From: Aleksa Sarai <cyphar@cyphar.com>
To: lampahome <pahome.chen@mirlab.org>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: why do we need utf8 normalization when compare name?
Date: Mon, 2 Mar 2020 21:37:54 +1100 [thread overview]
Message-ID: <20200302103754.nsvtne2vvduug77e@yavin> (raw)
In-Reply-To: <CAB3eZfv4VSj6_XBBdHK12iX_RakhvXnTCFAmQfwogR34uySo3Q@mail.gmail.com>
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On 2020-03-02, lampahome <pahome.chen@mirlab.org> wrote:
> According to case insensitive since kernel 5.2, d_compare will
> transform string into normalized form and then compare.
>
> But why do we need this normalization function? Could we just compare
> by utf8 string?
The problem is that there are multiple ways to represent the same glyph
in Unicode -- for instance, you can represent Å (the symbol for
angstrom) as both U+212B and U+0041 U+030A (the latin letter "A"
followed by the ring-above symbol "°"). Different software may choose to
represent the same glyphs in different Unicode forms, hence the need for
normalisation.
[1] is the Wikipedia article that describes this problem and what the
different kinds of Unicode normalisation are.
[1]: https://en.wikipedia.org/wiki/Unicode_equivalence
--
Aleksa Sarai
Senior Software Engineer (Containers)
SUSE Linux GmbH
<https://www.cyphar.com/>
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next prev parent reply other threads:[~2020-03-02 10:38 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-02 9:00 why do we need utf8 normalization when compare name? lampahome
2020-03-02 10:37 ` Aleksa Sarai [this message]
2020-03-02 10:47 ` Aleksa Sarai
2020-03-03 1:48 ` lampahome
[not found] ` <20200303070928.aawxoyeq77wnc3ts@yavin>
2020-03-03 10:13 ` lampahome
2020-03-03 17:22 ` Theodore Y. Ts'o
2020-03-02 12:54 ` Matthew Wilcox
2020-03-02 15:28 ` Al Viro
2020-03-02 17:14 ` Matthew Wilcox
2020-03-02 18:12 ` Theodore Y. Ts'o
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