Fix share transfer of single files and on the transfered node

[juliushaertl]

Fixes #21625

This fixes an issue where shares on single file transfers or on the root folder that is being transfered could not me moved over.

There were two issues here with the current implementation:

• When doing partial transfers with a path the shares to transfer were not filtered out so the transfer command attempted to migrate all shares to the new user
• The UserMountCache and Share object still had the old node information in their caches, so the share ownership checks had unexpected input data in

  server/lib/private/Share20/Manager.php

  Lines 302 to 305 in 43efac3

  	$userMounts = $userFolder->getById($share->getNode()->getId());
  	$userMount = array_shift($userMounts);
  	$mount = $userMount->getMountPoint();
  	if (!$isFederatedShare && $share->getNode()->getOwner() && $share->getNode()->getOwner()->getUID() !== $share->getSharedBy()) {

Steps to reproduce:

• Share a file f100.txt as admin with user1
• Transfer the file to user2 occ files:transfer-ownership --path=f100.txt admin user2

[MorrisJobke]

CI says "no".

[ChristophWurst]

:+

[juliushaertl]

Ready for another review, since i needed to go a bit of a different way to check if a share is contained in the transferred directory. Tests seem to pass now (before the rebase).

I'd actually like to extend the integration tests with some cases for this, but I'm still unable to get them to run locally, so I'd postpone this for a later point.

[blizzz]

🐘

[danxuliu]

With this pull request room reshares are no longer transferred if the target user is a participant in the conversation in that the source user shared the file.

[danxuliu]

Actually it seems to be a problem with reshares in general.

Steps to reproduce:

• user0 shares fileA with user1
• user1 shares fileA with user2
• occ files:transfer-ownership user1 user3

Expected result:

fileA is reshared from user3 to user2

Actual result:

fileA is still reshared from user1 to user2

[juliushaertl]

Ah, the source path is of course not null if no path is provided. 🙈

[juliushaertl]

backports:
stable18 #22802
stable19 #22804