Fix a file descriptor close race in kqueue_register()

After inserting a knote, check that the associated file descriptor
still references the same file. Remove the knote if the descriptor
has changed because otherwise the kqueue becomes inconsistent with
the file descriptor table.

There is an analogous race in fcntl(F_SETLK). It is already handled,
but the code can be simplified by using the same check as in
kqueue_register().

Fix inspired by DragonFly BSD

OK mpi@, anton@

0 files changed, 0 insertions, 0 deletions