vnc: add magic cookie to VncState

Set magic cookie on initialization.  Clear on cleanup.  Sprinkle a bunch
of assert()s checking the cookie, to verify the pointer is valid.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Message-id: 20180507102254.12107-1-kraxel@redhat.com

1 files changed, 3 insertions, 0 deletions

diff --git a/ui/vnc.h b/ui/vnc.h
index 7b29def77d..762632929b 100644
--- a/ui/vnc.h
+++ b/ui/vnc.h
@@ -255,8 +255,11 @@ typedef enum {
     VNC_STATE_UPDATE_FORCE,
 } VncStateUpdate;
 
+#define VNC_MAGIC ((uint64_t)0x05b3f069b3d204bb)
+
 struct VncState
 {
+    uint64_t magic;
     QIOChannelSocket *sioc; /* The underlying socket */
     QIOChannel *ioc; /* The channel currently used for I/O */
     guint ioc_tag;