linux-ext4 - Re: Maximum filename length

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Date:	Sat, 22 Nov 2008 10:50:25 +0800
From:	"rae l" <crquan@...il.com>
To:	"Theodore Tso" <tytso@....edu>
Cc:	"Alexey Salmin" <alexey.salmin@...il.com>,
	linux-ext4@...r.kernel.org
Subject: Re: Maximum filename length

On Sat, Nov 22, 2008 at 6:32 AM, Theodore Tso <tytso@....edu> wrote:
> So the problem is that even if we were to add that enhancement to
> ext4, there are lots of other things, both in and outside of the
> kernel, that would likely need to be changed in order to support this.
> I will say personally that its rare for me to use filenames longer
> than 50-60 characters, just because they are a pain in the *ss to
> type.  However, I can see how someone using a graphical interface
> might be happy with filenames in the 100-120 character range.  The
> question though is whether it is worth trying to fix this by
> increasing the filename length beyond 255 bytes or not, given the
> amount of effort that would be required in the kernel, libc,
> userspace, etc.

In China, there's also a trend moving ahead from 2bytes charsets
(GB2312/GBK/GB18030/BIG5) to UTF-8, so all Chinese characters will
need 3 bytes for each to each instead of 2 from then on. The 255
filename length limit the Chinese filename to 85 characters:

now try to touch a file with 86 Chinese characters:

gektop@tux ~/tmp 0 $ touch
中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中国
touch: cannot touch
`中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中国':
File name too long


It's very difficult to solve all these problems in the kernel, libc,
userspace, I know, but I think we should keep the option to fix them
in the future. Maybe in the next POSIX standard, we should change
NAME_MAX to [255 * max_bytes_per_character] ?


Regards,

>
>                                        - Ted
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-- 
Cheng Renquan, Shenzhen, China
Yogi Berra  - "I never said most of the things I said."