str_mod_check(s, p, len)
    VALUE s;
    char *p;
    long len;
{
    if (RSTRING(s)->ptr != p || RSTRING(s)->len != len) {
	rb_raise(rb_eRuntimeError, "string modified");
    }
}
str_mod_check(s, p, len)
    VALUE s;
    char *p;
    long len;
{
    if (RSTRING(s)->ptr != p || RSTRING(s)->len != len) {
	rb_raise(rb_eRuntimeError, "string modified");
    }
}