ref/refname: Add refname validation

1 files changed, 25 insertions, 0 deletions

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
+}