fix: Properly fetch version from shared files by accessing the owner storage version

Signed-off-by: Julius Härtl <jus@bitgrid.net>

Author: juliusknorr

apps/files_versions/lib/Versions/LegacyVersionsBackend.php

@@ -27,6 +27,7 @@
 namespace OCA\Files_Versions\Versions;
 
 use OC\Files\View;
+use OCA\Files_Sharing\ISharedStorage;
 use OCA\Files_Sharing\SharedStorage;
 use OCA\Files_Versions\Db\VersionEntity;
 use OCA\Files_Versions\Db\VersionsMapper;
@@ -196,6 +197,18 @@ public function read(IVersion $version) {
 
 	public function getVersionFile(IUser $user, FileInfo $sourceFile, $revision): File {
 		$userFolder = $this->rootFolder->getUserFolder($user->getUID());
+		$file = $userFolder->get($userFolder->getRelativePath($sourceFile->getPath()));
+		$ownerUserId = $file->getOwner()?->getUID();
+		$storage = $file->getStorage();
+
+		/** @var ISharedStorage $storage */
+		if ($storage->instanceOfStorage(ISharedStorage::class) && $ownerUserId) {
+			// Shared files have their versions in the owners root folder
+			$userFolder = $this->rootFolder->getUserFolder($ownerUserId);
+			$user = $this->userManager->get($file->getOwner()->getUID());
+			$sourceFile = $storage->getShare()->getNode();
+		}
+
 		$versionFolder = $this->getVersionFolder($user);
 		/** @var File $file */
 		$file = $versionFolder->get($userFolder->getRelativePath($sourceFile->getPath()) . '.v' . $revision);