1 files changed, 78 insertions, 0 deletions
diff --git a/third_party/git/builtin/symbolic-ref.c b/third_party/git/builtin/symbolic-ref.c
new file mode 100644
index 000000000000..80237f0df10f
--- /dev/null
+++ b/third_party/git/builtin/symbolic-ref.c
@@ -0,0 +1,78 @@
+#include "builtin.h"
+#include "config.h"
+#include "cache.h"
+#include "refs.h"
+#include "parse-options.h"
+
+static const char * const git_symbolic_ref_usage[] = {
+	N_("git symbolic-ref [<options>] <name> [<ref>]"),
+	N_("git symbolic-ref -d [-q] <name>"),
+	NULL
+};
+
+static int check_symref(const char *HEAD, int quiet, int shorten, int print)
+{
+	int flag;
+	const char *refname = resolve_ref_unsafe(HEAD, 0, NULL, &flag);
+
+	if (!refname)
+		die("No such ref: %s", HEAD);
+	else if (!(flag & REF_ISSYMREF)) {
+		if (!quiet)
+			die("ref %s is not a symbolic ref", HEAD);
+		else
+			return 1;
+	}
+	if (print) {
+		if (shorten)
+			refname = shorten_unambiguous_ref(refname, 0);
+		puts(refname);
+	}
+	return 0;
+}
+
+int cmd_symbolic_ref(int argc, const char **argv, const char *prefix)
+{
+	int quiet = 0, delete = 0, shorten = 0, ret = 0;
+	const char *msg = NULL;
+	struct option options[] = {
+		OPT__QUIET(&quiet,
+			N_("suppress error message for non-symbolic (detached) refs")),
+		OPT_BOOL('d', "delete", &delete, N_("delete symbolic ref")),
+		OPT_BOOL(0, "short", &shorten, N_("shorten ref output")),
+		OPT_STRING('m', NULL, &msg, N_("reason"), N_("reason of the update")),
+		OPT_END(),
+	};
+
+	git_config(git_default_config, NULL);
+	argc = parse_options(argc, argv, prefix, options,
+			     git_symbolic_ref_usage, 0);
+	if (msg && !*msg)
+		die("Refusing to perform update with empty message");
+
+	if (delete) {
+		if (argc != 1)
+			usage_with_options(git_symbolic_ref_usage, options);
+		ret = check_symref(argv[0], 1, 0, 0);
+		if (ret)
+			die("Cannot delete %s, not a symbolic ref", argv[0]);
+		if (!strcmp(argv[0], "HEAD"))
+			die("deleting '%s' is not allowed", argv[0]);
+		return delete_ref(NULL, argv[0], NULL, REF_NO_DEREF);
+	}
+
+	switch (argc) {
+	case 1:
+		ret = check_symref(argv[0], quiet, shorten, 1);
+		break;
+	case 2:
+		if (!strcmp(argv[0], "HEAD") &&
+		    !starts_with(argv[1], "refs/"))
+			die("Refusing to point HEAD outside of refs/");
+		ret = !!create_symref(argv[0], argv[1], msg);
+		break;
+	default:
+		usage_with_options(git_symbolic_ref_usage, options);
+	}
+	return ret;
+}