From b81fb73c3751ecbda4983ed83333ea7a88c077fb Mon Sep 17 00:00:00 2001
From: Wez Furlong <wez@wezfurlong.org>
Date: Sat, 24 Feb 2018 20:59:44 -0800
Subject: [PATCH] Really avoid underflow with `apt` scrolling

I thought I took care of this in 7c0536f9a36aca1d0a9af018b56dd435722cd31d,
but I misunderstood how saturating_sub works.  I still need to clamp
it within range.
---
 term/src/csi.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/term/src/csi.rs b/term/src/csi.rs
index 7f4585535..94c5784f8 100644
--- a/term/src/csi.rs
+++ b/term/src/csi.rs
@@ -369,8 +369,8 @@ impl<'a> CSIParser<'a> {
             &[top, bottom] => {
                 self.advance_by(2, params);
                 Some(CSIAction::SetScrollingRegion {
-                    top: top.saturating_sub(1),
-                    bottom: bottom.saturating_sub(1),
+                    top: top.saturating_sub(1).max(0),
+                    bottom: bottom.saturating_sub(1).max(0),
                 })
             }
             &[] => {