[gnome-panel] [panel] Fix crashes in various conditions with the new randr code

[Vincent Untz <vuntz src gnome org>]

commit 66b8e290bd0b767183cba583917907940b5b425a
Author: Vincent Untz <vuntz gnome org>
Date:   Tue Oct 6 12:47:52 2009 +0200

    [panel] Fix crashes in various conditions with the new randr code
    
    If nothing had probed the randr screen resources before us and the X
    server is supporting randr 1.3, then we got no output, and therefore no
    monitor. The fix here is to actively probe for resources if we detect
    this case. See https://bugzilla.gnome.org/show_bug.cgi?id=597101
    
    Also, in some cases, all outputs appear disconnected. See
    https://bugzilla.novell.com/show_bug.cgi?id=543876
    
    To be completely on the safe side, if we get no monitor information from
    randr, even if it is successful, we fallback to the GTK+ method.

 gnome-panel/panel-multiscreen.c |   35 ++++++++++++++++++++++++++++++-----
 1 files changed, 30 insertions(+), 5 deletions(-)
---
diff --git a/gnome-panel/panel-multiscreen.c b/gnome-panel/panel-multiscreen.c
index 8a05221..4ed76ae 100644
--- a/gnome-panel/panel-multiscreen.c
+++ b/gnome-panel/panel-multiscreen.c
@@ -136,9 +136,17 @@ panel_multiscreen_get_randr_monitors_for_screen (GdkScreen     *screen,
 	xroot = GDK_WINDOW_XWINDOW (gdk_screen_get_root_window (screen));
 
 #if (RANDR_MAJOR > 1 || (RANDR_MAJOR == 1 && RANDR_MINOR >= 3))
-	if (have_randr_1_3)
+	if (have_randr_1_3) {
 		resources = XRRGetScreenResourcesCurrent (xdisplay, xroot);
-	else
+		if (resources->noutput == 0) {
+			/* This might happen if nothing tried to get randr
+			 * resources from the server before, so we need an
+			 * active probe. See comment #27 in
+			 * https://bugzilla.gnome.org/show_bug.cgi?id=597101 */
+			XRRFreeScreenResources (resources);
+			resources = XRRGetScreenResources (xdisplay, xroot);
+		}
+	} else
 		resources = XRRGetScreenResources (xdisplay, xroot);
 #else
 	resources = XRRGetScreenResources (xdisplay, xroot);
@@ -205,6 +213,17 @@ panel_multiscreen_get_randr_monitors_for_screen (GdkScreen     *screen,
 		return FALSE;
 	}
 
+	if (geometries->len == 0) {
+		/* This can happen in at least one case:
+		 * https://bugzilla.novell.com/show_bug.cgi?id=543876 where all
+		 * monitors appear disconnected (possibly because the  screen
+		 * is behing a KVM switch) -- see comment #8.
+		 * There might be other cases too, so we stay on the safe side.
+		 */
+		g_array_free (geometries, TRUE);
+		return FALSE;
+	}
+
 	*monitors_ret = geometries->len;
 	*geometries_ret = (GdkRectangle *) g_array_free (geometries, FALSE);
 
@@ -238,9 +257,15 @@ panel_multiscreen_get_raw_monitors_for_screen (GdkScreen     *screen,
 					       int           *monitors_ret,
 					       GdkRectangle **geometries_ret)
 {
-	if (panel_multiscreen_get_randr_monitors_for_screen (screen,
-							     monitors_ret,
-							     geometries_ret))
+	gboolean res;
+
+	*monitors_ret = 0;
+	*geometries_ret = NULL;
+
+	res = panel_multiscreen_get_randr_monitors_for_screen (screen,
+							       monitors_ret,
+							       geometries_ret);
+	if (res && *monitors_ret > 0)
 		return;
 
 	panel_multiscreen_get_gdk_monitors_for_screen (screen,