Merge branch 'kn/ref-location'

Allow the directory in which reference backends store their data to
be specified.

* kn/ref-location:
  refs: add GIT_REFERENCE_BACKEND to specify reference backend
  refs: allow reference location in refstorage config
  refs: receive and use the reference storage payload
  refs: move out stub modification to generic layer
  refs: extract out `refs_create_refdir_stubs()`
  setup: don't modify repo in `create_reference_database()`

1 files changed, 84 insertions, 12 deletions

diff --git a/setup.c b/setup.c
index c8336eb20e..393b970ae4 100644
--- a/setup.c
+++ b/setup.c
@@ -631,6 +631,21 @@ static enum extension_result handle_extension_v0(const char *var,
 		return EXTENSION_UNKNOWN;
 }
 
+static void parse_reference_uri(const char *value, char **format,
+				char **payload)
+{
+	const char *schema_end;
+
+	schema_end = strstr(value, "://");
+	if (!schema_end) {
+		*format = xstrdup(value);
+		*payload = NULL;
+	} else {
+		*format = xstrndup(value, schema_end - value);
+		*payload = xstrdup_or_null(schema_end + 3);
+	}
+}
+
 /*
  * Record any new extensions in this function.
  */
@@ -673,10 +688,17 @@ static enum extension_result handle_extension(const char *var,
 		return EXTENSION_OK;
 	} else if (!strcmp(ext, "refstorage")) {
 		unsigned int format;
+		char *format_str;
 
 		if (!value)
 			return config_error_nonbool(var);
-		format = ref_storage_format_by_name(value);
+
+		parse_reference_uri(value, &format_str,
+				    &data->ref_storage_payload);
+
+		format = ref_storage_format_by_name(format_str);
+		free(format_str);
+
 		if (format == REF_STORAGE_FORMAT_UNKNOWN)
 			return error(_("invalid value for '%s': '%s'"),
 				     "extensions.refstorage", value);
@@ -852,6 +874,7 @@ void clear_repository_format(struct repository_format *format)
 	string_list_clear(&format->v1_only_extensions, 0);
 	free(format->work_tree);
 	free(format->partial_clone);
+	free(format->ref_storage_payload);
 	init_repository_format(format);
 }
 
@@ -1817,6 +1840,7 @@ const char *setup_git_directory_gently(int *nongit_ok)
 	static struct strbuf cwd = STRBUF_INIT;
 	struct strbuf dir = STRBUF_INIT, gitdir = STRBUF_INIT, report = STRBUF_INIT;
 	const char *prefix = NULL;
+	const char *ref_backend_uri;
 	struct repository_format repo_fmt = REPOSITORY_FORMAT_INIT;
 
 	/*
@@ -1944,7 +1968,8 @@ const char *setup_git_directory_gently(int *nongit_ok)
 			repo_set_compat_hash_algo(the_repository,
 						  repo_fmt.compat_hash_algo);
 			repo_set_ref_storage_format(the_repository,
-						    repo_fmt.ref_storage_format);
+						    repo_fmt.ref_storage_format,
+						    repo_fmt.ref_storage_payload);
 			the_repository->repository_format_worktree_config =
 				repo_fmt.worktree_config;
 			the_repository->repository_format_relative_worktrees =
@@ -1975,6 +2000,25 @@ const char *setup_git_directory_gently(int *nongit_ok)
 		setenv(GIT_PREFIX_ENVIRONMENT, "", 1);
 	}
 
+	/*
+	 * The env variable should override the repository config
+	 * for 'extensions.refStorage'.
+	 */
+	ref_backend_uri = getenv(GIT_REFERENCE_BACKEND_ENVIRONMENT);
+	if (ref_backend_uri) {
+		char *backend, *payload;
+		enum ref_storage_format format;
+
+		parse_reference_uri(ref_backend_uri, &backend, &payload);
+		format = ref_storage_format_by_name(backend);
+		if (format == REF_STORAGE_FORMAT_UNKNOWN)
+			die(_("unknown ref storage format: '%s'"), backend);
+		repo_set_ref_storage_format(the_repository, format, payload);
+
+		free(backend);
+		free(payload);
+	}
+
 	setup_original_cwd();
 
