dup and dup2 of a Windows directory descriptor threw. FreeBSD's
kern_dup makes both descriptors refer to one open file, so they share
the read position; the duplicate now points at the same DirectoryState,
which getdents and lseek go through, and keeps it after the original
is closed.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
lseek on a non-directory descriptor no longer takes the directory table lock when no directory is open, and a listing is read under the descriptor's own lock. SEEK_CUR with offset 0 only reports the position, and an overflowing SEEK_CUR offset reports EOVERFLOW.