Subject: [PATCH v3 19/20] repository: enable initialization of submodules

From: Brandon Williams <[email-masked]>
Date: Tue, 20 Jun 2017 12:19:50 -0700

Introduce 'repo_submodule_init()' which performs initialization of a
'struct repository' as a submodule of another 'struct repository'.

The resulting submodule can be in one of three states:

  1. The submodule is initialized and has a worktree.

  2. The submodule is initialized but does not have a worktree.  This
     would occur when the submodule's gitdir is present in the
     superproject's 'gitdir/modules/' directory yet the submodule has not
     been checked out in superproject's worktree.

  3. The submodule remains uninitialized due to an error in the
     initialization process or there is no matching submodule at the
     provided path in the superproject.

Signed-off-by: Brandon Williams <[email-masked]>
---
 repository.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
 repository.h | 10 ++++++++++
 2 files changed, 54 insertions(+)

diff --git a/repository.c b/repository.c
index 317041a4a..673b35ca5 100644
--- a/repository.c
+++ b/repository.c
@@ -155,6 +155,48 @@ int repo_init(struct repository *repo, const char *gitdir, const char *worktree)
 	return -1;
 }
 
+/*
+ * Initialize 'submodule' as the submodule given by 'path' in parent repository
+ * 'superproject'.
+ * Return 0 upon success and a non-zero value upon failure.
+ */
+int repo_submodule_init(struct repository *submodule,
+			struct repository *superproject,
+			const char *path)
+{
+	const struct submodule *sub;
+	struct strbuf submodule_path = STRBUF_INIT;
+	int ret = 0;
+
+	sub = submodule_from_cache(superproject, null_sha1, path);
+	if (!sub) {
+		ret = -1;
+		goto out;
+	}
+
+	strbuf_repo_worktree_path(&submodule_path, superproject, "%s", path);
+
+	if (repo_init(submodule, submodule_path.buf, submodule_path.buf)) {
+		strbuf_reset(&submodule_path);
+		strbuf_repo_git_path(&submodule_path, superproject,
+				     "modules/%s", sub->name);
+
+		if (repo_init(submodule, submodule_path.buf, NULL)) {
+			ret = -1;
+			goto out;
+		}
+	}
+
+	submodule->submodule_prefix = xstrfmt("%s%s/",
+					      superproject->submodule_prefix ?
+					      superproject->submodule_prefix :
+					      "", path);
+
+out:
+	strbuf_release(&submodule_path);
+	return ret;
+}
+
 void repo_clear(struct repository *repo)
 {
 	free(repo->gitdir);
@@ -169,6 +211,8 @@ void repo_clear(struct repository *repo)
 	repo->index_file = NULL;
 	free(repo->worktree);
 	repo->worktree = NULL;
+	free(repo->submodule_prefix);
+	repo->submodule_prefix = NULL;
 
 	if (repo->config) {
 		git_configset_clear(repo->config);
diff --git a/repository.h b/repository.h
index 4bc70ebc5..7b352accb 100644
--- a/repository.h
+++ b/repository.h
@@ -25,6 +25,13 @@ struct repository {
 	/* Path to the working directory */
 	char *worktree;
 
+	/*
+	 * Path from the root of the top-level superproject down to this
+	 * repository.  This is only non-NULL if the repository is initialized
+	 * as a submodule of another repository.
+	 */
+	char *submodule_prefix;
+
 	/* Subsystems */
 	/*
 	 * Repository's config which contains key-value pairs from the usual
@@ -59,6 +66,9 @@ extern struct repository *the_repository;
 extern void repo_set_gitdir(struct repository *repo, const char *path);
 extern void repo_set_worktree(struct repository *repo, const char *path);
 extern int repo_init(struct repository *repo, const char *gitdir, const char *worktree);
+extern int repo_submodule_init(struct repository *submodule,
+			       struct repository *superproject,
+			       const char *path);
 extern void repo_clear(struct repository *repo);
 
 extern int repo_read_index(struct repository *repo);
-- 
2.13.1.611.g7e3b11ae1-goog