From 9d08dc994d51298e2d8e75d8ed4ee477312ec53a Mon Sep 17 00:00:00 2001
From: Runxi Yu
Date: Sat, 7 Mar 2026 15:08:14 +0800
Subject: ref/refname: Add refname validation

---
 ref/refname/branch.go | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)
 create mode 100644 ref/refname/branch.go

(limited to 'ref/refname/branch.go')

diff --git a/ref/refname/branch.go b/ref/refname/branch.go
new file mode 100644
index 00000000..274a95e3
--- /dev/null
+++ b/ref/refname/branch.go
@@ -0,0 +1,25 @@
+package refname
+
+import "strings"
+
+// Branch checks one branch shorthand and returns its fully-qualified
+// refs/heads/... name.
+//
+// Unlike Git in-repository branch parsing, this helper does not expand @{-n}.
+func Branch(name string) (string, error) {
+	full := "refs/heads/" + name
+	if strings.HasPrefix(name, "-") || full == "refs/heads/HEAD" {
+		return "", &NameError{Name: name, Reason: "invalid branch name"}
+	}
+
+	err := validate(full, 0)
+	if err != nil {
+		return "", err
+	}
+
+	if strings.HasPrefix(name, "refs/") {
+		return name, nil
+	}
+
+	return full, nil
+}
-- 
cgit v1.3.1-10-gc9f91