linux-kernel - Re: [PATCH] fat: ignore .. subdir and always add a link to dirs

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Message-ID: <Zdier5NF7JeiMFx7@quatroqueijos.cascardo.eti.br>
Date: Fri, 23 Feb 2024 10:33:35 -0300
From: Thadeu Lima de Souza Cascardo <cascardo@...lia.com>
To: OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
Cc: linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	Gwendal Grignou <gwendal@...omium.org>, dlunev@...omium.org
Subject: Re: [PATCH] fat: ignore .. subdir and always add a link to dirs

On Fri, Feb 23, 2024 at 09:29:35PM +0900, OGAWA Hirofumi wrote:
> Thadeu Lima de Souza Cascardo <cascardo@...lia.com> writes:
> 
> > So far, I have only seen expected correct behavior here: mkdir/rmdir inside the
> > "bogus" directory works. rmdir of the "bogus" directory works.
> >
> > The only idiosyncrasies I can think of is that if neither "." or ".." are
> > present, the directory will have a link of 1, instead of 2. And when listing
> > the directory, those entries will not show up.
> >
> > Do you expect any of these to be corrected? It will require a more convoluted
> > change.
> >
> > Right now, I think accepting the idiosyncratic behavior for the bogus
> > filesystems is fine, as long as the correct filesystems continue to behave as
> > before. Which seems to be the case here as far as my testing has shown.
> 
> There are many corrupted images, and attacks. Allowing too wide is
> danger for fs.
> 
> BTW, this image works and pass fsck on windows? When I quickly tested
> ev3fs.zip (https://github.com/microsoft/pxt-ev3/issues/980) on windows
> on qemu, it didn't seem recognized as FAT. I can wrongly tested though.
> 
> Thanks.
> -- 
> OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>

Testing on FreeDOS, it is able to access the directory and create
subdirectories there. "." and ".." are missing when using "DIR" command. And
dosfsck complains about the missing "." and ".." but states it is not able to
fix those yet. But accessing the directory works nonetheless.

Cascardo.