Fix two bugs (at least 13 year old) of the [+]offset[.][Bb] XSI offset syntax:

Make it work with decimal offsets and with standard input.
Also fix the documentation; it showed the argument in the wrong place.
According to XSI (and our code), it must come *after* the filename,
and it can be used with at most one single filename.
Remove it from the SYNOPSIS; it only provides a subset of -j,
is less standard and contains lots of traps (i counted 7 distinct traps).
Instead, mention it as an alternative below -j where it belongs.
Also fix some markup quirks (that's what originally made me find this mess).
Feedback and OK sobrado@ jmc@.

2 files changed, 22 insertions, 15 deletions

diff --git a/usr.bin/hexdump/od.1 b/usr.bin/hexdump/od.1
index b8ba9379b3f..dce74fc0cca 100644
--- a/usr.bin/hexdump/od.1
+++ b/usr.bin/hexdump/od.1
@@ -1,4 +1,4 @@
-.\"  $OpenBSD: od.1,v 1.30 2014/04/19 09:24:28 sobrado Exp $
+.\"  $OpenBSD: od.1,v 1.31 2015/09/16 08:47:26 schwarze Exp $
 .\"  $NetBSD: od.1,v 1.16 2001/12/07 01:23:42 bjh21 Exp $
 .\"
 .\" Copyright (c) 2001 The NetBSD Foundation, Inc.
@@ -28,7 +28,7 @@
 .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 .\" POSSIBILITY OF SUCH DAMAGE.
 .\"/
-.Dd $Mdocdate: April 19 2014 $
+.Dd $Mdocdate: September 16 2015 $
 .Dt OD 1
 .Os
 .Sh NAME
@@ -36,22 +36,12 @@
 .Nd octal, decimal, hex, ascii dump
 .Sh SYNOPSIS
 .Nm od
-.Bk -words
 .Op Fl aBbcDdeFfHhIiLlOosvXx
 .Op Fl A Ar base
 .Op Fl j Ar offset
 .Op Fl N Ar length
 .Op Fl t Ar type_string
-.Sm off
-.Oo
-.Op Cm \&+
-.Li offset
-.Op Cm \&.
-.Op Cm Bb
-.Sm on
-.Oc
 .Op Ar
-.Ek
 .Sh DESCRIPTION
 The
 .Nm
@@ -166,6 +156,21 @@ causes it to be interpreted as a multiple of
 or
 .Li 1048576 ,
 respectively.
+.Pp
+As an alternative to
+.Nm
+.Fl j Ar offset
+.Op Ar file ,
+the X/Open System Interfaces syntax
+.Nm
+.Op Ar file
+.Sm off
+.Op Cm \&+
+.Ar offset
+.Op Cm \&.
+.Op Cm Bb
+.Sm on
+is also supported.
 .It Fl L
 Same as
 .Fl I .
diff --git a/usr.bin/hexdump/odsyntax.c b/usr.bin/hexdump/odsyntax.c
index 2854bf00e99..7af2fa5b5d8 100644
--- a/usr.bin/hexdump/odsyntax.c
+++ b/usr.bin/hexdump/odsyntax.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: odsyntax.c,v 1.25 2014/04/19 09:28:20 sobrado Exp $	*/
+/*	$OpenBSD: odsyntax.c,v 1.26 2015/09/16 08:47:26 schwarze Exp $	*/
 /*	$NetBSD: odsyntax.c,v 1.15 2001/12/07 15:14:29 bjh21 Exp $	*/
 
 /*-
@@ -299,7 +299,7 @@ oldusage(void)
 	extern char *__progname;
 	fprintf(stderr, "usage: %s [-aBbcDdeFfHhIiLlOosvXx] [-A base] "
 	    "[-j offset] [-N length]\n"
-	    "\t[-t type_string] [[+]offset[.][Bb]] [file ...]\n", __progname);
+	    "\t[-t type_string] [file ...]\n", __progname);
 	exit(1);
 }
 
@@ -371,6 +371,8 @@ odoffset(int argc, char ***argvp)
 		return;
 	}
 
+	if (*p == '.')
+		++p;
 	if (*p) {
 		if (*p == 'B') {
 			skip *= 1024;
@@ -397,7 +399,7 @@ odoffset(int argc, char ***argvp)
 	}
 
 	/* Terminate file list. */
-	(*argvp)[1] = NULL;
+	(*argvp)[argc > 1] = NULL;
 }
 
 static void