1 files changed, 197 insertions, 10 deletions

diff --git a/src/submodule.c b/src/submodule.c
index d2af1440a..d89dd049f 100644
--- a/src/submodule.c
+++ b/src/submodule.c
@@ -475,7 +475,7 @@ int git_submodule_repo_init(
 
 	/* get the configured remote url of the submodule */
 	if ((error = git_buf_printf(&buf, "submodule.%s.url", sm->name)) < 0 ||
-		(error = git_repository_config(&cfg, sm->repo)) < 0 ||
+		(error = git_repository_config_snapshot(&cfg, sm->repo)) < 0 ||
 		(error = git_config_get_string(&configured_url, cfg, buf.ptr)) < 0 ||
 		(error = submodule_repo_init(&sub_repo, sm->repo, sm->path, configured_url, use_gitlink)) < 0)
 		goto done;
@@ -790,7 +790,7 @@ git_submodule_ignore_t git_submodule_set_ignore(
 	return old;
 }
 
-git_submodule_update_t git_submodule_update(git_submodule *submodule)
+git_submodule_update_t git_submodule_update_strategy(git_submodule *submodule)
 {
 	assert(submodule);
 	return (submodule->update < GIT_SUBMODULE_UPDATE_CHECKOUT) ?
@@ -835,6 +835,178 @@ git_submodule_recurse_t git_submodule_set_fetch_recurse_submodules(
 	return old;
 }
 
+static int submodule_repo_create(
+	git_repository **out,
+	git_repository *parent_repo,
+	const char *path)
+{
+	int error = 0;
+	git_buf workdir = GIT_BUF_INIT, repodir = GIT_BUF_INIT;
+	git_repository_init_options initopt = GIT_REPOSITORY_INIT_OPTIONS_INIT;
+	git_repository *subrepo = NULL;
+
+	initopt.flags =
+		GIT_REPOSITORY_INIT_MKPATH |
+		GIT_REPOSITORY_INIT_NO_REINIT |
+		GIT_REPOSITORY_INIT_NO_DOTGIT_DIR |
+		GIT_REPOSITORY_INIT_RELATIVE_GITLINK;
+
+	/* Workdir: path to sub-repo working directory */
+	error = git_buf_joinpath(&workdir, git_repository_workdir(parent_repo), path);
+	if (error < 0)
+		goto cleanup;
+
+	initopt.workdir_path = workdir.ptr;
+
+	/**
+	 * Repodir: path to the sub-repo. sub-repo goes in:
+	 * <repo-dir>/modules/<name>/ with a gitlink in the 
+	 * sub-repo workdir directory to that repository.
+	 */
+	error = git_buf_join3(
+		&repodir, '/', git_repository_path(parent_repo), "modules", path);
+	if (error < 0)
+		goto cleanup;
+
+	error = git_repository_init_ext(&subrepo, repodir.ptr, &initopt);
+
+cleanup:
+	git_buf_free(&workdir);
+	git_buf_free(&repodir);
+
+	*out = subrepo;
+
+	return error;
+}
+
+/**
+ * Callback to override sub-repository creation when
+ * cloning a sub-repository.
+ */
+static int git_submodule_update_repo_init_cb(
+	git_repository **out,
+	const char *path,
+	int bare,
+	void *payload)
+{
+	GIT_UNUSED(bare);
+	git_submodule *sm = payload;
+
+	return submodule_repo_create(out, sm->repo, path);
+}
+
+int git_submodule_update(git_submodule *sm, int init, git_submodule_update_options *_update_options)
+{
+	int error;
+	unsigned int submodule_status;
+	git_config *config = NULL;
+	const char *submodule_url;
+	git_repository *sub_repo = NULL;
+	git_remote *remote = NULL;
+	git_object *target_commit = NULL;
+	git_buf buf = GIT_BUF_INIT;
+	git_submodule_update_options update_options = GIT_SUBMODULE_UPDATE_OPTIONS_INIT;
+	git_clone_options clone_options = GIT_CLONE_OPTIONS_INIT;
+
+	assert(sm);
+
+	if (_update_options)
+		memcpy(&update_options, _update_options, sizeof(git_submodule_update_options));
+
+	GITERR_CHECK_VERSION(&update_options, GIT_SUBMODULE_UPDATE_OPTIONS_VERSION, "git_submodule_update_options");
+
+	/* Copy over the remote callbacks */
+	clone_options.remote_callbacks = update_options.remote_callbacks;
+	clone_options.signature = update_options.signature;
+
+	/* Get the status of the submodule to determine if it is already initialized  */
+	if ((error = git_submodule_status(&submodule_status, sm)) < 0)
+		goto done;
+
+	/*
+	 * If submodule work dir is not already initialized, check to see
+	 * what we need to do (initialize, clone, return error...)
+	 */
+	if (submodule_status & GIT_SUBMODULE_STATUS_WD_UNINITIALIZED) {
+		/*
+		 * Work dir is not initialized, check to see if the submodule
+		 * info has been copied into .git/config
+		 */
+		if ((error = git_repository_config_snapshot(&config, sm->repo)) < 0 ||
+			(error = git_buf_printf(&buf, "submodule.%s.url", git_submodule_name(sm))) < 0)
+			goto done;
+
+		if ((error = git_config_get_string(&submodule_url, config, git_buf_cstr(&buf))) < 0) {
+			/*
+			 * If the error is not "not found" or if it is "not found" and we are not
+			 * initializing the submodule, then return error.
+			 */
+			if (error != GIT_ENOTFOUND)
+				goto done;
+
+			if (error == GIT_ENOTFOUND && !init) {
+				giterr_set(GITERR_SUBMODULE, "Submodule is not initialized.");
+				error = GIT_ERROR;
+				goto done;
+			}
+
+			/* The submodule has not been initialized yet - initialize it now.*/
+			if ((error = git_submodule_init(sm, 0)) < 0)
+				goto done;
+
+			git_config_free(config);
+			config = NULL;
+
+			if ((error = git_repository_config_snapshot(&config, sm->repo)) < 0 ||
+				(error = git_config_get_string(&submodule_url, config, git_buf_cstr(&buf))) < 0)
+				goto done;
+		}
+
+		/** submodule is initialized - now clone it **/
+		/* override repo creation */
+		clone_options.repository_cb = git_submodule_update_repo_init_cb;
+		clone_options.repository_cb_payload = sm;
+
+		/*
+		 * Do not perform checkout as part of clone, instead we 
+		 * will checkout the specific commit manually.
+		 */
+		clone_options.checkout_opts.checkout_strategy = GIT_CHECKOUT_NONE;
+		update_options.checkout_opts.checkout_strategy = update_options.clone_checkout_strategy;
+
+		if ((error = git_clone(&sub_repo, submodule_url, sm->path, &clone_options)) < 0 ||
+			(error = git_repository_set_head_detached(sub_repo, git_submodule_index_id(sm), update_options.signature, NULL)) < 0 ||
+			(error = git_checkout_head(sub_repo, &update_options.checkout_opts)) != 0)
+			goto done;
+	} else {
+		/**
+		 * Work dir is initialized - look up the commit in the parent repository's index,
+		 * update the workdir contents of the subrepository, and set the subrepository's
+		 * head to the new commit.
+		 */
+		if ((error = git_submodule_open(&sub_repo, sm)) < 0 ||
+			(error = git_object_lookup(&target_commit, sub_repo, git_submodule_index_id(sm), GIT_OBJ_COMMIT)) < 0 ||
+			(error = git_checkout_tree(sub_repo, target_commit, &update_options.checkout_opts)) != 0 ||
+			(error = git_repository_set_head_detached(sub_repo, git_submodule_index_id(sm), update_options.signature, NULL)) < 0)
+			goto done;
+
+		/* Invalidate the wd flags as the workdir has been updated. */
+		sm->flags = sm->flags &
+			~(GIT_SUBMODULE_STATUS_IN_WD |
+		  	GIT_SUBMODULE_STATUS__WD_OID_VALID |
+		  	GIT_SUBMODULE_STATUS__WD_SCANNED);
+	}
+
+done:
+	git_buf_free(&buf);
+	git_config_free(config);
+	git_object_free(target_commit);
+	git_remote_free(remote);
+	git_repository_free(sub_repo);
+
+	return error;
+}
+
 int git_submodule_init(git_submodule *sm, int overwrite)
 {
 	int error;
@@ -853,7 +1025,7 @@ int git_submodule_init(git_submodule *sm, int overwrite)
 
