[NIFI-8020] TailFile can leave FileChannel open when handling NUL characters

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.13.0
• Fix Version/s: 1.13.0
• Component/s: Extensions
• Assignee: Tamas Palfy
• Reporter: Tamas Palfy
• Created: 17/Nov/20 19:05
• Updated: 17/Nov/20 23:27
• Resolved: 17/Nov/20 23:27

Description

In TailFile when REREAD_ON_NUL is set to 'true' and a NUL character is encountered, the processor aborts all processing and yields to try again later.
However the opened FileChannel is not stored in the states. Because of this the reader is not cleaned up later.
On Windows this prevents from deleting the tailed file. (On linux it seems the file still can be deleted. Leaving open the FileChannel is not good nonetheless.)

Fix: Store the reader in the states.

Issue Links

• is caused by: NIFI-7972 TailFile reading from NFS may introduce NUL characters.
• links to: GitHub Pull Request #4671