rename

static VALUE
rb_file_s_rename(VALUE klass, VALUE from, VALUE to)
{
    const char *src, *dst;
    VALUE f, t;

    rb_secure(2);
    FilePathValue(from);
    FilePathValue(to);
    f = rb_str_encode_ospath(from);
    t = rb_str_encode_ospath(to);
    src = StringValueCStr(f);
    dst = StringValueCStr(t);
#if defined __CYGWIN__
    errno = 0;
#endif
    if (rename(src, dst) < 0) {
#if defined DOSISH
        switch (errno) {
          case EEXIST:
#if defined (__EMX__)
          case EACCES:
#endif
            if (chmod(dst, 0666) == 0 &&
                unlink(dst) == 0 &&
                rename(src, dst) == 0)
                return INT2FIX(0);
        }
#endif
        sys_fail2(from, to);
    }

    return INT2FIX(0);
}