after enough complaints by POSIX sh advocates,

• make parsing numbers with leading digit-zero as octal independent of
  mksh/lksh and dependent on set -o posix; adjust manpages to match
• warn about these changes and why mksh uses 32-bit consistent arithmetics
  and point people to lksh for host-long undefined-behaviour arithmetics
• point out, explicitly, that it is *legal* for the operating environment
  to make 'print $((2147483647 + 1))' (on a 32-bit system; adjust for a
  64-bit system) to run 'rm -rf ~ /' instead

Makefile

@@ -1,4 +1,4 @@
-# $MirOS: src/bin/mksh/Makefile,v 1.119 2013/04/27 18:22:47 tg Exp $
+# $MirOS: src/bin/mksh/Makefile,v 1.120 2013/04/27 18:50:21 tg Exp $
 #-
 # Copyright (c) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010,
 #		2011, 2012, 2013
@@ -104,6 +104,9 @@ test-build-lksh: .PHONY
 	cd ${.CURDIR} && exec ${MAKE} lksh.cat1 test-build \
 	    _TBF=-L USE_PRINTF_BUILTIN=0
 
+bothmans: .PHONY
+	cd ${.CURDIR} && exec ${MAKE} MAN='lksh.1 mksh.1' __MANALL
+
 cleandir: clean-extra
 
 clean-extra: .PHONY
@@ -132,7 +135,7 @@ CLEANFILES+=	${MAN:S/$/.txt/} ${MAN:S/$/.txt.gz/}
 CATS_KW=	mksh, ksh, sh
 CATS_TITLE_mksh_1=mksh - The MirBSD Korn Shell
 cats: ${MANALL} ${MANALL:S/.cat/.ps/}
-.if "${MANALL:Nmksh.cat1}" != ""
+.if "${MANALL:Nlksh.cat1:Nmksh.cat1}" != ""
 .  error Adjust here.
 .endif
 .for _m _n in mksh 1

check.t

@@ -1,4 +1,4 @@
-# $MirOS: src/bin/mksh/check.t,v 1.607 2013/04/26 21:22:42 tg Exp $
+# $MirOS: src/bin/mksh/check.t,v 1.608 2013/04/27 18:50:21 tg Exp $
 # $OpenBSD: bksl-nl.t,v 1.2 2001/01/28 23:04:56 niklas Exp $
 # $OpenBSD: history.t,v 1.5 2001/01/28 23:04:56 niklas Exp $
 # $OpenBSD: read.t,v 1.3 2003/03/10 03:48:16 david Exp $
@@ -3779,22 +3779,17 @@ expected-stdout:
 ---
 name: integer-base-check-flat
 description:
-	Check behaviour does not match POSuX, because a not type-safe
-	scripting language has *no* business interpreting "010" as octal
-category: shell:legacy-no
+	Check behaviour does not match POSuX (except if set -o posix),
+	because a not type-safe scripting language has *no* business
+	interpreting the string "010" as octal numer eight (dangerous).
 stdin:
-	echo :$((10)).$((010)).$((0x10)).
+	echo 1 "$("$__progname" -c 'echo :$((10))/$((010)),$((0x10)):')" .
+	echo 2 "$("$__progname" -o posix -c 'echo :$((10))/$((010)),$((0x10)):')" .
+	echo 3 "$("$__progname" -o sh -c 'echo :$((10))/$((010)),$((0x10)):')" .
 expected-stdout:
-	:10.10.16.
----
-name: integer-base-check-flat-legacy
-description:
-	Check behaviour matches POSuX for LEGACY KSH
-category: shell:legacy-yes
-stdin:
-	echo :$((10)).$((010)).$((0x10)).
-expected-stdout:
-	:10.8.16.
+	1 :10/10,16: .
+	2 :10/8,16: .
+	3 :10/10,16: .
 ---
 name: integer-base-check-numeric-from
 description:

