resurrect mg' no-tab-mode

It's a mode that makes mg insert spaces up to the next tab stop upon
pressing TAB, along with the various tweaks needed in other places so
for e.g. auto-indent-mode also uses spaces.

This is not just an unifdef NOTAB: even under no-tab-mode mg should
consider literal TAB characters wide up to the next tab stop, while the
hidden code considered hard tabs to be just control character (i.e. ^I)
with width of two columns.  I'm also introducing the helper function
doindent() in utils.c to de-obfuscate the insertion of tabs/spaces until
the given column.

ok tb@

11 files changed, 44 insertions, 92 deletions

diff --git a/usr.bin/mg/basic.c b/usr.bin/mg/basic.c
index 4a170480432..ed7d475c494 100644
--- a/usr.bin/mg/basic.c
+++ b/usr.bin/mg/basic.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: basic.c,v 1.52 2023/03/08 04:43:11 guenther Exp $	*/
+/*	$OpenBSD: basic.c,v 1.53 2023/04/17 09:49:04 op Exp $	*/
 
 /* This file is in the public domain */
 
@@ -274,14 +274,9 @@ getgoal(struct line *dlp)
 	int c, i, col = 0;
 	char tmp[5];
 
-
 	for (i = 0; i < llength(dlp); i++) {
 		c = lgetc(dlp, i);
-		if (c == '\t'
-#ifdef	NOTAB
-		    && !(curbp->b_flag & BFNOTAB)
-#endif
-			) {
+		if (c == '\t') {
 			col |= 0x07;
 			col++;
 		} else if (ISCTRL(c) != FALSE) {
diff --git a/usr.bin/mg/cmode.c b/usr.bin/mg/cmode.c
index 9f5ffd72f80..e5442a2b6ed 100644
--- a/usr.bin/mg/cmode.c
+++ b/usr.bin/mg/cmode.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: cmode.c,v 1.20 2022/12/26 19:16:02 jmc Exp $ */
+/* $OpenBSD: cmode.c,v 1.21 2023/04/17 09:49:04 op Exp $ */
 /*
  * This file is in the public domain.
  *
@@ -245,11 +245,7 @@ getindent(const struct line *lp, int *curi)
 	for (lo = 0; lo < llength(lp); lo++) {
 		if (!isspace(c = lgetc(lp, lo)))
 			break;
-		if (c == '\t'
-#ifdef NOTAB
-		    && !(curbp->b_flag & BFNOTAB)
-#endif /* NOTAB */
-		    ) {
+		if (c == '\t') {
 			nicol |= 0x07;
 		}
 		nicol++;
@@ -414,11 +410,7 @@ findcolpos(const struct buffer *bp, const struct line *lp, int lo)
 
 	for (i = 0; i < lo; ++i) {
 		c = lgetc(lp, i);
-		if (c == '\t'
-#ifdef NOTAB
-		    && !(bp->b_flag & BFNOTAB)
-#endif /* NOTAB */
-			) {
+		if (c == '\t') {
 			col |= 0x07;
 			col++;
 		} else if (ISCTRL(c) != FALSE)
diff --git a/usr.bin/mg/def.h b/usr.bin/mg/def.h
index 5475b513036..8cfaada0300 100644
--- a/usr.bin/mg/def.h
+++ b/usr.bin/mg/def.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: def.h,v 1.178 2023/03/30 19:00:02 op Exp $	*/
+/*	$OpenBSD: def.h,v 1.179 2023/04/17 09:49:04 op Exp $	*/
 
 /* This file is in the public domain. */
 
@@ -285,9 +285,7 @@ struct buffer {
 
 #define BFCHG	0x01			/* Changed.			 */
 #define BFBAK	0x02			/* Need to make a backup.	 */
-#ifdef	NOTAB
 #define BFNOTAB 0x04			/* no tab mode			 */
-#endif
 #define BFOVERWRITE 0x08		/* overwrite mode		 */
 #define BFREADONLY  0x10		/* read only mode		 */
 #define BFDIRTY     0x20		/* Buffer was modified elsewhere */
@@ -676,9 +674,7 @@ int		 executemacro(int, int);
 /* modes.c X */
 int		 indentmode(int, int);
 int		 fillmode(int, int);
-#ifdef NOTAB
 int		 notabmode(int, int);
-#endif	/* NOTAB */
 int		 overwrite_mode(int, int);
 int		 set_default_mode(int,int);
 
diff --git a/usr.bin/mg/display.c b/usr.bin/mg/display.c
index 1751b5ead13..3814a0bd29b 100644
--- a/usr.bin/mg/display.c
+++ b/usr.bin/mg/display.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: display.c,v 1.50 2023/03/08 04:43:11 guenther Exp $	*/
+/*	$OpenBSD: display.c,v 1.51 2023/04/17 09:49:04 op Exp $	*/
 
