From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6E837C32771 for ; Tue, 21 Jan 2020 00:07:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 48F2A24650 for ; Tue, 21 Jan 2020 00:07:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728655AbgAUAHI (ORCPT ); Mon, 20 Jan 2020 19:07:08 -0500 Received: from zeniv.linux.org.uk ([195.92.253.2]:57038 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727075AbgAUAHI (ORCPT ); Mon, 20 Jan 2020 19:07:08 -0500 Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1ith4P-00CK6C-FD; Tue, 21 Jan 2020 00:07:01 +0000 Date: Tue, 21 Jan 2020 00:07:01 +0000 From: Al Viro To: Pali =?iso-8859-1?Q?Roh=E1r?= Cc: OGAWA Hirofumi , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, "Theodore Y. Ts'o" , Namjae Jeon , Gabriel Krisman Bertazi Subject: Re: vfat: Broken case-insensitive support for UTF-8 Message-ID: <20200121000701.GG8904@ZenIV.linux.org.uk> References: <20200119221455.bac7dc55g56q2l4r@pali> <87sgkan57p.fsf@mail.parknet.co.jp> <20200120110438.ak7jpyy66clx5v6x@pali> <875zh6pc0f.fsf@mail.parknet.co.jp> <20200120214046.f6uq7rlih7diqahz@pali> <20200120224625.GE8904@ZenIV.linux.org.uk> <20200120235745.hzza3fkehlmw5s45@pali> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20200120235745.hzza3fkehlmw5s45@pali> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Tue, Jan 21, 2020 at 12:57:45AM +0100, Pali Rohár wrote: > On Monday 20 January 2020 22:46:25 Al Viro wrote: > > On Mon, Jan 20, 2020 at 10:40:46PM +0100, Pali Rohár wrote: > > > > > Ok, I did some research. It took me it longer as I thought as lot of > > > stuff is undocumented and hard to find all relevant information. > > > > > > So... fastfat.sys is using ntos function RtlUpcaseUnicodeString() which > > > takes UTF-16 string and returns upper case UTF-16 string. There is no > > > mapping table in fastfat.sys driver itself. > > > > Er... Surely it's OK to just tabulate that function on 65536 values > > and see how could that be packed into something more compact? > > It is OK, but too complicated. That function is in nt kernel. So you > need to build a new kernel module and also decide where to put output of > that function. It is a long time since I did some nt kernel hacking and > nowadays you need to download 10GB+ of Visual Studio code, then addons > for building kernel modules, figure out how to write and compile simple > kernel module via Visual Studio, write ini install file, try to load it > and then you even fail as recent Windows kernels refuse to load kernel > modules which are not signed... Wait a sec... From NT userland, on a mounted VFAT: for all s in single-codepoint strings open s for append if failed print s on stderr, along with error value write s to the opened file, adding to its tail close the file the for each equivalence class you'll get a single file, with all members of that class written to it. In addition you'll get the list of prohibited codepoints. Why bother with any kind of kernel modules? IDGI...