Re: [PATCH] generic/453: Exclude filenames that are not supported by exfat

[Matthew Wilcox <willy@infradead.org>]

On Mon, Apr 26, 2021 at 05:27:51PM +0530, Shreeya Patel wrote:
> On 26/04/21 6:04 am, Matthew Wilcox wrote:
> > On Mon, Apr 26, 2021 at 04:01:05AM +0530, Shreeya Patel wrote:
> > > exFAT filesystem does not support the following character codes
> > > 0x0000 - 0x001F ( Control Codes ), /, ?, :, ", \, *, <, |, >
> > ummm ...
> > 
> > > -# Fake slash?
> > > -setf "urk\xc0\xafmoo" "FAKESLASH"
> > That doesn't use any of the explained banned characters.  It uses 0xc0,
> > 0xaf.
> > 
> > Now, in utf-8, that's an nonconforming sequence.  "The Unicode and UCS
> > standards require that producers of UTF-8 shall use the shortest form
> > possible, for example, producing a two-byte sequence with first byte 0xc0
> > is nonconforming.  Unicode 3.1 has added the requirement that conforming
> > programs must not accept non-shortest forms in their input."
> > 
> > So is it that exfat is rejecting nonconforming sequences?  Or is it
> > converting the nonconforming sequence from 0xc0 0xaf to the conforming
> > sequence 0x2f, and then rejecting it (because it's '/')?
> > 
> 
> No, I don't think exfat is not converting nonconforming sequence from 0xc0
> 0xaf
> to the conforming sequence 0x2f.
> Because I get different outputs when tried with both ways.
> When I create a file with "urk\xc0\xafmoo", I get output as "Operation not
> permitted"
> and when I create it as "urk\x2fmoo", it gives "No such file or directory
> error" or
> you can consider this error as "Invalid argument"
> ( because that's what I get when I try for other characters like |, :, ?,
> etc )

I think we need to understand this before skipping the test.  Does it
also fail, eg, on cifs, vfat, jfs or udf?

> Box filename also fails with "Invalid argument" error.
> 
>