 	/* write "submodule.NAME.url" */
 
-	if ((git_submodule_resolve_url(&effective_submodule_url, sm->repo, sm->url)) < 0 ||
+	if ((error = git_submodule_resolve_url(&effective_submodule_url, sm->repo, sm->url)) < 0 ||
 		(error = git_buf_printf(&key, "submodule.%s.url", sm->name)) < 0 ||
 		(error = git_config__update_entry(
 			cfg, key.ptr, effective_submodule_url.ptr, overwrite != 0, false)) < 0)
@@ -1867,16 +2039,31 @@ static int lookup_head_remote_key(git_buf *remote_name, git_repository *repo)
 	if ((error = git_repository_head(&head, repo)) < 0)
 		return error;
 
+	/**
+	 * If head does not refer to a branch, then return
+	 * GIT_ENOTFOUND to indicate that we could not find
+	 * a remote key for the local tracking branch HEAD points to.
+	 **/
+	if (!git_reference_is_branch(head)) {
+		giterr_set(GITERR_INVALID,
+			"HEAD does not refer to a branch.");
+		error = GIT_ENOTFOUND;
+		goto done;
+	}
+
 	/* lookup remote tracking branch of HEAD */
-	if (!(error = git_branch_upstream_name(
-			&upstream_name, repo, git_reference_name(head))))
-	{
-		/* lookup remote of remote tracking branch */
-		error = git_branch_remote_name(remote_name, repo, upstream_name.ptr);
+	if ((error = git_branch_upstream_name(
+		&upstream_name,
+		repo,
+		git_reference_name(head))) < 0)
+		goto done;
 
-		git_buf_free(&upstream_name);
-	}
+	/* lookup remote of remote tracking branch */
+	if ((error = git_branch_remote_name(remote_name, repo, upstream_name.ptr)) < 0)
+		goto done;
 
+done:
+	git_buf_free(&upstream_name);
 	git_reference_free(head);
 
 	return error;