Panick on log rotation on Windows #200
Description
Hello,
FimService panicked on windows today. Log file provide a hint at what happened.
2025-08-06T07:05:55.6435 [ERROR] thread '<unnamed>' panicked at '(log) Unable to open events log file.: Os { code: 32, kind: Uncategorized, message: "The process cannot access the file because it is being used by another process." }': src\monitorevent.rs:88
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15: BuildSecurityDescriptorForSharingAccessEx
16: BaseThreadInitThunk
17: RtlUserThreadStart
2025-08-06T07:05:55.6556 [ERROR] thread 'FIM_HashScanner' panicked at '(hashevent::log) Unable to open events log file.: Os { code: 32, kind: Uncategorized, message: "The process cannot access the file because it is being used by another process." }': src\hashevent.rs:44
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17: BaseThreadInitThunk
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2025-08-06T07:05:55.7572 [INFO] File C:\ProgramData\fim\events.json rotated.
Here's what's happening:
Two different threads are trying to access the same log file (events.json) simultaneously, causing a file locking conflict.
Breaking Down the Errors
Error 1 - Main Monitor Thread:
Thread:
Location: src\monitorevent.rs:88
Issue: Cannot open the events log file
Error 2 - Hash Scanner Thread:
Thread: FIM_HashScanner
Location: src\hashevent.rs:44
Issue: Same file access problem
Key Error Details:
Error Code 32: Windows system error meaning "file is in use by another process"
File: C:\ProgramData\fim\events.json
Root Cause: Multiple threads trying to write and rotate the same log file without proper synchronization
The Core Problem
Fim implemented its own logging that miss critical feature such as thread synchronisation (?).
The Resolution
Use a standard logging library that support multi threading and can rotate log.