From ef62f27d014f39ece5e16500f0a58cdf13c32030 Mon Sep 17 00:00:00 2001
From: Ingo Schwarze <schwarze@openbsd.org>
Date: Sun, 19 Aug 2018 17:46:14 +0000
Subject: Mostly complete implementation of the 'c' (character available) roff
 conditional, except that the .char request still isn't supported and that
 behaviour differs from groff in many edge cases. But at least valid character
 names and numbers are now distinguished from invalid ones. This also fixes
 the bug that parsing of the 'c' conditional was incomplete, which resulted in
 leaking the tested character to the input parser at the beginning of the body
 when the condition was inverted.

---
 roff.c | 49 ++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 44 insertions(+), 5 deletions(-)

(limited to 'roff.c')

diff --git a/roff.c b/roff.c
index 0c733006..9b3002ca 100644
--- a/roff.c
+++ b/roff.c
@@ -1,4 +1,4 @@
-/*	$Id: roff.c,v 1.335 2018/08/18 22:05:43 schwarze Exp $ */
+/*	$Id: roff.c,v 1.336 2018/08/19 17:46:14 schwarze Exp $ */
 /*
  * Copyright (c) 2008-2012, 2014 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2010-2015, 2017, 2018 Ingo Schwarze <schwarze@openbsd.org>
@@ -2168,9 +2168,10 @@ out:
 static int
 roff_evalcond(struct roff *r, int ln, char *v, int *pos)
 {
-	char	*cp, *name;
-	size_t	 sz;
-	int	 deftype, number, savepos, istrue, wanttrue;
+	const char	*start, *end;
+	char		*cp, *name;
+	size_t		 sz;
+	int		 deftype, len, number, savepos, istrue, wanttrue;
 
 	if ('!' == v[*pos]) {
 		wanttrue = 0;
@@ -2185,12 +2186,50 @@ roff_evalcond(struct roff *r, int ln, char *v, int *pos)
 	case 'o':
 		(*pos)++;
 		return wanttrue;
-	case 'c':
 	case 'e':
 	case 't':
 	case 'v':
 		(*pos)++;
 		return !wanttrue;
+	case 'c':
+		do {
+			(*pos)++;
+		} while (v[*pos] == ' ');
+
+		/*
+		 * Quirk for groff compatibility:
+		 * The horizontal tab is neither available nor unavailable.
+		 */
+
+		if (v[*pos] == '\t') {
+			(*pos)++;
+			return 0;
+		}
+
+		/* Printable ASCII characters are available. */
+
+		if (v[*pos] != '\\') {
+			(*pos)++;
+			return wanttrue;
+		}
+
+		end = v + ++*pos;
+		switch (mandoc_escape(&end, &start, &len)) {
+		case ESCAPE_SPECIAL:
+			istrue = mchars_spec2cp(start, len) != -1;
+			break;
+		case ESCAPE_UNICODE:
+			istrue = 1;
+			break;
+		case ESCAPE_NUMBERED:
+			istrue = mchars_num2char(start, len) != -1;
+			break;
+		default:
+			istrue = !wanttrue;
+			break;
+		}
+		*pos = end - v;
+		return istrue == wanttrue;
 	case 'd':
 	case 'r':
 		cp = v + *pos + 1;
-- 
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