 /* This file is in the public domain. */
 
@@ -317,11 +317,7 @@ vtputc(int c)
 	vp = vscreen[vtrow];
 	if (vtcol >= ncol)
 		vp->v_text[ncol - 1] = '$';
-	else if (c == '\t'
-#ifdef	NOTAB
-	    && !(curbp->b_flag & BFNOTAB)
-#endif
-	    ) {
+	else if (c == '\t') {
 		do {
 			vtputc(' ');
 		} while (vtcol < ncol && (vtcol & 0x07) != 0);
@@ -353,11 +349,7 @@ vtpute(int c)
 	vp = vscreen[vtrow];
 	if (vtcol >= ncol)
 		vp->v_text[ncol - 1] = '$';
-	else if (c == '\t'
-#ifdef	NOTAB
-	    && !(curbp->b_flag & BFNOTAB)
-#endif
-	    ) {
+	else if (c == '\t') {
 		do {
 			vtpute(' ');
 		} while (((vtcol + lbound) & 0x07) != 0 && vtcol < ncol);
@@ -516,11 +508,7 @@ update(int modelinecolor)
 	i = 0;
 	while (i < curwp->w_doto) {
 		c = lgetc(lp, i++);
-		if (c == '\t'
-#ifdef	NOTAB
-		    && !(curbp->b_flag & BFNOTAB)
-#endif
-			) {
+		if (c == '\t') {
 			curcol |= 0x07;
 			curcol++;
 		} else if (ISCTRL(c) != FALSE)
diff --git a/usr.bin/mg/funmap.c b/usr.bin/mg/funmap.c
index e1c59fa0fb4..fbf41217328 100644
--- a/usr.bin/mg/funmap.c
+++ b/usr.bin/mg/funmap.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: funmap.c,v 1.65 2022/12/26 19:16:02 jmc Exp $	*/
+/*	$OpenBSD: funmap.c,v 1.66 2023/04/17 09:49:04 op Exp $	*/
 
 /* This file is in the public domain */
 
@@ -157,9 +157,7 @@ static struct funmap functnames[] = {
 	{enewline, "newline", 1},
 	{lfindent, "newline-and-indent", 1},
 	{forwline, "next-line", 1},
-#ifdef NOTAB
 	{notabmode, "no-tab-mode", 0},
-#endif /* NOTAB */
 	{notmodified, "not-modified", 0},
 	{openline, "open-line", 1},
 	{nextwind, "other-window", 0},
@@ -212,9 +210,7 @@ static struct funmap functnames[] = {
 	{shellcommand, "shell-command", 1},
 	{piperegion, "shell-command-on-region", 1},
 	{shrinkwind, "shrink-window", 1},
-#ifdef NOTAB
 	{space_to_tabstop, "space-to-tabstop", 0},
-#endif /* NOTAB */
 	{splitwind, "split-window-vertically", 0},
 	{definemacro, "start-kbd-macro", 0},
 	{spawncli, "suspend-emacs", 0},
diff --git a/usr.bin/mg/keymap.c b/usr.bin/mg/keymap.c
index 6e47e4f66cb..83e8b54d921 100644
--- a/usr.bin/mg/keymap.c
+++ b/usr.bin/mg/keymap.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: keymap.c,v 1.60 2022/10/20 18:59:24 op Exp $	*/
+/*	$OpenBSD: keymap.c,v 1.61 2023/04/17 09:49:04 op Exp $	*/
 
 /* This file is in the public domain. */
 
@@ -464,7 +464,6 @@ static struct KEYMAPE (1) indntmap = {
 	}
 };
 
