BugFix - NPE internalFolderSyncTimestamp & File Existence Check

[alperozturk96]

• Tests written, or not not needed

Changes

1. Fix the NullPointerException (NPE) for internalFolderSyncTimestamp.
2. Check for file existence in the InternalTwoWaySyncWork worker; otherwise, it will throw an exception.

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During my tests, I wasn’t able to reproduce the issue; however, some users with version 3.30.0 Final have already experienced the crash. It means some OCFile already saved into the internal storage via null value.

Potential fix could be in this PR:

Changing following set function, but I’m not sure.

ocFile.setInternalFolderSyncTimestamp(fileEntity.getInternalTwoWaySync()); ->

ocFile.setInternalFolderSyncTimestamp(nullToZero(fileEntity.getInternalTwoWaySync()));

To prevent further crashes, I checked nullability of the Long object and return non-null object. Alternative solution can be we can convert the Long object to long primitive type.

[superzanti]

Thank you!

This fixed it for me.

[tobiasKaminsky]

Draft or ready to review? 🙈

[alperozturk96]

@tobiasKaminsky We have to test two-way sync properly before merge this PR, so it's a draft.

[tobiasKaminsky]

If folder does not yet exist, we can still compute it:

• localFolderSize is 0, as nothing was downloaded yet

Rest of computation would then still apply.

[alperozturk96]

0ec1a97

[alperozturk96]

If the file does not exist, freeSpaceLeft will be 0 because file.getFreeSpace() will return 0.

Therefore, the condition if (freeSpaceLeft < (remoteFolderSize - localFolderSize)) will evaluate to true, as 0 < some_value - 0 is always true, causing the worker to be canceled. I assume remoteFolderSize going to be bigger than 0.

[github-actions]

APK file: https://www.kaminsky.me/nc-dev/android-artifacts/13612.apk



To test this change/fix you can simply download above APK file and install and test it in parallel to your existing Nextcloud app.

[github-actions]

Codacy

Lint

Type	master	PR
Warnings	59	59
Errors	3	3

SpotBugs

Category	Base	New
Bad practice	64	64
Correctness	63	63
Dodgy code	296	296
Experimental	1	1
Internationalization	7	7
Malicious code vulnerability	1	1
Multithreaded correctness	6	6
Performance	53	53
Security	18	18
Total	509	509