UTF-8 <-> UTF-16BE Converter in Kernel Needs Test

[Intron]

Yoshihiro Ota wrote:

> You may try these patches, first.
> http://people.freebsd.org/~imura/kiconv/
> 
> It sounds like these patches implement better supports.
> 
> Hiro
> 
> On Sun, 13 Aug 2006 01:28:17 +0800
> "Intron" <mag at intron.ac> wrote:
> 
>> I'm sorry that I send my experimental patch set here to call for test.
>> But if I send it to freebsd-i18n@, I wonder no one will respond to me.
>> 
>> Download: http://ftp.intron.ac/tmp/kiconv_utf8_20060813.tar.bz2
>> 
>> My patch set implements a UTF-8 <-> UTF-16BE converter for iconv in
>> kernel. It doesn't need kiconv(3) to send unnecessary UTF-8 <-> UTF-16BE
>> conversion tables to kernel. And it doesn't require the help of GNU
>> libiconv, which kiconv(3) depends on.
>> 
>> With my patch set, if you mount FAT/NTFS/ISO9660 file system, less
>> resource will be occupied than before:
>> 
>> mount_msdosfs -L ll_NN.UTF-8 /dev/md0s1 /mnt
>> 
>> See my "readme.txt" for installation guide.
>> 
>>                 ************  ATTENTION !!!  ************
>> 
>> 1. Do NOT test my patch set upon your CRITICAL FAT/NTFS partition !!!
>> 
>> 2. Limited by BUGGY FreeBSD modules msdosfs/ntfs/cd9660, whether you
>>     use my patch set or not, only 1/2-byte UTF-8 character (up to 0x7ff)
>>     is supported, which means only a few languages are supported.
>> 
>>     I will try to patch those modules to support all languages (up to
>>     6-byte UTF-8 character) included in current Unicode step by step.
>> 
>> ------------------------------------------------------------------------
>>                                                  From Beijing, China
>> 
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I have looked in his patch set. Some essential problems:

1. I don't know why the author takes the concept of Microsoft's 16-bit
    wchar_t as UTF-16BE (the macro ENCODING_UNICODE in /sys/sys/iconv.h).
    16-bit wchar_t is only enough for UCS-2 BE/LE (Unicode BMP) while
    real UTF-16 includes 4-byte formation.

2. Actually, kernel iconv is prepared only for Microsoft (FAT32, NTFS,
    Joliet extension to ISO 9660, SambaFS) so far. It should be a minimum
    function set just fit for Microsoft. Above all, it is not a complete
    implementation of UNIX98 iconv and should be as simple as possible.

3. In fact, UNIX98 iconv(3) handles any character set as char array.
    The usage of wchar_t is not of a good style in modules msdosfs/
    cd9660/ntfs. String function such as memcpy() should be used instead.
    If 5/6-byte UTF-8 sequence (Annex D of ISO/IEC 10646-1:2000) or other
    special encoding is allowed, handling by char array will be still
    robust.

------------------------------------------------------------------------
                                                From Beijing, China