/*
 *  call-seq:
 *     dir.exists?(file_name) -> nil
 *
 *  Return true if a file with the name +file_name+ exists in the directory.
 */
static VALUE
frt_dir_exists(VALUE self, VALUE rfname)
{
    Store *store = DATA_PTR(self);
    StringValue(rfname);
    return store->exists(store, rs2s(rfname)) ? Qtrue : Qfalse;
}