Android: App crashes when opening folder that contains subfolder with many files

[slovdahl]

Steps to reproduce

This is what I think happened. I haven't had the chance to try to reliably reproduce yet, but if someone wants me to, I could give it a try. Anyway, here goes:

1. Create a folder foo and a subfolder bar inside it
2. Create a huge number of files (4700+ in my case, doesn't have to be done on Android) in bar
3. Open foo and bar in the Android app so it's cached.
4. On another device (or in the web GUI), create a new subfolder in foo called baz and move bar into baz.
5. Open foo in the Android app again, and it crashes.

*** CAUSE OF ERROR ***

android.database.sqlite.SQLiteBlobTooBigException: Row too big to fit into CursorWindow requiredPos=3157, totalRows=1560
    at android.database.sqlite.SQLiteConnection.nativeExecuteForCursorWindow(Native Method)
    at android.database.sqlite.SQLiteConnection.executeForCursorWindow(SQLiteConnection.java:942)
    at android.database.sqlite.SQLiteSession.executeForCursorWindow(SQLiteSession.java:838)
    at android.database.sqlite.SQLiteQuery.fillWindow(SQLiteQuery.java:62)
    at android.database.sqlite.SQLiteCursor.fillWindow(SQLiteCursor.java:161)
    at android.database.sqlite.SQLiteCursor.onMove(SQLiteCursor.java:131)
    at android.database.AbstractCursor.moveToPosition(AbstractCursor.java:249)
    at android.database.AbstractCursor.moveToNext(AbstractCursor.java:281)
    at com.owncloud.android.providers.FileContentProvider.deleteDirectory(FileContentProvider.java:191)
    at com.owncloud.android.providers.FileContentProvider.delete(FileContentProvider.java:135)
    at com.owncloud.android.providers.FileContentProvider.deleteDirectory(FileContentProvider.java:185)
    at com.owncloud.android.providers.FileContentProvider.delete(FileContentProvider.java:135)
    at com.owncloud.android.providers.FileContentProvider.delete(FileContentProvider.java:115)
    at android.content.ContentProviderOperation.applyInternal(ContentProviderOperation.java:342)
    at android.content.ContentProviderOperation.apply(ContentProviderOperation.java:314)
    at com.owncloud.android.providers.FileContentProvider.applyBatch(FileContentProvider.java:671)
    at android.content.ContentProvider.applyBatch(ContentProvider.java:2179)
    at android.content.ContentProvider$Transport.applyBatch(ContentProvider.java:398)
    at android.content.ContentProviderClient.applyBatch(ContentProviderClient.java:532)
    at android.content.ContentProviderClient.applyBatch(ContentProviderClient.java:520)
    at android.content.ContentResolver.applyBatch(ContentResolver.java:1915)
    at com.owncloud.android.datamodel.FileDataStorageManager.saveFolder(FileDataStorageManager.java:407)
    at com.owncloud.android.operations.RefreshFolderOperation.synchronizeData(RefreshFolderOperation.java:478)
    at com.owncloud.android.operations.RefreshFolderOperation.fetchAndSyncRemoteFolder(RefreshFolderOperation.java:369)
    at com.owncloud.android.operations.RefreshFolderOperation.run(RefreshFolderOperation.java:228)
    at com.owncloud.android.lib.common.operations.RemoteOperation.run(RemoteOperation.java:357)
    at java.lang.Thread.run(Thread.java:919)

************ APP INFORMATION ************
ID: com.nextcloud.client
Version: 30110190
Build flavor: gplay

************ DEVICE INFORMATION ************
Brand: OnePlus
Device: OnePlus8Pro
Model: IN2023
Id: QKQ1.191222.002
Product: OnePlus8Pro_EEA

************ FIRMWARE ************
SDK: 29
Release: 10
Incremental: 2004111413

Expected behaviour

The app shouldn't crash.

Actual behaviour

The app crashes over and over again when opening the foo folder.

Environment data

Android version: 10

Device model: OnePlus 8 Pro

Stock or customized system: stock

Nextcloud app version: 3.11.1

Nextcloud server version: 18.0.3

Reverse proxy: nginx

[slovdahl]

• Clearing the cached data of the Android app didn't help.
• After moving the files back to the original location the Android app doesn't crash any more.

Sounds like this could be similar to #5900, #5759, #5481 and possibly others. Sorry for that, I just used the link that the app gave me along with the stack trace. Feel free to close this one if you feel it's redundant.

[tobiasKaminsky]

Thanks for the clear way on how to reproduce the issue.
I will try it soon.

[slovdahl]

Thank you! Bear in mind that this happened in a real scenario and is what I think happened. If you aren't able to reproduce it yourself, I could try to artificially reproduce it myself as well.

[tobiasKaminsky]

I created now a test which fails with same error message like you have.

This fails reliable if count is >= 5000;
https://github.com/nextcloud/android/pull/5918/files#diff-7146121379c37c7fda4c6542bdd37597R63