Re: [PATCH 2/2] worktree.c: use submodule interface to access refs from another worktree

Signed-off-by: Nguyễn Thái Ngọc Duy <redacted>
---
 branch.c   |  3 +-
 worktree.c | 99 +++++++++++++++-----------------------------------------------
 worktree.h |  2 +-
 3 files changed, 27 insertions(+), 77 deletions(-)

diff --git a/branch.c b/branch.c
index b955d4f316..db5843718f 100644
--- a/branch.c
+++ b/branch.c

@@ -354,7 +354,8 @@ int replace_each_worktree_head_symref(const char *oldref, const char *newref)
 	for (i = 0; worktrees[i]; i++) {
 		if (worktrees[i]->is_detached)
 			continue;
-		if (strcmp(oldref, worktrees[i]->head_ref))
+		if (worktrees[i]->head_ref &&
+		    strcmp(oldref, worktrees[i]->head_ref))
 			continue;
 
 		if (set_worktree_head_symref(get_worktree_git_dir(worktrees[i]),

diff --git a/worktree.c b/worktree.c
index d633761575..25e5bc9a3e 100644
--- a/worktree.c
+++ b/worktree.c

@@ -19,54 +19,24 @@ void free_worktrees(struct worktree **worktrees)
 	free (worktrees);
 }
 
-/*
- * read 'path_to_ref' into 'ref'.  Also if is_detached is not NULL,
- * set is_detached to 1 (0) if the ref is detached (is not detached).
- *
- * $GIT_COMMON_DIR/$symref (e.g. HEAD) is practically outside $GIT_DIR so
- * for linked worktrees, `resolve_ref_unsafe()` won't work (it uses
- * git_path). Parse the ref ourselves.
- *
- * return -1 if the ref is not a proper ref, 0 otherwise (success)
- */
-static int parse_ref(char *path_to_ref, struct strbuf *ref, int *is_detached)
-{
-	if (is_detached)
-		*is_detached = 0;
-	if (!strbuf_readlink(ref, path_to_ref, 0)) {
-		/* HEAD is symbolic link */
-		if (!starts_with(ref->buf, "refs/") ||
-				check_refname_format(ref->buf, 0))
-			return -1;
-	} else if (strbuf_read_file(ref, path_to_ref, 0) >= 0) {
-		/* textual symref or detached */
-		if (!starts_with(ref->buf, "ref:")) {
-			if (is_detached)
-				*is_detached = 1;
-		} else {
-			strbuf_remove(ref, 0, strlen("ref:"));
-			strbuf_trim(ref);
-			if (check_refname_format(ref->buf, 0))
-				return -1;
-		}
-	} else
-		return -1;
-	return 0;
-}
-
 /**
- * Add the head_sha1 and head_ref (if not detached) to the given worktree
+ * Update head_sha1, head_ref and is_detached of the given worktree
  */
-static void add_head_info(struct strbuf *head_ref, struct worktree *worktree)
+static void add_head_info(struct worktree *wt)
 {
-	if (head_ref->len) {
-		if (worktree->is_detached) {
-			get_sha1_hex(head_ref->buf, worktree->head_sha1);
-		} else {
-			resolve_ref_unsafe(head_ref->buf, 0, worktree->head_sha1, NULL);
-			worktree->head_ref = strbuf_detach(head_ref, NULL);
-		}
-	}
+	int flags;
+	const char *target;
+
+	target = resolve_ref_submodule(wt->path, "HEAD",
+				       RESOLVE_REF_READING,
+				       wt->head_sha1, &flags);
+	if (!target)
+		return;
+
+	if (flags & REF_ISSYMREF)
+		wt->head_ref = xstrdup(target);
+	else
+		wt->is_detached = 1;
 }
 
 /**

@@ -77,9 +47,7 @@ static struct worktree *get_main_worktree(void)
 	struct worktree *worktree = NULL;
 	struct strbuf path = STRBUF_INIT;
 	struct strbuf worktree_path = STRBUF_INIT;
-	struct strbuf head_ref = STRBUF_INIT;
 	int is_bare = 0;
-	int is_detached = 0;
 
 	strbuf_add_absolute_path(&worktree_path, get_git_common_dir());
 	is_bare = !strbuf_strip_suffix(&worktree_path, "/.git");

