https://bugs.winehq.org/show_bug.cgi?id=57035
--- Comment #5 from Zeb Figura z.figura12@gmail.com --- (In reply to LIU Hao from comment #4)
(In reply to Zeb Figura from comment #3)
The last one is the situation we're dealing with here (process A is wineserver; C is correctly calculated to always round up). If POSIX guarantees this, then it's a host (Linux) bug. If POSIX does not guarantee this, then I don't think there's anything we can do.
This is clearly not a host issue. There is no such issue on Wine 6 on Linux Mint 21 but there is such an issue on Wine 9 on the same system.
Hmm, I'm not sure where things could be going wrong in Wine code, but it sounds like it may be bisectable then?