repo: take an oid_type when initializing

include/git2/repository.h

@@ -351,6 +351,15 @@ typedef struct {
 	 * pointing to this URL.
 	 */
 	const char *origin_url;
+
+#ifdef GIT_EXPERIMENTAL_SHA256
+	/**
+	 *
+	 * Type of object IDs to use for this repository, or 0 for
+	 * default (currently SHA1).
+	 */
+	git_oid_t oid_type;
+#endif
 } git_repository_init_options;
 
 #define GIT_REPOSITORY_INIT_OPTIONS_VERSION 1

src/libgit2/repository.c

@@ -1983,7 +1983,8 @@ static int repo_init_config(
 	const char *repo_dir,
 	const char *work_dir,
 	uint32_t flags,
-	uint32_t mode)
+	uint32_t mode,
+	git_oid_t oid_type)
 {
 	int error = 0;
 	git_str cfg_path = GIT_STR_INIT, worktree_path = GIT_STR_INIT;
@@ -2040,6 +2041,11 @@ static int repo_init_config(
 		SET_REPO_CONFIG(bool, "receive.denyNonFastforwards", true);
 	}
 
+	if (oid_type != GIT_OID_SHA1) {
+		SET_REPO_CONFIG(int32, "core.repositoryformatversion", 1);
+		SET_REPO_CONFIG(string, "extensions.objectformat", git_oid_type_name(oid_type));
+	}
+
 cleanup:
 	git_str_dispose(&cfg_path);
 	git_str_dispose(&worktree_path);
@@ -2520,6 +2526,7 @@ int git_repository_init_ext(
 		common_path = GIT_STR_INIT;
 	const char *wd;
 	bool is_valid;
+	git_oid_t oid_type = GIT_OID_DEFAULT;
 	int error;
 
 	GIT_ASSERT_ARG(out);
@@ -2528,6 +2535,11 @@ int git_repository_init_ext(
 
 	GIT_ERROR_CHECK_VERSION(opts, GIT_REPOSITORY_INIT_OPTIONS_VERSION, "git_repository_init_options");
 
+#ifdef GIT_EXPERIMENTAL_SHA256
+	if (opts->oid_type)
+		oid_type = opts->oid_type;
+#endif
+
 	if ((error = repo_init_directories(&repo_path, &wd_path, given_repo, opts)) < 0)
 		goto out;
 
@@ -2546,13 +2558,13 @@ int git_repository_init_ext(
 
 		opts->flags |= GIT_REPOSITORY_INIT__IS_REINIT;
 
-		if ((error = repo_init_config(repo_path.ptr, wd, opts->flags, opts->mode)) < 0)
+		if ((error = repo_init_config(repo_path.ptr, wd, opts->flags, opts->mode, oid_type)) < 0)
 			goto out;
 
 		/* TODO: reinitialize the templates */
 	} else {
 		if ((error = repo_init_structure(repo_path.ptr, wd, opts)) < 0 ||
-		    (error = repo_init_config(repo_path.ptr, wd, opts->flags, opts->mode)) < 0 ||
+		    (error = repo_init_config(repo_path.ptr, wd, opts->flags, opts->mode, oid_type)) < 0 ||
 		    (error = repo_init_head(repo_path.ptr, opts->initial_head)) < 0)
 			goto out;
 	}