[Bug]: Data lost when moving to parent folder with the same name (conflict modal resolve with all new files)

[andrey18106]

⚠️ This issue respects the following points: ⚠️

• This is a bug, not a question or a configuration/webserver/proxy issue.
• This issue is not already reported on Github OR Nextcloud Community Forum (I've searched it).
• Nextcloud Server is up to date. See Maintenance and Release Schedule for supported versions.
• I agree to follow Nextcloud's Code of Conduct.

Bug description

When moving a folder to a parent folder which contains another folder with the same name may result in data loss. Reproducible both on stable NC30 and latest master.

Steps to reproduce

1. Create test folder "Test"
2. Create "New folder" inside test folder ("Test/New Folder"), put some files
3. Create "New folder" inside "Test/New folder", put some files
4. Move "Test/New folder/New folder" to parent ("Test/New folder") / or move the same name folder "New folder" from other place to "Test/New folder"
5. In conflict dialog choose "Select all new files"
6. See "Move or copy action failed" toast, the parent folder "Test/New folder" gets deleted, or if moved from other place, the "New folder" gets deleted.

Expected behavior

The move action successful with correct conflicts resolve that doesn't lead to data loss (e.g. if trashbin is disabled).

Nextcloud Server version

30

[solracsf]

Confirmed also on v29 with:

1. Create folder /Test
2. Create New folder inside /Test folder (so, /Test/New Folder), put some files in it
3. Create New folder inside /Test/New folder (so, /Test/New Folder/New Folder)
4. Move /Test/New folder/New folder to parent /Test/New folder
5. In conflict dialog choose Select all new files
6. See Move or copy action failed message ; the parent folder /Test/New folder gets deleted and /Test is now empty !!
7. With the trashbin enabled, /Test/New folder ends up in the trashbin (but could be restored). Without trashbin, files would be lost.

[sorbaugh]

@Pytal could you take a look? 🙏

[Pytal]

I've debugged the issue and found that this is not a frontend bug but rather a bug with sabre/dav. The issue can be seen in https://github.com/sabre-io/dav/blob/4.7.0/lib/DAV/CorePlugin.php#L607-L612

On MOVE “Test/Foo/Foo” to “Test/Foo” the following occurs:

• Delete “Test/Foo”
• Try to move “Test/Foo/Foo” to “Test/Foo”

This throws an error,

server/apps/dav/lib/Connector/Sabre/Directory.php

Line 194 in db5be3d

throw new \Sabre\DAV\Exception\NotFound('File with name ' . $path . ' could not be located');

, because “Test/Foo/Foo” no longer exists

cc @icewind1991 for sabre/dav expertise