From 0aad4fd779782407854b0e588c472631196d3e9f Mon Sep 17 00:00:00 2001
From: Josh Holtrop <jholtrop@gmail.com>
Date: Sun, 24 Jul 2016 12:28:58 -0400
Subject: [PATCH] GUI: avoid segfault when trying to scroll an empty buffer

---
 src/gui/Window.cc | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/gui/Window.cc b/src/gui/Window.cc
index 330beef..a7fef76 100644
--- a/src/gui/Window.cc
+++ b/src/gui/Window.cc
@@ -223,7 +223,8 @@ void Window::handle_event(SDL_Event & event)
 
 void Window::scroll_down()
 {
-    if (m_start_piece->next != m_buffer->piece_table->end_descriptor)
+    if ((m_start_piece != m_buffer->piece_table->end_descriptor) &&
+        (m_start_piece->next != m_buffer->piece_table->end_descriptor))
     {
         m_start_piece = m_start_piece->next;
         redraw();
@@ -232,7 +233,8 @@ void Window::scroll_down()
 
 void Window::scroll_up()
 {
-    if (m_start_piece->prev != m_buffer->piece_table->start_descriptor)
+    if ((m_start_piece != m_buffer->piece_table->start_descriptor) &&
+        (m_start_piece->prev != m_buffer->piece_table->start_descriptor))
     {
         m_start_piece = m_start_piece->prev;
         redraw();