1 files changed, 33 insertions, 0 deletions
diff --git a/lib/efi_loader/efi_helper.c b/lib/efi_loader/efi_helper.c
index c71e87d..788cb9f 100644
--- a/lib/efi_loader/efi_helper.c
+++ b/lib/efi_loader/efi_helper.c
@@ -190,3 +190,36 @@ int efi_unlink_dev(efi_handle_t handle)
 
 	return 0;
 }
+
+static int u16_tohex(u16 c)
+{
+	if (c >= '0' && c <= '9')
+		return c - '0';
+	if (c >= 'A' && c <= 'F')
+		return c - 'A' + 10;
+
+	/* not hexadecimal */
+	return -1;
+}
+
+bool efi_varname_is_load_option(u16 *var_name16, int *index)
+{
+	int id, i, digit;
+
+	if (memcmp(var_name16, u"Boot", 8))
+		return false;
+
+	for (id = 0, i = 0; i < 4; i++) {
+		digit = u16_tohex(var_name16[4 + i]);
+		if (digit < 0)
+			break;
+		id = (id << 4) + digit;
+	}
+	if (i == 4 && !var_name16[8]) {
+		if (index)
+			*index = id;
+		return true;
+	}
+
+	return false;
+}