FFS under Win11 creating unmanageable filenames ending with a dot

[jambon31]

Hi folks
I use FFS for some time to back up my andoid phones to a Windows machine, and recently noticed that some files landing on my Windows disk cannot be deleted or anything once created.

Setup is, Android connected with USB to a win11 laptop running FFS using MTP to copy Android files to local HDD.
Happens that a **very** popular android application has files in a /Sent/ directory with filenames terminated by a dot; they look like "tititata.". , with no extention.
=> the '.' is part of the filenames on the original (android) system
=> FFS does copy the files to the win11 laptop with the same filenames
=> win11 is unable to deal with these files afterwards. I can't access/move/delete them
=> If I use a copy+paste instead of FFS to copy the folder with explorer, the copied files are OK on the laptop HDD (=the trailing dot on the filename section are gone BUT not good for a backup because filenames have been modified)

Error from Windows if I try to access some backed up files on the HDD is "Item not found - This is no longer located in <directory name>". see screenshot.
Can't rename, change attributes, ownership, copy, move. I run FFS as a normal user and tried as admin to access the files with bogus names, does not help. Tried with explorer and cmd.exe , not working either, using quotes or other gotchas. NTFS filesystem checks OK with no errs.

This is arguably a FFS bug to create filenames that win11 cannot handle and users being stuck with.
If not seen as a bug, can you add something to FFS so users know about them filenames, and show a way to deal with baking them up, perhaps FFS should warn these files best filtered out and not backed up at all because of the hassle dealing with them on Win11 or something

===
**note** I finally managed to delete these "*.". files using FFS to scan the bogus directories on my HDD and used right click on the problematic files , selected 'Delete' and FFS was able to delete them bogus files,just like was able to create them.

Screenshots attached, thanks

MS explorer error on the file

2022-09-16 10_35_39-FreeFileSync Forum - Post a new topic and 6 more pages - Profile 1 - Microsoft​ .jpg (49.44 KiB) Viewed 945 times

FFS backed up filenames

2022-09-16 15_34_57-Sent-from FFS-BOGUS FILENAMES.jpg (194.56 KiB) Viewed 945 times

copy+paste backed up filenames

2022-09-16 15_34_11-Sent-from copy+paste.jpg (183.63 KiB) Viewed 945 times

[therube]

This is arguably a FFS bug to create filenames that win11 cannot handle

I'll argue that point, as having a file name that ends in a (.) dot is perfectly valid.
The fact that Windows itself does not (easily) know how to handle that situation is a failing of Windows.
(All that you have mentioned that can't be done with Windows, can be done, though perhaps not in a relatively straight forward manner.)

(Note that similarly, preceding or trailing spaces are also perfectly legal.)

If not seen as a bug, can you add something to FFS

Maybe... a setting could be added ? to ignore trailing (.) from the source (assuming FFS can determine that is the case), & copy sans the trailing (.) to the target?

Even though FFS copies with (.), you can (afterwards) remove the (.).
But in doing so, as you say, that breaks the comparison.
If FFS were able to ignore (.) [on reading of source], then comparisons & subsequent sync would remain valid.

Even better would be to see if you couldn't get that Android app to drop its' including of (.).
Any idea why they do that in the first place (as it is an odd thing to do)?
(Maybe it relates to operation on other, non-Windows OS?)

[jambon31]

I did use 'arguably' and I agree with you, I feel FFS can at least warn off users when these filenames being difficult to deal with. Or just finding this post will help now that it exists.

[Zenju]

FFS already has a check for folder names ending with a dot, and will fail when trying to create them.
It probably makes sense to also add this check when creating files. This is implemented for Windows only. There is no such issue on Linux, or macOS. Files ending with a dot can even be created via the file manager.

[therube]

Just to note, since FFS 11.26:

Don't allow creating file names ending with dot character (Windows)