builtin/clone: skip reading HEAD when retrieving remote

After we have set up the remote configuration in git-clone(1) we'll call
`remote_get()` to read the remote from the on-disk configuration. But
next to reading the on-disk configuration, `remote_get()` will also
cause us to try and read the repository's HEAD reference so that we can
figure out the current branch. Besides being pointless in git-clone(1)
because we're operating in an empty repository anyway, this will also
break once we move creation of the reference database to a later point
in time.

Refactor the code to introduce a new `remote_get_early()` function that
will skip reading the HEAD reference to address this issue.

Signed-off-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: pks-t

builtin/clone.c

@@ -1185,7 +1185,7 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
 	if (option_required_reference.nr || option_optional_reference.nr)
 		setup_reference();
 
-	remote = remote_get(remote_name);
+	remote = remote_get_early(remote_name);
 
 	refspec_appendf(&remote->fetch, "+%s*:%s*", src_ref_prefix,
 			branch_top.buf);

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);