XP64 shared a lot with Windows Server 2003. Perhaps the best Windows ever released.
7 and 2008R2 were pretty good too. All downhill from there..
https://pubs.opengroup.org/onlinepubs/009695299/functions/sy...
This is all a guess, the POSIX subsystems were a bit before my time and I've never actually used them. I just know how symlinks work on Windows/NTFS and when they were added.