Broken version preview in sidebar due to empty file

[juliushaertl]

When starting with an empty file there seems to be a scenario when there is a broken file version listed in the sidebar:

#!/bin/bash
filename=$(date | md5sum | cut -d " " -f 1)
NC_URL=https://admin:admin@nextcloud.local/remote.php/webdav/

echo $filename
echo "" > 1/$filename.md
echo a2 > 2/$filename.md
echo a3 > 3/$filename.md

curl -T "1/$filename.md" "$NC_URL/$filename.md"
curl -T "2/$filename.md" "$NC_URL/$filename.md" -H 'X-OC-Mtime: 12345648'
curl -T "3/$filename.md" "$NC_URL/$filename.md"

[juliushaertl]

Actually database content seems reasonable:

mysql> select * from oc_files_versions where file_id = 11970;
+------+---------+------------+------+----------+----------+
| id   | file_id | timestamp  | size | mimetype | metadata |
+------+---------+------------+------+----------+----------+
| 2945 |   11970 |   12345648 |    3 |       23 | []       |
| 2944 |   11970 | 1691662975 |    1 |       23 | []       |
| 2946 |   11970 | 1691662981 |    3 |       23 | []       |
+------+---------+------------+------+----------+----------+
3 rows in set (0.01 sec)

mysql> select path, mtime from oc_filecache where name like 'bbaf07%';
+----------------------------------------------------------------+------------+
| path                                                           | mtime      |
+----------------------------------------------------------------+------------+
| files/bbaf073b41fd7d439b1ea65da43f0b83.md                      | 1691662981 |
| files_versions/bbaf073b41fd7d439b1ea65da43f0b83.md.v1691662975 | 1691662975 |
| files_versions/bbaf073b41fd7d439b1ea65da43f0b83.md.v12345648   |   12345648 |
+----------------------------------------------------------------+------------+
3 rows in set (0.00 sec)

[juliushaertl]

Ok, seems to be just the preview as the file also downloads fine, 1 byte due to the newline

[juliushaertl]

Root cause fix is in #39786 but there is no cleanup yet of existing broken version references

[juliushaertl]

Finding orphaned db entries is quite tricky as we'd need to iterate over all entries to then

• find the root file path
• try to get the filecache entry for the path 'files_versions/$filepath.v$timestamp

One option could be to clean up on the fly when getting the versions, but a onetime cleanup would be preferred imo.

Non-tested patch for deleting orphaned db entry versions on the fly if they have no corresponding version file on the fs:

diff --git a/apps/files_versions/lib/Versions/LegacyVersionsBackend.php b/apps/files_versions/lib/Versions/LegacyVersionsBackend.php
index a9ea09247c2..f41e17f0adc 100644
--- a/apps/files_versions/lib/Versions/LegacyVersionsBackend.php
+++ b/apps/files_versions/lib/Versions/LegacyVersionsBackend.php
@@ -99,6 +99,8 @@ class LegacyVersionsBackend implements IVersionBackend, INameableVersionBackend,

                $versions = $this->getVersionsForFileFromDB($file, $user);

+
+
                if (count($versions) > 0) {
                        return $versions;
                }
@@ -138,6 +140,14 @@ class LegacyVersionsBackend implements IVersionBackend, INameableVersionBackend,
        private function getVersionsForFileFromDB(FileInfo $file, IUser $user): array {
                $userFolder = $this->rootFolder->getUserFolder($user->getUID());

+               $versions = $this->versionsMapper->findAllVersionsForFileId($file->getId());
+               $relativePath = $userFolder->getRelativePath($file->getPath());
+               $versionsFS = array_map(fn($version) => $version['version'], Storage::getVersions($user->getUID(), $relativePath));
+               $orphanedVersions = array_filter($versions, fn($version) => !in_array($version->getTimestamp(), $versionsFS));
+               foreach ($orphanedVersions as $version) {
+                       $this->versionsMapper->delete($version);
+               }
+
                return array_map(
                        fn (VersionEntity $versionEntity) => new Version(
                                $versionEntity->getTimestamp(),
@@ -151,7 +161,7 @@ class LegacyVersionsBackend implements IVersionBackend, INameableVersionBackend,
                                $user,
                                $versionEntity->getLabel(),
                        ),
-                       $this->versionsMapper->findAllVersionsForFileId($file->getId())
+                       $versions
                );
        }