[gtk-vnc] Avoid crash in motion event & vnc_display_get_pixbuf

[Daniel P. Berrange <dberrange src gnome org>]

commit f23f0ebf1b659208d5036e10ab1f32249a2e1a4c
Author: Daniel P. Berrange <dan berrange com>
Date:   Mon Nov 22 21:18:29 2010 +0000

    Avoid crash in motion event & vnc_display_get_pixbuf
    
    If a mouse event occurs before a connection completes setup
    priv->fb will be NULL and a crash can occur. Likewise if
    vnc_display_get_pixbuf() is called before priv->fb is set,
    then a crash occurs. Add checks for NULL in both cases

 src/vncdisplay.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)
---
diff --git a/src/vncdisplay.c b/src/vncdisplay.c
index 55fbcf4..0b7e800 100644
--- a/src/vncdisplay.c
+++ b/src/vncdisplay.c
@@ -557,6 +557,9 @@ static gboolean motion_event(GtkWidget *widget, GdkEventMotion *motion)
 	if (priv->conn == NULL || !vnc_connection_is_initialized(priv->conn))
 		return FALSE;
 
+	if (!priv->fb)
+		return FALSE;
+
 	fbw = vnc_framebuffer_get_width(VNC_FRAMEBUFFER(priv->fb));
 	fbh = vnc_framebuffer_get_height(VNC_FRAMEBUFFER(priv->fb));
 
@@ -2050,6 +2053,9 @@ GdkPixbuf *vnc_display_get_pixbuf(VncDisplay *obj)
 	    !vnc_connection_is_initialized(priv->conn))
 		return NULL;
 
+	if (!priv->fb)
+		return NULL;
+
 	fb = VNC_FRAMEBUFFER(priv->fb);
 	surface = vnc_cairo_framebuffer_get_surface(priv->fb);
 	content = cairo_surface_get_content(surface) | CAIRO_CONTENT_COLOR;