From bbae91361a027693030d57d9f83118f3130f21cc Mon Sep 17 00:00:00 2001
From: schwarze <schwarze@openbsd.org>
Date: Tue, 20 Dec 2022 14:55:45 +0000
Subject: [PATCH] document BIO_fd_non_fatal_error(3) and BIO_fd_should_retry(3)

---
 lib/libcrypto/man/BIO_s_fd.3 | 84 ++++++++++++++++++++++++++++++++----
 1 file changed, 76 insertions(+), 8 deletions(-)

diff --git a/lib/libcrypto/man/BIO_s_fd.3 b/lib/libcrypto/man/BIO_s_fd.3
index 5ac33e77ee6..a22ba5d6039 100644
--- a/lib/libcrypto/man/BIO_s_fd.3
+++ b/lib/libcrypto/man/BIO_s_fd.3
@@ -1,7 +1,24 @@
-.\"	$OpenBSD: BIO_s_fd.3,v 1.9 2018/05/01 17:05:05 schwarze Exp $
-.\"	OpenSSL 9b86974e Aug 17 15:21:33 2015 -0400
+.\" $OpenBSD: BIO_s_fd.3,v 1.10 2022/12/20 14:55:45 schwarze Exp $
+.\" full merge up to: OpenSSL 99d63d46 Oct 26 13:56:48 2016 -0400
 .\"
-.\" This file was written by Dr. Stephen Henson <steve@openssl.org>.
+.\" This file is a derived work.
+.\" The changes are covered by the following Copyright and license:
+.\"
+.\" Copyright (c) 2022 Ingo Schwarze <schwarze@openbsd.org>
+.\"
+.\" Permission to use, copy, modify, and distribute this software for any
+.\" purpose with or without fee is hereby granted, provided that the above
+.\" copyright notice and this permission notice appear in all copies.
+.\"
+.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+.\"
+.\" The original file was written by Dr. Stephen Henson <steve@openssl.org>.
 .\" Copyright (c) 2000 The OpenSSL Project.  All rights reserved.
 .\"
 .\" Redistribution and use in source and binary forms, with or without
@@ -48,14 +65,16 @@
 .\" 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 20 2022 $
 .Dt BIO_S_FD 3
 .Os
 .Sh NAME
 .Nm BIO_s_fd ,
 .Nm BIO_set_fd ,
 .Nm BIO_get_fd ,
-.Nm BIO_new_fd
+.Nm BIO_new_fd ,
+.Nm BIO_fd_non_fatal_error ,
+.Nm BIO_fd_should_retry
 .Nd file descriptor BIO
 .Sh SYNOPSIS
 .In openssl/bio.h
@@ -79,6 +98,10 @@
 .Fa "int fd"
 .Fa "int close_flag"
 .Fc
+.Ft int
+.Fn BIO_fd_non_fatal_error "int errnum"
+.Ft int
+.Fn BIO_fd_should_retry "int retval"
 .Sh DESCRIPTION
 .Fn BIO_s_fd
 returns the file descriptor BIO method.
@@ -140,6 +163,25 @@ returns a file descriptor BIO using
 and
 .Fa close_flag .
 .Pp
+.Fn BIO_fd_non_fatal_error
+determines whether the error status code
+.Fa errnum
+represents a recoverable error.
+.Fn BIO_fd_should_retry
+determines whether a recoverable error occurred by inspecting both
+.Xr errno 2
+and
+.Fa retval ,
+which is supposed to usually be
+the return value of a previously called function like
+.Xr BIO_read 3
+or
+.Xr BIO_write 3 .
+These two functions are mostly used internally; in application code,
+it is usually easier and more robust to use
+.Xr BIO_should_retry 3 ,
+which works for any BIO type.
+.Pp
 The behaviour of
 .Xr BIO_read 3
 and
@@ -181,6 +223,27 @@ returns the newly allocated
 or
 .Dv NULL
 if an error occurred.
+.Pp
+.Fn BIO_fd_non_fatal_error
+returns 1 if
+.Fa errnum
+is
+.Dv EAGAIN ,
+.Dv EALREADY ,
+.Dv EINPROGRESS ,
+.Dv EINTR ,
+or
+.Dv ENOTCONN
+and 0 otherwise, even if
+.Fa errnum
+is 0.
+.Pp
+.Fn BIO_fd_should_retry
+returns 1 if
+.Fn BIO_fd_non_fatal_error errno
+is 1 and
+.Fa retval
+is either 0 or \-1, or 0 otherwise.
 .Sh EXAMPLES
 This is a file descriptor BIO version of "Hello World":
 .Bd -literal -offset indent
@@ -193,14 +256,19 @@ BIO_free(out);
 .Xr BIO_new 3 ,
 .Xr BIO_read 3 ,
 .Xr BIO_s_socket 3 ,
-.Xr BIO_seek 3
+.Xr BIO_seek 3 ,
+.Xr BIO_should_retry 3
 .Sh HISTORY
 .Fn BIO_s_fd ,
 .Fn BIO_set_fd ,
 and
 .Fn BIO_get_fd
-first appeared in SSLeay 0.6.0.
+first appeared in SSLeay 0.6.0,
+.Fn BIO_fd_should_retry
+in SSLeay 0.6.5, and
 .Fn BIO_new_fd
-first appeared in SSLeay 0.8.0.
+and
+.Fn BIO_fd_non_fatal_error
+in SSLeay 0.8.0.
 All these functions have been available since
 .Ox 2.4 .
-- 
2.20.1