correct handling of blank lines after \c

3 files changed, 55 insertions, 17 deletions

diff --git a/usr.bin/mandoc/man.c b/usr.bin/mandoc/man.c
index ba7cdd8d386..c6ef632a5f7 100644
--- a/usr.bin/mandoc/man.c
+++ b/usr.bin/mandoc/man.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: man.c,v 1.122 2017/06/03 15:54:09 schwarze Exp $ */
+/*	$OpenBSD: man.c,v 1.123 2017/06/17 13:05:47 schwarze Exp $ */
 /*
  * Copyright (c) 2008, 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2013, 2014, 2015, 2017 Ingo Schwarze <schwarze@openbsd.org>
@@ -74,6 +74,8 @@ static int
 man_ptext(struct roff_man *man, int line, char *buf, int offs)
 {
 	int		 i;
+	const char 	*cp, *sp;
+	char		*ep;
 
 	/* Literal free-form text whitespace is preserved. */
 
@@ -87,19 +89,36 @@ man_ptext(struct roff_man *man, int line, char *buf, int offs)
 		/* Skip leading whitespace. */ ;
 
 	/*
-	 * Blank lines are ignored in next line scope and right
-	 * after headings but add a single vertical space elsewhere.
+	 * Blank lines are ignored in next line scope
+	 * and right after headings and cancel preceding \c,
+	 * but add a single vertical space elsewhere.
 	 */
 
 	if (buf[i] == '\0') {
-		if (man->flags & (MAN_ELINE | MAN_BLINE))
+		if (man->flags & (MAN_ELINE | MAN_BLINE)) {
 			mandoc_msg(MANDOCERR_BLK_BLANK, man->parse,
 			    line, 0, NULL);
-		else if (man->last->tok != MAN_SH &&
-		    man->last->tok != MAN_SS) {
-			roff_elem_alloc(man, line, offs, ROFF_sp);
-			man->next = ROFF_NEXT_SIBLING;
+			return 1;
 		}
+		if (man->last->tok == MAN_SH || man->last->tok == MAN_SS)
+			return 1;
+		switch (man->last->type) {
+		case ROFFT_TEXT:
+			sp = man->last->string;
+			cp = ep = strchr(sp, '\0') - 2;
+			if (cp < sp || cp[0] != '\\' || cp[1] != 'c')
+				break;
+			while (cp > sp && cp[-1] == '\\')
+				cp--;
+			if ((ep - cp) % 2)
+				break;
+			*ep = '\0';
+			return 1;
+		default:
+			break;
+		}
+		roff_elem_alloc(man, line, offs, ROFF_sp);
+		man->next = ROFF_NEXT_SIBLING;
 		return 1;
 	}
 
diff --git a/usr.bin/mandoc/man_term.c b/usr.bin/mandoc/man_term.c
index c284e3f45be..7b34366e6a0 100644
--- a/usr.bin/mandoc/man_term.c
+++ b/usr.bin/mandoc/man_term.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: man_term.c,v 1.159 2017/06/17 01:26:48 schwarze Exp $ */
+/*	$OpenBSD: man_term.c,v 1.160 2017/06/17 13:05:47 schwarze Exp $ */
 /*
  * Copyright (c) 2008-2012 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2010-2015, 2017 Ingo Schwarze <schwarze@openbsd.org>
@@ -870,7 +870,10 @@ print_man_node(DECL_ARGS)
 		 * before printing the line's data.
 		 */
 		if (*n->string == '\0') {
-			term_vspace(p);
+			if (p->flags & TERMP_NONEWLINE)
+				term_newln(p);
+			else
+				term_vspace(p);
 			return;
 		} else if (*n->string == ' ' && n->flags & NODE_LINE &&
 		    (p->flags & TERMP_NONEWLINE) == 0)
diff --git a/usr.bin/mandoc/mdoc.c b/usr.bin/mandoc/mdoc.c
index bc0ec426533..869f4a9a91b 100644
--- a/usr.bin/mandoc/mdoc.c
+++ b/usr.bin/mandoc/mdoc.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mdoc.c,v 1.155 2017/06/07 20:58:36 schwarze Exp $ */
+/*	$OpenBSD: mdoc.c,v 1.156 2017/06/17 13:05:47 schwarze Exp $ */
 /*
  * Copyright (c) 2008, 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2010, 2012-2017 Ingo Schwarze <schwarze@openbsd.org>
@@ -177,6 +177,7 @@ static int
 mdoc_ptext(struct roff_man *mdoc, int line, char *buf, int offs)
 {
 	struct roff_node *n;
+	const char	 *cp, *sp;
 	char		 *c, *ws, *end;
 
 	n = mdoc->last;
@@ -242,15 +243,30 @@ mdoc_ptext(struct roff_man *mdoc, int line, char *buf, int offs)
 		mandoc_msg(MANDOCERR_SPACE_EOL, mdoc->parse,
 		    line, (int)(ws-buf), NULL);
 
+	/*
+	 * Blank lines are allowed in no-fill mode
+	 * and cancel preceding \c,
+	 * but add a single vertical space elsewhere.
+	 */
+
 	if (buf[offs] == '\0' && ! (mdoc->flags & MDOC_LITERAL)) {
+		switch (mdoc->last->type) {
+		case ROFFT_TEXT:
+			sp = mdoc->last->string;
+			cp = end = strchr(sp, '\0') - 2;
+			if (cp < sp || cp[0] != '\\' || cp[1] != 'c')
+				break;
+			while (cp > sp && cp[-1] == '\\')
+				cp--;
+			if ((end - cp) % 2)
+				break;
+			*end = '\0';
+			return 1;
+		default:
+			break;
+		}
 		mandoc_msg(MANDOCERR_FI_BLANK, mdoc->parse,
 		    line, (int)(c - buf), NULL);
-
-		/*
-		 * Insert a `sp' in the case of a blank line.  Technically,
-		 * blank lines aren't allowed, but enough manuals assume this
-		 * behaviour that we want to work around it.
-		 */
 		roff_elem_alloc(mdoc, line, offs, ROFF_sp);
 		mdoc->last->flags |= NODE_VALID | NODE_ENDED;
 		mdoc->next = ROFF_NEXT_SIBLING;