===================================================================
RCS file: /cvs/mandoc/roff.c,v
retrieving revision 1.381
retrieving revision 1.384
diff -u -p -r1.381 -r1.384
--- mandoc/roff.c	2022/04/13 13:19:34	1.381
+++ mandoc/roff.c	2022/04/28 16:21:10	1.384
@@ -1,4 +1,4 @@
-/* $Id: roff.c,v 1.381 2022/04/13 13:19:34 schwarze Exp $ */
+/* $Id: roff.c,v 1.384 2022/04/28 16:21:10 schwarze Exp $ */
 /*
  * Copyright (c) 2010-2015, 2017-2022 Ingo Schwarze <schwarze@openbsd.org>
  * Copyright (c) 2008-2012, 2014 Kristaps Dzonsons <kristaps@bsd.lv>
@@ -227,6 +227,7 @@ static	int		 roff_line_ignore(ROFF_ARGS);
 static	void		 roff_man_alloc1(struct roff_man *);
 static	void		 roff_man_free1(struct roff_man *);
 static	int		 roff_manyarg(ROFF_ARGS);
+static	int		 roff_mc(ROFF_ARGS);
 static	int		 roff_noarg(ROFF_ARGS);
 static	int		 roff_nop(ROFF_ARGS);
 static	int		 roff_nr(ROFF_ARGS);
@@ -379,7 +380,7 @@ static	struct roffmac	 roffs[TOKEN_NONE] = {
 	{ roff_noarg, NULL, NULL, 0 },  /* fi */
 	{ roff_onearg, NULL, NULL, 0 },  /* ft */
 	{ roff_onearg, NULL, NULL, 0 },  /* ll */
-	{ roff_onearg, NULL, NULL, 0 },  /* mc */
+	{ roff_mc, NULL, NULL, 0 },  /* mc */
 	{ roff_noarg, NULL, NULL, 0 },  /* nf */
 	{ roff_onearg, NULL, NULL, 0 },  /* po */
 	{ roff_onearg, NULL, NULL, 0 },  /* rj */
@@ -2433,9 +2434,11 @@ roff_cond_sub(ROFF_ARGS)
 			}
 		}
 	} else if (t != TOKEN_NONE &&
-	    (rr || roffs[t].flags & ROFFMAC_STRUCT))
+	    (rr || roffs[t].flags & ROFFMAC_STRUCT)) {
 		irc |= (*roffs[t].proc)(r, t, buf, ln, ppos, pos, offs);
-	else
+		if (irc & ROFF_WHILE)
+			irc &= ~(ROFF_LOOPCONT | ROFF_LOOPEXIT);
+	} else
 		irc |= rr ? ROFF_CONT : ROFF_IGN;
 	return irc;
 }
@@ -3730,6 +3733,54 @@ roff_eo(ROFF_ARGS)
 }
 
 static int
+roff_mc(ROFF_ARGS)
+{
+	struct roff_node	*n;
+	char			*cp;
+
+	/* Parse the first argument. */
+
+	cp = buf->buf + pos;
+	if (*cp != '\0')
+		cp++;
+	if (buf->buf[pos] == '\\') {
+		switch (mandoc_escape((const char **)&cp, NULL, NULL)) {
+		case ESCAPE_SPECIAL:
+		case ESCAPE_UNICODE:
+		case ESCAPE_NUMBERED:
+			break;
+		default:
+			*cp = '\0';
+			mandoc_msg(MANDOCERR_MC_ESC, ln, pos,
+			    "mc %s", buf->buf + pos);
+			buf->buf[pos] = '\0';
+			break;
+		}
+	}
+
+	/* Ignore additional arguments. */
+
+	while (*cp == ' ')
+		*cp++ = '\0';
+	if (*cp != '\0') {
+		mandoc_msg(MANDOCERR_MC_DIST, ln, (int)(cp - buf->buf),
+		    "mc ... %s", cp);
+		*cp = '\0';
+	}
+
+	/* Create the .mc node. */
+
+	roff_elem_alloc(r->man, ln, ppos, tok);
+	n = r->man->last;
+	if (buf->buf[pos] != '\0')
+		roff_word_alloc(r->man, ln, pos, buf->buf + pos);
+	n->flags |= NODE_LINE | NODE_VALID | NODE_ENDED;
+	r->man->last = n;
+	r->man->next = ROFF_NEXT_SIBLING;
+	return ROFF_IGN;
+}
+
+static int
 roff_nop(ROFF_ARGS)
 {
 	while (buf->buf[pos] == ' ')
@@ -3870,8 +3921,9 @@ static int
 roff_shift(ROFF_ARGS)
 {
 	struct mctx	*ctx;
-	int		 levels, i;
+	int		 argpos, levels, i;
 
+	argpos = pos;
 	levels = 1;
 	if (buf->buf[pos] != '\0' &&
 	    roff_evalnum(r, ln, buf->buf, &pos, &levels, 0) == 0) {
@@ -3886,8 +3938,12 @@ roff_shift(ROFF_ARGS)
 	ctx = r->mstack + r->mstackpos;
 	if (levels > ctx->argc) {
 		mandoc_msg(MANDOCERR_SHIFT,
-		    ln, pos, "%d, but max is %d", levels, ctx->argc);
+		    ln, argpos, "%d, but max is %d", levels, ctx->argc);
 		levels = ctx->argc;
+	}
+	if (levels < 0) {
+		mandoc_msg(MANDOCERR_ARG_NEG, ln, argpos, "shift %d", levels);
+		levels = 0;
 	}
 	if (levels == 0)
 		return ROFF_IGN;