[PATCH v3 40/44] refs: allow ref backend to be set for clone

[David Turner <dturner@twopensource.com>]

Add a new option, --refs-backend-type, to allow the ref backend type to
be set on new clones.

Submodules must use the same ref backend as the parent repository, so
we also pass the --refs-backend-type option option when cloning
submodules.

Signed-off-by: David Turner <dturner@twopensource.com>
---
 Documentation/git-clone.txt |  4 ++++
 builtin/clone.c             | 27 +++++++++++++++++++++++++--
 builtin/submodule--helper.c |  5 ++++-
 cache.h                     |  1 +
 refs.c                      |  2 ++
 5 files changed, 36 insertions(+), 3 deletions(-)

diff --git a/Documentation/git-clone.txt b/Documentation/git-clone.txt
index f1f2a3f..d7a4cb0 100644
--- a/Documentation/git-clone.txt
+++ b/Documentation/git-clone.txt
@@ -14,6 +14,7 @@ SYNOPSIS
 	  [-o <name>] [-b <name>] [-u <upload-pack>] [--reference <repository>]
 	  [--dissociate] [--separate-git-dir <git dir>]
 	  [--depth <depth>] [--[no-]single-branch]
+	  [--refs-backend-type=<name>]
 	  [--recursive | --recurse-submodules] [--] <repository>
 	  [<directory>]
 
@@ -216,6 +217,9 @@ objects from the source repository into a pack in the cloned repository.
 	The result is Git repository can be separated from working
 	tree.
 
+--refs-backend-type=<name>::
+	Type of refs backend. Default is to use the original files based
+	backend.
 
 <repository>::
 	The (possibly remote) repository to clone from.  See the
diff --git a/builtin/clone.c b/builtin/clone.c
index 3e14491..d489a87 100644
--- a/builtin/clone.c
+++ b/builtin/clone.c
@@ -92,11 +92,13 @@ static struct option builtin_clone_options[] = {
 		   N_("separate git dir from working tree")),
 	OPT_STRING_LIST('c', "config", &option_config, N_("key=value"),
 			N_("set config inside the new repository")),
+	OPT_STRING(0, "refs-backend-type", &refs_backend_type,
+		   N_("name"), N_("name of backend type to use")),
 	OPT_END()
 };
 
 static const char *argv_submodule[] = {
-	"submodule", "update", "--init", "--recursive", NULL
+	"submodule", "update", "--init", "--recursive", NULL, NULL
 };
 
 static const char *get_repo_path_1(struct strbuf *path, int *is_bundle)
@@ -724,8 +726,24 @@ static int checkout(void)
 	err |= run_hook_le(NULL, "post-checkout", sha1_to_hex(null_sha1),
 			   sha1_to_hex(sha1), "1", NULL);
 
-	if (!err && option_recursive)
+	if (!err && option_recursive) {
+		const char **backend_arg = argv_submodule;
+		char *new_backend_arg = NULL;
+		if (refs_backend_type) {
+			while (*backend_arg)
+				++backend_arg;
+
+			new_backend_arg = xmalloc(21 + strlen(refs_backend_type));
+			sprintf(new_backend_arg, "--refs-backend-type=%s",
+				refs_backend_type);
+			*backend_arg = new_backend_arg;
+		}
 		err = run_command_v_opt(argv_submodule, RUN_GIT_CMD);
+		if (refs_backend_type) {
+			free(new_backend_arg);
+			*backend_arg = NULL;
+		}
+	}
 
 	return err;
 }
@@ -744,6 +762,11 @@ static void write_config(struct string_list *config)
 					       write_one_config, NULL) < 0)
 			die("unable to write parameters to config file");
 	}
+
+	if (refs_backend_type &&
+	    write_one_config("core.refs-backend-type",
+			     refs_backend_type, NULL) < 0)
+			die("unable to write backend parameter to config file");
 }
 
 static void write_refspec_config(const char *src_ref_prefix,
diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
index f4c3eff..5c9ca4e 100644
--- a/builtin/submodule--helper.c
+++ b/builtin/submodule--helper.c
@@ -140,7 +140,10 @@ static int clone_submodule(const char *path, const char *gitdir, const char *url
 		argv_array_pushl(&cp.args, "--reference", reference, NULL);
 	if (gitdir && *gitdir)
 		argv_array_pushl(&cp.args, "--separate-git-dir", gitdir, NULL);
-
+	if (refs_backend_type && *refs_backend_type) {
+		argv_array_push(&cp.args, "--refs-backend-type");
+		argv_array_push(&cp.args, refs_backend_type);
+	}
 	argv_array_push(&cp.args, url);
 	argv_array_push(&cp.args, path);
 
diff --git a/cache.h b/cache.h
index cc817dc..692cfd3 100644
--- a/cache.h
+++ b/cache.h
@@ -695,6 +695,7 @@ enum object_creation_mode {
 extern enum object_creation_mode object_creation_mode;
 
 extern char *notes_ref_name;
+extern const char *refs_backend_type;
 
 extern int grafts_replace_parents;
 
diff --git a/refs.c b/refs.c
index 025cc08..901558d 100644
--- a/refs.c
+++ b/refs.c
@@ -21,6 +21,8 @@ struct ref_be *the_refs_backend = &refs_be_files;
  */
 struct ref_be *refs_backends = &refs_be_files;
 
+const char *refs_backend_type;
+
 /*
  * This function is used to switch to an alternate backend.
  */
-- 
2.4.2.644.g97b850b-twtrsrc