+static int ventoy_is_builtin_var(const char *var)
+{
+ int i;
+ const char *c;
+ const char *builtin_vars_full[] =
+ {
+ "VT_DISK_1ST_NONVTOY",
+ "VT_DISK_1ST_NONUSB",
+ NULL
+ };
+
+ for (i = 0; builtin_vars_full[i]; i++)
+ {
+ if (grub_strcmp(builtin_vars_full[i], var) == 0)
+ {
+ return 1;
+ }
+ }
+
+ if (grub_strncmp(var, "VT_DISK_CLOSEST_", 16) == 0)
+ {
+ c = var + 16;
+ while (*c)
+ {
+ if (*c < '0' || *c > '9')
+ {
+ break;
+ }
+ c++;
+ }
+
+ if (*c == 0 && c != (var + 16))
+ {
+ return 1;
+ }
+ }
+
+ return 0;
+}
+