-#ifdef NOTAB
 static PF notab_tab[] = {
 	space_to_tabstop	/* ^I */
 };
@@ -479,7 +478,6 @@ static struct KEYMAPE (1) notabmap = {
 		}
 	}
 };
-#endif /* NOTAB */
 
 static struct KEYMAPE (1) overwmap = {
 	0,
@@ -511,9 +509,7 @@ struct maps_s	fundamental_mode = { (KEYMAP *)&fundmap, "fundamental" };
 static struct maps_s map_table[] = {
 	{(KEYMAP *) &fillmap, "fill",},
 	{(KEYMAP *) &indntmap, "indent",},
-#ifdef NOTAB
 	{(KEYMAP *) &notabmap, "notab",},
-#endif /* NOTAB */
 	{(KEYMAP *) &overwmap, "overwrite",},
 	{(KEYMAP *) &metamap, "esc prefix",},
 	{(KEYMAP *) &cXmap, "c-x prefix",},
diff --git a/usr.bin/mg/match.c b/usr.bin/mg/match.c
index d35fcfdb66e..cc293f1d8a9 100644
--- a/usr.bin/mg/match.c
+++ b/usr.bin/mg/match.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: match.c,v 1.22 2021/03/01 10:51:14 lum Exp $	*/
+/*	$OpenBSD: match.c,v 1.23 2023/04/17 09:49:04 op Exp $	*/
 
 /* This file is in the public domain. */
 
@@ -169,11 +169,7 @@ displaymatch(struct line *clp, int cbo)
 		bufo = 0;
 		for (cp = 0; cp < llength(clp); cp++) {
 			c = lgetc(clp, cp);
-			if (c != '\t'
-#ifdef NOTAB
-			    || (curbp->b_flag & BFNOTAB)
-#endif
-				)
+			if (c != '\t')
 				if (ISCTRL(c)) {
 					buf[bufo++] = '^';
 					buf[bufo++] = CCHR(c);
diff --git a/usr.bin/mg/mg.1 b/usr.bin/mg/mg.1
index beb85f1151f..d2edd289cc5 100644
--- a/usr.bin/mg/mg.1
+++ b/usr.bin/mg/mg.1
@@ -1,7 +1,7 @@
-.\"	$OpenBSD: mg.1,v 1.128 2023/03/29 07:29:17 op Exp $
+.\"	$OpenBSD: mg.1,v 1.129 2023/04/17 09:49:04 op Exp $
 .\" This file is in the public domain.
 .\"
-.Dd $Mdocdate: March 29 2023 $
+.Dd $Mdocdate: April 17 2023 $
 .Dt MG 1
 .Os
 .Sh NAME
@@ -738,9 +738,9 @@ Assumes tabs are every eight characters.
 Move forward
 .Va n
 lines.
-.\" .It no-tab-mode
-.\" Toggle notab mode.
-.\" In this mode, spaces are inserted rather than tabs.
+.It no-tab-mode
+Toggle notab mode.
+In this mode, spaces are inserted rather than tabs.
 .It not-modified
 Turn off the modified flag in the current buffer.
 .It open-line
diff --git a/usr.bin/mg/modes.c b/usr.bin/mg/modes.c
index 9d5e4ce5373..c95e1fdb03c 100644
--- a/usr.bin/mg/modes.c
+++ b/usr.bin/mg/modes.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: modes.c,v 1.21 2017/05/30 07:05:22 florian Exp $	*/
+/*	$OpenBSD: modes.c,v 1.22 2023/04/17 09:49:04 op Exp $	*/
 
 /* This file is in the public domain. */
 
@@ -78,7 +78,6 @@ fillmode(int f, int n)
 	return (changemode(f, n, "fill"));
 }
 
-#ifdef NOTAB
 int
 notabmode(int f, int n)
 {
@@ -93,7 +92,6 @@ notabmode(int f, int n)
 		curbp->b_flag ^= BFNOTAB;
 	return (TRUE);
 }
-#endif	/* NOTAB */
 
 int
 overwrite_mode(int f, int n)
@@ -162,13 +160,11 @@ set_default_mode(int f, int n)
 		else
 			defb_flag |= BFOVERWRITE;
 	}
-#ifdef NOTAB
 	if (strcmp(modebuf, "notab") == 0) {
 		if (n <= 0)
 			defb_flag &= ~BFNOTAB;
 		else
 			defb_flag |= BFNOTAB;
 	}
-#endif	/* NOTAB */
 	return (TRUE);
 }
diff --git a/usr.bin/mg/paragraph.c b/usr.bin/mg/paragraph.c
index b49a488a041..1455295f90d 100644
--- a/usr.bin/mg/paragraph.c
+++ b/usr.bin/mg/paragraph.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: paragraph.c,v 1.47 2023/03/08 04:43:11 guenther Exp $	*/
+/*	$OpenBSD: paragraph.c,v 1.48 2023/04/17 09:49:04 op Exp $	*/
 
