Rockbox

  • Status Unconfirmed
  • Percent Complete
    0%
  • Task Type Bugs
  • Category User Interface
  • Assigned To No-one
  • Operating System All players
  • Severity Low
  • Priority Very Low
  • Reported Version Daily build (which?)
  • Due in Version Undecided
  • Due Date Undecided
  • Votes
  • Private
Attached to Project: Rockbox
Opened by impig - 2021-05-23
Last edited by impig - 2021-05-26

FS#13293 - (exFAT) Directories ending with "." (dot) are invisible to file browser

UPDATE2: My SD card is exFAT formatted

Hi!
I realized I was missing some music on my X3ii player and figured out that directories with names that END with a “.” (dot) are invisible to the files browser. My SD card is formatted as exFAT.
Example: “Artist - Album X.”

Tested on both File view settings: “all” & “music” (same result).
Renaming them (removing the dot at the end, on computer) solves the problem.

Dots elsewhere in the name are not a problem, just at the end.
Example of OK dir name: “Artist - X. Album”

It would still be nice if these directories would be shown/accessible since you don’t always remember to rename them beforehand.

Tested on:
xDuoo X3ii
e910f63bba-210520

Thanks!

impig commented on 2021-05-23 19:35

I tried "all" and "music". My DIR sorting is by date.

impig commented on 2021-05-23 19:37

oh and the dot was not the first character in the name.

something like "The Artist - A. B. C. Album"

impig commented on 2021-05-24 18:47

I realized my description was not completely accurate so I updated the original post.

amachronic commented on 2021-05-26 16:33

FAT32 doesn't allow filenames to end with a dot. Might be why Rockbox isn't seeing it.

Are you using a non-FAT32 filesystem?

impig commented on 2021-05-26 19:32

@amachronic interesting… Indeed my SD card is formatted as exFAT.

Does rockbox only support FAT32/16? I couldn't find anything documented about supported filesystems…

I'll update my original post with the new info.
Thanks.

amachronic commented on 2021-05-26 23:52

@impig, the xDuoo X3ii is a hosted port, which means Rockbox runs as an application on the Linux OS "host". So it will support any filesystem that the host OS supports. On native ports (where Rockbox runs as the kernel) then only FAT32/16 has ever been supported.

A filesystem issue is just a wild guess on my part but maybe there is some file name check being wrongly applied.

I'll try to look into it at some point. Thanks for the info.

impig commented on 2021-05-27 08:49

Thanks for the info and support!

amachronic commented on 2021-05-27 16:50

Alright, I created a few folders ending with a dot, put some music in them, on an ext4 filesystem and ran the simulator. Rockbox displays them just fine and plays back okay.

Then I tried formatting an exFAT SD card and creating the same folders on it, using my laptop running Linux 5.10. The results are… interesting.

  1. Any number of trailing dots are stripped from filenames when creating files. For example if you create a file called 'Foo…' the kernel actually creates 'Foo', and that is what will show up in directory listings.
  2. Suppose you have a file 'XYZ'. You can append as many dots as you like to the filename and the kernel will happily access it, stripping off all the dots.
  3. Trailing spaces are NOT stripped. This is in stark contrast to FAT32 where trailing spaces are illegal in filenames.

Note I'm using the 'new' in-kernel exFAT driver, which got added in Linux 5.7. I don't know if the old FUSE driver works the same way.

I don't know which kernel version runs on the xDuoo X3ii, or which exFAT driver it uses, but any which way it looks like you're running afoul of these odd filename rules.

@impig, some further questions:

  1. Can you boot into the original firmware and see if the problem is present there too?
  2. Which OS did you use to copy files to the SD card?

Thank you.

impig commented on 2021-05-27 17:38

Thanks for investigating it @amachronic !

1. The original Hiby firmware sees the folder ending with a dot, but returns an error "No File Found" if you try to enter it. Running the "Update the music library" did not index this folder.

2. I copied the files to SD card using Devuan Beowulf which is based on Debian Buster:
Linux 4.19.0-16-amd64 #1 SMP Debian 4.19.181-1 (2021-03-19) x86_64 GNU/Linux

impig commented on 2021-05-27 17:44

In addition to that - My OS / Devuan lets me create folders "A." and "A" side by side on the exFAT formatted SD card, so it does see a difference in those two names.

amachronic commented on 2021-05-27 23:46

I tested with the FUSE-based driver on my end and it does differentiate "A." from "A".

The situation gets worse though: re-mounting the filesystem with the in-kernel driver, it can see that those two different directories exist and will show them both in a directory listing, but if you try to access "A." it silently reads "A" instead!

Now if you only have "A." present, the in-kernel driver won't be able to read "A." at all, even though it appears in a directory listing – because it's trying to strip the dots and access a non-existent folder "A".

This is a pretty serious bug IMHO. I can't find anything in the eXFAT spec relating to filenames except the usual banned characters like : * ! < > etc, nothing like stripping dots from the end of filenames.

Based on the behavior it looks like the xDuoo's kernel is using a buggy kernel exFAT driver, rather than the FUSE-based one. I don't think that's something we can fix, unfortunately.

impig commented on 2021-05-28 07:51

Really interesting indeed… Well it's easy enough to avoid it by ~smarter directory naming (or to know where to look if something is missing in aplaylist) so it's not a big deal if it can't be fixed…

Thanks again for looking into it!

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