From: Chong Yidong <cyd@stupidchicken.com>
Date: Sun, 5 Dec 2010 00:32:32 +0000 (-0500)
Subject: Avoid infloop when scrolling conservatively (Bug#7537).
X-Git-Tag: emacs-pretest-23.2.91~29
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=77f1ed6cb665b06fc1cdd4e2707932f0b499d481;p=emacs.git

Avoid infloop when scrolling conservatively (Bug#7537).

* src/xdisp.c (try_scrolling): Avoid infloop if the first line is obscured
due to a vscroll (Bug#7537).
---

diff --git a/src/ChangeLog b/src/ChangeLog
index 025161cc395..95f7039eaf7 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,8 @@
+2010-12-05  Chong Yidong  <cyd@stupidchicken.com>
+
+	* xdisp.c (try_scrolling): Avoid infloop if the first line is
+	obscured due to a vscroll (Bug#7537).
+
 2010-12-02  Jan Djärv  <jhd@zeplinf.localdomain>
 
 	* nsterm.h (FRAME_NS_TOOLBAR_HEIGHT): Rename to FRAME_TOOLBAR_HEIGHT.
diff --git a/src/xdisp.c b/src/xdisp.c
index a416c8ff435..dbe3e443c67 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -12759,7 +12759,11 @@ try_scrolling (window, just_this_one_p, scroll_conservatively,
 
       /* If cursor ends up on a partially visible line,
 	 treat that as being off the bottom of the screen.  */
-      if (! cursor_row_fully_visible_p (w, extra_scroll_margin_lines <= 1, 0))
+      if (! cursor_row_fully_visible_p (w, extra_scroll_margin_lines <= 1, 0)
+	  /* It's possible that the cursor is on the first line of the
+	     buffer, which is partially obscured due to a vscroll
+	     (Bug#7537).  In that case, avoid looping forever . */
+	  && extra_scroll_margin_lines < w->desired_matrix->nrows - 1)
 	{
 	  clear_glyph_matrix (w->desired_matrix);
 	  ++extra_scroll_margin_lines;