From 56c196dc250f2d6e3ebcc66997bddb1e765784f8 Mon Sep 17 00:00:00 2001
From: jilles <jilles@FreeBSD.org>
Date: Tue, 22 Nov 2016 22:30:55 +0000
Subject: [PATCH] open(2): Clarify non-POSIX error when opening a symlink with
 O_NOFOLLOW.

We return [EMLINK] instead of [ELOOP] when trying to open a symlink with
O_NOFOLLOW, so that the original case of [ELOOP] can be distinguished. Code
like cmp -h and xz takes advantage of this.

PR:		214633
Reviewed by:	kib, imp
MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D8586
---
 lib/libc/sys/open.2 | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/lib/libc/sys/open.2 b/lib/libc/sys/open.2
index 0562bfd4bb88..c1701188b49a 100644
--- a/lib/libc/sys/open.2
+++ b/lib/libc/sys/open.2
@@ -28,7 +28,7 @@
 .\"     @(#)open.2	8.2 (Berkeley) 11/16/93
 .\" $FreeBSD$
 .\"
-.Dd September 30, 2016
+.Dd November 22, 2016
 .Dt OPEN 2
 .Os
 .Sh NAME
@@ -503,6 +503,22 @@ The
 .Fn openat
 function was introduced in
 .Fx 8.0 .
+.Sh STANDARDS
+These functions are specified by
+.St -p1003.1-2008 .
+.Fx
+sets
+.Va errno
+to
+.Er EMLINK instead of
+.Er ELOOP
+as specified by
+.Tn POSIX
+when
+.Dv O_NOFOLLOW
+is set in flags and the final component of pathname is a symbolic link
+to distinguish it from the case of too many symbolic link traversals
+in one of its non-final components.
 .Sh BUGS
 The Open Group Extended API Set 2 specification requires that the test
 for whether