Add EV_RECEIPT to kevents.

EV_RECEIPT is useful to disambiguating error conditions when multiple
events structures are passed to kevent(2).  The error code is returned
in the data field and EV_ERROR is set.

Approved by:	rwatson (co-mentor)

1 files changed, 9 insertions, 0 deletions

diff --git a/lib/libc/sys/kqueue.2 b/lib/libc/sys/kqueue.2
index 63f5a4d..e899a1b 100644
--- a/lib/libc/sys/kqueue.2
+++ b/lib/libc/sys/kqueue.2
@@ -211,6 +211,15 @@ Removes the event from the kqueue.
 Events which are attached to
 file descriptors are automatically deleted on the last close of
 the descriptor.
+.It EV_RECEIPT
+This flag is useful for making bulk changes to a kqueue without draining
+any pending events.
+When passed as input, it forces
+.Dv EV_ERROR
+to always be returned.
+When a filter is successfully added the 
+.Va data
+field will be zero.
 .It EV_ONESHOT
 Causes the event to return only the first occurrence of the filter
 being triggered.