From c9adab2527a57f9d2ca4bc85bffe2c92f368c22f Mon Sep 17 00:00:00 2001
From: Karl Heuer <kwzh@gnu.org>
Date: Wed, 13 Dec 1995 02:22:47 +0000
Subject: [PATCH] (IT_set_terminal_modes): Save screen color attribute byte at
 startup, write saved screen dimensions to termscript file.
 (IT_reset_terminal_modes): When restoring startup screen contents, only
 restore as much as was saved, and only as much as the screen dimensions on
 exit can hold.  Blank the rest with the background color saved at startup. 
 Write restored screen dimensions to termscript file.

---
 src/msdos.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 50 insertions(+), 5 deletions(-)

diff --git a/src/msdos.c b/src/msdos.c
index 4d3c4028117..cff45ca3f94 100644
--- a/src/msdos.c
+++ b/src/msdos.c
@@ -249,6 +249,7 @@ static int startup_screen_size_X;
 static int startup_screen_size_Y;
 static int startup_pos_X;
 static int startup_pos_Y;
+static unsigned char startup_screen_attrib;
 
 static int term_setup_done;
 
@@ -554,12 +555,14 @@ IT_set_terminal_modes (void)
   
   startup_screen_size_X = screen_size_X;
   startup_screen_size_Y = screen_size_Y;
+  startup_screen_attrib = ScreenAttrib;
 
   ScreenGetCursor (&startup_pos_Y, &startup_pos_X);
   ScreenRetrieve (startup_screen_buffer = xmalloc (screen_size * 2));
 
   if (termscript)
-    fprintf (termscript, "<SCREEN SAVED>\n");
+    fprintf (termscript, "<SCREEN SAVED (dimensions=%dx%d)>\n",
+             screen_size_X, screen_size_Y);
 }
 
 /*
@@ -570,6 +573,15 @@ IT_set_terminal_modes (void)
 static
 IT_reset_terminal_modes (void)
 {
+  int display_row_start = (int) ScreenPrimary;
+  int saved_row_len     = startup_screen_size_X * 2;
+  int update_row_len    = ScreenCols () * 2;
+  int current_rows      = ScreenRows ();
+  int to_next_row       = update_row_len;
+  unsigned char *saved_row = startup_screen_buffer;
+  int cursor_pos_X = ScreenCols () - 1;
+  int cursor_pos_Y = ScreenRows () - 1;
+
   if (termscript)
     fprintf (termscript, "\n<RESET_TERM>");
 
@@ -578,12 +590,45 @@ IT_reset_terminal_modes (void)
   if (!term_setup_done)
     return;
   
-  ScreenUpdate (startup_screen_buffer);
-  ScreenSetCursor (startup_pos_Y, startup_pos_X);
-  xfree (startup_screen_buffer);
+  mouse_off ();
+ 
+  /* We have a situation here.
+     We cannot just do ScreenUpdate(startup_screen_buffer) because
+     the luser could have changed screen dimensions inside Emacs
+     and failed (or didn't want) to restore them before killing
+     Emacs.  ScreenUpdate() uses the *current* screen dimensions and
+     thus will happily use memory outside what was allocated for
+     `startup_screen_buffer'.
+     Thus we only restore as much as the current screen dimensions
+     can hold, and clear the rest (if the saved screen is smaller than
+     the current) with the color attribute saved at startup.  The cursor
+     is also restored within the visible dimensions.  */
+
+  ScreenAttrib = startup_screen_attrib;
+  ScreenClear ();
+
+  if (update_row_len > saved_row_len)
+    update_row_len = saved_row_len;
+  if (current_rows > startup_screen_size_Y)
+    current_rows = startup_screen_size_Y;
 
   if (termscript)
-    fprintf (termscript, "<SCREEN RESTORED>\n");
+    fprintf (termscript, "<SCREEN RESTORED (dimensions=%dx%d)>\n",
+             update_row_len / 2, current_rows);
+
+  while (current_rows--)
+    {
+      dosmemput (saved_row, update_row_len, display_row_start);
+      saved_row         += saved_row_len;
+      display_row_start += to_next_row;
+    }
+  if (startup_pos_X < cursor_pos_X)
+    cursor_pos_X = startup_pos_X;
+  if (startup_pos_Y < cursor_pos_Y)
+    cursor_pos_Y = startup_pos_Y;
+
+  ScreenSetCursor (cursor_pos_Y, cursor_pos_X);
+  xfree (startup_screen_buffer);
 
   term_setup_done = 0;
 }
-- 
2.39.2