From e2baa6523875aaa13b6b7db80b7985978b8ee492 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Ekl=C3=B6f?= <daniel@ekloef.se>
Date: Wed, 12 Apr 2023 16:39:54 +0200
Subject: [PATCH] =?UTF-8?q?render:=20ensure=20scroll=20region=E2=80=99s=20?=
 =?UTF-8?q?endpoint=20is=20valid=20after=20a=20window=20resize?=
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If we had a non-empty bottom scroll region, and the window was resized
to a smaller size, the scroll region was not reset correctly.

This led to a crash when scrolling the screen content.

Fix by making sure the scroll region’s endpoint is within range.
---
 CHANGELOG.md | 2 ++
 render.c     | 3 +--
 terminal.c   | 6 +++---
 3 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8500195b..ca98ed5c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -50,6 +50,8 @@
 ### Fixed
 
 * Incorrect icon in dock and window switcher on Gnome ([#1317][1317])
+* Crash when scrolling after resizing the window with non-zero
+  scrolling regions.
 
 [1317]: https://codeberg.org/dnkl/foot/issues/1317
 
diff --git a/render.c b/render.c
index f16898b4..d39c9489 100644
--- a/render.c
+++ b/render.c
@@ -4128,8 +4128,7 @@ maybe_resize(struct terminal *term, int width, int height, bool force)
 
     if (term->scroll_region.start >= term->rows)
         term->scroll_region.start = 0;
-
-    if (term->scroll_region.end >= old_rows)
+    if (term->scroll_region.end > term->rows)
         term->scroll_region.end = term->rows;
 
     term->render.last_cursor.row = NULL;
diff --git a/terminal.c b/terminal.c
index 04153513..2e62fbb7 100644
--- a/terminal.c
+++ b/terminal.c
@@ -2716,13 +2716,13 @@ term_scroll_partial(struct terminal *term, struct scroll_region region, int rows
         erase_line(term, row);
     }
 
-    term_damage_scroll(term, DAMAGE_SCROLL, region, rows);
-    term->grid->cur_row = grid_row(term->grid, term->grid->cursor.point.row);
-
 #if defined(_DEBUG)
     for (int r = 0; r < term->rows; r++)
         xassert(grid_row(term->grid, r) != NULL);
 #endif
+
+    term_damage_scroll(term, DAMAGE_SCROLL, region, rows);
+    term->grid->cur_row = grid_row(term->grid, term->grid->cursor.point.row);
 }
 
 void