@@ -91,13 +59,10 @@ static struct worktree *get_main_worktree(void)
 	worktree = xcalloc(1, sizeof(*worktree));
 	worktree->path = strbuf_detach(&worktree_path, NULL);
 	worktree->is_bare = is_bare;
-	worktree->is_detached = is_detached;
-	if (!parse_ref(path.buf, &head_ref, &is_detached))
-		add_head_info(&head_ref, worktree);
+	add_head_info(worktree);
 
 	strbuf_release(&path);
 	strbuf_release(&worktree_path);
-	strbuf_release(&head_ref);
 	return worktree;
 }
 

@@ -106,8 +71,6 @@ static struct worktree *get_linked_worktree(const char *id)
 	struct worktree *worktree = NULL;
 	struct strbuf path = STRBUF_INIT;
 	struct strbuf worktree_path = STRBUF_INIT;
-	struct strbuf head_ref = STRBUF_INIT;
-	int is_detached = 0;
 
 	if (!id)
 		die("Missing linked worktree name");

@@ -127,19 +90,14 @@ static struct worktree *get_linked_worktree(const char *id)
 	strbuf_reset(&path);
 	strbuf_addf(&path, "%s/worktrees/%s/HEAD", get_git_common_dir(), id);
 
-	if (parse_ref(path.buf, &head_ref, &is_detached) < 0)
-		goto done;
-
 	worktree = xcalloc(1, sizeof(*worktree));
 	worktree->path = strbuf_detach(&worktree_path, NULL);
 	worktree->id = xstrdup(id);
-	worktree->is_detached = is_detached;
-	add_head_info(&head_ref, worktree);
+	add_head_info(worktree);
 
 done:
 	strbuf_release(&path);
 	strbuf_release(&worktree_path);
-	strbuf_release(&head_ref);
 	return worktree;
 }
 

@@ -334,8 +292,6 @@ const struct worktree *find_shared_symref(const char *symref,
 					  const char *target)
 {
 	const struct worktree *existing = NULL;
-	struct strbuf path = STRBUF_INIT;
-	struct strbuf sb = STRBUF_INIT;
 	static struct worktree **worktrees;
 	int i = 0;
 

@@ -345,6 +301,10 @@ const struct worktree *find_shared_symref(const char *symref,
 
 	for (i = 0; worktrees[i]; i++) {
 		struct worktree *wt = worktrees[i];
+		const char *symref_target;
+		unsigned char sha1[20];
+		int flags;
+
 		if (wt->is_bare)
 			continue;
 

@@ -359,25 +319,14 @@ const struct worktree *find_shared_symref(const char *symref,
 			}
 		}
 
-		strbuf_reset(&path);
-		strbuf_reset(&sb);
-		strbuf_addf(&path, "%s/%s",
-			    get_worktree_git_dir(wt),
-			    symref);
-
-		if (parse_ref(path.buf, &sb, NULL)) {
-			continue;
-		}
-
-		if (!strcmp(sb.buf, target)) {
+		symref_target = resolve_ref_submodule(wt->path, symref, 0,
+						      sha1, &flags);
+		if ((flags & REF_ISSYMREF) && !strcmp(symref_target, target)) {
 			existing = wt;
 			break;
 		}
 	}
 
-	strbuf_release(&path);
-	strbuf_release(&sb);
-
 	return existing;
 }
 

diff --git a/worktree.h b/worktree.h
index 6bfb985203..5ea5e503fb 100644
--- a/worktree.h
+++ b/worktree.h

@@ -4,7 +4,7 @@
 struct worktree {
 	char *path;
 	char *id;
-	char *head_ref;
+	char *head_ref;		/* NULL if HEAD is broken or detached */
 	char *lock_reason;	/* internal use */
 	unsigned char head_sha1[20];
 	int is_detached;