From: David Laight <David.Laight@ACULAB.COM>
To: 'Al Viro' <viro@zeniv.linux.org.uk>
Cc: "'Pali Rohár'" <pali.rohar@gmail.com>,
"OGAWA Hirofumi" <hirofumi@mail.parknet.co.jp>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"Theodore Y. Ts'o" <tytso@mit.edu>,
"Namjae Jeon" <linkinjeon@gmail.com>,
"Gabriel Krisman Bertazi" <krisman@collabora.com>
Subject: RE: vfat: Broken case-insensitive support for UTF-8
Date: Mon, 20 Jan 2020 16:51:34 +0000 [thread overview]
Message-ID: <db8161512f33468981cbc49e71b7bf05@AcuMS.aculab.com> (raw)
In-Reply-To: <20200120161206.GC8904@ZenIV.linux.org.uk>
From: Al Viro
> Sent: 20 January 2020 16:12
> > From: Pali Rohár
> > > Sent: 20 January 2020 15:20
> > ...
> > > This is not possible. There is 1:1 mapping between UTF-8 sequence and
> > > Unicode code point. wchar_t in kernel represent either one Unicode code
> > > point (limited up to U+FFFF in NLS framework functions) or 2bytes in
> > > UTF-16 sequence (only in utf8s_to_utf16s() and utf16s_to_utf8s()
> > > functions).
> >
> > Unfortunately there is neither a 1:1 mapping of all possible byte sequences
> > to wchar_t (or unicode code points), nor a 1:1 mapping of all possible
> > wchar_t values to UTF-8.
> > Really both need to be defined - even for otherwise 'invalid' sequences.
>
> Who. Cares?
>
> Filename is a sequence of octets, not codepoints. Its interpretation is
> entirely up to the userland.
For filesystems that really ought to be true.
Saves a lot of problems in the kernel.
I guess the fat driver has to do something to convert the UCS-16 on-disk filenames
to/from a sequence of octets.
Even Microsoft have made it much easier to have case-dependant
NTS4 filesystems in windows 10.
(Ever watched the number of different cases in the list of c:/windows/system32/drivers/*.sys
filenames output when windows boots? They are nearly all different!)
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next prev parent reply other threads:[~2020-01-20 16:51 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-19 22:14 vfat: Broken case-insensitive support for UTF-8 Pali Rohár
2020-01-19 23:08 ` Al Viro
2020-01-19 23:33 ` Pali Rohár
2020-01-20 0:09 ` Al Viro
2020-01-20 11:19 ` Pali Rohár
2020-01-20 4:04 ` OGAWA Hirofumi
2020-01-20 7:30 ` Al Viro
2020-01-20 7:45 ` Al Viro
2020-01-20 8:07 ` oopsably broken case-insensitive support in ext4 and f2fs (Re: vfat: Broken case-insensitive support for UTF-8) Al Viro
2020-01-20 19:35 ` Al Viro
2020-01-24 4:29 ` Eric Biggers
2020-01-24 17:47 ` Linus Torvalds
2020-01-24 18:03 ` Jaegeuk Kim
2020-01-24 18:45 ` Eric Biggers
2020-01-20 11:04 ` vfat: Broken case-insensitive support for UTF-8 Pali Rohár
2020-01-20 12:07 ` OGAWA Hirofumi
2020-01-20 21:40 ` Pali Rohár
2020-01-20 22:46 ` Al Viro
2020-01-20 23:57 ` Pali Rohár
2020-01-21 0:07 ` Al Viro
2020-01-21 20:34 ` Pali Rohár
2020-01-21 21:36 ` Al Viro
2020-01-21 22:14 ` Al Viro
2020-01-21 22:46 ` Pali Rohár
2020-01-26 23:08 ` Pali Rohár
2020-01-21 12:43 ` David Laight
2020-01-22 0:25 ` Gabriel Krisman Bertazi
2020-01-20 15:07 ` David Laight
2020-01-20 15:20 ` Pali Rohár
2020-01-20 15:47 ` David Laight
2020-01-20 16:12 ` Al Viro
2020-01-20 16:51 ` David Laight [this message]
2020-01-20 16:27 ` Pali Rohár
2020-01-20 16:43 ` David Laight
2020-01-20 16:56 ` Pali Rohár
2020-01-20 17:37 ` Theodore Y. Ts'o
2020-01-20 17:32 ` Theodore Y. Ts'o
2020-01-20 17:56 ` Pali Rohár
2020-01-21 3:52 ` OGAWA Hirofumi
2020-01-21 11:00 ` Pali Rohár
2020-01-21 12:26 ` OGAWA Hirofumi
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