worktree.c: make find_shared_symref() return struct worktree *

This gives the caller more information and they can answer things like,
"is it the main worktree" or "is it the current worktree". The latter
question is needed for the "checkout a rebase branch" case later.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

5 files changed, 28 insertions, 23 deletions

diff --git a/branch.c b/branch.c
index 0674a99328..1f1fbf528c 100644
--- a/branch.c
+++ b/branch.c
@@ -336,13 +336,14 @@ void remove_branch_state(void)
 
 void die_if_checked_out(const char *branch)
 {
-	char *existing;
+	const struct worktree *wt;
 
-	existing = find_shared_symref("HEAD", branch);
-	if (existing) {
-		skip_prefix(branch, "refs/heads/", &branch);
-		die(_("'%s' is already checked out at '%s'"), branch, existing);
-	}
+	wt = find_shared_symref("HEAD", branch);
+	if (!wt)
+		return;
+	skip_prefix(branch, "refs/heads/", &branch);
+	die(_("'%s' is already checked out at '%s'"),
+	    branch, wt->path);
 }
 
 int replace_each_worktree_head_symref(const char *oldref, const char *newref)
diff --git a/builtin/branch.c b/builtin/branch.c
index 0adba629d2..bcde87d8e7 100644
--- a/builtin/branch.c
+++ b/builtin/branch.c
@@ -220,12 +220,12 @@ static int delete_branches(int argc, const char **argv, int force, int kinds,
 		name = mkpathdup(fmt, bname.buf);
 
 		if (kinds == FILTER_REFS_BRANCHES) {
-			char *worktree = find_shared_symref("HEAD", name);
-			if (worktree) {
+			const struct worktree *wt =
+				find_shared_symref("HEAD", name);
+			if (wt) {
 				error(_("Cannot delete branch '%s' "
 					"checked out at '%s'"),
-				      bname.buf, worktree);
-				free(worktree);
+				      bname.buf, wt->path);
 				ret = 1;
 				continue;
 			}
diff --git a/builtin/notes.c b/builtin/notes.c
index 6fd058de92..c65b59ad9a 100644
--- a/builtin/notes.c
+++ b/builtin/notes.c
@@ -847,15 +847,15 @@ static int merge(int argc, const char **argv, const char *prefix)
 		update_ref(msg.buf, default_notes_ref(), result_sha1, NULL,
 			   0, UPDATE_REFS_DIE_ON_ERR);
 	else { /* Merge has unresolved conflicts */
-		char *existing;
+		const struct worktree *wt;
 		/* Update .git/NOTES_MERGE_PARTIAL with partial merge result */
 		update_ref(msg.buf, "NOTES_MERGE_PARTIAL", result_sha1, NULL,
 			   0, UPDATE_REFS_DIE_ON_ERR);
 		/* Store ref-to-be-updated into .git/NOTES_MERGE_REF */
-		existing = find_shared_symref("NOTES_MERGE_REF", default_notes_ref());
-		if (existing)
+		wt = find_shared_symref("NOTES_MERGE_REF", default_notes_ref());
+		if (wt)
 			die(_("A notes merge into %s is already in-progress at %s"),
-			    default_notes_ref(), existing);
+			    default_notes_ref(), wt->path);
 		if (create_symref("NOTES_MERGE_REF", default_notes_ref(), NULL))
 			die("Failed to store link to current notes ref (%s)",
 			    default_notes_ref());
diff --git a/worktree.c b/worktree.c
index 5ae54f0091..360ba417e8 100644
--- a/worktree.c
+++ b/worktree.c
@@ -191,14 +191,19 @@ const char *get_worktree_git_dir(const struct worktree *wt)
 		return git_common_path("worktrees/%s", wt->id);
 }
 
-char *find_shared_symref(const char *symref, const char *target)
+const struct worktree *find_shared_symref(const char *symref,
+					  const char *target)
 {
-	char *existing = NULL;
+	const struct worktree *existing = NULL;
 	struct strbuf path = STRBUF_INIT;
 	struct strbuf sb = STRBUF_INIT;
-	struct worktree **worktrees = get_worktrees();
+	static struct worktree **worktrees;
 	int i = 0;
 
+	if (worktrees)
+		free_worktrees(worktrees);
+	worktrees = get_worktrees();
+
 	for (i = 0; worktrees[i]; i++) {
 		strbuf_reset(&path);
 		strbuf_reset(&sb);
@@ -211,14 +216,13 @@ char *find_shared_symref(const char *symref, const char *target)
 		}
 
 		if (!strcmp(sb.buf, target)) {
-			existing = xstrdup(worktrees[i]->path);
+			existing = worktrees[i];
 			break;
 		}
 	}
 
 	strbuf_release(&path);
 	strbuf_release(&sb);
-	free_worktrees(worktrees);
 
 	return existing;
 }
diff --git a/worktree.h b/worktree.h
index 3198c8da2a..ca50e73b58 100644
--- a/worktree.h
+++ b/worktree.h
@@ -35,10 +35,10 @@ extern void free_worktrees(struct worktree **);
 
 /*
  * Check if a per-worktree symref points to a ref in the main worktree
- * or any linked worktree, and return the path to the exising worktree
- * if it is.  Returns NULL if there is no existing ref.  The caller is
- * responsible for freeing the returned path.
+ * or any linked worktree, and return the worktree that holds the ref,
+ * or NULL otherwise. The result may be destroyed by the next call.
  */
-extern char *find_shared_symref(const char *symref, const char *target);
+extern const struct worktree *find_shared_symref(const char *symref,
+						 const char *target);
 
 #endif