From 7d11b6e3c1a1456e15565f806de0c5be09de812b Mon Sep 17 00:00:00 2001
From: schwarze <schwarze@openbsd.org>
Date: Tue, 28 Sep 2021 17:06:17 +0000
Subject: [PATCH] Revert part of the previous diff to fix a regression (another
 endless loop) reported by Michael <Stapelberg at Debian> in the Linux md(4)
 manual.

The reason the colwidth[] array is needed is not that it stores widths
different from those in tbl->cols[].width, but that only part of the
columns participate in the comparisons, i.e. only those intersecting
at least one span the still requires width distribution.
---
 usr.bin/mandoc/out.c | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/usr.bin/mandoc/out.c b/usr.bin/mandoc/out.c
index 6d73c08a255..28dcc25a278 100644
--- a/usr.bin/mandoc/out.c
+++ b/usr.bin/mandoc/out.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: out.c,v 1.54 2021/09/07 17:05:30 schwarze Exp $ */
+/*	$OpenBSD: out.c,v 1.55 2021/09/28 17:06:17 schwarze Exp $ */
 /*
  * Copyright (c) 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2011, 2014, 2015, 2017, 2018, 2019, 2021
@@ -121,6 +121,7 @@ tblcalc(struct rofftbl *tbl, const struct tbl_span *sp_first,
 	const struct tbl_dat	*dp;
 	struct roffcol		*col;
 	struct tbl_colgroup	*first_group, **gp, *g;
+	size_t			*colwidth;
 	size_t			 ewidth, min1, min2, wanted, width, xwidth;
 	int			 done, icol, maxcol, necol, nxcol, quirkcol;
 
@@ -254,8 +255,20 @@ tblcalc(struct rofftbl *tbl, const struct tbl_span *sp_first,
 			gp = &(*gp)->next;
 	}
 
+	colwidth = mandoc_reallocarray(NULL, maxcol + 1, sizeof(*colwidth));
 	while (first_group != NULL) {
 
+		/*
+		 * Rebuild the array of the widths of all columns
+		 * participating in spans that require expansion.
+		 */
+
+		for (icol = 0; icol <= maxcol; icol++)
+			colwidth[icol] = SIZE_MAX;
+		for (g = first_group; g != NULL; g = g->next)
+			for (icol = g->startcol; icol <= g->endcol; icol++)
+				colwidth[icol] = tbl->cols[icol].width;
+
 		/*
 		 * Find the smallest and second smallest column width
 		 * among the columns which may need expamsion.
@@ -263,7 +276,7 @@ tblcalc(struct rofftbl *tbl, const struct tbl_span *sp_first,
 
 		min1 = min2 = SIZE_MAX;
 		for (icol = 0; icol <= maxcol; icol++) {
-			width = tbl->cols[icol].width;
+			width = colwidth[icol];
 			if (min1 > width) {
 				min2 = min1;
 				min1 = width;
@@ -281,7 +294,7 @@ tblcalc(struct rofftbl *tbl, const struct tbl_span *sp_first,
 		for (g = first_group; g != NULL; g = g->next) {
 			necol = 0;
 			for (icol = g->startcol; icol <= g->endcol; icol++)
-				if (tbl->cols[icol].width == min1)
+				if (colwidth[icol] == min1)
 					necol++;
 			if (necol == 0)
 				continue;
@@ -298,7 +311,7 @@ tblcalc(struct rofftbl *tbl, const struct tbl_span *sp_first,
 		while ((g = *gp) != NULL) {
 			done = 0;
 			for (icol = g->startcol; icol <= g->endcol; icol++) {
-				if (tbl->cols[icol].width != min1)
+				if (colwidth[icol] != min1)
 					continue;
 				if (g->wanted <= wanted - min1) {
 					tbl->cols[icol].width += g->wanted;
@@ -315,6 +328,7 @@ tblcalc(struct rofftbl *tbl, const struct tbl_span *sp_first,
 				gp = &(*gp)->next;
 		}
 	}
+	free(colwidth);
 
 	/*
 	 * Align numbers with text.
-- 
2.20.1