Prevent negative arguments to the .ll request from causing integer

underflow.  Found while preparing an audit of termp.rmargin.

Overflow can also happen, but i see no sane way to deal with it,
so just let it happen.  It doesn't happen for any sane input anyway,
groff behaviour is undefined, and the resulting values are legal,
even though they are useless.

2 files changed, 10 insertions, 6 deletions

diff --git a/term_ascii.c b/term_ascii.c
index 9b5921ff..94be3597 100644
--- a/term_ascii.c
+++ b/term_ascii.c
@@ -159,12 +159,14 @@ ascii_setwidth(struct termp *p, int iop, size_t width)
 {
 
 	p->rmargin = p->defrmargin;
-	if (0 < iop)
+	if (iop > 0)
 		p->defrmargin += width;
-	else if (0 > iop)
+	else if (iop == 0)
+		p->defrmargin = width ? width : p->lastrmargin;
+	else if (p->defrmargin > width)
 		p->defrmargin -= width;
 	else
-		p->defrmargin = width ? width : p->lastrmargin;
+		p->defrmargin = 0;
 	p->lastrmargin = p->rmargin;
 	p->rmargin = p->maxrmargin = p->defrmargin;
 }
diff --git a/term_ps.c b/term_ps.c
index f1129c2d..344db82f 100644
--- a/term_ps.c
+++ b/term_ps.c
@@ -635,12 +635,14 @@ ps_setwidth(struct termp *p, int iop, size_t width)
 	size_t	 lastwidth;
 
 	lastwidth = p->ps->width;
-	if (0 < iop)
+	if (iop > 0)
 		p->ps->width += width;
-	else if (0 > iop)
+	else if (iop == 0)
+		p->ps->width = width ? width : p->ps->lastwidth;
+	else if (p->ps->width > width)
 		p->ps->width -= width;
 	else
-		p->ps->width = width ? width : p->ps->lastwidth;
+		p->ps->width = 0;
 	p->ps->lastwidth = lastwidth;
 }