Re: [PATCH] hfsplus: fix the bug that cannot recognize files with hangul file name

From: tchou <tchou@synology.com>
To: "Ernesto A. Fernández" <ernesto.mnd.fernandez@gmail.com>
Cc: linux-fsdevel@vger.kernel.org,
	linux-fsdevel-owner@vger.kernel.org, slava@dubeyko.com,
	htl10@users.sourceforge.net
Subject: Re: [PATCH] hfsplus: fix the bug that cannot recognize files with hangul file name
Date: Thu, 23 Nov 2017 11:57:41 +0800	[thread overview]
Message-ID: <080024a85dc413b72c181c6e75bdc736@synology.com> (raw)
In-Reply-To: <20171119005704.GA3495@debian.home>

> Could you please share the examples of incorrect and correct
> behaviour?

> What is it exactly that you are trying to fix? You mention an issue 
> with
> hangul characters, but I failed to trigger it. Could you expand on 
> that?
> 

Hi all,
There is an example.I use Mac mini to format my usb disk to HFS+ and 
touch
the file with filename "공유"(a Korean actor, https://goo.gl/VcBsrn) on 
it.
After it, I mount the usb disk on my ubuntu(Linux 4.14.0+) and get the
following error message when trying to ls and cp the file:

ls: cannot access 공유: No such file or directory
cp: cannot stat ‘공유’: No such file or directory

It seem's a problem for a long time(https://goo.gl/LiWGe5).
After applying my patch, I can ls and cp the file correctly.

> On Fri, Nov 17, 2017 at 04:20:05PM +0800, Ting-Chang Hou wrote:
>> The unicode of hangul from macOS is decomposed. There has a bug that
>> mistake decomposed unicode for composed when change unicode to ascii,
>> so it cannot recognize the hangul correctly.
>> 
>> Signed-off-by: Ting-Chang Hou <tchou@synology.com>
>> ---
>>  fs/hfsplus/unicode.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>> 
>> diff --git a/fs/hfsplus/unicode.c b/fs/hfsplus/unicode.c
>> index dfa90c2..2daf7b0 100644
>> --- a/fs/hfsplus/unicode.c
>> +++ b/fs/hfsplus/unicode.c
>> @@ -135,7 +135,7 @@ int hfsplus_uni2asc(struct super_block *sb,
>>  	ustrlen = be16_to_cpu(ustr->length);
>>  	len = *len_p;
>>  	ce1 = NULL;
>> -	compose = !test_bit(HFSPLUS_SB_NODECOMPOSE, &HFSPLUS_SB(sb)->flags);
>> +	compose = test_bit(HFSPLUS_SB_NODECOMPOSE, &HFSPLUS_SB(sb)->flags);
> 
> I'm not sure this is a mistake. The developers probably wanted the
> filenames to be recomposed before being presented in utf8. With your 
> patch,
> if you try the following (with the default mount options):
> 
>   touch Á
>   ls | hexdump -C
> 
> the utf8 output filename will be using the combining accent (CC 81) 
> instead
> of the Á character (C3 81). This is a bit annoying because it won't 
> print
> correctly in my terminal anymore.

I'm not exatly know why combining accent cannot print correctly in 
terminal
and how to avoid it. Whether apply my patch or not, my terminal cannot
print the hangul charactor correctly.