Bug: The first file and directory names to exceed the 260-character `MAX_PATH` limit appear truncated.

[RokeJulianLockhart]

Description

20250516-1635-45.6671105.mp4

As the aforementioned demonstrates, accessing a path whose length exceeds MAX_PATH (ascertained by attempting to access \\wsl.localhost\fedoraremix\mnt\rjlb_data\@{'Name'='Entities'}#.dir\@{'Status'='Commenced'; 'Name'='In Use'}#.dir\@{'Person'='Beedell'; 'Identifier'='S21AIB'}#.dir\@{'Name'='Entity-Specific'}#.dir\@{'Person'='Roke'; 'Identifier'='S1EV2L'}#.dir\@{'Name'='Technical'}#.dir via a BTRFS wsl --mount) causes a network resource access error:

Steps To Reproduce

1. Create the undermentioned structure:

   1. #!/usr/bin/env sh
      sudo lsblk -f

   2. NAME   FSTYPE FSVER LABEL UUID FSAVAIL FSUSE% MOUNTPOINTS
      sda
      sdb
      sdc                                           [SWAP]
      sdd                             954.8G     0% /mnt/wslg/distro
                                                    /
      sde
      ├─sde1
      ├─sde2
      ├─sde3
      └─sde4                            1.4T    24% /mnt/test
      sdf
      └─sdf1                          184.3G    90% /mnt/rjlb_data

   To do so, create a BTRFS-formatted filesystem on a blank storage device, then mount it:

   1. #!/usr/bin/env pwsh
      #Requires -PSEdition Core
      If ($IsWindows) {
      	sudo wsl --mount \\.\PHYSICALDRIVE1 --bare
      }

   2. #!/usr/bin/env sh
      sudo lsblk -f
      	# Utilise the output to confirm that the *device* has been mounted into `wsl`, then set its path as `$dev_id`, and define a mount point at `$path`.
      sudo mount -t btrfs /dev/$dev_id /mnt/$path

2. When mounted, create the hideous path aforementioned. If you attempt to access it via the Files GUI, it should display the aforementioned error modal.

This probably isn't a minimal reproduction list, because I've yet to narrow the cause.

Files Version

3.9.9.0

Windows Version

10.0.26120

User ID

353b71b8-86f9-4fe0-ac0e-e1da114b9349

Log File

debug.log

[Josh65-2201]

Thanks for the report, does it work in Windows File Explorer?

[RokeJulianLockhart]

@Josh65-2201, yes: I can access explorer.exe "\\?\UNC\wsl.localhost\fedoraremix\mnt\rjlb_data\@{'Name'='Entities'}#.dir\@{'Status'='Commenced'; 'Name'='In Use'}#.dir\@{'Person'='Beedell'; 'Identifier'='S21AIB'}#.dir\@{'Name'='Entity-Specific'}#.dir\@{'Person'='Roke'; 'Identifier'='S1EV2L'}#.dir\@{'Name'='Technical'}#.dir\.@{'Name'='A WinDbg Evaluation Of A Windows Explorer Crash'}#.dir" and beyond.

[Josh65-2201]

Can you try building Files https://files.community/docs/contributing/building-from-source and testing if it works with this branch https://github.com/files-community/Files/tree/ya/LongPaths

[RokeJulianLockhart]

#17133 (comment)

@Josh65-2201, I might be able to, but I spend so little time on Windows (versus Fedora), and I've so little experience compiling on Windows, that it might take a while. If your CI can cope with creating an .MSIX, .MSIXBundle, or .AppInstaller for it, I'll evaluate it immediately.

[RokeJulianLockhart]

I've just realized that I can navigate to it via the CLI:

files-preview "\\?\UNC\wsl.localhost\fedoraremix\mnt\rjlb_data\@{'Name'='Entities'}#.dir\@{'Status'='Commenced'; 'Name'='In Use'}#.dir\@{'Person'='Beedell'; 'Identifier'='S21AIB'}#.dir\@{'Name'='Entity-Specific'}#.dir\@{'Person'='Roke'; 'Identifier'='S1EV2L'}#.dir\@{'Name'='Technical'}#.dir\.@{'Name'='A WinDbg Evaluation Of A Windows Explorer Crash'}#.dir"

Merely thumbnail generation is inoperative:

Most interestingly, I can even navigate backward and forward until I entirely leave \\wsl.localhost\fedoraremix and return again:

20250516-1820-27.0794641.mp4

[Josh65-2201]

Based on the error message the way your opening it \\?\UNC is removed so Files doesn't bypass the max length restrictions, with the branch I send it shouldn't need that.

[RokeJulianLockhart]

Looks like there might be another bug, and whether caused by this, IDK:

1. 

2. The context menus contain no entries, and there is no error message, despite the path being non-existent:

   20250516-1834-09.0127523.mp4

I'm recording all of these affiliated bugs so that, when I do eventually compile Files, I am able to ensure that I verify that all of these have been remediated.

[RokeJulianLockhart]

#17133 (comment)

@Josh65-2201, I've not the necessary available storage space on $Env:SystemDrive (it requires 18 GiB), nor the bandwidth to install VS on a VM on my other OS. Apologies.

[Josh65-2201]

@RokeJulianLockhart Can you see if this is an issue in 3.9.10, https://files.community/download

[RokeJulianLockhart]

#17133 (comment)

@Josh65-2201, the problem of paths > MAX_PATH being inaccessible has been resolved. However, there is a significant regression in that the filesystem objects that exist at the point at which MAX_PATH would truncate it are truncated, identically to how they are in the aforecited error modal:

This doesn't reproduce in explorer.exe "\\wsl.localhost\fedoraremix\mnt\rjlb_data\@{'Name'='Entities'}#.dir\@{'Status'='Commenced'; 'Name'='In Use'}#.dir\@{'Person'='Beedell'; 'Identifier'='S21AIB'}#.dir\@{'Name'='Entity-Specific'}#.dir\@{'Person'='Roke'; 'Identifier'='S1EV2L'}#.dir":

Regardless, this isn't merely cosmetic, for it breaks wt.exe integration:

However, explorer.exe's wt.exe integration also breaks at this point. ¹

Environment

Get-AppxPackage FilesPreview | Select-Object -ExpandProperty Version returns 3.9.10.0.

Footnotes

1. github.com/microsoft/terminal/issues/19058 ↩

[Josh65-2201]

So the folder name is being cut off after the 260 character limit?