 /* This file is in the public domain. */
 
@@ -412,11 +412,7 @@ fillword(int f, int n)
 		if (i == curwp->w_doto)
 			return selfinsert(f, n);
 		c = lgetc(curwp->w_dotp, i);
-		if (c == '\t'
-#ifdef NOTAB
-		    && !(curbp->b_flag & BFNOTAB)
-#endif
-			)
+		if (c == '\t')
 			col |= 0x07;
 		else if (ISCTRL(c) != FALSE)
 			++col;
diff --git a/usr.bin/mg/util.c b/usr.bin/mg/util.c
index 5899b8a29b0..5fb0bd757c9 100644
--- a/usr.bin/mg/util.c
+++ b/usr.bin/mg/util.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: util.c,v 1.45 2023/03/08 04:43:11 guenther Exp $	*/
+/*	$OpenBSD: util.c,v 1.46 2023/04/17 09:49:04 op Exp $	*/
 
 /* This file is in the public domain. */
 
@@ -100,11 +100,7 @@ getcolpos(struct mgwin *wp)
 
 	for (i = 0; i < wp->w_doto; ++i) {
 		c = lgetc(wp->w_dotp, i);
-		if (c == '\t'
-#ifdef NOTAB
-		    && !(wp->w_bufp->b_flag & BFNOTAB)
-#endif /* NOTAB */
-			) {
+		if (c == '\t') {
 			col |= 0x07;
 			col++;
 		} else if (ISCTRL(c) != FALSE)
@@ -336,7 +332,23 @@ deltrailwhite(int f, int n)
 	return (TRUE);
 }
 
+/*
+ * Raw indent routine.  Use spaces and tabs to fill the given number of
+ * cols, but respect no-tab-mode.
+ */
+int
+doindent(int cols)
+{
+	int n;
 
+	if (curbp->b_flag & BFNOTAB)
+		return (linsert(cols, ' '));
+	if ((n = cols / 8) != 0 && linsert(n, '\t') == FALSE)
+		return (FALSE);
+	if ((n = cols % 8) != 0 && linsert(n, ' ') == FALSE)
+		return (FALSE);
+	return (TRUE);
+}
 
 /*
  * Insert a newline, then enough tabs and spaces to duplicate the indentation
@@ -367,12 +379,8 @@ lfindent(int f, int n)
 			++nicol;
 		}
 		(void)delwhite(FFRAND, 1);
-		if (lnewline() == FALSE || ((
-#ifdef	NOTAB
-		    curbp->b_flag & BFNOTAB) ? linsert(nicol, ' ') == FALSE : (
-#endif /* NOTAB */
-		    ((i = nicol / 8) != 0 && linsert(i, '\t') == FALSE) ||
-		    ((i = nicol % 8) != 0 && linsert(i, ' ') == FALSE)))) {
+
+		if (lnewline() == FALSE || doindent(nicol) == FALSE) {
 			s = FALSE;
 			break;
 		}
@@ -389,7 +397,7 @@ lfindent(int f, int n)
 int
 indent(int f, int n)
 {
-	int soff, i;
+	int soff;
 
 	if (n < 0)
 		return (FALSE);
@@ -403,12 +411,7 @@ indent(int f, int n)
 	/* insert appropriate whitespace */
 	soff = curwp->w_doto;
 	(void)gotobol(FFRAND, 1);
-	if (
-#ifdef	NOTAB
-	    (curbp->b_flag & BFNOTAB) ? linsert(n, ' ') == FALSE :
-#endif /* NOTAB */
-	    (((i = n / 8) != 0 && linsert(i, '\t') == FALSE) ||
-	    ((i = n % 8) != 0 && linsert(i, ' ') == FALSE)))
+	if (doindent(n) == FALSE)
 		return (FALSE);
 
 	forwchar(FFRAND, soff);
@@ -464,7 +467,6 @@ backdel(int f, int n)
 	return (s);
 }
 
-#ifdef	NOTAB
 int
 space_to_tabstop(int f, int n)
 {
@@ -474,7 +476,6 @@ space_to_tabstop(int f, int n)
 		return (TRUE);
 	return (linsert((n << 3) - (curwp->w_doto & 7), ' '));
 }
-#endif /* NOTAB */
 
 /*
  * Move the dot to the first non-whitespace character of the current line.