Document ERR_load_BN_strings(3).

jsing@ confirmed that this function is public and worth documenting.

This page needs much more work, it is outrageously incomplete and
unclear.  For example, it remains unexplained what error strings
are, what "registering" means and what the benefit for the application
is, what happens if it is not done, or what happens if an error
occurs after calling ERR_free_strings(3).  I tried to read the code,
but it is so contorted that i postponed that work.  For example,
it looks like there are hooks for applications to replace the
functions used for registering strings by other, application-supplied
functions, and, of course, there are many levels of macro and
function wrappers.

For now, i only documented the most obvious BUGS.

1 files changed, 47 insertions, 11 deletions

diff --git a/lib/libcrypto/man/ERR_load_crypto_strings.3 b/lib/libcrypto/man/ERR_load_crypto_strings.3
index 213fb662221..812258f60af 100644
--- a/lib/libcrypto/man/ERR_load_crypto_strings.3
+++ b/lib/libcrypto/man/ERR_load_crypto_strings.3
@@ -1,7 +1,24 @@
-.\"	$OpenBSD: ERR_load_crypto_strings.3,v 1.4 2016/11/23 17:59:29 schwarze Exp $
+.\"	$OpenBSD: ERR_load_crypto_strings.3,v 1.5 2017/01/26 04:37:08 schwarze Exp $
 .\"	OpenSSL a528d4f0 Oct 27 13:40:11 2015 -0400
 .\"
-.\" This file was written by Ulf Moeller <ulf@openssl.org>.
+.\" This file is a derived work.
+.\" The changes are covered by the following Copyright and license:
+.\"
+.\" Copyright (c) 2017 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 Ulf Moeller <ulf@openssl.org>.
 .\" Copyright (c) 2000 The OpenSSL Project.  All rights reserved.
 .\"
 .\" Redistribution and use in source and binary forms, with or without
@@ -48,13 +65,14 @@
 .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 .\" OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd $Mdocdate: November 23 2016 $
+.Dd $Mdocdate: January 26 2017 $
 .Dt ERR_LOAD_CRYPTO_STRINGS 3
 .Os
 .Sh NAME
 .Nm ERR_load_crypto_strings ,
-.Nm SSL_load_error_strings ,
-.Nm ERR_free_strings
+.Nm ERR_free_strings ,
+.Nm ERR_load_BN_strings ,
+.Nm SSL_load_error_strings
 .Nd load and free OpenSSL error strings
 .Sh SYNOPSIS
 .In openssl/err.h
@@ -62,6 +80,9 @@
 .Fn ERR_load_crypto_strings void
 .Ft void
 .Fn ERR_free_strings void
+.In openssl/bn.h
+.Ft void
+.Fn ERR_load_BN_strings void
 .In openssl/ssl.h
 .Ft void
 .Fn SSL_load_error_strings void
@@ -75,18 +96,25 @@ does the same, but also registers the
 .Xr ssl 3
 error strings.
 .Pp
+.Fn ERR_load_BN_strings
+only registers the error strings for the
+.Vt BIGNUM
+part of the library, i.e. the functions documented in
+.Xr BN_new 3
+and in the manual pages referenced from there.
+That may be useful if no other parts of the crypto library
+are used by the program.
+Similar functions exist for other parts of the crypto library,
+but they are not yet documented.
+.Pp
+If the error strings were already loaded before, no action occurs.
+.Pp
 One of these functions should be called before generating textual error
 messages.
 However, this is not required when memory usage is an issue.
 .Pp
 .Fn ERR_free_strings
 frees all previously loaded error strings.
-.Sh RETURN VALUES
-.Fn ERR_load_crypto_strings ,
-.Fn SSL_load_error_strings ,
-and
-.Fn ERR_free_strings
-return no values.
 .Sh SEE ALSO
 .Xr ERR 3 ,
 .Xr ERR_error_string 3
@@ -96,3 +124,11 @@ return no values.
 and
 .Fn ERR_free_strings
 are available in all versions of SSLeay and OpenSSL.
+.Sh BUGS
+Even though the error strings are already compiled into the object
+code of the library as static strings, these functions store them
+again using dynamically allocated memory on the heap.
+That may fail if insufficient memory is available,
+but these functions do not report such errors.
+Instead, they fail silently, possibly having registered none or only
+a part of the strings requested.