[PATCHv4 4/5] worktree: get worktrees from submodules

[Stefan Beller <sbeller@google.com>]

In a later patch we want to move around the the git directory of
a submodule. Both submodules as well as worktrees are involved in
placing git directories at unusual places, so their functionality
may collide. To react appropriately to situations where worktrees
in submodules are in use, offer a new function to query the
worktrees for submodules.

Signed-off-by: Stefan Beller <sbeller@google.com>
---
 worktree.c | 47 +++++++++++++++++++++++++++++++++++++----------
 worktree.h |  6 ++++++
 2 files changed, 43 insertions(+), 10 deletions(-)

diff --git a/worktree.c b/worktree.c
index eb6121263b..fa2b6dfa9a 100644
--- a/worktree.c
+++ b/worktree.c
@@ -72,7 +72,7 @@ static void add_head_info(struct strbuf *head_ref, struct worktree *worktree)
 /**
  * get the main worktree
  */
-static struct worktree *get_main_worktree(void)
+static struct worktree *get_main_worktree(const char *git_common_dir)
 {
 	struct worktree *worktree = NULL;
 	struct strbuf path = STRBUF_INIT;
@@ -81,12 +81,12 @@ static struct worktree *get_main_worktree(void)
 	int is_bare = 0;
 	int is_detached = 0;
 
-	strbuf_add_absolute_path(&worktree_path, get_git_common_dir());
+	strbuf_add_absolute_path(&worktree_path, git_common_dir);
 	is_bare = !strbuf_strip_suffix(&worktree_path, "/.git");
 	if (is_bare)
 		strbuf_strip_suffix(&worktree_path, "/.");
 
-	strbuf_addf(&path, "%s/HEAD", get_git_common_dir());
+	strbuf_addf(&path, "%s/HEAD", git_common_dir);
 
 	worktree = xcalloc(1, sizeof(*worktree));
 	worktree->path = strbuf_detach(&worktree_path, NULL);
@@ -101,7 +101,8 @@ static struct worktree *get_main_worktree(void)
 	return worktree;
 }
 
-static struct worktree *get_linked_worktree(const char *id)
+static struct worktree *get_linked_worktree(const char *git_common_dir,
+					    const char *id)
 {
 	struct worktree *worktree = NULL;
 	struct strbuf path = STRBUF_INIT;
@@ -112,7 +113,7 @@ static struct worktree *get_linked_worktree(const char *id)
 	if (!id)
 		die("Missing linked worktree name");
 
-	strbuf_git_common_path(&path, "worktrees/%s/gitdir", id);
+	strbuf_addf(&path, "%s/worktrees/%s/gitdir", git_common_dir, id);
 	if (strbuf_read_file(&worktree_path, path.buf, 0) <= 0)
 		/* invalid gitdir file */
 		goto done;
@@ -125,7 +126,7 @@ static struct worktree *get_linked_worktree(const char *id)
 	}
 
 	strbuf_reset(&path);
-	strbuf_addf(&path, "%s/worktrees/%s/HEAD", get_git_common_dir(), id);
+	strbuf_addf(&path, "%s/worktrees/%s/HEAD", git_common_dir, id);
 
 	if (parse_ref(path.buf, &head_ref, &is_detached) < 0)
 		goto done;
@@ -167,7 +168,8 @@ static int compare_worktree(const void *a_, const void *b_)
 	return fspathcmp((*a)->path, (*b)->path);
 }
 
-struct worktree **get_worktrees(unsigned flags)
+static struct worktree **get_worktrees_internal(const char *git_common_dir,
+						unsigned flags)
 {
 	struct worktree **list = NULL;
 	struct strbuf path = STRBUF_INIT;
@@ -177,9 +179,9 @@ struct worktree **get_worktrees(unsigned flags)
 
 	list = xmalloc(alloc * sizeof(struct worktree *));
 
-	list[counter++] = get_main_worktree();
+	list[counter++] = get_main_worktree(git_common_dir);
 
-	strbuf_addf(&path, "%s/worktrees", get_git_common_dir());
+	strbuf_addf(&path, "%s/worktrees", git_common_dir);
 	dir = opendir(path.buf);
 	strbuf_release(&path);
 	if (dir) {
@@ -188,7 +190,7 @@ struct worktree **get_worktrees(unsigned flags)
 			if (is_dot_or_dotdot(d->d_name))
 				continue;
 
-			if ((linked = get_linked_worktree(d->d_name))) {
+			if ((linked = get_linked_worktree(git_common_dir, d->d_name))) {
 				ALLOC_GROW(list, counter + 1, alloc);
 				list[counter++] = linked;
 			}
@@ -209,6 +211,31 @@ struct worktree **get_worktrees(unsigned flags)
 	return list;
 }
 
+struct worktree **get_worktrees(unsigned flags)
+{
+	return get_worktrees_internal(get_git_common_dir(), flags);
+}
+
+struct worktree **get_submodule_worktrees(const char *path, unsigned flags)
+{
+	char *submodule_gitdir;
+	const char *submodule_common_dir;
+	struct strbuf sb = STRBUF_INIT;
+	struct worktree **ret;
+
+	submodule_gitdir = git_pathdup_submodule(path, "%s", "");
+	if (!submodule_gitdir)
+		return NULL;
+
+	/* the env would be set for the superproject */
+	get_common_dir_noenv(&sb, submodule_gitdir);
+	submodule_common_dir = strbuf_detach(&sb, NULL);
+	ret = get_worktrees_internal(submodule_common_dir, flags);
+
+	free(submodule_gitdir);
+	return ret;
+}
+
 const char *get_worktree_git_dir(const struct worktree *wt)
 {
 	if (!wt)
diff --git a/worktree.h b/worktree.h
index d59ce1fee8..157fbc4a66 100644
--- a/worktree.h
+++ b/worktree.h
@@ -27,6 +27,12 @@ struct worktree {
  */
 extern struct worktree **get_worktrees(unsigned flags);
 
+/*
+ * Get the worktrees of a submodule named by `path`.
+ */
+extern struct worktree **get_submodule_worktrees(const char *path,
+						 unsigned flags);
+
 /*
  * Return git dir of the worktree. Note that the path may be relative.
  * If wt is NULL, git dir of current worktree is returned.
-- 
2.11.0.rc2.28.g2673dad