Document BN_abs_is_word(3).

While here, add the missing "const" qualifier to the second parameter
of BN_is_word(3) - even though i doubt that marking an integral type
parameter as "const" serves any significant purpose...

Note that the OpenSSL documentation for this function that Billy
Brumley committed on August 4, 2021 is actually wrong.  Essentially,
it says "BN_abs_is_word() test[s] if a equals ... |w|."  Now pray
tell me, what exactly is the point of taking the absolute value of
an unsigned integer number?  To compensate for the obvious absurdity
of his patch, Billy made a point of getting *three* OKs from rather
notable people: Pauli Dale, Nicola Tuveri, and Dmitry Belyavskiy.

I believe this is a striking example of the cavalier attitude some
projects put on display when it comes to documentation, and also a
striking example of how bad documentation can occasionally be worse
than no documentation at all, because the OpenSSL manual page will
now thoroughly confuse anyone reading it.

SCNR pointing out this (hopefully unintentional) hilarity - or is
this an attempt at trolling the readers of their documentation?
If it is, they certainly got me.

1 files changed, 21 insertions, 5 deletions

diff --git a/src/lib/libcrypto/man/BN_cmp.3 b/src/lib/libcrypto/man/BN_cmp.3
index 5c1fad64a0..9ca73a626f 100644
--- a/src/lib/libcrypto/man/BN_cmp.3
+++ b/src/lib/libcrypto/man/BN_cmp.3
@@ -1,5 +1,5 @@
-.\"     $OpenBSD: BN_cmp.3,v 1.8 2021/12/06 19:45:27 schwarze Exp $
-.\"     OpenSSL b97fdb57 Nov 11 09:33:09 2016 +0100
+.\" $OpenBSD: BN_cmp.3,v 1.9 2021/12/18 21:11:50 schwarze Exp $
+.\" full merge up to: OpenSSL 5b31b9df Aug 4 10:45:52 2021 +0300
 .\"
 .\" This file was written by Ulf Moeller <ulf@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: December 6 2021 $
+.Dd $Mdocdate: December 18 2021 $
 .Dt BN_CMP 3
 .Os
 .Sh NAME
@@ -57,6 +57,7 @@
 .Nm BN_is_zero ,
 .Nm BN_is_one ,
 .Nm BN_is_word ,
+.Nm BN_abs_is_word ,
 .Nm BN_is_odd
 .Nd BIGNUM comparison and test functions
 .Sh SYNOPSIS
@@ -82,7 +83,12 @@
 .Ft int
 .Fo BN_is_word
 .Fa "const BIGNUM *a"
-.Fa "BN_ULONG w"
+.Fa "const BN_ULONG w"
+.Fc
+.Ft int
+.Fo BN_abs_is_word
+.Fa "const BIGNUM *a"
+.Fa "const BN_ULONG w"
 .Fc
 .Ft int
 .Fo BN_is_odd
@@ -106,6 +112,11 @@ test if
 equals 0, 1, or
 .Fa w
 respectively.
+.Fn BN_abs_is_word
+tests if the absolute value of
+.Fa a
+equals
+.Fa w .
 .Fn BN_is_odd
 tests if a is odd.
 .Sh RETURN VALUES
@@ -125,6 +136,7 @@ and
 .Fn BN_is_zero ,
 .Fn BN_is_one ,
 .Fn BN_is_word ,
+.Fn BN_abs_is_word ,
 and
 .Fn BN_is_odd
 return 1 if the condition is true, 0 otherwise.
@@ -140,5 +152,9 @@ and
 first appeared in SSLeay 0.5.1.
 .Fn BN_is_odd
 first appeared in SSLeay 0.8.0.
-All these functions have been available since
+These functions have been available since
 .Ox 2.4 .
+.Pp
+.Fn BN_abs_is_word
+first appeared in OpenSSL 0.9.7 and has been available since
+.Ox 3.2 .