new manual page BIO_dup_chain(3)

1 files changed, 8 insertions, 3 deletions

diff --git a/src/lib/libcrypto/man/BIO_f_null.3 b/src/lib/libcrypto/man/BIO_f_null.3
index 755f37dae7..a74726e1ff 100644
--- a/src/lib/libcrypto/man/BIO_f_null.3
+++ b/src/lib/libcrypto/man/BIO_f_null.3
@@ -1,5 +1,5 @@
-.\"     $OpenBSD: BIO_f_null.3,v 1.9 2018/05/01 17:05:05 schwarze Exp $
-.\"     OpenSSL e117a890 Sep 14 12:14:41 2000 +0000
+.\" $OpenBSD: BIO_f_null.3,v 1.10 2022/12/18 19:35:36 schwarze Exp $
+.\" full merge up to: OpenSSL e9b77246 Jan 20 19:58:49 2017 +0100
 .\"
 .\" This file was written by Dr. Stephen Henson <steve@openssl.org>.
 .\" Copyright (c) 2000 The OpenSSL Project.  All rights reserved.
@@ -48,7 +48,7 @@
 .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 .\" OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd $Mdocdate: May 1 2018 $
+.Dd $Mdocdate: December 18 2022 $
 .Dt BIO_F_NULL 3
 .Os
 .Sh NAME
@@ -69,6 +69,11 @@ As may be apparent, a null filter BIO is not particularly useful.
 All requests to a null filter BIO are passed through to the next BIO
 in the chain: this means that a BIO chain containing a null filter BIO
 behaves just as though the BIO was not there.
+.Pp
+A chain containing a null filter BIO cannot be copied with
+.Xr BIO_dup_chain 3 ,
+and any attempt to do so fails and returns
+.Dv NULL .
 .Sh RETURN VALUES
 .Fn BIO_f_null
 returns the null filter BIO method.