From 083af243491fbc60906c764c29680da53f918764 Mon Sep 17 00:00:00 2001
From: schwarze <schwarze@openbsd.org>
Date: Sat, 9 May 2015 20:36:18 +0000
Subject: [PATCH] For half and reverse line feeds, recognize SUSv2-style
 escape-digit sequences in the input stream in addition to traditional
 BSD-style escape-control-char sequences because traditional tools, for
 example Heirloom roff, produce SUSv2-style sequences.  Switch the encoding of
 forward half line feeds in the output of -f back to SUSv2 style because
 that's likely to work with more tools than the non-standard traditional
 BSD-style sequence.  Fully document these choices.

Issues originally reported by bapt at FreeBSD.
OK millert@ jmc@, and bapt@ also more or less agrees with the direction.
---
 usr.bin/col/col.1 | 25 ++++++++++++++++++++-----
 usr.bin/col/col.c | 28 ++++++++++++++++++++--------
 2 files changed, 40 insertions(+), 13 deletions(-)

diff --git a/usr.bin/col/col.1 b/usr.bin/col/col.1
index 4ced0737280..e1db48d1bfa 100644
--- a/usr.bin/col/col.1
+++ b/usr.bin/col/col.1
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: col.1,v 1.12 2014/10/17 21:10:56 schwarze Exp $
+.\"	$OpenBSD: col.1,v 1.13 2015/05/09 20:36:18 schwarze Exp $
 .\"	$NetBSD: col.1,v 1.4 1995/03/26 05:25:52 glass Exp $
 .\"
 .\" Copyright (c) 1990, 1993
@@ -33,7 +33,7 @@
 .\"
 .\"     @(#)col.1	8.1 (Berkeley) 6/29/93
 .\"
-.Dd $Mdocdate: October 17 2014 $
+.Dd $Mdocdate: May 9 2015 $
 .Dt COL 1
 .Os
 .Sh NAME
@@ -77,18 +77,33 @@ By default, 128 lines are buffered.
 Output multiple spaces instead of tabs.
 .El
 .Pp
-The control sequences for carriage motion that
+In the input stream,
 .Nm
-understands and their decimal ASCII values are listed in the following
-table:
+understands both the escape sequences of the form escape-digit
+mandated by
+.St -susv2
+and the traditional
+.Bx
+format escape-control-character.
+The control sequences for carriage motion and their ASCII values
+are as follows:
 .Pp
 .Bl -tag -width "escape-backspace" -compact
 .It escape\-bell
 Reverse line feed (27 then 7).
+.It escape\-digit\-7
+Reverse line feed (27 then 55).
 .It escape\-backspace
 Half reverse line feed (27 then 8).
+.It escape\-digit\-8
+Half reverse line feed (27 then 56).
 .It escape\-tab
 Half forward line feed (27 then 9).
+.It escape\-digit\-9
+Half forward line feed (27 then 57).
+In
+.Fl f
+mode, this sequence may also occur in the output stream.
 .It backspace
 Moves back one column (8); ignored in the first column.
 .It carriage return
diff --git a/usr.bin/col/col.c b/usr.bin/col/col.c
index 3f50cdbe735..f44d26aa8d1 100644
--- a/usr.bin/col/col.c
+++ b/usr.bin/col/col.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: col.c,v 1.16 2015/05/08 16:30:07 schwarze Exp $	*/
+/*	$OpenBSD: col.c,v 1.17 2015/05/09 20:36:18 schwarze Exp $	*/
 /*	$NetBSD: col.c,v 1.7 1995/09/02 05:48:50 jtc Exp $	*/
 
 /*-
@@ -50,9 +50,6 @@
 #define	SI	'\017'		/* shift in to normal character set */
 #define	SO	'\016'		/* shift out to alternate character set */
 #define	VT	'\013'		/* vertical tab (aka reverse line feed) */
-#define	RLF	'\007'		/* ESC-07 reverse line feed */
-#define	RHLF	'\010'		/* ESC-010 reverse half-line feed */
-#define	FHLF	'\011'		/* ESC-011 forward half-line feed */
 
 /* build up at least this many lines before flushing them out */
 #define	BUFFER_MARGIN		32
@@ -165,14 +162,25 @@ main(int argc, char *argv[])
 				cur_col = 0;
 				continue;
 			case ESC:		/* just ignore EOF */
+				/*
+				 * In the input stream, accept both the
+				 * XPG5 sequences ESC-digit and the
+				 * traditional BSD sequences ESC-ctrl.
+				 */
 				switch(getchar()) {
-				case RLF:
+				case '7':  /* reverse line feed */
+					/* FALLTHROUGH */
+				case '\007':
 					addto_lineno(&cur_line, -2);
 					break;
-				case RHLF:
+				case '8':  /* reverse half-line feed */
+					/* FALLTHROUGH */
+				case '\010':
 					addto_lineno(&cur_line, -1);
 					break;
-				case FHLF:
+				case '9':  /* forward half-line feed */
+					/* FALLTHROUGH */
+				case '\011':
 					addto_lineno(&cur_line, 1);
 					if (cur_line > max_line)
 						max_line = cur_line;
@@ -350,8 +358,12 @@ flush_blanks(void)
 	for (i = nb; --i >= 0;)
 		PUTC('\n');
 	if (half) {
+		/*
+		 * In the output stream, always generate
+		 * escape sequences conforming to XPG5.
+		 */
 		PUTC(ESC);
-		PUTC('\011');
+		PUTC('9');
 		if (!nb)
 			PUTC('\r');
 	}
-- 
2.20.1