[src/trunk]: src/lib/libc/sys Update the EV_SET() description with newer impl...

[kamil <kamil%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/ae3d50f606d0
branches:  trunk
changeset: 354184:ae3d50f606d0
user:      kamil <kamil%NetBSD.org@localhost>
date:      Tue Jun 06 17:01:59 2017 +0000

description:
Update the EV_SET() description with newer implementation.

EV_SET(2) is a macro again, that wraps an inline function which is still
new in NetBSD 8.0.

Sponsored by <The NetBSD Foundation>

diffstat:

 lib/libc/sys/kqueue.2 |  21 +++++++++++++++------
 1 files changed, 15 insertions(+), 6 deletions(-)

diffs (40 lines):

diff -r fa951ec429dd -r ae3d50f606d0 lib/libc/sys/kqueue.2
--- a/lib/libc/sys/kqueue.2     Tue Jun 06 15:58:59 2017 +0000
+++ b/lib/libc/sys/kqueue.2     Tue Jun 06 17:01:59 2017 +0000
@@ -1,4 +1,4 @@
-.\"    $NetBSD: kqueue.2,v 1.41 2017/05/31 01:03:01 kamil Exp $
+.\"    $NetBSD: kqueue.2,v 1.42 2017/06/06 17:01:59 kamil Exp $
 .\"
 .\" Copyright (c) 2000 Jonathan Lemon
 .\" All rights reserved.
@@ -155,10 +155,19 @@
 .Fa eventlist .
 .Pp
 .Fn EV_SET
-is a static inline function which is provided for ease of initializing a
-kevent structure.
-Its original form was a preprocessor macro,
-which caused bugs in third party code.
+is a macro which is provided for ease of initializing a kevent structure.
+It wraps an internal static inline function to prevent preprocessor misuse.
+In the past this code would behave incorrectly and damage process's memory,
+if incrementation or decrementation would be used as the first argument.
+This example has been taken from LLDB, that caused the memory corruption and
+inspired the
+.Nx
+developers for improving the implementation.
+.Bd -literal -offset indent
+EV_SET(&in_events[i++], fd.first, EVFILT_READ, EV_ADD, 0, 0, 0);
+.Ed
+.Pp
+This macro is now safe in all major BSDs.
 .Pp
 The
 .Va kevent
@@ -673,5 +682,5 @@
 .Nx 6.0 .
 .Pp
 .Fn EV_SET
-was converted from a macro to a static inline function in
+was converted from a macro implementation to the macro wrapping a static inline function in
 .Nx 8.0 .