symref("HEAD", ref, NULL) < 0)
+ exit(1);
+ free(ref);
+ }
+
+ if (reinit && initial_branch)
+ warning(_("re-init: ignored --initial-branch=%s"),
+ initial_branch);
+
+ strbuf_release(&err);
+}
+
 static int create_default_files(const char *template_path,
  const char *original_git_dir,
- const char *initial_branch,
  const struct repository_format *fmt,
  int prev_bare_repository,
- int init_shared_repository,
- int quiet)
+ int init_shared_repository)
 {
  struct stat st1;
  struct strbuf buf = STRBUF_INIT;
  char *path;
- char junk[2];
  int reinit;
  int filemode;
- struct strbuf err = STRBUF_INIT;
  const char *init_template_dir = NULL;
  const char *work_tree = get_git_work_tree();
 
@@ -1921,6 +1979,8 @@ static int create_default_files(const char *template_path,
  reset_shared_repository();
  git_config(git_default_config, NULL);
 
+ reinit = is_reinit();
+
  /*
  * We must make sure command-line options continue to override any
  * values we might have just re-read from the config.
@@ -1964,39 +2024,6 @@ static int create_default_files(const char *template_path,
  adjust_shared_perm(get_git_dir());
  }
 
- /*
- * We need to create a "refs" dir in any case so that older
- * versions of git can tell that this is a repository.
- */
- safe_create_dir(git_path("refs"), 1);
- adjust_shared_perm(git_path("refs"));
-
- if (refs_init_db(&err))
- die("failed to set up refs db: %s", err.buf);
-
- /*
- * Point the HEAD symref to the initial branch with if HEAD does
- * not yet exist.
- */
- path = git_path_buf(&buf, "HEAD");
- reinit = (!access(path, R_OK)
- || readlink(path, junk, sizeof(junk)-1) != -1);
- if (!reinit) {
- char *ref;
-
- if (!initial_branch)
- initial_branch = git_default_branch_name(quiet);
-
- ref = xstrfmt("refs/heads/%s", initial_branch);
- if (check_refname_format(ref, 0) < 0)
- die(_("invalid initial branch name: '%s'"),
- initial_branch);
-
- if (create_symref("HEAD", ref, NULL) < 0)
- exit(1);
- free(ref);
- }
-
  initialize_repository_version(fmt->hash_algo, 0);
 
  /* Check filemode trustability */
@@ -2156,14 +2183,11 @@ int init_db(const char *git_dir, const char *real_git_dir,
  validate_hash_algorithm(&repo_fmt, hash);
 
  reinit = create_default_files(template_dir, original_git_dir,
- initial_branch, &repo_fmt,
- prev_bare_repository,
- init_shared_repository,
- flags & INIT_DB_QUIET);
- if (reinit && initial_branch)
- warning(_("re-init: ignored --initial-branch=%s"),
- initial_branch);
+ &repo_fmt, prev_bare_repository,
+ init_shared_repository);
 
+ if (!(flags & INIT_DB_SKIP_REFDB))
+ create_reference_database(initial_branch, flags & INIT_DB_QUIET);
  create_object_directory();
 
  if (get_shared_repository()) {

setup.h

@@ -169,14 +169,16 @@ int verify_repository_format(const struct repository_format *format,
  */
 void check_repository_format(struct repository_format *fmt);
 
-#define INIT_DB_QUIET 0x0001
-#define INIT_DB_EXIST_OK 0x0002
+#define INIT_DB_QUIET (1 << 0)
+#define INIT_DB_EXIST_OK (1 << 1)
+#define INIT_DB_SKIP_REFDB (1 << 2)
 
 int init_db(const char *git_dir, const char *real_git_dir,
  const char *template_dir, int hash_algo,
  const char *initial_branch, int init_shared_repository,
  unsigned int flags);
 void initialize_repository_version(int hash_algo, int reinit);
+void create_reference_database(const char *initial_branch, int quiet);
 
 /*
  * NOTE NOTE NOTE!!