 	strbuf_release(&dir);
@@ -2046,7 +2090,8 @@ void check_repository_format(struct repository_format *fmt)
 	repo_set_hash_algo(the_repository, fmt->hash_algo);
 	repo_set_compat_hash_algo(the_repository, fmt->compat_hash_algo);
 	repo_set_ref_storage_format(the_repository,
-				    fmt->ref_storage_format);
+				    fmt->ref_storage_format,
+				    fmt->ref_storage_payload);
 	the_repository->repository_format_worktree_config =
 		fmt->worktree_config;
 	the_repository->repository_format_submodule_path_cfg =
@@ -2319,7 +2364,8 @@ void initialize_repository_version(int hash_algo,
 	 * the remote repository's format.
 	 */
 	if (hash_algo != GIT_HASH_SHA1_LEGACY ||
-	    ref_storage_format != REF_STORAGE_FORMAT_FILES)
+	    ref_storage_format != REF_STORAGE_FORMAT_FILES ||
+	    the_repository->ref_storage_payload)
 		target_version = GIT_REPO_VERSION_READ;
 
 	if (hash_algo != GIT_HASH_SHA1_LEGACY && hash_algo != GIT_HASH_UNKNOWN)
@@ -2328,11 +2374,20 @@ void initialize_repository_version(int hash_algo,
 	else if (reinit)
 		repo_config_set_gently(the_repository, "extensions.objectformat", NULL);
 
-	if (ref_storage_format != REF_STORAGE_FORMAT_FILES)
+	if (the_repository->ref_storage_payload) {
+		struct strbuf ref_uri = STRBUF_INIT;
+
+		strbuf_addf(&ref_uri, "%s://%s",
+			    ref_storage_format_to_name(ref_storage_format),
+			    the_repository->ref_storage_payload);
+		repo_config_set(the_repository, "extensions.refstorage", ref_uri.buf);
+		strbuf_release(&ref_uri);
+	} else if (ref_storage_format != REF_STORAGE_FORMAT_FILES) {
 		repo_config_set(the_repository, "extensions.refstorage",
 				ref_storage_format_to_name(ref_storage_format));
-	else if (reinit)
+	} else if (reinit) {
 		repo_config_set_gently(the_repository, "extensions.refstorage", NULL);
+	}
 
 	if (reinit) {
 		struct strbuf config = STRBUF_INIT;
@@ -2375,14 +2430,12 @@ static int is_reinit(void)
 	return ret;
 }
 
-void create_reference_database(enum ref_storage_format ref_storage_format,
-			       const char *initial_branch, int quiet)
+void create_reference_database(const char *initial_branch, int quiet)
 {
 	struct strbuf err = STRBUF_INIT;
 	char *to_free = NULL;
 	int reinit = is_reinit();
 
-	repo_set_ref_storage_format(the_repository, ref_storage_format);
 	if (ref_store_create_on_disk(get_main_ref_store(the_repository), 0, &err))
 		die("failed to set up refs db: %s", err.buf);
 
@@ -2616,6 +2669,7 @@ static void repository_format_configure(struct repository_format *repo_fmt,
 		.ignore_repo = 1,
 		.ignore_worktree = 1,
 	};
+	const char *ref_backend_uri;
 	const char *env;
 
 	config_with_options(read_default_format_config, &cfg, NULL, NULL, &opts);
@@ -2661,7 +2715,26 @@ static void repository_format_configure(struct repository_format *repo_fmt,
 	} else {
 		repo_fmt->ref_storage_format = REF_STORAGE_FORMAT_DEFAULT;
 	}
-	repo_set_ref_storage_format(the_repository, repo_fmt->ref_storage_format);
+
+
+	ref_backend_uri = getenv(GIT_REFERENCE_BACKEND_ENVIRONMENT);
+	if (ref_backend_uri) {
+		char *backend, *payload;
+		enum ref_storage_format format;
+
+		parse_reference_uri(ref_backend_uri, &backend, &payload);
+		format = ref_storage_format_by_name(backend);
+		if (format == REF_STORAGE_FORMAT_UNKNOWN)
+			die(_("unknown ref storage format: '%s'"), backend);
+
+		repo_fmt->ref_storage_format = format;
+		repo_fmt->ref_storage_payload = payload;
+
+		free(backend);
+	}
+
+	repo_set_ref_storage_format(the_repository, repo_fmt->ref_storage_format,
+				    repo_fmt->ref_storage_payload);
 }
 
 int init_db(const char *git_dir, const char *real_git_dir,
@@ -2717,8 +2790,7 @@ int init_db(const char *git_dir, const char *real_git_dir,
 				      &repo_fmt, init_shared_repository);
 
 	if (!(flags & INIT_DB_SKIP_REFDB))
-		create_reference_database(repo_fmt.ref_storage_format,
-					  initial_branch, flags & INIT_DB_QUIET);
+		create_reference_database(initial_branch, flags & INIT_DB_QUIET);
 	create_object_directory();
 
 	if (repo_settings_get_shared_repository(the_repository)) {