lksh.1

@@ -1,7 +1,22 @@
-.\" $MirOS: src/bin/mksh/lksh.1,v 1.1 2013/04/27 18:13:58 tg Exp $
+.\" $MirOS: src/bin/mksh/lksh.1,v 1.2 2013/04/27 18:50:24 tg Exp $
 .\"-
 .\" Copyright (c) 2008, 2009, 2010, 2012, 2013
 .\"	Thorsten “mirabilos” Glaser <tg@mirbsd.org>
+.\"
+.\" Provided that these terms and disclaimer and all copyright notices
+.\" are retained or reproduced in an accompanying document, permission
+.\" is granted to deal in this work without restriction, including un‐
+.\" limited rights to use, publicly perform, distribute, sell, modify,
+.\" merge, give away, or sublicence.
+.\"
+.\" This work is provided “AS IS” and WITHOUT WARRANTY of any kind, to
+.\" the utmost extent permitted by applicable law, neither express nor
+.\" implied; without malicious intent or gross negligence. In no event
+.\" may a licensor, author or contributor be held liable for indirect,
+.\" direct, other damage, loss, or other issues arising in any way out
+.\" of dealing in the work, even if advised of the possibility of such
+.\" damage or existence of a defect, except proven that it results out
+.\" of said person’s immediate fault when using the work as intended.
 .\"-
 .\" Try to make GNU groff and AT&T nroff more compatible
 .\" * ` generates ‘ in gnroff, so use \`
@@ -149,11 +164,15 @@
 .Ek
 .Sh DESCRIPTION
 .Nm
-is a command interpreter intended exclusive for running legacy
+is a command interpreter intended exclusively for running legacy
 shell scripts.
 It is built on
 .Nm mksh ;
 refer to its manual page for details on the scripting language.
+It is recommended to port scripts to
+.Nm mksh
+instead of relying on legacy or idiotic POSIX-mandated behaviour,
+since the MirBSD Korn Shell scripting language is much more consistent.
 .Sh LEGACY MODE
 .Nm
 has the following differences from
@@ -212,9 +231,6 @@ unlike
 .Nm ksh ,
 does not keep file descriptors \*(Gt 2 private.
 .It
-.Nm
-parses leading-zero numbers as octal (base 8).
-.It
 Integers use the host C environment's
 .Vt long
 type, not
@@ -246,13 +262,6 @@ tries to make a cross between a legacy bourne/posix compatibl-ish
 shell and a legacy pdksh-alike but
 .Dq legacy
 is not exactly specified.
-Parsing numbers with leading zero digits or
-.Dq 0x
-is relatively recent in all
-.Nm pdksh
-derivates, but supported here for completeness.
-It might make sense to make this a run-time option, but
-that might also be overkill.
 .Pp
 The
 .Ic set

mksh.1

@@ -1,4 +1,4 @@
-.\" $MirOS: src/bin/mksh/mksh.1,v 1.310 2013/04/26 21:22:47 tg Exp $
+.\" $MirOS: src/bin/mksh/mksh.1,v 1.311 2013/04/27 18:50:24 tg Exp $
 .\" $OpenBSD: ksh.1,v 1.146 2013/03/18 11:10:52 mpi Exp $
 .\"-
 .\" Copyright © 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009,
@@ -74,7 +74,7 @@
 .\" with -mandoc, it might implement .Mx itself, but we want to
 .\" use our own definition. And .Dd must come *first*, always.
 .\"
-.Dd $Mdocdate: April 26 2013 $
+.Dd $Mdocdate: April 27 2013 $
 .\"
 .\" Check which macro package we use, and do other -mdoc setup.
 .\"
@@ -2563,9 +2563,14 @@ Additionally, base-16 integers may be specified by prefixing them with
 in all forms of arithmetic expressions, except as numeric arguments to the
 .Ic test
 built-in command.
-It is discouraged to prefix numbers with a sole zero
-.Pq Sq 0 ,
-because some shells may interpret them as base-8 integers.
+Prefixing numbers with a sole digit zero
+.Pq Sq 0
+leads to the shell interpreting it as base-8 integer in
+.Ic posix
+mode
+.Em only ;
+historically, (pd)ksh has never done so either anyway,
+and it's unsafe to do that, but POSIX demands it nowadays.
 As a special
 .Nm mksh
 extension, numbers to the base of one are treated as either (8-bit
@@ -6334,6 +6339,16 @@ Use co-processes instead.
 foo \*(Ba bar \*(Ba read baz            # will not change $baz
 foo \*(Ba bar \*(Ba& read \-p baz        # will, however, do so
 .Ed
+.Pp
+.Nm mksh
+provides a consistent set of 32-bit integer arithmetics, both signed
+and unsigned, with defined wraparound and sign of the result of a modulo
+operation, even (defying POSIX) on 64-bit systems.
+If you require 64-bit integer arithmetics, use
+.Nm lksh Pq legacy mksh
+instead, but be aware that, in POSIX, it's legal for the OS to make
+.Li print $((2147483647 + 1))
+delete all files on your system, as it's Undefined Behaviour.
 .Sh BUGS
 Suspending (using \*(haZ) pipelines like the one below will only suspend
 the currently running part of the pipeline; in this example,
@@ -6345,7 +6360,7 @@ $ /bin/sleep 666 && echo fubar
 .Ed
 .Pp
 This document attempts to describe
-.Nm mksh\ R45
+.Nm mksh\ R46
 and up,
 compiled without any options impacting functionality, such as
 .Dv MKSH_SMALL ,

var.c

@@ -27,7 +27,7 @@
 #include <sys/sysctl.h>
 #endif
 
-__RCSID("$MirOS: src/bin/mksh/var.c,v 1.170 2013/04/07 14:11:54 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/var.c,v 1.171 2013/04/27 18:50:25 tg Exp $");
 
 /*-
  * Variables
@@ -495,14 +495,12 @@ getint(struct tbl *vp, mksh_ari_u *nump, bool arith)
 		base = 16;
 		have_base = true;
 	}
-#ifdef MKSH_LEGACY_MODE
-	if (arith && s[0] == '0' && ksh_isdigit(s[1]) &&
+	if (Flag(FPOSIX) && arith && s[0] == '0' && ksh_isdigit(s[1]) &&
 	    !(vp->flag & ZEROFIL)) {
 		/* interpret as octal (deprecated) */
 		base = 8;
 		have_base = true;
 	}
-#endif
 	while ((c = *s++)) {
 		if (c == '-') {
 			neg = true;